bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Manipulation of Antibiotic-Producing Microorganisms
Authors: Vournakis John N. , Elander Richard P.
Published: October 2006

The application of directed selection techniques and genetic engineering methods for manipulation of antibiotic-producing microorganisms is generating a new era in industrial microbiology. Modern methods, based on advances in the knowledge of the biosynthetic pathways and regulatory mechanisms involved in the induction and repression of genes involved in antibiotic synthesis, provide a means of increasing antibiotic activity. Hence, recombinant DNA and protoplast fusion methods are used to alter the genetics of antibiotic producers in a semirandom fashion for the development of novel hybrid antibiotics. Directed mutation and selection, protoplast fusion, and both semirandom and specific recombinant DNA methods are examples of alternative procedures for manipulating the biosynthetic pathways of microorganisms for strain improvement and for new hybrid antibiotic synthesis.
Development of Hindlimb Locomotor Activity in the Bullfrog (
Rana catesbeiana
) Studied in Vitro
Authors: Stehouwer Donald J. , Farel Paul B.
Published: October 2006

The isolated central nervous system of the bullfrog larva (tadpole) is a valuable model system for studying the development of central motor control because the neural activity for locomotion is expressed in vitro. Patterned synaptic activation of immature hindlimb motoneurons is present before the bones and muscles of the hindlimb differentiate, and it develops against the background of the tadpole's functionally mature motor program for tail oscillations. This activation of hindlimb motoneurons later produces patterned bursting that underlies coordinated stepping and frog kicks.
Temporal Selectivity in the Central Auditory System of the Leopard Frog
Authors: Rose Gary , Capranica Robert R.
Published: October 2006

Amplitude modulation is a predominant temporal feature in many vocal signals. The leopard frog,
Rana pipiens
, has a class of neurons in the central auditory system that respond selectively to particular rates of amplitude modulation; these neurons can be characterized by a temporal tuning curve. Such selectivity is absent in the peripheral auditory system. This type of transformation may be fundamental in processing temporal information in the vertebrate sensory nervous system.
Proviral DNA of a Retrovirus, Human T-Cell Leukemia Virus, in Two Patients with AIDS
Authors: Gelmann Edward P. , Popovic Mikulas , Blayney Douglas , Masur Henry , Sidhu Gurdip , Stahl Rosalyn E. , Gallo Robert C.
Published: October 2006

The acquired immune deficiency syndrome (AIDS) is characterized by T-lymphocyte dysfunction and is frequently accompanied by opportunistic infections and Kaposi's sarcoma. Human T-cell leukemia virus (HTLV) is associated with T-cell malignancies and can transform T lymphocytes in vitro. In an attempt to find evidence of HTLV infection in patients with AIDS, DNA from samples of peripheral blood lymphocytes from 33 AIDS patients was analyzed by Southern blot-hybridization with a radiolabeled cloned HTLV DNA probe. Analysis of DNA from both the fresh (uncultured) lymphocytes and from T cells cultured with T-cell growth factor revealed the presence of integrated HTLV proviral sequences in lymphocytes from two of the patients, both of whom had antibody to HTLV. The proviral sequences could not be detected in blood samples obtained from these individuals at a later date, consistent with the possibility that the population of infected cells had become depleted.
Adaptive Changes of the Vestibulo-Ocular Reflex in Flatfish Are Achieved by Reorganization of Central Nervous Pathways
Authors: Graf W. , Baker R.
Published: October 2006

Flatfish provide a natural model for the study of adaptive changes in the vestibulo-ocular reflex system. During metamorphosis their vestibular and oculomotor coordinate systems undergo a 90° relative displacement. As a result, during swimming movements different types of compensatory eye movements are produced before and after metamorphosis by the same vestibular stimulation. Intracellular staining of central nervous connections in the flatfish with horseradish peroxidase revealed that in postmetamorphic fish secondary horizontal semicircular canal neurons contact vertical eye muscle motoneuron pools on both sides of the brain via pathways that are absent in all other vertebrates studied.
Dopaminergic Neurotoxicity of 1-Methyl-4-Phenyl-1,2,5,6-Tetrahydropyridine in Mice
Authors: Heikkila Richard E. , Hess Arthur , Duvoisin Roger C.
Published: October 2006

1-Methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) is known to cause an irreversible destruction of the dopaminergic nigrostriatal pathway and symptoms of parkinsonism in humans and in monkeys. However, MPTP has been reported to act only minimally or not at all in several other animal species. When MPTP (30 milligrams per kilogram of body weight) was administered parenterally to mice, a decrease in concentrations of neostriatal dopamine and its metabolites, a decrease in the capacity of neostriatal synaptosomal preparations to accumulate [
3
H]dopamine, and a disappearance of nerve cells in the zona compacta of the substantia nigra were observed. In contrast, MPTP administration had no effect on neostriatal concentrations of serotonin and its metabolites. MPTP administration thus results in biochemical and histological changes in mice similar to those reported in humans and monkeys and similar to those seen in Parkinson's disease in humans. The mouse should prove to be a useful small animal with which to study the mode of action of MPTP.
Membrane Changes in a Single Photoreceptor Cause Associative Learning in
Hermissenda
Authors: Farley Joseph , Richards William G. , Ling Lorraine J. , Liman Emily , Alkon Daniel L.
Published: October 2006

