Browsing by Author "Smith, Carine"

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    Ageing-associated oxidative stress and inflammation are alleviated by products from grapes
    (Hindawi, 2016) Petersen, K. S.; Smith, Carine
    Advanced age is associated with increased incidence of a variety of chronic disease states which share oxidative stress and inflammation as causative role players. Furthermore, data point to a role for both cumulative oxidative stress and low grade inflammation in the normal ageing process, independently of disease. Therefore, arguably the best route with which to address premature ageing, aswell as age-associated diseases such as diabetes, cardiovascular disease, and dementia, is preventative medicine aimed at modulation of these two responses, which are intricately interlinked. In this review, we provide a detailed account of the literature on the communication of these systems in the context of ageing, but with inclusion of relevant data obtained in other models. In doing so, we attempted to more clearly elucidate or identify the most probable cellular or molecular targets for preventative intervention. In addition, given the absence of a clear pharmaceutical solution in this context, together with the everincreasing consumer bias for natural medicine, we provide an overview of the literature on grape (Vitis vinifera) derived products, for which beneficial effects are consistently reported in the context of both oxidative stress and inflammation.
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    Anxiety : an overlooked confounder in the characterisation of chronic stress-related conditions?
    (Public Library of Science, 2020-04-16) Viljoen, Monet; Benecke, Rohan M.; Martin, Lindi; Adams, Rozanne C. M.; Seedat, Soraya; Smith, Carine
    Although anxiety disorders are among the most prevalent of psychiatric disorders, childhood trauma-related studies seldom consider anxiety proneness as distinct aetiological contributor. We aimed to distinguish between trauma- and anxiety-associated physiological profiles. South African adolescent volunteers were categorised for trauma exposure (CTQ, mean score 39±11) and anxiety proneness (AP)(CASI, mean score 37±7, STAI-T, mean score 41±8). Circulating hormone and leukocyte glucocorticoid receptor levels, as well as leukocyte functional capacity, were assessed. AP was associated with lower DHEAs (P<0.05) and higher leukocyte GR expression (P<0.05). DHEAs was also negatively correlated with anxiety sensitivity (CASI, P<0.05). In conclusion, AP may have more predictive power than trauma in terms of health profile. Increased glucocorticoid sensitivity previously reported after trauma, may be a unique function of anxiety and not trauma exposure per se. DHEAs concentration was identified as potentially useful marker for monitoring progressive changes in HPA-axis sensitivity and correlated with psychological measures of anxiety.
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    C-reactive protein is elevated only in high creatine kinase responders to muscle damaging exercise
    (Frontiers Media, 2017-02-11) Isaacs, Ashwin W.; Macaluso, Filippo; Smith, Carine; Myburgh, Kathryn H.; Seelaender, Marilia
    The purpose of this study was to investigate if exertional rhabdomyolysis induced by an acute bout of plyometric exercise in untrained individuals was associated with histological characteristics of skeletal muscle, creatine kinase (CK) polymorphism or secondary damage. Twenty-six healthy male untrained individuals completed a bout of plyometric exercise (10 sets of 10 maximal squat jumps, with each standardized to achieve at least 95% of individual maximal jump height). Blood samples were taken, and perceived pain was scored immediately before the exercise intervention and 6 h, 1, 2, and 3 days post-intervention. Muscle biopsies were collected 9 or 4 days before (baseline) and 3 days after plyometric jumps. Subjects were divided into two groups, high (n = 10) and low responders (n = 16), based on a cut-off limit for exertional rhabdomyolysis of peak CK activity ≥ 1000 U/L in any post-exercise blood sample. Perceived pain was more severe assessed in squat than standing position. Low responders perceived more pain at 6 h and 1 day, while high responders perceived more pain than low responders on days three and four after exercise; structural (dystrophin staining) and ultra-structural (transmission electron microscopy) analysis of muscle fibers revealed no baseline pathology; damage was evident in all individuals in both groups, with no difference between high and low responders in either damage or fiber type proportion. High responders had significantly higher total white blood cell and neutrophil counts 6 h and significantly higher C-reactive protein (CRP) 6 h and days one and two after exercise compared to low responders. High responders had significantly greater muscle myeloperoxidase (MPO) levels in baseline and 3 day post-exercise biopsies compared to baseline of low responders. MLCK C49T single polymorphism was present in 26% of volunteers, whose CK responses were not higher than those with MLCK CC or CT genotype. In conclusion, perceived pain is more effectively assessed with potentially affected muscle under eccentric strain, even if static. High CK responders also have pronounced CRP responses to unaccustomed plyometric exercise intervention. Exertional rhabdomyolysis after unaccustomed eccentric exercise may be related to underlying inability to resolve intramuscular MPO.
