Oral Microbiome Signatures in Diabetes Mellitus and Periodontal Disease.

Disturbances in the oral microbiome are associated with periodontal disease initiation and progression and diabetes mellitus (DM), but how this contributes to the cause-and-effect relationship between periodontal disease and DM is poorly understood. We examined the bacterial composition in plaque samples from 128 South Africans with periodontal disease across glycemic statuses using 16S rDNA sequencing of regions 2, 3, 4, 6-7, 8, and 9. Of the 9 phyla identified, Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, and Actinobacteria made up >98%. Fusobacteria and Actinobacteria were significantly more abundant in subjects with diabetes, while Proteobacteria were less abundant. However, in the presence of gingival bleeding and DM, as compared with DM without gingival bleeding, Actinobacteria were markedly reduced while Bacteroidetes were more abundant. In contrast, no differences in Actinobacteria or Bacteroidetes abundance were observed between DM with and without pocket depth (PD) ≥4 mm. At the genus level, similar changes in relative abundance were observed in the presence of DM and periodontal disease. Our findings remained in conditional logistic regression models adjusted for age, sex, waist circumference, and the 5 most dominant phyla. For example, Actinobacteria significantly increased the odds of diabetes by 10% in subjects with gingival bleeding, while Fusobacteria increased this odd by 14%; yet, among subjects with PD ≥4 mm, Fusobacteria decreased the odds of DM by 47%. Our findings have confirmed the alterations in the composition of the oral microbiota across glycemic statuses as well as different stages of periodontal disease. However, it is not clear whether these differences were the consequence of hyperglycemia or the presence of periodontal diseases. Therefore, we recommend further investigations in a longitudinal study design.

Measured Versus Calculated Small Dense LDL-Cholesterol and Cardiometabolic Traits in a South African Population.

Small-dense low density lipoprotein (sdLDL) is increasingly viewed as a marker for evaluating atherogenic risk, however its clinical uptake is hampered by the cumbersomeness of available methods. Consequently, a number of alternative methods for the estimation of sdLDL have been developed and none have been tested in a population from Africa. We evaluated an equation to estimate sdLDL-C from classic lipid parameters in South Africans. This is a cross-sectional study involving 1550 participants in which direct measurement of sdLDL in 237 participants was performed using a homogeneous enzymatic assay. Their mean age (standard deviation, SD) was 54.2 (14.7) years. 156 (65.8%) were normotolerant, 29 (12.2%) prediabetes, 17 (7.2%) screen detected diabetes and 35 (14.8%) known diabetes. Measured sdLDL values ranged from 0.17 to 3.39 versus-1.85 to 2.52 mmol/L calculated sdLDL. There was a significant positive correlation between the two measurements with a Pearson correlation coefficient of 0.659 (95%CI: 0.581-0.726). In a regression model, the adjusted R2 was 0.440 after adding age, 0.441 after further adding gender, then 0.443 with dysglycemia and lastly 0.447 upon adding body mass index. With the exception of HDL-cholesterol levels that decreased across increasing quintiles of calculated sdLDL, our data showed significant correlations between sdLDL and cardiometabolic risk factors, all p values < 0.0001. In conclusion, this study has shown that calculated sdLDL can be efficiently used to approximate population levels of sdLDL; however the modest correlation indicate that at the individual level, it will poorly approximate true sdLDL levels, with possible implications for risk stratification.

Increase in blood pressure over a 7-year period in a mixed-ancestry South African population.

