bluuebunny/crossref_metadata_2025 huggingface dataset:
Recognition Sites for Norepinephrine Uptake: Regulation by Neurotransmitter
Authors: Lee Chi-Ming , Javitch Jonathan A. , Snyder Solomon H.
Published: October 2006

Recognition sites for the uptake of norepinephrine on adrenergic neurons in the brain and periphery were labeled with [
3
H]desipramine. The number of these uptake sites varied with the concentration of transmitter; depletion of norepinephrine with reserpine reduced the number of uptake sites, whereas increasing the concentration of norepinephrine induced by treatment with monoamine oxidase inhibitors raised the number of binding sites. These dynamic alterations in norepinephrine uptake recognition sites may regulate synaptic function homeostatically, providing less inactivation of reuptake when the synaptic concentration of the transmitter is low and increased inactivation when it is high.
Polyene Toxicity in Renal Medulla: Injury Mediated by Transport Activity
Authors: Brezis Mayer , Rosen Seymour , Silva Patricio , Spokes Katherine , Epstein Franklin H.
Published: October 2006

Polyene antibiotics such as amphotericin and nystatin increase membrane permeability and thus increase the amount of oxygen consumed in active electrolyte transport. In isolated perfused rat kidneys, the polyenes produced extensive injury to the medullary thick ascending limb, a segment of the nephron with limited oxygen supply. This damage was prevented if reabsorptive transport was inhibited by ouabain. Cell death under these circumstances thus appears to be mediated by increased oxygen demand for transport activity.
Insulin Elicits Ingestion in Decerebrate Rats
Authors: Flynn Francis W. , Grill Harvey J.
Published: October 2006

Insulin administered to rats reliably elicits ingestion of food. To determine whether the neural mechanisms sufficient to control insulin-elicited ingestion are located in or caudal to the forebrain, decerebrate rats were treated with insulin and ingestive responses were measured. Insulin treatment produced hypoglycemia that was comparable, in magnitude and duration, in control and decerebrate rats. Decerebrate and control rats ingested significantly more sucrose solution while hypoglycemic than while normoglycemic. In contrast, insulin did not augment the water consumption of either group. These data indicate that neural systems caudal to the forebrain are sufficient to control ingestive consummatory behavior through the integration of metabolic signals generated by insulin treatment and taste afferent input from the oropharynx.
Spine Stems on Tectal Interneurons in Jewel Fish Are Shortened by Social Stimulation
Authors: Coss Richard G. , Globus Albert
Published: October 2006

Spined pyriform interneurons in community-reared jewel fish have more dendritic branches and spines in the deep tectal layers than those in isolates reared without visual-tactile contact with conspecifics. Furthermore, in the same dendritic loci in which the community-reared fish had more spines, the spine stems were shorter. The findings suggest that social stimulation induces localized formation of spines, which swell with synaptic activation. Shortening of the spine stem through elongated swelling of the spine head is likely to alter synaptic effectiveness through changes in electrotonic conductance.
Somatic Cell Genetics and Gene Families
Authors: D'Eustachio Peter , Ruddle Frank H.
Published: October 2006

The utility of somatic cell genetic analysis for the chromosomal localization of genes in mammals is well established. With the development of recombinant DNA probes and efficient blotting techniques that allow visualization of single-copy cellular genes, somatic cell genetics has been extended from the level of phenotypes expressed by whole cells to the level of the cellular genome itself. This extension has proved invaluable for the analysis of genes not readily expressed in somatic cell hybrids and for the study of multigene families, especially pseudogenes dispersed in different chromosomes throughout the genome.
Auditory Intensity Discrimination at High Frequencies in the Presence of Noise
Authors: Viemeister Neal F.
Published: October 2006

Over a wide range of intensities, subjects were able to detect small differences in the intensity of a high-frequency band of noise that was presented with a relatively intense, complementary band-reject noise. This indicates that neither of two possible mechanisms for peripheral intensity coding, those based on timing and on spread of excitation, is necessary for the large dynamic range of human hearing. It is shown that the information available in the firing rate of a small number of nerve fibers can account for these data.
Microcirculation of the Spleen: An Open or Closed Circulation?
Authors: Chen L-Tsun
Published: October 2006

By injecting plastic microspheres of a specific size (3 to 4 micrometers) into the circulation and following their movement and distribution in the spleen, it was revealed how blood travels from the arterial capillaries to the venous sinuses. This method demonstrated that both open and closed circulation exist in the spleen and that about 90 percent of the blood takes the open route of circulation in the normal unanesthetized rabbit.
4-Nonylphenol in Sewage Sludge: Accumulation of Toxic Metabolites from Nonionic Surfactants
Authors: Giger Walter , Brunner Paul H. , Schaffner Christian
Published: October 2006

Anaerobically treated sewage sludge was found to contain extraordinarily high concentrations of 4-nonylphenol, a metabolite derived from nonionic surfactants of the nonylphenol polyethoxylate type. Concentrations in activated sewage sludge, in mixed primary and secondary sludge, and in aerobically stabilized sludge were substantially lower, suggesting that the formation of 4-nonylphenol is favored under mesophilic anaerobic conditions. Because 4-nonylphenol may be highly toxic to aquatic life, further research is needed on the fate of 4-nonylphenol after sludge is disposed of in the environment.
Immunomicrospheres: Reagents for Cell Labeling and Separation
Authors: Rembaum A. , Dreyer W. J.
Published: October 2006

