Masters Degrees (Physiology)

Permanent URI for this collectionhttps://hdl.handle.net/10413/7046

Browse

Now showing 1 - 20 of 78

The acute effects of dioxidovanadium on blood glucose concentration and oxidative stress in the hippocampus of non-diabetic male Sprague Dawley rats and the chronic effects of dioxidovanadium on selected markers associated with hippocampal dysfunction in male streptozotocin-induced diabetic rats.
(2022) Dayanand, Yalka.; Ngubane, Phikelelani Siphosethu.; Khathi, Andile.; Sibiya, Ntethelelo Hopewell.
Diabetes mellitus is a disease associated with derangements in glucose metabolism and chronic hyperglycaemia. Chronic hyperglycaemia induces oxidative stress and inflammation that affect glucose sensitive hippocampal neurons resulting in generation of amyloid plaques and tau tangles. These are the primary markers used in the detection of neurodegenerative diseases such as Alzheimer’s and dementia. Hence, there is a strong correlation between diabetes and memory impairment. Current therapeutic options such as bolus insulin have been successful in the management of the disease. Despite the efficacy of these therapies, they however have been shown to possess undesirable effects that exacerbate the secondary pathological effects of diabetes on the hippocampus thereby contributing to the detriment of cognitive tasks such as learning and memory. Therefore, there is a need to explore alternative treatments. Transition metals have been shown to possess therapeutic effects with vanadium possessing the greatest potency in lowering blood glucose concentrations. However, studies have demonstrated toxic accumulation of vanadium in the hippocampus which result in the generation of oxidative stress and neurodegeneration. In our laboratory, we have synthesised dioxidovanadium (V) complex by attaching organic ligands to reduce the toxicity and improve potency of the metal. This complex has been shown to efficiently reduce blood glucose and elicit cardio and reno-protective properties. Despite these advancements the effects of this complex on the hippocampus and learning and memory are yet to be established. Therefore, in this study the aim was to evaluate the effect of dioxidovanadium complex on selected learning and memory parameters. Methodology The effect of vanadium on the brain was studied acutely and chronically. In the acute study, animals were separated into 2 groups, non-diabetic control group and a non-diabetic animal group which was were treated with vanadium complex (40 mg.kg-1 p.o). The treatment was administered at time 0. Subsequently an n=3 from each group was sacrificed at regular time intervals (1 hour, 2 hours, 6 hours, 24 hours, 5 days, 10 days) in each group. Blood glucose concentration was monitored before sacrificing and hippocampal tissue was harvested for malonaldehyde (MDA) analysis and glutathione peroxidase (GPx1) and tumour necrosis alpha (TNF-α). The second study was conducted over 5 weeks and consisted of an untreated non-diabetic control, a diabetic control, a positive insulin treated group (0.175 mg.kg-1 s.c) and two dioxidovanadium (V) treated groups (40 mg.kg-1 p.o), a non-diabetic and a diabetic group. Blood glucose was monitored weekly and the Morris water maze was conducted on the last week of the study. After 5 weeks the animals were sacrificed and hippocampal tissue was harvested for malonaldehyde (MDA) analysis, glutathione peroxidase (GPx1) tumour necrosis alpha (TNF-α), amyloid beta (Aβ) and hyperphosphorylated tau (pTau) ELISA’s. Results Acutely, dioxidovandium (V) did not lower blood glucose significantly in comparison to the control group. Interestingly, MDA, GPx1 and (TNF-α) were also not significantly different from the control group over all time periods in the study. Chronically, the glucose concentration of the dioxidovandium (V) treated diabetic group was significantly lowered when compared to the untreated group which displayed significantly increased glucose concentration in comparison to the non-diabetic control. The non-diabetic dioxidovanadium (V) treated group did not show a significant difference in glycaemic level. Increased MDA concentration in the diabetic group was significantly lowered by dioxidovanadium(V) treatment. GPx1 concentration in the dioxidovanadium (V) treated group significantly improved in comparison to the diabetic untreated control. The non-diabetic dioxidovandium (V) treated group showed no significant change in MDA and Gpx1 after the 5-week period. There was no significant difference in TNF-α in dioxidovanadium (V) treated groups, diabetic and non-diabetic. The concentration of Amyloid β was significantly lower in the diabetic control when compared to the non-diabetic control. The dioxidovanadium (V) treated groups, both diabetic and non-diabetic did not have a significant difference in comparison to the diabetic control. pTau concentrations in all groups did not significantly differ. Latency times for the last day of training the Morris water maze followed the same trend. The probe test results, which measured spatial memory, for the diabetic untreated and dioxidovanadium (V) treated groups were significantly reduced in comparison to the non-diabetic control group. The non-diabetic untreated and non-diabetic dioxodivanadium (V) treated were not significantly different. Conclusion Dioxidovanadium (V) treatment in non-diabetic animals did not induce hypoglycaemia acutely however reduced blood glucose concentration in diabetic animals when administered chronically. Dioxidovanadium (V) did not induce oxidative stress and may protect against neurodegeneration by enhancing antioxidant status and therefore was considered as a pro-oxidant in the hippocampus.
The alteration of dopamine receptors in L-DOPA (L-3,4-dihydroxyphenylalanine) induced dyskinesias.
(2021) Mokgokong, Makwena.; Mabandla, Musa Vuyisile.; Msibi, Zama Ndlondlo Princess.
