bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies with the Folate Binding Protein in Chronic Granulocytic Leukaemia Cells: I. SYNTHESIS AND RELEASE OF BINDER BY CELLS IN SHORT‐TERM CULTURE
Authors: COSTA MARIA DA , ROTHENBERG SHELDON P. 
Published: March 2008

Summary. Chronic granulocytic leukaemia (CGL) cells which contained a high concentration of unsaturated folate binding protein were incubated in suspension culture for a period of 5 h. Cell samples were periodically assayed for binder and these demonstrated active synthesis which was inhibited by puromycin, cyclo‐heximide, N‐ethylmaleimide, and by incubation at 4°, but not by actinomycin D.Folate binding activity could also be demonstrated in the culture medium and this increased with the duration of incubation. This release of binder was inhibited by culturing the cells at 4° and by the addition of N‐ethylmaleimide, but not by actinomycin D, puromycin, or cycloheximide.When the pre‐ and post‐culture cell lysates were saturated with tritiated folic acid ([3H]PteGlu) and subjected to chromatography on DEAE‐agarose, approximately half of the bound folate eluted with 0.001 M phosphate buffer at pH 6.0 and the other half eluted with 0.2 M buffer at pH 7.2. The culture medium and plasma from this patient with CGL as well as serum from two normal subjects saturated with [3H]PteGlu and similarly chromatographed contained primarily the acidic binder and much less of the binder eluting with the low molarity buffer.Since a folate binding protein immunochemically similar to the binder in CGL cells has been identified in the serum of non‐leukaemic subjects, these experiments suggest that the source of circulating folate binding protein may be the immature granulocyte.
Megakaryocytes and the Heterogeneity of Circulating Platelets
Authors: PENINGTON D. G. , STREATFIELD K. , ROXBURGH A. E. 
Published: March 2008

Summary. Megakaryocytes mature to the point of cytoplasmic disintegration in three principal ploidy classes: 8n, 16n and 32n. Cells of each of these ploidy classes have been identified, using both microdensitometry and measurement of cell volume and submitted to morphometric analysis. Mature megakaryocytes of the three ploidy classes have been shown to differ in the concentration of cytoplasmic constituents which would be expected to relate to the buoyant density of their platelet progeny. Density separated platelets have been similarly analysed. Light platelets correspond with the 32n megakaryocytes and are more liberally endowed with surface connected canalicular system than the progeny of the common 16n megakaryocytes; it is proposed that they have functional characteristics related to this finding. Dense platelets, which are larger in size, correspond with 8n megakaryocytes and show a greater content of granules and mitochondria than platelets of average density. These platelets most probably show specialized function relating to release of granule constituents.Fragments of cytoplasm released from megakaryocytes represent one form of ‘megathrombocyte’equated by others with newly formed platelets. The differences in structure between these fragments and circulating platelets are emphasized; each such fragment must undergo further disintegration into a number of platelets. It is suggested that the heterogeneity of circulating platelets with respect to both size and density stems from the origin of platelets of varying density from the different populations of megakaryocyte and their release in the form of large cytoplasmic fragments rather than as platelets.
Benzene Inhibition of in Vitro Rabbit Reticulocyte Haem Synthesis at Delta Aminolaevulinic Acid Synthetase: Reversal of Benzene Toxicity by Pyridoxine
Authors: Freedman Michael L. , Wildman Joseph M. , Rosman Judith , Eisen Jane , Greenblatt David R. 
Published: March 2008

Benzene (0.113 M) inhibited haem and protein synthesis in rabbit reticulocytes. This inhibition of haem synthesis was found when L‐2‐[14C]‐glycine was used as the radioactive precursor. However, when 4‐[14C]Δ‐aminolaevulinic acid (ALA) was used, there was no significant inhibition. Since ALA measures the haem synthetic pathway beyond the enzyme Δ‐aminolaevulinic acid synthetase (ALA synthetase), these results suggest that benzene inhibits haem synthesis at or before ALA synthetase. This was confirmed by demonstrating that 1 mM ALA both protected against and reversed the benzene inhibition of reticulocyte protein synthesis. In addition, 1 mM pyridoxine both protected against and reversed the benzene inhibition of reticulocyte haem and protein synthesis. These results indicate that benzene (or a metabolite) either competes with pyridoxal phosphate at ALA synthetase or competes with pyridoxine for pyridoxal phosphokinase.These results are discussed in terms of their implications for the possible roles of ALA synthetase and the haemin‐controlled repressor in benzene‐induced aplastic anaemia.
Simultaneous Presence of Receptors for Complement and Sheep Red Blood Cells on Human Fetal Thymocytes
Authors: Stein H. , Müller‐hermelink H. K. 
Published: March 2008

