No abstract available. / Thesis (M.Sc.)-University of Durban-Westville, 1990.

This study was designed to examine two premises: that the morphological "severity" of duodenal ulcers (DU) may influence the incidence of drug mediated healing and the morphological "quality" of healing after curative therapy may influence t he duration of remission. Biopsies taken at endoscopy from five healthy volunteers and from 84 patients suffering from DU were examined by light and electron microscopy. The endoscopic and morphological appearance of the mucosa within 8mm of the DU or scar, before and up to 1 year after therapy with either sucralfate, cimetidine, pirenzipine or misoprostol are described. Irrespective of the mode of therapy or whether the biopsies were from normal, juxta-DU or scar mucosa, specimens could be divided into 2 primary morphological classes: gastric metaplastic and non-metaplastic. Based on the degree of metaplastic differentiation and nonmetaplastic degeneration, these classes were further divided into 4 sub-classes. When correlated with the incidence of healing and duration of remission, metaplasia was generally found to be a positive and degenerative nonmetaplasia a negative prognostic criterion. Scores were awarded to primary morphological criteria and weighted to give high total s to favourable (metaplastic) and low totals to non-favourable (degenerative non-metaplastic) prognostic features. The sum of scores expressed as a percentage was termed the morphological index. This proved useful as a means of correlating mucosal morphology with DU healing and duration of remission. It also facilitated comparison of morphology within and between groups of patients before and after each drug regimen. The results showed that the morphological appearance of the ulcerative mucosa influenced healing and remission outcome. Discriminant analysis was applied to the numeric data that described the juxta-DU (group 1) and scar (group 2) morphology of patients treated with cimetidine in 2 studies. Separation between healed and not healed DU was achieved in 92% of group 1 and 100% (remission - more or less than 6 months) of group 2. When applied to the juxta-DU data from patients treated with cimetidine in a third study, the formulae predicted correctly in 88% of cases. In addition to predicting outcome, the formulae were used as standards to accommodate for natural variations in the prognosis of individual DU of patients enrolled for comparative drug studies. These data show that morphological analysis may be usefully employed in duodenal ulcer therapy. / Thesis (Ph.D.)-University of Natal, Durban, 1994.

Mitochondria perform functions which are central to the life of most eukaryotic cells. These organelles can be considered the ultimate energy power house of a living cell. The role of mitochondria in cancer phenotype remains a fertile area of research. Several carcinogens are known to enter the mitochondria, resulting in impaired functioning and altered structure. Aflatoxin BI (AFB1) a primary type I mycotoxin elaborated by Aspergillus flavus and Aspergillus parasiticus, is carcinogenic for a wide species range. The epoxide is capable of binding to nucleic acids and proteins, resulting in induced mutations, cellular toxicity, and eventually carcinogenesis. Approximately 250 000 deaths occur annually in both China and Africa due to patients presenting with Hepatocellular Carcinoma (HCC). The causative agents being AFB1-ingestion via contaminated foods and feeds, and the Hepatitis B Virus infection. The toxin has a multifaceted mode of attack, capable of being activated to a highly reactive and carcinogenic derivative, the AFB1-8,9-epoxide, via the cytochrome P450 enzyme system of the microsomes, endoplasmic reticulum and also the mitochondria. The epoxide is capable of binding to nucleic acids and proteins, resulting in the formation of covalent adducts. The repeated occurrence of gold labelled toxin within mitochondria from hepatomas of patients presenting with HCC suggested that these organelles were direct sites of toxin binding. Despite observations that mitochondria appear as direct and perhaps preferential targets for attack by AFB1, the actual in vivo immunolocalisation and characterisation of bound AFB1 within liver mitochondria has not been reported previously. In addition the role of AFB1-protein binding within mitochondria was investigated to determine the mode of action of the toxin, within the mitochondrial system. Liver sections from rats treated with a single lethal dose of AFB1, showed distinct ultrastructural abnormalities viz. large nuclei, increased heterochromatin, and swollen mitochondria. Immunocytochemistry revealed for the first time, the selective localisation of conjugated gold labelled toxin within the mitochondria. Toxin was found in the intracristal and peripheral spaces and frequently within the mitochondrial matrix. The mitochondria isolated from treated rats revealed significant alterations and damage to the mitochondrial membranes. The cristae were also markedly swollen with the associated clearing of the mitochondrial matrix. Western blot immunoassays revealed the presence of five AFB1-bound proteins (150kDa, 50kDa, 25kDa, 18kDa, 14kDa) in the inner mitochondrial fraction of isolated mitochondria. High pressure liquid chromatography also revealed that a significant proportion (84%) of an initial dose of toxin, was absorbed by mitochondrial protein. This study is the first to show the presence of specific mitochondrial proteins involved in toxin binding. In addition, the presence of toxin within the mitochondria and the specific binding to inner mitochondrial proteins suggest that the toxin specifically targets the electron transport chain and hence effects ATP production. This study conclusively indicates that mitochondria are direct targets for attack by AFB1 during experimental carcinogenesis. Mitochondria therefore play an important role in AFB1-mediated carcinogenesis. / Thesis (M.Med.Sc.)-University of Natal, Durban, 1998.

