bluuebunny/crossref_metadata_2025 huggingface dataset:
Defect in Phosphorylation of Insulin Receptors in Cells from an Insulin-Resistant Patient with Normal Insulin Binding
Authors: Grunberger George , Zick Yehiel , Gorden Phillip
Published: October 2006

Mononuclear blood cells were obtained from a patient with type A insulin resistance. The cells showed a normal ability to bind iodine 125-labeled insulin. Analysis of solubilized insulin receptors from the patient's cells revealed a defect in insulin-stimulated tyrosine kinase activity, which is closely associated with the receptor itself. The enzyme failed to phosphorylate the insulin receptor and showed a markedly reduced ability to phosphorylate exogenously added substrates. It appears that receptors from this insulin-resistant patient have a defect distal to the insulin-binding site (the α subunit of the receptor). The defect could be located in the β subunit, which has an adenosine triphosphate-binding site, or in another receptor component that transfers a signal of insulin binding into kinase activity. This dissociation between the normal binding and the defective protein kinase component of the insulin receptor represents the first biochemical defect of the receptor distal to ligand binding.
Synthesis, Transport, and Release of Posterior Pituitary Hormones
Authors: Brownstein Michael J. , Russell James T. , Gainer Harold
Published: October 2006

Vasopressin and oxytocin are made and released by neurons of the hypothalamo-neurohypophysial system. Pulse labeling these neurons with radioactive amino acid indicates that the two hormones and their respective neurophysin carrier proteins are synthesized as parts of separate precursor proteins. The precursors seem to be processed into smaller, biologically active molecules while they are being transported along the axon.
Axonal Transport: Each Major Rate Component Reflects the Movement of Distinct Macromolecular Complexes
Authors: Tytell Michael , Black Mark M. , Garner Judy A. , Lasek Raymond J.
Published: October 2006

The proteins of the three major rate components of axonal transport in guinea pig retinal ganglion cells were analyzed by one- and two-dimensional gel electrophoresis. Each rate component consisted of a different set of proteins that remained associated with each other during transport. This suggests that each rate component represents a distinct macromolecular complex and that these complexes may be definable organelles such as microtubules, microfilaments, and smooth endoplasmic reticulum. Thus, the transport of radiolabeled proteins in the axon reflects the movement of complete subcellular structures rather than the movement of individual proteins.
Form and Function of Retroviral Proviruses
Authors: Varmus Harold E.
Published: October 2006

Retroviruses have proved to be useful reagents for studying genetic and epigenetic (such as regulatory) changes in eukaryotic cells, for assessing functional and structural relationships between transposable genetic elements, for inducing insertional mutations, including some important in oncogenesis, and for transporting genes into eukaryotic cells, either after natural transduction of putative cellular oncogenes or after experimental construction of recombinant viruses. Many of these properties of retroviruses depend on their capacity to establish a DNA (proviral) form of their RNA genomes as a stable component of host chromosomes, in either somatic or germinal cells.
Secretion of Human Interferons by Yeast
Authors: Hitzeman Ronald A. , Leung David W. , Perry L. Jeanne , Kohr William J. , Levine Howard L. , Goeddel David V.
Published: October 2006

Plasmids were constructed to direct synthesis of the human interferons IFN-α1, IFN-α2, and IFN-γ in the yeast
Saccharomyces cerevisiae
. Expression of IFN genes containing coding sequences for secretion signals resulted in the secretion of IFN activity. A large proportion of the IFN-α1 and IFN-α2 isolated from the yeast cell growth media had the same amino termini as the natural mature interferons, suggesting a removal of the signal sequences identical to that of human cells. These results show that a lower eukaryote, such as yeast, can utilize and process a human signal sequence.
Bacterial Characterization by Flow Cytometry
Authors: Van Dilla M. A. , Langlois R. G. , Pinkel D. , Yajko D. , Hadley W. K.
Published: October 2006

Bacteria were analyzed in a dual-beam flow cytometer after double staining with the fluorescent dyes chromomycin A3 and Hoechst 33258, which bind preferentially to DNA that is rich in guanine-cytosine and adenine-thymine, respectively. The measurements were indicative of the cellular DNA content and base composition, cell concentration, and proliferative state of the population. The ratio of the chromomycin A3 signal to the Hoechst 33258 signal increased with the guanine-cytosine content of the cellular DNA for the six cultured species measured, following expectation. Bacteria in urine from patients with urinary tract infections were characterized without interference from host cell DNA, debris, or other particulates.
Science Centers: A Potential for Learning
Authors: Kimche Lee
Published: October 2006

The past decade has witnessed a proliferation of science-technology centers, or public places for informal learning about science and technology. Science centers are the only institutions that can provide the general public with participatory exhibits and experiences, together with an accurate scientific interpretation of the materials that are involved. The dramatic rise in attendance and the enthusiasm of repeat visitors to science centers reflect a strong public demand for exhibits designed to help the visitor develop a better understanding of the contemporary scientific issues of society.
β-Glucuronidase Catalyzed Hydrolysis of Benzo[
a
]pyrene-3-Glucuronide and Binding to DNA
Authors: Kinoshita Nadao , Gelboin Harry V.
Published: October 2006

