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Biomedical subjects

A J Wright

Publications and source records attributed to A J Wright.

At least 91 records · Page 5Linked to original sources
PubMed1990

The effects of sugar-beet fibre and wheat bran on iron and zinc absorption in rats.

The addition of 1 g sugar-beet fibre (Beta Fibre) to 3 g semi-synthetic diet resulted in a 54% increase in iron and a 39% increase in zinc absorption in rats. The same amount of non-starch polysaccharides fed as wheat bran (1.9 g) had no effect on Fe absorption but reduced Zn absorption by 9%. The inhibitory effect of wheat brain is probably due to its high phytate content, but there is, as yet, no explanation for the enhancement of Fe and Zn absorption caused by Beta Fibre. If the effect also occurs in man, it will have important implications for high-fibre diets and mineral nutrition.

Animals↗
PubMed1990

The effectiveness of various iron-supplementation regimens in improving the Fe status of anaemic rats.

Less frequent iron supplementation may be equally as beneficial to Fe-deficient subjects as routine daily supplementation because of the short-term suppressive effect of oral dosing with large amounts of Fe on subsequent Fe absorption. In the present study, the possibility that the administration of an Fe supplement every 2nd or 3rd day may be as effective in improving Fe status as a daily supplement was investigated in anaemic rats. Anaemic rats were given a 4 mg Fe supplement every day, on alternate days or every 3rd day, as a single dose with a midday meal or as a multiple dose with a morning, midday and evening meal. A low-Fe diet (13 mg/kg) was given at all other times. After 7 d, erythrocyte count, packed cell volume, mean cell volume, haemoglobin concentration and total liver Fe were measured and compared with those of meal-fed rats which had not been given any supplemental Fe. Rats which received a supplement every 3rd day, a total supplement of 12 mg, had a similar Fe status to those receiving a daily supplement, a total supplement of 28 mg. Administration of the supplement as a multiple, rather than as a single dose did not improve recovery from the Fe deficiency. It is suggested that less frequent supplementation with a smaller total amount of Fe, should be considered in human subjects. Such a regimen would minimize unpleasant side-effects of oral Fe therapy, decrease the risk of adverse effects of Fe on the absorption of other essential minerals and substantially cut the cost of supplementation programmes.

Anemia, Hypochromic↗
PubMed1989

Crouzon's disease. Part I. One-stage correction by combined face and forehead advancement.

Crouzon's disease results in maxillary hypoplasia and a receding forehead, which produce characteristic exorbitism. Total correction of the deformity by Le Fort III osteotomy and face advancement with a simultaneous forehead advancement corrects all the deformities. The advantages and disadvantages of this major craniofacial procedure are discussed after 2 case descriptions.

Child↗
PubMed1989

The effect of combined dietary iron, calcium and folic acid supplementation on apparent 65Zn absorption and zinc status in pregnant rats.

In the present study the effect of combined iron, calcium and folic acid supplementation of the diet on 65Zn retention and zinc status was studied in the pregnant rat. Female Wistar rats were fed on a low- (8 micrograms/g) or high- (60 micrograms/g) Zn diet for 14 d and then mated overnight. After mating, half the rats were fed on the low- or high-Zn diet as before, whilst the other half were fed on similar diets supplemented with Fe, Ca and folic acid. The level of supplementation was chosen to reflect proportionately the possible increase in daily intakes of these nutrients by pregnant women. Rats which did not mate successfully were used as non-pregnant controls. On day 18 of pregnancy, each animal was given a meal of the appropriate diet labelled extrinsically with 65Zn, and on day 20 rats were killed. Carcass 65Zn retention was lower in pregnant and non-pregnant rats fed on the supplemented diets compared with those fed on the unsupplemented diets. Rats which consumed the supplemented diets throughout pregnancy had reduced plasma Zn concentrations but femur and fetal Zn concentrations were unaffected. Maternal femur Ca and fetal Fe concentrations were lower in the high-Zn groups compared with rats fed on low-Zn diets. It was concluded that the risk of inducing fetal Zn depletion as a consequence of Fe, Ca and folic acid supplementation during pregnancy appeared to be slight.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1989

The effect of differences in dietary iron intake on 59Fe absorption and duodenal morphology in pregnant rats.

