Biomedical subjects

M G Herrera

Publications and source records attributed to M G Herrera.

At least 19 recordsLinked to original sources

PubMed2003

Water and sanitation associated with improved child growth.

OBJECTIVE: To examine the relation between household water and sanitation, and the risk of stunting and reversal of stunting in Khartoum and Crezira regions, Sudan. DESIGN: Prospective cohort study. SETTING: A total of 25 483 children aged 6-72 months from rural Sudan enrolled in an 18-month field trial in 1988 to study the effect of vitamin A supplementation on child health and survival. RESULTS: The mean height-for-age z-scores at baseline and the end of study were -1.66 and -1.55, respectively, for the group with water and sanitation facilities, and -2.03 and -1.94 for the group without water and sanitation, after adjustment for age, region, gender, mother's literacy, intervention group (vitamin A vs placebo), family wealth, breastfeeding and cleanliness. Among children of normal height-for-age at baseline, the risk of stunting (<-2 height-for-age z-score) was lowest in the group that came from homes that had both water and sanitation compared to children from homes without these facilities (multivariate RR=0.79, 95% CI 0.69-0.90). Among children stunted at baseline, those coming from homes with water and sanitation had a 17% greater chance of reversing stunting than those coming from homes without either facility (adjusted RR=1.17, 95% CI 0.99-1.38). We did not detect a synergistic association between access to water and sanitation. CONCLUSIONS: Water and sanitation are independently associated with improved growth of children. SPONSORSHIP: None.

Body Height↗

PubMed2001

Biodegradation of phenol in a continuous process: comparative study of stirred tank and fluidized-bed bioreactors.

The paper presents the main results obtained from the study of the biodegradation process of phenol by a pure culture of Pseudomonas putida ATCC 17484. The experimental work was carried out in two different systems: a stirred tank where cells grew as a suspended culture and a fluidized bed where cells were immobilized within calcium alginate gel beads. The influence of the hydraulic residence time (HRT) and organic loading rate on the removal efficiency of phenol was determined for both bioreactors. Also, the stability of the fluidized-bed bioreactor (FBB) in terms of its ability to withstand sudden phenol overdoses is also reported. Experimental values indicated that both bioreactors showed high phenol degradation efficiencies, higher than 90%, even for a phenol loading rate in the influent as high as 4 g phenol/l day. The FBB showed better performance than the suspended-culture bioreactor due to its better control and because it could operate with lower HRT.

Alginates↗

PubMed2000

Reduced visual resolution acuity and cerebral white matter damage in very-low-birthweight infants.

Neonatal cerebral white matter echolucencies predict visual resolution acuity deficits in very-low-birthweight (VLBW) infants. We examined maternal sociodemographic, lifestyle, intrapartum, infant birth/perinatal, and ocular motor/refractive characteristics to determine whether they accounted for this association in infants who were tested once between postnatal age 25 and 56 weeks (corrected for gestational age at birth). Cranial ultrasound scans were read by consensus to identify echolucency in a population of VLBW infants with no known ocular abnormalities. Visual resolution acuity was measured with the Acuity Card Procedure (ACP) in 14 infants with echolucency and compared with that of 81 VLBW infants born in the same hospitals with normal ultrasound scans. In time-oriented logistic regression models, echolucency remained a consistent predictor of abnormal visual resolution acuity after adjustment for covariates in three developmental periods (pre-, peri-, and postnatal). Odds ratios ranged from 19.3 (95% confidence interval, 4.5 to 82.2; p=0.001) to 10.4 (95% confidence interval, 1.3 to 81.9; p=0.03). Reduced visual resolution acuity in VLBW infants appears to be due to cerebral white matter damage.

Cerebral Cortex↗

PubMed2000

Undernutrition in relation to childhood infections: a prospective study in the Sudan.

