bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunoreactive Dynorphin-(1-8) and Corticotropin-Releasing Factor in Subpopulation of Hypothalamic Neurons
Authors: Roth Kevin A. , Weber Eckard , Barchas Jack D. , Chang Ding , Chang Jaw-Kang
Published: October 2006

Immunoreactive corticotropin-releasing factor (CRF) and dynorphin-(1-8) were visualized in rat hypothalamus by immunohistofluorescence with specific antibodies. In brains from colchicine-treated, adrenalectomized rats, neuronal perikarya with immunoreactive CRF were observed in the paraventricular nucleus of the hypothalamus. The CRF occurred together with the dynorphin-(1-8). However, the CRF immunoreactivity occurred only in a subpopulation of the dynorphin-(1-8) immunoreactive cells. These findings suggest that there may be a functional interrelationship of CRF with dynorphin-related opioid peptides and provide further evidence that neurons may contain more than one bioactive substance.
Different Proteins Associated with 10-Nanometer Filaments in Cultured Chick Neurons and Nonneuronal Cells
Authors: Bennett Gudrun S. , Tapscott Stephen J. , Kleinbart Fredric A. , Antin Parker B. , Holtzer Howard
Published: October 2006

A protein of molecular size 180 kilodaltons is associated with 10-nanometer filaments in neurons and is immunologically distinct from smaller putative neurofilament subunits and from 10-nanometer filament proteins in nonneuronal cells, such as myotubes and fibroblasts. Neurons do not contain vimentin, the major filament protein in many other cells, including the nonneuronal cells in cultures of neural tissue.
Absence of Correlation Between Base-Pair Sequence and RNA Conformation
Authors: Holbrook Stephen R. , Sussman Joel L. , Kim Sung-Hou
Published: October 2006

A survey of all available double-stranded RNA crystal structures shows that there is a considerable range of variation in local conformation of a given base-pair doublet, but that there is no significant correlation between base-pair sequence and RNA local conformation.
Complete Nucleotide Sequence and Organization of the Moloney Murine Sarcoma Virus Genome
Authors: Reddy E. Premkumar , Smith Mary Jane , Aaronson Stuart A.
Published: October 2006

The complete nucleotide sequence of a mammalian transforming retrovirus. Moloney murine sarcoma virus, has been determined. MSV, a recombinant virus derived of helper viral and cellular sequences, possesses termini resembling prokaryotic transposable elements. The viral genome has the coding capacity for the Moloney murine leukemia virus
gag
gene product and contains large deletions in
pol
and
env
genes. A large open reading frame encompassing its cell-derived sequences codes for its putative transforming protein. The nature of some of the important domains in the viral genome has been established, and their structure is discussed in relation to their function.
Antigenic Diversity in the Human Malaria Parasite
Plasmodium falciparum
Authors: McBride Jana S. , Walliker David , Morgan Gillian
Published: October 2006

Monoclonal antibodies against blood forms of
Plasmodium falciparum
were used to demonstrate considerable antigenic diversity in this species. Different isolates were distinguished by their ability to react with certain antibodies, and most of the antibodies reacted specifically with merozoites, schizonts, or both. The distribution of different antigenic types appeared not to be related to geographic origin. Serological typing with monoclonal antibodies extends the range of methods for identification of different strains of this malaria parasite.
Simultaneous Expression of Globin Genes for Embryonic and Adult Hemoglobins During Mammalian Ontogeny
Authors: Boussios Thalia , Bertles John F. , Clegg John B.
Published: October 2006

The dominant hemoglobin of the adult hamster was detected in yolk-sac erythroid cells, and its identity was confirmed by peptide mapping and by analysis of relevant peptides. Both the presence and active synthesis of two embryonic hemoglobins presumed to exist only in yolk-sac erythroid cells were detected in neonatal liver and spleen. Thus the time span of expression of both embryonic and adult globin genes during mammalian ontogeny may be considerably broader than presently believed.
Vasopressin Analog with Extraordinarily High Antidiuretic Potency: A Study of Conformation and Activity
Authors: Smith Clark W. , Walter Roderich
Published: October 2006

Application of information derived from a three-dimensional model of vasopressin bound to its antidiuretic receptor has resulted in the design and synthesis of a potent analog, [1-deamino,2-phenylalanine,7-(3,4-dehydroproline)]-arginine vasopressin; this analog has a specific antidiuretic activity of 13,000 ± 1,250 units per milligram; noteworthy at these doses is the absence of any detectable pressor activity. Three modifications based on conformational considerations were introduced into the vasopressin molecule in preparing the analog: (i) to enhance binding, a double bond was introduced into the side chain of an amino acid residue occupying a corner position of a β turn in the vasopressin conformation, (ii) the hydroxyl moiety was deleted from Tyr
2
, and (iii) to tighten the backbone structure and to enhance the enzymatic resistance of the analog, the NH
2
-terminal amino group was deleted.
Memory: Modification of Anisomycin-Induced Amnesia by Stimulants and Depressants
Authors: Flood James F. , Bennett Edward L. , Orme Ann E. , Rosenzweig Mark R. , Jarvik Murray E.
Published: October 2006

Mice were trained in a passive (foot shock) avoidance task. When administered after training, the stimulants caffeine or nicotine blocked amnesia for the task that had been produced by injections of the protein synthesis inhibitor anisomycin given prior to training. With foot shock at a higher intensity, anisomycin did not produce amnesia by itself, but the administration of the depressants chloral hydrate or sodium phenobarbital after training did cause amnesia. Stimulants and depressants did not have an appreciable influence on the overall degree of protein synthesis inhibition produced by anisomycin. The results support the hypothesis that arousal after training is an important factor in the conversion of short-term to long-term memory.
Major
pol
Gene Progenitors in the Evolution of Oncoviruses
Authors: Chiu Ing-Ming , Callahan Robert , Tronick Steven R. , Schlom Jeffrey , Aaronson Stuart A.
Published: October 2006

