Patent Publication Number: US-7214377-B2

Title: Method to prepare compositions comprising yeast treated with electromagnetic energy

Description:
1. FIELD OF THE INVENTION 
     The invention relates to oral compositions comprising yeast cells that can produce a healthful benefit in a subject inflicted with leukemia. The invention also relates to methods for manufacturing the oral compositions and methods of use thereof. 
     2. BACKGROUND OF THE INVENTION 
     2.1 Leukemia 
     Leukemia, which is the uncontrolled proliferation of blood cells, constitutes about 2% of adult cancers. The incidence rate is 2.5 out of 100,000 people. Each year, nearly 27,000 adults and more than 2,000 children in the United States are diagnosed with leukemia. In most types of leukemia, the abnormal cells are white blood cells. The leukemia cells usually look different from normal blood cells, and they do not function properly. 
     People with leukemia have a weakened immune system. They often get infections and have fevers. Also, people with leukemia often have less than the normal amount of healthy red blood cells and platelets. As a result, there are not enough red blood cells to carry oxygen through the body (a condition called anemia) and the patients look pale and are often weak and tired. Other common symptoms of leukemia include loss of appetite, loss of weight, swollen or tender lymph nodes, liver, or spleen, easy bleeding or bruising, tiny red spots (called petechiae) under the skin, swollen or bleeding gums, sweating (especially at night), and bone or joint pain. Because the abnormal cells may gradually collect in various parts of the body (e.g., the central nervous system, the digestive tract, kidneys, lungs, eyes, etc.), leukemia may cause nonspecific signs of headaches, vomiting, confusion, loss of muscle control, and seizures. The most efficient way to diagnose leukemia is by blood test (CBC or WBC). Bone marrow aspiration also shows evidence of leukemia cells. 
     The cause of leukemia is unknown. However, radiation, some toxins such as benzene, and some chemotherapy agents (drugs known as alkylating agents) used in patients treated for Hodgkin&#39;s disease, multiple myeloma, breast, ovarian, and gastrointestinal cancers are thought to cause leukemia. Abnormalities in chromosomes may also play a role in the development of acute leukemia. Immunosuppression following organ transplantation, and blood disorders such as polycythemia vera, essential thrombocythemia, and refractory anemia are also highly associated with the occurrence of leukemia. 
     Leukemia is either acute or chronic. In acute leukemia, the abnormal blood cells are immature cells that remain very immature and cannot carry out their normal functions. The number of blasts increases rapidly, and the disease gets worse quickly. In chronic leukemia, some blast cells are present, but in general, these cells are more mature and can carry out some of their normal functions. Also, the number of blasts increases less rapidly than in acute leukemia. As a result, chronic leukemia gets worse gradually. Leukemia can arise in either of the two main types of white blood cells—lymphoid cells (lymphocytic leukemia) or myeloid cells (myeloid or myelogenous leukemia). The most common types of leukemia are (1) acute lymphocytic leukemia (ALL), (2) acute myeloid leukemia (AML), (3) chronic lymphocytic leukemia (CLL), (4) chronic myeloid leukemia (CML), and (5) hairy cell leukemia. The French-American-British (FAB) classification divides leukemia based on morphologic, histochemical, and immunologic findings. 
     Treatment for leukemia is complex. Treatment of leukemia depends on the type of leukemia, the stage, the extent of the disease, whether the leukemia has been treated before, and also the age, symptoms and general health of the patient. Most people with leukemia are treated with chemotherapy. Some may also choose to have radiation therapy and/or bone marrow transplantation (BMT) or biological therapy. In some cases, surgery to remove the spleen (an operation called a splenectomy) may be part of the treatment plan. In addition, supportive care is often included by isolating patients to prevent invention, giving antibiotics to treat infection, and transfusing patients to control bleeding and red blood cells to combat anemia. 
     Radiation has not been highly effective as the primary treatment for leukemia, though it has been used as palliative therapy for patients with stage IV leukemia in an effort to relieve symptoms caused by the tumor. In addition, it has been on patients without metastasis following surgical removal of the primary tumor within the leukemia when the surgical margins are positive for tumor involvement, or if there is known residual tumor following surgery. Radiation is also used to shrink an especially large tumor prior to surgery or to slow the growth of inoperable tumors using either external beam (similar to an x-ray) or brachytherapy (internal radiation delivered with implanted radioactive seeds). It is common for the skin in the treated area to become red, dry, tender, and itchy. Radiation to the leukemia and nearby areas may cause nausea, vomiting, diarrhea, or urinary discomfort. Furthermore, it also dramatically reduces the meager number of healthy white blood cells left in the system. 
     In order to help restore the patient&#39;s immune system, a bone marrow transplant can help the patient produce enough white blood cells, red blood cells, and platelets. However, the donated bone marrow must match the patient&#39;s tissue type. Although there are many donor programs, usually a brother or a sister is the best source for so-called allogeneic BMT. 
     Many types of chemotherapy medications have been used for leukemia in various combinations in the past but some types of leukemia are highly resistant to chemotherapy. For instance, cytosine arabinoside (ARA-C) and anthracyclines (e.g., daunarubicin) yield response rates of 60% to 80%. Unfortunately, chemotherapy alone only cures 20% to 30% of the patients. Further, approximately 75% of patients achieving complete remission will relapse usually within 2 years. Potential side effects include nausea and vomiting, loss of hair, low blood cell counts, and fatigue. Many chemotherapeutic drugs have been tried in the past as single agents for the palliation of leukemia, but the results were generally disappointing. Nevertheless, the role of chemotherapy in the management of leukemia is continually evolving. Oftentimes, chemotherapy with radiation in adjunct to surgery is used. In general, chemotherapy can achieve long-term survival rates of up to 15% to 20%, even in patients with recurrent or metastatic disease (Ali et al., 2000,  Oncology  14(8):1223–30). Unfortunately, the high initial response rates to first line chemotherapy does not appear to translate into a survival benefit (Kohno and Kitahara, 2001,  Gan To Kagaku Ryoho  28(4):448–53). Moreover, there are many undesirable side effects associated with chemotherapy such as temporary hair loss, mouth sores, anemia (decreased numbers of red blood cells that may cause fatigue, dizziness, and shortness of breath), leukopenia (decreased numbers of white blood cells that may lower resistance to infection), thrombocytopenia (decreased numbers of platelets that may lead to easy bleeding or bruising), and gastrointestinal symptoms like nausea, vomiting, and diarrhea. Active chemotherapeutic agents include amsacrine (AMSA), busulfan (Myleran®), chlorambucil (Leukeran®), cladribine (2-chlorodeoxyadenosine; “2-CDA”; Leustatin®), cyclophosphamide (Cytoxan®), cytarabine (ara-C;Cytosar-U®), daunorubicin (Cerubidine®), doxorubicin (Adriamycin®), etoposide (VePesid®), fludarabine phosphate (Fludara®), hydroxyurea (Hydrea®), idarubicin (Idamycin®), L-asparaginase (Elspar®), methotrexate sodium plus 6-mercaptopurine (6-MP; Purinethol®), mitoxantrone (Novantrone®), pentostatin (2-deoxycoformycin; “DCF”; Nipent®), prednisone, retinoic acid (ATRA), vincristine sulfate (Oncovin®), and 6-thioguanine (Tabloid®). 
     The identification of active chemotherapeutic agents against cancers traditionally involved the use of various animal models of cancer. The mouse has been one of the most informative and productive experimental system for studying carcinogenesis (Sills et al., 2001,  Toxicol Letters  120:187–198), cancer therapy (Malkinson, 2001,  Lung Cancer  32(3):265–279; Hoffman R M., 1999,  Invest New Drugs  17(4):343–359), and cancer chemoprevention (Yun, 1999,  Annals NY Acad Sci.  889:157–192). Cancer research started with transplanted tumors in animals which provided reproducible and controllable materials for investigation. Pieces of primary animal tumors, cell suspensions made from these tumors, and immortal cell lines established from these tumor cells propagate when transplanted to animals of the same species. 
     To transplant human cancer to an animal and to prevent its destruction by rejection, the immune system of the animal are compromised. While originally accomplished by irradiation, thymectomy, and application of steroids to eliminate acquired immunity, nude mice that are athymic congenitally have been used as recipients of a variety of human tumors (Rygaard, 1983, in 13 th  International Cancer Congress Part C, Biology of Cancer (2), pp37–44, Alan R. Liss, Inc., NY; Fergusson and Smith, 1987,  Thorax,  42:753–758). While the athymic nude mouse model provides useful models to study a large number of human tumors in vivo, it does not develop spontaneous metastases and are not suitable for all types of tumors. Next, the severe combined immunodeficient (SCID) mice is developed in which the acquired immune system is completely disabled by a genetic mutation. Human lung cancer was first used to demonstrate the successful engraftment of a human cancer in the SCID mouse model (Reddy S., 1987,  Cancer Res.  47(9):2456–2460). Subsequently, the SCID mouse model have been shown to allow disseminated metastatic growths for a number of human tumors, particularly hematologic disorders and malignant melanoma (Mueller and Reisfeld, 1991,  Cancer Metastasis Rev.  10(3):193–200; Bankert et al., 2001,  Trends Immunol.  22:386–393). With the recent advent of transgenic technology, the mouse genome has become the primary mammalian genetic model for the study of cancer (Resor et al., 2001,  Human Molec Genet.  10:669–675). 
     While surgery, chemotherapeutic agents and radiation are useful in the treatment of leukemia, there is a continued need to find better treatment modalities and approaches to manage the disease that are more effective and less toxic, especially when clinical oncologists are giving increased attention to the quality of life of cancer patients. The present invention provides an alternative approach to cancer therapy and management of the disease by using an oral composition comprising yeasts. 
     2.2 Yeast-Based Compositions 
     Yeasts and components thereof have been developed to be used as dietary supplement or pharmaceuticals. However, none of the prior methods uses yeast cells which have been cultured in an electromagnetic field to produce a product that has an anti-cancer effect. The following are some examples of prior uses of yeast cells and components thereof: 
     U.S. Pat. No. 6,197,295 discloses a selenium-enriched dried yeast product which can be used as dietary supplement. The yeast strain  Saccharomyces boulardii  sequela PY 31 (ATCC 74366) is cultured in the presence of selenium salts and contains 300 to about 6,000 ppm intracellular selenium. Methods for reducing tumor cell growth by administration of the selenium yeast product in combination with chemotherapeutic agents is also disclosed. 
     U.S. Pat. No. 6,143,731 discloses a dietary additive containing whole β-glucans derived from yeast, which when administered to animals and humans, provide a source of fiber in the diet, a fecal bulking agent, a source of short chain fatty acids, reduce cholesterol and LDL, and raises HDL levels. 
     U.S. Pat. No. 5,504,079 discloses a method of stimulating an immune response in a subject utilizing modified yeast glucans which have enhanced immunobiologic activity. The modified glucans are prepared from the cell wall of  Saccharomyces  yeasts, and can be administered in a variety of routes including, for example, the oral, intravenous, subcutaneous, topical, and intranasal route. 
     U.S. Pat. No. 4,348,483 discloses a process for preparing a chromium yeast product which has a high intracellular chromium content. The process comprises allowing the yeast cells to absorb chromium under a controlled acidic pH and, thereafter inducing the yeast cells to grow by adding nutrients. The yeast cells are dried and used as a dietary supplement. 
     Citation of documents herein is not intended as an admission that any of the documents cited herein is pertinent prior art, or an admission that the cited documents are considered material to the patentability of the claims of the present application. All statements as to the date or representations as to the contents of these documents are based on the information available to the applicant and does not constitute any admission as to the correctness of the dates or contents of these documents. 
     3. SUMMARY OF THE INVENTION 
     The present invention relates to biological or oral compositions useful for subjects with leukemia. In one embodiment, the present invention provides biological compositions comprising live yeast cells which are capable of producing a healthful benefit in subjects with leukemia. In other embodiments, the invention provides methods of making the biological compositions, and methods of using the biological compositions. 
     In particular, the methods of the invention comprise culturing yeast cells in the presence of a series of electromagnetic fields such that the yeast cells becomes metabolically active. The electromagnetic fields used are each defined by one of five frequency ranges and a broad range of field strength. The starting yeast cells are commercially available and/or accessible to the public, such as but not limited to  Saccharomyces . The methods for making the biological compositions of the invention further comprise conditioning the activated yeast cells in plant extracts and the gastric juice of animals, while in the presence of another series of electromagnetic fields. 
     The methods of manufacturing also comprise expanding the number of activated or activated and conditioned yeast cells in large scale cultures in the presence of yet another series of electromagnetic fields, performing quality control measures, and packaging. Pharmaceutical compositions of the invention comprises activated and conditioned yeast cells and one or more pharmaceutically acceptable excipients or carriers. Additional ingredients, such as vitamins and/or flavors may be added to the biological compositions to form the oral compositions of the invention. Such additional carriers and ingredients can improve the healthful benefits, pharmacological properties, and organoleptic characteristics of the oral compositions. During the manufacturing process, the activated or activated and conditioned yeast cells may be dried and stored for a period of time. 
     The biological or oral compositions of the invention are ingested by the subject or used as an additive to be incorporated into food to be consumed by the subject. Dietary supplement and nutritional compositions comprising activated and conditioned yeast cells are encompassed by the invention. Preferably, the subject is a human being. 
     In various embodiments, the biological or oral compositions of the invention are used to produce a healthful benefit in a subject with leukemia or at high risk of developing leukemia. In particular, the biological composition of the invention can retard the growth of leukemia cells in an animal which received the composition orally. The composition can also be used to prolong the time of survival of an animal with leukemia. 
    