Single type B photoreceptors in intact, restrained
Hermissenda
were impaled with a microelectrode and exposed to either paired or unpaired presentations of light and depolarizing current to simulate natural stimulus effects during conditioning with light and rotation. Paired, but not unpaired, stimulus presentations produced cumulative depolarization and increased input resistance in type B cells. These membrane changes are similar to those observed after pairings of light and rotation are administered to either intact animals or isolated nervous systems or when light is paired with electrical stimulation of the vestibular system in isolated nervous systems. One and two days after treatment, pairing- and light-specific suppression of phototactic behavior was observed in recovered animals. These findings indicate that the membrane changes of type B cells produced by pairing light with current injections cause acquisition of the learned behavior.
Selective Recording and Stimulation of Individual Identified Neurons in Freely Behaving
Aplysia
Authors: Parsons David W. , ter Maat Andries , Pinsker Harold M.
Published: October 2006

A neuroethological technique is described for selective recording and stimulation of an individual neuron in freely behaving
Aplysia
by means of a fine wire glued into the connective tissue sheath above the identified cell body. A whole-nerve cuff electrode simultaneously monitored functionally related multiunit axon activity. For biophysical analysis the soma was impaled with a microelectrode when the ganglion was subsequently exposed. The technique is illustrated for several identified neurons involved in different behaviors.
Autonomic Nervous System Activity Distinguishes Among Emotions
Authors: Ekman Paul , Levenson Robert W , Friesen Wallace V.
Published: October 2006

Emotion-specific activity in the autonomic nervous system was generated by constructing facial prototypes of emotion muscle by muscle and by reliving past emotional experiences. The autonomic activity produced distinguished not only between positive and negative emotions, but also among negative emotions. This finding challenges emotion theories that have proposed autonomic activity to be undifferentiated or that have failed to address the implications of autonomic differentiation in emotion.
Turnover, Membrane Insertion, and Degradation of Sodium Channels in Rabbit Urinary Bladder
Authors: Loo Donald D. F. , Lewis Simon A. , Ifshin Mark S. , Diamond Jared M.
Published: October 2006

Noise analysis of rabbit bladder revealed two components: Lorentzian noise, arising from interaction of amiloride with the Na
+
channel, and flicker noise (1/
f
, where
f
is frequency), as in other biological membranes. Hydrostatic pressure, which causes exchange between intracellular vesicular membrane and apical membrane, increases the number but not the single-channel current of the amiloride-sensitive channels. Flicker noise arises from degraded channels that have lost amiloride sensitivity and Na
+
to K
+
selectivity. The degraded channels were selectively removed by washing the mucosal surface. These results imply channel turnover by intracellular synthesis, transfer from vesicular to apical membrane, degradation, and elimination.
Anisotropies in the Perception of Three-Dimensional Surfaces
Authors: Rogers Brian J. , Graham Maureen E.
Published: October 2006

The appearance of certain three-dimensional surfaces was found to depend on the orientation of the depth contours forming the surface. This was true both when the depth was specified by motion parallax and when it was specified by binocular disparities. Slowly changing depth surfaces that generated a pattern of relative motions or disparities characterized by a one-dimensional expansion-compression were perceived differently from those that produced a shear transformation.
Biogenesis of Ornithine Transcarbamylase in
spf
ash
Mutant Mice: Two Cytoplasmic Precursors, One Mitochondrial Enzyme
Authors: Rosenberg Leon E. , Kalousek Frantisek , Orsulak Michelle D.
Published: October 2006

Extracts of liver from hemizygous affected mice with the X-linked spf
ash
mutation have 5 to 10 percent of normal ornithine transcarbamylase (OTC) activity, yet the homogeneous enzyme isolated from these extracts is identical to that in controls. The OTC messenger RNA from mutant livers programs the synthesis of two distinct OTC precursor polypeptides—one normal in size, the other distinctly elongated. Both precursors are imported and proteolytically processed by mitochondria, but only the normal one is assembled into active trimer. This novel phenotype may result from a mutation in the structural gene for OTC leading, primarily, to aberrant splicing of OTC messenger RNA and, secondarily, to formation of a structurally altered precursor whose posttranslational pathway is ultimately futile because its mature mitochondrial form is not capable of assembly and functional expression.
Noninvasive Observations of Fluorinated Anesthetics in Rabbit Brain by Fluorine-19 Nuclear Magnetic Resonance
Authors: Wyrwicz Alice M. , Pszenny Margaret H. , Schofield John C. , Tillman Philip C. , Gordon Roy E. , Martin Peter A.
Published: October 2006

Fluorinated anesthetics were observed noninvasively in the brain of intact rabbits with fluorine-19 nuclear magnetic resonance spectroscopy. High-resolution fluorine-19 spectra of halothane, methoxyflurane, and isoflurane were obtained with a surface coil centered over the calvarium. Elimination of halothane from the brain was also monitored by this technique. Residual fluorine-19 signals from halothane (or a metabolite) could be detected as long as 98 hours after termination of anesthesia. These observations demonstrate the feasibility of using this technique to study the fate of fluorinated anesthetics in live mammals.
Normalization of Spiroperidol Binding in the Denervated Rat Striatum by Homologous Grafts of Substantia Nigra
Authors: Freed William J. , Ko Grant N. , Niehoff Debra L. , Kuhar Michael J. , Hoffer Barry J. , Olson Lars , Cannon-Spoor H. Eleanor , Morihisa John M. , Wyatt Richard Jed
Published: October 2006

