Department of Medical BioSciences

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https://hdl.handle.net/10566/76

The department fields specific expertise within the broad research fields of Anatomy, Cardiovascular Physiology, Herbal Sciences, Immunology, Medical Microbiology, Molecular & Cell Biology, Neuroscience, Reproduction, Toxicology and Virology

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Accuracy of magnetic resonance imaging in detecting lumbo-sacral nerve root compromise: A systematic literature review
(BioMed Central, 2016) Tawa, Nassib; Rhoda, Anthea; Diener, Ina
Background: MRI is considered to be the diagnostic tool of choice in diagnosing nerve root compromise among patients presenting with clinical suspicion of lumbo-sacral radiculopathy. There exists controversy among researchers and clinicians regarding the diagnostic utility and accuracy of MRI in detecting nerve root compromise and radiculopathy. This review evaluated 4 primary diagnostic accuracy studies that specifically assessed the accuracy of MRI in detecting nerve root compromise, as established in the current literature. Methods: Eight electronic data bases were searched for relevant articles from inception until January 2014. All primary diagnostic studies which investigated the accuracy of MRI in diagnosing nerve root compromise among patients with low back and referred leg symptoms were screened for inclusion. Qualifying studies were retrieved and independently assessed for methodological quality using the 'Quality Assessment of Diagnostic tests Accuracy Studies' criteria. Results: Four studies qualified for inclusion in this review. The sensitivity of MRI in detecting lumbar nerve root compromise was very low at 0.25 (95 % CI) while the specificity was relatively high at 0.92 (95 % CI). Conclusions: There is lack of sufficient high quality scientific evidence in support or against the use of MRI in diagnosing nerve root compression and radiculopathy. Therefore, clinicians should always correlate the findings of MRI with the patients' medical history and clinical presentation in clinical decision making.
Accurate automated quantitative imaging of tortoise erythrocytes using the NIS image analysis system
(Taylor & Francis, 2013) Walton, S.; Hofmeyr, Margaretha D.; van der Horst, Gerhard
The standard method for assessing blood cell characteristics using an ocular micrometer is time-consuming and limited. We used the Nikon NIS Elements imaging software and May-Grünwald-Giemsa staining to determine whether automated image analysis is suitable for rapid and accurate quantitative morphometry of erythrocytes. Blood was collected during four seasons from 126 geometric tortoises and the blood smears were evaluated for cell (C) and nuclear (N) characteristics of the erythrocytes. We measured area, length (L), width (W), perimeter, elongation and pixelation intensity, and calculated L/W and N/C areas. Erythrocyte size differed among cohorts; females, the larger sex, had smaller erythrocytes than either males or juveniles. Males had more elongated erythrocytes than females and erythrocytes of adults were more elongated than those of juveniles. Erythrocyte size and shape influence the efficiency of gas exchange owing to surface area to volume ratios, which are greater for small, elongated cells than for large, round cells. The high N/C ratio and low pixelation intensities of males and juveniles indicate that they may have had more immature erythrocytes in their circulation than females. The use of pixelation intensity to indicate the presence of immature erythrocytes was validated by seasonal differences that corresponded to the biology of the tortoises. Pixelation intensity was lowest in winter. We found that automated image analysis is a rapid and reliable method for determining cell size and shape, and it offers the potential for distinguishing among developmental stages that differ in staining intensity. The method should be useful for rapid health assessments, particularly of threatened species, and for comparative studies among different vertebrates.
Acute toxicity studies of the South African medicinal plant Galenia africana
(Elsevier, 2018) Ng’uni, Tiza; Klaasen, Jeremy A.; Fielding, Burtram C.