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    Chronic prosopis glandulosa treatment blunts neutrophil infiltration and enhances muscle repair after contusion injury
    (MDPI, 2015-01) George, Cindy; Smith, Carine; Isaacs, Ashwin W.; Huisamen, Barbara
    The current treatment options for soft tissue injuries remain suboptimal and often result in delayed/incomplete recovery of damaged muscle. The current study aimed to evaluate the effects of oral Prosopis glandulosa treatment on inflammation and regeneration in skeletal muscle after contusion injury, in comparison to a conventional treatment. The gastrocnemius muscle of rats was subjected to mass-drop injury and muscle samples collected after 1-, 3 h, 1- and 7 days post-injury. Rats were treated with P. glandulosa (100 mg/kg/day) either for 8 weeks prior to injury (up until day 7 post-injury), only post-injury, or with topically applied diclofenac post-injury (0.57 mg/kg). Neutrophil (His48-positive) and macrophage (F4/80-positive) infiltration was assessed by means of immunohistochemistry. Indicators of muscle satellite cell proliferation (ADAM12) and regeneration (desmin) were used to evaluate muscle repair. Chronic P. glandulosa and diclofenac treatment (p < 0.0001) was associated with suppression of the neutrophil response to contusion injury, however only chronic P. glandulosa treatment facilitated more effective muscle recovery (increased ADAM12 (p < 0.05) and desmin (p < 0.001) expression), while diclofenac treatment had inhibitory effects on repair, despite effective inhibition of neutrophil response. Data indicates that P. glandulosa treatment results in more effective muscle repair after contusion.
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    Endocrine and immune effects of dexamethasone in unilateral total knee replacement
    (SAGE Publications, 2006) Smith, Carine; Erasmus, P. J.; Myburgh, K. H.
    The effect of acute pre-surgery dexamethasone treatment on the inflammatory immune and endocrine responses to orthopaedic surgery was investigated. Whole blood samples were obtained before and 5 days after surgery for immune analysis, and serum was obtained before and 6 h, 3 days and 5 days after surgery for endocrine assessment. Dexamethasone did not affect the post-surgery granulocyte response, but inhibited the increase in monocyte count (an average increase of 38.5% was seen in the control group). Peak C-reactive protein concentration (3 days after surgery) was 51.4% lower in the dexamethasone group than in the control group. Dexamethasone had a major effect on cortisol concentrations and the cortisol:testosterone and cortisol: dehydroepiandrosterone ratios, but no effect on anabolic hormone concentrations. In conclusion, acute pre-surgery dexamethasone reatment may have beneficial effects in the post-surgery period, by limiting the extent of systemic inflammation and the cortisol response.
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    Evaluation of a nisin-eluting nanofiber scaffold to treat Staphylococcus aureus-induced skin infections in mice
    (American Society for Microbiology, 2013-08) Heunis, Tiaan D. J.; Smith, Carine; Dicks, Leon Milner Theodore, 1961-
    Staphylococcus aureus is a virulent pathogen and a major causative agent of superficial and invasive skin and soft tissue infections (SSSTIs). Antibiotic resistance in S. aureus, among other bacterial pathogens, has rapidly increased, and this is placing an enormous burden on the health care sector and has serious implications for infected individuals, especially immunocompromised patients. Alternative treatments thus need to be explored to continue to successfully treat infections caused by S. aureus, including antibiotic-resistant strains of S. aureus. In this study, an antimicrobial nanofiber wound dressing was generated by electrospinning nisin (Nisaplin) into poly(ethylene oxide) and poly(d,l-lactide) (50:50) blend nanofibers. Active nisin diffused from the nanofiber wound dressings for at least 4 days in vitro, as shown by consecutive transfers onto plates seeded with strains of methicillin-resistant S. aureus (MRSA). The nisin-containing nanofiber wound dressings significantly reduced S. aureus Xen 36 bioluminescence in vivo and viable cell numbers in a murine excisional skin infection model. The bacterial burden of wounds treated with nisin-containing nanofiber wound dressings was 4.3 × 102 CFU/wound, whereas wounds treated with control nanofiber wound dressings had 2.2 × 107 CFU/wound on the last day of the trial (day 7). Furthermore, the wound dressings stimulated wound closure of excisional wounds, and no adverse effects were observed by histological analysis. Nisin-containing nanofiber wound dressings have the potential to treat S. aureus skin infections and to potentially accelerate wound healing of excisional wounds.
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    Exercise, stress and immune system functional responses
    (Stellenbosch : University of Stellenbosch, 2004-12) Smith, Carine; Myburgh, Kathryn H.; University of Stellenbosch. Faculty of Science. Dept. of Physiological Sciences.
