bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Carcinogen Metabolism in the Rat Ovary by the Estrous Cycle and Gonadotropin
Authors: Bengtsson Margot , Rydstrom Jan
Published: October 2006

The activity of 7,12-dimethylbenz[
a
]anthracene hydroxylase in the rat ovary is several times higher in the proestrous phase of the estrous cycle than in the estrous and metestrous plus diestrous phases. Administration of gonadotropin leads to a similar increase in the capacity of the ovary to metabolize xenobiotics. This variation in the activity of 7,12-dimethylbenz[
a
]anthracene hydroxylase during the estrous cycle may be related to the marked changes in the incidence of ovarian cancer during menopause and in women taking contraceptive pills.
Biologically Active Chorionic Gonadotropin: Synthesis by the Human Fetus
Authors: McGregor W. G. , Kuhn R. W. , Jaffe R. B.
Published: October 2006

The kidney, and to a slight extent the liver, of human fetuses were found to synthesize and secrete the α subunit common to glycoprotein hormones. Fetal lung and muscle did not synthesize this protein. Since fetal kidney and liver were previously found to synthesize β chorionic gonadotropin, their ability to synthesize bioactive chorionic gonadotropin was also determined. The newly synthesized hormone bound to mouse Leydig cells and elicited a biological response: namely, the synthesis of testosterone. These results suggest that the human fetus may participate in metabolic homeostasis during its development.
Mapping of the Human
Blym
-1 Transforming Gene Activated in Burkitt Lymphomas to Chromosome 1
Authors: Morton Cynthia C. , Taub Rebecca , Diamond Alan , Lane Mary Ann , Cooper Geoffrey M. , Leder Philip
Published: October 2006

Blym
-1, a transforming gene detected by transfection of NIH 3T3 cells with DNA from Burkitt lymphomas, was mapped to the short arm of chromosome 1 (1p32) by chromosomal in situ hybridization. The
Blym
-1 gene was not physically linked to the cellular
myc
oncogene or to any of the immunoglobulin gene loci implicated in the characteristic chromosomal translocations in Burkitt lymphoma.
Prenatal Exposure to Carbon Monoxide: Learning and Memory Deficits
Authors: Mactutus Charles F. , Fechter Laurence D.
Published: October 2006

Exposing pregnant rats to carbon monoxide (150 parts per million) produced only minor reductions in the birth weights of the pups and gave no evidence of overt teratogenesis. However, behavioral evaluation of learning and memory processes in a two-way avoidance task suggested a functional deficit in the central nervous system of the exposed offspring. Multiple dependent measures and specific control groups confirmed that this deficit was independent of nonassociative or motivational alterations.
Magnesium Deficiency and Hypertension: Correlation Between Magnesium-Deficient Diets and Microcirculatory Changes in Situ
Authors: Altura Burton M. , Altura Bella T. , Gebrewold Asefa , Ising Hartmut , Gunther Theo
Published: October 2006

Rats maintained for 12 weeks on diets moderately or more severely deficient in magnesium showed significant elevations in arterial blood pressure compared to control animals. Examination of the mesenteric microcirculation in situ revealed that dietary magnesium deficiency resulted in reduced capillary, postcapillary, and venular blood flow concomitant with reduced terminal arteriolar, precapillary sphincter, and venular lumen sizes. The greater the degree of dietary magnesium deficiency the greater the reductions in microvascular lumen sizes. These findings may provide a rationale for the etiology, as well as treatment, of some forms of hypertensive vascular disease.
Ingestive Behavior Evoked by Hypothalamic Stimulation and Schedule-Induced Polydipsia Are Related
Authors: Mittleman Guy , Valenstein Elliot S.
Published: October 2006

Some, but not all, rats eat or drink in response to electrical stimulation of the lateral hypothalamus. Similarly, some, but not all, rats given food intermittently display schedule-induced polydipsia. In this experiment, animals that ate or drank during electrical stimulation tended also to be those displaying polydipsia. Thus, individual differences in predisposition to engage in ingestive behavior are consistent under two very different conditions.
α-Cardiac Actin Is the Major Sarcomeric Isoform Expressed in Embryonic Avian Skeletal Muscle
Authors: Paterson Bruce M. , Eldridge Juanita D.
Published: October 2006

A primer extension assay that is diagnostic for the messenger RNA's (mRNA's) transcribed from the β-cytoplasmic, α-cardiac, and α-skeletal actin genes of the chicken was used to measure the mRNA levels for these actin isoforms. Measurements were made in chicken breast muscle during myogenesis in vivo and in vitro. α-Cardiac actin mRNA accounts for more than 90 percent of the sarcomeric actin transcripts expressed in avian embryonic breast muscle. Five weeks after hatching, α-skeletal actin mRNA is the only detectable sarcomeric actin transcript.
Postnatal Modification of Hippocampal Circuitry Alters Avoidance Learning in Adult Rats
Authors: Lipp H.-P. , Schwegler H. , Driscoll P.
Published: October 2006

In rats and mice, the genetically mediated extent of the mossy fiber projection that synapses on the basal dendrites of hippocampal pyramidal cells is inversely correlated with rate of two-way avoidance (shuttle-box) learning. Postnatal hyperthyroidism, induced in 51 rat pups, resulted in marked variations of this infrapyramidal mossy fiber projection. The number of trials required for criterion performance of these rats in adulthood remained correlated with the neuroanatomical trait (r = 0.74, P < 0.0001).
Prolonged Weightlessness and Humoral Immunity
Authors: Voss Edward W.
Published: October 2006