L-3,4-dihydroxyphenylalanine (L-DOPA) can ease symptoms of Parkinson’s disease (PD), butextended use of L-DOPA causes abnormal involuntary movements (AIMs) called L-DOPA induced dyskinesias (LIDs). The present study aims to investigate alterations in HPA axis stimulation, neuroinflammation, DA signalling, and cholinergic signalling using molecular markers in a rat model of LIDs. A unilateral 6-hydroxydopamine (6-OHDA) lesion in the medial forebrain bundle of male Sprague-Dawley rats was used to model Parkinsonism. The PD rat model was treated with L-DOPA to further model LIDs. L-DOPA treated groups included rodents treated for 14 days and rats that developed AIMs during 28 days of treatment. LIDs severity was rated using the AIMs score. Motor skills were assessed using the elevated beam walking test. Cognitive functions were assessed using the Morris water maze test and the novel object recognition test. The concentrations of tumour necrosis factor-alpha (TNF-α), corticosterone, acetylcholinesterase (AChE), and dopamine (DA), and the expressions of D1 receptor (D1R) and D2 receptor (D2R) were quantified. L-DOPA treatment for 14 days improved the 6-OHDA-induced hypokinesia, incoordination, spatial learning, and spatial memory but did not improve recognition memory impairment. Prolonged (28 days) L-DOPA treatment led to AIMs development and failed to improve 6-OHDA-induced spatial memory impairment. L-DOPA treatment significantly increased striatal TNF-α and striatal DA concentration, cerebellar TNF-α and DA concentration, prefrontal cortex (PFC) DA and AChE concentration, but significantly reduced striatal AChE concentration, the concentration of TNF-α and D1R expression in the PFC, plasma corticosterone, and hippocampal AChE concentration. When treatment was prolonged for 28 days, striatal D2R expression significantly increased, while cerebellar TNF-α and DA concentration significantly decreased. Increased striatal D2R signalling increases motor output since the direct basal ganglia (BG) pathway is activated in LIDs. The present study showed significantly increased cerebellar DA concentration in response to BG hypoactivity; however, as striatal D2R increased cerebellar DA decreased. The connectivity between the BG and cerebellum in PD increases off L-DOPA and lowers On L-DOPA. The cognitive decline in the 6-OHDA lesioned rodents and those treated with L-DOPA results from increased AChE concentration. High AChE concentration leads to increased ACh catabolism which impairs cognitive function.
The association between incretin hormones concentrations and the development of diet-induced Prediabetes.
(2023) Mzimela, Nhlakanipho Mphatheni.; Khathi, Andile.; Sosibo, Aubrey Mbulelo.
The increase in the prevalence of type two diabetes mellitus(T2DM) is attributed to unhealthy lifestyles and high-calorie diets. T2DM is a chronic metabolic condition characterised by impaired insulin function and high blood glucose concentration. Prediabetes is an intermediate hyperglycemic condition that frequently occurs before the onset of T2DM. This condition is characterised by a gradual reduction of insulin sensitivity by insulin receptors in insulin-dependent cells, frequently followed by significantly high plasma glucose levels. In this condition, the blood glucose concentration is insufficient to diagnose T2DM. Studies have looked at how incretin peptides affect the pathology of T2DM. However, the link between incretin peptide levels and the onset of prediabetes remains unknown. Additionally, the effect of a low carbohydrate, high unsaturated fat diet on incretin levels during the reversal of prediabetes has not been established. Thus, this study aimed to assess the role of incretin levels in the emergence of prediabetes and the effect of a low carbohydrate, high unsaturated fat diet on incretin levels during the reversal of prediabetes. Methods The first study was conducted using 24 male Sprague-Dawley rats, divided into two groups given a standard rat diet (NPD) (=12), while the other group was given a high-fat high carbohydrate (HFHC) (n=12) diet. Six animals from each group were sacrificed at week 10 and week 20, and blood was collected for biochemical analysis at each time interval. After 20 weeks, the HFHC fed group was found to be prediabetic and were therefore named the prediabetic group (PD). At week 10, the NPD group had the following mean measurements for the NPD and HFHC groups respectively: Glucose (4.3mmol/L and 5.9mmol/L), Insulin (40.26 and 118.32pmol/L), HbAc1 (4.9 and 5.15%), GIP (9.308 and 12.91pmol/L),GLP-1 (18.53 and 15.73pmol/L), Leptin(1.92 and 1.08mmol/L), and Ghrelin (122.1 and 186.5pmol/L ). At week 20, the PD group had the following mean measurements for the NPD and PD groups: Glucose (4.4mmol/L and 7.35mmol/L), Insulin (41.18 and 159.42pmol/L), HbAc1 (4.7 and 6.65%), GIP (10.03 and15.1pmol/L),GLP-1 (21.52 and 6.73pmol/L), Leptin (2.16 and 0.78mmol/L ), Ghrelin (124.2and 210.63pmol/L). After 20 weeks of pre-diabetes induction, the second study began with 18 male Sprague-Dawley rats. Group A continued with the standard diet and was used as a non-prediabetic control (NPDC) (n=6). The pre-diabetic group B (n=12) was split into two experimental groups. One of the groups continued a HFHC diet and served as the pre-diabetic control group (PD)(n=6). In contrast, the other group had a diet intervention where the diet was changed to a low carbohydrate-high unsaturated fats diet (PD+DI) (n=6). All groups were then maintained on their respective diets for a further 12 weeks. At week 32, the PD+DI group had the following mean measurements: Glucose (5.367mmol/L), Insulin (188.5ng/ml), HbAc1 (4.62%), GIP (24.08pg/ml) , GLP-1, Leptin (1.267ng/ml) , and Ghrelin (17.09pg/ml). XVI Results In the first study, after 20 weeks, the HFHC diet resulted in moderate hyperglycaemia, elevated plasma insulin, elevated HbA1c and insulin resistance in the PD group compared to the NPD group. There were also significantly increased GIP and ghrelin concentrations with significantly low GLP-1 and leptin concentrations in the PD group compared to the NPD group. Interestingly, at week 10, there was moderate hyperglycaemia, elevated plasma insulin, elevated HbA1c and insulin resistance in the HFHC group. There were also significant GIP and ghrelin levels with significantly low GLP-1 and leptin concentrations, but there was no prediabetes. In the second study, there were significantly reduced blood glucose levels, plasma insulin levels, HOMA-IR index, and HbA1c in the PD+DI group compared to the PD group. In the PD+DI group, there are significantly reduced GIP and ghrelin levels with significantly increased GLP-1 and leptin concentrations compared to the PD group. However, when the PD-DI group is compared to the NPDC group, there is no significant difference in all measured parameters. Conclusion The first study's findings show that chronic ingestion of a HFHC diet causes dysregulation of incretin hormones from week 10, while prediabetes was only diagnosed at week 20. This dysregulation of incretin hormones precedes the onset of prediabetes and may trigger chronic insulin stimulation, leading to prediabetes development. In the second study, we observed the effect of diet on incretins as they play a significant role in developing and reversing pre-diabetes. Chronic consumption of a HFHC diet led to elevated blood glucose and insulin concentration, resulting in abnormal concentrations of incretins. The abnormal incretins then maintained this state of hyperglycemia and hyperinsulinemia, resulting in prediabetes. Chronic consumption of a LCHF by the pre-diabetic rats led to reduced concentrations of incretins, which could have led to a reduced HbA1c and eventually to the reversal of pre-diabetes. The results of this study suggest that incretin concentrations preceded the development of prediabetes and may even have a role in its development as well as its reversal.
