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Melatonin prevents the free radical and MADD metabolic profiles induced by antituberculosis drugs in an animal model

Abstract:  The objective was to determine the effect of combined antituberculosis (anti‐TB) drug therapy and an antioxidant, melatonin, on the free radical and organic acid profiles in an experimental rat model. A combined anti‐TB drug, Rifater, consisting of 12.0 mg rifampicin, 0.8 mg isoniazid, and 23.0 mg pyrazinamide and 18.56 μg melatonin/kg body weight per day (corresponding to average physiological human intake) were orally administered to Sprague–Dawley rats. Hydroxyl radical production was monitored by quantifying 2,3‐dihydroxybenzoic acid produced after intraperitonial sodium salicylate injections. Organic acid extractions and gas chromatography‐coupled mass spectrometry analyses were performed on collected urine samples. The results show hydroxyl radicals (P = 0.0019) and organic acids (P‐value range: 0.037 to <0.001), characteristic of a multiple acyl‐CoA dehydrogenase defect (MADD), were elevated with Rifater treatment and these elevations were significantly lowered with melatonin pretreatment (P‐value range: 0.031 to <0.001), probably because of its inherent antioxidant activity. We conclude that hydroxyl radical production and an increased organic acid profile induced by anti‐TB medication indicates inhibition of the electron transport chain. We also conclude that free radicals leading to clinical symptoms associated with an MADD metabolic profile induced by anti‐TB treatment could be alleviated by melatonin intervention.

Perspectives on a South African Tutor/Mentor Program: The Stellenbosch University Experience.

The development, implementation and perpetuation of a student academic and social support system has become an imperative strategy at South African universities. Access to tertiary education has, since 1994, systematically transformed institutions until they represent the demographic profile of the country. Previously disadvantaged groupings (black, coloured, female, handicapped, Indian, mixed ancestry) now frequent lecture halls and campuses, many of whom need additional support mechanisms to enhance their chances of success. This article deals with the University of Stellenbosch experience over a six‐year period and the development of a uniquely African tutor/mentor system which not only serves the student who is most at risk of failing, but also enhances the level of achievement of gifted students, many of whom are traditionally underachievers.

An immunocytochemical profile of the endocrine pancreas using an occlusive duct ligation model.

CONTEXT Ligation of the pancreatic duct, distally to its confluence into the bile duct has been shown to induce endocrine tissue regeneration. The surplus endocrine tissue formed is presumed to be able to replace pathologically and/or experimentally compromised tissue. OBJECTIVE This is a quantitative study on the histology of duct ligated pancreas employing immunocytochemistry and computerised morphometry. INTERVENTIONS Pancreatic duct ligation was performed on 25 groups of six normal Sprague-Dawley rats. Experimental animals were sacrificed at 12-hour intervals from day one to ten post-duct ligation and every 24 hours thereafter to day 14, the pancreas removed, fixed and processed. Six consecutive 3-6 micron serial sections were cut on a rotary hand microtome, floated onto 3-aminopropyl-trimethoxysilan coated slides and alternatively immunocytochemically stained for insulin, glucagon, pancreatic polypeptide and somatostatin. RESULTS Pancreas transformation between days 1/2 and 3 1/2 was characterised by acinar deletion and the appearance of immunoreactive cells for the primary endocrine hormones. Transdifferentiation of existing endocrine tissue saw islet insulin core cells replaced by pancreatic polypeptide- and somatostatin positive cells, glucagon deletion and random appearance of all endocrine cell types within the inter-islet interstitium by day 3 1/2. Days 4 to 14 were characterised by cellular migration and islet reconstruction. CONCLUSIONS To date our laboratory has investigated transplantation of foetal tissue beneath the renal capsule in syngeneic, isogeneic and allogeneic normal and diabetic rats. As pancreatic duct ligation induces the development of surplus endocrine tissue our next step would be to investigate the use of ligated pancreas as a replacement for foetal tissue.

Differentiation and classification of thoracolumbar transitional vertebrae

The literature states that transitional vertebrae at any junction are characterized by features retained from two adjacent regions in the vertebral column. Currently, there is no published literature available that describes the prevalence or morphology of thoracolumbar transitional vertebrae (TLTV). The aim of this study was to identify the qualitative characteristics of transitional vertebrae at the thoracolumbar junction and establish a technique to differentiate the various subtypes that may be found. A selection of vertebral columns from skeletal remains (n = 35) were evaluated in this study. Vertebrae were taken based on features that are atypical for vertebrae in each relative region. The transitional vertebrae were qualitatively identified based on overlapping thoracic and lumbar features of vertebrae at the thoracolumbar junction. The following general overlapping characteristics were observed: aplasia or hypoplasia of the transverse process, irregular orientation on the superior articular process and atypical mammillary bodies. The results show that the most frequent location of the transitional vertebrae was in the thoracic region (f = 23). The second most frequent location was in the lumbar region (f = 10). In two specimens of the selection (f = 2), an additional 13th thoracic vertebra was present which functioned as a transitional vertebra. This study concluded that one can accurately identify the characteristics of transitional vertebrae at the thoracolumbar junction. In addition, the various subtypes can be differentiated according to the region in the vertebral column the vertebra is located in and the relative number of vertebral segments in the adjacent regions of the vertebral column. This provides a qualitative tool for researchers to differentiate the transitional vertebrae from distinctly different typical thoracic or lumbar vertebrae at the thoracolumbar junction.

