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Biomedical subjects

C E West

Publications and source records attributed to C E West.

At least 19 recordsLinked to original sources
PubMed1992

Effects of vitamin A deficiency and Newcastle disease virus infection on lymphocyte subpopulations in chicken blood.

The effect of vitamin A deficiency and Newcastle disease virus (NDV)-infection on peripheral blood lymphocytes (PBL) was studied by differential cell counting and flow cytometry. Day-old chickens were fed purified diets containing either marginal or adequate levels of vitamin A and at 26 days of age half of the chickens in each group were infected with NDV. The absolute numbers of PBL and their subpopulations were studied until 10 days after infection. Vitamin A deficiency resulted in significantly lower numbers of PBL throughout the experiment. NDV-infection produced lymphopenia during the first 3 days, followed by a strong increase in PBL numbers after 6 days. Both changes in PBL were less pronounced in vitamin A-deficient birds. For flow cytometric analysis monoclonal antibodies reacting specifically with B-cells or a subpopulation of T-cells were used. Vitamin A-induced lymphopenia could be attributed to a decreased number of PBL, negative for both antibodies, and to the absence of an increase in B-cells which normally occurs at this age. The negative cells are suggested to represent, at least partially, cytotoxic T-cells, which may explain the impaired cytotoxic T-cell-activity found in earlier studies. NDV-induced lymphopenia and subsequent increase of PBL could be attributed to all cell types investigated. However, in vitamin A-deficient birds negative cells did not show these reactions. Therefore, it can be concluded that vitamin A deficiency has a detrimental effect on PBL, negative for both antibodies used, and on the normal growth of the number of B-cells at this age.

Animals↗
PubMed1992

Iron status in rats fed a purified diet without vitamin A.

The effect of vitamin A deficiency on iron status was investigated in rats. After 28 d of feeding either low or high vitamin A diets (0 vs 4000 IU of vitamin A per kg feed), the final body weight was slightly but significantly lowered by the low vitamin A diet. Plasma retinol concentrations were decreased in rats fed diets low in vitamin A. Marginal vitamin A deficiency produced slightly, but significantly lower blood hemoglobin concentrations; it did not clearly affect hematocrit. The concentration of iron in liver was significantly higher when diets low in vitamin A were fed while significantly lower levels were observed in femur.

Animals↗
PubMed1992

Production of chickens with marginal vitamin A deficiency.

Marginally vitamin A-deficient 1-d-old chickens capable of remaining healthy for at least 6 weeks were produced using a two-generation model. In this model, hens fed on diets with a limited vitamin A content were used to obtain 1-d-old chickens which were marginally deficient in vitamin A. Only hens with a narrow range of plasma retinol values (0.60-0.85 mumol/l) were satisfactory for this purpose. Above this range the 1-d-old chickens were not marginally vitamin A deficient. Below this range egg production and hatchability were affected to some extent depending on the degree of vitamin A deficiency. Even when egg production and hatchability remained at a high level in such birds, the 1-d-old chickens produced were not sufficiently strong to survive the first weeks of life. The advantages of the two-generation model for producing marginally vitamin A-deficient chickens are the increased uniformity and predictability of the chickens with respect to body-weight, general health and vitamin A status. However, it does take about 3 months to produce such chickens.

Animals↗
PubMed1992

Effect of vitamin A deficiency and Newcastle disease virus infection on IgA and IgM secretion in chickens.