In order to address the contradictory reports on the rat trace element status during a vitamin 8-6 deficiency, Zn, Cu and Fe balance was assessed over 8 weeks in 3 groups of young male rats. Group 1 was the control group fed on a diet supplemented with 3,5 mg/kg of vitamin B-6. Group 2 was the marginally deficient group, fed a diet supplemented with 1,75 mg/kg of vitamin B-6 and Group 3 was the totally deficient group without any vitamin 8-6 in the diet. Diet, urine and fecal samples were analysed to determine the mean daily Zn, Cu and Fe balance for each group during each week of the study. Urinary xanthurenic acid (XA), plasma pyridoxal (PL), and plasma pyridoxal 5' -phosphate (PLP) were also analysed in order to determine the vitamin 8-6 nutritional status of each animal group. The totally deficient Group 3 showed decreased growth and food consumption when compared to the control and marginally deficient groups. There was a significant difference in XA excretion and plasma PLP and PL levels between all 3 groups with a progressive increase in XA excretion and a progressive decrease in PLP and PL levels from Group to Group 3. Although all groups were found to be in a positive balance for Zn, Cu and Fe, the totally deficient group was in a less positive balance compared to Groups 1 and 2. Furthermore, the percentage excretion of Zn and Cu, when compared to the intake, was greater in this group. This increased excretion, coupled with a decreased food intake, accounted for the lowered Zn and Cu balances in the totally deficient group. Fe excretion did not differ significantly between all 3 groups. The marginally deficient Group 2 showed no significant difference in growth, food consumption, trace element balance and excretion when compared to the control group, indicating the beneficial effects of even subminimal levels of vitamin B-6. This study confirms that the nutritional status of t~ace elements, especially that of Zn and CU, is related to the vitamin B-6 status of the animal. / Thesis (M.Sc.)-University of Durban-Westville, 1988.

No abstract available. / Thesis (M.Sc.)-University of Durban-Westville, 1989.

Pre-eclampsia, often described as toxaemia of pregnancy, historically represents one of the most widely investigated conditions relating to human reproduction. To date no firm cure has been found and a clear, well defined mechanism has not been ascribed to the pathogenesis of the disease. Researchers seem to focus on single pathways in isolation of others. The disease rather represents a multitude of possible underlying pathologies nvolving genetics, immune dysregulation, vascular maladaptation, and sociobiological factors thus complicating the approach to treatment. However, a central theme is the presence of reduced placental perfusion resulting in a hypoxic and/or ischaemic placenta and the subsequent secretion of various factors that initiate the maternal syndrome. It is within this context that we examine how an intervention such as increasing placental perfusion may represent a promising treatment strategy for this disease. We sought to manipulate the vasodilatory mechanisms of the uterine vasculature using sildenafil citrate and a flavonoid extracted from Eriosema kraussianum (Kr2), in Sprague-Dawley rats that exhibited preeclampsia-like manifestations. Both treatment regimens improved fetal outcomes and reduced blood pressure amplification and proteinuria. They also reduced the plasma concentrations of the two anti-angiogenic factors; sFlt1 and sEng. Only sildenafil citrate improved nitric oxide levels which was expected, suggesting that Kr2 causes vasodilation by some other mechanism. Nevertheless, both compounds improved both pup and placental weights, suggesting that they also improve utero-placental perfusion. These findings that selective uterine vascular dilation improves placental perfusion may be promising in averting possible death to mothers and their babies from pre-eclampsia especially in low resource environments. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.