Immunomicrospheres are specially designed microscopic particles that have antibodies or similar molecules chemically bound to their surfaces. The antibody-coated microspheres react in a highly specific way with target cells, viruses, or other antigenic agents. Immunomicrospheres may be synthesized so that they incorporate compounds that are highly radioactive, intensely fluorescent, magnetic, electron opaque, highly colored, or pharmacologically active. These various types of microspheres may be coated with pure, highly specific monoclonal antibodies obtained by the new hybridoma cell cloning techniques or with conventional antibody preparations. Some of the many present and potential applications for these new reagents are (i) new types of radioimmune or immunofluorescent assays, (ii) improved fluorescence microscopy, (iii) separation of cells on the basis of the fluorescent, electrophoretic, or magnetic properties of bound immunomicrospheres, (iv) markers for use in several types of electron or standard light microscopy, and (v) delivery of lethal compounds to specific undesirable living cells. The combination of the various new types of synthetic microspheres and the newly available homogeneous antibodies offers new opportunities in research, diagnosis, and therapy.
Polyamine Metabolism: A Potential Therapeutic Target in Trypanosomes
Authors: Bacchi C. J. , Nathan H. C. , Hutner S. H. , McCann P. P. , Sjoerdsma A.
Published: October 2006

α-Difluoromethylornithine (RMI 71,782), a specific irreversible inhibitor of the first step in polyamine biosynthesis, that is, the formation of putrescine from ornithine by ornithine decarboxylase, cures mice infected with a virulent, rodent-passaged strain of
Trypanosoma brucei bruce
. This parasite is closely related to the trypanosomes that cause human sleeping sickness. The drug, which is remarkably nontoxic, was effective when administered in drinking water or by intubation. The ability of the compound to inhibit ornithine decarboxylase in vitro was demonstrated by the reduced amounts of putrescine synthesized from tritiated ornithine in
Trypanosoma bruce
suspensions. These observations direct attention to polyamine metabolism as a target for chemotherapy of parasitic diseases.
Fetal Alcohol Syndrome: Embryogenesis in a Mouse Model
Authors: Sulik Kathleen K. , Johnston Malcolm C. , Webb Mary A.
Published: October 2006

When two small doses of ethanol were administered to pregnant mice during the gastrulation stage of embryogenesis, the embryos developed craniofacial malformations closely resembling those seen in the human fetal alcohol syndrome. Striking histological changes appeared in the developing brain (neuroectoderm) within 24 hours of exposure. Decreased development of the neural plate and its derivatives apparently accounts for the craniofacial malformations. The critical exposure period is equivalent to the third week in human pregnancy.
Novel Proteinaceous Infectious Particles Cause Scrapie
Authors: Prusiner Stanley B.
Published: October 2006

After infection and a prolonged incubation period, the scrapie agent causes a degenerative disease of the central nervous system in sheep and goats. Six lines of evidence including sensitivity to proteases demonstrate that this agent contains a protein that is required for infectivity. Although the scrapie agent is irreversibly inactivated by alkali, five procedures with more specificity for modifying nucleic acids failed to cause inactivation. The agent shows heterogeneity with respect to size, apparently a result of its hydrophobicity; the smallest form may have a molecular weight of 50,000 or less. Because the novel properties of the scrapie agent distinguish it from viruses, plasmids, and viroids, a new term "prion" is proposed to denote a small
pro
teinaceous
in
fectious particle which is resistant to inactivation by most procedures that modify nucleic acids. Knowledge of the scrapie agent structure may have significance for understanding the causes of several degenerative diseases.
Midbrain Microinfusions of Prolactin Increase the Estrogen-Dependent Behavior, Lordosis
Authors: Harlan Richard E. , Shivers Brenda D. , Pfaff Donald W.
Published: October 2006

Microinfusions of rat prolactin into the dorsal midbrain of estrogen-treated, ovariectomized rats increased lordosis behavior. Midbrain microinfusions of antiserum to prolactin into rats displaying maximum lordosis had the opposite effect. The distribution of a prolactin-like substance in the brain was studied immunocytochemically. The results suggest that a hypothalamic neuronal system projecting to the midbrain contains a prolactin-like substance that plays a role in facilitating this behavior and therefore may mediate some of the effects of estrogen on the brain. These data, together with others from studies of the prolactin gene and its regulation, indicate that it may be possible to analyze a sequence of molecular events in the brain that facilitate a behavioral response.
Natural Distribution of the
Ixodes dammini
Spirochete
Authors: Bosler Edward M. , Coleman James L. , Benach Jorge L. , Massey Darlene A. , Hanrahan John P. , Burgdorfer Willy , Barbour Alan G.
Published: October 2006

Spirochetes believed to be the cause of Lyme disease were isolated from white-footed mice and white-tailed deer, the preferred natural hosts of
Ixodes dammini
, the tick vector. Evidence suggests that deer act as a reservoir of the disease and provide an overwintering mechanism for both spirochetes and adult ticks. Some tick larvae may acquire the spirochete by transovarial passage and the nymphal stage may transmit the disease to humans.
Selective Photothermolysis: Precise Microsurgery by Selective Absorption of Pulsed Radiation
Authors: Anderson R. Rox , Parrish John A.
Published: October 2006

