bluuebunny/crossref_metadata_2025 huggingface dataset:
Neural Organization and Evolution of Thermal Regulation in Mammals
Authors: Satinoff E.
Published: October 2006

This article proposes a modification of the currently accepted view of the central neural integration of body temperature. In place of a single integrator with multiple inputs and outputs, the new model includes as many integrators as there are thermoregulatory responses. Furthermore, these integrators are postulated to be represented at many levels of the nervous system, with each level facilitated or inhibited by levels above and below. The purpose of such a complicated arrangement is to achieve finer and finer control over body temperature. A consideration of how endothermy might have evolved, with originally nonthermally related responses gradually coming under thermal control, makes such a brain organization highly reasonable.
Physostigmine: Improvement of Long-Term Memory Processes in Normal Humans
Authors: Davis Kenneth L. , Mohs Richard C. , Tinklenberg Jared R. , Pfefferbaum Adolf , Hollister Leo E. , Kopell Bert S.
Published: October 2006

Nineteen normal male subjects received 1.0 milligram of physostigmine or 1.0 milligram of saline by a slow intravenous infusion on two nonconsecutive days. Physostigmine significantly enhanced storage of information into long-term memory. Retrieval of information from long-term memory was also improved. Short-term memory processes were not significantly altered by physostigmine.
Drug-Resistant
Salmonella
in the United States: an Epidemiologic Perspective
Authors: Cohen Mitchell L. , Tauxe Robert V.
Published: October 2006

Salmonellosis poses a health problem of large proportions in the United States. Annually, it accounts for more than 40,000 reported cases, 500 deaths, and financial costs well in excess of $50 million. Antimicrobial resistance is increasing in
Salmonella
strains, a finding that has important public health implications. Although the chain of transmission of the bacteria is often complex, combined epidemiologic and laboratory studies with the use of new methods in molecular biology make it possible to trace antimicrobial-resistant salmonellae to their primary source—foods of animal origin. These studies suggest that the antimicrobial drugs to which food animals are exposed provide selective pressure that leads to the appearance and persistence of resistant strains.
Yeast KEX2 Protease Has the Properties of a Human Proalbumin Converting Enzyme
Authors: Bathurst Ian C. , Brennan Stephen O. , Carrell Robin W. , Cousens Lawrence S. , Brake Anthony J. , Barr Philip J.
Published: October 2006

Several classes of proteolytic enzymes have been proposed to have a role in the processing of precursor forms of proproteins at paired basic amino acid residues. In higher eukaryotes, a single endopeptidase has yet to fulfill the necessary criteria as the physiologically relevant convertase. The observation of proalbumin circulating in a child with a bleeding disorder caused by an unusual α
1
-antitrypsin mutation led to speculation that the presence of this α
1
-antitrypsin mutant was inhibitory to the convertase. This provided an additional means of characterizing the processing enzyme. In this study the yeast KEX2 enzyme, a calcium-dependent thiol protease, was found to have all the properties expected for this processing enzyme. KEX2 correctly recognized and cleaved the prosequence in proalbumin. In addition, KEX2 was specifically inhibited by the mutant α
1
-antitrypsin but not by other serine protease inhibitors.
Two Mammalian Genes Transcribed from Opposite Strands of the Same DNA Locus
Authors: Adelman John P. , Bond Chris T. , Douglass James , Herbert Edward
Published: October 2006

This report describes the characterization of a genomic locus in the rat that encodes overlapping genes occupying both strands of the same piece of DNA. One gene (strand) encodes gonadotropin-releasing hormone (GnRH). A second gene, SH, is transcribed from the other DNA strand to produce RNA of undefined function. The RNAs transcribed from each DNA strand are spliced and polyadenylated, and share significant exon domains. GnRH is expressed in the central nervous system while SH transcripts are present in the heart. Thus, the genome of a mammalian organism encodes two distinct genes by using both strands of the same DNA.
It Is Diprotonated Inorganic Phosphate That Depresses Force in Skinned Skeletal Muscle Fibers
Authors: Nosek Thomas M. , Fender Kimberly Y. , Godt Robert E.
Published: October 2006

The increases in the intracellular concentrations of inorganic phosphate and hydrogen ion accompanying fatigue of skeletal muscle appear to be the most important metabolic changes associated with the decrease in contractile force. Experiments on chemically skinned single fibers from rabbit psoas muscle with
p
H ranging between 6 and 7.25 demonstrate that the depression of maximal calcium-activated force by inorganic phosphate correlates nicely with the concentration of the acidic (diprotonated) species. Therefore, in addition to the well-known depressant effect on the contractile machinery of lowering
p
H per se, any decrease of intracellular
p
H associated with fatigue further depresses force production by converting more of the total inorganic phosphate within the cell to the inhibitory diprotonated form.
Risk Assessment and Comparisons: An Introduction
Authors: Wilson Richard , Crouch E. A. C.
Published: October 2006

Risk assessment is presented as a way of examining risks so that they may be better avoided, reduced, or otherwise managed. Risk implies uncertainty, so that risk assessment is largely concerned with uncertainty and hence with a concept of probability that is hard to grasp. The results of even the simplest risk assessments need to be compared with similar assessments of commonplace situations to give them some meaning. We compare and contrast some risk estimates to display their similarities and differences.
Glucocorticoid Receptor-Like Antigen in Lymphoma Cell Membranes: Correlation to Cell Lysis
Authors: Gametchu Bahiru
Published: October 2006

