Physiology

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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.
Alzheimer’s disease dementia risk in post-traumatic stress disorder: identification of common underlying mechanisms using rat models.
(2021) Faborode, Oluwaseun Samuel.; Mabandla, Musa Vuyisile.
Post-traumatic stress disorder (PTSD) is a neuropsychiatric disorder that can develop from exposure to a trauma. Studies have shown that people who have PTSD are susceptible to developing dementia, mostly Alzheimer’s disease (AD), suggesting common underlying risk factors in the comorbidity. Although several molecular pathways have been implicated in AD and PTSD, including oxidative stress, cellular apoptosis, synaptic dysfunction and stress dysregulation, the underlying neurobiological mechanisms linking AD and PTSD are less understood. This study, therefore, investigated the effect of trauma-like exposure in an amyloid-beta (Aβ) rat model of AD. Seventy-two adult male Sprague-Dawley rats were used throughout the study. The animals were randomly divided into four groups where they received either footshocks or Aβ(1-42) injection or were exposed to footshocks and Aβ(1-42) injection or remained naive. Following inductions, the animals were tested for cognitive, locomotor and anxiety-like behaviours. Thereafter, brain samples were collected for further neurochemical analyses. Our results show that footshocks increased anxiety-like behaviour and impaired fear memory extinction in Aβ(1-42) lesioned rats. A combination of footshocks and Aβ(1-42) also reduced the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), NAD (P) H: quinone oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), and increased the expression of Kelch-like ECH-associated protein 1 (Keap1) in the amygdala and hippocampus. Prior exposure to footshocks before Aβ(1-42) lesion caused a decrease in the number of crossing in the target quadrant of the Morris water maze test and reduced percentage alternation in the Y-maze test, indicating memory deficits. There was an interactive effect of footshocks and Aβ(1-42) lesion on the downregulation of BIN1 and the upregulation of NR2B in the hippocampus. There was also an interactive effect of footshocks and Aβ(1-42) lesion on the upregulation of FKBP5 in the hippocampus, amygdala, and PFC. Our finding suggests that footshock stress can exacerbate AD-like pathology via dysregulated redox balance, BIN1 downregulation, FKBP5 and NR2B upregulation, and increased apoptosis in the brain of Aβ(1-42)-lesioned rats. These molecular changes were associated with increased anxiety, impaired fear extinction and memory deficits. These findings, therefore, suggest common molecular mechanisms in PTSD and AD. Isifo sengcindezi eba semva kwesehlakalo esibi i-post-traumatic stress disorder (i-PTSD) yisifo sokusebenzelana kwezinzwa nensebenzamqondo esidala wukwehlelwa yisehlakalo esibi. Ucwaningo selukhombise ukuthi abantu abane-PTSD basengcupheni yokuba nesifo sokukhohlwa, ikakhulukazi i- Alzheimer’s (i-AD), okuchaza ukuthi izimo eziyingcuphe enkulu ekubeni nezifo eziyizimbelambela. Nakuba izindlelamigudu eziningi zamamolekhyuli zisoleka kwi-AD ne-PTSD, okufaka nengcindezi ye-oxidative, i-cellular apoptosis, i-synaptic dysfunction kanye nokungalawuleki kwengcindezi, izindlelamigudu zempiliswanozinzwa nomzimba ezixhumanisa i-AD ne-PTSD akuqondwa ngokuphelele. Ngakho-ke lolu cwaningo, luphenye umthelela wokubekeka endaweni ecisho ibe yisehlakalo esinzima kwimodeli yamagundane i-amyloid-beta (Aβ) ye-rat model of AD. Amagundane amadala esilisa angamashumi ayisikhombisa nambili asetshenziswa kulolu cwaningo. Izilwane zehlukaniswa ngokungahleliwe zaba amaqembu amane lapho zanikwa khona amafootshocks noma umjovo we-Aβ(1-42) noma ayengathola i-footshocks nomjovo we-Aβ(1-42) noma ahlale engazi. Ukulandela ukwethulwa, izilwane zahlolelwa ukuziphatha kwazo ngokomcabango, ukuhamba nokuba nexhala. Emva