    
     
       4. BRIEF DESCRIPTION OF FIGURES 
         FIG. 1  Activation and conditioning of yeast cells. 1 yeast cell culture; 2 container; 3 electromagnetic field source; 4 electrode. 
         FIG. 2  Large scale propagation of yeast cells. 5 first container; 6 second container; 7 third container; 8 yeast cell cultures; 9 electromagnetic field source. 
     
    
    
     5. DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to biological compositions that can produce a healthful benefit in a subject with leukemia. The present invention provides methods for manufacturing the biological compositions as well as methods for using the biological compositions. 
     In one embodiment, the invention provides biological compositions that comprise yeasts. Unlike the traditional use of yeasts in the making of food, the yeast cells of the invention are not used as a source of enzymes that acts on the food ingredients. The yeasts are not a primary source of nutrients for the subject. Nor are yeast cells used as a carrier, such as metal salts. The yeast cells of the invention are live when administered orally or ingested along with food by a subject. Without being bound by any theory or mechanism, the inventor believes that the culture conditions activate and/or amplified the expression of a gene or a set of genes in the yeast cells such that the yeast cells becomes highly effective in stimulating the animal&#39;s immune system, including both specific and non-specific immunological reactions, the results of which are manifested as the overall healthful benefits observed in the treated subject. The healthful benefits provided by using the biological compositions are demonstrated in animal models of human leukemia which show inhibition of tumor growth and prolonged survival time of animals with the disease. 
     In another embodiment, the invention provides methods for making the yeast cells in the biological compositions. The starting materials are normal yeast cells which can be readily obtained commercially or from public microorganism deposits. The methods of the invention comprise a set of culture conditions that can be applied reproducibly to activate the yeast cells. The key feature of the culture conditions used in the methods of the invention is a series of alternating electromagnetic fields of defined frequency ranges and field strengths which are applied to the growing yeast cell culture. The method further comprises the step of conditioning the activated live yeast cells to the acidic environment of the stomach of the subject. The electromagnetic fields used in these methods can be created reproducibly at various scales, thus enabling even the large scale manufacturing of the biological compositions of the invention. By careful control of the culturing conditions, normal yeast cells can be activated routinely and reproducibly to become yeast cells of the invention. 
     In yet another embodiment, the invention provides methods for manufacturing an oral composition comprising activated and conditioned yeasts of the invention, and additional ingredients, including but not limited to pharmaceutically acceptable carriers or excipients, vitamins, herbs (including traditional Chinese medicine products), herbal extracts, minerals, amino acids, flavoring agents, coloring agents, and/or preservatives. 
     In yet another embodiment, the biological compositions can be added to food which will be consumed by the subject. As known to those skilled in the relevant art, many methods may be used to mix the biological or oral compositions of the invention with food while the yeast cells remain viable. In a particular embodiment, the culture broth comprising live yeast cells of the present invention are added directly to food just prior to consumption. Dried powders of the yeasts can also be reconstituted and added directly to food just prior to consumption. 
     In various embodiments, the oral compositions of the invention can be consumed directly by a subject or be fed directly to a subject. For example, the subject may drink the culture broth or a fraction thereof that comprises live activated and conditioned yeast cells. Oral compositions comprising dried yeast cells can also be given as a solid dosage form to the subject. 
     Although it is not necessary, the biological or oral compositions of the invention can be used in conjunction or in rotation with other types of treatment modalities such as but not limited to surgery, chemotherapeutic agents, and radiation. Since the biological compositions of the invention are administered orally, the assistance of health professionals in administration of the composition is generally not essential. 
     Described below in Section 5.1 are the yeast cells of the invention and methods of their preparation. Section 5.2 describes the use of the biological compositions of the invention in a subject suffering from leukemia. The examples in Sections 6 to 9 demonstrate the therapeutic benefits of an oral composition of the invention. The activated and conditioned yeast cells in the oral composition are characterized by their ability to (i) suppress the growth of cancer cells in an animal model of human leukemia, or (ii) prolong the survival of animals with transplanted cancer cells in a model of human leukemia, as compared to yeast cells which have not been activated and conditioned. 
     5.1 Preparation of the Yeast Cell Cultures 
     The yeast cells of the biological composition are produced by culturing a plurality of yeast cells in an appropriate culture medium in the presence of an alternating electromagnetic field over a period of time. The method comprises a first step of activating the yeast cells and a second step of conditioning the activated yeast cells. The activation process comprises culturing yeast cells in the presence of at least two, three, four or five electromagnetic fields of specific frequencies and field strength. The conditioning process comprises further culturing of the activated yeast cells in a medium comprising plant extracts and extracts from the stomach of an animal, in the presence of at least one electromagnetic field. The activated and conditioned yeast cells can be stored as dried cells after drying the cells under appropriate conditions. The dried activated and conditioned yeast cells can be used later in large scale culturing processes for manufacturing the biological compositions of the invention. The various culturing processes of the invention can be performed either as a batch process or a continuous process. 
     5.1.1 Yeasts 
     In various embodiments, yeasts of the genera of  Saccharomyces, Candida, Crebrothecium, Geotrichum, Hansenula, Kloeckera, Lipomyces, Pichia, Rhodosporidium, Rhodotorula, Torulopsis, Trichosporon , and  Wickerhamia  can be used in the invention. Generally, fungi used for food manufacturing are preferred. 
     Non-limiting examples of yeast strains include  Saccharomyces  sp., AS2.311;  Schizosaccharomyces pombe  Linder, AS2.214, AS2.248, AS2.249, AS2.255, AS2.257, AS2.259, AS2.260, AS2.274, AS2.994, AS2.1043, AS2.1149, AS2.1178, IFFI 1056;  Saccharomyces sake  Yabe, ACCC2045;  Saccharomyces uvarum  Beijer, IFFI 1023, IFFI 1032, IFFI 1036, IFFI 1044, IFFI 1072, IFFI 1205, IFFI 1207;  Saccharomyces rouxii  Boutroux, AS2.178, AS2.180, AS2.370, AS2.371;  Saccharomyces cerevisiae  Hansen Var. ellipsoideus, ACCC2043, AS2.2, AS2.3, AS2.8, AS2.53, AS2.163, AS2.168, AS2.483, AS2.541, AS2.559, AS2.606, AS2.607, AS2.611, AS2.612;  Saccharomyces carlsbergensis  Hansen, AS2.116, AS2.162, AS2.189, AS2.200, AS2.216, AS2.265, AS2.377, AS2.417, AS2.420, AS2.440, AS2.441, AS2.443, AS2.444, AS2.459, AS2.595, AS2.605, AS2.638, AS2.742, AS2.745, AS2.748, AS2.1042;  Rhodotorula aurantiaca  (Saito)Ladder; AS2.102, AS2.107, AS2.278, AS2.499, AS2.694, AS2.703, AS2.704 and AS2.1146;  Saccharomyces cerevisiae  Hansen, ACCC2034, ACCC2035, ACCC2036, ACCC2037, ACCC2038, ACCC2039, ACCC2040, ACCC2041, ACCC2042, AS2.1, AS2.4, AS2.11, AS2.14, AS2.16, AS2.56, AS2.69, AS2.70, AS2.93, AS2.98, AS2.101, AS2.109, AS2.110, AS2.112, AS2.139, AS2.173, AS2.182, AS2.196, AS2.242, AS2.336, AS2.346, AS2.369, AS2.374, AS2.375, AS2.379, AS2.380, AS2.382, AS2.393, AS2.395, AS2.396, AS2.397, AS2.398, AS2.399, AS2.400, AS2.406, AS2.408, AS2.409, AS2.413, AS2.414, AS2.415, AS2.416, AS2.422, AS2.423, AS2.430, AS2.431, AS2.432, AS2.451, AS2.452, AS2.453, AS2.458, AS2.460, AS2.463, AS2.467, AS2.486, AS2.501, AS2.502, AS2.503, AS2.504, AS2.516, AS2.535, AS2.536, AS2.558, AS2.560, AS2.561, AS2.562, AS2.576, AS2.593, AS2.594, AS2.614, AS2.620, AS2.628, AS2.631, AS2.666, AS2.982, AS2.1190, AS2.1364, AS2.1396, IFFI 1001, IFFI 1002, IFFI 1005, IFFI 1006, IFFI 1008, IFFI 1009, IFFI 1010, IFFI 1012, IFFI 1021, IFFI 1027, IFFI 1037, IFFI 1042, IFFI 1045, IFFI 1048, IFFI 1049, IFFI 1050, IFFI 1052, IFFI 1059, IFFI 1060, IFFI 1062, IFFI 1202, IFFI 1203, IFFI 1209, IFFI 1210, IFFI 1211, IFFI 1212, IFFI 1213, IFFI 1215, IFFI 1221, IFFI 1224, IFFI 1247, IFFI 1248, IFFI 1251, IFFI 1270, IFFI 1277, IFFI 1289, IFFI 1290, IFFI 1291, IFFI 1292, IFFI 1293, IFFI 1297, IFFI 1300, IFFI 1301, IFFI 1302, IFFI 1307, IFFI 1308, IFFI 1309, IFFI 1310, IFFI 1311, IFFI 1331, IFFI 1335, IFFI 1336, IFFI 1337, IFFI 1338, IFFI 1339, IFFI 1340, IFFI 1345, IFFI 1348, IFFI 1396, IFFI 1397, IFFI 1399, IFFI 1441 and IFFI 1443. Preferred yeast strains include but are not limited to  S. cerevisiae  AS2.501, AS2.502, AS2.503, AS2.504, AS2.535, AS2.558, AS2.560, AS2.561 and AS2.562. 
     Generally, yeast strains useful for the invention can be obtained from private or public laboratory cultures, or publicly accessible culture deposits, such as the American Type Culture Collection, 10801 University Boulevard, Manassas, Va. 20110-2209 and the China General Microbiological Culture Collection Center (CGMCC), China Committee for Culture Collection of Microorganisms, Institute of Microbiology, Chinese Academy of Sciences, Haidian, P.O. Box 2714, Beijing, 100080, China. 
     Non-limiting examples of using yeast cells of the invention with  Saccharomyces cerevisiae  Hansen strain AS2.11 are provided in Sections 6 to 9 herein below. The yeast cells of the invention do not comprise an enhanced level of selenium or chromium relative to that found in naturally occurring yeast cells. In certain embodiments, the biological compositions do not comprise cells of  Saccharomyces boulardii  (for example, ATCC Accession No. 74366) or cells of a particular strain of  Saccharomyces cerevisiae  (strain Hansen CBS 5926) that is also commonly referred to as  Saccharomyces boulardii.    
     Although it is preferred, the preparation of the yeast cells of the invention is not limited to starting with a pure strain of yeast. The yeast cells in the biological compositions may be produced by culturing a mixture of yeast cells of different species or strains. The constituents of a mixture of yeast cells can be determined by standard yeast identification techniques well known in the art. 
     In various embodiments of the invention, standard techniques for handling, transferring and storing yeasts are used. Although it is not necessary, sterile conditions or clean environments are highly desirable when carrying out the manufacturing processes of the invention, especially when the biological compositions are for human consumption. The manufacturing process can be adapted to meet regulatory guidelines on product safety and quality control by standard practice known in the art. 
     5.1.2 Electromagnetic Fields 
     As used herein, the terms “alternating electromagnetic field”, “electromagnetic field” or “EM field” are synonymous. An electromagnetic field useful in the invention can be generated by various means well known in the art. A schematic illustration of exemplary setups are depicted respectively in  FIG. 1 . An electromagnetic field of a desired frequency and a desired field strength is generated by an electromagnetic wave source ( 3 ) which comprises one or more signal generators that are capable of generating electromagnetic waves, preferably sinusoidal waves, and preferably in the frequency range of 1,500 to 15,000 MHz and most preferably 9,900 to 12,700 MHz. Such signal generators are well known in the art. Signal generators capable of generating signal with a narrower frequency range can also be used. If desirable, a signal amplifier can also be used to increase the output signal, and thus the strength of the EM field. 
     The electromagnetic field can be applied to the culture by a variety of means including placing the yeast cells in close proximity to a signal emitter connected to a source of electromagnetic waves. The signal generator is connected to the signal emitter by cables such as coaxial cables that can transmit signals up to greater than or equal to 30 GHz. Typically, the yeast cells are placed in a container which is made of material that is not an electric conductor, such as but not limited to plastic, resin, glass, and ceramic. 
     In one embodiment, the electromagnetic field is applied by signal emitters in the form of electrodes ( 4 ) that are submerged in a culture of yeast cells ( 1 ). In a preferred embodiment, one of the electrodes is a metal plate which is placed on the bottom of a non-conducting container ( 2 ), and the other electrode comprises a plurality of wires or tubes so configured inside the container such that the energy of the electromagnetic field can be evenly distributed in the culture. The electrodes are preferably made of copper. For an upright culture vessel, the tips of the wires or tubes are placed within 3 to 30 cm from the bottom of the vessel (i.e., approximately 2% to 10% of the height of the vessel from the bottom). Table 1 provides exemplary set up for culturing the yeast cells of the invention. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 height of culture 
                   
