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result(s) for
"Dix-Peek, Therese"
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Calcium ions and osteoclastogenesis initiate the induction of bone formation by coral‐derived macroporous constructs
by
Dix‐Peek, Therese
,
Dickens, Caroline
,
Klar, Roland M
in
Angiogenesis
,
Animals
,
Anthozoa - chemistry
2013
Coral‐derived calcium carbonate/hydroxyapatite macroporous constructs of the genus Goniopora with limited hydrothermal conversion to hydroxyapatite (7% HA/CC) initiate the induction of bone formation. Which are the molecular signals that initiate pattern formation and the induction of bone formation? To evaluate the role of released calcium ions and osteoclastogenesis, 7% HA/CC was pre‐loaded with either 500 μg of the calcium channel blocker, verapamil hydrochloride, or 240 μg of the osteoclast inhibitor, biphosphonate zoledronate, and implanted in the rectus abdominis muscle of six adult Chacma baboons Papio ursinus. Generated tissues on days 15, 60 and 90 were analysed by histomorphometry and qRT‐PCR. On day 15, up‐regulation of type IV collagen characterized all the implanted constructs correlating with vascular invasion. Zoledronate‐treated specimens showed an important delay in tissue patterning and morphogenesis with limited bone formation. Osteoclastic inhibition yielded minimal, if any, bone formation by induction. 7% HA/CC pre‐loaded with the Ca++ channel blocker verapamil hydrochloride strongly inhibited the induction of bone formation. Down‐regulation of bone morphogenetic protein‐2 (BMP‐2) together with up‐regulation of Noggin genes correlated with limited bone formation in 7% HA/CC pre‐loaded with either verapamil or zoledronate, indicating that the induction of bone formation by coral‐derived macroporous constructs is via the BMPs pathway. The spontaneous induction of bone formation is initiated by a local peak of Ca++ activating stem cell differentiation and the induction of bone formation.
Journal Article
High risk APOL1 genotypes and kidney disease among treatment naïve HIV patients at Kano, Nigeria
2022
Racial disparities are known in the occurrence of kidney disease with excess risks found among people of African descent. Apolipoprotein L1 (APOL1) gene variants G1 and G2 are associated with kidney disease among HIV infected individuals of African descent in the USA as well as among black population in South Africa. We set out to investigate the prevalence of these high-risk variants and their effects on kidney disease among HIV infected patients in Northern Nigeria with hitherto limited information despite earlier reports of high population frequencies of these alleles from the Southern part of the country. DNA samples obtained from the whole blood of 142 participants were genotyped for APOL1 G1 and G2 variants after initial baseline investigations including assessment of kidney function. Participants comprised 50 HIV positive patients with no evidence of kidney disease, 52 HIV negative individuals with no kidney disease and 40 HIV positive patients with chronic kidney disease (CKD) evidenced by persistent proteinuria and/or reduced eGFR, who also had a kidney biopsy. All the HIV positive patients were newly diagnosed and treatment naïve. The distribution of the APOL1 genotypes among the study participants revealed that 24.6% had a G1 risk allele and 19.0% a G2. The frequency of the High Risk Genotype (HRG) was 12.5% among those with CKD compared to 5.8% in the HIV negative group and zero in the HIV positive no CKD group. Having the HRG was associated with a higher odds for developing HIV Associated Nephropathy (HIVAN) (2 vs 0 risk alleles: OR 10.83, 95% CI 1.38-84.52; P = 0.023; 2 vs 0 or 1 risk alleles: OR 5.5, 95% CI 0.83-36.29; P = 0.07). The HRG was also associated with higher odds for Focal Segmental Glomerulosclerosis (FSGS) (2 vs 0 risk alleles: OR 13.0, 95% CI 2.06-81.91; P = 0.006 and 2 vs 0 or 1 risk alleles: OR 9.0, 95%CI 1.62-50.12; P = 0.01) when compared to the control group. This study showed a high population frequency of the individual risk alleles of the APOL1 gene with higher frequencies noted among HIV positive patients with kidney disease. There is high association with the presence of kidney disease and especially FSGS and HIVAN among treatment naive HIV patients carrying two copies of the HRG.
