Electronic Theses and Dissertations (PhDs)
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Item Comparison of the proteome of Huh7 cells transfected with different (sub)genotypes of Hepatitis B Virus prevailing in sub-Saharan Africa(University of the Witwatersrand, Johannesburg, 2024) Padarath, Kiyasha; Kramvis, AnnaHepatitis B Virus (HBV) is classified into nine genotypes, A to I, and at least 35 subgenotypes. In sub-Saharan Africa (SSA), (sub)genotypes A1, D3, and E prevail. Different mutations in the basic core promoter (BCP) and/or precore (PC) region that affect the expression of HBeAg can affect clinical outcomes and progression to hepatocellular carcinoma (HCC). Subgenotype A1, has high oncogenic potential and mutations affecting HBeAg expression at transcriptional, translation and post-translation levels, resulting in early HBeAg seroconversion. G1862T mutation, frequently found in subgenotype A1 HBV isolated from HCC patients, interferes with signal peptide cleavage and leads to a decreased expression of HBeAg. The effect of the SSA HBV (sub)genotypes and the G1862T mutation on protein expression and host signalling pathways has not been studied. Therefore, in this thesis Huh7 cells were transfected with replication-competent clones of (sub)genotypes A1, A2, D3 E and G1862T mutation to study the proteome using mass spectrometry. Proteomic analysis revealed significantly differentially expressed proteins between different SSA (sub)genotypes and A1 with G1862T compared to the wild-type. These differentially expressed proteins were classified into signalling pathways. The different (sub)genotypes and the G1862T mutant of HBV were shown to affect various signalling pathways involved in three hallmarks of cancer including: immune evasion and persistence, sustained proliferative signalling and genome instability and mutation. In particular, subgenotype A1 was shown to favour the dysregulation of MAPK (immune evasion and persistence) and PI3K/Akt/mTOR (sustained proliferative signalling) pathways and when accompanied by the G1862T mutation showed dysregulation of DNA synthesis pathway leading to uncontrolled proliferation (genome instability and mutation). This was the first study that demonstrated, using comprehensive proteomic analysis differences among SSA genotypes and the effect of G1862T in protein expression in vitro. It provides novel insights into the molecular underpinnings of the oncogenic potential of HBV.Item A comparative study of trabecular structure of the patellofemoral joint: Evolutionary and biomechanical perspectives(University of the Witwatersrand, Johannesburg, 2024) Tommy, Kimberleigh Ashley; Schepartz, LynneThe knee joint in primates is important in facilitating a variety of locomotor behaviours. The patellofemoral joint (PFJ), which encompasses the distal femur and patella, has been relatively understudied from an evolutionary and biomechanical standpoint. The lack of detailed information limits our understanding of joint loading and associated kinematics. Trabecular bone is an ideal material for study as it is highly responsive to mechanical loading associated with different postural and locomotor behaviours. This thesis sought to pursue the question, ‘How do different activities, different locomotor kinematics, and different taxa manifest variation in the internal structure of this joint?’. To do this, trabecular structures in the distal femur and patella were explored using an inter- and intra- specific perspective. Trabecular parameters quantified in this study were bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), connectivity density (Conn.D) and degree of anisotropy (DA). All analyses were conducted on high-resolution MicroCT scans where eight volumes of interest (VOI) of the distal femur and nine VOIs in the patella were quantified. Inter-specific analyses were conducted on extant primates (Homo, Pan and Papio) and Plio-Pleistocene hominins from South Africa (Australopithecus sediba, Australopithecus africanus, and Homo sp./Paranthropus robustus). To explore intra-specific variation within a single species, two human samples (Later Stone Age foragers and contemporary Post-Industrial South Africans) were analysed to determine the effects of activity levels and knee joint pathology (osteoarthritis) on trabecular bone structure. The findings of this study show that there were significant differences in trabecular structure among extant primates and Plio-Pleistocene hominins that indicate unique loading across the PFJ, likely as a result of kinematically different bipedalism and a broader locomotor repertoire than seen in living humans today. This study also showed that significant differences in trabecular structure occur among some extant primate species and that these are likely linked to differences in knee joint loading arising from species-specific knee structure and positional/locomotor behaviours. Within Homo specifically, results showed that trabecular structure