Mutagenic predisposition in genes implicated in Alzheimer's Disease

Alzheimer’s disease is the most common cause of late-life dementia and the fourth leading cause of death in the developed world. The aetiology of AD has not yet been resolved. It has been suggested that AD could result from multifactorial process involving both a genetic predisposition and an exposure to environmental factors modulated by the biological aging process. To date, epidemiological and molecular genetic data have led to the identification of three genes, amyloid precursor protein (APP), presenilin 1 (PS1) and presenilin 2 (PS2) genes, which, when mutated, can cause an early onset form of AD. Genetic linkage studies and association studies have also shown that the ε4 allele of the apolipoprotein E gene increases risk for AD in a dose dependent manner in both early onset and late onset AD. Recently, it has also been suggested that environmental factors may interact with a genetic predisposition to modify the risk of AD. Extensive research is underway to identify environmental and genetic risk factors for this complex disease. Over 40 genes have been tested as AD candidates yet none has been clearly established as an AD risk factor. Currently scientists are investigating the interrelationship between various gene loci and how environmental factors could affect an individual’s susceptibility to AD. This study evaluated the genotoxicity of environmental agents such as hydrogen peroxide, cadmium chloride and γ radiation induced oxidative DNA damage in lymphocytes and within specific DNA sequences of APP (exon 15-18) and PS1 (exon 3-12) genes of AD patients and age-matched control subjects. As indicators of oxidative DNA damage, the frequencies of DNA strand breaks, oxidized pyrimidines and altered purines was assessed using the alkaline Comet assay modified with lesion-specific endonucleases, endo-III and fpg; and fluorescence in situ hybridisation. The number of APP and PS1 hybridisation spots per comet were used as an indicator of the extent of damage. The location of the hybridisation spots in the head or tail of the comet were recorded to further determine whether the gene of interest lies within or in the vicinity of a damaged region of DNA. With the alkaline Comet assay modified with endo-III and fpg, it was demonstrated that patients with AD had significantly increased levels of DNA strand breaks, oxidized pyrimidines and altered purines induced by hydrogen peroxide, cadmium chloride and γ radiation compared with control subjects (p<0.05). This was further confirmed by the fluorescence in situ hybridisation modification of the alkaline Comet assay by demonstrating a significant increase in the mean number of APP and PS1 gene hybridisation spots per comet in AD patients compared with control subjects. Moreover, the gene sensitivity index of APP and PS1 to hydrogen peroxide, cadmium chloride and γ radiation were found to be higher in AD patients than in control subjects. Taken together, our results suggest (i) that lymphocytes from patients with AD are sensitive to these environmental genotoxic agents and (ii) there was an overall increase in the mean number and sensitivity index of APP and PS1 genes to environmental genotoxic agents which might link a genetic cause to oxidative stress in peripheral cells of AD patients than in control subjects. Although the mechanisms by which these environmental agents induced oxidative DNA damage remained to be elucidated, our data suggest that increased oxidative stress is an inherent property of cells carrying genes associated with AD.Dr. H. Abrahamse Mrs. J. V. Hin

Evaluating the electronic tuberculosis register surveillance system in Eden District, Western Cape, South Africa, 2015