Transplantation of embryonic substantia nigra into the adult rat brain decreases the motor asymmetry that is produced by dopamine receptor supersensitivity after a unilateral lesion of the substantia nigra. The authors report that this effect of transplantation is specific to grafts of substantia nigra. They also report that, in conjunction with the decrease in motor asymmetry, these grafts cause postsynaptic dopaminergic binding sites to return to normal density as measured by tritiated spiroperidol autoradiography. Thus, in animals with brain lesions, grafts of substantia nigra produce a long-term alteration in the functional status of host brain cell receptors that is associated with a reduction in the behavioral deficit.
6-Mercaptopurine Treatment of Pregnant Mice: Effects on Second and Third Generations
Authors: Reimers Thomas J. , Sluss Patrick M.
Published: October 2006

The immunosuppressive drug 6-mercaptopurine is embryotoxic in mice. Of the surviving female offspring of mice treated with low doses of 6-mercaptopurine during pregnancy, despite normal body weight and general appearance, many were either sterile or, if they became pregnant, had smaller litters and more dead fetuses as compared to offspring of mothers that had not received the drug.
The Stomach Signals Satiety
Authors: Deutsch J. A. , Young W. G. , Kalogeris T. J.
Published: October 2006

Inflatable pyloric cuffs and stomach tubes were implanted in rats. With the cuff inflated and a valve to limit intragastric pressure to that accompanying normal satiety, they drank only as much when they had been deprived of food for 12 hours as without inflation of the cuff. However, they overdrank with the cuff inflated when they had been water deprived for 12 hours. When 10 ml of milk was withdrawn from the stomach with the cuff inflated, compensatory drinking occurred. Further, compensatory drinking also occurred when milk escaped from the stomach into the duodenum. Satiety signals thus arise from the stomach.
Research in Instrument Sharing
Authors: Coulter Charles L.
Published: October 2006

Continued progress in many areas of science depends on access to advanced modern instruments and the data they provide. Costly instruments have been shared in a number of disciplines for many years, and common patterns of shared usage have developed independently. The scientific and financial aspects of large instrument usage are discussed from the points of view of the instrument centers, the users, and the funding agencies. The instrument problem is not one problem but many, and coordinated solutions must be implemented with well-defined goals based on knowledge of the needs of the users and developers of instruments.
DNA Structure: Evidence from Electron Microscopy
Authors: Griffith Jack D.
Published: October 2006

The contour lengths of φX174 DNA duplex and RNA-DNA hybrid molecules were measured by several commonly used electron microscopic techniques. The countour length of the hybrid molecules corresponds to a rise of 2.5 to 2.6 angstroms per base pair, as expected for the A conformation, while the length of φX174 duplex DNA similarly measured corresponds to a 2.9-angstrom rise, very different from 3.4 angstroms of the classic B form. Thus any chromatin structure parameter based on electron microscopy and a rise of 3.4 angstroms must be reappraised. The possibility that DNA in dilute solution also has a rise of 2.9 angstroms and a screw of 10.5 base pairs per turn is discussed.
Electrical Stimulation of the Amygdala as a Conditioned Stimulus in a Bait-Shyness Paradigm
Authors: Phillips Anthony G. , LePiane Fredric G.
Published: October 2006

Animals receiving low-intensity electrical stimulation of the basolateral nucleus of the amygdala while drinking plain tap water were injected with toxic doses of lithium chloride to examine whether brain stimulation can serve as a conditioned stimulus in a bait-shyness paradigm. Subjects receiving this pairing greatly reduced their water intake in a retention test, in a similar manner to a group in which saccharin was paired with poisoning. Pairing lithium chloride with stimulation of the amygdala had no effect on subsequent water intake in the absence of brain stimulation. This effect appears to be locus specific, as caudate stimulation could not serve as a conditioned stimulus.
Dietary Chloride as a Determinant of "Sodium-Dependent" Hypertension
Authors: Kurtz Theodore W. , Morris R. Curtis
Published: October 2006

The uninephrectomized rat given desoxycorticosterone (DOC) provides a classic model of "sodium-dependent" hypertension. In such rats, the extent to which a given dietary intake of sodium induced an increase in blood pressure depended on whether or not the anionic component of the sodium salt was chloride. With normal and high dietary intakes of sodium, sodium chloride induced increases in blood pressure much greater than that induced by approximately equimolar amounts of sodium bicarbonate, sodium ascorbate, or a combination of sodium bicarbonate and sodium ascorbate. A normal amount of dietary sodium chloride induced hypertension, whereas an equimolar amount of sodium bicarbonate did not increase blood pressure. This difference could not be attributed to differences in sodium or potassium balances, weight gain, or caloric intake. The DOC model of "sodium-dependent" hypertension might better be considered sodium chloride-dependent.
The Human Gene for the β Subunit of Nerve Growth Factor Is Located on the Proximal Short Arm of Chromosome 1
Authors: Francke Uta , de Martinville Bérengère , Coussens Lisa , Ullrich Axel
Published: October 2006

Fragments of the recently cloned human gene for the β subunit of nerve growth factor (β-NGF) were used as hybridization probes in analyzing two sets of rodent-human somatic cell hybrids for the presence of human β-NGF sequences. Results from the first set of hybrids assigned the human β-NGF gene to chromosome 1 and ruled out the presence of sequences of comparable homology on any other chromosome. With the second set of hybrids, which contained seven different, but overlapping, regions of chromosome 1, the NGF locus was mapped to band 1p22.
Compartmentation of Glycolytic and Glycogenolytic Metabolism in Vascular Smooth Muscle
Authors: Lynch Ronald M. , Paul Richard J.
Published: October 2006

