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Biomedical subjects

M H Ross

Publications and source records attributed to M H Ross.

At least 55 records · Page 3Linked to original sources
PubMed1989

Awareness of oral rehydration at well-baby clinics in Johannesburg.

A questionnaire regarding knowledge about oral rehydration therapy (ORT) was administered to 1087 adults bringing Asian, black, coloured and white children to under-5 clinics in Johannesburg. Although 54% had heard about ORT, misconceptions existed in this group and half thought that ORT stops diarrhoea. There were no significant differences in awareness of ORT between the different population groups. Awareness increased with age of the child, the birth order of the child and the educational level of the adult. These three factors were associated with statistically significant differences in awareness. Of these, educational level was the most important. The main first source of information about ORT was clinic sisters (54%), although when a child has diarrhoea a doctor is most commonly consulted (43%). Less-educated mothers of newborn first children appear to be in most need of health education, and recommendations to involve this group and health professionals in Johannesburg are discussed.

Adult↗
PubMed1985

Dietary habits and the prediction of life span of rats: a prospective test.

A multivariable statistical model for predicting the duration of life of rats permitted to select their own diets was evaluated prospectively. With information relating to pre-adult dietary habits and growth responses, the predicted length of life for an individual closely matched the observed life span; the average absolute error was 11%. This suggests that, even under normal feeding conditions, the diet/growth history is an important factor bearing on death rate. In general, an early adult death age is associated with a high food intake prior to adulthood particularly when coupled with a high efficiency of food utilization during the post-puberty period, a rapid growth rate and early attainment of mature weight. Deviations from this pattern serve to increase the duration of life of the individual.

Animals↗
PubMed1984

Down's syndrome: is there a decreased population of neurons?

Although gross abnormalities have been described in the brains of patients with Down's syndrome (DS), microscopic studies have revealed only minor and inconsistent findings. We compared two DS brains, in whole-brain serial sections, with similarly prepared age- and sex-matched normal controls. Architectonic abnormalities were noted, and cell counts revealed a significant poverty of granular cells in the DS brains, particularly in granular fields such as areas 3, 17, and 41. Golgi studies demonstrated all major cell types. A striking feature of the brain morphology in DS may be the curtailment of a specific cell type, most likely the aspinous stellate.

Adult↗
PubMed1983

Contribution of body weight and growth to risk of anterior pituitary gland tumors of the rat.

The dietary and growth histories of noninbred male Charles River COBS rats permitted freedom of dietary choice throughout life were analyzed to determine the conditions associated with the spontaneous occurrence of anterior pituitary gland tumors (PT). The animals were allowed to regulate their protein intake apart from energy intake. Multivariable models were derived distinguishing rats that develop PT from those remaining free of tumors throughout life. Conventional fixed diet studies suggested that the quantity and quality of the diet consumed would be the best explanatory variables. However, body weight-related variables were found to be more important. The interacting, time-related conditions conductive to a high probability of PT occurrence included an unusually high growth rate associated with a high level of conversion of the food consumed into body mass during early life and a high intake of protein relative to body weight during early adult life. The accuracy in identifying rats with PT was even greater if mature body weight was included as an explanatory variable.

Adenoma↗
PubMed1983

Body weight, dietary practices, and tumor susceptibility in the rat.

The mature body weight of outbred CD-Crl:COBS CD(SD)BR male rats permitted to select their own diets throughout life was shown to correlate linearly with the frequency of spontaneous tumors. In an analysis of the dietary practices of these animals, a multifactorial model was derived--for which prepuberty and early post-puberty data only were used--that accounted for a large proportion of the variance in mature weight. The level of food or calorie intake proved less informative than the following: the interactive effects of food intake relative to body weight, the proportion of protein and carbohydrate constituents in the diet, the intake of each of these components, and, particularly, the efficiency with which the diet consumed was used for growth during early postweaning life. In a prospective study of other rats maintained on a similar feeding regimen, the model was found to be an accurate predictor of mature weight. Several of the explanatory factors necessary for estimation of body weight also contributed to tumor susceptibility. Nonetheless, both dietary and body weight-related factors in a specific time-related sequence were required to explain variation in spontaneous tumor susceptibility.

Age Factors↗
PubMed1983

Dietary practices of early life and age at death of rats with tumors.

The association between the age at death of rats that develop spontaneous tumors and their early life dietary practices and growth responses was investigated. The data were obtained from outbred male Charles River CD Crl:COBS CD (SD)BR rats maintained for life on a self-selection dietary regimen that permitted them to regulate their protein intake apart from energy intake. A series of multivariable models was derived, after the rats were grouped by tumor type, that accurately accounted for the age of death of the individuals in each class. The models that explain the variance in death age of rats that develop tumors also differed from the combination of factors for rats that do not develop tumors but succumb to other age-related diseases. Although dietary protein and measures of growth are ubiquitous features in these models, no one set of idealized conditions for longevity can be proposed.

Age Factors↗
PubMed1982

Dietary practices of early life and spontaneous tumors of the rat.