BACKGROUND : Tuberculosis (TB) surveillance data are crucial to the effectiveness of National TB Control Programs. In South Africa, few surveillance system evaluations have been undertaken to provide a rigorous assessment of the platform from which the national and district health systems draws data to inform programs and policies. OBJEVTICE : Evaluate the attributes of Eden District’s TB surveillance system, Western Cape Province, South Africa. METHODS : Data quality, sensitivity and positive predictive value were assessed using secondary data from 40,033 TB cases entered in Eden District’s ETR.Net from 2007 to 2013, and 79 purposively selected TB Blue Cards (TBCs), a medical patient file and source document for data entered into ETR.Net. Simplicity, flexibility, acceptability, stability and usefulness of the ETR.Net were assessed qualitatively through interviews with TB nurses, information health officers, sub-district and district coordinators involved in the TB surveillance. RESULTS : TB surveillance system stakeholders report that Eden District’s ETR.Net system was simple, acceptable, flexible and stable, and achieves its objective of informing TB control program, policies and activities. Data were less complete in the ETR.Net (66–100%) than in the TBCs (76–100%), and concordant for most variables except pre-treatment smear results, antiretroviral therapy (ART) and treatment outcome. The sensitivity of recorded variables in ETR.Net was 98% for gender, 97% for patient category, 93% for ART, 92% for treatment outcome and 90% for pre-treatment smear grading. CONCLUSIONS : Our results reveal that the system provides useful information to guide TB control program activities in Eden District. However, urgent attention is needed to address gaps in clinical recording on the TBC and data capturing into the ETR.Net system. We recommend continuous training and support of TB personnel involved with TB care, management and surveillance on TB data recording into the TBCs and ETR.Net as well as the implementation of a well-structured quality control and assurance system.PEPFAR award and Foundation for Professional Development.http://www.tandfonline.com/loi/zgha20am2017School of Health Systems and Public Health (SHSPH

Risk factors for tuberculosis smear non-conversion in Eden district, Western Cape, South Africa, 2007-2013 : a retrospective cohort study

BACKGROUND : Tuberculosis (TB) continues to be a major global health problem. While progress has been made to improve TB cure rates, South Africa’s 76 % smear-positive pulmonary TB (PTB) case cure rate remains below the WHO target of 85 %. We report on the trends of TB smear non-conversion and their predictors at the end of an intensive phase of treatment, and how this impacted on treatment outcomes of smear-positive PTB cases in Eden District, Western Cape Province, South Africa. METHODS : Routinely collected, retrospective data of smear-positive PTB cases from the electronic TB register in Eden District between 2007 and 2013 was extracted. Non-conversion was defined as persistent sputum smear-positive PTB cases at the end of the two or three month intensive phase of treatment. Chi-square test for linear trend and simple linear regression analysis were used to analyse the change in percentages and slope of TB smear non-conversion rates over time. Risk factors for TB non-conversion, and their impact on treatment outcomes, were evaluated using logistic regression models. RESULTS : Of 12,742 total smear-positive PTB cases included in our study, 12.8 % (n = 1627) did not sputum smear convert; 13.3 % (1411 of 10,574) of new cases and 9.9 % (216 of 2168) of re-treatment cases. Although not statistically significant in either new or re-treatment cases, between 2007 and 2013, smear non-conversion decreased from 16.4 to 12.7 % (slope = −0.60; 95 % CI: −1.49 to 0.29; p = 0.142) in new cases, and from 11.3 to 10.8 % in re-treatment cases (slope = −0.29; 95 % CI: −1.06 to 0.48; p = 0.376). Male gender, HIV co-infection and a >2+ acid fast bacilli (AFB) smear grading at the start of TB treatment were independent risk factors for non-conversion (p < 0.001). Age was a risk factor for non-conversion in new cases, but not for re-treatment cases. Non-conversion was also associated with unsuccessful treatment outcomes (p < 0.01), including treatment default and treatment failure. CONCLUSIONS : Smear-positive PTB cases, especially men and those with identified risk factors for non-conversion, should be closely monitored throughout their treatment period. The South African TB control program should invest in patient adherence counselling and education to mitigate TB non-conversion risk factors, and to improve conversion and TB cure rates.This study was supported by PEPFAR funding through CDC South Africa and Foundation for Professional Development.http://www.biomedcentral.com/bmcinfectdis/hb2016School of Health Systems and Public Health (SHSPH

Declines in Lung Function After Antiretroviral Therapy Initiation in Adults With Human Immunodeficiency Virus and Tuberculosis: A Potential Manifestation of Respiratory Immune Reconstitution Inflammatory Syndrome

End-organ impairment has received relatively little research attention as a possible manifestation of tuberculosis immune reconstitution inflammatory syndrome (TB-IRIS). In this prospective cohort study, one-half of adults with human immunodeficiency virus and pulmonary tuberculosis experienced meaningful declines in lung function on antiretroviral therapy, suggesting a role for lung function in TB-IRIS definitions

Transmission of HIV-1 CTL escape variants provides HLA - mismatched recipients with a survival advantage.

