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Biomedical subjects

J B Mason

Publications and source records attributed to J B Mason.

At least 73 records · Page 4Linked to original sources
PubMed1990

Folate binding in intestinal brush border membranes: evidence for the presence of two binding activities.

Binding of [(3)H]folic acid by isolated rat jejunal brush border membranes (BBMs) was analyzed by chromatography on small Biogel P-30 columns. Folic acid binding to BBMs exhibited a prominent pH effect with a sharp maximum at pH 5.5 to 6.0. After acid treatment to strip the BBMs of bound folate, the membranes demonstrated a wider pH optimum (5.5 to 7.5) of folate binding and a higher binding capacity. Scatchard analysis of binding experiments performed at pH 6.0 revealed the existence of two components: one with a high affinity (kd = 12 to 25 nM) and low capacity (V(max) for non-acidified BBMs = 0.259 to 0.264 pmol/mg protein, V(max) for acidified BBMs = 0.41 to 0.71 pmol/mg protein) and the other with a low affinity (kd = 1.1 to 5.1 microM and high capacity (V(max) for non-acidified BBMs = 0.93 to 1.93 pmol/mg protein, V(max) for acidified BBMs = 4.05 to 7.69 pmol/mg protein). Phosphatidylinositol-specific phospholipase C preferentially detached the high affinity component from jejunal BBMs. Phosphatidylinositol-specific phospholipase C-released folate binding protein was precipitated by antibodies to the high-affinity folate-binding protein from rat kidney. These data suggest the existence of two different folate-binding proteins in isolated rat jejunal BBMs. The high-affinity folate-binding protein shares epitopes with the folate-binding protein in the kidney.

Journal Article↗
PubMed1990

Comparison of mothers' understanding of two child growth charts in Lesotho.

Reported are the results of a study that compared mothers' understanding of two growth monitoring charts in Lesotho, which was carried out to assist the government in selecting a national growth chart. The study was conducted over 4 months in nine primary health care (PHC) clinics, where 1221 mothers were enrolled. Mothers were assigned to one of the following chart groups: "road-to-health" (RTH), "growth surveillance" (GS), or no chart (controls). Mothers in the first two groups received instruction on their respective chart during monthly growth monitoring sessions and were tested on their knowledge of this chart before and after the follow-up period. The mothers in the control group were tested on the RTH and GS charts at the beginning and at the end of the study. The results indicated that mothers who received training on either chart markedly improved their understanding compared with the control group and that the RTH group understood their chart better than the GS group did theirs.

Audiovisual Aids↗
PubMed1988

Folate-binding protein and the absorption of folic acid in the small intestine of the suckling rat.

The folate in milk is largely bound to high-affinity folate-binding protein (FBP). With an in vivo intestinal loop technique, we examined the absorption of folic acid bound to FBP (FA-FBP) in the small intestine of the suckling rat. In contrast to unbound folic acid (FA), FA-FBP is absorbed more avidly in the ileum than in the jejunum (p less than 0.025) and its absorption is not inhibited by 1 mmol sulfasalazine/L. Folate-binding activities in the mucosa of the proximal (duodenum and jejunum combined) and distal (ileum) small intestine were also examined and found to be 0.32 and 1.31 pmol/mg protein, respectively (p less than 0.001). A 6-h fast produced a 42% decrease in folate-binding activity in the distal small intestine (p less than 0.01) but did not change activity in the proximal portion. Collectively, these observations suggest that FA-FBP is absorbed by a mechanism that is distinct from that responsible for the absorption of FA and that absorption does not require prior dissociation of the vitamin-binding protein complex.

Animals↗
PubMed1986

Stressful life situations and perception of stress in black and Indian duodenal ulcer patients.

The stressful life situations of 87 patients with endoscopically confirmed recent duodenal ulceration (DU) were compared with those of 75 essentially orthopaedic non-DU controls. Results indicated a statistically significant difference in the reporting of low income and dissatisfaction, including tensions related to considerable responsibility in the work situation but no authority, by both Indian and black DU patients. Indian DU patients reported significantly more family conflict and problems than controls, while black DU patients reported living in single hostels or in split families to a significantly greater degree than controls. Overall, DU patients experienced significantly greater stress in more areas of their lives than controls.