The cells of four thymus glands, two at 12 weeks, one at 16 weeks and one at 22 weeks gestational age, were examined cytochemically for enzymic activity and for surface markers. The reactions for chloroacetate esterase, peroxidase, and alkaline phosphatase were negative and the reaction for nonspecific esterase was only weakly positive in some of the cells. In contrast, nearly all thymocytes at the 12th gestational week showed strong focal acid phosphatase (acP) activity. The number of acP‐stainable cells and the staining intensity declined progressively. A high percentage of thymocytes in early fetal life express a complement receptor (CR); the proportion of CR‐bearing cells decreased while cells forming rosettes with sheep erythrocytes (possessing erythrocyte receptors: ER) correspondingly increased during fetal life. Using a mixed rosette assay, up to 30% of the thymocytes at 12 weeks gestation were found to bear CR and ER simultaneously. The number of CR‐and ER‐positive cells also declined progressively with fetal age.These findings show that CR‐positive, ER‐negative thymus cells mature into CR‐negative, ER‐positive thymocytes via a CR‐positive and ER‐positive intermediate cell, indicating that mature ER‐positive thymocytes do not originate from another cell line lacking CR. The changes in surface markers during early T cell maturation is relevant to certain lymphomas whose cells also show strong focal acP activity and also express both CR and ER. These lymphoma cells may correspond to fetal thymocytes or T precursor cells present in small numbers after birth.
Studies of von Willebrand Factor: Effects of Different Kinds of Carbohydrate Oxidases, SH‐Inhibitors and some other Chemical Reagents
Authors: Fukui H. , Mikami S. , Okuda T. , Murashima N. , Takase T. , Yoshioka A. 
Published: March 2008

The effects of several kinds of carbohydrate oxidase, SH‐inhibitors and some other chemical reagents on the activities of von Willebrand factor, factor VIII procoagulant and factor VIII‐related antigen were studied.Factor VIII procoagulant and von Willebrand factor activities were both inhibited by galactose oxidase, p‐hydroxymercuribenzoic acid, 2,4,6‐trinitrobenzensulfonic acid and sodium periodate. α‐mannosidase, N‐ethylmaleimide and phospholipase C inactivated factor VIII procoagulant but not von Willebrand factor activity. Dithiothreitol had little effect on factor VIII procoagulant activity but reduced significantly that of von Willebrand factor. It is suggested that galactose and the thiol and α‐aminogroup groups of lysine may play an important role in both factor VIII procoagulant and von Willebrand factor activity. Mannose may be responsible for the factor VIII procoagulant activity but not for the von Willebrand factor activity.The Laurell rocket heights of factor VIII‐related antigen rose with increasing concentration of galactose oxidase, 2,4,6‐trinitrobenzenesulfonic acid or sodium periodate. Gel filtration experiments showed that factor VIII‐related antigen may be dissociated into subunits by galactose oxidase but not by 2,4,6‐trinitrobenzenesulfonic acid or sodium periodate.
Aspects of Folate Metabolism in Renal Failure
Authors: Retief F. P. , Heyns A. du P. , Oosthuizen Mariëtha , van Reenen O. R. 
Published: March 2008

Plasma and urine folate fractions were evaluated after ingestion of radio‐active N5‐methyl‐tetrahydrofolic acid by a normal control (subject 1), a patient on maintenance haemodialysis for chronic glomerulonephritis (subject 2), and an anephric patient on haemodialysis (subject 3). In subjects 1 and 2 maximal plasma radiofolate peaks appeared within 1 h of isotope ingestion. In subject 3 the radio‐folate peak was delayed for 6 h although the total biofolate fraction reached a maximum at 0.5 h (comparable with findings in subject 2). Sephadex DEAE A50 chromatography showed the radiofolate fraction in subject 1 to be compatible with N5‐methyl‐tetrahydrofolic acid (peak 1). In subject 2 additional radiofolate peaks 2 and 3 were found. The nature of peak 2 is unknown but peak 3 may represent 10‐formyl‐tetrahydrofolate. Peak 1 was minimally present in subject 3. This limited study suggests a defect of methyl‐tetrahydrofolate metabolism in the anephric state unassociated with defective renal excretion per se.In normal urine, peak 2 predominated while urine of subject 2 had a predominant peak 3 and lesser peaks 1 and 2. Compared with the control, uraemic subjects 2 and 3 showed greatly decreased dialysis‐resistant (bound) plasma radiofolate fractions; all urinary radiofolates were fully dialysable. The unexplained radiofolate ‘binder’detected with haemoglobin‐coated charcoal adsorption in urine (subject 2) and occasionally in plasma, probably represents an artefact. Plasma from 27 uraemic subjects showed no abnormal in vitro radiofolate binding capacity.
Kinetics of Erythroid and Myeloid Stem Cells in Post‐Hypoxia Polycythaemia
Authors: Peschle C. , Magli M. C. , Cillo C. , Lettieri F. , Genovese A. , Pizzella F. , Soricelli A. 
Published: March 2008