OBJECTIVE: The aim of the study was to examine the relationships between nutritional status and diarrhoea and respiratory infections. DESIGN: Prospective cohort study within the framework of a randomized double-blind placebo-controlled intervention trial. SETTING: In rural communities in the Khartoum and Gezira regions, in Northern Sudan. SUBJECTS: 28,753 Sudanese pre-school children between 6 months and 6 y old. METHODS: Relative risks of subsequent diarrhoea and respiratory infections in relation to nutritional status measured by anthropometry (Z-scores of height-for-age (H/A), weight-for-height (W/H), and weight-for-age (W/A), which reflect stunting, wasting and underweight, respectively) were estimated using odds ratios from logistic regression adjusting for various covariates. RESULTS: H/A, W/H and W/A were significantly and inversely associated with subsequent diarrhoea and febrile diarrhoea (P for trend <0.001) with risks being 2.00 times higher (95% confidence interval, CI (1.64, 2.43)) among children with W/A Z-scores below -4 Z, and 1.75 times higher (95% CI (1.56, 1.96)) among those with a W/A Z-score between -4 and -3 Z compared with children having a W/A Z-score > or =1. Age, gender, region of residence and seasonality modified these associations. Also, febrile cough was inversely associated with W/A and W/H (P<0.03), with risks ranging from 1.41 times higher (95% CI (1.02, 1.97)) to 1.21 times higher (95% CI (1.04, 1.41)) in the group of underweight children with W/A Z-scores below -4 and between -2 and -1 Z, all compared with normally nourished children (> or =-1 Z). CONCLUSIONS: The reduction of severe but also mild and moderate undernutrition is necessary through nutrition, health and socio-economic improvement in order to prevent morbidity.

Body Weight↗

PubMed2000

Undernutrition and childhood infections: a prospective study of childhood infections in relation to growth in the Sudan.

UNLABELLED: The relationships between both diarrhoea and respiratory infections and linear and ponderal growth were prospectively examined among 28 753 Sudanese pre-school children. Childhood infections were significantly and inversely associated with attained height and attained weight and gain in height and weight over a 6-mo period. They were significantly and positively associated also with stunting after adjusting for age, gender, socio-economic status, dietary variables and previous morbidity. Attained height was on average 17 mm lower (95% CI [-19 -15]) for children with diarrhoea and 11 mm lower (95% CI [-3 -9]) for children with complicated cough than for those without these symptoms. The association between morbidity and attained weight was significant for diarrhoea and complicated cough, but the differences between children with and without symptoms were negligible. The risk of being stunted 6 mo later was 1.38 times (95% CI [1.20 1.59]), 1.29 times (95% CI [0.97 1.72]) and 1.32 times (95% CI [1.13 1.54]) greater among normally-nourished children with diarrhoea, febrile diarrhoea and fever, respectively, than among children without these symptoms. The difference in attained height between children with diarrhoea or complicated cough and those without symptoms increased with age, and was larger among the non-breastfed children compared with breastfed children. CONCLUSION: The results underline the need to reduce child morbidity to prevent the impairment of growth and development.

Child↗

PubMed2000

Dietary vitamin A intake and nondietary factors are associated with reversal of stunting in children.

We examined prospectively the associations between dietary vitamin A intake, nondietary factors and growth in 8174 Sudanese children ages 6-72 mo who were stunted at the start of follow-up. All subjects were weighed and measured at baseline and at 6-mo intervals for 18 mo of follow-up. Dietary vitamin A intake during the prior 24 h was assessed using recall of vitamin A-containing foods at baseline and 6-mo intervals. We examined the association of dietary vitamin A intake with growth and the incidence of recovery of stunting after controlling for age, sex, breast-feeding status and socioeconomic variables. We found that carotenoid intake was associated with a greater incidence of reversal of stunting. Children in the highest quintile grew 13 mm more during the study period than children in the lowest quintile [95% confidence interval (CI): 0-25 mm] in multivariate analyses. The relative risk (RR) of recovery associated with vitamin A intake was greater in infants up to 1 y old (RR = 3.3, CI: 0.9-11.7) than in children > or =3 y of age (RR = 1.0, CI: 0.8-1. 3) (P:-value for interaction = 0.08). Diets rich in carotenoids may increase the rate of recovery from stunting in children. Dietary effects on growth might be strongest among very young children and those who have been most malnourished. Age, sex, breast-feeding status, socioeconomic status and severity of baseline stunting also were associated with reversal of stunting in this population.