Background: Medicinal plants are used by a large proportion of the global population as complementary and alternative medicines. However, little is known about their toxicity. G. africana has been used to treat wounds, coughs and skin diseases and is used in cosmetic formulations such as lotions and shampoos. Methods: The acute oral and dermal toxicity potential of G. africana was analyzed after a single administration of 300 and 2000 mg/kgbw for acute oral toxicity and 2000 mg/kgbw for acute dermal toxicity. Female Sprague- Dawley rats were used for the acute oral toxicity study whereas both male and female Sprague-Dawley rats were used for the acute dermal toxicity study. In the Episkin skin irritation test, the irritation potential of G. africana (concentrate) and G. africana (in-use dilution) extracts were assessed using the Episkin reconstituted human epidermis. In the dermal sensitization study, female CBA/Ca mice were treated with G. africana concentrations of 50, 100 and 200 mg/ml respectively. The vehicle of choice was dimethylformamide which acted as a control. Results: The results of the acute oral and dermal toxicity studies revealed that the median lethal dosage (LD50) for G. africana extract in Sprague-Dawley rats was considered to exceed 2000 mg/kgbw. In the irritation test, the G. africana (concentrate) and G. africana (in-use dilution) extracts were non-irritant on the Episkin reconstituted human epidermis. In the dermal sensitization study, the stimulation index (SI) values for the mice treated with the G. africana extract at concentrations of 50, 100 and 200 mg/ml/kgbw, when compared to the control group, were 1.3, 0.9 and 1.3 respectively. The open application of the extract at the various concentrations did not result in a SI of ≥ 3 in any group. Hence, it did not elicit a hypersensitivity response. Conclusion: These findings demonstrate that the acute toxicity profile for G. africana is acceptable and can subsequently be used for single use in the pharmaceutical and cosmetic industries.
Additive antibacterial activity of naringenin and antibiotic combinations against multidrug resistant Staphylococcus aureus
(Academic Journals, 2015) Ng'uni, Tiza; Mothlalamme, Thato; Daniels, Raymond; Klaasen, Jeremy; Fielding, Burtram C.
Methicillin-resistant Staphylococcus aureus has been causing numerous problems in the health care sector. This is mainly due to its ability to develop resistance to a number of antibiotics used to treat staphylococcal infections. Medicinal plants have been used to treat various ailments over the years and are generating a lot of interest as alternative treatment options. Naringenin is a plant derived flavonoid that possesses antibacterial properties, among others. This study assessed the effect of combinations of naringenin and four antibiotics against two Staphylococcus aureus strains. The minimum inhibitory concentrations were determined using the disk diffusion and broth microdilution assays. In the disk diffusion assay, naringenin did not inhibit bacterial growth, nor did it enhance the antibacterial activity of the antibiotics in the combination study. This was attributed to its slow rate of diffusion out of the disks. On the contrary, in the broth microdilution assay, naringenin exhibited additive effects when combined with the antibiotics (at sub-inhibitory concentrations). These results show the potential of naringenin as an antibacterial agent. Furthermore, the additive effects observed at low naringenin concentrations showed that it can potentially be used in combination with antibiotics against multidrug resistant bacteria.
Alkaloids: Therapeutic Potential against Human Coronaviruses
(MPDI, 2020) Fielding, Burtram Clinton; da Silva Maia Bezerra Filho, Carlos; Ismail, Nasser S.M.
Alkaloids are a class of natural products known to have wide pharmacological activity and have great potential for the development of new drugs to treat a wide array of pathologies. Some alkaloids have antiviral activity and/or have been used as prototypes in the development of synthetic antiviral drugs. In this study, eleven anti-coronavirus alkaloids were identified from the scientific literature and their potential therapeutic value against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is discussed. In this study, in silico studies showed an affinity of the alkaloids for binding to the receptor-binding domain of the SARS-CoV-2 spike protein, putatively preventing it from binding to the host cell. Lastly, several mechanisms for the known anti-coronavirus activity of alkaloids were discussed, showing that the alkaloids are interesting compounds with potential use as bioactive agents against SARS-CoV-2.
Alternative medicine and herbal remedies in the treatment of erectile dysfunction: A systematic review
(Informa UK Limited, trading as Taylor & Francis Group., 2021) Leisegang, Kristian; Finelli, Renata
Objectives: To systematically review and discuss the current evidence from placebo-controlled clinical trials that investigated the use of alternative medicines and herbal remedies in the management of erectile dysfunction (ED). Methods: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)- based systematic review using specific keyword combinations was conducted on the PubMed and Scopus databases. Randomised controlled trials investigating herbal medicine in at least one group and using the International Index of Erectile Function (IIEF) as an outcome in patients primarily diagnosed with ED were included for review. Results: Following the literature search, screening and eligibility analysis, a total of 42 articles were included. The 42 articles were categorised as single herb extractions (n = 14), combination herbal formula (n = 5), combination of herbal formula and non-herbal nutraceuticals (n = 7), non-herbal nutraceuticals (n = 5), acupuncture and moxibustion (n = 2), diet and nutrition (n = 3), exercise (n = 5), and topical treatments (n = 1). Based on the results, Korean ginseng, Pygnogenol and Prelox, Tribulus terrestris, Lepidium meyenii, L-arginine, acupuncture and lifestyle interventions were the more predominantly investigated treatments interventions for ED. Conclusions: Panax ginseng, Pygnogenol, Prelox and Tribulus terrestris have promising evidence as herbal products, alongside L-arginine as a nutritional supplement, for ED based on IIEF outcomes, and warrant further clinical investigation. The mechanisms of action remain unclear, but each of these appears to in part increase nitric oxide synthesis. Importantly, improved diet and exercise should be considered, particularly in patients with obesity or diabetes mellitus.