in the distal femur and patella differed between groups that demonstrated different activity levels and varying degrees of pathological osteoarthritis. Together, these results show that trabecular structure in the PFJ reflects complex loading and that further interspecific and intraspecific studies are necessary to improve our understanding of structural integrity in the primate knee.Item Effects of aqueous extract of kolanut (Cola nitida) on Sprague Dawley dams and exposure on the hippocampus of the progeny(University of the Witwatersrand, Johannesburg, 2024) Atiba, Foluso Ayobami; Ihunwo, A. O.Background: Kolanut, a tropical nut eaten by people across sub-Sahara Africa, contains caffeine, theobromine, catechins, and tannins. Pregnant women often eat it to suppress morning sickness. This study investigated the effects of kolanut on the structure and functions of the developing hippocampus. Methods: Kolanut extract at 400 mg/kg of body weight infused in gel cubes was fed to 6 female and gel cubes without kolanut to control 6 female Sprague Dawley rats from the first day of mating till parturition. Several behavioral tests were administered on the pups namely surface righting (SR), cliff avoidance (CA) across different age group, post-natal day (PND) 4, 5, 6 & 7, head rising, head pivoting, locomotion, open field, novel object recognition (NOR) and location (NOL), and radial-arm maze (RAM) PND 21 and 56. Their hippocampi were subjected to histology [Nissl, Golgi-cox], immunohistochemistry (Ki67 and DCX), biochemistry [malondialdehyde (MDA), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPX), transcription factors [brain-derived neurotrophic factor (BDNF), and acetylcholine (ACh)]. Expression of immediate (c-fos & c-jun) and memory genes (dlg3, dlg4, creb1 & creb2) were also determined. Results: Difficulty to get pregnant was observed in 33.3% of the dams; 16.7% had a still birth while 4.0% of the pups from dams fed kolanut-treated diet had paralysis of the limb. Kolanut significantly reduced the body weight (p < 0.001 – p < 0.0001) and increased brain weight, especially at PNDs 56 & 70 (p < 0.001 – p < 0.0001) of the dams and pups compared to the control. Food consumption was significantly (p < 0.05) lower for dams on kolanut-treated diet, but their water intake was significantly higher (p < 0.001). Kolanut significantly affected the behavioral indices of the animals; it significantly increased the latency of CA and SR tests across age groups (p <0.0001 and p < 0.0001 respectively). The frequency of head rising, frequency of pivoting and its latency, and locomotion were significantly (p < 0.01 – p < 0.0001) lower in animals fed kolanut-treated diet. Animals fed kolanut-treated diet showed anxiety during the open field tests on PNDs 21 and 56, and exhibited increased line crossing, corner time, distance covered and velocity (p < 0.05 – p < 0.0001). Frequencies of freezing episodes, grooming, rearing, fecal bolus and urination were also significantly (p < 0.01 – p < 0.0001) higher in animals that received kolanut-treated diet. The discrimination ratio of NOR and NOL were significantly 5 lower in animals fed kolanut-treated diet; they took longer duration to complete the tasks in RAM. Results from Golgi staining showed that kolanut caused pyknosis (p < 0.0001), inflamed soma, reduced aborization and synapses (p < 0.0001), reduction in spine quantity (p < 0.0001), change in morphology, fragmentation and constriction of the dendrites of the hippocampal neurons. When stained with DCX, the hippocampi of animals fed kolanut showed decrease in mean density of neuronal cells (p < 0.0001), increase number of pyknosis (p < 0.0001) and chromatolytic cells (p < 0.0001), neuronal atrophy, clumping, multi-layering and gliosis of the DG cells. In addition, the Ki67 showed a significant loss of proliferating cells (p < 0.0001) in the sub-granular zone of the DG. Kolanut significantly (p= 0.0067) increased the MDA and glutathione peroxidase levels. BDNF and ACh were significantly (p = 0.0001) increased by kolanut. A significant and positive correlation was found between SRT and MDA in PND 7 (r = 0.99, p = 0.0059), grooming and MDA in PND 56 (r = 0.77, p = 0.0252), grooming and BDNF in PND 21 (r = 0.76, p = 0.0297). A significant negative correlation was obtained between rearing and ACh in PND 56 (r = -0.83, p = 0.0115), Ki67 and MDA (p = 0.0213), and DCX cells and BDNF (p = 0.017). Prenatal kolanut consumption caused downregulations of cfos mRNA and cjun mRNA and creb1levels, an increase in creb2 level and a significant reduction in the levels of dlg3 mRNA and dlg4 mRNA, thus affecting the dendrites and spine morphology. Conclusion: Prenatal kolanut consumption adversely affected food intake, behavior, neuronal morphology, decreased neurogenesis and neuroplasticity and resulted in downregulation of genes important for normal development of the neurons and synapses. It exerted anti-neuroprotective effects by inducing