One of the most important genetic factors known to affect the rate of disease progression in HIV-infected individuals is the genotype at the Class I Human Leukocyte Antigen (HLA) locus, which determines the HIV peptides targeted by cytotoxic T-lymphocytes (CTLs). Individuals with HLA-B*57 or B*5801 alleles, for example, target functionally important parts of the Gag protein. Mutants that escape these CTL responses may have lower fitness than the wild-type and can be associated with slower disease progression. Transmission of the escape variant to individuals without these HLA alleles is associated with rapid reversion to wild-type. However, the question of whether infection with an escape mutant offers an advantage to newly infected hosts has not been addressed. Here we investigate the relationship between the genotypes of transmitted viruses and prognostic markers of disease progression and show that infection with HLA-B*57/B*5801 escape mutants is associated with lower viral load and higher CD4+ counts

Association of HIV-Specific and Total CD8+ T Memory Phenotypes in Subtype C HIV-1 Infection with Viral Set Point.

Understanding early immunological events during HIV-1 infection that may set the course of disease progression is important for identifying correlates of viral control. This study explores the association of differentiation profiles of HIV-specific and total memory CD8+ T cells with viral set point. A cohort of 47 HIV-1-infected individuals, with differing viral set points at 12 mo, were recruited during acute infection. We identified that the magnitude of IFN-γ+ T cell responses at 6 mo postinfection did not associate with viral set point at 12 mo. A subset of 16 individuals was further studied to characterize CD8+ T cells for expression patterns of markers for memory differentiation, survival (CD127), senescence (CD57), and negative regulation (programmed death-1). We show that viral control and the predicted tempo of HIV disease progression in the first year of infection was associated with a synchronous differentiation of HIV-specific and total CD8+ memory subpopulations. At 6–9 mo postinfection, those with low viral set points had a significantly higher proportion of early differentiated HIV-specific and total memory CD8+ cells of a central memory (CD45RO+CD27+CCR7+) and intermediate memory (CD45RO−CD27+CCR7−) phenotype. Those with high viral set points possessed significantly larger frequencies of effector memory (CD45RO+CD27−CCR7−) cells. The proportions of memory subsets significantly correlated with CD38+CD8+ T cells. Thus, it is likely that a high Ag burden resulting in generalized immune activation may drive differentiation of HIV-specific and total memory CD8+ T cells

Evaluating the electronic tuberculosis register surveillance system in Eden District, Western Cape, South Africa, 2015

Background: Tuberculosis (TB) surveillance data are crucial to the effectiveness of National TB Control Programs. In South Africa, few surveillance system evaluations have been undertaken to provide a rigorous assessment of the platform from which the national and district health systems draws data to inform programs and policies. Objective: Evaluate the attributes of Eden District’s TB surveillance system, Western Cape Province, South Africa. Methods: Data quality, sensitivity and positive predictive value were assessed using secondary data from 40,033 TB cases entered in Eden District’s ETR.Net from 2007 to 2013, and 79 purposively selected TB Blue Cards (TBCs), a medical patient file and source document for data entered into ETR.Net. Simplicity, flexibility, acceptability, stability and usefulness of the ETR.Net were assessed qualitatively through interviews with TB nurses, information health officers, sub-district and district coordinators involved in the TB surveillance. Results: TB surveillance system stakeholders report that Eden District’s ETR.Net system was simple, acceptable, flexible and stable, and achieves its objective of informing TB control program, policies and activities. Data were less complete in the ETR.Net (66–100%) than in the TBCs (76–100%), and concordant for most variables except pre-treatment smear results, antiretroviral therapy (ART) and treatment outcome. The sensitivity of recorded variables in ETR.Net was 98% for gender, 97% for patient category, 93% for ART, 92% for treatment outcome and 90% for pre-treatment smear grading. Conclusions: Our results reveal that the system provides useful information to guide TB control program activities in Eden District. However, urgent attention is needed to address gaps in clinical recording on the TBC and data capturing into the ETR.Net system. We recommend continuous training and support of TB personnel involved with TB care, management and surveillance on TB data recording into the TBCs and ETR.Net as well as the implementation of a well-structured quality control and assurance system