    ENGLISH ABSTRACT: Stress related to chronic exercise affects both the immune and endocrine systems, but there are still many issues that are poorly understood, particularly effects of stress on the functional capacity of immune cells. This thesis probed some of these issues using physiological models of physical and psychological stress. Both exercise training stress and chronic psychological stress in human subjects were shown to result in an up-regulation of spontaneous reactivity of white blood cells in vitro, using two different assays, namely a) a peripheral blood mononuclear cell (PBMC) culture assay measuring immune cell responsiveness and b) a relatively new flow cytometry technique for assessing activation status of cells by their expression of the surface marker CD69, in a lymphocyte subpopulation-specific manner. An up-regulation of immune cell activation in the absence of an additional stressor was associated with a decreased capacity to mount a response to a subsequent mitogen stimulus in vitro after chronic psychological stress and acute, extreme exercise stress. Another novel finding was that cortisol high-responders to chronic psychological stress exhibited a higher spontaneous reactivity of both CD4+ and CD8+ lymphocytes when compared to cortisol low-responders. This result indicates that chronic exposure to cortisol may decrease its usual inhibitory effect on spontaneous T lymphocyte responsiveness. After optimisation of an animal model of mild, psychological stress, we demonstrated (using an IL-6 antibody) that IL-6 is necessary for a full-blown cortisol response to chronic, intermittent mild stress. Results also suggest that IL-6 plays a role in regulation of its own secretion by PBMCs in response to a stressor, by maintaining the production of IL-1β in the face of stress. Basal serum corticosterone concentration was shown to be the main determinant of the magnitude of mitogen-stimulated PBMC secretion of IL-6 in vitro in the stress-free controls. However, after blocking of IL-6 in vivo, IL-1β was identified as a major regulator of IL-6 secretion by mitogen-stimulated PBMCs in vitro, independently of the presence or absence of stress. The implications of these novel findings are that proinflammatory cytokines are sensitively regulated during mild stress.Mean serum cortisol concentration at rest was not a useful tool to assess chronic exercise stress after training intervention. However, classification of athletes at baseline into two groups according to their resting serum cortisol concentration illustrated two distinct patterns for the responses of both cortisol and the cortisol:testosterone ratio to chronic stress. These studies on the effects of chronic stress on parameters of the endocrine stress-axis and the immune system led to the following main conclusions: a) chronic exposure to cortisol results in a decreased inhibition of spontaneous immune cell activity at rest, b) this increased spontaneous activation of immune cells at rest in the absence of a stressor, is associated with a suppression of immune capacity to respond to a subsequent challenge, c) the latter finding is not evident under stress-free conditions where cortisol promoted immune cell IL-6 secretion, and d) IL- 1β and IL-6 are involved in the regulation of each others’ secretion.
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    Gender differences in metabolic risk factor prevalence in a South African student population
    (Clinics Cardiv Publishing, 2009-06) Smith, Carine; Essop, M. Faadiel
    We determined selected risk factors for the metabolic syndrome and assessed the metabolic risk status (using IDF criteria) of third-year physiology students at Stellenbosch University (88 males and 178 females). Outcome measures included anthropometry [body mass index (BMI), waist circumference, waist-to-hip ratio], blood pressure (BP), resting pulse rate, and fasting blood glucose, total cholesterol and triglyceride levels. In addition, students completed a lifestyle questionnaire. A number of gender-based differences were found, with male students displaying a greater incidence of risk factors for the metabolic syndrome: 6% of males versus 3% of females displayed a cluster of three risk factors. Twenty-five per cent of female students (but only 14% of males) exhibited waist circumferences above the accepted range, which was positively correlated, for males and females, with both systolic and diastolic BP, and in females only, also with total cholesterol levels. Male students on average exercised more than their female counterparts, but also exhibited poorer eating habits. Average blood triglyceride levels for both male and female students exceeded the accepted threshold (1.85 ± 1.62 mmol/l and 2.15 ± 1.79 mmol/l, respectively). We concluded that metabolic risk factors were evident in a much younger population than commonly expected. Moreover, the gender-specific differences observed may impact on future risk assessment and preventative measures adopted.
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    Harnessing Macrophages for Controlled-Release Drug Delivery : lessons From Microbes
    (Frontiers Media, 2019) Visser, Johan Georg; Du Preez Van Staden, Anton; Smith, Carine
    With the effectiveness of therapeutic agents ever decreasing and the increased incidence of multi-drug resistant pathogens, there is a clear need for administration of more potent, potentially more toxic, drugs. Alternatively, biopharmaceuticals may hold potential but require specialized protection from premature in vivo degradation. Thus, a paralleled need for specialized drug delivery systems has arisen. Although cell-mediated drug delivery is not a completely novel concept, the few applications described to date are not yet ready for in vivo application, for various reasons such as drug-induced carrier cell death, limited control over the site and timing of drug release and/or drug degradation by the host immune system. Here, we present our hypothesis for a new drug delivery system, which aims to negate these limitations. We propose transport of nanoparticle-encapsulated drugs inside autologous macrophages polarized to M1 phenotype for high mobility and treated to induce transient phagosome maturation arrest. In addition, we propose a significant shift of existing paradigms in the study of host-microbe interactions, in order to study microbial host immune evasion and dissemination patterns for their therapeutic utilization in the context of drug delivery. We describe a system in which microbial strategies may be adopted to facilitate absolute control over drug delivery, and without sacrificing the host carrier cells. We provide a comprehensive summary of the lessons we can learn from microbes in the context of drug delivery and discuss their feasibility for in vivo therapeutic application. We then describe our proposed “synthetic microbe drug delivery system” in detail. In our opinion, this multidisciplinary approach may hold the solution to effective, controlled drug delivery.