Oxidative stress resulting from an imbalance between free radicals and antioxidants is considered to be an important etiological factor in the development and maintenance of hypertension. Angiotensin II (Ang II) has been shown to be an important regulator of blood pressure and acts to elevate blood pressure by its pressor effects. The pressor effects of Ang II are well documented but recent evidence has suggested another possible role of Ang II in elevating blood pressure, whereby it acts via an independent mechanism that is directly linked with oxidative stress. The spontaneously hypertensive rat (SHR) is a widely used model in the investigation of the pathophysiological mechanisms involved in hypertension. This study was therefore undertaken to determine whether Ang II acts as a causative factor via oxidative stress in the development and maintenance of hypertension in the SHR. This was elucidated by evaluating the role of both the endogenous in vivo levels of Ang II as well as an exogenous sub-pressor dose of Ang II, on oxidative stress and its associated parameters. The parameters evaluated included, the antioxidant status of the model on the basis of the levels of the major antioxidant enzymes viz. SOD, GPx and catalase; the free radical generating capacity, by assessing the activity of the membrane bound enzyme NADPH oxidase and the levels of H2O2. The study also evaluated the levels of the endogenous vasodilator nitric oxide (NO), remodelling of the vasculature and the level of tissue oxidative stress in the kidney. The results show that the SHR has an elevated plasma Ang II level and an elevated level of oxidative stress, thus showing that in this model there is an intimate link between oxidative stress and Ang II. The SHR also shows depleted levels of NO and thus a decreased vasodilatory capacity and increased remodelling of the vasculature. The kidney showed an increased level of lipid peroxidation, which was due to the elevated levels of oxidative stress. All of these pathophysiological changes contribute to the elevation in blood pressure in this model. The long term infusion of the sub-pressor dose of Ang II affected the SHR to a greater extent than the Wistar. Although the dose of Ang II elevated the blood pressure in both models, the degree of the pathophysiological changes associated with the elevation in blood pressure was greater in the SHR. The Ang II infusion in both these models demonstrated that in the SHR which is genetically predisposed to hypertension, adjustments are made to the antioxidant system, that result in an elevated level of protection against oxidative stress. These results show that Ang II acts as a causative factor in the pathogenesis of hypertension in the SHR via its well documented pressor effects, as well as via a multitude of independent mechanisms that are linked to oxidative stress. This is substantiated by the significant decrease in NO that is caused by the elevated oxidative stress, as well as the previously described pathophysiological changes. This study has therefore shown that Ang II has an intimate causative link with oxidative stress that results in parallel mechanisms that work concomitantly with each other in hypertension in this model. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.