Suitably brief pulses of selectively absorbed optical radiation can cause selective damage to pigmented structures, cells, and organelles in vivo. Precise aiming is unnecessary in this unique form of radiation injury because inherent optical and thermal properties provide target selectivity. A simple, predictive model is presented. Selective damage to cutaneous microvessels and to melanosomes within melanocytes is shown after 577-nanometer (3 × 10
-7
second) and 351-nanometer (2 × 10
-8
second) pulses, respectively. Hemodynamic, histological, and ultrastructural responses are discussed.
Isolation of Human C-Reactive Protein Complementary DNA and Localization of the Gene to Chromosome 1
Authors: Whitehead Alexander S. , Bruns Gail A. P. , Markham Alexander F. , Colten Harvey R. , Woods Derek E.
Published: October 2006

With a synthetic oligonucleotide mixture as probe, complementary DNA clones of C-reactive protein were isolated from an adult human liver complementary DNA library. The clones ranged in size from 700 to 1100 base pairs and were identified by partial DNA sequence analysis. One complementary DNA clone was used as a probe for hybridization with human-rodent DNA's isolated from somatic cell hybrids and bound to nitrocellulose filters (Southern blot analysis) to assign the human C-reactive protein gene to chromosome 1.
Bioactive Cardiac Substances: Potent Vasorelaxant Activity in Mammalian Atria
Authors: Currie Mark G. , Geller David M. , Cole Barbara R. , Boylan John G. , YuSheng Wu , Holmberg Sandra W. , Needleman Philip
Published: October 2006

Mammalian atrial extracts possess natriuretic and diuretic activity. In experiments reported here it was found that atrial, but not ventricular, extract also causes relaxation of isolated vascular and nonvascular smooth muscle preparations. The smooth muscle relaxant activity of atrial extract was heat-stable and concentration-dependent and could be destroyed with protease. Rabbit aortic and chick rectum strips were used for the detection of atrial biological activity. The atrial activity was separated by column chromatography into two peaks having apparent molecular weights of 20,000 to 30,000 and less than 10,000. The atrial substance that copurified with the smooth muscle relaxant activity in both peaks caused natriuresis when injected into conscious rats. It appears that atria possess at least two peptides that elicit smooth muscle relaxation and natriuresis, suggesting an endogenous system of fluid volume regulation.
Solvent-Accessible Surfaces of Proteins and Nucleic Acids
Authors: Connolly Michael L.
Published: October 2006

A method is presented for analytically calculating a smooth, three-dimensional contour about a molecule. The molecular surface envelope may be drawn on either color raster computer displays or real-time vector computer graphics systems. Molecular areas and volumes may be computed analytically from this surface representation. Unlike most previous computer graphics representations of molecules, which imitate wire models or space-filling plastic spheres, this surface shows only the atoms that are accessible to solvent. This analytical method extends the earlier dot surface numerical algorithm, which has been applied in enzymology, rational drug design, immunology, and understanding DNA base sequence recognition.
Internal Fertilization in an Oviparous Frog
Authors: Townsend Daniel S. , Stewart Margaret M. , Pough F. Harvey , Brussard Peter F.
Published: October 2006

Eleutherodactylus coqui
, an oviparous frog, undergoes internal fertilization. If this mode of fertilization occurs in other species of anurans, interpretations of anuran reproductive strategies based on the assumption of external fertilization must be reviewed.
Industrial Microbiology
Authors: Demain Arnold L.
Published: October 2006

Industrial microbiology has served humanity since prebiblical times, providing fermented beverages and foods to enhance the quality of life. The antibiotic era featured an explosion in the number of microbial products for medicine, nutrition, industry, and research. Revolutionary developments in molecular genetics are propelling the field into a new growth phase with promise of solutions to major world problems.
Darwinism and the Expansion of Evolutionary Theory
Authors: Gould Stephen Jay
Published: October 2006

The essence of Darwinism lies in the claim that natural selection is a creative force, and in the reductionist assertion that selection upon individual organisms is the locus of evolutionary change. Critiques of adaptationism and gradualism call into doubt the traditional consequences of the argument for creativity, while a concept of hierarchy, with selection acting upon such higher-level "individuals" as demes and species, challenges the reductionist claim. An expanded hierarchical theory would not be Darwinism, as strictly defined, but it would capture, in abstract form, the fundamental feature of Darwin's vision—direction of evolution by selection at each level.
The Cholinergic Hypothesis of Geriatric Memory Dysfunction
Authors: Bartus Raymond T. , Dean Reginald L. , Beer Bernard , Lippa Arnold S.
Published: October 2006

Biochemical, electrophysiological, and pharmacological evidence supporting a role for cholinergic dysfunction in age-related memory disturbances is critically reviewed. An attempt has been made to identify pseudoissues, resolve certain controversies, and clarify misconceptions that have occurred in the literature. Significant cholinergic dysfunctions occur in the aged and demented central nervous system, relationships between these changes and loss of memory exist, similar memory deficits can be artificially induced by blocking cholinergic mechanisms in young subjects, and under certain tightly controlled conditions reliable memory improvements in aged subjects can be achieved after cholinergic stimulation. Conventional attempts to reduce memory impairments in clinical trials have not been therapeutically successful, however. Possible explanations for these disappointments are given and directions for future laboratory and clinical studies are suggested.
Behavioral Competition: A Mechanism for Schedule Interactions
Authors: Hinson John M. , Staddon J. E. R.
Published: October 2006

Rats pressing a lever for food reinforcement showed large positive-contrast effects when provided with the opportunity for a competing wheel-running response. Positive and negative behavioral contrast may reflect reallocation of competing interim and terminal responses between schedule components following changes in the reinforcement conditions in one component.
Integrating Visual Information from Successive Fixations
Authors: Jonides John , Irwin David E. , Yantis Steven
Published: October 2006

