Correlation between self-monitored mean blood glucose and average plasma glucose estimated from glycated haemoglobin in patients attending the diabetes clinic at Dr George Mukhari Academic Hospital, Pretoria, South Africa.

BACKGROUND: Glycated haemoglobin (HbA1c) has been used for decades as a measure of chronic glycaemia. A simple linear relationship between HbA1c values and mean blood glucose (MBG) has been identified and led to conversion of HbA1c values into estimated average glucose (eAG) levels, following the findings of the A1c-Derived Average Glucose (ADAG) Study Group. The intention was to help patients with diabetes mellitus (DM) understand their glycaemic control better, as eAG is reported in the same units as self-monitored glucose levels. However, factors other than glycaemia have been found to affect the relationship between HbA1c and MBG. OBJECTIVES: To: (i) determine the relationship between self-monitored MBG levels and HbA1c values; and (ii) evaluate the correlation between MBG levels and eAG levels calculated from HbA1c values using the regression equation derived from the ADAG Study Group in black South African patients with DM. METHODS: This was a prospective observational study of 96 diabetic patients. MBG levels were calculated using glucose measurements downloaded from the glucose meters for the previous 90 days (3 months). High-performance liquid chromatography was used for measurement of HbA1c values, collected at the end of 3 months. eAG was calculated using the regression equation from the ADAG Study Group, as follows: eAG (mmol/L) = 1.5944 × HbA1c (NGSP, %) - 2.594. RESULTS: A positive correlation was found between MBG and HbA1c in all participants (R2=0.69, p<0.0001). There was a wide range of MBG levels for any given HbA1c value. Clinically significant differences between MBG and eAG were found, with a ≥10% difference in 65.6% of the participants. eAG overestimated MBG in ~71.8% of the study population, with an overestimation of ≥1.6 mmol/L (28.7 mg/dL, equivalent to a 1% change in HbA1c value) in ~50% of the total study population. CONCLUSIONS: Our findings showed an imperfect relationship between MBG levels and HbA1c values. eAG significantly overestimated MBG, and this disagreement may cause confusion among both patients and clinicians. The risk of hypoglycaemic episodes may also increase if HbA1c and eAG alone are used to intensify therapy. We recommend that the use of eAG should be validated prior to implementation in clinical practice. It would be ideal to evaluate the relationship between average glucose and HbA1c in each individual patient in order to provide more personalised diabetes care.

Haemorrhagic transformation following ischaemic stroke: A retrospective study.

The aim of this study was to identify the prevalence of haemorrhagic transformation (HT) in patients with ischaemic stroke, and evaluate its association with medical comorbidities, stroke subtypes, premorbid medication, and long-term survival. To achieve this, we performed a retrospective analysis of 527 consecutive stroke rehabilitation patients. Of these, 102 (19.4%) developed HT. Older patients, and those with large artery strokes, had a higher risk of HT. Forty-one patients received alteplase (rtPA), of which 15 (36.6%) developed HT. A total of 129 (24.5%) patients were taking aspirin prior to their stroke and, of these, 39 (30.2%) developed HT. Twenty-three (4.36%) patients were taking vitamin k antagonists, prior to stroke, of which 14 (60.9%) developed HT. There were 102 patients (19.35%) with underlying atrial fibrillation, of whom 55 (53.9%) developed HT. Patients with known ischaemic heart disease had an increased risk of HT, and patients with HT had significantly lower total cholesterol levels (4.96 vs. 5.34) and lower LDL cholesterol levels (3.20 vs. 3.5). In conclusion, older age, atrial fibrillation, treatment with oral anticoagulants and antiplatelet medications prior to stroke, low total and LDL cholesterol, and rtPA use, are all associated with HT. Survival was not affected by the presence of HT.

Familial hypercholesterolaemia workshop for leveraging point-of-care testing and personalised medicine in association with the Lipid and Atherosclerosis Society of Southern Africa.