Preflight, inflight, and postflight serum samples obtained from crewmen aboard STS-9 were analyzed for immunoglobulin content. Control studies for circadian rhythm were conducted to further validate the analyses. Quantitation of immunoglobulins G, M, A, D, and E indicated relatively minor fluctuations in the concentration of each class of immunoglobulin during the experiment. Thus, microgravity effects on immunoglobulin levels during a 10-day flight were considered insignificant.
Suppression of Ovulation in the Rat by an Orally Active Antagonist of Luteinizing Hormone-Releasing Hormone
Authors: Nekola M. V. , Horvath A. , Ge L.-J. , Coy D. H. , Schally A. V.
Published: October 2006

A synthetic antagonist of luteinizing hormone-releasing hormone blocked ovulation in rats in a dose-dependent manner when given by gavage on the afternoon of proestrus. Ovulation was delayed for at least 1 day in all animals given 2 milligrams of antagonist and in some of the animals treated with 1 or 0.5 milligram. Oral administration of 2 milligrams also blocked the preovulatory surge of luteinizing hormone. This demonstration that antagonists of luteinizing hormone-releasing hormone can have oral antiovulatory activity clearly enhances their therapeutic potential.
Lead Exposure During Infancy Permanently Increases Lithium-Induced Polydipsia
Authors: Mailman Richard B. , Krigman Martin R. , Mueller Robert A. , Mushak Paul , Breese George R.
Published: October 2006

Lead (200 milligrams per kilogram) was administered daily by intubation to Long-Evans rats on days 3 through 30 of life. Thirty to 180 days after cessation of lead administration, the lead-treated rats were consistently more polydipsic after lithium administration (2 millimoles per kilogram per day) than were pair-treated controls. Lithium increased the plasma renin activity equally in both the lead-treated and the control groups. These data are evidence that there may be permanent neural changes induced by postnatal exposure to lead that are manifested by pharmacological challenge with lithium.
DNA Sequences Mediating Class Switching in α-Immunoglobulins
Authors: Davis Mark M. , Kim Stuart K. , Hood Leroy E.
Published: October 2006

Immunoglobulin class switching involves specific DNA rearrangements of the gene segments coding for heavy chain constant regions (C
H
) during B lymphocyte differentiation. In two different cases of C
μ
to C
α
switching examined here (T15 and M603) and one taken from the literature (MC101), three different sites on the 5′ side of C
μ
and three different sites on the 5′ side of C
α
are joined together in the process of C
H
switching. The sequences surrounding the three germ-line C
α
sites of recombination are highly conserved blocks of 30 nucleotides that may serve as recognition sequences for C
H
switching to the C
α
gene. This putative recognition sequence is repeated 17 times in approximately 1400 nucleotides of the germ-line C
α
5′ flanking sequence. The lack of homology between this C
α
sequence and sequences reported for the C
γ1
and C
γ2b
switch sites suggests that heavy chain switching is mediated by class-specific recognition sequences and, presumably, class-specific regulatory mechanisms. In addition, it appears that in one example (MC101) C
H
switching progressed from C
μ
to C
α
to C
γ1
. This switching pathway may present difficulties for the simple deletional model of C
H
switching.
Site-Specific X-Chromosome Rearrangements from Hybrid Dysgenesis in
Drosophila melanogaster
Authors: Berg Raissa , Engels William R. , Kreber Robert A.
Published: October 2006

When the germ line of
Drosophila
males is destabilized by a syndrome known as hybrid dysgenesis, X-chromosome rearrangements are found in up to 10 percent of the gametes produced. Some of these aberrations are simple inversions, but many are complex multibreak rearrangements. Furthermore, most of the breakpoints fall into a few highly localized positions on the chromosome. These positions are mostly at points of intercalary heterochromatin and may vary from one strain to the next. The results suggest that they may represent points of insertion of mobile DNA sequences.
Somatic Cell Hybrids from Frog Lymphocytes and Mouse Myeloma Cells
Authors: Hengartner H. , Du Pasquier L.
Published: October 2006

Stable somatic cell hybrids were obtained by fusing
Xenopus
lymphocytes with mouse myeloma cells. These hybrids contained one to four
Xenopus
chromosomes and expressed
Xenopus
gene products, one of which was a lymphocyte membrane protein of 85,000 daltons precipitated by a monoclonal antibody.
DNA Sequence of the Gene Encoding the E
α
Ia Polypeptide of the BALB/c Mouse
Authors: McNicholas Janet , Steinmetz Michael , Hunkapiller Tim , Jones Patricia , Hood Leroy
Published: October 2006

A 3.4-kilobase DNA fragment containing the gene coding for the E
α
chain of an Ia (I region-associated) antigen from the BALB/c mouse has been sequenced. It contains at least three exons, which correlate with the major structural domains of the E
α
chain—the two external domains α1 and α2, and the transmembrane-cytoplasmic domain. The coding sequence of the mouse E
α
gene shows striking homology to its human counterpart at the DNA and protein levels. The translated α2 exon demonstrates significant similarity to β
2
-microglobulin, to immunoglobulin constant region domains, and to certain domains of transplantation antigens. These observations and those of others suggest that the Ia antigen, transplantation antigen, and immunoglobulin gene families share a common ancestor.
Collagen Formation by the Hepatocyte in Primary Monolayer Culture and in Vivo
Authors: Diegelmann Robert F. , Guzelian Philip S. , Gay Renate , Gay Steffen
Published: October 2006

