bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell Biology of Synaptic Plasticity
Authors: Cotman Carl W. , Nieto-Sampedro Manuel
Published: October 2006

The nervous system of mammals retains throughout the animals' life-span the ability to modify the number, nature, and level of activity of its synapses. Synaptic plasticity is most evident after injury to the nervous system, and the cellular and molecular mechanisms that make it possible are beginning to be understood. Transplantation of brain tissue provides a powerful approach for studying mechanisms of synaptic plasticity. In turn, understanding the response of the central nervous system to injury can be used to optimize transplant survival and integration with the host brain.
Neurotrophic Influence on Lobster Skeletal Muscle
Authors: Lang Fred , Ogonowski Mark M. , Costello Walter J. , Hill Russell , Roehrig Beverly , Kent Karla , Sellers James
Published: October 2006

The correlation between histochemical properties of muscle fibers and the pattern of innervation by the two motor neurons was studied in the asymmetric claw closer muscles of the lobster. The closer muscle of the cutter claw is composed of 65 percent fast muscle fibers and 35 percent slow muscle fibers, whereas that in the crusher claw has all slow muscle fibers. In both claws, myofibrillar adenosinetriphosphatase activity was independent of the pattern of innervation. Oxidative capacity, as measured by reduced nicotinamide adenine dinucleotide activity, was correlated with motor axon presence: Muscle fibers innervated solely by the "fast" motor axon had low oxidative capacity, muscle fibers receiving only the slow motor axon had very high oxidative capacity, and fibers innervated by both axons had intermediate properties. The data suggest that the motor neurons may exert trophic influences that control certain muscle fiber properties but not others.
High-Resolution Proton Nuclear Magnetic Resonance Analysis of Metastatic Cancer Cells
Authors: Mountford Carolyn E. , Wright Lesley C. , Holmes Kerry T. , Mackinnon Wanda B. , Gregory Patricia , Fox Richard M.
Published: October 2006

High-resolution proton nuclear magnetic resonance (NMR) studies of intact cancer cells revealed differences between cells with the capacity to metastasize and those that produce locally invasive tumors. The NMR resonances that characterize the metastatic cells were associated with an increased ratio of cholesterol to phospholipid and an increased amount of plasma membrane-bound cholesterol ester. High-resolution NMR spectroscopy could therefore be used to assess the metastatic potential of primary tumors.
Cardiac Atria of BIO 14.6 Hamsters Are Deficient in Natriuretic Factor
Authors: Chimoskey J. E. , Spielman W. S. , Brandt M. A. , Heidemann S. R.
Published: October 2006

The hearts of 220-day-old hamsters of the BIO 14.6 strain are deficient in atrial natriuretic factor; saline extracts of atria produce one-third the natriuretic and diuretic effects of extracts of atria from age-matched normal hamsters. BIO 14.6 hamsters are known to develop congestive heart failure with edema when they are about 200 days old, and the venous congestion and edema are preventable by parabiosis with normal hamsters. The humoral mediator, the deficiency of which causes venous congestion and edema in BIO 14.6 hamsters, may be atrial natriuretic factor.
Amplification of the c-
myb
Oncogene in a Case of Human Acute Myelogenous Leukemia
Authors: Pelicci Pier-Giuseppe , Lanfrancone Luisa , Brathwaite Michel D. , Wolman Sandra R. , Dalla-Favera Riccardo
Published: October 2006

Amplification is one of the mechanisms by which cellular oncogenes may be altered in their function, possibly leading to neoplastic transformation. The oncogenes c-
myc
, c-
abl
, and c-Ki-
ras
are amplified in several different human neoplasias. The oncogene c-
myb
, which is specifically expressed and regulated in hematopoietic cells, was found to be amplified in cell lines ML-1, ML-2, and ML-3, which were separately cultured from cells of a patient with acute myelogenous leukemia (AML). A five- to tenfold amplification was correlated with high levels of expression of normal size c-
myb
messenger RNA and with chromosomal abnormalities in the region 6q22-24, where the c-
myb
locus is normally located. Amplification and cytogenetic abnormalities were detected in DNA's from primary and secondary cultures of ML cells, suggesting that they may have contributed to leukemogenesis. The similar AML cell lines HL-60 and ML's contain different amplified oncogenes: c-
myc
and c-
myb
, respectively. Alternative activation of structurally and possibly functionally similar oncogenes may distinguish—at the pathogenetic level—phenotypically similar tumors.
Labeled Putrescine as a Probe In Brain Tumors
Authors: Volkow Nora , Goldman Stephen S. , Flamm Eugene S. , Cravioto Humberto , Wolf Alfred P. , Brodie Jonathan D.
Published: October 2006

The polyamine metabolism of transplanted
N
-nitrosomethylurea-derived rat glioma was determined with radiolabeled putrescine used as a marker for malignancy. The uptake of putrescine in vivo was complete within 5 minutes and was specific for tumor tissue. The conversion of putrescine to spermine and other metabolites by the tumor was rapid, in contrast to the case for adjacent normal brain. These results suggest that putrescine labeled with carbon-11 may be used as a positron-emission tomographic tracer for the selective metabolic imaging of brain tumor and may be used in an appropriate model as a marker for tumor growth rate.
Extensive Dendritic Sprouting Induced by Close Axotomy of Central Neurons in the Lamprey
Authors: Hall Garth F. , Cohen Melvin J.
Published: October 2006