Familial hypercholesterolaemia (FH) is a common autosomal dominantly inherited disorder in which impaired clearance of plasma low-density lipoprotein cholesterol causes premature atherosclerotic vascular disease and tendon xanthomata. This workshop aimed to consolidate information on the diagnosis and management of FH in South Africa. The genetic causes include mutations in the LDL receptor, apolipoprotein B100 and proprotein convertase subtilisin/kexin type 9 (PCSK9). Additionally, the concatenation of multiple gene variants can result in polygenic FH. Therapeutic measures include a healthy lifestyle, statins and cholesterol-absorption inhibitors that will achieve control of the dyslipidaemia in the majority of cases. The recently introduced monoclonal antibodies to PCSK9 can improve achievement of target concentration in severe cases. FH is present in all sectors of the South African population but there is sparse documentation in the indigenous African populations. FH should be actively sought, diagnosed and treated with judicious pharmacotherapy and screening of relatives.

Prevalence of geophagia and its contributing factors among pregnant women at Dr. George Mukhari Academic Hospital, Pretoria.

INTRODUCTION: Geophagia is very common among pregnant women, particularly in Africa. There are many reasons given for geophagia such as cultural, medicinal and religious, making it an acceptable norm regardless of health risks involved. OBJECTIVES: The study explored prevalence and factors influencing geophagia among women visiting an antenatal clinic in Pretoria. METHODS: A quantitative survey was done on a convenience sample of 597 pregnant women and structured interviews conducted. Statistical analysis was done using simple percentage and interview data analyzed using Epi Info statistical software. RESULTS: Geophagia was reported by 54.0% of the women (n=323) and of these, 75.2% (n=243) ate at least 3 teaspoons per day. Reasons for the practice ranged from simple unexplained craving to belief that soil acts as an iron supplement. The study revealed that education levels did not act as a contributing factor as both literate and illiterate women were consumers. Partners of consumers played a key role in influencing the practice as most consumers were not married. CONCLUSION: Geophagia is practiced by a considerable proportion of pregnant women in this area. Greater vigilance may be needed as part of the antenatal classes to avoid potentially harmful effects of the habit.

High Prevalence of Primary Dyslipidaemia in Black South African Patients at a Tertiary Hospital in Northern Gauteng; South Africa

BACKGROUND:The prevalence of cardiovascular disease is projected to be 38.7% for the USA in 2020; including coronary heart disease at 8.6% and stroke at 3.6%. In South Africa (SA); premature deaths due to heart and blood vessel diseases in people of working age (35 - 64 years) have been predicted to increase by 41% between 2007 and 2030; with enormous negative economic impact. Atherosclerosis underlies much of the pathogenesis; which involves risk factors including dyslipidaemia. Secondary dyslipidaemia associated with diabetes mellitus; hypothyroidism; chronic renal disease; cholestasis; nephrotic syndrome; alcohol excess; drugs such as thiazide diuretics and antiretroviral agents may respond to treatment of underlying causes; but residual dyslipidaemia may in such cases be due to primary disorders of metabolism. Primary dyslipidaemias are uncommon and to a large extent underdiagnosed; especially in the black population of SA; reflecting a lack of clinical and laboratory awareness or expertise. Specific diagnoses enable effective intervention in the patients as well as the families.OBJECTIVE:To assess the burden and prevalence of dyslipidaemia in the SA black population at Dr George Mukhari Hospital in the north region of Gauteng.METHOD:A retrospective data analysis of 12-month lipid profiles comprising triglyceride (TG); total cholesterol (TC); high-density lipoprotein cholesterol and directly measured low-density lipoprotein (LDL) cholesterol (LDLC).RESULTS:There were 24 656 requests for 6 348 patients. The lipid cut-off levels were somewhat arbitrary but were based on the commonly used decision-making levels in the treatment guidelines. Severe hypercholesterolaemia (etgt;7 mmol/L) was seen in 299 (4.7%) patients and extreme hypercholesterolaemia (etgt;12 mmol/L) was seen in 30 (0.5%) patients. LDLC (etgt;5 mmol/L) occurred in 80 (1.3%) patients and etgt;10 mmol/L in 19 (0.3%) patients. A predominant triglyceride problem was seen in 578 (9.1%) patients with TG (etgt;2 mmol/L) and TC (etlt;5 mmol/L); whereas moderate hypertriglyceridaemia (etgt;5 mmol/L) was present in 113 (1.8%) patients; and more severe hypertriglyceridaemia (etgt;10 mmol/L) in 10 (0.2%). TC (etgt;5 mmol/L) with LDL (etgt;3 mmol/L) but TG in the normal range was seen in 369 (5.8%) patients; indicating a cholesterol-predominant problem. In contrast; LDLC (etgt;3 mmol/L) and TG (etgt;1.7 mmol/L) was seen in 249 (3.87%) representing mixed hyperlipidaemia. Paediatric patients with severe dyslipidaemia mostly suffered from nephrotic syndrome.CONCLUSION:A significant burden and a high prevalence of dyslipidaemias were present in adults in whom a monogenic disorder should be considered. The extent and severity of dyslipidaemia justify a special clinic and laboratory to ensure accurate diagnosis with effective intervention for patients and their families