Immunohistochemical techniques were used to confirm biochemical evidence that parenchymal cells isolated from adult rat liver and maintained in nonreplicating monolayer culture for 2 days synthesized type IV basement membrane collagen. On continued incubation in serum-free medium, the hepatocytes also synthesized the interstitial collagens, types I and III. Consistent with these results in culture, type IV collagen was localized to the hepatocytes in slices of pathologic rat liver. Hence collagen formation is a previously unrecognized function of the hepatocyte that may be important in the pathogenesis of liver fibrosis or cirrhosis.
Radiation Exposures in Utah from Nevada Nuclear Tests
Authors: Beck Harold L. , Krey Philip W.
Published: October 2006

The exposure of the population of Utah to external gamma-radiation from the fallout from nuclear weapons tests carried out between 1951 and 1958 at the Nevada Test Site has been reconstructed from recent measurements of residual cesium-137 and plutonium in soil. Although the highest exposures were found in the extreme southwest part of Utah, as expected, the residents of the populous northern valleys around Provo, Salt Lake City, and Ogden received a higher mean dose and a significantly greater population dose (person-rads) than did the residents of most counties closer to the test site. However, population doses from external exposure throughout Utah were far too low to result in any statistically observable health effects.
Primary Murine Bone Marrow Cultures Support Continuous Growth of Infectious Human Trypanosomes
Authors: Balber Andrew E.
Published: October 2006

The human parasite
Trypanosoma brucei gambiense
grew continuously at 37°C in primary cultures of murine bone marrow. Cultured parasites remained virulent for mice. Rapid parasite growth coincided with the appearance of adherent adipocyte-epitheloid cell aggregates that also promoted hematopoiesis. This culture system should permit studies of host cell control of trypanosome proliferation, pathogenic effects of trypanosomes on blood cell development, and the relative trypanocidal and marrow suppressive activities of drugs.
Pregnancy Increases Reactivity of Mice to Phenobarbital
Authors: Middaugh Lawrence D. , Zemp John W. , Boggan William O.
Published: October 2006

Compared to nonpregnant controls, pregnant mice injected with phenobarbital had lower concentrations of the drug in the plasma but equivalent concentrations in the brain. In spite of the similar concentrations in the brain, the behavioral response to phenobarbital was greater for pregnant than nonpregnant mice. These results suggest that the concentration of phenobarbital in the plasma, which is commonly used as a basis for adjusting phenobarbital dosage during pregnancy, is not an appropriate indicator of the dynamics of the drug.
Time-Resolved Resonance Raman Spectroscopy of Hemoglobin Derivatives: Heme Structure Changes in 7 Nanoseconds
Authors: Woodruff William H. , Farquharson Stuart
Published: October 2006

Resonance Raman spectra of oxyhemoglobin, deoxyhemoglobin, carboxyhemoglobin, and the corresponding myoglobin derivatives have been obtained with 7-nanosecond laser pulses at 531.8 nanometers. The results suggest that no transient constraint of the heme group by the globin structure occurs on this time scale, and thus establish a temporal sequence for the early events that may participate in the stereochemical trigger mechanism of hemoglobin cooperativity.
Infantile Stimulation Induces Brain Lateralization in Rats
Authors: Denenberg Victor H. , Garbanati James , Sherman Gordon , Yutzey David A. , Kaplan Richard
Published: October 2006

The hypothesis tested was that the effects of early experiences are asymmetrically distributed in the two brain hemispheres. Litters were either handled or not handled between birth and weaning, and the weanlings were reared in either laboratory cages or enriched environments between 21 and 50 days. When approximately 135 days old, animals within each of the four treatment groups had a right neocortical ablation, a left neocortical ablation, a sham operation, or no surgery. About 1 month later, all animals were given the open-field test for emotionality and exploratory behavior. Ablating either the right or left neocortex increased the activity scores of nonhandled controls, but there was no evidence of lateralization. However, the groups handled in infancy did show lateralization. Ablating the left brain did not significantly increase activity, but ablating the right brain caused extreme scores: handled rats without enrichment experience were the most active, and handled rats also placed into the enriched environment had near-zero scores in the open field.
Cytotoxicity of a Perfluorocarbon Blood Substitute to Macrophages in Vitro
Authors: Bucala Richard , Kawakami Masanobu , Cerami Anthony
Published: October 2006

Murine macrophage and macrophage-depleted splenocyte cultures were incubated under ambient oxygen with a commercially available perfluorocarbon blood substitute. The perfluorocarbon preparation was found to be selectively cytotoxic to macrophages. This finding may be significant in view of the preliminary therapeutic usage of these preparations. In addition, perfluorocarbons may be useful as a means of selectively removing macrophages from tissue and organ cultures.
Myasthenic Globulin Enhances the Loss of Acetylcholine Receptor Clusters
Authors: Bursztajn Sherry , McManaman James L. , Elias Stanton B. , Appel Stanley H.
Published: October 2006

Acetylcholine receptors are present in the sarcolemma of cultured skeletal muscle myotubes either as large clusters or in a diffuse distribution. Both the clustered and diffuse acetylcholine receptors are potentially removable from the membrane. Treatment of myotubes with globulin from patients with myasthenia gravis causes the loss of acetylcholine receptor clusters and the concomitant appearance of acetylcholine receptor microaggregates. The rate of acetylcholine receptor cluster loss is greater than the rate of acetylcholine receptor degradation, indicating that acetylcholine receptors are disrupted from clusters to form microaggregates before being removed from the plasma membrane.
Diphenylhydantoin: An Alternative Ligand of a Glucocorticoid Receptor Affecting Prostaglandin Generation in A/J Mice
Authors: Katsumata Masuyuki , Gupta Chhanda , Baker Mary K. , Sussdorf Claudia E. , Goldman Allen S.
Published: October 2006

