Thesis (DPhil (Biomedical Science))--Cape Peninsula University of Technology, 2019. / Diabetes mellitus (DM) is a group of metabolic disorders characterised by persistent high blood glucose levels together with abnormal metabolism of macromolecules. If the hyperglycemia is not controlled, adverse metabolic changes could occur leading to the progressive development of severe complications. Formation of reactive oxygen/nitrogen species and inflammatory responses are principal mechanisms that have been implicated in the development of hyperglycemia-induced tissue damage. The commercially available drugs utilised in the treatment of diabetes have been linked to detrimental side effects hence the need to discover alternative medicines especially from medicinal plants. Catharanthus roseus is both a medicinal and ornamental plant that is traditionally used to treat various diseases. It has been reported to possess antidiabetic, anticancer, antimicrobial and antioxidant properties. The plant has been shown to possess more than 100 monotepernoid indole alkaloids which were linked to the plants’ antihyperglycemic and antioxidant effects. Therefore, this study was carried out to investigate the effect of vindoline; a bioactive compound derived from C. roseus against type 2 diabetes–induced complications. The study also investigated the effects of Catharanthus roseus extracts in RIN-5F cell line. The study was carried out in two parts: viz in vitro and the in vivo assessments. The in vitro study initially investigated the polyphenolic content and antioxidant activities of vindoline and the 3 extracts (methanolic, aqueous and the dichloromethane) of C.roseus. The assays used to evaluate the antioxidant capacity of the extracts include oxygen radical absorbance capacity (ORAC) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) inhibitory assay. Among the evaluated extracts, the methanolic extract demonstrated both high total polyphenolic content and antioxidant capacity. The HLPC analysis of the extracts was performed and showed highest concentrations of vindoline in the dichloromethane extract and the aqueous extract exhibited the least. The antioxidant activities of vindoline were determined and compared to a known antioxidant, ascorbic acid. Vindoline revealed stronger ORAC activity than ascorbic acid however the ferric reducing antioxidant power did not show any significant differences (p < 0.05). Insulin secretion studies were performed in a β-cell insulinoma cell line- RIN-5F exposed to different concentrations of glucose (high, low and in the absence of glucose). The studies were carried out to compare the β-cell stimulatory effect of vindoline to the extracts. After performing cytotoxic experiments, concentrations that resulted in about 80% cell viability were used to determine the insulin secretory effects. In cells that exposed to glucotoxicity (50 mM glucose), vindoline showed the highest β-cell stimulatory effect (p < 0.05) when compared to the untreated controls and to the cells that were treated with the methanolic extract. In cells that were exposed to a low glucose concentration, vindoline additionally showed significant β-cell stimulatory effect at p < 0.05 when compared to the aqueous and the methanolic extracts. Thereafter, the intracellular reactive oxygen species assay (ROSA) was performed in glucotoxicity-induced cells after treatment with vindoline and the respective extracts. The results were compared to the untreated control: vindoline, methanolic and the dichloromethane extracts indicated significant reduction in ROS generation (p < 0.05). Further measurement of the release of TNF-α, a pro-inflammatory cytokine in the cells following treatment, the results were not significant among the groups at p < 0.05. The carbohydrate enzymes inhibitory activity of vindoline and extracts of C.roseus (50, 25, 12.5 and 6.125 mg/ml) were measured. The alpha glucosidase inhibitory activities of the extracts at 50 mg/ml resulted in < 30% enzyme inhibition with no significant differences among the groups at p < 0.05. At lower concentrations, the dichloromethane extract exhibited significantly lower inhibitory activities when compared to the methanolic and the aqueous extract (p < 0.05). The alpha amylase inhibitory activity of the methanolic extract was significantly increased at all concentrations; recording the highest enzyme inhibition of approximately 40% (p < 0.5). However, the dichloromethane extract did not show any enzyme inhibitory activity. The enzyme inhibitory activity of vindoline was compared to acarbose-a known standard drug, for both enzymes; vindoline did not show appreciable enzyme inhibition when compared to acarbose (p < 0.05). In vivo studies were performed in a type 2 diabetes (T2DM) rat model in which T2DM was induced in 6 weeks old male Wistar rats by having them drink 10% fructose solution ad libitum for 14 days followed by a single intraperitoneal injection of streptozotocin (STZ 40 mg/kg) in freshly prepared 0.1 M citrate buffer (pH 4.5). Animals were randomly divided into six groups (n=8) and received daily treatments for 6 weeks with the vehicle, vindoline (20 mg/kg) or glibenclamide (5 mg/kg) via oral gavage. The effects of the treatments on blood glucose, insulin, body weight, organ weight, serum biochemical parameters, oxidative status, inflammatory markers and tissue histology were assessed in diabetic and non-diabetic rats. Administration of vindoline significantly (p < 0.05) reduced the fasting blood glucose in diabetic rats by 15% and significantly increased serum insulin levels when compared to the diabetic controls. Vindoline and glibenclamide significantly (p < 0.05) reduced the levels of circulating hepatic enzymes in T2DM; the results were significant when compared to the diabetic controls. Treatment with vindoline significantly improved the hepatic antioxidant status as indicated by increased ORAC, superoxide dismutase and catalase activities, indicative of the protective effect of vindoline in diabetes-induced hepatic injury. Assessment of the levels of pro-inflammatory cytokines in the hepatic tissue indicated remarkable reduction of TNF-ɑ by (-41%) and IL-6 (-28%) in diabetic rats treated with vindoline when compared to the diabetic controls (p < 0.05). The serum lipid profile showed marked increases in the levels of serum lipids (triglycerides, low density lipoproteins, total cholesterol and very low density lipoproteins) in diabetic controls when compared to all treatment groups (p < 0.05). Therefore, vindoline and glibenclamide showed possible protective effects against diabetes-induced cardiovascular disease. Kidney function assessment revealed increased levels of urea and creatinine in the diabetic control group. Vindoline and glibenclamide significantly reduced the urea and creatinine levels in diabetic rats. Vindoline additionally improved the FRAP in diabetic hearts. The SOD activity and ORAC were increased while lipid peroxidation was reduced in the kidneys of diabetic rats treated with vindoline when compared to the diabetic control (p < 0.05). Histopathological assessment in diabetic rats showed severe damage of the liver, kidney and pancreas. Treatment of diabetic rats with vindoline restored the structure of these organs which was indicated by minimum structural changes. The expression of pro-apoptotic marker caspase 9 in response to glucose stress was significantly higher in the diabetic control group when compared to all the treatment groups. Treatment with vindoline showed remarkable reduction of caspase 9 expression in the diabetic rats. In conclusion, persistent high blood glucose levels resulted in free radical induced tissue damage in the type 2 diabetes rat model. Vindoline demonstrated protective effects against diabetes induced hepatic, cardiac, pancreatic and nephritic injuries. In addition, vindoline improved insulin secretion in both in vitro and in vivo setups hence the findings suggest that vindoline could be an important agent that can be considered in the treatment and management of diabetes and diabetic complications.

