Masters Degrees (Chemical Pathology)

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Browsing Masters Degrees (Chemical Pathology) by browse.metadata.advisor "Erasmus, Rajiv T."

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    The association between vitamin D, vitamin D Binding proteins and VDR polymorphisms in diabetic and non-diabetic patients
    (Stellenbosch : Stellenbosch University, 2019-03) Maepa, Setjie Welcome; Matsha, Tandi E.; Erasmus, Rajiv T.; Stellenbosch University. Faculty of Medicine and Health Science. Dept. of Pathology. Chemical Pathology.
    ENGLISH ABSTRACT: Introduction: Type 2 diabetes mellitus (T2DM) is by far the most prevalent form of diabetes manifesting with insulin resistance (IR), abnormal pancreatic β-cell function and hyperglycaemia. Evidence from epidemiological and observational studies have shown that vitamin D deficiency is associated with increased risk for T2DM although the findings are inconsistent and inconclusive. In the circulation vitamin D is transported bound to vitamin D binding protein (VDBP), evidence showed that vitamin D levels are positively associated with VDBP levels. Several genes such as vitamin D receptor gene (VDR), involved in the metabolic pathway of T2DM have been considered good candidate for susceptibility to T2DM. The present study aimed to investigate the association between vitamin D, vitamin D binding proteins (VDBP) and vitamin D receptor (VDR) polymorphisms in T2DM and non-diabetic patients in the mixed ancestry population. Materials and methods: The current study comprised of 1603 participants (387 males and 1216 females). Vitamin D levels were measured using the paramagnetic particle chemiluminescence test on a Beckman DXI. Vitamin D binding protein (VDBP) in serum samples was measured using the Human Vitamin D BP Quantikine ELISA kit. Fok1 (rs2228570), Apa1 (rs7975232) and Taq1 (rs731236) single nucleotide polymorphisms (SNPs) of the VDR gene were genotyped from a genomic DNA using the TaqMan SNP Genotyping Assays and were confirmed by direct sequencing. Results: Vitamin D deficiency (44%) and insufficiency (42.6%) were highly prevalent and optimal 25(OH)D levels were very low with only 13% having optimal levels. The overall vitamin D status of the whole population group was insufficient (22.0±7.6 ng/mL). 25(OH)D levels and serum VDBP varied according to gender with males having higher 25(OH)D levels (23.6±7 vs 21.5±7.5ng/mL, P=0.0006) and females with significantly higher serum VDBP levels (299.1±71.2 vs 315.9±76.1 µg/mL, P<0.0001). 25(OH)D levels were generally significantly decreased in the hyper-glycemic subgroups. Screen-detected DM males had low 25(OH)D levels compared to normoglycaemic group (17.0±6.1vs 24.2±8.2, P=0.0214). A similar trend was observed in the female groups (21.1±6.0 vs 22.4±7.9, P=0007). Anthropometric measurements including the BMI (kg/m2), Waist C (cm) and Hip C (cm) were significantly higher in hyper-glycaemic group than in normo-glycaemic males and females (All, P<0.0001). In contrast, there were no significant differences in serum VDBP (µg/mL) between the glycaemic sub-groups in either male (P=0.5614) or females (P= 0.4813). The glycaemic parameters, as expected, were significantly increased in the hyperglycaemic sub-groups in both genders, including FBG (mmol/L), 2 hr BG (mmol/L), HbA1c (%), FBI (mIU/L), 2 hr BI (mIU/L) and HOMA-IR (All, both males and females P<0.0001). In general, the lipids, including the triglycerides (mmol/L), LDL-C (mmol/L) and Cholesterol (mmol/L) were also significantly increased in both genders in the hyper-glycaemic sub-groups (All, males P≤0.0300, females P<0.0001), while HDL-C (mmol/L) was significantly decreased in both males and females in the hyperglycaemic sub-groups (All, P≤0.0308). The variant genotype GG of the Fok1, AA of Apa1 and GG of the Taq1 SNPs were not significantly different in hyper-glycaemic patients compared to normo-glycaemic group (58.5% vs 55.1%, P-value, 40.1% vs 38.0%, P-value and 6.9% vs 8.5%, Pvalue,) respectively. Similarly, there was no significant difference in the alleles frequency distribution of these SNPs between the groups. Results also demonstrated no significance difference in the genotype or allele frequency distribution of Fok1 (rs2228570), Apa1 (rs7975232) and Taq1 (rs731236) SNPs between subjects with optimal Vitamin D (25(OH)D ng/mL) levels and those with insufficient/deficient levels (P≥0.2036 and P≥0.6347 respectively). These trends were