β-Glucuronidase catalyzes the hydrolysis of benzo[
a
]pyrene-3-glucuronide to 3-hydroxybenzo[
a
]pyrene. During the enzymatic hydrolysis, a benzo[
a
]pyrene derivative is formed which binds to DNA to a far greater extent than either the 3-hydroxybenzo[
a
]pyrene or its glucuronide. These results suggest that conjugates of benzo[
a
]pyrene may be converted by β-glucuronidase at intracellular and organ sites distal to the initial sites of oxygenation and conjugation of benzo[
a
]pyrene to activated intermediates that are possibly carcinogenic.
Isolation of Lymphocytopathic Retroviruses from San Francisco Patients with AIDS
Authors: Levy Jay A. , Hoffman Anthony D. , Kramer Susan M. , Landis Jill A. , Shimabukuro Joni M. , Oshiro Lyndon S.
Published: October 2006

Infectious retroviruses have been detected in 22 of 45 randomly selected patients with acquired immune deficiency syndrome (AIDS) and in other individuals from San Francisco. The AIDS-associated retroviruses (ARV) studied in detail had a type D morphology, Mg
2+
-dependent reverse transcriptase, and cytopathic effects on lymphocytes. The viruses can be propagated in an established adult human T cell line, HUT-78. They cross-react with antiserum to the lymphadenopathy-associated retrovirus isolated from AIDS patients in France. Antibodies to ARV were found in all 86 AIDS patients and in a high percentage of 88 other homosexual men in San Francisco. This observation indicates the widespread presence of these lymphocytopathic retroviruses and their close association with AIDS.
Constitutive Fragile Sites and Cancer
Authors: Yunis Jorge J. , Soreng A. Lee
Published: October 2006

Breaks were observed at 51 sites in homologous chromosomes in lymphocytes from ten humans and two great apes when cells were deprived of thymidine. The incidence of breaks was enhanced by caffeine, a substance that inhibits DNA repair in replicating cells. The locations of 20 sites were correlated with breakpoints that have been related to human malignancy.
Postsynaptic Transmission Block Can Cause Terminal Sprouting of a Motor Nerve
Authors: Holland R. L. , Brown M. C.
Published: October 2006

Sprouting of mouse soleus motor nerve terminals can be evoked by daily intramuscular injections of purified α-bungarotoxin. This finding supports the hypothesis that an important stimulus to terminal sprouting in partial denervation and presynaptic nerve blockade is a product of inactive muscle fibers.
Human Hepatocellular Carcinoma Cell Lines Secrete the Major Plasma Proteins and Hepatitis B Surface Antigen
Authors: Knowles Barbara B. , Howe Chin C. , Aden David P.
Published: October 2006

Analysis of the cell culture fluid from two new human hepatoma-derived cell lines reveals that 17 of the major human plasma proteins are synthesized and secreted by these cells. One of these cell lines, Hep 3B, also produces the two major polypeptides of the hepatitis B virus surface antigen. When Hep 3B is injected into athymic mice, metastatic hepatocellular carcinomas appear. These cell lines provide experimental models for investigation of plasma protein biosynthesis and the relation of the hepatitis B virus genome to tumorigenicity.
Expression of a Bacterial Gene in Mammalian Cells
Authors: Mulligan R. C. , Berg P.
Published: October 2006

Transfection of cultured monkey kidney cells with recombinant DNA constructed with a cloned
Escherichia coli
gene that codes for xanthine-guanine phosphoribosyltransferase and several different SV40 DNA-based vectors, results in the synthesis of readily measurable quantities of the bacterial enzyme. Moreover, the physiological defect in purine nucleotide synthesis characteristic of human Lesch-Nyhan cells can be overcome by the introduction of the bacterial gene into these cells.
Visualization of Specific Angiotensin II Binding Sites in the Brain by Fluorescent Microscopy
Authors: Landas Steve , Phillips M. Ian , Stamler John F. , Raizada Mohan K.
Published: October 2006

The organum vasculosum of the lamina terminalis has been implicated as the site of receptors mediating central responses of angiotensin II. Up to now, this had been based on indirect evidence, but direct visualization of angiotensin II at its site of action has now been achieved by the use of a biologically active fluorescent angiotensin II agonist. The ventricular surface of the organum vasculosum lamina terminalis showed intense fluorescence, which was virtually eliminated by an excess of unlabeled angiotensin II.
Synaptic Excitation May Activate a Calcium-Dependent Potassium Conductance in Hippocampal Pyramidal Cells
Authors: Nicoll R. A. , Alger B. E.
Published: October 2006

In hippocampal CA1 pyramidal cells, orthodromic synaptic excitation is followed by an early hyperpolarization mediated by γ-aminobutyric acid (GABA) and a late non-GABA-mediated hyperpolarization that has properties consistent with an increase in potassium conductance. Depolarizations produced by iontophoretically applied glutamate are followed by hyperpolarizations that have features in accordance with an increase in potassium conductance. The hyperpolarizations are independent of chloride and resistant to tetrodotoxin but are blocked by a low-calcium, high-cobalt medium. Voltage clamping the glutamate depolarization does not reduce the subsequent hyperpolarization, indicating that the hyperpolarization results from a direct increase in calcium conductance produced by glutamate, rather than from activation of voltage-sensitive calcium channels. A single transmitter, possibly acting on one type of receptor and channel, may initiate both excitation and inhibition in the same postsynaptic cell.
Human Muscle Phosphoglycerate Mutase Deficiency: Newly Discovered Metabolic Myopathy
Authors: DiMauro Salvatore , Miranda Armand F. , Khan Shahnaz , Gitlin Kevin , Friedman Robert
Published: October 2006

