Peripheral olfactory deafferentation of the primary olfactory system in rats using ZnSO4 nasal spray with special reference to maternal behavior

A modified method of applying ZnSO4 to the olfactory mucosa is described. Treated rats experienced severe nasal congestion that cleared within 24 h; more persistent morbidity did not occur. Nonpregnant females observed with male intruders 24 h following ZnSO4 showed no alterations in behavior other than a reduction in anogenital sniffing, indicating that they were not hypoactive or irritable. In other experiments, lactating females were observed in a hole-board apparatus; 2 days posttreatment anosmia was confirmed in 80% of bilaterally ZnSO4-treated females by the absence of preference for pup odors. After bilateral but not unilateral ZnSO4 treatment, initially activity scores and nose pokes were equivalent in all groups, but later they both were lower than in controls, probably due to a more rapid habituation to the novel apparatus. We conclude that intranasal ZnSO4 by small-volume spray is a useful experimental tool.     

Prostaglandin-H synthase-1 (PGHS-1) gene is expressed in specific neurons of the brain of the late gestation ovine fetus

Prostaglandin (PG) E2 acts on the brain stem to modulate breathing activity in the ovine fetus. The source of this PGE2 is unknown and we hypothesized that it is produced locally in the developing brain and functions in a paracrine and/or autocrine manner. The purpose of the present study was to establish whether prostaglandin-H synthase-1 (PGHS-1), a crucial enzyme in de novo prostaglandin synthesis, is present and its gene expressed in the ovine fetal brain. Immunohistochemical and molecular hybridization techniques were used to identify sites of PGHS-1 immunoreactivity and PGHS-1 mRNA expression respectively in the brain of the ovine fetus in late gestation (approximately 126 days gestation, term 145 days). PGHS-1 immunoreactivity was localized to specific regions of the fetal brain, including the cortex, hypothalamus, hippocampal formation, superior colliculus of the midbrain, parabrachial nucleus of the pons, and the reticular formation, raphe, nucleus of the solitary tract, and gracile and cuneate nuclei of the medulla. The relative abundance of PGHS-1 mRNA in selected brain regions, as determined by Northern blot analysis, correlated qualitatively with the number of PGHS-1 immunoreactive neurons identified in each region. In situ hybridization demonstrated PGHS-1 mRNA to be localized in the same neurons or nuclei as PGHS-1 immunoreactivity. These results indicate that PGHS-1 synthesized de novo in many brain regions including two that are important in respiratory control: the pneumotaxic center (parabrachial nucleus) and the dorsal respiratory group (nucleus tractus solitarius) suggesting that prostaglandins that modulate fetal respiratory activity are synthesized endogenously.     

Clavicular osteomyelitis as a complication of head and neck surgery

To investigate the development of airway hyperresponsiveness in infantile guinea pigs, animals (10 days old) were immunized twice and challenged by inhalation of 1% ovalbumin for 10 min with 7 days intervals. Similar to adult guinea pigs, infantile ones developed an increased airway responsiveness to acetylcholine 24 hr after antigen challenge. There was a marked increase in the number of total leukocytes, eosinophils and lymphocytes in bronchoalveolar lavage fluid (BALF). Suplatast tosilate (suplatast) and pemirolast potassium (pemirolast) given orally throughout the experiments suppressed the development of airway hyperresponsiveness in infantile animals. They showed similar potency in the suppression of eosinophil accumulation in BALF and lung tissue, while suplatast inhibited lymphocyte accumulation stronger than pemirolast. Collectively, the present model of airway hyperresponsiveness in infantile guinea pigs may be useful in predicting the efficacy of antiallergic agents in the treatment of asthmatic children.     

Adherent neutrophils activate endothelial myosin light chain kinase: role in transendothelial migration

Increased vascular endothelial cell (EC) permeability and neutrophilic leukocyte (PMN) diapedesis through paracellular gaps are cardinal features of acute inflammation. Activation of the EC contractile apparatus is necessary and sufficient to increase vascular permeability in specific models of EC barrier dysfunction. However, it is unknown whether EC contraction with subsequent paracellular gap formation is required for PMN transendothelial migration in response to chemotactic factors. To test this possibility, we assessed migration of human PMNs across confluent bovine pulmonary arterial EC monolayers. Transendothelial PMN migration in the absence of a chemotactic gradient was minimal, whereas abluminal addition of leukotriene B4 (LTB4; 5 microM) resulted in significantly increased PMN migration. Reductions in EC myosin light chain kinase (MLCK) activity by EC monolayer pretreatment with specific MLCK inhibitors (KT-5926 or ML-7) or by increases in cAMP-protein kinase A activity (cholera toxin) significantly reduced PMN transmigration (30-70% inhibition). In contrast, pretreatment with the myosin-associated phosphatase inhibitor calyculin resulted in the accumulation of phosphorylated myosin light chains, EC contraction, and significantly enhanced PMN migration. Finally, the interaction of PMNs with 32P-labeled EC monolayers was shown to directly increase EC myosin phosphorylation in a time-dependent fashion. Taken together, these results are consistent with the hypothesis that the phosphorylation status of EC myosin regulates PMN migration and further indicate that EC MLCK is activated by chemoattractant-stimulated PMNs. Neutrophil-dependent activation of the EC contractile apparatus with subsequent paracellular gap formation may be a key determinant of transendothelial PMN migration responses to chemotactic agents.     

Hypoxia-reoxygenation is as damaging as ischemia-reperfusion in the rat liver

OBJECTIVE: We hypothesized that the extent of injury and release of xanthine oxidase, an oxidant generator, into the circulation would be less in normal-flow hypoxia-reoxygenation than in equal duration no-flow ischemia-reperfusion. DESIGN: Randomized study. SETTING: University-based animal research facility. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: The livers were isolated, perfused, and then randomly subjected to 2 hrs of hypoxia (normal flow, low oxygen) or ischemia (no flow, no oxygen), and 2 hrs of reperfusion. Hepatocytes were also isolated, and were subjected to either: a) hypoxia (0, 2, 4, and 6 hrs); or b) hypoxia (2 and 4 hrs) with reoxygenation (2 hrs). MEASUREMENTS AND MAIN RESULTS: The extent of liver injury (as assessed by release of hepatocellular enzymes) and the release of xanthine oxidase were measured from isolated-perfused rat livers and cultured hepatocytes. The pattern of release of xanthine oxidase in isolated-perfused liver effluent was different in hypoxia-reoxygenation compared with ischemia-reperfusion. During hypoxia, xanthine oxidase gradually increased in the effluent; then, the xanthine oxidase decreased to low concentrations during reoxygenation. After ischemia, there was a sharp spike in xanthine oxidase at 1 min of reperfusion, with a rapid decrease to low concentrations. The total release of xanthine oxidase during hypoxia-reoxygenation was similar to that during ischemia-reperfusion. Lactate dehydrogenase and other markers of liver injury showed a pattern of release that was similar to that of xanthine oxidase, but the total release of markers was not different between the two groups. In hepatocytes, most of the release of enzymes occurred in hypoxia, and the rate of release was not different between hypoxia and hypoxia-reoxygenation. CONCLUSIONS: Hypoxia-reoxygenation results in as much damage to the liver as ischemia-reperfusion, and results in the release of a similar amount of oxidant-producing xanthine oxidase into the circulation.