Academic health center administrators don't perish when they don't publish.
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Academic Medical Centers↗
Biomedical subjects
R H Glew
Publications and source records attributed to R H Glew.
The fatty acid composition of human milk in northern Nigeria.
The authors previously reported that the milk of Yoruba women in southwestern Nigeria was deficient in alpha-linolenic acid and contained a high percentage (42%) of medium chain-length fatty acids (MCFA, C10-C14). In the present study, the authors used capillary gas-liquid chromatography to analyze the milk of Hausa women in the northern region of Nigeria. The milk of the Hausa women contained 27% MCFA, 10.6% linoleic acid, 0.41% alpha-linolenic acid, 0.52% arachidonic acid, and 0.32% docosahexaenoic acid. The proportion of alpha-linolenic acid in the serum phospholipids of a subset of exclusively breastfed infants (n = 15; mean age, 6.2 +/- 0.3 months) was below the limit of detection (< 0.03%). While the milk of women in northern Nigeria is adequate with regard to n-3 and n-6 fatty acids, to satisfy the requirements for alpha-linolenic acid, it may be necessary to supplement the infants of these women after the first 6 months of life.
Adult↗
Folate and vitamin B12 status of adolescent girls in northern Nigeria.
The diets of populations in many developing countries are low in folate and vitamin B12 and a deficiency of either of these vitamins results in increased risk for cardiovascular disease and neural tube defects. The rates of neural tube defects in Nigeria are among the highest reported worldwide. Since many girls marry at an early age in northern Nigeria, we therefore determined the folate and vitamin B12 status of adolescent girls between 12 and 16 years of age in Maiduguri, Nigeria. The mean serum folate concentration for subjects was 15.3 +/- 5.2 nmol/L. Whereas only four subjects (2.4%) had serum folate concentrations lower than 6.8 nmol/L, a level indicative of negative folate balance, 9% of the subjects had serum vitamin B12 concentrations at or below 134 pmol/L, the lower limit of the reference range for their age group. Serum homocysteine was measured in 56 of the 162 subjects and the mean level was 15.9 +/- 5.0 mumol/L. The majority of subjects had serum homocysteine concentrations above the upper limit of the reference range for their age group. We conclude that the adolescent girls we studied were at greater risk for vitamin B12 deficiency than folate deficiency. This conclusion is consistent with the fact that their diet included few foods that contained vitamin B12.
Adolescent↗
The joys of international work.
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Bibliographies as Topic↗
Increased serum levels of N-telopeptides (NTx) of bone collagen in postmenopausal Nigerian women.
Serum levels of cross-linked N-telopeptides (NTx) of bone collagen, alkaline phosphatase (ALP), and intact parathyroid hormone (PTH) were determined in 64 premenopausal (PRM) and 86 postmenopausal (PSM) women living in northern Nigeria. Serum NTx values were correlated with ALP activity (r = 0.31-0.58, P < 0.01) and PTH (0. 32-0.35, P < 0.01)) in all of the subjects studied, and were also related to age (-0.47, P < 0.001) and body mass index (-0.45, P < 0. 001) in PRM women. Menopause had the effect of increasing the circulating concentrations of NTx and ALP activity by 15% (P = 0. 001) and 11% (P = 0.02), respectively; however, serum levels of PTH were not different between these two groups of women. Compared with Caucasian counterparts matched for age and body mass index, PSM Nigerian women had significantly increased circulating concentrations of NTx (21.7 versus 16.2 nmol BCE/liter, P = 0.01) and demonstrated a trend towards higher ALP activities and PTH levels. These results indicate that (1) discrete reference intervals should be defined for biochemical markers of bone metabolism in African populations, (2) Nigerian women have relatively higher rates of bone turnover, and (3) further investigation of the implications of increased serum NTx should be undertaken using physical methods such as dual X-ray absorptiometry (DXA) and bone ultrasound attenuation.
Adult↗
Selective retention of n-3 and n-6 fatty acids in human milk lipids in the face of increasing proportions of medium chain-length (C10-14) fatty acids.
