bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Shock Genes: Regulatory Role for Differentiation in Parasitic Protozoa
Authors: Van der Ploeg Lex H. T. , Giannini Suzanne H. , Cantor Charles R.
Published: October 2006

The parasitic protozoa
Trypanosoma brucei
and
Leishmania major
are transmitted by insect vectors to their mammalian hosts. The temperature difference between the hosts (25° and 37°C) may induce a heat shock response in the parasite. Transcripts of heat shock genes (homologous to Hsp70 and Hsp83) were 25 to 100 times more abundant in
Trypanosoma brucei
bloodstream forms (trypomastigotes) than in insect (procyclic) stages. In
Leishmania major
the patterns of heat shock gene expression in promastigotes (insect-adapted) and amastigotes (mammal-adapted) were different. A temperature shift in vitro induced differentiation of
Leishmania major
from promastigotes to amastigotes. Therefore, heat shock genes may be responsible for differentiation of these vector-borne parasites.
Regional Brain Dopamine Metabolism: A Marker for the Speed, Direction, and Posture of Moving Animals
Authors: Freed Curt R. , Yamamoto Bryan K.
Published: October 2006

Brain dopamine is necessary for normal movement. To determine whether there is a precise relation between the intensity of movement and changes in brain dopamine metabolism, the investigators ran rats on straight and circular treadmills at different speeds and with different body postures. Concentrations of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid increased in the caudate and accumbens nuclei in direct relation to the speed and angular posture of the animals. Dopamine metabolism in the nucleus accumbens was more strongly linked to the speed and direction of movement, while in the caudate nucleus dopamine and 3,4-dihydroxyphenylacetic acid were affected most by posture and direction.
Auditory Responses in Avian Vocal Motor Neurons: A Motor Theory for Song Perception in Birds
Authors: Williams Heather , Nottebohm Fernando
Published: October 2006

The hypoglossal motor neurons that innervate the vocal organ (syrinx) of the male zebra finch show a selective, long-latency (50-millisecond) response to sound. This response is eliminated by lesions to forebrain song-control nuclei. Different song syllables elicit a response from different syringeal motor neurons. Conspecific vocalizations may therefore be perceived as members of a set of vocal gestures and thus distinct from other environmental sounds. This hypothesis is an avian parallel to the motor theory of speech perception in humans.
Defining Lipid Transport Pathways in Animal Cells
Authors: Pagano Richard E. , Sleight Richard G.
Published: October 2006

A new technique for studying the metabolism and intracellular transport of lipid molecules in living cells based on the use of fluorescent lipid analogs is described. The cellular processing of various intermediates (phosphatidic acid and ceramide) and end products (phosphatidylcholine and phosphatidylethanolamine) in lipid biosynthesis is reviewed and a working model for compartmentalization during lipid biosynthesis is presented.
Hydrogen Peroxide Induces Spawning in Mollusks, with Activation of Prostaglandin Endoperoxide Synthetase
Authors: Morse Daniel E. , Duncan Helen , Hooker Neal , Morse Aileen
Published: October 2006

Addition of hydrogen peroxide to seawater causes synchronous spawning in gravid male and female abalones, and certain other mollusks as well. This effect is blocked by exposure of the animals to aspirin, an inhibitor of the enzyme catalyzing oxidative synthesis of prostaglandin endoperoxide. Hydrogen peroxide activates this enzymatic reaction in cell-free extracts prepared from abalone eggs (a very rich source of the prostaglandin endoperoxide synthetase); this effect appears to reveal a fundamental property of prostaglandin endoperoxide synthesis. Applicability of these findings to both mariculture and medical purposes is suggested.
Muscle Crossbridge Stroke and Activity Revealed by Optical Diffraction
Authors: Barden Julian A. , Mason Peter
Published: October 2006

Optical diffraction measurements during rapid releases of active toad muscle show that the sarcomeres contract within 1 millisecond by an amount up to but not greater than 12 nanometers. This distance is identified with the effective working stroke of a crossbridge. The crossbridges immediately start cycling to produce the normal contraction velocity in unloaded muscle.
Opioid Peptides Modulate Luteinizing Hormone Secretion During Sexual Maturation
Authors: Blank Michael S. , Panerai Alberto E. , Friesen Henry G.
Published: October 2006

Subcutaneous injections of naloxone, an opiate antagonist, lead to an increase in serum luteinizing hormone concentrations in female but not in male rats before they reach puberty. In addition, estradiol benzoate specifically blocks the luteinizing hormone response to naloxone in prepubertal female rats, suggesting that the opioid peptides have a physiological role in the endocrine events leading to sexual maturation.
Sodium-Selective Liquid Ion-Exchanger Microelectrodes for Intracellular Measurements
Authors: O'Doherty J. , Garcia-Diaz J. F. , Armstrong W. McD.
Published: October 2006

The sodium-selective ligand 1,1,1-tris[1
1
-(2
1
-oxa-4
1
-oxo-5
1
-aza-5
1
-methyl)dodecanyl]propane dissolved in 3-nitro-o-xylene containing a small amount of the lipophilic anion tetrachlorophenyl borate was used as a liquid ion-exchanger in sodium-selective microelectrodes. The microelectrodes gave rapid, stable responses that were linear functions of the logarithm of sodium activity. They were tested under conditions approximating those to be expected in the cell interior, and the results indicated that they can be used to measure intracellular sodium activity without significant interference from intracellular potassium.
Embryonic Rodent Brain Contains Estrogen Receptors
Authors: Vito Christine C. , Fox Thomas O.
Published: October 2006