Amino acids 1055 to 1192 in the S2 Region of severe acute respiratory syndrome Coronavirus S Protein induce neutralizing antibodies: Implications for the development of vaccines and antiviral agents
(American Society for Microbiology, 2005) Keng, Choong-Tat; Zhang, Aihua; Shen, Shuo; Lip, Kuo-Ming; Fielding, Burtram C.; Tan, Timothy H.P.; Chou, Chih-Fong; Loh, Chay Boon; Wang, Sifang; Fu, Jianlin; Yang, Xiaoming; Lim, Seng Gee; Hong, Wanjin; Tan, Yee-Joo
The spike (S) protein of the severe acute respiratory syndrome coronavirus (SARS-CoV) interacts with cellular receptors to mediate membrane fusion, allowing viral entry into host cells; hence it is recognized as the primary target of neutralizing antibodies, and therefore knowledge of antigenic determinants that can elicit neutralizing antibodies could be beneficial for the development of a protective vaccine. Here, we expressed five different fragments of S, covering the entire ectodomain (amino acids 48 to 1192), as glutathione S-transferase fusion proteins in Escherichia coli and used the purified proteins to raise antibodies in rabbits. By Western blot analysis and immunoprecipitation experiments, we showed that all the antibodies are specific and highly sensitive to both the native and denatured forms of the full-length S protein expressed in virus-infected cells and transfected cells, respectively. Indirect immunofluorescence performed on fixed but unpermeabilized cells showed that these antibodies can recognize the mature form of S on the cell surface. All the antibodies were also able to detect the maturation of the 200-kDa form of S to the 210-kDa form by pulse-chase experiments. When the antibodies were tested for their ability to inhibit SARS-CoV propagation in Vero E6 culture, it was found that the anti-S 10 antibody, which was targeted to amino acid residues 1029 to 1192 of S, which include heptad repeat 2, has strong neutralizing activities, suggesting that this region of S carries neutralizing epitopes and is very important for virus entry into cells.
Anaerobes and bacterial vaginosis in pregnancy: virulence factors contributing to vaginal colonisation
(Multidisciplinary Digital Publishing Institute, 2014) Africa, Charlene W.J.; Nel, Janske; Stemmet, Megan C.
The aetiology and pathogenesis of bacterial vaginosis (BV) is unclear but it appears to be associated with factors that disrupt the normal acidity of the vagina thus altering the equilibrium between the normal vaginal microbiota. BV has serious implications for female morbidity, including reports of pelvic inflammatory disease, adverse pregnancy outcomes, increased susceptibility to sexually transmitted infections and infertility. This paper reviewed new available information regarding possible factors contributing to the establishment of the BV vaginal biofilm, examined the proposed role of anaerobic microbial species recently detected by new culture-independent methods and discusses developments related to the effects of BV on human pregnancy. The literature search included Pubmed (NLM), LISTA (EBSCO), and Web of Science. Because of the complexity and diversity of population groups, diagnosis and methodology used, no meta-analysis was performed. Several anaerobic microbial species previously missed in the laboratory diagnosis of BV have been revealed while taking cognisance of newly proposed theories of infection, thereby improving our understanding and knowledge of the complex aetiology and pathogenesis of BV and its perceived role in adverse pregnancy outcomes.