The effect of vitamin A deficiency or the lentogenic La Sota strain of Newcastle disease virus (NDV) infection, or both, on immunoglobulin (IgA and IgM) levels in bile and plasma were investigated. In addition, tissue distribution of IgA-, IgG- and IgM-containing cells was studied to establish the source of these Ig. Chickens (1-d-old) with limited vitamin A reserves were fed ad lib. on diets containing either marginal or adequate levels of vitamin A. At 4 weeks of age, half the chickens in each group were infected with NDV. The number of IgA- and IgM-containing cells was not significantly affected by vitamin A deficiency, demonstrating that neither class-switching nor homing of Ig-containing cells is influenced by vitamin A deficiency. Although bile IgM levels were not significantly different in vitamin A-deficient chickens compared with normal chickens, IgA levels were significantly lower. This decrease was even more pronounced in deficient NDV-infected chickens, despite the higher number of IgA-containing cells found in these birds. These results, together with the slightly increased levels of IgA in plasma of vitamin A-deficient chickens, suggest that the hepatobiliary transport of IgA is impaired by vitamin A deficiency and possibly also by NDV infection, although disturbed secretion by IgA-containing cells cannot be excluded.

Animals↗
PubMed1992

Cross-sectional study on the iron and vitamin A status of pregnant women in West Java, Indonesia.

A cross-sectional study of the prevalence of iron and vitamin A deficiency in normal pregnant women in West Java, Indonesia, was carried out. Of the 318 women studied, 49.4% were anemic and, according to multiple criteria, 43.5% had iron-deficiency anemia, 22.3% had iron-deficient erythropoiesis, and 6.6% had iron depletion. Serum retinol values revealed that 2.5% of the pregnant women were vitamin A deficient and 31% had marginal vitamin A status. The relative dose-response test carried out on 45 women showed that 4 (8.9%) had deficient vitamin A liver stores. After gestational stage, parity, and subdistrict were adjusted for, serum retinol concentrations were significantly positively associated (P < 0.01) with hemoglobin concentrations, hematocrit, and serum iron concentrations. The suboptimal vitamin A status associated with nutritional-deficiency anemia suggests that pregnant women in the area should be supplemented not only with iron but also with vitamin A. This proposal should be tested in an intervention study.

Cross-Sectional Studies↗
PubMed1992

Epithelia-damaging virus infections affect vitamin A status in chickens.

The effect of infection with infectious bronchitis virus (IBV) and reovirus (RV) on vitamin A status was investigated in chickens with a normal or marginal intake of vitamin A. At the age of 4 wk, chickens were infected with either IBV or RV, primarily affecting the respiratory or intestinal tract, respectively. Both viruses lowered plasma retinol levels significantly. The effect was more pronounced in chickens fed a diet marginally deficient in vitamin A than in those fed a diet adequate in vitamin A. Concentrations of retinol-binding protein, transthyretin and albumin in RV-infected chickens were also significantly lower than in noninfected chickens fed the same diets; in chickens infected with IBV, there was no effect. These results suggest that the reduced vitamin A status of IBV-infected chickens could be attributed to increased rate of utilization by tissues. In RV infection, this mechanism could be involved but impaired absorption of nutrients (including vitamin A) and direct loss of nutrients via the intestinal tract could also be important.

Animals↗
PubMed1992

Causes of blindness in children in the blind schools of Ethiopia.

A total of 721 children in the six schools for the blind in Ethiopia were studied. In 1988-1989 histories were taken to ascertain the predisposing factors and ophthalmological examinations and records were used to determine the causes of blindness. Ninety-five per cent of those examined had bilateral blindness, 12% did not know how they had become blind and, of those who provided information on how they became blind, 21% knew that they were born blind, 30% implicated measles as being responsible, and 13% implicated 'mitch' which is an Amharic term used to describe a very wide range of nonspecific and vague illnesses of which measles probably constitutes a significant proportion. Seventy per cent of the blindness was due to either corneal opacity or phthisis bulbi. Of those with non-congenital bilateral corneal opacity or phthisis bulbi, 40% were preceded by measles and 17% by mitch. A study of 66 adults in the handicraft and skill-training centres attached to the blind schools indicated that the principal predisposing factors of blindness were mitch (30%), smallpox (15%), cataract (12%), and traditional eye medicine (11%). Seventy percent had corneal scars of phthisis bulbi and 14% cataract.