Estradiol-binding proteins with the properties of putative estrogen receptors are present in cytosol extracts of embryonic mouse hypothalamus and other brain regions. These embryonic estrogen receptors are adultlike in their high affinity and limited capacity for estradiol, sensitivity to diethylstilbestrol, ability to adhere to DNA, and behavior during DNA-cellulose affinity chromatography. As early as 4 days before birth, mouse hypothalamus has approximately 40 percent of the adult concentration of hypothalamic estrogen receptors with these properties. These observations raise the possibility that embryonic rodent brain has the biochemical potential to respond to sex hormones and that the critical period of brain sexual differentiation could be initiated prenatally.
Human Skin Fibroblasts Derived from Papillary and Reticular Dermis: Differences in Growth Potential in Vitro
Authors: Harper Robert A. , Grove Gary
Published: October 2006

Papillary fibroblasts, when compared to reticular fibroblasts from the same skin specimen, exhibit greater proliferative capacities in vitro. These results demonstrate a difference in function between morphologically similar cells obtained from the same tissue. Such findings represent an important consideration in the study of cell aging in vitro.
A Synthetic Pentapeptide with Biological Activity Characteristic of the Thymic Hormone Thymopoietin
Authors: Goldstein Gideon , Scheid Margrit P. , Boyse Edward A. , Schlesinger David H. , Van Wauwe Jean
Published: October 2006

The pentapeptide arginyl-lysyl-aspartyl-valyl-tyrosine, corresponding to amino acid residues 32-36 in thymopoietin, was synthesized. In vitro, this pentapeptide induced the differentiation of murine prothymocytes to thymocytes and inhibited differentiative induction of cells of the B lineage. This combination of actions is presently unique to the parent molecule thymopoietin. In vivo, the pentapeptide reduced the high numbers of autologous rosette-forming cells normally present in the spleens of athymic mice; this also is a property of thymopoietin. These results suggest that this readily synthesized pentapeptide corresponds to an active site of thymopoietin and might serve as a therapeutic substitute for thymopoietin.
Evidence for Extra-Renal 1 α-Hydroxylation of 25-Hydroxyvitamin D
3
in Pregnancy
Authors: Gray T. Kenney , Lester Gayle E. , Lorenc Roman S.
Published: October 2006

The kidneys are thought to be the only organs capable of 1 α-hydroxylation of vitamin D and its metabolites. We have examined the in vivo conversion of
3
H-(25,26)-25-hydroxyvitamin D
3
(25OHD
3
) to
3
H-(25,26)-1 α,25-dihydroxyvitamin D
3
[1α,25(OH)
2
D
3
] in vitamin D-deficient, pregnant and nonpregnant rats. As expected, nephrectomy of nonpregnant, vitamin D-deficient rats prevented the conversion of 25OHD
3
to 1α,25(OH)
2
D
3
. In contrast, nephrectomy of pregnant, vitamin D-deficient rats reduced but did not abolish the formation of 1 α,25(OH)
2
D
3
from its precursor. The identity of the radioactive metabolite formed from
3
H-25OHD
3
which circulated in nephrectomized, pregnant rats was established as 1α,25(OH)
2
D
3
by comigration with synthetic 1 α,25(OH)
2
D
3
on high-pressure liquid chromatography. The simultaneous absence of 1 α,25(OH)
2
D
3
in the fetal kidneys indicated that the site of 1 α-hydroxylation after nephrectomy of the pregnant rat was probably extra-renal in origin. Two sites of 1 α-hydroxylation of 25OHD
3
, one renal and the other extra-renal, either fetoplacental or maternal, may exist in the pregnant, vitamin D-deficient rat.
Muscle Fiber Regeneration After Transplantation: Prediction of Structure and Physiology from Electromyograms
Authors: Gorniak Gerard C. , Gans Carl , Faulkner John A.
Published: October 2006

Digitized electromyographic activity of transplanted extensor digitorum longus (EDL) muscles in cats differs from that of control EDL and anterior tibialis muscles lying adjacent to transplanted EDL muscles. In autotransplanted muscles, the cross-sectional area of the fibers shows a negative correlation with mean spike frequency and a positive correlation with mean amplitude. The mean frequency-amplitude products correlate with isometric tetanic tensions.
Diffusion-Like Process Can Account for Protein Secretion by the Pancreas
Authors: Isenman Lois D. , Rothman S. S.
Published: October 2006

When fluid secretion by the pancreas was mechanically blocked, amylase secretion into the duct ceased. When flow was reduced in a graded fashion by the application of a back pressure, amylase output was reduced proportionately and amylase concentration in secretion was maintained constant. Thus, the secretion of digestive enzyme from the cell into the duct appears to be dependent upon the concentration of enzyme in the duct system. This behavior is most simply explained by diffusion-like (concentration dependent, bidirectional) fluxes of digestive enzyme across the plasma membrane. A unidirectional process, such as exocytosis, whose rate should be unaffected by fluid flow, cannot readily explain these results.
Noradrenergic Innervation of Cerebral Cortex: Widespread Effects of Local Cortical Lesions
Authors: Morrison John H. , Molliver Mark E. , Grzanna Reinhard
Published: October 2006

The trajectory of the intracortical noradrenergic fibers has been characterized by histochemical analysis following the production of cortical lesions in the rat. A large group of noradrenergic fibers enters the cortex at the frontal pole and proceeds caudally through the deep layers of dorsolateral cortex. Branches arise from these longitudinally directed fibers and form a uniform pattern of innervation throughout lateral cortex. Because these fibers travel long distances rostrocaudally within the gray matter, a large area of cortex can be deprived of noradrenergic innervation by a relatively small lesion of frontal cortex. The medial and lateral cortex can be selectively and differentially denervated of noradrenergic fibers, and there is a medial to lateral topographic relationship between deep longitudinally running fibers and overlying cortex.
Genes Coding for Histone Proteins in Man Are Located on the Distal End of the Long Arm of Chromosome 7
Authors: Chandler Mary E. , Kedes Laurence H. , Cohn Ronald H. , Yunis Jorge J.
Published: October 2006