Analysis of Variance↗

PubMed2000

Tomato intake in relation to mortality and morbidity among Sudanese children.

The intake of foods that contain high levels of antioxidants may counteract the adverse effects of oxidative stress and lead to improved immune function and reduced risk of infectious disease. We prospectively examined the relationship between the consumption of tomatoes, a rich source of antioxidants, and mortality and diarrheal and respiratory morbidity rates among 28,753 children who were 6-60 mo old and enrolled in a longitudinal study in the Sudan. Children in each household were visited every 6 mo for a maximum of four visits. At each round, mothers recalled whether a child had consumed tomatoes in the previous 24 h. Events (death or morbidity) reported at each round were prospectively allocated according to the number of days of tomato intake. Intake of tomatoes for 2 or 3 d compared with none was associated, respectively, with 48% (relative risk, 0. 53; 95% confidence interval, 0.30-0.91) and 83% (0.17; 0.04-0.72) reductions in morality rates (P: for trend = 0.002). The association between tomato use and death remained statistically significant (P: for trend = 0.004), even after further adjustment for total vitamin A intake. Tomato intake was also associated with a reduced risk of death associated with diarrhea in the week preceding death (P: for trend = 0.009) or fever (P: for trend = 0.04). Intake of tomatoes was also inversely and significantly associated with the risks of diarrheal and respiratory infections. Our data suggest that tomatoes may be beneficial for child health but also emphasize the general importance of food-based approaches to the prevention of micronutrient malnutrition and protection of the health of children in developing countries.

Antioxidants↗

PubMed1999

A randomized trial of vitamin A supplements in relation to mortality among human immunodeficiency virus-infected and uninfected children in Tanzania.

OBJECTIVES: To determine whether vitamin A supplements result in reduced mortality among HIV-infected and uninfected children. DESIGN: Randomized, double blind, placebo-controlled trial. METHODS: Starting in April, 1993, we randomized 687 children age 6 months to 5 years who were admitted to the hospital with pneumonia. Children who were severely malnourished or had clinical signs of vitamin A deficiency were excluded. At baseline children received placebo or 400 000 IU (or half that for infants) of vitamin A, in addition to standard treatment for pneumonia. They received further doses of the same regimen 4 and 8 months after hospital discharge. Sera from children were tested for HIV antibodies by enzyme-linked immunosorbent assay and Western blot tests. For positive children <15 months of age, HIV infection was confirmed by amplified heat-denatured HIV-p24 antigen assays with confirmatory neutralization assays. HIV status was ascertained for 648 of 687 enrolled children. The mean duration of follow-up was 24.4 months (SD = 12.1). RESULTS: Of 648 children 58 (9%) were HIV-infected. Compared with uninfected children, all-cause mortality was higher among HIV-infected children, as was mortality caused by pneumonia or diarrhea (P < 0.001 for each). Overall vitamin A supplements resulted in a 49% reduction in mortality [relative risk (RR), 0.51; 95% confidence interval (CI), 0.29 to 0.90, P = 0.02]. Vitamin A supplements reduced all-cause mortality by 63% among HIV-infected children (RR 0.37; CI 0.14 to 0.95, P = 0.04) and by 42% among uninfected children (RR 0.58, CI 0.28 to 1.19, P = 0.14). Vitamin A supplements were also associated with a 68% reduction in AIDS-related deaths (P = 0.05) and a 92% reduction in diarrhea-related deaths (P = 0.01). CONCLUSION: Vitamin A deficiency, which is common among children in many developing countries, is particularly severe among HIV-infected children. Our findings indicate that vitamin A supplements, a low cost intervention, reduce mortality of HIV-infected children.