Biomarkers and histopathologic changes in rats with monocrotaline-induced pulmonary hypertension following administration of antiretroviral medications.
(2020) Adeoti, Adekunle Olatayo.; Nadar, Anand.
Pulmonary hypertension (PH) is a progressive life-threatening vasculopathy characterized by dysregulated pulmonary vascular remodelling that results in an increased pulmonary vascular resistance, right ventricular hypertrophy, right heart failure and untimely death. Human Immunodeficiency Virus (HIV) is a recognized cause of PH with a relatively stable prevalence of HIV associated PH of 0.5% in most developed countries. One of the animal models of PH is comprises a once off monocrotaline (MCT) in rats, which leads to PH that mimics typical PH presentation observed in humans. Early administration of antiretroviral medication has been shown to prevent the development of PH in human subjects, however, in advanced cases no significant improvement was reported. The impact of antiretroviral medications is controversial; however, nucleoside reverse transcriptase inhibitors (NRTI) and protease inhibitors (PI) have been shown to improve outcome in PH animal models. A potential connection between combination antiretroviral and PH in human subjects has been established which was contrary the protective effects of solely administer NRTI. The study was conducted to test the hypothesis that antiretroviral medications could ameliorate MCT induced PH in rat models and identify potential biomarker for PH. An approval was given by the Animal Research Ethics Committee of the institution (AREC/066/018M) of University of KwaZulu-Natal, Durban, South Africa, to conduct the study. Forty adult male Sprague-Dawley rats (body weight: 200-250 g) were randomly divided into five groups (n=8 per group). The treatment groups received a single intraperitoneal injection of MCT (60 mg kg-1) while the control group received an equivalent volume of intraperitoneal saline injection. Zidovudine (100 mg kg-1), ritonavir (30 mg kg-1), or combination of both drugs (zidovudine 100 mg kg-1 and ritonavir 30 mg kg-1) were administrated daily for the study period of 28 days to the rats in three of the four groups with MCT for 28 days respectively. On the twenty-eighth day of the study, rats were sacrificed, and the harvested lungs and hearts organ were analyzed. Gene expression was conducted using RT-PCR for the antioxidant’s enzymes, ASK-1 and a laboratory assay for lipid peroxidation was performed. A significantly higher mRNA gene expression of catalase, superoxide dismutase, and glutathione peroxidase in the heart tissue of the antiretroviral treated rats was observed and compared to the untreated groups. There was an increase in malondialdehyde (MDA) in the heart tissues of untreated rats (37.01±1.16 nmol/g, p<0.0001) compared to the control group (3.46±0.97 nmol/g) with an associated reduction in MDA by the antiretrovirals. Furthermore, an increase in the total antioxidant capacity (TAC) in AZT (0.85±0.02 nmol/g, p<0.0001), RTV (0.63±0.03 nmol/g, p<0.0001) and combination of AZT/RTV (0.77±0.06 nmol/g, p<0.0001) compared to untreated (0.28±0.025) rats. Furthermore, lower relative mRNA gene expression of ASK-1 was observed in the heart of the treated rats with zidovudine (2.67 ± 0.09, p < 0.0001), ritonavir (2.57 ±0.11, p < 0.0001) and a combination of both (2.75 ± 0.06, p < 0.0001) when compared to rats in the untreated group. An overexpressed mRNA gene of ASK-1 in the untreated rats (12.0 ± 0.90, p < 0.0001) when compared to the control. This study shows evidence that zidovudine and ritonavir ameliorate MCT-induced PH in rats by suppressing oxidative stress. Also, ASK-1 is a potential biomarker for anti-apoptotic characteristics of PH. Our findings indicate the antioxidative role of antiretroviral medications in PH and the role of biomarkers in PH.
Cardiopulmonary exercise testing for high-risk South African surgical patients.
(2007) Biccard, Bruce McClure.
