PubMed Health⌕ Search

Biomedical subjects

L H Allen

Publications and source records attributed to L H Allen.

At least 19 recordsLinked to original sources
PubMed2005

Low erythrocyte folate, but not plasma vitamin B-12 or homocysteine,is associated with dementia in elderly Latinos.

The relationship between B vitamin status and cognitive function has been of interest for many years. There is evidence of relationships between intake and status of folate and vitamin B-12 with neurological, cognitive, and memory impairment, but results have been inconsistent. Plasma B-12, erythrocyte folate, methylmalonic acid,and homocysteine were evaluated as predictors of cognitive function in a large population based sample of Latino elderly living in the Sacramento, California region. The hypothesis tested was that low folate and/or B-12 status predicts cognitive function impairment and dementia. Logistic regression was used to examine the differences in B-vitamin status by cognitive function category. Erythrocyte folate was related to dementia after controlling for age, gender, education, income, diabetes diagnosis, serum creatinine, and depressive symptoms. The highest prevalence of low erythrocyte folate occurred in the Dementia group and was significantly higher than in the Normal group. Plasma B-12, MMA, Hcy, and prevalence of a normal values for these variables, were not significantly different among the cognitive function classes. We conclude that folate status is associated with dementia but that more research is needed on the relationship between vitaminB-12 status, Hcy and cognitive function to explore possible associations with these parameters.

Aged↗
PubMed2004

Pulque intake during pregnancy and lactation in rural Mexico: alcohol and child growth from 1 to 57 months.

OBJECTIVE: To examine maternal intake of a mildly alcoholic beverage (pulque) during pregnancy and lactation, and its potential effect on postpartum child growth and attained size. DESIGN: A prospective cohort study that followed mothers (during pregnancy and lactation) and their offspring (from birth to approximately 57 months of age). SETTING: Six villages in rural, central Mexico. SUBJECTS: Subjects are 58 mother-child pairs. Pulque intake was measured as part of a dietary assessment that was conducted for 2days/month during pregnancy and early lactation. RESULTS: Most mothers consumed pulque during pregnancy (69.0%) and lactation (72.4%). Among pulque drinkers, the average ethanol intake was 125.1 g/week during pregnancy and 113.8 g/week during lactation. Greater pulque intake during lactation, independent of intake during pregnancy, was associated with slower weight and linear growth from 1 to 57 months, and smaller attained size at 57 months. Low-to-moderate pulque intake during pregnancy, in comparison to either nonconsumption or heavy intake, was also associated with greater stature at 57 months. CONCLUSIONS: Pulque intake during lactation may have adversely influenced postnatal growth in this population. Public health interventions are urgently needed in Mexico to reduce heavy intake of pulque by pregnant and lactating women, and to replace intake with foods that provide the vitamins and minerals present in the traditional alcoholic beverage.

Adult↗
PubMed2004

Persistence, distribution, and emission of Telone C35 injected into a Florida sandy soil as affected by moisture, organic matter, and plastic film cover.

With the phase-out of methyl bromide scheduled for 2005, alternative fumigants are being sought. This study of Telone C35, a mixture of (Z)- and (E)-1,3-dichloropropene (1,3-D) with chloropicirin (CP), focuses on its emissions, distribution, and persistence in Florida sandy soil in microplots with different soil-water and organic matter carbon (C) content with and without two different plastic film mulches. The addition of CP did not affect the physical behavior of the isomers of 1,3-D. Slower subsurface dispersion and longer residence time of the mixed fumigant occurred at higher water content. An increase in the percent organic carbon in the soil led to a more rapid decrease for chloropicirin than for 1,3-dichloropene isomers. The use of a virtually impermeable film (VIF) for soil cover provided a more even distribution and longer persistence under all the conditions studied in comparison to polyethylene (PE) film cover or no cover. The conditions of near field capacity water content, low organic matter, and a virtually impermeable film cover yielded optimum conditions for the distribution, emission control, and persistence of Telone C35 in a Florida sandy soil.

Allyl Compounds↗
PubMed2001

Evaluation of validity of items for a food behavior checklist.