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    In utero exposure to maternal chronic inflammation transfers a pro-inflammatory profile to generation F2 via sex-specific mechanisms
    (Frontiers Media, 2020) Adams, Rozanne Charlene McChary; Smith, Carine
    Generational transfer of maladaptations in offspring have been reported to persist for multiple generations in conditions of chronic inflammation, metabolic and psychological stress. Thus, the current study aimed to expand our understanding of the nature, potential sex specificity, and transgenerational plasticity of inflammatory maladaptations resulting from maternal chronic inflammation. Briefly, F1 and F2 generations of offspring from C57/BL/6 dams exposed to a modified maternal periconception systemic inflammation (MSPI) protocol were profiled in terms of leukocyte and splenocyte counts and cytokine responses, as well as glucocorticoid sensitivity. Overall, F1 male and female LPS groups presented with glucocorticoid hypersensitivity (with elevated corticosterone and increased leukocyte glucocorticoid receptor levels) along with a pro-inflammatory phenotype, which carried over to the F2 generation. The transfer of inflammatory and glucocorticoid responsiveness from F1 to F2 is evident, with heritability of this phenotype in F2. The findings suggest that maternal (F0) perinatal chronic inflammation resulted in glucocorticoid dysregulation and a resultant pro-inflammatory phenotype, which is transferred in the maternal lineage but seems to affect male offspring to a greater extent. Of further interest, upregulation of IL-1β cytokine responses is reported in female offspring only. The cumulative maladaptation reported in F2 offspring when both F1 parents were affected by maternal LPS exposure is suggestive of immune senescence. Given the potential impact of current results and the lack of sex-specific investigations, more research in this context is urgently required.
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    Influence of lifestyle choices on metabolic risk has distinct gender and age differences
    (Medknow Publications, 2014) Smith, Carine; Essop, Mogammad Faadiel
    Background and Aim: We aimed to determine the incidence of metabolic syndrome risk factors in young and older university campus population. The infl uence of life-style choices on the physiological risk profi le was also assessed. Methods: For this cross-sectional study, 335 volunteers were recruited from the main campus of Stellenbosch University in the Western Cape, South Africa. Complete data sets were available for 200 subjects (older males n = 35; older females n = 53; young males n = 27 and young females n = 85). Venous blood samples were collected and analyzed for fasting levels of glucose, triglycerides (TG) and total cholesterol. In addition, height, body mass, waist and hip circumferences as well as resting pulse rate and blood pressure (BP), were determined and body mass index was calculated. Subjects also completed a questionnaire on life-style choices. Results: Central obesity and high BP was the major risk factors contributing to metabolic risk in the older population, while increased fasting TG level was the most common risk factor in young females. Gender differences in the young population included relatively higher cholesterol in females and higher BP in males. Although younger males consumed fast food more often than older males, the older population consumed signifi cantly more alcohol and exercised signifi cantly less. Conclusion: We conclude that different generations and gender difference may have different etiologies for metabolic risk. Therefore, the preventative education on metabolic risk and monitoring of disease progression should be optimized for individual groups and revised regularly in order to accommodate these differences
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    Inhibition of corticosteroid-binding globulin gene expression by glucocorticoids involves C/EBPβ
    (2014-10) Verhoog, Nicolette; Allie-Reid, Fatima; Vanden Berghe, Wim; Smith, Carine; Haegeman, Guy; Hapgood, Janet; Louw, Ann
    Corticosteroid-binding globulin (CBG), a negative acute phase protein produced primarily in the liver, is responsible for the transport of glucocorticoids (GCs). It also modulates the bioavailability of GCs, as only free or unbound steroids are biologically active. Fluctuations in CBG levels therefore can directly affect GC bioavailability. This study investigates the molecular mechanism whereby GCs inhibit the expression of CBG. GCs regulate gene expression via the glucocorticoid receptor (GR), which either directly binds to DNA or acts indirectly via tethering to other DNA-bound transcription factors. Although no GC-response elements (GRE) are present in the Cbg promoter, putative binding sites for C/EBPβ, able to tether to the GR, as well as HNF3α involved in GR signaling, are present. C/EBPβ, but not HNF3α, was identified as an important mediator of DEX-mediated inhibition of Cbg promoter activity by using specific deletion and mutant promoter reporter constructs of Cbg. Furthermore, knockdown of C/EBPβ protein expression reduced DEX-induced repression of CBG mRNA, confirming C/EBPβ’s involvement in GC-mediated CBG repression. Chromatin immunoprecipitation (ChIP) after DEX treatment indicated increased co-recruitment of C/EBPβ and GR to the Cbg promoter, while C/EBPβ knockdown prevented GR recruitment. Together, the results suggest that DEX repression of CBG involves tethering of the GR to C/EBPβ.