Analyses of spermatozoa surface proteins using different separation techniques
(University of the Western Cape, 2013) Fortuin, Kay Arlene; Henkel, Ralph; Menkveld, Rudolf
Passage of spermatozoa through the female reproductive tract is essential for the regulation of fertilization, ensuring that healthy sperm reach the oocyte. Previous studies were devoted to morphological selection of sperm cells by the cervical mucus. However, research prove that the loss of integrity of the sperm plasma membrane is associated with infertile men, irrespective of their normal semen parameters. This indicates that the sperm plasma membrane plays an important role in fertilization. Further studies indicated that sperm surface proteins assist penetration through the female reproductive tract and would therefore provide useful insight in understanding other factors associated with male infertility. The aim of this project was to determine if there are any differences between sperm surface proteins of fertile donor samples in relation to infertile patient samples using different separation techniques and different detergents. Three different sperm separation techniques were employed, including wash, swim-up (SU) and Percoll density gradient centrifugation (DGC).Parallel to this, the deoxy-ribose nucleic acid (DNA) fragmentation of these cells were analysed for comparison of the extent of DNA damage induced due to different separation techniques used. This provided evidence that the best separation technique is the DGC as it minimises the amount of DNA fragmentation caused. Four different detergents were used in the process of extracting the membrane proteins from spermatozoa, namely sodium dodecyl sulphate (SDS), saponin,cetyl-trimethyl-ammonium bromide (CTAB), and TWEEN-20. The membrane proteins were then separated on a12% SDS poly-acrylamide gel electrophoresis (PAGE), and analysed by Coomassie blue and silver staining techniques as well as densitometry. Due to the different chemical nature of the detergents that extracted different surface proteins, CTAB (cationic) and SDS (anionic) extracted the most because of its strong solubilising abilities as non-ionic detergents. Common proteins that were extracted in donor samples included; 115, 92.5, 89, 61, 55.5, 51.5, 47, 44.5, 43, 38.5, 34 and 28 kDa proteins. In patients, commonly occurring proteins included; 92.5, 74.5, 70, 60.5, 51.5, 50, 44.5, 43, 36, 29.5, and 25.5 kDa proteins. Marked differences were found between membrane proteins extracted from donor samples in comparison to patient samples. Identification of these proteins was done using the SwissProt database and a literature search. Mostly non-genomic progesterone receptors were identified; others included oestrogen receptor, a phosphotyrosyl protein, P34H, equatorial segment protein, mannose lectin receptor, human guanylylcyclase receptor, epididymal protease inhibitor receptor, PH30 and estradiol binding protein. The function of the membrane surface proteins identified in this study plays a vital role in fertilization. A few of these functions include sperm attachment and binding to the oocyte as well as penetration thereof. Others play a role in signalling events such as capacitation, hyperactivation and acrosome reaction. The absence of these proteins in patient sperm possibly accounts for the functional inability to successfully achieve fertilization suggesting that this provides molecular insight to reasons for infertility amongst men. In addition to this, proteins presented by patient samples that were absent in healthy donors may too account for their infertility status. Estradiol binding protein and PH30 are two proteins presented only in patient samples. Their function plays a role in the inhibition of the acrosome reaction and sperm-egg fusion, respectively. In conclusion, these differences in protein expression between fertile donors and patients may form the molecular basis of infertility amongst men and indicates possibilities for novel proteonomic approaches to improve andrological diagnosis in future.
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.
The antihypertentive effect of aqueous extract O Africana leaves
(University of the Western Cape, 2007) Wang, Xu; Dietrich, Daneel; Johnson, Quinton; Dept. of Medical BioSciences; Faculty of Science
The incidence of cardiovascular diseases, including hypertension, is on the increase worldwide. Medicinal plants played an important role in the treatment of hypertension for centuries. Very few scientific studies have, however, been done to validate the use of these phytotherapies. O africana is on of the many phytotherapies that has been use indigenously for years to treat hypertension. The objectives of this study were to determine the most effective does of O africana aqueous extract which will reduce blood pressure; to determine whether chronic administration of O africana can be used to prevent and treat hypertension; to determine whether O africana exert its effects by modulation of the renin-angiotensin system.
Antimicrobial resistant Gram-positive cocci in pregnant mothers with aerobic vaginitis
(Infection Control Africa Network (ICAN), 2016) Kaambo, Eveline; Abrantes, Pedro Miguel dos Santos; McArthur, Carole P.; Africa, Charlene W.J.