S-49 mouse lymphoma cells undergo lysis when treated with glucocorticoids; the mechanism of this effect is not understood. A protein was detected in the plasma membrane of these cells by means of direct immunofluorescent labeling with a monoclonal antibody to the soluble glucocorticoid receptor. Cellular heterogeneity in the content of this glucocorticoid receptor-like molecule was evident. By immunoadsorption to antibody-coated tissue culture plates, the cells were separated into populations positive (100%) and depleted (38%) for this membrane antigen. Gel electrophoresis, specific immunoblot, and autoradiographic (binding of [
3
H]dexamethasone mesylate) analysis of the membrane proteins from the membrane antigen-positive group revealed multiple protein bands ranging in size from 85 to 145 kilodaltons. Furthermore, comparison of the glucocorticoid sensitivity of these groups of cells showed complete lysis of the membrane antigen-positive cells and only partial lysis of the antigen-deficient group, which suggests that the lysis response of cells to glucocorticoids is mediated by a glucocorticoid receptor-like molecule located in the plasma membrane.
On the Prevalence of Room-Temperature Protein Phosphorescence
Authors: Vanderkooi Jane M. , Calhoun Doroth B. , Englander S. Walter
Published: October 2006

A large number of proteins were tested for the property of intrinsic phosphorescence in deoxygenated aqueous solution at room temperature. The majority of proteins exhibit phosphorescence under normal solution conditions. Phosphorescence lifetimes from 0.5 millisecond to 2 seconds were observed in three-fourths of the proteins tested. The lifetime appears to correlate with relative isolation of the tryptophan indole side chain from solvent. With few exceptions, proteins in general can be expected to display a phosphorescence lifetime greater than 30 microseconds. This widespread characteristic of proteins has been largely overlooked because long-lived phosphorescence is highly sensitive to quenching by low levels of dissolved oxygen in solution. Protein phosphorescence offers a new time domain and a far wider dynamic range than has been used before for photoluminescence experimentation.
Genetic Analysis of Halothane Sensitivity in
Caenorhabditis elegans
Authors: Sedensky Margaret M. , Meneely Philip M.
Published: October 2006

The nematode
Caenorhabditis elegans
appears to be a useful model for studying the action of volatile anesthetics. A mutant strain that is hypersensitive to the widely used anesthetic halothane was described earlier. The mutation is now shown to be an allele of
unc-79
. Other alleles of
unc-79
are also associated with hypersensitivity to halothane. A strain with a mutation in a second gene,
unc-80
, is also hypersensitive to halothane. Nematodes bearing mutations in both
unc-79
and
unc-80
are slightly more sensitive to halothane than those bearing only one of these mutations. Mutations in a third gene,
unc-9
, suppress both
unc-79
and
unc-80
. Nematodes bearing the suppressor mutations alone have normal sensitivity to halothane. These results show that sensitivity to halothane can be altered by mutations in several different genes.
β
1
- and β
2
-Adrenergic Receptors in Rat Cerebral Cortex Are Independently Regulated
Authors: Minneman Kenneth P. , Dibner Mark D. , Wolfe Barry B. , Molinoff Perry B.
Published: October 2006

Repeated administration of the tricyclic antidepressant desmethylimipramine to adult rats for 10 days caused a 40 percent decrease in the density of β
1
-adrenergic receptors in the cerebral cortex but had no effect on the density of β
2
-adrenergic receptors. Conversely, destruction of noradrenergic neurons by administration of 6-hydroxydopamine to neonatal rats caused a 64 percent increase in the density of β
1
-adrenergic receptors in adult cerebral cortex with no change in the density of β
2
-adrenergic receptors. These results suggest that the β-adrenergic receptors in rat cortex involved in neuronal function are primarily of the β
1
subtype.
Parallel and Serial Processes in Motion Detection
Authors: Dick Miri , Ullman Shimon , Sagi Dov
Published: October 2006

Apparent motion was used to explore humans' ability to perceive the direction of motion in the visual field. A marked qualitative difference in this ability was found between short- and long-range motion. For short-range motion, the detection of the direction of motion is characterized by parallel operation over a wide visual field (that is, detection performance is independent of the number of objects in an array). When the positional displacement is large relative to an object's size, the direction of motion is detected in a serial manner. The process of detection is limited in this case by the ability to detect other events, such as appearance and disappearance of an object, and the ability to compute their spatio-temporal relations. The results are consistent with a previously suggested division of the motion detection system into short- and long-range processes. The direction of short-range motion can be perceived in parallel (preattentively), whereas long-range motion is attentive and requires more complicated computations. It seems that the detection of long-range motion is a conjunction task, combining the detection of disappearance and appearance.
Delay Time of Hemoglobin S Polymerization Prevents Most Cells from Sickling in Vivo
Authors: Mozzarelli Andrea , Hofrichter James , Eaton William A.
Published: October 2006