Adult↗
PubMed1986

Substrate dependence and oxygen sensitivity of tone and of spontaneous and evoked contractions of the distal colonic muscularis mucosae of opossum.

The muscularis mucosae of the opossum distal colon fails to maintain tone and to generate spontaneous contractions in an anaerobic environment in vitro. To investigate this phenomenon further, dose-response curves to agonists under different oxygen concentrations were examined. In other experiments the tissue was actively exhausted (i.e., repeatedly stimulated in a substrate-free environment until no response to K+, acetylcholine, or histamine could be observed) and then equilibrated with an alternative substrate for 3 h, when the ability of the tissue to contract to agonists was reevaluated. Reducing the available oxygen abolished tone and caused a graded loss of responses to histamine; in contrast, at 0% oxygen maximum responses to acetylcholine were reduced by only 75%. Abolition of tone by the addition of cyanide to the bathing medium did not affect the amplitude of responses to histamine and acetylcholine. The tissue was able to use all the chosen alternative substrates to different degrees for acetylcholine-induced contraction; similarly, with the exception of beta-hydroxybutyrate it could use all substrates to some degree to support responses to histamine. The evidence suggests that the source of energy required to maintain tone is different from the source required to sustain K+ or agonist-induced contractions, and that the dependence of isotonic contractions on exogenous substrates varies with the pharmacologic stimulus.

Acetylcholine↗
PubMed1983

Nutritional surveillance.

The concept of nutritional surveillance is derived from disease surveillance, and means "to watch over nutrition, in order to make decisions that lead to improvements in nutrition in populations". Three distinct objectives have been defined for surveillance systems, primarily in relation to problems of malnutrition in developing countries: to aid long-term planning in health and development; to provide input for programme management and evaluation; and to give timely warning of the need for intervention to prevent critical deteriorations in food consumption. Decisions affecting nutrition are made at various administrative levels, and the uses of different types of nutritional surveillance information can be related to national policies, development programmes, public health and nutrition programmes, and timely warning and intervention programmes. The information should answer specific questions, for example concerning the nutritional status and trends of particular population groups.Defining the uses and users of the information is the first essential step in designing a system; this is illustrated with reference to agricultural and rural development planning, the health sector, and nutrition and social welfare programmes. The most usual data outputs are nutritional outcome indicators (e.g., prevalence of malnutrition among preschool children), disaggregated by descriptive or classifying variables, of which the commonest is simply administrative area. Often, additional "status" indicators, such as quality of housing or water supply, are presented at the same time. On the other hand, timely warning requires earlier indicators of the possibility of nutritional deterioration, and agricultural indicators are often the most appropriate.DATA COME FROM TWO MAIN TYPES OF SOURCE: administrative (e.g., clinics and schools) and household sample surveys. Each source has its own advantages and disadvantages: for example, administrative data often already exist, and can be disaggregated to village level, but are of unknown representativeness and often cannot be linked with other variables of interest; sample surveys provide integrated data of more or less known representativeness, but sample sizes usually do not allow disaggregation to, for example, specific villages. A combination of these sources, with a capability for ad hoc surveys (formal or informal) is often the best solution. Finally, much depends on adequate facilities for data analysis, even though simple, comprehensible data outputs are what is required. Intersectoral cooperation is needed to provide realistic options for the decision-making process.

Agriculture↗
PubMed1981

The effect of stressful life situations on the healing of duodenal ulceration.

Ninety-five duodenal ulcer patients were assessed by a gastro-enterologist as being either difficult or easy healers. Difficult healers were defined as those taking longer than 6 weeks to heal or those who relapsed within 6 months of healing, as assessed by endoscopy. Easy healers were defined as being healed within 6 weeks of treatment and remaining healed. The detailed psychosocial questionnaires compiled for patients were analysed in terms of stressful life situations experienced at the time of treatment. Significantly more stressful life situations occurred in patients with a difficult healing period than in those who experienced easy healing. Of the stressful life situations which were considered the area of family stress appeared most crucial in retarding easy recovery.

Duodenal Ulcer↗