bluuebunny/crossref_metadata_2025 huggingface dataset:
Gut Reactions of Radioactive Nitrite After Intratracheal Administration in Mice
Authors: Thayer James R. , Chasko Joseph H. , Swartz Laura A. , Parks Norris J.
Published: October 2006

Intratracheal administration to mice of radioactive nitrite labeled with nitrogen-13 (
13
NO
2
-
) (half-life, 9.96 minutes) in dosages that do not cause pharmacological perturbation reveals that oxidative and reductive reactions occur in different organs. Oxidation of
13
NO
2
-
to radioactive nitrate (
13
NO
3
-
) predominates in the blood and liver. Reduction of
13
NO
2
-
occurs in those mice that harbor intestinal microflora; this reduction does not occur in germ-free mice. The intestinal reduction products include ammonium, glutamate, glutamine, and urea. With a detection limit of about 0.01 percent of the instilled nitrogen-13, no labeled nitrosamines were detected within 30 minutes. Reduced nitrogen-13 is transported out of the intestine into the circulatory system and appears in the urine along with
13
NO
3
-
. The biological half-period for
13
NO
2
-
destruction is about 7 minutes, and both oxidation and reduction products are formed.
Cardiovascular Actions of Cadmium at Environmental Exposure Levels
Authors: Kopp Stephen J. , Glonek Thomas , Perry H. Mitchell , Erlanger Margaret , Perry Elizabeth F.
Published: October 2006

A low intake of dietary cadmium induces specific dose-dependent functional and biochemical changes in the cardiovascular tissues of rats. Maximum changes occur when the cadmium intake is 10 to 20 micrograms per kilogram of body weight per day. The changes reflect the accumulation of "critical" concentrations of cadmium in the cardiovascular tissues. The biologic activity of cadmium is demonstrated for intakes that approach those of the average American adult exposed to the usual environmental concentrations of the element but not to industrial concentrations. The sensitivity of the cardiovascular system to low doses of cadmium could not be anticipated by extrapolation from data on exposure to high concentrations of cadmium. The data support the hypothesis that ingested or inhaled environmental cadmium may contribute to essential hypertension in humans.
Binding of Nenzo[
a
]pyrene 7,8-Diol-9,10-Epoxides to DNA, RNA, and Protein of Mouse Skin Occurs with High Stereoselectivity
Authors: Koreeda Masato , Moore Patrick D. , Wislocki Peter G. , Levin Wayne , Conney Allan H. , Yagi Haruhiko , Jerina Donald M.
Published: October 2006

The formation, stereostructure, and cellular reactions of the 7,8-diol-9,10-epoxide metabolites of the carcinogen benzo[
a
]pyrene have been examined after topical application of benzo[
a
]pyrene to the skin of mice. In this known target tissue, polymer adducts from diastereomeric diol epoxides, (+)-(7
S
, 8
R
, 9
R
, 10
R
) and (+)-(7
R
, 8
S
, 9
R
, 10
R
), were formed stereospecifically from their corresponding 7,8-dihydrodiols. Both diol epoxides bind with proteins, RNA, and DNA in vivo. For the nucleic acids, binding occurs preferentially at the 2-amino group of guanine in cellular RNA and DNA in vivo. Methods for establishing the structure of the cellular adducts as well as the possible biological implications of their formation are discussed.
Mammalian Gonadal Determination and Gametogenesis
Authors: Gordon Jon W. , Ruddle Frank H.
Published: October 2006

Although a relationship between the X and Y chromosomes and mammalian sexual development has long been recognized, a detailed understanding of this relation is still lacking. Recent advances in somatic cell genetics and recombinant DNA technology should provide the tools for solving this fundamental problem in developmental genetics.
Chemical Modification of Carotid Body Chemoreception by Sulfhydryls
Authors: Lahiri Sukhamay
Published: October 2006

Sulfhydryl reagents cause striking augmentation of the chemoreceptor responses of the carotid body to hypoxia. This indicates that a cellular plasma membrane protein with a reactive sulfhydryl group is a constituent part of the chemoreceptor architecture and provides a means of identification, localization, and isolation of the protein.
Viral Epitopes and Monoclonal Antibodies: Isolation of Blocking Antibodies That Inhibit Virus Neutralization
Authors: Massey Richard J. , Schochetman Gerald
Published: October 2006

The inability of pathogenic animal viruses to be completely neutralized by antibodies can lead to chronic viral infections in which infectious virus persists even in the presence of excess neutralizing antibody. A mechanism that results in this nonneutralized fraction of virus was defined by the topographical relationships of viral epitopes identified with monoclonal antibodies wherein monoclonal antibodies bind to virus and sterically block the binding of neutralizing antibodies.
Opiate Receptor Distribution in the Cerebral Cortex of the Rhesus Monkey
Authors: Wise Steven P. , Herkenham Miles
Published: October 2006

The distribution of opiate receptors in the cerebral cortex of the rhesus monkey (
Macaca mulatta
) was determined by autoradiographic visualization of [
3
H]naloxone binding to tissue sections. Naloxone was bound in relatively large amounts to the cortical laminae containing the cell bodies of output neurons, to a varying set of additional laminae in different cortical fields, to fields closer to more primitive types of cortex, and to polysensory cortical fields. From these laminar and areal variations in distribution, it appears that opiate receptors play a role in specific aspects of cortical function.
Insertion Sequence Duplication in Transpositional Recombination
Authors: Weinert Ted A. , Schaus Nancy A. , Grindley Nigel D. F.
Published: October 2006

