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Biomedical subjects

G C Cook

Publications and source records attributed to G C Cook.

At least 163 records · Page 9Linked to original sources
PubMed1976

D-xylose absorption and jejunal morphology in African patients with pellagra (niacin tryptophan deficiency).

D-xylose absorption tests and jejunal morphology have been shown to be unaltered in 12 African patients with pellagra when compared with normal values for Zambian Africa adults; that result is contrary to two previous investigations in India and Egypt respectively. A significant inverse association has been shown, however, between D-xylose absorption and serum immunoglobulin IgG and IgA concentrations; that is consistent with previous studies and probably reflects malabsorption of xylose in the presence of systemic infections. It is concluded that pellagra per se does not alter intestinal structure or monosaccharide absorption.

Humans↗
PubMed1976

Impairment of jejunal absorption rate of carnosine by glycylglycine in man in vivo.

Using a double-lumen tube jejunal perfusion system in vivo, the mutual effects of carnosine (beta-alanyl-L-histidine) and glycylglycine on their respective absorption rates have been studied in six Zambian African adults. Data on the effect of the constituent amino-acids of carnosine on glycylglycine absorption rate have similarly been obtained. The solutions infused in each subject contained (A) carnosine (50 mmol l.-1), (B) carnosine (50 mmol l.-1) and glycylglycine (50 mmol l.-1), (C) glycylglycine (50 mmol l.-1), and (D) glycylglycine (50 mmol l.-1), L-histidine (50 mmol l.-1) and beta-alanine (50 mmol l.-1). Glycylglycine produced a significant impairment in the mean rate of histidine absorption from carnosine (P less than 0-01). However, carnosine did not have a significant effect on the mean rate of glycine absorption from glycylglycine. Mean rate of histidine absorption from solution D was significantly higher than that from solution A (P less than 0-01). Mean rate of glycine absorption from glycylglycine was not significantly different during infusion of solutions B, C, and D. The results are consistent with the concept that carnosine on glycylglycine is probably because the affinity of mechanism; the lack of influence of carnosine on glycylglycine is probably because the affinity of carnosine for the dipeptide uptake mechanism is relatively low. A gross difference has been shown between mean absorption rate of histidine from free L-histidine (solution D) (25-8 mmol h-1) and when it is given in the form of carnosine in the presence of another dipeptide (solution B) (8-7 mmol h-1); that emphasizes the complexity of amino acid and peptide interaction during absorption, which must be important in nutrition.

Adolescent↗
PubMed1976

Absorption of xylose, glucose, glycine, and folic (pteroylglutamic) acid in Zambian Africans with anaemia.

Rates of glucose, glycine, and folic (pteroylglutamic) acid absorption were determined for a 30 cm jejunal segment in vivo, with a double-lumen tube perfusion system, in 10 Zambian African women with a mean haemoglobin concentration of 5-1 (3-5-9-2) g/dl. In four the anaemia was megaloblastic (due to folate deficiency) and in six hypochromic. Perfusion solutions contained (1) glucose 200 mmol/1, (2) glycine 100 mmol/1, and (3) folic acid 250 mug/1. D-xylose absorption after a 25 g oral load was determined in them, and also in 18 additional patients (11 had megaloblastic and seven either hypochromic or haemolytic anaemia). Xylose absorption tests were significantly impaired in the patients with megaloblastic compared with hypochromic or haemolytic anaemia (P less than 0-001); those with untreated megaloblastic anaemia had a greater abnormality than those who had started treatment. Mean glucose, glycine, and folic acid absorption rates were similar to those in controls, and the rates in patients with megaloblastic and hypochromic anaemia were not significantly different. Correlation between glucose absorption rate and xylose excretion was, however, significantly (P less than 0-02). If more patients had been studied it seems likely therefore that a significant impairment of glucose absorption rate in the presence of megaloblastic anaemia would also have been demonstrated. In this investigation anaemia per se did not affect glucose, glycine, or folic acid absorption rates or xylose absorption, but xylose absorption was reduced in patients with megaloblastic anaemia. That abnormality was probably related to folate deficiency, and the underlying mechanism seems to be different from that causing impairment of monosaccharide absorption in patients with systemic bacterial infections. Mean glycine and folic acid absorption rates were not altered by megaloblastic anaemia, indicating that folate deficiency does not cause a general depression of absorption.

Adolescent↗
PubMed1975

High intestinal lactase concentrations in adult Arbs in Saudi Arabia.