The genetic relationships among molecularly cloned prototype viruses representing all of the major oncovirus genera were investigated by molecular hybridization and nucleotide sequence analysis. One of the major progenitors of the
pol
genes of such viruses gives rise to mammalian type C viruses and another gives rise to type A, B, D, and avian type C oncoviruses. Evidence of unusual patterns of homology among the
env
genes of mammalian type C and D oncoviruses illustrates that genetic interactions between their progenitors contributed to the evolution of oncoviruses.
Cooperative Research: A Case Report
Authors: Leake Chauncey D.
Published: October 2006

It is felt by the workers concerned in this cooperative venture that the real effort is just beginning. The hopefulness of undertaking to find arsenical and mercurial organic compounds which might be better than anything yet known for the treatment of syphilis of the central nervous system has been justified, and this is provoking greater optimism for the future. So much promising study is in sight that enthusiasm among the group in increasingly evident at each meeting. It is hoped that this plain recital of the story of a working cooperative scientific research, with its implied disappointments and reverses, as well as with its successes, may prove to be the needed stimulus to the inauguration of similar efforts elsewhere.
Initiation of Angiogenesis by Human Follicular Fluid
Authors: Frederick Jane L. , Shimanuki Takao , diZerega Gere S.
Published: October 2006

Angiogenesis was observed and measured after injection of human follicular fluid into rabbit corneas. Undiluted human follicular fluid stimulated angiogenesis in every case, with new blood vessels visible 3 days after injection and extending 2.0 millimeters from the corneal scleral limbus into the injection site by day 15. Stimulation of angiogenesis was lost by heating or diluting the follicular fluid but was retained after charcoal stripping or dialysis. Human follicular fluid contains an angiogenic factor that may be associated with perifollicular neovascularization during folliculogenesis.
Double-Stranded RNA Is Present in Extracts of Tobacco Plants Infected with Tobacco Mosaic Virus
Authors: Derrick Kenneth S.
Published: October 2006

Serologically specific electron microscopy was used to detect double-stranded RNA in extracts of tobacco infected with tobacco mosaic virus. Assays were made immediately after extraction, without purification, concentration, or treatment with phenol or detergent. This indicates that the double-stranded RNA is native and is not an artifact induced by purification methods.
L-Dopa Methyl Ester: Prolongation of Survival of Neuroblastoma-Bearing Mice After Treatment
Authors: Wick Michael M.
Published: October 2006

L-Dopa has been shown to demonstrate enhanced toxicity toward melanoma cells in vitro. Since melanocytes arise from the neural crest embryologically, the effect of L-dopa methyl ester, a soluble analog, on the murine C1300 neuroblastoma was studied. There was significant antitumor activity against the neuroblastoma, which was enhanced by combination with a dopa decarboxylase inhibitor, Ro4-4602. In vitro studies suggested inhibition of DNA synthesis as the principal site of action. A mechanism involving sulfhydryl compound scavenging is postulated.
Human Breast Cancer: Androgen Action Mediated by Estrogen Receptor
Authors: Zava David T. , McGuire William L.
Published: October 2006

Growth of the human breast cancer cell line MCF-7 is enhanced by androgens, but only at pharmacological concentrations. Although physiological concentrations of androgens translocate the androgen receptor into the nucleus, no mitogenic effects are observed. By contrast, pharmacological androgens translocate not only the androgen receptor but also the estrogen receptor, and at these high doses significantly increase both DNA and estrogen-dependent protein synthesis. We therefore propose that androgens stimulate MCF-7 cell growth not through the androgen receptor but rather through the estrogen receptor.
High-Molecular-Weight Immunoreactive β-Endorphin in Extracts of Human Placenta Is a Fragment of Immunoglobulin G
Authors: Julliard Jacques H. , Shibasaki Tamotsu , Ling Nicholas , Guillemin Roger
Published: October 2006

A high-molecular-weight protein with β-endorphin- and adrenocorticotropin-immunoreactivities was isolated from extracts of human placenta after several purification steps, including immunoadsorption with a well-characterized antiserum raised to β-endorphin. This protein was identified as the heavy chain of the human immunoglobulin class IgG
1
. These results have led to the recognition of homologies in the amino acid sequences of these physiologically unrelated molecules. They also suggest caution in accepting immunological competence as the sole criterion of the chemical identity of a ligand.
Dexamethasone Fails to Suppress β-Endorphin Plasma Concentrations in Humans and Rhesus Monkeys
Authors: Kalin Ned H. , Risch Samuel C. , Cohen Robert M. , Insel Thomas , Murphy Dennis L.
Published: October 2006

In humans and rhesus monkeys, dexamethasone decreased concentrations of plasma cortisol but did not alter circulating β-endorphin immunoreactivity. Contrary to current theory suggesting that pituitary β-endorphin and adrenocorticotropic hormone are controlled by identical regulatory mechanisms for synthesis and release, our evidence suggests that in higher primates the established glucocorticoid feedback mechanism for the adrenocorticotropic hormone-cortisol system does not regulate β-endorphin secretion in the same way.
Steps Toward Computer Analysis of Nucleotide Sequences
Authors: Gingeras Thomas R. , Roberts Richard J.
Published: October 2006

