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Biomedical subjects

R Stock

Publications and source records attributed to R Stock.

At least 37 records · Page 2Linked to original sources
PubMed1985

Health care for some: a Nigerian study of who gets what, where and why?

The persistent underdevelopment of health in the Third World belies the optimism of the "Health care for all by the year 2000" campaign. In order to understand the underdevelopment of health, it is essential to examine the historical evolution of specific health systems. These ideas are developed in a case study of health care in Kano State, Nigeria. The nature and contemporary development of the health care system, which includes state voluntary agency and private sector outlets for Western scientific medicine and a large and varied traditional medicine sector, are examined. Although the deepening health care crisis may potentially spur a reconsideration of priorities and strategies, past experience suggests that a stubborn retention of a pared-down and increasingly unjust version of the present system is more likely.

Health Resources↗
PubMed1983

Distance and the utilization of health facilities in rural Nigeria.

The distance patients must travel in order to obtain treatment has long been recognized as a primary determinant of the utilization of health care facilities. The distance factor is especially significant in rural Third World settings where the density of Western-type health facilities is often low, where the majority of patients are likely to make the journey for treatment as pedestrians and where there are viable and usually more accessible alternate sources of medicine. This study examines the impact of distance on the utilization of health care facilities in the Hadejia area of Kano State, Nigeria. Per capita utilization was found to decline exponentially with distance. The rate of distance decay in utilization levels varies according to the type of facility, socio-demographic variables and illness. Hausa perceptions about sickness and about specific illnesses are reflected in the varying incidence of health facility utilization in the treatment of particular illnesses and distance decay gradients of varying steepness. Although the per capita consumption of health care decreases exponentially for concentric distance bands, individual villages show great disparities in utilization rates which are only partly attributable to distance.

Adult↗
PubMed1983

Impact of weighing procedures and variation in protein degradation rate on measured performance of growing lambs and cattle.

A lamb growth trial was conducted to evaluate soybean meal and blood meal and to compare two experimental designs (a completely randomized design and a switchback design). A larger amount of variation was observed with the switchback than with the randomized design. A larger number of animals, longer treatment period or increased number of weighings may be needed to overcome end point weighing errors and decrease the variation in the switchback design. In both designs, there was a significantly greater conversion of protein to gain for blood meal (BM)-supplemented lambs than for soybean meal (SBM)-supplemented lambs. The relative value of BM compared with SBM was 251% (completely randomized design) or 296% (switchback design). Weighing steers 2 or 3 d at the beginning and end of the trial reduced variation and increased the probability of detecting differences in daily gain, gain/feed and protein efficiency when compared with a standard weighing method (once at the beginning and once at the end of the trial). Regressing 11 weekly weights on an average of one, two or three initial and final weights also reduced variation and increased the probability of detecting treatment differences. Regressions of weekly weights were more useful as the number of initial and final weights was decreased. Daily gain and gain/feed increased linearly (P less than .05) with protein level when BM or SBM was fed. A nonlinear model was used to predict protein requirement, maximum gain and relative protein values. There was a range in relative values for BM of 255 to 348% depending on the method of analysis used.

Analysis of Variance↗
PubMed1982

Relationship between brain mitochondrial hexokinase and neuronal function: comparable effects of 2-deoxy-D-glucose and thiopental.

Mitochondrially bound brain hexokinase is solubilized by anesthetics and this effect has been suggested to contribute to anesthesia. In the present investigation the influence of the metabolic inhibitor 2-deoxy-D-glucose (2-DOG) was studied. An isolated rat brain preparation was used to avoid the contribution of peripheral reactions. Isolated rat brains were perfused for 45 min with media containing 4 mmol/l glucose, 10 mmol/l 2-DOG and/or 0.4 mmol/l thiopental. The EEG was monitored and acetylcholine, 2-DOG and its 6-phosphate, as well as the intracellular distribution of hexokinase activity were determined in brain tissue. Soluble hexokinase activity in brain cortex was enhanced by 2-DOG, as also by thiopental, and even more pronounced by both drugs used together, Results from in vitro experiments suggest that solubilization of mitochondrial hexokinase after 2-DOG is mediated by intracellularly accumulated 2-DOG-6-phosphate. 2-DOG produced a significant impairment of neuronal activity, revealing EEG patterns similar to those caused by thiopental anesthesia. Cortical acetylcholine levels were elevated by 2-DOG, as well as by thiopental, and again both drugs showed an additive effect when used in combination. This effect which may be the result of an inhibition of acetylcholine release, was also detectable in mice in vivo after 5 g 2-DOG/kg i.p., whereas the same dose of 3-O-methylglucose had no effect. The results provide further evidence that mitochondrial hexokinase may be involved in the relationship between cerebral metabolism and brain function.