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    Interplay of the inflammatory and stress systems in a hepatic cell line : interactions between glucocorticoid receptor agonists and interleukin-6
    (HighWire Press, 2010-11) Visser, Koch; Smith, Carine; Louw, Ann
    The liver plays an important role in inflammation and stress by producing the acute phase proteins (APPs) required for resolution of inflammation as well as by delivering systemic glucose, through gluconeogenesis, required to fuel the stress response. Disruption of the interplay between interleukin 6 (IL-6) and glucocorticoids (GCs), the peripheral mediators of inflammation and stress, respectively, maylead to side-effects associated with the pharmacological use of GCs.Thecurrent study investigated the interplay between IL-6 and GCs in a hepatoma cell line (BWTG3) at protein (protein activity assays, Western blotting, and ELISA) andmRNA(qPCR) levels. Specifically, the action of dexamethasone (Dex), a known antiinflammatory drug and glucocorticoid receptor (GR) agonist, is compared to that of Compound A (CpdA), a selective glucocorticoid receptor agonist (SEGRA). CpdA, like IL-6, but unlike Dex, increases GR binding and decreases the metabolic enzymes, tyrosine aminotransferase, phosphoenolpyruvate carboxykinase, andgammaglutamyltransferase, at protein ormRNAlevel. Like Dex, both CpdA and IL-6 increase the positive APPs, serum amyloid A and C-reactive protein, and decrease the negative APP, corticosteroid binding globulin. The study shows that the GC, Dex, and IL-6 generally have divergent effects on the GR and metabolic enzymes, while their functions are convergent on the APPs. In contrast to Dex,CpdAhas effects convergent to that of IL-6onthe GR, metabolic enzymes,and APPs. Thus these findings suggest that CpdA, like Dex, modulates APPs, leading to effective control of inflammation, while, in contrast to Dex, it is less likely to lead to GC-induced side-effects.
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    Lactobacillus equigenerosi strain Le1 invades equine epithelial cells
    (American Society for Microbiology, 2012) Botha, Marlie; Botes, Marelize; Loos, Ben; Smith, Carine; Dicks, Leon Milner Theodore, 1961-
    Lactobacillus equigenerosi strain Le1, a natural inhabitant of the equine gastrointestinal tract, survived pH 3.0 and incubation in the presence of 1.5% (wt/vol) bile salts for at least 2 h. Strain Le1 showed 8% cell surface hydrophobicity, 60% auto-aggregation, and 47% coaggregation with Clostridium difficile C6. Only 1% of the cells adhered to viable buccal epithelial cells and invaded the cells within 20 min after contact. Preincubation of strain Le1 in a buffer containing pronase prevented adhesion to viable epithelial cells. Preincubation in a pepsin buffer delayed invasion from 20 min to 1 h. Strain Le1 did not adhere to nonviable epithelial cells. Administration of L. equigenerosi Le1 (1x10 9 CFU per 50 kg body weight) to healthy horses did not increase white blood cell numbers. Differential white blood cell counts and aspartate aminotransferase levels remained constant. Glucose, lactate, cholesterol, and urea levels remained constant during administration with L. equigenerosi Le1 but decreased during the week after administration.
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    Migration of bacteriocins across gastrointestinal epithelial and vascular endothelial cells, as determined using in vitro simulations
    (Nature Research (part of Springer Nature), 2019-08-07) Dreyer, Leane; Smith, Carine; Deane, Shelly M.; Dicks, Leon Milner Theodore, 1961-; Van Staden, Anton D.
