UWCScholar :: Browsing by Author "Hiss, Donavon"

Browsing by Author "Hiss, Donavon"

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Antibacterial activity of some South African plant extracts against streptococcus mutans
(University of the Western Cape, 2015) Kelani, Madeha Mohammed; Hiss, Donavon; Mohammed, Ahmed
Good oral health has a major influence on the general quality of life and well-being. Several chronic and systemic diseases have been attributed to poor oral health. With the increasing incidence of oral diseases, the global need for alterative prevention and treatment methods and safe, effective, and economical products has expanded. There are many studies showed that Streptococcus mutans has been implicated as major etiological agent of dental caries. South African has very rich natural flora especially Cape region. Several South African medicinal plants have been used since immemorial time for treatment of different human pathologies including dental problems. The antibacterial activities of plants extracts have been recognized and documented scientifically during the last few decades. In this project we aimed at the screening of 31 South African plants randomly collected from Cape region for their antibacterial activity against Streptococcus mutans initially at two concentrations (500 and 100 µg/ml).MIC’s and MBC’s were determined for the active plant extracts, as well as the qualitative studies of the effect of the active extracts on the biofilm formation. The best or the most active safe plant (Psoralea fruticans) was submitted to chromatographic separation to isolate the bioactive compounds which could be responsible for such activity. Identification of the pure active compounds was carried out using different spectroscopic techniques. Finally the biological evaluation of the isolated pure compounds was measured against S. mutans and also the cytotoxicity studies in-vitro against normal cells lines was carried out.
Criteria to facilitate the implementation of woman-centred care in childbirth units of Limpopo Province, South Africa (Part 2)
(OASIS OpenJournals, 2013) Maputle, Maria S.; Hiss, Donavon
Background: Facilitation of mutual participation, respectful and egalitarian relationship between the mother and the midwife during childbirth is a critical aspect. This article delineated the criteria that would facilitate the implementation of woman-centred care in childbirth units of the Limpopo Province in South Africa, following a concept analysis described in Part 1. Empirical referents or indicators were used to measure the concept woman-centred care and to validate its existence in reality. These empirical referents were referred to as measurable properties that further verified the concept. Objective: The objective of this article was to formulate criteria that would facilitate implementation of woman-centred care in childbirth units of Limpopo Province in South Africa. Method: Criteria to facilitate the implementation of woman-centred care were formulated by the gathering of information about the topic under review and the use of resources to define the key elements of the criteria which were integrated into the Batho Pele principles. The criteria were then validated by selecting with a vested interest in the successful development and implementation of the criteria. Results: Criteria were formulated to facilitate the implementation of woman-centred care that was integrated within the framework of Batho Pele principles. Conclusion: These formulated criteria for woman-centred care will be used as an institutional self-evaluation tool to enhance implementation of the Batho Pele principles in childbirth units. These criteria will give direction and provide guidelines for the performance of midwifery staff and will also help supervisors to guide staff to improve performance.
Does Olea africana protect the heart against ischemiareperfusion injury?