A laser photolysis technique has been developed to assess the quantitative significance of the delay time of hemoglobin S gelation to the pathophysiology of sickle cell disease. Changes in the saturation of hemoglobin S with carbon monoxide produced by varying the intensity of a photolytic laser beam were used to simulate changes in the saturation of oxyhemoglobin S produced by variations in oxygen pressure. The presence of polymer at steady-state saturation with carbon monoxide was determined by measurement of the kinetics of gelation after complete photodissociation. The kinetics are a very sensitive probe for polymer since small amounts of polymerized hemoglobin increase the rate of nucleation sufficiently to eliminate the delay period. First, the equilibrium gelation properties of partially photodissociated carbonmonoxyhemoglobin S were shown to be the same as partially oxygenated hemoglobin S, and the method was then used to determine the effect of saturation on the formation and disappearance of polymers in individual sickle cells. The saturation at which polymers first formed upon deoxygenation was much lower than the saturation at which polymers disappeared upon reoxygenation. The results indicate that at venous saturations with oxygen, gelation takes place in most cells at equilibrium, but is prevented from occurring in vivo because the delay times are sufficiently long that most cells return to the lungs and are reoxygenated before polymerization has begun.
Sickling Rates of Human as Red Cells Infected in Vitro with
Plasmodium falciparum
Malaria
Authors: Roth Eugene F. , Friedman Milton , Ueda Yoshihiro , Tellez Isabel , Trager William , Nagel Ronald L.
Published: October 2006

The kinetics of sickling of malaria-infected red cells from humans with sickle cell trait were studied in vitro in an attempt to obtain direct experimental evidence for a selective advantage of the hemoglobin S heterozygote in a malarious region. The sickling rates of cells infected with
Plasmodium falciparum
and of non-infected cells were studied both in the total absence of oxygen (by dithionite addition) and at several different concentrations of oxyhemoglobin which might obtain in vivo. In all cases, red cells containing small plasmodium parasite forms (ring forms) sickled approximately eight times as readily as uninfected cells. Cells containing large parasitic forms (trophozoites and schizonts) appeared to sickle less readily than uninfected cells, by light microscopy criteria, but electron micrographs demonstrated the presence of polymerized deoxyhemoglobin S with a high frequency. It is concluded that enhanced sickling of plasmodium-infected AS cells may be one mechanism whereby the hemoglobin S polymorphism is balanced in favor of the heterozygote.
Model Studies of Polychlorinated Dibenzo-
p
-Dioxin Formation During Municipal Refuse Incineration
Authors: Karasek F. W. , Dickson L. C.
Published: October 2006

Toxic chlorinated dibenzo-
p
-dioxins are known to be formed in incinerators that burn municipal refuse. These compounds were synthesized by surface-catalyzed reactions on fly ash particulates taken from incinerators. Dioxins were produced catalytically from chlorinated phenol precursors, from non-chlorinated compounds that were chemically dissimilar to dioxins, and from reaction of phenol with inorganic chlorides. The relative amounts of dioxins formed from [
13
C
6
]pentachlorophenol with different fly ashes that had been cleaned of all organic compounds corresponded well with those amounts originally found on the samples as received from the incinerators. The optimum temperature range for the formation of dioxins from pentachlorophenol was 250° to 350°C.
Tolerance Induced by Thymic Epithelial Grafts in Birds
Authors: Ohki Hiroko , Martin Claude , Corbel Catherine , Coltey Monique , Le Douarin Nicole M.
Published: October 2006

Grafts of the anterior limb bud introduced at embryonic day 4 between histoincompatible chick embryos were subject to chronic, mild rejection beginning from several weeks to several months after birth. In contrast, quail wing buds similarly grafted into chickens started to be rejected at the first or second week after birth and finally autoamputated. Embryonic thymus epithelium from donor quail (before it had been colonized by hemopoietic cells) was grafted into chicks. A chimeric thymic epithelial stroma was generated in which the lymphocytes of the chick acquired the capacity to recognize the grafted limb as self either permanently or for a protracted period of time. In such thymic chimeras the grafted wings were not rejected.
Chemoattractant-Regulated Mobilization of a Novel Intracellular Compartment in Human Neutrophils
Authors: Borregaard N. , Miller L. J. , Springer T. A.
Published: October 2006

A novel mobilizable intracellular compartment was identified in human neutrophils by latent alkaline phosphatase activity. This compartment is mobilized to the plasma membrane much more readily than any identified granule subset and has kinetics of up-regulation in the membrane similar to those reported for a variety of receptor proteins. Triton X-100 permeabilization of both intact human neutrophils and subcellular fractions obtained by density-gradient centrifugation revealed that 70 percent of the alkaline phosphatase is located in an intracellular compartment distinct from primary, secondary, and gelatinase granules and from the plasma membrane. This compartment fully translocates to the plasma membrane after stimulation with nanomolar concentrations of the chemotactic peptide
N
-formylmethionylleucylphenylalanine.
Reduction to Homozygosity of Genes on Chromosome 11 in Human Breast Neoplasia
Authors: Ali Iqbal Unnisa , Lidereau Rosette , Theillet Charles , Callahan Robert
Published: October 2006

The somatic loss of heterozygosity for normal alleles occurring in human tumors has suggested the presence of recessive oncogenes. The results presented here demonstrate a loss of heterozygosity of several genes on chromosome 11 in primary breast tumors. Restriction fragment length polymorphism analysis of these DNAs further suggests that the most frequent loss of sequences in breast tumors occurs between the β-globin and parathyroid hormone loci on the short arm of chromosome 11. The loss of heterozygosity for chromosome 11 loci has a significant association with tumors that lack estrogen and progesterone receptors, grade III tumors, and distal metastasis.
Family Study of Platelet Membrane Fluidity in Alzheimer's Disease
Authors: Zubenko George S. , Wusylko Michael , Cohen Bruce M. , Boller Francois , Teply Ivana
Published: October 2006