Aim: To determine the prognostic value of cardiopulmonary exercise testing (CPET) for major vascular surgery in South African patients. Methods: CPET has been used in Durban since October 2004 to predict cardiac risk for high-risk patients undergoing major vascular surgery. A submaximal 'anaerobic threshold' (AT) test was conducted on all high-risk patients. Patients were classified into two groups: 'low AT' where the oxygen consumption at the AT was <1 lml.kg^.min"1 for cycling or < 9ml.kg"1.mkf1 for arm cranking and 'high AT' when the patient surpassed these targets. Analysis of all in-hospital deaths following surgery was conducted by two independent assessors blinded to the CPET test result. Deaths classified as primarily 'cardiac in origin' have been used in this retrospective cohort analysis. Results: The AT measured during CPET was not a statistically significant pre-operative prognostic marker of cardiac mortality. However, the survivors of the patients with a 'low AT' may be identified by their response to increasing metabolic demand between 5 and 7 ml.kg^.min"1. Survivors were more dependent on increasing heart rate, while non-survivors were more dependent on oxygen extraction. When this information is added to the AT, CPET was the only test statistically associated with cardiac mortality, in comparison to Lee's Revised Cardiac Risk Index and the resting left ventricular ejection fraction which were not statistically associated with cardiac death. A hundred percent of patients with a positive test died of cardiac causes, while 11% of the patients with a negative test had cardiac deaths. The risk ratio associated with cardiac death following a positive test was 8.00 [95% CI 3.8-16.9]. The sensitivity was 0.25 [95% CI 0.04-0.64], the specificity was 1.00 [95% CI 0.90-1.00], the positive predictive value was 1.00 [95% CI 0.20-0.95] and the negative predictive value was 0.88 [95% CI 0.74-0.95]. Conclusions: CPET provides valuable prognostic information in our surgical population.
A comparative assessment of local, commercial and homemade amahewu with respect to nutritional value, hygiene, and other health benefits to the community.
(2003) Mbongwa, Hlengiwe Prosperity.; Gqaleni, Nceba.
Fermentation is a process by which primary food products are modified biochemically by the action of microorganisms and/or their enzymes. Several societies have, over the years, intentionally carried it out to enhance the taste, aroma, shelf-life, texture, nutritional value and other properties of food. It is used in many parts (lithe world. However, there are regional differences in use and these depend on the availability of raw materials, consumption habits. and other socio-cultural factors. This study was aimed at (comparatively) assessing, local commercial and homemade amahewu with respect to nutritional value, hygiene and other health benefits to the commirn ity. Methods employed were Thin Layer Chromatography (TLC) (mycotoxins), High Perliffmance Liquid Chromatography (HPLC) (mycotoxins, sugars and amino acids), Dumas (proteins), SOxhlet (lipids) and intubation technique (metabolisable energy) to analyse maize meal and amahewu samples from various regions. The regions sampled included mal3heleni (South Coast) and kwaNgcolosi (North Coast) villages. Commercial amahewu was analysed with kind permission from Clover SA. Species from the following genera were isolated and identified from amahewu samples: Lactobacillus, Saccharonivccs, Lcuconostoc, Lactococcus, Panioca, Entcrobacter and kleb•iella. Saccharotnyces was detected in commercial samples only. Gram-negative strains were identified in most of manheleni village samples. No traceable amounts of aflatoxin BI (AFB1), fumonisin B 1 (FBI) and zearalenone (ZEA) were found in Clover SA samples. AFB I was detected in 40% of both maize meal and amahewu samples from maBheleni (range 0.55 — 0.84ng/g and 8.3x10 5 — 9.1x10-5ng/g respectively). From the same village, 100% of the maize meal and 80% of the amahewu samples were contaminated with FBI (range 4.1 47.2ng/g and 1.4 ---- 6.9ng/g respectively). ZEA was detected in all maize meal samples (range 0.9 — 4.3ng/g). None of the amahewu samples contained detectable levels of ZEA. All maize meal and amahewu samples from kwaNgcolosi were contaminated with AF13 1 (range 8.3 — 30.I ng/g and 0.04 - 0.102ng/g respectively). FB I was detected in 75% of both maize meal and amahewu samples from the same village (range 0.5 — 4.1ng/g and 0.04 0.56ng/g respectively). ZEA was also found in all maize meal samples and 75% of amahewu samples (range 3.7 — 16.4ng/g and 0.03 -- 0.06ng/g respectively). MaBheleni, Clover SA and kwaNgcolosi maize meal and amahewu samples contained vitamins B1, 13 2 and B6 with a range of 0.31+0.21 - 4.48±0.81 B 1 ; 0.15±0.14 - 1.67±0.33 B2 and 0.05±0.07 - 0.77±1.45 lig/g B6. Fat levels ranged from 0.28±0.40 to 4.54±0.05 percentage by weight. The levels of proteins varied from 4.02±0.02 to 8.40±0.04 percentage by weight. Starch concentrations ranged from 31.51.5.28 to 75.911.92g/100g. Maize meal samples contained glucose and maltose, while glucose, fructose, sucrose, maltose, M-triose, DP 4 and 5 and DP >15 were detected in amahewu. Apparent and true metabolisable energy for homemade and commercial Freeze-dried amahewu was 13.194 and 13.696MJ/kg (AME N ); and 13.605 and 14.106M.Ekv ( 1 MEN ), respectively. This study has shown that lactic acid maize fermentation reduce' the levels of AF13 1 , FB I and ZEA toxins in maize meal, inhibits the growth of most Gram-negative bacteria, and in some instances, fermentation did improve the nutritional value. Metabolisable energy analysis represents an important tool to assess whether or not compounds ingested are converted to sources of energy in the body and utilised. Amahewu fermentation yielded beneficial products (probiotics: reduced mycotoxins levels and reduced starch). In conclusion, natural lactic acid maize fermentation to produce amahewu will do more good than harm to the consumer, therefore, people need to be advised on how to safely store their maize and also to be encouraged to consume their stored maize in fermented form.