Predictors of male condom use among sexually active heterosexual young women in South Africa, 2012

Abstract Background In South Africa, young women are at disproportionate risk of HIV infection with about 2363 new infections per week in 2015. Proper condom use is one of the most effective HIV/AIDS prevention strategies among sexually active persons. Understanding factors associated with male condom use in this key population group is important to curb the spread of HIV. This study determined practices and predictors of male condom use among sexually active young women in South Africa. Methods The 2012 National HIV Communication Survey measured the extent of exposure to communication activities for HIV prevention among men and women aged 16–55 years in South Africa. We performed a secondary data analysis on a subset of this survey, focussing on 1031 women aged 16–24 years who reported having had sex in the past 12 months. We determined predictors of male condom use using the unconditional multivariable logistic regression model. Results Of the 1031 young women, 595 (57.8%) reported using a male condom at last sex, 68.4% in women aged 16–19 years and 54.5% in women aged 20–24 years (p < 0.001). Delayed sexual debut [20 years or above] (Adjusted Odds Ratio [aOR] 2.1, 95% CI: 1.2 to 3.7, p = 0.006); being a student (aOR 1.6, 95% CI: 1.2 to 2.3, p = 0.005); and exposure to HIV communication programmes (aOR 3.1, 95% CI: 1.2 to 8.6, p = 0.025) were significantly associated with male condom use at last sex. Conclusion Male condom use was a common practice among young women and was associated with delayed sexual debut and exposure to HIV communication programmes. Behavioral interventions and HIV communication programmes should therefore encourage young women to delay initiation of sex and promote usage of male condoms

Human immunodeficiency virus-specific gamma interferon enzyme-linked immunospot assay responses targeting specific regions of the proteome during primary subtype C infection are poor predictors of the course of viremia and set point.

It is unknown whether patterns of human immunodeficiency virus (HIV)-specific T-cell responses during acute infection may influence the viral set point and the course of disease. We wished to establish whether the magnitude and breadth of HIV type 1 (HIV-1)-specific T-cell responses at 3 months postinfection were correlated with the viral-load set point at 12 months and hypothesized that the magnitude and breadth of HIV-specific T-cell responses during primary infection would predict the set point. Gamma interferon (IFN-gamma) enzyme-linked immunospot (ELISPOT) assay responses across the complete proteome were measured in 47 subtype C HIV-1-infected participants at a median of 12 weeks postinfection. When corrected for amino acid length and individuals responding to each region, the order of recognition was as follows: Nef > Gag > Pol > Rev > Vpr > Env > Vpu > Vif > Tat. Nef responses were significantly (P < 0.05) dominant, targeted six epitopic regions, and were unrelated to the course of viremia. There was no significant difference in the magnitude and breadth of responses for each protein region with disease progression, although there was a trend of increased breadth (mean, four to seven pools) in rapid progressors. Correlation of the magnitude and breadth of IFN-gamma responses with the viral set point at 12 months revealed almost zero association for each protein region. Taken together, these data demonstrate that the magnitude and breadth of IFN-gamma ELISPOT assay responses at 3 months postinfection are unrelated to the course of disease in the first year of infection and are not associated with, and have low predictive power for, the viral set point at 12 months