Whole blood Fe isotopic signature in a sub-Saharan African population.

The Fe isotopic composition of an individual's whole blood has recently been shown to be an interesting clinical indicator of Fe status. The present study aimed to evaluate the influence of several endemic characteristics of a representative population of the South Kivu province, an Fe-rich volcanic African region, on the whole blood Fe isotopic composition. Both diabetes mellitus and the ferroportin Q248H mutation are very common in Africa and are strongly associated with impairments in Fe metabolism. Fe isotopic analysis of whole blood samples was carried out using multi-collector inductively coupled plasma-mass spectrometry (after chromatographic isolation of the target element). Forty-two male subjects (between 48 and 59 years old) living in Bukavu (South Kivu) were enrolled in this study. Among the selected population, wild-type subjects and subjects presenting the ferroportin Q248H mutation (heterozygotes and homozygotes) were included. Within each group, diabetic and non-diabetic patients were considered. The whole blood δ56Fe value ranged from -3.09‰ to -2.41‰. The δ56Fe value shows a significant negative correlation with the ferritin concentration. No correlation could be established between the whole blood δ56Fe value and the transferrin concentration, transferrin saturation or serum Fe concentration. The ferroportin Q248H mutation did not seem to have affected the whole blood Fe isotopic signature. The whole blood δ56Fe values were significantly higher in diabetic subjects than in non-diabetic subjects and showed a significant negative correlation with body mass index (BMI) values.

A simple colorimetric assay for measuring fructosamine 3 kinase activity.

BACKGROUND: Fructosamine 3 kinase (FN3K) is a deglycating enzyme, which may play a key role in reducing diabetes-induced organ damage by removing bound glucose from glycated proteins. We wanted to develop a simple colorimetric method for assaying FN3K activity in human body fluids. METHODS: Glycated bovine serum albumin (BSA) was obtained by glycation with a 10% glucose solution at 37 °C. After 72 h, glycated BSA was dialyzed against phosphate buffered saline (0.1 mol/L, pH 7.4). The dialyzed solution (containing ±1000 µmol/L fructosamine) was used as an FN3K substrate. In the assay, 300 µL of substrate was incubated with 50 µL of serum and 100 µL of MgCl2 (0.7 mmol/L)/ATP (3.2 mmol/L). The fructosamine concentration was determined at the start and after incubation (120 min, 25 °C). The decrease in fructosamine concentration over time is a measure for the FN3K activity (1 U corresponding to 1 µmol/min). Concomitantly, the FN3K SNP rs1056534 and the ferroportin SNP rs1156350 were genotyped. RESULTS: Within-assay CV was 6.0%. Reference values for FN3K activity in serum were 14.2±1.6 U/L (n=143). Reference values for FN3K were neither age- nor sex-dependent. The various FN3K SNP rs1056534 genotypes showed no significant differences in serum FN3K activity. In diabetics (n=191), values (14.0±2.2 U/L) were comparable to those of the controls. FN3K activity in erythrocytes was significantly higher (170.3±7.6 U/L). The intra-erythrocytic FN3K activity makes the results prone to hemolysis. FN3K activity depended on the ferroportin Q248H genotypes, with the highest value for the wild type genotype. Neither transferrin saturation nor ferritin were confounders for the FN3K activity. FN3K activity was significantly (p<0.0001) correlated with HbA1c values, although the correlation between FN3K and HbA1c was weak. CONCLUSIONS: The simple colorimetric method allows determining FN3K activity in human serum. The assay may be useful for studying the impact of deglycation processes in diabetes mellitus.

The association between fructosamine-3 kinase 900C/G polymorphism, transferrin polymorphism and human herpesvirus-8 infection in diabetics living in South Kivu.

Prevalences of human herpesvirus-8 (HHV-8) infection and diabetes mellitus are very common in certain parts of Africa, containing iron-rich soils. We hypothesized that some genetic factors could have a link with susceptibility to HHV-8 infection. We focused on ferroportin Q248H mutation (rs11568350), transferrin (TF) polymorphism and fructosamine-3 kinase (FN3K) 900C/G polymorphism (rs1056534). The study population consisted of 210 type 2 diabetic adults and 125 healthy controls recruited in Bukavu (South Kivu). In the whole study population (diabetics+healthy controls), ferroportin Q248H mutation was detected in 47 subjects (14.0%) with 43 heterozygotes and 4 homozygotes. TF phenotype frequencies were 88.1% (CC), 10.4% (CD) and 1.5% (BC). Genotype frequencies of FN3K 900C/G polymorphism were respectively 9,3% (CC), 43.3% (GC) and 47.4% (GG). Prevalence of HHV8-infection in the study population was 77.3%. HHV-8 infection rate and HHV-8 IgG antibody titer were significantly higher in diabetics then in controls (p<0.0001). Significant differences were observed in HHV-8 infection rate and in HHV-8 IgG antibody titer according to FN3K rs1056534 (p<0.05 and p<0.05, respectively) and TF polymorphism (p<0.05 and p=0.005, respectively). No significant differences in HHV-8 infection rate and in HHV-8 IgG antibody titer were observed in the ferroportin Q248H mutation carriers (rs11568350) in comparison with ferroportin wild type. In a multiple regression analysis, FN3K rs1056534, TF polymorphism and presence of diabetes mellitus were predictors for HHV-8 infection. In contrast to these findings, ferroportin Q248H mutation (rs11568350) did not influence the susceptibility for an HHV-8 infection in sub-Saharan Africans.