Massive dendritic sprouting was induced in identified giant reticulospinal neurons of the lamprey by axotomy close to the soma. An axonal lesion slightly farther from the cell body induced new growth from both dendrites and axon. The amount of new growth per cell was the same whether it originated from the dendrites alone or from axonal and dendritic compartments. The location of the axonal lesion therefore determines where, in the neuron, membrane is inserted to produce the new neurites. The dendritic tree of a differentiated vertebrate central neuron was shown to have sufficient plasticity to extend new growth for several millimeters beyond the normal dendritic domain.
Visual Phenomena Induced by Relativistic Carbon Ions with and Without Cerenkov Radiation
Authors: McNulty P. J. , Pease V. P. , Bond V. P.
Published: October 2006

Exposing the human eye to individual carbon ions (
6
C
+
) moving at relativistic speeds results in visual phenomena that include point flashes, streaks, and larger diffuse flashes. The diffuse flashes have previously been observed by astronauts in space but not in laboratory experiments with particles of high atomic number and energy. They are observed only when the nucleus moves fast enough to generate Cerenkov radiation.
Identification of Presynaptic Neurons by Laser Photostimulation
Authors: Farber Ira C. , Grinvald Amiram
Published: October 2006

An optical method involving the use of a laser and a novel fluorescent dye as a photostimulation probe has been developed to identify presynaptic neurons in a large ensemble of cells. Illumination of an extracellularly stained neuron by the laser microbeam evokes action potentials. With this technique an interneuron connecting identified leech neurons was quickly located. The method speeds up the elucidation of neuronal networks, especially when small cells are involved.
Activation of Dormant Genes in Specialized Cells
Authors: DiBerardino Marie A. , Hoffner Nancy J. , Etkin Laurence D.
Published: October 2006

In several experimental systems the genomic capacity in specialized cells can be assessed by examining the activation of dormant genes. Since some of these specialized cells can be induced to change cell phenotype, all cell specializations do not necessarily involve irreversible genetic changes.
Colloidal Solution of Water in Organic Solvents: a Microheterogeneous Medium for Enzymatic Reactions
Authors: Martinek Karel , Levashov A. V. , Khmelnitsky Yu. L. , Klyachko N. L. , Berezin I. V.
Published: October 2006

To simulate in vitro the conditions under which enzymes act in vivo, enzyme molecules have been entrapped in hydrated reverse micelles of a surfactant in organic solvents. In this system the catalytic activity of one of the enzymes studied (peroxidase) became much higher than in water, and the specificity of the other enzyme (alcohol dehydrogenase) was dramatically altered.
Immunofluorescence of NADPH-Cytochrome
c
(P450) Reductase in Rat and Minipig Tissues Injected with Phenobarbital
Authors: Dees Jane Howard , Coe Larry Dean , Yasukochi Yukio , Masters Bettie Sue
Published: October 2006

The enzyme NADPH-cytochrome
c
(P-450) reductase was identified by indirect immunofluorescence in hepatocytes, bronchioles, and proximal tubules of liver, lung, and kidney, respectively, of rats and minipigs that had been injected with phenobarbital or saline. The distribution of this component of the cytochrome P-450-mediated microsomal system may be relevant to sites of drug toxicity and carcinogenesis.
Incorporation of 4-Amino-5-Hydroxymethylpyrimidine into Thiamine by Microorganisms
Authors: White Robert H.
Published: October 2006

One possible route for the biosynthesis of the (4-amino-2-methyl-5-pyrimidyl)-methyl moiety of thiamine would involve the formation of a methyl group on the demethylated pyrimidine, 4-amino-5-hydroxymethylpyrimidine, before its incorporation into thiamine. This possibility was tested by preparing the 4-amino-5-hydroxymethylpyrimidine and feeding it to
Escherichia coli
.
Bacillus subtilis
, and
Saccharomyces cerevisiae
. Analysis of the thiamine produced by these organisms showed that 4-amino-5-hydroxymethylpyrimidine was readily incorporated into thiamine without the addition of a methyl group, and no evidence was found for the conversion of this pyrimidine into normal methylated pyrimidine. Substitution of the demethylated thiamine for thiamine had no effect on the growth rate or the yield of
E. coli
cells. Complete substitution of the thiamine with the (4-amino-5-pyrimidyl)-methyl moiety was possible in an
E. coli
pur I mutant. The extent of incorporation of the demethylated pyrimidine decreased in some organisms and increased in others by the addition of adenine to the growth medium; this difference led to a simple test to separate organisms that use 5-aminoimidazole ribonucleotide for the biosynthesis of thiamine pyrimidine from those that do not.
Monoclonal Antibodies to Hypothalamic Growth Hormone-Releasing Factor with Picomoles of Antigen
Authors: Luben Richard A. , Brazeau Paul , Bohlen Peter , Guillemin Roger
Published: October 2006

Monoclonal antibodies specific for rat hypothalamic growth hormone-releasing factor (rGRF) have been produced by in vitro immunization of mouse spleen cells with less than 1 nanomole of rGRF in a partially purified preparation. Hybridoma supernatants were screened for anti-rGRF activity by use of a pituitary culture assay system that can detect growth hormone-releasing factor in the femtomole range. Such highly sensitive in vitro techniques permit the use of picomole quantities of an antigen in partially purified preparations for the isolation of monoclonal antibodies, which can in turn be used in biological studies and in immunochemical procedures for large-scale purification and isolation of that antigen.
Neuromuscular Patterns and the Origin of Trophic Specialization in Fishes
Authors: Lauder George V.
Published: October 2006