The effect of iron intake on 59Fe absorption throughout pregnancy, and on maternal and fetal Fe status towards the end of pregnancy, was investigated in rats. The influence of pregnancy and dietary Fe on duodenal morphology was also studied. Female rats were fed on a diet containing 17 or 100 mg Fe/kg for 2 weeks before and throughout pregnancy. 59Fe absorption was measured on days 1 or 2, 8 or 9 and 17 or 18 of pregnancy, and maternal and fetal Fe status was determined on days 18 or 19. Pregnancy resulted in a fall in haemoglobin (Hb) concentration. Compared with non-pregnant counterparts, total liver Fe was reduced in the low-Fe group, but not in the high-Fe group, indicating that the fall in Hb in the high-Fe rats was not associated with an Fe-deficient state. 59Fe absorption in rats fed on both diets increased throughout pregnancy, demonstrating that Fe supplementation of the diet, to a level that prevented the development of Fe-deficiency, failed to suppress an increase in absorption. Fetal weight appeared to be an important determinant of the efficiency of Fe absorption in late pregnancy. Poor maternal Fe status was accompanied by a reduction in fetal Fe concentration but results also suggested that fetuses were partly protected from maternal Fe-deficiency. Pregnancy resulted in increased duodenal circumference and villus dimensions, whilst high dietary Fe reduced duodenal growth in both pregnant and non-pregnant animals. The relevance of this finding is discussed. It was concluded that, in rats, pregnancy per se causes an enhancement in Fe absorption and that the degree of enhancement is in part related to fetal mass.

Animals↗
PubMed1989

Measurement of non-haem iron absorption in non-anaemic rats using 59Fe: can the Fe content of duodenal mucosal cells cause lumen or mucosal radioisotope dilution, or both, thus resulting in the underestimation of Fe absorption?

Male Wistar rats (188 g) were fed on a semi-synthetic (SS) diet (38 mg iron/kg) ad lib. for 7 d and then meal-fed for 1 d. After a 21 h fast each rat was given one meal (10 g) of high-Fe SS (500 mg Fe/kg; high-Fe group) or control (38 mg Fe/kg; control group) diet. After 16 h 2 ml of an 59Fe-labelled ferrous sulphate solution (18 kBq 59Fe; 120 micrograms Fe) was administrated by gavage and equal numbers of rats from each group were killed 6 or 24 h after dosing. Mucosal uptake of 59Fe from the gut lumen and transfer of 59Fe from mucosa into the carcass were measured. Total Fe content of the duodenum was also determined. Mucosal 59Fe uptake and transfer were markedly lower in the high-Fe group compared with the control group. The Fe content of the duodenum, the major region of Fe absorption, was significantly greater in the high-Fe group than in the controls. A larger amount of Fe may thus have been released into the lumen of the high-Fe rats, via mucosal cell turnover, resulting in a greater lumen dilution of the 59Fe dose in this group compared with the controls. Calculations are presented which demonstrate that such an effect could not possibly account for the observed difference in mucosal 59Fe uptake between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Beneficial effect of chronic bradycardial pacing on capillary growth and heart performance in volume overload heart hypertrophy.

We have previously reported that chronic bradycardial pacing increases both capillary density/mm2 (CD) and maximal work output in normal rabbit hearts. This technique has now been applied to rabbits with volume-overload hypertrophy due to lesion of the aortic valve. Four groups of animals were studied: controls (C), paced (P), valve-lesioned (VL), and paced valve-lesioned (PVL). The aortic valve was lesioned 8 weeks before the acute experiments; pacing was started 4 weeks before the acute experiments, and thus, the PVL group had developed hypertrophy before pacing was started. The degree of hypertrophy was similar in VL hearts whether paced or not: heart wt/body wt ratio increased by 33.5 +/- 8.9% (mean +/- SEM) in VL and 25.2 +/- 8.2% in PVL versus control animals of similar body weight (p less than 0.001). The hearts of the PVL animals showed a higher CD (2,277 +/- 107) than VL hearts (1,383 +/- 43), CD in C hearts of similar weights being 1,595 +/- 103, and in P hearts 2,350 +/- 194. Thus, CD was lower by 14% in VL and higher by 43% in PVL than in C hearts. Valve-lesioning had a significant effect in reducing maximal cardiac minute work (p less than 0.001), whereas pacing significantly improved maximal cardiac minute work (p less than 0.001) to 2.467 +/- 0.206 J/g x 10(-4) in the P group versus 1.609 +/- 0.105 in the C group.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1989

Theodore Dreiser's "Laughing Gas".