Muscle phosphoglycerate mutase activity was decreased (5.7 percent of the lowest control value) in a 52-year-old man with intolerance for strenuous exercise and recurrent pigmenturia since adolescence. All of the other enzymes of glycolysis had normal activities, and glycogen concentration was normal. Electrophoretic, heat lability, and mercury inhibition studies showed that the small residual activity in the patient's muscle was represented by the brain (BB) isoenzyme of phosphoglycerate mutase, suggesting a genetic defect of the M subunit which predominates in normal muscle. The prevalence of the BB isoenzyme in other tissues, including muscle culture, may explain why symptoms were confined to muscle.
Hyperkeratosis Induced by Sunlight Degradation Products of the Major Polybrominated Biphenyl in Firemaster
Authors: Patterson D. G. , Hill R. H. , Needham L. L. , Orti D. L. , Kimbrough R. D. , Liddle J. A.
Published: October 2006

Sunlight photodegradation of 2,2′,4,4′,5,5′-hexabromobiphenyl, the major component of Firemaster, gave a mixture that produces severe hyperkeratosis of the rabbit ear. This component in its pure state does not cause hyperkeratosis. One or more of the four major photolysis products must be responsible for this activity. A similar photodegradation pattern was observed for 2,2′,3,4,4′,5,5′-heptabromobiphenyl, the second largest component of Firemaster.
Solubilized Adenosine Receptors in the Brain: Regulation of Guanine Nucleotides
Authors: Gavish Moshe , Goodman Robert R. , Snyder Solomon H.
Published: October 2006

Adenosine receptors associated with a reduction of adenylate cyclase and labeled by tritium-labeled cyclohexyladenosine can be solubilized from brain membranes with sodium cholate. Regulation of receptor binding by guanine nucleotides is retained in the soluble state. Influences of cations observed in membrane preparations of adenosine receptors are no longer detected with the solubilized receptors. The apparent retention of a complex of receptors and guanosine triphosphate binding but not cation binding protein in the soluble state may permit a molecular analysis of receptor regulation.
Residual Calcium Ions Depress Activation of Calcium-Dependent Current
Authors: Eckert Roger , Ewald Douglas
Published: October 2006

Calcium ions enter and accumulate during depolarization of some cells, activating a potassium current,
I
K(Ca)
, that depends on the cytoplasmic concentration of calcium ions, [Ca]
i
. However, elevation of [Ca]
i
can depress
I
K(Ca)
elicited by a subsequent membrane depolarization. The depression of
I
K(Ca)
is ascribed here to a [Ca]
i
-mediated inactivation of the voltage-gated calcium conductance, which causes a net reduction in calcium ions available for the activation of
I
K(Ca)
. This suggests that other processes dependent on gated calcium entry may also be depressed by small background elevations in cytosolic free calcium ions.
Spectral Character of Sunlight Modulates Photosynthesis of Previtamin D
3
and Its Photoisomers in Human Skin
Authors: MacLaughlin J. A. , Anderson R. R. , Holick M. F.
Published: October 2006

The photosynthesis of previtamin D
3
from 7-dehydrocholesterol in human skin was determined after exposure to narrow-band radiation or simulated solar radiation. The optimum wavelengths for the production of previtamin D
3
were determined to be between 295 and 300 nanometers. When human skin was exposed to 295-nanometer radiation, up to 65 percent of the original 7-dehydrocholesterol content was converted to previtamin D
3
. In comparison, when adjacent skin was exposed to simulated solar radiation, the maximum formation of previtamin D
3
was about 20 percent. Major differences in the formation of lumisterol
3
and tachysterol
3
from previtamin D
3
were also observed. It is concluded that the spectral character of natural sunlight has a profound effect on the photochemistry of 7-dehydrocholesterol in human skin.
Corticotropin-Releasing Factor Stimulates Accumulation of Adenosine 3′,5′-Monophosphate in Rat Pituitary Corticotrophs
Authors: Labrie Fernand , Veilleux Raymonde , Lefevre Gerard , Coy David H. , Sueiras-Diaz Javier , Schally Andrew V.
Published: October 2006

The presence of synthetic ovine corticotropin-releasing factor leads to a rapid and marked stimulation of adenosine 3′,5′-monophosphate accumulation in an enriched population of rat pituitary corticotrophs in primary culture. The increase, observed as early as 60 seconds after the addition of corticotropin-releasing factor, suggests that changes in the intracellular concentration of the cyclic nucleotide coincide with or precede the secretion of adrenocorticotropic hormone in response to corticotropin-releasing factor.
Rat Pro-Opiomelanocortin Contains Sulfate
Authors: Hoshina Harumi , Hortin Glen , Boime Irving
Published: October 2006

Intermediate lobes isolated from rat pituitary glands incorporated [
35
S]sulfate into pro-opiomelanocortin and other adrenocorticotropic hormone-containing peptides. Incubation of intermediate lobes in medium containing the arginine analog canavanine inhibited the cleavage of pro-opiomelanocortin into smaller products. Pro-opiomelanocortin that accumulated in the presence of canavanine was also sulfated.
Postprandial Changes in the Exhalation Rate of Radon Produced in Vivo
Authors: Rundo J. , Markun F. , Sha J. Y.
Published: October 2006

The rate of exhalation of radon by persons with long-standing radium burdens increases about twofold shortly after a meal. The increase is short-lived and "normal" values are regained in 1.5 to 2 hours. The effect may account in part for the poor reproducibility in estimates of the freely emanating part of the radium content.
Genetic Transformation of
Drosophila
with Transposable Element Vectors
Authors: Rubin Gerald M. , Spradling Allan C.
Published: October 2006