The vaginal microbiota of a healthy asymptomatic woman consists of an extensive diversity of anaerobic and aerobic bacterial genera and species dominated by the microaerophilic genus Lactobacillus , known to inhibit the growth of potentially pathogenic non-acid tolerant microorganisms. An imbalance of species within this biofilm may result in endogenous opportunistic infections such as aerobic vaginitis (AV) caused by S. agalactiae and E. faecalis, which have been implicated in neonatal and obstetric sepsis. The prevalence and antimicrobial susceptibility of E. faecalis and S. agalactiae in pregnant women with AV in the Western Cape, South Africa was determined using standard microbiological culture methods and the Sensititre TREK system. AV was detected in 26.13% of the 199 tested pregnant women, with S. agalactiae and E. faecalis isolated from 32 and 20 mothers respectively. S. agalactiae and E. faecalis showed resistance to 12 of the 17 antibiotics tested, including those recommended for prophylaxis according to the CDC guidelines. The resistance of S. agalactiae and E. faecalis to commonly administered antimicrobials highlights the need for alternative treatment regimens for AV during pregnancy to reduce the risk of AV-associated negative pregnancy outcomes.
Antimicrobial-resistant Klebsiella species isolated from free-range chicken samples in an informal settlement
(Termedia Publishing House, 2012) Fielding, Burtram C.; Mnabisa, Amanda; Gouws, Pieter A.; Morris, Thureyah
Sub-therapeutic doses of antimicrobial agents are administered routinely to poultry to aid growth and to prevent disease, with prolonged exposure often resulting in bacterial resistance. Crossover of antibiotic resistant bacteria from poultry to humans poses a risk to human health. In this study, 17 chicken samples collected from a vendor operating in an informal settlement in the Cape Town Metropolitan area, South Africa were screened for antimicrobial-resistant Gram-negative bacilli using the Kirby Bauer disk diffusion assay. In total, six antibiotics were screened: ampicillin, ciprofloxacin, gentamicin, nalidixic acid, tetracycline and trimethoprim. Surprisingly, Klebsiella ozaenae was identified in 96 and K. rhinoscleromatis in 6 (n = 102) of the samples tested. Interestingly, ~40% of the isolated Klebsiella spp. showed multiple resistance to at least three of the six antibiotics tested. Klebsiella ozaenae and K. rhinoscleromatis cause clinical chronic rhinitis and are almost exclusively associated with people living in areas of poor hygiene.
Antioxidant and apoptosis-inhibition potential of Carpobrotus edulis in a model of parkinson’s disease
(African Association of Physiological Sciences, 2018) Enogieru, A.B.; Omoruyi, S.I.; Ekpo, Okobi
Background: Parkinson’s disease (PD) is a neurological disorder resulting from the progressive loss of dopaminergic neurons. There is currently no known cure for PD, thus the search for complementary and alternative medicines capable of halting the degeneration of dopaminergic neurons is plausible. Carpobrotus edulis (CE) is an indigenous plant used in South African traditional medicine used for the treatment of a number of disease conditions including tuberculosis, diabetes mellitus and constipation. It has been suggested that CE contains bioactive compounds which are responsible for its acclaimed medicinal potential. No studies have been reported on the potential benefit of CE to the nervous system. This study was therefore done to evaluate the protective effects of CE against 1-methyl-4-phenylpyridinium (MPP+)-induced toxicity in the dopaminergic SH-SY5Y cell line, as well as its underlying mechanism. Methods: In this study, SH-SY5Y cells were treated with varying concentrations of CE and MPP+ respectively to determine the optimal concentrations of MPP+ and CE for further experiments. Thereafter, SH-SY5Y cells were pre-treated with 30 μM of CE before exposure to 2 mM of MPP+ to induce cellular damage. Cell viability was evaluated using the MTT assay, intracellular reactive oxygen species (ROS) production was determined using flow cytometry and the Hoechst nuclear staining was used to visualize apoptosis. Caspases 3/7 and 9 activity was assessed using commercially available kits. Results: MPP+ treatment induced marked cell viability, increased the number of condensed nuclei and apoptotic cells, increased ROS production, initiated caspase 9 and activated caspase 3/7 in SH-SY5Y cells. The observed effects of MPP+-induced toxicity were attenuated by the pre-treatment of SH-SY5Y cells with 30 μM of CE. Conclusion: The protective effects of CE against MPP+-induced toxicity in SH-SY5Y cells may be attributed to its antioxidant and anti-apoptotic properties.