The pattern of muscle electrical activity in the pharyngeal muscles of the mollusc-eating sunfish
Lepomis microlophus
is highly specialized in comparison with the pattern displayed by most other members of the sunfish family and does not change when different prey are eaten. The closest genealogical relative of this species has the specialized muscle activity pattern for crushing prey when it feeds on snails but uses the primitive sequence of muscle activity during swallowing of other prey. The ability of species that crush snails to use molluscan prey effectively is due primarily to the evolutionary transformation of the neuromuscular program controlling the trophic apparatus.
Nicotinic Cholinergic Receptor Binding Sites in the Brain: Regulation in Vivo
Authors: Schwartz Rochelle D. , Kellar Kenneth J.
Published: October 2006

Tritiated acetylcholine was used to measure binding sites with characteristics of nicotinic cholinergic receptors in rat brain. Regulation of the binding sites in vivo was examined by administering two drugs that stimulate nicotinic receptors directly or indirectly. After 10 days of exposure to the cholinesterase inhibitor diisopropyl fluorophosphate, binding of tritiated acetylcholine in the cerebral cortex was decreased. However, after repeated administration of nicotine for 10 days, binding of tritiated acetylcholine in the cortex was increased. Saturation analysis of tritiated acetylcholine binding in the cortices of rats treated with diisopropyl fluorophosphate or nicotine indicated that the number of binding sites decreased and increased, respectively, while the affinity of the sites was unaltered.
Electron Microscope Tomography: Transcription in Three Dimensions
Authors: Olins Donald E. , Olins Ada L. , Levy Henri A. , Durfee Richard C. , Margle Stephen M. , Tinnel Ed P. , Dover S. David
Published: October 2006

Three-dimensional reconstruction of an asymmetric biological ultrastructure has been achieved by tomographic analysis of electron micrographs of sections tilted on a goniometer specimen stage. Aligned micrographs could be displayed as red-green three-dimensional movies. The techniques have been applied to portions of in situ transcription units of a Balbiani ring in the polytene chromosomes of the midge
Chironomus tentans
. Current data suggest a DNA compaction of about 8 to 1 in a transcription unit. Nascent ribonucleoprotein granules display an imperfect sixfold helical arrangement around the chromatin axis.
On the Nature of Intelligence
Authors: Hunt Earl
Published: October 2006

Our concept of intelligence has been heavily influenced by the development of intelligence tests as screening devices in education and personnel selection. An alternative approach is to begin with a theory of the process of cognition and identify those aspects of individual mental performance that should be important on theoretical grounds. Three classes of performance have been identified. These deal with a person's choice of an internal representation for a problem, strategies for manipulating the representation, and abilities to execute elementary information processing steps required by the strategy.
Isolation of lAmellar Bodies from Neonatal Mouse Epidermis by Selective Sequential Filtration
Authors: Grayson Stephen , Johnson-Winegar Anna D. , Elias Peter M.
Published: October 2006

Isolation of epidermal lamellar bodies has presented a challenge because pressures required to homogenize keratinocytes can destroy these organelles and because the lamellar body readily releases its contents during prolonged isolation procedures. In an attempt to isolate lamellar bodies, sheets of intact stratum corneum and stratum granulosum were obtained from neonatal mice with highly purified staphylococcal epidermolytic toxin, disrupted, and passed through a series of filters. The final filtrate was rich in intact lamellar bodies and contained variable amounts of ribosomes and other vesicular structures. Availability of a highly purified lamellar body preparation from postnatal epidermis should help to clarify the role of this organelle in epidermal function. The technique of selective, sequential filtration represents a new approach to cell fractionation that may have wide applications in cell biology and biochemistry.
Lecithin Consumption Increases Acetylcholine Concentrations in Rat Brain and Adrenal Gland
Authors: Hirsch Madelyn J. , Wurtman Richard J.
Published: October 2006

Consumption of a single meal containing lecithin, the major source of choline occurring naturally in the diet, increased the concentrations of choline and acetylcholine in rat brain and adrenal gland. Hence, the concentration of acetylcholine in the tissues may normally be under direct, short-term nutritional control.
Mouse Leukemia: Therapy with Monoclonal Antibodies Against a Thymus Differentiation Antigen
Authors: Bernstein Irwin D. , Tam Milton R. , Nowinski Robert C.
Published: October 2006

Monoclonal antibodies against a thymus cell differentiation antigen (Thy-1.1) were effective in the therapy of a transplanted mouse leukemia. Passive immunization resulted in high titers of cytotoxic antibody in the serum of treated mice and the suppression of metastatic tumor cells. The tumor-suppressive effects of the monoclonal antibodies were amplified by the administration of exogenous complement. This combined antibody and complement therapy resulted in the cure of leukemia in a significant proportion of the treated animals.
Rapid Eye Movement Sleep PGO-Type Waves Are Present in the Dorsal Pons of the Albino Rat
Authors: Farber Jorge , Marks Gerald A. , Roffwarg Howard P.
Published: October 2006

We have found rapid eye movement sleep central phasic activity in the form of episodic, repetitive, monophasic waves in the albino rat. This activity is recorded in discrete areas of the dorso-lateral pons, including the nucleus locus ceruleus. The vast majority of these waves occur during rapid eye movement sleep. Their distribution and electrophysiological characteristics are similar to those of ponto-geniculo-occipital waves in the cat.
Ethanol in Low Doses Augments Calcium-Mediated Mechanisms Measured Intracellularly in Hippocampal Neurons
Authors: Carlen Peter L. , Gurevich Nataly , Durand Dominique
Published: October 2006