also observed when serum VDBP levels were evaluated against Fok1, Apa1 and Taq1 genotypes. Multiple linear regression showed that low 25(OH)D was associated with increased LDL-C and PTH in both male and females irrespective of T2DM, but serum VDBP was associated with low 25(OH)D in hyper-glycaemic females only. In normo-glycaemic males 19.5% of the variation in 25(OH)D was attributed to increased LDL-C and in the hyper-glycaemic group 15.5% it was attributed to PTH and CRP. In normo-glycaemic females 12.8% variation in 25(OH)D was attributed to LDL-C, serum creatinine and PTH, whereas in hyper-glycaemic group 16.1% was attributed to increased age, serum VDBP, triglycerides, LDL-C, creatinine and PTH. Conclusion: This study showed prevalence of vitamin D deficiency/insufficiency in the mixed ancestry population group. There was no association between vitamin D (25(OH)D), vitamin D binding proteins (serum VDBP) and VDR polymorphisms in T2DM patients. Serum VDBP levels were associated with low vitamin D levels in hyper-glycaemic females only. Increased LDL-C, PTH and CRP were predictors of low vitamin D levels.
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    The effect of fructosamine 3 kinase (FN3K) genotypes on the glycation gap in type 2 diabetic and non-diabetic mixed ancestry population of South Africa
    (Stellenbosch : Stellenbosch University, 2018-12) Motshwari, Dipuo Dephney; Erasmus, Rajiv T.; Zemlin, Annalise E.; Matsha, Tandi; Stellenbosch University. Faculty of Medicine and Health Science. Dept. of Pathology. Chemical Pathology.
    ENGLISH ABSTRACT: Introduction In2017 the International Diabetes Federation (IDF) reported that approximately 425 million adults aged 20-79 years were estimated to have diabetes mellitus (DM) worldwide. The nonenzymatic glycation reactions of proteins such as haemoglobin have been associated with the development of diabetic related complications. These reactions were believed to be irreversible until the discovery of a protein repair enzyme fructosamine 3 kinase (FN3K). This enzyme deglycates glycated haemoglobin (HbA1c) in erythrocytes and other glycated proteins in other tissues. Animal model studies found that the activity of this enzyme varies between individuals leading to differences in HbA1c levels. This results in discrepancies between HbA1c and other glycaemic measures which is termed the glycation gap. The glycation gap is consistent over time within individuals and is associated with diabetic complications. Genetic variants in the FN3K gene have been associated with altered enzyme activity. Therefore, the aim of this study was to examine the role of FN3K genotypes on the glycation gap Methods A total of 1412 subjects (925 normal, 216 pre-diabetic and 271 type 2 diabetics), with 339 males and 1073 females aged ≥ 20 years of mixed ancestry descent, residing in Bellville South, South Africa were included in this study. The diabetics were diagnosed using the oral glucose tolerance test. The glycation gap was determined according to a formula: Glycation gap= HbA1c - FHbA1c, (FHbA1c = {[(fructosamine- mean fructosamine)/SD fructosamine] X SD HbA1c} + mean HbA1c). DNA was extracted from whole blood using the salt extraction method. FN3K single nucleotide polymorphisms (SNPs) were genotyped with the Applied Biosystems™ QuantStudio™ 7 Flex Real-Time PCR System 96 well fast from Thermo Fisher Scientific. HbA1c was measured using HPLC (Biorad Variant Turbo) and fructosamine was measured using a colorimetric test nitro-blue-tetrazolium (NBT). Results SNP c. -232A/T deviated from Hardy Weinberg Equilibrium (HWE) and was left out for the rest of the statistical analysis. The polymorphism G900C followed the Hardy-Weinberg Equilibrium and was therefore studied. The genotype frequencies for SNP G900C in the glycaemic sub-groups were as follows, GG: 45.9 %, GC: 43.7 %, CC: 10.4 % in normal subjects; GG: 48.6 %, GC: 41.7 %, CC: 9.7% in pre-diabetics and GG: 41.7 %, GC: 46.5 %, CC: 11.8 % in diabetics, and they followed the Hardy-Weinberg equilibrium. There were no significant differences in the SNP G900C genotype frequencies between the glycaemic subgroups. The glycation gap significantly decreased across the GG, GC and CC genotype variants in males, mean ± SD were -0.13±0.86, -0.25±0.72 and -0.80±1.04 respectively, (P=0.0239). However the difference was not observed in females. Moreover the glycation gap showed a positive correlation with non glycaemic factors including body mass index (BMI) (r=0.3694, p<0.0001), waist circumference (waistC) (r=0.3749, p<0.0001), hip circumference (hipC) (r0.3151, p<0.0001), triglycerides (r=0.2540, p<0.0001) and a negative correlation with high density lipoprotein cholesterol (HDL-Chol) (r=-0.2031, p<0.0001). Conclusion In conclusion the present study found that the glycation gap might be influenced by genetic In conclusion the present study found that the glycation gap might be influenced by genetic active mechanisms in the intracellular erythrocyte compartment. Identification of the G900C polymorphism in an early stage of diabetes could be useful especially in therapeutic decisions and prediction of improved prognosis. However, there are other confounding factors influencing the glycation gap and future studies are required to confirm these findings.
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    Free light chains in patients with HIV: establishing local reference ranges and their association with stage of disease, chronic antigen stimulation and the effect of Haart
    (Stellenbosch : Stellenbosch University, 2012-03) Germishuys, Jurie J.; Zemlin, Annalise E.; Erasmus, Rajiv T.; Stellenbosch University. Faculty of Health Sciences. Dept. of Pathology. Chemical Pathology.
    ENGLISH ABSTRACT: Background: Serum free light chains (FLC) are associated with imbalances in heavy and light chain production. Abnormal FLC ratios have been associated with risk of progression in certain diseases. Automated assays are available for their determination and they are used in the followup and management of patients with monoclonal gammopathies. Acceptable imprecision, specificity, accuracy and reproducibility between reagent batches is required to prevent under- or overestimation. Method validation is a standard process in every good laboratory to judge the acceptability of a new method. Reference intervals have been established in an older population, but it was considered important to verify these in our population. HIV is associated with B-cell dysfunction. As B-cell abnormalities are associated with disorders leading to monoclonal gammopathies, we postulated that the FLC levels and FLC ratio would be abnormal in HIV infected individuals. Methods and materials: Controls and pooled patient samples were used for the method validation study which included imprecision studies, linearity, recovery and interference studies, and method comparison studies, the latter compared our method to the same method used in another laboratory. For the reference interval study, blood was obtained from 120 healthy subjects. The following blood tests were performed: total protein, IgG, IgA, IgM, creatinine, protein electrophoresis, kappa FLC and lambda FLC. Using the kappa and lambda FLC results, a FLC ratio was determined. Three hundred and sixty-nine HIV positive subjects were then studied. The same tests were performed, as well as CD4+ counts and viral loads on the majority of them. Results: For the method validation study, precision, linearity and recovery was acceptable. Minimal interference was observed with haemolysis, lipaemia, bilirubin and rheumatoid factor. Our method showed comparable performance with the established method. For the reference interval study, all the creatinine values were normal, as were serum protein values. The serum protein electrophoreses were independently reviewed by 3 pathologists. Most were normal, with a few polyclonal increases seen, but no definite monoclonal bands. The 95% reference intervals for FLC’s as well as the FLC ratio were not statistically significantly different to the manufacturer’s recommendations. When examining the HIV positive study population, we found that FLC and FLC ratio were influenced by markers of HIV disease severity, such as CD4+ count, IgG, viral load, use of antiretroviral treatment and abnormal serum protein electrophoreses. Conclusion: The validation study of FLC showed excellent precision, acceptable bias, good linearity, good recovery and minimal interference, allowing routine introduction of the test. The 95% reference intervals obtained for our population were slightly higher than those recommended by the manufacturer. However, as most of the values fell within the manufacturer’s limits, we could accept the manufacturer’s recommended cut-offs. We found that FLC levels were definitely influenced by markers of HIV disease severity in our population and we postulate that they may be of use for follow-up of patients with HIV.