oxidative stress, altering cholinergic system activity, stimulating over- expression of BDNF protein and concomitantly causing changes in morphology of the hippocampal neurons. Pregnant women and those of reproductive status need to be made aware of the adverse effects of kolanut consumption during pregnancy.Item Examination of the metatarsal diaphyseal nutrient foramina: Implications for forensic analysis and morpho-functional adaptations in 19th and 20th century individuals(University of the Witwatersrand, Johannesburg, 2024) Manjatika, Arthur Tsalani; Mazengenya, Pedzisai; Davimes, Joshua GabrielMetatarsal fractures occurring at the nutrient foramen (NF) level are debilitating and result in poor healing patterns due to disturbed blood flow. Variations in the topographical anatomy of the NF, which may be population-specific, make it challenging to understand its role in fracture development. The area around the NF is considered weak as the nutrient canal may reduce the structural integrity of the bone, predisposing the bone to a high risk of fracture development. However, there are no previous studies that examined the trabecular microarchitecture around the metatarsal diaphyseal NF to determine its fragility. In forensic settings, the NF of upper and lower limb long bones aids in the sex estimation of unknown individuals. However, the usefulness of the measurements around the metatarsal diaphyseal NF is unknown. This study aimed to examine the topography, morphometry and trabecular microarchitecture around the NF in 19th and 20th century South African populations. The study utilised 4284 dry cadaveric metatarsal bones (first to fifth, from the left and right sides) of South African populations, including South African Africans (SAA), South Africans of Mixed Ancestry (SAMA) and South Africans of European descent (SAED) that are housed in the Raymond A. Dart Collection of Modern Human Skeletons housed in the School of Anatomical Sciences, University of the Witwatersrand. The metatarsals were obtained from 438 individuals aged between 18 and 65 years (mean age 46.78 ± 13.29 years). The metatarsal bones were examined for topographical variations (i.e. location, position, number, size) of the NF. For sex estimation, five dimensions around the region of the NF (total length of the bone, distance from the proximal end to NF, circumference at the level of the NF, and mediolateral and dorsoplantar diameters at the level of the NF) were measured from 876 metatarsals from 186 individuals of the SAED, 995 metatarsal bones from 200 individuals of SAA, and 248 metatarsal bones from 51 individuals of the SAMA population. The direct and stepwise discriminant function (DFA) analysis and logistic regression (LRA) analysis were then used to generate functions for sex estimation from these measurements. For the analysis of age-related trabecular microarchitecture changes among the three modern populations (20th century) of South Africa, 88 metatarsal bones from 44 first and 44 fifth metatarsal bones were utilised. The age range for the specimens was 0-40 years. The bones were scanned using μCT to examine the trabecular microarchitectural parameters including bone surface volume (BS/BV), bone volume fraction (BV/TV), trabecular number (TbN), trabecular spacing (TbSp), trabecular thickness (TbTh), and local bone density for trabecular bone strength. Finally, 32 first and 32 fifth metatarsal bones were selected from SAA individuals from the age-matched (18-65 years) 19th and 20th century populations in order to determine secular changes in the trabecular microarchitectural parameters using μCT. Topographically, the NF was observed in 99.4% of all the metatarsal bones. Most (84.5%) of the metatarsals had a single NF. The highest number of NF observed on a single bone was 5. The NF were primarily (97.4%) located in the middle third of the metatarsal bones. The position of the NF exhibited variations depending on the bone. The first metatarsal bones had predominantly dominant-sized NF, while the second, third, fourth and fifth metatarsal bones had predominantly small-sized NF. Overall, there were no significant population topographical variations of the NF (P>0.05). Morphometrically, the dimensions around the NF exhibited sexual dimorphism in all populations. In the SAED, the classification accuracies for multivariable DFA and LRA ranged from 83.1-88.7%. In the SAA, the classification accuracies for multivariable DFA and LRA ranged from 75-80.5%. In the SAMA, the classification accuracies for multivariable DFA and LRA ranged from 75-83.7%. The BV/TV and TbTh showed higher values, and the BS/BV, TbN and TbSp showed lower values around the NF than at the proximal and distal diaphyses in all population groups (P<0.001). In the 20th century SAA, SAED and SAMA, the BV/TV and TbTh were highest, and the BS/BV, TbSp, and TbN were lowest in the 21-30 years group. In the 19th and 20th century SAA, the BS/BV, TbSp and TbN gradually increased while