Advances in recombinant DNA technology have allowed the isolation of large numbers of biologically interesting fragments of DNA. Concomitant improvements in methods for nucleic acid sequencing have led many investigators to characterize their clones by sequencing them. This has resulted in the accumulation of such large amounts of sequence data that computer-assisted methods, with programs directed toward the manipulation of nucleic acid sequences, have become indispensable during the collection and analysis of that data.
Emergence of Posttetanic Potentiation as a Distinct Phase in the Differentiation of an Identified Synapse in
Aplysia
Authors: Ohmori Harunori , Rayport Stephen G. , Kandel Eric R.
Published: October 2006

The developmental time course of posttetanic potentiation was studied at an identified chemical synapse. In stage 11 juveniles (3 weeks after metamorphosis), the synaptic connections made by cholinergic neuron L
10
onto postsynaptic neurons L
2
to L
6
were present but showed no posttetanic potentiation. In stage 13 adults (12 weeks after metamorphosis), the same tetanus resulted in an increase of 300 percent in the synaptic potential. A similar pattern was observed at two other identified synapses in the abdominal ganglion. Thus, the initial steps in synapse formation do not include the expression of this plastic capability. Rather, at least 10 weeks is required between the onset of synaptic function and the final expression of mature synaptic properties.
Viral Receptors on Isolated Murine and Human Ependymal Cells
Authors: Tardieu M. , Weiner H. L.
Published: October 2006

Viruses that infect ependyma cause ependymitis in humans and hydrocephalus in experimental animals. We report that reovirus type 1 (which induces hydrocephalus in mice) binds to the surface of isolated human and murine ciliated ependymal cells. With the use of recombinant viral clones, the binding property was mapped to the type 1 viral hemagglutinin, which also determines in vivo the affinity of reovirus type 1 for ependyma. Mumps virus, measles virus, parainfluenza type 3, and herpes simplex virus type 1 bind to murine ependyma cells, whereas reovirus type 3, herpes simplex virus type 2, and poliovirus type 1 do not.
Immunotherapy of Metastases Enhances Subsequent Chemotherapy
Authors: Hanna Michael G. , Key Marc E.
Published: October 2006

In many multimodal therapies of cancer, postsurgical chemotherapy is administered before immunotherapy for treatment of micrometastatic disease. This sequence may not be the most efficacious. Experiments in which strain 2 guinea pigs bearing syngeneic L10 hepatocarcinomas were given immunotherapy showed that infiltrating immune effector cells not only were tumoricidal but disrupted the characteristically compact structure of metastatic foci. When cytotoxic drugs were administered at the peak of this inflammatory response, the survival rate of the guinea pigs increased significantly. We conclude that postsurgical immunotherapy can enhance the effect of cytotoxic drugs administered subsequently.
Pyrazole-Induced Thyroid Necrosis: A Distinct Organ Lesion
Authors: Szabo Sandor , Horbath Eva , Kovacs Kalman , Larsen P. Reed
Published: October 2006

One oral dose of pyrazole caused necrosis of rat thyroid follicular epithelial cells but spared the parafollicular (C) cells and the parathyroid glands. Serum thyroxine (T
4
) and triiodothyronine (T
3
) were significantly decreased on day 3 after pyrazole administration and were immeasurable on day 5. At day 5 the thyroid was enlarged and the concentration of thyroid-stimulating hormone in the serum was increased, indicating an appropriate pituitary response to a primary lesion in the thyroid. Doses of pyrazole which produced no morphologic change in the thyroids also significantly depressed the concentrations of T
4
and T
3
in the serum.
5′ Viral and Human Cellular Sequences Corresponding to the Transforming Gene of Simian Sarcoma Virus
Authors: Josephs Steven F. , Dalla-Favera Riccardo , Gelmann Edward P. , Gallo Robert C. , Wong-Staal Flossie
Published: October 2006

The 5′ nucleotide sequences of the transforming gene of simian sarcoma virus (v-
sis
) and its human cellular homolog (c-
sis
) were compared. A short homology was found between helper virus and cellular DNA sequences at the junction of v-
sis
and c-
sis
, which may have had a role in the original recombination event leading to the generation of simian sarcoma virus.
Ionizing Radiation Decreases Veratridine-Stimulated Uptake of Sodium in Rat Brain Synaptosomes
Authors: Wixon Henry N. , Hunt Walter A.
Published: October 2006

Veratridine-stimulated uptake of sodium-22 in brain synaptosomes was significantly reduced by ionizing radiation over a dose range of 10 to 1000 rads. The response was dose-dependent and involved a decrease in the maximum effect of veratridine on uptake. The central nervous system may be more sensitive to ionizing radiation than generally thought, perhaps through a loss of the ability of the sodium channel to respond properly to stimulation.
Normalizing Effect of an Adrenocorticotropic Hormone (4-9) Analog ORG 2766 on Disturbed Social Behavior in Rats
Authors: Niesink Raymond J. M. , van Ree Jan M.
Published: October 2006

Short-term isolation increased the frequency of social interactions in rats tested in pairs, while pairs of rats placed in an unfamiliar test cage and subjected to a high level of illumination spent less time in active social contact. These changes in social behavior elicited by environmental manipulations were counteracted by treatment with the adrenocorticotropic hormone (4-9) analog ORG 2766. The peptide's normalizing effect may be mediated by endogenous opioid systems.
Segregation and Mapping Analysis of Polymorphic HLA Class I Restriction Fragments: Detection of a Novel Fragment
Authors: Erlich Henry A. , Stetler Deborah , Sheng-Dong Rosy , Ness Dolly , Grumet Carl
Published: October 2006