Insertion sequences (IS) are discrete segments of DNA that can transpose from one genomic site to another and promote genetic rearrangements. A question that is central to understanding the mechanism of transpositional recombination is whether genetic rearrangements are accompanied by duplication of the IS that promotes them. Analysis of adjacent deletions mediated by IS
903
provides the strongest evidence to date than any IS-mediated transpositional recombination can occur by an efficient replicative mechanism.
A Serological Test for Leprosy with a Glycolipid Specific for
Mycobacterium leprae
Authors: Young Douglas B. , Buchanan Thomas M.
Published: October 2006

A phenolic glycolipid from
Mycobacterium leprae
was purified and used as antigen in an enzyme-linked immunosorbent assay. Antibodies directed against the lipid were seen in serums from leprosy patients but not in serums from uninfected controls or patients infected with other mycobacteria, including
Mycobacterium tuberculosis
. The antibody response distinguished between the
Mycobacterium leprae
lipid and the structurally related phenolic glycolipid from
Mycobacterium kansasii
. This assay has considerable potential as a specific serodiagnostic test for leprosy infection.
Mass Spectrometry: Analytical Capabilities and Potentials
Authors: Cooks R. G. , Busch K. L. , Glish G. L.
Published: October 2006

The mass range of mass spectrometers has been extended by almost an order of magnitude in the past decade, ionization procedures have been introduced which allow ionic, nonvolatile compounds to be examined, and new capabilities have been achieved through the successful integration of separation and analysis techniques. In combination with other techniques, mass spectrometry has been used in biological and environmental research to characterize constituents of mixtures, including those present in trace amounts; in metabolic profiling, where high throughput and large dynamic range are important; and in protein structure determinations. Measurements of stable isotope abundances by mass spectrometry have been used in enzymology, studies of photosynthesis, and carbon dating. Outside the area of chemical analysis, mass spectrometry has been used to study gas-phase acidities and basicities and to study organic reaction mechanisms in the gas phase. Trends in mass spectrometry include multidimensional experiments, use of ionization methods, direct mixture analysis without extensive sample preparation, and the development of advanced instrumentation including an ion trap and an inductively coupled plasma mass spectrometer. It is likely that mass spectrometry will come to be much more widely used and that data will increasingly be other than conventional mass spectra.
Isolation, Structure, and Synthesis of a Human Seminal Plasma Peptide with Inhibin-Like Activity
Authors: Ramasharma K. , Sairam M. R. , Seidah N. G. , Chrétien M. , Manjunath P. , Schiller P. W. , Yamashiro D. , Li Choh Hao
Published: October 2006

A basic peptide isolated from pooled human seminal plasma exhibited inhibin-like activity by suppressing pituitary follicle-stimulating hormone secretion in vitro and in vivo. The peptide has been characterized and sequenced, and a 31-amino-acid synthetic replicate showed full biological activity in vitro.
The Goldfish Ear Codes the Axis of Acoustic Particle Motion in Three Dimensions
Authors: Fay Richard R.
Published: October 2006

Auditory and vestibular nerve fibers of the goldfish are strongly directionally sensitive to whole-body acceleration at audio frequencies. The three-dimensional pattern of sensitivity shows that input from a receptor ensemble (hair cells) is essentially equivalent to that expected from a single hair cell having a given three-dimensional orientation of best sensitivity. Fibers from the sacculus, lagena, and utriculus differ with respect to distributions of directional orientation, but are similar in best threshold (less than 1 nanometer, root mean square, at 140 hertz). In combination with other mechanisms for detection of sound pressure, this directionality is a likely basis for directional hearing in fishes, and it could allow the determination of underwater acoustic intensity.
Spatial Orientation in Weightlessness and Readaptation to Earth's Gravity
Authors: Young Laurence R. , Oman Charles M. , Watt Douglas G. D. , Money Kenneth E. , Lichtenberg Byron K.
Published: October 2006

Unusual vestibular responses to head movements in weightlessness may produce spatial orientation illusions and symptoms of space motion sickness. An integrated set of experiments was performed during Spacelab 1, as well as before and after the flight, to evaluate responses mediated by the otolith organs and semicircular canals. A variety of measurements were used, including eye movements, postural control, perception of orientation, and susceptibility to space sickness.
Kainic Acid Induces Sprouting of Retinal Neurons
Authors: Peichl Leo , Bolz Jürgen
Published: October 2006

The neurotoxin kainic acid caused dose-dependent morphological changes in horizontal cells of the retinas of adult cats and rabbits. High concentrations of kainic acid killed the cells, but when exposed to sublethal doses they contracted their dendritic fields and sent sprouting processes into the inner retina. It appears that kainic acid can induce neuronal growth as well as degeneration and that the potential for morphological plasticity is still present in neurons of the adult mammalian retina.
Innovation and Evaluation
Authors: Mosteller Frederick
Published: October 2006

Social, medical, and technological innovations are discussed, first with reference to historical examples and then with modern studies. I show the need for evaluating both the innovations themselves and the research processes leading to them. I suggest some kinds of research that need to be carried out if we are to continue to have a vigorous program of scientific and technological innovation. Finally, I explain the new initiative by the AAAS in science and engineering education.
Morphological Basis of Long-Term Habituation and Sensitization in
Aplysia
Authors: Bailey Craig H. , Chen Mary
Published: October 2006