The antioxidant properties of melatonin during chemical hypoxia and reoxygenation injury in rat ventricular myocytes
(University of the Western Cape, 2000) Salie, Ruduwaan; Dietrich, Daneel; Lochner, Amanda
It is well known that ischaemia chemical hypoxia followed by reperfusion is not always accompanied by recovery of myocardial function and often produces further cell damage (Hearse et al., 1973). This phenomenon commonly referred to as the oxygen paradox (Hearse et al., 1973), is usually characterised by extensive tissue damage and the formation of oxygen free radicals / reactive oxygen species (ROS). As the work on free radicals progressed it became apparent that there is a fine balance between cellular systems that produce free radicals and those that sustain their tolerable levels, to maintain normal cell function (Ferrari et al., 1990). The relative importance of free radicals in the production of irreversible cell damage, as well as the mechanisms involved are not fully understood. Using the rat mode of myocardial infarction followed by reperfusion, many investigators employed various antioxidants / free radical scavengers in various combinations at different stages of hypoxia / reoxygenation with the intention of reducing free radical mediated damage (Meerson et al., 1981; Shlafer et al., 1982; Stewart et al., 1983; Hess et a1., 1983; McCord and Fridovich, 1973). There is also an increasing interest in defining new antioxidants of high potency, low toxicity and good solubility properties in aqueous as well as organic phases. Recently it has been shown that melatonin (n-acetyl-5-methoxytryptamine) has the ability to directly scavenge free radicals (Reiter, 1993) It was therefore the aim of this study, to investigate oxidative stress during chemical hypoxia and reoxygenation in isolated rat ventricular myocytes and to study the antioxidant effects sf 6sl4fsnin, employed at different stages of chemical hypoxia and / or reoxygenation. To reveal the phenomenon of oxidative stress using laser scanning confocal microscopy, myocytes were preloaded with tetramethyl rhodamine (TMRM) together with one of the following fluorophores: (i) dihydric loro fluorescein diacetate (DCDHF) or dihydrorhodaminel23 (DHR) to illustrate the formation of HzOz and / or ROS; or (ii) fluo'3, AM (fluo) to show changes in intracellular free calcium. In superfused myocytes, chemical hypoxia was induced for 12.5 min by the addition of 1.5 mM KCN and 20 mM deoxy glucose to the superfusion buffer followed by 0, 1.5 or 15 min reoxygenation. Cells were also exposed to 27 .5 min chemical hypoxia without reoxygetration. Melatonin (50 pM) was added at different time intervals during the experimental protocol. All the myocytes (untreated and melatonin treated), indicated increased DCDHF but not DHR or fluo fluorescence under control oxygenated conditions (norrroxia). This probably implicate nonanal physiological levels of H2O2 and I or ROS and presumably an intact endogenous antioxidant system, since none of the cells suffered any damage. It was also indicated that melatonin had no effect on H2O2 and / or ROS formation and the viability of any of the cells during normoxia. Exposure of myocytes to chemical hypoxia for 12.5 min caused contracture and damage to 70 - 89 % of cells. This was associated with the generation of H2O2 and/ or ROS, an increase in intracellular calcium but maintenance of membrane potential. Early reoxygenation did not exacerbate or improve the changes observed during chemical hypoxia. Melatonin protected myocytes from hypoxic induced damage and increased cell viability from 20 to 80 % (p<0.05). Melatonin treated cells had reduced levels of ROS and intracellular calcium. The protection conferred by melatonin during exposure of cells to 12.5 min chemical hypoxia disappears if chemical hypoxia is prolonged to 27.5 min. After 27 -5 mn chemical hypoxia > 85 Vo of cells showed marked morphological changes and were considered to be irreversibly damaged. Myocytes indicated increased DCDHF; DHR and fluo fluorescence, implicating increased H2O2 and I or ROS formation and increased intracellular calcium respectively, after 12.5 min chemical hypoxia. However, the application of melatonin, effectively scavenged H2O2 and / or ROS and protected cells only for the first 14.5 min of chemical hypoxia, after which all of the cells indicated increased H2O2 and / or ROS formation, increased intracellular calcium and suffered irreversible damage. Presumably, as chemical hypoxia progressed, the accumulation of H2O2, the formation of ROS and degradation of endogenous antioxidant enzymes transpired, which resulted in damage to the majority of cells by the end of this period.