The electrophysiological effects of ethanol in low doses (5 to 20 millimoles per liter or 23 to 92 milligrams per 100 milliliters) were examined intracellularly in CA1 cells of rat hippocampus in vitro. Inhibitory and excitatory postsynaptic potentials were increased when ethanol was applied to the respective synaptic terminal regions. Postsynaptically, ethanol caused a moderate hyperpolarization with increased membrane conductance, even when synaptic transmission was blocked. Ethanol augmented the hyperpolarization that followed repetitive firing or that followed the eliciting of calcium spikes in the presence of tetrodotoxin, but not the rapid afterhyperpolarization in calcium-free medium. Ethanol appears to augment calcium-mediated mechanisms both pre- and postsynaptically.
Identification of a BALB/c H-2L
d
Gene by DNA-Mediated Gene Transfer
Authors: Goodenow Robert S. , McMillan Minnie , Örn Anders , Nicolson Margery , Davidson Norman , Frelinger Jeffrey A. , Hood Leroy
Published: October 2006

Gene transfer and immunoselection were used in the identification of a BALB/c genomic clone containing an H-2L
d
gene (clone 27.5). Transformation of thymidine kinase-negative C3H mouse L cells with the cloned 27.5 DNA together with the herpes simplex virus tk gene produced transformants expressing L
d
molecules detected by radioimmune assay with monoclonal hybridoma antibodies to L
d
antigens. The foreign L
d
gene products expressed by cloned mouse L cell transformants were shown to be virtually indistinguishable from BALB/c spleen L
d
molecules by two-dimensional electrophoretic analysis of H-2L
d
immunoprecipitates. These results indicate that the genomic clone 27.5 contains a functional BALB/c H-2L
d
gene and demonstrate the usefulness of this approach for identifying the gene products encoded by cloned genes which are members of a multigene family. Furthermore, the ability to place cell-surface recognition molecules on the surfaces of foreign cells provides a powerful opportunity for functional analyses of these molecules.
Congenital Malformations Induced by Laetrile
Authors: Willhite Calvin C.
Published: October 2006

Laetrile administered orally to pregnant hamsters caused skeletal malformations in the offspring, but intravenous laetrile failed to result in embryopathic effects. Oral laetrile significantly increased in situ cyanide concentrations, while intravenous laetrile did not. Thiosulfate administration protected embryos from the teratogenic effects of oral laetrile. The embryopathic effects of oral laetrile appear to be due to cyanide released by bacterial β-glucosidase activity.
A Brain Heater in the Swordfish
Authors: Carey Francis G.
Published: October 2006

The brain and eye of swordfish are warmer than the water. Associated with one of the eye muscles is a tissue that heats the brain. This brain heater is rich in mitochondria and cytochrome c and is supplied with blood through a vascular heat exchanger. It protects the central nervous system from rapid cooling during daily vertical excursions which may take the swordfish through a wide temperature range.
Presence of Coelomocytes in the Primitive Chordate Amphioxus (
Branchiostoma lanceolatum
)
Authors: Rhodes Christopher P. , Ratcliffe Norman A. , Rowley Andrew F.
Published: October 2006

Previously undescribed free and fixed cells in the coelomic cavity of
Branchiostoma lanceolatum
respond immunologically to particulate antigens. This species is thus an important model for future investigations of the phylogeny of the immune system.
Hemispheric Asymmetries in the Behavioral and Hormonal Effects of Sexually Differentiating Mammalian Brain
Authors: Nordeen E. J. , Yahr Pauline
Published: October 2006

Estrogen pellets were placed in either the right or left hypothalamus of newborn female rats so that only one side of this brain area was exposed to the postnatal masculinizing and defeminizing effects of the hormone. The effects of estrogen on gonadotropin secretion and reproductive behavior depended on both the region and the side of implantation. Exposure of the left hypothalamus to estrogen resulted in defeminized development. Exposure of the right hypothalamus to estrogen resulted in masculinized development. Thus the response of the developing hypothalamus to gonadal steroids may be asymmetric.
Variable Ultrasound Echogenicity in Flowing Blood
Authors: Sigel Bernard , Machi Junji , Beitler Julio C. , Justin Jeffery R. , Coelho Julio C. U.
Published: October 2006

Real-time ultrasound imaging of large abdominal veins revealed bloodstream echogenicity of variable intensity. This variability is largely due to the entrance and persistance of tributary blood currents that show different echogenicity. Red cell aggregation is probably an important cause of bloodstream echoes and their variable intensity.
Microbial Competition
Authors: Fredrickson A. G. , Stephanopoulos Gregory
Published: October 2006

Populations of microorganisms inhabiting a common environment compete for nutrients and other resources of the environment. In some cases, the populations even excrete into the environment chemicals that are toxic or inhibitory to their competitors. Competition between two populations tends to eliminate one of the populations from their common habitat, especially when competition is focused on a single resource and when the populations do not otherwise interact. However, a number of factors mitigate the severity of competition and thus competitors often coexist.
Reduction of the Isoproterenol-Induced Alterations in Cardiac Adenine Nucleotides and Morphology by Ribose
Authors: Zimmer H.-G. , Ibel H. , Steinkopff G. , Korb G.
Published: October 2006