                   
               
               
                 medium in the 
                 distance electrodes are 
                 range for distance of 
               
               
                 non-conducting 
                 placed from the bottom 
                 the electrodes from the 
               
               
                 container (cm) 
                 of the container (cm) 
                 bottom (cm) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 15 to 20 
                 3 
                 3 to 5 
               
               
                 20 to 30 
                 5 
                 5 to 7 
               
               
                 30 to 50 
                 7 
                  7 to 10 
               
               
                 50 to 70 
                 10 
                 10 to 15 
               
               
                  70 to 100 
                 15 
                 15 to 20 
               
               
                 100 to 150 
                 20 
                 20 to 30 
               
               
                 150 to 200 
                 30 
                 25 to 30 
               
               
                   
               
            
           
         
       
     
     The number of electrodes used depends on both the volume of the culture and the diameter of the electrode. For example, for a culture having a volume of 10 liter or less, two or three electrodes having a diameter of between 0.5 to 2.0 mm can be used. For a culture volume of 10 to 100 liter of culture, the electrodes can have a diameter of 3.0 to 5.0 mm. For a culture volume of 100 to 1,000 liter, the electrodes can have a diameter of 6.0 to 15.0 mm. For a culture having a volume greater than 1,000 liter, the electrodes can have a diameter of between 20.0 to 25.0 mm. 
     5.1.3 Activation of Yeast Cells 
     According to the invention, the method for producing activated yeast cells of the invention comprises culturing yeast cells in the presence of at least two, three, four or five alternating electromagnetic (EM) fields. 
     The culture process can be initiated by inoculating 1,000 ml of medium with an inoculum of a selected yeast strain (such as one of those described in Section 5.1.1) such that the starting cell density of the culture is greater than about 10 5  cells per ml. For example,  Saccharomyces cerevisiae  Hansen strain AS2.11 can be used. The starting culture can be used to seed larger scale culture. The culture is maintained initially at 28° C. to 32° C. for 22 to 30 hours prior to exposure to the EM field(s), typically at 30° C. for 28 hours. 
     The culturing process may preferably be conducted under conditions in which the concentration of dissolved oxygen is between 0.025 to 0.08 mol/m 3 , preferably 0.04 mol/m 3 . The oxygen level can be controlled by any conventional means known in the art, including but not limited to stirring and/or bubbling. 
     The culture is most preferably carried out in a liquid medium which contains sources of nutrients assimilable by the yeast cells. Table 2 provides an exemplary medium for culturing the yeast cells of the invention. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Medium Composition 
                 Quantity 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Sucrose or glucose 
                 20 
                 g 
               
               
                   
                 Vitamin B 12   
                 40 
                 μg 
               
               
                   
                 Vitamin B 6   
                 30 
                 μg 
               
               
                   
                 Vitamin D 
                 20 
                 μg 
               
               
                   
                 Vitamin H 
                 20 
                 μg 
               
               
                   
                 Bovine calf serum 
                 30 
                 ml 
               
               
                   
                 MgSO 4 .7H 2 O 
                 0.25 
                 g 
               
               
                   
                 NaCl 
                 0.30 
                 g 
               
               
                   
                 CaSO 4 .2H 2 O 
                 0.20 
                 g 
               
               
                   
                 CaCO 3 .5H 2 O 
                 4.0 
                 g 
               
               
                   
                 Peptone 
                 2.5 
                 g 
               
               
                   
                 Autoclaved water 
                 1,000 
                 ml 
               
               
                   
                   
               
            
           
         
       