This paper reports the results of our analysis of the impact high levels of de novo fatty acids have on the proportions of essential and non-essential fatty acids in human milk lipids. The data for seven fatty acids (linoleic, alpha-linolenic, arachidonic (AA), docosahexaenoic (DHA), palmitic, stearic and oleic) were derived from several studies conducted in Nigeria. The proportion by weight of each of these fatty acids was plotted versus the proportion of C10-14 fatty acids. As the proportion of C10-14 fatty acids increased from 15 to 65%, there was not a proportional decrease in the percentages of all seven fatty acids, but, instead, preferential incorporation of the essential fatty acids, AA and DHA into the triacylglycerol component of the milk. At the same time, the proportions of stearic and oleic acid declined by 69% and 86%, respectively. However, the proportions of linoleic acid, palmitic acid, DHA, AA and alpha-linolenic acid, in milk lipids decreased by only 44%, 40%, 39%, 28% and 2.3%, respectively. These observations indicate that as the contribution of C10-14 fatty acids increases, essential fatty acids are preferentially incorporated into milk triacylglycerols at the expense of oleic acid and stearic acid.
Adolescent↗
Rickets in Nigerian children: response to calcium supplementation.
In a previous study of rachitic children in Jos, Nigeria we concluded that inadequate dietary intake of calcium was the primary contributing factor to the development of their rickets. The objective of the present study was to determine the effect of calcium supplementation in 10 children with radiographically and biochemically proven rickets from the same geographical area. Rachitic children were provided with calcium supplements of 1000 mg/day for a period of 3 months. Serum and urine samples were obtained at baseline and at 24 hours, 1 week, 4 weeks, and 12 weeks after initiation of supplementation. Serum calcium, phosphorus, alkaline phosphatase, intact parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were measured at each time point. Dietary recalls obtained at two separate times were used to estimate usual daily intakes of calcium and phosphorus. Ten non-rachitic age-matched controls from the same geographical area were recruited for comparison. Nine of 10 rachitic subjects had radiographic evidence of healing after 3 months of calcium therapy. Although serum calcium concentrations returned to control levels, other biochemical data indicated that the rickets of these subjects may have been multifactorial in aetiology, pointing to a possible defect in the synthesis of 25-hydroxyvitamin D.
Anthropometry↗
Aminoaciduria in calcium-deficiency rickets in northern Nigeria.
Generalized aminoaciduria is associated with vitamin D-deficiency rickets in humans, but there is little information regarding aminoaciduria in rickets caused by primary calcium deficiency. In contrast to rickets in other parts of the world, this bone disease in Nigeria is caused primarily by inadequate intake of dietary calcium. We conducted a clinical trial in Jos, Nigeria in 10 children with radiographically and biochemically proven rickets; an equal number of non-rachitic healthy children from the same area served as controls. Serum and 24 h urine samples were obtained at baseline and at 24 h, 1 week, 4 weeks, and 12 weeks after initiation of calcium supplementation (1000 mg/day) and were analysed for their content of amino acids. Serum calcium, phosphorus, intact parathyroid hormone (PTH), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were also measured at each time point. In the rachitic subjects urinary amino acid concentrations were elevated from 2- to 16-fold at baseline, while serum amino acid levels increased 1.5- to 3.8-fold compared to controls. After 12 weeks of calcium supplementation, serum and urine amino acids decreased. There was no correlation between the degree of aminoaciduria and serum PTH or 1,25-dihydroxyvitamin D concentrations. We conclude that the aminoaciduria in these rachitic children was related to their calcium status and not to their vitamin D or PTH status.
Amino Acids↗
Differential effects of heparin on the early and late phases of hepatic ischemia and reperfusion injury in the pig.
The mechanisms by which heparin protects the liver during induced episodes of liver ischemia-reperfusion are poorly understood. Previous work in a swine model demonstrated that serum levels of glycohydrolases and lipid peroxide peaked within 3 h after 45 minutes of hepatic ischemia followed by reperfusion. Serum levels of lactate dehydrogenase and aspartate aminotransferase peaked 20-24 h later. The aim of this study was to evaluate the effect of heparin on these two-phases of enzyme release, using a pig model of hepatic ischemia-reperfusion injury. Twenty male swine were divided into control (n = 8) and heparin (n = 12) groups. In the heparin group, heparin was administered prior to and concurrent with ischemia-reperfusion. Following 45 min of hepatic ischemia, the levels of beta-galactosidase, beta-glucosidase, acid phosphatase, purine nucleoside phosphorylase, lipid peroxides, lactate dehydrogenase, and aspartate aminotransferase in serum were monitored for up to 166 h and compared to pre-ischemic and control levels. With heparin infusion, the peak levels of beta-galactosidase, beta-glucosidase, and the lipid peroxide were reduced to 50-60% of the control levels. Acid phosphatase and purine nucleoside phosphorylase activities in serum were reduced to 25% and 60%, respectively. The peak concentrations of lactate dehydrogenase and aspartate aminotransferase were reduced to about 25% of the control level. In addition, the serum enzymes of control pigs did not return to pre-ischemic levels until 2 weeks after hepatic ischemia, while they normalized in less than 1 week in the heparin-treated animals. Systemic heparinization had different protective effects on the first and secondary phases of liver injury. These differences may reflect heparin protection of different types of liver cells. The protection of the parenchymal cells may be the combined result of reduced sinusoidal cell injury and the anticoagulant properties of heparin.
