Biomedical subjects

R D Semba

Publications and source records attributed to R D Semba.

At least 19 recordsLinked to original sources

PubMed2006

Effect of antibiotic treatment of subclinical mastitis on human immunodeficiency virus type 1 RNA in human milk.

Although subclinical mastitis is associated with increased HIV load in breast milk, it is not known whether empirical treatment with antibiotics will reduce breast milk HIV load. We examined the effect of antibiotic treatment for subclinical mastitis on HIV load in breast milk. Seventy-five HIV-infected post-partum women in Malawi with subclinical mastitis were treated with oral amoxicillin/clavulanic acid and were followed between 1 and 24 weeks later. Breastmilk HIV-1 load and sodium concentration were measured and microbiological studies were performed at presentation. At 1 week (n = 34), the proportion of women with elevated breast milk leukocyte counts decreased significantly to 41.2% (p < 0.0001) and there was a nonsignificant increase in breast milk HIV-1 RNA load (p = 0.9264) and sodium concentration (p = 0.08) in the affected breast. At 4 to 12 weeks (n = 63), breast milk HIV-1 RNA load and sodium concentration decreased significantly (p < 0.05) and 17.5% had elevated breast milk leukocyte counts. Treatment with amoxicillin/clavulanic acid was associated with a significant decrease in inflammation of the breast, but breast milk HIV load remained elevated despite a significant decrease from baseline. These findings have important implications regarding how mothers should be counselled on safety of resuming breastfeeding after resolution of subclinical mastitis.

Amoxicillin↗

PubMed2006

Physical activity in a cohort of HIV-positive and HIV-negative injection drug users.

Physical activity is beneficial for persons with HIV infection but little is known about the relationships between physical activity, HIV treatment and injection drug use (IDU). This study compared physical activity levels between HIV-negative and HIV-positive injection drug users (IDUs) and between HIV-positive participants not on any treatment and participants on highly active antiretroviral therapy (HAART). Anthropometric measurements were obtained and an interviewer-administered modified Paffenbarger physical activity questionnaire was administered to 324 participants in a sub-study of the AIDS Linked to Intravenous Experiences (ALIVE) cohort, an ongoing study of HIV-negative and HIV-positive IDUs. Generalized linear models were used to obtain univariate means and to adjust for confounding (age, gender, employment and recent IDU). Vigorous activity was lower among HAART participants than HIV-positive participants not on treatment (p=0.0025) and somewhat lower than HIV-negative participants (p=0.11). Injection drug use and viral load were not associated with vigorous activity. Energy expenditure in vigorous activity was also lower among HAART participants than both HIV-negative and HIV-positive participants not on treatment. Thus, HIV-positive participants on HAART spend less time on vigorous activity independent of recent IDU. More research is needed into the reasons and mechanism for the lack of vigorous activities, including behavioral, psychological and physiological reasons.

Adult↗

PubMed2005

Serum antioxidants, inflammation, and total mortality in older women.

The inflammatory cytokine interleukin-6 (IL-6) has been linked to poor health outcomes in older adults. Oxidative stress triggers the production of IL-6, and antioxidant micronutrients play a critical role in decreasing this inflammatory response. The authors sought to identify the relations between serum levels of antioxidant nutrients and IL-6 and mortality in older women. Levels of alpha- and beta-carotene, lycopene, lutein/zeaxanthin, alpha-cryptoxanthin, total carotenoids, retinol, alpha-tocopherol, zinc, and selenium were measured at baseline in 619 participants in Women's Health and Aging Study I (Baltimore, Maryland, 1992-1998). IL-6 was measured at baseline and at follow-up 1 and 2 years later, and all-cause mortality was determined over a 5-year period. Participants with the highest serum levels of alpha-carotene, total carotenoids, and selenium were significantly less likely to be in the highest tertile of serum IL-6 at baseline (p < 0.0001). Those with the lowest levels of alpha- and beta-carotene, lutein/zeaxanthin, and total carotenoids were significantly more likely to have increasing IL-6 levels over a period of 2 years. Those with the lowest selenium levels had a significantly higher risk of total mortality over a period of 5 years (hazard ratio = 1.54, 95% confidence interval: 1.03, 2.32). These findings suggest that specific antioxidant nutrients may play an important role in suppressing IL-6 levels in disabled older women.

