21 research outputs found
Of Nigerians, albinos, satanists and anecdotes: A critical review of the HSRC report on human trafficking
The deluge of news articles about human trafficking in South Africa, and the media preoccupation with trafficking in the run-up to the 2010 FIFA World Cup, could lead an observer to believe that South Africa is a 'hotbed' of human trafficking. Yet, there are no baseline data about the extent or nature of the problem. The Human Sciences Research Council (HSRC) released a research report in March this year that purports to provide 'the first comprehensive assessment of human trafficking in South Africa.' The report is beset with methodological problems and assumptions. It is based on very little original research. The authors of this review argue that it represents a missed opportunity to provide much needed information about human trafficking in South Africa and fuels sensationalism about human trafficking
Developmental consequences of perinatal cannabis exposure: behavioral and neuroendocrine effects in adult rodents
Cannabis is the most commonly used illicit drug among pregnant women. Since the endocannabinoid system plays a crucial role in brain development, maternal exposure to cannabis derivatives might result in long-lasting neurobehavioral abnormalities in the exposed offspring. It is difficult to detect these effects, and their underlying neurobiological mechanisms, in clinical cohorts, because of their intrinsic methodological and interpretative issues. The present paper reviews relevant rodent studies examining the long-term behavioral consequences of exposure to cannabinoid compounds during pregnancy and/or lactation. Maternal exposure to even low doses of cannabinoid compounds results in atypical locomotor activity, cognitive impairments, altered emotional behavior, and enhanced sensitivity to drugs of abuse in the adult rodent offspring. Some of the observed behavioral abnormalities might be related to alterations in stress hormone levels induced by maternal cannabis exposure. There is increasing evidence from animal studies showing that cannabinoid drugs are neuroteratogens which induce enduring neurobehavioral abnormalities in the exposed offspring. Several preclinical findings reviewed in this paper are in line with clinical studies reporting hyperactivity, cognitive impairments and altered emotionality in humans exposed in utero to cannabis. Conversely, genetic, environmental and social factors could also influence the neurobiological effects of early cannabis exposure in humans
Risks of misinterpretation in the evaluation of the effect of fruit-based drinks in postprandial studies
It has been suggested that some fruit-based drinks (FBD) may delay the onset of postprandial stress, which is involved in the pathogenesis of many diseases. The majority of the studies, which have investigated the effects of FBD on postprandial stress, involved a placebo that was a drink with the same content in sugars or carbohydrates of the FBD, but without the bioactive antioxidant compounds. These studies were aimed more at evaluating the effect of the antioxidants rather than the effect of the FBD as a whole. Only 4 studies compared the effect of FBD with water as control and did not support the hypothesis that FBD could inhibit postprandial dysmetabolism, as well as the studies that compared the effect of orange juice and cola. Overall, the results suggest a complex relationship between postprandial dysmetabolism, inflammation, and oxidative stress. Furthermore, the inflammatory and oxidative stress markers need further analytical validation and normal ranges should be established in order to reach a firm conclusion. Finally, caution should be taken in the interpretation of the effect of FBD in postprandial studies and the reviewed results suggest that dietary recommendations should aim to limit rather than increase sugar-sweetened beverages consumption
Effect of cocoa products and flavanols on platelet aggregation in humans: a systematic review
Previous evidence suggested an active role of cocoa products and flavanols in modulating platelet aggre- 1 gation. However, cocoa flavanols are characterized by a low bioavailability that can deeply affect their presence in biological fluids and raise questions on their biological effect in humans. We performed a sys- tematic search on Medline, Embase, Cochrane and ProQuest databases, until April 2015, on the effect of cocoa products on platelet aggregation in human intervention studies. We identified 13 interventions, of which only five involved repeated administration. Different effects were observed on the basis of the platelet aggregation test used, whereas neither a longer duration of treatment nor a higher dose was associated with a higher inhibition of platelet aggregation. In conclusion, the reviewed results suggest that consumption of cocoa products in bolus administration positively affects platelet aggregation in both healthy subjects and diseased patients. On the other hand, more evidence is required in order to assess
the effect of long-term cocoa product ingestion and to identify the bioactive components involved
Green tea and bone marrow transplantation: from antioxidant activity to enzymatic and multidrug-resistance modulation
Epigallocatechin-3-gallate (EGCG), the main flavonoid of Green Tea (GT), could play an active role in the prevention of oxidative stress related diseases, such as hematological malignancies. Some effects of EGCG are not imputable to the antioxidant activity, but involve modulation of antioxidant enzymes and uric acid (UA) levels. The latter is the major factor responsible of the plasma Non-Enzymatic Antioxidant Capacity (NEAC). However, hyperuricaemia is a frequent clinical feature caused by tumor lysis syndrome or cyclosporine side effects, before and after bone marrow transplantation (BMT). Besides, food-drug interactions could be associated with GT consumption and could have clinical implications.