Exogenous DNA sequences were introduced into the
Drosophila
germ line. A
rosy
transposon (ry1), constructed by inserting a chromosomal DNA fragment containing the wild-type
rosy
gene into a P transposable element, transformed germ line cells in 20 to 50 percent of the injected
rosy
mutant embryos. Transformants contained one or two copies of chromosomally integrated, intact ry1 that were stably inherited in subsequent generations. These transformed flies had wild-type eye color indicating that the visible genetic defect in the host strain could be fully and permanently corrected by the transferred gene. To demonstrate the generality of this approach, a DNA segment that does not confer a recognizable phenotype on recipients was also transferred into germ line chromosomes.
Cotransmitters in the Motor Nerves of the Guinea Pig Vas Deferens: Electrophysiological Evidence
Authors: Sneddon P. , Westfall D. P. , Fedan J. S.
Published: October 2006

The contractile response of the guinea pig vas deferens to motor nerve stimulation is biphasic. The first phase is antagonized by the specific adenosine triphosphate-receptor antagonist arylazido aminoproprionyl adenosine triphosphate (ANAPP
3
), and the second by the α-receptor antagonist prazosin. The underlying electrical event, the excitatory junction potential, is also blocked by ANAPP
3
, but not by prazosin.
A Benzodiazepine Receptor Antagonist Decreases Sleep and Reverses the Hypnotic Actions of Flurazepam
Authors: Mendelson Wallace B. , Cain Michael , Cook James M. , Paul Steven M. , Skolnick Phil
Published: October 2006

The benzodiazepine receptor antagonist 3-hydroxymethyl-β-carboline, which blocks several of the pharmacological actions of benzodiazepines, induces a dose-dependent increase in sleep latency in the rat. Furthermore, at a low dose that by itself does not affect sleep, 3-hydroxymethyl-β-carboline blocks sleep induction by a large dose of flurazepam. The benzodiazepine receptor may play a role in both the physiological regulation and pharmacological induction of sleep.
Bidirectional Transmission at the Rectifying Electrotonic Synapse: A Voltage-Dependent Process
Authors: Giaume Christian , Korn Henri
Published: October 2006

Rectifying properties of electrotonic synapses established by the crayfish giant motor fiber are associated with a more negative resting membrane potential in the presynaptic than in the postsynaptic side of the junction. An increased junctional conductance and bidirectional transmission are produced, with almost no delay, by inverting this polarization.
Neutrophil Pseudoplatelets: Their Discrimination by Myeloperoxidase Demonstration
Authors: Hanker Jacob S. , Giammara Beverly L.
Published: October 2006

Neutrophils, especially in acute infection or the myeloid leukemias, may shed platelet-sized particles that can readily be distinguished from true platelets because they contain neutrophil myeloperoxidase. This enzyme, unlike platelet peroxidase, is not inhibited by glutaraldehyde. The myeloperoxidase and acid hydrolase levels and continuous plasma membranes of these cell-like particles suggest that they are functional cellular entities. They further differ from platelets in that they contain nuclear remnants, occur in bacteria-laden pus and inflammatory exudates, are ingested by macrophages, and do not adhere to each other or aggregate. They could be involved in the immune response to pathogens or contribute to trauma and healing by facilitating deployment of neutrophil acid hydrolase, neutral protease, and myeloperoxidase.
Transcriptional Enhancer Elements in the Mouse Immunoglobulin Heavy Chain Locus
Authors: Mercola Mark , Wang Xiao-Fan , Olsen Jory , Calame Kathryn
Published: October 2006

Two regions in the immunoglobulin heavy chain locus were tested for their ability to enhance transcription of the SV40 early promoter. A portion of the intervening sequence between the heavy chain joining region (J
h
) and the constant region of the μ chain (Cμ) can enhance transcription when it is cloned either 5′ or 3′ to the SV40 early promoter. The region between Cα and the alpha switch site, which occurs 5′ to the translocated c-myc oncogene in many murine plasmacytomas, does not show transcriptional enhancer activity in this assay.
Correlation of Glucocorticoid Receptor Binding Sites on MMTV Proviral DNA with Hormone Inducible Transcription
Authors: Pfahl Magnus , McGinnis David , Hendricks Michelle , Groner Bernd , Hynes Nancy E.
Published: October 2006

Steroid hormones, when complexed to their receptors, recognize and bind specific DNA sequences and subsequently induce increased levels of transcription. The mechanisms of steroid hormone action were analyzed by constructing chimeric DNA molecules from portions of mouse mammary tumor virus envelope and long terminal repeat (LTR) regions ligated to the thymidine kinase (tk) gene of herpes simplex virus. This construction allowed the tk gene to be expressed in a hormone-responsive fashion upon transfection into Ltk
-
cells. Comparison of transcription data with in vitro binding data showed that hormone-responsive transcription can be directly correlated to the presence of steroid hormone receptor binding sites on the DNA. There are at least two such receptor binding sites in the LTR region, one between -202 and -137 and another between -137 and -50 base pairs from the RNA cap site, as well as a site near the 5′ end of the envelope region. These results strengthen the hypothesis that steroid-receptor complexes regulate genes primarily by binding to DNA sites near the promoter region and thereby modulate transcription.
The Molecular Basis of Neuronal Excitability
Authors: Catterall William A.
Published: October 2006

Neurons process and transmit information in the form of electrical signals. Their electrical excitability is due to the presence of voltage-sensitive ion channels in the neuronal plasma membrane. In recent years, the voltage-sensitive sodium channel of mammalian brain has become the first of these important neuronal components to be studied at the molecular level. This article describes the distribution of sodium channels among the functional compartments of the neuron and reviews work leading to the identification, purification, and characterization of this membrane glycoprotein.
Hypoxic Coordinate Regulation of Mitochondrial Enzymes in Mammalian Cells
Authors: Murphy Brian J. , Robin Eugene D. , Tapper Douglas P. , Wong Ronald J. , Clayton David A.
Published: October 2006

