PATHOPHYSIOLOGY

Pathophysiology

Pathophysiology

A) Clearly, the most important pathologic correlate of Meniere's disease is fluctuating and symptomatic endolymphatic hydrops, predominantly of the pars inferior. The authors have found rupture of the endolymphatic membrane (Reissner's or the saccular wall) to occur in approximately one third of cases in their human temporal bone collection, usually in the pars inferior. (Andersson 2001) It seems logical that both physical and chemical mechanisms can concomitantly cause the symptoms. Chemical factors characteristically include osmotic and hydrostatic pressure alterations and, most likely, changes in membrane permeability, causing egress of inappropriate ions across the membrane barrier so as to incite sensory dendrites leading to cochlear and vestibular symptoms.

B)Among currently available bronchodilators for feline patients, salbutamol was selected as a SA ß2-adrenergic agonist because it is frequently used as a rescue medication in the symptomatic management of human asthma and COPD exacerbations (Buhl and Farmer, 2004), as well as in naturally asthmatic (Padrid, 2000). In addition to being the lone LA ß2-adrenergic agonist suitable for lung delivery in salmeterol, as an adjunctive treatment to inhaled corticosteroids, has been shown in human asthma to lead to a greater improvement in symptoms and lung function compared to increasing the dose of inhaled corticosteroids (Edwards 2006). Even though in vitro studies tend to implicate serotonin in allergen-induced bronchoconstriction (Scott 2002) , the multifactorial pathophysiology of feline bronchial disease requires the need to widen therapeutic options with further investigations on anticholinergics (such as ipratropium bromide) and the methylxanthines.

C) Increased risk of diarrhoea caused by Clostridium difficile in elderly patients receiving cefotaxime, Clostridium difficile is a Gram positive anaerobic spore forming bacillus whose pathogenicity is related to exotoxin production in the large bowel. (Dent 2003)This may result in disease ranging from trivial diarrhoea to life threatening pseudomembranous colitis. Between 1982 and 1993 there was a 15-fold national increase in reported C difficile infections that was most marked in patients aged over 65.1 C difficile diarrhoea is almost exclusively acquired in hospital and strongly associated with the use of broad spectrum antibiotics. (Hassan 2005)In 1993 the British Thoracic Society recommended cefotaxime and cefuroxime as first line antibiotics for treating severe community acquired pneumonia of unknown cause in adults.2 As a result the use of cefotaxime increased 20-fold in our unit. After November 1993 we also saw an unexpected increase in the incidence of C difficile diarrhoea, and we therefore sought to determine whether the two events were related.

D) Pharmacokinetics is a discipline that uses mathematical models to describe and predict the time-course of drug concentrations in body fluids. During the last 30 years, our ability to apply pharmacokinetic principles to clinical psychiatry and psychopharmacology has undergone major advances. Important improvements in analytical chemistry techniques partly explain this progress. Methods for quantization of drug concentrations in plasma and tissues are now highly sensitive and specific. For almost all drugs used to treat mental disorders, techniques such as gas chromatography, liquid chromatography, and mass spectroscopy can be used to quantitative serum or plasma concentrations of these agents and their pertinent metabolites ...