Tritium-labeled complementary RNA's to two cloned sea urchin DNA sequences, one coding for histones H1, H2B, and H4 and the other for H2A and H3, were hybridized in situ to high resolution human chromosomes. Evidence is presented showing that the histone genes in man are localized in bands q32-36 on the long arm of chromosome 7.
Vascular Smooth Muscle Cell Kinetics: a New Assay for Studying Patterns of Cellular Proliferation in Vivo
Authors: Goldberg Itzhak D. , Stemerman Michael B. , Schnipper Lowell E. , Ransil Bernard J. , Crooks Gary W. , Fuhro Robert L.
Published: October 2006

A new quantitative assay for studying the kinetics of vascular smooth muscle cells in vivo is reported. The assay was used to determine the specific activity of DNA from rabbit aortic smooth muscle cells stimulated to grow by removal of the endothelial layer. The specific activity of the DNA was correlated with the rate of tritiated thymidine incorporation as measured by autoradiography and with the rate of DNA synthesis as estimated by direct measurement of cellular proliferation. Smooth muscle cells exhibit a 24-hour latent period in vivo prior to DNA synthesis; the synthesis peaks at 48 hours and then rapidly declines. The decline in DNA synthesis is not related to endothelial regrowth, and may be of homeostatic significance in limiting luminal stenosis. The assay offers a rapid and reliable alternative to autoradiographic and morphometric techniques for evaluating growth kinetics and growth regulation in vivo.
Mutual Repulsion Between Moving Visual Targets
Authors: Marshak William , Sekuler Robert
Published: October 2006

When two spatially intermingled sets of random dots move in different directions, the direction of each set may be misperceived. Observers report that each set of dots appears to move in a direction displaced by as much as 20° from the direction of its companion set. Probably the result of inhibitory interactions, this mutual repulsion occurs at a central site in the visual system and may normally enhance discrimination of direction.
Dolphin Lung Collapse and Intramuscular Circulation During Free Diving: Evidence from Nitrogen Washout
Authors: Ridgway Sam H. , Howard Red
Published: October 2006

Intramuscular nitrogen tensions in
Tursiops truncatus
after a schedule of repetitive ocean dives suggest a lung collapse depth of about 70 meters and suggest that intramuscular circulation is maintained during unrestrained diving in the open ocean. Therefore, the bottle-nosed dolphin is not protected by lung collapse from the decompression hazards of dives to depths shallower than 70 meters.
Temperature-Dependent Sex Determination in Turtles
Authors: Bull J. J. , Vogt R. C.
Published: October 2006

The sex of hatchling map turtles is determined by incubation temperature of eggs in the laboratory as well as in nature. Temperature controls sex differentiation rather than causing a differential mortality of sexes. Temperature has no effect on sex determination in a soft-shelled turtle.
Long-Term Treatment with Lithium Prevents the Development of Dopamine Receptor Supersensitivity
Authors: Pert Agu , Rosenblatt Jack E. , Sivit Carlos , Pert Candace B. , Bunney William E.
Published: October 2006

Long-term treatment of rats with haloperidol produced an increased sensitivity to the locomotor and stereotypic effects of apomorphine. This behavioral dopaminergic supersensitivity was accompanied by increased binding of [
3
H]spiroperidol in the striatum. Rats treated concurrently with lithium and haloperidol failed to develop both behavioral sensitivity to apomorphine and increased striatal dopamine receptor binding. The ability of lithium to prevent recurrent manicdepressive episodes may be related, in part, to its ability to stabilize dopaminergic receptor sensitivity.
Alternative RNA Processing: Determining Neuronal Phenotype
Authors: Rosenfeld Michael G. , Amara Susan G. , Evans Ronald M.
Published: October 2006

On the basis of an analysis of the human and rat calcitonin genes and of a related gene, alternative RNA processing represents a developmental strategy of the brain to dictate tissue-specific patterns of polypeptide synthesis. This regulation allows the calcitonin gene to generate two messenger RNA's, one encoding the precursor of a novel neuropeptide, referred to as CGRP, which predominates in the brain, and the second encoding the precursor to the hormone calcitonin which predominates in thyroid C cells. The distribution of CGRP in the central and peripheral nervous system and in endocrine and other organ systems suggests potential functions in nociception, ingestive behavior, cardiovascular homeostasis, and mineral metabolism.
Optical Measurements of Extracellular Calcium Depletion During a Single Heartbeat
Authors: Cleemann L. , Pizarro G. , Morad M.
Published: October 2006

The impermeant dye antipyrylazo III was used to measure depletion of extracellular calcium and net influx of calcium through the sarcolemma during the cardiac action potential. It was found that calcium entry occurs continuously during the action potential and is under direct control of the membrane potential. The inotropic action of epinephrine is accompanied by increased influx of calcium, while strophanthidin enhances the twitch without altering calcium influx during the action potential.
Prospects for Human Gene Therapy
Authors: Anderson W. French
Published: October 2006

Procedures have now been developed for inserting functional genes into the bone marrow of mice. The most effective delivery system at present uses retroviral-based vectors to transfer a gene into murine bone marrow cells in culture. The genetically altered bone marrow is then implanted into recipient animals. These somatic cell gene therapy techniques are becoming increasingly efficient. Their future application in humans should result in at least partial correction of a number of genetic disorders. However, the safety of the procedures must still be established by further animal studies before human clinical trials would be ethical.
Compensatory Increase in Tyrosine Hydroxylase Activity in Rat Brain After Intraventricular Injections of 6-Hydroxydopamine
Authors: Acheson Ann L. , Zigmond Michael J. , Stricker Edward M.
Published: October 2006

