Biomedical subjects
Publications and source records attributed to S Hurwitz.
The 4th case of botulism in South Africa is reported. Unusual features are the detection of toxin in the patient's serum 7 weeks after the onset of the illness and the need for 14 weeks' intermittent positive pressure ventilation. Symptomatic treatment and meticulous nursing resulted in complete recovery. The microbiology, pathophysiology, clinical features, diagnosis and management of botulism are briefly reviewed.
Eighty-five samples of pleural fluid obtained from 76 patients with biopsy-proven tuberculous pleurisy were examined cytologically. Numerous reactive mesothelial cells were present in only 1,2% of specimens examined. In contrast, 65,3% of pleural fluid aspirates obtained from a control group of patients in congestive cardiac failure contained marked mesothelial exfoliation. The suggestion that the presence of numerous, often highly reactive mesothelial cells in a pleural aspirate makes the diagnosis of tuberculosis unlikely is confirmed.
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Starch digestion and glucose absorption were determined in vivo along the chick's (Gallus domesticus) intestine, using 91Y and 51Cr-EDTA as unabsorbed reference substances. About 65% of the ingested starch was digested up to the end of the duodenum, 85% up to the end of the jejunum and about 97% at the terminal ileum. A fraction of about 97% of the glucose, ingested or released from ingested starch, was absorbed. The duodenum was the major site of glucose absorption which continued at a decreased rate down the small intestine. Glucose absorption increased linearily with luminal concentration with no indication of saturation. The apparent permeability for glucose was similar for the jejunum and ileum.
The site of digestion and absorption of protein was examined in chicks fed soybean meal and casein and in turkeys fed soybean meal, using 91YCl3 as a non-absorbed reference substance. In soy-fed chicks, peptides with molecular weight (MW) between 8,000 to 15,000 accumulated in the proximal small intestine, and low MW peptides accumulated distally. A similar pattern was observed in soy-fed turkeys, although with events occurring proximally to those in the chick. In casein-fed chicks, a gradual reduction in the peptide MW was observed with increasing distance from the pylorus. The rates of formation and absorption of peptides with MW below 500 were similar throughout the small intestine in soy-fed chicks; whereas, the rate of their formation exceeded absorption rate in casein-fed chicks. Net secretion of nitrogen into the duodenum was observed in soybean-fed chicks, no net secretion in casein-fed chicks and 50% absorption in soybean-fed turkeys with net secretion in the gizzard. From the sequence of digestive and absorptive events, apparently solubilization and breakdown of intermediate peptides are rate-limiting in protein absorption from soybean meal diets. But when casein is fed, the rate of uptake of low MW peptides appears to be limiting.
The absorption and excretion in vivo of cholecalciferol or 25-hydroxycholecalciferol (25-HCC) were determined in chicks (Gallus domesticus) and turkeys (Meleagris gallopavo). The overall net cholecalciferol or 25-HCC absorption in chicks and cholecalciferol in turkey poults was 66.5 +/- 3.3, 74.9 +/- 3.7 and 83.6 +/- 7.1% of the intake, respectively. The absorption of cholecalciferol or 25-HCC in chicks and turkeys occurred at the upper part of the intestine. 25-HCC, esters and non-polar metabolites of cholecalciferol or 25-HCC, and their polar metabolites, were secreted in the duodenum of chicks and turkeys but were partially reabsorbed at the upper part of the jejunum.
Intestinal mucosal uptake of protein complexed-fatty acids was studied in ligated duodenal loops in the chick. Increasing the concentration of an albumin oleic acid-complex resulted in a linear increase in uptake of oleic acid. Varying the albumin-to-oleic-acid ratio with constant albumin concentration resulted in depressed oleic acid uptake when the ratio was below 1:3. Uptake of oleic acid complexed to albumin was increased by some 60% on addition of taurocholic acid above its critical micellar concentration. In the absence of albumin, oleic acid uptake was some 60% high from a micellar solution. Uptake of lauric acid from aqueous solution was linear with concentration until its maximum solubility was reached, whereas uptake from albumin complexes at varying lauric acid concentrations was not linear with increasing concentration. Stearic acid exhibited lowest uptake and linoleic and linolenic acid highest uptake both when complexed to albumin or from micellar solution, although albumin-complexed fatty acids were transported at about half the rate of micellar fatty acids. We concluded that some proportion of fatty acids complexed to lipophilic proteins can be absorbed in the intestine in the absence of bile acids. When oleic acid was complexed to casein, bovine serum albumin or beta-lactoglobulin at protein:oleic acid ratio of 1:10 serosal transport was 40 to 50% of mucosal uptake.