Thesis (MScMed)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: It has recently been observed that the application of multiple short cycles of reperfusion and ischaemia, at the onset of reperfusion, elicits cardioprotection against injury due to prior sustained ischaemia. This phenomenon has been termed “postconditioning” (postC) and is of special interest due to its clinical applicability. Although much work has been done to delineate the mechanism of protection, there is still controversy regarding the precise algorithm of postC, the importance of the reperfusion injury salvage kinases (RISK), as well as uncertainty about the possible role of p38 MAPK and the protein phosphatases in postC cardioprotection. The aims of this study were therefore: I. To develop and characterise a cardioprotective postC protocol in the ex vivo rat heart, using both the retrogradely perfused and working heart models. II. To characterise the profiles of PKB/Akt, ERK p42/p44 and p38 MAPK associated with the postC intervention. III. To investigate the possible role of the serine/threonine protein phosphatases type 1 and type 2A (PP1 and PP2A) in the mechanism of postC. Hearts from male Wistar rats were perfused in both the retrograde Langendorff (at a perfusion pressure of 100 cmH2O and diastolic pressure set between 1 and 10 mmHg) and working heart models (preload: 15 cmH20 and afterload: 100 cmH20). Several different postC protocols were tested for their cardioprotective effect, as analysed by infarct size (IFS; determined by triphenyltetrazolium chloride (TTC) staining) and functional recovery. Experimental parameters tested were the number of cycles (3,4 or 6), the duration of the cycles (10, 15, 20 or 30 seconds), the method of application (regional or global) and temperature during the intervention (36.5 or 37 °C). Different sustained ischaemic insults were also utilised: 35 minutes regional (RI) or 20, 25, 30 and 35 minutes global ischaemia (GI). Hearts treated with a cardioprotective postC intervention or standard reperfusion after sustained ischaemia, were freeze-clamped at 10 and 30 minutes reperfusion in both perfusion models. Tissue samples were then analyzed using Western blotting, probing for total and phosphorylated PKB/Akt, ERK p42/p44 and p38 MAPK. The contribution of PKB/Akt and ERK p42/p44 activation to cardioprotection was also investigated by administration of inhibitors (A6730 and PD098059 respectively) in the final 5 minutes of ischaemia and the first 10 minutes of reperfusion, in the presence and absence of the postC intervention. The effect of these inhibitors were analyzed in terms of IFS and kinase profiles. The possible role of the phosphatases in postC was investigated by observing the effect of cantharidin (a PP1 and PP2A inhibitor) treatment directly before sustained ischaemia (PreCanth) or in reperfusion (PostCanth), in the presence and absence of postC, on IFS and kinase profiles. A postC protocol of 6x10 seconds global reperfusion / ischaemia, at 37°C, was found to give the best and most consistent reduction in infarct size in both the Langendorff (IFS in NonPostC: 47.99±3.31% vs postC: 27.81±2.49%; p<0.0001) and working heart (IFS in NonPostC: 35.81±3.67% vs postC: 17.74±2.73%, p<0.001) models. It could however only improve functional recovery in the Langendorff model (after 30 minutes GI: rate pressure product (RPP) recovery: NonPostC = 12.27±2.63% vs postC = 24.61±2.53%, p<0.05; and after 35 minutes GI: left ventricular developed pressure (LVDP) recovery: NonPostC = 28.40±7.02% vs postC = 48.49±3.14%, p<0.05). This protection was associated with increased PKB/Akt (NonPostC: 0.88±0.26 AU (arbitrary unit) vs postC: 1.65±0.06 AU; p<0.05) and ERK p42 (NonPostC: 2.03±0.2 AU vs postC: 3.13±0.19 AU; p<0.05) phosphorylation. Inhibition of PKB/Akt activation with A6730 (2.5 μM) abrogated the infarct sparing effect of postC. Administration of cantharidin, either before of after ischaemia, in the absence of postC, conferred an infarct sparing effect (IFS in PreCanth: 15.42±1.80%, PostCanth: 21.60±2.79%; p<0.05) associated with an increase in the phosphorylation of MAPK p38 (administration before ischaemia: NonCanth: 1.52±0.26 AU vs PreCanth: 2.49±0.17 AU, p<0.05; and administration after ischaemia: NonCanth: 5.64±1.17 AU vs PostCanth: 10.69±1.29 AU, p<0.05) and ERK p42 (when administered in reperfusion; NonCanth: 2.24±0.21 AU vs PostCanth: 3.34±0.37 AU; p<0.05). Cantharidin treatment combined with the postC intervention did not elicit an additive infarct sparing effect (postC: 17.74±2.72%, PreCanth-postC: 13.30±3.46% and PostCanth-postC: 15.39±2.67%). In conclusion: a postC protocol of 6x10 seconds global ischaemia / reperfusion, at 37°C, confers the best infarct sparing effect in both the Langendorff and working rat heart models. This protection is associated with ERK p42 and PKB/Akt phosphorylation, although only PKB/Akt is necessary for cardioprotection. We could not find evidence for PP1 and PP2A involvement in postC, although inhibition of these phosphatases per se does elicit an infarct sparing effect. The latter observation suggests that phosphatase activation during ischaemia / reperfusion is potentially harmful. / AFRIKAANSE OPSOMMING: Dit is onlangs waargeneem dat toediening van meervoudige siklusse herperfusie / iskemie, met die aanvang van herperfusie, die hart teen iskemie / herperfusie beskadiging beskerm. Hierdie verskynsel, bekend as postkondisionering (postC), geniet tans