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Tubular membrane ultrafiltration and microfiltration are important industrial separation and concentration processes. Process optimisation requires reduction of membrane build-up. Gas slug introduction has been shown to be a useful... more
Tubular membrane ultrafiltration and microfiltration are important industrial separation and concentration processes. Process optimisation requires reduction of membrane build-up. Gas slug introduction has been shown to be a useful approach for flux enhancement. However, process quantification is required for design and optimisation. In this work we employ a non-porous wall CFD model to quantify hydrodynamics in the two-phase slug flow process. Mass transfer is subsequently quantified from wall shear stress, which was determined from the CFD. The mass transfer model is an improved one-dimensional boundary layer model, which empirically incorporates effects of wall suction and analytically includes edge effects for circular conduits. Predicted shear stress profiles are in agreement with experimental results and flux estimates prove more reliable than that from previous models. Previous models ignored suction effects and employed less rigorous fluid property inclusion, which ultimatel...
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In this study, gas sparged ultrafiltration experiments are performed using a tubular membrane module installed horizontally with solution of dextran as the test media. Experiments showed that flux enhancement; as a consequence of gas... more
In this study, gas sparged ultrafiltration experiments are performed using a tubular membrane module installed horizontally with solution of dextran as the test media. Experiments showed that flux enhancement; as a consequence of gas sparging is profoundly augmented. Controlled pulse injection proved to be more advantageous than uncontrolled gas sparging. Experimental work was conducted over a wide range of gas and liquid flow rates. Numerical simulation using CFD provided insightful information on the structure of the flow in the membrane module and predicted the permeate flux with reasonable accuracy.
In the present paper, the effect of chemical additives or reagents on rheological characteristics of coal� water slurry (CWS) was investigated. The powerlaw model was applied to determine the non� Newtonian properties of coal slurries.... more
In the present paper, the effect of chemical additives or reagents on rheological characteristics of coal� water slurry (CWS) was investigated. The powerlaw model was applied to determine the non� Newtonian properties of coal slurries. Three types of dispersants namely, sulphonic acid, sodium tri� polyphosphate and sodium carbonate were studied and tested at different concentrations ranging from 0.5 to 1.5%
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Wasting and micronutrient malnutrition have not been well characterized in adults with pulmonary tuberculosis. We hypothesized that micronutrient malnutrition is associated with wasting and higher plasma human immunodeficiency virus (HIV)... more
Wasting and micronutrient malnutrition have not been well characterized in adults with pulmonary tuberculosis. We hypothesized that micronutrient malnutrition is associated with wasting and higher plasma human immunodeficiency virus (HIV) load in adults with pulmonary tuberculosis. In a cross-sectional study involving 579 HIV-positive and 222 HIV-negative adults with pulmonary tuberculosis in Zomba, Malawi, anthropometry, plasma HIV load and plasma micronutrient concentrations (retinol, alpha-tocopherol, carotenoids, zinc, and selenium) were measured. The risk of micronutrient deficiencies was examined at different severity levels of wasting. Body mass index (BMI), plasma retinol, carotenoid and selenium concentrations significantly decreased by increasing tertile of plasma HIV load. There were no significant differences in plasma micronutrient concentrations between HIV-negative individuals and HIV-positive individuals who were in the lowest tertile of plasma HIV load. Plasma vitam...