     
     The culturing medium is heated to 45° C. and cooled before adding the vitamin B 12 , vitamin B 6 , vitamin D, vitamin H, and bovine calf serum. 
     In general, carbohydrates such as sugars, for example, sucrose, glucose, fructose, dextrose, maltose, xylose, and the like and starches, can be used either alone or in combination as sources of assimilable carbon in the culture medium. The exact quantity of the carbohydrate source or sources utilized in the medium depends in part upon the other ingredients of the medium but, in general, the amount of carbohydrate usually varies between about 0.1% and 5% by weight of the medium and is preferably between about 0.2% and 2%. These carbon sources can be used individually, or several such carbon sources may be combined in the medium. Among the inorganic salts which can be incorporated in the culture media are the customary salts capable of yielding sodium, calcium, phosphate, sulfate, carbonate, and like ions. Non-limiting examples of nutrient inorganic salts are KH 2 PO 4 , (NH 4 ) 2 HPO 4 , CaCO 3 , MgSO 4 , NaCl, and CaSO 4 . 
     It should be noted that the composition of the media provided in Table 2 is not intended to be limiting. The process can be scaled up or down according to needs. Various modifications of the culture medium may be made by those skilled in the art, in view of practical and economic considerations, such as the scale of culture and local supply of media components. 
     In certain embodiments, a series of at least two, three, four or five EM fields are applied to the culture of yeast cells, each having a different frequency within a stated range, and a different field strength within a stated range. The EM fields can be applied in any order and by any means known in the art, such as the apparatus described in Section 5.1.2. Although any of the following two, three or four EM fields can be applied, preferably, all five EM fields are applied. 
     For the first EM field, the frequency is in the range of 9,971 to 9,980 MHz and the field strength is in the range of 200 to 220 mV/cm. The yeast culture is exposed to this first EM field at 30±2° C. for about 24 hours. 
     For the second EM field, the frequency is in the range of 11,481 to 11,490 MHz and the field strength is in the range of 190 to 210 mV/cm. The yeast culture is exposed to this second EM field at 30±2° C. for about 8 hours. 
     For the third EM field, the frequency is in the range of 12,191 to 12,200 MHz and the field strength is in the range of 230 to 250 mV/cm. The yeast culture is exposed to this third EM field at 30±2° C. for about 24 hours. 
     For the fourth EM field, the frequency is in the range of 12,561 to 12,570 MHz and the field strength is in the range of 240 to 270 mV/cm. The yeast culture is exposed to this fourth EM field at 30±2° C. for about 8 hours. 
     For the fifth EM field, the frequency is in the range of 12,611 to 12,620 MHz and the field strength is in the range of 260 to 280 mV/cm. The yeast culture is exposed to this fifth EM field at 30±2° C. for about 24 hours. 
     In less preferred embodiments, the yeast cells can be cultured by exposure to two, three or four of the above-mentioned EM fields in a different order. The yeast cells can remain in the same container and use the same set of electromagnetic wave generator and emitters when switching from one EM field to another EM field. 
     The cell density of the culture at the end of the activation process is typically greater than about 10 6  to 10 9  cells per ml (estimated by hematocytometer). The activated yeast cells may be recovered from the culture by various methods known in the art, and stored at a temperature below about 0° C. to 4° C. The activated yeast cells recovered from the liquid culture may be dried and stored in powder form. Preferably, the powder form of the yeast cells comprises greater than about 10 7  to 10 10  yeast cells per gram. 
     5.1.4 Conditioning of Yeast Cells 
     According to the invention, performance of the activated yeast cells can be optimized by culturing the activated yeast cells in the presence of an extract from the stomach (e.g., the gastric juice) of an animal with physiology similar to the subject to which the biological composition will be administered. The inclusion of this additional conditioning process allows the activated yeast cells to adapt to and endure the acidic environment of the subject&#39;s stomach. The method for conditioning activated yeast cells of the invention comprises culturing yeast cells in such materials in the presence of at least one EM field. 
     The culture process can be initiated by inoculating 1,000 ml of a conditioning medium with about 10 gram of dried activated yeasts containing about 10 10  cells per gram (as prepared by the methods described in Section 5.1.3). An equivalent number of yeast cells in culture, preferably greater than 10 6  to 10 9  cells per ml, more preferably at 10 8  cells per ml, can also be used as an inoculum. The conditioning medium comprises per 1,000 ml about 700 ml of gastric juice of an animal and about 300 ml of wild hawthorn juice. The process can be scaled up or down according to needs. 
     The gastric juice of an animal can be obtained from the stomach content of a freshly slaughtered animal. Although not essential, the animal is preferably kept under a clean environment, and fed a standard diet, preferably germ-free. For example, the content of the stomach of a 120-day old pig is mixed with 2,000 ml of distilled water, and allowed to settle without stirring for 6 hours. The clear liquid above is collected for use as the gastric juice used in the conditioning process. The gastric juice of a pig can be used to condition yeast cells for use in a variety of mammals, including humans. Other methods that can be used to collect the gastric juice include centrifugation or filtration of the mixture to remove debris and/or microorganisms. The gastric juice so obtained can be stored at 4° C. Preferably, the collection procedures and storage are carried out under sterile conditions. 
     The wild hawthorn juice is an extract of wild hawthorn fruits prepared by slicing the fruits and drying the slices in air, preferably to less than 8% moisture (commercial dryer can be used if necessary), crushing the dried fruits to less than 20 mesh, and mixing 1,500 ml of water per 500 gram of the crushed wild hawthorn. The mixture is then allowed to settle without stirring for 6 hours, and the clear liquid above is collected for use as the wild hawthorn juice used in the conditioning process. Other methods that can be used to collect the hawthorn juice include centrifugation or filtration of the mixture. Preferably, the collection procedures and storage are carried out under sterile conditions. 
     The activated yeast cells are conditioned by culturing in at least one of the following two EM fields which can be applied by the apparatus described in Section 5.1.2 or any means known in the art: 
     The first EM field has a frequency in the range of 12,561 to 12,570 MHz and a field strength in the range of 260 to 290 mV/cm. The temperature is maintained at 28° C. to 32° C., and typically at 30° C. The yeast culture is exposed to this first EM field for about 12 hours. 
     The second EM field has a frequency in the range of 12,611 to 12,620 MHz and a field strength in the range of 260 to 280 mV/cm. The temperature is maintained at 28° C. to 32° C., and typically at 30° C. The yeast culture is exposed to this second EM field for about 39 hours. 
     In a preferred embodiment, the activated yeast cells are conditioned by culturing in both of the above-mentioned EM fields. In less preferred embodiments, the yeast cells are conditioned in the two different EM fields in a different order. In other embodiments, a series of EM fields having field characteristics within the ranges stated above can be applied to condition the yeast cells. The yeast cells can remain in the same container and use the same set of electromagnetic wave generator and emitters when switching from one EM field to another EM field. 
     The cell density of the culture at the end of the activation process is typically greater than about 10 7  to 10 10  cells per ml (estimated by hematocytometer). The activated and conditioned yeast cells may be recovered from the culture by various methods known in the art, and stored at a temperature below about 0° C. to 4° C. 
     The activated and conditioned yeast cells can be used directly in a biological composition or used as a starter culture for large scale manufacturing. The activated and conditioned yeast cells recovered from the liquid culture may be dried and stored in powder form. Preferably, the powder form of the activated and conditioned yeast cells comprises greater than about 10 8  to 10 11  yeast cells per gram. 
     5.1.5 Large Scale Manufacturing 
     The present invention also encompasses methods of manufacturing of the biological compositions of the invention at a large scale. The activated and conditioned yeast cells as prepared by Sections 5.1.3 and 5.1.4 are propagated on a large scale to make the biological compositions of the invention. The method comprises culturing the yeast cells in the presence of one or more EM fields for a period of time, diluting the growing yeast cells with fresh medium, and repeating the process. The method can be carried out as a batch process or a continuous process. 
     In one preferred embodiment, a set of three containers (5, 6, 7) each comprising a set of electrodes for generating an electromagnetic field as described in Section 5.1.2 are set up each with 1,000 liters of a culture medium. See  FIG. 2 . The culture medium comprises nutrients assimilable by the yeast cells as shown in Table 3. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Material 
                 Quantity 
               
               
                   
                   
               
             
            
               
                   
                 Wild hawthorn juice 
                 300 liters 
               
               
                   
                 Jujube juice 
                 300 liters 
               
               
                   
                 Wu wei zi juice 
                 300 liters 
               
               
                   
                 Soybean juice 
                 100 liters 
               
               
                   
                   
               
            
           
         
       