    Little is known about the migration of bacteriocins across human cells. In this study, we report on migration of three bacteriocins nisin, plantaricin 423 and bacST4SA across colonic adenocarcinoma (Caco-2) cells and human umbilical vein endothelial cells (HUVECs). Bacteriocins were fluorescently labelled while still maintaining antimicrobial activity. Migration of fluorescently labelled bacteriocins across monolayers was assessed in vitro using transmigration well inserts. After 3 h, 75% of nisin, 85% of plantaricin 423 and 82% of bacST4SA migrated across the Caco-2 cell monolayer. Over the same time span, 88% nisin, 93% plantaricin 423 and 91% bacST4SA migrated across the HUVEC monolayer. The viability of both cell types remained unchanged when exposed to 50 µM of nisin, plantaricin 423 or bacST4SA. The effect of human plasma on bacteriocin activity was also assessed. Activity loss was dependent on bacteriocin type and concentration, with the class-IIa bacteriocins retaining more activity compared to nisin. This is the first report of bacteriocins migrating across simulated gastrointestinal- and vascular-barriers. This study provides some of the first evidence that bacteriocins are capable of crossing the gut-blood-barrier. However, in vivo studies need to be performed to confirm these findings and expand on the role of bacteriocin migration across cell barriers
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    Pre-exercise glutamine supplementation could prevent decreases in postexercise serum glutamine following a single bout of intensive exercise
    (2001) Strauss, Johannes A. de W.; Myburgh, Kathryn H.; Kruger, Annalie; Smith, Carine; Robson, Paula J.
    ENGLISH ABSTRACT: The objective is to determine if glutamine supplementation prior to exercise would cause an increase in serum glutamine concentration, as opposed to supplementation during exercise or in the post-exercise period. The subjects were fourteen female athletes of the local athletic club who volunteered to participate in the study. Design. This was a single-blind cross-over design. A single dose of 5 g L-glutamine, dissolved in 250 ml of a sugar-free orange drink, or a placebo, was given 45 min­ utes before the VO₂max test. Blood samples were col­ lected before supplementation, 45 minutes after supplementation, immediately after the VO₂max test, and 45 minutes into the recovery period. Blood samples were analysed for serum glutamine concentrations, using an enzymatic method with standard reagents (Glutamine / Glutamate Statpack, Sigma Bio Science™). Haematological variables were analysed by means of a Coulter Counter and a differential white blood cell (WBC) count was obtained from a stained (Leishman's stain) blood film. Results. The mean ± standard error of the mean (±SEM) age, mass, height and VO₂max of the subjects were 19.6 ± 0.4 years, 56.6 ± 1.6 kg, 168.6 ± 1.6 cm and 56.1 ± 1.4 ml/kg/min respectively. During the placebo trial the glutamine concentrations, when adjusted for haemoconcentration, decreased from the resting and pre-exercise concentrations of 675 ± 39 µmol/I and 652 ± 45 µmol/I respectively, to 499 ± 38 µmol/I immediately after exercise (P < 0.01). During the recovery period, glutamine concentrations (606 ± 44 µmol/I) returned to levels close to the resting and pre-exercise levels (P > 0.05). During the glutamine trial, pre-exercise concen­ trations of glutamine were raised from 725 ± 30 µmol/I to 1 252 ± 31 µmol/1 (P < 0.01). This increased level of glu­ tamine was maintained throughout the rest of the proto­ col. Following exercise, an expected increase in the absolute WBC count {almost doubled) was observed in both the placebo and glutamine trials (P < 0.01). No other differences in the absolute WBC and WBC-sub­ population counts were observed between trials. Conclusion. We conclude that glutamine supplementa­ tion before exercise could increase serum glutamine concentrations and may thus prevent the fall in glutamine observed during intensive exercise. This may influence WBC function, but has no effect on WBC concentrations.
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    A review : the fate of bacteriocins in the human gastro-intestinal tract : do they cross the gut–blood barrier?
    (Frontiers Media, 2018) Dicks, Leon Millner Theodore, 1961-; Dreyer, Leane; Smith, Carine; Van Staden, Anton D.
    The intestinal barrier, consisting of the vascular endothelium, epithelial cell lining, and mucus layer, covers a surface of about 400 m2. The integrity of the gut wall is sustained by transcellular proteins forming tight junctions between the epithelial cells. Protected by three layers of mucin, the gut wall forms a non-permeable barrier, keeping digestive enzymes and microorganisms within the luminal space, separate from the blood stream. Microorganisms colonizing the gut may produce bacteriocins in an attempt to outcompete pathogens. Production of bacteriocins in a harsh and complex environment such as the gastro-intestinal tract (GIT) may be below minimal inhibitory concentration (MIC) levels. At such low levels, the stability of bacteriocins may be compromised. Despite this, most bacteria in the gut have the ability to produce bacteriocins, distributed throughout the GIT. With most antimicrobial studies being performed in vitro, we know little about the migration of bacteriocins across epithelial barriers. The behavior of bacteriocins in the GIT is studied ex vivo, using models, flow cells, or membranes resembling the gut wall. Furthermore, little is known about the effect bacteriocins have on the immune system. It is generally believed that the peptides will be destroyed by macrophages once they cross the gut wall. Studies done on the survival of neurotherapeutic peptides and their crossing of the brain–blood barrier, along with other studies on small peptides intravenously injected, may provide some answers. In this review, the stability of bacteriocins in the GIT, their effect on gut epithelial cells, and their ability to cross epithelial cells are discussed. These are important questions to address in the light of recent papers advocating the use of bacteriocins as possible alternatives to, or used in combination with, antibiotics.