the BV/TV and TbTh gradually decreased from 18-29 to 50-65 years. Overall, there were no significant population differences in the trabecular microarchitecture between 19th and 20th century SAA individuals or across the 20th century SAA, SAED and SAMA. The present study found that the topographical anatomy of the metatarsal diaphyseal NF exhibits no significant population variations. The measurements around the metatarsal NF are sexually dimorphic. The DFA and LRA functions yielded high classification accuracies for sex estimation appropriate for forensic use in the SAED, but the functions can be cautiously applied in the SAA and SAMA for estimating sex in forensic and archeological settings due to low discriminatory power. The study demonstrated that the region around the metatarsal diaphyseal NF exhibits high BV/TV, TbTh, but low BS/BV, TbN and TbSp indicating high trabecular bone quality in the NF region compared to other parts of the metatarsal diaphysis across all age groups and the different populations examined. The study also demonstrated that there are no significant secular trabecular microarchitecture changes between 19th and 20th century individuals. Comprehensive knowledge of the NF is essential to understanding fracture development and repair patterns clinically and for use in estimating sex in forensic settings.Item Histo-morphological Perturbations in the Testes of Diabetic Sprague Dawley Rat Following Atripla® And Alcohol Co-administration(University of the Witwatersrand, Johannesburg, 2023-08) Owembabazi, Elna; Nkomozepi, Pilani; Mbajiorgu, Ejikeme FelixA decline in male fertility is increasingly becoming a major concern in this millennium. However, the associated effects of diabetes, alcohol abuse, and cART use and their interaction which are clinically important in male reproductive health have not received proper attention. Each of these conditions (diabetes, alcohol abuse, and cART use) has been shown to negatively impact the male reproductive system. Moreover, diabetes, alcohol abuse, and cART are intricately connected and thus can and occur simultaneously in an individual, a scenario that might provoke severe reproductive dysfunctions. Therefore, this study investigated the impact of diabetes, alcohol abuse, cART use, and their combinations on testicular histomorphometry, reproductive hormone profile, oxidative and inflammatory markers, germ cell proliferation and apoptosis, and androgen receptor expression. A total of forty-eight HIV naive rats (48) were divided into two main groups, non-diabetic and diabetic groups, which were further subdivided into four subgroups consisting of six rats each. The non-diabetic groups (1-4); Group 1; Control, Group 2: Alcohol treated (A), Group 3: combination antiretroviral therapy treated (cART), and Group 4: alcohol plus cART treated (A+cART). The diabetic groups (5-8); Group 5: diabetic only (DM), Group 6: diabetic treated with alcohol (DM+A), Group 7: diabetic treated with cART (DM+cART), and Group 8: diabetic treated with both alcohol and cART (DM+A+cART). The rats were fed normal rat chow and terminated after 90 days of treatment. Blood was drawn through a cardiac puncture into plain vacutainers, thereafter, animals were perfused with 0.1M phosphate buffer, and the testes harvested, weighed, and then fixed in 10% neutral buffered formalin for histology and immunohistochemistry analysis. During the experimental period, hyperglycemia, low glucose tolerance, and polydipsia were observed in the diabetic groups (5-8) only. Though, a general decrease in testis weight, volume, and size was found in all treated groups compared to the control group, a significant (p˂0.05) decrease was detected in the DM+A group only. With exception of the DM+A+cART group, the epithelial area fraction, epithelial height, and tubule area and diameter reduced significantly in all treated groups. The luminal area fraction and luminal diameter which significantly reduced in cART, DM, and DM+cART groups, were increased in A+cART. Further, connective tissue and interstitial area fractions increased significantly in all treated groups. The spermatogonia increased significantly in A, cART, DM, and DM+A+cART groups relative to control group, but reduced significantly in DM+A. However, spermatocytes, round spermatids, and elongated spermatids decreased significantly in all treated groups, with exception of spermatocytes of the alcohol group. All treated groups showed a decrease in the number of Sertoli cells relative to the control but a significant decrease was only found in the DM+A group, but all treated groups had significantly decreased Leydig cell diameter and volume. Johnsen’s testicular score was significantly reduced in A, A+cART, DM, and DM+A treated groups. Additionally, varying severity of seminiferous tubules (ST) lesions such as shrinkage of ST, lifting of epithelium, widened intercellular space, karyolysis, epithelial sloughing, ST atrophy, multinucleated giant