baie aandag vanweë die kliniese toepaslikheid van die ingreep. Ten spyte van intensiewe navorsing om die betrokke meganisme van beskerming vas te stel, is daar steeds kontroversie oor die presiese algoritme van die ingreep, asook die betrokkenheid van die sogenaamde iskemie herperfusie oorlewings kinases (RISK). Daar bestaan ook onsekerheid oor die rol van die stres-kinase, p38 MAPK, asook die proteïen fosfatases in die meganisme van beskerming teen iskemiese besering. Hierdie studie het dus drie doelstellings gehad: I. Ontwikkeling van ‘n postC protokol wat beskerming ontlok in die rothart ex vivo, deur gebruik te maak van beide die retrograad geperfuseerde ballon model, asook die werkhart model. II. Analiese van die profiele van die kinases PKB/Akt, ERK p42/p44 en p38 MAPK tydens herperfusie van postC en kontrole (NonPostC) harte. III. Ondersoek na die moontlike rol van die serien / treonien proteïen fosfatases tipe 1 en tipe 2A (PP1 en PP2A) in die meganisme van postC beskerming. Harte van manlike Wistar rotte is geperfuseer in beide die retrograad geperfuseerde ballon (d.i. die Langendorff) model (teen ‘n konstante perfusie druk van 100 cmH20 en ‘n diastoliese druk gestel tussen 1 en 10 mmHg), asook die werkhart model (teen ‘n voorbelading van 15 cmH20 en ‘n nabelading van 100 cmH20). Verskeie moontlike postC protokolle is getoets vir hul vermoë om kardiobeskerming te ontlok, in terme van funksionele herstel en infarktgrootte (IFS), soos bepaal deur trifenieltetrazolium chloried (TTC) kleuring. Die eksperimentele veranderlikes tydens die postC protokol wat ondersoek is, sluit in: die aantal siklusse (3, 4 of 6), die duur van die siklusse (10, 15, 20 of 30 sekondes), die wyse van postC toediening (streeks of globaal) en laastens die temperatuur tydens die ingreep (36.5 of 37 °C). Daar is ook gebruik gemaak van verskillende periodes iskemie: 35 minute streeks iskemie (RI), asook 20, 25, 30 en 35 minute globale iskemie (GI). Na 10 of 30 minute herperfusie is harte wat blootgestel is aan ‘n kardiobeskermende postC ingreep of gewone standaard herperfusie na iskemie, in beide perfusie modelle, gevriesklamp. Die weefsel proteïen-inhoud is verder geanaliseer deur van die Western blot tegniek gebruik te maak vir bepaling van die totale en fosforileerde vlakke van PKB/Akt, ERK p42/p44 en p38 MAPK. Die funksionele belang van PKB/Akt en ERK p42/p44 is verder ondersoek deur die effek van ‘n geskikte inhibitor (onderskeidelik A6730 en PD098059, toegedien tydens die laaste 5 minute van iskemie en die eerste 10 minute van herperfusie), in die teenwoordigheid en afwesigheid van die postC ingreep, op infarktgrootte en kinase aktiwiteit te monitor. Die moontlike rol van proteïen fosfatases in postC is ondersoek deur die effek van cantharidin (‘n PP1 en PP2A inhibitor) op infarktgrootte en kinase profiele te ondersoek. Cantharidin is óf onmiddelik voor iskemie óf tydens herperfusie toegedien, in die aan – en afwesigheid van die postC ingreep. Daar is bevind dat ‘n postC protokol van 6x10 sekondes globale iskemie / herperfusie, teen 37°C, die mees effektiewe en konstante verlaging in infarktgrootte teweeg gebring het in beide die ballon model (IFS in NonPostC: 47.99±3.31% vs postC: 27.81±2.49%; p<0.0001), asook die werkhart (IFS in NonPostC: 35.81±3.67% vs postC: 17.74±2.73%, p<0.001). Funksionele herstel kon egter slegs ontlok word in die ballon model (na 30 minute GI: tempo druk produk (RPP) herstel: NonPostC = 12.27±2.63% vs postC = 24.61±2.53%, p<0.05; en na 35 minute GI: linker ventrikulêre ontwikkelde druk (LVDP) herstel: NonPostC = 28.40±7.02% vs postC = 48.49±3.14%, p<0.05). Die infarkt-besparende effek van postC was geassosieer met ‘n toename in die fosforilasie van beide PKB/Akt (NonPostC: 0.88±0.26 AU (arbitrêre eenhede) vs postC: 1.65±0.06 AU; p<0.05) en ERK p42 (NonPostC: 2.03±0.2 AU vs postC: 3.13±0.19 AU; p<0.05). Inhibisie van PKB/Akt met A6730 (2.5 μM) het die infarkt-besparende effek van postC opgehef. Inhibisie van PP1 en PP2A opsigself, deur toediening van cantharidin óf voor óf na iskemie (in die afwesigheid van postC), het ‘n infarkt-besparende effek ontlok (IFS in PreCanth: 15.42±1.80%, PostCanth: 21.60±2.79%; p<0.05). Hierdie kardiobeskerming was geassosieer met ‘n toename in die fosforilasie van beide p38 MAPK (met toediening voor iskemie: NonCanth: 1.52±0.26 AU vs PreCanth: 2.49±0.17 AU, p<0.05; en toediening na iskemie: NonCanth: 5.64±1.17 AU vs PostCanth: 10.69±1.29 AU, p<0.05), asook ERK p42, indien cantharidin toegedien is tydens herperfusie (NonCanth: 2.24±0.21 AU vs PostCanth: 3.34±0.37 AU; p<0.05). Kombinasie van cantharidin behandeling met postC toediening kon egter nie ‘n kumulatiewe infarkt-besparende effek uitlok nie (postC: 17.74±2.72%, PreCanth-postC: 13.30±3.46% en PostCanth-postC: 15.39±2.67%). In samevatting: ‘n PostC protokol van 6x10 sekondes globale iskemie / herperfusie, teen 37°C, ontlok die mees effektiewe infarkt-besparende effek in beide die ballon, sowel as die werkhart modelle. Alhoewel hierdie beskerming geassosieer is met ‘n toename in die fosforilasie van beide PKB/Akt en ERK p42/p44 tydens herperfusie, is dit slegs PKB/Akt wat van funksionele belang is in die meganisme van kardiobeskerming. Ons kon geen bewyse vind vir die betrokkenheid van PP1 en PP2A in postC beskerming nie, alhoewel inhibisie van hierdie fosfatases opsigself infarkt-besparend is. Laasgenoemde waarneming toon dat fosfatase aktivering tydens iskemie / herperfusie skadelike gevolge mag hê.

