bluuebunny/crossref_metadata_2025 huggingface dataset:
Acetylcholine Synthesis in Synaptosomes: Mode of Transfer of Mitochondrial Acetyl Coenzyme A
Authors: Benjamin A. M. , Quastel J. H.
Published: October 2006

Labeled acetylcholine derived from labeled pyruvate in a synaptosomal preparation from rat brain, incubated with nicotinamide adenine dinucleotide as well as coenzyme A, is stimulated by calcium ions in the absence but not in the presence of Triton X-100. Whereas citrate is taken up by cholinergic synaptosomes because it suppresses the formation of acetylcholine from pyruvate, it is not itself converted into acetylcholine. The evidence suggests that there is a calcium-dependent transfer of mitochondrial acetyl coenzyme A into the cholinergic synaptoplasm, which is apparently devoid of the citrate cleavage enzyme, and is there converted into acetylcholine. The permeability of the inner mitochondrial membrane to coenzyme A and acetyl coenzyme A seems to be enhanced by calcium ions, and this effect may be mediated by mitochondrial phospholipase A
2
.
Cellular Aging: Further Evidence for the Commitment Theory
Authors: Holliday R. , Huschtscha L. I. , Kirkwood T. B. L.
Published: October 2006

A large, transient reduction in the population size of human fibroblasts in early passages significantly increases the variability of the life-spans of cultures in comparison to control cultures, as predicted by the commitment theory of cellular aging. The theory also predicts that a constant population of noncycling cells will appear in the later part of the culture life-span. This was confirmed by labeling the cells in culture with tritiated thymidine.
Adenosine Triphosphate-Deficient Erythrocytes of the Egg-Laying Mammal, Echidna (
Tachyglossus aculeatus
)
Authors: Kim H. D. , Zeidler R. B. , Sallis J. D. , Nichol S. C. , Isaacks R. E.
Published: October 2006

The erythrocytes of the short-beaked echidna (
Tachyglossus aculeatus
), an egg-laying mammal, were examined for the presence of phosphorylated compounds. The erythrocytes contained only 0.03 ± 0.01 micromoles of adenosine 5′-triphosphate per milliliter of cells. This amount is two orders of magnitude less than that in human cells. Although the echidna erythrocytes had an abundance of 2,3-diphosphoglycerate and other glycolytic intermediates, no other energy-rich pyridine and purine compounds were detected.
An Efference Copy Which Is Modified by Reafferent Input
Authors: Bell Curtis C.
Published: October 2006

In electric fish of the mormyrid family, an efference copy is present in the brain region that receives afferent input from ampullary electroreceptors. The efference copy is elicited by the motor command to fire the electric organ. Its effect is always opposite that of ampullary afferents responding to the electric organ discharge, and it changes to match variations in this afferent input. It probably reduces the central effects of activity in ampullary receptors evoked by the electric organ discharge.
Induction of Invagination in Insect Epithelium: Paradigm for Embryonic Invagination
Authors: Nardi James B.
Published: October 2006

The proposal that adhesive disparities between inpocketing populations of cells and surrounding epithelia drive epithelial invagination was tested in grafting experiments with moth pupal wing epithelium. Evidence exists that a cellular adhesiveness gradient spans the proximodistal axis of the wing. Although pupal wing cells normally do not invaginate or evaginate, epithelial folding can be induced after exchange of grafts from opposite ends of the proximodistal axis. The hypothesis that cytoskeletal elements are the primary agents in epithelial invagination should be reevaluated.
Heparin Facilitates the Extraction of Tissue Fibronectin
Authors: Bray Bonnie Anderson , Mandl Ines , Turino Gerard M.
Published: October 2006

Extraction of fibronectin from two human tissues, lung parenchyma and placental villi, was facilitated by the incorporation of heparin into extraction media. The effect of heparin was additive to the effect of urea which is known to extract fibronectin. These experiments provide further evidence that fibronectin and glycosaminoglycans are associated in connective tissues and the use of heparin forms the basis for a simple method for extraction and quantitation of tissue fibronectin.
Epithelial Cell Volume Regulation: Bicarbonate Dependence
Authors: Fisher R. S. , Persson B.-E. , Spring K. R.
Published: October 2006

When
Necturus
gallbladder epithelial cells are osmotically shrunken, they rapidly return to their original volume despite the continued presence of a hypertonic bathing solution. This volume-regulatory process requires bicarbonate ions in the bathing solutions and is associated with the uptake of chloride ions. Volume-regulatory increase by epithelial cells is probably due to the parallel operation of sodium-hydrogen and chloride-bicarbonate exchangers in the apical cell membrane.
Side-Effect Reduction by Use of Drugs That Bind to Separate But Equivalent Binding Sites
Authors: Ehrenstein Gerald , Huang Li-Yen
Published: October 2006

If two drugs cause the same molecular effect by binding to separate noncompetitive binding sites, therapy with a mixture of the two drugs can provide a given desired effect with a lower level of side effects than therapy with either drug alone.
A Brain for All Seasons: Cyclical Anatomical Changes in Song Control Nuclei of the Canary Brain
Authors: Nottebohm Fernando
Published: October 2006

Male canaries that have reached sexual maturity can, in subsequent years, learn new song repertoires. Two telencephalic song control nuclei, the hyperstriatum ventrale, pars caudale, and nucleus robustus archistriatalis are, respectively, 99 and 76 percent larger in the spring, when male canaries are producing stable adult song, than in the fall, at the end of the molt and after several months of not singing. It is hypothesized that such fluctuations reflect an increase and then reduction in numbers of synapses and are related to the yearly ability to acquire new motor coordinations.
Mouse Interferons: Amino Terminal Amino Acid Sequences of Various Species
Authors: Taira Hideharu , Broeze Robert J. , Jayaram Bettadapura M. , Lengyel Peter , Hunkapiller Michael W. , Hood Leroy E.
Published: October 2006