The effect of hypoxic exposure on various mitochondrial enzymes and on cell mitochondrial genomic content was studied in two types of mammalian cells. Hypoxia depressed the activity of six enzymes to the same degree. The kinetics of depression and of recovery during reexposure to normoxia were statistically similar for three marker enzymes. Despite the global and symmetrical decrease in enzyme activities, mitochondrial DNA remained constant. This suggests either symmetrical loss of mitochondrial enzymes from all mitochondria or complete loss of enzymes from a subpopulation of mitochondria with retention of an intact mitochondrial genome.
Entamoeba histolytica
: a Eukaryote Without Glutathione Metabolism
Authors: Fahey Robert C. , Newton Gerald L. , Arrick Bradley , Overdank-Bogart Tobie , Aley Stephen B.
Published: October 2006

Entamoeba histolytica
was found to grow normally without producing glutathione and the main enzymes of glutathione metabolism, indicating that glutathione is not essential for many eukaryotic processes. This parasitic amoeba is an unusual eukaryote whose special features may help define the crucial functions of glutathione in those eukaryotes that do use it. Since
Entamoeba histolytica
lacks mitochondria and the usual aerobic respiratory pathways, the finding that it grows without glutathione and other evidence support the hypothesis that a primary function of glutathione in eukaryotes involves protection against oxygen toxicity associated with mitochondria and suggest that eukaryotes may have acquired glutathione metabolism at the time that they acquired mitochondria.
Primary Structure of v-
raf
: Relatedness to the
src
Family of Oncogenes
Authors: Mark George E. , Rapp Ulf R.
Published: October 2006

A replication-defective, acute transforming retrovirus (murine sarcoma virus 3611) was isolated from mouse and molecularly cloned. The nucleotide sequence of 1.5 kilobases encompassing the transforming gene (v-
raf
) was determined. This sequence, which predicts the amino acid sequence of a gag-
raf
fusion protein, terminates 180 nucleotides from the 3′ end of the acquired cellular sequence. Comparison of the predicted amino acid sequence of v-
raf
with the predicted amino acid sequences of other oncogenes reveals significant homologies to the
src
family of oncogenes. There is a lack of homology within the sequence of the tyrosine acceptor domain described for the phosphotyrosine kinase members of the
src
family of transforming proteins. Phylogenetic arrangement of this family of oncogenes suggests that tyrosine-specific phosphorylation may be a recently acquired activity.
Selective Tropism of Lymphadenopathy Associated Virus (LAV) for Helper-Inducer T Lymphocytes
Authors: Klatzmann David , Barré-Sinoussi Francoise , Nugeyre Marie Thèrése , Danguet Claude , Vilmer Etienne , Griscelli Claude , Brun-Veziret Francoise , Rouzioux Christine , Gluckman Jean Claude , Chermann Jean-Claude , Montagnier Luc
Published: October 2006

Lymphadenopathy associated virus (LAV) has been isolated from patients with the acquired immunodeficiency syndrome (AIDS) or lymphadenopathy syndrome. Since the immune deficiency in AIDS seems to be primarily related to the defect of the helper-inducer T lymphocyte subset, the possibility that LAV is selectively tropic for this subset was investigated. Fractionation of T lymphocytes was achieved by cellular affinity chromatography with monoclonal antibodies. In a hemophilic patient who was a healthy carrier of LAV, reverse transcriptase activity and virus particles detected by electron microscopy were found only in cultures of helper-inducer lymphocytes. When infected with LAV in vitro, lymphocyte subsets from normal individuals yielded similar results. Virus production was associated with impaired proliferation, modulation of T3-T4 cell markers, and the appearance of cytopathic effects. The results provide evidence for the involvement of LAV in AIDS.
Nucleotide Sequence of the Rasheed Rat Sarcoma Virus Oncogene: New Mutations
Authors: Rasheed Suraiya , Norman Gary L. , Heidecker Gisela
Published: October 2006

The nucleotide sequence of the oncogene of the Rasheed strain of rat sarcoma virus was determined. The oncogene (Ra-v-
ras
) encodes a 29,000-dalton (p29) transforming protein. This protein is distinct from the immunologically related 21,000-dalton protein (p21) of the Harvey murine sarcoma virus in its amino terminus and in having additional mutations in its carboxyl terminus. Although the functional significance of these changes is unknown, they appear to occur only in rat sarcoma virus.
Dietary Carcinogens and Anticarcinogens
Authors: Ames Bruce N.
Published: October 2006

The human diet contains a great variety of natural mutagens and carcinogens, as well as many natural antimutagens and anticarcinogens. Many of these mutagens and carcinogens may act through the generation of oxygen radicals. Oxygen radicals may also play a major role as endogenous initiators of degenerative processes, such as DNA damage and mutation (and promotion), that may be related to cancer, heart disease, and aging. Dietary intake of natural antioxidants could be an important aspect of the body's defense mechanism against these agents. Many antioxidants are being identified as anticarcinogens. Characterizing and optimizing such defense systems may be an important part of a strategy of minimizing cancer and other age-related diseases.
High-Performance Liquid Chromatography of Biopolymers
Authors: Regnier Fred E.
Published: October 2006

