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. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2007.

Oxidative stress, resulting from an antioxidant/free radical imbalance, is considered to be an important etiologic factor in the patho-physiological changes associated with salt sensitive hypertension. An important unresolved issue in hypertension research is the mechanism for organ damage during the development of the syndrome. Reactive oxygen species (ROS) such as the superoxide radical (02) , hydrogen peroxide (H202), and the hydroxyl radical (OH), may playa critical role in the pathogenesis of hypertension by targeting the very tissue that is responsible for regulating blood pressure, during the hypertensive state. Thus, this study was undertaken to evaluate the antioxidant and free radical status in the DSS rat strain, which has been shown to be an excellent model of salt sensitive hypertension. The antioxidant status was evaluated on the basis of the vascular superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels, and the free radical status was evaluated on the basis of the plasma H20 2 concentration. The levels of malonyldialdehyde (MDA), which is a bio-marker for lipid peroxidation was used to determine the level of oxidative stress in the kidney, liver and brain. The kidney and liver were also subjected to an induced free radical mediated lipid peroxidation, by exposing the tissue to increasing known concentrations of H202 (2.5mM - 15mM). The level of lipid peroxidation was used to assess the tissues antioxidant buffering capacity to an induced free radical "attack". The results have shown that the DSS strain may have a compensatory increase in vascular SOD levels, to counter an increase in 02-. SOD levels were significantly lower during salt loading. The GPx levels were significantly lower in the DSS strain, and showed a slight increase during salt loading. The results demonstrate that the DSS strain has a compromised antioxidant status compared to the DSR strain. The plasma H202concentration displayed non-significant changes in the DSS strain, however salt loading did result in a non-significant increase in the plasma H202 concentration in the DSS strain. The GPx : HZ02 ratio, demonstrated an inadequate increase in GPx levels during salt loading to neutralise this non-significant increase in HzOz concentration. The kidney showed an increased level of in vivo lipid peroxidation, which could implicate increased tissue damage, and thus confirm the kidney as being a target organ during the hypertensive state. The liver and brain showed non-significant differences in the level of in vivo lipid peroxidation and are therefore thought not to be target tissue in the hypertensive state. The kidney displayed a decreased antioxidant buffering capacity to the induced free radical "attack", thereby demonstrating the tissue's decreased ability to neutralise an increased free radical level. Although the liver displayed a "normal" level of in vivo lipid peroxidation, it also displayed a decreased antioxidant buffering capacity to an induced free radical "attack", showing that the liver is able to cope with in vivo free radical levels, but at higher free radical levels, its loses its ability to quench a free radical "attack" and thereby minimise lipid peroxidation. The in vivo lipid peroxidation levels of the kidney, liver and brain have shown that tissues have varying abilities to cope with tissue oxidative stress, and behave differently, in their free radical quenching abilities. These results have shown that a compromised free radical and antioxidant status results in oxidative damage to the tissue responsible for regulating blood pressure. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, Westville, 2006.

