Differential sensitivity of selected rat brain areas to excitatory neurotransmitters released by K+ depolarization

When injected intrathecally in mice in a volume of 5 microliter, adenosine had no effect on tail-flick or hot-plate reaction latencies at dosages up to 1 mM concentration. There were no other behavioral effects observed either. Injecting 1 mM of the adenosine receptor agonist, 5'-N-ethylcarboxamide adenosine (NECA) caused both motor paralysis of the hind-legs with a duration of approximately 4 h and simultaneous antinociception. A slight weakness of the hindlegs, but a profound antinociceptive effect, was observed after the 100 microM dose only. After 10 microM, there was no effect on motor behavior but still a prolongation of the tail-flick and hot-plate reaction latencies. Pretreatment with the adenosine receptor antagonist theophylline attenuated the antinociceptive effect of NECA. Activation of spinal adenosine receptors thus appears to selectively elicit analgesia.     

Participation of prefrontal neurons in the preparation of visually guided eye movements in the rhesus monkey

1. We recorded from 257 neurons in the banks of the posterior third of the principal sulcus of two rhesus monkeys trained to look at a fixation point and make saccades to stimuli in the visual periphery. Sixty-six percent (220/257) discharged or were suppressed in association with one or more aspects of the tasks we used. 2. Fifty-eight percent (151/257) of the neurons responded to the appearance of a spot of light in some part of the contralateral visual field. Cells did not seem to have absolute requirements for stimulus shape, size, or direction of motion. 3. Thirty-six percent (29/79) of visually responsive neurons tested quantitatively gave an enhanced response to the stimulus in the receptive field when the monkey had to make a saccade to the stimulus when its appearance was synchronous with the disappearance of the fixation point (synchron task). Twenty-nine percent (19/57) of the neurons gave an enhanced response to the stimulus when the monkey had to make a saccade to the stimulus some time after it appeared (delayed-saccade task). In general, enhancement in the synchron task correlated well with enhancement in the delayed-saccade task. 4. Enhancement was spatially specific. It did not occur when the monkey made a saccade to a stimulus outside the receptive field even though there was a stimulus within the receptive field. 5. Twenty-three percent (27/117) of neurons studied in the delayed-saccade task gave two bursts, one at the appearance of the stimulus and a second one around the saccade. This second burst generally did not occur when the monkey made the same saccade to a remembered target, but instead required the presence of the visual stimulus, and so we describe it as a reactivation of the visual response. Reactivation was also spatially specific. 6. The latency from reactivation to the beginning of the saccade ranged from 160 ms before the saccade to the beginning of the saccade. Reactivation usually continued for several hundred milliseconds after the saccade, sometimes for the duration of the trial. 7. Reactivation and enhancement are not the same mechanism. Although some cells showed both phenomena there was no correlation between enhancement and reactivation. 8. Cells that showed reactivation in the saccade task also showed reactivation at a weaker level in a suppressed-saccade task. In this task the monkeys had to hold fixation despite the disappearance of the fixation point and the continued presence of the peripheral stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cutaneous responses to histamine, compound 48/80, and codeine in patients with chronic renal failure

Pruritus is a common symptom associated with chronic renal failure (CRF). But increased plasma histamine levels and skin mast cell proliferation previously reported in these patients did not correlate with the intensity of the pruritus. Since increased mast cell releasability was described in chronic idiopathic urticaria, we attempted to examine whether this mechanism could explain pruritus in patients with CRF. Twenty-five patients with end stage renal failure were skin tested with histamine, codeine, and compound 48/80. There were nine patients on continuous ambulatory peritoneal dialysis, eight patients on hemodialysis, (tested both before and after dialysis) and eight patients with advanced CRF. Wheal area after intradermal injection of three concentrations of the above substances was measured. In general, the wheal areas in all patients with CRF were either similar to or smaller than those of the control group who were without renal impairment. In conclusion, patients with CRF with or without dialysis therapy demonstrated unchanged or decreased skin test responses to histamine, codeine, and compound 48/80. Increased mast cell releasability cannot explain the pruritus in patients with CRF.     

Studies on salivary γA in agammaglobulinaemia

Sera and saliva from nine adult subjects with acquired agammaglobulinaemia and from two individuals with a selective absence of γA were studied for γA and secretory γA content. In all subjects, except for one (B.Cr.), secretory γA was detected in saliva when γA was demonstrable by radial diffusion in serum, and salivary secretory piece alone was found in the absence of serum γA. Saliva B.Cr. contained both γA and free secretory piece, whereas the serum from this patient appeared to lack γA. However, when tested by quantitative complement fixation, a small amount of serum γA was detected. Chromatographic separation and subsequent immunological testing of saliva B.Cr. revealed the presence of secretory γA, secretory piece, and a small amount of serum-type γA. Severity of sinopulmonary infections in these subjects did not correlate with the presence or absence of secretory γA. These observations further substantiate that the production of serum and secretory γA is controlled by similar mechanisms, and that a quantitative defect in secretory γA production does not by itself account for the presence of sinopulmonary disease.     

