Development of approaches to improve the healing following muscle contusion

Muscle injuries are a challenging problem in traumatology, and the most frequent occurrence in sports medicine. Muscle contusions are among the most common muscle injuries. Although this injury is capable of healing, an incomplete functional recovery often occurs, depending on the severity of the blunt trauma. We have developed an animal model of muscle contusion in mice (high energy blunt trauma) and characterized the muscle's ability to heal following this injury using histology and immunohistochemistry to determine the level of muscle regeneration and the development of scar tissue. We have observed a massive muscle regeneration occurring in the first 2 wk postinjury that is subsequently followed by the development of muscle fibrosis. Based on these observations, we propose that the enhancement of muscle growth and regeneration, as well as the prevention of fibrotic development, could be used as approach(es) to improve the healing of muscle injuries. In fact, we have identified three growth factors (bFGF, IGF-1, and NGF) capable of enhancing myoblast proliferation and differentiation in vitro and improving the healing of the injured muscle in vivo. Furthermore, the ability of adenovirus to mediate direct and ex vivo gene transfer of beta-galactosidase into the injured site opens possibilities of delivering an efficient and persistent expression of these growth factors in the injured muscle. These studies should help in the development of strategies to promote efficient muscle healing with complete functional recovery following muscle contusion.     

Experimental nephrolithiasis in rats: the effect of ethylene glycol and vitamin D3 on the induction of renal calcium oxalate crystals

Using ethylene glycol (EG) and vitamin D3 as crystal-inducing diet (CID) in rats, we investigated the effect of the dosage of EG on the generation of chronic calcium oxalate (CaOx) nephrolithiasis. We collected weekly 24 hour urines and measured herein the amount of oxalate, calcium, glycosaminoglycans (GAG's), creatinine, protein, alkaline phosphatase (AP), gamma-glutamyl transpeptidase (gamma-GT), and N-acetyl-beta-glucosaminidase (NAG). The potential of these urines to inhibit crystal growth and agglomeration was also evaluated. After four weeks, the kidneys were screened by histology and radiography for the presence of CaOx crystals and the amount of kidney-associated oxalate was biochemically measured. Using 0.5 vol.% EG, only a part of the rats showed CaOx deposition in the renal cortex and/or medulla, without obvious differences between Wistar and Sprague-Dawley (SD) rats. If a dietary EG concentration of 0.75, 1.0, or 1.5 vol.% was used, the amount of kidney-associated oxalate was proportionally higher and CaOx crystal formation was consistently found in all rats. Most crystals were encountered in the cortex, whereas in the medulla and the papillary region, crystals were only occasionally detected. From these data, we conclude that in the chronic rat model, based on EG and vitamin D3, a consistent deposition of CaOx crystals is obtained using a EG concentration of at least 0.75%.     

Apyrase administration prolongs discordant xenograft survival

Platelet thrombi and vascular inflammation are prominent features of discordant xenograft rejection. The purinergic nucleotides ATP and ADP, which are secreted from platelets and released by injured endothelial cells (EC), are important mediators of these reactions. Quiescent EC express the ectoenzyme ATP-diphosphohydrolase (ATPDase; an apyrase), which exerts an important thromboregulatory function by hydrolyzing both ATP and ADP. We have shown that ATPDase activity is rapidly lost from the surface of the EC following ischemia-reperfusion injury and during xenograft rejection. The aim of this study was to supplement ATPDase activity within xenografts by infusion of soluble apyrases, and thereby validate the importance of local ATPDase activity in the modulation of xenograft rejection. Lewis rats underwent heterotopic cardiac xenografting from guinea pigs and apyrase was administered intravenously (200 U/kg) as a single dose to evaluate effects on hyperacute rejection (HAR). This initial dose was followed by a continuous apyrase infusion (8.0 U/kg/hr) directly into the graft aorta in combination with systemic cobra venom factor (CVF) administration to deplete complement when delayed xenograft rejection (DXR) was studied. Functional apyrase levels in vivo were assessed by the capacity of blood samples taken at the time of surgery and rejection to inhibit platelet aggregation in vitro. Apyrase administration significantly prolonged graft survival in HAR and DXR. Functional assays showed inhibition of platelet aggregation suggesting effective systemic antiaggregatory effects of the administered apyrases. Histologic studies showed that apyrase administration abrogated local platelet aggregation and activation in HAR and DXR. Our data demonstrate that local administration of apyrase prolonged discordant xenograft survival. These observations emphasize the potential importance of purinergic mediators in platelet activation during xenograft rejection.     