Evidence for the binding of 5,5-diphenylhydantoin and glucocorticoids to a common receptor is presented for pulmonary and hepatic cytosols and thymocytes of A/J female mice. The 5,5-diphenylhydantoin-protein complex is adsorbed by DNA cellulose, and is incorporated into nuclei, 5,5-Diphenylhydantoin, like glucocorticoids, inhibits the production of prostaglandins in thymocytes. Thus a common receptor is probably responsible for the inhibitory and teratogenic effects of these drugs.
Hemoglobin Switching: A Cellular Model
Authors: Alter Blanche P. , Goff Sabra C.
Published: October 2006

Regulation of hemoglobin synthesis depends in part on the population of cells available for erythroid differentiation. Mouse erythroleukemia cells were cloned, and the clones were induced with dimethyl sulfoxide to test the relative induction of β minor and β major synthesis. Cells of line 745 produced approximately 35 percent β minor after induction, and 39 clones of line 745 produced from 23 to 61 percent β minor. Further subcloning of the clone that produced 61 percent β minor led to three subclones, all of which produced more than 90 percent β minor. Thus one kind of hemoglobin regulation occurs at the cellular level.
Prevention of Death from Metastases by Immune RNA Therapy
Authors: Wang Bosco Shang , Onikul Suzanne R. , Mannick John A.
Published: October 2006

The effect of immune RNA treatment on the incidence of death from pulmonary metastases was studied in C57BL/6J mice after excision of a B16 murine melanoma. Immune RNA was extracted from the lymphoid tissues of guinea pigs immunized with B16 tumor and then incubated in vitro with normal C57BL/6J mouse splenocytes. Mice receiving intraperitoneal injections of these RNA-treated syngeneic splenocytes after the primary B16 isograft was resectioned showed significantly improved long-term survival (42 to 67 percent in three successive experiments) as compared to control mice (0 to 20 percent survival) receiving untreated splenocytes. The effect of RNA treatment was tumor-specific and ribonuclease sensitive. The results suggest that immunotherapy with immune RNA may be of benefit to certain patients after surgery for cancer.
Histocompatibility and Isoenzyme Differences in Commercially Supplied "BALB/c" Mice
Authors: Kahan Brenda , Auerbach Robert , Alter Barbara J. , Bach Fritz H.
Published: October 2006

BALB/c mice obtained commercially were found to differ significantly from the standard phenotype of BALB/c strain mice. Isoenzyme tests and H-2 haplotype analyses indicated that the majority of mice from two of the three sources tested appeared mixed, frequently heterozygous, and did not consistently express either the expected H-2 or glucose phosphate isomerase type.
Psychophysical Evidence for More Than Two Kinds of Cone in Dichromatic Color Blindness
Authors: Frome Francine S. , Piantanida Thomas P. , Kelley D. H.
Published: October 2006

Psychophysical evidence shows that at least some classically diagnosed dichromats have three cone types rather than two. The anomalous cones, previously thought to be absent, are less sensitive than normal cones to both spectral and temporal variations, and have spectral sensitivities like those of the abnormal cones of anomalous trichromats. These results are not consistent with either loss or replacement models of X-linked recessive color-vision defects, since some dichromats apparently have the same three photopigments as anomalous trichromats.
Mutagenicity of a New Hair Dye Ingredient: 4-Ethoxy-
m
-phenylenediamine
Authors: Prival Michael J. , Mitchell Valerie D. , Gomez Yolanda P.
Published: October 2006

An ingredient recently introduced in hair dyes, 4-ethoxy-
m
-phenylenediamine, is mutagenic in histidine-requiring strains of
Salmonella typhimurium
. Its mutagenic activity is similar to that of the hair dye ingredient it apparently replaced, 4-methoxy-
m
-phenylenediamine.
Directed Deletion of a Yeast Transfer RNA Intervening Sequence
Authors: Wallace R. Bruce , Johnson Peter F. , Tanaka Shoji , Schöld Monica , Itakura Keiichi , Abelson John
Published: October 2006

Many eukaryotic genes contain intervening sequences, segments of DNA that interrupt the continuity of the gene. They are removed from RNA transcripts of the gene by a process known as splicing. The intervening sequence in a yeast tyrosine transfer RNA (tRNA
Tyr
) suppressor gene was deleted in order to test its role in the expression of the gene. The altered gene and its parent were introduced into yeast by transformation. Both genes exhibited suppressor function, showing that the intervening sequence is not absolutely essential for the expression of this gene.
Hormone Binding Alters the Conformation of the Insulin Receptor
Authors: Pilch Paul F. , Czech Michael P.
Published: October 2006

Fat cells or fat cell membranes were briefly subjected to mild proteolysis under conditions where insulin receptors were either free or bound to
125
I-labeled insulin. When receptors were then affinity-labeled to visualize the effects of this treatment, it was observed that receptors that had been occupied by ligand during proteolysis exhibited greater rates of degradation than unoccupied receptors. These results demonstrate that insulin-receptor interaction induces a change in receptor structure that may be related to signal transmission.
HLA Variants of Cultured Human Lymphoid Cells: Evidence for Mutational Origin and Estimation of Mutation Rate
Authors: Pious Donald , Soderland Carl
Published: October 2006

Variants of a diploid lymphoid cell line that show a loss of HLA-B27 antigen occur randomly in time and independently of exposure to the alloantiserum used for their isolation. From these and previous findings of variant stability, inducibility by mutagens, and the absence of linked variation, we conclude that most HLA variants arise by mutation. The mutation rate for HLA-B27 loss is 8 × 10
-7
per cell per generation.
Nalidixic Acid, Oxolinic Acid, and Novobiocin Inhibit Yeast Glycyl- and Leucyl-Transfer RNA Synthetases
Authors: Wright H. T. , Nurse K. C. , Goldstein D. J.
Published: October 2006