     
     The wild hawthorn juice is an extract of fresh wild hawthorn fruits prepared by washing the fruits clean, drying the fruits in air or using a commercial dryer to less than 8% moisture, crushing the dried fruits to less than 20 mesh, and mixing the crushed wild hawthorn with water at a ratio of 400 liters of water per 100 kg of crushed fruits. The mixture is then stirred continuously for 12 hours while the temperature is maintained at 28° C. to 30° C. The mixture is then centrifuged at 1,000 rpm to collect the supernatant which is used as described above. Preferably, the procedures are carried out under sterile conditions. 
     The jujube juice is an extract of fresh jujube fruits prepared by washing the fruits clean, drying the fruits to less than 8% moisture, crushing the dried fruits to less than 20 mesh, and mixing the crushed jujube with water at a ratio of 400 liters of water per 100 kg of crushed fruits. The mixture is then stirred continuously for 12 hours while the temperature is maintained at 28° C. to 30° C. The mixture is then centrifuged at 1,000 rpm to collect the supernatant which is used as described above. Preferably, the procedures are carried out under sterile conditions. 
     The wu wei zi juice is an extract of fresh berries of  Schisandra chinensis  plant prepared by washing the berries, drying the fruits to less than 8% moisture, crushing the dried berries to less than 20 mesh, and mixing the crushed berries with water at a ratio of 400 liters of water per 100 kg of crushed berries. The mixture is then stirred continuously for 12 hours while the temperature is maintained at 28° C. to 30° C. The mixture is then centrifuged at 1,000 rpm to collect the supernatant which is used as described above. Preferably, the procedures are carried out under sterile conditions. 
     The soybean juice is prepared by washing the soybeans, drying the soybeans to less than 8% moisture, crushing the soybeans to less than 20 mesh, and mixing the crushed soybeans with water. For 30 kg of soybeans, 130 liters of water is used. The mixture is then stirred continuously for 12 hours while the temperature is maintained at 28° C. to 30° C. The mixture is then centrifuged at 1,000 rpm to collect the supernatant which is used as described above. Preferably, the procedures are carried out under sterile conditions. 
     The first container is inoculated with activated or activated and conditioned yeast cells as prepared by the methods of Sections 5.1.4 and 5.1.5. About 1,000 gram of dried yeast powder are added to 1,000 liter of culture medium. Each gram of the dried yeast powder comprises about 1010 yeast cells. Instead of dried yeast cells, an equivalent number of yeast cells in a liquid medium can also be used, preferably greater than about 10 6  to 10 9  cells per ml, more preferably about 10 7  cells per ml. 
     The yeast cells in the first container (5) are then subjected to a series of two EM fields. For the first EM field, which can be applied by the apparatus described in Section 5.1.2, the frequency is in the range of 12,561 to 12,570 MHz and the field strength is in the range of 255 to 275 mV/cm. The yeast culture is exposed to this first EM field for about 8 hours. The yeast cells are then subjected to a second EM field having a frequency in the range of 12,611 to 12,620 MHz and a field strength in the range of 290 to 310 mV/cm. The yeast culture is exposed to this second EM field for about 12 hours. The yeast cells from the first container are then transferred to the second container which contains about 1,000 liter of the culture medium. In effect, the first yeast culture is diluted by about 50% with fresh culture medium. 
     In the second container ( 6 ), the yeast cells are again subjected to a series of two EM fields. The frequencies used in the second container are similar to those used in the first container but the field strengths are marginally lower. The first EM field has a frequency in the range of 12,561 to 12,570 MHz and a field strength in the range of 270 to 290 mV/cm. The yeast culture is exposed to this EM field for about 8 hours. The yeast cells are then subjected to a second EM field having a frequency in the range of 12,611 to 12,620 MHz and a field strength in the range of 290 to 320 mV/cm. The yeast culture is exposed to this second EM field for about 12 hours. The yeast cells from the second container are then transferred to the third container which contains yet another 1,000 liter of the culture medium. Again, the second yeast culture is diluted by about 50% with fresh culture medium. 
     In the third container ( 7 ), the yeast cells are again subjected to a series of two EM fields. The frequencies used in the third container are similar to those used in the first and second container but the field strengths are lower. The first EM field has a frequency in the range of 12,561 to 12,570 MHz and field strength in the range of 170 to 190 mV/cm. The yeast culture is exposed to this EM field for about 12 hours. The yeast cells are then subjected to a second EM field having a frequency in the range of 12,611 to 12,620 MHz and a field strength in the range of 250 to 270 mV/cm. The yeast culture is exposed to this EM field for about 24 hours. 
     The yeast cell culture resulting from the end of this stage can be used directly as an oral composition of the invention, or used to form other compositions encompassed by the invention. 
     The cell density of the culture at the end of the large scale manufacturing process is typically greater than about 10 8  to 10 10  cells per ml (estimated by hematocytometer). The concentration of yeast cells in the medium can be concentrated or diluted accordingly. In certain embodiments, the concentration of yeast cells in the medium is in the range of 10 3  to 10 10  cells per ml. In less preferred embodiments, the concentration of yeast cells in the medium is in the range of 10 3  to 10 6  cells per ml. In more preferred embodiments, the concentration of yeast cells in the medium is greater than 10 6  to 10 10  cells per ml. In most preferred embodiments, the concentration of yeast cells in the medium is in the range of 10 6  to 5×10 8  cells per ml. 
     Other ingredients that enhance the healthful benefits, pharmacological properties and/or organoleptic characteristics of the composition can be added to the yeast cell culture. To maintain viability and freshness of the composition, it is preferred that the various downstream and packaging process be carried out below room temperature, and preferably at 0° C. to 4° C. In one embodiment, the yeast cell culture can be packaged in liquid containers. 
     In another embodiment, the activated and conditioned yeast cells can be dried as follows. The yeast cell culture is first centrifuged under 75 to 100 g for 10 to 20 minutes to remove the supernatant. The residue which may contain up to 85% moisture is dried in a first dryer at a temperature not exceeding 60±2° C. for a period of 5 minutes so that yeast cells quickly became dormant. The yeast cells were then sent to a second dryer and dried at a temperature not exceeding 65±2° C. for a period of about 8 minutes to further remove at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 98%, or at least 99% of water. For example, the yeast cells may be dried to remove at least 88% of water so the dried yeast cells may contain up to 12% moisture. 
     After cooling to room temperature, the dried yeast cells can be packaged by standard pharmaceutical methods in various solid dosage form, each containing a predetermined amount of the dried material. In a preferred embodiment, the dried material comprises about 10 5  to 10 11  cells per gram. In a more preferred embodiment, the dried material comprises about 10 8  to 5×10 10  cells per gram. In a most preferred embodiment, the dried material comprises about 5×10 8  cells per gram. 
     In general, the compositions are prepared by uniformly and intimately admixing the active ingredient with liquid carriers or finely divided solid carriers. 
     5.1.6 Preferred Embodiments 
     In one preferred embodiment, the invention provides a method for preparing a biological composition comprising activated and conditioned yeast cells, said method comprising in any order the steps of:
         (a) culturing the yeast cells in a first electromagnetic field having a frequency at 9,978 MHz and a field strength of 217 mV/cm;   (b) culturing the yeast cells in a second electromagnetic field having a frequency at 11,484 MHz and a field strength of 207 mV/cm;   (c) culturing the yeast cells in a third electromagnetic field having a frequency at 12,196 MHz and a field strength of 238 mV/cm;   (d) culturing the yeast cells in a fourth electromagnetic field having a frequency at 12,565 MHz and a field strength of 244 mV/cm; and   (e) culturing the yeast cells in a fifth electromagnetic field having a frequency at 12,612 MHz and a field strength of 262 mV/cm;
 
and after the last of the first five steps, the following steps in any order:
   (f) culturing the yeast cells in a liquid medium comprising wild hawthorn juice and gastric juice of a mammal in a sixth electromagnetic field having a frequency at 12,565 MHz and a field strength of 265 mV/cm; and   (g) culturing the yeast cells in a liquid medium comprising wild hawthorn juice and gastric juice of a mammal in a seventh electromagnetic field having a frequency at 12,612 MHz and a field strength of 278 mV/cm.       

     The activated and conditioned yeast cells obtained at the conclusion of this method is encompassed by the invention. Preferably, the yeast cells are  Saccharomyces cerevisiae  Hansen strain AS2.11. These yeast cells can be used in the following method of further expanding number of activated and conditioned yeast cells. 
     In another preferred embodiment, the invention provides a method of mass producing a biological composition comprising activated and conditioned yeast cells, said method comprising culturing the activated and conditioned yeast cells prepared by the preferred embodiment described above in this section, in a medium comprising wild hawthorn juice, jujube juice, wu wei zi juice, and soybean juice, and in the presence of one or more series of electromagnetic fields. Each series of EM fields comprises two EM fields in the order stated:
         (h) an eighth electromagnetic field or series of electromagnetic fields having a frequency at 12,565 MHz and a field strength in the range of 170 to 290 mV/cm, preferably at three fields strengths, e.g., in the order of 270 mV/cm, 277 mV/cm, and 184 mV/cm; and   (i) a ninth electromagnetic field or series of electromagnetic fields having a frequency at 12,612 MHz and a field strength in the range of 250 to 320 mV/cm, preferably at three fields strengths, e.g., in the order of 296 mV/cm, 318 mV/cm, and 267 mV/cm.       