Acid Phosphatase↗
Content of lipid nutrients in the milk of Fulani women.
Little is known about the nutrition of the infants of the Fulani, migratory nomads of the western Sahel of Africa. Milk was collected from 18 Fulani women 10 to 30 days postpartum and the fatty acid compositions of the triacylglycerol and phospholipid fractions were determined by capillary gas-liquid chromatography. De novo fatty acids (10:0-14:0) comprised 36.3 +/- 12.7% of fatty acids of the triacylglycerols. Compared to the milk of various populations worldwide, the milk of the Fulani women contained adequate proportions of alpha-linolenic acid (0.50 +/- 0.16%) and arachidonic acid (0.42 +/- 0.22%), but relatively low amounts of linoleic acid (9.95 +/- 2.13%) and docosahexaenoic acid (DHA) (0.15 +/- 0.08%). In addition, the milk of the Fulani women contained adequate concentrations of beta-carotene (1.58 +/- 0.69 micrograms/dl) and vitamin A (42.7 +/- 40.3 micrograms/dl), but very low levels of vitamin E (0.11 +/- 0.10 mg/dl). These data indicate that exclusively breasted infants of Fulani women were receiving relatively low amounts of critical fatty acids and vitamin E.
Adolescent↗
Methionine infusion reproduces liver injury of parenteral nutrition cholestasis.
Cholestatic jaundice is the major complication of total parenteral nutrition (TPN) in infancy. We have previously shown that the TPN solution is directly toxic to the liver, and that this toxicity appears to be mediated by one or more amino acids. Elevated serum methionine levels, without corresponding increases in its metabolites, suggest that accumulation of this toxic amino acid may cause TPN cholestasis. Nine-week-old rabbits (n = 28) were divided into three groups. The FED group was fed standard rabbit chow ad libitum. The TPN group was not fed and received only i.v. TPN (including methionine 121 mg.kg-1.d-1), and lipids. The EXP group was fed chow ad libitum and received i.v. methionine (121 mg.kg-1.d-1). After 14 d, we evaluated bile flow, bromosulfophthalein excretion, serum liver enzymes, liver histology, and serum amino acid levels. Bile flow was significantly depressed in the TPN and EXP groups compared with FED controls (32.9 +/- 9.4 and 45.7 +/- 14.4 versus 82.9 +/- 13.8). Excretion of the bilirubin analog bromosulfophthalein tended to be delayed by methionine infusion (p = 0.15). Serum liver enzymes (aspartate transaminase, alanine aminotransferase, gamma-glutamyltransferase, and alkaline phosphatase) were normal in all groups. Histologic liver injury in the EXP group was similar to that caused by TPN. Balloon degeneration, and portal inflammation were seen in both groups. Homocysteine, an early metabolite of methionine, was elevated in the TPN and EXP groups compared with FED controls. Intravenous methionine is hepatotoxic. Despite full oral feeding, it produces a depression of bile flow and histologic liver injury similar to that seen with TPN. Elevated homocysteine levels suggests an enzymatic block early in the pathway of methionine metabolism. We believe that methionine may be an important factor in the pathogenesis of TPN cholestasis.
Amino Acids↗
Catalytic mechanism and specificity for hydrolysis and transglycosylation reactions of cytosolic beta-glucosidase from guinea pig liver.
Cytosolic beta-glucosidase (CBG) from mammalian liver is known for its broad substrate specificity and has been implicated in the transformation of xenobiotic glycosides. CBG also catalyzes a variety of transglycosylation reactions, which have been been shown with other glycosylhydrolases to function in synthetic and genetic regulatory pathways. We investigated the catalytic mechanism, substrate specificity, and transglycosylation acceptor specificity of guinea pig liver CBG by several methods. These studies indicate that CBG employs a two-step catalytic mechanism with the formation of a covalent enzyme-sugar intermediate and that CBG will transfer sugar residues to primary hydroxyls and equatorial but not axial C-4 hydroxyls of aldopyranosyl sugars. Kinetic studies revealed that correction for transglycosylation reactions is necessary to derive correct kinetic parameters for CBG. Further analyses revealed that for aldopyranosyl substrates, the activation energy barrier is affected most by the presence of a C-6 carbon and by the configuration of the C-2 hydroxyl, whereas the binding energy is affected modestly by the configuration and substituents at C-2, C-4, and C-5. These data indicate that the transglycosylation activity of CBG derives from the formation of a covalently linked enzyme-sugar intermediate and that the specificity of CBG for transglycosylation reactions is different from its specificity for hydrolysis reactions.