Summary. The number of erythroid burst‐ (BFU‐E) and colony‐forming units (CFU‐E), as well as of myeloid‐macrophage colony‐forming units (CFU‐C), has been evaluated in tibial marrow and spleen of ex‐hypoxic polycythaemic mice, at sequential time intervals after the end of hypoxia.In both marrow and spleen, the kinetics of the CFU‐E pool is characterized by a sharp fall from above normal to lower than normal values. BFU‐E and CFU‐C however rise from below normal to higher than normal levels. These results have been correlated with both the erythropoietin (Ep) and the erythropoietic activity curves.It is apparent that Ep levels largely control both the differentiation and the amplification of the CFU‐E pool and it is suggested that Ep may act as a ‘survival factor’ at the CFU‐E level and/or increase the flow of cells from BFU‐E to CFU‐E.The difference in response between CFU‐E and BFU‐E favours a clearcut distinction between these populations, whereas the similarity between the BFU‐E and CFU‐C response suggests a close relationship between these two cell populations.It is also of interest that the murine spleen functions as a large reservoir of erythroid microenvironment for hypoxia‐induced stress erythropoiesis.
Characteristics of Various Factor VIII Concentrates used in Treatment of Haemophilia A
Authors: Nilsson I. M. , Hedner U. 
Published: March 2008

Summary.Five different factor VIII concentrates, AHF‐Kabi (fraction I‐o), Krynativ‐Kabi (freeze‐dried cryoprecipitate), Hemofil‐Hyland, AHF‐profilate‐Abbott, Kryobulin‐Immuno, available in Sweden for treatment of haemophiliacs were compared with respect toin vivorecovery, half‐life of factor VIII clotting activity (VIII:C) andin vitroproperties. The parameters studied were VIII:C, factor VIII related antigen (VIIIR:AG), crossed immunoelectrophoresis, ristocetin co‐factor activity (VIII: Rcof), fibrinogen content and factor XIII activity. AHF‐Kabi had the lowest concentration of VIII:C. All the preparations had higher values for VIIIR:AG than for VIII:C. The quotient was highest for Hemofil, Krynativ‐Kabi and Kryobulin and varied between 4 and 7. The lowest quotient, 1.3 to 4, was that of AHF‐Kabi. The number of units of VIII: Rcof was almost the same as that of VIII:C. AHF‐Kabi had the highest fibrinogen concentration and was the only preparation with high amounts of F XIII. In crossed immunoelectrophoresis AHF‐Kabi showed a similar pattern to that of normal plasma. The other preparations had a different pattern suggesting less heterogenicity of the molecule. Thein vivorecovery was about the same for all the concentrates. The disappearance rate of VIII:C after infusion of corresponding doses of the different concentrates was studied in six patients with severe haemophilia A who were not bleeding. AHF‐Kabi had a half‐life between 18 and 26 h which was substantially longer than any of the other preparations. The half‐life of Hemofil, Krynativ‐Kabi, AHF‐Profilate and Kryobulin varied between 8 and 16 h. The concentrates were given to three patients with severe classical von Willebrand's disease. All the preparations caused an increase of VIII:C and VIIIR:AG as well as of VIII:Rcof, but only AHF‐Kabi corrected the prolonged bleeding time.Knowledge of the properties of various VIII concentrates is of importance for the choice of treatment in haemophilia and von Willebrand's disease.
The Effect of Thiamphenicol on the Production of Immature Red Blood Cells under Anaemic Conditions
Authors: Nijhof W. , Wierenga P. K. , Kardaun S. 
Published: March 2008