CDw150(SLAM) is a receptor for a lymphotropic strain of measles virus and may account for the immunosuppressive properties of this virus.

Natural isolates of measles virus readily infect several lymphocyte cell lines. These viruses appear to use a receptor other than CD46, the molecule to which most laboratory strains of virus bind. Methods used to identify and characterize this lymphocyte receptor for measles virus are described in this study. A binding assay with a soluble form of measles virus H protein demonstrated that B-cell lines, activated with Epstein-Barr virus, or T cells, transformed with human T-cell leukemia virus, exhibit this receptor on their cell surfaces. On the other hand, resting lymphocytes, monocytes, or immature leukocytes either failed to express or possessed reduced levels of this receptor. A cDNA library derived from B95-8 marmoset B-cell lines was used to identify this receptor through expression cloning. This molecule was shown to be CDw150, which is also known as the signaling lymphocytic activation molecule (SLAM). When the lymphocyte receptor was expressed in Chinese hamster ovary (CHOP) or human embryonic kidney (293T) cells, these cells became susceptible to lymphotropic as well as laboratory strains of measles virus. Binding assays confirmed that either lymphotropic or laboratory strains of measles virus could adhere to human or marmoset CDw150, but interaction with the mouse homolog was weak. These infections were independent of the presence of CD46 on the host cell surface. Interaction of measles virus with CDw150(SLAM) could explain the immunosuppressive properties of this virus.

X protein of hepatitis B virus inhibits Fas-mediated apoptosis and is associated with up-regulation of the SAPK/JNK pathway.

The X protein from a chronic strain of hepatitis B virus (HBx) was determined to inhibit Fas-mediated apoptosis and promote cell survival. Fas-mediated apoptosis is the major cause of hepatocyte damage during liver disease. Experiments demonstrated that cell death caused by anti-Fas antibodies was blocked by the expression of HBx in human primary hepatocytes and mouse embryo fibroblasts. This effect was also observed in mouse erythroleukemia cells that lacked p53, indicating that protection against Fas-mediated apoptosis was independent of p53. Components of the signal transduction pathways involved in this protection were studied. The SAPK/JNK pathway has previously been suggested to be a survival pathway for some cells undergoing Fas-mediated apoptosis, and kinase assays showed that SAPK activity was highly up-regulated in cells expressing the HBx protein. Normal mouse fibroblasts expressing HBx were protected from death, whereas identical fibroblasts lacking the SEK1 component from the SAPK pathway succumbed to Fas-mediated apoptosis, whether HBx was present or not. Assays showed that caspase 3 and 8 activities and the release of cytochrome c from mitochondria were inhibited, in the presence of HBx, following stimulation with anti-Fas antibodies. Coprecipitation and confocal immunofluorescence microscopy experiments demonstrated that HBx localizes with a cytoplasmic complex containing MEKK1, SEK1, SAPK, and 14-3-3 proteins. Finally, mutational analysis of HBx demonstrated that a potential binding region for 14-3-3 proteins was essential for induction of SAPK/JNK activity and protection from Fas-mediated apoptosis.

Functional significance of globotriaosyl ceramide in interferon-alpha(2)/type 1 interferon receptor-mediated antiviral activity.