cells, and germinal epithelium derangement were observed in the treated animal groups. Further, the thickness ST basement membrane increased significantly in cART, DM, and DM+cART groups but testis capsule thickness increased significantly in A+cART, DM+A, and DM+A+cART groups. The testicular interstitial connective tissue fibers viz. collagen, reticulin, and elastin reduced significantly in all treated groups, except for the reticulin which was non-significantly decreased in the alcohol (A) group. Furthermore, luteinizing hormone was significantly elevated in A and A+cART groups but significantly reduced in the DM+A+cART group. However, follicle-stimulating hormone increased significantly in all treated groups, with exception of DM+cART group. Testosterone levels were significantly reduced in DM, DM+A, and DM+A+cART groups, but no significant difference (p>0.05) was found in the inhibin B level in all treated groups compared to the control. In addition, the intensity and number of Sertoli and Leydig cells expressing androgen receptor were significantly reduced in all treated groups, except for the number of Sertoli cells expressing androgen receptor in the alcohol group. Expression of inflammatory markers (IL-1β, TNF-α, and IL-6) was upregulated in all treated groups, with exception of IL-1β of the A+cART group and TNF-α of cART and A+cART groups. The markers for oxidative stress (iNOS, MDA, and 8-OHDG) and apoptosis (caspase 3) were upregulated in all treated groups, with exception of MDA in the alcohol group. Though, the number of germ cells expressing proliferation marker Ki-67 was significantly reduced in all treated groups, the staining intensity was significantly increased compared to the control group. The results show that diabetes, alcohol abuse, cART, and their combinations have deleterious effects on the testicular histoarchitecture and function, which are suggested to result from the upregulation of oxidants and cytokines and androgen receptor depletion. The results further suggest that the interaction arising from a co-presence of cART and alcohol in diabetic condition could mildly diminish their independent effects due to their common cytochrome P450 metabolic pathway. This study yielded invaluable data on the contribution of cART alcohol-diabetes interaction on the male reproductive functioning/dysfunction and hopefully will help clinicians in managing reproductive challenges in patients of this category.Item Characterising skeletopathy in an animal model of type 2 diabetes(University of the Witwatersrand, Johannesburg, 2022-11) Dlamini, Gcwalisile Frances; Ndou, RobertType two diabetes (T2D) is a chronic, progressive heterogonous syndrome with a genetic and environmental origin. It is now recognized as an epidemic with a high morbidity and mortality rate. The endocrinology of type 2 diabetes (T2D) and its predisposing factors have been studied extensively, while diabetic skeletopathy has received negligible research. Previous studies report that fractures in T2D vary with specific sub regions in bones, therefore prompting our study to focus mainly on the femoral head and neck as well as the humerus head. Femoral neck fractures are the commonest, followed by the proximal femur, distal radius and proximal humerus. Susceptibility to fracture is a sequelae of poor bone remodeling. Poor bone remodeling is established at molecular and cellular levels. It depends on the activity of osteoblasts, osteocytes and osteoclasts, which are under the influence of TGF-β1, a pro-osteogenic cytokine, together with BMP3, an anti-osteogenic cytokine. T2D induced bone marrow adipocity and the accumulation of AGEs in cortical bone have also been implicated in increasing susceptibility to fracture. It is still unclear how T2D affects molecular and cellular elements that culminate in weaker bones observed in diabetic patients. In addition, it is debatable if T2D affects the skeleton at disease onset or later in the disease. Therefore, this study aimed to characterize T2D induced skeletopathy and related it to age, in the Zucker Diabetic Sprague Dawley (ZDSD) rat, using the femur and humerus. This study initially confirmed the diabetic state by monitoring animal weights, fasting blood glucose levels, and fasting oral glucose tolerance tests (OGTTs) every fortnight. Then triglyceride levels and quantified serum levels of osteoregulatory hormones such as insulin and osteocalcin were monitored. To assess oxidative stress, Malondialdehyde (MDA) serum levels were also determined by ELISA. Once diabetes was successfully induced, rats were grouped according to strain and age at termination. Termination age was at 20 weeks and 28 weeks . The Sprague Dawley (SD) rats were the controls, while the Zucker Diabetic Sprague Dawley rats (ZDSD) were the experimental groups. These were designated as SD20WK (n=8) and ZDSD20WK (n=7) respectively. Another batch was designated as SD28WK (n=8), and ZDSD (n=15) that were terminated at 28 weeks