OBJECTIVES: To evaluate the validity of food behavior items, using a biological measure (serum carotenoids) as the criterion for validity of fruit and vegetable intake, and the results from multiple 24-hour recalls to test convergent validity with nutrient intake. DESIGN: Participants responded to 39 food-behavior questions and later completed three 1-day dietary recalls. Serum carotenoid levels were determined for a 59% randomly selected subsample. SUBJECTS/SETTING: A convenience sample of 100 English-speaking, low-income women participating in a Food Stamp Nutrition Education Program in 8 California counties. Statistical analyses Spearman correlation coefficients were calculated between responses to the food behavior items and (a) serum carotenoid levels and (b) mean nutrient intakes from the 24-hour recalls. Cronbach's coefficient alpha was determined for items within broad food behavior topics. RESULTS: Responses to 10 food behavior items were significantly correlated with serum carotenoid levels (correlations greater than 0.45 were found for choosing low-fat foods and a self-evaluation of overall dietary quality). An additional 12 items showed hypothesized associations with the 24-hour recall data (with a maximum correlation 0.50 for number of eggs per week and dietary cholesterol). Cronbach's coefficient alpha ranged from 0.28 (for 5 fat and cholesterol items) to 0.79 (for 9 fruit and vegetable items). APPLICATIONS/CONCLUSIONS: Nutrition professionals can use these methods to validate items for food behavior checklists for specific populations. The items described here may be useful when designing instruments to administer to low-income women in a community setting.

Adult↗
PubMed2001

RNA localization and germ cell determination in Xenopus.

In many organisms the proper development of the embryo depends on the asymmetrical distribution of maternal RNAs and proteins in the egg. Although the Xenopus oocyte is radially symmetrical it contains distinct populations of maternal RNAs that are localized either in the animal or vegetal pole. The process of localization of RNAs in Xenopus oocytes occurs during the long period of oocyte differentiation and growth that is accompanied by the elaboration of oocyte polarity. Some of the vegetally localized RNAs, such as Vg1, VegT, and Xwnt11, are involved in axial patterning and germ layer specification. Others, such as Xdazl and Xcat2, which are located in the germ plasm, are likely to play a role in the specification of germ cell fate. We will discuss the different aspects of RNA localization in Xenopus in the context of the differentiation of the germ cells and the development of the oocyte polarity.

Animals↗
PubMed2001

Maternal consumption of pulque, a traditional central Mexican alcoholic beverage: relationships to infant growth and development.

OBJECTIVES: To document the consumption during pregnancy of pulque, a traditional central Mexican alcoholic beverage, and its relationship to subsequent infant size, physical growth and performance on the Bayley Scales of Infant Development. DESIGN: Prospective cohort study. SETTING: Six villages in rural, central Mexico in 1984-1985. SUBJECTS: Seventy mother-infant pairs. RESULTS: Most women (72.9%) consumed pulque during pregnancy, and 28.6% consumed more than 150 g ethanol week(-1) from the beverage. Individuals who consumed pulque showed no compensating decrease in energy obtained from other foods. Pulque consumption possessed curvilinear relationships with both infant length (at 1 and 6 months) and Bayley mental performance (at 6 months). Heavy pulque intakes were associated with smaller infant size and poorer mental performance. In modest quantities, pulque consumption may have been beneficial due to its micronutrient content. CONCLUSIONS: Intakes of alcohol from pulque were common among pregnant women in these rural, central Mexican villages. Given current scientific knowledge of the adverse effects of ethanol on foetal development, public health interventions are needed to reduce heavy pulque consumption during pregnancy in some areas of rural Mexico.

Adult↗
PubMed2001

Biological mechanisms that might underlie iron's effects on fetal growth and preterm birth.

A negative association between anemia and duration of gestation and low birth weight has been reported in the majority of studies, although a causal link remains to be proven. This paper explores potential biological mechanisms that might explain how anemia, iron deficiency or both could cause low birth weight and preterm delivery. The risk factors for preterm delivery and intrauterine growth retardation are quite similar, although relatively little is understood about the influence of maternal nutritional status on risk of preterm delivery. Several potential biological mechanisms were identified through which anemia or iron deficiency could affect pregnancy outcome. Anemia (by causing hypoxia) and iron deficiency (by increasing serum norepinephrine concentrations) can induce maternal and fetal stress, which stimulates the synthesis of corticotropin-releasing hormone (CRH). Elevated CRH concentrations are a major risk factor for preterm labor, pregnancy-induced hypertension and eclampsia, and premature rupture of the membranes. CRH also increases fetal cortisol production, and cortisol may inhibit longitudinal growth of the fetus. An alternative mechanism could be that iron deficiency increases oxidative damage to erythrocytes and the fetoplacental unit. Iron deficiency may also increase the risk of maternal infections, which can stimulate the production of CRH and are a major risk factor for preterm delivery. It would be useful to explore these potential biological mechanisms in randomized, controlled iron supplementation trials in anemic and iron-deficient pregnant women.