Animals↗
Expression of cytosolic beta-glucosidase in guinea pig liver cells.
The cytosolic beta-glucosidase of mammalian liver has been implicated in the metabolic transformation of plant glycosides, such as vicine and amygdalin, which are associated with the development of toxic syndromes. We investigated which cell types express cytosolic beta-glucosidase in guinea pig liver, and characterized the contribution of this enzyme to the hydrolysis of aromatic glucosides in cultured cells and in tissue slices. Cytosolic beta-glucosidase was expressed in hepatocytes and not in Kupffer or endothelial cells as determined by enzyme-specific activity and Western blots of liver cell extracts. Intracellular beta-glucosidase activity was visualized using the fluorescent beta-glucosidase substrate, resorufin beta-D-glucoside, and shown to be caused by the cytosolic beta-glucosidase using the inhibitors, conduritol beta-epoxide and dinitrophenol-2-deoxy-2-fluoro-beta-D-glucopyranoside (DNP2FGlc). Staining of fresh liver slices with resorufin beta-glucoside revealed that cytosolic beta-glucosidase is expressed in all hepatocytes, with no significant portal-central gradient. These data indicate that cytosolic beta-glucosidase is a hepatocyte-specific enzyme, and support the hypothesis that cytosolic beta-glucosidase in the liver functions to hydrolyze small glucosides absorbed by the intestine. Furthermore, toxic injury to cultured hepatocytes by CCl4 resulted in release of cytosolic beta-glucosidase in parallel with the hepatocyte marker enzymes alanine transaminase and lactate dehydrogenase. This suggests that acute increases in serum levels of cytosolic beta-glucosidase in animal models of liver injury may reflect direct injury of hepatocytes.
Animals↗
Calcium supplements increase the serum levels of crosslinked N-telopeptides of bone collagen and parathyroid hormone in rachitic Nigerian children.
OBJECTIVES: Biochemical markers of bone turnover were measured in the sera of 16 controls and 10 children with calcium-deficiency rickets, during a 12-week course of calcium supplementation (1 g CaCO3/d) that was effective in healing the bone lesions of the rachitic children. DESIGN AND METHODS: Serum levels of crosslinked N-telopeptides of bone collagen (NTx), parathyroid hormone (PTH), alkaline phosphatase (ALP), and urinary deoxypyridinoline (LP) were assayed at baseline and during the course of calcium therapy and compared with data of the 16 non-rachitic controls. RESULTS: Calcium therapy suppressed serum NTx and PTH levels in the rachitic children within 24 h; however, after the first week, PTH and NTx levels increased to the extent that at 12 weeks both were elevated when compared with controls or to baseline levels. Serum levels of NTx and PTH were correlated in the controls and experimental subjects (r = 0.63, p < 0.001). CONCLUSIONS: The rate of bone resorption, as estimated by serum NTx concentration, is increased during the healing of rachitic lesions.
Alkaline Phosphatase↗
Use of the Trolox assay to estimate the antioxidant content of seventeen edible wild plants of Niger.
Although wild edible plants of the western Sahel and other parts of sub-Saharan Africa are consumed to some extent at all times of the year, greater amounts are consumed when cereal harvests are insufficient to support the populations living in these areas. The purpose of this study was to use a recently reported Trolox-based assay to measure the total antioxidant capacity of aqueous extracts of 17 plants that we gathered from southern Niger. The antioxidant contents of the aqueous extracts were compared to those of spinach and potato. Of the 17 plants, 11 had a greater antioxidant content than spinach and 14 had a greater antioxidant content than potato. The leaves of Tapinanthus globiferus had the greatest antioxidant content, and the fruit of Parinari macrophylla had the lowest. In general, leaves contained more antioxidants than either fruits or seeds. The total antioxidant capacity of the aqueous extracts was relatively high, indicating that the wild plants of the western Sahel may contain substantial amounts of water-soluble flavonoid glycosides, which are potent antioxidants and have been shown to have anticancer properties.
Antioxidants↗
Serum levels of cross-linked N-telopeptides and aminoterminal propeptides of type I collagen indicate low bone mineral density in elderly women.
