Computer simulations and the use of radiolabelled sulphur colloid to measure the efficiency of the mononuclear phagocyte system

Technique are described whereby the clearance of the radiolabelled blood borne colloid can be continuously and reproducibly measured non-invasively from the same animal in vivo or from the isolated perfused intact liver in vitro. Using these techniques, the rate of removal of radiolabelled sulphur colloid by the mononuclear phagocytes in vivo and in vitro was shown to be biexponential. The pattern of clearance of colloid and the factors contributing to this were analysed with the aid of a computer program which mimicked the in vitro liver perfusion.     

Modifying delivery technique of fenoterol from a metered dose inhaler

Twenty-eight outpatients with bronchial asthma inhaled one puff of fenoterol hydrobromide (200 mcg) from a metered dose inhaler, either held in three different mouth positions or from three different starting lung volumes. Inhaling bronchodilator with closed mouth was significantly less effective than when the mouth was open, or when the inhaler was four cm from the open mouth. Inspiration of drug beginning from 75% of vital capacity resulted in better bronchodilation than starting at residual volume. Patients are likely to obtain maximum benefit from metered dose inhalers when the mouth is open and the inspiratory volume is small.     

A mixture of ammonium perchlorate and sodium chlorate enhances alterations of the pituitary-thyroid axis caused by the individual chemicals in adult male F344 rats

Ammonium perchlorate (AP) and sodium chlorate (SC) have been detected in public drinking water supplies in many parts of the United States. These chemicals cause perturbations in pituitary-thyroid homeostasis in animals by competitively inhibiting iodide uptake, thus hindering the synthesis of thyroglobulin and reducing circulating T(4) (thyroxine). Little is known about the short-term exposure effects of mixtures of perchlorate and chlorate. The present study investigated the potential for the response to a mixture of these chemicals on the pituitary-thyroid axis in rats to be greater than that induced by the individual chemicals. Adult male F-344 rats were exposed, via their drinking water, to the nominal concentrations of 0.1, 1.0, 10 mg/L AP or 10, 100, 1000 mg/L SC and their mixtures for 7 days. Serum T(4) levels were significantly (p < 0.05) reduced in rats following exposure to the mixtures, but not after exposure to the individual chemicals. Serum T(3) (triiodothyronine) was not altered by treatment and TSH (thyroid stimulating hormone) was only increased after the high-dose chlorate treatment. Histological examination of the thyroid gland showed colloid depletion and hypertrophy of follicular epithelial cells in high-dose single chemical and all mixture-treated rats, while hyperplasia was observed only in some of the rats treated with mixtures (AP 10 + SC 100, AP 0.1 + SC 1000, and AP 10 + SC 1000 mg/L). These data suggest that short-term exposure to the mixture of AP and SC enhances the effect of either chemical alone on the pituitary-thyroid axis in rats.     

Psychosocial factors in medical and psychological treatment avoidance: the role of the doctor-patient relationship

A community sample of 1106 adults was examined to assess the impact of the doctor-patient relationship on participants' avoidance of treatment for a recognized medical or psychological problem. Of five aspects of participants' previous experience with their physicians, all but waiting time predicted participants' self-reported treatment avoidance. In two logistic regression models participants who felt their physicians listened more to their concerns were less likely to avoid treatment for both medical and psychological problems during the previous 12 months. These findings suggest that patients' perceptions of how they are treated by physicians may help explain why many people delay or avoid healthcare treatment, even when faced with a significant health problem.     

Laminin-5-enriched extracellular matrix accelerates angiogenesis and neovascularization in association with ePTFE

The performance of biomedical implant devices is often limited by inappropriate tissue responses associated with synthetic materials used in device construction. Adverse healing responses, in particular the lack of an extensive vascular supply in the peri-implant tissue, are believed to lead to the ultimate failure of many of these medical devices. Accelerated formation of new blood vessels in the peri-implant tissue and within porous polymeric implants is hypothesized to improve the performance of such biomedical implant devices. The current study evaluated the use of cell-mediated, extracellular matrix modification of expanded polytetrafluoroethylene (ePTFE) to increase vessel growth in peri-implant tissue and within the pores of the implants. Discs of ePTFE were modified through cell-mediated matrix deposition using epithelial and endothelial cell lines with variable deposition of collagen types, fibronectin, and laminin types. Cell matrix-modified discs, Matrigel-coated discs, and nonmodified discs were implanted in both the adipose and subcutaneous tissues of the rat. Following a 5-week implant period, samples were removed and evaluated histologically and morphometrically for the presence of blood vessels in the peri-implant tissue and within the pores of the polymer as well as for the presence of activated macrophages and monocytes. A significantly increased presence of activated macrophages and monocytes was associated only with the samples modified with the matrix from a human microvessel endothelial cell line. Increased vessel density was identified in association with those ePTFE samples modified with either the 804-G, HaCaT, or II-4 cell matrices, all of which have extracellular matrices enriched in the protein laminin-5.