Trauma-induced glial proliferation: possible involvement of the immune system

Rat neurologlial cells proliferate following trauma to the frontal cortex. Since previous reports have indicated that activated T-lymphocytes secrete a factor which can induce the proliferation of glial cells in vitro, we investigated the effects of immunosuppression on the trauma-induced proliferation of glial cells in the rat. Animals were treated with either methotrexate (2.5 and 10 mg/kg/day), hydrocortisone (100 mg/kg/day), or saline for five days prior to lesioning of the cortex. Immunocompetence was estimated by measuring sheep red blood cell hemagglutination titers at the time of killing. On the last day of drug treatment, rats were mechanically lesioned on the frontal cortex, and the incorporation of intraventricularly injected 3H-thymidine (3H-TdR) into cortical DNA, a measure of glial cell proliferation, was determined two days after lesioning. Intraperitoneal treatment with methotrexate before the lesioning depressed 3H-TdR incorporation into brain DNA, and reduced hemagglutination titers and thymus and spleen weight. However, intramuscular hydrocortisone pretreatment, which had immunosuppressive actions similar to methotrexate, had a much smaller effect on 3H-TdR incorporation into brain DNA following trauma. Methotrexate given acutely after lesioning did not depress thymidine utilization in the lesioned rat cortex, apparently because of poor penetration of the folate analog into the brain. Thus, we conclude that inhibition of glial cell proliferation resulting from methotrexate pretreatment had been produced indirectly, probably by its severe immunosuppressive effects.

Effects of various catecholamine receptor antagonists, muscle relaxation and physical hindrance on shuttlebox self-stimulation

Certain drugs, particularly clozapine and clonidine, have been reported to increase selectively the latency to initiate brain stimulation (the ON latency) in a shuttlebox test of self-stimulation, suggesting a preferential attenuation of the "reward" component. The pharmacological selectivity of this reported effect was systematically evaluated. At doses that blocked bar-pressing self-stimulation, metoclopramide (3 mg/kg), prazosin (3 mg/kg) clonidine (0.1mg/kg), clozapine (3 mg/kg)and haloperidol (0.3 mg/kg), all elevated the ON latency to a greater extent than the OFF latency. Methocarbamol (200 mg/kg), and a muscle relaxant, also elevated the ON latency preferentially but the magnitude of this preferential effect was smaller than that produced by the other drugs. A hurdle in the center of the shuttlebox increased the ON and OFF latencies nonselectively. The shuttlebox procedure does not clearly discriminate among various substances that interfere with noradrenergic or dopaminergic neurotransmission, but the common profile produced by the these substances is distinguishable to some degree from simple motor disruption.

Legionnaires' disease in pneumonia patients in Iowa. A retrospective seroepidemiologic study, 1972-1977

The frequency of Legionnaires' disease among 586 cases of pneumonia that occurred in Iowa between fiscal years 1972 and 1977 was studied retrospectively on the basis of paired sera. The frequency of confirmed Legionnaires' disease was 4.1% and of presumptive Legionnaires' disease was 11.4%. Infections with the Legionnaires' disease (LD) bacterium were most frequent in the summer. Of the 22% of pneumonias for which a cause could be defined, Legionnaires' disease was third in frequency behind Mycoplasma pneumoniae and influenza A virus infections. Infections with the LD bacterium occurred in association with pneumonias in most age groups. The youngest patient with LD infection was a 5-year-old boy with pneumonia. The disease occurred 3.2 times more often in males than in females. In males, the frequency of confirmed and presumptive Legionnaires' disease increased steadily to plateau after the fourth decade at about 12% and 28%, respectively. In females the frequency of presumptive Legionnaires' disease was 7% to 16%, relatively evenly distributed over all age groups. Pneumonias associated with LD bacterium infection should be considered in the differential diagnosis of community-acquired pneumonias in most age groups.

Interdisciplinary study of diazepam sedation for outpatient dentistry

Patients unable to submit themselves to routine dental treatment under local anaesthesia were studied during treatment under diazepam sedation accompanied by local anaesthesia, and compared with a matched control group for psychiatric assessment. Physiological responses, operating conditions, amnesia, pain threshold, and recovery were all assessed by various tests.Some of the patients had an anxiety neurosis, and several had been referred because of previous failure to complete dental treatment. Satisfactory conditions were obtained in all but two instances, and no adverse physiological responses occurred with diazepam in an intravenous dose of 0.2 mg./kg. Patients were clinically safe to leave accompanied by a responsible adult within one hour of administration of the drug. Some patients showed an improvement in attitude towards dentistry following treatment.

Nutrient content of South African red meat and the effect of age and production system

Feeding systems, slaughter age and other production techniques notably influence the nutrient content of red meat. The modernization of the different South African production systems since the previous nutrient composition studies, justifies the necessity to update existing knowledge on the nutritional profile of South African produced beef. In addition, a need was identified to extrapolate the effect of the two different feeding systems (extensive and intensive) on this nutritional profile. Results indicate that the total lipid content of marketable young carcasses (age A, fat code 2) has decreased over time, in line with global health and nutrition trends for leaner foods. With the majority of beef from these young carcasses being produced on intensive grain-based feeding systems, South Africa has a unique advantage in terms of total lipid content of such grain-fed produce. Internationally, grain-fed red meat is in most cases higher in total and saturated fat content compared to grass-fed counterparts, while in South African the opposite was observed. In addition to total fat content, the role of various lipid fractions in human health has often been associated with specific produce positioning and marketing. South African grass-fed beef is significantly higher in healthy omega 3 fatty acids and conjugated linoleic acid, irrespective of degree of fat trimming. From a human nutrition perspective, it should be kept in mind that the total amount of omega 3 fatty acids per edible portion of beef produced in either production system is low in comparison to human dietary recommendations.Keywords: Beef, fatty acids, grain-fed beef, grass-fed beef, physical composition

Changes in the composition of South African red meat

Red meat often evokes a wide array of complex and contradictory arguments. It is viewed as the most expensive component of any diet, supplying many essential nutrients as part of a healthy, prudent eating plan. Yet, red meat is non-homogenous, unique to each country, and continually changing in composition. It is observed that the amount of fat on carcasses has reduced over time, simultaneously improving nutrient density through feed efficiency. The objective of this paper is to present composition data on South African lamb, mutton and beef, and report on the changes observed between local data and international data (for lamb and mutton), as well as changes in the composition of South African beef over time. South African lamb and mutton contain notably less fat and more nutrients per 100 g product than international sheep meat produced, rendering a lean product with a higher nutrient density. Compared to previous studies on South African beef, the current data indicate notable changes in the composition over time, specifically related to a reduction in fat content. This reduction together with changes in carcass weight has resulted in changes in carcass composition and thus changes in nutrient density. The data attest that in order to align industry processes, as well as legislation and marketing strategies, continued research on composition needs to be performed for the baseline information to remain relevant and accurate.Keywords: Beef, lamb, mutton, nutrient content, nutritional composition, South Africa