Continuous intravenous infusion of ribose (200 milligrams per kilogram per hour) for 24 hours induced a marked stimulation of cardiac adenine nucleotide biosynthesis in unanesthetized and unrestrained rats that had been treated with isoproterenol subcutaneously (25 milligrams per kilogram). The diminution of adenine nucleotides characteristic for the action of high doses of isoproterenol was entirely prevented, and the incidence of the isoproterenol-induced myocardial cell damage was significantly reduced when ribose was administered. These results support the view that depletion of adenine nucleotides is involved in the development of cardiac necrosis.
Asymmetrically Permeable Membrane Channels in Cell Junction
Authors: Flagg-Newton J. L. , Loewenstein W. R.
Published: October 2006

Asymmetric membrane junctions were formed in culture by pairing two cell types which, in their respective homologous junctions, have cell-cell channels of different permselectivities. The channels in the asymmetric junction, presumably made of unequal channel precursors, displayed directional permselectivity; fluorescent labeled glutamic acid (700 daltons), but not smaller and less polar permeant molecules, traversed the junction more readily in one direction than in the other. The favored direction was the one where the permeant passed first through the cell membrane that would have the less restrictive channels in a homologous junction. This directional selectivity requires no electric field across the junction and is thus distinct from a rectifying junction. The physiological potential of such directional molecular sieving for partitioning communication between tissue cells of different function and developmental fate are discussed.
Interaction of Laminae of the Cingulate Cortex with the Anteroventral Thalamus During Behavioral Learning
Authors: Gabriel Michael , Foster Kent , Orona Edward
Published: October 2006

Neurons in deep laminae of the rabbit cingulate cortex develop discriminative activity at an early stage of behavioral discrimination learning, whereas neurons in the anteroventral nucleus of thalamus and neurons in the superficial cortical laminae develop such activity in a late stage of behavioral learning. It is hypothesized that early-forming discriminative neuronal activity, relayed to anteroventral neurons via the corticothalamic pathway, contributes to the construction of changes underlying the late-forming neuronal discrimination in the anteroventral nucleus. The resultant late discriminative activity in the anteroventral nucleus is then relayed via the thalamocortical pathway back to the superficial cortical laminae, promoting disengagement of cortex from further task-processing.
Electrical Activity in an Exocrine Gland: Optical Recording with a Potentiometric Dye
Authors: Senseman D. M. , Salzberg B. M.
Published: October 2006

Propagated action potentials in the salivary gland of a freshwater snail were detected by optical means. Voltage-dependent absorption changes from acinar cells stained with a merocyanine-oxazolone dye faithfully reproduced the time course of electrical activity in this tissue. Such signals may provide a useful tool for the study of endocrine tissue as well.
Genetics and the Origin of a Vector Population:
Aedes aegypti
, a Case Study
Authors: Powell Jeffrey R. , Tabachnick Walter J. , Arnold Jonathan
Published: October 2006

Thirty-four population samples representing the worldwide distribution of the mosquito
Aedes aegypti
were analyzed for variation at 19 to 22 enzyme-coding genes. A multivariate discriminant analysis revealed that the genetic differences among populations in six geographic regions and between two subspecies enable one to determine the regional origin of a population. Such studies of population genetics may have quite general applicability in studying vector-borne diseases.
Genes for Growth Hormone, Chorionic Somatomammotropin, and Growth Hormone-Like Gene on Chromosome 17 in Humans
Authors: Owerbach David , Rutter William J. , Martial Joseph A. , Baxter John D. , Shows Thomas B.
Published: October 2006

The human genes for growth hormone (
GH
), chorionic somatomammotropin (
CSH
), and a third growth hormone-like gene (
GHL
) have been located on chromosome 17 in humans. DNA fragments of 2.6, 2.8, and 9.5 kilobase pairs containing
GH
,
CSH
, and
GHL
, respectively, were identified in human genomic DNA, and a 7.5-kilobase DNA fragment related to growth hormone DNA sequences was found in mouse cells. In somatic hybrids of human and mouse cells containing reduced numbers of human chromosomes, but a normal complement of mouse chromosomes, the mouse 7.5-kilobase DNA fragment was always present, whereas the 2.6-, 2.8-, and 9.5-kilobase human fragments were present only when human chromosome 17 was also present.
Acetylcholine Synthesis by Displaced Amacrine Cells
Authors: Hayden Shawn A. , Mills John W. , Masland Richard M.
Published: October 2006

The ganglion cell layer of the rabbit retina contains neurons that synthesize acetylcholine. To identify these neurons, the ganglion cells were labeled by retrograde transport of a fluorescent dye, and the acetylcholine-synthesizing cells of the same retinas were labeled by exposing the tissue to tritiated choline. Autoradiographs inspected by fluorescence microscopy showed that tritiated acetylcholine and the dye accumulated in different cells. Optic nerves of other animals were sectioned, causing degeneration of many neurons of the ganglion cell layer. This loss affected neither the retina's overall rate of acetylcholine synthesis nor the number of acetylcholine-containing cells in the ganglion cell layer. The acetylcholine-synthesizing neurons thus appear to be displaced amacrine cells.
Left-Handed Double Helical DNA: Variations in the Backbone Conformation
Authors: Wang Andrew H.-J. , Quigley Gary J. , Kolpak Francis J. , van der Marel Gus , van Boom Jacques H. , Rich Alexander
Published: October 2006