An HLA-B7 complementary DNA clone was used as a hybridization probe to analyze the segregation pattern of polymorphic class I restriction fragments in several families whose HLA types had been determined by serological techniques. In one family in which a crossover in the HLA region had occurred, a specific genomic fragment was mapped with respect to the crossover. In another family, a novel genomic fragment present in one child and absent in all other family members was observed. With the exception of this novel fragment, all polymorphic class I fragments observed in this study segregated with a serologically defined parental haplotype, a result consistent with HLA linkage.
Effect of Prior Immunization on Induction of Cervical Cancer in Mice by Herpes Simplex Virus Type 2
Authors: Wentz W. Budd , Heggie Alfred D. , Anthony Donald D. , Reagan James W.
Published: October 2006

Previous studies at this laboratory showed that repeated application of inactivated herpes simplex virus type 2 to the mouse cervix produces premalignant and malignant lesions. In the present study mice were inoculated with inactivated herpes simplex virus type 2 or control solution and Freund's adjuvant by intraperitoneal and subcutaneous routes before exposure of the cervix to inactivated virus. It appears that immunization with inactivated virus conferred a protection against the induction of cervical carcinoma.
Molecular Dissection of Transcriptional Control Elements Within the Long Terminal Repeat of the Retrovirus
Authors: Srinivasan A. , Reddy E. P. , Dunn Claire Y. , Aaronson Stuart A.
Published: October 2006

The retroviral long terminal repeat (LTR) contains transcriptional control elements that affect viral gene expression. By deletion mutagenesis of the genome of the cloned Abelson murine leukemia virus, regulatory signals could be mapped to at least three domains within the LTR. A defective 5′ LTR that did not sustain transforming gene function was complemented by an intact LTR positioned at the 3′ end of the genome. This versatility of the retroviral genome with respect to its transcriptional control elements appears to provide a strong selective advantage for viral gene expression.
Novel Viral Sequences Related to Human T-Cell Leukemia Virus in T Cells of a Seropositive Baboon
Authors: Guo Hong-Guang , Wong-Stall Flossie , Gallo Robert C.
Published: October 2006

Antibodies reactive with proteins of human T-cell leukemia virus (HTLV) can be found in Old World monkeys. A T-lymphocyte cell line established from a seropositive baboon (
Papio cynocephalus
) was analyzed for the presence of viral DNA sequences. The provirus found in these cells was related to but distinct from HTLV subgroup I. These results add to recent evidence from human studies that HTLV represents a spectrum of infectious T-lymphotropic retroviruses that includes closely and distantly related members.
Human Colon Cells: Culture and in Vitro Transformation
Authors: Moyer Mary Pat , Aust J. Bradley
Published: October 2006

Normal human colon mucosal epithelial cells were cultured in vitro and treated with the oncogenic simian DNA virus (SV40) and the chemical carcinogen azoxymethane. Both SV40 and azoxymethane altered a number of phenotypic characteristics of the normal human colon cells, including their morphology, culture longevity, growth in soft agar, substrate adherence, and peanut agglutinin binding. The SV40 transformants synthesized intranuclear T antigen. These data indicate that normal human colon mucosal cells were transformed toward the malignant phenotype.
Immunochemical Localization of NADP-Specific Isocitrate Dehydrogenase in
Escherichia coli
Authors: Swafford James R. , Malloy Peter J. , Reeves Henry C.
Published: October 2006

The intracellular localization of isocitrate dehydrogenase was determined by immunochemical techniques with ultrathin sections of
Escherichia coli
. The thin sections, which were obtained by ultracryomicrotomy, were incubated first with antiserum specific for the enzyme and then with a protein A-gold complex. Transmission electron microscopy showed that the gold label was dispersed mainly in the cytoplasm.
3-Methoxy-4-Hydroxyphenylglycol in Cerebrospinal Fluid and Vanillylmandelic Acid in Urine of Humans with Hypertension
Authors: Saran R. K. , Sahuja R. C. , Gupta N. N. , Hasan M. , Bhargava K. P. , Shanker K. , Kishor K.
Published: October 2006

3-Methoxy-4-hydroxyphenylglycol (MHPG) was measured in lumbar spinal fluid of 20 subjects with hypertension of varied etiology and severity. There was a significant correlation between the concentration of MHPG and the severity of hypertension. However, changes in the concentration of vanillylmandelic acid in the urine of these subjects were insignificant. In six subjects, administration of clonidine or α-methyldopa, two centrally acting antihypertensive drugs, was associated with a significant lowering of MHPG concentrations. These data support the hypothesis that central catecholamines are involved in clinical hypertension.
Who Will Pay for Medical Education in Our Teaching Hospitals?
Authors: Relman Arnold S.
Published: October 2006

Although most medical educators believe that education, research, and patient care are inseparable and essential to their academic mission, the educational component of this triad has never been given adequate, earmarked support. To fund educational programs, medical centers first relied on research grants and later on third-party payments intended for patient care. However, research money has long since ceased to be available for other purposes and recent federal cost containment measures have started to reduce payments for patient care. Teaching hospitals are threatened with loss of support not only for education, but for their capital improvements and care of the poor. Many institutions are now hoping to generate new income through business deals with for-profit health care corporations, but this effort probably will also fail and may compromise professional traditions. Teaching hospitals serve the public interest and will have to depend, at least in part, on public subsidy of their unavoidable extra costs.
Oncornavirus: Isolation From a Squirrel Monkey (
Saimiri sciureus
) Lung Culture
Authors: Heberling R. L. , Barker S. T. , Kalter S. S. , Smith G. C. , Helmke R. J.
Published: October 2006