Adolescent↗
PubMed1991

Changes in lymphoid organs and blood lymphocytes induced by vitamin A deficiency and Newcastle disease virus infection in chickens.

The effect of vitamin A deficiency in the presence or absence of Newcastle disease virus infection (NDV, La Sota strain) on weight of lymphoid organs and on the number and type of circulating white blood cells (WBC) was investigated in chickens. Day-old chickens with limited vitamin A reserves were fed purified diets containing either marginal (ad libitum) or adequate (pair-fed) levels of vitamin A and at 21-28 days of age; half the chickens in each group were infected with NDV. Vitamin A deficiency resulted only in significantly lower absolute and relative weights of bursa of Fabricius and after infection both weights of bursa and thymus were significantly lower. Relative weight of spleen was significantly higher after infection irrespective of vitamin A status. Liver weights were not affected by vitamin A status and/or NDV infection. Both vitamin A deficiency and NDV infection resulted in lymphopenia, while the lowest number of WBC were observed in vitamin A-deficient chickens during the acute phase of NDV (5 days after infection). Subsequent to lymphopenia due to NDV infection, a marked lymphocytosis was observed in controls and to a lesser extent in vitamin A-deficient birds. These results indicate that vitamin A deficiency, which is aggravated by concomitant NDV infection, affects lymphoid cell systems.

Animals↗
PubMed1991

Effect of vitamin A deficiency on the activity of macrophages in Newcastle disease virus-infected chickens.

The effect of vitamin A deficiency on the activity of peritoneal macrophages (PM) was investigated in noninfected and Newcastle disease virus (NDV)-infected chickens. Day-old chickens with limited vitamin A reserves were fed diets containing either marginal (120 retinol equivalents (RE)/kg) or adequate (1200 RE/kg) levels of vitamin A. At 4 weeks of age, half of the chickens in each group were infected with the La Sota strain of NDV and PM were isolated 11 or 12 days later. These were used for counting the uptake of fluorescein isothiocyanate-labeled yeast cells as an indicator of phagocytic activity and for measuring the reduction of nitroblue tetrazolium (NBT), which provides an estimate of oxygen-dependent killing of microorganisms. Vitamin A deficiency impaired NBT reduction and, to a lesser extent, phagocytosis in both infected and noninfected chickens. NDV infection increased phagocytosis and NBT reduction in normal and, to a lesser extent, in vitamin A-deficient chickens.

Animals↗
PubMed1991

Xerophthalmia in Ethiopia: a nationwide ophthalmological, biochemical and anthropometric survey.

A total of 6636 children, aged from 6 months to 6 years and selected throughout the country using a multi-staged stratified sample design, were examined for signs of xerophthalmia. The concentrations of retinol and of beta-carotene were measured in 742 children, including those with xerophthalmia and every twentieth of the remaining children. Anthropometric measurements were made on 2909 of the children. Bitot's spots were seen in 1.0% of all children, with a higher prevalence in the pastoral (1.6%) and cropping (1.1%) agro-ecological zones than in the zones characterized by cash crops (0.4%) and 'ensete' (false banana, Ensete ventricosum) (0.0%). One case of corneal xerosis and 2 cases of corneal scar were also seen. Serum retinol levels were in the 'deficient' range (less than 0.35 mumol l-1) in 16% and 'low' (0.35-0.69 mumol l-1) in 44% of children. Serum retinol and clinical signs did not show any correlation with occupation and education of head of household, household size or anthropometric measurements. More stunting than wasting was observed, with peak prevalence of these signs of malnutrition being observed in the second year of life.

Agriculture↗
PubMed1990

Vitamin A deficiency impairs cytotoxic T lymphocyte activity in Newcastle disease virus-infected chickens.