Four different crystals of d(CpGpCpGpCpG) have been solved by x-ray diffraction analysis and all form similar left-handed double helical Z-DNA molecules in the crystal lattice. Two different conformations are observed for the phosphates in the GpC sequences, as the phosphates are found either facing the helical groove or rotated away from it. The latter conformation is often found when hydrated magnesium ions are complexed to a phosphate oxygen atom. These different conformations may be used when right-handed B-DNA joins left-handed Z-DNA. Atomic coordinates and torsion angles are presented for both types of Z-DNA.
Prenatal Exposure to Ethanol Alters the Organization of Hippocampal Mossy Fibers in Rats
Authors: West James R. , Hodges Cheryl A. , Black Asa C.
Published: October 2006

Rats exposed to ethanol throughout their gestation were found to have abnormally distributed mossy fibers in temporal regions of the hippocampus. This demonstrates that prenatal exposure to ethanol causes alterations in neuronal circuitry that persist to maturity. Such defects may play a role in the mental retardation often observed in children with fetal alcohol syndrome.
In Vivo Gene Therapy of Hemophilia B: Sustained Partial Correction in Factor IX-Deficient Dogs
Authors: Kay Mark A. , Rothenberg Steven , Landen Charles N. , Bellinger Dwight A. , Leland Frances , Toman Carol , Finegold Milton , Thompson Arthur R. , Read M. S. , Brinkhous Kenneth M. , Woo Savio L. C.
Published: October 2006

The liver represents a model organ for gene therapy. A method has been developed for hepatic gene transfer in vivo by the direct infusion of recombinant retroviral vectors into the portal vasculature, which results in the persistent expression of exogenous genes. To determine if these technologies are applicable for the treatment of hemophilia B patients, preclinical efficacy studies were done in a hemophilia B dog model. When the canine factor IX complementary DNA was transduced directly into the hepatocytes of affected dogs in vivo, the animals constitutively expressed low levels of canine factor IX for more than 5 months. Persistent expression of the clotting factor resulted in reductions of whole blood clotting and partial thromboplastin times of the treated animals. Thus, long-term treatment of hemophilia B patients may be feasible by direct hepatic gene therapy in vivo.
Mammalian Locomotor-Respiratory Integration: Implications for Diaphragmatic and Pulmonary Design
Authors: Bramble Dennis M. , Jenkins Farish A.
Published: October 2006

Diaphragmatic function and intrapulmonary respiratory flow in running mammals were found to differ substantially from the corresponding conditions known in resting mammals. In trotting dogs, orbital oscillations of the diaphragm were driven by inertial displacements of the viscera induced by locomotion. In turn, oscillations of the visceral mass drove pulmonary ventilation independent of diaphragmatic contractions, which primarily served to modulate visceral kinetics. Visceral displacements and loading of the anterior chest wall by the forelimbs are among the factors that contribute to an asynchronous ventilation of the lungs and interlobar gas recycling. Basic features of mammalian respiratory design, including the structure of the diaphragm and lobation of the lungs, appear to reflect the mechanical requirements of locomotor-respiratory integration.
Receptive Field Reorganization in Dorsal Column Nuclei During Temporary Denervation
Authors: Pettit Michael J. , Schwark Harris D.
Published: October 2006

Altered sensory input can result in the reorganization of somatosensory maps in the cerebral cortex and thalamus, but the extent to which reorganization occurs at lower levels of the somatosensory system is unknown. In cat dorsal column nuclei (DCN), the injection of local anesthetic into the receptive fields of DCN neurons resulted in the emergence of a new receptive field in all 13 neurons studied. New receptive fields emerged rapidly (within minutes), sometimes accompanied by changes in adaptation rates and stimulus selectivity, suggesting that the new fields arose from the unmasking of previously ineffective inputs. Receptive field reorganization was not imposed by descending cortical inputs to the DCN, because comparable results were obtained in 10 additional cells when the somatosensory and motor cortex were removed before recording. These results suggest that mechanisms underlying somatotopic reorganization exist at the earliest stages of somatosensory processing. Such mechanisms may participate in adaptive responses of the nervous system to injury or continuously changing sensory stimulation.
Synthesis and Degradation of Cyclic ADP-Ribose by NAD Glycohydrolases
Authors: Kim Hyuntae , Jacobson Elaine L. , Jacobson Myron K.
Published: October 2006

Cyclic adenosine diphosphoribose (cADPR), a recently discovered metabolite of nicotinamide adenine dinucleotide (NAD), is a potent calcium-releasing agent postulated to be a new second messenger. An enzyme that catalyzes the synthesis of cADPR from NAD and the hydrolysis of cADPR to ADP-ribose (ADPR) was purified to homogeneity from canine spleen microsomes. The net conversion of NAD to ADPR categorizes this enzyme as an NAD glycohydrolase. NAD glycohydrolases are ubiquitous membrane-bound enzymes that have been known for many years but whose function has not been identified. The results presented here suggest that these enzymes may function in the regulation of calcium homeostasis by the ability to synthesize and degrade cADPR.
Vision in Insects: Pathways Possibly Underlying Neural Adaptation and Lateral Inhibition
Authors: Strausfeld N. J. , Campos-Ortega J. A.
Published: October 2006