Aqueous leaf extract of Moringa oleifera reduced intracellular ROS production, DNA fragmentation and acrosome reaction in Human spermatozoa in vitro
(Blackwell Publishing Ltd, 2021) Henkel, R.R; Moichela, F.T; Adefolaju, G.A
The effects of aqueous leaf extract of Moringa oleifera (MO) on human sperm functions and integrity was studied in vitro. Semen was obtained by masturbation after 3–5 days' abstinence from 34 healthy donors in Western Cape, South Africa. Liquefied semen was washed in human tubular fluid supplemented with 1% bovine serum albumin (HTF-BSA;1:5) with 10 min centrifugation at 300 g. Sperm suspensions were subsequently incubated with MO extract (0.625, 6.25, 62.5 and 625 µg/ml) for 1 hr, where HTF-BSA served as control. Sperm motility, vitality, DNA fragmentation, reactive oxygen species production, mitochondrial membrane potential, capacitation and acrosome reaction were assessed. Sperm motility, vitality, mitochondrial membrane potential and capacitation remained unchanged (p >.05). A dose-dependent decrease in sperm reactive oxygen species production (p <.0001), DNA fragmentation (p <.0001) and acrosome reaction (p <.001) was observed. An increase in the percentage of non-capacitated sperm (p <.01) was noted at 625 µg/ml.
Aqueous leaf extract of Sutherlandia frutescens attenuates ROS-induced apoptosis and loss of mitochondrial membrane potential in MPP+-treated SH-SY5Y cells
(University of Benin, 2020) Ekpo, E. O.; Enogieru, Adaze Bijou; Omoruyi, Sylvester Ifeanyi
To investigate the neuroprotective activity of the aqueous extract of Sutherlandia frutescens (SF) against 1-methyl-4-phenylpyridinium (MPP+)-induced toxicity in SH-SY5Y neuroblastoma cells. Methods: SH-SY5Y neuroblastoma cells were divided into different treatment groups: untreated cells, cells treated with MPP+ alone (2 mM), cells pretreated with SF (20 μg) prior to MPP+ (2 mM) treatment and cells treated with SF (20 μg) alone. Twenty-four hours after treatment with MPP+, cell viability was assessed by MTT assay, and changes in cell morphology, intracellular reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP) as well as caspases 3/7 and 9 activities were determined. Results: Treatment of SH-SY5Y cells with MPP+ alone significantly altered cellular morphology, increased ROS production (p = 0.005), induced a significant loss of MMP (p = 0.0011) and caused significant apoptotic cell death, via the activation of caspases 3/7 and 9 (p ≤ 0.0359). These effects were however significantly (p ≤ 0.0359) attenuated in cells pre-treated with the aqueous leaf extract of SF, indicating the possible neuroprotective activity of the SF extract.
Are claudin-5 tight-junction proteins in the blood-brain barrier porous?
(Wolters Kluwer Health, 2020) Fisher, David W.; Mentor, Shireen
The capillaries of the brain are particularly special, as they are not simply conduits for blood, but are primarily responsible to ensure that the neurons function in a strictly regulated homeostatic interstitium. Brain endothelial cells (BECs) express a plethora of ion channels on its luminal and abluminal surfaces, namely: potassium (K+ ) channels (i.e., Kir2 and Kv1), chloride (Cl–)/bicarbonate (HCO3–) channels, as well as a number of ion-solute exchangers (Redzic et al., 2011). These channels essentially prioritize vectorial transendothelial transport, especially for the regulation of K+ flux across the blood-brain barrier (BBB) (Redzic et al., 2011). The differences between the K+ concentration of the brain interstitium and plasma is only 2 mM to 4 mM, but the maintenance of this ionic concentration difference provides a constancy for the neuronal resting membrane potential, their associated firing thresholds and the preservation of a constant level of neuronal excitability.
Aspects of the interrelation between hypertension and insulin resistance
(University of the Western Cape, 2009) Osuafor, Godswill Nwabuisi; Dietrich, Daneel; Dept. of Medical BioSciences; Faculty of Science
Conclusion of this study: These data suggest that 6 weeks of high-fat feeding induces hypertension but does not produce obesity, dyslipidemia and insulin resistance. However, this model may be useful in studying vascular reactivity in hypertension in the absence of insulin resistance.