Journal Article
Demographic and clinical profile of black patients with chronic kidney disease attending a tertiary hospital in Johannesburg, South Africa
2022
The prevalence of chronic kidney disease (CKD) is increasing worldwide; black patients have an increased risk of developing CKD and end stage kidney disease (ESKD) at significantly higher rates than other races. A cross sectional study was carried out on black patients with CKD attending the kidney outpatient clinic at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) in South Africa, between September 2019 to March 2020. Demographic and clinical data were extracted from the ongoing kidney outpatient clinic records and interviews, and were filled in a questionnaire. Patients provided blood and urine for laboratory investigations as standard of care, and data were descriptively and inferentially entered into REDcap and analysed using STATA version 17. Multivariable logistic regression analysis was used to identify demographic and clinical variables associated with advanced CKD. A total of 312 black patients with CKD were enrolled in the study with a median age of 58 (IQR 46-67) years; 58% patients had advanced CKD, 31.5% of whom had grossly increased proteinuria, 96.7% had hypertension, 38.7% had diabetes mellitus and 38.1% had both hypertension and diabetes mellitus. In patients with advanced CKD, the median age was 61 (IQR 51-69) years, eGFR 33 (30-39) mL/min/1.73 m.sup.2, serum bicarbonate 22 (IQR 20-24), haemoglobin 12.9 (IQR 11.5-14.0) g/dl and serum uric acid 0.43 (IQR 0.37-0.53). The prevalence of metabolic acidosis was 62.4%, anemia 46.4% and gout 30.9% among those with advanced CKD, while the prevalence of metabolic acidosis and anaemia was 46.6% and 25.9% respectively in those with early CKD. Variables with higher odds for advanced CKD after multivariable logistic regression analysis were hypertension (OR 3.3, 95% CI 1.2-9.2, P = 0.020), diabetes mellitus (OR 1.8, 95% CI 1.1-3.3, P = 0.024), severe proteinuria (OR 3.5, 95% CI 1.9-6.5, P = 0.001), angina (OR 2.5, 95% CI 1.2-5.1, P = 0.008), anaemia (OR 2.9, 95% CI 1.7-4.9, P = 0.001), hyperuricemia (OR 2.4, 95% CI 1.4-4.1, P = 0.001), and metabolic acidosis (OR 2.0, 95% CI 1.2-3.1, P = 0.005). Other associations with advanced CKD were loss of spouse (widow/widower) (OR 3.2, 95% CI 1.4-7.4, P = 0.006), low transferrin (OR 2.4, 95% CI 1.1-5.1, P = 0.028), hyperkalemia (OR 5.4, 95% CI 1.2-24.1, P = 0.029), use of allopurinol (OR 2.4, 95% CI 1.4-4.3, P = 0.005) and doxazosin (OR 1.9, 95% CI 1.2-3.1, P = 0.006). Hypertension and diabetes mellitus were strongly associated with advanced CKD, suggesting a need for primary and secondary population-based prevention measures. Metabolic acidosis, anemia with low transferrin levels, hyperuricemia and hyperkalemia were highly prevalent in our patients, including those with early CKD, and they were strongly associated with advanced CKD, requiring clinicians and dietitians to be proactive in supporting the needs of CKD patients in meeting their daily dietary requirements towards preventing and slowing the progression of CKD.
Journal Article
Association of chronic inflammation and accelerated atherosclerosis among an indigenous black population with chronic kidney disease
by
Naidoo, Sagren
,
Naicker, Saraladevi
,
Dix-Peek, Therese
in
Adult
,
Arteriosclerosis
,
Atherosclerosis
2020
Inflammation plays a major role in the development of atherosclerosis and cardiovascular morbidity and mortality in chronic kidney disease (CKD) patients. Toll-like receptor-4 (TLR4) is a major receptor for lipopolysaccharides (endotoxin) and other ligands involved in the pathogenesis of inflammation. We determined whether endotoxin levels and the presence of TLR4 polymorphisms are associated with markers of inflammation and atherosclerosis among South African CKD patients.
Endotoxin, lipopolysaccharide binding protein (LBP), serum CD14 (sCD14), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1) and carotid intima media thickness (CIMT) were measured in 160 participants (120 CKD patients and 40 controls). Associations between endotoxins and CIMT in the presence of sCD14, IL-8 and MCP-1, were assessed using odds ratios. Participants were screened for the presence of Asp299Gly and Thr399Ile TLR4 polymorphisms, and CIMT and inflammatory markers were compared between subjects with and without TLR4 polymorphisms.