Like horizontal cells in vertebrate retinas, horizontal amacrine cells beneath the insect eye intervene between receptors and interneurons at the first level of synapses. Synaptic arrangements between amacrines and interneurons that give rise to regular networks of axon collaterals may explain recent electrophysiological observations of lateral inhibition beneath the insect retina. Neural adaptation mechanisms acting on single retinotopic channels or assemblies of channels can also be referred to reciprocal relationships between receptors and first-order interneurons as well as to centrifugal cells from levels of so-called photopic receptor endings.
A High-Temperature Superconducting Receiver for Nuclear Magnetic Resonance Microscopy
Authors: Black R. D. , Early T. A. , Roemer P. B. , Mueller O. M. , Mogro-Campero A. , Turner L. G. , Johnson G. A.
Published: October 2006

A high-temperature superconducting-receiver system for use in nuclear magnetic resonance (NMR) microscopy is described. The scaling behavior of sources of sample and receiver-coil noise is analyzed, and it is demonstrated that Johnson, or thermal, noise in the receiver coil is the factor that limits resolution. The behavior of superconductors in the environment of an NMR experiment is examined, and a prototypical system for imaging biological specimens is discussed. Preliminary spin-echo images are shown, and the ultimate limits of the signal-to-noise ratio of the probe are investigated.
Translocation of TCRα Chains into the Lumen of the Endoplasmic Reticulum and Their Degradation
Authors: Shin Jaekyoon , Lee Songjae , Strominger Jack L.
Published: October 2006

After synthesis, the α chain of the T cell antigen receptor (TCRα) can form a complex with other TCR chains and move to the cell surface, or TCRα can undergo degradation in the endoplasmic reticulum (ER) if it remains unassembled. The mechanism of translocation and degradation in the ER is unclear. It was found that the putative transmembrane region of TCRα (α
tm
) was incompetent on its own to act as a transmembrane region. Molecules that contained α
tm
were translocated into the ER lumen and then underwent either rapid degradation or secretion, depending on the sequence of the cytoplasmic domain. A specific signal for ER degradation within α
tm
does not appear to be present.
Mouse Chromosome Translocations: Visualization and Analysis by Electron Microscopy of the Synaptonemal Complex
Authors: Moses Montrose J. , Russell Liane B. , Cacheiro N. L. A.
Published: October 2006

Pachytene chromosomes of mice heterozygous for known translocations are clearly depicted by configurations of the synaptonemal complexes in spread (whole mount) preparations. In one autosomal and two X-autosome translocations analyzed, breakpoints are identifiable; localization by measurement agrees with mitotic data and shows the translocations to be reciprocal. Synapsis with the Y is inhibited in one translocation in which the breakpoint is in the pairing region of the X.
L-Dopa: Selective Toxicity for Melanoma Cells in Vitro
Authors: Wick Michael M. , Byers Lisken , Frei Emil
Published: October 2006

In a study of the effect of L-dopa, an intermediate in the biosynthesis of the pigment melanin, on the growth of human and murine melanoma cells a highly selective inhibition of growth was observed for pigmented cell lines (S91A and human melanoma) as compared to the nonpigmented control cells (amelanotic melanoma S91B, mouse fibroblast L929, and Chinese hamster ovary). There was a correlation between toxicity and the extent of incorporation of radioactively labeled L-dopa by each line.
Quantitation of Cytoplasmic Tubulin by Radioimmunoassay
Authors: Morgan Janet L. , Rodkey L. Scott , Spooner Brian S.
Published: October 2006

A radioimmunoassay has been developed for the quantitation of cytoplasmic tubulin. It measures tubulin between 20 and 1500 nanograms and does so independently of decay in colchicine-binding activity. In addition, the state of tubulin as subunit or polymer does not alter the measurement.
Cerebral Lateralization of Haptic Perception: Interaction of Responses to Braille and Music Reveals a Functional Basis
Authors: Smith Myra Okazaki , Chu Jennifer , Edmonston William E.
Published: October 2006

Normally, haptic perception of the left hand surpasses that of the right. But simultaneously playing music into the left (but not the right) ear reverses this superiority. This suggests that the left cerebral hemisphere has full haptic perceptual capability, which is subject to right hemisphere interference unless the latter's attentional mechanisms are engaged by contralateral peripheral stimulation.
Brain Self-Stimulation: Direct Evidence for the Involvement of Dopamine in the Prefrontal Cortex
Authors: Mora F. , Myers R. D.
Published: October 2006

Rats were trained to self-stimulate the medial prefrontal cortex, a region rich in dopaminergic terminals. After the region adjacent to the electrode site was labeled with [
14
C]dopamine, it was perfused repeatedly by means of push-pull cannulas. Electrical stimulation of this cortical area in six animals enhanced the release of dopamine and its associated metabolites in nine of 16 experiments. Thus in vivo evidence is provided that dopamine is involved in the brain self-stimulation mechanism within the frontal cortex.
Vitamin K
Authors: Doisy E. A. , Binkley S. B. , Thayer S. A. , McKee R. W.
Published: October 2006

During the decade following Dam's first observations on the hemorrhagic syndrome the combined efforts of several groups of investigators have solved many of the important problems connected with the new vitamin. Sources of vitamin K were discovered, methods of extraction and purification devised, the isolation effected, the structure of K
1
worked out and then verified by synthesis, and a promising start made on the therapeutic applications. In addition, simple water soluble compounds with antihemorrhagic properties have been supplied for clinical work. Preliminary results with these compounds are encouraging.
Receptive Fields of Auditory Neurons in the Owl
Authors: Knudsen Eric I. , Konishi Masakazu , Pettigrew John D.
Published: October 2006