Mouse interferons of three size classes (A, 35,000 to 40,000 daltons; B, 26,000 to 33,000 daltons; and C, 20,000 daltons) were purified from Ehrlich ascites tumor cells infected with Newcastle disease virus. The sequences of the first 24 amino acids (No. 17 has not been identified) of interferons A and B are identical. The sequence of the first 20 amino acids of interferon C differs from that of A and B in 18 positions. There is partial homology in amino terminal sequence between mouse interferons A (or B) and a human fibroblast interferon and between mouse interferon C and a human lymphoblastoid interferon.
Bronchodilatation: Noncholinergic, Nonadrenergic Mediation Demonstrated in Vivo in the Cat
Authors: Irvin Charles G. , Boileau Robert , Tremblay Jacques , Martin Richard R. , Macklem Peter T.
Published: October 2006

The composite vagus nerve was stimulated during intravenous infusion of 5-hydroxytryptamine in cats subjected to pharmacologic autonomic blockade with atropine, propranolol, and phentolamine. Bronchial caliber, as assessed by changes in pulmonary resistance, demonstrated a marked dilatation, and dilatation could still be demonstrated after preliminary treatment with reserpine. By stimulating the component branches of the vagus nerve, it was determined that the parasympathetic branch is responsible for this phenomenon.
Eyeblinks and Visual Suppression
Authors: Volkmann Frances C. , Riggs Lorrin A. , Moore Robert K.
Published: October 2006

A technique for bypassing the eyelids permits equivalent visual stimulation of the retina before, during, or after a blink. Sensitivity to these stimuli decreases during voluntary blinks. This indicates that the source of the deficit is neural rather than optical. Such a visual loss may help to explain the common experience that most blinks go unnoticed.
Do the Two Eyes Constitute Separate Visual Channels?
Authors: Cormack Robert H. , Blake Randolph
Published: October 2006

A two-interval forced-choice procedure was used to study monocular detection of a briefly presented low-contrast sine-wave grating pattern. Uncertainty about which eye was stimulated degraded detection performance for stereoblind observers but not for normal ones. These results relate to selective monocular suppression, stereopsis, and other forms of binocular interaction and suggest the level at which inputs to the two eyes are combined neurally.
Magnetic Field of a Nerve Impulse: First Measurements
Authors: Wikswo John P. , Barach John P. , Freeman John A.
Published: October 2006

The magnetic field of the action potential from an isolated frog sciatic nerve was measured by a SQUID magnetometer with a novel room-temperature pickup coil. The 1.2 × 10
-10
tesla field was measured 1.3 millimeters from the nerve with a signal-to-noise ratio of 40 to 1.
Faster Cholinergic REM Sleep Induction in Euthymic Patients with Primary Affective Illness
Authors: Sitaram N. , Nurnberger John I. , Gershon Elliot S. , Gillin J. Christian
Published: October 2006

Arecoline, a cholinergic muscarinic receptor agonist, induced rapid eye movement sleep significantly more rapidly in patients with primary affective illness in remission than in normal control subjects matched for age and sex. These results, and others, suggest that patients with primary affective illness may have a supersensitive cholinergic system both when they are ill and when their symptoms are in clinical remission.
Saccadic Eye Movements and Body Sway
Authors: White Keith D. , Post R. B. , Leibowitz H. W.
Published: October 2006

Different conditions of moving retinal images show differential influences on postural stability. A surrounding pattern moved during steady fixation increases body sway, but similar image motions generated by voluntary saccades do not. Mechanisms for postural control do not respond to visual feedback during saccades. Analogous principles in saccadic suppression and space constancy are discussed.
Antibody to Spermine: A Natural Biological Constituent
Authors: Bartos D. , Bartos F. , Campbell R. A. , Grettie D. P. , Smejtek P.
Published: October 2006

A protein that binds spermine specifically was separated from normal rabbit serum by affinity chromatography. Immunoelectrophoresis, the Ouchterlony immunodiffusion test, and gradient gel electrophoresis indicated that this protein has immunoglobulin characteristics and consists of several populations of antibodies to spermine. These were sequentially released from Sepharose-spermine gel by step-wise elution with solutions ranging in
p
H from 4 to 1. The binding constants varied from 5.0 × 10
-8
to 11.1 × 10
-8
liters per mole. These globulins did not react with monoacetylputrescine, L-ornithine, L-lysine, and histamine. Negligible cross-reactivity was detected with spermidine, putrescine, N
8
-monoacetylspermidine, cadaverine, and diaminopropane. Since perturbations in polyamine metabolism have been identified in several diseases, the study of extracellular polyamine homeostasis may reveal an important regulatory function for this protein.
Acquisition of a Memory Skill
Authors: Ericsson K. Anders , Chase William G. , Faloon Steve
Published: October 2006

After more than 230 hours of practice in the laboratory, a subject was able to increase his memory span from 7 to 79 digits. His performance on other memory tests with digits equaled that of memory experts with lifelong training. With an appropriate mnemonic system, there is seemingly no limit to memory performance with practice.
Biomedical Implantable Microelectronics
Authors: Meindl James D.
Published: October 2006