The effect of vitamin A deficiency on cytotoxic T lymphocyte (CTL) activity was investigated during the acute phase of disease 7 days after primary inoculation and 1 day after secondary inoculation in chickens with or without Newcastle disease virus (NDV, La Sota strain) infection. Day-old chickens with limited vitamin A reserves were fed purified diets containing either marginal (ad libitum) or adequate (pair-fed) levels of vitamin A, and at 3 weeks of age half of the chickens in each group were infected with NDV. Cytotoxic activity was investigated during the acute phase of disease (7 days after primary inoculation) and 1 day after secondary inoculation, in an assay system with either peripheral blood lymphocytes (PBL) or nonadherent splenocytes as effector cells and adherent splenocytes from the same animal as target cells. After primary inoculation, cytotoxic activity could only be demonstrated in nonadherent splenocytes. Vitamin A deficiency resulted in significantly reduced CTL activity at all effector/target cell ratios tested. After reinfection CTL activity could also be demonstrated in PBL, but only from chickens fed the control diet, suggesting a diminished pool of CTL in vitamin A deficiency. The results of this study indicate that vitamin A deficiency impairs CTL activity - a part of the cell-mediated defense system - and this may have important implications for recovery from viral infection.

Animals↗
PubMed1990

Dietary animal proteins and cholesterol metabolism in rabbits.

The effect in rabbits of giving isonitrogenous purified diets containing casein, ovalbumin, fish protein, milk-whey protein and soya-bean protein were compared. The diets were balanced for cholesterol and for the amount and type of fat. When incorporated into low-cholesterol diets (0.08 g cholesterol/kg), casein, ovalbumin and soya-bean protein produced similar levels of serum cholesterol. With a high background of dietary cholesterol (1.5 g/kg), serum cholesterol concentrations increased with soya-bean protein, whey protein, casein and fish protein, in that order. Thus, the hypercholesterolaemic effect of casein in carefully balanced diets was only seen against a high-cholesterol background. The development of hypercholesterolaemia produced by giving fish protein was different from that produced by casein. First, less cholesterol accumulated in the very-low-density-lipoprotein fractions and more in the lipoproteins of higher density with fish protein than with casein. Second, fish protein, unlike casein, did not increase liver cholesterol. Third, transfer of rabbits from a diet containing soya-bean protein to one containing casein resulted in an immediate marked depression in neutral steroid and bile acid excretion in faeces. However, when rabbits were fed on the diet with fish protein after the diet with soya-bean protein, there was no significant depression in neutral steroid output and the depression in bile acid output was delayed. The present study suggests that different animal proteins cause hypercholesterolaemia by different mechanisms.

Animals↗
PubMed1990

Cholesterol metabolism, digestion rates and postprandial changes in serum of swine fed purified diets containing either casein or soybean protein.

Swine fitted with re-entrant ileo-cecal cannulas were fed purified diets containing either casein or soybean protein to study possible relations between cholesterol metabolism, digestion of dietary constituents and postprandial patterns of various serum components. Compared with soybean protein, dietary casein produced an increase in serum total cholesterol in which the excess cholesterol was located in the low density lipoprotein fraction. Ileal and fecal excretion of neutral steroids was diminished in pigs fed casein, suggesting that cholesterol absorption was stimulated. The apparent ileal absorption of protein was increased in pigs fed casein. The enhanced absorption of cholesterol and protein was associated with a reduced rate of flow of chyme through the ileum. The output of bile acids in the feces of pigs fed casein was decreased, whereas the ileal output was not significantly affected. This could be attributed to increased uptake of bile acids from the cecum and/or colon, which may in part be related to the indirectly observed decreased formation of secondary bile acids. Postprandial serum concentrations of insulin and glucose were temporarily increased in pigs fed casein, whereas those of triglycerides were decreased. We suggest that the decreased excretion of cholesterol and bile acids is the major determinant of casein-induced hypercholesterolemia in swine.

Animals↗
PubMed1990

Boys from populations with high-carbohydrate intake have higher fasting triglyceride levels than boys from populations with high-fat intake.