Aged↗

PubMed2005

Low plasma selenium concentrations, high plasma human immunodeficiency virus load and high interleukin-6 concentrations are risk factors associated with anemia in adults presenting with pulmonary tuberculosis in Zomba district, Malawi.

BACKGROUND: Although anemia is common among adults with pulmonary tuberculosis and human immunodeficiency virus (HIV) infection in sub-Saharan Africa, the factors contributing to its pathogenesis have not been well characterized. OBJECTIVE: To characterize the antioxidant micronutrient status, interleukin-6 (IL-6) concentrations, and HIV load in relationship with anemia in adults with pulmonary tuberculosis. SETTING: Zomba district, Malawi. METHODS: Erythropoietin, IL-6, plasma HIV load, and markers of micronutrient status (hemoglobin (Hb), plasma concentrations of retinol, alpha-tocopherol, carotenoids, ferritin, zinc, and selenium) were measured in 500 adults who presented with pulmonary tuberculosis in Zomba Central Hospital, Malawi. RESULTS: Among 370 HIV-positive and 130 HIV-negative adults, the prevalence of anemia was 88 and 77%, respectively (P = 0.002), and moderate to severe anemia (Hb < 80 g/l) occurred in 30 and 15%, respectively (P = 0.001). Geometric mean IL-6 concentration was 21.1 pg/ml, with no difference between HIV-positive and -negative adults. The erythropoietin response to anemia was not different between adults with elevated IL-6 and those with lower IL-6 concentrations. In a multivariate logistic regression model, HIV load, and lower plasma selenium concentrations were associated with moderate to severe anemia. In a final multivariate linear regression model, IL-6, plasma HIV load, and plasma selenium concentrations were associated with Hb concentrations. CONCLUSION: This study suggests that low selenium concentrations, high HIV load, and high IL-6 concentrations are associated with anemia in adults with pulmonary tuberculosis in sub-Saharan Africa.

Adult↗

PubMed2005

Epidemiology and microbiology of subclinical mastitis among HIV-infected women in Malawi.

The epidemiology and microbiology of subclinical mastitis, a risk factor for perinatal HIV transmission, have not been well characterized. In all, 250 HIV-infected women were followed from two weeks to 12 months postpartum in Blantyre, Malawi, and subclinical mastitis was assessed by breast milk leukocyte counts. The point prevalence of subclinical mastitis at 2, 4, 6, 10, and 14 weeks, and 6, 9, and 12 months was 12.2%, 7.8%, 6.8%, 3.7%, 10.6%, 5.1%, 4.9%, and 1.9%, respectively (P = 0.002), and 27.2% of women had at least one episode of subclinical mastitis. There was no significant relationship between maternal plasma HIV load or parity and subclinical mastitis. Staphylococcus aureus was isolated in 30% of women with subclinical mastitis, and the proportion of women with positive cultures decreased during follow-up (P = 0.02). Subclinical mastitis is prevalent among breastfeeding mothers and further studies are needed to characterize the differences between infectious and non-infectious subclinical mastitis.

Adult↗

PubMed2004

Relationship of vitamin A deficiency, iron deficiency, and inflammation to anemia among preschool children in the Republic of the Marshall Islands.