Vascular smooth muscle is characterized by a high rate of aerobic lactate production, which may be altered independently of oxidative phosphorylation. This finding suggested a cytoplasmic compartmentation of metabolism. Exogenous glucose was found to be the sole precursor of aerobic glycolysis under unstimulated conditions. Although tissue depolarization with high K
+
resulted in a substantial reduction of endogenous glycogen, exogenous glucose remained the sole precursor of aerobic lactate production. These data showed unequivocally that carbohydrate metabolism is compartmentalized in vascular smooth muscle.
A Polypeptide Secreted by Transformed Cells That Modulates Human Plasminogen Activator Production
Authors: Davies Robin L. , Rifkin Daniel B. , Tepper Robert , Miller Anne , Kucherlapati Raju
Published: October 2006

A diffusible factor produced and secreted by malignant murine cells was capable of inducing plasminogen activator production by normal diploid human fibroblasts. The factor's ability to induce plasminogen activator was insensitive to treatment with nucleases, but its activity was destroyed by digestion with proteases. It is proposed that such a factor would play a role in malignancy if it would recruit normal cells that were adjacent to transformed cells to produce plasminogen activator which could result in tumor-promoted proteolysis.
X Chromosome-Linked Transmission and Expression of Retroviral Genomes Microinjected into Mouse Zygotes
Authors: Stewart Colin , Harbers Klaus , Jähner Detlev , Jaenisch Rudolf
Published: October 2006

A genomic clone consisting of the Moloney leukemia proviral genome with moderately repetitive mouse sequences was microinjected into the pronucleus of a mouse zygote. An animal was derived that carried multiple copies of proviral DNA in a tandem array. No evidence for homologous recombination was obtained. The viral genome was expressed in this animal and was transmitted as a single unit to its offspring. Subsequent breeding studies revealed that the proviral DNA had integrated on an X chromosome.
Childhood Leukemia and Fallout from the Nevada Nuclear Tests
Authors: Land Charles E. , McKay Frank W. , Machado Stella G.
Published: October 2006

Cancer mortality data from the National Center for Health Statistics, covering the period 1950 through 1978, were used to test a reported association between childhood leukemia and exposure to radioactive fallout from nuclear weapons tests in Nevada between 1951 and 1958. No pattern of temporal and geographic variation in risk supportive of the reported association was found. Comparison of these results with those presented in support of an association of risk with fallout suggests that the purported association merely reflects an anomalously low leukemia rate in southern Utah during the period 1944 to 1949.
Nurturing the Scientific Enterprise
Authors: Wyngaarden James B.
Published: October 2006

The National Institutes of Health has given its highest priority to funding investigator-initiated projects and to minimizing year-to-year fluctuations in the number of new and competing awards. Adequate funding for centers, research contracts, intramural research, and training is also necessary for creation of the science base essential to sustaining the powerful momentum of recent progress. The important question for the future is whether the present system is sufficiently flexible and imaginative to keep pace with the contemporary revolution in science.
Crystals of the Octameric Histone Core of the Nucleosome
Authors: Burlingame Rufus W. , Love Warner E. , Moudrianakis Evangelos N.
Published: October 2006

The undegraded core histone octamer has been crystallized in a form suitable for x-ray analysis. The hexagonal bipyramidal crystals reproducibly grow larger than 1.0 by 0.6 millimeter, X-ray reflections are observed from Bragg planes with spacings larger than 3.5 angstroms. The crystals have the symmetry of the space group P3
1
21 or its enantiomorph. There appears to be one histone octamer per asymmetric unit.
Stature Throughout the World
Authors: Bean R. Bennett
Published: October 2006

Tropic jungle life has an influence that decreases stature, and so has Arctic cold and waste. In each there is difficulty in procuring proper food, and discomfort in the extreme.

The active life of the temperate zone with its comforts and abundant food supply produces the tallest statures.

The greatest extremes of small stature are found among the Negrillos of Central Africa and the Aymaras of Central South America, in the jungles of excessive heat and poor food supply. Next to these come the Eskimos, Lapps and Siberians, with ice and excessive cold and poor food supply. On the other hand, the littoral and southern Baltic regions in Europe, the western part of Asia, eastern Africa, and the plains and pampas of the Americas with their active life, abundant food supply and temperate climate produce the tallest statures.

Certain stocks may move into areas for which they are not fitted and remain for a time, and such conditions exist throughout the world to-day where recent movements of peoples have taken place, but ultimately there is a survival of the stock best fitted for the environment, and the unfitted stocks disappear by amalgamation, eradication or dispersal.

Sea areas and probably sea food have an influence in reducing stature. The present Mediterranean peoples and the primordial British have small statures and so does Japan, yet they came from taller continental stocks. The Central Americans and Fuegians are smaller than the continental peoples near-by. The Malays and southern Asiatics are smaller than the peoples of the interior of the continent. Other instances might be cited.

There is some evidence that the seaboard statures of the United States are less than those of the interior, but other factors enter here.