Experimentally, high-carbohydrate diets have been shown to elevate triglycerides, but it has not been established whether this rise is permanent or transient. The authors approached this question by studying 719 boys from worldwide populations with marked differences in long-term carbohydrate intake. Fasting serum triglycerides, total cholesterol and high density lipoprotein (HDL) cholesterol concentrations were measured in boys aged 8 and 9 years from 12 countries--eight in Europe, three in Africa, and one in Asia. A standardized protocol was used for obtaining fasting blood and for the preparation, storage and transport of serum, and all measurements were made in one laboratory. Published values were used for the United States. Mean values for lipid levels per country were compared with the percentage of daily energy intake consumed as carbohydrate or fat, as determined by survey. Boys from populations with higher carbohydrate and lower fat intake had lower low density lipoprotein (LDL) cholesterol levels (univariate regression coefficient (+/- standard error, -0.028 +/- 0.009 mmol/liter for each percent of energy from carbohydrate; p less than 0.01, n = 13), but they also had higher fasting triglycerides (0.010 +/- 0.002 mmol/liter for each percent of energy from carbohydrate; p less than 0.01, n = 13) and lower HDL cholesterol levels (-0.022 +/- 0.003 mmol/liter for each percent of energy from carbohydrate; p less than 0.001, n = 13). These trends agree with results from epidemiologic studies within populations and from controlled dietary trials, and suggest that in normolipidemic healthy subjects, high-carbohydrate, low-fat diets cause higher triglyceride levels than diets that are higher in fats and oils.

Africa↗
PubMed1989

Digestibility of casein, formaldehyde-treated casein and soya-bean protein in relation to their effects on serum cholesterol in rabbits.

Adult male rabbits were fed on semi-purified diets containing soya-bean protein isolate, casein or formaldehyde-treated casein as the protein source and 1 g cholesterol and 5 g of the non-absorbable marker chronic oxide/kg diet. The concentration of cholesterol in serum and in liver was increased on both the casein and formaldehyde-treated-casein diets. Excretion of bile acids and their concentration in faeces were lower in rabbits fed on casein or formaldehyde-treated casein when compared with rabbits fed on soya-bean protein. Apparent digestibility of nitrogen was lowest when formaldehyde-treated casein was fed, and highest on the casein diet. In rabbits fed on casein treated with formaldehyde, higher proportions of N were found in the water-soluble and trichloroacetic acid-insoluble protein fractions of the gastrointestinal tract contents compared with rabbits on the other two diets. Absorption of phosphate from the gastrointestinal tract was higher in rabbits fed on casein than in rabbits fed on soya-bean protein or formaldehyde-treated casein. The results indicate that, in rabbits, protein digestibility may not be an important determinant of serum cholesterol.

Animals↗
PubMed1989

Development and relative validity of a food frequency questionnaire for the estimation of intake of retinol and beta-carotene.

The aim of this study was to develop and validate a semiquantitative food frequency questionnaire to classify individuals according to their intakes of retinol and beta-carotene. Food items for the questionnaire were selected both on the basis of their contribution to total population intake of retinol and beta-carotene and on the proportion of between-person variation explained, which was as calculated from data of two study populations in the Netherlands. Thus, 15 products containing retinol and 15 products containing beta-carotene were selected. These contributed over 90% to the total intake and explained 99% of the variation of retinol and beta-carotene, respectively. The questionnaire was validated against a dietary history in a population of 82 women (aged 30-49 years). The time elapsed between the two interviews was (on average) 25 days. Spearman rank-order correlation coefficients comparing the questionnaire with the dietary history were 0.54, 0.59, and 0.64 for retinol, beta-carotene, and total vitamin A, respectively. The proportion of exact agreement in the two extreme categories of vitamin A intake, based on quintiles, was 56%. The corresponding gross misclassification (from 1 extreme category into the opposite) was 3%. These data indicate that a very short questionnaire can classify subjects into categories according to their vitamin A intake.

Adult↗