Effects of group support on the evaluation of an antagonist.

"The present experiment was concerned with variations in person perception as a function of the perceiver's role in instigating a stimulus person to hostility." Perception of the stimulus person was manipulated by experimentally determining information feedback concerning acceptance of ideas by a group of which S was a part. Interpersonal perception was seen to be a function of inner (individual) as well as outer (socially determined) criteria. The results are discussed in terms of their implication for studies on person perception and in light of cognitive and frustration-aggression theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vitamin K2 (menaquinone) biosynthesis in Escherichia coli: evidence for the presence of an essential histidine residue in o-succinylbenzoyl coenzyme A synthetase

o-Succinylbenzoyl coenzyme A (OSB-CoA) synthetase, when treated with diethylpyrocarbonate (DEP), showed a time-dependent loss of enzyme activity. The inactivation follows pseudo-first-order kinetics with a second-order rate constant of 9.2 x 10(-4) +/- 1.4 x 10(-4) microM(-1) min(-1). The difference spectrum of the modified enzyme versus the native enzyme showed an increase in A242 that is characteristic of N-carbethoxyhistidine and was reversed by treatment with hydroxylamine. Inactivation due to nonspecific secondary structural changes in the protein and modification of tyrosine, lysine, or cysteine residues was ruled out. Kinetics of enzyme inactivation and the stoichiometry of histidine modification indicate that of the eight histidine residues modified per subunit of the enzyme, a single residue is responsible for the enzyme activity. A plot of the log reciprocal of the half-time of inactivation against the log DEP concentration further suggests that one histidine residue is involved in the catalysis. Further, the enzyme was partially protected from inactivation by either o-succinylbenzoic acid (OSB), ATP, or ATP plus Mg2+ while inactivation was completely prevented by the presence of the combination of OSB, ATP, and Mg2+. Thus, it appears that a histidine residue located at or near the active site of the enzyme is essential for activity. When His341 present in the previously identified ATP binding motif was mutated to Ala, the enzyme lost 65% of its activity and the Km for ATP increased 5.4-fold. Thus, His341 of OSB-CoA synthetase plays an important role in catalysis since it is probably involved in the binding of ATP to the enzyme.     

Altered arachidonic acid metabolism contributes to the failure of dopamine to inhibit Na+,K(+)-ATPase in kidney of spontaneously hypertensive rats

Dopamine decreases tubular sodium reabsorption in part by inhibition of Na+,K(+)-ATPase activity in renal proximal tubules. The signaling mechanism involved in dopamine-mediated inhibition of Na+,K(+)-ATPase is known to be defective in spontaneously hypertensive animals. The present study was designed to evaluate the role of phospholipase A2 (PLA2) and its metabolic pathway in dopamine-induced inhibition of Na+,K(+)-ATPase in renal proximal tubules from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). Renal proximal tubular suspensions were prepared and Na+,K(+)-ATPase activity was measured as ouabain-sensitive adenosine triphosphate hydrolysis. Dopamine inhibited Na+,K(+)-ATPase activity in a concentration (1 nM-10 microM)-dependent manner in WKY rats while it failed to inhibit the enzyme activity in SHR. Dopamine (10 microM)-induced inhibition of Na+,K(+)-ATPase activity in WKY rats was significantly blocked by mepacrine (10 microM), a PLA2 inhibitor, suggesting the involvement of PLA2 in dopamine-mediated inhibition of Na+,K(+)-ATPase. Arachidonic acid (a product released by PLA2 action) inhibited Na+,K(+)-ATPase in a concentration-dependent (1-100 microM) manner in WKY rats while the inhibition in SHR was significantly attenuated (IC50: 7.5 and 80 microM in WKY rats and SHR, respectively). Furthermore, lower concentrations of arachidonic acid stimulated (30% at 1 microM) Na+,K(+)-ATPase activity in SHR. This suggests a defect in the metabolism of arachidonic acid in SHR. Proadifen (10 microM), an inhibitor of cytochrome P-450 monoxygenase (an arachidonic acid metabolizing enzyme) significantly blocked the inhibition produced by arachidonic acid in WKY rats and abolished the difference in arachidonic acid inhibition of Na+,K(+)-ATPase between WKY rats and SHR. These data suggest that PLA2 is involved in dopamine-induced inhibition of Na+,K(+)-ATPase and altered arachidonic acid metabolism may contribute to reduced dopaminergic inhibition of Na+,K(+)-ATPase activity in spontaneously hypertensive rats.     