Research Interests: Microbiology, Medical Microbiology, Adolescent, Micronutrients, HIV, and 15 moreMalawi, Malnutrition, Humans, Female, Male, Zinc, Clinical Sciences, Middle Aged, Human immunodeficiency virus, Body mass index (BMI), Adult, Pulmonary Tuberculosis, Cross sectional Study, Cross Sectional Studies, and Viral Load
The acute phase response and inflammation are associated with lower plasma retinol concentrations, but their effect on breast milk retinol concentrations is unclear. We measured plasma retinol concentrations, acute phase proteins, and... more
The acute phase response and inflammation are associated with lower plasma retinol concentrations, but their effect on breast milk retinol concentrations is unclear. We measured plasma retinol concentrations, acute phase proteins, and breast milk retinol concentrations in 237 breast-feeding women at 2 wk postpartum in Blantyre, Malawi; 16.5% of the women had plasma retinol < 0.70 micromol/L and 14.8% had breast milk retinol < 1.05 micromol/L. Among women with and without inflammation [alpha(1)-acid glycoprotein (AGP) > 1 g/L and/or C-reactive protein (CRP) > 5 mg/L], geometric mean (95% CI) plasma retinol was 0.89 (0.84, 0.94) and 1.05 (1.01, 1.17) mumol/L, respectively (P < 0.0001). Among women with and without inflammation, geometric mean (95% CI) breast milk retinol was 2.12 (1.89, 2.36) and 2.05 (1.75, 2.39) micromol/L, respectively (P = 0.74). In multiple linear regression models adjusting for age, parity, education, BMI, and days postpartum, plasma retinol conce...
Research Interests: Nutrition and Dietetics, Inflammation, Animal Production, Malawi, Vitamin A, and 18 moreHumans, Female, Systemic inflammation, P-glycoprotein, Infant, The, Body Mass Index, Multiple Linear Regression, C reactive protein, Adult, Breast feeding, Breast milk, Human Milk, Vitamin A deficiency, Biological markers, Food Sciences, Parity, and Acute Phase Response
Objective. We investigated gender-spe- cific risks of mother-to-child transmission (MTCT) at birth and at 6 to 8 weeks among infants born to HIV- infected African women. Design. Follow-up study of infants enrolled in 2 ran- domized, phase... more
Objective. We investigated gender-spe- cific risks of mother-to-child transmission (MTCT) at birth and at 6 to 8 weeks among infants born to HIV- infected African women. Design. Follow-up study of infants enrolled in 2 ran- domized, phase III, clinical trials to prevent MTCT, con- ducted in Blantyre, Malawi, in southeast Africa. Methods. Infants were enrolled at birth and moni- tored
Research Interests: Pediatrics, Multivariate Statistics, Clinical Trial, Probability, HIV, and 19 moreMalawi, Birth Weight, Pregnancy, Humans, Female, Male, Gender Difference, Infant, Follow-up studies, Hiv Infection, Risk factors, Newborn Infant, mother to child transmission of HIV /AIDS prevention, Sex Factors, Sub Saharan Africa, Risk Factors, Fetal death, Mortality rate, and Viral Load
Innovative, low-cost, and acceptable measures are needed to reduce sexually transmitted infections (STIs) including HIV. Use of a topical microbicide wipe for penile cleaning before and after sex might be effective in preventing STIs.... more
Innovative, low-cost, and acceptable measures are needed to reduce sexually transmitted infections (STIs) including HIV. Use of a topical microbicide wipe for penile cleaning before and after sex might be effective in preventing STIs. However, evaluation of this simple method has not been done. Two studies were conducted in Malawi to determine the safety, acceptability, and potential efficacy of a benzalkonium chloride topical penile microbicide wipe. The first study was a phase 1 dose-escalating clinical trial among low-risk circumcised or uncircumcised HIV-negative men. The second study was a pilot before-after efficacy study among uncircumcised HIV-negative or -positive men. In the first study 24 circumcised and 27 uncircumcised men were enrolled. During the entire study period, 18 adverse events (AEs) were reported, and 3 AEs were confirmed by physical examination. Acceptability concerns did not increase with dose escalation, and adherence to use of the wipe ranged from 89%-95%. In the second study, 27 men were enrolled. Gram stain and culture tests showed significant reductions in frequency of several organisms after use of the wipe, including STI-associated bacteria. This penile wipe is safe, acceptable, and can decrease the frequency of penile colonization with microorganisms. The clinical relevance remains to be determined in larger clinical trials.