Looked at in its broadest sense, environment molds the individual, selection retains the fittest under different environments, and heredity carries on the results.
Differential NK Cell and Macrophage Killing of Hamster Cells Infected with Nononcogenic or Oncogenic Adenovirus
Authors: Cook James L. , Lewis Andrew M.
Published: October 2006

Hamster cells infected with highly oncogenic human adenovirus type 12 (Ad12) were resistant to lysis by natural killer cells and macrophages, compared to cells infected with nononcogenic adenovirus type 2 (Ad2). The data suggest that early adenovirus gene expression in hamster cells results in preferential survival of Ad12, compared to Ad2, infected cells in vivo, thus providing an explanation for the differences in the oncogenicities of these two transforming viruses.
Direct Excitatory Interactions Between Cones of Different Spectral Types in the Turtle Retina
Authors: Normann Richard A. , Perlman Ido , Kolb Helga , Jones Jill , Daly Scott J.
Published: October 2006

Cone linear sensitivities to red and green stimuli were measured intracellularly in the dark- and light-adapted turtle retina. Test flashes of small diameter were used to minimize horizontal cell feedback. Light adaptation was achieved with either green or red background illumination. The ratio of cone sensitivities to red and green light depended on the color of the background light and differed from the ratio measured in the dark. Electron microscope studies of Golgi-stained turtle cones revealed direct synaptic connections between red and green cones mediated by cone telodendria. These data indicate that the red cone photoresponse is not univariant as has been previously supposed and suggest that mixing of signals from different spectral classes of cones can occur via direct excitatory connections between cones.
Genetic Influences in Criminal Convictions: Evidence from an Adoption Cohort
Authors: Mednick Sarnoff A. , Gabrielli William F. , Hutchings Barry
Published: October 2006

The possibility that genetic factors are among the causes of criminal behavior was tested by comparing court convictions of 14,427 adoptees with those of their biological and adoptive parents. A statistically significant correlation was found between the adoptees and their biological parents for convictions of property crimes. This was not true with respect to violent crimes. There was no statistically significant correlation between adoptee and adoptive parent court convictions. Siblings adopted separately into different homes tended to be concordant for convictions, especially if the shared biological father also had a record of criminal behavior.
Treatment of a 12-Hour Shift of Sleep Schedule with Benzodiazepines
Authors: Seidel Wesley F. , Roth Thomas , Roehrs Timothy , Zorick Frank , Dement William C.
Published: October 2006

Normal sleepers underwent sleep recordings and daytime tests of sleep tendency, performance, and mood while being shifted 180° in their sleep-wake schedule. After two baseline 24-hour periods, subjects postponed sleep until noon. For the next three 24-hour periods, they were in bed from 1200 to 2000 and received triazolam, flurazepam, or placebo at bedtime in parallel groups. Placebo subjects showed significant sleep loss after the shift. Active medication reversed this sleep loss. Despite good sleep, flurazepam subjects appeared most impaired of the three groups on objective assessments of waking function; triazolam subjects were least impaired.
Duchenne Muscular Dystrophy Involving Translocation of the
dmd
Gene Next to Ribosomal RNA Genes
Authors: Worton Ronald G. , Duff Catherine , Sylvester James E. , Schmickel Roy D. , Willard Huntington F.
Published: October 2006

Duchenne muscular dystrophy (DMD) is a severe X-linked disorder leading to early death of affected males. Females with the disease are rare, but seven are known to be affected because of a chromosomal rearrangement involving a site at or near the
dmd
gene on the X chromosome. One of the seven has a translocation between the X and chromosome 21. The translocation-derived chromosomes from this patient have been isolated, and the translocation is shown to have split the block of genes encoding ribosomal RNA on the short arm of chromosome 21. Thus ribosomal RNA gene probes may be used to identify a junction fragment from the translocation site, allowing access to cloned segments of the X at or near the
dmd
gene and presenting a new approach to the study of this disease.
Characterization and Localization of Proopiomelanocortin Messenger RNA in the Adult Rat Testis
Authors: Pintar John E. , Schachter Beth S. , Herman Andrea B. , Durgerian Sally , Krieger Dorothy T.
Published: October 2006

Northern blot analysis of total RNA and polyadenylated RNA isolated from adult rat testes showed that a proopiomelanocortin (POMC)-like messenger RNA molecule is present in these extracts. The testicular POMC messenger RNA is comparable in length to amygdala and midbrain POMC messenger RNA and appears to be at least 200 nucleotides shorter than POMC messenger RNA found in the hypothalamus and anterior and intermediate lobes of the pituitary gland. Hybridization in situ showed that POMC messenger RNA is located in Leydig cells, which are the only testicular cells that contain immunostainable POMC-derived peptides. These results suggest that local synthesis of POMC occurs in the testis.
Stimulated DNA Synthesis in Frog Nuclei by Cytoplasmic Extracts of Temperature-Sensitive Mammalian Cells
Authors: Floros Joanna , Chang Helena , Baserga Renato
Published: October 2006

Cytoplasmic extracts of proliferating cells stimulate DNA synthesis in isolated nuclei of
Xenopus laevis
liver. When tested by the same assay, cytoplasmic extracts of resting cells are completely inactive. When cytoplasmic extracts are prepared from cell cycle-specific temperature-sensitive mutants arrested in the G
1
phase of the cell cycle by the nonpermissive temperature, they also fail to stimulate DNA synthesis in frog nuclei. The results indicate that, to stimulate DNA synthesis in isolated frog nuclei, essentially all information of G
1
cells must be present.
The Heart Is a Target Organ for Androgen
Authors: McGill H. C. , Anselmo V. C. , Buchanan J. M. , Sheridan P. J.
Published: October 2006