Thesis (MScMedSc (Biomedical Sciences. Medical Physiology))--University of Stellenbosch, 2006. / Introduction: Obesity, which is implicated in the development of the metabolic syndrome (MS) is reaching epidemic proportions worldwide. MS significantly increases the risk of developing cardiovascular disease, which includes coronary artery disease. The current absence of animal models of diet induced obesity and the MS makes the investigation of the cardiovascular consequences of MS virtually impossible. As a result the effects of the MS on cardiac function, morphology and susceptibility to ischaemia are not well understood. Aims: We set out to: 1) develop and characterize a rodent model of dietinduced obesity and the MS, 2) investigate the susceptibility of hearts from these animals to ischaemia/reperfusion induced injury and, 3) determine whether angiotensin II (Ang II) and endothelin-1 (ET-1) plays a role in cardiac remodelling and/or the severity of ischaemia and reperfusion injury in this model. Methods: Male Wistar rats were fed a standard rat chow diet or cafeteria diet (CD) for 16 weeks. After the feeding period rats were sacrificed and blood and myocardial tissue samples were collected to document biochemical changes in these animals. Hearts were perfused on the isolated working rat heart perfusion apparatus to assess myocardial mechanical function before and after ischaemia. In a separate series of experiments, hearts underwent coronary artery ligation to determine the incidence and duration of ventricular arrhythmias during ischaemia and reperfusion, using electrocardiography. To assess a possible link between myocardial remodelling and ischaemia/reperfusion injury and myocardial Ang II and ET-1 content, we also measured these peptides under basal conditions and during ischaemia. Two-dimensional targeted Mmode echocardiography was used to assess in vivo myocardial mechanical function in control and obese rats. Results: After 16 weeks on the CD, obese rats satisfied the World Health Organization (WHO) criteria for the MS by having visceral obesity, insulin resistance, dyslipidaemia and an elevated systolic blood pressure, compared to control rats. Circulating Ang II levels, but not ET-1 levels, were elevated in CD fed rats. Obese rats had cardiac hypertrophy and ex vivo basal myocardial mechanical function was depressed in the CD fed rat hearts compared to control rat hearts. CD fed rat hearts had poorer aortic output (AO) recoveries compared to hearts from control rats. These hearts also had a higher incidence and duration of reperfusion arrhythmias. No such functional differences were seen in the in vivo experiments. No differences in basal or ischaemic myocardial Ang II and ET-1 levels were seen in either group. Conclusion: We have developed and characterized a model of diet-induced obesity and the MS. Obesity is associated with cardiac hypertrophy and an increased myocardial susceptibility to ischaemia and reperfusion injury in our model. The hearts from obese rats were also more prone to reperfusion ventricular arrhythmias. As myocardial function was only poorer in the ex vivo obese animal experiments, our data suggests that the obesity associated changes in function observed in the ex vivo studies may be related to the absence of circulating substrates or factors, which are essential for their normal mechanical function.

Thesis (MScMedSc)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: INTRODUCTION: Obesity and its associated complications such as diabetes and cardiovascular disease are escalating worldwide. Cardiovascular mortality and the occurrence of heart failure following a myocardial infarction are increased among diabetics. A high caloric diet has been associated with specific metabolic alterations such as increased FA utilization and decreased glucose utilization. We therefore hypothesized that, in a rat model of diet-induced obesity, pathways involved in myocardial glucose utilization would be down regulated with simultaneous up regulation of FA utilization pathways and that this will lead to certain metabolic adaptations which will eventually become maladaptive. We aimed to elucidate mitochondrial oxidative capacity, biogenesis, and signaling pathways involved in substrate utilization and energy production in rats on the obesity inducing diet for a period of 8 or 16 weeks. METHODS: The diet of male Wistar rats (180-200 g) was supplemented with sucrose and condensed milk for 8 or 16 weeks (DIO) and compared to age-matched controls. We determined the fasting blood glucose and serum insulin levels, which was used to calculate the HOMA index. Furthermore, (i) A set of hearts were removed and freeze-clamped immediately. (ii) Isolated hearts were perfused with Krebs-Henseleit buffer (10 mM glucose), subjected to regional ischaemia by ligating the left anterior descending artery (35 min). After 10 min reperfusion, the infarcted and non-infarcted zones were freeze-clamped separately. Isolated mitochondria prepared from fresh tissue were used to measure oxidative capacity using either glutamate or palmitoyl-L-carnitine as substrates and exposed to anoxia (20 min) /reperfusion and used in e- transport chain complex analysis. Additionally we determined (i) ATP production (HPLC), (ii) citrate synthase activity and quantity as measure of active mitochondria per mg of protein and (iii) PDH complex expression and activity (ELISA). Levels of GLUT1, GLUT 4, PGC-1α, PPARα, PKB/Akt, GSK-3, PTEN, AMPK and PI3K activity were measured via Western blotting and Real-time PCR was used to measure the expression of PDK 4 and FAT/CD36. RESULTS: The blood glucose and serum insulin levels were significantly elevated in the diet group after 8 weeks of DIO. The PPARα, PGC-1α and PDK 4 levels were also significantly elevated in the diet group with no significant difference in the levels of any of the other proteins measured or the level of citrate synthase activity. After 16 weeks of DIO the citrate synthase, PTEN and p-PI3K activity was significantly reduced and the %recovery after anoxia/reperfusion when using palmitoyl