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Biomedical subjects

K H Brown

Publications and source records attributed to K H Brown.

At least 19 recordsLinked to original sources
PubMed1999

Epidemiology of altered intestinal permeability to lactulose and mannitol in Guatemalan infants.

BACKGROUND: Subclinical alterations of small intestinal function have been reported frequently in tropical countries. Studies of small intestinal permeability to lactulose and mannitol were therefore completed in Guatemalan infants from a low-income, periurban community to assess the prevalence of altered intestinal function and the factors associated with this condition. METHODS: Two hundred studies were successfully completed in 158 infants who had been free of diarrhea for at least 1 week before the day of study. Urinary concentrations of lactulose and mannitol during the 5-hour period after ingestion of 400 mg/kg body weight of lactulose and 100 mg/kg body weight of mannitol were measured by gas-liquid chromatography and compared by age group, feeding practices, anthropometric indexes, and serum iron and zinc concentrations. RESULTS: The overall prevalence of altered intestinal permeability (defined as a ratio of urinary recovery of lactulose to mannitol [L/M] > or =0.07) was 30%. The urinary L/M recovery ratio was positively associated with age; low weight for age; and, in infants less than 6 months of age, non-breast-feeding. Children with serum iron concentrations less than 7.16 microM/l (40 [microg/dl) had higher median L/M ratios (L/M = 0.068; 95% confidence interval [CI], 0.054, 0.085) than those with iron levels higher than this cutoff (L/M = 0.052; CI = 0.046, 0.058; p = 0.038). The median urinary L/M recovery ratio in 10 currently asymptomatic infants who had diarrhea during the week before testing (0.087; CI = 0.49, 0.154) was higher than that in children who had been free from diarrhea for at least 1 week (0.052; CI = 0.048, 0.056; p = 0.01). CONCLUSION: Age, feeding practices, low weight-for-age, low serum iron concentration, and recent diarrhea were all associated with altered intestinal function in this group of Guatemalan infants.

Aging↗
PubMed1998

Effects of age of introduction of complementary foods on iron status of breast-fed infants in Honduras.

To evaluate the effect of introducing complementary foods before 6 mo of age, we randomly assigned 164 infants who had been exclusively breast-fed for 4 mo to continue being exclusively breast-fed until 6 mo (EBF group) or to receive iron-fortified foods in addition to breast milk from 4 to 6 mo (BF+SF group). At 6 mo, the BF+SF group had higher mean iron intake (4 mg/d compared with 0.2 mg/d in EBF infants) and higher hemoglobin, hematocrit, and ferritin values than the EBF group (P < 0.05). The percentage with low hemoglobin (< 103 g/L) did not differ significantly between groups, but fewer infants in the BF+SF group had a low hematocrit (< 0.33; 21.4% compared with 32.0%, respectively; P < 0.05). The percentage of infants with ferritin concentrations < 12 microg/L at 6 mo was lower than the percentage with low hemoglobin or hematocrit, raising questions about the validity of the cutoffs at this age. Infants at greatest risk for anemia and low ferritin were those with birth weights < 2500 g; no infant with a birth weight > 3000 g had a low ferritin value at 6 mo. We conclude that the risk of iron deficiency is low among infants with birth weights > 3000 g who are exclusively breast-fed for 6 mo. Iron drops are recommended for low-birth-weight infants; for breast-fed infants with birth weights between 2500 and 3000 g, further research is needed to determine whether iron drops are more effective than complementary foods for preventing iron deficiency before 6 mo.

Age Factors↗
PubMed1998

Plasma kinetics of an oral dose of [2H4]retinyl acetate in human subjects with estimated low or high total body stores of vitamin A.