The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in labeled platelet membranes, an index of membrane fluidity, identifies a prominent subgroup of patients with Alzheimer's disease who manifest distinct clinical features. In a family study, the prevalence of this platelet membrane abnormality was 3.2 to 11.5 times higher in asymptomatic, first-degree relatives of probands with Alzheimer's disease than in neurologically healthy control subjects chosen without regard to family history of dementia. The pattern of the platelet membrane abnormality within families was consistent with that of a fully penetrant autosomal dominant trait. Thus, this abnormality of platelet membranes may be an inherited factor that is related to the development of Alzheimer's disease.
Separation of D and L Amino Acids by Liquid Chromatography: Use of Chiral Eluants
Authors: Hare P. E. , Gil-Av E.
Published: October 2006

An aqueous eluant containing a chiral copper-proline complex effects the separation of underivatized amino acid enantiomers on an ion-exchange column. The stereoselectivity is ascribed to differences in stability of the diastereomeric amino acid-copper complexes formed in solution. A simple change in the chirality of the eluant reverses the order of the enantiomer elution. For detection and quantification of picomole amounts of amino acids, the eluant is monitored for fluorescence after reaction with o-phthalaldehyde, a reagent insensitive to proline but highly sensitive for amino acids containing a primary amino group.
Teaching Reasoning
Authors: Nisbett Richard E. , Fong Geoffrey T. , Lehman Darrin R. , Cheng Patricia W.
Published: October 2006

Twentieth-century psychologists have been pessimistic about teaching reasoning, prevailing opinion suggesting that people may possess only domain-specific rules, rather than abstract rules; this would mean that training a rule in one domain would not produce generalization to other domains. Alternatively, it was thought that people might possess abstract rules (such as logical ones) but that these are induced developmentally through self-discovery methods and cannot be trained. Research suggests a much more optimistic view: even brief formal training in inferential rules may enhance their use for reasoning about everyday life events. Previous theorists may have been mistaken about trainability, in part because they misidentified the kind of rules that people use naturally.
Suppression of Neurite Elongation and Growth Cone Motility by Electrical Activity
Authors: Cohan Christopher S. , Kater Stanley B.
Published: October 2006

Electrical activity may regulate a number of neuronal functions in addition to its role in transmitting signals along nerve cells. The hypothesis that electrical activity affects neurite elongation in sprouting neurons was tested by stimulating individual snail neurons isolated in cell culture. The findings demonstrated that growth cone advance, and thus neurite elongation, is reversibly stopped during periods when action potentials are experimentally evoked. A decrease in filopodial number and growth cone area was also observed. Thus, action potentials can mediate the cessation of neurite outgrowth and thereby may influence structure and connectivity within the nervous system.
Bright Light Resets the Human Circadian Pacemaker Independent of the Timing of the Sleep-Wake Cycle
Authors: Czeisler Charles A. , Allan James S. , Strogatz Steven H. , Ronda Joseph M. , Sánchez Ramiro , Ríos C. David , Freitag Walter O. , Richardson Gary S. , Kronauer Richard E.
Published: October 2006

Human circadian rhythms were once thought to be insensitive to light, with synchronization to the 24-hour day accomplished either through social contacts or the sleep-wake schedule. Yet the demonstration of an intensity-dependent neuroendocrine response to bright light has led to renewed consideration of light as a possible synchronizer of the human circadian pacemaker. In a laboratory study, the output of the circadian pacemaker of an elderly woman was monitored before and after exposure to 4 hours of bright light for seven consecutive evenings, and before and after a control study in ordinary room light while her sleep-wake schedule and social contacts remained unchanged. The exposure to bright light in the evening induced a 6-hour delay shift of her circadian pacemaker, as indicated by recordings of body temperature and cortisol secretion. The unexpected magnitude, rapidity, and stability of the shift challenge existing concepts regarding circadian phase-resetting capacity in man and suggest that exposure to bright light can indeed reset the human circadian pacemaker, which controls daily variations in physiologic, behavioral, and cognitive function.
Amplification of an Esterase Gene Is Responsible for Insecticide Resistance in a California
Culex
Mosquito
Authors: Mouchès Claude , Pasteur Nicole , Bergé Jean B. , Hyrien Olivier , Raymond Michel , Robert de Saint Vincent Bruno , de Silvestri Monique , Georghiou George P.
Published: October 2006

An esterase gene from the mosquito
Culex quinquefasciatus
that is responsible for resistance to a variety of organophosphorus (OP) insecticides was cloned in λgt11 phage. This gene was used to investigate the genetic mechanism of the high production of the esterase B1 it encodes in OP-resistant
Culex quinquefasciatus
Say (Tem-R strain) from California. Adults of the Tem-R strain were found to possess at least 250 times more copies of the gene than adults of a susceptible strain (S-Lab). The finding that selection by pesticides may result in the amplification of genes encoding detoxifying enzymes in whole, normally developed, reproducing insects emphasizes the biological importance of this mechanism and opens new areas of investigation in pesticide resistance management.
Molecular Cloning and Expression of Neuroleukin, a Neurotrophic Factor for Spinal and Sensory Neurons
Authors: Gurney Mark E. , Heinrich Susan P. , Lee Mark R. , Yin Hsiang-Sshu
Published: October 2006