was significantly increased in the diet group. There was no change in mitochondrial oxidative function in both groups after 8 and 16 weeks, as well as no difference in ATP production during state 3 respiration. CONCLUSION: The increased blood glucose and serum insulin levels as well as the increase in the HOMA index in the diet group after 8 weeks of DIO indicates that these obese animals were insulin resistant. An increase in the level of PPARα and PGC-1α expression indicates an early compensatory effect which facilitates enhanced fatty acid utilization. This is underscored by elevated levels of PDK 4. We could find no significant difference in the quantity of the PDH enzyme but there was a significant increase in the level of PDH activity in the diet group after 16 weeks of DIO. Mitochondria from the 16 weeks DIO animals were able to withstand anoxia/reperfusion and showed no malfunctioning of the electron transport chain, despite a reduction in PI3K & PTEN activity and the presence of insulin resistance. Mitochondrial biogenesis does not seem to play a significant role in the heart‟s adaptive response as there was no increase in the citrate synthase activity in both groups. We conclude that the hearts from these obese and insulin resistant rats are coping well and have adapted metabolically to compensate for any reduction in glucose oxidation. It is plausible that this initial metabolic adaptation may become maladaptive as obesity progresses. / AFRIKAANSE OPSOMMING: INLEIDING: Vetsug en die geassosieerde komplikasies, naamlik diabetes en kardiovaskulêre siektes is besig om wêreldwyd toe te neem. Kardiovaskulêre sterftes en die voorkoms van hartversaking ná 'n miokardiale infarksie is verhoog onder diabete. 'n Dieet met 'n hoë vetinname word ook geassosieer met spesifieke metabolise veranderings, soos verhoogde vetsuur gebruik en 'n afname in glukoseverbruik. Ons het dus vermoed dat seintransduksie paaie betrokke by miokardiale glukose verbruik afgereguleer sal wees met tesame opreguleering van seintransduksie paaie betrokke by vetsuur verbruik, en dat dit sal lei tot sekere metaboliese aanpassings wat uiteindelik wanaanpaslik sal word. Ons DOESTELLING in hierdie studie was dus om meer lig te werp op mitokondriale oksidatiewe kapasiteit, biogenese, en seintransduksie betrokke by substraatverbruik en energieproduksie in rotte op die vetsugveroorsakende-dieet (vir 'n tydperk van 8 tot 16 weke). METODE: Die dieet van die manlike Wistar rotte (180-200 g) is aangevul met sucrose en gekondenseerde melk vir 8 of 16 weke (DIO) en is dan vergelyk met kontrole rotte van dieselfde ouderdom. Die vastende bloedglukose-en insulienvlakke is bepaal en hierdie waardes is gebruik om die HOMA indeks te bereken. Verder is, (i) 'n stel harte verwyder en onmiddelik gevriesklamp (ii) geïsoleerde harte met Krebs-Henseleit buffer (10 mM glukose) geperfuseer en dan aan 35 min streeksiskemie en 10 min herperfusie blottgestel. Na 10 min herperfusie, is die infarct en nie-infarktsones apart gevriesklamp. Geïsoleerde mitokonderieë is voorberei van vars weefsel en is gebruik a) om oksidatiewe kapasiteit te meet met behulp van glutamaat of palmitoiel-L-karnitien as substrate of b) blootgestel aan 20 min anoksie gevolg deur heroksigenasie of c) is gebruik in elektronvervoerkettingkompleks analise. Verder is die volgende ook bepaal: (i) ATP-produksie (HPLC), (ii) sitraat sintase aktiwiteit en hoeveelheid, gemeet as maatstaf van die aktiewe mitkondrieë per mg van proteïen en (iii) PDH-komplekuitdrukking en aktiwiteit (ELISA). Vlakke van GLUT 1, GLUT 4, PGC-1 alpha, PPAR alpha, PKB/Akt, GSK-3, PTEN, AMPK, en PI 3 kinase is bepaal deur Western klad analise en “Real –time PCR” is gebruik om die uitdrukking van PDK 4 en FAT/CD 36 te bepaal. RESULTATE: Die bloedglukose- en serum insulinvlakke was beduidend verhoog in die dieetgroep na 8 weke van DIO. Die PPAR alpha, PGC-1 alpha en PDK 4 vlakke was ook beduidend verhoog in die dieetgroep met geen beduidende verskil in die vlakke van enige van die ander proteïene gemeet of die vlakke van sitraat-sintase aktiwiteit nie. Na 16 weke van DIO het die vlakke van sitraat-sintase, PTEN en p-PI 3 kinase beduidend verlaag en die % herstel na anoksie/heroksigenering (met die gebruik van palmitoiel-L-karnitien) het beduidend toegeneem in die dieetgroep. Geen ander mitokondriale veranderinge kon waargeneem word nie. Ons kon geen verandering vind in die mitokondriale oksidatiewe funksie tussen die twee groepe na 8 en 16 weke van DIO. Daar was ook geen verandering in die hoeveelheid ATP geproduseer gedurende staat 3 respirasie. GEVOLGTREKKING: Die verhoogde bloedglukose en serum insulienvlakke, sowel as die toename in die HOMA indeks in die dieetgroep na 8 weke van DIO, dui daarop dat hierdie oorgewig diere insulienweerstandig is. 'n Toename in die vlak van PPAR alpha en PGC-1 alpha uitdrukking dui op 'n vroeë kompenserende effek, wat die verhoogde verbruik van vetsure fasiliteer. Dit is beklemtoon deur verhoogde vlakke van PDK 4. Ons kon geen beduidende verskil in die hoeveelheid PDH-ensiem vind nie, maar daar was wel 'n beduidende toename in die vlak van PDH aktiwiteit in die dieetgroep na 16 weke van DIO. Mitokondrieë van die 16 weke DIO diere kon anoksie/heroksigenering weestaan en het geen wanfunksionering van die elektronvervoerketting getoon nie, ten spyte van 'n vermindering in PI 3 kinase en PTEN aktiwiteit en die teenwoordigheid van insulienweerstandigheid. Mitokondriale biogenese blyk nie 'n beduidende rol te speel in die hart se aanpassingreaksie nie, want daar was geen verhoging in die sitraat-sintase aktiwiteit in beide groepe nie. Na aanluiding van die resultate verkry met hierdie studie, maak ons ook die gevolgtrekking dat die harte van rotte na 16 weke se blootstelling aan 'n hoë vet omgewing, metabolies kon aanpas en goed funksioneer. Ons gevolgtrekking is dus dat die harte van diere wat lei aan vetsug en wat insulien weerstandig is die verlaaging in glukose metabolisme goed hanteer en metabolies aangepas het hierby. Dit is moontlik dat hierdie aanvanklike aanpasing wanaanpaslik kan word soos vetsug vorder.