Adrenocorticotropic Hormone↗
PubMed2001

Nutrition: a reservoir for integrative science.

In the last twenty years, powerful new molecular techniques were introduced that made it possible to advance knowledge in human biology using a reductionist approach. Now, the need for scientists to deal with complexity should drive a movement toward an integrationist approach to science. We propose that nutritional science is one of the best reservoirs for this approach. The American Society for Nutritional Sciences can play an important role by developing and delivering a cogent message that convinces the scientific establishment that nutrition fills this valuable niche. The society must develop a comprehensive strategy to develop our image as the reservoir for life sciences integration. Our efforts can start with our national meeting and publications, with the research initiatives for which we advocate, with our graduate training programs and with the public relations image we project for ourselves. Defining the image and future directions of nutrition as the discipline that can integrate scientific knowledge from the cell and molecule to the whole body and beyond to populations can be the most important task that our society undertakes. If we do not effectively meet this challenge, a golden opportunity will pass to others and nutritional scientists will be left to follow them.

Biological Science Disciplines↗
PubMed2000

Iron and zinc supplementation improves indicators of vitamin A status of Mexican preschoolers.

BACKGROUND: The coexistence of multiple micronutrient deficiencies is a widespread public health problem in many regions of the world. Interactions between zinc deficiency and vitamin A metabolism have been reported but no longitudinal studies have evaluated the effect of iron deficiency on vitamin A. OBJECTIVE: The objective of this study was to investigate the effect of supplementation with iron, zinc, or both on vitamin A and its metabolically related proteins retinol binding protein (RBP) and transthyretin. DESIGN: The study was a longitudinal, double-blind, placebo-controlled trial in which 219 rural Mexican children aged 18-36 mo were randomly assigned to receive 20 mg Zn/d, 20 mg Fe/d, 20 mg Zn/d plus 20 mg Fe/d, or placebo. RESULTS: Six months after supplementation, plasma retinol increased in all supplemented groups. Compared with placebo, zinc supplementation was associated with significantly higher plasma retinol and transthyretin but the increase in RBP was not significant. Iron supplementation significantly increased plasma retinol, RBP, and transthyretin. Supplementation with zinc plus iron significantly increased plasma retinol but not RBP or transthyretin. Children deficient in zinc, iron, or vitamin A (as indicated by nutrient plasma concentration) at the beginning of the study had a significantly greater increase in retinol than did children with adequate nutrient status. CONCLUSIONS: Supplementation with zinc, iron, or both improved indicators of vitamin A status. The results of this study agree with previous observations of a metabolic interaction between zinc and vitamin A and suggest an interaction between iron and vitamin A metabolism.

Child, Preschool↗
PubMed2000

Anemia and iron deficiency: effects on pregnancy outcome.

This article reviews current knowledge of the effects of maternal anemia and iron deficiency on pregnancy outcome. A considerable amount of information remains to be learned about the benefits of maternal iron supplementation on the health and iron status of the mother and her child during pregnancy and postpartum. Current knowledge indicates that iron deficiency anemia in pregnancy is a risk factor for preterm delivery and subsequent low birth weight, and possibly for inferior neonatal health. Data are inadequate to determine the extent to which maternal anemia might contribute to maternal mortality. Even for women who enter pregnancy with reasonable iron stores, iron supplements improve iron status during pregnancy and for a considerable length of time postpartum, thus providing some protection against iron deficiency in the subsequent pregnancy. Mounting evidence indicates that maternal iron deficiency in pregnancy reduces fetal iron stores, perhaps well into the first year of life. This deserves further exploration because of the tendency of infants to develop iron deficiency anemia and because of the documented adverse consequences of this condition on infant development. The weight of evidence supports the advisability of routine iron supplementation during pregnancy.

Anemia, Iron-Deficiency↗
PubMed2000

Lack of hemoglobin response to iron supplementation in anemic mexican preschoolers with multiple micronutrient deficiencies.