Innovative applications of microelectronics in new biomedical implantable instruments offer a singular opportunity for advances in medical research and practice because of two salient factors: (i) beyond all other types of biomedical instruments, implants exploit fully the inherent technical advantages—complex functional capability, high reliability, lower power drain, small size and weight—of microelectronics, and (ii) implants bring microelectronics into intimate association with biological systems. The combination of these two factors enables otherwise impossible new experiments to be conducted and new prostheses developed that will improve the quality of human life.
Lithium Reduces the Number of Acetylcholine Receptors in Skeletal Muscle
Authors: Pestronk Alan , Drachman Daniel B.
Published: October 2006

Extended treatment of rats with lithium inhibits the increase in the number of extrajunctional acetylcholine receptors that occurs in their denervated skeletal muscle. In normal muscle, lithium reduces the number of acetylcholine receptors at neuromuscular junctions. These changes appear to be a relatively specific effect of lithium on the turnover of receptors. Skeletal muscle provides an accessible system for analyzing the role of lithium (and other cations) in the regulation of cell surface receptors. This regulation may play a role in the mechanism by which lithium prevents recurrent manic-depressive episodes.
Subcellular Origin of Cholinergic Transmitter Release from Mouse Brain
Authors: Carroll Paul T. , Aspry Jo-Anne M.
Published: October 2006

Samples of minced mouse forebrain were treated in a way that resulted in a high ratio of false cholinergic transmitter (acetylhomocholine) to true transmitter (acetylcholine) in a synaptic vesicle fraction, and a low ratio of false to true transmitter in the nerve terminal cytoplasm. The spontaneous release of cholinergic transmitters from this minced tissue occurred independently of calcium and had a ratio of false to true transmitter similar to that of the cytoplasm, whereas the evoked transmitter release required calcium and had a ratio of false to true transmitter similar to that of the vesicular fraction.
Nigral Dopamine Neurons: Intracellular Recording and Identification with L-Dopa Injection and Histofluorescence
Authors: Grace Anthony A. , Bunney Benjamin S.
Published: October 2006

Intracellular recordings in vivo were obtained from dopamine-containing neurons of the rat substantia nigra. These neurons were identified electrophysiologically by antidromic activation and histochemically by L-dopa injection and subsequent fluorescence histochemistry. Extracellular spikes and antidromic conduction velocity of the neurons were identical to those previously described for putative dopaminergic neurons. Spontaneous intracellular fast potentials, slow depolarizations during burst firing, and spike prepotentials were observed.
Exposure of Newborn Rats to Pharmacologically Active Compounds May Permanently Alter Carcinogen Metabolism
Authors: Faris Ronald A. , Campbell T. Colin
Published: October 2006

Administration of phenobarbital to mother rats during early lactation causes long-term, perhaps permanent, alteration of hepatic microsomal mixed-function oxidase activity and aflatoxin B
1
adduct formation in the adult male offspring. These findings suggest that perinatal exposure to pharmacologically active compounds may be a determinant of cancer risk.
Rapid Induction of Cellular Strain Specificity by Newly Acquired Cytoplasmic Components in Amoebas
Authors: Lorch I. Joan , Jeon Kwang W.
Published: October 2006

A new strain-specific character was induced in amoebas by bacterial endosymbionts after only 10 to 15 cell generations of symbiosis. The nuclei of changed amoebas not only became incompatible with the cytoplasm of the original strain, but also exerted a strong lethal effect on intact amoebas of the same original strain.
Conversion of 3T3-L1 Fibroblasts to Fat Cells by an Inhibitor of Methylation: Effect of 3-Deazaadenosine
Authors: Chiang Peter K.
Published: October 2006

3-Deazaadenosine, an inhibitor of methylation, increased the frequency of conversion of 3T3-L1 fibroblasts to fat cells in a dose-dependent manner. Once converted, the 3T3-L1 fat cells retained their adipose morphology and accumulated triglycerides even when 3-deazaadenosine was removed from the culture medium. 3-Deazaadenosine may perturb cellular methylation and thereby lead to an increase in the frequency of differentiation of 3T3-L1 fibroblasts to fat cells.
RNAs with Dual Specificity and Dual RNAs with Similar Specificity
Authors: Connell Gregory J. , Yarus Michael
Published: October 2006

The biological role of RNA is delimited by its possible reactions, which can be explored by selection. A comparison of selected RNAs that bind one ligand with those that bind two related ligands suggests that a single nucleotide substitution can expand binding specificity. An RNA site with dual (joint) specificity has adenine and cytosine bases whose p
K
a
's appear shifted upward, thereby mimicking an efficient general acid-base catalyst. The joint site also contains two conserved, looped arginine-coding triplets implicated in arginine site formation. Two selected joint RNAs are identical in some regions and distinct in others. The distinct regions, like some peptides, seem to function similarly without being similar in primary structure.
Sensing Starvation: a Homoserine Lactone—Dependent Signaling Pathway in
Escherichia coli
Authors: Huisman Gjalt W. , Kolter Roberto
Published: October 2006

When nutrients become limiting, many bacteria differentiate and become resistant to environmental stresses. For
Escherichia coli
, this process is mediated by the σ
s
subunit of RNA polymerase. Expression of σ
s
was induced by homoserine lactone, a metabolite synthesized from intermediates in threonine biosynthesis. Homoserine lactone-dependent synthesis of σ
s
was prevented by overexpression of a newly identified protein, RspA. The function of homoserine lactone derivatives in many cell density-dependent phenomena and the similarity of RspA to a
Streptomyces ambofaciens
protein suggest that synthesis of homoserine lactone may be a general signal of starvation.
Chemotactic Factor-Induced Release of Membrane Calcium in Rabbit Neutrophils
Authors: Naccache P. H. , Volpi M. , Showell H. J. , Becker E. L. , Sha'afi R. I.
Published: October 2006