(2009) Maliza, Asanda; Dietrich, Daneel; Hiss, Donavon
Cardiovascular disease is a major health problem and remains the number one cause of death worldwide. For centuries, medicinal plants have been used in different cultures as medicines for the treatment and control of various diseases. Olea africana, also known as the wild olive, is amongst the herbal plants used by people to treat many ailments.Recently, scientific studies on the hypotensive, vasodilatory and antidysarrhythmic effects of O. africana have been reported. Triterpenoids isolated from the O. africana leaves, for example, have antioxidant properties. The aqueous extract from the leaves of O. africana also have angiotensin-converting enzyme (ACE) inhibitory effects. ACE inhibitors and antioxidants protect the heart against ischemic-reperfusion injury. The serine / threonine protein kinase B (PKB) also known as Akt is activated downstream of phosphoinositide 3- (PI-3) kinase (PI-3-Kinase) and is involved in cardioprotection against ischemia-reperfusion injury. Angiotensin II (AII) decreases the intrinsic PI-3-kinase activity. In this study, we hypothesized that ACE inhibitors increase PI-3-kinase activity and thus activates PKB. The aims of this study were: 1) to determine whether treatment with the crude aqueous extract of leaves of O. africana protect the heart against ischemic-reperfusion injury and 2) if so, to determine whether the protection is mediated via the PKB signaling mechanism. Hearts isolated from male Wistar rats were perfused with different concentrations of the plant extract. In one set of experiments, male Wistar rats were treated with the plant extract (1000 mg/kg/day) for 5 weeks for the evaluation of cardiac function before and after ischemia. At the end of the experiments, hearts were freeze-clamped and kept for PKB / Akt determination. In another set of experiments, we determined the effect of O. africana extract (1000 mg/kg/day) or captopril (50 mg/kg/day) on infarct size. Rats fed jelly served as controls for captopril. In a subset of experiments, hearts were frozen immediately after treatment with O. africana extract (1000 mg/kg/day) or captopril (50mg/kg/day) and PKB were determined.Perfusion with the plant extract significantly decreased coronary flow (p<0.05). The heart function was decreased as evidenced by observed decreases in the force of contraction and heart rate, although these were not measured. Chronic treatment with the crude aqueous plant extract had no effect on cardiac function before ischemia, functional recovery (% left ventricular developed pressure and % rate pressure product) and PKB /Akt phosphorylation (p>0.05). Both the aqueous extract of O. africana leaves and captopril had no effect on infarct size compared to the control group (p>0.05). Captopril,however, improved the recovery of the left ventricular developed pressure. Non-perfused hearts isolated from rats treated with O. africana extract and captopril did not show any response to both captopril and the O. africana extract treatment as measured by PKB /Akt phosphorylation. The results of the present study suggest that the crude aqueous extract of O. africana is not cardioprotective against ischemia-reperfusion injury in this system of the isolated perfused rat heart.
Effect of Eurycoma longifolia (Tongkat Ali) on the prostate cancer cell line LNCaP
(2013) Abouhamraa, Hamza; Henkel, Ralf; Hiss, Donavon
Eurycoma Longfolia Jack, also known as Tongkat Ali (TA) is a tropical plant belonging to the family of Simaroubaceae is widely distributed in South East Asian countries. The extracts of TA have been proven to have cytotoxicity, anti-proliferative and aphrodisiac properties. In vitro assays revealed cytotoxicity toward human breast cancer cell lines MCF-7, KB, CaOV-3, RD, DU-145and HepG2 human liver cancer cells and appear promising as a new chemotherapeutic agent against human cervical carcinoma (HeLa) cells. Although, there are extensive studies reported on its cytotoxicity benefits there are none pertaining to LNCaP human prostate cell line. Therefore, this study aimed at testing the effects of TA on LNCaP cells and prostate specific antigen (PSA) production. Materials and Methods This study investigated the effect of different concentrations of TA (0.0025, 0.025, 2.5, 25 and 250 g/ml) TA on LNCaP human prostate cancer cell line for 24 and 96 hours. The following parameters were investigated: morphology, cell viability (MTT), testosterone modulation, Annexin V-CY3 binding (Apoptosis), DNA fragmentation (TUNEL), caspase 3/7 activity (apoptosis), and PSA production. Results When observing the morphological changes of LNCaP cells exposed to TA, a clear increase in detachment and cell death via apoptosis as the concentrations of TA increased. The viability decreased significantly in both 24 and 96 hour treatment of TA at higher dosages (25 and 250 g/ml). The significant inhibitory effects on testosterone stimulated cell proliferation were seen at TA concentrations as low as 0.0025 μg/ml TA. At higher concentrations of TA (25 and 250 μg/ml), for all testosterone dosages a decreasing trend in proliferation was found. vii Testosterone concentrations of 10 nM showed maximum stimulation of cell proliferation for TA dosages up to 2.5 μg/ml. All concentrations of TA showed significant increase in apoptosis of the cells as dosages increased. A higher amount of DNA damage found at the highest dosage (250 μg/ml) of TA. The relative caspase 3/7 activation showed significant (P=0.0043) activation at the highest concentration (250 μg/ml) of TA. Relative PSA production resulted only a 5% increase with no significant difference at all doses indicting that TA does not change the cell PSA production and the decline in PSA concentration is due to LNCaP cells dying as a result of this exposure to TA. Conclusion In summary, the major finding of this study is that Tongkat Ali inhibits the viability of prostate cancer cell lines (LNCaP) through caspase-mediated pathway, as well as increased the level of apoptotic such as DNA fragmentation. In addition, Tongkat Alin also inhibited PSA production. In LNCaP cells, testosterone with the addition of TA does not increase the growth of the cells. However, more in-vitro and in-vivo studies are needed to establish the exact constituents of the extracts and their mechanism of action. Thus, this study opens perspectives on the use of Tongkat Ali preparations in the treatment of aging male symptoms, prostate cancer prevention or as additional treatment to standard prostate cancer therapy.