A complete life history was obtained of the dietary practices, growth responses, and diseases of outbred male Charles River COBS rats permitted to select their own diets. Simple correlation analyses proved inadequate for detecting an association between any single factor at any age and tumor development. A multifactorial model showed that animals that developed tumors could be distinguished from those that did not, solely on the basis of age- or weight-specific information prior to maturity. The combination of variables that maximize the probability of a neoplasm is: 1. a high absolute protein intake shortly after weaning, 2. a high degree of efficiency in converting consumed food into body mass at the time the individual enters puberty, 3. a high level of protein intake relative to body weight during the early adult period and concomitantly, 4. a high level of food intake, and 5. a rapid growth rate during early postnatal life so that comparatively less time is required to attain a specified body weight than a subsequent weight increment. The opposite set of conditions reduces the probability of neoplasm occurrence, which is even further minimized if the proportion of protein in the diet in early postweaning life and the absolute intake of protein during the early adult period are relatively high. Differences in temporal-specific dietary practices and growth responses accounted for differences in the tissue origin of the tumors.

Age Factors↗
PubMed1980

Ultrastructural alterations in the adluminal testicular compartment in men with varicocele.

Testicular biopsies from 21 otherwise healthy men with diagnosed varicocele were processed for light and electron microscopy. Whereas germ cell morphology and tissue architecture of the basal testicular compartment appeared normal, cellular mophology and intercellular associations of the adluminal testicular compartment were variably altered. In affected tubules, spermatid nuclear and acrosomal morphology was abnormal and sloughing was evident. Spermatids were maloriented relative to Sertoli cells, and Sertoli-germ cell junctional complexes appeared to be structurally abnormal. Contradistinctly, Sertoli-Sertoli cell junctional complexes appeared unaffected. Results from this study indicate that testicular disruption in varicocele is a phenomenon of the adluminal compartment, that the Sertoli cell is, in fact, more sensitive to perturbation of the testicular environment than are germ cells, and that the Sertoli cell is the primary intratubular site of alteration leading secondarily to spermatogenic disruption.

Acrosome↗
PubMed1979

Community participation in cardiac rehabilitation.

Cardiac patients are not solely responsible for their own rehabilitation. The rehabilitative process is a prolonged one, and success lies in multidisciplinary management involving the patient, the immediate family and the community. The Health Act (Act No. 63 of 1977) has various implications for the future provision of rehabilitative services in South Africa. Each member of the health team and the community has a specific role to play, either within or outside the hospital setting, thus providing ongoing rehabilitative supervision of cardiac patients.

Aftercare↗
PubMed1979

Characterization of Sertoli cell-germ cell junctional specializations in dissociated testicular cells.

To further characterize Sertoli cell-germ cell junctional specializations seminiferous tubules from sexually mature Sprague-Dawley rats were dissociated by enzymatic and mechanical methods. Ultrastructural analysis of cell suspensions prepared by incubation in collagenase alone or by mechanical methods revealed that spermatids remained attached to Sertoli cells or Sertoli cell fragments. Such cellular associations were found only between Sertoli cell fragments and spematids in which the developing acrosome had made contact with the plasma membrane (step 8 and subsequent steps of spermiogenesis). Furthermore, the fragments were confined to that region of the plasma membrane over the acrosome. The Sertoli cell half of this adhesive site displayed the typical elements of Sertoli cell junctions, filamentous bundles and associated cisterna of endoplasmic reticulum, in apposition to the spermatids. The spermatids demonstrated no surface specializations at the attachment sites. In contrast, in cell suspensions prepared with trypsin, spermatids were free of attachments to Sertoli cells or their fragments. These results demonstrate that: (1) the junctions act to bind cells together, (2) adhesive type contact is established between Sertoli cells and spermatids at step 8 and subsequent steps of spermiogenesis, (3) contact is restricted to the spermatid plasma membrane over the acrosome, and (4) spermatids can be freed from the junctional specializations by treatment with trypsin.

Animals↗
PubMed1977

Sertoli-sertoli junctions and Sertoli-spermatid junctions after efferent ductule ligation and lanthanum treatment.

Seminiferous tubules, partially dilated by ligation of the efferent ductules, were examined after treatment with lanthanum. Lanthanum penetrated the intercellular spaces of the seminiferous epithelium, but only to the level of the Sertoli-Sertoli junctions. Further penetration from the interstitial surface of the tubule was restricted by membrane fusions (tight junctions) at the junctional complex. Lanthanum also penetrated the epithelium from the luminal surface permeating the adluminal intercellular spaces, including the site of the Sertoli-spermatid junction. The lanthanum occupying the Sertoli-spermatid junctional site appeared as a slightly narrower electron-opaque zone than that found in the non-specialized intercellular areas. The findings clearly reveal that only the Sertoli-Sertoli junctional site forms a restrictive barrier. In contrast to the specializations of plasma membrane which form the tight junction, the associated filaments and cisterna of endoplasmic reticulum may be components more directly related to maintaining and regulating cell adhesion.

Animals↗