BACKGROUND: In developing countries, incomplete resolution of anemia with iron supplementation is often attributed to poor compliance or inadequate duration of supplementation, but it could result from deficiencies of other micronutrients. OBJECTIVE: Our objective was to assess children's hematologic response to supervised, long-term iron supplementation and the relation of this response to other micronutrient deficiencies, anthropometry, morbidity, and usual dietary intake. DESIGN: Rural Mexican children aged 18-36 mo (n = 219) were supplemented for 12 mo with either 20 mg Fe, 20 mg Zn, both iron and zinc, or placebo. Children were categorized as iron-unsupplemented (IUS; n = 109) or iron supplemented (IS; n = 108). Hemoglobin, hematocrit, mean corpuscular volume, mean cell hemoglobin, plasma concentrations of micronutrients that can affect hematopoiesis, anthropometry, and diet were assessed at 0, 6, and 12 mo; morbidity was assessed biweekly. RESULTS: At baseline, 70% of children had low hemoglobin (</=115 g/L), 60% had low hematocrit, 48% were ferritin deficient, 10% had deficient and 33% had low plasma vitamin B-12 concentrations, 29% had deficient vitamin A concentrations, and 70% had deficient vitamin E concentrations. Iron supplementation increased ferritin from 11 +/- 14 microg/L at baseline to 31 +/- 18 microg/L after 6 mo (P < 0.001) and 41 +/- 17 microg/L after 12 mo. However, anemia persisted in 30% and 31% of supplemented children at 6 and 12 mo, respectively, and was not significantly different between the IUS and IS groups at 12 mo. Initial plasma vitamin B-12, height-for-age, and dietary quality predicted the hematopoietic response to iron. CONCLUSION: Lack of hemoglobin response to iron was associated with indicators of chronic undernutrition and multiple micronutrient deficiencies.

Anemia↗
PubMed2000

Iron absorption from ferrous bisglycinate and ferric trisglycinate in whole maize is regulated by iron status.

BACKGROUND: There is a need to determine whether iron absorption from iron amino acid chelates is protected from inhibition by dietary phytate and regulated normally by iron status. OBJECTIVE: The objective of this study was to compare iron absorption from ferrous sulfate, ferrous bisglycinate, and ferric trisglycinate in whole-maize meal; to determine whether iron from ferrous bisglycinate and ferrous sulfate exchanges in the intestinal pool; and to assess iron absorption from ferrous bisglycinate and ferric trisglycinate over a range of iron statuses. DESIGN: In study 1A, 10 iron-sufficient men consumed ferrous sulfate-fortified whole-maize meal porridge equilibrated with (59)Fe-sulfate on day 1 and (55)Fe-bisglycinate on day 2. In study 1B, these volunteers consumed ferrous sulfate-fortified porridge equilibrated with (59)Fe-sulfate and (55)Fe-bisglycinate simultaneously. In studies 2A and 2B, iron absorption from 3 mg Fe as (59)Fe-ascorbate, (55)Fe-bisglycinate, or (59)Fe-trisglycinate in water and in porridge was compared in 23 subjects with a range of iron statuses. Iron absorption was determined from blood radioactivity on day 16. RESULTS: In study 1A, geometric mean iron absorption from ferrous bisglycinate was 6.0% (range: 2.6-13.6%), 4 times higher than that from ferrous sulfate (1. 7%; range: 1.0-3.3%; P < 0.05). In study 1B, absorption from neither source was different from that in study 1A. In studies 2A and 2B, absorption from all sources was strongly inversely related to serum ferritin, with geometric means of 32.5% (iron ascorbate), 9.1% (bisglycinate), and 15.3% (trisglycinate). Iron from ferric trisglycinate was poorly absorbed (2.3%; range: 0.5-9.2%) from maize. CONCLUSION: In whole-maize meal, iron from ferrous bisglycinate is better absorbed than is iron from ferrous sulfate and does not exchange with iron from maize or ferrous sulfate in the intestinal pool. Absorption of iron from bisglycinate and trisglycinate is regulated normally by iron status.

Absorption↗
PubMed2000

In vitro and in vivo macrophage function can occur independently of SLP-76.