A novel 56,000-dalton growth factor found in mouse salivary gland was purified, molecularly cloned, and expressed in monkey COS cells. The protein is a neurotrophic factor and also, surprisingly, a lymphokine product of lectin-stimulated T cells. The factor was therefore named neuroleukin. Neuroleukin promotes the survival in culture of a subpopulation of embryonic spinal neurons that probably includes skeletal motor neurons. Neuroleukin also supports the survival of cultured sensory neurons that are insensitive to nerve growth factor, but has no effect on sympathetic or parasympathetic neurons. The amino acid sequence of neuroleukin is partly homologous to a highly conserved region of the external envelope protein of HTLV-III/LAV, the retrovirus that causes acquired immune deficiency syndrome.
New Prospects for Epidemiologic Investigations
Authors: Glass Roger I.
Published: October 2006

Epidemiology has evolved from its historic origins as the study of major epidemics and vital statistics to a contemporary focus on the study of the distribution and determinants of health and disease in humans. This evolution reflects changes in the patterns of diseases and deaths that have occurred in our time and has placed new emphasis on preventing avoidable, premature deaths. Advances in clinical medicine, laboratory science, statistical and data handling methods, and in our basic understanding of the pathogenesis of disease have enabled epidemiologists to better examine causes of disease and to propose more effective strategies for prevention and control.
Neuronal Properties of Clonal Hybrid Cell Lines Derived from Central Cholinergic Neurons
Authors: Hammond David N. , Wainer Bruce H. , Tonsgard James H. , Heller Alfred
Published: October 2006

Clonal cell lines derived from specific types of central neurons can be used to identify and characterize properties specific to those neurons. With somatic cell fusion techniques, nine clonal hybrid cell lines have been developed from the septal region of the mouse basal forebrain. Two lines express characteristics typical of cholinergic neurons—choline acetyltransferase activity and immunoreactivity, neurite formation with neurofilament protein immunoreactivity, and aggregation in rotation-mediated cell culture. These cell lines may be useful for studying the trophic interactions that support the development and maintenance of central cholinergic connections.
Human Breast Cancer: Correlation of Relapse and Survival with Amplification of the HER-2/neuOncogene
Authors: Slamon Dennis J. , Clark Gary M. , Wong Steven G. , Levin Wendy J. , Ullrich Axel , McGuire William L.
Published: October 2006

The HER-2/neuoncogene is a member of theerbB-like oncogene family, and is related to, but distinct from, the epidermal growth factor receptor. This gene has been shown to be amplified in human breast cancer cell lines. In the current study, alterations of the gene in 189 primary human breast cancers were investigated. HER-2/neuwas found to be amplified from 2- to greater than 20-fold in 30% of the tumors. Correlation of gene amplification with several disease parameters was evaluated. Amplification of the HER-2/neugene was a significant predictor of both overall survival and time to relapse in patients with breast cancer. It retained its significance even when adjustments were made for other known prognostic factors. Moreover, HER-2/neuamplification had greater prognostic value than most currently used prognostic factors, including hormonal-receptor status, in lymph node-positive disease. These data indicate that this gene may play a role in the biologic behavior and/or pathogenesis of human breast cancer.
Metalloregulatory DNA-binding Protein Encoded by the
merR
Gene: Isolation and Characterization
Authors: O'Halloran Thomas , Walsh Christopher
Published: October 2006

The MerR protein mediates the induction of the mercury resistance phenotype in bacteria; it has been isolated in order to study the effects of metal-ion induced changes in the metabolism of prokaryotic cells at the molecular level. After DNA sequences responsible for negative autoregulation were removed, the 16-kilodalton protein was overproduced and purified to more than 90 percent homogeneity by a salt extraction procedure that yields about 5 milligrams of protein per gram of cells. Complementation data, amino terminal analysis, gel filtration, and deoxyribonuclease I protection studies demonstrate that the purified
merR
gene product is a dimer under nondenaturing conditions and that it binds specifically to DNA, in the presence and absence of mercury, at a palindromic site which is directly between the -10 and -35 regions of the structural genes and adjacent to its own promoter. These initial results indicate that MerR is a DNA-binding metalloregulatory protein that plays a central role in this heavy metal responsive system and they delineate an operator site in the
mer
operon.
Cellular and Subcellular Heterogeneity of [Ca
2+
]
i
in Single Heart Cells Revealed by Fura-2
Authors: Wier W. G. , Cannell M. B. , Berlin J. R , Marban E. , Lederer W. J.
Published: October 2006

Digital imaging of calcium indicator signals (fura-2 fluorescence) from single cardiac cells has revealed different subcellular patterns of cytoplasmic calcium ion concentration ([Ca
2+
]
i
) that are associated with different types of cellular appearance and behavior. In any population of enzymatically isolated rat heart cells, there are (i) mechanically quiescent cells in which [Ca
2+
]
i
is spatially uniform, constant over time, and relatively low; (ii) spontaneously contracting cells, which have an increased [Ca
2+
]
i
, but in which the spatial uniformity of [Ca
2+
]
i
is interrupted periodically by spontaneous propagating waves of high [Ca
2+
]
i
; and (iii) cells that are hypercontracted (rounded up) and that have higher levels of [Ca
2+
]
i
than the other two types. The observed cellular and subcellular heterogeneity of [Ca
2+
]
i
in isolated cells indicates that experiments performed on suspensions of cells should be interpreted with caution. The spontaneous [Ca
2+
]
i
fluctuations previously observed without spatial resolution in multicellular preparations may actually be inhomogeneous at the subcellular level.
Lunar-Modulated Geomagnetic Orientation by a Marine Mollusk
Authors: Lohmann Kenneth J. , Willows A. O. Dennis
Published: October 2006