The interaction of chemotactic factors (fMet-Leu-Phe and C5a) with rabbit neutrophils leads to rapid and specific release of membrane calcium, as evidenced by changes in the fluorescence of cell-associated chlorotetracycline. These two structurally different stimuli appear to interact with the same pool of membrane calcium.
Protein Enhancement of Hammerhead Ribozyme Catalysis
Authors: Tsuchihashi Zenta , Khosla Mala , Herschlag Daniel
Published: October 2006

When the recognition sequence of a ribozyme is extended beyond a certain length, turnover is slowed and specificity is decreased. Here, it is shown that a protein can help a ribozyme overcome these general limitations on ribozyme activity. Cleavage of an RNA oligonucleotide by a hammerhead ribozyme is enhanced 10- to 20-fold upon addition of a protein derived from the p7 nucleocapsid (NC) protein of human immunodeficiency virus-type 1. The NC protein also enhances the ability of the ribozyme to discriminate between cleavage of RNA oligonucleotides with differing sequences. These catalytic improvements can be attributed to the strand exchange activity of this RNA binding protein. It is conceivable that endogenous or added proteins may provide analogous increases in ribozyme activity and specificity in vivo.
Uncovering of Functional Alternative CTLA-4 Counter-Receptor in B7-Deficient Mice
Authors: Freeman Gordon J. , Borriello Frank , Hodes Richard J. , Reiser Hans , Hathcock Karen S. , Laszlo Gloria , McKnight Andrew J. , Kim Jinny , Du Lina , Lombard David B. , Gray Gary S. , Nadler Lee M. , Sharpe Arlene H.
Published: October 2006

B7 delivers a costimulatory signal through CD28, resulting in interleukin-2 secretion and T cell proliferation. Blockade of this pathway results in T cell anergy. The in vivo role of B7 was evaluated with B7-deficient mice. These mice had a 70 percent decrease in costimulation of the response to alloantigen. Despite lacking B7 expression, activated B cells from these mice bound CTLA-4 and GL1 monoclonal antibody, demonstrating that alternative CTLA-4 ligand or ligands exist. These receptors are functionally important because the residual allogenic mixed lymphocyte responses were blocked by CTLA4Ig. Characterization of these CTLA-4 ligands should lead to strategies for manipulating the immune response.
Besnoitia Species (Protozoa, Sporozoa, Toxoplasmatidae): Recognition of Cyclic Transmission by Cats
Authors: Wallace G. D. , Frenkel J. K.
Published: October 2006

Isosporan oocysts, measuring 13 by 16 micrometers, from a cat in Hawaii produced
Besnoitia
cysts in tissues of mice and rats. Feeding these cysts to cats led to oocyst shedding after 11 to 13 days, continuing for a mean of 11 days. This indicates a two-host cycle for
Besnoitia
, adding an intestinal phase and oocyst production by a carnivore to the already known tissue stages. Thus a representative of
Besnoitia
, similar to other species in cattle, horses, reindeer, impala, other mammals, and reptiles, has been shown to be a coccidian of cats, capable of being spread by fecal contamination.
Besnoitia
is the fourth mammalian tissue parasite, together with
Toxoplasma
,
Hammondia
, and
Sarcocystis
, found to produce isosporan-type oocysts.
Induction of Type I Diabetes by Interferon-α in Transgenic Mice
Authors: Stewart T. A. , Hultgren B. , Huang X. , Pitts-Meek S. , Hully J. , MacLachlan N. J.
Published: October 2006

Type I diabetes is an autoimmune disease involving an interaction between an epigenetic event (possibly a viral infection), the pancreatic β cells, and the immune system in a genetically susceptible host. The possibility that the type I interferons could mediate this interaction was tested with transgenic mice in which the insulin-producing β cells expressed an interferon-α. These mice developed a hypoinsulinemic diabetes associated with a mixed inflammation centered on the islets. The inflammation and the diabetes were prevented with a neutralizing antibody to the interferon-α. Thus, the expression of interferon-α by the β cells could be causal in the development of type I diabetes, which suggests a therapeutic approach to this disease.
Protein-Protein Interactions Contributing to the Specificity of Intracellular Vesicular Trafficking
Authors: Calakos Nicole , Bennett Mark K. , Peterson Karen E. , Scheller Richard H.
Published: October 2006

Intracellular vesicles destined to fuse with the plasma membrane and secrete their contents must have a mechanism for specifically interacting with the appropriate target membrane. Such a mechanism is now suggested by the demonstration of specific interaction between vesicular proteins and plasma membrane proteins. The vesicle-associated membrane proteins (VAMPs) 1 and 2 specifically bind the acceptor membrane proteins syntaxin 1A and 4 but not syntaxin 2 or 3. The binding site is within amino acids 194 to 267 of syntaxin 1A, and the approximate equilibrium dissociation constant is 4.7 × 10
-6
molar. These data suggest a physical basis for the specificity of intracellular vesicular transport.
Structural Features of Polysaccharides That Induce Intra-Abdominal Abscesses
Authors: Tzianabos Arthur O. , Onderdonk Andrew B. , Rosner Bernard , Cisneros Ronald L. , Kasper Dennis L.
Published: October 2006

