Joel A. Dave

Chronic noncommunicable diseases and HIV-AIDS on a collision course: relevance for health care delivery, particularly in low-resource settings—insights from South Africa

Sub-Saharan Africa is experiencing a multiple disease burden. Noncommunicable diseases (NCDs) are emerging, and their risk factors are becoming more common as lifestyles change and rates of urbanization increase. Simultaneously, epidemics of infectious diseases persist, and HIV/AIDS has taken hold in the region, although recent data indicate a decrease in new HIV infection rates. With the use of diabetes as a marker for NCDs, it was estimated that the number of people with diabetes would rise between 2000 and 2010 despite the HIV/AIDS epidemic, largely because of the aging of the population and the increase in risk factors for diabetes in South Africa. These numbers are likely to increase further, given the declining HIV/AIDS mortality rates and longer life expectancy due to the up-scaling of antiretroviral therapy (ART), with its concomitant metabolic complications. Given that treated HIV/AIDS has become a chronic disease, and the health care needs of people on ART resemble those of people with NCDs, and given that vertical programs are difficult to sustain when health systems are underresourced and strained, there is a powerful argument to integrate the primary level care for people with chronic diseases, whether they be NCDs or infectious diseases. Pilot studies are required to test the feasibility of an integrated service that extends from health facilities into the community in a reciprocal manner based on the WHO Innovative Care for Chronic Conditions model of care. These will begin to provide the evidence that policy makers need to change the mode of health care delivery.

HIV neuropathy in South Africans: Frequency, characteristics, and risk factors

The purpose was to estimate the frequency, characteristics, and risk factors of HIV‐associated distal sensory polyneuropathy (DSP) among South Africans who attend an urban community‐based clinic. In a cross‐sectional study, neuropathy status was determined in 598 HIV‐infected adults using validated tools (Brief Peripheral Neuropathy Screen and a modified version of the Total Neuropathy Score) to categorize subjects as DSP versus no DSP. Symptomatic DSP (SDSP) required the presence of at least two neuropathic signs together with symptoms. Clinical, anthropometric, and laboratory evaluations were prospectively performed. CD4 counts, antiretroviral therapy (ART), and questionnaires regarding previous tuberculosis (TB) and alcohol exposure were collected retrospectively. Approximately half (49%) of the study population were diagnosed with DSP, and 30% of the study population were diagnosed with SDSP. In multivariate analyses the odds ratio (OR) (95% confidence interval) of DSP were independently associated with ART use (OR 1.7, 1.0–2.9), age (per 10 year increment) (OR 1.7, 1.4–2.2), and prior TB (OR 2.0, 1.3–3.0). Pain or paresthesias were reported as moderately severe by 70% of those with SDSP. Stavudine use was significantly associated with DSP. DSP is a clinically significant problem in urban HIV‐infected Africans. Our findings raise the possibility that the incidence of DSP may be reduced with avoidance of stavudine‐containing regimens in older subjects, especially with a history of prior TB infection. Muscle Nerve, 2010

Association of HIV and ART with cardiometabolic traits in sub-Saharan Africa: a systematic review and meta-analysis