Mesenchymal cells are required for epithelial duct cell-to-beta cell maturation and function in an injured adult pancreas in the rat

The islet, the endocrine portion of the pancreas - develops from an invagination of the pancreatic duct epithelial cells (PDECs) into the surrounding tissue. The contact of the PDECs with mesenchymal cells (MSCs) may be an essential drive for endocrine cell fate. During pancreatic development, cells that express Neurogenin-3 (Ngn3) biomarker are precursors of insulin- producing beta cells. These precursors have been reported in the neogenesis of islets from adult tissues following the surgical ligation of the main pancreatic duct (PDL). But the capacity of these precursors to induce the appropriate signals to complete the entire neogenesis program has been questioned. We studied the fate of co-culture of PDECs and MSCs from the ligated adult pancreas and established the exact location of adult stem- or progenitor-like cells that give rise to beta cells. PDECs were cultured in direct contact with or without MSCs in serum-containing culture media. The cytomorphology of the cells in co-cultures was determined and the immunocytochemical study of the cells was carried out using anti-Ngn3, anti-insulin and anti-cytokeratin-7 (CK7) antibodies. Both the PDEC/MSC- and PDEC/MSC+ cultures showed out- pocketing from duct epithelium by the end of the second week, which are distinct as cell clusters only in PDEC/MSC+ cells later in week four, exhibiting numerous branching ducts. Co-expression of Ngn3 with insulin was observed in both cultures from the second week. However, characterizations of these Ngn3+ cells in the PDEC/MSC+ culture revealed that these cells also co-expressed a CK7 biomarker. This study provides new evidence of the ductal epithelial nature of beta cells in injured adult pancreata; and that the mesenchymal stromal cells are required to sustain Ngn3 expression for beta cell maturation and function.

Shoulder surgeon and autologous cellular regeneration - From bench to bed: Part one- the link between the human fibroblast, connective tissue disorders and shoulder

The process of autologous cell regeneration (ACR) is a facet of cell therapy and regenerative medicine. It is initiated when activated autologous platelet rich plasma alone (PRP), containing cytokines or growth factors, is injected into the dermis or other structure in order to initiate a regenerative or antiaging process. The recipients resident cells at the target zone are activated by biologically active growth factors, derived from the activated platelets in the PRP through a paracrine effect. The platelet gel that contains the fibrin and clumped platelets, releases growth factors that influences activation of macrophages and stem cells in the recipient site. Tissue regeneration is facilitated by stem cell proliferation and differentiation. The PRP that has sealant and wound healing properties, may shift the wound healing cascade to the left, thereby speeding up tissue regeneration and remodelling by the use of the recipients own plasma. Both the fibroblast and myofibroblast play key roles in the wound healing cascade. The fibroblast, of mesenchymal origin, plays a pivotal role in the formation of the extracellular matrix and deposition of collagen. A failure of organised fibroblast function results in important and disabling disease processes and conditions such as chronic ischaemic heart disease and remodelling of the heart, lung fibrosis, fibromatosis, solar aged-face, keloids, hypertrophic scar formation, nodular fasciitis, inguinal hernia, Dupuytrens disease and scleroderma. More recent additions include frozen shoulder and the captured shoulder. In aesthetic medicine, one of the prime functions of fractional photothermolysis with lasers, intense pulsed light and radiofrequency devices, is to stimulate dermal fibroblast proliferation, by thermal energy thereby increasing collagen deposition which enhances facial rejuvenation. Platelet -rich plasma (REGENLAB PRP, REGENLAB-ACR) possesses unique growth factors that stimulate, fibroblast, keratinocyte and myoblasts ex vivo in tissue culture, allowing three-dimensional cell proliferation within the fibrin gel. PRP can be used as a cell carrier (i.e., keratinocytes, fibroblasts), may enhance cell retention at the point of treatment. REGENKIT is authorized for human use, ISO and CE marked. In this overview fibroblast morphology, tissue culture and cell biology relevant to the shoulder surgeon is reviewed.

Efficiency of Co-Expression of Transcription Factors Pdx1, Ngn3, NeuroD and Pax6 with Insulin: A Statistical Approach

Aim: The objective of this study was to investigate the time related profile and efficiency of co-expression of the homeodomain proteins Pdx1, NeuroD, Ngn3, Pax6 and caspase3 with insulin, and to establish the time periods post PDL optimum for islets transplantation. Study Design/Methods: In this experimental study, immunofluorescent staining procedure was performed on deparaffinized pancreatic duct ligated (PDL) tissues of 78 Sprague-Dawley rats. Quantification of protein coexpression was made using a computerized morphometry. The efficiency of co-expression was arbitrary defined by the value of mean ratio (score without unit) of insulin expression divided by each expression index of the other proteins, occurring within the time interval of 12-24 h post PDL. Statistical tool was used to analyze the efficiency of co-expression of proteins; analysis of variances (one way ANOVA) was used to compare the means of co-expression indexes across the time periods pre- and post PDL. P-values less than 0.05 were considered statistically significant; no post hoc test was done. Results: The curve of insulin expression showed a crossover with that of the co-expression at different time periods pre- and post PDL. The optimal or higher efficiency of co-expression was observed for insulin and Ngn3 co-expression, while a good or medium efficiency was noted for the co-expression of insulin with Pdx1, insulin with NeuroD and insulin with Pax6. Low or weak efficiency was observed for the co-expression of insulin with caspase3. Conclusion: We therefore propose an early islets transplantation using 12-24 h post PDL harvested pancreatic tissues.