One of the classic problems in perception is how visual information from successive fixations of a scene is integrated to form a coherent view of the scene. The results of this experiment implicate a process that integrates by summing information from successive fixations after spatially reconciling the information from each glimpse. The output of this process is a memory image that preserves the properly reconciled information from successive fixations.
The Regulation of Infanticide and Parental Behavior: Implications for Reproductive Success in Male Mice
Authors: vom Saal Frederick S. , Howard Lynn S.
Published: October 2006

Infanticide has been proposed to be a pathological response to overcrowding or other forms of environmental stress and thus a maladaptive behavior. However, in male house mice this behavior is predictable and is modulated by learning. Committing infanticide can increase a male's reproductive success and in some situations may therefore be an adaptive behavior.
Proton Nuclear Magnetic Resonance of Intact Friend Leukemia Cells: Phosphorylcholine Increase During Differentiation
Authors: Agris Paul F. , Campbell Iain D.
Published: October 2006

Proton nuclear magnetic resonance of intact Friend leukemia cells was used to analyze their erythroid-like differentiation. The technique, which requires only 10
8
to 10
9
cells and approximately 2 minutes for acquisition of each spectrum, demonstrated the occurrence of many signal changes during differentiation. With cell extracts, 64 signals were assigned to 12 amino acids and 19 other intermediary metabolites, and a dramatic signal change was attributed to a fourfold increase in cytoplasmic phosphorylcholines.
Amplification and Adaptation in Regulatory and Sensory Systems
Authors: Koshland Daniel E. , Goldbeter Albert , Stock Jeffry B.
Published: October 2006

Biological systems respond to sensory inputs and changing metabolic conditions both by amplifying signals and by adapting to them. The mechanisms by which these apparently opposing goals are achieved by the chemistry of the cell are described and evaluated.
Pigeon Perception of Letters of the Alphabet
Authors: Blough Donald S.
Published: October 2006

In a three-choice discrimination task three pigeons learned to distinguish each letter of the alphabet from all other letters. Errors during learning were based on 54 presentations of each target letter with every other letter. The errors were used to scale letters in a multidimensional similarity space and to associate them in hierarchical clusters. The results resembled those generated from similarity judgments by humans, suggesting cross-task and cross-species generality in processes of letter discrimination.
Intracellular Recordings from Cochlear Outer Hair Cells
Authors: Dallos Peter , Santos-Sacchi Joseph , Flock Åke
Published: October 2006

Intracellular recordings were made from outer hair cells in the third turn of the guinea pig cochlea, and the electrical characteristics of the cells were compared to those of inner hair cells, supporting cells, and extracellular spaces from the same recording region. Outer hair cells have higher membrane potentials than do inner hair cells, but they produce smaller a-c receptor potentials. The frequency response characteristics of both types of hair cells are probably not significantly different. In the frequency region where tuning is optimal, both cell types produce depolarizing d-c receptor potentials, but outer hair cells also generate hyperpolarizing responses at low frequencies.
Synchronous Neural Afterdischarges in Rat Hippocampal Slices Without Active Chemical Synapses
Authors: Taylor Charles P. , Dudek F. Edward
Published: October 2006

Extracellular field potential and intracellular recordings from neurons in rat hippocampus show that, even with synaptic transmission blocked, antidromic electrical stimuli can trigger afterdischarges of up to 9 seconds duration; during these discharges action potentials of a single neuron were synchronized with extracellularly recorded population spikes. Apparently mechanisms other than recurrent chemical synapses can synchronize and recruit epileptiform events. Measurements of transmembrane potential indicate that transient extracellular electrical fields (ephaptic interactions) contribute to the observed synchrony; electrotonic coupling and changes in the concentration of extracellular ions may also contribute.
Bovine Babesiosis: Protection of Cattle with Culture-Derived Soluble
Babesia bovis
Antigen
Authors: Smith Ronald D. , James Mark A. , Ristic Miodrag , Aikawa Masamichi , Vega y Murguia Carlos A.
Published: October 2006

Adult Hereford (
Bos taurus
) cattle were protected from severe reactions and death caused by the tick-borne protozoan hemoparasite
Babesia bovis
, 3 months after vaccination with a cell culture—derived immunogen. The immunogen consisted of filtered, freeze-dried supernatant fluid collected from long-term cultures of
Babesia bovis
in vitro. It was reconstituted with saponin adjuvant and injected twice subcutaneously at 2-week intervals. Serum collected from vaccinated cattle caused thickening of the merozoite surface coat, aggregation, and lysis of merozoites in vitro. This reaction was identical to that caused by serum from immune carrier cattle suggesting that the protective antigen present in culture fluids is merozoite surface coat antigen. No mortality occurred among vaccinated cattle, whereas mortality among unvaccinated cattle and
Babesia bigemina
—immune cattle was 62.5 percent indicating that immunity to bovine babesiosis is species-specific.
Influence of Calcium Ion on the Binding of Fibrin Amino Terminal Peptides to Fibrinogen
Authors: Laudano Andrew P. , Doolittle Russell F.
Published: October 2006