Background Sub-Saharan Africa (SSA) has the highest burden of HIV in the world and a rising prevalence of cardiometabolic disease; however, the interrelationship between HIV, antiretroviral therapy (ART) and cardiometabolic traits is not well described in SSA populations. Methods We conducted a systematic review and meta-analysis through MEDLINE and EMBASE (up to January 2012), as well as direct author contact. Eligible studies provided summary or individual-level data on one or more of the following traits in HIV+ and HIV-, or ART+ and ART- subgroups in SSA: body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides (TGs) and fasting blood glucose (FBG) or glycated hemoglobin (HbA1c). Information was synthesized under a random-effects model and the primary outcomes were the standardized mean differences (SMD) of the specified traits between subgroups of participants. Results Data were obtained from 49 published and 3 unpublished studies which reported on 29 755 individuals. HIV infection was associated with higher TGs [SMD, 0.26; 95% confidence interval (CI), 0.08 to 0.44] and lower HDL (SMD, −0.59; 95% CI, −0.86 to −0.31), BMI (SMD, −0.32; 95% CI, −0.45 to −0.18), SBP (SMD, −0.40; 95% CI, −0.55 to −0.25) and DBP (SMD, −0.34; 95% CI, −0.51 to −0.17). Among HIV+ individuals, ART use was associated with higher LDL (SMD, 0.43; 95% CI, 0.14 to 0.72) and HDL (SMD, 0.39; 95% CI, 0.11 to 0.66), and lower HbA1c (SMD, −0.34; 95% CI, −0.62 to −0.06). Fully adjusted estimates from analyses of individual participant data were consistent with meta-analysis of summary estimates for most traits. Conclusions Broadly consistent with results from populations of European descent, these results suggest differences in cardiometabolic traits between HIV-infected and uninfected individuals in SSA, which might be modified by ART use. In a region with the highest burden of HIV, it will be important to clarify these findings to reliably assess the need for monitoring and managing cardiometabolic risk in HIV-infected populations in SSA.

Differential Effects of Abdominal Adipose Tissue Distribution on Insulin Sensitivity in Black and White South African Women

Black South African women are more insulin resistant than BMI‐matched white women. The objective of the study was to characterize the determinants of insulin sensitivity in black and white South African women matched for BMI. A total of 57 normal‐weight (BMI 18–25 kg/m2) and obese (BMI > 30 kg/m2) black and white premenopausal South African women underwent the following measurements: body composition (dual‐energy X‐ray absorptiometry), body fat distribution (computerized tomography (CT)), insulin sensitivity (SI, frequently sampled intravenous glucose tolerance test), dietary intake (food frequency questionnaire), physical activity (Global Physical Activity Questionnaire), and socioeconomic status (SES, demographic questionnaire). Black women were less insulin sensitive (4.4 ± 0.8 vs. 9.5 ± 0.8 and 3.0 ± 0.8 vs. 6.0 ± 0.8 × 10−5/min/(pmol/l), for normal‐weight and obese women, respectively, P < 0.001), but had less visceral adipose tissue (VAT) (P = 0.051), more abdominal superficial subcutaneous adipose tissue (SAT) (P = 0.003), lower SES (P < 0.001), and higher dietary fat intake (P = 0.001) than white women matched for BMI. SI correlated with deep and superficial SAT in both black (R = −0.594, P = 0.002 and R = 0.495, P = 0.012) and white women (R = −0.554, P = 0.005 and R = −0.546, P = 0.004), but with VAT in white women only (R = −0.534, P = 0.005). In conclusion, body fat distribution is differentially associated with insulin sensitivity in black and white women. Therefore, the different abdominal fat depots may have varying metabolic consequences in women of different ethnic origins.

Effect of nonnucleoside reverse transcriptase inhibitor-based antiretroviral therapy on dysglycemia and insulin sensitivity in South African HIV-Infected Patients