The capsular polysaccharide complex from
Bacteroides fragilis
promotes the formation of intra-abdominal abscesses—a pathologic host response to infecting microorganisms. This complex consists of two distinct polysaccharides, each with repeating units that have positively charged amino groups and negatively charged carboxyl or phosphate groups. Analysis of these polysaccharides as well as other charged carbohydrates before and after chemical modification revealed that these oppositely charged groups are required for the induction of intra-abdominal abscesses in a rat model.
Mutations in the Glucose-6-Phosphatase Gene that Cause Glycogen Storage Disease Type 1a
Authors: Lei Ke-Jian , Shelly Leslie L. , Pan Chi-Jiunn , Sidbury James B. , Chou Janice Yang
Published: October 2006

Glycogen storage disease (GSD) type 1a is caused by the deficiency of D-glucose-6-phosphatase (G6Pase), the key enzyme in glucose homeostasis. Despite both a high incidence and morbidity, the molecular mechanisms underlying this deficiency have eluded characterization. In the present study, the molecular and biochemical characterization of the human G6Pase complementary DNA, its gene, and the expressed protein, which is indistinguishable from human microsomal G6Pase, are reported. Several mutations in the G6Pase gene of affected individuals that completely inactivate the enzyme have been identified. These results establish the molecular basis of this disease and open the way for future gene therapy.
Complete Covalent Structure of a Human IgA1 Immunoglobulin
Authors: Liu Yu-Sheng Victor , Low Teresa L. K. , Infante Anthony , Putnam Frank W.
Published: October 2006

The complete covalent structure has been determined for a human myeloma IgA1 immunoglobulin. This protein has unique features in the amino acid sequence and disulfide bridge structure of the variable (V) and constant (C) regions of both the α heavy and the λ light chains, and in the number and loci of oligosaccharides. Whereas C region domains of heavy chains have evolved independently over eons, recent isotypic variations have occurred in λ light chains and possibly in α heavy chains.
Membrane Glycolipids: Regional Synthesis and Axonal Transport in a Single Identified Neuron of
Aplysia californica
Authors: Sherbany Ariel A. , Ambron Richard T. , Schwartz James H.
Published: October 2006

Glycolipids moving along an identified axon of
Aplysia californica
were synthesized and incorporated into intracytoplasmic membranes solely in the perikaryon: direct injection of tritiated sugar into the axon revealed no local synthesis or exchange. There was no indication for transfer into axoplasm from glia. Insertion of glycolipids into nascent membranes occurs coordinately with insertion of protein components in the cell body.
Morphine Lowering of Self-Stimulation Thresholds: Lack of Tolerance with Long-Term Administration
Authors: Esposito Ralph , Kornetsky Conan
Published: October 2006

Rats were given increasing amounts of morphine over a period of weeks in order to achieve tolerance. Doses of the drug which initially reduced the threshold for self-stimulation behavior continued to do so after long-term administration. These results demonstrate a persistent central effect of morphine which may be related to the opiate "high."
Socially Induced Inhibition of Genetically Determined Maturation in the Platyfish,
Xiphophorus maculatus
Authors: Sohn Joel J.
Published: October 2006

Maturation in
Xiphophorus maculatus
(Pisces; Poeciliidae) is under control of the sex-linked
P
gene. However, when two individuals are reared together the socially dominant individual delays the maturation of the subordinate. Nevertheless, it is not a requirement that a fish be socially dominant to become mature. The data suggest that inhibition of maturity takes place when an individual is not dominant at a time near the genetically determined age of maturation. Two hypotheses are offered to explain these results.
Primary Structure of Cholera Toxin β-Chain: A Glycoprotein Hormone Analog?
Authors: Kurosky Alexander , Markel Daiel E. , Peterson Johnny W. , Fitch Walter M.
Published: October 2006

The completed sequence of the β-chain of cholera toxin (103 amino acid residues) was compared to the β-chains of chorionic gonadotropin, thyrotropin, luteinizing, and follicle stimulating hormones. The overall chemical similarity of the toxin β-chain to the hormones was not statistically different from random; however, a comparison of the first 40 residues of the toxin β-chain to the glycoprotein hormones revealed a segment of the hormones which was significantly chemically similar. The probability was < .003 that the similarity was due to chance.
Lateral Diffusion in Planar Lipid Bilayers
Authors: Fahey P. F. , Koppel D. E. , Barak L. S. , Wolf D. E. , Elson E. L. , Webb W. W.
Published: October 2006

Direct measurements by fluorescence correlation spectroscopy of lateral diffusion coefficients of fluorescent lipid analogs in lipid bilayer membranes indicate self-diffusion coefficients D ≳ 10
-7
square centimeters per second for various lipid systems above their reported transition temperatures. Cholesterol in egg lecithin at mole ratio of 1 : 2 reduces D by about twofold, while retained hydrocarbon solvent can increase it by two- to threefold.
Developmental Dyslexia: Two Right Hemispheres and None Left
Authors: Witelson Sandra F.
Published: October 2006

Developmental dyslexia may be associated with (i) bi-hemisphere representation of spatial functions, in contrast to the right-hemisphere specialization observed in normal children, and (ii) typical left-hemisphere representation of linguistic functions, as is observed in normal children. The bilateral neural involvement in spatial processing may interfere with the left hemisphere's processing of its own specialized functions and result in deficient linguistic, sequential cognitive processing and in overuse of the spatial, holistic cognitive mode. This pattern of cognitive deficits and biases may lead dyslexics to read predominantly with a spatial-holistic cognitive strategy and neglect the phonetic-sequential strategy. Such an approach in learning to read phonetically coded languages, such as English, may be inefficient and limited.
Hyperphenylalanemia: Effect on Brain Polyribosomes Can Be Partially Reversed by Other Amino Acids
Authors: Hughes Joseph V. , Johnson Terry C.
Published: October 2006