The morphological basis of the persistent synaptic plasticity that underlies long-term habituation and sensitization of the gill withdrawal reflex in
Aplysia californica
was explored by examining the fine structure of sensory neuron presynaptic terminals (the critical site of plasticity for the short-term forms of both types of learning) in control animals and in animals whose behavior had been modified by training. The number, size, and vesicle complement of sensory neuron active zones were larger in animals showing long-term sensitization than in control animals and smaller in animals showing long-term habituation. These changes are likely to represent an anatomical substrate for the memory consolidation of these tasks.
Haloperidol-Induced Plasticity of Axon Terminals in Rat Substantia Nigra
Authors: Benes Francine M. , Paskevich Peter A. , Domesick Valerie B.
Published: October 2006

An electron micrographic morphometric analysis of nerve endings in substantia nigra of rats repeatedly treated with haloperidol was performed. Although most parameters showed no difference, drug-treated animals exhibited a significant shift in the distribution of relative numbers of axon terminals, suggesting neuroleptic-induced axon-collateral sprouting.
Burst Discharge in Mammalian Neuroendocrine Cells Involves an Intrinsic Regenerative Mechanism
Authors: Andrew R. David , Dudek F. Edward
Published: October 2006

Intracellular recordings from mammalian neuroendocrine cells showed that steady, injected currents can modify and block periodic spike bursts previously associated with increased neurohormone release. Spike afterpotentials could sum to form plateau potentials, which generated bursts and did not depend on axonal conduction or chemical synapses. Therefore, bursting involves a spike-dependent, positive-feedback mechanism endogenous to single neuroendocrine cells.
Hepatic Glucose Production Oscillates in Synchrony with the Islet Secretory Cycle in Fasting Rhesus Monkeys
Authors: Goodner Charles J. , Hom Frederick G. , Koerker Donna J.
Published: October 2006

Oscillations in the concentration of plasma glucose were found to reflect large fluctuations in hepatic glucose production. The fluctuations in glucose production were synchronous with fluctuations in the concentration of plasma insulin and glucagon. This synchrony suggests that hepatic pathways are entrained to the islet cycle with a minimal time delay.
Sugar and Dental Caries: A Review of Human Studies
Authors: Newbrun Ernest
Published: October 2006

Studies of special population groups, epidemiological surveys, controlled longitudinal studies of humans, and longitudinal studies on the effect of sugar substitutes indicate that frequent or high intake of sugary foods predisposes to dental decay. The relation is not always clear-cut, and most studies have important methodological problems and limitations. Longitudinal measurements of caries increments combined with multiple dietary histories are needed to clarify the association between caries and eating habits. The relative cariogenicity of specific foods can be assessed by a combination of in vitro tests, human in vivo tests, and experimental caries in animals. Human diets, however, vary in food items eaten and the frequency and sequence of eating, and these factors can affect the cariogenicity of a food. Therefore, reported correlations must be interpreted with caution.
In Vitro Reassembly of Squid Brain Intermediate Filaments (Neurofilaments): Purification by Assembly-Disassembly
Authors: Zackroff Robert V. , Goldman Robert D.
Published: October 2006

Intermediate filaments from squid brain tissue were reassembled in vitro and purified by two cycles of assembly and disassembly. Purified squid brain filaments contained one major polypeptide (60,000 daltons), which constituted about 70 percent of the total protein, and three minor polypeptides (74,000, 100,000, and 220,000 daltons). Squid brain intermediate filaments were reconstituted from rod-shaped protofilamentous subunits. In addition to the intermediate filaments, dense bodies which may function in intermediate filament nucleation or organization were retained through two purification cycles.
Suckling Infant Rats Learn a Preference for a Novel Olfactory Stimulus Paired with Milk Delivery
Authors: Brake Stephen C.
Published: October 2006

When presented a novel olfactory stimulus while suckling a passive dam, 11- to 14-day-old rat pups acquire a conditioned preference for that stimulus. The magnitude of the conditioned preference is greater if the pups received milk while suckling than if they did not. The results indicate that infants are capable of learning while suckling and that milk delivery plays a role in this associative process.
Transformation of Paralytic Shellfish Toxins as Demonstrated in Scallop Homogenates
Authors: Shimizu Yuzuru , Yoshioka Masako
Published: October 2006

Toxins in shellfish, which are responsible for paralytic poisonings, undergo reductive transformation when incubated with the homogenate of various portions of the scallop,
Placopecten magellanicus
. The transformation includes the reductive elimination of
O
-sulfate groups, a change that is most evident in the locomotor tissue homogenates. The commercially important adductor muscles can also inactivate the toxins.
Endoplasmic Reticulum Sequesters Calcium in the Squid Giant Axon
Authors: Henkart Maryanna P. , Reese T. S. , Brinley F. J.
Published: October 2006

Axons were loaded with calcium, rapidly frozen, and freeze-substituted. The endoplasmic reticulum, in addition to mitochondria, contained calcium deposits, as indicated by electron probe x-ray microanalysis. Oxalate injected into living axons helped to preserve calcium-containing deposits during preparation for microscopy. It is concluded that the endoplasmic reticulum is a calcium-sequestering compartment in the squid giant axon.
Periodicity of Sleep States Is Altered in Infants at Risk for the Sudden Infant Death Syndrome
Authors: Harper R. M. , Leake B. , Hoffman H. , Walter D. O. , Hoppenbrouwers T. , Hodgman J. , Sterman M. B.
Published: October 2006