The ability to separate biological macromolecules with good resolution on liquid chromatographic columns has depended on the development of suitable packing materials. In size exclusion chromatography, molecules are separated by size on the basis of differential permeation of the packing. Ion exchange, hydrophobic interaction (or reversed-phase), and affinity chromatography are all surface-mediated separation methods, although they depend on different retention mechanisms. High-performance liquid chromatographic columns designed for biopolymers offer major advantages over conventional columns in both speed and resolving power. The exponential growth of literature on the high-performance separation of peptides and proteins in particular indicates that the technique will become the dominant form of column liquid chromatography.
Activity Patterns of Human Skeletal Muscles: Relation to Muscle Fiber Type Composition
Authors: Monster A. Willem , Chan Hing C. , O'Connor David
Published: October 2006

The muscle activity of normal ambulatory individuals was recorded continuously for 8-hour (working day) periods. Parameters of activity patterns were defined and numerical outcomes for these parameters were compared across a diverse population of muscles. Several pattern parameters, such as the average percentage of time active, were highly correlated with the percentage of type I fibers of a muscle.
Erythrocyte form of Spectrin in Cerebellum: Appearance at a Specific Stage in the Terminal Differentiation of Neurons
Authors: Lazarides Elias , Nelson W. James
Published: October 2006

The developing chicken cerebellum contains two forms of the plasma membrane-associated actin-binding protein spectrin. The brain form, αγ-spectrin (fodrin), is expressed constitutively in all neuronal cell bodies and processes during all stages of cerebellar morphogenesis. On the other hand, the erythrocyte form, αβ′β-spectrin, accumulates exclusively at the plasma membrane of the cell bodies of Purkinje and granule cells and of neurons in cerebellar nuclei, but only after these cells have become postmitotic and have completed their migration to their final positions in the cerebellum. The appearance of αβ′β-spectrin coincides temporally with the establishment of axosomatic contacts on these three neuronal cell types, which suggests that αβ′β-spectrin accumulates in response to the formation of functional synaptic connections during cerebellar ontogeny.
H-2
-Linked Resistance to Mastocytoma in Male Mice: Immune Response to a Histocompatibility Antigen on the X Chromosome
Authors: Kwak Larry W. , Kucuk Omer , Melvold Roger W. , Williams R. Michael
Published: October 2006

Male hybrids from a cross between female mice of strain C57BL/6Kh and males of strain DBA/2J lived longer after injection of P815 mastocytoma cells of DBA/2 origin than did their female siblings. Responses to the histocompatibility antigen on the X chromosome of the DBA/2 strain may be involved in resistance to the tumor. When the female parent was replaced with a C57BL/6Kh carrying one of several mutations in the
H-2
region, this sex effect disappeared in some of the hybrid combinations. Thus, the
H-2
complex appears to be involved in the regulation of the immune response to the X-linked histocompatibility antigen in this tumor model.
Gamma Interferon Synthesis by Human Thymocytes and T Lymphocytes Inhibited by Cyclosporin A
Authors: Reem Gabrielle H. , Cook Laura A. , Vilček Jan
Published: October 2006

Cyclosporin A depresses the synthesis of gamma interferon by human thymocytes and T lymphocytes in vitro. This observation is of potential clinical significance because the long-term treatment of transplant patients with cyclosporin A, a widely used immunosuppressive agent, can give rise to B-cell lymphoma resulting from Epstein-Barr virus activation.
Fast and Slow Magnetic Phenomena in Focal Epileptic Seizures
Authors: Barth Daniel S. , Sutherling William , Beatty Jackson
Published: October 2006

The magnetic fields associated with penicillin-induced focal epilepsy were measured in laboratory rats. Interictal magnetic spikes were similar to those previously observed in humans with focal seizure disorders. The magnetic fields of the seizure itself displayed both slow and fast phenomena, reversing in direction on opposite sides of the head.
The Structure of Crystalline Tris: A Plastic Crystal Precursor, Buffer, and Acetylcholine Attenuator
Authors: Rudman Reuben , Eilerman Donna , La Placa Sam J.
Published: October 2006

The crystal and molecular structure of the widely used buffer tris(hydroxymethyl)aminomethane (tris) has been determined from single-crystal diffractometer data to a standard agreement factor (
R
value) of 0.026 and bond length standard deviations of 0.002 angstrom. Tris crystallizes in the orthorhombic system, space group
Pn
2
1
a
, with four molecules per unit cell;
a
= 8.844(1) angstroms,
b
= 7.794(1) angstroms, and
c
= 8.795(1) angstroms. The center-to-center distances of tris molecules in the ordered phase range from 0.4 to 1.0 angstrom less than they do in the orientationally disordered (plastic) phase of similar molecules.
Fluorinated Molecule as a Tracer: Difluoroserotonin in Human Platelets Mapped by Electron Energy-Loss Spectroscopy
Authors: Costa Jonathan L. , Joy David C. , Maher Dennis M. , Kirk Kenneth L. , Hui S. W.
Published: October 2006

The intracellular distribution of fluorine has been delineated in human platelets incubated with 4,6-difluoroserotonin, utilizing a scanning-transmission electron microscope equipped with an energy-loss spectrometer. Discrete intracellular structures corresponding in location to dense bodies contained high concentrations of fluorine. Electron energy-loss spectroscopy, which apparently can detect less than 10
-20
gram of fluorine in an area of 10 square nanometers, can thus localize fluorinated tracer molecules with biological activity.
Criteria for Evidence of Chemical Carcinogenicity
Authors:   Interdisciplinary Panel on Carcinogenicity
Published: October 2006