     The series may be repeated several times, such as three times, each time using a slightly lower field strength. 
     5.2 Methods of Uses 
     5.2.1 Uses in Subjects with Leukemia 
     The present invention further provides methods of use of the biological compositions of the invention. In one embodiment, the biological composition is used as a medicament for treatment of leukemia. In another embodiment, the biological composition is used as a dietary supplement, health food, or health drink. The methods comprise administering an effective amount of the biological composition to a subject in need. The biological composition may be administered orally, in liquid or solid form, or enterally through a feeding tube. As used herein, the term “an effective amount” means an amount sufficient to provide a therapeutic or healthful benefit in the context of leukemia. 
     According to the invention, the biological composition can produce a healthful benefit in a subject suffering from leukemia. Preferably, the subject is a human being. The subject in need is one who is diagnosed with leukemia, with or without metastasis, at any stage of the disease. As used herein, the term “leukemia” includes but is not limited to acute lymphocytic leukemia, acute myeloid leukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, and hairy cell leukemia. 
     The subject may be a leukemia patient who is receiving concurrently other treatment modalities against the leukemia. The subject can be a leukemia patient who had undergone a regimen of treatment (e.g., chemotherapy and/or radiation) and whose cancer is regressing. The subject may be a leukemia patient who had undergone a regimen of treatment and who appears to be clinically free of the leukemia. The biological composition of the invention can be administered adjunctively with any of the treatment modalities, such as but not limited to chemotherapy, radiation, and/or surgery. For example, the biological composition can be used in combination with one or more chemotherapeutic or immunotherapeutic agents, such as amsacrine (AMSA), busulfan (Myleran®), chlorambucil (Leukeran®), cladribine (2-chlorodeoxyadenosine; “2-CDA”; Leustatin®), cyclophosphamide (Cytoxan®), cytarabine (ara-C;Cytosar-U®), daunorubicin (Cerubidine®), doxorubicin (Adriamycin®), etoposide (VePesid®), fludarabine phosphate (Fludara®), hydroxyurea (Hydrea®), idarubicin (Idamycin®), L-asparaginase (Elspar®), methotrexate sodium plus 6-mercaptopurine (6-MP; Purinethol®), mitoxantrone (Novantrone®), pentostatin (2-deoxycoformycin; “DCF”; Nipent®), prednisone, retinoic acid (ATRA), vincristine sulfate (Oncovin®), and 6-thioguanine (Tabloid®). The biological composition can also be used after other regimen(s) of treatment is concluded. 
     The subject may be one who has not yet been diagnosed with leukemia but are predisposed to or at high risk of developing leukemia as a result of genetic factors and/or environmental factors. The subject may also be one who displays characteristics that are associated with a high risk of leukemia, such as nodules detected by computer tomographic scanning or suspect cells in biopsy and/or body fluids. 
     Depending on the subject, the therapeutic and healthful benefits range from inhibiting or retarding the growth of the leukemia and/or the spread of the leukemia to other parts of the body (i.e., metastasis), palliating the symptoms of the cancer, improving the probability of survival of the subject with the cancer, prolonging the life expectancy of the subject, improving the quality of life of the subject, and/or reducing the probability of relapse after a successful course of treatment (e.g., surgery, chemotherapy or radiation). The symptoms associated with leukemia include a weakened immune system, infections, fevers, decrease in red blood cells and platelets, weakness, fatigue, loss of appetite, loss of weight, swollen or tender lymph nodes, liver, or spleen, easy bleeding or bruising, tiny red spots (called petechiae) under the skin, swollen or bleeding gums, sweating (especially at night), bone or joint pain, headaches, vomiting, confusion, loss of muscle control, and seizures. 
     In particular, the invention provides a method for retarding the growth of leukemia cells in a subject, such as a human, comprising administering orally to the subject a biological composition of the invention. The invention also provide a method for prolonging the time of survival of a subject inflicted with leukemia, preferably a human patient, comprising administering orally to the subject a biological composition of the invention. 
     The effective dose will vary with the subject treated. The effective dose for the subject will also vary with the condition to be treated and the severity of the condition to be treated. The dose, and perhaps the dose frequency, will also vary according to the age, body weight, and response of the individual subject. In general, the total daily dose range of activated and conditioned yeast cells for a subject inflicted with leukemia is from about 10 5  to 10 11  cells per day; preferably, about 10 8  to 5×10 10  cells per day; more preferably, about 2×10 9  cells per day in powder form or 9×10 8  to 1×10 10  cells per day in liquid preparations, administered in single or divided doses orally. The length of time for a course of treatment should be at least 1 week, at least 2 weeks, at least 3 weeks, at least 4 weeks, at least 5 weeks, at least 7 weeks, at least 10 weeks, at least 13 weeks, at least 15 weeks, at least 20 weeks, at least 6 months, or at least 1 year. It may be necessary to use dosages outside these ranges in some cases as will be apparent to those skilled in the art. In certain embodiments, the oral compositions can be administered for a period of time until the symptoms and/or infection of the patients by the bacteria and viruses are under control, or when the disease has regressed partially or completely. For use as a dietary supplement, the total daily dose range should be from about 10 5  to 10 11  cells per day; preferably, about 5×10 7  to 5×10 9  cells per day. The oral compositions can be administered as a dietary supplement for as long as 6 months, or in accordance with recommended length of use under the Dietary Supplement Health and Education Act (DSHEA) or other government or industry guidelines. Further, it is noted that the nutritionist, dietician, clinician or treating physician will know how and when to interrupt, adjust, or terminate use of the biological composition as a medicament or dietary supplement in conjunction with individual patient response. 
     The effect of the biological compositions of the invention on development and progression of leukemia can be monitored by any methods known to one skilled in the art, including but not limited to measuring: a) changes in the size and morphology of the tumor using imaging techniques such as a computed tomographic (CT) scan or a sonogram; and b) changes in levels of biological markers of risk for leukemia. 
     5.2.2 Formulations 
     The biological compositions of the present invention comprise activated and conditioned live yeast cells prepared as described above in Section 5.1, as active ingredient, and can optionally contain a pharmaceutically acceptable carrier or excipient, and/or other ingredients provided that these ingredients do not kill or inhibit the yeast cells. Other ingredients that can be incorporated into the biological compositions of the present invention, may include, but are not limited to, herbs (including traditional Chinese medicine products), herbal extracts, vitamins, amino acids, metal salts, metal chelates, coloring agents, flavor enhancers, preservatives, and the like. 
     Any dosage form may be employed for providing the subject with an effective dosage of the oral composition. Dosage forms include tablets, capsules, dispersions, suspensions, solutions, and the like. In one embodiment, compositions of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets, or tablets, each containing a predetermined amount of activated and conditioned yeast cells, as a powder or granules or as a solution or a suspension in an aqueous liquid, a non-aqueous liquid, an oil-in-water emulsion, or a water-in-oil liquid emulsion. In general, the compositions are prepared by uniformly and intimately admixing the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product into the desired presentation. Such products can be used as pharmaceuticals or dietary supplements, depending on the dosage and circumstances of its use. 
     The oral compositions of the present invention may additionally include binding agents (e.g., pregelatinized maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); binders or fillers (e.g., lactose, pentosan, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (e.g., magnesium stearate, talc or silica); disintegrants (e.g., potato starch or sodium starch glycolate); or wetting agents (e.g., sodium lauryl sulphate). The tablets or capsules can be coated by methods well known in the art. 
     Liquid preparations for oral administration can take the form of, for example, solutions, syrups or suspensions, or they can be presented as a dry product for constitution with water or other suitable vehicle before use. The temperature of the liquid used to reconstitute the dried product should be less than 65° C. Such liquid preparations can be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents (e.g., sorbitol syrup, cellulose derivatives or hydrogenated edible fats); emulsifying agents (e.g., lecithin or acacia); non-aqueous vehicles (e.g., almond oil, oily esters, ethyl alcohol or fractionated vegetable oils); and preservatives (e.g., methyl or propyl-p-hydroxybenzoates or sorbic acid). As described below, the preparations can also be made to resemble foods or beverages, containing buffer salts, flavoring, coloring and sweetening agents as appropriate. In certain embodiments, the oral composition is a cell suspension comprising about 10 3  to 10 10  cells per ml. The oral composition can be produced by diluting or concentrating the yeast culture medium produced by the method of Section 5.1.5 as required. In less preferred embodiments, the oral composition is a cell suspension containing about 10 3  to 10 6  cells per ml. In more preferred embodiments, the oral composition is a cell suspension containing greater than about 10 6  to 10′ cells per ml. In most preferred embodiments, the oral composition is a cell suspension containing about 10 6  to 5×10 8  cells per ml. The oral composition can be formulated as a health drink and packaged in liquid containers, each containing a predetermined amount of the liquid yeast culture. Standard methods of quality control and packaging are applied to produce in one embodiment of the invention, oral compositions packaged in liquid containers each comprising about 1 ml, 2 ml, 3 ml, 4 ml, 5 ml, 10 ml, 15 ml, 20 ml, 30 ml, 40 ml, 50 ml, 75 ml, 100 ml, 150 ml, 200 ml, 250 ml, 500 ml, 750 ml, or 1,000 ml of the live yeast cells. The number of container to be taken each day to obtain the total daily dose in a subject depends on the number of activated and conditioned yeast cells contained within each container. For example, a container may comprise 50 ml of liquid with 10 7  cells per ml and when a total daily dose of about 2×10 9  cells per day is desired, a subject can drink 4 containers per day to obtain the desired total daily dose. 
     Generally, because of their ease of administration, tablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers as described above are employed. In a preferred embodiment, the composition is a capsule. The capsules can be formulated by any commercially available methods. In certain embodiments, the composition is a capsule containing 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 40 mg, 50 mg, 75 mg, 100 mg, 150 mg, 200 mg, 300 mg, 400 mg, 500 mg, 600 mg, 700 mg, 800 mg, 900 mg, 1.0 gram, 1.25 gram, 1.5 gram, or 2.0 gram of live yeast cells in powder form. The powder in the capsule comprises about 10 5  to about 10 11  cells per gram; more preferably, about 10 8  to 5×10 10  cells per gram; and most preferably, about 5×10 8  cells per gram. The number of capsule to be taken each day to obtain the total daily dose in a subject depends on the number of activated and conditioned yeast cells contained within each capsule. For example, a capsule may comprise about 500 mg of powder with 5×10 8  cells per gram. To achieve a total daily dose of about 2×10 9  cells per day, a subject can take two capsules at a time for four times per day. 
     In another embodiment, the biological compositions comprising activated and conditioned yeast cells can be added directly to foods so that an effective amount of yeast cells is ingested during normal meals. Any methods known to those skilled in the art may be used to add to or incorporate the biological compositions into natural or processed foods, provided that the activated and conditioned yeast cells remain viable. Preferably, the nutritional compositions of the invention are made and stored under conditions, such as temperature, from about 0° C. to 4° C. As used herein, the term “food” broadly refers to any kind of material, liquid or solid, that is used for nourishing an animal, and for sustaining normal or accelerated growth of an animal including humans. Many types of food products or beverages, such as but not limited to, fruit juice, herbal extracts, tea-based beverages, dairy products, soybean product (e.g., tofu), and rice products, can be used to form nutritional compositions comprising the activated and conditioned yeast cells of the invention. 
     The invention is further defined by reference to the following example describing in detail the animal trials conducted to study the efficacy and safety of activated and conditioned yeast cells of the invention. 
     6. EXAMPLE 
     The following example illustrates the benefit of a biological composition of the invention in a SWI mouse model of human leukemia. The growth of the tumor cells in the mice was studied. 
     Murine transplantable leukemia cell line L6565 closely resembles the human leukemia pathology. See, e.g., Lab Animal and Animal Experiment Techniques, China Chinese Medicine Publisher, 1997, which is incorporated herein by reference in its entirety. 
     The biological composition comprising 10 8  cells per ml of activated and conditioned yeast cells of the strain  Saccharomyces cerevisiae  Hansen strain AS2.11 was prepared by the methods described in Section 5.1 and subsections therein. 
     6.1 Animal Preparation 
     The animals used to generate the leukemia cells for the experiments were SWI mice (obtainable from the Chinese Academy of Military Medicine Science, Beijing, China), both males and females, with an average body weight of about 18 to 22 gram. About 10 6  viable tumor cells of the leukemia cell line L6565 (obtainable from the Cancer Institute, Chinese Academy of Medical Sciences, Beijing, Cancer) in about 0.2 ml spleen cell culture suspension were injected subcutaneously into the animals. 
     6.2 Experimental Design 
     The mice injected with tumor cells were immediately divided into 4 experimental groups of ten mice per group and one control group. The four experimental groups were triplicated (i.e., using a total of 120 mice in the experimental groups). In group AY, the mice received 0.3 ml of the biological composition once per day. In group NY, the mice received 0.3 ml of the untreated yeast cells once per day. In group CTX, the mice were injected subcutaneously with 20 mg of cyclophosphamide (CTX) per kg body weight per day. In group CK1, the mice received 0.3 ml of physiological saline once per day. A fifth group of mice, group CK2, which did not receive tumor cells, was given 0.3 ml of physiological saline per day. 
     The mice received the biological composition, untreated yeast cells, CTX or saline on the same day as the tumor cells were transplanted. The mice in group CK2 also started receiving saline on the same day as the other four groups. The biological composition, untreated yeast cells and saline were administered orally by a feeding tube and the CTX by subcutaneous injection for 21 consecutive days. On the 22 nd  day from tumor inoculation, the mice were sacrificed. The number of tumor cells in the mice were determined by standard techniques. 
     6.3 Results 
     Table 4 shows the differences in the number of tumor cells in the mice of the various treatment and control groups. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                   
                 number of leukemia cells and 
               
               
                   
                 Group 
                 standard deviation (cells/ml) 
               
               
                   
                   
               
             
            
               
                   
                 AY 
                  0.0 ± 0.0 
               
               
                   
                 NY 
                 2,930 ± 798 (all animals died between 
               
               
                   
                   
                 9 to 13 days after injection of 
               
               
                   
                   
                 tumor; the number of tumor cells were 
               
               
                   
                   
                 measured at the time of death) 
               
               
                   
                 CTX 
                   933 ± 241 
               
               
                   
                 CK1 
                 2,860 ± 831 (all animals died between 
               
               
                   
                   
                 9 to 15 days after injection of 
               
               
                   
                   
                 tumor; the number of tumor cells were 
               
               
                   
                   
                 measured at the time of death) 
               
               
                   
                 CK2 
                  0.0 ± 0.0 
               
               
                   
                   
               
            
           
         
       