The effect of sunitinib on neuroblastoma and glioblastoma cell growth
(University of the Western Cape, 2020) Roos, Kelly; Hiss, Donavon; Flepisi, Brian
Cancer is a global health catastrophe, with neuroblastoma, the most common solid childhood tumor, and glioblastoma, a deadly brain tumor, being aggressive and unresponsive to current treatment modalities. These tumors are known to utilize uncontrollable cell proliferative capabilities as a mechanism for tumor survival. Therefore, malignant cell growth can be mitigated by targeting the essential proteins that regulate cell growth, such as receptor tyrosine kinases (RTKs). Under normal physiological conditions, RTKs bind with varying affinity to mitogenic stimuli such as growth factors such as vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) which, in turn, leads to receptor phosphorylation and activation.
The effects of doxorubicin loaded chitosan-alginate nanoparticles on SK-N-BE(2) neuroblastoma cells
(University of the Western Cape, 2022) Rahman, Ziyaad; Hiss, Donavon
Cancer is a life-threatening disease and one of the leading causes of death globally. Cancer was thought to be associated with developed countries only but it is increasingly becoming a major health challenge in developing countries, including South Africa. Neuroblastoma is a form of cancer that affects the very early forms of nerve cells and is the most common extra-cranial solid tumour in children. It develops mainly in the adrenal medulla and the sympathetic ganglia. The focus of the present study is the development of a doxorubicin-loaded nanoparticle drug delivery system for the treatment of neuroblastoma. The biological diversity of the neuroblastic tumours that occur in patients has led to a divided approach in therapeutic strategies. Recent research efforts are aimed at designing therapies that will exploit the key oncogenic features of tumours, either within the tumours, in the tumour microenvironment, or both. Although doxorubicin chemotherapy is known to be generally very effective, previous studies have shown that it may result in the undesired toxicity of cardiomyocytes, cardiac fibroblasts, cardiac progenitor cells, endothelial progenitor cells, smooth muscle cells, and mesenchymal stem cells.
Genomic instability in South African breast cancer patients
(2013) Langa, Bridget Cebisile; Abdul-Rasool, Sahar; Hiss, Donavon
Breast cancer (BC) is one of the most common malignancies in women. Death results from treatment failure and metastatic disease. Thousands of lives might be saved if it was possible to detect and eliminate occult metastatic cells before they become clinically evident. Therefore, there is a critical need to identify new markers to improve treatment options for these patients. Genomic instability is the earliest indication of breast cancer and the use of genomic methodologies is a progress towards early detection and treatment, through the identification of biomarkers that can be translated into novel therapy targets. The interferon regulatory factor-1(IRF-1) gene, localized on chromosome 5q31.1, is believed to act as a tumor suppressor gene in breast cancer. The IRF-1 was found to be inactivated by single nucleotide polymorphism (SNP) in breast cancer suggesting that the loss of its function might be critical to the development of the disease. The phosphatidylinositol 3-kinase (PIK3) signaling pathway mediates key cellular functions and alterations of genes in this pathway, including PIK3CA, serine-threonine protein kinases (AKT1and AKT2), phosphatase and tensin homolog (PTEN), fibroblast growth factor receptor 2 (FGFR2) and ERBB2, whose expression have been demonstrated to be altered in breast cancer patients. In addition, these genes are linked to treatment resistance. vi In this study, we have investigated allelic loss of IRF-1 gene in primary tumors obtained from patients undergoing mastectomy at Groote Schuur hospital (Cape Town, South Africa). These samples were then further analyzed for the DNA copy number changes of specific genes involved in the PIK3/AKT signaling pathway. Statistical analysis has been performed in order to correlate genomic findings with clinical-histopathological and follow up information from the patients and to establish whether these genes can predict prognosis. Our data analysis has indicated that 46 cases (45.5%) out of 101 cases were informative for the IRF-1 dinucleotide marker used for LOH analysis (Figure 3.1). LOH was detected in 23 of these informative cases (23/46; 50%). No statistical significance was found between LOH at the IRF-1 locus and age (≤50 years or >50 years) (P value = 1.0000) and earlier stage (Stages I and II) (P value= 0.4982) based on Fisher’s exact test. Patients presented a high level of DNA copy number changes in genes involved in the PIK3/AKT pathway. The most frequent changes were observed in the PIK3CA and PTEN genes. PIK3CA presented high copy number in 36.8% of the cases. PTEN was observed with low copy number in 47.5% of the cases. This dissertation shows the effectiveness of genomic methodologies as means for the detection of early breast cancer progression in South African women. The PIK 3/AKT genes can validate the usefulness of breast cancer therapies.