The Interdisciplinary Panel on Carcinogenicity reviewed and reevaluated criteria for assessing evidence of carcinogenicity of chemical substances. The panel reviewed criteria applicable to data derived from human epidemiological studies and from both in vivo and in vitro laboratory studies. A critical appraisal of all these sources of information led to the conclusion that the characterization of human risk always requires interdisciplinary evaluation of the entire array of data on a case-by-case basis. Animal studies, whenever possible, should be augmented by studies of mechanisms, metabolism, and pharmacodynamics. Such studies may assist in assessing risk to man. Recognizing the utility of such data should point the way for better assessment in the future.
Antidepressants Cause Lethal Disruption of Membrane Function in the Human Protozoan Parasite
Leishmania
Authors: Zilberstein Dan , Dwyer Dennis M.
Published: October 2006

The antidepressant compounds clomipramine and nitroimipramine were cidal to extracellular promastigotes of both human protozoan parasites
Leishmania donovani
and
Leishmania major
. Clomipramine also killed amastigotes of both species within murine macrophages with no apparent toxicity to the host cells. Further, amastigotes were more sensitive than promastigotes to clomipramine. Clomipramine (100 micromoles per liter or 0.2 nanomole per 1 × 10
6
cells) inhibited L-proline transport in promastigotes. Synergistic inhibition of L-proline transport was observed with clomipramine after addition of either of the ionophores valinomycin or nigericin. These observations suggest that the cytotoxic effects of clomipramine result from its disruption of the proton electrochemical gradient of the parasite surface membrane.
Incidence of Low Birth Weight Among Love Canal Residents
Authors: Vianna Nicholas J. , Polan Adele K.
Published: October 2006

The incidence of low birth weight among white live-born infants from 1940 through 1978 was studied in various sections of the Love Canal. A statistically significant excess was found in the historic swale area from 1940 through 1953, the period when various chemicals were dumped in this disposal site. Potential confounding factors such as medical-therapeutic histories, smoking, education, maternal age, birth order, length of gestation, and urban-rural difference did not appear to account for this observation. Low birth weight rates were comparable to those of upstate New York from 1954 through 1978, the period when there was no deposition of chemical wastes.
Receptors for Glucocorticoids in the Lens Epithelium of the Calf
Authors: Southren A. Louis , Gordon Gary G. , Yeh Helena S. , Dunn Michael W. , Weinstein Bernard I.
Published: October 2006

The calf lens epithelium contains a specific cytoplasmic receptor for glucocorticoids. This binding protein has a high affinity for dexamethasone (average dissociation constant, 8 × 10
-9
mole per liter), a low capacity (average, 550 femtomoles per milligram of protein), extreme heat sensitivity, and exhibits a pattern of competition similar to that of glucocorticoid receptors in other tissues. This provides direct biochemical evidence that these tissues may function as a target organ for glucocorticoids.
Illusory Contours and Cortical Neuron Responses
Authors: von der Heydt R. , Peterhans E. , Baumgartner G.
Published: October 2006

Figures in which human observers perceive "illusory contours" were found to evoke responses in cells of area 18 in the visual cortex of alert monkeys. The cells responded as if the contours were formed by real lines or edges. Modifications that weakened the perception of contours also reduced the neuronal responses. In contrast, cells in area 17 were apparently unable to "see" these contours.
A Pure Enzyme Catalyzing Penicillin Biosynthesis
Authors: Hollander I. J. , Shen Y.-Q. , Heim J. , Demain A. L. , Wolfe S.
Published: October 2006

Isopenicillin N synthetase (cyclase) has been purified to homogeneity from
Cephalosporium acremonium
strain C-10. The enzyme has a molecular weight of 40,000 to 42,000 and yields a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was purified in 10 percent yield by a combination of protamine sulfate and ammonium sulfate precipitations, gel filtration, and ion-exchange high-performance liquid chromatography. The purified enzyme can be stabilized with sucrose and stored at -20°C for several weeks without any loss in activity.
Biotechnology as an Intellectual Property
Authors: Adler Reid G.
Published: October 2006

Recent advances in biotechnology have created many public policy and legal issues, one of the most significant of which is the treatment of biotechnological industrial products, particularly under the patent system. Patents represent one of several types of intellectual property; their ownership confers the right to exclude others from benefitting from the tangible products of a proprietary subject matter. Intellectual property law and its protections will play a major role in the rate at which biotechnology develops in the United States. In this article biotechnological intellectual property issues are reviewed in the context of their underlying legal requirements. The implications of other factors, such as international competition, research funding, and gene ownership, are also considered.
Rapid Degradation of "New" Acetylcholine Receptors at Neuromuscular Junctions
Authors: Stanley Elis F. , Drachman Daniel B.
Published: October 2006

Acetylcholine receptors at innervated neuromuscular junctions are very stable, with half-lives reported to be 6 to 13 days. Their turnover is described as a first-order process, implying a single population of receptors. In this study, two subpopulations of acetylcholine receptors at normally innervated junctions have been identified. One has a rapid turnover rate with a half-life of 18.7 hours, similar to that of extrajunctional receptors, and the other has a slow turnover rate with a half-life of 12.4 days. The rapidly turned over subpopulation represents approximately 20 percent of the total junctional receptors. This finding may account for the discrepancies in previous reports of turnover rates and may explain the rapid reversibility in vivo of agents that "irreversibly" block acetylcholine receptors. This finding also implies that the synthesis rate of junctional acetylcholine receptors may be higher than previous estimates. The rapidly turned-over subpopulation may represent receptors that were newly inserted into the neuromuscular junction and that were not yet stabilized by an influence of the motor nerve.
Potentiation of Glucocorticoid Activity by 5β-Dihydrocortisol: Its Role in Glaucoma
Authors: Weinstein Bernard I. , Gordon Gary G. , Southren A. Louis
Published: October 2006