Behavioral experiments indicated that the marine opisthobranch mollusk
Tritonia diomedea
can derive directional cues from the magnetic field of the earth. The magnetic direction toward which nudibranchs spontaneously oriented in the geomagnetic field showed recurring patterns of variation correlated with lunar phase, suggesting that the behavioral response to magnetism is modulated by a circa-lunar rhythm. The discovery of a magnetic sense in a mollusk with giant, reidentifiable neurons provides a unique opportunity to study the cellular mechanisms underlying magnetic field detection.
Human Lipoprotein Lipase Complementary DNA Sequence
Authors: Wion Karen L. , Kirchgessner Todd G. , Lusis Aldons J. , Schotz Michael C. , Lawn Richard M.
Published: October 2006

Lipoprotein lipase is a key enzyme of lipid metabolism that acts to hydrolyze triglycerides, providing free fatty acids for cells and affecting the maturation of circulating lipoproteins. It has been proposed that the enzyme plays a role in the development of obesity and atherosclerosis. The human enzyme has been difficult to purify and its protein sequence was heretofore undetermined. A complementary DNA for human lipoprotein lipase that codes for a mature protein of 448 amino acids has now been cloned and sequenced. Analysis of the sequence indicates that human lipoprotein lipase, hepatic lipase, and pancreatic lipase are members of a gene family. Two distinct species of lipoprotein lipase messenger RNA that arise from alternative sites of 3′-terminal polyadenylation were detected in several different tissues.
Antipsychotic Drug Action in Schizophrenic Patients: Effect on Cortical Dopamine Metabolism After Long-Term Treatment
Authors: Bacopoulos N. C. , Spokes E. G. , Bird E. D. , Roth R. H.
Published: October 2006

In the brains of deceased schizophrenics who underwent long-term treatment with antipsychotic drugs, the concentration of homovanillic acid (a dopamine metabolite) was significantly increased in the orbital frontal, cingulate, and temporal tip areas of the cortex, but not in the putamen or the nucleus accumbens. The concentration of homovanillic acid was normal in the brains of schizophrenics who were not treated with antipsychotic drugs.
Cassette of Eight Exons Shared by Genes for LDL Receptor and EGF Precursor
Authors: Südhof Thomas C. , Russell David W. , Goldstein Joseph L. , Brown Michael S. , Sanchez-Pescador Ray , Bell Graeme I.
Published: October 2006

The amino acid sequences of the human low-density lipoprotein (LDL) receptor and the human precursor for epidermal growth factor (EGF) show 33 percent identity over a stretch of 400 residues. This region of homology is encoded by eight contiguous exons in each respective gene. Of the nine introns that separate these exons, five are located in identical positions in the two protein sequences. This finding suggests that the homologous region may have resulted from a duplication of an ancestral gene and that the two genes evolved further by recruitment of exons from other genes, which provided the specific functional domains of the LDL receptor and the EGF precursor.
T-Cell Receptor β-Chain Expression: Dependence on Relatively Few Variable Region Genes
Authors: Behlke Mark A. , Spinella Dominic G. , Chou Hubert S. , Sha William , Hartl Daniel L. , Loh Dennis Y.
Published: October 2006

Fifteen independently isolated complementary DNA clones that contain T-cell receptor (TCR) V
β
genes were sequenced and found to represent 11 different V
β
genes. When compared with known sequences, 14 different V
β
genes could be defined from a total of 25 complementary DNA's; 11 clones therefore involved repeated usage of previously identified V
β
's. Based on these data, we calculate a maximum likelihood estimate of the number of expressed germline V
β
genes to be 18 with an upper 95 percent confidence bound of 30 genes. Southern blot analysis has shown that most of these genes belong to single element subfamilies which show very limited interstrain polymorphism. The TCR β-chain diversity appears to be generated from a limited V
β
gene pool primarily by extensive variability at the variable-diversity-joining (V-D-J) junctional site, with no evidence for the involvement of somatic hypermutation.
Complete Development of Hepatic Stages of
Plasmodium falciparum
in Vitro
Authors: Mazier D. , Beaudoin R. L. , Mellouk S. , Druilhe P. , Texier B. , Trosper J. , Miltgen F. , Landau I. , Paul C. , Brandicourt O. , Guguen-Guillouzo C. , Langlois P. , Gentilini M.
Published: October 2006

An in vitro model was developed to study the hepatic phase of
Plasmodium falciparum
, the only malaria parasite lethal to man. Primary cultures of human hepatocytes were inoculated with sporozoites of Brazilian and African strains of
P. falciparum
. On days 1 through 7 after inoculation examination of fluorescence-labeled and Giemsa-stained preparations demonstrated the presence of many intracellular parasites. In three separate sets of experiments all cultures were found to be infected with as many as 650 liver schizonts measuring up to 40 micrometers. After the addition of red blood cells, intraerythrocytic forms of
P. falciparum
were detected on days 12 and 13 by an immunofluorescence assay, indicating that the hepatic cycle had been completed in vitro.
Flow Effects on Prostacyclin Production by Cultured Human Endothelial Cells
Authors: Frangos John A. , Eskin Suzanne G. , McIntire Larry V. , Ives C. L.
Published: October 2006