The normal succession of sleep and waking states through a night is disturbed in infants at risk for the sudden infant death syndrome. Compared with normal infants, siblings of the sudden infant death syndrome victims have longer intervals between active sleep epochs at particular times during the night in the newborn period and a decreased tendency to enter short waking periods at 2 and 3 months of age. The latter finding is interpreted as an increased tendency to remain asleep, or a relative failure to arouse from sleep in infants at risk.
Plasmid-Assisted Molecular Breeding: New Technique for Enhanced Biodegradation of Persistent Toxic Chemicals
Authors: Kellogg S. T. , Chatterjee D. K. , Chakrabarty A. M.
Published: October 2006

The persistence of synthetic herbicides such as 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and its release in massive amounts as a herbicide (Agent Orange) have created toxicological problems in many countries. In nature, 2,4,5-T is slowly degraded by cooxidation and is not utilized as a sole source of carbon and energy. The technique of plasmid-assisted molecular breeding has led to the development of bacterial strains capable of totally degrading 2,4,5-T by using it as their sole source of carbon at high concentrations (greater than 1 mg/ml). Spectrophotometry and gas chromatography reveal various intermediates during growth of the culture with 2,4,5-T.
Buprenorphine Suppresses Heroin Use by Heroin Addicts
Authors: Mello Nancy K. , Mendelson Jack H.
Published: October 2006

Heroin-dependent men were given buprenorphine (a partial opiate agonist-antagonist) or a placebo under double-blind conditions on a clinical research ward where they could acquire heroin (21 to 40.5 milligrams per day, intravenously). Buprenorphine significantly (P < .001) suppressed the self-administration of heroin over 10 days. Control subjects took between 93 and 100 percent of the available heroin. The effects of buprenorphine were dose-dependent; a dose of 8 milligrams per day reduced heroin use by 69 to 98 percent; a dose of 4 milligrams per day reduced heroin use by 45 percent. Termination of buprenorphine maintenance did not result in opiate withdrawal signs or symptoms. The subjects liked buprenorphine and indicated that it was preferable to methadone or naltrexone. Buprenorphine should be a safe and effective new pharmacotherapy for heroin dependence.
Bone Cancer from Radium: Canine Dose Response Explains Data for Mice and Humans
Authors: Raabe Otto G. , Book Steven A. , Parks Norris J.
Published: October 2006

Analysis of lifetime studies of 243 beagles with skeletal burdens of radium-226 shows that the distribution of bone cancers clusters about a linear function of the logarithms of radiation dose rate to the skeleton and time from exposure until death. Similar relations displaced by species-dependent response ratios also provide satisfactory descriptions of the reported data on deaths from primary bone cancers in people and mice exposed to radium-226. The median cumulative doses (or times) leading to death from bone tumors are 2.9 times larger for dogs than for mice and 3.6 times larger for people than for dogs. These response ratios are well correlated with the normal life expectancies. The cumulative radiation dose required to give significant risk of bone cancer is found to be much less at lower dose rates than at higher rates, but the time required for the tumors to be manifested is longer. At low dose rates, this time exceeds the normal life-span and appears as a practical threshold, which for bone cancer is estimated to occur at an average cumulative radiation dose to the skeleton of about 50 to 110 rads for the three species.
Energy Requirement for Nitrogen Fixation in Actinorhizal and Legume Root Nodules
Authors: Tjepkema John D. , Winship Lawrence J.
Published: October 2006

The ratio of respiration to nitrogenase activity was measured in five species of actinorhizal root nodules and eight species of legume nodules. The two types of nodules could not be distinguished on the basis of this ratio; this evidence thus indicates that the energy cost of nitrogen fixation is similar for both.
Developmental Equations Reflect Brain Dysfunctions
Authors: Ahn H. , Prichep L. , John E. R. , Baird H. , Trepetin M. , Kaye H.
Published: October 2006

Developmental equations, which predict 32 parameters of the electroencephalogram recorded from the healthy human as a function of age, were tested in diverse groups of children. Few significant deviations were found in normal children, even in a culture different from the one on which the equations were based. A high incidence of significant deviations was found in children with learning disabilities and those at risk for various neurological disorders.
Electroretinographic Responses to Alternating Gratings Before and After Section of the Optic Nerve
Authors: Mafei L. , Fiorentini A.
Published: October 2006

Electroretinographic (ERG) responses to sinusoidal gratings reversed in contrast (pattern-reversal ERG) were recorded from both eyes of cats before and after unilateral section of the optic nerve. In the eye ipsilateral to the section, the pattern-reversal ERG remained unaltered for a few days after the section, then progressively decreased in amplitude, first at low and then at high spatial frequencies, to disappear completely about 4 months after the section, when ganglion cell degeneration was practically complete. The flash ERG remained unaltered. No alteration was observed in the contralateral eye.
Conduction System in a Sponge
Authors: Lawn I. D. , Mackie G. O. , Silver G.
Published: October 2006