In vitro neuroprotective effects of boophone disticha, brunsvigia bosmaniae and strumaria truncata extracts in sh-sy5y cells.
(University of Western Cape, 2021) Kangwa, Tusekile Sarah; Ekpo, Okobi; Hiss, Donavon
Parkinson's disease (PD), the second most common neurodegenerative disorder after Alzheimer's disease, is one of the leading disability disorders with about 10 million people affected worldwide. The pathological hallmarks of PD are defined by the loss of dopaminergic neurons in the substantia nigra pars compacta of the midbrain with its characteristic clinical motor and non-motor symptoms. However, the loss in dopaminergic neurons causes characteristic clinical manifestations, which include non-motor and motor symptoms. Damage to cholinergic neurotransmitter systems causes non-motor symptoms like sleeping disorders, depression, and a variety of other psychiatric issues, while a malfunctioning nigrostriatal dopaminergic pathway causes such motor symptoms as tremors, stiffness, and postural instability. PD symptoms usually mirror the degree of alteration to neuronal integrity in the affected parts of the brain, but the severity of progression varies with each patient.
Platelet - Rich Fibrin (PRF) - The effect of storage time on platelet concentration
(South African Dental Association, 2015) Peck, Mogammad T.; Hiss, Donavon; Stephen, L.; Satti, A.; Majeed, Abdul
The aim of this study was to determine whether storage time had a significant effect on the platelet concentration of platelet-rich fibrin (PRF). Three blood samples were drawn from each participant into a sterile blood sampling tube. Two of the blood samples were centrifuged to form PRF. The third non-centrifuged sample was used to measure the baseline blood platelet concentration. After PRF had formed, it was removed from the respective test tubes at different time intervals i.e. immediately after centrifugation (Group A) and after 60 min of storage time in the blood collecting tube (Group B). The residual blood from each group was tested for platelet concentration and compared with the baseline reading (as an indirect measure of the platelet concentrate of PRF). The PRF produced in Group A (PRF A) had a mean platelet concentration of 274 + - 57.8 X 109/L, whereas the PRF of Group B (PRF B) was 278 + - 58.2 X 109/L. A statistically significant difference was seen between the groups (p < 0.001).
The effects of selective inhibitors of N-Glycosylation and Endoplasmic Reticulum stress inducers on Neuroblastoma cell proliferation and Apoptosis
(University of the Western Cape, 2017) Eshiak, Ebtehal Elkamel M.; Hiss, Donavon
Among all childhood cancers diagnosed, neuroblastoma (NB) is the most prevalent during infancy. In patients younger than 15 years, it accounts for more than 7% of malignancies and about 15% of all paediatric mortalities. A family history of NB is considered a genetic predisposition and risk factor. In 1-2% of inherited cases, the molecular causative factors linked to the disease are germline mutations, including anaplastic lymphoma kinase (ALK, gain of function), PHOX2B (loss of function) and MYCN (gain of function). NB differs from most solid tumours because of its heterogeneity in both pathobiologic and clinical behaviour, ranging from spontaneous regression to highly-aggressive metastatic disease resistant to conventional and investigational anticancer drugs. Hence, NB embodies a spectrum of disease.