Endothelial cell functions, such as arachidonic acid metabolism, may be modulated by membrane stresses induced by blood flow. The production of prostacyclin by primary human endothelial cell cultures subjected to pulsatile and steady flow shear stress was measured. The onset of flow led to a sudden increase in prostacyclin production, which decreased to a steady rate within several minutes. The steady-state production rate of cells subjected to pulsatile shear stress was more than twice that of cells exposed to steady shear stress and 16 times greater than that of cells in stationary culture.
Emotion and Facial Efference: A Theory Reclaimed
Authors: Zajonc R. B.
Published: October 2006

A theory of emotional expression, ignored since 1906, holds that facial muscles act as ligatures on facial blood vessels and thereby regulate cerebral blood flow, which, in turn, influences subjective feeling. The theory, developed by Israel Waynbaum, a French physician, hypothesizes the subjective experience of emotions as following facial expression rather than preceding it. It answers Darwin's question of why different muscles contract or relax in different emotions better than Darwin's own theory. When restated in terms of contemporary neurophysiological knowledge, it explains and organizes several ill-understood emotional processes and phenomena.
Expression of Two Variant Surface Glycoproteins on Individual African Trypanosomes During Antigen Switching
Authors: Esser Klaus M. , Schoenbechler Maurice J.
Published: October 2006

Individual
Trypanosoma brucei rhodesiense
organisms were observed in the process of switching variant surface glycoproteins (VSG's). During this switch, trypanosomes simultaneously expressed both pre- and postswitch VSG's uniformly over their surface as detected with monoclonal antibodies. Analysis of this switching event showed that trypanosomes expressing any one of three distinct preswitch VSG's could switch to expression of from one to three different postswitch VSG's. Up to 2.7 percent of the trypanosome population was in the process of switching at one time.
High-Frequency Switching of Colony Morphology in
Candida albicans
Authors: Slutsky Bernice , Buffo Jeffrey , Soll David R.
Published: October 2006

The pathogenic yeast
Candida albicans
switches heritably and at high frequency between at least seven general phenotypes identified by colony morphology on agar. Spontaneous conversion from the original smooth to variant phenotypes (star, ring, irregular wrinkle, hat, stipple, and fuzzy) occurs at a combined frequency of 1.4 × 10
-4
, but is increased 200 times by a low dose of ultraviolet light that kills less than 10 percent of the cells. After the initial conversion, cells switch spontaneously to other phenotypes at a combined frequency of 2 × 10
-2
. Switching is therefore heritable, but also reversible at high frequency. The genetic basis of this newly discovered process and its possible role in Candida pathogenesis are considered.
Bilateral Syringeal Interaction in Vocal Production of an Oscine Bird Sound
Authors: Nowicki Stephen , Capranica Robert R.
Published: October 2006

The vocal organ, or syrinx, of oscine birds has two parts, each of which has generally been presumed to operate independently of the other. A significant counter-example is now demonstrated in the production of a common vocalization by the black-capped chickadee (
Parus atricapillus
), in which the two acoustic sources interact in a nonlinear fashion. This bird produces a sound with multiple frequency components that are heterodyne products resulting from cross-modulation between two signals, thus providing evidence that avian phonation can involve cooperative coupling between the two syringeal sources.
Hemocyanin Respiratory Pigment in Bivalve Mollusks
Authors: Morse M. Patricia , Meyhöfer Edgar , Otto Joann J. , Kuzirian Alan M.
Published: October 2006

Hemocyanins, high molecular weight oxygen-binding proteins, were identified in two species of protobranch bivalve mollusks,
Acila castrensis
and
Yoldia limatula
. Although hemocyanins have been reported in chitons, gastropods, and cephalopods, they have not been observed in the Class Bivalvia. In
A. castrensis
the dissociation products of hemocyanin, characterized by gel electrophoresis, had a subunit molecular weight of approximately 250K. Negatively stained preparations of extracted hemocyanin formed protein aggregates in the shape of cylinders measuring 35 by 38 nanometers. X-ray microanalysis of hemocyanin aggregates in thin sections of
Y. limatula
demonstrated the presence of copper in the molecules. The discovery of hemocyanin in the protobranchs reinforces the primitive nature of the taxon and is further evidence that the major molluscan classes have a common ancestry.
Differential Conditioning of Associative Synaptic Enhancement in Hippocampal Brain Slices
Authors: Kelso Stephen R. , Brown Thomas H.
Published: October 2006

An electrophysiological stimulation paradigm similar to one that produces Pavlovian conditioning was applied to synaptic inputs to pyramidal neurons of hippocampal brain slices. Persistent synaptic enhancement was induced in one of two weak synaptic inputs by pairing high-frequency electrical stimulation of the weak input with stimulation of a third, stronger input to the same region. Forward (temporally overlapping) but not backward (temporally separate) pairings caused this enhancement. Thus hippocampal synapses in vitro can undergo the conditional and selective type of associative modification that could provide the substrate for some of the mnemonic functions in which the hippocampus is thought to participate.
Uncoupling Translocation from Translation: Implications for Transport of Proteins Across Membranes
Authors: Perara Eve , Rothman Richard E. , Lingappa Vishwanath R.
Published: October 2006