The maximum rise in blood glucose after 50 g lactose by mouth was determined in 40 adult Arabs. Out of 30 Bedouin, urban Saudi, and Yemeni and 9 of mixed ancestry (usually partly African), 25 (83%) and 2 (22%) respectively showed an increase of over 1-1 mmol/1 (20 mg/100 ml). In common with most northern Europeans and Hamitic people of northern Africa, Arabs in Saudi Arabia usually have high intestinal lactase concentrations in adult life. This persistence of high levels probably originated in the Arabian peninsula. Its selective advantage may have been associated with the fluid and calorie content of camels' milk, which is important for survival in desert nomads.

Adolescent↗
PubMed1975

Relation between malaria serum gamma-globulin concentration and the D-xylose absorption test.

D-xylose excretion after a 25 g. oral load was determined in 15 African subjects suffering from malaria. Nine of them were re-investigated after the malaria had been or was being treated. Malarial parasitaemia and pyrexia did not significantly influence results of the D-xylose test. However, in the untreated subjects, there was a significant inverse correlation between the weight of D-xylose excreted and the serum gamma-globulin concentrations. The observation may have a nutritional importance.

Adolescent↗
PubMed1975

Serum immunoglobulin and protein concentrations in Zambian African patients in Lusaka.

Serum immunoglobulins IgG, IgA, IgM and IgD and gamma-globulin, total globulin and albumin concentrations have been determined in 136 adult Zambian African hospital in-patients, with several diagnoses, in Lusaka, Zambia. The study gives base-line data for that population. A significant positive correlation between serum IgG and gamma-globulin concentrations (P less than 0.001) suggests that for routine use the less costly method for serum gamma-globulin determination gives equally useful information as that for IgG.

Adult↗
PubMed1974

Inverse relation between serum IgG concentration and glucose and xylose absorption in Zambian African adults.

In three separate investigations in Zambian African adults in Lusaka an inverse association has been shown between serum IgG concentration and either glucose absorption rate from the jejunum (from a 200-mM solution) or xylose absorption (from a 25-g oral load). In developing areas of the world, where serum IgG concentrations are often high, this finding may have widespread nutritional implications.

Adult↗
PubMed1974

Effect of glycylglycine and glycine on jejunal absorption rate of L-histidine in man in vivo.

1. Using a double-lumen tube jejunal perfusion system in vivo, the effects of glycylglycine and glycine on the jejunal transfer rate of L-histidine have been studied in a 30 cm jejunal segment, in six Zambian African men. Data on the effect of L-histidine on glycylglycine transfer rate have also been obtained. The solutions perfused in each subject contained (A) L-histidine (100 m-mole l.(-1)), (B) L-histidine (100 m-mole l.(-1)) and glycylglycine (50 m-mole l.(-1)), (C) glycylglycine (50 m-mole l.(-1)), and (D) L-histidine (100 m-mole l.(-1)) and glycine (100 m-mole l.(-1)).2. Whereas the presence of glycine in the perfusing fluid significantly impaired the absorption rate of L-histidine (P < 0.01), glycylglycine had no significant effect. The presence of L-histidine in the perfusing fluid had no significant effect on the rate of glycylglycine absorption. When compared with results for glycine absorption rate in twelve Zambian African subjects in another study, the presence of L-histidine produced a significant impairment in the rate of glycine absorption (P < 0.001).3. The results demonstrate a mutual inhibition between the rates of L-histidine and glycine absorption. The lack of a similar inhibition between L-histidine and glycylglycine is consistent with the concept of independent transfer mechanisms for amino acids and dipeptides in the human jejunum.

Adult↗
PubMed1974

Reaction of human small intestine to an intraluminal tube and its importance in jejunal perfusion studies.

A double-lumen tube with a mercury weight attached to its distal end was positioned in the small intestine of six subjects who were to undergo an elective laparotomy. The tube and the technique for its localization were exactly similar to those used in previous intestinal perfusion experiments. Marked ;concertinaing', or gathering of the small intestine proximal to the mercury weight, was seen at laparotomy in all six subjects. The ratio between the mean intestinal length from the mercury weight to the ligament of Treitz after removal of the tube to that with the tube in situ was 3.0 (2.5-3.8). Mean total jejuno-ileal length was 421 (320-521) cm. In five of the six subjects the distal end of the tube was more than half way between the ligament of Treitz and the ileo-caecal valve although it was only 100-120 (mean 108) cm from the incisor teeth. Segmental perfusion studies of the human jejunum involve a much longer length of small intestine than is generally assumed-by a factor of approximately 3. Such studies assess absorption rates over a substantial proportion of the small intestine and are not confined to a short segment of proximal jejunum. The nutritional significance of such studies in which amino acids, peptides, and carbohydrates are investigated is increased. Studies designed to measure absorption rates from the ileum should be treated with caution as part or all of the perfusion segment may be past the ileo-caecal valve.

Adult↗