The neurotoxin 6-hydroxydopamine produced a permanent loss of endogenous norepinephrine and of
3
H-labeled norepinephrine uptake sites in the hippocampus within 5 days. These losses were initially accompanied by parallel decreases in tyrosine hydroxylase activity and synaptosomal norepinephrine synthesis. Within 21 days, however, hippocampal tyrosine hydroxylase activity and norepinephrine synthesis rate increased three- to fivefold. These data suggest a novel form of plasticity in brain-damaged animals characterized by an increase in the capacity for transmitter biosynthesis in residual neurons.
Biotin Enhances Guanylate Cyclase Activity
Authors: Vesely David L.
Published: October 2006

Biotin and its analog, (+)-biotin-
p
-nitrophenyl ester enhanced guanylate cyclase activity two- to threefold in rat liver, kidney, colon, cerebellum, and heart. Dose-response relationships revealed that at concentrations as low as 1 micromolar, both biotin and its analog caused maximal augmentation of guanylate cyclase activity. These data suggest a role for the activation of guanylate cyclase in the mechanism of action of this vitamin.
An Excitatory Amino Acid Antagonist Blocks Cone Input to Sign-Conserving Second-Order Retinal Neurons
Authors: Slaughter Malcolm M. , Miller Robert F.
Published: October 2006

cis
-2,3-Piperidinedicarboxylic acid (PDA), an excitatory amino acid antagonist, reversibly blocked cone input to OFF bipolars and horizontal cells, whereas ON bipolars were relatively unaffected. Kainic acid effects were also blocked, indicating a postsynaptic mechanism of action. The use of PDA helps to characterize one of two classes of excitatory amino acid synaptic receptors that mediate cone influence in the outer retina.
Immunohistochemistry of Adenosine Deaminase: Implications for Adenosine Neurotransmission
Authors: Nagy J. I. , LaBella L. A. , Buss M. , Daddona P. E.
Published: October 2006

Immunohistochemical analysis of adenosine deaminase in rat brain revealed an extensive plexus of adenosine deaminase-containing neurons in the basal hypothalamus. These neurons converged on and were most numerous in three major centers, namely, the tuberal, caudal, and postmammillary caudal magnocellular nuclei. Most other brain regions were devoid of cells containing adenosine deaminase. Some adenosine deaminase-containing neurons were retrogradely labeled with the fluorescent dye fast blue when the dye was injected into the frontal cortex and striatum. Specific populations of neurons having high levels of adenosine deaminase may release adenosine as a neurotransmitter.
Bimodal Distribution of Dopamine Receptor Densities in Brains of Schizophrenics
Authors: Seeman P. , Ulpian C. , Bergeron C. , Riederer P. , Jellinger K. , Gabriel E. , Reynolds G. P. , Tourtellotte W. W.
Published: October 2006

The dopamine hypothesis of schizophrenia was examined by measuring the density of dopamine receptors in the postmortem brains of 81 control subjects and 59 schizophrenics from four different countries. The densities of dopamine receptors in the tissues from the schizophrenic patients had a bimodal distribution in the caudate nucleus, putamen, and nucleus accumbens. One mode occurred 25 percent above the control density, and a second mode occurred at a density 2.3 times that of the control density for all three regions. Although almost all the patients had been medicated with neuroleptics, the two modes had the same dissociation constant for the labeled ligand used, suggesting that the neuroleptic doses were similar for the two populations of schizophrenics. The results thus provide direct evidence for two distinct categories of schizophrenia.
Chronic Arthritis in Goats Caused by a Retrovirus
Authors: Crawford T. B. , Adams D. S. , Cheevers W. P. , Cork L. C.
Published: October 2006

A virus was isolated from an adult goat with chronic arthritis and shown to belong to the retrovirus group by electron microscopy and biochemical methods. Inoculation of the virus into cesarean-derived specific-pathogen-free goats' kids produced arthritic lesions similar to those in the spontaneous disease. Virus was reisolated from the experimentally induced lesions.
Leucine Enkephalin: Localization in and Axoplasmic Transport by Sacral Parasympathetic Preganglionic Neurons
Authors: Glazer Ellyn J. , Basbaum Allan I.
Published: October 2006

Nerve processes and cell bodies containing leucine enkephalin were demonstrated in the sacral autonomic nucleus of the cat by immunocytochemical methods. Enkephalinergic preganglionic perikarya were seen only when axonal transport was blocked either by colchicine or by ventral root ligation. Ligation of the sacral ventral roots also produced damming of enkephalin immunoreactivity proximal to the S
2
ligature. These data indicate that parasympathetic preganglionic neurons synthesize and transport enkephalin or enkephalin-like immunoreactive compounds to the periphery.
Sensory and Motor Functions of Spinal Cord Substance P
Authors: Piercey Montford F. , Schroeder Lawrence A. , Folkers Karl , Xu J.-C. , Horig J.
Published: October 2006

Low doses of D-Pro
2
-D-Phe
7
-D-Trp
9
-substance P, a specific substance P antagonist, depressed the scratching and biting behaviors elicited by intrathecal injections of substance P, and cutaneous application of algesic substances. Higher antagonist doses caused hindlimb paralysis. This suggests that substance P is a neurotransmitter for primary nociceptor afferents and may also have an important function in motor control.
Molecular Weight of Human Gamma Interferon Is Similar to that of Other Human Interferons
Authors: Yip Y. K. , Barrowclough Barbara S. , Urban Carl , Vilček Jan
Published: October 2006