The affinity of the amino terminal tetrapeptide of the β chain of fibrin, Gly-His-Arg-Pro, for fibrinogen dramatically increases in the presence of 2 millimolar calcium ion. In contrast, there is no significant increase in the affinity of peptides beginning with the amino terminal sequence of the fibrin α chain, Gly-Pro-Arg, in the presence of calcium ions, although the number of binding sites increases. In the latter case, the increased number of sites is due to the α chain analogs binding to the site ordinarily occupied by the β chain analogs. These results indicate that structures at the amino terminus of the fibrin β chain play a more important role in fibrin polymerization when calcium ions are present.
Normalization by Cell Fusion of Sister Chromatid Exchange in Bloom Syndrome Lymphocytes
Authors: Shiraishi Yukimasa , Matsui Sei-ichi , Sandberg Avery A.
Published: October 2006

Fusion of fresh lymphocytes from a Bloom syndrome (BS) patient with those of normal subjects or a BS heterozygote resulted in complete normalization of the frequency of sister chromatid exchanges in the chromosomes of BS cells. This normalization took place by the first mitosis in hybrid cells. In contrast, cultivation of BS lymphocytes with those of normal subjects or the BS heterozygote had no effect on sister chromatid exchanges. The cell fusion experiments suggest that the normalization of the sister chromatid exchange frequencies in BS cells can be achieved by factors conserved in the cells of various mammalian species. These findings are compatible with the concept that BS is a recessive genetic mutation at regulatory levels of the DNA repair function.
Psychoneuroendocrine Influences on Immunocompetence and Neoplasia
Authors: Riley Vernon
Published: October 2006

Emotional, psychosocial, or anxiety-stimulated stress produces increased plasma concentrations of adrenal corticoids and other hormones through well-known neuroendocrine pathways. A direct consequence of these increased corticoid concentrations is injury to elements of the immunological apparatus, which may leave the subject vulnerable to the action of latent oncogenic viruses, newly transformed cancer cells, or other incipient pathological processes that are normally held in check by an intact immunological apparatus. This article describes studies that examine the adverse effects of increased plasma concentrations of adrenal corticoids on the thymus and thymus-dependent T cells, inasmuch as these elements constitute a major defense system against various neoplastic processes and other pathologies. The studies demonstrate that anxiety-stress can be quantitatively induced and the consequences measured through specific biochemical and cellular parameters, providing that authentic quiescent baselines of these conditions are obtained in the experimental animals by the use of low-stress protective housing and handling techniques.
Chiral Recognition by Nucleosides and Nucleotides: Resolution of Helicenes by High-Performance Liquid Chromatography
Authors: Kim Young Hwan , Tishbee A. , Gil-Av E.
Published: October 2006

Chiral recognition by nucleosides and nucleotides coated on silica gel was studied by high-performance liquid chromatography. Helicenes, which are chiral polyaromatic hydrocarbons, were used as probes. Stereoselectivity was detected when the nucleobase was a purine (adenosine, deoxyadenosine. adenosine 3′-monophosphate. adenosine 5′-monophosphate, adenosine 3′, 5′-monophosphate, and guanosine), but was not detected with the pyrimidine derivative uridine. For a given nucleobase (adenine), all changes in the ribose moiety affected the resolution factors, which ranged between 1.03 and 1.074. These results might be relevant to the enantioselectivity of carcinogenic metabolites of polyaromatic hydrocarbons.
Breast Imaging in Coronal Planes with Simultaneous Pulse Echo and Transmission Ultrasound
Authors: Carson Paul L. , Meyer Charles R. , Scherzinger Ann L. , Oughton Thomas V.
Published: October 2006

Clear delineation of breast architecture was achieved with compound pulse echo ultrasound imaging in which the images were acquired in the coronal planes used for quantitative transmission ultrasonic computed tomography. Since most connective tissue planes in the breast radiate toward the nipple, compound scans from the sides of the breast record normal interfaces more consistently and reveal greater symmetries in normal portions of relatively full breasts than do conventional scans in sagittal or transverse planes. Simultaneous acquisition of the pulse echo images and images representing the local ultrasound attenuation coefficient and speed of ultrasound suggested complementary roles for reflection and through-transmission images in breast cancer detection. The high quality of pulse echo images in coronal planes provides the potential for more complete pulse echo diagnosis and the basis for spatial correlation of lesions viewed in pulse echo and ultrasonic computed tomograms. These observations may permit routine ultrasonic computed tomography of the breast in the clinical setting.
Neuronal Architecture of On and Off Pathways to Ganglion Cells in Carp Retina
Authors: Famiglietti Edward V. , Kaneko Akimichi , Tachibana Masao
Published: October 2006

Bipolar, amacrine, and ganglion cells of carp retina, stained intracellularly with Procion yellow, can be divided into types a and b, according to the destination of terminals and dendritic trees in the inner plexiform layer (sublamina a and b, respectively). Type a cells showed hyperpolarizing, or off, responses and type b cells depolarizing, or on, responses. Carp thus resembles cat in the basic organization of on and off pathways in the retina.
Intraclonal Variation in Proliferative Potential of Human Diploid Fibroblasts: Stochastic Mechanism for Cellular Aging
Authors: Smith James R. , Whitney Ronald G.
Published: October 2006

At several points during the growth of a clone of human embryonic lung fibroblasts in vitro, 100 to 200 cells were removed at random and the proliferative potential of each cell was determined. At each sample point, a wide variation in remaining population doubling ability was observed among the individual cells and the distributions of doubling potentials were distinctly bimodal. Furthermore, the two cells arising from a single mitosis differed in their ability to proliferate by as many as eight population doublings (256-fold in the number of cells produced). The results suggest that a stochastic process is responsible for determining the limited proliferative potential of human embryonic lung fibroblasts.
Genetic Expression of Wilson's Disease in Cell Culture: A Diagnostic Marker
Authors: Chan Wai-Yee , Cushing William , Coffman Mary Ann , Rennert Owen M.
Published: October 2006