The dentino-enamel junction revisited

The dentino-enamel junction is not an simple inert interface between two mineralized structures. A less simplistic view suggests that the dentino-enamel junctional complex should also include the inner aprismatic enamel and the mantle dentin. At early stages of enamel formation, fibroblast growth factor (FGF)-2 is stored in and released from the inner aprismatic enamel, possibly under the control of matrix metalloproteinase (MMP)-3. The concentration peak for MMP-2 and -9 observed in the mantle dentin coincided with a very low labeling for TIMP-1 and -2, favoring the cross-talk between mineralizing epithelial and connective structures, and as a consequence the translocation of enamel proteins toward odontoblasts and pulp cells, and vice versa, the translocation of dentin proteins toward secretory ameloblasts and cells of the enamel organ. Finally, in X-linked hypophosphatemic rickets, large interglobular spaces in the circumpulpal dentin were the major defect induced by the gene alteration, whereas the mantle dentin was constantly unaffected. Altogether, these data plead for the recognition of the dentino-enamel junctional complex as a specific entity bearing its own biological characteristics.     

Biologic activities of antibodies to the neutral-polysaccharide component of the Pseudomonas aeruginosa lipopolysaccharide are blocked by O side chains and mucoid exopolysaccharide (alginate).

Virulent strains of Pseudomonas aeruginosa are either of a nonmucoid, lipopolysaccharide (LPS)-smooth or mucoid, LPS-rough phenotype, and immunity to these different variants is efficiently mediated by antibodies specific to O antigens or mucoid exopolysaccharide (also called alginate), respectively. In addition to O side chains and core polysaccharide components, the LPS of P. aeruginosa also contains neutral-polysaccharide components that express antigenic determinants common to many clinical isolates. We evaluated antibodies specific to neutral polysaccharides for the ability to mediate opsonic killing and protective immunity. Antibodies to these antigens mediated opsonic killing of poorly virulent nonmucoid LPS-rough isolates but not of isogenic strains with either a LPS-smooth or a mucoid phenotype. Antibodies to neutral-polysaccharide antigens also failed to protect neutropenic mice from challenge with modest doses of LPS-smooth P. aeruginosa strains (< 10(3) CFU per mouse), whereas O-antigen-specific antibodies were highly protective. Antibodies to neutral polysaccharides deposited significantly (P = 0.002) more C3 onto LPS-rough strains than did antibodies to O side chains, but this situation was reversed when isogenic LPS-smooth strains were tested. Given that protective immunity against P. aeruginosa must be directed against either nonmucoid LPS-smooth strains or mucoid LPS-rough strains, it appears that antibodies specific to neutral-polysaccharide antigens do not protect against P. aeruginosa infection. Lack of protection is likely due to the ability of both O side chains and mucoid exopolysaccharide (alginate) to interfere with the opsonic killing activity of neutral-polysaccharide-specific antibodies.     

Husbands' and wives' adjustment to pregnancy and first parenthood

There are conflicting reports regarding type and extent of the change in couples' lives due to the arrival of a 1st baby. The present short-term longitudinal study of 39 volunteer couples had 2 major objectives: 1) to examine changes in couples' division of labor during the transition to parenthood; and 2) to investigate husband-wife differences in the associations between indices of marital and parental adjustment during the early postpartum months. Individual questionnaires and interviews were administered in couples' homes on 3 occasions: early pregnancy, late pregnancy, and 3-4 months postpartum. The major findings were that changes in household division of labor from early pregnancy to late pregnancy to 3-4 months postpartum demonstrated a curvilinear pattern, such that late pregnancy was characterized by more egalitarian household roles than was found in early pregnancy or postpartum. Marital adjustment mean scores suggested that marriages were functioning well at 3-4 momnths postpartum. Fathers' greater involvement with the baby was associated with better marital and parental adjustment, whereas fathers' postpartum participation in feminine household tasks was correlated with lower adjustment. In contrast to father, mothers' greater participation in baby care tasks was associated with lower marital adjustment. Mothers usually perceived changes in marriage and lifestyle due to the baby as more bothersome than did fathers. Adjustment to parenthood and marital adjustment measures were more interrelated more frequently for fathers than mothers. These findings underscore the complex associations among husbands' and wives' household roles, marital adjustment, involvement with baby, and adjustment to parenthood.     

Timing of Diosgenin Appearance in Suspension Cultures of Dioscorea deltoidea

Cycloheximide and compactin were added to cell suspension cultures of DIOSCOREA DELTOIDEA. Cycloheximide inhibited growth and diosgenin biosynthesis completely at 40 mg/l when added during the growth phase. Compactin partially inhibited growth and diosgenin production at 100 microg/l when added during the growth phase. [1- (14)C]-Acetate incorporation into diosgenin was about 20-fold higher when added during the early stages of growth as compared to addition in the stationary phase. Incorporation of [1- (14)C]-acetate into diosgenin was inhibited by compactin only during the early stages of growth. These results indicate the formation of an accumulating intermediary metabolite during the early stages of growth which is transformed into diosgenin when D. DELTOIDEA cells are in the stationary phase.