The effects of selective inhibitors of n-glycosylation and endoplasmic reticulum stress inducers on the expression of neuroblastoma drug resistance
(University of the Western Cape, 2017) Husein, Wejdan A.B. Mahmud; Hiss, Donavon; Ekpo, Okobi
Neuroblastoma (NB) represents 8-10% of all childhood tumours and accounts for approximately 15% of all cancer-related deaths in the paediatric population. Approximately half of newly diagnosed children with this tumour will present with metastatic disease or histologically aggressive large tumours that are at high risk for treatment failure. Since NBs are often widely disseminated and the tumours genetically heterogeneous in terms of their growth and metastatic behaviour, it is challenging to pinpoint their origin and predict disease prognosis. Several risk factors have been identified to play a role in disease progression, including age at the time of initial presentation, tumour stage, histology and ploidy of the tumour, and cytogenetic aberrations such as MYCN amplification, anaplastic lymphoma kinase (ALK), loss of heterozygosity of 11q and gain of 17q chromosomes.
Will the new Consumer Protection Act prevent harm to nutritional supplement users?
(Health & Medical Publishing Group, 2011) Gabriels, Gary; Lambert, Mike; Smith, Pete; Hiss, Donavon
BACKGROUND. There is no clear distinction between the regulation of food, supplements and medicines in South Africa. Consequently, grey areas exist in implementing the legislation, particularly in the supplement industry. The increase in supplement sales in South Africa can be attributed to aggressive marketing by manufacturers whose claims are not always supported by published peer-reviewed evidence. Such claims often go unchecked, resulting in consumers being mislead about the role of supplements. As a result of poor regulation, contaminants or adulterants in supplements may also cause insidious effects unrelated to the listed ingredients. AIM. To assess the regulations, legislation, and claims associated with nutritional supplement products in South Africa. METHOD. Peer-reviewed literature and the relevant South African statutes were consulted. RESULTS. The National Health Act incorporates the Medicine Control Council, which is charged with ensuring the safety, quality and effectiveness of medicines, and related matters, including complementary/alternative medicines. The South African Institute for Drug-Free Sport and Amendment Act provides for testing athletes for using banned substances, but currently does not concern itself with monitoring nutritional supplements for contaminants or adulterants that may cause a positive drug test, which has implications for sports participants and also the health of the general population. The implementation of the Consumer Protection Act 68 of 2008 (CPA) could protect consumer rights if it is administered and resourced appropriately. CONCLUSION. The CPA should promote greater levels of policy development, regulatory enforcement, and consumer education of South Africa's supplement industry.
Woman-centred care in childbirth: a concept analysis (Part 1)
(AOSIS OpenJournals, 2013) Maputle, Maria S.; Hiss, Donavon
'Woman-centred care' in childbirth is a process in which a woman makes choices and is involved in and has control over her care and relationship with her midwife. The aim of this paper is to study the concept of woman-centred care through analysis in the context of childbirth. The attributes, antecedents and consequences of this concept are identified, and a model case, a borderline case and a contrary case constructed to achieve conceptual clarity. A concept analysis was undertaken as described by Walker and Avant (2011), with an extensive exploration of domain-specific literature and evidence from various disciplines. It was established from the concept analysis that 'woman-centred care' was complex and experienced individualistically. The analysis indicated that mothers' participation is supposed to be based on a more collaborative relationship and partnership. Participation is exhibited by open communication and the mother's involvement in decision-making, consultation and collaboration with the attending midwife, further characterised by mutual respect and the midwife listening to the mother's views. There is also an exchange of complete and unbiased information, recognition and honouring of cultural diversity and making of informed choices. Through an inductive discovery approach and drawing on inferences, attributes were clustered in an attempt to identify the apparent essence of the concept. From the results of the concept analysis described in this study, the researchers recommend the formulation of criteria that could facilitate implementation and evaluation of woman-centred care and its empirical referents in the context of the Batho Pele principles (Part 2).
Young South African adults perceptions of parent psychological control and antisocial behaviour
(Society for Personality Research (Inc.), 2012) Roman, Nicolette V.; Human, Anja; Hiss, Donavon
We extended prior research by investigating perceptions of parental psychological control as a contributor to young adults’ antisocial behavior in a sample of 382 South African university students aged between 18 and 25 years. Barber’s (1996) measure of parental psychological control and the Youth Self-Report (Achenbach & Edelbrock, 1987) questionnaires were administered for data collection. A positive relationship was found between parental psychological control and the antisocial behavior of young adults. Additionally, the results of the hierarchical regression analysis suggest that maternal psychological control, compared to paternal psychological control, was a stronger predictor of antisocial behavior.

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