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    Sutherlandia frutescens may exacerbate HIV-associated neuroinflammation
    (BioMed Central, 2015-07-18) Africa, Luan Dane; Smith, Carine
    Background: Neuroinflammation is central to the aetiology of HIV-associated neurocognitive disorders (HAND) that are prevalent in late stage AIDS. Anti-retroviral (ARV) treatments are rolled out relatively late in the context of neuroinflammatory changes, so that their usefulness in directly preventing HAND is probably limited. It is common practice for HIV+ individuals in developing countries to make use of traditional medicines. One such medicine is Sutherlandia frutescens - commonly consumed as a water infusion. Here its efficacy as an anti-inflammatory modality in this context was investigated in an in vitro co-culture model of the blood–brain barrier (BBB). Methods: Single cultures of human astrocytes (HA), HUVECs and primary human monocytes, as well as co-cultures (BBB), were stimulated with HIV-1 subtype B & C Tat protein and/or HL2/3 cell secretory proteins after pre-treatment with S.frutescens extract. Effects of this pre-treatment on pro-inflammatory cytokine secretion and monocyte migration across the BBB were assessed. Results: In accordance with others, B Tat was more pro-inflammatory than C Tat, validating our model. S.frutescens decreased IL-1β secretion significantly (P < 0.0001), but exacerbated both monocyte chemoattractant protein-1 (P < 0001) – a major role player in HIV-associated neuroinflammation – and CD14+ monocyte infiltration across the BBB (P < 0.01). Conclusions: Current data illustrates that the combined use of HL2/3 cells and the simulated BBB presents an accurate, physiologically relevant in vitro model with which to study neuroinflammation in the context of HIV/AIDS. In addition, our results caution against the use of S.frutescens as anti-inflammatory modality at any stage post-HIV infection.
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    The trace aminergic system : a gender-sensitive therapeutic target for IBS?
    (BioMed Central, 2020-09-28) Pretorius, Lesha; Smith, Carine
    Due to a lack of specific or sensitive biomarkers, drug discovery advances have been limited for individuals suffering from irritable bowel syndrome (IBS). While current therapies provide symptomatic relief, inflammation itself is relatively neglected, despite the presence of chronic immune activation and innate immune system dysfunction. Moreover, considering the microgenderome concept, gender is a significant aetiological risk factor. We believe that we have pinpointed a “missing link” that connects gender, dysbiosis, diet, and inflammation in the context of IBS, which may be manipulated as therapeutic target. The trace aminergic system is conveniently positioned at the interface of the gut microbiome, dietary nutrients and by-products, and mucosal immunity. Almost all leukocyte populations express trace amine associated receptors and significant amounts of trace amines originate from both food and the gut microbiota. Additionally, although IBS-specific data are sparse, existing data supports an interpretation in favour of a gender dependence in trace aminergic signalling. As such, trace aminergic signalling may be altered by fluctuations of especially female reproductive hormones. Utilizing a multidisciplinary approach, this review discusses potential mechanisms of actions, which include hyperreactivity of the immune system and aberrant serotonin signalling, and links outcomes to the symptomology clinically prevalent in IBS. Taken together, it is feasible that the additional level of regulation by the trace aminergic system in IBS has been overlooked, until now. As such, we suggest that components of the trace aminergic system be considered targets for future therapeutic action, with the specific focus of reducing oxidative stress and inflammation.
