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Biomedical subjects

M H Merson

Publications and source records attributed to M H Merson.

At least 19 recordsLinked to original sources
PubMed1989

Alpha-tocopheryl succinate protects hepatocytes from chemical-induced toxicity under physiological calcium conditions.

Rat and canine hepatocyte suspensions were exposed to toxic concentrations of ethyl methanesulfonate (EMS) and ionophore A-23187 in the presence and absence of extracellular calcium (Ca2+) and alpha-tocopheryl succinate (alpha-TS). The exogenous administration of alpha-TS (25 microM) completely protected hepatocytes from chemically-induced toxicity when exposed to 'physiological' free extracellular calcium concentrations (0.8-1.5 mM). Under these protective conditions the cellular accumulation of both alpha-TS (2.8 nmol/10(6) cells) and alpha-T (0.91 nmol/10(6) cells) were observed. Hepatocytes exposed to unesterified alpha-tocopherol (alpha-T, 25 microM) or alpha-tocopheryl acetate (alpha-TA, 25 microM), however, were not protected from the toxic effect of chemicals even though these treatments resulted in the marked accumulation of cellular alpha-T (2.65 nmol/10(6) cells) and alpha-TA (2.3 nmol/10(6) cells), respectively. Our findings suggest that the supplementation of endogenous stores of alpha-T or alpha-TA does not promote protection against chemical toxicity and that alpha-TS cytoprotection results not from the accumulation of alpha-T but rather from the cellular presence of the intact alpha-TS molecule. Thus alpha-TS appears to possess cytoprotective properties that differ from other vitamin E congeners.

Animals↗
PubMed1988

Control of diarrhoeal diseases.

During its early years, WHO was primarily concerned with epidemic control, standardization and quality control of vaccines, and administration of the International Sanitary Regulations. Among the acute enteric infections, cholera received the greatest attention because of its propensity for rapid epidemic spread. When the seventh pandemic of cholera began in 1961, WHO responded with a greatly expanded programme of activities which included cooperation with countries in training and control efforts, and research on treatment and prevention, especially vaccine development. At the same time, numerous training courses were held on enteric infections and a series of controlled field trials established the degree of protection conferred by existing typhoid and paratyphoid vaccines. In 1970, when the cholera pandemic spread to Africa, the emergency assistance programme was reactivated, with increasing attention to the provision of appropriate treatment, especially oral rehydration therapy, rather than the supply of ineffective vaccines. The requirement of cholera vaccination for international travel in the International Health Regulations was abolished in 1973 by the World Health Assembly. Another public health problem of importance during the 1970s was the increase in antibiotic resistance of enteric bacteria, especially Shigella dysenteriae 1 and Salmonella typhi, first in Central America and Mexico and later in Asia. There was a notable acceleration in research on diarrhoeal disease and especially on cholera during this period, with the discovery of several new viral and bacterial agents of diarrhoea, advances in knowledge of intestinal immunity indicating that better protection might be achieved with oral vaccines, and the demonstration of the effectiveness of a single formulation of oral rehydration salts (ORS) in the treatment of all diarrhoeas including cholera.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholera↗
PubMed1984

Nutritional status, body size and severity of diarrhoea associated with rotavirus or enterotoxigenic Escherichia coli.

Children with severe malnutrition have an increased risk of death from diarrhoea. To determine if the clinical manifestations of specific types of diarrhoea differed according to the nutritional status or size (weight and length) of the patient, we studied children with acute diarrhoea associated with rotavirus or enterotoxigenic Escherichia coli. In this study we found that a child's body size, which was determined by his age and nutritional status, was a significant predictor of his rate of stool output per kilogram of body weight. Thus, children who are small because of young age and/or malnutrition appear to lose a greater proportion of their total fluid volume during diarrhoea and might be expected to have a higher frequency of severe dehydration and death, if untreated.

Bangladesh↗
PubMed1982

Contamination of weaning foods and transmission of enterotoxigenic Escherichia coli diarrhoea in children in rural Bangladesh.

In longitudinal studies of infectious diseases and nutrition in Bangladesh, we determined the degree of bacterial contamination of traditional weaning foods and evaluated the role of these foods in the transmission of diarrhoeal diseases. 41% of samples of food items fed to weaning aged children contained Escherichia coli; these organisms were used as indicators of faecal contamination. Milk and foods prepared particularly for infants were more frequently and heavily contaminated with E. coli than was boiled rice, and E. coli levels were found to be related to the storage of cooked foods at high environmental temperatures. 50% of drinking water specimens also contained E. coli, but colony counts were approximately 10-fold lower than in food specimens. The proportion of a child's food samples that contained E. coli was significantly related to the child's annual incidence of diarrhoea associated with enterotoxigenic E. coli. This observation underscores the importance of seeking locally available foods that are hygienic as well as nutritious to supplement the diets of breastfeeding children in developing countries.

Bangladesh↗
PubMed1982

Endemic cholera in rural Bangladesh, 1966-1980.

Since 1963, the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), formerly the Cholera Research Laboratory, has maintained a field station in Matlab to treat patients from a surveillance population of 240,000 who have cholera and other diarrheal diseases. Since 1966, the authors have analyzed hospital records of 7141 surveillance-area patients culture-positive for v. cholerae 01 to relate the seasonality, age and sex distribution, and geographic trends with hypotheses concerning transmission, immunity, and risk groups. From this review, they have found that: 1) children 2-9 years old and adult women are most commonly hospitalized for cholera; 2) V. cholerae 01 emerges simultaneously throughout the area of surveillance, with the early cases being of different phage types; 3) three patients were hospitalized twice for cholera compared with 29 expected on the basis of life-table analysis (p less than 0.01), suggesting that immunity to severe disease conferred by previous illness may be stable and long-lasting; 4) no constant relationship was found between the times of onset or peaks of the yearly cholera epidemic and the times of onset or peaks of the monsoon rains or river water levels; and 5) an outbreak of multiply antibiotic-resistant V. cholerae 01 infection documented in 1979 raises questions about the dissemination of resistance plasmids, antibiotic-use patterns, and the need for other drugs in addition to tetracycline. While little progress has been made in understanding the mode of transmission of v. cholerae 01, and in identifying practices for prevention, fluid therapy in this area has decreased the case fatality rate significantly and provides guidance for similar programs elsewhere.

Adolescent↗