INTRODUCTION: Although vitamin A deficiency, iron deficiency, and inflammation may contribute to anemia, their relative contribution to anemia has not been well characterized in preschool children in developing countries. OBJECTIVE: To characterize the contributions of vitamin A and iron deficiencies and inflammation to anemia among preschool children in the Republic of the Marshall Islands. SUBJECTS AND METHODS: A community-based survey, the Republic of the Marshall Islands Vitamin A Deficiency Study, was conducted among 919 preschool children. The relationship of vitamin A and iron status and markers of inflammation, tumor necrosis factor-alpha, alpha1-acid glycoprotein, and interleukin-10, to anemia were studied in a subsample of 367 children. RESULTS: Among the 367 children, the prevalence of anemia was 42.5%. The prevalence of severe vitamin A deficiency (serum vitamin A < 0.35 micromol/l) and iron deficiency (serum ferritin < 12 microg/dl) were 10.9 and 51.7%, respectively. The respective prevalence of iron deficiency anemia (hemoglobin < 110 g/l and iron deficiency), anemia with inflammation (anemia with TNF-alpha > 2 pg/ml and/or AGP > 1000 mg/l), and severe vitamin A deficiency combined with anemia was 26.7, 35.6, and 7.6%. In multivariate linear regression models that adjusted for age, sex, and inflammation, both iron deficiency (odds ratio (OR) 1.74, 95% confidence interval (CI) 1.08-2.83, P = 0.023) and severe vitamin A deficiency (OR 4.85, 95% CI 2.14-10.9, P < 0.0001) were significantly associated with anemia. CONCLUSIONS: Both iron and vitamin A deficiencies were independent risk factors for anemia, but inflammation was not a significant risk factor for anemia among these preschool children.

Anemia↗

PubMed2004

Malnutrition and the severity of lung disease in adults with pulmonary tuberculosis in Malawi.

SETTING: Zomba Central Hospital, Zomba, Malawi. OBJECTIVE: To examine the relationship between malnutrition and the severity of lung disease in human immunodeficiency virus (HIV) positive and negative adults with pulmonary tuberculosis (PTB). DESIGN: Cross-sectional study. METHODS: Chest radiographs and anthropometric measurements were obtained and bioelectrical impedance analysis was conducted in sputum-positive patients with pulmonary tuberculosis. Lung disease in chest radiographs was graded as normal, minimal, moderately advanced and far advanced according to a conventional classification system. RESULTS: Among 319 adults with PTB with or without HIV co-infection, body mass index (BMI), fat mass and phase angle were independently associated with increasing severity of lung disease. Multiple logistic regression analyses showed that BMI, fat mass and phase angle were associated with increasing severity of lung disease among 236 HIV-positive adults, when adjusted for sex, age, and plasma HIV load. CONCLUSION: The severity of lung disease in adults with PTB is associated with the extent of malnutrition, as reflected by BMI and body composition studies using bioelectrical impedance analysis.

Adult↗

PubMed2004

Long-term outcome in patients registered with tuberculosis in Zomba, Malawi: mortality at 7 years according to initial HIV status and type of TB.

SETTING: Zomba Central Hospital, Malawi. OBJECTIVES: To determine the outcome of all adult patients who were registered for tuberculosis (TB) treatment 7 years previously according to initial human immunodeficiency virus (HIV) status and type of TB. DESIGN: A retrospective cohort study of adult patients registered for TB treatment between July and December 1995. Follow-up at patients' homes was performed at the end of treatment, at 32 months and at 84 months (7 years) from the time of TB registration. FINDINGS: Eight hundred and twenty-seven TB patients were registered: 793 had concordant HIV test results, of whom 612 (77%) were HIV-positive. At 7 years, 136 (17%) patients were alive, 539 (65%) had died and 152 (18%) were lost to follow-up. The death rate for all TB patients was 23.7 per 100 person-years of observation. HIV-positive patients had higher death rates than HIV-negative patients (hazard ratio [HR] 2.2, 95% confidence interval [95%CI] 1.7-2.8). Death rates in smear-negative pulmonary TB patients (HR 2.1, 95%CI 1.7-2.6) and in patients with extra-pulmonary TB (HR 1.7, 95% CI 1.3-2.0) were higher than in patients with smear-positive PTB. CONCLUSIONS: There was a high mortality rate in TB patients during and after anti-tuberculosis treatment. Adjunctive treatments to reduce death rates are urgently needed.

Adult↗

PubMed2003

Are lutein and zeaxanthin conditionally essential nutrients for eye health?

The carotenoids lutein and zeaxanthin are found in the macula in high concentrations and may play a role in the pathogenesis of age-related macular degeneration (ARMD). Lutein and zeaxanthin may protect the macula and photoreceptor outer segments throughout the retina from oxidative stress and play a role in an antioxidant cascade that safely disarms the energy of reactive oxygen species. Although lutein and zeaxanthin are not essential nutrients, studies are beginning to suggest that they fit the criteria for conditionally essential nutrients. Low plasma lutein and zeaxanthin concentrations or dietary intake are associated with low macular pigment density and increased risk of ARMD. Dietary deprivation of lutein and zeaxanthin in primates causes pathological changes in the macula. Should controlled clinical trials show lutein and/or zeaxanthin supplementation protects against the development or progression of ARMD and other eye diseases, then lutein and zeaxanthin could be considered as conditionally essential nutrients for humans.

Aging↗

PubMed2003

Risk factors for nightblindness among women of childbearing age in Cambodia.

OBJECTIVE: To characterize risk factors for nightblindness among nonpregnant women of childbearing age, a group recently recognized to be at high risk of vitamin A deficiency in some developing countries. DESIGN: Case-control study. SETTING: The study included >15 000 households in National Micronutrient Survey of Cambodia conducted in 2000. SUBJECTS: The prevalence of nightblindness among 13 358 nonpregnant women was 2.0%. A total of 328 nonpregnant women with nightblindness were matched by province with 1009 nonpregnant women without nightblindness. METHODS: Univariate and multivariate logistic regression models were used to estimate odds ratios (ORs) as estimates of the relative risk of factors associated with nightblindness. RESULTS: In a final model, materials in the wall of the house (OR 1.4, 95% confidence interval (CI) 0.9-2.0), land ownership < or =0.5 hectares (OR 1.4, 95% CI 1.0-1.9), nightblindness in last pregnancy (OR 44.5, 95% CI 29.2-67.8), parity >3 (OR 1.5, 95% CI 1.0-2.1), diarrhea within the last 2 weeks (OR 1.9, 95% CI 1.3-2.8), maternal body mass index <18.5 (OR 1.8, 95% CI 1.2-2.7), and lack of consumption of vitamin A-rich animal foods in the last 24 h (1-60 retinol equivalents (RE) OR 1.1, 95% CI 0.7-1.6; > or =60 RE, OR 0.7, 95% CI 0.4-1.0) were associated with nightblindness among nonpregnant women. CONCLUSIONS: Women of childbearing age in Cambodia with low socioeconomic status, low consumption of vitamin A-rich animal foods, a history of nightblindness during the previous pregnancy, parity >3, malnutrition, and diarrhea have a higher risk of nightblindness. SPONSORSHIP: United States Agency for International Development (442-G-00-95-00515-00).

Adolescent↗

PubMed2002

The anemia of vitamin A deficiency: epidemiology and pathogenesis.

OBJECTIVE: To gain insight into vitamin A deficiency as a cause of anemia. METHODS: Comprehensive review of the scientific literature. RESULTS: Although vitamin A deficiency is recognized to cause anemia, 'vitamin A deficiency anemia' lacks complete characterization as a distinct clinical entity. Vitamin A appears to be involved in the pathogenesis of anemia through diverse biological mechanisms, such as the enhancement of growth and differentiation of erythrocyte progenitor cells, potentiation of immunity to infection and reduction of the anemia of infection, and mobilization of iron stores from tissues. Epidemiological surveys show that the prevalence of anemia is high in populations affected by vitamin A deficiency in developing countries. Improvement of vitamin A status has generally been shown to reduce anemia, but the actual public health impact on anemia is unclear. CONCLUSIONS: Further work is needed to elucidate the biological mechanisms by which vitamin A causes anemia. The inclusion of anemia as an outcome measure in future micronutrient intervention studies should help provide further insight into the anemia of vitamin A deficiency.

Adolescent↗

PubMed2002

Assessment of vitamin A status of preschool children in Indonesia using plasma retinol-binding protein.

Although plasma retinol-binding protein (RBP) has been proposed as an indicator of vitamin A status of populations in less technologically developed settings, potential factors which could influence this indicator include inflammation and protein energy status. Plasma RBP, retinol, alpha1-acid glycoprotein (AGP), C-reactive protein (CRP), and albumin were measured in a study of 236 preschool children in Bandung, Indonesia. Spearman correlation coefficient between plasma RBP and retinol concentrations was 0.55 (p < 0.0001). By linear regression, 0.70 pmol/l retinol was equivalent to 0.69 micromol/l RBP. With these cut-off points for defining vitamin A deficiency and plasma retinol as the standard for comparison, RBP had a sensitivity and specificity of 75.0 per cent and 63.2 per cent, respectively. The correlation between RBP and retinol was not affected by plasma AGP, CRP, or albumin concentration. Measurement of plasma RBP by radial immunodiffusion is simple and inexpensive, and this test can be used as a simple surrogate measure for vitamin A concentrations in large field studies.

Biomarkers↗

PubMed2002

Risk factors and cumulative incidence of anaemia among human immunodeficiency virus-infected children in Uganda.

Anaemia has not been well characterised among HIV-infected children in sub-Saharan Africa. Baseline prevalence and cumulative incidence of anaemia (haemoglobin < 110 g/L) were 91.7% and 100% and, for moderate anaemia (haemoglobin < 90 g/L), were 35.1% and 58.4%, respectively, among 225 HIV-infected children followed from 9 to 36 months of age. Hospitalisation, suspected tuberculosis, malaria and height-for-age Z-score <-2 were significantly associated with moderate anaemia. Moderate anaemia and weight-for-height Z-score <-2 were associated with mortality. Anaemia is common and associated with increased mortality in HIV-infected children.

AIDS-Related Opportunistic Infections↗

PubMed2001

Iron status and indicators of human immunodeficiency virus disease severity among pregnant women in Malawi.

The relationships among hemoglobin, ferritin, and transferrin receptor levels and 2 markers of human immunodeficiency virus (HIV) disease severity--HIV load and CD4(+) lymphocyte count--were characterized among 483 pregnant women in Malawi, Africa. The only significant correlation was an inverse correlation between hemoglobin level and plasma HIV load (r=-.104; P<.03). The prevalence of iron deficiency anemia was not significantly different across quartiles of HIV load or CD4(+) lymphocyte count. In contrast to previous studies, these data suggest that iron status is not related to markers of HIV disease severity in pregnant women in Africa.

Anemia, Iron-Deficiency↗

PubMed2001

Improvement of anemia among HIV-infected injection drug users receiving highly active antiretroviral therapy.

Although anemia is common during HIV infection, it is unclear whether potent antiretroviral therapy would improve or worsen anemia. We conducted a study to examine the impact of highly active antiretroviral therapy (HAART) on anemia in a cohort of HIV-positive injection drug users (IDUs) in Baltimore, Maryland. At baseline, the overall prevalence of anemia was 40%. During mean follow-up of one year, among 102 subjects who received HAART, there was a mean increase in hemoglobin of 3.6 +/- 1.7 g/L (p =.0003) [corrected] and a mean decrease in log(10) plasma HIV load of 0.25 +/- 0.06 copies/ml (p <.0002) [corrected]. Among 103 control subjects who were not receiving antiretroviral medications, there was a mean decrease in hemoglobin of 4.2 +/- 1.1 g/L (p <.04) [corrected] and mean increase in log(10) plasma HIV load of 0.78 +/- 0.17 copies/ml (p <.0001) [corrected]. Multivariate analysis using mixed linear models showed that HAART was associated with an increase of hemoglobin of 0.223 g/L per month (p <.0001) after adjusting for body mass index, opportunistic infections, and gender. HAART was associated with an improvement in anemia, and potential mechanisms that may be involved include a reduction in opportunistic infections and the anemia of chronic disease and an improvement in nutritional status.