of age. The latter were further divided into moderate diabetes (ZDSD28WK-MOD) (n=9) and severe diabetes (ZDSD28WK-SVD) groups (n=6). Bilateral humeri and femora were harvested then fixed in 10% buffered formalin. Right proximal femora and humeri were scanned using a 3D-μCT scanner (Nikon XTH 225L) to analyse trabecular morphometric parameters, cortical bone area and medullary canal area. Biomechanical strength was analyzed by three point bending tests using a universal tensile tester. Left proximal femora and humeri were processed for histology. Some sections were stained with Haematoxylin and Eosin (H&E) to assess normal histologic morphology and adipocyte quantification. Remnant sections were immunolabelled using the anti-TRAP and anti-ALP antibodies for osteocyte and osteoblast quantification respectively, to assess osteolysis and osteogenesis. Immunolocalization of AGEs, TGF-β1 and BMP3 was also conducted to investigate their role in diabetic skeletopathy. We found that diabetes affected osteoblastogenesis as measured by ALP positive cells and bone marrow adipocytes. TRAP positive osteocytes numbers were increased in the presence of T2D, suggesting an increased osteolysis. There was reduced TGFB1 expression with increased BMP3 expression. The number of AGEs immuno-positive cells as well as its extracellular expression was increased. Our finding suggest that osteoblast and osteocyte numbers are regulated by TGFβ1 and BMP3 in both bones, under the influence of AGEs. Our findings from osteometry, 3-point bending tests and Micro CT support that diabetes weakens bone. The diabetic effect results in lighter, shorter hollow bones that perform poorly under loading, as well as exhibit unfavourable trabeculae microarchitecture. Our findings confirm that T2D causes increased fragility in the proximal femur and humerus as well the mid-diaphysis. These perturbations occur early and late in the disease, and they are also exacerbated by the presence of hyperglycemia. We conclude that the ZDSD rat can be used as a translational model for diabetic skeletopathy at cellular and molecular level, and it can be extrapolated to humans after consideration of other factors like, basal metabolism, age, sex and skeletal loading patterns. We recommend optimal control of blood glucose levels at all stages of the disease to reduce the incidence of fractures in diabetic patients.Item Morphological changes in the lungs and air sacs of the Japanese quail (Coturnix japonica) exposed to heat stress(University of the Witwatersrand, Johannesburg, 2023-08) Abdulkadir, Abdurrahman; Reddy, DeranThe Japanese quail presents a potential protein food security alternative in rural sub-Saharan Africa because of its small size and easy husbandry. The nutritional and therapeutic value of its meat and egg makes it an interesting and better choice than chicken in some parts of the world. In addition, researchers used Japanese quail as an animal model of human genetic and developmental disorders because of its short generational interval. However, global warming threatens its welfare by propagating heat stress. The physiological response of Japanese quail under heat stress causes negative performance and sometimes instant mortality. Hence, in this study, lung of the quail under heat stress was microscopically examined as it is the most important organ for survival under heat stress. All other organs depend on the lungs for oxygen, and it is also the most crucial in evaporative cooling. A total of 38 Japanese quail were used in this study. A pilot study was conducted that used eight quails, to ensure the possibility of survival under the proposed experimental temperatures. Afterwards, 30 quails were randomly allocated — based on initial body mass— to five groups of six quails each. The control groups (CT and CT2) were maintained at a thermoneutral temperature of 25°C throughout the experiment while acute heat stress group (AH) were maintained at 38°C for 24 hours only. The chronic heat stress groups (CH1 and CH2) were maintained at 35°C for seven days and 28 days respectively. Body mass, cloacal temperature, and respiratory rate of quails were measured daily to monitor health and detect any serious ill health from heat exposure. Food and water were provided ad libitum. At the end of the experiment, all quails were terminated using an overdose of anaesthetic and lungs were harvested and processed for microscopy. Lung weight, volume and size were measured before sampling. Tissue samples were processed, and sections were cut with a microtome and stained with Mayers H&E, new pentachrome stain and Gomori’s one-step trichrome stain. Other tissue samples were triple immunolabelled with anti-α-SMA and Collagen 1 antibody and DAPI nuclear stain. Tissue samples were also processed for scanning and transmission electron microscopy. No significant difference in body mass, cloacal temperature, respiratory rate and lung parameters was found in heat-stressed quails compared