The segregation of secretory proteins into the cisternae of the endoplasmic reticulum (ER) is normally tightly coupled to their synthesis. This feature distinguishes their biogenesis from that of proteins targeted to many other organelles. In the examples presented, translocation across the ER membrane is dissociated from translation. Transport, which is normally cotranslational, may proceed in the absence of chain elongation. Moreover, translocation across the ER membrane does not proceed spontaneously since, even in the absence of protein synthesis, energy substrates are required for translocation. These conclusions have been extended to the cotranslational integration of newly synthesized transmembrane proteins.
A Fluorescence Photobleaching Assay of Gap Junction-mediated Communication Between Human Cells
Authors: Wade Margaret H. , Trosko James E. , Schindler Melvin
Published: October 2006

Gap junction-mediated communication between contiguous cells has been implicated in the regulation of cell proliferation and differentiation. This report describes a new technique to measure cell-cell communication, gap fluorescence redistribution after photobleaching, which is based on the diffusion-dependent return of 6-carboxyfluorescein-mediated fluorescence in a photobleached cell that is in contact with other fluorescently labeled cells. Fluorescence recovery rates are interpreted as dye transport across gap junctions. Results of experiments on normal human fibroblasts and human teratocarcinoma cells show that this technique can measure rapid dye transfer and detect inhibition of communication (between teratocarcinoma cells) by the tumor promoters 12-
O
-tetradecanoyl-phorbol-13-acetate and the pesticide dieldrin.
Limits of Neurogenesis in Primates
Authors: Rakic Pasko
Published: October 2006

Systematic analysis of autoradiograms prepared from postpubertal rhesus monkeys given single and multiple injections of tritium-labeled thymidine and killed 3 days to 6 years later displayed a slow turnover of glial cells but failed to reveal any radiolabeled neurons. Therefore, unlike neurons of some nonprimate species, all neurons of the rhesus monkey brain are generated during prenatal and early postnatal life. A stable population of neurons in primates, including humans, may be important for the continuity of learning and memory over a lifetime.
Genotoxicity of Formaldehyde in Cultured Human Bronchial Fibroblasts
Authors: Grafstrom Roland C. , Curren Rodger D. , Yang Li L. , Harris Curtis C.
Published: October 2006

Formaldehyde, a common environmental pollutant, inhibits repair of
O
6
-methylguanine and potentiates the mutagenicity of an alkylating agent,
N
-methyl-
N
-nitrosourea, in normal human fibroblasts. Because formaldehyde alone also causes mutations in human cells, the compound may cause genotoxicity by a dual mechanism of directly damaging DNA and inhibiting repair of mutagenic and carcinogenic DNA lesions caused by other chemical and physical carcinogens.
Neurobiological Bases of Rhythmic Motor Acts in Vertebrates
Authors: Grillner Sten
Published: October 2006

The general principles governing the nervous control of innate motor acts in vertebrates are discussed. Particular consideration is given to the control of locomotion in both mammals and lower vertebrates. One in vitro model of the lamprey central nervous system has been developed. It can be maintained in vitro for several days and the motor pattern underlying locomotion can be elicited in isolated sections of the spinal cord. These findings now allow a detailed analysis of the underlying neural mechanisms. The hypothesis that different parts of the network controlling locomotion can be used in a variety of other motor acts, including learned ones, is reviewed.
Amygdalectomy Impairs Crossmodal Association in Monkeys
Authors: Murray Elisabeth A. , Mishkin Mortimer
Published: October 2006

Monkeys trained on both visual and tactual versions of an object memory task (delayed nonmatching-to-sample) received bilateral ablations of either the amygdaloid complex or the hippocampal formation of the brain. Although both groups performed well on the two intramodal versions (visual-to-visual and tactual-to-tactual), the amygdalectomized monkeys were severely impaired relative to the hippocampectomized monkeys on a crossmodal version (tactual-to-visual). The findings suggest that the amygdala is critical for certain forms of crossmodal association and that the loss of such associations underlies many of the bizarre behaviors that make up the Klüver-Bucy syndrome.
"Where" and "What" in Vision
Authors: Sagi Dov , Julesz Bela
Published: October 2006

The mixture of a few horizontal and vertical line segments embedded in an aggregate of diagonal line segments can be rapidly counted and their positions rapidly determined by a parallel (preattentive) process. However, the discrimination between horizontal and vertical orientation (that is, discrimination of a single conspicuous feature) requires serial search by focal attention. Under recent theories of attention, focal attention has been assumed to be required for the recognition of different combinations of features. According to the findings of this experiment, knowing "what" even a single feature is requires time-consuming search by focal attention. Only knowing "where" a target is is mediated by a parallel process.
Monitoring the Time Course of Cerebral Deoxyglucose Metabolism by
31
P Nuclear Magnetic Resonance Spectroscopy
Authors: Deuel Ruthmary K. , Yue Genevieve M. , Sherman William R. , Schickner David J. , Ackerman Joseph J. H.
Published: October 2006

The phosphorylation of 2-deoxyglucose by the mammalian brain is used as an index of the brain's energy metabolism. The results of phosphorus-31 nuclear magnetic resonance (
31
P NMR) monitoring of conscious animals in vivo showed rapid phosphorylation of 2-deoxyglucose by brain tissue. The rate of phosphorylation as determined by
31
P NMR was consistent with results achieved by tracer methods using carbon-14-labeled 2-deoxyglucose. However, the disappearance of 2-deoxyglucose-6-phosphate was shown to be faster than that reported by tracer studies and occurred without alterations of intracellular pH and energy homeostasis. These results were confirmed by gas chromatography and mass spectroscopy. It is postulated that 2-deoxyglucose may be metabolized in several ways, including dephosphorylation by a hexose phosphatase.