Around World War I, American novelist Theodore Dreiser wrote several plays, one of which, "Laughing Gas," explores the odd experience of a physician undergoing surgery with nitrous oxide/oxygen anesthesia. The content of this play and its relationship to Dreiser's career are examined.

Drama↗
PubMed1989

Can growth of capillaries in the heart and skeletal muscle be explained by the presence of an angiogenic factor?

Capillary growth was induced in rabbit hearts by long-term bradycardial pacing, and in skeletal muscles by long-term electrical stimulation. In order to find out what factors may be responsible for it, samples of all tissues were analysed for angiogenic activity (AA). To estimate the possible role of mechanical factors, blood flow was measured at rest and during maximal dilatation. Rabbit hearts were paced at half the normal frequency for 24 h/day for 1-2 months by electrodes implanted in the right atrium. Gastrocnemius-plantaris muscles were stimulated at 10 Hz via implanted electrodes, 8 h/day for 14 days. Unpaced hearts and non-stimulated muscles served as controls. Capillary density (estimated in frozen cross-sections stained for alkaline phosphatase) was higher in paced than in control hearts (2235 +/- 86, s.e.m. cap/mm2, 1815 +/- 83, P less than 0.005); capillary/fibre ratio was 2.84 +/- 0.21 in stimulated and 1.243 +/- 0.06 in control gastrocnemius (P less than 0.001). The presence of AA was assayed on chicken chorioallantoic membrane (CAM). All paced and 50% of control hearts showed positive CAM results. Control gastrocnemii gave positive results in 25%, plantaris in 30%: stimulated muscles showed 30% and 37.5% positive responses. Coronary blood flow at rest was significantly lower in chronically paced than control hearts (2.172 g/ml/min, 3.025 +/- 0.187, P less than 0.05) and not significantly different during maximal dilatation (9.217 +/- 1.722 and 11.166 +/- 1.158 respectively). Blood flow per heart beat was significantly higher during acute bradycardia as well as in bradycardially paced hearts at rest. Blood flow in stimulated muscles was significantly higher than in controls both at rest (26.2 +/- 3.36 ml/100 g/min as compared to 8.5 +/- 2.15, P less than 0.001) and during muscle contractions (56.1 +/- 4.5 and 20.7 +/- 2.6). It can thus be concluded that growth of capillaries in skeletal muscles may be due to mechanical factors connected with the increased blood flow while in the heart AA may act in concert with blood flow changes.

Angiogenesis Inducing Agents↗
PubMed1988

The effect of chronic bradycardial pacing on the oxidative capacity in rabbit hearts.

Blood flow and oxygen consumption were estimated in isolated hearts from control rabbits or animals with chronic bradycardia achieved by transvenous atrial pacing for 4 weeks; these parameters were related to ultrastructural changes. Chronic reduction of heart frequency to about 50% of control values resulted in an increased capillary/fibre ratio (1.43 +/- 0.07 in paced, 1.26 +/- 0.07 in control hearts), increased capillary density (2339 +/- 148 vs 1897 +/- 95) and increased volume density of mitochondria (36.36 +/- 1.28% vs 31.38 +/- 1.7%), in paced and control hearts, respectively, with no signs of heart hypertrophy (fibre diameters 28.5 micron in both groups). Maximal blood flow (3 ml.g-1.min-1) was similar in paced and control hearts. Maximal oxygen consumption (achieved by a gradual increase in preload and increase in force of contraction by noradrenalin infusion) in paced hearts was significantly higher than in control hearts and was achieved by a higher oxygen extraction. This could be due both to the increased volume density of mitochondria and to a more homogeneous distribution of flow through an enlarged capillary bed. The increased oxidative capacity induced by chronic bradycardial pacing can explain improved maximal cardiac work found under these conditions previously in vivo.

Animals↗
PubMed1988

Legionella bozemanii pneumonia in an immunocompromised patient.