Wilson's disease fibroblasts have an elevated intracellular copper concentration as compared to cultured control cells. A decreased ratio of copper to protein was observed in cytoplasmic protein (or proteins) having a molecular weight ≥ 30,000 in Wilson's disease cells. The results of this culture study indicate its potential importance in the early unequivocal diagnosis of this disorder.
Flavin Adenine Dinucleotide—Dependent Monooxygenase: Its Role in the Sulfoxidation of Pesticides in Mammals
Authors: Hajjar Nicolas P. , Hodgson Ernest
Published: October 2006

The flavin adenine dinucleotide-dependent monooxygenase in mammalian hepatic microsomes plays a major role in the oxidative metabolism of thioether-containing pesticides. Thirty-four compounds were tested, and it was determined that organophosphorus insecticides such as disulfoton and phorate are rapidly oxidized by the purified enzyme to their corresponding sulfoxides. The enzyme does not catalyze the oxidation of the thiophosphoryl and thiol sulfur atoms of these or other phosphorothioates and phosphorodithioates, or the oxidation of the sulfoxide to the sulfone. Carbamates aldicarb and Croneton are also oxidized, but at a lower rate.
Cerebral Arteriolar Damage by Arachidonic Acid and Prostaglandin G
2
Authors: Kontos Hermes A. , Wei Enoch P. , Povlishock John T. , Dietrich W. Dalton , Magiera Christopher J. , Ellis Earl F.
Published: October 2006

Application of arachidonic acid or prostaglandin G
2
to the brain surface of anesthetized cats induced cerebral arteriolar damage. Scavengers of free oxygen radicals inhibited this damage. Prostaglandin H
2
, prostaglandin E
2
, and 11,14,17-eicosatrienoic acid did not produce arteriolar damage. It appears that increased prostaglandin synthesis produces cerebral vascular damage by generating free oxygen radicals.
Auditory Brainstem Anomalies in Human Albinos
Authors: Creel Donnell , Garber Sharon R. , King Richard A. , Witkop Carl J.
Published: October 2006

Brainstem auditory evoked potentials recorded from human albinos indicate significant hemispheric asymmetry. The asymmetry is symptomatic of differences between decussated and nondecussated auditory pathways in albino and pigmented humans at approximately the level of the superior olivary nuclei. Abnormal decussation of auditory pathways in albinos probably coincides with known visual system anomalies.
Antibody Targeting of Liposomes: Cell Specificity Obtained by Conjugation of F(ab′)
2
to Vesicle Surface
Authors: Heath Timothy D. , Fraley Robert T. , Papahdjopoulos Demetrios
Published: October 2006

A method devised for conjugating liposomes with protein resulted in the binding of up to 200 micrograms of immunoglobulin G per micromole of lipid. The coupling of antibody to human erythrocyte F(ab′)
2
in vesicles (140 molecules per vesicle) by this method caused a 200-fold increase in the binding of vesicles to human erythrocytes and resulted in about 80 percent of the vesicle lipid and contents being associated with cells.
Nucleosome Cores Have Two Specific Binding Sites for Nonhistone Chromosomal Proteins HMG 14 and HMG 17
Authors: Mardian James K. W. , Paton Arthur E. , Bunick Gerard J. , Olins Donald E.
Published: October 2006

The binding of HMG 14 (or 17) to nucleosome cores produces two major additional bands on nondenaturing polyacrylamide gels. Bound HMG 14 alters the relative densities of the end-labeled DNA fragment distribution produced by deoxyribonuclease I digestion of reconstructed poly(deoxyadenylate-deoxythymidylate) nucleosome cores. These results indicate nucleosome cores have two specific binding sites for HMG 14 (or 17).
Specific Reading Disability: Differences in Contrast Sensitivity as a Function of Spatial Frequency
Authors: Lovegrove W. J. , Bowling A. , Badcock D. , Blackwood M.
Published: October 2006

Contrast thresholds for sine-wave gratings of spatial frequencies of 2, 4, 12, and 16 cycles per degree were determined for normal and disabled readers at a range of stimulus durations. Normal readers demonstrated monotonically decreasing sensitivity with increasing spatial frequency at exposure durations between 40 and 100 milliseconds. At exposure durations of 150 to 1000 milliseconds, they showed peak sensitivity at 4 cycles per degree. In comparison, disabled readers showed monotonically decreasing sensitivity with increasing spatial frequency at all stimulus durations. The difference in sensitivity pattern across spatial frequencies was greatest at stimulus durations approximately equal to fixation durations during reading.
Oral Contraceptives, Lanosterol, and Platelet Hyperactivity in Rat
Authors: Ciavatti M. , Dumont E. , Benoit C. , Renaud S.
Published: October 2006

Lanosterol, a cholesterol precursor that increases considerably in the platelets of rats treated with oral contraceptives, was incubated with either platelet-rich plasma or washed platelet suspension. After 2 minutes there was a remarkable dose-related increase in platelet activity. This platelet hyperactivity as measured by clotting time and platelet aggregation could not be reproduced by cholesterol or ethinylestradiol.
Micromolar Ca
2+
Stimulates Fusion of Lipid Vesicles with Planar Bilayers Containing a Calcium-Binding Protein
Authors: Zimmerberg Joshua , Cohen Fredric S. , Finkelstein Alan
Published: October 2006