Levels of aminoterminal propeptide (PINP) and the cross-linked carboxyterminal (ICTP) and aminoterminal (NTx) telopeptides of type I collagen were determined in the sera of 202 healthy women, 60-90 years of age, and correlated with densitometric measurements of their lumbar spine, femoral neck, and total body regions. Total skeleton bone mineral density (BMD) was associated most strongly with serum NTx levels (r = -0.51, p < 0.0001). Serum NTx and PINP levels correlated with BMD at all regions measured and were significantly increased in osteopenic women (16.0 vs. 13.3 nmol bone collagen equivalents/L for NTx, p = 0.0006 and 46.5 vs. 40.9 micrograms/L for PINP, p = 0.02). Elevations of NTx and PINP over a 3 year interval correlated with decreases in BMD measured at the femoral neck and to increases in serum concentration of alkaline phosphatase activity and ICTP. Serum levels of ICTP, NTx, PINP, ICTP, estrone, and alkaline phosphatase activity were correlated and serum NTx values were related to circulating thyroxine and intact parathyroid hormone levels. NTx and PINP levels were significantly decreased in the sera of women receiving estrogen replacement therapy (12.0 vs. 14.8 nmol bone collagen equivalents/L for NTx, and 35.5 vs. 45.2 micrograms/L for PINP, p < 0.001). Multiple regression analysis indicated that 42% of the variability observed in total skeletal BMD could be explained by age, weight, and serum levels of NTx and estrone. Within this model of covariance, the serum NTx level alone accounted for 10.1% of total body BMD variability.
Absorptiometry, Photon↗
Analysis of nutritional components of eight famine foods of the Republic of Niger.
In the western Sahel, indigenous plants become important staples when cereal harvests are inadequate to support populations inhabiting that region of Africa. The purpose of this study was to assess the nutrient content of several of these edible wild plants. The leaves of the following seven plant foods were analyzed: Ziziphus mauritiana, Cerathotheca sesamoides, Moringa oleifera, Leptadenia hastata, Hibiscus sabdarifa, Amaranthus viridis, and Adansonia digitata. The fatty acid, vitamin E, carotenoid, selected mineral and amino acid contents of these plant foods were determined. These same analyses were performed on the fruit of the Adanisonia digitata. In quantitative and qualitative terms, Amaranthus viridis was found to be an excellent source of protein. Its amino acid composition compared favorably to that of a World Health Organization (WHO) protein standard. It also contained considerable amounts of the two fatty acids that are essential in humans (linoleic and alpha-linolenic) and a number of minerals including iron, magnesium. calcium and zinc. The leaves of Hibiscus sabdarifa contained an appreciable quantity of protein the composition of which was comparable to the WHO standard. The mineral content of the leaves of this plant was also exceptionally high; noteworthy was its high zinc content. H. sabdarifa also contained significant quantities of the two essential fatty acids. Ziziphus mauritiana was an excellent source of the essential fatty acid linoleic acid and several of the metals including iron, calcium, magnesium and zinc. Its content of other essential nutrients, however, was rather low. In general, Adansonia digitata leaves were nutritionally superior to the fruit of the tree; however, the fruit did contain useful quantities of potassium, phosphorus, zinc and alpha-linolenic acid. The Leptadenia hastata leaves were an especially good source of lutein and beta-carotene. These data should be useful to the people who inhabit the western Sahel in helping them devise healthy diets during times when cereal staples are in short supply.
Amino Acids↗
Nutrient content of the edible leaves of seven wild plants from Niger.
Wild plants play an important role in the diet of the inhabitants of Niger. These plants tend to be drought-resistant and are gathered both in times of plenty as well as times of need. Used in everyday cooking, famine foods may be an important source of nutrients. The goal of this study was to investigate the nutritional role of wild plants in the nigérien diet. To this end, leaves of seven plants species were analyzed for their mineral, amino acid and fatty acid contents: Ximenia americana, Amaranthus viridus, Corchorus tridens, Hibiscus sabdarifa, Maerua crassifolia, Moringa oleifera, and Leptadenia hastata. Ximenia americana contained large amounts of calcium. Large quantities of iron were present in Amaranthus viridus. All seven plants contained significant amounts of selenium and phosphorus. Corchorus tridens contained the most protein (19-25% dry weight), and its composition compared favorably to the World Health Organization's standard for essential amino acids. Moringa oleifera contained 17% protein and compared favorably with the WHO standard. Corchorus tridens contained the largest amounts of the two essential fatty acids linoleic and alpha-linolenic acids. These results reinforce the growing awareness that wild edible plants of the Western Sahel can contribute useful amounts of essential nutrients, including amino acids, fatty acids and trace minerals, to human diets.
Amino Acids↗