The molecular weight (as determined by molecular sieve chromatography) of human gamma interferon, formerly referred to as immune or type II interferon, is between 40,000 and 70,000. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gamma interferon activity was recovered mainly from two regions of the gels corresponding to molecular weights of 20,000 and 25,000. The results suggest that in native form human gamma interferon may be aggregated.
Basement Membrane Collagen: Degradation by Migrating Endothelial Cells
Authors: Kalebic Tea , Garbisa S. , Glaser B. , Liotta L. A.
Published: October 2006

One of the first steps in neovascularization is dissolution of the basement membrane at the point of endothelial outgrowth. An assay was developed to determine whether basement membrane collagens (types IV and V) are degraded by endothelial cells migrating toward a chemotactic stimulus. Fetal bovine endothelial cells were placed on one side of a filter containing the collagen substrate, and a chemoattractant derived from retinal extracts was placed on the opposite side. Degradation of both type IV and type V collagens was observed when the retinal factor was placed on the side of the filter opposite the endothelial cells. Metalloproteinases that cleaved type IV and type V collagens could be extracted from the endothelial cells with detergents. Such endothelial cell-associated (possibly membrane-bound) proteinases may locally disrupt the basement membrane and facilitate the outgrowth of capillary sprouts toward the angiogenic stimulus.
Nicotine in Breast Fluid of Nonlactating Women
Authors: Petrakis Nicholas L. , Gruenke Larry D. , Beelen Trudy C. , Castagnoli Neal , Craig J. Cymerman
Published: October 2006

Using a combination of gas chromatography, mass spectrometry, and selected ion recording techniques, we have identified nicotine and its major metabolite, cotinine, in the breast fluid of nonlactating women smokers. As little as 25 picograms could be measured by using the deuterated variants, [5′,5′-2H]nicotine and [3,3-2H]cotinine, both as internal standards and as carriers in an inverse isotope dilution method.
The Enzymatic Synthesis of 5-Amino-4-Imidazolecarboxamide Riboside Triphosphate (ZTP)
Authors: Sabina Richard L. , Holmes Edward W. , Becker Michael A.
Published: October 2006

5-Amino-4-imidazolecarboxamide riboside triphosphate (ZTP) is thought to play a regulatory role in cellular metabolism. Unlike other nucleoside triphosphates, ZTP is synthesized in a one-step reaction in which the pyrophosphate group of 5-phosphoribosyl-1-pyrophosphate is transferred to the riboside monophosphate (ZMP) in a reaction catalyzed by 5-phosphoribosyl-1-pyrophosphate synthetase; reversal of this reaction leads to dephosphorylation of ZTP to ZMP. This unusual route of synthesis (and catabolism) of ZTP may be important in defining its metabolic effects in the cell.
Functional Properties of Antigen-Specific T Cells Infected by Human T-Cell Leukemia-Lymphoma Virus (HTLV-I)
Authors: Mitsuya Hiroaki , Guo Hong-Guang , Cossman Jeffrey , Megson Mary , Reitz Marvin S. , Broder Samuel
Published: October 2006

Tetanus-toxoid specific helper-inducer T-cell clones, which had been infected and transformed by human T-cell leukemia-lymphoma virus (HTLV-I), were obtained from an antigen-specific human T cell line by using a limiting dilution technique in the presence of the virus. These HTLV-I-infected T-cell clones proliferated specifically in response to soluble tetanus toxoid but, unlike normal T cells, they could do so in the absence of accessory cells. The HTLV-I-infected T-cell clones did not present the antigen to autologous antigen-specific T cells that were not infected with HTLV-I. The capacity of helper-inducer T cells to retain antigen-specific reactivity after infection by HTLV-I, while losing the normal T-cell requirement for accessory cells, has clinical and theoretical implications.
Detection of c-
sis
Transcripts and Synthesis of PDGF-Like Proteins by Human Osteosarcoma Cells
Authors: Graves D. T. , Owen A. J. , Barth R. K. , Tempst P. , Winoto A. , Fors L. , Hood L. E. , Antoniades H. N.
Published: October 2006

Platelet-derived growth factor (PDGF) has been previously shown to be homologous to the transforming gene of simian sarcoma virus (v-
sis
"), and inappropriate expression of the cellular counterpart of the v-
sis
" gene (c-
sis
") has been implicated in the generation of mesenchymal tumors. The U-2 OS human osteosarcoma line was shown to contain multiple c-
sis
" transcripts. Immunoprecipitation experiments with antiserum to PDGF identified a variety of polypeptides ranging in size from 18,000 to 165,000 daltons that were immunoprecipitated specifically from U-2 OS cell extracts. The osteosarcoma also was shown to secrete a 29,000-dalton protein having the serological and structural characteristics of PDGF.
Chronologic and Physiologic Age Affect Replicative Life-Span of Fibroblasts from Diabetic, Prediabetic, and Normal Donors
Authors: Goldstein Samuel , Moerman Elena J. , Soeldner J. Stuart , Gleason Ray E. , Barnett Donald M.
Published: October 2006

Cultured skin fibroblasts from subjects with clinically apparent diabetes mellitus and from subjects genetically predisposed to diabetes have a replicative lifespan that is inversely related to donor age. Fibroblasts from carefully defined normal subjects not predisposed to diabetes fail to show this correlation. The data support the idea that physiologic status of the tissue donor is a more precise determinant of fibroblast replicative lifespan than chronologic age.
Detection of Bityrosine in Cataractous Human Lens Protein
Authors: Garcia-Castineiras Sixto , Dillon James , Spector Abraham
Published: October 2006

Bityrosine was isolated from the insoluble protein of human cataractous lenses. Identification was based on correspondence with synthetic bityrosine with respect to chromatography, fluorescence, and ultraviolet and mass spectra. It is suggested that the compound may form cross-links with polypeptide chains in old and cataractous lenses, causing significant alteration in native protein structure.
Contact-Mediated Bone Resorption by Human Monocytes in Vitro
Authors: Kahn Arnold J. , Stewart Carleton C. , Teitelbaum Steven L.
Published: October 2006