Endotoxin levels correlated with sCD14 (r = 0.441, p<0.001) and MCP-1 (r = 0.388, p<0.001) levels while increased CIMT was associated with MCP-1 (r = 0.448, p<0.001), sCD14 levels (r = 0.476, p<0.001), LBP (r = 0.340, p<0.001), and IL-8 (r = 0.395, p<0.001). Atherosclerosis was associated with endotoxin levels (odds ratio: 4.95; 95% confidence interval: 2.52-9.73; p<0.001), and was predicted by higher serum levels of inflammatory markers. Analysis of patients with TLR4 polymorphisms showed reduced serum levels of inflammatory markers and CIMT values compared with the patients carrying the wild type TLR4 alleles.
The study demonstrated associations between circulating endotoxaemia, systemic inflammation and accelerated atherosclerosis among South African CKD patients, and showed that the atherogenic predictive power of endotoxaemia was significantly increased by the presence of elevated levels of inflammatory markers. Additional findings, which must be confirmed, suggest that TLR4 polymorphisms are associated with low levels of inflammatory markers and CIMT values.
Journal Article
Colorectal cancer progression to metastasis is associated with dynamic genome-wide biphasic 5-hydroxymethylcytosine accumulation
by
Dix-Peek, Thérèse
,
Murcott, Ben
,
Sero, Julia
in
5-Hydroxymethylcytosine
,
5-Methylcytosine - analogs & derivatives
,
5-Methylcytosine - metabolism
2025
Background
Colorectal cancer (CRC) progression from adenoma to adenocarcinoma is associated with global reduction in 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). DNA hypomethylation continues upon liver metastasis. Here we examine 5hmC changes upon progression to liver metastasis.
Results
5hmC is increased in metastatic liver tissue relative to the primary colon tumour and expression of TET2 and TET3 is negatively correlated with risk for metastasis in patients with CRC. Genes associated with increased 5-hydroxymethylcytosine show KEGG enrichment for adherens junctions, cytoskeleton and cell migration around a core cadherin (CDH2) network. Overall, the 5-hydroxymethylcyosine profile in the liver metastasis is similar to normal colon appearing to recover at many loci where it was originally present in normal colon and then spreading to adjacent sites. The underlying sequences at the recover and spread regions are enriched for SALL4, ZNF770, ZNF121 and PAX5 transcription factor binding sites. Finally, we show in a zebrafish migration assay using SW480 CRISPR-engineered TET knockout and rescue cells that reduced TET expression leads to a reduced migration frequency.
Conclusions
Together these results suggest a biphasic trajectory for 5-hydroxymethyation dynamics that has bearing on potential therapeutic interventions aimed at manipulating 5-hydroxymethylcytosine levels.
Journal Article
Associations of plasma fibroblast growth factor 23 and other markers of chronic kidney disease—Mineral and bone disorder with all-cause mortality in South African patients on maintenance dialysis: A 3-year prospective cohort study
by
Rekhviashvili, Vakhtang
,
Naicker, Saraladevi
,
Dix-Peek, Therese
in
Adult
,
Biology and Life Sciences
,
Biomarkers - blood
2019
Few studies have linked high levels of plasma C-terminal fibroblast growth factor 23 (FGF23) with poor clinical outcomes in patients on maintenance haemodialysis (MHD), while the association between intact FGF23 and mortality in this group of patients remains inconclusive. Therefore, the aim of this study was to evaluate the association between plasma levels of intact FGF23 and mortality in dialysis patients.
A prospective multicenter study involving patients undergoing dialysis at three dialysis centers in Johannesburg was undertaken between 1st October 2014 and 31st December 2017.