Comparison of the effects of oral and transdermal adminstration of chloroquine on selected haematological parameters and inflammatory cytokines in P.berghei- infected male Sprague-Dawley rats.
(2016) Gumede, Nontobeko Myllet.; Mabandla, Musa Vuyisile.
Introduction Chloroquine (CHQ), the mainstay antimalarial drug accumulates in organs and alters physiological function. Hypoglycaemia, impairment of kidney function and anaemia are among an array of pathophysiological manifestations caused by malaria infection or oral CHQ treatment. However, it is unclear whether this anaemia is solely due to the parasite or by CHQ. Therefore, there is need to investigate and distinguish between the pathophysiological effects of malaria alone and those of CHQ treatment. The purpose of the current study was to investigate and compare the effects of using oral CHQ treatment or a transdermal CHQ patch in the treatment of malarial infection. To this effect, we evaluated changes in haematological parameters as well as plasma cytokine concentrations in male Sprague-Dawley rats. We also looked at the morphological effects of various visceral organs following malarial infection and subsequent treatment with CHQ. The study duration was 3 weeks divided into pre-treatment (days 0-7), treatment (8-12) and post treatment (13-21) periods. CHQ treatment was either administrated orally (30mg/kg, twice daily) or via a once off CHQ matrix patch (56mg/kg). Oral CHQ treatment reduced red blood cell count, haematocrit, haemoglobin and mean corpuscular haemoglobin in non-infected and infected animals. Topical application increased the above parameters in infected rats. Oral CHQ decreased pro-inflammatory cytokine concentration in infected rats on the day (day 8 of the experiment) of the treatment period in comparison to pretreatment (baseline) measurements. However, on the last day (day 12) of the treatment period and during the post-treatment period there was an increase in pro-inflammatory cytokine concentration while patch application decreased pro-inflammatory cytokine concentration in infected rats throughout the experimental period. P.berghei-infected rats following oral and transdermal CHQ delivery showed mild morphological changes on the liver, heart, kidney and spleen by comparison to infected control animals. In non-infected rats oral CHQ treatment showed adverse morphological effects on the architecture of these organs, while no changes were observed following transdermal CHQ delivery. C-reactive protein is an acute phase protein, a component of innate immune response and is useful in early detection of inflammation. Oral CHQ administration increased CRP concentration. However, CRP concentration was not affected in patch treated animals. The results of the current study have demonstrated that the once off patch application of the CHQ-formulation has no morphological effects when compared to oral administration of CHQ on various organs. The ability of the pectin-CHQ matrix patch to provide slow, sustained CHQ releases into the circulation, avoids drug dumping in various tissue organs therefore circumventing the adverse effects associated with oral administration of CHQ. In addition, our results show that both CHQ and malaria parasite result in the development of anaemia by affecting RBCs and plasma pro-inflammatory cytokines. These findings suggest that transdermal CHQ delivery could therefore be used in conjunction with or as an alternative treatment in the management of malaria.
Contractile effects of Gunnera perpensa and Rhoicissus tridentata bioactive extracts in isolated rat uterine muscles.
(2014) Dube, Sinenkosi Carol.; Musabayane, Cephas Tagumirwa.
Abstract available in PDF file.
The cytotoxic effects of aflatoxin B1 and fumonisin B1 on cultured human cells.
(2004) Van der Stok, Mary Elizabeth.; Myburg, Rene Bernadette.
Aflatoxin B1 (AFB1) and Fumonisin B1 (FB1), potentially cytotoxic and carcinogenic mycotoxins are common contaminants of agricultural commodities in South Africa and thus could be detrimental to the human immune system. Many of the cytotoxic effects of AFB1 require its bioactivation to an epoxide, which will bind covalently to macromolecules to form protein and DNA adducts. Fumonisin B1 is a competitive inhibitor of sphingosine and sphinganine N aceyltransferase, which are key components in the pathways for sphingolipid biosynthesis. Accumulation of free sphingoid bases, which are both cytotoxic and mitogenic, could provide a plausible explanation for the toxicity and carcinogenicity of FB1. The cytotoxic effects of AFB1 and FB1 on normal human lymphocytes, individually and in combination were assessed using the methylthiazol tetrazolium (MTT) bioassay. Two different methods of treatment were used, the treatment of isolated normal human lymphocytes for 12, 24, 48, 72 and 96 hours and whole blood treated for 12 hours. Flow cytometry and fluorescent microscopy were used to determine whether AFB1 and FB1 (5uM and 50uM), individually or in combination, were capable of inducing apoptosis, necrosis or nuclear fragmentation in isolated lymphocytes and whole blood treated for 12 hours. DNA damage was evaluated using the comet assay. The results showed that AFB1routinely induced higher levels of cytotoxicity in isolated lymphocytes than FB1. In the combination treatment, the mitogenic properties of FB1 appeared to partially counteract the cytotoxic effect exerted by AFB1. When whole blood was treated with the same concentration and ratio of toxin, FB1 was shown to be more cytotoxic than AFB1. The combination treatment of whole blood was shown to be cytotoxic in a dose dependent manner. The toxins appeared to exert a greater cytotoxic effect, when treated in combination than individually at higher concentrations. Aflatoxin B1 induced increased levels of apoptosis and necrosis in isolated lymphocytes while treatment with the FB1 resulted in increased levels of apoptosis at both concentrations. Treatment with the combination also resulted in increased levels of apoptosis. The levels of apoptosis were reduced in whole blood lymphocytes when compared to isolated lymphocytes. However, treatment with AFB1 and FB1 resulted in increased levels of apoptosis. Both AFB1 and FB1 are capable of inducing nuclear fragmentation. Treatment with FB1 (5uM and 50uM) resulted in greater degree of fragmentation than AFB1. The most nuclear fragmentation was induced by the 5uM combination treatment. The 50uM combination treatment of isolated lymphocytes induced the most DNA damage. As both toxins are common contaminants and have been known to coexist, this could be a potential area of concern for public health.