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    Using rodent models to simulate stress of physiologically relevant severity : when, why and how
    (InTech, Rijeka, Croatia, 2012) Smith, Carine
    Given the demands of modern life, it is no wonder that the concept of stress has become a household topic for discussion. Also in the academic realm the phenomenon which is stress, is topping the charts in terms of research interest. The short term costs as well as the long term maladaptive effects of stress have been a popular topic of research in especially physiology and psychology for the past few decades, ever since Hans Selye defined the term “stress” in 1956 (Selye, 1956). Stress-related chronic disease, such as cardiovascular disease, diabetes and depression, places an ever-increasing burden on society – medically, socially and financially. Therefore, if we are to limit the spread and impact of this “pandemic”, it is imperative to properly manage the effects of stress on our bodies. This of course, is only possible if we have a complete understanding of the body’s response to stress. The response to stress is almost never localised and contained. Rather, a stress response is initiated in response to a local physical (e.g. contusion to skeletal muscle) or mental (e.g. the loss of a loved one) stressor, but always culminates in a wide-spread, systemic response process that affects many organs and systems. Consider for a moment a less complex research model in a different discipline. Metabolic pathways (e.g. the Krebs cycle or glycolysis) can easily be manipulated in cell culture assays using one single cell type at a time, since these pathways (including substrate supply and waste removal systems) are contained in its entirety within each cell. In contrast, with the stress response pathways this is clearly not the case. The stress response is a complex network of events, which is directed via two interlinked pathways, one endocrine (the hypothalamic pituitary adrenal (HPA)-axis) and one neural (the locus coeruleus norepinephrine (LC-NE) or sympatho-adrenal medullary (SAM)- system). While the neural pathway is mainly activated neurally in response to stress perception, leading to the well-known “fight-or-flight” response, the endocrine pathway has many more triggers. Apart from neural activation, the HPA-axis is also activated by a large number of hormones and even chemical messengers, such as interleukin-6, a cytokine and mediator of inflammation, which is known to increase cortisol secretion. A contributing factor to the complexity of the HPA-axis is the fact that cortisol, the main end product of this stress response, has both endocrine and metabolic functions. Although cortisol is commonly known as the “stress hormone” in the context of psychological stress, its main function is actually metabolic – to maintain glucose supply to the brain. Therefore, the HPA-axis is structured not only for activation in response to perceived stress, but also to react to metabolic stimuli. Furthermore, while the stress response should be powerful and fast in an acute stress situation, the response should be controlled and relatively more limited in a situation of chronic stress, to prevent detrimental effects to the organism in the long term. One can appreciate therefore the need for relatively complex signalling networks in this regard, which serves to activate, limit or inhibit the stress response. To achieve this, numerous molecular mechanisms are in place, and react and interact in response to various stress signals. To give just one example, the glucocorticoid receptor, which is present on most cells to enable cortisol’s effect on these cells, is up-regulated in response to acute stress, but down-regulated after a period of chronic stress. Such complexities make the choice of a suitable stress research model both a difficult, and vital one. While some mechanisms, e.g. activation agents of specific adrenal or pituitary cell types, may be elucidated in cell culture, a whole-system model is required in order to assess the net effect of any stressor to these systems. This does not imply that there is no place for ex vivo or in vitro studies in the discipline of stress research, far from it! A large number of cell-based – and more recently organotypic culture-based – studies have contributed substantially to our understanding of specific mechanisms and/or partial pathways relevant to stress. The important point here is that ideally, in vitro work should at some point be followed up by in vivo investigations, in order to test the applicability of results obtained in vitro, to a whole system. The importance of in vivo assessments, and the need for conducting them in a model specifically suitable to answer the question at hand, is clear when one considers the huge number of described animal models in the scientific literature. Apart from more conventional models using genetically “intact” rodents, recent advances in biotechnology have made possible research using non-physiological models such as gene-knock out animals. These animals may be genetically modified to erase the gene coding for a particular protein, so that the researcher may elect to produce animals completely lacking a particular protein of interest (e.g. IL-6 knockout mice), or in some cases lacking it in only one organ or system (e.g. STAT-3 knocked out or “switched off” in skeletal muscle only). These models may be used to shed light on various in vivo mechanisms which could previously not be properly elucidated using the conventional methods. However, these models have their limitations. For example, when doing research on inflammation, an animal in which a proinflammatory cytokine was knocked out, may display increased or decreased basal levels of other pro-inflammatory cytokines, or an altered anti-inflammatory cytokine profile, or even up- or down-regulated cytokine responses on activation, as a spontaneous compensatory mechanism. The resultant net effect of the genetic manipulation therefore may result in a model that is not physiologically accurate, and responses measured may not accurately reflect normal in vivo responses. Furthermore, these compensatory mechanisms and/or the mere absence of an important protein may also result in other – sometimes unanticipated – side-effects (such as severe constipation in IL-6 knockout mice). Apart from being a confounding factor in the intended study, in some cases these undesired outcomes may result in poor health or even shortened life expectancy of the experimental animal, so that it limits the application of such a model even further. Of course, chain-reaction compensatory responses will also limit the extent to which results obtained in such models, may be extrapolated to a (at least genetically) normal situation. Relatively “old-fashioned”, or more conventional methods, when applied optimally, therefore still have an important place in research, both in applied areas such as pharmacology and in areas of basic research. Only when a situation that is physiologically relevant is recreated or simulated, can one realistically assess either the response to a challenge, or the outcome of a remedial intervention. Therefore, in this chapter, I would like to reflect on methods used to simulate a variety of stressors to the body, starting with a variety of models used to simulate psychological stress, ranging in severity from non-extreme (mild) psychological stress to extreme mental trauma. I will also discuss general considerations in picking the appropriate animal model to use, which may determine the difference between success and failure in your research. Details on the various models will be provided, including issues such as repeatability and standardisation. Models will also be discussed in terms of their suitability for different research approaches or objectives, as well as in terms of their limitations. Arguments for and against the use of any particular model will also be illustrated using actual research data.