The hexactinellid sponge
Rhabdocalyptus dawsoni
is capable of arresting its exhalant water current in response to mechanical and electrical stimuli. The arrest is coordinated by a conduction system with a precise threshold of excitability and a chronaxie of 38 milliseconds. The response is propagated throughout the sponge at a mean velocity of 0.22 centimeter per second, and conduction is unpolarized.
Local Foveal Inhibitory Effects of Global Peripheral Excitation
Authors: Breitmeyer Bruno G. , Valberg Arne
Published: October 2006

Global excitation produced by oscillating a peripheral square-wave grating back and forth through one-half cycle inhibits the visibility of an incremental test flash only when the flash is presented in the foveal region of the visual field. This finding is discussed in the context of the neurophysiological periphery effect and shift-effect and their possible role in saccadic suppression.
Movement of the Guide Sequence During RNA Catalysis by a Group I Ribozyme
Authors: Wang Jin-Feng , Downs William D. , Cech Thomas R.
Published: October 2006

Ribozymes derived from the self-splicing pre-ribosomal RNA of
Tetrahymena
act as sequence-specific endonucleases. The reaction involves binding an RNA or DNA substrate by base pairing to the internal guide sequence (IGS) to form helix P1. Site-specific photo-crosslinking localized the 5′ end of the IGS in helix P1 to the vicinity of conserved bases between helices P4 and P5, supporting a major feature of the Michel-Westhof three-dimensional structure model. The crosslinked ribozyme retained catalytic activity. When not base-paired, the IGS was still specifically crosslinked, but the major site was 37 Å distant from the reactive site in the experimentally supported three-dimensional model. The data indicate that a substantial induced-fit conformational change accompanies P1 formation, and they provide a physical basis for understanding the transport of oligonucleotides to the catalytic core of the ribozyme. The ability of RNA to orchestrate large-scale conformational changes may help explain why the ribosome and the spliceosome are RNA-based machines.
Differential T Cell Costimulatory Requirements in CD28-Deficient Mice
Authors: Shahinian Arda , Pfeffer Klaus , Lee Kelvin P. , Kündig Thomas M. , Kishihara Kenji , Wakeham Andrew , Kawai Kazuhiro , Ohashi Pamela S. , Thompson Craig B. , Mak Tak W.
Published: October 2006

T cell receptor stimulation without costimulation is insufficient for the induction of an optimal immune response. It is thought that engagement of the CD28 molecule with its ligand B7 provides an essential costimulatory signal without which full activation of T cells cannot occur. A mouse strain with a defective CD28 gene was established. Development of T and B cells in the CD28-deficient mice appeared normal. However, T lymphocytes derived from CD28
-/-
mutant mice had impaired responses to lectins. Lectin stimulation did not trigger interleukin-2 (IL-2) production, IL-2 receptor α expression was significantly decreased, and exogenous IL-2 only partially rescued the CD28 defect. Basal immunoglobulin (Ig) concentrations in CD28-deficient mice were about one-fifth of those found in wild-type controls, with low titers of IgG1 and IgG2b but an increase in IgG2a. In addition, activity of T helper cells in CD28
-/-
mice was reduced and immunoglobulin class switching was diminished after infection with vesicular stomatitis virus. However, cytotoxic T cells could still be induced and the mice showed delayed-type hypersensitivity after infection with lymphocytic choriomeningitis virus. Thus, CD28 is not required for all T cell responses in vivo, suggesting that alternative costimulatory pathways may exist.
Metalloenzymes, Structural Motifs, and Inorganic Models
Authors: Karlin Kenneth D.
Published: October 2006

Metalloenzymes effect a variety of important chemical transformations, often involving small molecule substrates or products such as molecular oxygen, hydrogen, nitrogen, and water. A diverse array of ions or metal clusters is observed at the active-site cores, but living systems use basic recurring structures that have been modified or tuned for specific purposes. Inorganic chemists are actively involved in the elucidation of the structure, spectroscopy, and mechanism of action of these biological catalysts, in part through a synthetic modeling approach involving biomimetic studies.
Invasion of Erythrocytes by Malaria Merozoites
Authors: Dvorak James A. , Miller Louis H. , Whitehouse Willard C. , Shiroishi Tsugiye
Published: October 2006

An electro-optical system was developed to record microscope images with high resolution at low light intensities. The system was used to study the invasion of erythrocytes by malaria merozoites. Invasion consists of attachment of the anterior end of the parasite to the erythrocyte, deformation of the erythrocyte, and entry of the parasite by erythrocyte membrane invagination.
Transsynaptic Expression of a Presynaptic Glutamate Receptor During Hippocampal Long-Term Potentiation
Authors: Smirnova Tania , Laroche Serge , Errington Michael L. , Hicks Andrew A. , Bliss Timothy V. P. , Mallet Jacques
Published: October 2006

Repetitive activation of excitatory synapses in the hippocampus produces a persistent enhancement of synaptic efficiency known as long-term potentiation (LTP). In anesthetized and in freely moving rats, the induction of LTP in the perforant path led to a transient increase in the amount of messenger RNA (mRNA) coding for a presynaptic glutamate receptor (GR33) in dentate granule cells. The amount of GR33 mRNA was increased for at least 5 hours after the induction of LTP but was indistinguishable from control values 1 day after induction. The
N
-methyl-D-aspartate receptor antagonist 2-aminophosphonovalerate prevented the induction of both LTP and the increase in GR33 mRNA. The amount of GR33 protein was increased in the mossy fiber terminal zone of dentate granule cells 5 hours after the induction of LTP. These results suggest that the induction of LTP in synapses at one stage in a neural network may lead to modification in synaptic function at the next stage in the network.
Inherited Metabolic Diseases of the Nervous System
Authors: Brady Roscoe O.
Published: October 2006