Human circulating monocytes in tissue culture are capable of resorbing devitalized adult and fetal bone. An important component of this process is the adhesion of the cells to the mineralized substrate and the localized removal of matrix from beneath the attached cells. The process appears to involve both release of lysosomal enzymes onto the substrate and intracellular accumulation (transport) of resorbed matrix.
Cholecystokinin Receptors in the Brain: Characterization and Distribution
Authors: Saito Atsushi , Sankaran Hariharan , Goldfine Ira D. , Williams John A.
Published: October 2006

Specific cholecystokinin binding sites in particulate fractions of rat brain were measured with iodine 125-labeled Bolton-Hunter cholecystokinin, a cholecystokinin analog that has full biological activity. Binding was detected in brain regions known to contain immunoreactive cholecystokinin. Binding was saturable, reversible, of high affinity (dissociation constant, 1.7 × 10
-9
M
), and was inhibited by cholecystokinin analogs but not by unrelated hormones.
Levels of Batrachotoxin and Lack of Sensitivity to Its Action in Poison-Dart Frogs (
Phyllobates
)
Authors: Daly John W. , Myers Charles W. , Warnick Jordan E. , Albuquerque Edson X.
Published: October 2006

Batrachotoxin is present in remarkably high amounts in the skin of
Phyllobates terribilis
. Levels of batrachotoxin tend to be reduced when
P. terribilis
is maintained in captivity, but even after being confined for up to 6 years, these frogs were still at least five times more toxic than other
Phyllobates
species used by natives for poisoning blowgun darts. Batrachotoxin was not detectable in F
1
progeny reared to maturity in captivity. Nerve and muscle preparations from wild-caught frogs and from the nontoxic F
1
frogs were both insensitive to batrachotoxin. The regulatory site controlling sodium-channel activation and permeability appears to have been minimally altered to prevent interaction with batrachotoxin, but is still sensitive to other sodium conductance activators (veratridine, grayanotoxin) to which the frogs are not exposed naturally.
Tumor DNA Structure in Plant Cells Transformed by
A. tumefaciens
Authors: Zambryski Patricia , Holsters Marcelle , Kruger Kelly , Depicker Ann , Schell Josef , Van Montagu Marc , Goodman Howard M.
Published: October 2006

Crown gall tumors are induced in plants by infection with the soil bacterium
Agrobacterium tumefaciens
. Because the tumor induction involves transfer of a portion of the tumor-inducing (Ti) plasmid DNA from the bacterium to the plant cells, this system is of interest for the study of genetic exchange as well as tumor induction. The boundaries of the transferred DNA (T-DNA) have been cloned from transformed plant cells of tobacco. Detailed mapping with restriction enzymes and nucleotide sequence analysis of two independent clones were used to study the molecular structure of the ends of the T-DNA. One clone contains the two ends of the T-DNA joined together; the other contains one end of the T-DNA joined to repetitive plant DNA sequences. These studies provide direct evidence that the T-DNA can be integrated into the plant genome. In addition, the data suggest that in the plant, T-DNA can be tandemly repeated. Sequence analysis of the junction of crown gall clone 1 reveals several direct repeats as well as an inverted repeat; these structures may be involved in the transfer of the DNA from
Agrobacterium
to plant cells.
Catecholamine-Induced Alteration in Sedimentation Behavior of Membrane Bound β-Adrenergic Receptors
Authors: Harden T. Kendall , Cotton Calvin U. , Waldo Gary L. , Lutton John K. , Perkins John P.
Published: October 2006

Incubation of astrocytoma cells with catecholamines results in a decrease in catecholamine-stimulated adenylate cyclase activity and a concomitant alteration in the sedimentation properties of particulate β-adrenergic receptors. The altered receptors exhibit agonist binding properties similar to those of receptors that are "uncoupled" from adenylate cyclase.
2-Amino-4-Phosphonobutyric Acid: A New Pharmacological Tool for Retina Research
Authors: Slaughter Malcolm M. , Miller Robert F.
Published: October 2006

Information processing in the vertebrate retina occurs in two separate channels known as ON and OFF channels. When intracellular electrophysiological recordings were obtained from the perfused retina-eyecup preparation of the mudpuppy (Necturus maculosus), the addition of 2-amino-4-phosphonobutyric acid to the bathing medium blocked all responses in the ON channel but left intact the OFF responses including OFF ganglion cell discharge. 2-Amino-4-phosphonobutyric acid blocks the light response of the ON bipolar cell by mimicking the endogenous photoreceptor transmitter.
Polypeptide-Binding Membrane Receptors: Analysis and Classification
Authors: Kaplan Jerry
Published: October 2006

Polypeptide receptors on mammalian plasma membranes can be categorized on the basis of function. The binding of ligand by class I receptors results in changes in cell metabolism or behavior. Hormone-receptor interactions typify this group. The binding of ligand by class II receptors results in ligand internalization. Although changes in cellular activity may result from metabolism of the internalized ligand, the interaction between ligand and class II receptor does not itself lead to alterations in cell behavior. Class II receptors include those for low-density lipoproteins and for α-macroglobulin-protease complexes. Although receptors within each category are chemically disparate, they show striking similarities in behavior. Analysis of the behavioral patterns of receptors in each category reveals insights into receptor physiology and allows for a prospective analysis of receptor characteristics.
Morphiceptin (NH
4
-Tyr-Pro-Phe-Pro-COHN
2
): a Potent and Specific Agonist for Morphine (μ) Receptors
Authors: Chang Kwen-Jen , Lillian Anthony , Hazum Eli , Cuatrecasas Pedro , Chang Jaw-Kang
Published: October 2006