Fusion of phospholipid vesicles with a planar phospholipid bilayer membrane that contains a calcium-binding protein appears to mimic the essential aspects of cytoplasmic-vesicle fusion with plasma membranes (exocytosis) in that (i) there is a low basal rate of fusion in the absence of Ca
2+
+, (ii) this basal rate is enormously increased by micromolar (∼ 10 μ
M
) amounts of Ca
2+
+, and (iii) this rate is not increased by millimolar Mg
2+
. Essential to this process is an osmotic gradient across the planar membrane, with the side containing the vesicles hyperosmotic to the opposite side. Similar osmotic gradients or their equivalent may be crucial for biological fusion events.
Sex Differences in Mathematical Ability: Fact or Artifact?
Authors: Benbow Camilla Persson , Stanley Julian C.
Published: October 2006

A substantial sex difference in mathematical reasoning ability (score on the mathematics test of the Scholastic Aptitude Test) in favor of boys was found in a study of 9927 intellectually gifted junior high school students. Our data contradict the hypothesis that differential course-taking accounts for observed sex differences in mathematical ability, but support the hypothesis that these differences are somewhat increased by environmental influences.
Presentation of a Viral T Cell Epitope Expressed in the CDR3 Region of a Self Immunoglobulin Molecule
Authors: Zaghouani Habib , Steinman Ralph , Nonacs Ruta , Shah Himanshu , Gerhard Walter , Bona Constantin
Published: October 2006

Synthetic peptides corresponding to microbial epitopes stimulate T cell immunity but their immunogenicity is poor and their half-lives are short. A viral epitope inserted into the complementarity-determining region 3 (CDR3) loop of the heavy chain of a self immunoglobulin (Ig) molecule was generated from the Ig context and was presented by I-E
d
class II molecules to virus-specific, CD4
+
T cells. Chimeric Ig-peptide was presented 100 to 1000 times more efficiently than free synthetic peptide and was able to prime virus-specific T cells in vivo. These features suggest that antigenized Ig can provide an improved and safe vaccine for the presentation of microbial and other peptides.
CD40 Ligand Gene Defects Responsible for X-Linked Hyper-IgM Syndrome
Authors: Allen R. Cutler , Armitage Richard J. , Conley Mary Ellen , Rosenblatt Howard , Jenkins Nancy A. , Copeland Neal G. , Bedell Mary A. , Edelhoff Susanne , Disteche Christine M. , Simoneaux Denise K. , Fanslow William C. , Belmont John , Spriggs Melanie K.
Published: October 2006

The ligand for CD40 (CD40L) is a membrane glycoprotein on activated T cells that induces B cell proliferation and immunoglobulin secretion. Abnormalities in the CD40L gene were associated with an X-linked immunodeficiency in humans [hyper-IgM (immunoglobulin M) syndrome]. This disease is characterized by elevated concentrations of serum IgM and decreased amounts of all other isotypes. CD40L complementary DNAs from three of four patients with this syndrome contained distinct point mutations. Recombinant expression of two of the mutant CD40L complementary DNAs resulted in proteins incapable of binding to CD40 and unable to induce proliferation or IgE secretion from normal B cells. Activated T cells from the four affected patients failed to express wild-type CD40L, although their B cells responded normally to wild-type CD40L. Thus, these CD40L defects lead to a T cell abnormality that results in the failure of patient B cells to undergo immunoglobulin class switching.
mSlo
, a Complex Mouse Gene Encoding "Maxi" Calcium-Activated Potassium Channels
Authors: Butler Alice , Tsunoda Susan , McCobb David P. , Wei Aguan , Salkoff Lawrence
Published: October 2006

Complementary DNAs (cDNAs) from
mSlo
, a gene encoding calcium-activated potassium channels, were isolated from mouse brain and skeletal muscle, sequenced, and expressed in
Xenopus
oocytes. The
mSlo
-encoded channel resembled "maxi" or BK (high conductance) channel types; single channel conductance was 272 picosiemens with symmetrical potassium concentrations. Whole cell and single channel currents were blocked by charybdotoxin, iberiotoxin, and tetraethylammonium ion. A large number of variant
mSlo
cDNAs were isolated, indicating that several diverse mammalian BK channel types are produced by a single gene.
Ribozymes: A Distinct Class of Metalloenzymes
Authors: Pyle Anna Marie
Published: October 2006

Ribozymes are an important new class of metalloenzymes that have an unlikely feature: they are made entirely of ribonucleic acid (RNA). Metal ions are essential for efficient chemical catalysis by ribozymes and are often required for the stabilization of ribozyme structure. Most ribozymes catalyze reactions at phosphorus centers through one of two major mechanistic pathways, and reaction has been observed at carbon centers. Creative experiments have revealed the position of metal ions in the active site of two ribozymes. The exploitation of variable metal geometry and reactivity has expanded ribozyme chemistry and has facilitated the application of in vitro selection for the creation of novel ribozymes.
Oldest Horse Brains: More Advanced Than Previously Realized
Authors: Radinsky Leonard
Published: October 2006

Previous interpretations of early horse brains were based on an incorrectly identified fossil endocast, now believed to be from a condylarth. Newly prepared endocasts of
Hyracotherium
, the oldest horse and one of the earliest perissodactyls, reveal a relatively larger brain, with a more expanded neocortex, than existed in the condylarth ancestors of perissodactyls. Fifty million years ago, horse brains had suprasylvian, ectolateral, and lateral sulci, but the frontal lobe was undeveloped.
Biodegradable Long-Circulating Polymeric Nanospheres
Authors: Gref Ruxandra , Minamitake Yoshiharu , Peracchia Maria Teresa , Trubetskoy Vladimir , Torchilin Vladimir , Langer Robert
Published: October 2006