     
     Like those mice which did not receive tumor cells (group CK2), the mice bearing leukemia cells that received 0.3 ml of the biological composition of the invention (group AY) also did not develop leukemia. In contrast, all of the mice in group CTX (20 mg of CTX per kg body weight per day) developed leukemia and all of the mice in group NY (03 ml of untreated yeast cells per day) and the mice that did not receive treatment (group CK1) died between 9 to 15 days after injection of the tumor. 
     7. EXAMPLE 
     The following example illustrates the benefit of a biological composition of the invention in a SWI mouse model of human leukemia. The survival time of mice after tumor injection and treatment was studied. 
     The biological composition comprising 10 8  cells per ml of activated and conditioned yeast cells of the strain  Saccharomyces cerevisiae  Hansen strain AS2.11 was prepared by the methods described in Section 5.1 and subsections therein. 
     7.1 Animal Preparation 
     The animals were prepared in a similar manner as described in Section 6.1. 
     7.2 Experimental Design 
     The mice injected with tumor cells were kept for 5 days and then were divided into 4 experimental groups of ten mice per group and one control group. The four experimental groups were triplicated (i.e., using a total of 120 mice in the experimental groups). In group 2AY, the mice received 0.3 ml of the biological composition once per day. In group 2NY, the mice received 0.3 ml of the untreated yeast cells once per day. In group 2CTX, the mice were injected subcutaneously with 20 mg of cyclophosphamide (CTX) per kg body weight per day. In group 2CK1, the mice received 0.3 ml of physiological saline once per day. A fifth group of mice, group 2CK2, which did not receive tumor cells, was given 0.3 ml of physiological saline per day. 
     The mice received the biological composition, untreated yeast cells, CTX or saline on the same day as the tumor cells were transplanted. The mice in group CK2 also started receiving saline on the same day as the other four groups. The biological composition, untreated yeast cells and saline were administered orally by a feeding tube and the CTX by subcutaneous injection for 21 consecutive days. The mice were observed over 6 months from the day of tumor inoculation and survival was recorded. The number of tumor cells in the mice were determined by standard techniques. 
     7.3 Results 
     Table 5 shows the number of mice in the various treatment and control group that survived the tumor injection over a period of 6 months. Each of the 30 mice in each group received 21 consecutive days of either untreated yeast cells, CTX, saline or the biological composition of the invention. Table 6 shows the number of tumor cells in the mice in the various treatment and control groups. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Number of live animals remaining in the 
               
               
                 groups after 21 days of treatment 
               
            
           
           
               
               
               
               
               
               
            
               
                 Time after 
                   
                   
                   
                   
                   
               
               
                 cessation of 
                   
                   
                 Group 
                 Group 
                 Group 
               
               
                 treatment 
                 Group 2AY 
                 Group 2NY 
                 2CTX 
                 2CK1 
                 2CK2 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 0 month 
                 30 
                 19 
                 28 
                 17 
                 30 
               
               
                 1 month 
                 30 
                 0 
                 19 
                 0 
                 30 
               
               
                 2 months 
                 30 
                 0 
                 3 
                 0 
                 30 
               
               
                 3 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                 4 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                 5 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                 6 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 6 
               
               
                   
                   
               
               
                   
                   
                 number of leukemia cells and 
               
               
                   
                 Group 
                 standard deviation (cells/ml) 
               
               
                   
                   
               
             
            
               
                   
                 2AY 
                 0.0 ± 0.0 
               
               
                   
                 2NY 
                 all animals dead 
               
               
                   
                 2CTX 
                 all animals dead 
               
               
                   
                 2CK1 
                 all animals dead 
               
               
                   
                 2CK2 
                 0.0 ± 0.0 
               
               
                   
                   
               
            
           
         
       
     
     All of the mice bearing leukemia cells that received 0.3 ml of the biological composition of the invention (group 2AY) survived for more than 6 months and the tumor never reoccurred. On the contrary, all of the mice in group 2NY (0.3 ml of untreated yeast cells per day), group 2CTX (20 mg of CTX per kg body weight per day) and group 2CK1 (0.3 ml of saline per day) died during the experiment. 
     As in Example 6, the mice bearing leukemia cells that received 0.3 ml of the biological composition of the invention (group 2AY) did not develop leukemia. 
     8. EXAMPLE 
     The following example illustrates the benefit of a biological composition of the invention in a T 739  mouse model of leukemia. The growth of the tumor in the mice was studied. Detailed description of the use of T 739  mice to study cancer can be found in, e.g., Niu Q. et al., 2001,  Zhonghua Zhong Liu Za Zhi.  23(5):382–4, and Zheng F. et al., 2000,  Zhonghua Jie He He Hu Xi Za Zhi.  23(1):34–6, each of which is incorporated herein by reference in its entirety. 
     The biological composition comprising 10 8  cells per ml of activated and conditioned yeast cells of the strain  Saccharomyces cerevisiae  Hansen strain AS2.11 was prepared by the methods described in Section 5.1 and subsections therein. 
     8.1 Animal Preparation 
     The animals used to generate the leukemia cells for the experiments were T 739  mouse (obtainable from the Chinese Academy of Military Medicine Sciences, Beijing, China), both males and females, with an average body weight of about 18 to 22 gram. About 10 6  viable tumor cells of the leukemia cell line T 739  in about 0.2 ml culture suspension were injected subcutaneously into the animals. 
     8.2 Experimental Design 
     The mice injected with tumor cells were immediately divided into 4 experimental groups of ten mice per group and one control group. The four experimental groups were triplicated (i.e., using a total of 120 mice in the experimental groups). In group AY, the mice received 0.3 ml of the biological composition once per day. In group NY, the mice received 0.3 ml of the untreated yeast cells once per day. In group CTX, the mice were injected subcutaneously with 20 mg of cyclophosphamide (CTX) per kg body weight per day. In group CK1, the mice received 0.3 ml of physiological saline once per day. A fifth group of mice, group CK2, which did not receive tumor cells, was given 0.3 ml of physiological saline per day. 
     The mice received the biological composition, untreated yeast cells, CTX or saline on the same day as the tumor cells were transplanted. The mice in group CK2 also started receiving saline on the same day as the other four groups. The biological composition, untreated yeast cells and saline were administered orally by a feeding tube and the CTX by subcutaneous injection for 21 consecutive days. On the 22 nd  day from tumor inoculation, the mice were sacrificed. The number of tumor cells in the mice were determined by standard techniques. 
     8.3 Results 
     Table 7 shows the differences in the number of tumor cells in the mice of the various treatment and control groups. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 7 
               
               
                   
                   
               
               
                   
                   
                 number of leukemia cells and 
               
               
                   
                 Group 
                 standard deviation (cells/ml) 
               
               
                   
                   
               
             
            
               
                   
                 AY 
                 0.0 ± 0.0 
               
               
                   
                 NY 
                 2,032 ± 643 (all animals died between 
               
               
                   
                   
                 10 to 15 days after injection of 
               
               
                   
                   
                 tumor; the number of tumor cells were 
               
               
                   
                   
                 measured at the time of death) 
               
               
                   
                 CTX 
                   957 ± 132 
               
               
                   
                 CK1 
                 2,087 ± 712 (all animals died between 
               
               
                   
                   
                 11 to 17 days after injection of 
               
               
                   
                   
                 tumor; the number of tumor cells were 
               
               
                   
                   
                 measured at the time of death) 
               
               
                   
                 CK2 
                 0.0 ± 0.0 
               
               
                   
                   
               
            
           
         
       
     
     Like those mice which did not receive tumor cells (group CK2), the mice in group bearing leukemia cells that received 0.3 ml of the biological composition of the invention (group AY) also did not develop leukemia. In contrast, all of the mice in group CTX (20 mg of CTX per kg body weight per day) developed leukemia and all of the mice in group NY (03 ml of untreated yeast cells per day) and the mice that did not receive treatment (group CK1) died between 10 to 17 days after injection of the tumor. The mice bearing leukemia cells that received 0.3 ml of the biological composition of the invention (group AY) showed the least deviation in the weight of mice as compared to healthy mice not injected tumor cells (group CK2). The mice in group AY also had less tumor mass as compared to mice that did not receive treatment (group CK1) as well as the mice in group NY (0.3 ml of untreated yeast cells per day) and the mice in group CTX (30 mg of cyclophosphamide per kg body weight per day). 
     9. EXAMPLE 
     The following example illustrates the benefit of a biological composition of the invention in a T 739  mouse model of leukemia. The survival time of the rats after tumor injection and treatment was studied. 
     The biological composition comprising 10 8  cells per ml of activated and conditioned yeast cells of the strain  Saccharomyces cerevisiae  Hansen strain AS2.11 was prepared by the methods described in Section 5.1 and subsections therein. 
     9.1 Animal Preparation 
     The animals were prepared in a similar manner as described in Section 8.1. 
     9.2 Experimental Design 
     The mice injected with tumor cells were immediately divided into 4 experimental groups of ten mice per group and one control group. The four experimental groups were triplicated (i.e., using a total of 120 mice in the experimental groups). In group 2AY, the mice received 0.3 ml of the biological composition once per day. In group 2NY, the mice received 0.3 ml of the untreated yeast cells once per day. In group 2CTX, the mice were injected subcutaneously with 20 mg of cyclophosphamide (CTX) per kg body weight per day. In group 2CK1, the mice received 0.3 ml of physiological saline once per day. A fifth group of mice, group 2CK2, which did not receive tumor cells, was given 0.3 ml of physiological saline per day. 
     The mice received the biological composition, untreated yeast cells, CTX or saline on the same day as the tumor cells were transplanted. The mice in group CK2 also started receiving saline on the same day as the other four groups. The biological composition, untreated yeast cells and saline were administered orally by a feeding tube and the CTX by subcutaneous injection for 21 consecutive days. The mice were observed over 6 months from the day of tumor inoculation and survival was recorded. The number of tumor cells in the mice were determined by standard techniques. 
     9.3 Results 
     Table 8 shows the number of mice in the various treatment and control group that survived the tumor injection over a period of 6 months. Each of the 30 mice in each group received 21 consecutive days of either untreated yeast cells, CTX, saline or the biological composition of the invention. Table 9 shows the number of tumor cells in the mice in the various treatment and control groups. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Number of live animals remaining in the 
               
               
                 groups after 30 days of treatment 
               
            
           
           
               
               
               
               
               
               
            
               
                 Time after 
                   
                   
                   
                   
                   