The effects on the cardiac cycle length of stimulating the vagus nerves with single supramaximal electrical shocks depended upon when they were stimulated during the cycle. A maximum prolongation of the cardiac cycle was obtained when the vagi were stimulated 167 msec (SD±64) after the peak of an electrocardiogram P wave. The interval between a P wave and the subsequent vagal stimulation was called Pl-St interval. Pl-St(max) was the Pl-St interval at which maximum prolongation of the cardiac cycle occurred. Pl-St(max) increased significantly (p (0.001) with longer cardiac cycles. When the Pl-St intervals were shorter or longer than 167 msec (SD±64) the effects of vagal stimulation were less. The latent period for the effects of vagal stimulation was 195 msec (SD±32) The latent period also increased significantly (p(O.Ol) with longer cardiac cycles. The rise time of the vagal effect, obtained by subtracting (Pl-St(max)+ latent period) from the control cardiac cycle length, was 124 msec (SD+31) and occurred between Pl-St intervals of 167 msec (SD±64) and 291 msec (SD±70). The rise time did not vary with cardiac cycle length (p) 0.1), but the magnitude of the maximum response to vagal stimulation was inversely proportional to rise time (p <. 0.02). The peak response to vagal stimulation must have occurred when the vagal effects pegan somewhere in the middle of diastolic depolarization of the pacemaker cells in the S-A node. The reasons for this were discussed. The half-decay time for the effects of vagal stimulation was 210 msec (SD±102). The slope of the curve relating the prolongation of the cardiac cycle length to Pl-St is positive at Pl-St intervals less than 167 msec (SD±64) and negative at Pl-St intervals between 167 msec (SD±64) and 291 msec (SD±90). The positive slope ranged from 0.13 to 0.48 with a mean of 0.23. The paradoxical responses of the S-A node to vagal inhibitory input obtained by Reid (1969), Levy et al (1969)and Dong and Reitz (1970) would be explained by the dependence of the cardiac cycle length upon the time of arrival of vagal stimulus in relation to the previous P wave and upon the slope of the curve relating the prolongation of the cardiac cycle length to Pl-St interval being positive and between zero and two at Pl-St intervals less than 167 msec (SD±64. The effects of single shock stimulation of the vagus nerves persisted for 3.890 sec (SD+l.255)7 the number of cardiac cycles involved varied between 5 and 11. The duration of the effects of vagal stimulation did not depend upon when during the cardiac cycle the vagi were stimulated. A "dip" in the response to vagal stimulation was present in all the experiments. The possibility of the "dip" phenomenon being due to simultaneous stimulation of the sympathetic fibres in the vago-sympathetic trunk was ruled out. It is suggested that the "dip" phenomenon may be due to transient accumulation of K+ in the interstitial fluid surrounding the pacemaker cells in the S-A node.There was no paradoxical response of the smooth muscle in the distal colon of the adult rabbit when the frequency of sympathetic inhibitory input was continuously increased. A paradoxical response in the frequency but not in the size of the contraction of the smooth muscle was obtained when the sympathetic nerves were stimulated with bursts of stimuli, each burst consisting of 5-40 impulses, 10 msec apart. One may conclude from this that the delay of the next spontaneous contraction but not the inhibition of the size of smooth muscle contraction is dependent upon the arrival time of a burst of stimuli during a contraction cycle. This was confirmed in an experiment when the sympathetic nerves were stimulated with single bursts of stimuli applied at different times during the contraction cycle. It is unlikely that such a paradoxical response would occur under physiological conditions as this would require the natural sympathetic efferent discharges to the smooth muscle to occur in regular bursts, each burst consisting of impulses at a high frequency. Stimulation of the sympathetic nerves at 3, 5, 10 and 25 PPS caused an inhibition of the size and frequency of smooth muscle contraction in the distal colon of the newborn rabbit. Assuming that the cholinergic fibres are excitatory there is therefore no evidence for the sympathetic fibres to the distal colon being cholinergic in the newborn rabbit. This is contrary to Burn's (1968) report of the sympathetic fibres being motor and cholinergic to the small intestinal smooth muscle in the newborn rabbit.The heart rate increased rapidly at the onset of exercise and then more gradually over the rest of the exercise period. The initial increase in the heart rate during exercise was not affected by adrenergic blockade but the subsequent increase in heart rate was significantly reduced by adrenergic blockade. Hence the increase in heart rate at the onset of exercise is due primarily to a decrease in the cardiac vagal efferent discharge, whereas the subsequent increase in heart rate is due to both a further decrease ln vagal discharge and an increase in sympathetic discharge to the S-A node. In almost all the sub jects there was initially a rapid decline in the heart rate in the post-exercise period, but subsequently the heart rate returned to resting levels in a variety of ways. These were classified into 5 types. Of particular interest to the present study was the Type V pattern of heart rate change. This was characterised by an increase in heart rate of 6 beats or more per minute during the post-exercise period, with or without superimposed arrhythmia. The Type V pattern may be the equivalent of the paradoxical responses to inhibitory input demonstrated in animal experiments i.e. an increase in the heart rate with increasing vagal stimulation frequency. Type V pattern occurred more frequently at mild exercise levels (4 out of 14) than at moderate exercise level (lout of 14) and also more frequently in adrenergic blocked individuals (11 out of 28) than in control subjects (5 out of 28) It is suggested that the sympathetic effects on the P-R interval and arterial baroreceptor modulation of vagal efferent discharge protect again st the occurrence of paradoxical responses to vagal inhibitory input. They may do so by confining the vagal discharge to the rise time of vagal effect during the cardiac cycle. On the other hand the Type V pattern in p-adrenergic blocked individuals may be due to a decrease in the vagal discharge, in which case Type V pattern would not be a paradoxical response. The changes in minute ventilation in the post-exercise period were also variable. Besides a gradual decline in minute ventilation there were also gradual increases and sudden increases and decreases in minute ventilation. These may represent a form of paradoxical response to increasing inhibitory input and decreasing excitatory input to the respiratory neurones in man. However, all the changes in minute ventilation could also be explained by fluctuating excitatory and inhibitory neural input to the respiratory neurones. / Thesis (MD)-University of Natal, Durban, 1973.