The deuterated retinol dilution technique is an indirect method for quantitatively estimating total body stores of vitamin A by using the postequilibration plasma isotopic ratio [2H4]retinol:retinol and the prediction model described by Furr et al (Am J Clin Nutr 1989;49:713-6). Limited data are available on the time required for an oral dose of labeled vitamin A to mix with vitamin A body stores in human subjects. This article describes the plasma retinol kinetics of an oral dose of [2H4] retinyl acetate in 4 healthy adults (2 men and 2 women) and 1 healthy female child in the United States and in 4 Bangladeshi women. After an oral dose of [2H4]retinyl acetate was administered, plasma samples were collected at 6, 12, and 24 h postdose during the first day and at 15 time points during the subsequent 90-d period for measurement of plasma [2H4]retinol:retinol. The mean respective plasma isotopic ratios on day 20 for US and Bangladeshi subjects (0.02 +/- 0.02 and 0.17 +/- 0.12, P = 0.03) and estimated total body vitamin A reserves (1.03 +/- 0.45 and 0.10 +/- 0.11 mmol, P = 0.003) were significantly different. The fraction of dose in plasma was plotted against time, and biexponential equations were fit to the kinetic data by using the time points from 24 h through day 90. The mean equilibration time (time required for the fraction of dose in plasma to reach a plateau) for all subjects was 16.6 +/- 3.8 d (11-23 d). There was no difference in estimated equilibration time between the group of US and Bangladeshi adult subjects (17.5 +/- 4.4 and 16.3 +/- 3.9 d, respectively, P = 0.69). Thus, the size of hepatic vitamin A reserves does not appear to affect equilibration time within the range of values observed.

Adolescent↗
PubMed1998

Effect of infections on plasma zinc concentration and implications for zinc status assessment in low-income countries.

The development of intervention programs to control zinc deficiency is hampered by the lack of sensitive, specific, low-cost indicators of zinc status. The mean plasma zinc concentration of groups of individuals has been suggested as a possible indicator of a population's zinc status because the plasma zinc concentration seems to predict whether growth will increase in response to zinc supplementation. However, experimental studies in both animal models and adult human volunteers as well as clinical studies of infected and noninfected adults indicate that systemic infections that produce an acute phase response also cause the plasma zinc concentration to fall. Therefore, concerns have been raised about the usefulness of plasma zinc concentration as an indicator of zinc status in populations with high prevalences of infections. By contrast with the aforementioned studies in adults, cross-sectional, community-based surveys of children with and without common infections have not found any association between the presence of infection and plasma zinc concentration, possibly because the severity of those infections observed in children in field settings was less than that of the infections studied in adults. Thus, it appears that the mean plasma zinc concentration may be a useful indicator of population zinc status for children in low-income countries despite the high prevalence of common childhood infections encountered in these settings.

Adolescent↗
PubMed1998

Effect of genetically modified, low-phytic acid maize on absorption of iron from tortillas.

BACKGROUND: Genetically modified, low-phytic acid strains of maize were developed to enhance mineral absorption, but have not been tested previously in humans. OBJECTIVES: We evaluated the mineral and phytic acid contents of a low-phytic acid "flint" maize (LPM, the lpa-1-1 mutant) and its parent, wild-type strain (WTM) and measured iron absorption from tortillas prepared with each type of maize and from a reference dose of ferrous ascorbate. DESIGN: Proximate composition and mineral and phytic acid contents were measured by standard techniques. Iron absorption from tortillas was evaluated by using the extrinsic tag method and was measured as the incorporation of radiolabeled iron into the red blood cells of 14 nonanemic men 2 wk after intake. RESULTS: The phytic acid content of LPM was 3.48 mg/g, approximately 35% of the phytic acid content of WTM; concentrations of macronutrients and most minerals were not significantly different between strains. Iron absorption results were adjusted to 40% absorption of ferrous ascorbate. Iron absorption was 49% greater from LPM (8.2% of intake) than from WTM (5.5% of intake) tortillas (P < 0.001, repeated-measures analysis of variance). CONCLUSION: Consumption of genetically modified, low-phytic acid strains of maize may improve iron absorption in human populations that consume maize-based diets.