Autoradiographic and biochemical analyses of the hearts of female rhesus monkeys and baboons indicate that atrial and ventricular myocardial cells contain androgen receptors. Although the specific effects of nuclear uptake and retention of androgen on the function of heart muscle cells are not known, the presence of this receptor suggests that sex steroid hormones may affect myocardial function directly and may explain some of the peculiar differences in heart disease between men and women.
Fertilization of Squirrel Monkey and Hamster Ova in the Rabbit Oviduct (Xenogenous Fertilization)
Authors: DeMayo F. J. , Mizoguchi H. , Dukelow W. R.
Published: October 2006

Homologous sperm and ova of either squirrel monkeys or hamsters were placed in the oviducts of pseudopregnant rabbits. Xenogenous fertilization rates of 36 and 60 percent were obtained for squirrel monkey and hamster gametes, respectively.
Regression of Aflatoxin B
1
-Induced Hepatocellular Carcinomas by Reduced Glutathione
Authors: Novi Anna M.
Published: October 2006

Reduced glutathione administered to rats bearing aflatoxin B
1
-induced liver tumors caused regression of tumor growth and resulted in survival of the animals. Since glutathione is a harmless natural product, it merits further investigation as a potential antitumor drug for humans.
Divalent Cation Ionophores Stimulate Resorption and Inhibit DNA Synthesis in Cultured Fetal Rat Bone
Authors: Lorenzo Joseph A. , Raisz Lawrence G.
Published: October 2006

Two divalent cation ionophores, A23187 and Ionomycin, which are selective for calcium, stimulated the resorption of fetal rat long bones in organ culture at 0.1 to 1 micromolar but not at higher concentrations. Both agents inhibited DNA synthesis at concentrations that stimulated resorption. These results might explain the differences in ionophore effects on bone previously reported, and they imply that cell replication is not required for osteoclast formation in fetal rat long bone cultures.
Reversal Diabetes by Islet Transplantation: Vulnerability of the Established Allograft
Authors: Bowen K. M. , Prowse S. J. , Lafferty K. J.
Published: October 2006

Nonspecific stimulation of the immune system of CBA mice carrying a functional BALB/c islet allograft failed to trigger graft rejection. Only three of six animals rejected their graft when injected intravenously with 10
5
, 10
6
, and 10
7
peritoneal cells of BALB/c origin over a 3-month period commencing 100 days after transplantation.
Steady-State Relationship of Calcium-45 Between Bone and Blood: Differences in Growing Dogs, Chicks, and Rats
Authors: Klein LeRoy
Published: October 2006

In young animals that had received multiple doses of calcium-45, a constant ratio of calcium-45 specific activity in blood to that in bone was found in growing dogs and chicks but not in rats. This steady-state relationship of calcium-45 between bone and blood suggests that during growth in dogs and chicks most of the skeletal calcium is in an active state of turnover. In growing rats, after the first 2 weeks of life, the blood/bone ratio of calcium-45 decreases due to a decrease in bone resorption.
Type III Hyperlipoproteinemia Associated with Apolipoprotein E Deficiency
Authors: Ghiselli Giancarlo , Schaefer Ernst J. , Gascon Pedro , Breser H. Bryan
Published: October 2006

Subjects with type III hyperlipoproteinemia develop premature atherosclerosis and have hyperlipidemia due to an increase in cholesterol-rich very low density lipoproteins (VLDL) of abnormal electrophoretic mobility. Apolipoprotein E is a major protein constituent of VLDL and appears to be important for the hepatic uptake of triglyceride-rich lipoproteins. A new kindred of patients with type III hyperlipoproteinemia is described in which no plasma apolipoprotein E could be detected, consistent with the concept that type III hyperlipoproteinemia may be due to an absence or striking deficiency of apolipoprotein E.
Luteal Phase Defects Induced by an Agonist of Luteinizing Hormone-Releasing Factor: A Model for Fertility Control
Authors: Sheehan K. L. , Casper R. F. , Yen S. S. C.
Published: October 2006

Subcutaneous injection of 50 micrograms of a luteinizing hormone-releasing factor agonist (LRF agonist) for three successive days at the time of menstruation in normal cycling women induces a shortened luteal phase with suboptimal concentrations of circulating estradiol and progesterone. This luteal phase defect follows a reduced concentration of follicle-stimulating hormone during the follicular phase and a resulting inadequate follicular maturation. Since a short luteal phase is associated with an endometrium not conducive to implantation, administration of the LRF agonist at the onset of menstrual cycle may prove to be a practical and novel approach to fertility control.
Cannabinoids in Male Mice: Effects on Fertility and Spermatogenesis
Authors: Dalterio Susan , Badr Fouad , Bartke Andrzej , Mayfield Denise
Published: October 2006

Exposure of adult male mice to cannabinoids is associated with a reduction in fertility and an increased incidence of chromosomal abnormalities. These effects are evident not only in the treated mice, but also in their untreated male offspring.
Alpha-Substituted γ-Butyrolactones: New Class of Anticonvulsant Drugs
Authors: Klunk William E. , McKeon Ann C. , Covey Douglas F. , Ferrendelli James A.
Published: October 2006

Alkyl-Substituted γ-butyrolactones were synthesized and tested for their convulsant and anticonvulsant actions in mice and guinea pigs. The alpha-substituted compounds, α, α-dimethyl-, and α-ethyl-α-methyl-γ-butyrolactone were anticonvulsant compounds with a spectrum of activity similar to that of ethosuximide. In contrast, beta-substituted compounds were convulsant agents similar to picrotoxinin. The alpha-substituted γ-butyrolactones represent a new class of anticonvulsant drugs with experimental and clinical potential.
Mammalian Tyrosinase Catalyzes Three Reactions in the Biosynthesis of Melanin
Authors: Körner Ann , Pawelek John
Published: October 2006