The synthetic peptide NH
2
-Tyr-Pro-Phe-Pro-CONH2 (morphiceptin), which is the amide of a fragment of the milk protein β-casein, has morphinelike activities and is highly specific for morphine (μ) receptors but not for enkephalin (δ) receptors. It is as active as morphine in the guinea pig ileum but much less active in the mouse and rat vas deferens. The discovery of this specific morphine receptor ligand substantiates the hypothesis of multiple opiate receptors. The ligand, which may be of physiological significance since a very similar, or identical, activity can be detected in enzymatic digests of β-casein, may prove useful for further investigation of the functions of opiate receptor subtypes.
5-Methylcytosine in Eukaryotic DNA
Authors: Ehrlich Melanie , Wang Richard Y.-H.
Published: October 2006

A small portion of the cytosine residues in the DNA of higher eukaryotes as well as in that of many lowe eukaryotes if methylated. The resulting 5-methylcytosine residues occur in specific in the DNA, usually adjacent to guanine residues on the 3' side. This methylation of eukaryotic DNA has been proposed to function in many ways, including control of transcription, maintenance of chromosome structure, repair of DNA, establishment of preferred sites for mutation, oncogenic transformation, and, in certain systems, protection of DNA against enzymatic degradation.
Inserted Sequences in Bovine Satellite DNA's
Authors: Streeck Rolf E.
Published: October 2006

The nucleotide sequence of the 1413-base-pair repeat unit of bovine 1.711a satellite DNA (density in cesium chloride, 1.711 grams per cubic centimeter) has been determined. The repeat unit contains two segments consisting of variants of a basic 23-base-pair sequence that is closely related to sequences of bovine 1.706 satellite DNA. A third segment of the repeat unit contains an unrelated 611-base-pair sequence that is not internally repetitive. This segment is flanked by inverted repeats of 8 base pairs and, on one side, by a direct repeat of the terminal sequence. A related segment is present in bovine 1.711b satellite DNA and is inserted into sequences derived from the 1.715 satellite. These nucleotide sequences suggest the timing of some of the stages in the evolution of these complex, closely related satellite DNA's and indicate the mechanisms inherent in their divergence from a common ancestor.
Milk of Dairy Cows Frequently Contains a Leukemogenic Virus
Authors: Ferrer Jorge F. , Kenyon Simon J. , Gupta Phalguni
Published: October 2006

Milk or viable milk cells collected from 24 dairy cattle naturally infected with bovine leukemia virus were inoculated into lambs, which were subsequently examined for the development of infection. With this bioassay, infectious virus was demonstrated in the milk of 17 of the cows. Bovine leukemia virus is leukemogenic in at least two mammalian species, is widespread in commercial dairy herds, and can infect a wide range of hosts in vivo and cells, including human cells, in vitro.
Increased Pyrophosphate in Fibroblasts and Lymphoblasts from Patients with Hereditary Diffuse Articular Chondrocalcinosis
Authors: Lust G. , Faure G. , Netter P. , Seegmiller J. E.
Published: October 2006

The metabolic and genetic factors leading to deposition of calcium pyrophosphate crystals in cartilage of patients with chondrocalcinosis are not well understood. Analysis of cultured fibroblasts and lymphoblasts from 12 affected members of a large kindred showed a mean concentration of intracellular inorganic pyrophosphate two times greater than that in cells from unaffected family members or normal, unrelated volunteers. Increased intracellular pyrophosphate may, therefore, be a biochemical marker for the heterozygous expression of the chondrocalcinosis gene.
Cloned Viral Protein Vaccine for Foot-and-Mouth Disease: Responses in Cattle and Swine
Authors: Kleid Dennis G. , Yansura Daniel , Small Barbara , Dowbenko Donald , Moore Douglas M. , Grubman Marvin J. , McKercher Peter D. , Morgan Donald O. , Robertson Betty H. , Bachrach Howard L.
Published: October 2006

A DNA sequence coding for the immunogenic capsid protein VP
3
of foot-and-mouth disease virus A
12
, prepared from the virion RNA, was ligated to a plasmid designed to express a chimeric protein from the
Escherichia coli
tryptophan promoter-operator system. When
Escherichia coli
transformed with this plasmid was grown in tryptophan-depleted media, approximately 17 percent of the total cellular protein was found to be an insoluble and stable chimeric protein. The purified chimeric protein competed equally on a molar basis with VP
3
for specific antibodies to foot-and-mouth disease virus. When inoculated into six cattle and two swine, this protein elicited high levels of neutralizing antibody and protection against challenge with foot-and-mouth disease virus.
Hyperglycemia of Diabetic Rats Decreased by a Glucagon Receptor Antagonist
Authors: Johnson David G. , Goebel Camy Ulichny , Hruby Victor J. , Bregman Marvin D. , Trivedi Dev
Published: October 2006

The glucagon analog [l-
N
α
-trinitrophenylhistidine, 12-homoarginine]-glucagon (THG) was examined for its ability to lower blood glucose concentrations in rats made diabetic with streptozotocin. In vitro, THG is a potent antagonist of glucagon activation of the hepatic adenylate cyclase assay system. Intravenous bolus injections of THG caused rapid decreases (20 to 35 percent) of short duration in blood glucose. Continuous infusion of low concentrations of the inhibitor led to larger sustained decreases in blood glucose (30 to 65 percent). These studies demonstrate that a glucagon receptor antagonist can substantially reduce blood glucose levels in diabetic animals without addition of exogenous insulin.
Long-Term Synaptic Potentiation in the Superior Cervical Ganglion
Authors: Brown Thomas H. , McAfee Donald A.
Published: October 2006