Thesis (PhD(FoodSc))--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Potential beneficial and/or adverse modulatory effects of polyphenol-enriched extracts of rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.) on the antioxidant homeostasis in the liver were investigated. Phase II metabolism of aspalathin and mangiferin, the major polyphenols of rooibos and honeybush respectively, was assessed for potential glucuronidation and sulphation. Glucuronidation resulted in a loss of antioxidant activity for aspalathin and mangiferin in post-column HPLC-DAD-DPPH• and HPLC-DAD-ABTS•+ assays and also a decreased activity of iron chelating properties of mangiferin in the FRAP assay. Two independent studies for 28 and 90 days with polyphenol-enriched extracts (PEEs) of unfermented rooibos [Aspalathus linearis (PER)] and honeybush [Cyclopia. subternata (PECsub) and C. genistoides (PECgen)] in male Fischer rats were conducted to assess possible beneficial and/or adverse biological effects. PECgen was only included in the 28 day study. PEEs were characterised by in vitro antioxidant assays and HPLC analysis. The importance of detailed chemical characterization of rooibos and honeybush when investigating biological effects in vivo is clear as distinctive biological effects and major differences in compositions were evident. Biological parameters included were serum chemical parameters, activities of selected antioxidant enzymes, levels of glutathione and the modulation of expression of oxidative stress and antioxidant defense related genes in the liver. Sub-chronic (90 days) exposure of rats to PER and PECsub both adversely affected iron absorption significantly (P<0.05) and significantly (P<0.05) and markedly lowered levels of reduced glutathione (GSH) in the liver. The high levels of polyphenol intake were implicated and interaction with glutathione was postulated to occur via catechol o-quinone conjugations with GSH. This was also implicated in the significantly (P<0.05) increased activity of glutathione reductase (GR) following 28 days. These findings suggest that PEEs from rooibos and honeybush have the potential to alter the glutathione homeostasis, which could contribute to oxidative status in the liver. PECsub resulted in alterations in the liver biliary system which was manifested as significantly (P<0.05) increased serum total bilirubin (Tbili) and alkaline phosphatase (ALP), depending on the age of the rats, level of total polyphenols and duration of exposure. The expression of a number of oxidative stress and antioxidant defense related genes were differentially altered by the PEEs of rooibos and honeybush in rat liver and further indicated potential oxidative stress. Modulatory effects of PEEs on expression of 84 of these genes in rat liver were assessed with a quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) array and provided additional insights into the possible adverse and protective effects of rooibos and honeybush. Further investigation on total polyphenol dose levels and time of exposure in the application of PEEs of rooibos and honeybush as dietary supplements and functional foods is recommended and will also be of value in anticipated regulatory requirements for future substantiation of safety and efficacy. / AFRIKAANSE OPSOMMING: Die moontlike voordelige en/of nadelige modulerende effekte van polifenol-verrykde ekstrakte van rooibos (Aspalathus linearis) en heuningbos (Cyclopia spp.) op die antioksidant homeostasis in die lewer is ondersoek. Die fase II metaboliete van aspalatien en mangiferin, die hoof verbindings in rooibos en heuningbos onderskeidelik, is ondersoek t.o.v. glukuronidering en sulfonering. Glukuronidasie het gelei tot n verlies in antioksidant aktiwiteit van aspalatien en mangiferin soos bepaal in post-kolom HPLC-DAD-DPPH• en HPLC-DADABTS•+ toetse, asook verminderde interaksie met yster van mangiferin in die FRAP toets. Twee onafhanklike studies van 28 en 90 dae is onderneem met polifenol-verrykde ekstrakte (PVEs) van ongefermenteerde rooibos [Aspalathus linearis (PVR)] en heuningbos [Cyclopia. subternata (PVCsub) and C. genistoides (PVCgen)] in manlike Fisher rotte om die moontlike voordelige en/of nadelige biologiese effekte te ondersoek. PECgen was slegs in die 28 dae studie ingesluit. PVEs is gekarrakteriseer deur in vitro antioksidant en HPLC analises. Die belang van chemiese karaktirisering van rooibos en heuningbos tydens ondersoeke na biologiese aktiwiteit is duidelik aangesien verskeie en variërende biologiese aktiwiteite en verskille in die komposisie in die huidige studie gesien is. Die biologiese parameters wat ondersoek is om die effek van die PVEs te bepaal het serum kliniese parameters, aktiwiteit van geselekteerde ensieme, glutatioon en evaluering van die ekspressie van oksidatiewe en antioksidant verwante gene in die lewer, ingesluit. Sub-kroniese (90 dae) blootstelling van rotte aan PVR en PVCgen het yster absorpsie negatief beïnvloed. Die beduidende (P<0.05) verlaagde vlak van gereduseerde glutatioon in die lewer was toegeskryf aan die hoë vlakke van polifenole ingeneem tydens die studie en word moontlik veroorsaak deur n spesifieke katekol o-konjugasie van GSH. Hierdie interaksie was ook moontlik die oorsaak van n beduidende (P<0.05) toename in die aktiwiteit van glutatioon reduktase. Dié bevindinge het moontlike implikasies t.o.v die glutatioon homeostase en is n moontlike indikase dat PVEs van rooibos kan bydra tot oksidatiewe stres. PVCsub het veranderinge in die lewer gal-sisteem tot gevolg gehad aangesien daar n beduidende (P<0.05) verhoging in die serum totale bilirubin en alkalien fosfaat was. Hierdie veranderinge is beïnvloed deur die ouderdom, vlakke van die totale polifenole en die periode van blootstelling. Die uitdrukking van oksidatiewe en antioksidant verwante gene is op verskillende maniere beïnvloed deur die PVEs van rooibos en heuningbos in rot lewer and dien as n verdere indikasie van onderliggende oksidatiewe stres. Die modulerende effekte van PVEs op geenuitdrukking het gelei tot additionele insig aangaande die moontlike skadelike of beskermende eienskappe van PVEs vir gebruik as kruie produkte of dieet aanvullings. Die indikasies van moontlike oksidatiewe stres was duidelik van biologiese parameters en modulering van geenuitdrukking in die lewer, en vereis verdere ondersoek na die polifenool dosis en periode van toediening voordat PVEs van rooibos en heuningbos as funksionele voedsel produkte gebruik word. Hierdie ondersoek sowel as toekomstige ondersoeke in hierdie verband sal van waarde wees vir regulatoriese vereistes omtrent die veiligheid en effektiwiteit van rooibos en heuningbos kruie produkte.