The biosynthesis of melanin is initiated by the catalytic oxidation of tyrosine to dopa by tyrosinase in a reaction that requires dopa as a cofactor. Tyrosinase then catalyzes the dehydrogenation of dopa to dopaquinone. The subsequent reactions can proceed spontaneously in vitro. Tyrosinase, purified from murine melanomas and the skins of brown mice, has now been shown to catalyze a third reaction in mammalian melanogenesis, namely the conversion of 5,6-dihydroxyindole to melanochrome. This reaction requires dopa as a cofactor and is inhibited by tyrosine. Conversely, 5,6-dihydroxyindole inhibits the oxidation of tyrosine to dopa, so that the relative concentrations of tyrosine and 5,6-dihydroxyindole within the mammalian pigment cell are capable of regulating melanogenesis in a previously unrecognized fashion. Tyrosinase has the unusual property of catalyzing three distinct reactions within a single biochemical pathway: the hydroxylation of a monophenol, the dehydrogenation of a catechol, and the dehydrogenation of a dihydroxyindole. The first and third of these reactions require dopa as a cofactor; in the second reaction, dopa is a substrate.
Destruction of
Trypanosoma cruzi
by Natural Killer Cells
Authors: Hatcher Frank M. , Kuhn Raymond E.
Published: October 2006

Mice infected with
Trypanosoma cruzi
or stimulated with poly(inosinic ⋅ cytodylic acid) were found to possess splenic and peritoneal exudate cells with enhanced cytotoxic activity against epimastigote and trypomastigote forms of
Trypanosoma cruzi
. By use of specific alloantiserums it was determined that the effector cells responsible for this cytotoxic activity were typical natural killer cells.
Chronic Parkinsonism in Humans Due to a Product of Meperidine-Analog Synthesis
Authors: Langston J. William , Ballard Philip , Tetrud James W. , Irwin Ian
Published: October 2006

Four persons developed marked parkinsonism after using an illicit drug intravenously. Analysis of the substance injected by two of these patients revealed primarily 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) with trace amounts of 1-methyl-4-phenyl-4-propionoxy-piperidine (MPPP). On the basis of the striking parkinsonian features observed in our patients, and additional pathological data from one previously reported case, it is proposed that this chemical selectively damages cells in the substantia nigra.
Action Potentials in Macrophages Derived from Human Monocytes
Authors: McCann Frances V. , Cole James J. , Guyre Paul M. , Russell Jerome A. G.
Published: October 2006

The electrical activity of macrophages derived from human blood monocytes was recorded in vitro with intracellular microelectrodes and was analyzed with computer-assisted data acquisition and analysis techniques. In cells impaled 6 to 8 days after the cultures were prepared, the resting potentials reached a maximum value of -72 millivolts. The cells were electrically excitable; spikes exhibited a slow upstroke, a fast downstroke, a discrete threshold, a large overshoot, and a brief undershoot. Repetitive firing was induced by a maintained depolarizing current. A positive relation was observed between transmembrane currents and resting potential. Voltage-current relations were nonrectifying for subthreshold current injections. Since these cells had not been treated with any specific activation factors, the electrical activity recorded is evidence for the presence of voltage-dependent inward and outward currents in the membranes of mature macrophages. The electrical signals generated by these cells may be useful for the assay of sensor and effector functions of macrophages, such as chemotaxis, receptor-ligand interactions, and phagocytosis.
Spermidine Requirement for Cell Proliferation in Eukaryotic Cells: Structural Specificity and Quantitation
Authors: Porter Carl W. , Bergeron Raymond J.
Published: October 2006

Six structural homologs of spermidine and five of its precursor, putrescine, were studied for their ability to prevent cytostasis of cultured L1210 leukemia cells induced by α-difluoromethylornithine (DFMO), a specific inhibitor of putrescine biosynthesis. High-performance liquid chromatography and competition studies with spermidine indicated that the homologs, which vary in the length of the carbon chain separating the amines, penetrated the cells. The structural specificity of the spermidine carrier was defined. Three of the six spermidine homologs supported cell growth during a 48-hour incubation in the presence of DFMO, indicating that a two-carbon extension of spermidine structure was tolerated for biological function. Two of the five putrescine homologs supported growth after being converted by the cells to their respective spermidine homologs. The central nitrogen of spermidine appears to be essential for function since diamines of chain length comparable to that of spermidine did not prevent DFMO cytostasis. No more than 15 percent of the spermidine normally present in L1210 cells was required for cell proliferation in the presence of DFMO.
Role of Surface-Active Phospholipids in Gastric Cytoprotection
Authors: Lichtenberger Lenard M. , Graziani Lynne A. , Dial Elizabeth J. , Butler Bruce D. , Hills Brian A.
Published: October 2006

Intragastric administration of a liposomal surfactant suspension markedly reduced acid-induced gastric ulcerogenesis and bleeding in rats. The concentration of surface-active molecules intrinsically present in the gastric mucosa was increased two to six times by administration of 16,16-dimethyl prostaglandin E
2
. Thus, local accumulation of surface-active phospholipids may be an integral component of the cytoprotective mechanism activated by prostaglandin treatment.
Retrieval of Information from Long-Term Memory
Authors: Anderson John R.
Published: October 2006