with control. However, microscopic examination revealed blood congestion and excessive leakage of blood into airway of lungs in heat-stressed groups compared with the control. In addition, there was structural damage to parenchyma and blood vessels, which incites an inflammatory response causing deposition of collagen fibres in some areas of the lungs in heat-stressed groups. Interestingly, these effects occur in a time-dependent pattern. The most impact is seen in AH and CH1 groups while CH2 shows signs of recovery. In conclusion, Japanese quail lung was negatively impacted by heat stress, which can lead to instant mortality or long-term reduction of performance. Despite the evidence from this study suggesting that Japanese quail can adapt to the effects of heat stress if it survives the initial impact, a conscious effort must be made to alleviate or remove heat stress for quality outcomes.Item In vitro and in silico characterization of the anticholinesterase activity of select terpenoids against anopheles vectors(2024) Rants’o, Thankhoe AbramMalaria is a life-threatening plasmodial disease that is transmitted by female Anopheles mosquitoes. Major African malaria vectors include Anopheles arabiensis, An. funestus, An. gambiae and An. coluzzii. Malaria vector control programs have shown effectiveness in reducing the Anopheles populations. The main insecticide classes used in these interventions include pyrethroids, organochlorines, organophosphates, carbamates, and neonicotinoids. Nevertheless, the development of Anopheles resistance to these insecticide classes has greatly reduced the effectiveness of these interventions. A common resistance mechanism is through rapid detoxification of insecticides by overexpressed P450 monooxygenases. Although acetylcholinesterase (AChE) is a valid target in Anopheles vector, current anticholinesterase insecticides suffer from resistance and low selectivity between insect and mammal AChE targets. This indicates the urgent need to discover novel AChE inhibitors with higher affinity to Anopheles AChE compared to the mammal target, and less prone to resistance caused by the overexpressed monooxygenases. Identification of novel AChE inhibitors from natural sources and their potential to kill Anopheles during all its different life stages, presents a cost-effective approach. This PhD study aimed to identify such novel AChE inhibitors from essential oil sources and assess them for consistent activity against Anopheles species with hyperactive P450 monooxygenases. In this study, molecular differences between Anopheles and human AChEs were identified showing the opportunity to develop selective Anopheles AChE inhibitors. A novel approach was used to integrate the in silico and in vitro assays in assessing the Anopheles AChE inhibitory potential of select terpenoids and coupled these to the in vivo assays against different life stages of Anopheles. The terpenoids, farnesol, (-)-α-bisabolol, cisnerolidol, trans-nerolidol, and methyleugenol were identified as potent Anopheles AChE inhibitors and larvicidal agents with moderate adulticidal effects. Farnesol and (-)-α-bisabolol also displayed pupicidal activity, while methyleugenol inhibited the hatching of Anopheles eggs. Generally, farnesol and (-)-α-bisabolol were highly active across the Anopheles species, except in the strain with P450-based metabolic resistance. In contrast, the efficacy of cisnerolidol, trans-nerolidol, and methyleugenol was not affected by this resistance mechanism. This research suggests that cis-nerolidol, trans-nerolidol, and methyleugenol are potential candidates for further development as anticholinesterase bioinsecticides.Item Evaluation of antioxidant properties and neuroprotective effects of methanolic leaf extract of combretum molle in D-galactose-induced aging model of Sprague Dawley rats(2024) Fasemore, Thandi Mamorapelo DorothySeveral physical and biochemical changes in the body occur because of the biological process of aging. As part of natural aging, the brain encounters morphological and functional changes that affect dendritic trees and synapses, neurotransmission, circulation, and metabolism. The brain's high metabolism, elevated levels of lipids, and inadequate antioxidant defences make it susceptible to oxidative stress. A reducing sugar called D-galactose (D-gal) causes a significant build-up of reactive oxygen species (ROS). Combretum molle (C.molle) is a plant rich in compounds that scavenge free radicals and is frequently used to cure a variety of human illnesses in African traditional medicine. This study investigated the potential impact of C.molle on rat brain aging brought on by D-galactose. Fifty adult male Sprague Dawley rats were treated for 90 days and were composed of 5 groups (n=10) as follows: I) Control group received saline and distilled water, II) C.molle only group received intragastric gavage of C.molle (500 mg/kg), III) D-gal only group received a subcutaneous injection