Aspects of the interrelation between hypertension and insulin resistance: a preliminary study
(2009) Nwabuisi, Osuafor Godswill; Dietrich, Daneel
Background: It is well known that some genetic factors and dietary factors, such as excessive salt intake and excessive caloric intake (resulting in obesity) are risk factors for hypertension. Fifty percent of all hypertensive patients are also insulin resistant. Both hypertension and insulin resistance are again risk factors for other cardiovascular diseases such as atherosclerosis and heart failure. The nature of the association between hypertension and insulin resistance has not been clearly elucidated. Spontaneously hypertensive rats are the ideal models to study the aspects of the relationships between hypertension and insulin resistance. Models of high-fat feeding induce obesity,hypertension and insulin resistance and are thus used extensively to study hypertension because these models closely mimic some of the renal and cardiovascular changes found in human hypertensive patients. The present study was initiated to evaluate if insulin resistance will develop within 6 weeks in a model of high-fat diet induced hypertension and if so, to determine whether captopril will affect the presence of insulin resistance.This model should in future be used to study vascular reactivity to phenylephrine (PHE),acetylcholine (ACH) and sodium nitroprusside (SNP) in hypertensive animals in theabsence or presence of insulin resistance and in normotensive insulin resistant animals. Methods: In a series of experiments, rats were divided into four groups that received different treatments: (i) laboratory pellets, (ii) high-fat diet, (iii) high-fat diet plus captopril and (iv) high-fat diet plus vehicle. Body weight was measured weekly for 6 weeks. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured every week during the 6-weeks feeding period by the tail cuff method using a two channel computerized non-invasive system from Kent Scientific Corporation, USA.m Intraperitonealy glucose tolerance tests (IPGTTs) were performed at week 3 and week 6.After 6 weeks, and after an overnight fast, the plasma lipid profile was determined using a portable CardiochekTM blood test system. Fasting plasma insulin was determined using an immunoenzymatic assay for the in vitro quantitative measurement of rat insulin (INS) in serum and plasma. Insulin sensitivity was estimated by the quantitative insulin sensitivity check index (QUICKI) using the fasting plasma insulin and fasting glucose levels. After week 6 on the high-fat diet, thoracic aortae from the control and high-fat fed(HFD) animals were excised and vascular response to PHE, ACH and SNP were assessed in intact and denuded endothelium.Result: High-fat feeding did not cause a significant increase in body weight. High-fat feeding significantly increased systolic blood pressure from 125±2.1 mmHg in control animals to 155±5.9 mmHg in the HFD group (P < 0.05) and 158±5.6 mmHg in the HFDV group (P < 0.05). Diastolic blood pressure was increased from 86±2.8 mmHg in the control group to 117±2.5 mmHg in the HFD group (P < 0.05) and 113±3.4 mmHg in the HFDV group (P < 0.05). Visceral fat was increased from 0.8±0.1g in the control group to 3.1±0.6 g in the HFD group and 3.8±0.6 g in the HFDV group. IPGTTs performed at weeks 3 and 6 respectively did not differ significantly from the control group as evidenced from the AUC’s at weeks 3 and 6 respectively. High-fat feeding had no significant effects on blood cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) values or and fasting plasma insulin levels. The KCl induced contraction in both aortic rings with intact and denuded endothelium did not differ significantly between the control and HFD groups (P= 0.4 and 0.8) respectively. The contraction mediated by KCl in aortic rings with intact and denuded endothelium from the control or HFD groups also did not differ significantly(control: intact vs denuded, P = 0.2; HFD: intact vs denuded, P = 1). Dose responsecurves(1-10 μM) to PHE indicated slightly stronger contractions in the high-fat fed animals at submaximal doses tested. The maximum contraction achieved was however the same (94±19% and 99±2.6% relative to KCl induced contraction, in the control and HFD group respectively, P<0.05). Relaxation responses to ACH and SNP represent preliminary data.Conclusion: These data suggest that 6 weeks of high-fat feeding induces hypertension but does not produce obesity, dyslipidemia and insulin resistance. However, this model may be useful in studying vascular reactivity in hypertension in the absence of insulin resistance.

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