The influence of sound location on the responses of auditory neurons in the forebrain of the owl (
Tyto alba
) was studied directly by using a remotely controlled, movable sound source under free-field, anechoic conditions. Some auditory neurons demonstrated well-defined receptive fields that were (i) restricted both in elevation and in azimuth and (ii) relatively independent of the intensity and the nature of the sound stimulus. The majority of the fields were located frontally and contralateral to the recording site.
Chromosomal Subunits in Active Genes Have an Altered Conformation
Authors: Weintraub Harold , Groudine Mark
Published: October 2006

Ten percent digestion of isolated nuclei by pancreatic deoxyribonuclease I preferentially removes globin DNA sequences from nuclei obtained from chick red blood cells but not from nuclei obtained from fibroblasts, from brain, or from a population of red blood cell precursors. Moreover, the nontranscribed ovalbumin sequences in nuclei isolated from red blood cells and fibroblasts are retained after mild deoxyribonuclease I digestion. This suggests that active genes are preferentially digested by deoxyribonuclease I. In contrast, treatment of red cell nuclei with staphylococcal nuclease results in no preferential digestion of active globin genes. When the 11
S
monomers obtained after staphylococcal nuclease digestion of nuclei are then digested with deoxyribonuclease I, the active globin genes are again preferentially digested. The results indicate that active genes are probably associated with histones in a subunit conformation in which the associated DNA is particularly sensitive to digestion by deoxyribonuclease I.
H-Y Male Antigen: Detection on Eight-Cell Mouse Embryos
Authors: Krco Christopher J. , Goldberg Ellen H.
Published: October 2006

The H-Y (male) antigen is expressed on 50 percent of eight-cell embryos (2 days old) of the mouse, strain C57BL/6. This work provides additional evidence that H-Y expression is not dependent on male differentiation.
Choice Behavior in Rhesus Monkeys: Cocaine Versus Food
Authors: Aigner Thomas G. , Balster Robert L.
Published: October 2006

Rhesus monkeys were allowed to choose between intravenous injections of cocaine and food reinforcement for lever pressing. A choice trial was available every 15 minutes continuously for 8 days. The animals chose cocaine almost exclusively, which resulted in high cocaine intake, decreased food intake, weight loss, and marked behavioral toxicity. The study provides evidence of the reinforcing efficacy of cocaine.
Hydroxymethyluracil in Eukaryote DNA: A Natural Feature of the Pyrrophyta (Dinoflagellates)
Authors: Rae Peter M. M.
Published: October 2006

Analysis of the DNA of several diverse dinoflagellates and other algae has revealed that the presence of the base hydroxymethyluracil (HOMeU) is a feature common among the DNA's of dinoflagellates; this base has not been found in any other group of eukaryotes that has been examined. Among examined members of the dinoflagellates, the ratio of the base pairs HOMeU⋅A to T⋅A, where A is adenine and T is thymine, ranges from 0.14 to 2.13. In addition to hydroxymethyluracil, the DNA of one dinoflagellate contains methylcytosine, and that of another contains methyladenine, while the DNA of other dinoflagellates contains no detectable amounts of either of these two bases.
Productivity of Ospreys in Connecticut—Long Island Increases as DDE Residues Decline
Authors: Spitzer Paul R. , Risebrough Robert W. , Walker Wayman , Hernandez Robert , Poole Alan , Puleston Dennis , Nisbet Ian C. T.
Published: October 2006

Nesting success of ospreys (Pandion haliaetus) breeding in the Connecticut—Long Island area has increased since 1973 and is now approaching the levels recorded prior to the 1950's. Simultaneously, DDE and dieldrin residues have declined in unhatched eggs. Levels of polychorinated biphenyls have shown no changes over the period 1969 to 1976. The increase in productivity is attributed primarily to lower levels of DDE contamination. Detrimental effects in the past on ospreys in the Connecticut River estuary are attributed to local contamination with dieldrin.
Determining the intensity and energy expenditure during commuter cycling
Authors: de Geus B , De Smet S , Nijs J , Meeusen R
Published: October 2006

Objectives:To determine the intensity and energy expenditure during commuter cycling, and to investigate whether cycling to work at a self-chosen intensity corresponds to recommendations of the Centers for Disease Control and Prevention (CDC) and American College of Sports Medicine (ACSM) for health improvement and ACSM recommendations for fitness improvement.

Methods:18 healthy, untrained middle-aged people, who did not cycle to work, underwent two maximal exercise tests (MT and MT2) in order to measure their maximal heart rate and oxygen consumption (VO2). MT2 was performed 24 weeks after MT. Participants were asked to cycle at least three times a week to their workplace over a one-way minimum distance of 2 km. Data on cycling were recorded in a diary. 12 weeks after MT, a field test was conducted, where participants had to cycle to or from their workplace. The same measurements were taken as during MT as markers of exercise intensity. Metabolic equivalents (METs) and energy expenditure were calculated.

Results:The intensity during the field test was >75% of their maximal aerobic capacity. The mean (SD) MET value was 6.8 (1.9). The energy expenditure during the field test was 220 (115) kcal or 540 (139) kcal/h and 1539 (892) kcal/week. Men consumed significantly (p<0.01) more energy per hour than women.

Conclusion:Commuter cycling at a self-selected intensity meets the CDC and ACSM recommendations for health improvement and the ACSM recommendations for improvement of cardiorespiratory fitness. However, as the participants cycled faster during the field test than during daily cycling, the results should be interpreted with caution.