The N-terminus of the type 1 interferon receptor subunit, IFNAR1, has high amino acid sequence similarity to the receptor binding B subunit of the Escherichia coli-derived verotoxin 1, VT1. The glycolipid, globotriaosyl ceramide (Gb(3): Gal alpha(1) --> 4 Gal beta 1 --> 4 Glu beta 1 --> 1 Cer) is the specific cell receptor for VT1. Gb(3)-deficient variant cells selected for VT resistance are cross-resistant to interferon-alpha (IFN-alpha)-mediated antiproliferative activity. The association of eIFNAR1 with Gal alpha 1 --> 4 Gal containing glycolipids has been previously shown to be important for the receptor-mediated IFN-alpha signal transduction for growth inhibition. The crucial role of Gb(3) for the signal transduction of IFN-alpha-mediated antiviral activity is now reported. IFN-alpha-mediated antiviral activity, nuclear translocation of activated Stat1, and increased expression of PKR were defective in Gb(3)-deficient vero mutant cells, although the surface expression of IFNAR1 was unaltered. The VT1B subunit was found to inhibit IFN-alpha-mediated antiviral activity, Stat1 nuclear translocation and PKR upregulation. Unlike VT1 cytotoxicity, IFN-alpha-induced Stat1 nuclear translocation was not inhibited when RME was prevented, suggesting that the accessory function of Gb(3) occurs at the plasma membrane. IFN-alpha antiviral activity was also studied in Gb(3)-positive MRC-5 cells, which are resistant to IFN-alpha growth inhibition, partially resistant to VT1 but still remain fully sensitive to IFN-alpha antiviral activity, and two astrocytoma cell lines expressing different Gb(3) fatty acid isoforms. In both systems, long chain fatty acid-containing Gb(3) isoforms, which are less effective to mediate VT1 cytotoxicity, were found to correlate with higher IFN-alpha-mediated antiviral activity. Inhibition of Gb(3) synthesis in toto prevented IFN-alpha antiviral activity in all cells. We propose that the long chain Gb(3) fatty isoforms preferentially remain in the plasma membrane, and by associating with IFNAR1, mediate IFN-alpha antiviral signaling, whereas short chain Gb(3) fatty acid isoforms are preferentially internalized to mediate VT1 cytotoxicity and IFNAR1-dependent IFN-alpha growth inhibition.

Globotriaosyl ceramide (Gb3) expression in human tumour cells: intracellular trafficking defines a new retrograde transport pathway from the cell surface to the nucleus, which correlates with sensitivity to verotoxin.

The verotoxin receptor globotriaosyl ceramide (Gb3) is overexpressed in an ovarian tumour resistant to chemotherapy. An overlay of frozen tumour sections shows extensive staining of the tumour cells with verotoxin B subunit. In addition, blood vessels within the tumour mass are stained. The sensitivity of ovarian tumour cells in vitro to verotoxin can be modulated by culturing the cells in sodium butyrate to obtain an approximately 5000-fold increase in susceptibility. This increased susceptibility is correlated with the intracellular targeting of verotoxin as monitored by using FITC-VT B subunit, in that prior to sodium butyrate treatment the toxin is internalized to a juxtanuclear (likely) Golgi location whereas, following butyrate treatment the intracellular toxin is distributed around the nucleus, consistent with endoplasmic reticulum and nuclear envelope location. This perinuclear location is similar to that found for drug-resistant variants of ovarian tumour cell lines. These results suggest that intracellular targeting of verotoxin to the perinuclear area results in increased cytotoxicity. Potentially such targeting may also occur in other human tumours.

CD77-dependent retrograde transport of CD19 to the nuclear membrane: functional relationship between CD77 and CD19 during germinal center B-cell apoptosis.

A region of the N-terminal extracellular domain of the B-cell restricted cell differentiation antigen, CD19, has high amino acid sequence similarity to the receptor binding subunit B of verotoxin 1 (VT), an Escherichia coli elaborated cytotoxin, which specifically binds to the cell surface glycolipid, globotriaosylceramide, also known as the germinal center (GC) B-cell differentiation antigen, CD77. We have previously provided evidence of the association of CD19 and CD77 on the cell surface and in CD19-mediated homotypic adhesion of the Daudi Burkitt Lymphoma cell line, one normal counterpart of which is a subset of GC B cells. Evidence for the role of CD77 in CD19-induced apoptosis is now presented. Initial cell surface distribution, antibody-induced redistribution, internalization, and intracellular routing of CD19 were studied by confocal microscopy, IF, and postembedding IEM in CD77+ve and CD77-ve cells to investigate the possible role of CD77 in CD19 internalization and signaling. Daudi Burkitt's lymphoma cells were used as CD77+ve cells and as CD77-ve cells, Daudi mutant VT500 cells, and Daudi cells treated with PPMP, an inhibitor of CD77 synthesis, were used. Antibody ligated CD19 surface redistribution, internalization, and subcellular distribution of internalized CD19 was found to be different in CD77+ve and CD77-ve cells. A delay in internalization of antibody-CD19 complex was observed in CD77-ve cells. Internalized CD19 was targeted to the nuclear envelope in CD77+ve cells in a manner similar to that reported for VT, but not in CD77-ve cells. Internalization of CD77 by ligation with verotoxin prevented the internalization of ligated CD19. Induction of apoptosis following crosslinking of cell surface CD19 was greater in CD77+ve cells than in CD77-ve cells. The nuclear targeting of internalized CD19 and induction of apoptosis following CD19 crosslinking only in CD77+ve cells indicates a role for CD77-dependent CD19 retrograde transport from the B cell surface via the ER to the nuclear envelope in CD19-mediated signal transduction for apoptosis.