Studies on the essential role of ascorbic acid in the energy dependent release of insulin from pancreatic islets

Pancreatic islets from young normal and scorbutic male guinea pigs were examined for their ability to release insulin when stimulated with depolarizing levels of KCl (45 mM) and by 20 mM D-glyceraldehyde. Islets from normal guinea pigs released insulin in a K+ and D-glyceraldehyde dependent manner showing a rapid initial secretion phase followed by secondary waves of insulin release during a 120 min period. Islets from scorbutic guinea pigs were able to respond to elevated K+ in a manner identical to that of the control islets. In contrast, insulin release from ascorbic acid deficient islets in response to the secretagogue, D-glyceraldehyde, was significantly delayed and decreased responses were observed during the 120 min period after D-glyceraldehyde stimulation. The results are consistent with the site of action of ascorbic acid on energy-dependent insulin release lying between the triose-phosphate level of glycolysis and the generation of ATP by oxidative phosphorylation.     

Small group research, that once and future field: An interpretation of the past with an eye to the future.

This review chronicles prior approaches to research on small groups, critiques contemporary theories and methods, and notes some future possibilities. Early group researchers worked in isolated "schools," treating groups as social systems for influencing members, for patterning interaction, or for performing tasks. Assumptions of those 3 schools are blended in some contemporary approaches, treating groups as systems for processing information; for managing consensus and conflict; and for motivating, regulating, and coordinating member behavior. Past and contemporary approaches are limited by their analytic focus, limited temporal scope, and failure to treat groups in context. The article points to an alternative theoretical approach that treats groups as complex, adaptive, dynamic systems and notes some methodological issues and possibilities raised by that approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies on the essential oils in Ligusticum chuanxiong Hort. of different habitats and species

Constituents of the essential oils obtained from Chuanxiong, Yungxiong, Fuxiong, Xixiong and "Chuanxiong" of Japan were analysed by GC-MS. Ninety-six compounds including ligustilide, etc. were identified. Their percentages in the oils were given.     

Destabilization of peptide binding and interdomain communication by an E543K mutation in the bovine 70-kDa heat shock cognate protein, a molecular chaperone

We have compared 70-kDa heat shock cognate protein (Hsc70) isolated from bovine brain with recombinant wild type protein and mutant E543K protein (previously studied as wild type in our laboratory). Wild type bovine and recombinant protein differ by posttranslational modification of lysine 561 but interact similarly with a short peptide (fluorescein-labeled FYQLALT) and with denatured staphylococcal nuclease-(Delta135-149). Mutation E543K results in 4. 5-fold faster release of peptide and lower stability of complexes with staphylococcal nuclease-(Delta135-149). ATP hydrolysis rates of the wild type proteins are enhanced 6-10-fold by the addition of peptide. The E543K mutant has a peptide-stimulated hydrolytic rate similar to that of wild type protein but a higher unstimulated rate, yielding a mere 2-fold enhancement. All three versions of Hsc70 possess similar ATP-dependent conformational shifts, and all show potassium ion dependence. These data support the following model: (i) in the presence of K+, Mg2+, and ATP, the peptide binding domain inhibits the ATPase; (ii) binding of peptide relieves this inhibition; and (iii) the E543K mutation significantly attenuates the inhibition by the peptide binding domain and destabilizes Hsc70-peptide complexes.     

Effects of stimulus variation on responses to the group version of he Holtzman Inkbolt Technique.

Investigated the effects on the Color and Shading scores of the Holtzman Inkblot Technique (HIT) when the standard group slides were experimentally altered with regard to the stimulus dimensions of color and shading. 2 groups of 40 undergraduates each were given different series of HIT slides; 1 series contained a subset of slides lightened by underexposing, and a 2nd contained slides darkened by overexposing. Results indicate no significant differences for the HIT Color and Shading scores between normal and altered slides in these 2 series. This finding has important implications for quality control in the production of group slides and for the statistical character and meaning of such variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of a natural mutation in an antigenic site on the fusion protein of measles virus that is involved in neutralization

Although measles virus is an antigenically monotypic virus, nucleotide sequence analysis of the hemagglutinin and nucleoprotein genes has permitted the differentiation of a number of genotypes. In contrast, the fusion (F) protein is highly conserved; only three amino acid changes have been reported over a 40-year period. We have isolated a measles virus strain which did not react with an anti-F monoclonal antibody (MAb) which we had previously shown to be directed against a dominant antigenic site. This virus strain, Lys-1, had seven amino acid changes compared with the Edmonston strain. We have shown that a single amino acid at position 73 is responsible for its nonreactivity with the anti-F MAb. With the same MAb, antibody-resistant mutants were prepared from the vaccine strain. A single amino acid change at position 73 (R-->W) was observed. The possibility of selecting measles virus variants in vaccinated populations is discussed.     