               
               
                 cessation of 
                   
                 Group 
                 Group 
                 Group 
                   
               
               
                 treatment 
                 Group 2AY 
                 2NY 
                 2CTX 
                 2CK1 
                 Group 2CK2 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 0 month 
                 30 
                 0 
                 28 
                 0 
                 30 
               
               
                 1 month 
                 30 
                 0 
                 19 
                 0 
                 30 
               
               
                 2 months 
                 30 
                 0 
                 3 
                 0 
                 30 
               
               
                 3 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                 4 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                 5 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                 6 months 
                 30 
                 0 
                 0 
                 0 
                 30 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 9 
               
               
                   
                   
               
               
                   
                   
                 number of leukemia cells and 
               
               
                   
                 Group 
                 standard deviation (cells/ml) 
               
               
                   
                   
               
             
            
               
                   
                 2AY 
                 0.0 ± 0.0 
               
               
                   
                 2NY 
                 all animals dead 
               
               
                   
                 2CTX 
                 all animals dead 
               
               
                   
                 2CK1 
                 all animals dead 
               
               
                   
                 2CK2 
                 0.0 ± 0.0 
               
               
                   
                   
               
            
           
         
       
     
     All of the mice bearing leukemia cells that received 0.3 ml of the biological composition of the invention (group 2AY) survived for more than 6 months and the tumor never reoccurred. On the contrary, all of the mice in group 2NY (0.3 ml of untreated yeast cells per day), group 2CTX (20 mg of CTX per kg body weight per day) and group 2CK1 (0.3 ml of saline per day) died during the experiment. 
     As in Example 8, the mice bearing leukemia cells that received 0.3 ml of the biological composition of the invention (group 2AY) did not develop leukemia. 
     10. EXAMPLE 
     The following example illustrates the benefit of a biological composition of the invention in regulating cell changes in a leukemia cell line HL-60. The leukemia cell line HL-60 is commonly used to establish the efficacy of a treatment. See, e.g., Modern Pharmacology Experimental Protocols, Peking Union Medical College Publisher, 1998. 
     Flow cytometry was used to study the changes in cell cycles. Flow cytometry measures the number of cells in different cell cycles by analyzing the amount of DNA in a single cell. A fluorescent dye, propidium iodide (PI) intercalates with DNA and emits yellow and red regions fluorescence in response to 488 nm excitation. Cells in the G1 and G0 cell cycle phases will contain a 2n amount of DNA. Cells in the G2 and M phases will contain a 4n amount of DNA, while cells in S phase will have a DNA content between 2n and 4n (as the DNA has only partially been replicated). In particular, flow cytometry can be used to determine the percentage of live cells in each phase of the cell cycle and the percentage of dead cells. This information, coupled with the doubling time, allows one to calculate the length of each cell cycle phase. More detailed description of the methodologies and applications of flow cytometry can be found in Darzynkiewicz et al., 2001,  Clin Lab Med.  21(4):857–73, which is incorporated by reference herein in its entirety. 
     The biological composition comprising 10 8  cells per ml of activated and conditioned yeast cells of the strain  Saccharomyces cerevisiae  Hansen strain AS2.11 was prepared by the methods described in Section 5.1 and subsections therein. 
     10.1 Experimental Design 
     Activated HL-60 leukemia cells (obtainable from the Cancer Institute, Chinese Academy of Military Medical Sciences, Beijing, China) were cultured in RPMI-1640 suspension and then divided into 3 groups of 10 9  cells per group. The three groups of HL-60 cells were quintuplicated. Detailed description of the cultivation of human leukemia HL-60 cells can be found in, e.g., Saether A. K. et al., 1991,  Eur J. Cell Biol.  55(2):346–51, which is incorporated by reference herein in its entirety. 
     In the experimental group AY, the biological composition was filtered through 0.22 μm filter. The activated and conditioned yeast cells (about 5 μm in width and 10 μm in length) were collected and added to 10 9  HL-60 leukemia cells per ml to make 5% final concentration by weight. In the comparative group NY, the untreated yeast cells were filtered through 0.22 μm filter. The untreated yeast cells (about 5 μm in width and 10 μm in length) were collected and added to 10 9  HL-60 leukemia cells per ml to make 5% final concentration by weight. In the control group CK, 10 9  HL-60 leukemia cells per ml was used. 
     Each group of cells were observed after culturing for 24 hours and 72 hours. Afterwards, the cells were stained with propidium iodide and the percentage of cells at different cell cycle stages were observed using flow cytometry. Detailed description of the use of flow cytometry to study different cell cycle stages can be found in Hagisawa S. et al.,  Med Electron Microsc.  1999;32(3):167–174). 
     10.2 Results 
     Tables 10 and 11 show the percentages of live leukemia cells in each cell cycle and the percentages of dead leukemia cells in the treatment and control groups after culturing for 24 hours and 72 hours, respectively. 
     
       
         
           
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                 Percentages of live leukemia cells and 
               
               
                 dead leukemia cells after 24 hours 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Cell Cycle 
                 AY 
                 NY 
                 CK 
               
               
                   
                 Stage 
                 (% of cells) 
                 (% of cells) 
                 (% of cells) 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 G 0 –G 1   
                 28.9% 
                 33.2% 
                 33.0% 
               
               
                   
                 S 
                 50.8% 
                 44.4% 
                 44.3% 
               
               
                   
                 G 2 –M 
                 20.3% 
                 22.4% 
                 22.6% 
               
               
                   
                 Programmed 
                 24.7% 
                 3.2% 
                 3.1% 
               
               
                   
                 Cell Death 
               
               
                   
                   
               
            
           
         
       
     
     After culturing the HL-60 leukemia cells with the activated and conditioned yeast cells for 24 hours (group AY), 24.7% of the HL-60 leukemia cells were dead and 75.3% of the leukemia cells were alive (100%−24.7%). Out of the total number of live leukemia cells, 28.9% were in G 0 –G 1  stage; 50.8% were in S stage; and 20.3% were in G 2 -M stage, i.e., 28.9%+50.8%+20.3%=100% (total live leukemia cells). 
     In contrast, after culturing the HL-60 leukemia cells with untreated yeast cells for 24 hours (group NY), 3.2% of the leukemia cells were dead and 96.8% of the leukemia cells were alive (100%−3.2%). Out of the total number of live leukemia cells, 33.2% were in G 0 –G 1  stage; 44.4% were in S stage; and 22.4% were in G 2 -M stage, i.e., 33.2%+44.4%+22.4%=100% (total live leukemia cells). 
     Similarly, after culturing the HL-60 leukemia cells alone for 24 hours (group CK), only 3.1% of the leukemia cells were dead and 96.9% of the leukemia cells were alive (100%−3.1%). Out of the total number of live leukemia cells, 33.0% were in G 0 –G 1  stage; 44.3% were in S stage; and 22.6% were in G 2 -M stage, i.e., 33.0%+44.3%+22.6%=99.9% (total live leukemia cells). 
     After 24 hours, the percentage of programmed cell death is significantly greater (8×) when the HL-60 leukemia cells were co-incubated with the activated and conditioned yeast cells of the present invention (24.7% in group AY) than when the HL-60 leukemia cells were co-incubated with the untreated yeast cells (3.2% in group NY) or cultured alone (3.1% in group CK). At 24 hours, co-incubation with the activated and conditioned yeast cells of the present invention have already begun to reduce the number of live leukemia cells. A significant number of live leukemia cells in all three groups were at S stage, i.e., when DNA replication occurs (synthesis phase). 
     
       
         
           
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 Percentages of live leukemia cells and 
               
               
                 dead leukemia cells after 72 hours 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Cell Cycle 
                 AY 
                 NY 
                 CK 
               
               
                   
                 Stage 
                 (% of cells) 
                 (% of cells) 
                 (% of cells) 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 G 0 –G 1   
                 56.2% 
                 41.6% 
                 41.3% 
               
               
                   
                 S 
                 36.1% 
                 40.2% 
                 40.7% 
               
               
                   
                 G 2 –M 
                 7.7% 
                 18.2% 
                 18.0% 
               
               
                   
                 Programmed 
                 85.2% 
                 11.6% 
                 11.3% 
               
               
                   
                 Cell Death 
               
               
                   
                   
               
            
           
         
       
     
     After culturing the HL-60 leukemia cells with the activated and conditioned yeast cells for 72 hours (group AY), 85.2% of the leukemia cells were dead and 14.8% of the leukemia cells were alive (100%−85.2%). Out of the total number of live leukemia cells, 56.2% were in G 0 –G 1  stage; 36.1% were in S stage; and 7.7% were in G 2 -M stage, i.e., 56.2%+36.1%+7.7%=100% (total live leukemia cells). 
     In contrast, after culturing the HL-60 leukemia cells with untreated yeast cells for 72 hours (group NY), 11.6% of the leukemia cells were dead and 88.4% of the leukemia cells were alive (100%−11.6%). Out of the total number of live leukemia cells, 41.6% were in G 0 –G 1  stage; 40.2% were in S stage; and 18.2% were in G 2 -M stage, i.e., 41.6%+40.2%+18.2%=100% (total live leukemia cells). 
     Similarly, after culturing the HL-60 leukemia cells alone for 72 hours (group CK), only 11.3% of the leukemia cells were dead and 88.7% of the leukemia cells were alive (100%−11.3%). Out of the total number of live leukemia cells, 41.3% were in G 0 –G 1  stage; 40.7% were in S stage; and 18.0% were in G 2 -M stage, i.e., 41.3%+40.7%+18.0%=100.0% (total live leukemia cells). 
     After 72 hours, the percentage of programmed cell death is still significantly greater (8×) when the HL-60 leukemia cells were co-incubated with the activated and conditioned yeast cells of the present invention (85.2% in group AY) than when the HL-60 leukemia cells were co-incubated with the untreated yeast cells (11.6% in group NY) or cultured alone (11.3% in group CK). The percentage of programmed cell deaths in group AY increased more than three-folds from 24.7% to 85.2%, suggesting that the activated and conditioned yeast cells of the present invention are extremely effective in reducing the number of live leukemia cells. Further, more than half of the live leukemia cells in group AY at 72 hours (56.2%) are now in G 0 –G 1  stage, i.e., a temporary or permanent resting period where the cell has reached an end stage of development and will no longer divide. 
     The present invention is not to be limited in scope by the specific embodiments described which are intended as single illustrations of individual aspects of the invention, and functionally equivalent methods and components are within the scope of the invention. Indeed, various modifications of the invention, in addition to those shown and described herein, will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to fall within the scope of the appended claims. 
     All publications, patents and patent applications mentioned in this specification are herein incorporated by reference into the specification to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference.