The effect of synthetic alginate sulfate hydrogels with recombinant PDGF-BB on Wound healing.

OBJECTIVE: Platelet-derived growth factor (PDGF-BB) is an important factor in the regeneration and wound healing. One of the problems is that there is not enough efficiency in the transmission or delivery of such factors in the wound site. In this study, alginate sulfate hydrogel was synthesized with recombinant PDGF-BB growth factor for achieving a quick method in wound healing. METHODS: In this study, Alginate sulfate hydrogel was made by photo-crosslinking method and methacrylate. Its toxicity was evaluated by MTT assay. Transforming growth factor was studied in releasing from synthesized alginate sulfate hydrogels and also, lack of toxicity was confirmed, and hydrogel was made with a recombinant human growth factor. Wounds were created with a diameter of 10 mm on the back of rats in order to check the wound healing. RESULTS: This study showed that alginate sulfate hydrogels-PDGF-BB were faster in wound healing than non-sulfate alginate hydrogels-PDGF-BB. Therefore, the controlled delivery of growth factor system can be a powerful idea for therapeutic applications for wound healing. CONCLUSION: Alginate sulfate hydrogel with recombinant growth factor 4 µg/cm2 (PDGF-BB) was very suitable for wound healing (Tab. 1, Fig. 3, Ref. 34).

Cloning and expression of recombinant human platelet-derived growth factor-BB in Pichia Pink.

The PDGF-BB plays a key role in several pathogenesis diseases and it is believed to be an important mediator for wound healing. The recombinant human PDGF-BB is safe and effective to stimulate the healing of chronic, full thickness and lower extremity diabetic neurotrophic ulcers. In the present study, we attempted to produce a PDGF-BB growth factor and also, evaluate its functionality in cell proliferation in yeast host Pichia pink. Pichia pink yeast was used as a host for evaluation of the rhPDGF-BB expression. The coding sequence of PDGF-BB protein was synthesized after optimization and packed into the pGEM. Recombinant proteins were produced and purified. The construct of pPinkα-HC-pdgf was confirmed by sequence, the PDGF-BB protein was expressed and purified with using a nickel affinity chromatography column and then characterized by SDS-PAGE electrophoresis. The biological activity of PDGF-BB was estimated with using human fibroblast cell line. The measurement of protein concentration was determined by Bradford and human PDGF-BB ELISA kit. Purified rhPDGF-BB showed similar biological activity (as the standard PDGF-BB) and suggested that the recombinant protein has a successful protein expression (as well as considerable biological activity in P. pink host). The exact amount of recombinant PDGF-BB concentrations were measured by specific ELISA test which it was about 30 µg/ml. Our study suggested that efficiency of biological activity of PDGF-BB protein may be related to its conformational similarity with standard type and also, it practically may be important in wound healing and tissue regeneration.

Design and fabrication of a nanofibrous polycaprolactone tubular nerve guide for peripheral nerve tissue engineering using a two-pole electrospinning system.

Nerve guidance conduits are considered to be the new generation of scaffolds designed for nerve disorders. A tubular construct with a highly aligned fibrous structure, mimicking the endoneurium layer surrounding inner axons of a nerve fascicle, is a suitable candidate for a nerve guide. In this paper a new approach for the fabrication of 3D tubular nerve guides is introduced using simulation of a two-pole electrospinning system and describing its mechanism. The structure of this scaffold is then optimized using the Taguchi statistical method and after morphological studies by scanning electron microscopy, the crystallinity, tensile strength and protein adsorption of these highly aligned fibres are investigated, comparing them with semi-aligned and random fibres produced via conventional mandrel electrospinning. Cell attachment, proliferation and migration of PC12 neuronal like cells are studied on highly aligned, semi aligned and random structures, and morphological change and elongation are observed in PC12 cells. The results of these studies suggest that conduits fabricated using two-pole electrospinning are a suitable and promising scaffold for peripheral and even spinal nerve regeneration. This nerve guide has a great potential for further advanced modifications and regeneration in higher levels.

Fabrication of biocompatible titanium scaffolds using space holder technique.

Open-pore titanium scaffolds were fabricated by sintering of compressed mixtures of TiH(1.924) and urea. Spherical and irregular shaped space holders were used to investigate the effect of pore shape on cellular behavior. After removal of the space holder, the shape of the spacers was replicated to the pores. Average diameter of the pores was in the range of 300-600 µm. SEM images showed that titanium hydride resulted in higher surface roughness and larger micro porosities than pure titanium. In vitro evaluations were carried out by using MTT assay, measuring alkaline phosphatase activity and alizarin red staining in flow perfusion bioreactor for cell culture. Observations revealed excellent attachment and proliferation of G-292 cells to the highly porous scaffolds fabricated with titanium hydride and urea of this research.

Expression analysis of loci associated with type 2 diabetes in human tissues.

AIMS/HYPOTHESIS: Genetic mapping has identified over 20 loci contributing to genetic risk of type 2 diabetes. The next step is to identify the genes and mechanisms regulating the contributions of genetic risk to disease. The goal of this study was to evaluate the effect of age, height, weight and risk alleles on expression of candidate genes in diabetes-associated regions in three relevant human tissues. METHODS: We measured transcript abundance for WFS1, KCNJ11, TCF2 (also known as HNF1B), PPARG, HHEX, IDE, CDKAL1, CDKN2A, CDKN2B, IGF2BP2, SLC30A8 and TCF7L2 by quantitative RT-PCR in human pancreas (n = 50), colon (n = 195) and liver (n = 50). Tissue samples were genotyped for single nucleotide polymorphisms (SNPs) associated with type 2 diabetes. The effects of age, height, weight, tissue and SNP on RNA expression were tested by linear modelling. RESULTS: Expression of all genes exhibited tissue bias. Immunohistochemistry confirmed the findings for HHEX, IDE and SLC30A8, which showed strongest tissue-specific mRNA expression bias. Neither age, height nor weight were associated with gene expression. We found no evidence that type 2 diabetes-associated SNPs affect neighbouring gene expression (cis-expression quantitative trait loci) in colon, pancreas and liver. CONCLUSIONS/INTERPRETATION: This study provides new evidence that tissue-type, but not age, height, weight or SNPs in or near candidate genes associated with increased risk of type 2 diabetes are strong contributors to differential gene expression in the genes and tissues examined.

Biocompatibility testing of a new silver-impregnated catheter in vivo.

The purpose of this investigation was to compare the local effects of polyurethane (Tecothane) and silicone tubes with or without silver impregnation in rats. Bacterial colonization or infection of the exit site and/or tunnel were documented and interpreted. All tubes were placed subcutaneously or percutaneously in the neck of 41 Sprague-Dawley rats and guided beneath the dorsal muscles into the peritoneal cavity. The incidence of bacterial abscesses along the implanted tubes was evaluated daily. After 90 days, or earlier if sepsis developed, the animals were killed painlessly and various organs and tissues from the entry site and the catheter tunnel examined histologically. In the group where polyurethane tubes were placed percutaneously, there was no difference in the frequency of abscesses between silver-impregnated and non-impregnated tubes (5/6 with and 5/7 without silver). The only difference noted was in the group with percutaneously placed silicone tubes between those with and without silver. Abscesses only occurred in 2/4 animals in the silver group and in 5/5 animals in the control group. Histological examination showed no difference in either group between infectious and foreign body reactions. Silver particles in subcutaneous, muscle and peritoneal tissue could not be demonstrated.

Continuous plasma resin perfusion for detoxification of methotrexate.

UNLABELLED: Acute renal failure is a rare but very severe side-effect of methotrexate (MTX) treatment requiring extracorporeal detoxification. A new detoxification regime, consisting of a haemodiafiltration (HDF) and continuous plasma resin perfusion (PRP) over anion exchange resin column with high affinity for MTX, was used for treatment of MTX-induced acute renal failure in a 2-year-old boy with medulloblastoma. More than 99% of MTX was removed from plasma by perfusion over the resin column resulting in a marked decrease of MTX plasma half-life. No haematological complications occurred. CONCLUSION: The use of PRP alone or in combination with HDF is a new and effective treatment strategy for extracorporeal detoxification of MTX.

Intermittent administration of furosemide versus continuous infusion in the postoperative management of children following open heart surgery.

OBJECTIVE: To compare the amount of furosemide needed to fulfil defined criteria for renal output if given intermittently or as a continuous infusion and to compare the effect of these two regimens on hemodynamic variables and urine electrolyte concentrations. DESIGN: Prospective randomized study of postoperative hemodynamically stable pediatric cardiac patients. The patients were given furosemide according to the urine output, either as an intermittent bolus injection or as a continuous infusion. SETTING: Pediatric intensive care unit in a university hospital. PATIENTS: The patients were randomly assigned before admission to either the intermittent i.v. or the continuous furosemide i.v. infusion group. MEASUREMENTS AND RESULTS: Demographic and hemodynamic data were recorded for a maximum of 72 h, as were furosemide dose, urine output, and fluid and inotropic drug requirements. Forty-six patients completed the study. Maximal hourly urine output was significantly higher in the intermittent group. A significantly lower dose of furosemide in the intermittent group produced the same 24-h urine volume as in the continuous infusion group. CONCLUSIONS: Intermittent furosemide administration may be recommended in hemodynamically stable postoperative pediatric cardiac patients because of less drug requirement. However, the high maximal urine output may cause hemodynamic problems in patients who depend on high inotropic support.