K+ channel-opening action contributes to the preventive effects of nicorandil on U46619-induced vasoconstriction of canine large coronary arteries in vivo

The antispasmogenic effects of nicorandil on epicardial coronary artery vasoconstriction were compared with those of a K+ channel opener, cromakalim, and a nitrovasodilator, nitroglycerin, in open-chest dogs. Intracoronary administration of U46619 (0.5-1.0 micrograms), a stable thromboxane A2 analogue, reduced the external diameter of the left circumflex coronary artery with no marked alternations in systemic hemodynamics. This U46619-induced vasoconstriction of large epicardial coronary arteries was dose-dependently prevented by the intracoronary infusion of nicorandil (1-10 micrograms/kg/min), cromakalim (0.03 micrograms/kg/min) and nitroglycerin (1 micrograms/kg/min). After pretreatment with glibenclamide (3 mg/kg, i.v.), and ATP-sensitive K+ channel blocker, these effects of nicorandil and cromakalim were inhibited significantly, whereas the response to nitroglycerin remained unchanged. Nicorandil (3 micrograms/kg/min), cromakalim (0.03 micrograms/kg/min) and nitroglycerin (1 micrograms/kg/min) increased coronary blood flow. However, the inhibitory effects of each drug on the U46619-induced vasoconstriction were not influenced by the partial occlusion of the left circumflex coronary artery, which kept coronary blood flow constant. This indicates a direct antispasmogenic effect of K+ channel openers, which is independent of that mediated by the response to flow. Furthermore, our results suggest that, by this effect, nicorandil protects large coronary arteries from U46619-induced vasoconstriction.     

Distance between the basic group of the amino acid residue's side chain in position P1 of trypsin inhibitor CMTI-III and Asp189 in the substrate pocket of trypsin has an essential influence on the inhibitory activity

Three new analogues of trypsin inhibitor CMTI-III were synthesized by the solid-phase method: [Lys5]-CMTI-III, [Orn5]CMTI-III and [Dab5]CMTI-III. Only one analogue with L-lysine residue in position P1 showed inhibitory activity of the same order of magnitude as did wild CMTI-III. Two remaining analogues were completely inactive. A conclusion was drawn that the distance between the basic group of the amino acid residue's side chain in position P1 of the trypsin inhibitor CMTI-III and Asp189 in the substrate pocket of trypsin plays an essential role for the trypsin-inhibitor interaction.     

Effects of autoantibodies to the insulin receptor on isolated adipocytes. Studies of insulin binding and insulin action

Autoantibodies to the insulin receptor have been detected in the sera of several patients with the Type B syndrome of insulin resistance and acanthosis nigricans. In this study we have used three of these sera (B-1, B-2, and B-3) as probes of the insulin receptor in isolated rat adipocytes. Preincubation of adipocytes with each of the three sera resulted in an inhibition of subsequent [(125)I]insulin binding. 50% inhibition of binding occurred with serum dilutions of 1:5 to 1:7,500. As in our previous studies with other tissues, Scatchard analysis of the insulin-binding data was curvilinear consistent with negative cooperativity. Computer analysis suggested that in each case the inhibition of binding was due to a decrease in receptor affinity rather than a change in available receptor number. In addition to the effects on insulin binding, adipocytes pretreated with antireceptor sera also showed alterations in biological responses. All three sera produced some stimulation of basal glucose oxidation. With serum B-3, maximal stimulation of glucose oxidation occurred at a serum concentration that inhibited binding by only 10-15%, whereas with serum B-2 the dilution curves for inhibition of binding and stimulation of glucose oxidation were superimposable. Serum B-1 behaved as a partial agonist; that is, it inhibited binding more effectively than it stimulated glucose oxidation. Cells pretreated with this serum in a concentration which inhibited binding by 80% also showed a five-fold shift to the right in the dose response of insulin-stimulated glucose oxidation, whereas spermine-stimulated glucose oxidation was unaffected. Serum B-2, which contained the highest titer of antireceptor antibodies, also stimulated 2-deoxy-glucose transport, as well as glucose incorporation into lipid and glycogen. Both the ability of the serum to inhibit binding and stimulate glucose utilization were enriched in purified immunoglobulin fractions and retained in the F(ab')(2) fragment of the IgG. In addition, the bioactivity was blocked by antihuman IgG but not by anti-insulin antibodies. Enzymatic digestion of adipocytes with trypsin resulted in a complete loss of insulin-stimulated bioactivity of serum B-3, but had only minor effects on the glucose oxidation produced by serum B-1 or B-2.These data suggest that the antibodies present in these three sera bind to different determinants on the insulin receptor. Thus, these antibodies may be useful probes of receptor structure and function.     

Studies on the role of cephalic-vagal stimulation in the acid secretory response to eating in normal human subjects

These experiments were performed to determine the importance of cephalic-vagal stimulation in the acid secretory response to eating in normal human subjects. Cephalic stimulation was induced by a modified sham feeding (MSF) technique, during which subjects chewed and expectorated appetizing food. The response to MSF was compared with that to gastric distention with 600 ml NaCl, glucose, or food. In addition, we measured the extent to which cephalic stimulation augments acid secretion that has been stimulated simultaneously by these other mechanisms. Our conclusions are as follows: (a) cephalic stimulation accounts for approximately one-third of the acid secreted when all mechanisms act simultaneously (food-distention plus MSF); (b) within the limits imposed by the maximal secretory capacity, the response to MSF is approximately the same, regardless of whether acid secretion is otherwise unstimulated or is stimulated simultaneously by gastric distention with NaCl, glucose, or food; and (c) gastric distention prolongs the response to cephalic stimulation.     

Effects of K+-depolarization, arachidonic acid, ethanol, and aging on the high-affinity choline transport in rat hippocampus

The Na+-dependent high-affinity choline uptake (HACU) transport and the [3H]hemicholinium-3 ([3H]HC-3) specific binding were measured on hippocampal synaptosomes of young (3-6 months) and old (22 months) Wistar rats. In vitro effects of 100-300 microM arachidonic acid (AA) and of 5% ethanol were tested under basal as well as stimulated (55 mM KCl) conditions. The influence of AA (an irreversible decrease of HACU and a reversible increase of [3H]HC-3 binding) was more marked under stimulated rather than basal conditions in brain tissue of young rats. The increased K+-depolarization effect on HACU and the decreased influence of AA on [3H]HC-3 binding were estimated in brain tissue of old compared to young rats. Results suggest the involvement of different pools of the high-affinity choline carrier and marked changes due to aging in the regulation of the HACU transport.     

The effects of eprosartan, an angiotensin II AT1 receptor antagonist, on uric acid excretion in patients with mild to moderate essential hypertension

To test our hypothesis that arginine (Arg) and lysine (Lys) enhance immune activities via neuronal control of the thymus and the spleen, a jugular vein was cannulated for amino acid administration in male Wistar rats (approximately 300 g). In one group (n = 5), an efferent nerve filament of the vagal thymus was isolated. In another group (n = 5), splenic nerve efferents were isolated. Efferent firing rates were recorded before and for 60-90 minutes after 10 mM Arg-Lys in 0.5 ml saline intravenously (i.v.). Differences in firing rates were evaluated using analysis of variance (ANOVA) and t-test. I.v. Arg-Lys increased vagal efferent firing rate to the thymus; enhancing thymic lymphocyte release. I.v. Arg-Lys decreased firing rate in splenic efferents; enhancing natural killer (NK) cell activity. Therefore, Arg-Lys are detected by hepatoportal sensors, stimulating hepatic vagal afferents to the hypothalamus, with the efferent neuronal impulses from the hypothalamus modulating immune function in thymus and spleen, thereby demonstrating the mechanism of Arg and Lys immune enhancing activity.     

Effects of an auditory and an auditory-visual method of blending instruction on the ability of prereaders to decode synthetic words.

Studied differential effectiveness of 2 methods of blending instruction on the ability of prereaders to decode synthetic words. Children's responses were also analyzed for generalizations that could be made about the blending process. The 80 Ss, having an average age of 62 mo, were pupils at 3 private preschools. Findings indicate the superiority of auditory-visual training over auditory, with both methods significantly superior to practice on sound-letter association (the control group task). Findings also indicate that blending may need to be taught for specific phonic patterns and that position (initial and final) or type (stop or continuant) of consonants in words make little difference in their blendability. Findings challenge some basic tenets of beginning reading instruction. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A controlled comparison of thermal biofeedback and relaxation training in the treatment of essential hypertension: II. Effects on cardiovascular reactivity.

Compared progressive muscle relaxation (PMR), thermal biofeedback (BFB), and drug withdrawal (DW) as possible substitutes for 2nd-stage (sympatholytic) antihypertensive medications, using 73 hypertensive adults. Reactivity (heart rate, systolic blood pressure, and diastolic blood pressure) to 3 stressors (mental arithmetic, cold pressor, and negative mental imagery) was measured before and after PMR, BFB, and DW. PMR led to more reductions in some aspect of reactivity than did BFB. Reductions in reactivity were seen more for mental arithmetic and systolic blood pressure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of ibotenic acid lesions of the nucleus accumbens on paced mating behavior in the female rat.

The present study investigated the role of the nucleus accumbens (NAcc) in paced mating behavior in female rats. A sexually receptive female rat will approach and withdraw from a sexually active male, thereby controlling the timing of the receipt of sexual stimulation (e.g., mounts, intromissions, ejaculations). In this study, ibotenic acid lesions in the NAcc core increased the likelihood that a female rat would withdraw from a male rat after a mount but did not affect contact return latency or sexual receptivity. lbotenic acid lesions in the NAcc shell did not affect paced mating behavior or sexual receptivity. The results suggest that the NAcc core plays a role in suppressing withdrawal behavior in response to less intense mating stimulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)