This overview was designed primarily to provide examples of hereditary metabolic disorders that result in nervous system dysfunction. Some of the more frequently encountered pathological conditions were selected in order to illustrate the mechanisms and the consequences of the metabolic derangements. Therapeutic approaches for the correction of such disorders are discussed where it appears appropriate. In time the precise etiology for those eponymous genetic conditions with stereotyped pathologic and clinical manifestations such as Huntington's chorea and Friedreich's ataxia will be disclosed. It is possible that some forms of epilepsy and perhaps certain psychiatric disturbances will be shown to be inherited metabolic disorders. As our knowledge and skill increase, this logic may eventually be extended to biochemical explanations of variation in individual skills and talents. Certainly innovative extrapolation and novel research directions will be necessary to provide an understanding of these differences. However, it is axiomatic in research that each useful contribution serves largely as a point of departure for further accomplishments.
Crystal Structure of Neocarzinostatin, an Antitumor Protein-Chromophore Complex
Authors: Kim Kyoung-Hee , Kwon Byoung-Mog , Myers Andrew G. , Rees Douglas C.
Published: October 2006

Structures of the protein-chromophore complex and the apoprotein form of neocarzinostatin were determined at 1.8 angstrom resolution. Neocarzinostatin is composed of a labile chromophore with DNA-cleaving activity and a stabilizing protein. The chromophore displays marked nonlinearity of the triple bonds and is bound noncovalently in a pocket formed by the two protein domains. The chromophore π-face interacts with the phenyl ring edges of Phe
52
and Phe
78
. The amino sugar and carbonate groups of the chromophore are solvent exposed, whereas the epoxide, acetylene groups, and carbon C-12, the site of nucleophilic thiol addition during chromophore activation, are unexposed. The position of the amino group of the chromophore carbohydrate relative to C-12 supports the idea that the amino group plays a role in thiol activation.
Rad: a Member of the Ras Family Overexpressed in Muscle of Type II Diabetic Humans
Authors: Reynet Christine , Kahn C. Ronald
Published: October 2006

To identify the gene or genes associated with insulin resistance in Type II (non-insulin-dependent) diabetes mellitus, subtraction libraries were prepared from skeletal muscle of normal and diabetic humans and screened with subtracted probes. Only one clone out of 4000 was selectively overexpressed in Type II diabetic muscle as compared to muscle of non-diabetic or Type I diabetic individuals. This clone encoded a new 29-kilodalton member of the Ras-guanosine triphosphatase superfamily and was termed Rad (Ras associated with diabetes). Messenger ribonucleic acid of Rad was expressed primarily in skeletal and cardiac muscle and was increased an average of 8.6-fold in the muscle of Type II diabetics as compared to normal individuals.
Neuronal Differentiation Rescued by Implantation of
Weaver
Granule Cell Precursors into Wild-Type Cerebellar Cortex
Authors: Gao Wei-Qiang , Hatten Mary E.
Published: October 2006

The migration of postmitotic neurons away from compact, germinal zones is a critical step in neuronal differentiation in the developing brain. To study the molecular signals necessary for cerebellar granule cell migration in situ, precursor cells from the neurological mutant mouse
weaver
, an animal with phenotypic defects in migration, were implanted into the external germinal layer (EGL) of wild-type cerebellar cortex. In this region, labeled
weaver
precursor cells of the EGL progressed through all stages of granule neuron differentiation, including the extension of parallel fibers, migration through the molecular and Purkinje cell layers, positioning in the internal granule cell layer, and extension of dendrites. Thus, the
weaver
gene acts nonautonomously in vivo, and local cell interactions may induce early steps in neuronal differentiation that are required for granule cell migration.
Molecular Cloning of an Apolipoprotein B Messenger RNA Editing Protein
Authors: Teng BaBie , Burant Charles F. , Davidson Nicholas O.
Published: October 2006

Mammalian apolipoprotein B (apo B) exists in two forms, each the product of a single gene. The shorter form, apo B48, arises by posttranscriptional RNA editing whereby cytidine deamination produces a UAA termination codon. A full-length complementary DNA clone encoding an apo B messenger RNA editing protein (REPR) was isolated from rat small intestine. The 229-residue protein contains consensus phosphorylation sites and leucine zipper domains. HepG2 cell extracts acquire editing activity when mixed with REPR from oocyte extracts. REPR is essential for apo B messenger RNA editing, and the isolation and characterization of REPR may lead to the identification of other eukaryotic RNA editing proteins.
North American Egg Parasite Successfully Controls a Different Host Genus in South America
Authors: Drooz A. T. , Bustillo A. E. , Fedde G. F. , Fedde V. H.
Published: October 2006

Telenomus alsophilae
, a parasite of the eggs of the geometrid
Alsophila pometaria
in North America, was introduced into Colombia, South America, for the biological control of a pest host in another genus,
Oxydia trychiata
. Successful results were obtained with this unorthodox procedure to control a forest insect.
Derived X Chromosome in the Turtle Genus
Staurotypus
Authors: Sites Jack W. , Bickham John W. , Haiduk Mike W.
Published: October 2006