BACKGROUND: An increase in the prevalence of high blood pressure (BP) has been reported globally and in the South African (SA) population. OBJECTIVES: To investigate temporal changes in absolute BP levels and hypertension prevalence in the mixed-ancestry South Africans. METHODS: Participants were from two independent cross-sectional surveys conducted during 2008/09 (N=928) and 2014/16 (N=1 969) in Bellville South, Cape Town, SA. Participants' eligibility was based on several criteria, including age >20 years and neither bedridden nor pregnant. Data were obtained by administered questionnaires, clinical measurements (BP and anthropometry) and biochemical assessments (oral glucose tolerance tests and cotinine levels). Known hypertension was based on a self-reported history of doctor-diagnosed hypertension and ongoing treatment. Comparison across years was based on the crude prevalence of hypertension as well as direct age-standardised prevalence, based on the SA 2011 mixed-ancestry population distribution, in 10-year age increments. RESULTS: In all, 708 participants (76.3%) in 2008/09 and 1 488 (75.6%) in 2014/16 were female. Between 2008/09 and 2014/16, mean systolic BP increased from 124 to 136 mmHg (absolute mean difference 15 mmHg) and mean diastolic BP from 75 to 85 mmHg (absolute mean difference 9 mmHg) in the overall sample. The prevalence of screen-detected hypertension increased from 11.6% to 24.8%, with a similar increase in males and females, while the prevalence of known cases remained stable. These changes remained significant after adjustment for age and gender. CONCLUSIONS: A rightward shift in absolute BP translated into a significant increase in the prevalence of hypertension over time in this population. The predominant increases in screen-detected hypertension suggest that the deteriorating profile was not matched by efforts to detect and manage individuals with higher-than-optimal BP levels.

Waist circumference percentiles of black South African children aged 10 - 14 years from different study sites

Background. Waist circumference (WC) is a useful predictor of cardiometabolic risk in children. Published data on WC percentiles of children from African countries are limited.Objectives. To describe age- and sex-specific Wpercentiles in black South African (SA) children from different study sites, and compare these percentiles with median WCpercentiles of African-American (AA) children.Methods. Secondary data on WC for 10 - 14-year-old black SA children (N=4 954; 2 406 boys and 2 548 girls) were extracted from the data sets of six studies. Smoothed WC percentile curves for boys and girls were constructed using the LMS method. The 50th percentile for age- and sex-specific WC measurements was compared across study sites and with AA counterparts.Results. Girls had higher WC values than boys from the 50th to 95th percentiles at all ages. The 50th WC percentiles of all groups of SA children combined were lower than those of AA children. When SA groups were considered separately, Western Cape children had median WC values similar to AA children, while rural Limpopo children had the lowest WC values. The 95th percentiles for Western Cape girls exceeded the adult cutoff point for metabolic syndrome (WC ≥80 cm) from age 11years.Conclusions. The differences in WC values for 10 - 14-year-old children across the six study sites highlight the need for nationally representative data to develop age-, sex- and ethnic-specific WC percentiles for black SA children. The results raise concerns about high WC among Western Cape girls

Genetic association studies of obesity in Africa: a systematic review.

Obesity is increasing in Africa, but the underlying genetic background largely remains unknown. We assessed existing evidence on genetic determinants of obesity among populations within Africa. MEDLINE and EMBASE were searched and the bibliographies of retrieved articles were examined. Included studies had to report on the association of a genetic marker with obesity indices and the presence/occurrence of obesity/obesity trait. Data were extracted on study design and characteristics, genetic determinants and effect estimates of associations with obesity indices. According to this data, over 300 polymorphisms in 42 genes have been studied in various population groups within Africa mostly through the candidate gene approach. Polymorphisms in genes such as ACE, ADIPOQ, ADRB2, AGRP, AR, CAPN10, CD36, C7orf31, DRD4, FTO, MC3R, MC4R, SGIP1 and LEP were found to be associated with various measures of obesity. Of the 36 polymorphisms previously validated by genome-wide association studies (GWAS) elsewhere, only FTO and MC4R polymorphisms showed significant associations with obesity in black South Africans, Nigerians and Ghanaians. However, these data are insufficient to establish the true nature of genetic susceptibility to obesity in populations within Africa. There has been recent progress in describing the genetic architecture of obesity among populations within Africa. This effort needs to be sustained via GWAS studies.

Paraoxonase1 genetic polymorphisms in a mixed ancestry African population.