Recent clinical studies have highlighted the effectiveness of immunotherapy for Gram-negative bacteraemia in humans. Studies in America, undertaken on patients with Gram-negative bacteraemia, have shown that mortality was reduced by virtually 50% in patients who received specific antiendotoxin antiserum. In India, mortality from pseudomonas septicaemia was significantly reduced by the administration of small quantities of a anti-pseudomonas immunoglobulin. The antibodies in those studies were raised by vaccination of healthy volunteers with heat-killed Gram-negative bacteria or vaccines containing endotoxin. Adverse side effects in volunteers as well as logistic and legal problems make it difficult to produce antiserum on a large scale, in this manner. In Israel, S.L. Gaffin and coworkers found that approximately 7% of plasma units in a blood bank had antiendotoxin antibody concentrations of 40 ).1g/m1 or greater. This high titre human plasma significantly protected cats from lethal endotoxic shock secondary to haemorrhage. The immunoprecipitin technique used by them to measure antiendotoxin antibody concentrations was unsuitable for screening large numbers of blood samples. To overcome this problem we have devised an enzyme-linked imounosorbent assay (ELISA) for determining the level of antiendotoxin immunoglobulin G in human plasma. The assay, which is suitable for large scale use, was found to be specific for antiendotoxin antibodies. It was calibrated using a serum sample of specific antibody concentration as determined by an ilununoprecipitin assay. Serum samples found to be high in antiendotoxin titres (> 40_ug/m1) were tested for their specificity towards endotoxins from 12 bacterial iv strains and species. While each sample was found to have its own characteristic specificities, most were found to react strongly with Sh. flexneri, S. typhimurium and S. enteritidis. The Natal Blood Transfusion Service has found that in Natal, blood units containing high concentrations of specific antibodies occur with a frequency of 3,6% among all White donors and 10,35% among all African donors. They found that African females, in turn, had almost twice the frequency of high titre serum as African males. In this study, Indian female hospital patients did not have a statistically higher frequency of high-titre serum than Indian male patients. Blood units donated to the Natal Blood Transfusion Service are now routinely screened by ELISA for antiendotoxin antibodies and those units with high concentrations (> 40 ug/ml) of antibody were pooled and fractionated to obtain a gamma globulin, Lot LG-l. The binding capacity of the LG-1 antibodies towards 12 endotoxins was examined. Binding was found to be highest with endotoxin from Sh. flexneri, S. abortus equi and S. typhimurium and intermediate with S. enteritidis and E.coli 026:B6. Binding with the other endotoxins tested was relatively low. Differential absorption experiments showed that LG-1 was made up of a mixture of cross-reacting as well as specific antibodies For example, the antibodies binding Sh. flexneri endotoxin were mainly specific. Those binding E. coli 026:B6 endotoxin were specific and cross-reacting in almost equal proportions. Antibodies to the endotoxins from the salmonella strains tested were mainly cross-reacting. The specificities of the LG-1 antibodies towards endotoxins from the various Gram-negative bacteria did not in most cases reflect the incidence of these organisms in blood cultures taken from hospital patients. V The activity of LG-1 antibodies was compared to that of normal human immunoglobulin preparations obtained from the National Blood Fractionation Centre, Pinetown and to an anti-pseudomonas immunoglobulin prepared by Wellcome Laboratories, England. The binding capacity of the antibodies in the standard globulin preparations towards most of the endotoxins tested was less than 15% of that of the LG-1 antibodies. The anti-pseudomonas immunoglobulin was shown to bind poorly to most of the endotoxins tested in comparison with binding by LG-1 antibodies. / Thesis (MMedSc.)-University of Natal, Durban, 1984.