C-banding, G-banding, and silver (Ag-AS) staining techniques reveal a distinctive sex chromosome system in the turtle
Staurotypus salvinii
. Unlike previously described systems in most other vertebrate groups in which the Y or W is derived and the homogametic sex represents the primitive condition, the reverse is true for
S. salvinii
. The X chromosome is derived; thus the homogametic sex (female) is more derived than the heterogametic sex. The male is intermediate between the female and the ancestral condition observed in other turtle species. Staurotypus does not confirm to the general model of sex chromosome evolution for diploid dioecious organisms.
Markers for Detection of Supplementation in Narcotic Programs—Deuterium-Labeled Methadone
Authors: Hsia J. C. , Tam J. C. L. , Giles H. G. , Leung C. C. , Marcus H. , Marshman J. A. , LeBlanc A. E.
Published: October 2006

Specific deuterium labeling of methadone and use of gas chromatography-mass spectroscopy technique permits rapid and quantitative determination of the ratio of the labeled to unlabeled drug in body fluids. A trideuteriomethadone (methadone-d
3
) was shown to have exactly the same analgesic activity and toxicity in mice as methadone. The rates of absorption, distribution, and excretion of methadone-d
3
and methadone were identical in rats. These observations suggest that methadone-d
3
may be used as an in vivo marker for monitoring methadone intake of patients, and thus may improve the effectiveness of methadone treatment programs.
Metaphase Chromosome Anomaly: Association with Drug Resistance and Cell-Specific Products
Authors: Biedler June L. , Spengler Barbara A.
Published: October 2006

Large, homogeneously staining chromosome regions which lack the longitudinal differentiation ordinarily revealed by cytogenetic "banding" methods have been found in antifolate-resistant Chinese hamster cells and also in human neuroblastoma cells established in vitro. The drug-resistant cells are characterized by excessive production of the target enzyme, dihydrofolate reductase, while the human neuroblastoma cells have phenotypes of normal neuronal cells. The homogeneously staining region appears to represent a novel metaphase chromosome anomaly which may have functional significance in cells with specialized properties.
Sialic Acid: Effect of Removal on Calcium Exchangeability of Cultured Heart Cells
Authors: Langer G. A. , Frank J. S. , Nudd L. M. , Seraydarian K.
Published: October 2006

Specific removal of sialic acid from cultured heart cells with purified neuraminidase increases cellular calcium exchangeability. Potassium exchange is unaffected or slightly decreased. Sialic acid removal also permits lanthanum, normally restricted to the cellular surface, to enter the cells and displace more than 80 percent of cellular calcium. The results indicate a specific role of cellular surface components in the control of calcium exchangeability in the heart.
Identification of Specific Changes in the Pattern of Brain Protein Synthesis After Training
Authors: Shashoua Victor E.
Published: October 2006

Double labeling studies with [
3
H]valine and [
14
C]valine were used to investigate the pattern of protein synthesis in the brains of goldfish. The protein fractions in three bands (α, β, and γ) on sodium dodecyl sulfate-polyacrylamide gels indicate that more valine was incorporated in the brains of goldfish that had been trained in a vestibular conditioning task than in the brains of untrained fish or fish trained in a variety of control behavioral situations. Changes in the pattern of labeling were localized in the cytoplasmic fraction of the brain; no increases in labeling occurred in either the nuclear or synaptosomal components. The results suggest that a specific change occurs in the pattern of protein synthesis in the brain after the acquisition of a new behavior.
Picosecond Chemistry
Authors: Busch G. E. , Rentzepis P. M.
Published: October 2006

The ability to directly measure and evaluate ultrafast processes with unprecedented time resolution and reliability has greatly extended our knowledge about the kinetics of primary processes in chemistry and allied physical and biological sciences. Improvements in the reliability and versatility of picosecond techniques should lead to an increase in the experimental information about basic interactions in atomic and molecular systems.
Physical Dependence of Opiate-Like Peptides
Authors: Wei Eddie , Loh Horace
Published: October 2006

Methionine-enkephalin and β-endorphin, endogenous peptides with activities similar to those of opiates, were infused for 70 hours into the periaqueductal gray-fourth ventricular spaces of the rat brain. When challenged with a naloxone, a specific opiate antagonist, these animals manifested a typical morphine-like withdrawal syndrome. These results show that such peptides can cause physical dependence.
Role of the thrombin/protease-activated receptor 1 pathway in intestinal ischemia-reperfusion injury in rats
Authors: Tsuboi Hisato , Naito Yuji , Katada Kazuhiro , Takagi Tomohisa , Handa Osamu , Kokura Satoshi , Ichikawa Hiroshi , Yoshida Norimasa , Tsukada Minoru , Yoshikawa Toshikazu
Published: October 2006