An oncornavirus isolated from a squirrel monkey (
Saimiri sciureus
) lung culture has a density of 1.16 to 1.17 grams per milliliter, contains 70
S
RNA, and has an RNA-directed DNA polymerase that prefers Mg
2+
over Mn
2+
in an assay in which polyribocytidylate ⋅ oligodeoxyguanylate (12-18) is used as a synthetic template. Morphologically, the virus resembles Mason-Pfizer monkey virus but is antigenically distinct from this virus. The virus grows in cells of human, chimpanzee, rhesus monkey, canine, and mink origin, but not cells of squirrel monkey origin. On the basis of its properties, the newly isolated virus can be classified as a retravirus.
Prolongation of Rat Islet Allograft Survival by Direct Ultraviolet Irradiation of the Graft
Authors: Lau Henry , Reemtsma Keith , Hardy Mark A.
Published: October 2006

Ultraviolet irradiation of rat dendritic cells completely abrogated their allostimulatory capacity in a mixed lymphocyte reaction. Rat islets of Langerhans similarly irradiated remained hormonally functional when transplanted into syngeneic diabetic rats. Allogeneic transplantation across a major histocompatibility barrier of islets initially treated in vitro with ultraviolet irradiation resulted in prolonged allograft survival without the use of any immunosuppressive agents.
Myosin Heads Do Not Move on Activation in Highly Stretched Vertebrate Striated Muscle
Authors: Yagi N. , Matsubara I.
Published: October 2006

Highly stretched muscles in which thick and thin filaments no longer overlap produce little or no tension on activation. In preparations producing no tension, the 42.9-nanometer myosin layer line shown in x-ray diffraction patterns does not become weaker. This suggests that myosin heads do not move from their resting positions in the absence of actin.
Mental Symptoms in Huntington's Disease and a Possible Primary Aminergic Neuron Lesion
Authors: Mann J. John , Stanley Michael , Gershon Samuel , Rossor M.
Published: October 2006

Monoamine oxidase activity was higher in the cerebral cortex and basal ganglia of patients dying from Huntington's disease than in controls. Enzyme kinetics and multiple substrate studies indicated that the increased activity was due to elevated concentrations of monoamine oxidase type B. Concentrations of homovanillic acid were increased in the cerebral cortex but not in the basal ganglia of brains of patients with Huntington's disease. These changes may represent a primary aminergic lesion that could underlie some of the mental symptoms of this disease.
Pyrolysis Mass Spectrometry of Complex Organic Materials
Authors: Meuzelaar Henk L. C. , Windig Willem , Harper Alice M. , Huff Stanley M. , McClennen William H. , Richards Joseph M.
Published: October 2006

Pyrolysis mass spectrometry in combination with computerized multivariate statistical analysis enables qualitative and quantitative analysis of nonvolatile organic materials containing molecular assemblies of a complexity and size far beyond the capabilities of direct mass spectrometry. The state of the art in pyrolysis mass spectrometry techniques is illustrated through specific applications, including structural determination and quality control of synthetic polymers, quantitative analysis of polymer mixtures, classification and structural characterization of fossil organic matter, and nonsupervised numerical extraction of component patterns from complex biological samples.
Effect of Cell-Cell Interactions on Drug Sensitivity and Growth of Drug-Sensitive and -Resistant Tumor Cells in Spheroids
Authors: Tofilon Philip J. , Buckley Neil , Deen Dennis F.
Published: October 2006

Multicellular spheroids were grown from mixtures of rat brain tumor cells sensitive (9L) and resistant (R
3
) to 1,3-bis(2-chloroethyl)-1-nitrosourea. Percentages of each cell subpopulation in these spheroids were estimated with the sister chromatid exchange assay and were found to be approximately the same as those used to initiate spheroids. Spheroids grown from 9L cells alone had a higher growth rate than spheroids grown from R
3
cells alone. However, the growth rate of mixed-cell spheroids was essentially the same as that of pure 9L spheroids and was independent of the percentages of R
3
cells in mixed-cell spheroids. The sensitivity of 9L cells in mixed-cell spheroids treated with 1,3-bis(2-chloroethyl)-1-nitrosourea, estimated by changes in the number of sister chromatid exchanges per metaphase induced by treatment, decreased as the percentage of R
3
cells increased. These effects are probably the result of an interaction between the two cell subpopulations held in three-dimensional contact, a situation similar to that in tumors in situ. The results suggest why one cell subpopulation of tumors does not become dominant during growth and indicate that interactions between cell subpopulations can influence the sensitivity of one subpopulation to 1,3-bis(2-chloroethyl)-1-nitrosourea.
A Harvester Ant Venom: Chemistry and Pharmacology
Authors: Schmidt Justin O. , Blum Murray S.
Published: October 2006

The mammalian toxicity of the potently algogenic venom of the ant
Pogonomyrmex badius
is greater than that reported for any other insect venom. This enzyme-rich venom contains high concentrations of phospholipase A
2
and B, hyaluronidase, acid phosphatase, lipase, and esterases. This hemolytic secretion from the poison gland produces unusual symptoms in mammals and appears to have been evolved as a deterrent for vertebrate predators.
Effect of Oxygen Pressure During Culture on Survival of Mouse Thyroid Allografts
Authors: Talmage David W. , Dart Gladys A.
Published: October 2006