Regional mapping of the human platelet-activating factor receptor gene (PTAFR) to 1p35-->p34.3 by fluorescence in situ hybridization

The human platelet-activating factor cell-surface receptor (PTAFR) is a G protein-coupled receptor thought to contribute to many atopic and inflammatory diseases and, perhaps, to the growth of some neoplasms. Exploring the possibility that the PTAFR might be involved in the genetic predisposition to any disease requires knowledge of its chromosomal localization. In this paper we have used a 20-kb human genomic fragment containing the coding sequence of the cloned PTAFR to determine the regional chromosomal localization of the gene. Using fluorescence in situ hybridization, the localization of the human PTAFR gene was mapped to 1p35-->p34.3.     

Age and sex effects on HbA1c. A study in a healthy Chinese population

OBJECTIVE: To evaluate whether glycohemoglobin levels increase with age in both sexes and to determine the effect of BMI on this increment. RESEARCH DESIGN AND METHODS: A cross-sectional survey of 4,580 healthy Chinese men and women, aged 20-85 years, was performed. All subjects who did not have identifiable diseases and who were not on medication known to influence glucose tolerance were recruited from participants at the preventive services of the National Cheng-Kung University Hospital. As an indicator of plasma glucose levels, glycohemoglobin was measured. The subjects were classified according to their age and BMI for both men and women, and any relationships with glycohemoglobin levels were evaluated. RESULTS: In all the BMI groups divided into quartiles, glycohemoglobin levels increased with age. The largest elevation of glycohemoglobin was observed in the 45- to 54-year-old age-group, except in men with a BMI between the lowest and highest quartiles. The group with a BMI above the highest quartile had a higher glycohemoglobin than the group with a BMI below the lowest quartile in men aged < 54 years and women aged 35-64 years. Men had higher average glycohemoglobin levels than women < 55 years of age. CONCLUSIONS: The age factor itself may cause an elevation in glycohemoglobin independent of other age-related factors in Chinese men and women, and there is a sex difference with a lower average glycohemoglobin level in women before menopause. Furthermore, BMI, but not a family predisposition to diabetes or leisure-time physical activity, affects this age-dependent increase in glycohemoglobin levels.     

Solubilization and functional reconstitution of the human placental taurine transporter

Recent studies have suggested that Lp(a) is implicated in the high incidence of coronary heart disease in diabetic subjects, but data are still controversial. We therefore studied the distribution of plasma Lp(a), assayed by radial immunodiffusion, in a group of 224 diabetics and compared them to 92 non diabetic controls. Besides plasma Lp(a), TG and glucose were evaluated in 16 insulin-requiring diabetic patients before and after 10 days of normoglycaemia. The distribution of plasma Lp(a), as usually skewed to the left, was not different either between diabetic subjects and controls or between Type 1 and Type 2 diabetic subjects. No significant correlation was observed between Lp(a) and glycaemic control expressed by HbA1c. The sequence of normoglycaemia did not affect plasma Lp(a), no significant correlation between the variations of glycaemia and Lp(a) levels and the variations of triglyceridaemia and Lp(a) levels were found. Thus our group of diabetic subjects has a similar distribution of Lp(a) to controls. Lp(a) concentrations do not seem to be affected by chronic hyperglycaemia or rapid normalisation of glycaemic levels. However there is a strong need of standardization of Lp(a) assay before any definitive conclusion. As we have so far no efficient treatment for lowering Lp(a) in daily clinical practice, the energetic care of other associated vascular risk factors is needed.