The effect of a single injection of phenylalanine (2 mg/g of body weight) on brain polyribosomes, which increases the number of inactive monoribosomes, persists for 2 to 3 hours. A single injection of seven large neutral amino acids after phenylalanine administration results in a reversal of the effect on brain polyribosomes with a resultant decrease in monoribosomes to near normal levels. The other common amino acids are apparently not limiting during hyperphenylalanemia, because an injection of these did not increase recovery.
Fluidity in the Membranes of Adult and Neonatal Human Erythrocytes
Authors: Kehry M. , Yguerabide J. , Singer S. J.
Published: October 2006

Several antigens and receptors are mobile in the plane of the membrane of the intact neonatal human erythrocyte but not in the membrane of the normal adult cell. In this report, measurements of the fluorescence polarization of perylene dissolved in isolated erythrocyte membranes are reported, which are indistinguishable for the two kinds of cells. This result indicates that the viscosities of the membrane interiors of the two cells are the same. The observed mobility differences, therefore, cannot be attributed to different lipid viscosities in the two membranes.
Hereditary Hemolytic Anemia with Increased Red Cell Adenosine Deaminase (45- to 70-fold) and Decreased Adenosine Triphosphate
Authors: Valentine William N. , Paglia Donald E. , Tartaglia Anthony P. , Gilsanz Florinda
Published: October 2006

Hereditary hemolytic anemia, a dominantly transmitted disorder, has affected 12 family members spanning three generations. The concentration of adenosine triphosphate in the red cells was about half that of comparably reticulocyte-rich blood. Since adenosine deaminase and adenosine kinase compete for a common substrate, the greatly increased activity of the former may interfere with nucleotide salvage via the latter.
Antagonism of Catecholamine Receptor Signaling by Expression of Cytoplasmic Domains of the Receptors
Authors: Luttrell Louis M. , Ostrowski Jacek , Cotecchia Susanna , Kendall Humphrey , Lefkowitz Robert J.
Published: October 2006

The actions of many hormones and neurotransmitters are mediated by the members of a superfamily of receptors coupled to heterotrimeric guanine nucleotide-binding proteins (G proteins). These receptors are characterized by a highly conserved topographical arrangement in which seven transmembrane domains are connected by intracellular and extracellular loops. The interaction between these receptors and G proteins is mediated in large part by the third intracellular loop of the receptor. Coexpression of the third intracellular loop of the α
1B
-adrenergic receptor with its parent receptor inhibited receptor-mediated activation of phospholipase C. The inhibition extended to the closely related α
1C
-adrenergic receptor subtype, but not the phospholipase C-coupled M1 muscarinic acetylcholine receptor nor the adenylate cyclase-coupled D
1A
dopamine receptor. These results suggest that the receptor-G protein interface may represent a target for receptor antagonist drugs.
Calcium Mobilization by Dual Receptors During Fertilization of Sea Urchin Eggs
Authors: Lee Hon Cheung , Aarhus Robert , Walseth Timothy F.
Published: October 2006

Fertilization is accompanied by a transient increase in the concentration of intracellular Ca
2+
, which serves as a signal for initiating development. Some of the Ca
2+
appears to be released from intracellular stores by the binding of inositol trisphosphate (IP
3
) to its receptor. However, in sea urchin eggs, other mechanisms appear to participate. Cyclic adenosine diphosphate-ribose (cADPR), a naturally occurring metabolite of nicotinamide adenine dinucleotide, is as potent as IP
3
in mobilizing Ca
2+
in sea urchin eggs. Experiments with antagonists of the cADPR and IP
3
receptors revealed that both Ca
2+
mobilizing systems were activated during fertilization. Blockage of either of the systems alone was not sufficient to prevent the sperm-induced Ca
2+
transient. This study provides direct evidence for a physiological role of cADPR in the Ca
2+
signaling process.
Avian Muscular Dystrophy: Functional and Biochemical Improvement with Diphenylhydantoin
Authors: Entrikin Richard K. , Swanson Karen L. , Weidoff Paul M. , Patterson Gary T. , Wilson Barry W.
Published: October 2006

Chicks affected with hereditary muscular dystrophy were injected twice daily with 20 milligrams of diphenylhydantoin per kilogram of body weight on days 1 to 40 after hatching. The righting ability of dystrophic chicks treated with diphenylhydantoin was improved compared to that of untreated dystrophic chicks, and acetylcholinesterase activity was reduced to normal levels in the posterior latissimus dorsi muscles.
Effect of Delta-9-Tetrahydrocannabinol on Uterine and Vaginal Cytology of Ovariectomized Rats
Authors: Solomon Jolane , Cocchia Mary Ann , DiMartino Rita
Published: October 2006

The estrogen-like activity of delta-9-tetrahydrocannabinol (Δ
9
-THC), an active component of marihuana, as measured by uterine weight gain and vaginal smear techniques in ovariectomized rats, is reflected in histological examination of uterine and vaginal tissues. Doses of 1, 2.5, and 10 milligrams of Δ
9
-THC per kilogram elicit hypertrophy and hyperplasia of the uterus; the dose of 2.5 milligrams per kilogram is most effective. There is an increase in stratification of vaginal epithelium with doses of 2.5 and 10 milligrams per kilogram; cornifying cells are seen with 2.5 milligrams per kilogram.
Reduced Warfarin Binding of Albumin Variants
Authors: Wilding George , Blumberg Barach S. , Vesell Elliot S.
Published: October 2006