The cytotoxic effects of deoxynivalenol and fumonisin B1 on the HT-29 human colonic adenocarcinoma cell line.
(2005) Reddy, Krishnaveni.; Chuturgoon, Anil Amichund.
The human population can be considered as a subject of combined exposure to chemicals against which the gastrointestinal tract represents the first barrier. The most relevant are those compounds that occur in plants which are used as foods, medicines and beverages. Of special interest are the mycotoxins deoxynivalenol (DON) and fumonisin B1 (FB1), two of the most commonly encountered food-borne mycotoxins and curcumin, a popular spice and pigment reported to have antineoplastic properties. In this study, the HT-29 cell line was used to assess the toxicity of the mycotoxins DON and FB1 (5uM and 50uM) as well as the possible cytoprotective effects of curcumin (50uM) on colonic cells. Mixtures of both mycotoxins were also assessed to determine any possible interaction. Cytotoxicity, DNA fragmentation, cellular morphology and cell surface alterations were evaluated using the methylthiazol tetrazolium (MTT) bioassay, the single cell gel electrophoresis (SCGE) assay, fluorescence microscopy and scanning electron microscopy respectively. Deoxynivalenol displayed cytotoxic and genotoxic effects as well as induced morphological features of apoptosis and cell surface alterations that worsened with increasing concentration. Fumonisin B1 exhibited a proliferative effect at the high concentration however DNA damage and cell surface alterations worsened with decreasing concentration. Mixtures of DON and FB1 displayed similar effects to those exhibited by DON in terms of cytotoxicity, DNA fragmentation, morphology and cell surface alterations indicating that DON is able to antagonise the effects of FB1 at the concentrations tested. Curcumin appeared to exhibit a protective effect that was prominent when co-administered with the 50uM toxin concentration. Low concentrations of DON and FB1 (5uM) were sufficient to induce apoptosis in this cell line and suggest a danger from natural contamination by these toxins. Curcumin, however, warrants further investigation with regards to its cytoprotective activities in the presence of these mycotoxins as it could present a promising candidate for a natural chemoprotective agent in the armamentarium against mycotoxin induced cancers.
The cytotoxic effects of T-2 toxin on normal human lymphocytes.
(1998) Moodley, Therishnee.; Chuturgoon, Anil Amichund.; Dutton, Michael Francis.
T -2 toxin is an immunosuppressive mycotoxin that has been conjoined with several symptoms and diseases as early as the turn of the century, but whose mechanisms of action are still being investigated. Accordingly, this study was an attempt to determine the cytotoxic effects of T -2 toxin on normal human lymphocytes in vitro, with particular emphasis on mitochondrial viability, cellular and nuclear morphology as well as the localisation of the subcellular sites of toxin interaction. The cytotoxicity of T -2 toxin was assessed with the use of a methylthiazol tetrazolium (MTT) assay. This assay targeted the succinate dehydrogenase activity of the lymphocytic mitochondria, over a range of concentrations of T-2 toxin at various incubation times. The morphology of treated lymphocytes was analysed with the use of transmission electron microscopy and the localisation of the toxin was accomplished via immunocytochemistry. DNA fragmentation studies formed an integral part of the analyses. The cytotoxicity assay indicated that not only was cell viability inversely proportional to both the dose and exposure time, but that the eftects of the different doses were only evident at prolonged incubation times (12-24 hours). The electron microscopy studies showed that T-2 toxin (1,56 ug/ml) induced apoptosis (cell suicide) in normal human lymphocytes. This was determined by the observation of chromatin condensation and nuclear disintegration within the toxin treated lymphocytes. Apoptosis seemed to occur independently of mitochondrial damage at 6 hours of exposure to T-2 toxin. The presence of polyribosomes within the treated lymphocytes indicated that protein synthesis was not inhibited. Anti-T-2 toxin conjugated gold label was present in all areas of damage, particularly within the nuclei of the T-2 toxin treated lymphocytes. The DNA fragmentation results showed that T-2 toxin induced fragmentation in lymphocytes, the extent of which was directly proportional to the exposure time. It appears that the early signs of T-2 toxin induced apoptosis in normal human lymphocytes can be determined by damage to the nucleus.
A cytotoxic evaluation of aflatoxin B1, zearalenone and their epoxide derivatives using human cell lines.
(1996) Pillay, Dharmarai.; Chuturgoon, Anil Amichund.; Dutton, Michael Francis.
Since the discovery of mycotoxins in food, the thrust of biochemical and toxicological research has been carried out on animals which has proven to be uncoordinated and not easily extrapolated to humans. Over the last decade, there have been increasing pressures to review and reduce the use of animals in experimental toxicological studies. Consequently in this study aflatoxin B1 (AFB1), zearalenone (Zea) and their epoxide derivatives have been evaluated using in vitro assays. The HepG2, A549 and Hela cell lines were used for assessing the cytotoxicity, effects on cellular metabolism and sites of action of AFB1, Zea and their derivatives. The cytotoxicity of these mycotoxins was evaluated using the methylthiazol tetrazolium (MTT) reduction assay. Cells, treated with mycotoxins were prepared for transmission electron mlcroscopy (TEM), immunocytochemistry (ICC), scanning electron microscopy (SEM), confocal and light microscopy. From the cytotoxicity assay it was found that the epoxide derivatives were more toxic than the parent toxin when exposed to HepG2 cells with no significant differences in toxicity levels in A549 and Hela treated cells. Both epoxide derivatives displayed a regression of hepatoma cell proliferation at high doses (25ug/ml) while lower concentrations (<12.5ug/ml) enhanced cell growth. Microscopy analyses showed distinct cellular alterations. When exposed to AFB1 (12.5ug/ml) hepatoma cells showed prominent ultrastructural alterations such as areas of cytoplasmic lysis and increased numbers of secondary lysosomes while cells exposed to Zea (l2.5ug/ml) displayed numerous ovoid mitochondria and proliferation of rough endoplasmic reticulum which is indicative of enhanced protein synthesis. The presence of label in toxin treated cells is suggestive of the effects of these mycotoxins. Such cellular changes may lead to altered metabolism and cell function.