Child, Preschool↗

PubMed1998

Vitamin A supplementation and severity of pneumonia in children admitted to the hospital in Dar es Salaam, Tanzania.

Vitamin A deficiency and acute lower respiratory tract infections coexist as important public health problems in many developing countries. We carried out a randomized, double-blind, placebo-controlled trial to examine whether large doses of vitamin A given to Tanzanian children who are admitted to the hospital with nonmeasles pneumonia would reduce the severity of respiratory disease. Six hundred eighty-seven children were randomly assigned to receive either placebo or vitamin A [200 000 IU (60 mg retinol equivalents) for children > 1 y of age and 100000 IU (30 mg retinol equivalents) for infants] on the day of admission and another dose on the following day. Of the 346 children in the vitamin A group, 13 died in the hospital, compared with 8 of 341 children in the placebo group; the relative mortality was 1.63 (95% CI: 0.67, 3.97; P = 0.28). The mean number of days of hospitalization was the same in both groups (4.2 d). There were no differences between the vitamin A and placebo groups in the duration of hospital stay when examined within categories of children stratified by age, sex, breast-feeding status, nutritional status at baseline, or quartile of dietary vitamin A intake in the 4 mo before admission to the hospital. There were also no differences in the mean number of days of fever, rapid respiratory rate, or hypoxia, whether these endpoints were examined in the total number of subjects or in a subset with more severe clinical conditions at baseline. Large doses of vitamin A had no protective effect on the course of pneumonia in hospitalized Tanzanian children.

Body Temperature↗

PubMed1998

A longitudinal study of prolonged breastfeeding in relation to child undernutrition.

BACKGROUND: In a number of studies prolonged breastfeeding was associated with a higher risk of undernutrition, although most of these studies are limited by their cross-sectional design which does not allow examination of temporal relationships between full weaning and undernutrition. METHODS: The relationship between prolonged breastfeeding and child growth was examined prospectively among children under 36 months old who participated in a large cohort study. At baseline and at each of three 6-monthly follow-up visits breastfeeding status was assessed and all subjects were weighed and measured. RESULTS: Undernourished children were more likely to be breastfed for a longer period of time compared with normal children. We found a small difference between breastfed and fully weaned children in the gain in height over the following 6-month period; however, breastfed children were likely to gain significantly less weight, particularly among children who were aged 6-12 months. Similar findings were noted when these associations were examined among children who were normally nourished at the time of breastfeeding assessment. The inverse association between breastfeeding status and weight gain was significantly larger among children of poor or illiterate mothers compared with children of relatively more affluent or literate mothers, respectively. CONCLUSIONS: Our findings suggest that the inverse association is not causal, and may be explained by poorer complementary feeding among breastfed compared with weaned children. Children from poorer households and whose parents are illiterate are more likely to have less than adequate complementary feeding. The importance of adequate complementary feeding in the second half of infancy needs to be stressed in nutrition education programmes.

Body Height↗

PubMed1997

A prospective study of malnutrition in relation to child mortality in the Sudan.

We examined prospectively the relation between malnutrition and mortality among Sudanese children. A cohort of 28753 children between the ages of 6 mo and 6 y was examined every 6 mo for 18 mo. Two hundred thirty-two children died during 18 mo of follow-up (480624 child-months). Low weight-for-height was associated with an increased risk of mortality (P < 0.0001). Even children with Z scores between -1 and -2 were 50% more likely to die in the following 6 mo than were children with Z scores > -1 (multivariate relative mortality: 1.5; 95% CI: 1.1, 2.2). There was also an inverse relation between height-for-age and mortality (P < 0.0001). Among breast-fed children, the relative mortality associated with a Z score for weight-for-height of < -3 compared with > -2 was 7.3 (95% CI: 3.3, 15.9); among children not breast-fed, it was 26.0 (95% CI: 12.8, 53.0; P for interaction = 0.001). A strong and significant synergy was also found between infection and wasting or stunting as predictors of child mortality (P for interaction = 0.001 and 0.02. respectively). In developing countries, children who are below the customary cutoff point of -2 Z for weight-for-height may be at higher risk of death. Breast-feeding and reduction of morbidity should be advocated in programs designed to reduce malnutrition and mortality among children.