Summary. The toxic action of thiamphenicol was demonstrated in normal and phlebotomized rabbits. Thiamphenicol administration to normal rabbits resulted in a reduction of the number of reticulocytes and eventually to a decrease in the total red cell count. In rabbits made anaemic thiamphenicol did not prevent a reticulocyte crisis. The rate of synthesis of haemoglobin and the total amount of ribosomes in these reticulocytes were low. The disome was the most abundant polysome. This was in contrast with the findings of reticulocytes from control rabbits. Shortly after the thiamphenicol administration reticulocytes appeared with propcrties comparable with those from control rabbits.Besides the impairment of reticulocyte production a decrease in the total cellularity of the marrow was shown. The erythroid, granuloid and lymphoid cell lines appeared to be all affected. However, only the red cells showed a distinct shift from young to old erythroblasts. The inhibition of red cell production was not caused by a deficiency of erythropoietin since the levels were extremely high during thiamphenicol administration. From these findings it is concluded that one of the major effects of thiamphenicol is the inhibition of the conversion of the committed stem cell to proerythroblasts.
Adenosine Deaminase (ADA) Activity in Lymphocytes of Normal Individuals and Patients with Chronic Lymphatic Leukaemia
Authors: Ramot B. , Brok‐Simoni F. , Barnea N. , And I. Bank , Holtzmann F. 
Published: March 2008

Summary. Adenosine dcamiiiase (adenosine aminohydrolase, ADA) activity was found to be low in lymphocytes of chronic lymphatic leukaemia (CLL) patients compared to normal lymphocytes. This was determined on 42 controls and 49 CLL patients. The mean activity in normal lymphocytes was found to be 4.35±3.34 μmol/h/108 cells while in CLL cells it was 2.45±2.54 μmol/h/108 cells.The association of red cell adenosine deaininase (ADA) deficiency with the autosomal recessive form of combined immune deficiency syndrome has been well established (Giblett & Anderson, 1972; Knudsen & Dissing, 1973; Meuwissen et al, 1975). Low levels of ADA were also described in children with acute lymphatic leukaemia in relapse and remission as well as in their parents (Zimmer et al, 1974). Since an immunologic handicap frequently evolves during the course of chronic lymphatic leukaemia (CLL), it is of special interest to determine the activity of this enzyme in lymphocytes of such patients as compared to normals.
Immunological Studies in Combined Factor V and Factor VIII Deficiency
Authors: Giddings J. C. , Seligsohn U. , Bloom A. L. 
Published: March 2008

SUMMARY.Plasma samples from patients with inherited combined factor V and factor VIII deficiency were examined by immunological methods for the presence of factor V and factor VIII‐related antigens. A factor V‐related antigen was consistently demonstrated in all plasma samples by inhibitor neutralization assay using a non‐precipitating rabbit antibody. Factor VIII‐related antigens were detected by inhibitor neutralization using human antibody and by electroimmunoassay using a precipitating rabbit antibody. The amounts of factor V and factor VIII‐related antigens present in the patient's samples were similar to those found in normal human plasma. The findings confirm the presence of normal levels of factor VHI‐related antigen in the plasma of these patients and suggest that inactive antigenic determinants of procoagulant factor V and procoagulant factor VIII are also present. The results are consistent with the possibility that a common precursor of procoagulant factor V and factor VIII is defective in these patients.
Assay of Ristocetin Co‐factor using Fixed Platelets and a Platelet Counting Technique
Authors: Evans R. J. , Austen D. E. G. 
Published: March 2008

SUMMARY.A new assay of ristocetin co‐factor has been developed which is based on platelet counting using a Coulter Counter. A modified method of washing and fixing platelets has also been devised to provide a suitable platelet preparation which can be used in this assay. These fixed platelets have consistently proved to be satisfactory and have given high levels of maximum percentage aggregation. They have been stored for periods up to 6 months without significant deterioration. The method of platelet counting is simple in operation and sensitive to relatively low levels of platelet aggregation. It is precise and seems to offer distinct advantages over existing methods.
Heterogeneity of Rabbit Platelets
Authors: Karpatkin S. 
Published: March 2008