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Background: Poor nutrition may be associated with mother-to- child transmission (MTCT) of HIV and other adverse pregnancy outcomes. Objective: The objective was to examine the relation of nutritional indicators with adverse pregnancy... more
Background: Poor nutrition may be associated with mother-to- child transmission (MTCT) of HIV and other adverse pregnancy outcomes. Objective: The objective was to examine the relation of nutritional indicators with adverse pregnancy outcomes among HIV-infected women in Tanzania, Zambia, and Malawi. Design: Body mass index (BMI; in kg/m2) and hemoglobin con- centrationsatenrollmentandweightchangeduringpregnancywere prospectively related to fetal loss, neonatal death, low
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The objective of this study was to determine the incidence of HIV-1. The goal of this study was to inform HIV prevention and vaccine trials by conducting a multisite study in Malawi and Zimbabwe. Women of reproductive age were enrolled in... more
The objective of this study was to determine the incidence of HIV-1. The goal of this study was to inform HIV prevention and vaccine trials by conducting a multisite study in Malawi and Zimbabwe. Women of reproductive age were enrolled in a prospective study. They received 5 intensive HIV counseling and condom promotion sessions over 2 months. Subsequently, HIV-negative women completed quarterly follow-up visits. HIV incidence rates and predictors of HIV acquisition were assessed. A total of 2016 HIV-negative women were enrolled in the condom promotion and counseling phase of the study. Of these, 1679 were tested for HIV during follow up and 113 women seroconverted, resulting in an overall HIV incidence rate of 4.7 per 100 women-years (95% confidence interval = 3.8-5.6). Incidence rates were similar across sites. The major predictors of HIV acquisition were young age, presence of sexually transmitted infections, being unmarried, and higher educational level. The incidence of HIV continues to be high among women in both Malawi and Zimbabwe despite counseling and condom promotion.
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Research Interests: Risk Taking, Chlamydia trachomatis, Biological Sciences, Humans, Baltimore, and 14 moreFemale, Sexually transmitted infections, Male, Sexual Behavior, Trichomonas vaginalis, Prevalence, Questionnaires, Adult, Bacterial Vaginosis, Condoms, Cross Sectional Studies, Sexually Transmitted Diseases, Neisseria gonorrhoeae, and Cohort Studies
Research Interests: Communication, Public sector, Multidisciplinary, Maternal and Child Health, Antiretroviral Therapy, and 22 moreSouth Africa, Prospective studies, Pregnancy, Humans, Female, Cohort Study, Follow-up studies, Pregnancy Loss, Hiv Infection, Incidence, PLoS one, Prevalence, Fertility Rate, Adult, Time Factors, Highly Active Antiretroviral Therapy, Pregnant Women, Pregnancy Rate, Confidence Interval, Cumulative Incidence, Health Personnel, and Viral Load(South Africa, Prospective studies, Pregnancy, Humans, Female, Cohort Study, Follow-up studies, Pregnancy Loss, Hiv Infection, Incidence, PLoS one, Prevalence, Fertility Rate, Adult, Time Factors, Highly Active Antiretroviral Therapy, Pregnant Women, Pregnancy Rate, Confidence Interval, Cumulative Incidence, Health Personnel, and Viral Load)
(South Africa, Prospective studies, Pregnancy, Humans, Female, Cohort Study, Follow-up studies, Pregnancy Loss, Hiv Infection, Incidence, PLoS one, Prevalence, Fertility Rate, Adult, Time Factors, Highly Active Antiretroviral Therapy, Pregnant Women, Pregnancy Rate, Confidence Interval, Cumulative Incidence, Health Personnel, and Viral Load)
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Research Interests: Pediatrics, Africa, Survival Analysis, Comorbidity, HIV, and 22 moreDiarrhea, Humans, Chronic Disease, Female, Male, Infant, Follow-up studies, Hiv Infection, Human immunodeficiency virus, Kaplan-Meier, Fever, Survival Rate, First Year, Physical examination, Management Strategy, Dermatitis, Developmental delay, Cough, Proportional Hazards Models, Prospective Study, First Occurrence, and Acquired immunodeficiency syndrome(Diarrhea, Humans, Chronic Disease, Female, Male, Infant, Follow-up studies, Hiv Infection, Human immunodeficiency virus, Kaplan-Meier, Fever, Survival Rate, First Year, Physical examination, Management Strategy, Dermatitis, Developmental delay, Cough, Proportional Hazards Models, Prospective Study, First Occurrence, and Acquired immunodeficiency syndrome)
(Diarrhea, Humans, Chronic Disease, Female, Male, Infant, Follow-up studies, Hiv Infection, Human immunodeficiency virus, Kaplan-Meier, Fever, Survival Rate, First Year, Physical examination, Management Strategy, Dermatitis, Developmental delay, Cough, Proportional Hazards Models, Prospective Study, First Occurrence, and Acquired immunodeficiency syndrome)
Infants born to women who receive intrapartum antibiotics may have higher rates of infectious morbidity and mortality than unexposed infants. Our goal was to determine the association of maternal intrapartum antibiotics and early neonatal... more
Infants born to women who receive intrapartum antibiotics may have higher rates of infectious morbidity and mortality than unexposed infants. Our goal was to determine the association of maternal intrapartum antibiotics and early neonatal morbidity and mortality. We performed secondary analysis of data from a multisite randomized, placebo-controlled clinical trial of antibiotics to prevent chorioamnionitis-associated mother-to-child transmission of HIV-1 and preterm birth in sub-Saharan Africa. Early neonatal morbidity and mortality were analyzed. In an intention-to-treat (ITT) analysis, infants born to women randomly assigned to antibiotics or placebo were compared. In addition, non-ITT analysis was performed because some women received nonstudy antibiotics for various clinical indications. Overall, 2659 pregnant women were randomly assigned. Of these, 2466 HIV-1-infected and HIV-1-uninfected women delivered 2413 live born and 84 stillborn infants. In the ITT analysis, there were no significant associations between exposure to antibiotics and early neonatal outcomes. Non-ITT analyses showed more illness at birth (11.2% vs 8.6%, P = .03) and more admissions to the special care infant unit (12.6% vs 9.8%, P = .04) among infants exposed to maternal intrapartum antibiotics than among unexposed infants. Additional analyses revealed greater early neonatal morbidity and mortality among infants of mothers who received nonstudy antibiotics than of mothers who received study antibiotics. There is no association between intrapartum exposure to antibiotics and early neonatal morbidity or mortality. The associations observed in non-ITT analyses are most likely the result of women with peripartum illnesses being more likely to receive nonstudy antibiotics.
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Research Interests: Survival Analysis, Tanzania, Zambia, HIV, Multivariate Analysis, and 16 moreMalawi, Pregnancy, Humans, Female, Infant, Risk factors, Newborn Infant, Human immunodeficiency virus, Longitudinal Studies, Anti-Bacterial Agents, Adult, Time Factors, Pregnant Women, Risk Factors, Proportional Hazards Models, and Viral Load
HIV-infected and uninfected children who survived their first year of life were prospectively followed in Malawi to assess levels of mortality and related risk factors during the second and third years of life. Children with known HIV... more
HIV-infected and uninfected children who survived their first year of life were prospectively followed in Malawi to assess levels of mortality and related risk factors during the second and third years of life. Children with known HIV status from an earlier perinatal intervention trial were enrolled. These children [HIV-infected (Group A); HIV-uninfected but born to HIV-seropositive mothers (Group B); and children born to HIV-seronegative mothers (Group C)] were followed every 3 months until age 36 months. Mortality data were collected at each visit. Immunologic data (CD4+ percent) were collected at or immediately after enrollment. Overall 702 children were enrolled and 83 children died during follow-up. The mortality rate per 1000 person years of observation was 339.3 among Group A children, 46.3 among Group B children and 35.7 among Group C children. Among HIV-infected children the cumulative proportion surviving to age 24 months was 70% and those surviving to age 36 months was 55%. By age 32 months none of the severely immunosuppressed (CD4% &amp;amp;lt; 15%) children had survived. The mortality differentials between HIV-infected and uninfected children persisted after adjusting for several risk factors. The major causes of death among infected children (n = 52) were wasting and respiratory conditions. Although all HIV-infected children had received childhood immunizations, mortality was high. Management of these children should include aggressive antimicrobial treatment, and evaluation of prophylactic regimens should be considered.
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The risk of HIV-1 infection is high among breast-fed children in sub-Saharan Africa. Monitoring the nutritional status can provide useful information to determine the effect of HIV infection and breast-feeding on child growth and... more
The risk of HIV-1 infection is high among breast-fed children in sub-Saharan Africa. Monitoring the nutritional status can provide useful information to determine the effect of HIV infection and breast-feeding on child growth and development. We longitudinally assessed the nutritional status and determined its association with HIV infection and breast-feeding among Malawian children. We analyzed data from 2 clinical trials to prevent mother-to-child transmission of HIV in Malawi. These trials were conducted during 2000-2003 before the current guidelines were implemented to breast-feed exclusively during the first 6 months and wean thereafter. The nutritional status of children was measured up to age 24 months, using z-scores. Age-specific differences in length-for-age (L/A), weight-for-age (W/A), and weight-for-length (W/L) were compared stratifying by gender and HIV infection status. Multivariable models examined the mean change in z-scores controlling for breast-feeding and other factors. In this analysis, 1589 children were included. Boys had significantly lower L/A scores and became stunted (z-score -&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;2 standard deviations) earlier than girls. HIV-infected children had significantly lower mean L/A and W/A z-scores than HIV-uninfected children and became stunted and underweight at an earlier age. In multivariable analysis not being breast-fed and being HIV infected were significantly (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) associated with decreases in mean L/A, W/A, and W/L z-scores. This study shows the impact of infant HIV infection on growth and supports the critical importance of breast-feeding. Mother-to-child transmission of HIV programs should endeavor to preserve breast-feeding and find alternative measures to prevent postnatal HIV transmission.
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Research Interests: Developing Countries, England, HIV, Malawi, Humans, and 17 moreFemale, Male, Infant, Risk factors, Newborn Infant, New England, Infant Mortality, Adverse Event, Breast feeding, Breast milk, Human Milk, Combination drug therapy, Risk Factors, New England Journalof Medicine, Proportional Hazards Models, Control Group, and Nevirapine
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In the Human Immunodeficiency Virus (HIV) Network for Prevention Trials (HIVNET) 012 trial in Uganda, 6-8 weeks after single-dose nevirapine (SD-NVP), NVP resistance mutations were detected at a higher rate in women with HIV-1 subtype D... more
In the Human Immunodeficiency Virus (HIV) Network for Prevention Trials (HIVNET) 012 trial in Uganda, 6-8 weeks after single-dose nevirapine (SD-NVP), NVP resistance mutations were detected at a higher rate in women with HIV-1 subtype D than in women with subtype A. Here, we evaluate the rate of NVP resistance mutations in women with subtype C. NVP resistance mutations were detected using the ViroSeq HIV-1 Genotyping System. The portion of women with any NVP resistance mutation was higher in those with subtype C (45/65 [69.2%] in the NVP and zidovudine trial, Malawi) than in those in the HIVNET 012 trial with either subtype A (28/144 [19.4%]; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.0001) or subtype D (35/97 [36.1%]; P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.0001). In a multivariate model, subtype (C vs. A: odds ratio [OR], 8.73 [95% confidence interval {CI}, 4.29-17.76]; C vs. D: OR, 3.38 [95% CI, 1.65-6.93]) and viral load at delivery (OR, 2.35 [95% CI, 1.62-3.40]) independently predicted NVP resistance mutations, but maternal age, parity, and time between SD-NVP and the 6-8-week visit did not. The rate of NVP resistance mutations after SD-NVP was significantly higher in women with HIV-1 subtype C than in women with subtype A or D. Studies are needed to assess the clinical significance of this finding.
Research Interests: Infectious Diseases, HIV, Biological Sciences, Pregnancy, Humans, and 5 moreFemale, Infectious, Genotype, Adult, and Nevirapine
Research Interests: Nursing, Immunology, Mastitis, Carotenoids, Adolescent, and 22 moreMalawi, Pregnancy, Humans, Female, Hiv Infection, Potassium, Proteins, Risk factors, Clinical Sciences, Human immunodeficiency virus, Longitudinal Studies, Adult, Sodium, Public health systems and services research, Breast milk, Human Milk, Risk Factors, Cross sectional Study, Cross Sectional Studies, Human Lactation, Interleukin, and Viral Load(Malawi, Pregnancy, Humans, Female, Hiv Infection, Potassium, Proteins, Risk factors, Clinical Sciences, Human immunodeficiency virus, Longitudinal Studies, Adult, Sodium, Public health systems and services research, Breast milk, Human Milk, Risk Factors, Cross sectional Study, Cross Sectional Studies, Human Lactation, Interleukin, and Viral Load)
(Malawi, Pregnancy, Humans, Female, Hiv Infection, Potassium, Proteins, Risk factors, Clinical Sciences, Human immunodeficiency virus, Longitudinal Studies, Adult, Sodium, Public health systems and services research, Breast milk, Human Milk, Risk Factors, Cross sectional Study, Cross Sectional Studies, Human Lactation, Interleukin, and Viral Load)
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The major remaining challenge in the prevention of mother-to-child transmission is the reduction of the risk in settings where breast-feeding is common. This review gives an update on ongoing or planned antiretroviral intervention studies... more
The major remaining challenge in the prevention of mother-to-child transmission is the reduction of the risk in settings where breast-feeding is common. This review gives an update on ongoing or planned antiretroviral intervention studies in resource-limited settings that are aimed at reducing the risk of mother-to-infant HIV transmission during lactation. These strategies include antiretroviral therapy given to the mother to reduce viral load in plasma and breast milk as well as antiretroviral regimens providing prophylaxis to uninfected infants during the period of breast-feeding. The rationale for the interventions based on animal models and human studies is described as well as the study designs of clinical trials. Potential risks and benefits of these interventions to mothers and infants are also highlighted. Laboratory studies nested within several of these trials will provide a better understanding of the pathogenesis of postnatal HIV transmission and its potential prevention using antiretroviral drugs.
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The HIVNET 012 trial in Uganda showed that mother-to-child transmission (MTCT) of HIV-1 can be prevented by providing pregnant women and their infants with a single dose (SD) of the antiretroviral drug, nevirapine (NVP). 1,2 Safety and... more
The HIVNET 012 trial in Uganda showed that mother-to-child transmission (MTCT) of HIV-1 can be prevented by providing pregnant women and their infants with a single dose (SD) of the antiretroviral drug, nevirapine (NVP). 1,2 Safety and efficacy of 1-or 2-dose NVP prophylaxis for ...
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Our objectives were to assess clinical signs and diagnoses associated with primary HIV-1 infection among infants. We analyzed data from a clinical trial (HIV Prevention Trials Network Protocol 024) in sub-Saharan Africa. Study visits were... more
Our objectives were to assess clinical signs and diagnoses associated with primary HIV-1 infection among infants. We analyzed data from a clinical trial (HIV Prevention Trials Network Protocol 024) in sub-Saharan Africa. Study visits were conducted at birth, at 4-6 weeks, and at 3, 6, 9, and 12 months. The study population comprised live born, singleton, first-born infants of HIV-1-infected women with negative HIV-1 RNA assays who were still breastfeeding at 4-6 weeks. Of 1317 HIV-1-exposed infants, 84 became HIV-1 infected after 4-6 weeks and 1233 remained uninfected. There were 102 primary and 5650 nonprimary infection visits. The most common signs were cough and diarrhea, and the most common diagnoses were malaria and pneumonia. Primary infection was associated with significantly increased odds of diarrhea [odds ratio (OR) = 2.4], pneumonia (OR = 3.5), otitis media (OR = 3.1), and oral thrush (OR = 2.9). For the clinical signs and diagnoses evaluated, sensitivity was low (1%-16.7%) and specificity was high (88.2%-99%). Positive predictive values ranged from 0.1%-1.4%. Negative predictive values ranged from 28.0%-51.1%. Certain clinical signs and diagnoses, although more common during primary HIV-1 infection, had low sensitivity and high specificity. Efforts to expand access to laboratory assays for the diagnosis of primary HIV-1 infection among infants of HIV-1-infected women should be emphasized.
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We used a sensitive point mutation assay, LigAmp, to detect and quantify K103N-containing variants in African women who received single-dose nevirapine (NVP) to prevent mother-to-child HIV-1 transmission. Plasma for testing was collected... more
We used a sensitive point mutation assay, LigAmp, to detect and quantify K103N-containing variants in African women who received single-dose nevirapine (NVP) to prevent mother-to-child HIV-1 transmission. Plasma for testing was collected 6 to 8 weeks postpartum from 301 women (144 subtype A, 63 subtype C, and 94 subtype D). The portion of women with 0.5% or more K103N-containing variants was lowest for subtype A (60/144, 41.7%) and highest for subtype C (44/63, 69.8%; P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.0001). K103N was rarely detected in pre-NVP samples. In a multivariate model, K103N detection was associated with HIV-1 subtype (C &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; A), after adjusting for log10 delivery viral load, the number of days between NVP dosing and sample collection, age, and parity. Among women with K103N detected: (1) the median %K103N was lower for subtype A (2.2%) than C (11.7%, P = 0.0001) or D (5.5%, P = 0.04), and (2) in a multivariate linear model, higher log10 (%K103N) was associated with HIV subtype (C &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; A, P = 0.0001; D &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; A, P = 0.01; and C vs D, no difference), but not other factors. After administration of single-dose NVP, K103N was detected more frequently and at higher levels in women with subtypes C and D than A. Further studies are needed to evaluate the clinical significance of NVP-resistant variants in this setting.
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Research Interests: Medical Microbiology, Adolescent, Tanzania, Zambia, Malawi, and 15 morePregnancy, Humans, Female, Young Adult, Hiv Infection, Risk factors, Clinical Sciences, Prevalence, Human immunodeficiency virus, Adult, Public health systems and services research, Pregnant Women, STD, Risk Factors, and Bacterial Vaginosis
The aim of this study was to determine HIV-1 incidence among women of reproductive age in Malawi. A prospective study design was followed. HIV-1 uninfected women were followed up for nine visits during a period of 12 months. At baseline,... more
The aim of this study was to determine HIV-1 incidence among women of reproductive age in Malawi. A prospective study design was followed. HIV-1 uninfected women were followed up for nine visits during a period of 12 months. At baseline, women received HIV-1 counselling and testing. At each visit, venous blood was collected for HIV-1 testing. Incidence rate for HIV-1 was estimated using person-years of follow up (PYFU). Risk factors for HIV acquisition were assessed using Cox proportional hazard models. A total of 842 HIV-1 negative women were enrolled in the study. Of these, 787 had subsequent HIV testing and 31 were found HIV-1 infected; an overall incidence rate of 4.51 (95% confidence interval: 2.96-6.06) per 100 PYFU was obtained. Young age, using hormonal injectable contraceptives and bacterial vaginosis were the main predictors of HIV acquisition. The incidence of HIV continues to be high among women in Malawi, and young women appear to be at higher risk.
Research Interests: Research Methodology, Behavior, Medical Microbiology, Developing Countries, Economic Development, and 16 moreHealth, HIV, Malawi, Prospective studies, Population, Humans, Measurement, Female, Incidence, Risk factors, Clinical Sciences, Prevalence, Public health systems and services research, Risk Factors, Bacterial Vaginosis, and Sexually Transmitted Diseases
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,... more
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.