Adult↗
PubMed1998

Zinc supplementation improves the growth of stunted rural Guatemalan infants.

The impact of zinc supplementation on the growth and body composition of Guatemalan infants was assessed in a community-based, double-blind intervention trial. Infants aged 6-9 mo were assigned randomly to receive 4 mL of a beverage containing 10 mg of zinc as zinc sulfate (n = 45) or a placebo (n = 44) daily (7 d/wk) for an average of 6.9 mo. The children's weight, length, mid-upper arm and head circumferences, and triceps skinfolds were measured at baseline and at 1-2 mo intervals until the end of supplementation. Midarm muscle area (MMA) was derived from the mid-upper arm circumference and triceps skinfolds measurements. Maternal anthropometry and family socioeconomic and demographic characteristics also were obtained. Zinc supplementation was associated with an overall increase of 0.61 cm2 in MMA (P = 0.02). Children who received zinc supplements had a mean length increment that was 0.75 cm greater than those who did not (P = 0.12). However, there was a significant interaction between treatment group and initial length-for-age status (P = 0.04), such that supplemented children who were stunted at baseline (length-for-age Z score less than -2) gained 1.40 cm more than stunted children who received the placebo. We conclude that zinc supplementation of these rural Guatemalan infants during 6. 9 mo increased accretion of fat-free mass and enhanced the linear growth of those who were stunted at baseline. Further research is required to determine whether zinc supplementation during longer periods of time may achieve larger and more generalized effects on physical growth.

Body Composition↗
PubMed1998

Formaldehyde-related textile allergy: an update.

Part I of this study explores whether clothing today contains formaldehyde levels likely to cause contact allergy in formaldehyde-allergic patients. Part II of this study examines whether current reactions to textiles may be due to allergy to textile resins and whether individuals with formaldehyde-related textile allergy will react to the newer low formaldehyde resins used in the textile industry. Part I: free formaldehyde was measured in 16 fabric specimens produced in the US and overseas. Additionally, since the textile industry has moved to the use of newer methods for measuring fabric formaldehyde content, the newer methodology was compared with the older methods used in the medical literature. Part II: 10 subjects with known textile contact allergy were patch tested to available Chemotechnique textile resins and 6 new low-formaldehyde resins used by the textile industry. Part I: 8 fabric specimens yielded no detectable formaldehyde and 7 specimens yielded <200 ppm free formaldehyde, using Schiff's reagent and Merck testing methods. 1 specimen showed approximately 2000 ppm formaldehyde, as measured by the Merck test, but only 24 ppm free formaldehyde when retested by the method described in Japanese Law #112. Part II: all subjects reacted strongly to formaldehyde and DMDHEU (the predominant resin currently used in textiles). 6 subjects reacted to EUMF. 2 subjects had mild reactions to the newer low-formaldehyde resins and 1 to the non-formaldehyde Fixapret NF. Our results suggest that most clothing today yields free formaldehyde levels unlikely to cause contact allergy in formaldehyde-allergic individuals. Japanese method #112 is the recommended methodology to measure free formaldehyde in future studies. DMDHEU may now represent the main cause of textile allergy and may be a better screen than EUMF for this problem. Newer resins yielding fabrics with <75 ppm free formaldehyde may cause occasional reactions, but are more likely to be tolerated by individuals with textile contact allergy. Treatment of these individuals should be directed at identification of reliable sources of garments utilizing these newer resins.

Adult↗
PubMed1997

Validation of single daytime samples of human milk to estimate the 24-h concentration of lipids in urban Guatemalan mothers.