The study comprised 165 chronic dialysis patients (111 blacks, 54 whites) with a mean age of 46.6 ±14.2 years. During a three year follow up period, there were 46 deaths (1.03 per 100 person-years). The median plasma FGF 23 level was 382 pg/ml (interquartile range [IQR], 145-2977). In adjusted multivariable analyses, there was a non-statistically significant increase in the risk of mortality with higher quartiles of FGF 23 levels: the adjusted hazard ratios (HR) for the second, third and fourth quantiles were HR 3.20 (95% CI, 0.99-10.35; P = 0.052), HR 2.43(95% CI,0.65-9.09; P = 0.19), and HR 2.09 (95% CI, 0.66-7.32; P = 0.25),respectively. Corrected serum calcium 2.38-2.5 mmol/l [HR 2.98 (95% CI, 1.07-8.29; P = 0.04] and > 2.50 mmol/l [HR 5.50 (95% CI, 1.84-16.48; P = 0.002] were independently associated with increased risk of death. Likewise, patients with intact parathyroid hormone > 600 pg/ml had a 3.46-fold higher risk of death (HR 3.46, 95% CI, 1.22-9.82 P = 0.019). These findings persisted in time -dependent analyses.
Higher levels of intact FGF 23 appear not to be independently associated with all-cause mortality in our dialysis patients, while hypercalcaemia and severe hyperparathyroidism were found to be independent predictors of mortality in this cohort of patients.
Journal Article
Clinical Characteristics, Long-Term Pharmacokinetics, and Outcomes in Kidney Transplant Recipients from an African Tertiary Centre: A 10-Year Single-Centre Retrospective Review
by
Makgoro, Confidence
,
Dix-Peek, Therese
,
Dickens, Caroline
in
acute rejection
,
Antithymocyte globulin
,
Creatinine
2026
Background: Kidney transplantation outcomes in resource-limited settings remain underreported. This 10-year retrospective review examined the clinical characteristics, long-term pharmacokinetics, and outcomes of kidney transplant recipients at a South African public hospital. Methods: Data from kidney transplant recipients between January 2012 and December 2022 were analysed. Graft and patient survival were assessed using Kaplan–Meier analysis. Cox proportional hazards models were used to evaluate the associations between clinical and pharmacokinetic variables and outcomes. Results: The one- and five-year graft survival rates were 87.9% and 65.6%, respectively. Acute rejection, as confirmed by biopsy, was associated with graft failure (HR, 2.46; p = 0.010). Increasing recipient age at transplantation increased the graft failure risk by about 5.0% per year (HR: 1.05, p = 0.006). Tacrolimus trough and normalised trough levels were lower in the graft loss group 73% and 93% of the time, respectively, despite similar tacrolimus doses. Whereas achieving optimal tacrolimus concentration did not significantly affect graft survival, maintaining a haemoglobin level >10 g/dL improved the chances of 3-, 4-, and 5-year graft survival (p-value, 0.001, 0.001, and <0.001, respectively). Patient survival rates were more favourable than graft survival rates. The 1-year and 5-year patient survival rates were 90.0% and 77.4%, respectively. Conclusions: This study offers insights into transplant outcomes in low-resource public health settings. The findings emphasise the impact of rejection and age on the risk of graft failure and the significance of maintaining adequate haemoglobin levels after transplantation. The results also indicate the need for more nuanced and personalised approaches to tacrolimus monitoring in the long-term following transplantation.
Journal Article
Associations of Transforming Growth Factor-β (TGF-β) with Chronic Kidney Disease Progression in Patients Attending a Tertiary Hospital in Johannesburg, South Africa
by
Meremo, Alfred
,
Naicker, Saraladevi
,
Dix-Peek, Therese
in
Analysis
,
Biomarkers
,
Blood pressure
2026
Introduction: The global prevalence of chronic kidney disease (CKD) is increasing and it is associated with higher mortality rates. Transforming growth factor-beta (TGF-β) can serve as a novel biomarker for early prediction of chronic kidney disease (CKD) progression. Methods: This was a prospective longitudinal study among black patients with CKD who attended the Charlotte Maxeke Johannesburg Academic Hospital between September 2019 and March 2022. Patients provided urine and blood samples for laboratory investigations at study entry (0) and at 24 months follow up. Baseline serum and urine TGF-β1, TGF-β2 and TGF-β3 levels were measured using ELISAs. Multivariable logistic regression analysis was utilized to determine if TGF-β isoforms could predict CKD progression. Results: A total of 312 patients were enrolled at baseline, of whom 275 (88.1%) had early-stage CKD (Stage 1–3). A majority, 95.2% (297/312), of the patients completed the study after 2 years follow up. The prevalence of CKD progression was 47.8% when measured by a sustained decline in eGFR of >4 mL/min/1.73 m2/year or more and 51.9% when measured by a change in uPCR > 30%. The patients with CKD progression had significantly lower eGFR and increased urine protein–creatinine ratios compared to non-progressors. Furthermore, comparing progressors with non-progressors, the median serum TGF-β1 was 21210 (15915–25745) ng/L vs. 24200 (17570–29560) ng/L and the median urine TGF-β3 was 17.5 (5.4–76.2) ng/L vs. 2.8 (1.8–15.3) ng/L, respectively. Baseline serum and urine TGF-β isoforms were unable to discriminate between CKD progressors and non-progressors after multivariable logistic regression analysis. Conclusions: Despite the multiple roles of TGF-β isoforms in kidney disease, baseline levels were not predictive of chronic kidney disease progression.