Diabetes mellitus (DM) has become a global threat in developing and developed countries, where diabetic patients are more prone to cardiovascular complications, a condition called diabetic cardiomyopathy. Studies have shown a direct link between hyperglycaemia and an increase in the production of reactive oxygen species in cardiac cells leading to diabetic cardiomyopathy. This study tests oleanolic acid, a bioactive compound from the plant Syzigium aromaticum as an antioxidant which could have a potential role in management of DM. Aims i) To extract Oleanolic acid (OA) from Syzigium aromaticim, ii) Investigate the antioxidant effects of plant derived OA in an in-vitro model of hyperglycaemia induced oxidative stress. Methods The flower buds of the Syzigium aromaticim [(Linnaeus) Merrill & Perry] (Myrtaceae) plant (commonly called cloves) were used to isolate OA. The ethyl acetate solubles from the cloves were subjected to chromatographic fractionation to yield OA powder. Spectroscopic analysis was done using 1D and 2D 1H and 13C NMR techniques for the identification of the structure of the compound. This compound was then used in vitro to test for its antioxidative properties. H9C2 cardiac myoblasts were employed which were treated with normoglycaemic (5.5 mM) and hyperglycaemic (33 mM) glucose conditions. The cells were then treated with oleanolic acid to test for its antioxidant properties. We looked at a dose-dependent (0, 20, 50 μM) and time-dependent effects of OA treatment (6 and 24 hrs) following 48 hours glucose exposure. ROS levels were measured using H2DCF-DA fluorescence staining using microscopy and flow cytometry techniques for analysis. xviii Results Recrystallisation of the powder with ethanol and inspection of the 1 and 2- dimensional 1H- and 13C-NMR spectra of the compound with comparison to literature data confirmed OA molecular structure and IUPAC numbering similar to that of literature characterized and confirmed the structure of oleanolic acid. In cell specific data high glucose treatments on H9C2 cells showed increased ROS production (22 ± 6 % and 20 ± 7 % n= 3 p< 0.01) for 6 and 24 hrs treatments, respectively, compared to their normoglycaemic control groups. The 6 h OA treated group showed a decrease in ROS production with 26.6 ± 17.4 % for the 20 μM while for 50 μM there was a 37.7 ± 14.3% decrease. A ROS reduction trend was observed in the normoglycaemic group, but this was significant at 24 hrs with 46.8 ± 45.3% and 57.3 ± 9 % for both 20 and 50 μM treatments, respectively. The 24 hrs OA treated group showed a dose-dependent decrease in ROS with 50 μM more pronounced (80.7% ± 4.5 %). The 20 μM OA treatments also showed a 15.7 ± 19 % decrease in ROS. Discussion In the present study, we have evaluated the antioxidant effects of OA in vitro following extraction of the compound from Syzigium aromaticim. The oxidative stress induced by hyperglycaemia was attenuated by oleanolic acid and this also translated into decreased ROS suggesting its use as an antioxidant in alleviating cardiovascular complications associated with diabetes mellitus.

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. / Thesis (M.Med.)-University of Natal, Durban, 1996.