The large within- and between-sample variability in breast milk lipid content greatly complicates the collection of representative samples in field studies. The main purpose of this study was to validate the ability of individual daytime samples to predict the 24-h lipid concentration of breast milk. We also studied maternal, child, and other factors (time of day and interval between feeds) associated with the within- and between-mother variability in milk lipid content. Fifty-two primiparous urban Guatemalan women between 1 and 4 mo postpartum were studied. Milk samples were collected during six 2-h intervals from 0600 to 1800, and throughout the night when the child breast-fed. On average, the 24-h pooled milk samples contained 4.2 +/- 0.92% (mean +/- SD) lipids and the best concordance with this value was obtained with samples collected between 0600 and 0800 (concordance correlation coefficient = 0.60, P < 0.05). None of the regression equations to predict the 24-h lipid content of breast milk based on daytime samples reached a sufficiently high predictive power to be recommended for the estimation of individual child intake. Time of day and time elapsed since the last feeding were significant determinants of diurnal variations in milk lipid content, whereas between-mother variability was explained by maternal weight (P = 0.05) and body mass index (P < 0.05). For the collection of milk samples in surveys and pre-post studies, we recommend standardization of time of day and interval between feeds.

Adult↗
PubMed1997

Effects of age at introduction of complementary foods to breast-fed infants on duration of lactational amenorrhea in Honduran women.

Lactational amenorrhea (LA) is associated with postpartum infertility and is known to be related to breast-feeding frequency and duration, but the exact role of complementary feeding of the infant has not been clearly defined. Data on LA were collected during and after a 2-mo intervention trial in which low-income Honduran women who had breast-fed fully for 4 mo were randomly assigned to one of three groups: continued full breast-feeding until 6 mo (FBF, n = 50), introduction of complementary foods at 4 mo with ad libitum breast-feeding from 4 to 6 mo (SF, n = 47), or introduction of complementary foods at 4 mo with maintenance of baseline breast-feeding frequency from 4 to 6 mo (SF-M, n = 44). Women were followed up until the infant was 12 mo of age, or later if menses had not occurred by then. All but six of the women continued to breast-feed for > or = 12 mo. With the exclusion of those whose menses returned before 18 wk postpartum (which could not have been due to the intervention), the proportion of women who were amenorrheic at 6 mo was 64.5% in the SF group, 80.0% in the FBF group, and 85.7% in the SF-M group (chi-square test = 4.13, P = 0.02; one-tailed test with the latter two groups combined). The total duration of LA did not differ significantly among groups. The most significant determinant of LA was time spent breast-feeding (min/d), which was in turn negatively associated (P = 0.06) with the infant's energy intake from complementary foods in regression analyses. These results indicate that there is a significant effect of introducing foods at 4 mo on the likelihood of amenorrhea at 6 mo postpartum, but not thereafter, and that this effect is not seen in mothers who maintain breast-feeding frequency.

Adolescent↗
PubMed1997

Assessment of vitamin A status by the deuterated-retinol-dilution technique and comparison with hepatic vitamin A concentration in Bangladeshi surgical patients.

Hepatic stores of vitamin A were estimated in 31 Bangladeshi surgical patients (15 males and 16 females) by the deuterated-retinol-dilution (DRD) technique and by analysis of the vitamin A concentration of a liver biopsy specimen obtained during previously scheduled abdominal surgery. Patients ranged in age from 21 to 65 y and had an average body mass index (BMI: in kg/m2) of 17.7 +/- 3.4. They received 0.753 mumol [2H4]retinyl acetate/kg body wt orally 9-11 d before surgery. Hepatic vitamin A reserves were estimated according to Furr et al (Am J Clin Nutr 1989;49:713-6) by using a single plasma isotopic-ratio measurement (18-25 d postdose). Estimated mean hepatic vitamin A stores were similar by both techniques, 0.110 +/- 0.072 mmol (by DRD) compared with 0.100 +/- 0.067 mmol (by biopsy). Regression analysis was used to compare results of the DRD and biopsy techniques. A significant linear relation was found between the two techniques (r = 0.75, P < 0.0001), and the least-squares regression line was not significantly different from y = x (P = 0.09). The results indicate that the DRD technique provided a very good estimate of hepatic vitamin A reserves for this population. However, a wide prediction interval was observed for estimates of hepatic vitamin A reserves for individual subjects. Thus, further refinement of the prediction model is necessary to improve estimates of hepatic vitamin A reserves for individual subjects.