In order to gather prospective information on the chronological age at which lung functions start to decline, follow-up measurements were carried out on 38 young adults (30 men and eight women) whose respiratory and cardiac function had been studied previously in the course of a survey of high school students. In the 15 subjects who had reached adult height at the time of the first study, only the vital capacity showed no change between studies, while forced expiratory flow rates (FEV1, MMEF), transfer factor (TLCO) and alveolar volume (VA) all decreased. By contrast, in the 23 subjects who had grown in stature since the previous tests, there was an increase in the slow and forced vital capacity, no consistent change in FEV1 and MMEF, and a decrease in TLCO. The findings are consistent with the view that the age-related decline does not start at the same chronological age for all lung functions, and suggest that structural changes associated with biological "aging" affect some functions before others. The results also illustrate the inadequacy of predicting values for early adulthood by backward extrapolation from later decades or forward extrapolation from the teens, and underline the need for comprehensive studies to elucidate the pattern of change which accompanies growth, maturation, and early adulthood.
The amino acid requirements of broiler chicks, on a weekly or biweekly basis, were calculated according to a model presented previously (Hurwitz et al., 1978). Based on the present results, the model has been somewhat modified. The model requirements provided the basis for computer-designed diets which were fed to chicks of different ages and were composed to others computed on the basis of NRC (1971, 1977) requirements. In all cases the model-based diets, which were considerably lower in protein, supported weight gains equivalent to those obtained on NRC-based diets. The relatively poorer feed efficiency observed in the first trial with chicks fed the model-based diets, could be alleviated by equalizing both energy and lipid concentrations in the experimental diets. Thus, equal growth and feed efficiency were obtained with the model and NRC (1971)-based diets, for 2- to 10-week-old chicks. The possible reasons for the slightly higher abdominal fat content of the chicks fed the model-based diets are discussed.
Health surveys were carried out in two factories, one in which only chrysotile had been used and one in which chrysotile, crocidolite and amosite had been used. The same health questionnaire, given by the same interviewer, and the same lung function tests recorded on the same apparatus were carried out as in previous studies with Quebec chrysotile asbestos miners and millers. Results were expressed as prevalence % abnormality. Despite shorter exposure to apparently lower levels of dust, the factory workers showed a greater prevalence of certain symptoms and of respiratory function abnormality than the miners and millers. The results suggest a greater effect of process than of fibre type on these health measurements, a finding with implications for control and one which deserves further study.
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There is a significant incidence of active pulmonary tuberculosis with coexisting lung cancer. It is likely that the cancer activates dormant tuberculosis. In a population group beset by a high incidence of tuberculosis, the heavy smoker who has attained his fifth decade seems particularly vulnerable to the combined diseases.
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A side-effect of high-dose corticosteroid therapy, namely the development of Kebsiella meningitis, in an asthmatic patient is reported. The possible mechanisms involved are discussed.
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Male chicks, fed low, normal, or high calcium- and cholecalciferol-containing diets for 14 days, were given three combined injections of 17 beta-estradiol and testosterone (7 and 2.4 mg/kg/dose, respectively) or the vehicle alone, at 3-day intervals. The hormonal treatment resulted in increased plasma calcium and medullary bone calcium concentrations, independently of the dietary calcium intake. Kidney 25-hydroxycholecalciferol-1-hydroxylase and duodenal calcium-binding protein were increased in response to gonadal hormones. The magnitude of this response markedly diminished with increased calcium intake and almost completely disappeared in chicks fed the high calcium diet. The results suggest that the increases in plasma calcium and medullary bone formation due to gonadal hormones are independent of calcium intake while the effect of hormones on duodenal calcium-binding protein and the 25-hydroxycholecalciferol-1-hydroxylase activity appears to be mediated through the change in calcium needs due to medullary bone formation.