Brief tetanic stimulation of the preganglionic nerves to the superior cervical ganglion enhances the postganglionic response to single preganglionic stimuli for 1 to 3 hours. This long-term potentiation of transmission through the ganglion is apparently not attributable to a persistent muscarinic action of the preganglionic neurotransmitter, acetylcholine, since neither the magnitude nor the time course of the phenomenon is reduced by atropine. The decay of long-term potentiation can be described by a first-order kinetic process with a mean time constant of 80 minutes. We conclude that long-term potentiation, once considered a unique property of the hippocampus, is in fact a more general feature of synaptic function. This form of synaptic memory may significantly influence information processing and control in other regions of the nervous system, including autonomic ganglia.
Peptide and Steroid Regulation of Muscle Degeneration in an Insect
Authors: Schwartz Lawrence M. , Truman James W.
Published: October 2006

Two types of cell death occur in the intersegmental muscles of the giant silkmoth
Antheraea polyphemus
. The first results from a slow atrophy of the fibers, and the second is a rapid, programmed dissolution of the muscle. Both types appear to be mediated by endocrine factors. The slow atrophy is brought about by the decline in the steroid molting hormone 20-hydroxyecdysone and can be prevented with exogenous steroid. The rapid degeneration is triggered by the peptide eclosion hormone, but the sensitivity of the muscle to the peptide depends on the history of exposure of the muscle to 20-hydroxyecdysone.
A New Tumor-Promoting Agent, Dihydroteleocidin B, Markedly Enhances Chemically Induced Malignant Cell Transformation
Authors: Hirakawa Tadashi , Kakunaga Takeo , Fujiki Hirota , Sugimura Takashi
Published: October 2006

Teleocidin, which was isolated from mycelia of Streptomyces, is a potent tumor promoter in mouse skin. The catalytically hydrogenated compound dihydroteleocidin B markedly enhanced malignant cell transformation induced by 3-methylcholanthrene or ultraviolet radiation. Dihydroteleocidin B was at least 100 times more effective in enhancing transformation than 12-
O
-tetradecanoyl phorbol-13-acetate, the strongest promoter known until now, whereas both promoters showed equal capacities to induce early membrane effects and DNA synthesis.
Transcriptional Control Signals of a Eukaryotic Protein-Coding Gene
Authors: McKnight Steven L. , Kingsbury Robert
Published: October 2006

Transcriptional control signals of a model eukaryotic protein-coding gene have been identified by a new procedure of in vitro mutagenesis. This method allows small clusters of nucleotide residues to be substituted in a site-directed manner without causing the addition or deletion of other sequences. Transcription assays of a systematic series of these clustered point mutants have led to the identification of three distinct control signals located within the 105-nucleotide residues immediately upstream from the point where transcription begins.
Phosphorylation of Myosin Light Chains in Mouse Fast-Twitch Muscle Associated with Reduced Actomyosin Turnover Rate
Authors: Crow M. T. , Kushmerick M. J.
Published: October 2006

Phosphorylation of the 18,000-dalton light chains of the fast-twitch myosin in mouse extensor digitorum longus muscles was correlated with reduction in the rate of the actomyosin adenosinetriphosphatase in vivo, but neither of these changes occurred in the soleus muscle. These results suggest that actomyosin interactions can be down-regulated by a reversible covalent modification of myosin light chains, that a mechanism for thick-filament regulation occurs in vertebrate skeletal muscle, and that the expression of this regulation may be limited to a specific fiber type.
Inflammation and Collagenase Production in Rats with Adjuvant Arthritis Reduced with 13-
cis
-Retinoic Acid
Authors: Brinckerhoff Constance E. , Coffey John W. , Sullivan Ann C.
Published: October 2006

Oral administration of 13-
cis
-retinoic acid (40 or 160 milligrams per kilogram of body weight daily) significantly reduced the inflammation associated with developing and established adjuvant arthritis, an experimentally induced arthritis in rats that resembles human rheumatoid arthritis. The amount of collagenase secreted in tissue culture by adherent cells isolated from the inflamed joints of adjuvant rats treated with 13-
cis
-retinoic acid also decreased as compared to the amount secreted by cells from vehicle-treated adjuvant rats. Collagenase is important in the joint destruction accompanying rheumatoid arthritis. The successful use of retinoids in the treatment of this proliferative but nonmalignant disorder demonstrates a new application of these compounds.
Measurement of Suppressor Transfer RNA Activity
Authors: Young James F. , Capecchi Mario , Laski Frank A. , RajBhandary Uttam L. , Sharp Phillip A. , Palese Peter
Published: October 2006

Transfer RNA (tRNA) suppression of nonsense mutations in prokaryotic systems has been widely used to study the structure and function of different prokaryotic genes. Through genetic engineering techniques, it is now possible to introduce suppressor (Su
+
) tRNA molecules into mammalian cells. A quantitative assay of the suppressor tRNA activity in these mammalian cells is described; it is based on the amount of tRNA-mediated readthrough of a terminating codon in the influenza virus NS1 gene after the cells are infected with virus. Suppressor activity in L cells continuously expressing Su
+
(tRNA
tyr
) was 3.5 percent and that in CV-1 cells infected with an SV40- Su
+
(tRNA
tyr
) recombinant was 22.5 percent.
Rat Transforming Growth Factor Type 1: Structure and Relation to Epidermal Growth Factor
Authors: Marquardt Hans , Hunkapiller Michael W. , Hood Leroy E. , Todaro George J.
Published: October 2006

The complete amino acid sequence of rat transforming growth factor type 1 has been determined. This growth factor, obtained from retrovirus-transformed fibroblasts, is structurally and functionally related to mouse epidermal growth factor and human urogastrone. Production of this polypeptide by various neoplastic cells might contribute to the continued expression of the transformed phenotype.