5β-Dihydrocortisol potentiated the threshold level (the smallest dose producing a measurable effect) of topically applied cortisol (0.02 percent) and dexamethasone (0.003 percent) in causing nuclear translocation of the cytosolic glucocorticoid receptor in rabbit iris-ciliary body tissue. 5β-Dihydrocortisol accumulates in cells cultured from trabecular meshwork specimens from patients with primary open-angle glaucoma, but not in similar cells derived from nonglaucomatous patients. In view of the sensitivity of patients with primary open-angle glaucoma to the effects of glucocorticoids in raising intraocular pressure, this potentiation may be responsible for the steroid sensitivity and for the ocular hypertension seen in this disorder.
Alternating Current Delivered into the Scala Media Alters Sound Pressure at the Eardrum
Authors: Hubbard Allyn E. , Mountain David C.
Published: October 2006

Alternating current delivered into the scala media of the gerbil cochlea modulates the amplitude of a test tone measured near the eardrum. Variations in the electromechanical effect with acoustic stimulus parameters and observed physiological vulnerability suggest that cochlear hair cells are the biophysical origin of the process. Cochlear hair cells have traditionally been thought of as passive receptor cells, but they may play an active role in cochlear micromechanics.
Subpicosecond Spectroscopy of Bacteriorhodopsin
Authors: Ippen E. P. , Shank C. V. , Lewis A. , Marcus M. A.
Published: October 2006

Subpicosecond pulses have been used to study the ultrafast dynamics of the photochemistry of bacteriorhodopsin. An optically induced absorption that appears in about 1.0 picosecond at physiological temperatures has been resolved in time. The data can be interpreted in terms of the photochemical formation of bathobacteriorhodopsin and provide support for an excitation mechanism involving molecular rearrangement in the protein induced by electron redistribution in the chromophore.
Antibodies to Purified Insulin Receptor Have Insulin-Like Activity
Authors: Jacobs Steven , Chang Kwen-Jen , Cuatrecasas Pedro
Published: October 2006

Antibodies to insulin receptors purified from rat liver membranes do not complete with [
125
I]insulin for binding to the insulin receptor but do precipitate solubilized receptors labeled with [
125
I]insulin. These antibodies have the insulin-like activities of enhancing glucose oxidation and inhibiting epinephrine-induced lipolysis in rat adipocytes. Thus, antibody binds to the receptor at a different site from that to which insulin binds, yet the interaction can initiate an effective biological response. These results indicate that the previously studied insulin-binding sites are the physiological macromolecular receptors for insulin.
Copulatory Vocalizations of Chacma Baboons (
Papio ursinus
), Gibbons (
Hylobates hoolock
), and Humans
Authors: Hamilton William J. , Arrowood Patricia C.
Published: October 2006

The copulatory vocalizations of female baboons (
Papio ursinus
) are more complex than those of female gibbons (
Hylobates hoolock
) or human females. Adult males of all these species begin calling later than the female, but subordinate baboon males do not call. Copulatory vocalizations may serve to mutually stimulate the mating partners or to incite male competition.
EXAFS: New Horizons in Structure Determinations
Authors: Eisenberger P. , Kincaid B. M.
Published: October 2006

Although the phenomena of extended x-ray absorption fine structure (EXAFS) were observed as early as the 1930's, EXAFS has only recently, with the utilization of synchrotron radiation, been transformed into a powerful structural technique. The theory and experimental practice of the technique are described and illustrated with data on germanium. Applications to systems as diverse as hemoglobin, polymer-bound catalysts, ions in solution, amorphous solids, and adsorbate atoms on surfaces are reviewed. With the recent approval of funding for new, more powerful dedicated synchrotron sources, the future holds the possibility of a virtual revolution in structure determinations.
L-Tryptophan: A Common Denominator of Biochemical and Neurological Events of Acute Hepatic Porphyria?
Authors: Litman David A. , Correia Maria Almira
Published: October 2006

Hepatic porphyrias are disorders of heme synthesis characterized by genetically determined lesions of one of the key enzymes of heme synthesis. In carriers of such lesions, several factors (drugs, environmental chemicals, or diet) precipitate acute and often fatal attacks of neurologic dysfunction, which are promptly relieved by intravenous infusion of heme. However, the mechanism of such heme-induced amelioration remains elusive. To probe this mechanism, the biochemical events triggered by acute hepatic heme deficiency were examined in an animal model of chemically induced porphyria. Acute hepatic heme depletion in porphyric rats was found to impair hepatic tryptophan pyrrolase activity which, in turn, elevated tryptophan and 5-hydroxytryptamine turnover in the brain. These alterations in porphyric rats were dramatically reversed by parenteral heme administration. These findings suggest that increased tryptophan and 5-hydroxytryptamine in the nervous system may be responsible for the neurologic dysfunctions observed in humans with acute attacks of hepatic porphyria.
Memory Retrieval: A Time-Locked Process in Infancy
Authors: Fagen Jeffrey W. , Rovee-Collier Carolyn
Published: October 2006

Three-month-old infants learned to activate an overhead crib mobile by operant footkicking and received a visual reminder of the event (a "reactivation treatment") 2 weeks later, after forgetting had occurred. Subsequent manifestation of the association was a monotonic increasing function of time since the reactivation treatment, and performance of infants tested 8 hours after the reminder was related to the time spent sleeping in the interim (
r
= 0.75). These data demonstrate that normal retrieval is time-dependent. Moreover, individual data suggest that retrieval may be continuous rather than discontinuous.