Legionella bozemanii, a rare cause of pneumonia, has a predilection for patients with impaired cellular immunity and underlying disease. We report the 12th culture-proven case of this infection, acquired in the community by a patient undergoing chemotherapy for chronic lymphocytic leukemia. The diagnosis was established when studies of bronchoalveolar lavage fluid produced a positive reaction with species-specific fluorescent antibody and growth on selective culture media. Although erythromycin was administered within 48 hours after the initial examination, the clinical condition did not improve substantially until rifampin was added to the antimicrobial regimen.

Aged↗
PubMed1988

The effect of riboflavin deficiency in rats on the absorption and distribution of iron.

1. Riboflavin may play a part in the transport of iron across the gastrointestinal mucosa. Fe absorption was measured in the rat by monitoring whole-body retention of a dose of 59Fe using a small-animal gamma-counter. 2. Female Norwegian Hooded rats were fed on a diet deficient in riboflavin (B2-) from 5 weeks of age. Control animals, fed on a complete diet (B2+), were weight-matched to rats fed on the B2- diet. After 7 weeks all rats were fed on a test meal extrinsically labelled with 59Fe and whole-body radioactivity measured for 15 d. 3. Riboflavin deficiency was associated with a reduction in the percentage of the dose absorbed and an increase in the rate of loss of Fe post absorption. 4. A smaller percentage of the absorbed dose was present in the livers of the riboflavin-deficient animals.

Animals↗
PubMed1988

The effect of three types of saponin on iron and zinc absorption from a single meal in the rat.

1. Iron and zinc retentions in young male rats, given 3 g starch-sucrose paste containing 120 micrograms Fe as FeSO4 or 139 micrograms Zn as ZnCl2 (extrinsically labelled with 59Fe or 65Zn) and increasing amounts of Gypsophila saponins, were measured by whole-body counting. The results were compared with whole-body Fe and Zn retention from a meal containing crude or purified saponin fractions. In a separate experiment Fe retention from a meal containing Gypsophila saponins, soyasaponin I, or saponins extracted from lucerne (Medicago sativa) plant tops, was measured in older rats. 2. Results indicated that Fe absorption decreased with increasing concentration of Gypsophila saponins. This was significant at a saponin:Fe molar value of approximately 1, with maximum effect occurring at molar ratios of 4 and above, when Fe absorption was reduced by approximately 17%. Gypsophila saponins had no effect on Zn absorption from a test meal. 3. Fe absorption was similar in groups given purified or crude Gypsophila saponins at the same saponin:mineral molar value of 8, demonstrating that the 'non-saponin' fraction of the commercial preparation does not affect the absorption of this mineral. 4. Saponins extracted from lucerne plant tops, fed at a saponin:Fe value of approximately 8, also reduced Fe absorption from a single meal. Fe absorption from a meal containing a similar amount of soyasaponin I was not significantly different from controls. 5. These results indicate that some dietary saponins may reduce Fe absorption and hence have an adverse effect on Fe status in man and simple-stomached animals.

Absorption↗
PubMed1988

Effect of reduced dietary zinc intake on carbohydrate and Zn metabolism in the genetically diabetic mouse (C57BL/KsJ db+/db+).

1. Male, 4-5-week-old, genetically diabetic mice (C57BL/KsJ db/db) and non-diabetic heterozygote littermates (C57BL/KsJ db/+) were fed on a diet containing 1 mg zinc/kg (low-Zn groups) or 54 mg Zn/kg (control groups) for 27 d. Food intakes and body-weight gain were recorded regularly. On day 28, after an overnight fast, animals were killed and blood glucose and insulin concentrations, liver glycogen, and femur and pancreatic Zn concentrations were determined. 2. The consumption of the low-Zn diet had only a minimal effect on the Zn status of the mice as indicated by growth rate, food intake and femur and pancreatic Zn concentrations. In fact, diabetic mice fed on the low-Zn diet had a higher total food intake than those fed on the control diet. The low-Zn diabetic mice had higher fasting blood glucose and liver glycogen levels than their control counterparts. Fasting blood insulin concentration was unaffected by dietary regimen. 3. A second experiment was performed in which the rate of loss of 65Zn, injected subcutaneously, was measured by whole-body counting in the two mouse genotypes over a 28 d period, from 4 to 5 weeks of age. The influence of feeding low-Zn or control diets was also examined. At the end of the study femur and pancreatic Zn and non-fasting blood glucose levels were determined. 4. All mice fed on the low-Zn diet showed a marked reduction in whole-body 65Zn loss compared with those animals fed on the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