CXC chemokines, including human interleukin-8 and rat cytokine-induced neutrophil chemoattractant-1, play a crucial role in the pathogenesis of intestinal inflammation induced by ischemia-reperfusion (I-R). Thrombin and its specific receptor, protease-activated receptor 1 (PAR1), act as important players in inflammation. However, the association between thrombin activation and chemokine production during I-R has not been well studied. We investigated whether thrombin and PAR1 might be involved in the pathophysiology of intestinal I-R, using an in vivo model. Intestinal damage was induced by clamping the superior mesenteric artery for 30 min followed by reperfusion in male Wistar rats. Thrombin-antithrombin complex was measured as an indicator of thrombin activation. PAR1 expression in the intestine was evaluated by real-time PCR. The severity of the intestinal mucosal injury was evaluated on the distal segment of the ileum by several biochemical markers and histological findings. Reperfusion significantly increased the serum levels of thrombin-antithrombin complex and enhanced PAR1 expression in the intestinal mucosa. The levels of both intraluminal hemoglobin and protein were significantly increased in the I-R group. The mucosal myeloperoxidase activity and expressions and/or productions of cytokine-induced neutrophil chemoattractant-1 and TNF-α were significantly increased after I-R. These increases were inhibited by the treatment of rat with antithrombin intravenously before I-R at a dose of 30 U/kg. These results suggest that the thrombin/PAR1 pathway plays an important role in the production of these cytokines during I-R and that antithrombin exerts potent anti-inflammatory effects on this injury via inhibition of proinflammatory cytokines.
The Role of Dopamine Receptors in the Neurobehavioral Syndrome Provoked by Activation of L-Type Calcium Channels in Rodents
Authors: Kasim Suhail , Blake Bonita L. , Fan Xueliang , Chartoff Elena , Egami Kiyoshi , Breese George R. , Hess Ellen J. , Jinnah H.A.
Published: October 2006

In rodents, activation of L-type calcium channels with ±BayK 8644 causes an unusual behavioral syndrome that includes dystonia and self-biting. Prior studies have linked both of these behaviors to dysfunction of dopaminergic transmission in the striatum. The current studies were designed to further elucidate the relationship between ±BayK 8644 and dopaminergic transmission in the expression of the behavioral syndrome. The drug does not appear to release presynaptic dopamine stores, since microdialysis of the striatum revealed dopamine release was unaltered by ±BayK 8644. In addition, the behaviors were preserved or even exaggerated in mice or rats with virtually complete dopamine depletion. On the other hand, pretreatment of mice with D3 or D1/5 dopamine receptor antagonists attenuated the behavioral effects of ±BayK 8644, while pretreatment with D2 or D4 antagonists had no effect. In D3 receptor knockout mice, ±BayK 8644 elicited both dystonia and self-biting, but these behaviors were less severe than in matched controls. In D1 receptor knockout mice, behavioral responses to ±BayK 8644 appeared exaggerated. These results argue that the behavioral effects of ±BayK 8644 are not mediated by a presynaptic influence. Instead, the behaviors appear to result from a postsynaptic activation of the drug, which does not require but can be modified by D3 or D1/5 receptors.
The BiSearch web server
Authors: Arányi Tamás , Váradi András , Simon István , Tusnády Gábor E
Published: October 2006

Background

A large number of PCR primer-design softwares are available online. However, only very few of them can be used for the design of primers to amplify bisulfite-treated DNA templates, necessary to determine genomic DNA methylation profiles. Indeed, the number of studies on bisulfite-treated templates exponentially increases as determining DNA methylation becomes more important in the diagnosis of cancers. Bisulfite-treated DNA is difficult to amplify since undesired PCR products are often amplified due to the increased sequence redundancy after the chemical conversion. In order to increase the efficiency of PCR primer-design, we have developed BiSearch web server, an online primer-design tool for both bisulfite-treated and native DNA templates.

Results

The web tool is composed of a primer-design and an electronic PCR (ePCR) algorithm. The completely reformulated ePCR module detects potential mispriming sites as well as undesired PCR products on both cDNA and native or bisulfite-treated genomic DNA libraries. Due to the new algorithm of the current version, the ePCR module became approximately hundred times faster than the previous one and gave the best performance when compared to other web based tools. This high-speed ePCR analysis made possible the development of the new option of high-throughput primer screening. BiSearch web server can be used for academic researchers at the http://bisearch.enzim.hu site.

Conclusion

BiSearch web server is a useful tool for primer-design for any DNA template and especially for bisulfite-treated genomes. The ePCR tool for fast detection of mispriming sites and alternative PCR products in cDNA libraries and native or bisulfite-treated genomes are the unique features of the new version of BiSearch software.
Overexpression of Eag1 potassium channels in clinical tumours
Authors: Hemmerlein Bernhard , Weseloh Rüdiger M , Mello de Queiroz Fernanda , Knötgen Hendrik , Sánchez Araceli , Rubio María E , Martin Sabine , Schliephacke Tessa , Jenke Marc , Heinz-Joachim-Radzun  , Stühmer Walter , Pardo Luis A
Published: October 2006

Background

Certain types of potassium channels (known as Eag1, KCNH1, Kv10.1) are associated with the production of tumours in patients and in animals. We have now studied the expression pattern of the Eag1 channel in a large range of normal and tumour tissues from different collections utilising molecular biological and immunohistochemical techniques.

Results

The use of reverse transcription real-time PCR and specifically generated monoclonal anti-Eag1 antibodies showed that expression of the channel is normally limited to specific areas of the brain and to restricted cell populations throughout the body. Tumour samples, however, showed a significant overexpression of the channel with high frequency (up to 80% depending on the tissue source) regardless of the detection method (staining with either one of the antibodies, or detection of Eag1 RNA).

Conclusion

Inhibition of Eag1 expression in tumour cell lines reduced cell proliferation. Eag1 may therefore represent a promising target for the tailored treatment of human tumours. Furthermore, as normal cells expressing Eag1 are either protected by the blood-brain barrier or represent the terminal stage of normal differentiation, Eag1 based therapies could produce only minor side effects.