kwalokho, amasampula obuchopho aqoqwa ukuze aphinde acutshungulelwe amanyurokhemikhali. Imiphumela yethu iveze ukuthi ama-footshocks enyuse ukuziphatha sakuba nexhala kanye nokuqeda ukukhumbula ukwesaba okugwegwile kuma-Aβ(1-42) onikwe amalesioned rats. Ingxubevange yefootshocks ne-Aβ(1-42) iphinde yehlisa ukuvela kwe-nuclear factor erythroid 2-related factor 2 (Nrf2), i-NAD (P) H: i-quinone oxidoreductase 1 (NQO1), i-heme oxygenase-1 (HO-1), kanye nokuvela okusezingeni eliphezulu kwe-Kelch-like ECH-associated protein 1 (Keap1) kwi-amygdala ne-hippocampus. Ukusondelana nama-footshocks kwangaphambi kwe-Aβ(1-42) kwdala ukwehla esibalweni sokuhlanganayo kwi-target quadrant yokuhlolwa kwe-Morris water maze test nenguqunguquko yephesenti kwi-Y-maze test, okuveza ukushoda kokukhumbula. Kwaba nomthelela onokungenelana wama-footshocks kanye ne-Aβ(1-42) lesion ekulawulenikwehlisa i-BIN1 nasekulawulenikukhuphula i-NR2B kwi-hippocampus. Kwaphinde kwaba nomthelela ongenelanayo we-footshocks ne- Aβ(1-42) lesion ekulawulenikukhuphula i- FKBP5 kwi-hippocampus, i-amygdala, ne- PFC. Esikutholile kuphakamise ukuthi ingcindezi ye-footshock ingabhebhezela isakhiwosifo esifuze i-AD nge-dysregulated redox balance, i-BIN1 downregulation, i-FKBP5 ne-NR2B upreguation, i-apoptosis ephezulu ebuchosheni be-Aβ(1-42)-ekuma-lesioned rats. Lezi zinguquko kumamolekhyuli zazihlotshaniswe nokwenyuka kwexhala, inqedakwesaba egwegwile nokulahlekelwa wukukhumbula. Ngakho-ke lokhu okutholakele, kuphakamisa izindlela ezejwayelekile zomumo wamamolekhyuli kwi-PTSD ne-AD.
An investigation on the effects of a rhenium (V) compound with uracil-derived ligands on markers associated with hepatic, cardiovascular and renal complications in diet-induced prediabetic rats.
(2023) Siboto, Angezwa.; Khathi, Andile.; Ngubane, Phikelelani Siphosethu.; Sibiya, Ntethelelo Hopewell.
Prediabetes is a metabolic disorder that often precedes the onset of type 2 diabetes mellitus. This development of this asymptomatic condition is associated with chronic consumption of high calorie diets and sedentary lifestyles. Prediabetes results in decreased insulin sensitivity in the peripheral tissues resulting in elevated blood glucose levels that are not high enough for a diagnosis of type 2 diabetes. This moderate hyperglycaemia has been shown to lead to trigger complications such as non-alcoholic fatty liver disease, renal dysfunction and cardiovascular disease which are generally only diagnosed during type 2 diabetes. The current management strategy for prediabetes consists of a combination of pharmacological and lifestyle intervention. The pharmacological agents such as metformin while lifestyle intervention involves dietary modification to lower calorie diets. Studies show that prediabetic patients tend to be more dependent pharmacological intervention and struggle with changing diets thus lowering the efficacy of drugs such as metformin. This often leads to the eventual development of prediabetes. Therefore, there is a need for new pharmacological agents that can remain effective in both the presence and absence of dietary intervention. In our laboratory we have synthesised a novel rhenium (v) compound with uracil-derived ligands that has shown promising biological activities that include anti-hyperglycaemic effects in diet-induced prediabetic rats. This compound was shown to improve insulin sensitivity in peripheral tissues in prediabetic rats. To advance from this knowledge, this study sought to investigate the effects of the rhenium (V) compound with uracil-derived ligands on markers associated with hepatic, cardiovascular and renal complications in diet induced prediabetic rats model.
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.
The case for critical thought: an investigation into contemporary determinist knowledge, its social effects, and the alternative offered by a 'mode 2' approach to teaching, learning and research.
(2002) Skinner, Jane.