Nalidixic acid and novobiocin inhibit the aminoacylation and pyrophosphate exchange activities of glycyl- and leucyl-transfer RNA synthetases from bakers' yeast. Similar types of inhibition are observed for both enzymes, suggesting similar mechanisms. The potency of these inhibitors is comparable to that observed for their inhibition of in vivo DNA synthesis in eukaryotic cells.
Scienceand James McKeen Cattell, 1894 to 1945
Authors: Sokal Michael M.
Published: October 2006

Cattell took control ofSciencein 1894, turned it into America's most important scientific journal, and edited it for 50 years.
Liposomes as Gene Carriers: Efficient Transformation of Mouse L Cells by Thymidine Kinase Gene
Authors: Schaefer-Ridder Maria , Wang Yuan , Hofschneider Peter Hans
Published: October 2006

Stable transformation of mouse L cells deficient in thymidine kinase was achieved by liposome-mediated transfer of a recombinant plasmid carrying the thymidine kinase gene. Ten percent of the recipient cells expressed thymidine kinase activity. The transformed phenotype (for example, 200 out of 10
6
cells) was stable under selective and nonselective conditions. The liposome technique is compared with other methods currently used for gene transfer.
Onset and Offset of Brain Events as Indices of Mental Chronometry
Authors: Renault Bernard , Ragot Richard , Lesevre Nicole , Remond Antoine
Published: October 2006

Analysis of single-trial electroencephalogram waveforms in a reaction time task demonstrated that the onset and offset values of event-related potentials can be used as indices of the duration of information processing. Two negative waves have been identified which peak at different times in different regions of the scalp, with the second overlapping the last part of the first. These waves are related in different ways to the duration of perceptual processing.
Cultivation of Bacteria-Free
Hydra viridis
: Missing Budding Factor in Nonsymbiotic Hydra
Authors: Rahat M. , Dimentman Ch.
Published: October 2006

Bacteria-free hydra, cultured in sterile media, were fed bacteria-free larvae of
Artemia salina
. Normal growth and budding were obtained in symbiotic and aposymbiotic
Hydra viridis
. Two nonsymbiotic hydra species did not form buds under bacteria-free conditions. When these hydra were fed nonsterile Artemia, or if the medium was reinoculated with bacteria isolated from budding stock cultures, normal budding was resumed. An exogenous budding factor, which can be provided by nonsterile
Artemia
larvae, or even by some bacteria, appears to be required by these nonsymbiotic hydra. This factor is endogenous in
Hydra viridis
.
Serotonin Analog Selectively Ablates Indentified Neurons in the Leech Embryo
Authors: Glover Joel C. , Kramer Andrew P.
Published: October 2006

Exposure of embryonic leeches to 5,7-dihydroxytryptamine, a cytotoxic analog of the monoamine neurotransmitter serotonin, results in the selective ablation of serotonin-containing neurons in the ventral nerve cord. Other neurons appear to be unaffected by this treatment, including those that contain another monoamine neurotransmitter, dopamine. Embryos with ablations continue to develop into juvenile leeches, but as juveniles they are unable to make normal swimming movements. However, normal swimming movements can be instated in such leeches by injecting them with serotonin.
Cholinergic Agonists Induce Vectorial Release of Serotonin from Duodenal Enterochromaffin Cells
Authors: Forsberg Erik J. , Miller Richard J.
Published: October 2006

Serotonin-containing enterochromaffin cells in the rabbit duodenal mucosa span the tissue contacting both the luminal and serosal sides. When the serosal surface is stimulated with carbachol in vitro, serotonin is secreted on the serosal side but not the mucosal side. Carbachol added to the luminal side is ineffective. Atropine but not hexamethonium blocks the effect of carbachol. Acetylcholine on the serosal surface also stimulates serotonin release on the serosal side. These findings indicate that enterochromaffin cells possess on their serosal surfaces muscarinic receptors that mediate vectorial release of serotonin when activated by cholinergic agonists.
Genetic Length of a Human Chromosomal Segment Measured by Recombination Between Two Fragile Sites
Authors: Sutherland Grant R. , Baker Elizabeth , Mulley John C.
Published: October 2006

Two families were studied in which the same homolog of chromosome pair 10 expressed both the fragile sites on the long (q) arm at 10q23 and 10q25. Recombination between the fragile sites was observed in 3 of the 27 offspring in whom it could occur. The genetic length of chromosome between the fragile sites was 11 female centimorgans within a 95 percent probability interval of 4 to 28 centimorgans. This estimate of genetic length is comparable to those obtained with other methods.
Hypotensive Effect of Fasting: Possible Involvement of the Sympathetic Nervous System and Endogenous Opiates
Authors: Einhorn Daniel , Young James B. , Landberg Lewis
Published: October 2006

Fasting lowers blood pressure to a greater extent in spontaneously hypertensive rats than in normotensive rats. While fasting reduced cardiac sympathetic activity to an equivalent extent in both groups of animals, only in the hypertensive rats did fasting elicit an opiate-mediated vasodepressor response that was independent of sympathetic withdrawal. Both sympathetic nervous system suppression and endogenous opiate activation, therefore, may contribute to the hypotensive effect of fasting in the spontaneously hypertensive rat.
Release of γ-Aminobutyric Acid from Cat Colon
Authors: Taniyama Kohtaro , Kusunoki Masato , Saito Naoaki , Tanaka Chikako
Published: October 2006