A marked increase in the percentage of mouse thyroids that retained function 20 days after transplantation across a major histocompatibility barrier and the percentage that lacked generalized infiltration was observed when the grafts received hyperbaric oxygen during a 4-day culture period. Perfusion of the donor animal before thyroidotomy and the addition of fetal calf serum to the culture medium did not have a significant effect on graft survival, but the percentage of grafts lacking generalized infiltration was slightly increased by the addition of hydrocortisone to the culture medium.
Cohort Mortality for Prostatic Cancer Among United States Nonwhites
Authors: Ernster Virginia L. , Selvin Steve , Winkelstein Warren
Published: October 2006

In recent decades, age-adjusted mortality rates from prostatic cancer have risen precipitously among blacks, remaining unchanged among whites. It is now the most common cancer among United States black males. When nonwhite mortality rates were examined by age and birth cohort, it was found that peak rates occurred at every age in the cohort of 1896 to 1900, and declined thereafter. This presages an arrest and reversal of the time trend in summary mortality rates as more recent nonwhite cohorts reach the ages of maximum risk.
Intrahippocampal Septal Grafts Ameliorate Learning Impairments in Aged Rats
Authors: Gage Fred H. , Björklund Anders , Stenevi Ulf , Dunnett Stephen B. , Kelly Paul A. T.
Published: October 2006

Grafts of fetal septal tissue rich in cholinergic neurons were implanted as a dissociated cell suspension into the depth of the hippocampal formation in aged rats with severe impairments in spatial learning abilities. After 2½ to 3 months, the rats with grafts, but not the controls, had improved their performance in a spatial learning test. Their improvement was due, at least in part, to an increased ability to use spatial cues in the task. In all animals the grafts had produced an extensive acetylcholinesterase-positive terminal network in the surrounding host hippocampal formation. Thus, the action of cholinergic neurons in the graft onto elements in the host hippocampal circuitry may be a necessary, but perhaps not sufficient, prerequisite for the observed functional recovery.
Processing of Proenkephalin Is Tissue-Specific
Authors: Liston Dane , Patey Gilles , Rossier Jean , Verbanck Paul , Vanderhaeghen Jean-Jacques
Published: October 2006

Most neuropeptides are synthesized as large precursor proteins. These precursors undergo a maturation process involving several proteolytic events that generate the biologically active peptides. The enzymatic mechanisms underlying this processing are still largely unknown. The processing of the precursor protein proenkephalin was studied in two different bovine tissues, the hypothalamus and adrenal medulla. The high molecular weight enkephalin-containing peptides that accumulate in these two tissues were found to be different, indicating the existence of two processing pathways for this neuropeptide precursor.
Is Thymosin Action Mediated by Prostaglandin Release?
Authors: Garaci Cristina Rinaldi , Favalli Cartesio , Del Gobbo Vera , Garaci Enrico , Jaffe Bernard M.
Published: October 2006

Treatment of spleen cells derived from adult thymectomized mice with thymosin fraction 5 resulted in a rapid and dose-dependent stimulation of the release of immunoreactive prostaglandin E
2
. The release of prostaglandin E
2
was associated with induction of theta antigen and was totally inhibited by indomethacin. In contrast, prostaglandin E
2
release from spleen cells from intact donors was inhibited by treatment with fraction 5. The data support the concept that prostaglandin E
2
mediates the effects of thymosin fraction 5 on lymphocytes.
Acetylcholine Mediates a Slow Synaptic Potential in Hippocampal Pyramidal Cells
Authors: Cole A. E. , Nicoll R. A.
Published: October 2006

The hippocampal slice preparation was used to study the role of acetylcholine as a synaptic transmitter. Bath-applied acetylcholine had three actions on pyramidal cells: (i) depolarization associated with increased input resistance, (ii) blockade of calcium-activated potassium responses, and (iii) blockade of accommodation of cell discharge. All these actions were reversed by the muscarinic antagonist atropine. Stimulation of sites in the slice known to contain cholinergic fibers mimicked all the actions. Furthermore, these evoked synaptic responses were enhanced by the cholinesterase inhibitor eserine and were blocked by atropine. These findings provide electrophysiological support for the role of acetylcholine as a synaptic transmitter in the brain and demonstrate that nonclassical synaptic responses involving the blockade of membrane conductances exist in the brain.
DNA Rearrangement and Altered RNA Expression of the c-
myb
Oncogene In Mouse Plasmacytoid Lymphosarcomas
Authors: Mushinski J. Frederic , Potter Michael , Bauer Steven R. , Reddy E. Premkumar
Published: October 2006

Three types of tumors termed plasmacytomas (ABPC's), lymphosarcomas (ABLS's), and plasmacytoid lymphosarcomas (ABPL's) arise in BALB/c mice treated with pristane and Abelson murine leukemia virus (A-MuLV). While most ABPC's and ABLS's contain integrated A-MuLV proviral genome and synthesize the v-
abl
RNA, most ABPL's do not. The ABPL tumors were examined for the expression of other oncogenes that may be associated with their transformed state, in the absence of transforming virus. These tumors expressed abundant c-
myb
RNA of unusually large size and showed DNA rearrangements of the c-
myb
locus.
Salt Taste Transduction Occurs Through an Amiloride-Sensitive Sodium Transport Pathway
Authors: Heck Gerard L. , Mierson Sheella , DeSimone John A.
Published: October 2006

An important early event in mammalian gustatory transduction with respect to sodium chloride has been found to be the passage of sodium ions through specific transport pathways in the apical region of the taste bud. The inward current caused by sodium chloride placed on the mucosal surface of an in vitro preparation of rat dorsal lingual epithelium can be substantially reduced by the blocker of sodium ion transport, amiloride. The data show (i) that amiloride is a specific blocker of the chorda tympani response to sodium chloride, but not to potassium chloride, (ii) that the sodium and potassium gustatory systems are largely independent at the peripheral level, and (iii) that the classical ion taste "receptor" is actually a specific transport pathway permitting the cation to enter the taste-bud cell and thereby to spread depolarizing current.
Somatic Activation of
ras
K
Gene in a Human Ovarian Carcinoma
Authors: Feig L. A. , Bast R. C. , Knapp R. C. , Cooper G. M.
Published: October 2006