Background:Data on the prevalence of the complications of antiretroviral therapy (ART) (diabetes, central fat accumulation, peripheral fat wasting, and dyslipidemia) in sub-Saharan Africa are sparse. We examined the prevalence and associated risk factors of dysglycemia and insulin sensitivity in HIV-infected South Africans. Methods:HIV-infected patients, on nonnucleoside reverse transcriptase inhibitor-based ART or ART-naive, had oral glucose tolerance tests and clinical anthropometry. Insulin sensitivity and β-cell function were assessed. Results:The prevalence of dysglycemia in 406 ART-naive patients and 443 patients on ART was 25.7% and 21.9% (P = 0.193), respectively. Dysglycemic patients on ART had a similar body mass index (P = 0.440), greater waist circumference (P = 0.047), and smaller calf skinfold thickness (P = 0.015) than dysglycemic ART-naive patients but no difference in β-cell function or insulin sensitivity. Normoglycemic patients on ART had a greater body mass index (P = 0.0009), waist circumference (P = 0.0001), and abdominal skinfold thickness (P = 0.040), similar calf skinfold thickness (P = 0.079), and reduced β-cell function [lower insulinogenic index (P = 0.027) and oral disposition index (Do, P = 0.020)] compared with normoglycemic ART-naive patients. In multivariate analysis, older age [odds ratio (OR): 1.04, 95% confidence interval (CI): 1.02 to 1.06], male gender (OR: 1.96, 95% CI: 1.28 to 2.99), higher CD4 count (OR: 1.0, 95% CI: 1.00 to 1.02) and use of efavirenz (OR: 1.70, 95% CI: 1.19 to 2.45) were associated with dysglycemia. Conclusions:The prevalence of dysglycemia in ART-naive and ART patients was similar. Peripheral fat wasting was more common in dysglycemic patients on ART. The association of efavirenz with dysglycemia is important because first-line ART regimens in the developing world include nonnucleoside reverse transcriptase inhibitors, and increasingly, efavirenz is selected because of its perceived lower toxicity than nevirapine.

Mycosin-1, a subtilisin-like serine protease of Mycobacterium tuberculosis, is cell wall-associated and expressed during infection of macrophages

BackgroundExported proteases are commonly associated with virulence in bacterial pathogens, yet there is a paucity of information regarding their role in Mycobacterium tuberculosis. There are five genes (mycP1-5) present within the genome of Mycobacterium tuberculosis H37Rv that encode a family of secreted, subtilisin-like serine proteases (the mycosins). The gene mycP1 (encoding mycosin-1) was found to be situated 3700 bp (four ORFs) from the RD1 deletion region in the genome of the attenuated vaccine strain M. bovis BCG (bacille de Calmette et Guérin) and was selected for further analyses due to the absence of expression in this organism.ResultsFull-length, 50 kDa mycosin-1 was observed in M. tuberculosis cellular lysates, whereas lower-molecular-weight species were detected in culture filtrates. A similar lower-molecular-weight species was also observed during growth in macrophages. Mycosin-1 was localized to the membrane and cell wall fractions in M. tuberculosis by Western blotting, and to the cell envelope by electron microscopy. Furthermore, M. tuberculosis culture filtrates were shown to contain a proteolytic activity inhibited by mixed serine/cysteine protease inhibitors and activated by Ca2+, features typical of the subtilisins.ConclusionsMycosin-1 is an extracellular protein that is membrane- and cell wall-associated, and is shed into the culture supernatant. The protein is expressed after infection of macrophages and is subjected to proteolytic processing. Although proteolytically active mycosin-1 could not be generated recombinantly, serine protease activity containing features typical of the subtilisins was detected in M. tuberculosis culture filtrates.

The mycosins of Mycobacterium tuberculosis H37Rv: a family of subtilisin-like serine proteases

There is little information regarding the role of proteolysis in Mycobacterium tuberculosis and no studies on the potential involvement of proteases in the pathogenesis of tuberculosis. We identified five M. tuberculosis genes (mycP1-5) that encode a family of serine proteases (mycosins-1 to 5), ranging from 36 to 47% identity. Each protein contains a catalytic triad (Asp, His, Ser) within highly conserved sequences, typical of proteases of the subtilisin family. These genes are also present in M. bovis BCG and other virulent mycobacteria, but only one homologue (mycP3) was detected in M. smegmatis. The mycosins have N-terminal signal sequences and C-terminal transmembrane anchors, and the localisation of the mycosins to the membrane/cell wall was verified by Western blot analysis of heterologously expressed proteins in cellular fractions of M. smegmatis. In M. tuberculosis, all the mycosins were expressed constitutively during growth in broth. Mycosins-2 and 3 were also expressed constitutively in M. bovis BCG, but no expression of mycosin-1 was detected. Mycosin-2 was modified by cleavage in all three mycobacterial species. The multiplicity and constitutive expression of these proteins suggests that they have an important role in the biology of M. tuberculosis.