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    Lipoprotein X : biochemical predictors and detection by non-denaturing polyacrylamide gradient gel electrophoresis
    (Stellenbosch : Stellenbosch University, 2007-12) Le Riche, Mia; Marias, David; Erasmus, Rajiv T.; Stellenbosch University. Faculty of Health Sciences. Dept. of Pathology. Chemical Pathology.
    ENGLISH ABSTRACT: Lipoprotein X (LpX) is an abnormal cholesterol-containing particle that may be present in the serum of subjects with cholestasis, lecithin:cholesterol acyltransferase (LCAT) deficiency and parenteral nutrition. The biochemistry, metabolism, clinical significance and laboratory analysis of LpX is discussed in this study. This laboratory-based project investigated icteric samples received at the Chemical Pathology laboratory, Tygerberg Hospital, for serum predictors of LpX and the use of a modified non-denaturing polyacrylamide gradient gel electrophoresis system in the detection of LpX. The study showed that the non-denaturing polyacrylamide gradient gel electrophoresis system (2-8%) is a useful test in demonstrating LpX in icteric plasma and has potential for a screening test in LCAT deficiency. Serum concentration of conjugated bilirubin, alkaline phosphatase, gamma glutamyltransferase, free cholesterol, phospholipid, free cholesterol: total cholesterol ratio and conjugated bilirubin: total bilirubin ratio are all good predictors of LpX. The ratio of free cholesterol to total cholesterol (FC/TC > 0.6) was the best predictor of LpX. In the setting of obstructive liver disease LpX is seen in 66% of patients if total cholesterol is > 7.5 mmol/L.
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    The occurance of genetic variations in the MYH9 gene and their association with CKD in a mixed South African population
    (Stellenbosch : Stellenbosch University, 2012-12) Masconi, Katya; Matsha, Tandi; Erasmus, Rajiv T.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology.
    ENGLISH ABSTRACT: The purpose of this study was to investigate the association of the selected MYH9 single nucleotide polymorphisms (SNPs) with chronic kidney disease (CKD) and its related co-morbidities in the South African mixed ancestry population residing in Bellville South, Cape Town. In 2008, two landmark studies identified SNPs in the MYH9 gene which explained most of the increased risk for non-diabetic CKD in African Americans. These polymorphisms were later found to be weakly associated with diabetic nephropathy. Three SNPs that exhibited independent evidence for association with CKD were selected (rs5756152, rs4821480 and rs12107). These were genotyped using a Taqman genotyping assay on a BioRad MiniOpticon and confirmed by sequencing in 724 subjects from Bellville South, Cape Town, South Africa. Prevalent CKD was defined based on the estimated glomerular filtration rate calculated using the modification of diet in renal disease (MDRD) formula. Chronic kidney disease was present in 214 subjects (29.6%), 96.3% were stage 3 and only 8 subjects were stage 4. In additive allelic models, adjusted for age and gender, rs5756152 demonstrated an association with kidney function whereby each G allele of rs5756152 increased eGFR by 3.67 ml/min/1.73, reduced serum creatinine by 4.5% and increased fasting plasma glucose by 0.51 mmol/L. When an interaction model was used, the effect of rs5756152 on serum creatinine, eGFR and blood glucose levels was retained, and enhanced, but only in diabetic subjects. In addition, rs4821480 T allele increased eGFR while rs12107 A allele decreased glucose levels in diabetic subjects. In contrast to reports that MYH9 SNPs are strongly associated with non-diabetic end stage renal disease, our study demonstrated that rs5756152 and rs4821480 are associated with early kidney function derangements in type 2 diabetes whilst rs12107 is associated with glucose metabolism. Our findings, along with previous reports, suggest that the MYH9 gene may have a broader genetic risk effect on different types of kidney diseases than previously thought.