The molecular mechanisms involved in the redox and drug metabolizing/transporting pathways was discussed with particular reference to the potential role of GT and EGCG in BMT. Moreover, reviewing data on NEAC, isoprostanes, uric acid and various enzymes, from human studies on GT, its extract or EGCG, an increase in NEAC, no effect on isoprostanes and contrasting results on UA and enzymes were observed.
Currently, few and contrasting available evidences suggest caution for GT consumption in BMT patients and more studies are needed in order to better understand the potential impact of EGCG on oxidative stress and metabolizing/transporting systems
Effect on rat arterial blood pressure of chemically generated peroxyl radicals and protection by antioxidants.
Convincing evidence suggests that blood redox changes play a role in the development of various cardiovascular disorders including hypertension. Nutritional antioxidants have been suggested to play a role in cardiovascular disease prevention. In this study, we investigated in vivo changes in rat arterial blood pressure induced by acute exposition to an increased load of peroxyl radicals and by the administration of selected antioxidants after chemically induced oxidative stress. Hydrosoluble and liposoluble peroxyl radicals, generated by 2,2'-azobis-(2-amidinopropane) dihydrochloride and 2,2'-azobis 2,4-di-methylvaleronitrile, induced a dose-dependent decrease in rat blood pressure. All antioxidants tested (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid, vitamin C, glutathione and dithiothreitol) returned peroxyl radical-induced hypotension to normal. Of the various antioxidants tested, glutathione was the most effective in restoring blood pressure after peroxyl radical generation. Treatment of rats with a thiol-chelating agent (N-ethylmaleimide) and an oxidizing agent (5,5'-dithiobis-2-nitrobenzoic) inhibited peroxyl radical-mediated hypotension. Our results suggest that acute exposition to peroxyl radicals have a hypotensive effect on blood pressure and that thiols play an active role in the redox regulation of blood pressure. Other experiments are needed to clarify the role played by oxidative potentials on blood pressure and the mechanism of action of nutritional antioxidants
Interference of flavonoids with fluorescent intracellular probes: methodological implications in the evaluation of the oxidative burst by flow cytometry
The evaluation of oxidative burst is particularly relevant in many pathological and subclinical conditions. Flow cytometry provides quick and accurate measures of the reactive oxygen species production by leukocytes in most situations. However, spurious results, related to probes' efflux may be observed in several instances. Many factors affect the evaluation of the oxidative burst with fluorescent probes that require intracellular deacetylation and could be substrate of the multidrug resistance proteins (MDR). After discussing the implications of the efflux of fluorophores in the normalization strategies in flow cytometry assays, we have pointed out the possible interference of flavonoids with fluorescet probes' staining and signal. We have also reviewed the results from human intervention studies regarding the evaluation of oxidative burst with these probes. In vitro, at concentrations close to post-ingestion circulating levels, some flavonoids and their metabolites could interfere with probes' staining and fluorescence signal through different mechanisms, such as the inhibition of esterases, the modulation of the MDR-mediate efflux of probe and the inhibition of the oxidation of probe. These effects may explain the contrasting results obtained by human intervention studies. Finally, also inflammatory state or the use of drugs substrate of MDR proteins could affect the evaluation of the oxidative burst with intracellular probes
Intestinal motility disorder induced by free radicals: a new model mimicking oxidative stress in gut.
Literature data suggest that the inflamed intestine may be subjected to a considerable oxidative stress. Therefore, the aim of the present study was to simulate the oxidative stress in the gastrointestinal tract and to explore its effect on intestinal motility. This was attained by treating isolated segments from the rabbit jejunum and from the guinea pig ileum with 2,2'-Azobis (2-amidinopropane) dihydrochloride (ABAP), which generates peroxyl radicals by thermal decomposition. Treatment of intestinal segments with ABAP reduced the muscarinic cholinergic response to acetylcholine in both preparations and induced a dose-dependent inhibition of the spontaneous contractions in the jejunum, also in the presence of tetrodotoxin. ABAP was found to inhibit the contractile response induced by BaCl(2) in guinea pig ileum preparations. This effect was not dose-dependent and it was reversed by Bay-K 8644, which activates voltage operated L-type calcium channels. The rapid and reversible effects of ABAP suggest that it might directly affect L-type calcium channels before lipoperoxidation induction. In conclusion, the results of the present study show that ABAP could be a useful tool to simulate early contractility dysfunctions mediated by oxidative stress