The release of γ-aminobutyric acid was confirmed in isolated cat colon loaded with tritiated γ-aminobutyric acid. Thirty to 180 minutes after loading the spontaneous efflux of tritium appeared to fit a single exponential curve with an efflux rate coefficient of 0.002 per minute. Electrical stimulation produced frequency-dependent increases in the tritium efflux and in the contractions. Even 120 minutes later over 91 percent of the total radioactivity in the superfusates was attributable to tritiated γ-aminobutyric acid. The acid release and the contractions induced by electrical transmural stimulation were inhibited by tetrodotoxin and by a calcium-free medium. Release of the acid was not significant during contractions elicited by nicotine and acetylcholine. These findings indicate that γ-aminobutyric acid is released from the terminals of neurons in the myenteric plexus of the colon.
Bleb Formation in Hepatocytes During Drug Metabolism Is Caused by Disturbances in Thiol and Calcium Ion Homeostasis
Authors: Jewell Sarah A. , Bellomo Giorgio , Thor Hjördis , Orrenius Sten , Smith Martyn T.
Published: October 2006

A wide variety of toxic chemicals cause blebbing of the plasma membrane in isolated hepatocytes. These alterations in surface structure occur well before cell death. The formation of blebs appears to be directly related to changes in the concentration of extramitochondrial calcium ions. These changes probably reduce the ability of the hepatocyte cytoskeleton to maintain normal surface morphology. The concentration of soluble thiols, notably glutathione, appears to regulate the size of the extramitochondrial calcium ion pool. Disturbances in intracellular thiol and calcium ion homeostasis therefore seem to be responsible for the surface blebbing observed during toxic injury to isolated hepatocytes.
Direct Measurement of Pulmonary Capillary Transit Times
Authors: Wagner Wiltz W. , Latham Leonard P. , Gillespie Mark N. , Guenther John P. , Capen Ronald L.
Published: October 2006

Direct measurements of capillary transit times in dog lungs were made by using in vivo television microscopy. Mean transit times were unexpectedly long. As pulmonary artery pressures were raised, transit times decreased, suggesting that the normally existing hydrostatic pressure gradient in the lung causes a vertical distribution of transit times. The more rapid transit times approached the minimum time required for complete oxygenation.
Medical Technology and Cost Containment: Two Applications of Operations Research
Authors: Ledley R. S. , Thiagarajan T. R. , Landau T. P.
Published: October 2006

The government proposes "common sense" regulations to help contain rising health costs due to the increasing use of high-technology procedures, such as computerized tomography scanning. Two illustrations are given showing that such ad hoc regulations may have the effect of increasing costs and are certainly far from the optimum obtained by known methods of operations research.
Long Ascending Projections from Substantia Gelatinosa Rolandi and the Subjacent Dorsal Horn in the Rat
Authors: Giesler Glenn J. , Cannon J. Timothy , Urca Gideon , Liebeskind John C.
Published: October 2006

Small neurons of the substantia gelatinosa Rolandi and the subjacent dorsal horn of the spinal cord have been thought to exert a direct modulatory effect only on neurons located within a distance of a few spinal segments. By using the technique of retrograde transport of horseradish peroxidase, however, it has been found that in the rat a significant number of these cells, particularly those of the subjacent dorsal horn, ascend many spinal segments to the lateral cervical nucleus and to the lower brainstem. These data provide an anatomic basis for a role of substantia gelatinosa Rolandi and subjacent dorsal horn cells in modulating or contributing to sensory information transmission not only in nearby segments but in far distant structures.
Alcoholic Rhabdomyolysis: An Experimental Model in the Rat
Authors: Haller Ronald G. , Drachman Daniel B.
Published: October 2006

The main features of alcoholic rhabdomyolysis-skeletal muscle necrosis, marked elevation of serum creatine phosphokinase, and myoglobinuria-were produced in rats by a combination of relatively prolonged (2 to 4 weeks) exposure to ethanol and a brief period of food deprivation. This observation suggests that fasting may similarly trigger muscle injury during binge drinking in man. The effect of fasting is in part related to an increase in blood alcohol due to reduced alcohol clearance and in part caused by a fasting-induced potentiation of the toxic effects of high concentrations of alcohol of skeletal muscle.
Meprobamate Reduces Accuracy of Physiological Detection of Deception
Authors: Waid William M. , Orne Emily Carota , Cook Mary R. , Orne Martin T.
Published: October 2006

Normal male subjects attempted to deceive an experimenter recording electrodermal, respiratory, and cardiovascular activity. Those who had ingested a placebo or nothing were detected with statistically significant frequency on the basis of their phasic electrodermal responses, which clearly distinguished them from truthful suspects. That was not the case with deceptive subjects who had ingested 400 milligrams of meprobamate, nor did the examiner detect which subjects had received the drug.
Pregnancies in Humans by Fertilization in Vitro and Embryo Transfer in the Controlled Ovulatory Cycle
Authors: Trounson A. O. , Leeton J. F. , Wood C. , Webb J. , Wood J.
Published: October 2006

Normal pregnancies have been established in four women with tubal infertility by fertilization in vitro, embryo culture, and embryo transfer after stimulation of follicular growth with clomiphene citrate. In three of these women the time of oocyte maturation was controlled by human chorionic gonadotropin. This procedure for the control of ovulatory response has many advantages when compared with the previously successful method of using the natural ovulatory cycle.
Myelinated Central Vertebrate Axon Lacks Voltage-Sensitive Potassium Conductance
Authors: Kaars Charles , Faber Donald S.
Published: October 2006

