A generally nonlethal Salmonella typhimurium infection in weanling rats produced bacterial myocarditis and myocardial hyperplasia. Myocardial lesions were characterized by focal infiltrates of inflammatory cells (predominantly mononuclear). segmental myocyte necrosis, and incipient fibrosis. Although bacterial infections are infrequently associated with myocarditis, the S. typhimurium infection in young rats produced a new experimental model of diffuse myocardial inflammatory foci. Biochemical changes in the myocardium included great increases in total myocardial contents of protein (23%), RNA (39%) and DNA (43%) and several lipid fractions (35–55%) as well as in tissue activities of acid hydrolases, such as cathepsin D (124%) and β‐glucuronidase (135%), all of which contrasted with the relatively limited areas of histologic involvement (1.5%). To study the effects of additional stress in this model infection, some rats were exercised by forced running in wheels for 2 hours and others were fasted for 24 hours before samples were obtained. The short period of forced exercise in this infection caused an additional increase of myocardial protein content (47%) but with no additional change in histology. The expected fasting‐induced degradation of protein as well as an infection‐associated increase in myocardial lipids were each prevented when rats were fasted during ongoing acute infection. Protein degradation, as reflected by heightened acid hydrolase activities, seemed to occur at a similar rate regardless of other stresses, whereas the rate of myocardial protein synthesis appeared to be alterable.
ExtractExperimentally induced endotoxemia in the rhesus monkey produced a two-to fourfold increase in plasma triglyceride concentration; glucose administration partially prevented this rise. Plasma free fatty acid and phospholipid values were depressed 40-50y0 of control values whereas cholesterol values were unchanged. Endotoxin-treated monkeys displayed slowed glucose disap~earance (K values, 2.2 versus 1.1) and higher levels of sugar in blood when given glucose (72 =t 8 mg/ 100 ml versus 15 1 + 1 1 mg/ 100 ml). These studies indicate that endotoxin has a marked effect on the pattern of substrate utilization by the host.
SpeculationAlterations in lipid and carbohydrate metabolism affecting substrate utilization of the host may account for many of the clinicopathologic events associated with endotoxemia. Therapeutic measures designed to increase the availability of metabolic fuels for efficient cellular fuel utilization might be of value to patients during endotoxemia.
The isometric muscular strength and endurance of 10 male volunteers were measured four times per day for 15 consecutive days. Eight experimental subjects were inoculated with sandfly fever virus and two double-blind controls were given sterile saline on the seventh day. The muscular performances of the control subjects remained essentially constant throughout. Decrements in muscular strength and endurance occurred with the experimentals during the brief period of illness three or four days after inoculation, then performances improved towards baseline levels.
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