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Articles by P. M Wise
Total Records ( 2 ) for P. M Wise
  P. M Wise , K Zhao and C. J. Wysocki
 

Relatively, few studies have focused on how nasal irritation changes over time. To simulate the rhythm of natural respiration, subjects received 3-s pulses of volatile organic compounds interspersed with 3-s pulses of clean air. Each trial, subjects received 9 pulses of a chemical vapor over about 1 min. Subjects rated nasal irritation from each pulse using magnitude estimation. Within a trial, compound and concentration were fixed. Compound (ethanol, n-butanol, or n-hexanol) and concentration (4 levels for each compound) varied across trials. For all stimuli, rated irritation decreased over time (adaptation). Plots of log-rated intensity versus elapsed time were approximately linear (intensity decreased by a fixed ratio per unit time). Interestingly, the slopes of intensity versus time functions differed very little: Regardless of concentration and compound, rated irritation decreased by about 32% over the 9 pulses. The basic mechanism of short-term adaptation may be the same for the 3 alcohols studied. Regardless, these data suggest that very simple models might be able to describe some aspects of perceptual dynamics quite well.

  T. I Lam , P. M Wise and M. E. O'Donnell
 

Blood-brain barrier (BBB) Na transporters are essential for brain water and electrolyte homeostasis. However, they also contribute to edema formation during the early hours of ischemic stroke by increased transport of Na from blood into brain across an intact BBB. We previously showed that a luminal BBB Na-K-Cl cotransporter is stimulated by hypoxia, aglycemia, and AVP and that inhibition of the cotransporter by intravenous bumetanide significantly reduces edema and infarct in the rat middle cerebral artery occlusion (MCAO) model of stroke. More recently, we found evidence that intravenous cariporide (HOE-642), a highly potent Na/H exchange inhibitor, also reduces brain edema after MCAO. The present study was conducted to investigate which Na/H exchange protein isoforms are present in BBB endothelial cells and to evaluate the effects of ischemic factors on BBB Na/H exchange activity. Western blot analysis of bovine cerebral microvascular endothelial cells (CMEC) and immunoelectron microscopy of perfusion-fixed rat brain revealed that Na/H exchanger isoforms 1 and 2 (NHE1 and NHE2) are present in BBB endothelial cells. Using microspectrofluorometry and the pH-sensitive dye BCECF, we found that hypoxia (2% O2, 30 min), aglycemia (30 min), and AVP (1–200 nM, 5 min) significantly increased CMEC Na/H exchange activity, assessed as Na-dependent, HOE-642-sensitive H+ flux. We found that AVP stimulation of CMEC Na/H exchange activity is dependent on intracellular Ca concentration and is blocked by V1, but not V2, vasopressin receptor antagonists. Our findings support the hypothesis that a BBB Na/H exchanger, possibly NHE1 and/or NHE2, is stimulated during ischemia to participate in cerebral edema formation.

 
 
 
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