Paraoxonase 1 (PON1) activity is markedly influenced by coding polymorphisms, Q/R at position 192 and M/L at position 55 of the PON1 gene. We investigated the frequencies of these polymorphisms and their effects on PON1 and antioxidant activities in 844 South African mixed ancestry individuals. Genotyping was done using allele-specific TaqMan technology, PON1 activities were measured using paraoxon and phenylacetate, oxidative status was determined by measuring the antioxidant activities of ferric reducing antioxidant power and trolox equivalent antioxidant capacity, and lipid peroxidation markers included malondialdehyde and oxidized LDL. The frequencies of Q192R and L55M were 47.6% and 28.8%, respectively, and the most common corresponding alleles were 192R (60.4%) and 55M (82.6%). The Q192 was significantly associated with 5.8 units' increase in PON1 concentration and 15.4 units' decrease in PONase activity after adjustment for age, sex, BMI, and diabetes, with suggestion of differential effects by diabetes status. The PON1 L55 variant was associated with none of the measured indices. In conclusion, we have shown that the Q192R polymorphism is a determinant of both PON1 concentration and activity and this association appeared to be enhanced in subjects with diabetes.

Rare mutations of peroxisome proliferator-activated receptor gamma: frequencies and relationship with insulin resistance and diabetes risk in the mixed ancestry population from South Africa.

Background. Genetic variants in the nuclear transcription receptor, PPARG, are associated with cardiometabolic traits, but reports remain conflicting. We determined the frequency and the clinical relevance of PPARG SNPs in an African mixed ancestry population. Methods. In a cross-sectional study, 820 participants were genotyped for rs1800571, rs72551362, rs72551363, rs72551364, and rs3856806, using allele-specific TaqMan technology. The homeostatic model assessment of insulin (HOMA-IR), ß-cells function (HOMA-B%), fasting insulin resistance index (FIRI), and the quantitative insulin-sensitivity check index (QUICKI) were calculated. Results. No sequence variants were found except for the rs3856806. The frequency of the PPARG-His447His variant was 23.8% in the overall population group, with no difference by diabetes status (P = 0.215). The His447His allele T was associated with none of the markers of insulin resistance overall and by diabetes status. In models adjusted for 2-hour insulin, the T allele was associated with lower prevalent diabetes risk (odds ratio 0.56 (95% CI 0.31-0.95)). Conclusion. Our study confirms the almost zero occurrences of known rare PPARG SNPs and has shown for the first time in an African population that one of the common SNPs, His447His, may be protective against type 2 diabetes.

Indices of paraoxonase and oxidative status do not enhance the prediction of subclinical cardiovascular disease in mixed-ancestry South Africans.

We evaluated the association of indices of paraoxonase (PON1) and oxidative status with subclinical cardiovascular disease (CVD) in mixed-ancestry South Africans. Participants were 491 adults (126 men) who were stratified by diabetes status and body mass index (BMI). Carotid intima-media thickness (CIMT) was used as a measure of subclinical CVD. Indices of PON1 and oxidative status were determined by measuring levels and activities (paraoxonase and arylesterase) of PON1, antioxidant activity (ferric reducing antioxidant power and trolox equivalent antioxidant capacity), and lipid peroxidation markers (malondialdehyde and oxidized LDL). Diabetic subjects (28.9%) displayed a significant decrease in PON1 status and antioxidant activity as well as increase in oxidized LDL and malondialdehyde. A similar profile was apparent across increasing BMI categories. CIMT was higher in diabetic than nondiabetic subjects (P < 0.0001) but showed no variation across BMI categories. Overall, CIMT correlated negatively with indices of antioxidant activity and positively with measures of lipid oxidation. Sex, age, BMI, and diabetes altogether explained 29.2% of CIMT, with no further improvement from adding PON1 and/or antioxidant status indices. Though indices of PON1 and oxidative status correlate with CIMT, their measurements may not be useful for identifying subjects at high CVD risk in this population.

Three-year's changes in glucose tolerance status in the Bellville South cohort: rates and phenotypes associated with progression.