Intracellular recordings were obtained from the goldfish Mauthner cell soma and axon before and after intracellular iontophoresis of drugs that block voltage-sensitive potassium conductance. Analysis of the action potentials generated by the axon hillock-initial segment and by the axon suggest that axonal impulses lack this potassium conductance. Thus, impulse repolarization in the Mauthner axon, and perhaps in other vertebrate central axons, may not involve an active potassium current.
Early Removal of One Eye Reduces Normally Occurring Cell Death in the Remaining Eye
Authors: Sengelaub Dale R. , Finlay Barbara L.
Published: October 2006

During normal development of the hamster eye, there is a substantial loss of cells from the retinal ganglion cell layer in the first two postnatal weeks. If one eye is lost at birth, this cell death is reduced in the remaining eye. This may account for the increased ipsilateral projection from this eye to the thalamus and midbrain observed in these animals.
Short-Term Variations in Diet Composition Change the Pattern of Spontaneous Motor Activity in Rats
Authors: Chiel Hillel J. , Wurtman Richard J.
Published: October 2006

The nocturnal activity patterns of rats changed significantly within 3 days after they were given unrestricted access to isocaloric diets in which the ratio of carbohydrate to protein was systematically varied. As the ratio increased, the rats were more continuously active. The subjects showed similar responses to variations in this ratio whether the diet contained 15 or 45 percent fat. No correlation was found between the number of calories an animal ate and its activity pattern.
Behavioral Effects of Lead and
Toxocara canis
in Mice
Authors: Dolinsky Z.S. , Burright R.G. , Donovick P.J. , Glickman L.T. , Babish J. , Summers B. , Cypess R.H.
Published: October 2006

Adult mice were administered the common parasite
Toxocara canis
or lead or both. The parasite clearly altered mouse performance on tests of exploration, activity, learning, and motor coordination; behavioral effects in mice receiving lead alone were less general. Consequences of
Toxocara
administration appeared attenuated in animals receiving both agents. Parasite larvae were found in the central nervous system in all infected mice.
Progesterone Regulation of the Occupied Form of Nuclear Estrogen Receptor
Authors: Okulicz William C. , Evans Rawden W. , Leavitt Wendell W.
Published: October 2006

Total concentrations of estrogen receptor in the uterine nuclear fraction are reduced rapidly after progesterone treatment of the proestrous hamster. Progesterone acts selectively on the occupied form of the nuclear estrogen receptor, with no effect on the concentration of an unoccupied form. This observation indicates that progesterone modulates the action of estrogen by controlling nuclear retention of the estrogen-receptor complex.
Cerebral Cortex Responds Rapidly to Thyroid Hormones
Authors: Leonard Jack L. , Kaplan Michael M. , Visser Theo J. , Silva J. Enrique , Larsen P. Reed
Published: October 2006

In rats subjected to thyroidectomy there was a two- to fourfold increase in cerebral cortex iodothyronine 5′-deiodinase activity within 24 hours. This increase was prevented by thyroxine replacement. The increased cortical 5′-deiodinase in chronically hypothyroid rats was normalized within 4 hours by a single intravenous injection of triiodothyronine. These results indicate that the adult central nervous system can give a very rapid biochemical response to thyroid hormone.
Placental β-Endorphin-Like Peptides
Authors: Houck J. C. , Kimball C. , Chang C. , Pedigo N. W. , Yamamura H. I.
Published: October 2006

Acid extracts of human placental tissue contain, by both radioimmunoassay and radioreceptor assay, β-endrophin-like material. Half of this material will not go through a 5000-dalton filter and on Sephadex G-200 has a molecular size between 25,000 and 50,000 daltons. Of the material going through a 5000-dalton ultrafilter, 80 percent is excluded on Sephadex G-25 and held back, very slightly, on Bio-Rad P6, indicating a molecular size of approximately 4500 to 4800 daltons. Thus, placenta appears to have macromolecular precursors from which a β-endorphin-like material is released, with a size approximately 12 amino acids longer than that of the pituitary hormone.
Auditory and Vocal Nuclei in the Frog Brain Concentrate Sex Hormones
Authors: Kelley Darcy B.
Published: October 2006

Mate calling by South African clawed frogs,
Xenopus laevis
, is under the control of androgens. Autoradiographic studies demonstrate androgen-concentrating neurons in a motor nucleus that controls mate calling and a midbrain nucleus that is stimulated by sound. Hormone concentration by laryngeal motor neurons suggests that steroids regulate the final common path for vocal behavior. Modulation of auditory sensitivity by hormones could explain seasonal variations in behavioral responsiveness to conspecific vocalizations.
Rat Model for Carcinogenesis in Ureterosigmoidostomy
Authors: Crissey Michael M. , Steele Glenn D. , Gittes Ruben F.
Published: October 2006

A rat model is used to study the carcinogenesis that occurs when urine is surgically diverted into the fecal stream, as in ureterosigmoidostomy. Adenocarcinoma of the colon occurs adjacent to the urine inlet. It is completely prevented by proximal diversion of the feces, implying that fecal carcinogens are activated locally by the urine or the urothelium.
Survival of Mice Receiving Melanoma Transplants Is Promoted by Hydroquinone
Authors: Chavin Walter , Jelonek Edward J. , Reed Allen H. , Binder Laurence R.
Published: October 2006