Journal Article
Lower FGFR2 mRNA Expression and Higher Levels of FGFR2 IIIc in HER2-Positive Breast Cancer
by
Dix-Peek, Thérèse
,
Dickens, Caroline
,
Valcárcel, Juan
in
alternative splicing
,
Apoptosis
,
Breast cancer
2024
Fibroblast growth factor receptor 2 (FGFR2) has been associated with breast cancer. We performed in silico analyses to investigate the FGFR2 mRNA expression and splice variants associated with breast cancer subtypes. Online databases, including cBioPortal and TCGA SpliceSeq, were used to examine the association between the FGFR2 expression and splice variants with breast cancer subtypes. A higher FGFR2 mRNA was significantly associated with luminal, oestrogen receptor (ER)-positive breast cancers, and invasive lobular carcinomas, whereas a lower FGFR2 was associated with human epidermal growth factor receptor 2 (HER2)-positive breast cancer and invasive ductal carcinomas. The epithelial alternatively spliced FGFR2 IIIb isoform was significantly enriched in ER+ breast cancer, while the mesenchymal FGFR2 IIIc isoform was significantly prevalent in HER2+ cancer. Increased levels of FGFR2 and IIIb splice isoforms are associated with less aggressive breast cancer phenotypes, while decreased levels of FGFR2 and increased IIIc splice isoform are associated with more aggressive phenotypes.
Journal Article
Correlation between volume overload, chronic inflammation, and left ventricular dysfunction in chronic kidney disease patients
by
Naidoo, Sagren
,
Naicker, Saraladevi
,
Dix-Peek, Therese
in
Hemodialysis
,
Inflammation
,
Kidney diseases
2016
Background: Fluid overload is common in chronic kidney disease (CKD) patients, potentially driving chronic inflammation and left ventricular dysfunction. We investigated the association between volume overload, chronic inflammation, and left ventricular dysfunction across subgroups of CKD patients. Methods: The study included 160 participants, comprising peritoneal dialysis (PD), hemodialysis (HD), stage-3 CKD patients, and age- and sex-matched controls (40 in each group). Fluid status was assessed using a body composition monitor (BCM); serum endotoxin, lipopolysaccharide binding protein (LBP), C-reactive protein (CRP). and interleukin-6 (IL-6) levels were measured as markers of inflammation. Echocardiography was done to assess left ventricular dimension and function. Results: Endotoxemia and volume overload were common across the spectrum of CKD patients and were aggravated by worsening kidney function. Among HD cohorts, postdialysis endotoxemia was increased among patients with dialysis-induced hemodynamic instability and was also closely related to ultrafiltration volume. Endotoxin, IL-6, CRP, and LBP levels were elevated in patients with volume overload compared to euvolemic patients (p < 0.05). Patients with elevated circulating endotoxemia had higher left ventricular mass index (LVMI) compared to patients with lower endotoxin levels. Fluid overload correlated with endotoxin levels, IL-6, and LVMI; while LVMI correlated weakly with LBP and CRP. Conclusion: CKD patients typically presented with significant endotoxemia and overt volume overload, which may contribute significantly to chronic low-grade inflammation and left ventricular dysfunction. An additive contribution from hemodialysis treatment may strongly enhance the severity of endotoxemia in HD patients.
Journal Article