Rabbits were injected intravenously with a cohort platelet label, 75Se‐selenomethionine. Platelet‐rich plasma was separated into five different platelet density fractions on each of seven days by repetitively centrifuging the same sample of platelet‐rich plasma at increasing gravitational force. The heaviest platelet sediment fraction was enriched with larger platelets. The lightest platelet sediment fraction was enriched with smaller platelets. Incorporation of isotope into the heaviest platelet fraction was considerably greater than incorporation into the lightest platelet fraction, i.e. heavy‐light specific activity ratio was 9.63, on day 1. The ratio of the heaviest platelet fraction specific activity to the specific activities of the platelets sedimented at higher g forces (lighter‐smaller platelets), generally decreased on each day for 4–6 d by a factor of 2.8–7.0‐fold. Whereas incorporation of isotope into the heaviest platelet fraction declined on days 3–4, incorporation into the lightest three fractions remained the same. Cohort platelet survival curves revealed a significant lag period of 1–2 d for the incorporation of isotope into the lightest three platelet fractions compared to the heaviest two platelet fractions. The mean platelet survival of the lightest two fractions was significantly shorter than the mean platelet survival of the heaviest three fractions.SDS‐polyacrylamide gel electrophoresis of the platelet cell sap of the five platelet fractions generally revealed 10 prominent protein bands for the heaviest platelet fractions. The lightest platelet fraction, which comprised 16% of the harvested platelet population, had six absent to markedly diminished platelet proteins of modecular weights between 142 000 and 46 000 daltons.The data are compatible with two models: (1) Heavy‐large platelets are, on average, young platelets which become lighter‐smaller platelets while losing platelet membrane and cell sap components with time. (2) Heavy‐large platelets and light‐small platelets are produced independently by specific megakarocytes. The heavy‐large platelets incorporate more isotope than lighter‐smaller platelets (possibly because of their megakarocyte precursor). However, they are released earlier into the circulation than lighter‐smaller platelets and are therefore younger platelets.
The Control of Hepatic Iron Uptake: Correlation with Transferrin Synthesis
Authors: Morton A. G. , Tavill A. S. 
Published: March 2008

Summary. The control of hepatic iron uptake was studied in the perfused liver isolated from rats subjected to nutritional iron deficiency. The total hepatic iron uptake and incorporation into ferritin was found to be higher in iron deficiency and during the 48 h of oral refeeding with iron than in the normal state. Specific incorporation of iron into ferritin from a perfusate of normal transferrin iron saturation was enhanced in nutritional iron deficiency as compared to controls after 5 h of perfusion but not after 1 h, suggesting that increased uptake of iron from the perfusate may play a role in stimulating hepatic ferritin synthesis and assembly. This promotion of uptake into ferritin was inhibited by cycloheximide suggesting that enhanced incorporation of iron is dependent upon de novo synthesis of apoferritin. In control, nutritionally iron deficient and iron‐refed rats there was a significant, direct correlation between the transferrin‐iron saturation of the perfusate at physiological transferrin concentrations and total hepatic iron uptake after 5 h perfusion.A significant positive correlation was found between the hepatic total and ferritin iron uptake and the transferrin synthetic rate measured in the same liver. It is proposed that in the liver the negative feedback of iron supply on transferrin synthesis may be linked with a positive feedback on ferritin synthesis. The timecourse of these reciprocal responses suggests a role for hepatic ferritin and/or a component of the non‐haem, non‐ferritin iron pool in the regulation of transferrin synthesis.
Malignant Histiocytosis: A Clinico‐pathological Study of 12 Cases
Authors: Lampert I. A. , Catovsky D. , Bergier N. 
Published: March 2008

SUMMARY The clinico‐pathological features of 12 cases of inalignant histiocytosis (histiocytic medullary reticulosis), aged 12–60 years, were studied. Special emphasis wx put on the analysis of the hacmatological, cytological and histopathological findings of the disease.Bone marrow aspirates and biopsies from involved tissues (liver, lymph node, spleen and skin) were found best suited for establishing the diagnosis. Cytochemical and ultrastructural data support the concept that the neoplastic cells belong to the mononuclear‐phagocyte system.Three untreated patients died in less than 6 months. Median survival of the nine treated patients was 1 year. Seven patients were treated with the combination chemotherapy CHOP and four achieved a complete remission. Three of them are alive and continue in unmaintained remission for more than 1 year, surviving so far for 18+ to 31+ months. Two cases showed evidence of CNS involvement, one during life and the other as a post‐mortem finding.The differential diagnosis from other related or unrelated disorders and the possible aetiological factors responsible for the disease are discussed in detail.