In BALB/c female mice with melanoma transplants, the incidence of "takes" is decreased and survival is increased by hydroquinone, a melanocytolytic agent. The mechanism of drug action is suggested to be via DNA. The significant and high degree of positive response to hydroquinone treatment in vivo is encouraging for the clinical management of melanoma with melanocytolytic agents.
Ethanol Specifically Potentiates GABA-Mediated Neurotransmission in Feline Cerebral Cortex
Authors: Nestoros J. N.
Published: October 2006

Ethanol (ethyl alcohol) potentiates the inhibition of cortical neurons by γ-aminobutyric acid. This effect is specific, since ethanol does not potentiate inhibition by glycine, serotonin, or dopamine. These results have implications for alcoholism because (i) γ-aminobutyric acid mediates anxiolytic mechanisms, and (ii) anxiety is implicated in the etiology of alcoholism.
Electromyograms Are Repeatable: Precautions and Limitations
Authors: Gans Carl , Gorniak Gerard C.
Published: October 2006

Electromyograms recorded by bipolar, fine wire electrodes placed into anatomically equivalent sites in skeletal muscles of vertebrates are repeatable when the animals use the muscles in a similar way. Repeatability applies to the number of spikes recorded from a given site and to their average amplitude as well as to the root-mean-square value, though the values obtained for these descriptors differ among muscles, and perhaps fascicles, of particular animals even when the animals are performing equivalent actions. Tests suggest that these results are not affected by the nature of most kinds of recording equipment. Also, substantial differences in electrode tip configuration and wire diameter induce relatively minor, less than 8 percent, differences in electrode resistance and impedance. Doubling the length of the fine wire leads produces less than an 8 percent (15 percent when the length is tripled) effect; however, the effect of electrode material may be as much as 85 percent in resistance and 20 percent in impedance. Reports of nonreproducibility or variability of electromyograms apparently result mainly from anatomically inexact placement into physiologically and histochemically different fascicles of compound muscles, from recordings of muscles that are active at very low levels, and perhaps from comparison among recordings of muscles that really differ in their activity level.
Stimulation of DNA and Collagen Synthesis by Autologous Growth Factor in Cultured Fetal Rat Calvaria
Authors: Canalis Ernesto , Peck William A. , Raisz Lawrence G.
Published: October 2006

Conditioned medium derived from organ or cell cultures prepared from 19- to 21-day fetal rat calvaria stimulated the incorporation of [
3
H]proline into collagen and of [
3
H]thymidine into DNA in organ cultures of the same tissue. Addition of cortisol enhanced the effect on collagen but not on DNA synthesis. These effects appeared to be due to a nondialyzable and heat-stable growth factor.
Protein Antigens from
Staphylococcus aureus
Strains Associated with Toxic-Shock Syndrome
Authors: Cohen Mitchell L. , Falkow Stanley
Published: October 2006

Staphylococcus aureus
isolates from patients with toxic-shock syndrome have two antigenic proteins that distinguish these strains from isolates obtained from patients who do not have this syndrome and who are colonized or infected with
S. aureus
. These proteins may either represent antigenic markers, the toxin (or toxins), or toxic subunits that cause the clinical manifestations of this disease.
Extracellular Access to the Na,K Pump: Pathway Similar to Ion Channel
Authors: Gadsby David C. , Rakowski R. F. , De Weer Paul
Published: October 2006

In each normal Na,K pump cycle, first three sodium and then two potassium ions are transported; in both cases, the ions become temporarily occluded in pump conformations that isolate them from internal and external solutions. A major charge movement occurs during sodium translocation and accompanies the deocclusion of sodium ions or their release to the cell exterior, or both. The nature of the charge movement was examined by measurement of the unidirectional sodium-22 efflux mediated by Na
i
-Na
o
exchange (Na
i
and Na
o
are internal and external sodium ions) in voltage-clamped, internally dialyzed squid giant axons in the absence of potassium; in this way the pump activity was restricted to the sodium-translocation pathway. Although electroneutral, the Na
i
-Na
o
exchange was nevertheless voltage-sensitive: increasingly negative potentials enhanced its rate along a saturating sigmoid curve. Such voltage dependence demonstrates that the release and rebinding of external sodium is the predominant charge-moving (hence, voltage-sensitive) step, suggesting that extracellular sodium ions must reach their binding sites deep in the pump molecule through a high-field access channel. This implies that part of the pump molecule is functionally analogous to an ion channel.
Metal Ions in Enzymes Using Ammonia or Amides
Authors: Dixon Nicholas E. , Gazzola Carlo , Blakeley Robert L. , Zerner Burt
Published: October 2006

In an attempt to understand the role of nickel in jack bean urease (1), we turned to a variety of other enzymes important in the utilization, production, or transfer of ammonia. We found several, including the L-histidine and L-phenylalanine ammonialyases and some enzymes that utilize glutamine or ammonia in amidotransferase reactions, all of which show evidence for the involvement of as yet unreported transition metal ions in their mechanism of action.

We support the view that catalysis by metalloenzymes may be a reflection of the chemistry of the metal ion itself as a Lewis acid, and that perhaps too much emphasis has been placed on supposed special characteristics (such as strain, "entasis") of the enzyme-metal ion association. In this context, we have discussed the mechanism of catalysis of hydrolysis of specific substrates by carboxypeptidase A, and have returned to urease to examine the role of nickel in its mechanism of action.
Phylogeny of DNA Polymerase-β
Authors: Chang Lucy M. S.
Published: October 2006

Analyses of various organisms for DNA polymerase-β activity show that the enzyme is widely distributed in cells from multicellular animals but absent in bacteria, plants, and protozoa. These results suggest that DNA polymerase-β may have evolved with the development of metazoan forms. Further evolutionary changes of the enzyme protein may account for some of the minor differences in properties of the enzyme in various organisms.