This thesis is centrally concerned with the current nee-liberal world order and its effects upon society. It is concerned to expose the contradictions and weaknesses within the knowledge systems that underpin our political reality. It considers economics as the determining discourse of neo-liberal politics, analytic biology as its determining discourse of individual persons, and analytic and neo-pragmatist philosophy as its leading systems of thought. In each case it finds a linear rationalism compatible with the determinist materialism of noo-Darwinism, and indeed explicitly invoking Darwin. This seems to vindicate Manuel Castells's fmding of this 'Knowledge Society' as driven by 'an abstract, universal instrumentalism'. The thought systems of this economic liberalism have seen politics subsumed within economics, de-humanising most of the institutions of the earlier Liberal tradition, to the detriment of both freedom and democracy. But it disputes Castells's assumption that this is a necessary reality and finds in neo-liberal education the exception to this dehumanising trend. Revitalised as 'Mode 2' knowledge production, this form of teaching, learning and research is found to be ideally suited to challenge the underpinnings of the very social order which initially produced it. The thesis as a whole is designed to employ Mode 2 methods in order to support this contention. Using this approach it seeks to demonstrate that in place of neo-Darwinism the ideas of the South African natural scientist Eugene Marais, concerning the significance of conscious thought itself within evolution, can provide a more convincing epistemoloy than the behaviourism and materialism of analytic biology. It finds John Maynard Keynes's acceptance of economics as a moral and not a natural science, more logically convincing and more inherently useful for social reconstruction than the current mathematicisation of economic theory. Prevalent philosophical approaches appear to serve only to reinforce the systems of thought already found (and found wanting) in politics, biology and economics. But again these philosophies are shown to be vulnerable to a Mode 2 critique, particularly employing the ontological understanding of the contemporary pragmatist philosopher Joseph Margolis, whose strong version of relativism allows for both bivalent and multivalent truth values more appropriate to understanding the complex realities of ethical and democratic societies.
Characterising epigenetic alterations following cocaine consumption.
(2017) Ajonijebu, Duyilemi Chris.; Mabandla, Musa Vuyisile.
Complementary data from clinical and animal research have converged on the hypothesis that persistent use of psychostimulant drugs such as cocaine may not only involve pathological alterations in neural processes that subserve reward–related learning, but also complex interactions between genes and the environment through epigenetic modifications. Fosb and Crem (cAMP response element modulator) are among the central trans-factors suspected to mediate these long–term neurobiological changes due to their potential roles in drug reward. However, the critical question that concerns inheritance of epigenetic marks associated with parental cocaine experience in social settings, offspring vulnerability and modifying maternal–foetal environment by fostering, remains poorly understood. The present study therefore aimed to investigate possible associations between cocaine–induced behavioural changes in social contexts and DNA methylation patterns of inducible transcription factors in the prefrontal cortex (PFC) and hippocampus (HPC) of the exposed parent mice. We further examined whether the induced epigenetic changes were inheritable and then determined the impact of early postnatal (PN) fostering on associated neurobiological changes in the offspring of drug-exposed parents. In doing so, we were able to investigate the interaction between epigenetic and environmental factors in relation to drug consumption. Behavioural response of C57BL/6 mice to cocaine treatments were examined using conditioned place preference (CPP) and IntelliCage (IC) phenotyping techniques. In the CPP experiment, male mice received 6 cocaine injections (10mg/kg, i.p.) on alternate days followed by 6 days of extinction learning. A subthreshold dose of cocaine (5mg/kg, i.p) was later injected to reinstate CPP behaviour. In the IC, female mice were group–housed and initially had free access to drugs (300mg/L cocaine and 12% v/v ethanol in their drinking bottles) and water for 30 days to investigate consumption preference. Subsequently, withdrawal effect and alternate nose-poke learning tasks (ANT) were examined in the following 28 days with concurrent access to cocaine and water. In both experiments, locomotor activity and novelty exploration/recognition memory of mice were examined post cocaine treatments. DNA methylation status of Crem and Fosb gene promoters, within the HPC and PFC, were also assessed using quantitative real–time polymerase chain reaction. Thereafter, cocaine exposed or unexposed male and female mice were matched for mating to produce offspring with lineal phenotypes. At birth, some of the offspring were cross-fostered to further examine the impact of PN fostering on drug-induced epigenetic changes. Locomotion, memory competence and DNA methylation status were also evaluated in the offspring similar to the parent mice. In male mice, cocaine treatment resulted in significant changes in CPP during conditioning. After extinction learning, the subthreshold dose of cocaine did not reinstate the conditioned behaviour. The treatment increased locomotor activity in the open