Vaccines directed against the influenza virus become ineffective due to continuous mutation. An alternative approach might be to control replication at the genomic level by enzymatic methylation of the polymerase genes. Hence in this study, a method to locate and successfully isolate the H1N1 influenza A polymerase genes was investigated. The virus was cultured in chick embryos via the allantoic route using aseptic techniques. Following incubation, the allantoic fluid was isolated and washed to remove any contaminating blood cells. The allantoic fluid was checked for fungal and bacterial contamination using the blood agar test and the presence of the virus was established by the haemagglutination titration test. Viral particles were pelleted by ultracentrifugation. Electron microscopy verified the morphology and size of these viruses while immunofluorescence studies, using a monoclonal antibody, confirmed the influenza A strain. The ribose test verified the presence of RNA in the samples. Purified viral pellets were pooled and homogenised in buffer containing guanidine thiocyanate, mercaptoethanol and sarkosyl. The samples were incubated on ice before mechanical disruption of the virus. Viral RNA was isolated from the upper aqueous layer after a standard phenol/chloroform extraction procedure. RNA was quantified spectrophotometrically and purity assessed initially by the absorbance ratio readings at 260/280 nm. Electrophoresis of the RNA samples was performed together with RNA molecular weight markers on a 1.5% formamide agarose gel. Five bands were identified and the band containing the polymerase genes was size selected, located and excised. Purification of the polymerase genes from the agarose was achieved by using the BIO 101 RNAid kit. The three isolated polymerase RNAs were reverse transcribed using the Boehringer Mannheim cDNA synthesis kit. The results indicate that the H1N1 influenza virus was successfully grown and isolated from chick embryos. Absence of contamination and verification of viral presence at different stages of the study were indications that asepsis was successfully achieved. The RNA obtained was sufficient and suitable for cDNA synthesis. This cDNA may now be used for further molecular analysis and subsequent DNA methylation studies. Further, transfection studies may then be performed to determine, if any, the the expression of methylated and unmethylated cDNA. / Thesis (M.Med.)-University of Natal, 1992.

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. / Thesis (M.Med.)-University of KwaZulu-Natal, 2004.

The incidence of sudden death during or after squash play has become a source of concern. In order to screen for coronary artery disease, exercise stress testing has been advocated, by the American College of Sports Medicine (1986), for those at or above the age of 45 already exercising or before embarking on exercise. Eighteen veteran squash players (mean age 49 ± 3 yr) took part in the study. Heart rate response was monitored throughout a squash match and for an hour after play. ECG changes were monitored for one hour after squash play. Mean heart rate, throughout playing time was 148 ± 16 beats per minute (range 118 - 168 bpm), representing 86.7% of Predicted Maximum Heart Rate (PMHR). Mean maximal heart rate was 169 ± 14 bpm (range 141 - 186 bpm), representing 98.8% of PMHR. Thus squash represents a very high intensity activity for these players. On subsequent ECG monitoring, no abnormalities were detected. The results of this study confirm that squash is an extremely high intensity sport and that even veteran players play at a level close to their maximal. This level of play did not provoke subsequent cardiac arrhythmias in this small group of players, contrary to an earlier study that reported arrhythmias in one third of a group of younger players in the post match period. / Thesis (M.Med.Sc.)-University of Natal, 1997.

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

Due to the lack of morphological data on prepubertal Indian male soccer players in South Africa, this study was undertaken on ninety male prepubertal subjects. The subjects were divided into three groups of thirty subjects each: Experienced "E" (those playing organized soccer for more than two years), beginners "8" (those playing organized soccer for less than two years) and sedentary "S" (those not participating in organized soccer). All subjects were measured according to Heath - Carter anthropometric somatotype methods. Fitness tests comprising power and strength tests (vertical jump height and standing broad jump) and muscle endurance tests (push - ups and sit - ups) were also done. The three groups were first compared to each other and then to available international data. There were no statistical differences among the three groups for: height, weight, age, triceps, subscapular, suprailiac, calf and total skinfolds, humerus and biceps girth, ectomorphy, mesomorphy and endomorphy, suggesting a general homogenicity between groups. For fitness tests the "E" group performed significantly better than the others for standing broad jump and sit - ups (p = 0.005 and p = 0.036 respectively). For push - ups the "8" and "E" were significantly better than the "S" group, (p = 0.013, for "8" versus "S" group), indicating that in soccer muscle strength and explosive strength are important. The lack of difference between the groups for anthropometric criteria in this study may be explained by the experienced players' inadequate training. Other factors may include the lack of parental involvement, inadequate knowledge on fitness aspects and poor training methods. Furthermore, the sedentary group may be participating in unorganized activities which renders them at a level similar to the experienced group. Data on non - Indian South African junior players is required to help us understand the lack of significant Indian talent in the National team. Other factors such as diet, cultural differences, training methods, level of coaching, environmental factors and sport facilities need investigation and be addressed if we want to see an improvement in the South African Indian soccer players. / Thesis (M.Med.Sc.)-University of Natal, Durban, 1997.