Thesis (PhD (Biomedical Sciences. Medical Physiology))--University of Stellenbosch, 2006. / Early life trauma leads to behavioural abnormalities later in life. These include mood and anxiety disorders such as depression and posttraumatic stress disorder (PTSD). This association may be due in part to the effects of trauma on brain development. Data from basic and clinical experiments suggest that alterations in the hippocampus may be fundamental to the development of these disorders. Here we used an animal model of early life trauma to investigate its effects on the behaviour and neurochemistry of the adult rat. Adolescent rats were subjected to time-dependent sensitization stress consisting of a triple stressor (2 hours restraint, 20 min swim stress and exposure to ether vapour) on post-natal day (PND) 28, a single re-stress on PND 35 (20 min swim stress), and a second re-stress in adulthood (PND 60, 20 min swim stress). The rationale was that the frequency of exposure to situational reminders contributes to the maintenance over time of fear-related behavioural disturbances. The effects of trauma on the hypothalamus-pituitary-adrenal-axis, hippocampal and plasma neurotrophin levels, behaviour and phosphoinositide-3 kinase (PI-3 kinase) signaling proteins were initially investigated. In addition, proteomic technologies such as protein arrays and 2D-SDS PAGE combined with liquid chromatography tandem mass spectrometry (LC-MS/MS) were employed to study trauma-induced effects on the hippocampus. Traumatized animals showed a decrease in glucocorticoid receptors in the dentate gyrus of the hippocampus and an increase in basal corticosterone levels 24 hours after adulthood re-stress. These effects were reversed by pretreatment with the serotonin selective reuptake inhibitor, escitalopram. A decrease in the neurotrophins, BDNF and NT-3 were evident 8 days, but not 24 hours after adulthood re-stress. This decrease was not accompanied by decreases in plasma neurotrophin or PI-3 kinase, protein kinase B (PKB), phosphatase and tensin homologue (PTEN), phospho-forkhead and phospho-AFX protein levels. In addition, traumatized animals showed increased rearing in both the elevated plus maze and open field. Proteomic analysis of trauma-induced changes in the hippocampus show increases in Ca2+ homeostasis / signaling proteins such as S-100B, phospho-JNK and calcineurin. Apoptotic initiator proteins, including caspase 9, -10 and -12 were increased and there was evidence of cytoskeletal protein dysregulation. Furthermore, cell cycle regulators and energy metabolism proteins were decreased. These effects indicate to a cellular state of cell cycle arrest after increased calcium influx to avoid apoptosis. Our data suggest that adolescent trauma with adulthood re-stress may affect numerous systems at different levels. These include neuroendocrine-, protein systems and behaviour, and confirmed that a systems biology approach is needed for a better understanding of the neurobiology of mental disorders.

Tao Kin Pong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 144-152). / Abstracts in English and Chinese. / Chapter i. --- Cover page --- p.1 / Chapter ii. --- Table of contents --- p.2 / Chapter iii. --- Abstract of thesis (English version and Chinese Version) --- p.4 / Chapter iv. --- Acknowledgements --- p.8 / Chapter v. --- Abbreviations --- p.9 / Chapter 1. --- Introduction / Interstitial tissue and Leydig cells --- p.11 / Seminiferous tubules --- p.11 / "Male germ cell line and spermatogenesis (Mitotic, Meiotic and Post-meiotic)" --- p.12 / Sertoli cells --- p.14 / Specialized organizations of junction present in testis --- p.15 / Dynamic nature of Sertoli-Sertoli & Sertoli-germ cell junctions --- p.16 / Role of proteases and protease inhibitors in male gametogenesis --- p.17 / Proteases and Proteases Inhibitors expressed in testis --- p.18 / Hormonal control of spermatogenesis --- p.19 / Hypothyroidism and testis development --- p.21 / Genes to be studied: / Proteases --- p.22 / Proteases Inhibitors --- p.27 / Other spermatogenesis related genes --- p.30 / Chapter 2. --- Objectives --- p.32 / Chapter 3. --- Materials and Methods / Animal treatments and tissue collection --- p.33 / RNA preparation --- p.34 / RT-PCRs --- p.35 / Real-time PCRs --- p.35 / Data manipulations and Statistics --- p.36 / Primer sequences used in this experiment --- p.37 / Chapter 4. --- Results / "Effect of neonatal hypothyroidism on developmental profile of body weight, absolute and relative testicular weight" --- p.40 / Developmental transcription profiles of genes under normal and hypothyroidism --- p.43 / Screening Data --- p.78 / Expression of non-spermatogenic genes at neonatal age --- p.88 / Responsiveness of gene transcription after thyroxin replacement --- p.89 / Changes of gene expression under different hypothyroid regimens --- p.97 / Chapter 5. --- Discussion / Changes in testicular size under hypothyroidism --- p.107 / Five patterns of transcription profile --- p.107 / "Suggestion on the role of ""MEIOTIC"" proteases and inhibitors" --- p.111 / "Suggestion on the role of ""POST-MEIOTIC"" proteases and inhibitors" --- p.113 / "Explanations on ""SOMATIC"" genes" --- p.114 / "Explanations on ""MITOTIC"" genes" --- p.115 / Explanations on the un-clustered pattern --- p.116 / Explanations on the age down-regulated group --- p.116 / Proposed clustering of genes according to their transcription profile --- p.117 / "Expression of some ""non-spermatogenic"" genes before puberty" --- p.123 / Neonatal hypothyroidism as a model for studying reproductive physiology --- p.125 / Different components of spermatogenesis --- p.127 / Chapter I. --- Roles of nuclear and chromatin related genes in assisting meiosis --- p.128 / Chapter II. --- Roles of specific transcription regulators in assisting gene selection --- p.129 / Chapter III. --- Role of signal transduction molecules for translation and activation --- p.131 / Chapter IV. --- Role of proteases and inhibitors for matrix and junctions dynamics --- p.132 / The somatic proteases and inhibitors system in the testis --- p.133 / Spermatogenic proteases and inhibitors system --- p.134 / Chapter V. --- Role of matrix and junctional molecules in intercellular interactions --- p.137 / Chapter VI. --- Role of cytoplasmic motors in cellular movement --- p.139 / Chapter 6. --- Conclusion / Proposed story of spermatogenesis - involvement of proteases and inhibitors --- p.140 / Future Direction --- p.141 / Chapter 7. --- References --- p.144

Further studies of Stk31 in spermatogenesis in vivo would allow the identification of the asymmetry machinery of GSCs and the signaling mechanism underlying cell fate determination. Further studies of STK31 in cancer stem cells would allow the development of new diagnostic and therapeutic approaches. / In the first part of the experiment, the expression and cellular localization of STK31 were investigated. RT-PCR results showed that STK31 was reactivated in 47 -- 86% of multiple cancers. Immunofluorescent study and GFP tagging experiment showed that STK31 was localized in the cytoplasm and formed aggregated granules that divide asymmetrically during mitosis. Further study by co-staining with E-cadherin demonstrated that the mouse homolog, Stk31, was expressed in the transition state between undifferentiated and differentiated spermatogonia. These data suggest the possible involvement of STK31 in mouse spermatogonia and cancer development. / In the second part of the experiment, the function of Stk31 in mouse spermatogonia was investigated- A GSC culture on an STO feeder layer was established. Studies on growing properties, expression of molecular markers and germ cell transplantation showed that GSC culture maintained spermatogonial stem cell activity. Retinoic