field but decreased novelty exploration in the object recognition task. These changes were characterized by significant hypomethylation in Crem and Fosb gene promoters only in the PFC. During the first 30 days of free access to cocaine, ethanol or water in the IC, the female mice spent significantly more time licking and consuming cocaine than ethanol, whereas consumption of either drugs was significantly less than water. Overall, the mice exhibited motivational deficits as manifested by their inability to learn the ANT. Our data also showed that prolonged access to cocaine in the IC decreased locomotor activity while recognition memory remained intact in the cocaine–experienced mice compared to their controls. These changes were accompanied by hypomethylation or hypermethylation in the promoters of Fosb and Crem genes in the PFC and HPC of the cocaine–experienced mice, respectively. In the offspring, memory performance and locomotor activity were not affected by parental cocaine exposure, except that recognition memory was impaired by early PN fostering in offspring lineally inclined to either paternal and/or combined parental cocaine experience. Crem was hypomethylated only in the PFC of offspring of cocaine–exposed parent mice, while fostering the offspring reversed the expression. Significant change in Fosb methylation was only observed in the HPC of fostered offspring. Together, these findings suggest differential responses of the substrate brain regions to the converging environmental stimuli and dynamic regulation of induced neurobiological changes via DNA methylation. Overall, the data also provide some evidence that cocaine–induced epigenetic marks can be inherited by the non-drug exposed offspring while early PN fostering may enhance molecular switching that may render the individual vulnerable to drug consumption. Key words: Cocaine; social environment; IntelliCage, conditioned place preference; Crem; Fosb; DNA methylation; hippocampus; prefrontal cortex; epigenetic inheritance; postnatal fostering.
Chemical investigation of isihlambezo or traditional pregnancy-related medicines.
(2004) Brookes, Kathleen Bridget.; Dutton, Michael Francis.
This study was undertaken to redress the scant knowledge regarding the chemistry and mode of action of pregnancy-related traditional medicines, or isihlambezo (Zulu), which are used by 60 to 80% of women in South Africa. The three selected plants are among the six most frequently cited species from the approximately 90 used by traditional healers. The purpose of the study was to identify components which could cause uterine contractions, those with nutritional value for the foetus and mother, and those with any toxic effects. Plant root extracts were purified via silica gel column chromatography and bioassays were carried out on the fractions, using isolated rat uterine tissue. Purified compounds were identified via spectral techniques, and some were characterised by comparison to authentic standards using HPLC, and others by matching their GC-MS spectra to library standards. Thirty-eight compounds were identified in total, the majority of these being novel to the species concerned. Those isolated from Combretum kraussii were 1 sitosterol, 2 combretastatin, 3 3',4-tri-O-methylellagic acid, 4 combretastatin B-1, 5 combretastatin A-1, 6 3,3'-di-O-ellagic acid lactone, 7a ellagic acid lactone, 7b ellagic acid, 8 and 9 a mixture of combretastatin B-1 and A-1 glucosides, 10 and 11 partly characterised glucosides of ellagic acid. Those isolated from Gunnera perpensa were 12 3',4-tri-methylellagic acid, 13 ellagic acid lactone, 14 1,1'-biphenyl-4,4'-diacetic acid, 15 p-hydroxybenzaldehyde, 16 Z-methyl lespedezate, 17 and 18 partly characterized higher glucosides of Z-methyllespedezate. Those isolated rom Rhoicissus tridentata were 19 (-)-epigallocatechin, 20 (+)-gallocatechin, 21 procyanidin B3, 22 procyanidin B4, 23 (+)-catechin hydrate, 24 (+)-mollisacacidin, 25 (+)-epicatechin, 26 fisetinidol-(4a-8) catechin, 27 (-)-fisetinidol, 28 fisetinidol-(4b-8)catechin, 29 gallic acid, 30 epicatechin-3-0-gallate, 31 partly characterized hydrogel of glucose, 32 sitosterol, 33 sitosterolin, 34 y-sitosterol, 35 oleanolic acid, 36 lupen-3-one, 37 20-epi-y-taraxastananol and 38 triacontanol. The compounds with the greatest in vitro uteroactivity were predominantly proanthocyanidins or phenolic glucosides. It is proposed that effects of phenolic glucosides could be due to the interaction of the sugar moiety as well as the phenolic moiety with the receptor site in muscle tissue. The corresponding phenolic aglycones isolated were only moderately uterotonic, or unreactive by comparison. Non-polar compounds such as sitosterol and sitosterolin showed minimal enhancement of the uterine response at low concentrations, and inhibition at higher concentrations. Aqueous root extracts of the plants were all found to be non-toxic according to cell-viability tests using monkey vero cells and human fibroblasts. Extracts are therefore considered safe for human consumption, although it is recommended that Rhoicissus tridentata be used with caution because it showed the lowest cell viability of the three species, and uterine hyperstimulation has been attributed to this species, as well as CNS depression and respiratory arrest. Ions which could be nutritionally beneficial in pregnancy, calcium, iron, and phospate, were present in low in aqueous extracts. Levels of calcium and potassium ions were considered to be too low to directly stimulate uterine muscle. Proanthocyanidins, combretastatins, ellagic acid derivatives and phytosterols, with health-promoting properties, were also identified.