Expression of SH2 domain-containing leukocyte-specific phosphoprotein of 76 kDa (SLP-76), a hematopoietic cell-specific adapter protein, is required to couple Syk family tyrosine kinase activation to downstream mediators such as phospholipase C (PLC)-gamma following TCR, platelet collagen receptor and mast cell Fc epsilon R stimulation. In addition to T cells, mast cells and platelets, SLP-76 is expressed in monocytes and macrophages. To determine the role of SLP-76 in Fc gamma R-stimulated signaling pathways in macrophages, we examined cultured bone marrow-derived macrophages (BMM) from SLP-76(-/-) and wild-type mice. In this study, we show that Fc gamma R cross-linking rapidly induces tyrosine phosphorylation of SLP-76 in wild-type BMM. Surprisingly, however, BMM from SLP-76(-/-) mice activate ERK2 and phosphorylate PLC-gamma 2 following Fc gamma R ligation. Furthermore, SLP-76(-/-) BMM display normal Fc gamma R-dependent phagocytic function and reactive oxygen intermediate production. SLP-76(-/-) and SLP-76(+/+) BMM secrete comparable levels of IL-12 in response to lipopolysaccharide and IFN-gamma. To examine macrophage function in vivo, SLP-76(-/-) mice were challenged i.v. with Listeria monocytogenes. SLP-76(-/-) mice survive and efficiently contain the acute phase of infection similar to wild-type mice but exhibit a stable chronic infection attributed to the lack of mature T cells. These data show that, although SLP-76 is required to couple Syk family PTK activity to downstream mediators and effector functions in Fc gamma R-induced pathways in some cell types, activation of Fc gamma R-dependent pathways occurs independently of SLP-76 in BM

Adaptor Proteins, Signal Transducing↗
PubMed1998

Spot ferritin assay for serum samples dried on filter paper.

A spot method was developed for analyzing ferritin from 20-microL serum samples (n = 71) that were spotted and dried on filter paper and stored frozen (2 d). Spot samples were thawed, incubated in a buffer containing cellulase, and centrifuged and the supernate assayed for ferritin by a commercial radioimmunoassay. The geometric means (+/- 1 SD) for ferritin analyzed with the spot and traditional methods were 49.4 (range: 14.9-164.0) and 47.5 (range: 14.4-156.0) micrograms/L, respectively. The two methods correlated strongly (r = 0.98, P = 0.0001). Storage of spot samples (n = 31) under various conditions (at room temperature, refrigerated, or frozen for 2 wk, or at room temperature for 4 wk) in airtight bags before analysis yielded ferritin values that were not significantly different from those obtained by the traditional method. Ferritin values from spotted samples stored at room temperature for 4 wk before being analyzed were only 2.2 micrograms/L higher than those from samples analyzed by the traditional method. With iron depletion defined as a serum ferritin concentration < 15 micrograms/L, this method corresponded absolutely with the traditional method in classifying individuals as iron sufficient or deficient. Thus, the spot ferritin method (with samples stored at room temperature for 4 wk) offers a reliable, accurate, and practical tool for iron status assessment in field studies. Capillary blood can be sampled to avoid the costs and concerns associated with venipuncture and spotted serum samples can be stored at room temperature for > or = 4 wk, eliminating the need for freezing during storage and transportation.

Adolescent↗
PubMed1998

Zinc and micronutrient supplements for children.

Provision of zinc supplements to children should be considered when their usual diet is low in absorbable zinc; severe stunting, low plasma zinc, or both; or persistent diarrhea. Inadequate zinc intakes are highly prevalent in developing countries, especially during the period of complementary feeding when zinc requirements are high and breast milk contributes little. To date, systematic evaluation of the acceptability of different zinc salts used as supplements is lacking. Some zinc salts are unpalatable and cause problems, such as nausea, at higher doses. Zinc carbonate and oxide are insoluble and poorly absorbed. Little information on the bioavailability of different zinc supplements in the presence of dietary inhibitors of zinc absorption exists. More information is needed on the quantity and frequency of dosing. Consideration should be given to the routine inclusion of zinc in iron supplements provided to children and to the simultaneous inclusion of other micronutrients in zinc supplements.

Child, Preschool↗
PubMed1998

Intervention within days for some orbital floor fractures: the white-eyed blowout.

Management of blowout fractures involving the orbital floor has been controversial over the past several decades. One school of thought recommends conservative treatment for 4 to 6 months while another recommends a 'wait and watch' period of 2 weeks before intervention. The authors have encountered a group of patients with such fractures, commonly children (less than 16 years of age), who have sustained a blow to the periocular area, yet have marked motility restrictions in up and down gaze, minimal soft tissue signs of trauma, lack of enophthalmos, and very minimal evidence of floor disruption on radiologic exam. A 2-week waiting period has been found to be of little benefit in these persons and possibly harmful to their motility. We advocate surgery within the first few days after injury as it may help to avoid permanent motility restriction. The authors have termed this entity 'the white-eyed blowout fracture.'

Adolescent↗