Animals↗
PubMed1980

Studies on the linkage of energy metabolism and neuronal activity in the isolated perfused rat brain.

An isolated rat brain preparation was perfused using glucose-free (= aglycemic) media. The high-energy phosphates, substrates of the glycolytic pathway, free amino acids, acetylcholine as well as the intracellular distribution of hexokinase activity were determined in brain tissues. The EEG was evaluated visually. The levels of glycolytic substrates, glutamate, and glutamine in cortical tissue decreased after aglycemic perfusion whereas the asparte level increased and the GABA level remained unchanged. The high-energy phosphate content seemed to be unaffected for about 15 min of aglycemic perfusion and fell significantly after 20 min. The EEG of the isolated brain changed rapidly after starting aglycemic perfusion and became isoelectric after 12--15 min. Hyperglycemic perfusion (35 mmol glucose per liter perfusion medium) did not alter the energy metabolism of the isolated brain. The breakdown of cerebral energy metabolism and of EEG activity was postponed when thiopental was added to the perfusion medium. The soluble hexokinase activity measured in cortical tissue was reduced after aglycemic perfusion and was enhanced after thiopental. Hyperglycemic perfusion did not influence the intracellular hexokinase distribution. The acetylcholine level in the striatum of the isolated rat brain was significantly decreased by aglycemia and was increased in hypothalamus by thiopental. It was suggested that hexokinase bound to the mitochondrial membrane may play an important role in the relationship of energy metabolism and neuronal activity.

Acetylcholine↗
PubMed1975

The effects of increased glucose supply and thiopental anesthesia on energy metabolism of the isolated perfused rat brain.

The effects of glucose concentrations in the perfusion medium ranging from 5 to 15 mM and thiopental, on cerebral energy metabolism were studied using the isolated perfused rat brain. After a perfusion time of 30 min brain levels of the following substrates and metabolites were determined: P-creatine, ATP, ADP, AMP, glycogen, glucose, glucose-6P, fructose-6-P, pyruvate, lactate, alpha-ketoglutarate, glutamate, ammonia. In control experiments increasing the glucose concentration in the perfusion medium produced an increase of intracellular brain glucose concentration only, revealing a linear relationship between glucose content in brain and blood. Neither high-energy phosphates nor glycolytic intermediates were markedly affected by the changes in blood glucose. With an anesthetic dose of thiopental (0.15 mM) in the perfusion medium identical metabolic alterations occured in all experiments: P-creatine and glucose were significantly increased whereas ADP, AMP, lactate and pyruvate were diminished. Also with thiopental brain glucose was linearly related with the glucose concentration in the perfusion medium. The calculated regression line was apparently parallel with that from control experiments; that means thipental always caused an elevation of brain glucose by the same amount of 0.9 mumoles/g--irrespective of the initial cerebral glucose content. The results yield further evidence that glucose transport is not the rate-limiting step in glycolysis. The action of thiopetal on glycolytic pathway is discussed.

Adenine Nucleotides↗
PubMed1975

Decreased glycolytic flux rate in the isolated perfused rat brain after pretreatment with 6-aminonicotinamide.

Cerebral energy metabolism was studied in the isolated perfused rat brain after 6-aminonicotinamide (6-AN; 35 mg/kg i.p.) administered to the intact animals 7 hrs before perfusion was started. The metabolic alterations in the isolated rat brains were such as reported for rat and mouse brain in vivo: Inhibition of 6-phosphogluconate dehydrogenase was followed by an accumulation of 6-phosphogluconate, leading to a decreased activity of glucosephosphate isomerse. This was reflected by increased levels of glucose and glucose 6-phosphate and decreased levels of fructose 6-phosphate, pyruvate and lactate. Since the concentration of lactate in the perfusate of the isolated brain was also lowered, 6-AN must have reduced the glycolytic flux rate.

6-Aminonicotinamide↗