AIDS-Related Opportunistic Infections↗

PubMed2001

Low carotenoid concentration and the risk of HIV seroconversion in Pune, India.

Low vitamin A and carotenoid levels could increase the risk of sexual HIV acquisition by altering the integrity of the genital epithelium or by immunologic dysfunction. We addressed this issue by measuring serum vitamin A and carotenoid levels in patients who were at risk of subsequent HIV infection. In a nested case-control study in individuals attending two sexually transmitted disease (STD) clinics in Pune, India, serum micronutrient levels were measured in 44 cases with documented HIV seroconversion (11 women and 33 men) and in STD patients matched for gender and length of follow-up with no subsequent HIV seroconversion (controls). STD patients in Pune had low vitamin A and carotenoid levels, and low serum beta-carotene levels were independently associated with an increased risk of subsequent HIV seroconversion. STD patients with beta-carotene levels less than 0.075 micromol/L were 21 times more likely to acquire HIV infection than those with higher levels (adjusted odds ratio = 21.1; p =.01). No such association was observed in case of other non-provitamin A carotenoids. This study reports the first evidence of an association between low serum provitamin A carotenoid levels and an increased risk for heterosexual HIV acquisition in STD patients in Pune, India.

Adolescent↗

PubMed2001

Impact of vitamin A supplementation on anaemia and plasma erythropoietin concentrations in pregnant women: a controlled clinical trial.

INTRODUCTION: Although studies suggest that vitamin A or its metabolites influence the synthesis of erythropoietin in vitro and in animal models, it is unclear whether vitamin A supplementation increases plasma erythropoietin concentrations in humans. OBJECTIVE: To determine whether daily vitamin A supplementation increases plasma erythropoietin concentrations in pregnant women with a high prevalence of anaemia. METHODS: A randomized, double-blind, controlled clinical trial was conducted to examine the effect of daily vitamin A (3000 microg retinol equivalent), iron (30 mg), and folate (400 microg) versus iron (30 mg) and folate (400 microg) (control) on haemoglobin and plasma erythropoietin concentrations in 203 pregnant women in Malawi, Africa. RESULTS: Mean gestational age at enrollment was 23 wk, at which time 50% of the women were anaemic (haemoglobin <110 g/L). Mean (+/-SEM) change in haemoglobin from enrollment to 38 wk was 4.7+/-1.6 g/L (p=0.003) and 7.3+/-2.3 g/L (p=0.003) in the vitamin A and control groups, respectively. Mean change in plasma erythropoietin concentrations from enrollment to 38 wk was 2.39+/-5.00 (p=0.63) and -2.87+/-3.92 IU/L (p=0.46) in the vitamin A and controls groups, respectively. There were no significant differences between vitamin A and control groups in the slope of the regression line between log10 erythropoietin and haemoglobin at enrollment or 38 wk, and between enrollment and follow-up within either group. CONCLUSIONS: Vitamin A supplementation does not appear to increase haemoglobin and plasma erythropoietin concentrations among pregnant women with a high prevalence of anaemia in Malawi.

Adult↗

PubMed2001

Iron supplementation during human immunodeficiency virus infection: a double-edged sword?

Although iron supplementation is considered beneficial for groups at risk for anemia, concern has been raised that it could be harmful during human immunodeficiency virus (HIV) infection. Studies suggest: (1) faster HIV disease progression in thalassemia major patients receiving inadequate doses of iron-chelating drug; (2) higher mortality among patients receiving iron supplementation with dapsone compared with aerosolized pentamidine for prophylaxis against Pneumocytis carinii pneumonia; (3) higher iron stores and mortality among patients with haptoglobin Hp 2-2 phenotype; and (4) shorter survival among patients with high bone marrow iron deposition. These studies largely involved men in developed countries. Among HIV-infected pregnant women in Africa with a high prevalence of iron deficiency, no relationship was found between indicators of iron status and HIV disease severity. The available data do not contraindicate the current practice of iron supplementation in developing countries where there is a high prevalence of both HIV infection and iron deficiency.

Anemia, Iron-Deficiency↗