AIMS: To determine the phenotypes associated with progression to type 2 diabetes or worsening in glucose tolerance during a 3-year follow-up of a community-based cohort in Cape Town, South Africa. METHODS: A total of 198 eligible subjects (72.3% women) aged 55.2 years, from the Bellville-South community were followed-up between 2008 and 2011. Baseline and follow-up data collections included glucose tolerance status, anthropometric, blood pressure, lipids, insulin, γ-glutamyltransferase, cotinine, creatinine and HbA1c. Progression in glucose tolerance status at 3-year was the composite of new-onset diabetes and any worsening in glucose tolerance status. RESULTS: The cumulative incidence of progression in glucose tolerance status was: 16.2% (32 participants including 11 with new-onset diabetes), and increased in a stepwise fashion with the number of components of metabolic syndrome (MetS). In age and sex-adjusted logistic regression analyses, MetS [odd ratio: 3.08 (95% CI: 1.34-7.10)], HbA1c [5.26 (1.94-14.24)], HDL-cholesterol [0.05 (0.01-0.33)], γ-glutamyltransferase [1.99 (1.07-3.67)], triglycerides [1.71 (1.13-2.58)] and total/HDL-cholesterol [1.45 (1.08-1.93)] were significant predictors of progression, while borderline effects were observed for baseline glucose and diastolic blood pressure. Markers of adiposity were mostly stable or improved among non-progressors during follow-up, but deteriorated significantly among progressors, resulting in significant statistical interactions. CONCLUSIONS: High rates of deterioration of glucose status over time were found in our population, with nearly one-fifth of them acquiring a glucose tolerance worse status within a very short follow-up. Our study extends to this setting the well-known utility of phenotypes of MetS single or in combination, in predicting worsening in glucose tolerance status.

The 30-year cardiovascular risk profile of South Africans with diagnosed diabetes, undiagnosed diabetes, pre-diabetes or normoglycaemia: the Bellville, South Africa pilot study.

The aim of this pilot study was to assess the 30-year risk for cardiovascular disease (CVD) in the South Africa population of mixed-ancestry in individuals with non-diabetic hyperglycaemia, and undiagnosed and self-reported diabetes. Participants were drawn from an urban community of the Bellville South suburb of Cape Town. In total, 583 subjects without a history of CVD were eligible for lifetime CVD risk estimation. Gender-specific prediction for CVD risk was calculated using the 30-year CVD interactive risk calculator. High CVD risk (> 20%) was evident in normoglycaemic and younger subjects (under 35 years). The significant predictors of CVD were sibling history of diabetes, and triglyceride, low-density lipoprotein cholesterol and glycated haemoglobin levels (p < 0.001). The high lifetime risk in normoglycaemic and younger subjects may be considered a warning that CVD might take on epidemic proportions in the near future in this country. We recommend the inclusion of education on CVD in school and university curricula.

Association of cocaine- and amphetamine-related transcript, leptin and leptin receptor gene polymorphisms with anthropometric obesity phenotype indicators in South African learners.

BACKGROUND/AIMS: Obesity has increased rapidly in South African children and adolescents. Genes involved in appetite regulation have been extensively studied worldwide, but their role in the obesity phenotype in South African Black and mixed-ancestry school adolescents is unknown. METHODS: Seven common polymorphisms in LEP, GHRL, CART and LEPR were analysed for genotype and haplotype association with anthropometric obesity phenotype indicators in South African Black and mixed-ancestry adolescent school learners. RESULTS: The CART c.517A→G polymorphism was significantly associated with obesity susceptibility. The LEPR Lys(109)Arg G allele was associated with an average reduction of 2.36 kg/m(2) in body mass index (BMI), 5.66 cm in waist circumference (WC) and 1.61 cm in mid-upper-arm circumference (MUAC). This was confirmed by haplotype analysis. Additionally, a haplotype of the LEP polymorphisms significantly increased BMI, MUAC and hip circumference, while LEPR haplotypes were associated with differences in MUAC. CONCLUSION: Our findings suggest that c.517A→G and Lys(109)Arg contribute to the variation in anthropometric obesity phenotype indicators observed among Black African and mixed-ancestry South African learners. Furthermore, haplotypes of LEP, LEPR and GHRL polymorphisms were associated with varying measurements of weight, BMI and WC. Further studies are required to confirm our results in a larger and homogeneous study population group.

Association of the ENPP1 rs997509 polymorphism with obesity in South African mixed ancestry learners.

