No abstract

In humans, the brain accounts for about 20% of the body's free cholesterol, most of which is synthesized de novo in brain. To maintain cholesterol balance throughout life, cholesterol becomes metabolized to 24S-hydroxycholesterol, principally in neurons. In mouse, rat, and probably human, metabolism to 24S-hydroxycholesterol accounts for about 50% of cholesterol turnover; however, the route by which the remainder is turned over has yet to be elucidated. Here, we describe a novel liquid chromatography (LC) multistage fragmentation mass spectrometry (MS n ) methodology for the identification, with high sensitivity (low pg), of cholesterol metabolites in rat brain. The methodology includes derivatization to enhance ionization, exact mass analysis at high resolution to identify potential metabolites, and LC-MS n (n53) to allow their characterization. 24S-hydroxycholesterol was confirmed as a major oxysterol in rat brain, and other oxysterols identified for the first time in brain included 24,25-, 24,27-, 25,27-, 6,24,-7a,25-, and 7a,27-dihydroxycholesterols. In addition, 3b-hydroxy-5-oxo-5,6-secocholestan-6-al and its aldol, two molecules linked to amyloidogenesis of proteins, were characterized in rat

A non-experimental research design using questionnaires, was undertaken to find out what information out of that commonly given following myocardial infarction (MI), patients and their spouse/partners rate as being most and least important. These results were then compared with the results obtained from nurse subjects, who were given the same instrument to complete. Eighteen subjects were recruited for each of the three subject groups. Results indicated that some congruency existed between the three groups in terms of what they perceived as the most and least important categories of information. Yet, the scores for some informational categories included on the instrument, were significantly different between the nursing and two other groups (P < 0.01). However, in relation to the patient and spouse/partner groups, only a weak difference (P < 0.10) was found for the category 'dietary information'. These findings and others are discussed, and recommendations are made for improving the information giving process post-MI.

The effect of various hepatotoxicants on urinary taurine and urinary creatine has been studied in the rat. Several hepatotoxic agents, carbon tetrachloride, thioacetamide, galactosamine and allyl alcohol which all caused hepatic necrosis (sometimes accompanied by steatosis), resulted in a rise in urinary taurine and in some cases creatine, when administered to rats. Ethionine and hydrazine also raised urinary taurine but caused only steatosis and did not raise urinary creatine. Therefore urinary taurine and possibly creatine may be useful markers of liver injury and dysfunction. Liver taurine levels were also affected by some of the hepatotoxicants but in those cases where there was a rise in urinary taurine this could not be accounted for by the loss in liver taurine. It is suggested that the increase in urinary taurine is partly due to changes in protein synthesis and hence in sulphur amino acid metabolism caused by hepatotoxic agents. However, bromobenzene did not increase urinary taurine and alpha-naphthylisothiocyanate and lithocholate caused reduced levels. It is suggested that this lack of increase in urinary taurine may be due to depletion of glutathione or interference with the biliary system.

C-reactive protein (CRP), haptoglobin (Hp) and fibrinogen (Fbgn) are acute phase reactants (APRs), the blood levels of which increase during acute inflammation. However, although the levels of these APRs are used to monitor inflammation in man, their usefulness and sensitivity as markers of inflammation in rodents are less clear. We therefore wished to evaluate, in a comparative fashion, a prototype immunoassay for serum CRP, a commercial assay for serum Hp, and an automated assay for Fbgn, using a model of acute inflammation in the rat. Additionally, pro-inflammatory cytokines and serum protein fractions were also measured. The model of inflammation used was the intraperitoneal injection of Freund's complete adjuvant (FCA). In a concluding experiment, findings with Hp in the FCA rat model were validated in a toxicologically relevant study involving the induction of acute hepatic inflammation using the model hepatotoxicant carbon tetrachloride (CCl(4)). Female Wistar Han rats were treated with a single injection of FCA in a dose-response study (1.25-10.0 ml/kg, sampling at 36 h) and two time-course studies (over 40 h and 21 days). In a final experiment, rats were dosed with CCl(4) at 0.8 ml/kg and sampled over a 17-day period. In FCA and CCl(4) experiments, serum/plasma was prepared and tissues taken at autopsy for histological assessment (CCl(4) study only). In the dose-response study, serum CRP, Hp and plasma Fbgn were increased at all FCA dose levels at 36 h post-dosing. Serum alpha(2) and beta(1) globulin fractions were also increased, while albumin levels were decreased. In the 40-h time-course study, CRP levels peaked at 25-40 h post-dosing, to approximately 120% of control (as 100%). Hp levels increased to a maximum at 25 and 40 h post-dosing with values greater than 400% of control, and alpha(2) and beta(1) globulin fractions peaked at 30 and 40 h post-dosing to 221 and 187% of control, respectively. Increased serum interleukin-6 (IL-6) and interleukin-1beta (IL-1beta) levels peaked at 20 h (11-fold) and 25 h (19-fold), respectively. In a 21-day time-course study, no increased CRP levels were measured despite elevated levels of Hp, which peaked at 36 h (approximately 7-fold above control), and remained elevated up to 21 days. IL-6 and IL-1beta levels peaked at 12 h (19-fold) and 24 h (28-fold), respectively. Liver histopathology of animals treated with CCl(4) showed centrilobular hepatocellular degeneration and necrosis (most significant at 36 h) with an inflammatory response (most significant at 48 h). Resolution of the lesion was complete by 4 days post-dosing. Serum alanine aminotransferase, aspartate aminotransferase and glutamate dehydrogenase levels peaked at 36 h post-dosing. Hp levels increased maximally at 48 h (426% of control). We conclude that serum CRP is a poor marker of acute inflammation in the rat in comparison with serum Hp and plasma Fbgn. Between Hp and Fbgn, serum Hp is shown to be the most sensitive and useful marker of acute inflammation.