Abdomen↗
PubMed1997

Zinc supplementation affects the activity patterns of rural Guatemalan infants.

Zinc deficiency has been associated with growth deficits, reduced dietary intake and appetite, and has been hypothesized to result in reduced activity. This randomized, double-blind, placebo-controlled study examined whether 10 mg of oral zinc as zinc sulfate, given daily for up to 7 mo, affected activity patterns of 85 Guatemalan infants recruited at 6-9 mo of age. Infant activity was assessed by time sampling-observation method at 10-min intervals during a 12-h data collection period, at base line, 3 and 7 mo follow-up. Motor development and the percentage of time infants were observed in various positions (being carried, lying down, sitting, crawling, standing or walking) and engaged in various activities (eating, sleeping, resting, crying/whining or playing) were compared by treatment group. No differences in motor development were observed by treatment group. However, at follow-up 2 (after 7 mo of supplementation), zinc-supplemented infants were significantly more frequently observed sitting up compared with lying down, and were playing during 4.18 +/- 1.95% (P < 0.05) more observations than unsupplemented infants. They were also somewhat less likely to be observed crying or whining (P < 0.10) compared with those receiving the placebo. These effects are independent of other factors including infant age, motor development, sex, maternal education, family socioeconomic status and nutritional status at base line. Further research must be conducted to determine the long-term developmental importance of these differences in activity patterns associated with zinc supplementation in this setting.

Administration, Oral↗
PubMed1997

Acceptability, safety, and digestibility of spray-dried bovine serum added to diets of recovering malnourished children.

BACKGROUND: Specially collected, spray-dried bovine and porcine blood plasma have been incorporated previously in feeds of weanling farm animals, resulting in increased dietary intakes and greater rates of weight gain than observed in control animals. Before conducting similar trials in human populations, preliminary studies have been completed to assess the acceptability, safety, and digestibility of processed animal plasma in young children. METHODS: Masked study diets were provided sequentially to each of ten young, Peruvian children recovering from severe protein-energy malnutrition during three randomly ordered 7-day dietary periods. The control diet was prepared from rice, milk, vegetable oil, and sugar; the two study diets included spray-dried, bovine serum concentrate to replace either 25% or 50% of the milk protein of the control diet. Urine and feces were collected quantitatively during the last four days of each diet period to assess stool weight, apparent absorption of macronutrients, and retention of nitrogen. RESULTS: All children consumed the entire amounts offered of each of the diets. The mean number of daily bowel movements and mean apparent absorption and retention of nitrogen and mean apparent absorption of carbohydrate were similar for each diet. Fractional absorption of dietary lipid and of total energy increased significantly in relation to the amount of bovine serum concentrate in the diet, although this might be explained by the simultaneous replacement of milk fat with additional vegetable oil. CONCLUSIONS: Each of the diets was well accepted by the study children, and there was no evidence of any adverse effects of bovine serum concentrate.

Animals↗
PubMed1997

Impact of zinc supplementation on morbidity from diarrhea and respiratory infections among rural Guatemalan children.