Aging↗

PubMed1997

Dietary vitamin A intake in relation to child growth.

Severe deficits in ponderal and linear growth are problems of major public health significance among children in developing countries. We prospectively examined the association of dietary vitamin A intake with child growth among 28,740 Sudanese children ages 6-72 months. At baseline and at each 6-month visit, all subjects were weighed and measured. Dietary vitamin A intake during the prior 24 hours was assessed using recall of vitamin A-containing foods. Dietary vitamin A intake was associated with attained height and weight after controlling for age, sex, morbidity, and socioeconomic variables. Compared with children in the bottom quintile of intake, those in the top quintile were 11 mm taller [95% confidence interval (CI) = 8-13] and 237 gm heavier (95% CI = 153-320). Higher dietary vitamin A intake was also associated with reduced risk of stunting [relative risk (RR) for 5th vs 1st quintile = 0.7; 95% CI = 0.5-0.9] and wasting (RR = 0.7; 95% CI = 0.5-0.9). Adequate intake of foods containing vitamin A may improve child growth where vitamin A deficiency prevails, but this relation may not be due to vitamin A per se.

Body Height↗

PubMed1997

The effect of vitamin A supplementation on the growth of preschool children in the Sudan.

OBJECTIVES: This study assessed the effect of vitamin A supplementation at 6-month intervals on child growth. METHODS: Sudanese children (n = 28,740) 6 to 72 months of age were weighed and measured at baseline and at each of three follow-up visits. RESULTS: Periodic vitamin A supplementation had no effect on the rate of weight or height gain in the total population or on the incidence of wasting, stunting, or wasting and stunting among children who were normally nourished at baseline. CONCLUSIONS: Reducing poverty and improving access to adequate diets should remain the goals of programs designed to improve the nutritional status of malnourished populations.

Body Height↗

PubMed1997

Risk factors of low dietary vitamin A intake among children in the Sudan.

We examined the determinants of dietary vitamin A intake among Sudanese children, information which is important for designing effective interventions based on the dietary approach. Children under the age of two years were at greater risk of consuming a diet low in vitamin A compared with children who were five years or older. Compared with children from relatively affluent households, those from poorer households were about twice as likely to consume low levels of carotenoid or preformed vitamin A. Low vitamin A intake was also significantly associated with lack of running water, a latrine, radio, or television in the household, and inversely associated with maternal or paternal illiteracy and with cleanliness of the child subjectively assessed by the interviewer. As expected, breastfed children in the first two years of life were likely to consume lower levels of preformed vitamin A and carotenoid from food (excluding breast milk) compared with non-breastfed children. Low vitamin A intake was more prevalent in the dry months of the year. Efforts to increase accessibility to vitamin A containing food, combined with nutrition education campaigns and public health programmes directed at improving sanitation and reducing infection are necessary as part of the long-term solution to the problem of vitamin A deficiency.

Age Factors↗

PubMed1995

Dietary vitamin A intake and the incidence of diarrhea and respiratory infection among Sudanese children.

The relationship of vitamin A deficiency and child survival has been documented in a number of studies but not in others, yet the relationship of vitamin A with child morbidity remains controversial. We prospectively examined the relationship of dietary vitamin A intake and the incidences of diarrhea and respiratory infection among 28,753 Sudanese children between the ages of 6 mo and 6 y. Total dietary vitamin A intake was strongly and inversely associated with the risk of diarrhea (multivariate risk in top relative to bottom quintile = 0.58, 95% confidence interval = 0.47-0.72); we also observed a strong inverse association with the risk of having cough and fever (0.60, 0.45-0.81). On the other hand, we noted a significantly positive association of dietary vitamin A intake and incidence of cough alone (1.69, 1.52-1.88), a sign that may be assocsated with a healthy respiratory epithelium. Vitamin A intake was also negatively associated with the risk of measles. These prospective data emphasize the importance of adequate dietary vitamin A intake to protect the health of children in developing countries.