BACKGROUND: The Ectonucleotide Pyrophosphatase Phosphodiesterasel (ENPP1) polymorphisms have been associated with metabolic traits. There is no data on the effect of ENPP1 in South African children or adults. OBJECTIVE: To investigate the role of K121Q (rs1044498), rs997509 and rs9402349 in obesity and other components of the metabolic syndrome. DESIGN: A case-control study. SUBJECTS: Sixty four obese and 64 lean mixed ancestry learners. SETTING: Western Cape, South Africa. MAIN OUTCOME MEASURE: The ENPP1 rs997509T allele is independently associated with obesity in children of mixed ancestry from South Africa. RESULTS: The T allele frequency of the rs997509 differed significantly between obese and controls, p=0.0100 and increased the risk of being obese, p = 0.0238. Furthermore, the estimated effect of the T allele was an increase of 8.6 cm in waist circumference, 10.2 kg in weight and a corresponding 4.9 kg/m2 in BMI. Individuals carrying both the 121Q and the T allele of rs997509 were more associated with obesity (odds ratio = 3.85, 95% CI: 1.13 to 13.09) whilst those carrying the C allele of rs997509 in the presence of 121Q were likely to be lean with odds ratio of obesity 0.41 (95% CI: 0.19 to 0.87). CONCLUSION: Our findings suggest that ENPP1 polymorphisms may contribute to different metabolic characteristics, all of which are associated with insulin resistance in mixed ancestry children of South Africa. However, a larger study is required to confirm findings of this study.

Membrane saturated fatty acids and disease progression in multiple sclerosis patients.

The risk of developing multiple sclerosis is associated with increased dietary intake of saturated fatty acids. We determined the fatty acid composition within the different phospholipid fractions of red blood and peripheral blood mononuclear cell membranes of 31 patients diagnosed with multiple sclerosis and 30 healthy control subjects using gas chromatography. Individual saturated fatty acids were correlated with the severity of neurological outcome as measured by the Kurtzke Expanded Disability Status Scale. Significant increases were found in multiple sclerosis peripheral blood mononuclear cell membrane sphingomyelin C14:0 and phosphatidylinositol C22:0. In the peripheral blood mononuclear cell membranes, C22:0 and C24:0 showed positive correlations, while C14:0, C16:0 and C20:0 showed inverse correlations with the Functional System Scores. In conclusion, this study is in accordance with previous studies that have shown an increase in shorter long-chain SATS in MS patients. In addition, this study also showed that higher C14:0 and C16:0 reflected better disease outcome as demonstrated by the inverse correlation with the EDSS and FSS. We have also characterized the specific SATS, that is, long-chain SATS that may increase the risk of developing MS.

Erythrocyte membrane fatty acids in patients with multiple sclerosis.

BACKGROUND: Reports on fatty acids levels in multiple sclerosis remain inconclusive. OBJECTIVE: To determine the erythrocyte membrane fatty acid levels in multiple sclerosis patients and correlate with Kurtzke Expanded Disability Status Scale. METHODS: Fatty acid composition of 31 multiple sclerosis and 30 control individuals were measured by gas chromatography. RESULTS: The membrane phosphatidylcholine C20:4n - 6 concentration was lower in the multiple sclerosis patients when compared to that of the control group, P = 0.04 and it correlated inversely with the EDSS and FSS. CONCLUSION: Decrease in C20:4n - 6 in the erythrocyte membrane could be an indication of depleted plasma stores, and a reflection of disease severity.

Expression of p53 and its homolog, p73, in HPV DNA positive oesophageal squamous cell carcinomas.

Several studies have detected human papilloma virus (HPV) DNA in squamous cell carcinoma of the oesophagus (OSCC). In this study, we analysed OSCC specimens from 114 patients for the presence of HPV DNA, and p53 and p73 expression. HPV DNA was detected in 44.7% of cases, with the low risk HPV11 occurring most frequently. p53 and p73 expression was detected in 70% and 61.4% of cases, respectively. There was no correlation between expression of p53, p73 or HPV infection and tumour grade, or between p53 expression and the presence of HPV DNA. There was, however, significant correlation between p73 expression and the presence of HPV DNA (p<0.01) and p53 and p73 co-expression (p<0.001), as well as co-expression of p53 and p73 with HPV status (p<0.05). These data support previous studies suggesting a role for HPV infection in OSCC and also indicate that HPV infection and p53 and p73 overexpression are not mutually exclusive. In addition, the data implicate a role for p73 in OSCC and suggest a complex interaction between p53, p73 and HPV in the aetiology of the disease.