A tumor isolate from a patient with serous cystadenocarcinoma of the ovary contained an activated
ras
K
gene detected by transfection of NIH/3T3 cells. In contrast, DNA from normal cells of the same patient lacked transforming activity, indicating that activation of this transforming gene was the consequence of somatic mutation in the neoplastic cells. The transforming gene product displayed an electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels that differed from the mobilities of
ras
K
transforming proteins in other tumors, indicating that a previously undescribed mutation was responsible for activation of
ras
K
in this ovarian carcinoma.
Microdifferential Holography and the Polysarcomeric Unit of Activation of Skeletal Muscle
Authors: Sharnoff M. , Karcher T. H. , Brehm L. P.
Published: October 2006

Unbalanced holographic difference images of contracting skeletal muscle fibers reveal that activation affects the amplitude of the light scattered by individual myofibrils. The results suggest that the unit of activation is not the sarcomeric structural unit, but a monomyofibrillar segment containing 20 to 40 contiguous sarcomeres.
Prenatal Alcohol Exposure Alters Adult Expression of Sexually Dimorphic Behavior in the Rat
Authors: McGivern Robert F. , Clancy Andrew N. , Hill Mary Ann , Noble Ernest P.
Published: October 2006

Saccharin preference and performance in a Lashley III maze were found to be altered in adult male and female rats that had been exposed to alcohol during gestation. Specifically, the sexual dimorphism normally observed in both behaviors was absent in fetal alcohol-exposed animals. The lack of sexual dimorphism appeared to result from a masculinization of the exposed females and a feminization of the exposed males.
Dietary Restriction Retards Age-Related Loss of Gamma Crystallins in the Mouse Lens
Authors: Leveille P. J. , Weindruch R. , Walford R. L. , Bok D. , Horwitz J.
Published: October 2006

The soluble crystallins in lenses from diet-restricted and control mice of diverse ages (2, 11, or 30 months) were studied by high-performance liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results obtained with both methods suggest that dietary restriction decelerates age-related loss of soluble gamma crystallins.
Increased Numbers of Thoracic Dorsal Root Axons in Rats Given Antibodies to Nerve Growth Factor
Authors: Hulsebosch C. E. , Coggeshall R. E. , Perez-Polo J. R.
Published: October 2006

Sensory axons were counted in untreated 1-month-old rats and in littermates that were injected with antibodies to nerve growth factor. There were 45 percent more unmyelinated and 17 percent more myelinated axons in dorsal roots of the fifth thoracic spinal segment in treated rats. This suggests that the number of sensory axons can be changed by postnatal inactivation of nerve growth factor.
Chemical Impurity Produces Extra Compound Eyes and Heads in Crickets
Authors: Walton Barbara T.
Published: October 2006

A chemical impurity isolated from commercially purchased acridine causes cricket embryos to develop extra compound eyes, branched antennae, extra antennae, and extra heads. Purified acridine does not produce similar duplications of cricket heads or head structures nor do the substituted acridines proflavine, acriflavine, or acridine orange. A dose-response relation exists such that the number and severity of abnormalities increase with increasing concentration of the teratogen.
Autoradiographic Identification of Ornithine Decarboxylase in Mouse Kidney by Means of α-[5-
14
C]Difluoromethylornithine
Authors: Pegg Anthony E. , Seely James , Zagon Ian S.
Published: October 2006

α-Difluoromethylornithine is an enzyme-activated irreversible inhibitor of ornithine decarboxylase that forms a covalent bond with the enzyme. When α-[5-
14
C]difluoromethylornithine was administered to androgen-treated mice, only ornithine decarboxylase became labeled. Autoradiographic examination of kidney, liver, and brain indicated much more extensive incorporation of labeled difluoromethylornithine into kidney protein than into the protein of the other tissues. Such incorporation was greatly reduced by prior treatment of the mice with cycloheximide. These results correlate with the presence of ornithine decarboxylase activity which is much higher in the kidney than in the other tissues and is lost rapidly when protein synthesis is inhibited. The binding of this drug in vivo, therefore, is useful for determining the distribution of ornithine decarboxylase. The enzyme was predominantly located in the proximal tubule cells of the kidney in androgen-treated mice.
Rabbit Hepatic Progesterone 21-Hydroxylase Exhibits a Bimodal Distribution of Activity
Authors: Dieter Hermann H. , Muller-Eberhard Ursula , Johnson Eric F.
Published: October 2006

Progesterone 21-hydroxylase activity varies extensively among liver microsomes prepared from individual New Zealand White (NZW) rabbits. The 21-hydroxylase activities are distributed between two groupings that differ by more than tenfold in mean activity. Both male and female animals are represented in the two groupings. However, females exhibited the higher activity more frequently than males. The 21-hydroxylation of progesterone is catalyzed by one of the liver microsomal cytochrome P-450 isozymes, form 1, and these differences in activity are suggestive of differences in the occurrence of this isozyme among NZW rabbits.
Increased Sensitivity of Lymphocytes from People Over 65 to Cell Cycle Arrest and Chromosomal Damage
Authors: Staiano-Coico Lisa , Darzynkiewicz Zbigniew , Hefton John M. , Dutkowski Regina , Darlington Gretchen J. , Weksler Marc E.
Published: October 2006