Interleukin-1 increases vacuolar-type H+-ATPase activity in murine peritoneal macrophages.

Maintenance of cytoplasmic pH (pHi) within a narrow physiological range is crucial to normal cellular function. This is of particular relevance to phagocytic cells within the acidic inflammatory microenvironment where the pHi tends to be acid loaded. We have previously reported that a vacuolar-type H(+)-ATPase (V-ATPase) situated in the plasma membrane of macrophages and poised to extrude protons from the cytoplasmic to the extracellular space is an important pHi regulatory mechanism within the inflammatory milieu. Since this microenvironment is frequently characterized by the influx of cells known to release inflammatory cytokines, we performed studies to examine the effect of one such mediator molecule, interleukin-1 (IL-1), on pHi regulation in peritoneal macrophages. IL-1 caused a time- and dose-dependent increase in macrophage pHi recovery from an acute acid load. This effect was specific to IL-1 and was due to enhanced plasmalemmal V-ATPase activity. The increased V-ATPase activity by IL-1 occurred following a lag period of several hours and required de novo protein and mRNA synthesis. However, Northern blot analysis revealed that IL-1 did not exert its effect via alterations in the levels of mRNA transcripts for the A or B subunits of the V-ATPase complex. Finally, stimulation of both cAMP-dependent protein kinase and protein kinase C was required for the stimulatory effect of IL-1 on V-ATPase activity. Thus, cytokines present within the inflammatory milieu are able to modulate pHi regulatory mechanisms. These data may represent a novel mechanism whereby cytokines may improve cellular function at inflammatory sites.

Capping and receptor-mediated endocytosis of cell-bound verotoxin (Shiga-like toxin). 1: Chemical identification of an amino acid in the B subunit necessary for efficient receptor glycolipid binding and cellular internalization.

The glycolipid globotriaosylceramide (Gb3) is the plasma membrane receptor that mediates the internalization of verotoxin (VT1) into susceptible cells by capping and receptor-mediated endocytosis (RME). Internalization of fluorescein isothiocyanate-conjugated holotoxin into Daudi lymphoma cells was found to be slower than the pentameric receptor binding B subunit alone, suggesting that the A subunit may interact with the membrane to compromise the lateral mobility of the receptor bound B subunit. 3-D reconstruction of fluorescent images by confocal microscopy confirmed the complete internalization of holotoxin. VT1 internalization and cytotoxicity was inhibited by monodansyl cadavarine, which supports a role for clathrin coated pits in the RME of VT1. Biotinylation of the B subunit (in contrast to fluorescein labelling) was found to prevent toxin internalization. This effect correlated with reduced binding of Gb3 and reduced cytotoxicity in vitro. By cleavage of the B subunit at the single tryptophan residue, the reduced Gb3 binding and lack of cellular internalization was shown to be due to the biotinylation of lysine 53 in the VT1 B subunit. This residue was not labelled with fluorescein isothiocyanate in the native protein. This conclusion was confirmed by the finding that biotinylation of VT2c (which contains lys 53) prevented glycolipid receptor binding, whereas biotinylation of VT2e (in which lys 53 is substituted by ile) had no effect.

Computed tomography appearance of melanoma of nasal cavity.

Melanoma of the nasal cavity is a mucosal lesion that is quite rare. It comprises less than 1% of all melanomas and constitutes 4% of primary malignant tumors of the nasal cavity. The computed tomography appearance of this entity is discussed and found to be nonspecific.