Determination of exposure of humans to selected mycotoxins with particular reference to aflatoxins.
(1995) Early, Deborah Angeline.; Dutton, Michael Francis.; Chuturgoon, Anil Amichund.
Mycotoxins are poisonous secondary metabolites commonly produced by fungi and are involved in human disease conditions known as mycotoxicoses. There is evidence to show that food eaten by the rural Black population of Southern Africa is contaminated with mycotoxins. A tenuous relationship exists between the occurrence of mycotoxins in foods and certain disease conditions in humans. In order to verify this relationship, efforts have, in the past, been made to detect mycotoxins and their metabolites in physiological fluids and tissues. The difficulty with this approach is that mycotoxins in the body have short half lives, being rapidly excreted or metabolised to other forms. More recently it has been shown that aflatoxin B1, as its activated epoxide, can conjugate with macromolecules such as nucleic acids and proteins. These survive for much longer than the free toxins and by suitable methods can be isolated and measured. This allows for a much better estimate of exposure of the individual to aflatoxin. This study reviews and evaluates screening methods for the detection and analysis of mycotoxin contamination in rural foodstuffs such as maize and groundnuts. Methods for the production of aflatoxin-lysine and protein adducts are motivated and developed then used in the identification of naturally occurring adducts in humans. Isolation and quantitative analysis techniques are proposed to routinely screen patients for evidence of aflatoxin exposure.
The determination of unilateral ratios (knee and shoulder muscle strength), of provincial cricketers.
(2002) Lock, Natasha.; Mars, Maurice.
Abstract available in PDF.
Development and application of an ELISA method of analysis for fumonisins
(2000) Biden, Patricia May; Dutton, Michael Francis.; Chuturgoon, Anil Amichund.
Fumonisins, mycotoxins produced by the fungus, Fusarium moniliforme, which grows on maize, are a major worldwide agricultural problem. Consumption of contaminated maize feeds causes a wide variety of toxic effects in animals depending on the species of animal. In humans, high concentrations of fumonisins have been shown to correlate with increased incidence of oesophageal cancer (OC). Most analyses for fumonisins are done using high performance liquid chromatography (HPLC) which requires time-consuming extraction and clean-up prior to preparation of a fluorescent derivative. Enzyme-linked immunosorbent assays (ELISA), which are sensitive and specific, are a viable alternative but commercially available antibodies and kits are extremely expensive. Polyclonal antibodies against fumonisin B, (FB,) were raised in chickens and rabbits; all animals produced antibodies from week 2 onwards, the highest titre was at week 8 from one of the chickens. Cross-reactivities with FB, analogues were checked. A sensitive, quantitative competitive indirect ELISA (CI-ELISA) was developed and optimised; range 0.2 to 20 ng/ml (in buffer), detection limit 0.2 nglml (in buffer), intra-assay coefficient of variation (CV) was 5.33 % and inter-assay 7.04%. This method was adapted to analyse human plasma and urine samples. After removal of proteins by boiling, the range of recoveries of FBI were 94.7% toI12.4% at 4 ng/ml; and 94.6% to 108.7% at 8 ng/ml. Blood and urine samples from patients with OC (40 plasma, 17 urine), controls (21 plasma, 12 urine) and patients with other forms of cancer (20 plasma, 10 urine) were collected from hospitals in the Durban Metropolitan area and analysed for fumonisins. Detectable levels (>0.4 nglml) were found in 86.9% of plasma samples and 94.9% of urine samples. Statistical evaluation showed a highly significant difference between plasma results for OC and controls (p<0.000 1) but no significant difference between the urine results. Comparison of other forms of cancer and controls showed no significant differences for either the plasma or the urine samples. However, there was a highly significant difference between the OC and other forms of cancer results for both plasma (p<0.005) and urine (p<0.05) samples. Some samples (9 plasma, 8 urine) were checked by HPLC. For plasma samples there was correlation between the ELISA and HPLC methods (r = 0.656, p<0.005) but not for urine samples.
The effect of dietary egg on human plasma cholesterol and triglyceride levels.
(1990) Raidoo, Kogie.; Burger, F. J.
No abstract available.
Effect of highly active antiretroviral therapy (HAART) on HIV-1 tat protein-induced neurotoxicity.
(2014) Zulu, Simo Siyanda.; Daniels, William Mark Uren.; Mabandla, Musa Vuyisile.