Information is represented in long-term memory as a network of associations among concepts. Information is retrieved by spreading activation from concepts in working memory through the network structure. The time required to retrieve information is a function of the level of activation that it achieves. Fanning of multiple paths from a node dissipates the activation the node sends down any path and increases retrieval time. Fan effects are reduced as subjects overlearn the material or when they can change their task from a recognition judgment to a consistency judgment.
Trypsin Inhibition by Tapeworms: Antienzyme Secretion or
p
H Adjustment?
Authors: Uglem Gary L. , Just John J.
Published: October 2006

The tapeworm
Hymenolepis diminuta
releases proteins that inhibit trypsin activity. These proteins may be either antienzymes or nonspecific macromolecules that interfere with trypsin. Saline solutions with initial
p
H values ranging from 5.5 to 10.0 were all acidified to
p
H 5.0 by tapeworms. If the initial
p
H was lower than 5.0, it was raised. Because trypsin activity is inhibited at
p
H 5.0, this intestinal parasite can protect itself from digestion by regulating its environmental
p
H or releasing trypsin inhibitors, or both.
Potential Role of Galactokinase in Neonatal Carbohydrate Assimilation
Authors: Kliegman R. M. , Miettinen E. L. , Morton S.
Published: October 2006

Glucose given to the newborn human may result in hyperglycemia, suggesting that its utilization is impaired at this developmental stage. Galactose is thought to be a more appropriate carbohydrate source for the newborn. The enzymes involved in hexose phosphorylation may, in part, be responsible for these observations. A key regulatory enzyme of hepatic glucose assimilation, glucokinase, is diminished in newborns compared to adults, whereas galactokinase activity is increased. When newborn dogs were fasted and then fed either glucose or galactose, their plasma insulin responses to glucose were similar, but the pups fed galactose demonstrated an attenuated systemic appearance rate of glucose. Hexose incorporation into hepatic glycogen and net glycogen synthesis was augmented in the galactose-fed dogs. In vitro, liver from neonatal dogs showed enhanced galactokinase activity relative to that for hexokinase or glucokinase. Neonatal hexose assimilation may be independent of insulin action and, instead, be related to the developmental presence of hexose phosphorylating enzymes.
Digoxin-Inactivating Bacteria: Identification in Human Gut Flora
Authors: Dobkin Jay F. , Saha Jnan R. , Butler Vincent P. , Neu Harold C. , Lindenbaum John
Published: October 2006

Digoxin, the most widely used cardiac glycoside, undergoes significant metabolic conversion in many patients to cardioinactive metabolites in which the lactone ring is reduced. This appears to occur within the gastrointestinal tract. An attempt was made to isolate and identify the organisms capable of reducing digoxin from stool cultures obtained from human volunteers. Of hundreds of isolates studied, only
Eubacterium lentum
, a common anaerobe of the human colonic flora, converted digoxin to reduced derivatives. Such organisms were also isolated in high concentrations from the stools of individuals who did not excrete these metabolites when given digoxin in vivo. When the growth of
E. lentum
was stimulated by arginine, inactivation of digoxin was inhibited. Neither the presence of these organisms alone nor their concentration within the gut flora appeared to determine whether digoxin would be inactivated by this pathway in vivo.
Contiguity to Males in Utero Affects Avoidance Responding in Adult Female Mice
Authors: Hauser Herbert , Gandelman Ronald
Published: October 2006

Female mice that had been situated in utero between two female fetuses displayed higher levels of active avoidance responding in adult life than females that had been located between two male fetuses and males for whom uterine position was without effect. Uterine position, therefore, influences acquired as well as species-typical behaviors.
Radioactive Labeling of Antibody: A Simple and Efficient Method
Authors: Hnatowich D. J. , Layne W. W. , Childs R. L. , Lanteigne D. , Davis M. A. , Griffin T. W. , Doherty P. W.
Published: October 2006

A simple and efficient method of covalently coupling the strong chelator diethylenetriaminepentaacetic acid to proteins was developed for radiolabeling immunoglobulin G antibodies. After being coupled and labeled with indium-111, a monoclonal antibody to carcinoembryonic antigen retained its ability to bind to its antigen in vitro and in vivo. In nude mice with a human colorectal xenograft, 41 percent of the injected radioactivity became localized in each gram of xenograft at 24 hours compared with 9 percent for control antibody and 19 percent for radioiodinated antibody to carcinoembryonic antigen.
Microwear of Mammalian Teeth as an Indicator of Diet
Authors: Walker Alan , Hoeck Hendrick N. , Perez Linda
Published: October 2006

Microwear details on teeth of two sympatric species of hyrax are correlated with major dietary differences observed in the wild. Grazing (
Procavia johnstoni
) and browsing (
Heterohyrax brucei
) species can be distinguished. The results show that diets of extinct species may be deduced from tooth microwear.
The Fanconi Syndrome in Basenji Dogs: A New Model for Renal Transport Defects
Authors: Bovee K. C. , Joyce T. , Reynolds R. , Segal S.
Published: October 2006

The renal defects resulting in a Fanconi syndrome were seen in eight Basenji dogs by measuring renal clearance and in vitro amino acid and sugar uptake and performing histopathologic evaluations. Renal tubular handling of glucose, phosphate, sodium, potassium, uric acid, and amino acids was abnormal, and in vitro uptake of labeled lysine, glycine, and α-methyl-D-glucoside by renal cortical slices was impaired. Histopathology was normal except for enlarged nuclei in some renal tubule cells. These Basenji dogs, which may be genetically affected, represent a likely model for idiopathic Fanconi syndrome in humans.