Binding studies of albumins A/A and A/Me from human plasma and isolated albumin revealed small, but statistically significant, reductions in warfarin binding of albumin A/Me compared to albumin A/A. Such differences in binding in vitro could result in altered pharmacological responses to warfarin administered to individuals possessing albumin A/Me. To determine if clinically significant differences in warfarin distribution exist, observations should be made in vivo on patients of different albumin phenotype who are receiving warfarin therapeutically.
The Effect of Posttranslational Modifications on the Interaction of Ras2 with Adenylyl Cyclase
Authors: Kuroda Yuichi , Suzuki Noboru , Kataoka Tohru
Published: October 2006

Ras proteins undergo a series of posttranslational modifications that are critical for their cellular function. These modifications are necessary to anchor Ras proteins to the membrane. Yeast Ras2 proteins were purified with various degrees of modification and examined for their ability to activate their effector, adenylyl cyclase. The farnesylated intermediate form of Ras2 had more than 100 times higher affinity for adenylyl cyclase than for the unprocessed form. The subsequent palmitoylation reaction had little effect. In contrast, palmitoylation was required for efficient membrane localization of the Ras2 protein. These results indicate the importance of farnesylation in the interaction of Ras2 with its effector.
Structure of the Thiamine- and Flavin-Dependent Enzyme Pyruvate Oxidase
Authors: Muller Yves A. , Schulz Georg E.
Published: October 2006

Pyruvate oxidase from
Lactobacillus plantarum
is a tetrameric enzyme that decarboxylates pyruvate, producing hydrogen peroxide and the energy-storage metabolite acetylphosphate. Structure determination at 2.1 angstroms showed that the cofactors thiamine pyrophosphate (TPP) and flavin adenine dinucleotide (FAD) are bound at the carboxyl termini of six-stranded parallel β sheets. The pyrophosphate moiety of TPP is bound to a metal ion and to a βααβ unit corresponding to an established sequence fingerprint. The spatial arrangement of TPP and FAD suggests that the oxidation of the oxyethyl intermediate does not occur by hydride displacement but rather by a two-step transfer of two electrons.
The Nonhelical Structure of Antifreeze Protein Type III
Authors: Sönnichsen Frank D. , Sykes Brian D. , Chao Heman , Davies Peter L.
Published: October 2006

Antifreeze proteins (AFPs) are present in the blood of some marine fishes and inhibit the growth of ice crystals at subzero temperatures by adsorption to the ice lattice. The solution structure of a Type III AFP was determined by two-dimensional nuclear magnetic resonance spectroscopy. These measurements indicate that this 66-residue protein has an unusual fold in which eight β strands form two sheets of three antiparallel strands and one sheet of two antiparallel strands, and the triple-stranded sheets are packed orthogonally into a β sandwich. This structure is completely different from the amphipathic, helical structure observed for Type I AFPs.
Chemical Synthesis of Restriction Enzyme Recognition Sites Useful for Cloning
Authors: Scheller Richard H. , Dickerson Richard E. , Boyer Herbert W. , Riggs Arthur D. , Itakura Keiichi
Published: October 2006

By a triester chemical synthesis method, three decameric DNA's have been made; these act as substrates for several restriction endonucleases, including Eco RI, Bam I, and Hind III. These homogeneous decamers form duplexes that can be efficiently blunt-end ligated to themselves or to other DNA molecules by the action of T4 DNA ligase and thus are useful tools for molecular cloning experiments.
Use of Phage Immunity in Molecular Cloning Experiments
Authors: Backman Keith , Hawley Diane , Ross Michael J.
Published: October 2006

Immunity to phage superinfection is a useful selective marker in molecular cloning experiments. Plasmids which have unique sites for several different restriction endonucleases and which specify immunity to bacteriophage λ are described.
Nucleotide Sequences from a Rabbit Alpha Globin Gene Inserted in a Chimeric Plasmid
Authors: Liu Alvin Y. , Paddock Gary V. , Heindell Howard C. , Salser Winston
Published: October 2006

Rabbit alpha globin gene copies have been made, using reverse transcriptase and DNA polymerase I, and cloned in bacterial plasmids. Plasmid pHb72 has been shown to contain the alpha gene sequence by restriction enzyme analysis and nucleotide sequencing studies, and therefore has been approved for propagation under P2 plus EK1 conditions by the National Recombinant DNA Committee.
Microsatellite Instability in Cancer of the Proximal Colon
Authors: Thibodeau S. N. , Bren G. , Schaid D.
Published: October 2006

Colorectal tumor DNA was examined for somatic instability at (CA)

n

repeats on human chromosomes 5q, 15q, 17p, and 18q. Differences between tumor and normal DNA were detected in 25 of the 90 (28 percent) tumors examined. This instability appeared as either a substantial change in repeat length (often heterogeneous in nature) or a minor change (typically two base pairs). Microsatellite instability was significantly correlated with the tumor's location in the proximal colon (
P
= 0.003), with increased patient survival (
P
= 0.02), and, inversely, with loss of heterozygosity for chromosomes 5q, 17p, and 18q. These data suggest that some colorectal cancers may arise through a mechanism that does not necessarily involve loss of heterozygosity.
New Challenges in Human in Vitro Fertilization
Authors: Winston Robert M. L. , Handyside Alan H.
Published: October 2006

This review assesses some scientific and ethical problems with human in vitro fertilization. Improved selection of viable embryos, better culture conditions, and greater understanding of the uterine environment will increase success and prevent multiple pregnancy. Further advances will also improve oocyte cryopreservation, in vitro maturation of oocytes, knowledge of sperm function, and sperm microinjection. Preimplantation diagnosis will help avoid genetic diseases and increase understanding of embryonic defects and the viability of zygotes. The greatest ethical problem with all these developments seems to be delivery of these complex treatments when health-care resources are increasingly limited.
Expression of
Pseudomonas aeruginosa
Virulence Genes Requires Cell-to-Cell Communication
Authors: Passador Luciano , Cook James M. , Gambello Michael J. , Rust Lynn , Iglewski Barbara H.
Published: October 2006