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    Screening for Chronic Kidney Disease (CKD) in a high risk population using a Point of Care Instrument for creatinine measurement: A community based study (The Bellville South Africa Study)
    (Stellenbosch : Stellenbosch University, 2017-12) Krige, Tammy; Erasmus, Rajiv T.; Rensburg, Megan; Stellenbosch University. Faculty of Medicine and Health Science. Dept. of Pathology. Chemical Pathology.
    ENGLISH ABSTRACT : Chronic kidney disease (CKD) is described as abnormal kidney function in which one third is lost over a period of 3 months and is a global epidemic with a particularly concentrated incidence within developing countries, such as Sub-Sahara Africa (SSA). Health facilities in SSA are limited due to lack of funding and a dearth in disease and medical knowledge. This coupled with the high incidence of both communicable and non-communicable diseases makes for an ideal environment for the implementation of Point-of-Care Testing (POCT), defined as an analytical test that is performed near the patient, delivering results in real time without the need for a conventional laboratory. CKD POCT involves the measurement of creatinine in capillary whole blood samples in order to determine the estimated glomerular filtration rate (eGFR) of patients in order to stage their CKD status from stage 1-6. This study aimed to bridge the gap in knowledge with regard to cut-offs of creatinine levels and eGFR values when screening a mixed ancestry populations. Currently there is only documented and standardized cut-offs for Caucasian and African American populations. This study looked at the African mixed ancestry population and acts as a starting point for standardizing POCT cut-offs for other international mixed ancestry populations. 103 participants were recruited from the Bellville South community, Cape Town, South Africa. The study was a comparative study that was designed to evaluate the Nova Statsensor® point of care instrument for the measurement of creatinine for the detection of CKD in adult mixed ancestry subjects from the Bellville South Community in South Africa. Secondary objectives included (1) the prevalence of CKD based on the results of the instrument, and (2) the correlation between the Nova Statsensor®, and the central laboratory creatinine values (IDMS traceable). Ancillary objectives of the study were to evaluate the technical quality of POC testing for creatinine in a community setting, as well as the evaluation of the cost implications when introducing this form of POCT into a primary care setting. The study found that the Nova Statsensor® in this study had a sensitivity of 66.7% and a specificity of 100%, displaying excellent diagnostic accuracy. It was found that the device displayed negative proportional bias which may lead to future CKD patients being misdiagnosed as healthy within screening programmes. The prevalence was found to be 2.9% within this mixed ancestry population. The device was user friendly and requires a small sample volume, however it is costly to implement. The laboratory evaluation study found that the Nova Statsensor® creatinine meter produced a direct creatinine concentration comparison that was less than expected, possibly due to creatinine levels depending on several factors which include muscle mass, obesity, gender, and age and having a wide reference interval. Thus highlighting the importance of the use of the equations to calculate eGFR in CKD screening in order to obtain the CKD staging results which displayed better correlation to the reference method, compared to creatinine measurement alone. The device was comparable to the reference method when performance was measured based on CKD staging through the calculation of the MDRD equation.