Flow cytometry revealed that, in the presence of tritiated thymidine, a greater percentage of phytohemagglutinin-stimulated lymphocytes from old human donors were arrested in the G
2
or M phase than were cells from young donors. Furthermore, lymphocytes from old donors showed significantly more chromosomal damage than did lymphocytes from young donors. Lymphocyte cultures from old or young donors not exposed to tritiated thymidine had the same percentage of cycling lymphocytes in G
2
or M, although the number of lymphocytes stimulated by phytohemagglutinin to enter the cell cycle was significantly lower in cultures from old donors. Thus, the impaired incorporation of tritiated thymidine by phytohemagglutinin-exposed lymphocytes from old humans reflects both an impaired proliferative response to phytohemagglutinin and an increased sensitivity to the radiobiological effects of tritiated thymidine.
Hormonal Control Of Sexual Differentiation: Changes in Electric Organ Discharge Waveform
Authors: Bass Andrew H. , Hopkins Carl D.
Published: October 2006

Males and females of some mormyrid electric fishes generate electrical pulses that differ in waveform and duration. For one such species, testosterone or dihydrotestosterone induces females and immature males to produce the mature male electric organ discharge which is two times the duration of the female or immature discharge. Estradiol has only a weak effect. For a second species where males and females have similar electric organ discharges, testosterone produces no effect. The data suggest that androgens affect the electric organ itself.
An Unusual Glucocerebroside in the Crustacean Nervous System
Authors: Shimomura Koichiro , Hanjura Sunita , Ki Ping F. , Kishimoto Yasuo
Published: October 2006

High concentrations of glucocerebroside (glucosylceramide) were found in the ventral nerve cord, brain, optic nerve, and antenna, but not in the nonneural tissue, of the brown shrimp
Penaeus aztecus aztecus
. This lipid contained unusual sphingoid bases consisting of 14-, 15-, and 16-carbon sphinganines and sphingenines. The fatty acids were mainly nonhydroxylated homologs 22 carbons long and longer, similar to those found in galactocerebroside but differing from those in glucocerebroside in mammalian nervous systems.
Transmission of Integrated Sea Urchin Histone Genes by Nuclear Transplantation in
Xenopus laevis
Authors: Etkin Laurence D. , Roberts Mary
Published: October 2006

Sea urchin histone genes contained in a recombinant plasmid pSp102 were microinjected into the cytoplasm of fertilized eggs of
Xenopus laevis
. By the late blastula stage, plasmid DNA sequences were detected comigrating with the high molecular weight cellular DNA (greater than 48 kilobases). Analysis of the DNA from injected embryos digested with various restriction endonuclease demonstrated that the injected DNA was integrated into the frog genome. Clones of embryos containing the pSp102 DNA sequences were produced by means of nuclear transplantation. Individuals of the same clone contain the pSp102 sequences integrated into similar chromosomal locations. These sites vary between different clones.
Cooperative Immunoassays: Ultrasensitive Assays with Mixed Monoclonal Antibodies
Authors: Ehrlich Paul H. , Moyle William R.
Published: October 2006

Mixtures of certain monoclonal antibodies appear to bind human chorionic gonadotropin in a "cooperative" fashion because they form circular complexes with the hormone. Experiments illustrate how this property might be exploited to develop very sensitive immunoassays for human chorionic gonadotropin or any other antigen. Since the assays are not based on competitive inhibition between radiolabeled and unlabeled antigen, they are much more sensitive than a traditional radioimmunoassay in which either one of the same antibodies is used alone.
Rate of Synaptic Replacement in Denervated Rat Hippocampus Declines Precipitously From the Juvenile Period to Adulthood
Authors: McWilliams J. R. , Lynch G.
Published: October 2006

Synaptic contacts per unit area in the rat dentate gyrus reach adult numbers by the end of the first month after birth and remain constant thereafter. This experiment demonstrated that the rate at which synapses were replaced by sprouting after a lesion declined dramatically from 35 to 90 days of age. Thus, the juvenile period of the rat's life is marked by a considerable change in neuronal plasticity. This may be related to age-dependent effects in recovery from brain damage.
Cocaine-Induced Rotation: Sex-Dependent Differences Between Left- and Right-Sided Rats
Authors: Glick Stanley D. , Hinds Patricia A. , Shapiro Raymond M.
Published: October 2006

Cocaine elicited dose-related rotation (circling) in naïve rats. The maximum effect was greater than observed previously with other drugs. Overall, females were more sensitive to cocaine than males. However, right-biased females were more sensitive than left-biased females, whereas left-biased males were more sensitive than right-biased males. The results suggest that sex-dependent differences in brain asymmetry may be an important determinant of cocaine sensitivity.
Aged Rats: Recovery of Motor Impairments by Intrastriatal Nigral Grafts
Authors: Gage Fred H. , Dunnett Stephen B. , Stenevi Ulf , Björklund Anders
Published: October 2006

Dissociated cell suspensions, prepared from the substantia nigra and septal regions of rat embryos, can be grafted to the depths of the caudate-putamen and hippocampus of aged rats. The grafts were rich in dopamine-containing and acetylcholinesterase-positive neurons and had produced extensive new dopaminergic and cholinergic terminal networks in the host neostriatum and hippocampus, respectively. The intrastriatal dopaminergic grafts were associated with a significant improvement in motor coordination in the aged rats. This result suggests that the intracerebral grafting technique may provide a new tool for exploring the role of dopaminergic and cholinergic deficits in the neurological and behavioral impairments associated with aging.