Injectable nanoparticulate carriers have important potential applications such as site-specific drug delivery or medical imaging. Conventional carriers, however, cannot generally be used because they are eliminated by the reticulo-endothelial system within seconds or minutes after intravenous injection. To address these limitations, monodisperse biodegradable nanospheres were developed from amphiphilic copolymers composed of two biocompatible blocks. The nanospheres exhibited dramatically increased blood circulation times and reduced liver accumulation in mice. Furthermore, they entrapped up to 45 percent by weight of the drug in the dense core in a one-step procedure and could be freeze-dried and easily redispersed without additives in aqueous solutions.
An Antiviral Soluble Form of the LDL Receptor Induced by Interferon
Authors: Fischer Dina G. , Tal Nathan , Novick Daniela , Barak Sara , Rubinstein Menachem
Published: October 2006

Interferons, which induce several intracellular antiviral proteins, also induce an extracellular soluble protein that inhibits vesicular stomatitis virus (VSV) infection. This 28-kilodalton soluble protein was purified to homogeneity and identified by protein sequencing as the ligand-binding domain of the human 160-kilodalton low density lipoprotein receptor (LDLR). The existence of an antiviral soluble LDLR was confirmed by immunoaffinity chromatography with monoclonal antibody to LDLR. This soluble receptor mediates most of the interferon-triggered antiviral activity against VSV, apparently by interfering with virus assembly or budding, and not by inhibiting virus attachment to cells.
Arabidopsis
Ethylene-Response Gene
ETR1
: Similarity of Product to Two-Component Regulators
Authors: Chang Caren , Kwok Shing F. , Bleecker Anthony B. , Meyerowitz Elliot M.
Published: October 2006

Ethylene behaves as a hormone in plants, regulating such aspects of growth and development as fruit ripening, flower senescence, and abscission. Ethylene insensitivity is conferred by dominant mutations in the
ETR1
gene early in the ethylene signal transduction pathway of
Arabidopsis thaliana
. The
ETR1
gene was cloned by the method of chromosome walking. Each of the four known
etr1
mutant alleles contains a missense mutation near the amino terminus of the predicted protein. Although the sequence of the amino-terminal half of the deduced ETR1 protein appears to be novel, the carboxyl-terminal half is similar in sequence to both components of the prokaryotic family of signal transducers known as the two-component systems. Thus, an early step in ethylene signal transduction in plants may involve transfer of phosphate as in prokaryotic two-component systems. The dominant
etr1-1
mutant gene conferred ethylene insensitivity to wild-type
Arabidopsis
plants when introduced by transformation.
WT1
-Mediated Growth Suppression of Wilms Tumor Cells Expressing a
WT1
Splicing Variant
Authors: Haber Daniel A. , Park Seon , Maheswaran Shyamala , Englert Christoph , Re Gian G. , Hazen-Martin Debra J. , Sens Donald A. , Garvin A. Julian
Published: October 2006

A human Wilms tumor cell line (RM1) was developed to test the tumor suppressor activity of WT1, a zinc finger transcription factor that is expressed in the developing human kidney and is mutationally inactivated in a subset of Wilms tumors. Transfection of each of four wild-type
WT1
isoforms suppressed the growth of RM1 cells. The endogenous
WT1
transcript in these cells was devoid of exon 2 sequences, a splicing alteration that was also detected in varying amounts in all Wilms tumors tested but not in normal kidney. Production of this abnormal transcript, which encodes a functionally altered protein, may represent a distinct mechanism for inactivating
WT1
in Wilms tumors.
Marek's Disease: Effects of
B
Histocompatibility Alloalleles in Resistant and Susceptible Chicken Lines
Authors: Briles W. Elwood , Stone Howard A. , Cole R. K.
Published: October 2006

Lines of chickens selected from a common ancestral population for either resistance or susceptibility to Marek's disease developed contrasting frequencies of particular
B
alloalleles. Comparison of inoculated sibs in backcross-families revealed that the
B
alloalleles characterizing the two lines accounted for an eightfold difference in tumor incidence. This genetic difference in tumorigenesis associated with the alloalleles of the major histocompatibility complex is probably expressed through the cell-mediated immune system.
Arrestin Function in Inactivation of G Protein-Coupled Receptor Rhodopsin in Vivo
Authors: Dolph Patrick J. , Ranganathan Rama , Colley Nansi J. , Hardy Robert W. , Socolich Michael , Zuker Charles S.
Published: October 2006

Arrestins have been implicated in the regulation of many G protein-coupled receptor signaling cascades. Mutations in two
Drosophila
photoreceptor-specific arrestin genes,
arrestin 1
and
arrestin 2
, were generated. Analysis of the light response in these mutants shows that the
Arr1
and
Arr2
proteins are mediators of rhodopsin inactivation and are essential for the termination of the phototransduction cascade in vivo. The saturation of arrestin function by an excess of activated rhodopsin is responsible for a continuously activated state of the photoreceptors known as the prolonged depolarized afterpotential. In the absence of arrestins, photoreceptors undergo light-dependent retinal degeneration as a result of the continued activity of the phototransduction cascade. These results demonstrate the fundamental requirement for members of the arrestin protein family in the regulation of G protein-coupled receptors and signaling cascades in vivo.