Background: HIV-1-trans-activating (Tat) protein has been associated with development of HIV associated neurocognitive disorder (HAND). Previous studies have demonstrated that Tat protein causes neurotoxicity through an increase in reactive oxygen species (ROS) leading to damage of proteins and other cellular components. Tat has also been shown to cause excessive production of pro-inflammatory cytokines. However the role of antiretroviral agents in the neuropathology of HIV is not known. The objective of this study was to investigate whether a combination of antiretroviral drugs (Zidovudine, Lamivudine and Efavirenz, a highly active antiretroviral therapy, HAART) is effective in reducing the toxic effects of Tat protein in the rat hippocampus. Materials and methods: Male Sprague-Dawley rats were divided into four groups (n=10 per group). Each rat received bilateral intrahippocampal injection of either Tat protein (5μg/10μL) or vehicle, followed 7 days later by a combination of antiretroviral drugs (Zidovudine 12mg/kg, Lamivudine 6mg/kg and Efavirenz 24mg/kg) or saline injected intraperitoneally, twice a day, for 7 days. After treatment, animals were sacrificed and hippocampal tissue was collected for analysis of cleaved caspase-3, 4- hydroxynonenal (NHE), tumor necrosis factor alpha (TNF-α), phosphorylated extracellular signal regulated kinase (pERK) and Synaptophysin. Results: Tat increased cleaved caspase-3 levels in the hippocampus. Antiretroviral treatment decreased the Tat-induced increase in cleaved caspase-3. Tat increased HNE, a marker of lipid peroxidation and reduced hippocampal synaptophysin. The latter Tat-induced effects were not reversed by antiretroviral treatment. The antiretroviral drug combination activated the pERK pathway and increased TNF-α levels in hippocampal tissue, independent of Tat infusion. Discussion: Our findings showed that antiretroviral drugs reversed Tat-induced cleaved caspase-3, reducing apoptosis but did not reverse Tat-induced increase in lipid peroxidation and the synaptic marker, synaptophysin. The evidence suggests that the combination of antiretroviral drugs may be toxic, elevating hippocampal pERK and TNF-α levels. However, these effects could also be beneficial to the individual, since TNF-α has been shown to inhibit viral replication. The present results provide novel insight into the mechanism of antiretroviral action.
The effect of infra-red laser therapy on fibroblast activity in cell culture.
(1997) Mars, Susan.; Chuturgoon, Anil Amichund.
Abstract available in PDF.
Effect of titanium dioxide nanoparticle aggregation on mouse myoblast cellular cytotoxicity and nitric oxide synthesis.
(2017) Phoswa, Wendy.; Mackraj, Irene.
ABSTRACT Introduction: The emerging interest of engineered titanium dioxide nanoparticles (TiO2 NPs) in medical, agricultural, industrial and manufacturing sectors have raised health questions worldwide. Therefore, the objective was to assess the effect of physiochemical properties of titanium dioxide nanoparticles (TiO2 NPs) on the cellular cytotoxicity, proliferation and physiological properties. Methods: TiO2 NPs were suspended in varying concentrations of bovine serum albumin (BSA γ-globulin) and characterised using nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) for the determination of particle size, aggregation state, and zeta potential. The effect of TiO2 physiochemical properties on cellular cytotoxicity and proliferation was assessed in vitro on mouse myoblast (C2C12) cells using the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] and BrdU assay respectively. Nitric oxide (NO), a major signalling molecule was measured using a biochemical test. in vitro. Results: There was an increase in size, distribution, surface charge and reduced aggregation in BSA stabilised TiO2 NPs in comparison to non-stabilised TiO2 NPs. Increased cytotoxicity of cells treated with monodispersed TiO2 NPs compared to cells treated with aggregated TiO2 NPs (p<0.001) was observed. A significant decrease in cell viability in cells treated with BSA (0.5, 0.8 and 1.0 mg/ml) stabilised TiO2 NPs (40, 120, 240, 320 and 400 mg/ml) in a dose-dependent manner in contrast to cells treated with BSA (0.3 and 1.5 mg/ml) stabilised TiO2 NPs (40, 120, 240, 320 and 400 mg/ml) dose dependent manner was observed (p<0.05). However, there was a greater decrease in cell viability in BSA (0.8 mg/ml) stabilised TiO2 NPs (40, 120, 240, 320 and 400 mg/ml) compared to other BSA concentration (p<0.05). In addition, there was a significant difference in DNA proliferation of the control and treated cells. A significant difference in DNA damage was observed in cells treated with BSA compared to non-treated cells, especially at BSA concentrations of 0.8 and 1.5 mg/ml. A significant difference in DNA damage in cells treated with TiO2 NPs in combination with BSA (0.8 and 1.5 mg/ml) was obtained. There was greater difference in DNA damage of cells exposed to TiO2 NPs in combination with 0.8 mg/ml compared to TiO2 NPs in combination with 1.5 mg/ml. More interestingly there was a significant difference between the levels of nitric oxide (NO) in 40 and 400 mg/ml TiO2 NPs treated cells in comparison to cells treated with BSA (0.3-1.5 mg/ml) stabilised TiO2 NPs (40 and 400 mg/ml) (p<0.05). There was a significance difference in the levels of NO between cells treated with 40 mg/ml TiO2 NPs vs (0.3, 0.5, 0.8 and 1.0 mg/ml) BSA stabilised TiO2 NPs (40 mg/ml) (p<0.05). However, there was greater significant difference between 400 mg/ml TiO2 treated cells vs BSA (0.5, 0.8 and 1.0 mg/ml) stabilised 400 mg/ml TiO2 NPs (400 mg/ml) (p<0.05). Discussion/Conclusion: The use of BSA as a nanoparticle stabiliser impacted upon physiochemical properties for the determination of in vitro cytotoxicity. These findings indicate that particle size needs to be taken into consideration when assessing nanoparticle toxicity. The results also indicate that less aggregated TiO2 NPs are more toxic than more aggregated TiO2 NPs and have a potential to inhibit cellular signalling mechanisms such as NO signalling and cellular proliferation.
The effect of ultradistance running on premenopausal women of different ethnic groups.
(2005) McGregor, Avril.; Mars, Maurice.; Cassim, Bilkish.
No abstract available.

Browse

Browsing Masters Degrees (Physiology) by Title