of D-galactose (150 mg/kg), IV) CMD 90 group received D-galactose and C.molle simultaneously for 90 days, V) CMD 45 group received D-galactose for the first 45 days and C. molle for the remaining 45 days. The animals underwent behavioral evaluation post-treatment for a further period of 7 days twice a day. The rat’s cognitive function was evaluated through Novel object recognition and object location tests. The C.molle ’s neuroprotection was evaluated through levels of acetylcholinesterase (AchE), Acetylcholine (Ach), Brain Derived Neurotropic Factor (BDNF), and Tumor Necrosis Factor (TNF) alpha including the effects on adult neurogenesis through Ki-67 and doublecortin (DCX) immunohistochemistry. The oxidative stress level was measured through the evaluation of lipid peroxidation marker malondialdehyde (MDA), glutathione peroxidase (GSH-Px), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activity. The C.molle significantly attenuated the effects of D-galactose-induced changes in the hippocampus and cortex, ranging from cognitive capacity, and oxidative stress by increasing GSH, BDNF, Ach, GSH-Px, CAT, and SOD activity. Additionally, C. molle caused a decrease in the levels of MDA, TNF alpha, and AchE activity, and ameliorated reduced cell proliferation and neuroblast differentiation brought about by D-galactose.Item Effect of boophone disticha on the behaviour and hippocampal neuroanatomy in a BALB/c mouse model(2024) Xhakaza, Nkosiphendule KhuthazelaniDepression is one of the most common neuropsychiatric disorders and is associated with dysfunction of the neuroendocrine system and alterations in specific brain proteins. Boophone disticha (BD) is an indigenous psychoactive bulb that belongs to the Amaryllidacae family, which is widely used in Southern Africa to treat depression, with scientific evidence of potent antidepressant-like effects. The present study examined the antidepressant effects of BD and its mechanisms of action by measuring some behavioural parameters in the elevated plus maze, light dark box, open field forced swimming, brain content of corticosterone, brain derived neurotropic factor (BDNF), and neuroblast differentiation in the hippocampus of Balb/c mice exposed to the five-day repeated forced swim stress (5dRFSS) and 28 days chronic restraint stress. Male Balb/c mice were subjected to the 5dRFSS and 28 days chronic restraint protocols to induce depressivelike behaviour (decreased swimming, increased floating, decreased open arm entry, decreased time spent in the open arms and decreased head dips in the elevated plus maze test, increased time in dark box in the light dark box test, reduced frequency of rearing and increased time on the sides of the open field in the open field test), and treated with distilled water, fluoxetine and BD. Three weeks Boophone disticha treatment (10mg/kg/p.o) significantly attenuated both the 5dRFSS and chronic restraint-induced behavioural abnormalities and the elevated brain tissue corticosterone levels observed in stressed mice. Additionally, 5dRFSS exposure significantly decreased the number of neuroblasts in the hippocampus and BDNF levels in the brain of Balb/c mice, while fluoxetine and BD treatment attenuated these changes. In the chronic restraint stressed mice, similar effects of BD treatment were observed after 21 days of treatment, however, the levels of corticosterone were not different in control and stressed animals, probably due to habituation to stress. In both 5dRFSS and chronic restraint stress, the antidepressant effects of BD were comparable to those of fluoxetine, but unlike fluoxetine, BD did not show any anxiogenic effects, suggesting better pharmacological functions. It is important to note that in chronic restraint stress mice, it appeared that animals seemed to have habituated to stressful conditions, demonstrated in part by brain tissue levels of corticosterone that were not elevated in stressed animals treated with distilled water. However, BDNF levels remained significantly low in stressed animals treated with distilled water, suggesting that the effect of chronic stress in this parameter were not reversed when animals habituated. In conclusion, our study shows that BD exerted antidepressant-like effects in both 5dRFSS and chronic restraint stress mice, mediated in part by normalizing brain corticosterone and BDNF levels. Due to some degree of habituation in chronic stress model, caution should be exercised when evaluation effects of treatment in different parameters to evaluate antistress effects of tested agents, particularly levels of corticosterone. Furthermore, the persistent low levels of BDNF suggest that habituation of animals to chronic stress is due to normalising levels of corticosterone but not BDNF. The above occurrence could suggest that recovery from chronic stress without antidepressant treatment could alleviate other behavioural symptoms but not cognitive impairment which is influenced in part by BDNF levels.