OBJECTIVE: A community-based, randomized, double-blind intervention trial was conducted to measure the impact of zinc supplementation on young Guatemalan children's morbidity from diarrhea and respiratory infections. METHODS: Children aged 6 to 9 months were randomly assigned to receive 4 mL of a beverage containing 10 mg of zinc (as zinc sulfate) daily (7 d/wk) for 7 months (n = 45) or a placebo (n = 44). Morbidity data were collected daily. Diagnoses of diarrhea, fever, and anorexia were based on mothers' definitions. Respiratory infections were defined as the presence of at least two of the following symptoms: runny nose, cough, wheezing, difficulty breathing, or fever. RESULTS: High rates of diarrhea and respiratory infections were reported. Children from the placebo group had a 20% episodic prevalence of diarrhea, with 8 episodes/100 d, and a 7% episodic prevalence of respiratory infections, with 3 episodes/100 d. The median incidence of diarrhea among children who received zinc supplementation was reduced by 22% (Wilcoxon rank test), with larger reductions among boys and among children with weight-for-length at baseline lower than the median of the sample (39% reductions in both subgroups). Zinc supplementation also produced a 67% reduction in the percentage of children who had one or more episodes of persistent diarrhea (chi2 test). No significant effects were found on the episodic prevalence of diarrhea, the number of days per episode, or the episodic prevalence or incidence of respiratory infections. CONCLUSIONS: The large impact of zinc supplementation on diarrhea incidence suggests that young, rural Guatemalan children may be zinc deficient and that zinc supplementation may be an effective intervention to improve their health and growth.

Deficiency Diseases↗
PubMed1996

Feeding practices and growth among low-income Peruvian infants: a comparison of internationally-recommended definitions.

BACKGROUND: Data from a longitudinal study of 153 low-income Peruvian infants were used to assess the relationship between internationally-recommended definitions of feeding practices and infants' monthly weight gain and weight status at 12 months. METHODS: Infants were classified into feeding categories using monthly reported data. Analysis of variance was used to assess the relationship between reported usual feeding practices and growth. Reported breastfeeding practices were compared to observed breastfeeding practices and to weighted breast milk intakes to determine the validity of recommended breastfeeding definitions. RESULTS: Breastfed infants who consumed non-human milks during the first month of life gained less weight during that month (P < 0.002) than exclusively and predominantly breastfed infants. Reported daily nursing frequency was associated with observed nursing frequency and breast milk energy intake (P < 0.05) for infants < 9 months old. Patterns of growth varied according to early diets. Infants who consumed breast milk and non-human milks and those who were fully weaned by 4 months were more likely to be underweight at 12 months than other infants. Infants classified as token breastfeeders ( < or = 3 times/24 hours) from 0 to 120 days had monthly gains that were similar to those of fully weaned infants. CONCLUSIONS: Infants feeding definitions should 1) continue to differentiate exclusively breastfed infants from other infants who are almost exclusively or predominantly breastfed; 2) distinguish partially breastfed infants who consume only non-breastfeeding frequency or the % of their total daily energy that comes from breast milk.

Analysis of Variance↗
PubMed1996

Effect of postpartum maternal infection on proteins and trace elements in colostrum and early milk.

In developing countries, maternal infections during lactation are common. In this study, we evaluated the effect of acute maternal postpartum infection on the composition of colostrum and early milk with special emphasis on milk proteins and trace elements. The study was carried out in two maternity hospitals in Lima, Peru. Subjects were normally nourished women (body mass index (BMI) > 20.0) who intended to exclusively breastfeed their child and who had fever and clinical symptoms of infection within the first 48 h postpartum (n = 34). Non-ill women of similar characteristics were selected as controls (n = 23). Blood and milk samples were taken on days 1 and 14 postpartum. An acute phase response was confirmed by significantly increased serum levels of C-reactive protein in infected women. Serum zinc levels increased significantly from day 1 to day 14, but were not affected by infection. Serum copper levels were significantly higher in ill women than in non-ill women on day 1. All participating women were breastfeeding on day 14. Whey protein levels, the whey/casein ratio and total protein levels decreased significantly with time, but were not affected by infection. There were no differences in milk iron or copper levels with time or infection. Milk zinc levels decreased significantly with time, but were not affected by infection. Maternal infection during the early postpartum period does not appear to adversely affect the initiation of lactation or milk protein and trace element contents.

Adolescent↗