Non-NMDA receptors in the nucleus of the tractus solitarius play the predominant role in mediating aortic baroreceptor reflexes

The purpose of these studies was to determine the relative role of N-methyl-D-aspartic acid (NMDA) receptors and non-NMDA receptors in the nucleus of the tractus solitarius (NTS) in mediating arterial baroreceptor reflexes evoked by electrical stimulation of the aortic nerve. Selective blockade of NMDA receptors in the NTS had little effect on aortic baroreflexes except at high frequencies of aortic nerve stimulation. In contrast, blockade of non-NMDA receptors in the NTS abolished aortic baroreceptor reflexes. These results suggest that although NMDA receptors may modulate baroreflex responses, synaptic activation of non-NMDA receptors in the NTS plays the predominant role in mediating aortic baroreceptor reflexes.

A functional approach to understanding attitudes toward AIDS victims

Attitudes toward victims of AIDS were conceptualized as serving three possible functions: a value-expressive function (e.g., stigmatization), an ego-defensive function (e.g., homosexual prejudice), or a knowledge function (e.g., victim derogation). These functions were evaluated by having a sample of U.S. undergraduates respond to a victim who had contracted AIDS by one of three different means: a blood transfusion, a sexual encounter of a homosexual nature, or intravenous drug use. Subjects then indicated their beliefs about the victim's responsibility for the disease, feelings toward the victim, and likely behavioral interactions with the victim. The findings provided most support for the knowledge function of attitudes toward AIDS victims.

Cell mutants defective in synthesizing a heparan sulfate proteoglycan with regions of defined monosaccharide sequence

We have demonstrated that mouse LTA cells synthesize cell-surface heparan sulfate proteoglycans (HSPGs) with regions of defined monosaccharide sequence that specifically interact with antithrombin (HSPGact). It remains unclear how HSPGact can be generated by a biosynthetic pathway with no simple template for directing the ordered assembly of monosaccharide units. To examine this issue, we treated LTA cells with ethyl methanesulfonate and then isolated seven stable mutants that synthesize only 8-27% of the wild-type HSPGact but produce normal amounts of other HSPGs. These mutants are recessive in nature and fall into at least two different complementation groups. The delineation of the molecular basis of these defects should help to elucidate the manner by which cells synthesize HSPGs with regions of defined monosaccharide sequence.

Agaricus bisporus metapotyrosinase: preparation, characterization, and conversion to mixed-metal derivatives of the binuclear site

The alpha, beta, and gamma isozymes of Agaricus bisporus tyrosinase undergo inactivation in the presence of oxalate. The inactivation rate law is first order in enzyme and second order in oxalate. On a more rapid time scale than inactivation, oxalate acts as a competitive inhibitor of the catecholase reaction of tyrosinase. After removal of oxalate by dialysis, the inactivated enzyme is found to contain 50% of the original copper, all of which is present as paramagnetic, mononuclear copper sites. The ESR parameters of this copper indicate a tetragonal environment with nitrogen and oxygen ligands. The product of oxalate inactivation has lost one copper from each binuclear site and is thus a metapo derivative. Addition of Cu(II) to metapotyrosinase results in complete recovery of copper and catalytic activity. Prolonged storage of metapotyrosinase, in the absence of any additional Cu(II), results in copper migration, producing a 50% recovery of the original specific activity, expressed on a protein basis. Copper migration converts metapo sites into equal numbers of reconstituted, holo sites and fully apo sites. Both copper migration and copper reconstitution follow apparent first-order kinetics and are pH dependent. The involvement of two ionizable groups accounts for the observed pH dependence of each process. For copper migration pKa values of 6.0 and 8.8 were found, while for copper reconstitution the pKa values were 5.4 and 6.9. Addition of either Co(II) or Zn(II) to metapotyrosinase results in the formation of enzymatically inactive, mixed-metal derivatives of the binuclear copper site having one Cu(II) and one Co(II) or Zn(II) ion.(ABSTRACT TRUNCATED AT 250 WORDS)

Some effects of sex-linked clothing and gender schema on the stereotyping of infants

Two predictions were evaluated: first, that given minimal information about an infant, individuals would use sex-related cues (i.e., clothing) to categorize, evaluate, and make attributions about the infant, and second, that gender schematic individuals would be more likely than gender aschematic individuals to use such sex-related cues. On the basis of the Bem Sex Role Inventory, American college students were classified as either gender schematic (masculine or feminine) or gender aschematic (undifferentiated or androgynous). The students categorized, evaluated, and made trait attributions about an infant dressed in male, female, or ambiguous clothing. Both gender schematic and gender aschematic individuals relied on sex-related cues in their perceptions of the infant.

Is L-glutamate a neurotransmitter of baroreceptor information in the nucleus of the tractus solitarius?