Pseudomonas aeruginosa
is an opportunistic human pathogen that causes a variety of infections in immunocompromised hosts and individuals with cystic fibrosis. Expression of elastase, one of the virulence factors produced by this organism, requires the transcriptional activator LasR. Experiments with gene fusions show that gene
lasl
is essential for high expression of elastase. The
lasl
gene is involved in the synthesis of a diffusible molecule termed
Pseudomonas
autoinducer (PAI). PAI provides
P. aeruginosa
with a means of cell-to-cell communication that is required for the expression of virulence genes and may provide a target for therapeutic approaches.
The Three-Dimensional Structure of an Arachidonic Acid 15-Lipoxygenase
Authors: Boyington Jeffrey C. , Gaffney Betty J. , Amzel L. Mario
Published: October 2006

In mammals, the hydroperoxidation of arachidonic acid by lipoxygenases leads to the formation of leukotrienes and lipoxins, compounds that mediate inflammatory responses. Lipoxygenases are dioxygenases that contain a nonheme iron and are present in many animal cells. Soybean lipoxygenase-1 is a single-chain, 839-residue protein closely related to mammalian lipoxygenases. The structure of soybean lipoxygenase-1 solved to 2.6 angstrom resolution shows that the enzyme has two domains: a 146-residue β barrel and a 693-residue helical bundle. The iron atom is in the center of the larger domain and is coordinated by three histidines and the COO
-
of the carboxyl terminus. The coordination geometry is nonregular and appears to be a distorted octahedron in which two adjacent positions are not occupied by ligands. Two cavities, in the shapes of a bent cylinder and a frustum, connect the unoccupied positions to the surface of the enzyme. The iron, with two adjacent and unoccupied positions, is poised to interact with the 1,4-diene system of the substrate and with molecular oxygen during catalysis.
Modal Shifts in Acetylcholine Receptor Channel Gating Confer Subunit-Dependent Desensitization
Authors: Naranjo David , Brehm Paul
Published: October 2006

During the transition from embryonic to adult skeletal muscle, a decreased mean channel open time and accelerated desensitization of nicotinic acetylcholine (ACh) receptors result from the substitution of an ε subunit for γ. A single ACh receptor channel of the embryonic type, expressed in
Xenopus
oocytes, interconverts between gating modes of short and long open time, whereas the adult receptor channel resides almost exclusively in the gating mode with short open time. Differences in the fraction of time spent in either gating mode account for the subunit dependence of both receptor open time and desensitization. Therefore, developmental changes in the kinetics of muscle ACh receptors may be imparted through subunit-dependent stabilization of intrinsic gating modes.
Hibernation and Body Weight in Dormice: A New Type of Endogenous Cycle
Authors: Mrosovsky N.
Published: October 2006

Under conditions unfavorable to hibernation (22°C), the body-weight cycles of dormice are only a few weeks long, but under conditions in which dormice hibernate (5°C), the cycles can last many months; the more the animals hibernate, the longer are the cycles. Such cycles contrast with the relative independence from torpor of the period of circannual cycles in other hibernating rodents and with the temperature compensation of circannual and circadian cycles in general.
Nuclear Morphometry During the Cell Cycle
Authors: Kendall F. , Swenson R. , Borun T. , Rowinski J. , Nicolini C.
Published: October 2006

Directly measured and derived geometric and densitometric parameters were obtained by means of the automated image analyzer Quantimet 720-D in Feulgen-stained HeLa cells synchronized by selective mitotic detachment. These data indicate substantial alteration of nuclear morphology during the entire cell cycle, even during the G1 and G2 phases, and the late G1-early S and late S-G2 transitions.
Insecticide Solvents: Interference with Insecticidal Action
Authors: Brattsten L. B. , Wilkinson C. F.
Published: October 2006

Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal
N
-demethylation of
p
-chloro
N
-methylaniline in midgut preparations of southern armyworm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.
Stability of the Individual Globin Genes During Erythroid Differentiation
Authors: Benz Edward , Turner Patricia , Barker Jane , Nienhuis Arthur
Published: October 2006

The genes for sheep β
A
, β
C
, and γ globin were all present in DNA from erythroid cells which synthesized only β
C
globin. Similarly, selective excision of non-expressed genes was shown not to occur during human erythroid differentiation. In contrast, evolutionary deletion of the β
C
gene accounts for the inability of many sheep to make this globin.
Inhibition of Mast Cell Histamine Secretion by
N
-Substituted Derivatives of Phosphatidylserine
Authors: Martin Thomas W. , Lagunoff David
Published: October 2006

The structural basis for the highly specific action of phosphatidylserine in enhancing mast cell histamine secretion induced by concanavalin A was investigated by studying the activities of three
N
-substituted derivatives:
N
-acetyl phosphatidylserine,
N
-1-dimethylaminonaphthalene-5-sulfonyl phosphatidylserine, and
N
-4-nitrobenzo-2-oxa-1,3-diazole phosphatidylserine. None of the derivatives was capable of activating concanavalin A-induced histamine secretion at concentrations two to three times that required for maximal activation by phosphatidylserine. Instead, the derivatives were found to inhibit the secretory response of mast cells to the calcium ionophore A23187 as well as to concanavalin A. The inhibition was noncytotoxic, partially reversible by washing, and associated with binding of
N
-substituted phosphatidylserine to the mast cell.