Insulin Response in Relation to Insulin Sensitivity: An appropriate β-cell response in black South African women

OBJECTIVE The purpose of this study was to characterize differences in the acute insulin response to glucose (AIRg) relative to insulin sensitivity (SI) in black and white premenopausal normoglycemic South African women matched for body fatness. RESEARCH DESIGN AND METHODS Cross-sectional analysis including 57 black and white South African women matched for BMI, SI, AIRg, and the disposition index (AIRg × SI) were performed using a frequently sampled intravenous glucose tolerance test with minimal model analysis, and similar measures were analyzed using an oral glucose tolerance test (OGTT). Body composition was assessed by dual-energy X-ray absorptiometry and computed tomography. RESULTS SI was significantly lower (4.4 ± 0.8 vs. 9.4 ± 0.8 and 2.9 ± 0.8 vs. 6.0 ± 0. 8 × 10−5 min−1/[pmol/l], P < 0.001) and AIRg was significantly higher (1,028 ± 255 vs. 352 ± 246 and 1,968 ± 229 vs. 469 ± 246 pmol/l, P < 0.001), despite similar body fatness (30.9 ± 1.4 vs. 29.7 ± 1.3 and 46.8 ± 1.2 vs. 44.4 ± 1.3%) in the normal-weight and obese black women compared with their white counterparts, respectively. Disposition index, a marker of β-cell function, was not different between ethnic groups (3,811 ± 538 vs. 2,966 ± 518 and 3,646 ± 485 vs. 2,353 ± 518 × 10−5 min, P = 0.10). Similar results were obtained for the OGTT-derived measures. CONCLUSIONS Black South African women are more insulin resistant than their white counterparts but compensate by increasing their insulin response to maintain normal glucose levels, suggesting an appropriate β-cell response for the level of insulin sensitivity.

Ethnic differences in serum lipoproteins and their determinants in South African women.

The objective of the study was to characterize ethnic differences in lipid levels and low-density lipoprotein (LDL) particle size and subclasses in black and white South African women and to explore the associations with insulin sensitivity (S(I)), body composition, and lifestyle factors. Fasting serum lipids and LDL size and subclasses, body composition (dual-energy x-ray absorptiometry), and S(I) (frequently sampled intravenous glucose tolerance test) were measured in normal-weight (body mass index <25 kg/m(2)) black (n = 15) and white (n = 15), and obese (body mass index >30 kg/m(2)) black (n = 13) and white (n = 13) women. Normal-weight and obese black women had lower triglycerides (0.59 +/- 0.09 and 0.77 +/- 0.10 vs 0.89 +/- 0.09 and 0.93 +/- 0.10 mmol/L, P < .05) and high-density lipoprotein cholesterol (1.2 +/- 0.1 and 1.1 +/- 0.1 vs 1.7 +/- 0.1 and 1.6 +/- 0.3 mmol/L, P < .01) than white women. The LDL particle size was not different, but obese black women had more LDL subclass IV (17.3% +/- 1.0% vs 12.5% +/- 1.0%, P < .01). In white women, triglycerides and LDL particle size correlated with S(I) (P < .01), whereas cholesterol levels correlated with body fat (P < .05). Low socioeconomic status, low dietary protein intake, and injectable contraceptive use were the major determinants of unfavorable lipid profiles in black women. Black women had lower triglyceride and high-density lipoprotein cholesterol levels and more small dense LDL particles than white women. The major determinants of serum lipids in black women were socioeconomic status and lifestyle factors, whereas in white women, S(I) and body composition most closely correlated with serum lipids.

Depot- and ethnic-specific differences in the relationship between adipose tissue inflammation and insulin sensitivity

Objective  It is unclear whether there are differences in inflammatory gene expression between abdominal and gluteal subcutaneous adipose tissue (SAT), and between black and white women. We therefore tested the hypotheses that SAT inflammatory gene expression is greater in the abdominal compared to the gluteal depot, and SAT inflammatory gene expression is associated with differential insulin sensitivity (SI) in black and white women.