The nucleus of the tractus solitarius (NTS) is the central termination site of peripheral baroreceptor afferents. It has been suggested that the excitatory amino acid (EAA) L-glutamate may be a neurotransmitter which mediates transmission of baroreceptor information in the rat NTS. The present studies examined this hypothesis by pharmacological blockade of EAA receptors in the NTS. Bilateral microinjections into the NTS of the EAA receptor antagonist kynurenic acid (KYN) virtually abolished baroreflexes elicited by electrical stimulation of the aortic nerve. In addition, hypotension and bradycardia evoked by injections into the NTS of the selective EAA receptor agonists N-methyl-D-aspartate, kainate and the quisqualate-selective agonist, alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid were reduced by 75% or more after KYN. Paradoxically, KYN did not reduce cardiovascular responses produced by injections into the NTS of L-glutamate. These results demonstrate that 1) blockade of EAA receptors in the NTS is sufficient to abolish synaptically mediated aortic baroreflexes; 2) cardiovascular responses evoked by L-glutamate are not reduced after documented blockade of N-methyl-D-aspartate, kainate and quisqualate receptors in the NTS by KYN; and 3) under the conditions of these experiments, the pharmacological actions of exogenously administered L-glutamate are not identical to those of the neurotransmitter which is released at NTS synapses by aortic nerve stimulation. These observations suggest that an EAA or EAA analog other than L-glutamate may be the neurotransmitter of baroreceptor information in the NTS.

[Duration of breast feeding in an urban area of São Paulo, Brazil]

Duration of breast-feeding was studied by the authors among a representative sample of families with children under one year of age that resided in the area of coverage of the Health Center-School Samuel B. Pessoa in the borough of Butantã, São Paulo. The data was obtained by means of home interviews in which respondents were questioned about what type of food the child was eating that day, so that they did not have to depend on memory. The median duration of breast-feeding was found to be 2.8 months (84 days), thus showing that in the area under study early weaning is still practiced. Nevertheless, the study confirms the trend observed in the city of São Paulo in the last few years of a return to breast-feeding. This conclusion is supported by the fact that, contrary to the pattern in the previous decade, longer duration of breast-feeding is associated with higher academic levels of the parents (both), i.e., the practice is on the increase among the higher social and economic segments of the population. The study shows that the father can play a significant role in breast-feeding patterns. No correlation was found between breast-feeding duration and number of siblings, per capita monthly income, academic level of the mother, or the regularity of health check-ups.

A comparison of in-vivo and imaginal participant modeling

Recent research indicates that effective treatments of phobic reactions are often performance-based and involve exposure to the phobic object. The present study was designed to determine whether both of these components were necessary for the effectiveness of participant modeling procedures (N = 26). Phobic individuals were assigned randomly to one of two forms of participant modeling: In-vivo vs. imaginal. Both treatment analogues were identical except that the in-vivo version involved actual exposure to a phobic object, while the imaginal version simply required individuals to imagine that the phobic object was physically present. Results on behavioral and self-report measures indicated that both in-vivo and imaginal participant modeling were effective in generating increased approach behavior, but neither produced generalization beyond the laboratory setting. Explanations were discussed.

Thought-induced change in phobic beliefs: sometimes it helps, sometimes it hurts

Derived two predictions from Tesser's (1978) work on thought-induced polarization. First, the longer individuals thought in a constrained manner about a phobic object, the more strongly they would believe that they were able to cope with the object. Second, the longer individuals thought in an unconstrained manner about a phobic object, the more strongly they would believe that they were unable to cope with the object. It was also predicted that, in both cases, the relationship between thought and belief change would be monotonic. These hypotheses were tested by randomly assigning phobic individuals (N = 20) to one of two treatment conditions: Constrained thought or unconstrained thought. Beliefs about extra-laboratory behavior were used to assess the effects of treatment, and results supported all predictions.

[Plasma renin activity in hypertensive patients under basal conditions and in various postures: preliminary data]

We have studied PRA levels in 10 healthy subjects compared with 10 patients affected with essential hypertension (with low PRA) on venous blood samples collected after 8 hours of rest and after 15-20 minutes of slow plain walk. Contemporarely we have taken up arterious pression levels in each class of subjects of these studies. No significant differences of PRA are demonstrable in healthy subjects and in patients affected with essential hypertension. Postural changes in hypertension produces significant rise of PRA, not related to arterial pressure.

[Oxoprenolol and plasmatic renin activity in essential hypertension: preliminary data]

We have studied PRA levels in 10 healthy subjects compared with 10 patients affected with essential hypertension (with low PRA) on venous blood samples collected after 8 hours of rest and after 15-20 minutes of slow plain walk and 15 minutes after intravenous administration of oxoprenolol (mg 2). Contemporarely we have taken up arterious pression levels in each class of subjects of these studies. Postural changes produces significant rise of PRA in subjects affected with essential hypertension, that is significantly inhibited by pharmacologic interference produced by beta-blocking agents. This occurrence is independent of arterial pressure changes.