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.
The cytotoxic effects, anti-iflammatory, antioxidant, antibacterial, and antidiabetic properties of eight selected South African plants for medicinal purposes.
(2020) Nkala, Bongani Alphouse.; Mbongwa, Hlengiwe Prosperity.; Qwebani-Ogunleye, Tozama.
People from the Southern African region have been using the fauna and flora of the region in their homes for millennia to treat all sorts of ailments and complaints with great success. This knowledge transfer was done through ’apprenticeships’ and oral communication. Certain communities consider medicinal plants to be safer than drugs and that they can treat more than one ailment. This study investigated cytotoxic effect, antimicrobial, anti-inflammatory, antioxidant, and antidiabetic properties of eight selected South African plants for medicinal purposes. Plant species were collected from the Walter Sisulu National Botanical-Gardens and were extracted with 90% methanol (1 g/10 ml) and concentrate to 10 mg/ml. Antimicrobial activities were determined by the microplate dilution method to establish the ability of the plant extracts to inhibit or kill pathogenic organisms with minimal inhibitory concentrations and minimum bactericidal concentration. Cytotoxicity effects were determined with Alamar blue and crystal violet cell viability assays, against C2C12 and RAW 264.7 cells. Anti-inflammatory effects were identified with stimulated lipopolysaccharide RAW 264.7 cells, and nitric oxide inhibition was measured with Griess reagent assay. The estimation of preliminary phytochemical, antioxidant (DPPH and ABTS radical scavenging), and alpha-amylase inhibition were determined with standard methods. The plant extracts inhibition and bactericidal effects were observed against all bacteria, namely: Lippia javanica (0.25±0.00 to 1.13±0.29 mg/ml); Ziziphus mucronata leaf (0.44±0.00 to 1.00±0.00 mg/ml); Erythrina lysistemon (0.44±0.00 to 1.08±0.00 mg/ml) and Schkuhria pinnata (0.5±0.00 to 1.34±0.00 mg/ml). All plant extracts exhibited flavonoids, phenols, terpenoids, and coumarins. The antioxidant inhibition was observed above 80% for Schkuhria pinnata, Lippia javanica, Clerodendrum myricoides, and Erythrina lysistemon. Also, these plant species exhibited an alpha-amylase inhibitory effect of 80%. The IC50 values were > 1000 μg/ml. All plant extracts demonstrated some degree of an antiinflammatory effect. However, Clerondendrum myricoides (35% - 89%), Lippia javanica (26% - 77%), Erythrina lysistemon (23% - 76%), Schkuhria pinnata (27% - 65%), and Vernonia oligocephala (16% - 58%) with IC50 value >1000 μg/ml, exhibited a marked antiinflammatory effect. Therefore, the presence of phenolic, flavonoids, anti-inflammatory, antioxidants, and α-amylase properties are potential solutions towards the management of diabetes and other chronic inflammatory diseases. Keywords: medicinal plants, antimicrobial, cytotoxicity, anti-inflammatory, antidiabetic, antioxidant.
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.

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