Child↗

PubMed1994

Dietary vitamin A intake and the risk of mortality among children.

Increased consumption of dietary vitamin A is advocated as a long-term solution to vitamin A deficiency. We prospectively examined the relationship of dietary vitamin A intake and child mortality among 28,753 Sudanese children aged 6 mo to 6 y, who participated in a trial of vitamin A supplementation. After 18 mo of follow-up, 232 children died. Total dietary vitamin A intake was strongly and inversely associated with risk of mortality. The age- and sex-adjusted relative risk (RR) of mortality for a comparison of children in extreme quintiles was 0.35 (95% CIs 0.21-0.60; P for trend over quintiles < 0.0001). Even after possible confounding by socioeconomic variables was adjusted for, vitamin A intake was significantly protective (multi-variate relative risk 0.53). Dietary vitamin A intake was especially protective among children who were wasted and stunted or who had diarrhea or cough. These prospective data support an important role of dietary vitamin A in reducing childhood mortality in developing countries.

Age Factors↗

PubMed1994

Child nutrition and armed conflicts in Iraq.

The object of the study was to assess the nutritional status of children 0-5 years, who were attending maternal and child health clinics in Basrah city, 6 months after the cessation of the Gulf War, and took the form of a cross-sectional study. The study population consisted of 723 children, the majority of whom were between 0 and 36 months of age, attending maternal and child health clinics (MCHC) in Basrah city for routine immunizations. Each MCHC was visited on a separate day and all children attending on that day were included in the study. A proportion (8 per cent) of the study population were wasted, most of them in the 12-24-month age category. Twenty-four per cent of the children were stunted. Stunting and low weight-for-age were significantly higher among children of low socio-economic households. Comparison of these data with an earlier nutritional survey in the area showed that the nutritional status of children in Basrah city has deteriorated as a result of successive armed conflicts. There is need to monitor the health and nutritional status of children, and take appropriate action in order to protect them.

Anthropometry↗

PubMed1993

Vitamin A supplementation and child mortality. A meta-analysis.

OBJECTIVE: A two-part meta-analysis of studies examining the relationship of vitamin A supplementation and child mortality. DATA SOURCES: We identified studies by searching the MEDLARS database from 1966 through 1992 and by scanning Current Contents and bibliographies of pertinent articles. STUDY SELECTION: All 12 vitamin A controlled trials with data on mortality identified in the search were used in the analysis. DATA EXTRACTION: Data were independently extracted by two investigators who also assessed the quality of each study using a previously described method. DATA SYNTHESIS: We formally tested for heterogeneity across studies. We pooled studies using the Mantel-Haenszel and the DerSimonian and Laird methods and adjusted for the effect of cluster assignment of treatment groups in community-based studies. Vitamin A supplementation to hospitalized measles patients was highly protective against mortality (DerSimonian and Laird odds ratio, 0.39; 95% confidence interval, 0.22 to 0.66; P = .0004) (part 1 of the meta-analysis). Supplementation was also protective against overall mortality in community-based studies (DerSimonian and Laird odds ratio, 0.70; clustering-adjusted 95% confidence interval, 0.56 to 0.87; P = .001) (part 2 of the meta-analysis). CONCLUSIONS: Vitamin A supplements are associated with a significant reduction in mortality when given periodically to children at the community level. Factors that affect the bioavailability of large doses of Vitamin A need to be studied further. Vitamin A supplements should be given to all measles patients in developing countries whether or not they have symptoms of vitamin A deficiency.

Child↗