Glycated nail proteins as a new biomarker in management of the South Kivu Congolese diabetics.

INTRODUCTION: Diagnosis and monitoring of diabetes mellitus in sub-Saharan Africa, based on blood analyses, are hampered by infrastructural and cultural reasons. The first aim of this study was to evaluate the diagnostic accuracy of glycated nail proteins for diabetes mellitus. The second aim was to compare the course of short- and long-term glycemic biomarkers after 6 months of antidiabetic treatment. These objectives should support our hypothesis that glycated nail proteins could be used as an alternative glycemic biomarker. MATERIALS AND METHODS: This case-control study consisted of 163 black diabetics and 67 non-diabetics of the South Kivu (Democratic Republic of Congo). Diagnostic accuracy of glycated nail proteins was evaluated using ROC curve analysis. At the start of the study, glycated nail protein concentrations were compared between diabetics and non-diabetics, using a nitro blue tetrazolium (NBT) colorimetric method. In a subgroup of 30 diabetics, concentrations of glycated nail proteins, fasting glucose (Accu-Chek® Aviva), serum fructosamine (NBT) and HbA1c (DCA-2000+®) were measured at start and after 6 months. RESULTS: ROC analysis yielded an AUC of 0.71 (95% confidence interval (CI): 0.65-0.76) and a cut-off point of 3.83 µmol/g nail. Concentration of glycated nail proteins was significantly higher (P<0.001) in diabetics in comparison with non-diabetics. After 6 months of antidiabetic treatment, a significant drop in the fasting glucose concentration (P=0.017) and concentration of glycated nail proteins (P=0.008) was observed in contrast to serum fructosamine and HbA1c. CONCLUSIONS: Measurement of glycated nail proteins could be used to diagnose and monitor diabetes mellitus in sub-Saharan Africa.

[Hypertension in the adult Congolese population of Southern Kivu: Results of the Vitaraa Study]. / Hypertension artérielle chez l'adulte Congolais du Sud Kivu : résultats de l'étude Vitaraa.

OBJECTIVE: To assess the prevalence of cardiovascular risk factors in adult urban and rural Congolese subjects. METHODS: We obtained anthropometric data and information on life habits and medical history in 699 people ≥ 20 years, 444 in an urban, 255 in a rural setting. We determined the body mass index and recorded two blood pressure measurements that were averaged for analysis. Hypertension was BP ≥ 140/90mmHg, awareness and/or use of antihypertensive treatment. Diabetes mellitus was self-reported diagnosis or a casual glycemia ≥ 200mg/dL. We assessed the probability of hypertension in stepwise multiple logistic analysis, and awareness, and control of hypertension. RESULTS: We found higher (P<0.001) prevalence in the urban than the rural subjects for hypertension (41.4% vs 38.1%), diabetes (4.9% vs 3.2%), overweight/obesity (37.6% vs 16.5%), abdominal obesity (30.9% vs 12.9%), use of alcohol (45% vs 17.6%) and smoking (11.6% vs 1.2%). Hypertension was associated (P<0.05) to aging in 51.3%, overweight/obesity in 54.5%, diabetes in 69%, abdominal obesity in 63.8%, low physical activity in 42.4%, to stress in urban environment in 43.2% and professional position (executives: 53.2%, workers: 38.6%). Of these hypertensive subjects, 57.5% were unaware, 30.5% were treated, with control achieved in only 13.6% (17.4% women vs 6.9% men; P<0.01). In the logistic model, the probability of hypertension increased with age (OR for age>55 years: 2.35; P<0.001), overweight/obesity (2.22; P<0.001) and diabetes mellitus (2.67; P<0.05). CONCLUSIONS: Our results indicate a heavy burden of uncontrolled risk factors in the Congolese population the potential complications of which run at a high mortality rate. They highlight the need for reasonable prevention measures at the population level.