Research Interests: Microbiology, Medical Microbiology, Mastitis, Micronutrients, HIV, and 16 moreMalawi, Pregnancy, Humans, Female, Staphylococcus aureus, Hiv Infection, Risk factors, Clinical Sciences, Newborn Infant, Adult, Public health systems and services research, Breast feeding, Human Milk, STD, Risk Factors, and Viral Load
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Research Interests: Statistics, Epidemiology, HIV, Malawi, Pregnancy, and 16 moreHumans, Female, Male, Missing Data, Infant, Follow-up studies, Hiv Infection, Risk factors, Newborn Infant, Prevalence, Human immunodeficiency virus, Public health systems and services research, Retrospective Studies, Risk Factors, Gestational Age, and Predictive value of tests
Low birthweight, prematurity and intra-uterine growth retardation (IUGR) are major determinants of child survival. Therefore, it is important to assess excess mortality due to human immunodeficiency virus (HIV) infection in populations... more
Low birthweight, prematurity and intra-uterine growth retardation (IUGR) are major determinants of child survival. Therefore, it is important to assess excess mortality due to human immunodeficiency virus (HIV) infection in populations where low birthweight is common. A prospective study was conducted on 1385 children born to seropositive and seronegative women in urban Malawi. Children were regularly examined and tested for HIV. The mortality rate of children of HIV seropositive mothers was substantially higher (223/1000 at 12 months, 317/1000 at 24 months and 360/1000 at 30 months) than that of children of seronegative mothers (68/1000 at 12 months, 106/1000 at 24 months and 118/1000 at 30 months). The incidence of prematurity and IUGR was also higher in infants of HIV seropositive mothers than in infants of seronegative mothers (12.7% versus 3.8%, P &amp;amp;lt; 0.001 for premature and 7.7% versus 4.4%, P = 0.02 for IUGR infants). The mother-to-infant HIV-1 transmission rate was 35.1%. After 12 months of age, HIV infected children showed the highest mortality; however, uninfected children of HIV seropositive and children of HIV seronegative mothers had similar mortality. The mean birthweight of HIV infected and uninfected children was not significantly different. In HIV infected children the most frequent causes of death were diarrhoea, pneumonia and failure to thrive. Less common risk factors for child mortality included active maternal syphilis and cervicitis/vaginitis. The substantial difference in survival among children of HIV infected and uninfected mothers suggests that mortality could be reduced if HIV infection were not a risk factor. To decrease childhood mortality, a combination of interventions such as treatment of sexually transmitted infections during pregnancy and measures to reduce mother-to-infant transmission should be adopted.
Research Interests: Statistics, Epidemiology, Survival Analysis, HIV, Multivariate Analysis, and 16 moreMalawi, Birth Weight, Prospective studies, Pregnancy, Humans, Female, Risk factors, Newborn Infant, Human immunodeficiency virus, Infant Mortality, Public health systems and services research, Hiv seropositivity, Risk Factors, Child mortality, Sexually Transmitted Diseases, and Case Control Studies(Malawi, Birth Weight, Prospective studies, Pregnancy, Humans, Female, Risk factors, Newborn Infant, Human immunodeficiency virus, Infant Mortality, Public health systems and services research, Hiv seropositivity, Risk Factors, Child mortality, Sexually Transmitted Diseases, and Case Control Studies)
(Malawi, Birth Weight, Prospective studies, Pregnancy, Humans, Female, Risk factors, Newborn Infant, Human immunodeficiency virus, Infant Mortality, Public health systems and services research, Hiv seropositivity, Risk Factors, Child mortality, Sexually Transmitted Diseases, and Case Control Studies)
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An attempt is made to model slug flow inside square capillaries containing Newtonian liquids. In square micro-channels, slug flows proved to promote high rates of heat and mass transfer between the solid boundaries and the bulk flow. This... more
An attempt is made to model slug flow inside square capillaries containing Newtonian liquids. In square micro-channels, slug flows proved to promote high rates of heat and mass transfer between the solid boundaries and the bulk flow. This is due to the combination of ...
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ABSTRACT The analogy between heat and mass transfer is frequently employed in single-phase flows. Here the analogy is examined for two processes involving two-phase flow in meso-channels with bores ≤1 mm: the injection of gas bubbles to... more
ABSTRACT The analogy between heat and mass transfer is frequently employed in single-phase flows. Here the analogy is examined for two processes involving two-phase flow in meso-channels with bores ≤1 mm: the injection of gas bubbles to enhance the ultrafiltration of large molecules in aqueous solutions using hollow fibre membranes and flow boiling in the confined-bubble regime. This paper considers the local mechanisms in these superficially similar processes, based on information from experiments and numerical simulations and discusses the extent to which they are indeed similar. It is concluded that there is no useful analogy between mass and heat transfer in these processes but they share a requirement for accurate estimation of the thickness of the liquid film between confined bubbles and the channel wall at high Reynolds numbers.