Folic acid is a water-soluble, B-complex vitamin influencing a number of biological processes in humans and particularly important in the prevention of neural tube defects (associated with spinal bifida) in unborn children. Reliable analytical methods are therefore needed for quantisation of the amount of total folic acid (FA) in biological materials of quality assurance and regulatory purposes. What is particularly needed are rapid and reliable methods for ensuring that the correct amount of FA is consumed and the degradation rates of these compound is kept at minimum during the extraction process. Analytical methods for determination of folic acid in biological materials have been around for decades and the most common procedures include microbiological assay; biomolecular interaction analysis (BIA); immunoassay; conventional chromatographic procedure such as thin-layer column chromatography (TLC) and high performance liquid chromatography (HPLC). These procedures were replaced by HPLC, which is more rapid and in many instances yields a better resolution. Current HPLC methods uses C-18 column and reverse phase conditions in combination with ion-pair or ion suppression techniques; fluorescence or electrochemical detector, unfortunately, excitation and emission of folic acid is found not sufficiently to allow physiological levels of the form of the vitamin to be detected. In addition, ion-pair reagent nullifies the mobile phase and interferes with the absorption! fluoresce spectrum resulting in poor separation. Therefore this study was carried out to address and improve the problems that are in the existing HPLC methods. Currently scarce information is available on the determination of folic acid in biological materials by HPLC with UV detection. Serum samples were spiked with folic acid standard to check the efficiency of the method. Other wavelengths from 200 nm to 300 nm were attempted for detection of folic acid, in which the wavelength 250 nm was found to have better absorbance compared to other wavelengths. Folic acid was detected at 250 nm wavelength under isocratic elution using a mobile phase consisting of citrate phosphate buffer: acetic acid: methanol. Folic acid in maize meal was detected at 290 nm using mobile phase containing potassium phosphate containing ascorbic acid/sodium ascorbate mixture and 2-mercaptoethanol under gradient elution. The mobile phase used for gradient and isocratic elution was suitable for separation of folic acid from other compounds with flow rate of 3 ml/min modified to Iml/mim to avoid overloading of the column under isocratic elution. For good separation of folic acid under gradient elution the flow rate was set at 0.8ml/min with pH of mobile phase modified from pH 2.2 to pH 2.5. The recovery of folic acid added to human serum was 91% -100% and recovery of folic acid added in unfermented maize meal and fermented maize meal ranged from 55% - 73%. Folic acid level from unfermented maize meal and fermented maize meal ranged between 1.29 - 1.3 [!g/g and 1 - 2.1 [!g/g respectively. In conclusion the optimised method in this study gives better analytical results when compared with earlier HPLC method in terms of efficiency, reproducibility and sensitivity for folic acid in human serum and maize meal. However, there is a need to minimise the loss of folic acid during the sample treatment. The outcome of this work indicated that more work has to be done to improve extraction procedure for specific foods with minimum time preparation to sample analysis. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, Durban, 2007.

This study was aimed at investigating the potential of lactic acid fermentation in reducing myco toxin concentration in maize meal products. Maize meal was spiked separately with aflatoxin Bi, fumonism Bi, and zearalenone, and fermented for four days. During this period the concentration of each toxin and the pH of the fermented maize meal were monitored. There was a significant (p= 0.000) decrease in the concentration of all the mycotoxins, with a percentage reduction of 55-69 by the third day and 68-75 by the fourth day, respectively. Commercial amahewu samples were also screened for the presence of these three mycotoxins, and the results indicated that the samples were not contaminated with detectable levels of these toxins. An attempt was made to characterise the metabolic derivatives (by-products) of each mycotoxin following lactic acid maize meal fermentation. To achieve this maize meal samples were separately spiked with each of mycotoxin, fermented for four days and screened for specific mycotoxin derivatives (by-products) using GC/MS, HPLC and relevant standards (i.e. partially hydrolysed fumonisin Bi, aflatoxin B2a, a- and Pzearalenol). None of the targeted derivatives could be detected in the fermented maize meal samples. The potential cytotoxicity of the mycotoxin-spiked fermented samples was investigated using an SNO cell line. The fermented toxin-spiked maize meal samples with a starter culture were comparatively less toxic (29 - 36%) to SNO oesophageal cells than samples spiked with toxin without a starter culture (24 - 30%). However, this observed difference was not statistically significant (p = 0.295 - 0.681). Furthermore, cells that were only inoculated with the cell culture medium had significantly (p = 0.000) high percentage cell viability. This study indicates that it is possible to significantly reduce the concentration of mycotoxins using lactic acid maize fermentation to trace levels. However, such a reduction will not significantly alter the possible chronic toxic effects of such toxins in the diet, particularly a maize based diet containing poor quality protein. The trace amounts of these toxins in fermented and unfermented maize meal should continue to be a cause for concern. / Thesis (M.Med.Sc.)-University of Natal, Durban, 2003.