acid was then used to induce differentiation of GSC. The differentiation status was confirmed by monitoring the expression of molecular markers. RT-PCR and immunofluorescent study showed that the expression of Stk31 was induced in RA-induced differentiation and Stk31 proteins were asymmetrically distributed during GSC division. Overexpression of Stk31 in GSCs using retroviral transduction induced the differentiation phenotypes. These data indicate the involvement of Stk31 in mouse spermatogonia cell fate determination. / In the third part of the experiment, the function of STK31 in human colon cancer was investigated. A stable STK31 knock-down Caco2 cells were established by stably transfecting two miR RNAi designs with different efficiency into Caco2 cells. Flow cytometry analysis showed that knock-down of STK31 resulted in G1 phase arrest. Cell counts and MTS assays suggested that knock-down of STK31 decreased cell proliferation in confluent cultures. Knock-down of STK31 also enhanced cell attachment to several ECM proteins and decreases cell migration as suggested by attachment assays and migration assays. Moreover, knock-down of STK31 enhanced enterocytic differentiation and inhibited tumorigenicity both in vitro and in vivo as indicated by colony formation assays and xenograft assays. Date obtained from whole genome microarray studies indicate that STK31 regulates these "stemness" properties through altering the expression of key players in various pathways including KIT, SMAD1 and Cyclin D2. These results suggest the involvement of STK31 in colon cancer as a regulator of "sternness". / Spermatogenesis is a complicated process involving mitosis, meiosis and post-meiotic differentiation. Due to the lack of in vitro models, genes that are involved in mammalian spermatogenesis are largely unknown. Spermatogenesis and tumorigenesis share important biological similarities. This co-relation can be signified by a special group of genes called cancer/testis (CT) antigens, which are only expressed in the testes and cancer. Although cancer biology has been extensively studied for decades, promising therapeutic methods are not available for every type of cancer. Recent discovery of cancer stem cells and functional genomics studies have shed light on the development of new diagnostic and therapeutic approaches. This thesis describes the expression, cellular localization and function of a novel CT gene, STK31, in spermatogonia and cancer development. / Fok, Kin Lam Ellis. / "December 2009." / Adviser: H.C. Chan. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 143-169). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Attention-deficit hyperactivity disorder (ADHD) is a common neuropsychiatric disorder with onset at preschool age Approximately 5-10% of school-aged children worldwide have ADHD. Psychostimulants are the most common treatments for ADHD, although the precise etiology and pathological mechanisms underlying ADHD are poorly understood. Animal models could help to elucidate and further the understanding of this disorder. Among the major rodent models of ADHD of the genetic and neurotoxin-exposed animal models, the spontaneously hypertensive rats (SHR) are more extensively studied. Nevertheless, the mechanism of ADHD is complex and the evidence of SHR model for ADHD has been conflicting. Objective. In this work, we combined behavioral, neurochemical, neuroimaging, pharmacological and molecular studies to examine SHR as an animal model of ADHD. At the same time, the results of our studies could help us to explore the potential mechanism of ADHD. Material and methods. We compared the locomotor activity, attention, inhibition, learning and memory of juvenile male SHR with those of age- and gender-matched genetic control Wistar-Kyoto rats (WKY) by using the open field test, Morris water maze and prepulse inhibition test. We employed magnetic resonance imaging (MRI) to measure potential morphological differences between different brain areas of SHR and WKY, and the functional MRI (fMRI) for functional differences in these brain areas. We also measured dopamine concentration and dopamine related genes expression in the different dopamine pathways by using enzyme-linked immunosorbent assay (ELISA) to measure the dopamine concentration and by using real time PCR to assay genes expression. We examined SHR responses to D-amphetamine (D-AMP), which is psychostimulant. These included locomotor activity and inhibition ability during D-AMP treatment, expression of dopamine related genes after D-AMP treatment measured by real time PCR and c-fos protein after repeated treatment of D-AMP by the Western Blotting. Results . Hyperactivity, impulsivity and attention deficit were observed in SHR. Decreased brain volume in caudate-putamen and vermis cerebelli in SHR were demarcated using MRI. Functional MRI (fMRI) and altered c-fos expression indicated plasticity changes of the prefrontal cortex (PFC) in SHR. Dopamine content was found to decrease in mesocortical and mesolimbic dopamine pathways, but increased in the striatum. Dopamine D4 receptors gene and protein expression were decreased in the PFC in SHR. We also found that the expression of the synaptosomal-associated protein 25 (SNAP-25) gene was initially lower in the PFC but higher in the striatum in SHR. However, this disparity of SNAP-25 in the PFC vanished after repeated treatment of D-AMP between SHR and WKY. Conclusions. In the present study, we demonstrated that SHR could be established as an ADHD model by completing complex assessments of face validity, construct validity and prediction validity. We suggested that the "synaptogenesis hypotheses" might contribute to the abnormal release of dopamine and dysfunction of PFC and the striatum in SEER. In conclusion, our results have provided further new information relevant to the understanding of ADHD in human via the analysis of the SHR model. / Li, Qi. / Adviser: David Yen. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1375. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 108-125). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / School code: 1307.

Early cortical injury has been attributed to the consequential effects of various factors, such as alcohol, drug addiction, smoking, and inadequate nutrient intakes during periods of pregnancy and lactation, or delivery of infants by forceps, and premature deliveries. These are only a few examples of circumstances, or "injury", that may result in disorders ranging from mild learning difficulties to aggressive behaviour. Injury to the cortex during the early years of development has been know to result in poor behavioural outcome into adulthood. Presently, the most common form of treatment includes a pharmacological agent, which may be accompanied with behavioral modification therapies supported by families. As an alternative form of therapy towards the treatment of early cortical injury, choline and a vitamin and mineral supplement (EM Power+) were used to determine the possibilities of nutrition intervention in an animal model. The injuries were incurred by aspiration lesion at days three, (Exp.1) and four, (Exp.2) and lesions were localized to the midline medial frontal cortex in some rats, while a different group of rats received lesions in the posterior parietal cortex. The pre-and postnatal choline treated animals showed favorable results for the medial frontal lesions, and the postnatal vitamin supplement treated animals showed favorable results for treatment in both medial frontal and posterior parietal lesions. All animals were tested in adulthood indicating that nutrition intervention is very beneficial for alleviating some of the functional deficits commonly seen from early cortical injury. / xiv, 191 leaves : ill. ; 28 cm.