Iron and the folate-vitamin B12-methylation pathway in multiple sclerosis.

UNLABELLED: Some subjects with multiple sclerosis (MS) present with low blood iron parameters. Anecdotal reports and a single patient study suggest that iron supplementation may be beneficial in these subjects. Myelin is regenerated continually, but prerequisites for this process are iron and a functional folate-vitamin B12-methylation pathway. The aim of this study was to determine iron status, folate and homocysteine in MS subjects, and to evaluate the effect on MS symptoms if deficiencies were addressed. RESULTS: In relapsing-remitting MS subjects, serum iron concentration correlated significantly with age at diagnosis (r=0.49; p=0.008). In Caucasian female MS subjects, serum iron and ferritin concentrations were significantly lower than in matched controls. In a 6-month pilot study, 12 subjects taking a regimen of nutritional supplements designed to promote myelin regeneration, improved significantly neurologically as measured by the Kurzke EDSS (Total Score means 3.50 to 2.45, 29.9%; p=0.021). These were significantly improved (p=0.002) compared to 6 control group patients taking multivitamins (Kurzke Score increased by 13.9% from 4.83 to 5.50). Both groups had significantly reduced homocysteine concentrations at 6 months, suggesting that methylation is necessary but not sufficient for myelin regeneration.

Self-induced vomiting -- risk for oesophageal cancer?

BACKGROUND: Chronic inflammation of the oesophagus is considered a precursor condition for the development of oesophageal cancer. Identification of the causes of chronic oesophageal irritation is therefore relevant in developing preventive measures. Self-induced vomiting is a cultural practice among the black population of South Africa, particularly those living in the Transkei, a region reported to have one of the highest incidences of oesophageal cancer worldwide. METHODS: We retrospectively examined the association between the practice of self-induced vomiting and the development of cytological features of inflammation in 478 self-selected subjects living in Transkei who underwent early screening for oesophageal cancer. Screening involved brush biopsy, cytological investigation and a questionnaire interview. RESULTS: The prevalence of self-induced vomiting was 80.5% and 79.1% in males and females, respectively, and this was stable across all ages. Furthermore, self-induced vomiting was found to be significantly and independently associated with oesophageal chronic inflammation (odds ratio 1.83, 95% confidence interval: 1.13 - 2.96, p = 0.013). CONCLUSION: While the association between the cultural practice of self-induced vomiting and oesophageal cancer has previously been hypothesised, this is the first study to report on an association between this practice and oesophageal chronic inflammation. Further studies that take into account the method used, frequency and duration of vomiting, age of commencement and fasting state of subjects practicing self-induced vomiting coupled with accurate indicators of inflammation are needed to elucidate the role of self-induced vomiting in oesophageal pathogenesis.

Human papillomavirus associated with oesophageal cancer.

AIM: To study the prevalence and the different types of human papillomavirus (HPV) in patients with oesophageal cancer from a high risk area of South Africa (Transkei). METHODS: DNA samples from 50 paraffin wax embedded tissue sections were analysed by nested polymerase chain reaction (PCR) using the degenerate HPV L1 consensus primer pairs MY09/MY11 and GP5+/GP6+. Positive PCR samples were subjected to DNA sequence analysis. RESULTS: HPV DNA was detected in 23 of the 50 samples. Sequence analysis revealed that most patients (11) harboured DNA to HPV type 11, whereas other types included DNA HPV type 39 (seven patients), type 16 (two patients), and type 52 (one patient). HPV type 39 has not previously been shown to be associated with oesophageal cancer. In contrast to earlier studies that have found HPV type 16 to be more frequently associated with oesophageal cancer, HPV type 11 was the predominant subtype in this study. CONCLUSIONS: The high frequency of occurrence of HPV in oesophageal tumours (23 of 50 patients; 46%) implicates HPV as one of the possible aetiological factors in this disease. The finding that the low risk HPV subtypes predominate indicates that transformation may be effected via the E6 and E7 proteins.