Search PubMed⌕ Search

Biomedical subjects

R G Bell

Publications and source records attributed to R G Bell.

At least 127 records · Page 7Linked to original sources
PubMed1976

Feedlot manure top dressing for irrigated pasture: good agricultural practice or a health hazard?

Top dressing a spray-irrigated pasture of orchard-grass with 125 t/ha of overwintered beef feedlot manure almost doubled the yield of dry forage: 6353 kg/ha vs. 3578 kg/ha for the plots receiving no manure. Even at this rate of application, the manure did not contaminate the irrigated grass with enteropathogenic bacteria after irrigation. When the grass became contaminated through the use of fecally polluted irrigation water, the fecal coliforms, indicator organisms with survival characteristics similar to the salmonellae, were effectively eliminated from the grass after exposure to 65 hr of bright sunlight.

Agriculture↗
PubMed1976

Serum and small intestinal immunoglobulin levels in undernourished children.

Intestinal immunoglobulin levels were quantitated in undernourished Indonesian children with enteric infections and normally nourished Indonesians with and without enteric infections. These were compared to the same parameters in Australian Aboriginal children (also suffering undernutrition) and normal Caucasian children. Children with enteric infections displayed equally elevated levels of intestinal immunoglobulin irrespective of their nutritional status. Intestinal infections appeared to elevate IgG levels more than secretory IgA levels in the age group examined. However, it appeared likely that some of the EgG was serum-derived whereas the IgA appeared to be locally produced. There was no apparent deficiency in the capacity of undernourished children to manufacture and secrete immunoglobulin in the gut.

Asian People↗
PubMed1976

The influence of dietary protein deficiency on haemopoietic cells in the mouse.

These experiments examined the effect of a diet limited only in protein (4% by weight) on haemopoietic stem cells in mice. This diet places severe restrictions on growth and cell proliferation and this was reflected in lower numbers of colony forming units (CFUs) and in vitro colony forming cells (CFCs). Differences were apparent in the response of different organs to this stress; for instance, the incidence of spleen CFUs fell sharply from around 40/mg spleen tissue to 1-4/mg spleen tissue after 3 weeks on a low protein diet. This selective loss did not occur in bone marrow where total CFUs remained proportional to cellular content. Yet a third pattern was shown by thymus CFUs--although the numbers were low these increased from 16/thymus in normal mice to 132/thymus in deprived mice. This was the only organ examined which showed an increase. The effects of a return to a high protein (18%) diet showed that the spleen was the most responsive organ. By day 5 after the return to 18% protein the spleen contained as many CFUs per million cells as the bone marrow. During this time the content of CFU in the spleen had increased some 50-fold whereas bone marrow CFUs only doubled. The spleen assumes the major reconstructive role during the refeeding process.

Animals↗
PubMed1976

The development in beef cattle manure of Petriedllidium boydii (Shear) Malloch, a potential pathogen for man and cattle.

Petriellidium boydii (Allescheria boydii) dominated the mycoflora of manure samples form three beef cattle feedlots after incubation at room temperature for 4 months. The possible dangers associated with this pathogenic fungus, which causes mycotic abortion in livestock, pulmonary allescheriasis in man, and mycetomas in both man and animals, are discussed. This fungus could create a health hazard in feedlots where in situ manure decompostion is encouraged.

Abortion, Veterinary↗
PubMed1976

Influence of dietary protein restriction on immune competence. II. Effect on lymphoid tissue.

Weanling mice fed a 4 percent diet showed a generalized loss of lymphoid tissue which was greater than the loss of total body weight. This effect was greatest in the thymus greater than spleen greater than mesenteric lymph node. Cell loss was most pronounced during the 1st week on diets, then remained at stable levels for 3 weeks and showed a gradual rise thereafter. The effect was shown to be mediated partly by a cessation of growth in lymphoid organs due to the low protein intake and, secondly, an adrenal corticosteroid induced lympholysis which actually reduced cell numbers. Recirculating T cells and resident B cells were amongst the least affected cells whereas stem cells, non-migratory T cells and other reticuloendothelial cells were most depressed in numbers. At no stage was the germinal centre forming capacity of the mesenteric node lost although cell recruitment to antigenically stimulated nodes was diminished. During nutritional repletion the spleen, thymus and mesenteric node all showed different and characteristic regrowth. The spleen was most active initially and rapidly reconstituted haemopoietic cells and B cells. This was followed by the thymus which showed a delayed reinitiation of its normal growth kinetics which had been interrupted by the diet. The evidence suggested that full rehabilitation of the immune apparatus took place even after 2 months of nutritional deprivation.

Adrenal Cortex Hormones↗
PubMed1976

The effects of nutritional rehabilitation on antibody production in protein-deficient mice.

The transfer of chronically protein-deficient mice to an optimal diet a few days before immunization with sheep erythrocytes, tetanus toxoid or Brucella abortus vaccine either failed to increase antibody production above the level produced by deficient mice, or suppressed the responses to below those produced by deficient mice or normally-fed controls. Transfer to high protein diet on the day of immunization or feeding deficient mice the normal diet for just 2 days at the time of injection produced higher titres than did transfer a few days before immunization. Secondary responses to TT were affected by transfer to the normal diet at priming, rather than at rechallenge. Some mechanisms which may explain these findings and their implications for immunization schedules in malnourished humans are discussed.

Agglutination Tests↗
PubMed1975

Influence of dietary protein restriction on immune competence. I. Effect on the capacity of cells from various lymphoid organs to induce graft-vs.-host reactions.

The effect of dietary protein restriction in mice on the capacity of their lymphoid cells to induce graft-vs.-host responses (GVHR) was studied. Mice were fed diets containing 4% or 20% protein ad libitum. The GVHR capacity of cells from all lymphoid organs of deprived mice was increased on a cell-for-cell basis over that of their normally fed counterparts. The slope of the dose-response curves did not change for spleen and mesenteric lymph node cells although their reactivity was increased by fourfold, and 50% respectively. The slope of the curves for thymus and Peyer's patches was changed indicating fundamental changes in the reactive cellular populations of these organs. Changes in GVH reactivity of cell populations from deprived mice were not mediated by increased corticosteroid production as adrenalectomy did not reduce their GVH responses. An explanation for the results was sought in a general decrease in production of short-lived cells with a rapid turnover such as most B cells. Long-lived T cells appear to persist and retain their reactivity for quite long periods in the face of nutritional insults.

Adrenalectomy↗
PubMed1975

Immunoglobulin classes carrying homocytotropic and passive hemagglutinating antibody activities in the marsupial Setonix brachyurus (the quokka).

On the basis of their physicochemical and antigenic properties, and by analogy with guinea pig immunoglobulins, two antibody classes in the serum of the marsupial Setonix brachyurus have been classified as IgG1 and IgG2 isotypes. The analogy between these marsupial immunoglobulins and those of eutherian (placental) species was extended by an investigation of their biological activities. The electrophoretically slow antibody (IgG2) fixed hemolytic complement, precipitated soluble antigen and predominated early in the response mounted when quokkas were immunized with antigen emulsified in Freund's complete adjuvant (FCA). The more anodic antibody (IgG1) in this marsupial did not fix complement, was inefficient in precipitating antigen and was the predominant antibody synthesized by quokkas immunized with antigen adsorbed to alumina gel. The IgG1 isotype in this marsupial appears to possess both passive hemagglutinating (HA) and homocytotropic antibody (HCA) activities. However, the HCA and IgG1 HA activities did not develop in parallel during the course of the immune response, thus suggesting that only a functional subpopulation of the IgG1 antibodies possess homocytotropic activity.

Absorption↗