可注射性磷酸钙骨水泥生物相容性评价

目的:磷酸钙骨水泥是一种新型骨移植替代材料,对它的改性研究是近年来的研究热点之一,通过改变磷酸钙骨水泥的流变学,制备可注射性磷酸钙骨水泥更适于微创应用,但应用于临床要对其生物相容性进行评价。方法:实验于2006-10/2007-01在天津医院骨科研究所完成。①实验材料:可注射性磷酸钙骨水泥(由固相与液相两部分组成,固相为碳酸钙、磷酸氢钙等,液相为磷酸钠盐溶液)。②实验动物:新西兰兔14只,体质量2.0～3.5kg,雌雄各半。实验过程中对动物处置符合动物伦理学要求。③实验方法和评估:通过采用可注射性磷酸钙骨水泥浸提液和试件与骨髓基质细胞分别共培养,MTT法测定细胞相对增殖率,进行细胞毒性反应分级,光镜和扫描电镜观察细胞生长形态和生长活性。可注射性磷酸钙骨水泥浸提液进行溶血和热原试验观察。将可注射性磷酸钙骨水泥试件植入兔肌肉内,观察炎症反应和纤维包膜形成情况。结果:14只新西兰兔均进入结果分析。可注射性磷酸钙骨水泥浸提液和试件与骨髓基质细胞共培养,细胞生长形态良好,数量逐渐增加,细胞毒性反应为0～Ⅰ级,基本无毒性。浸提液的溶血率<0.05%,注入兔耳缘静脉后未引起发热反应。可注射性磷酸钙骨水泥试件植入兔肌肉中观察24周,早期有淋巴细胞浸润,包膜形成,晚期淋巴减少或消失,包膜稳定,无增厚趋势,未见有白细胞浸润。结论:可注射性磷酸钙骨水泥具有良好的生物相容性,符合植入人体生物材料的细胞毒性要求,对机体不会造成不良影响,因而临床可以安全使用。     

EUROPEAN STUDY ON EPIDEMIOLOGY AND THE MANAGEMENT OF HCV IN THE HAEMODIALYSIS POPULATION. PART 1: CENTRE POLICY

Haemodialysis patients are known to be at risk of infection of Hepatitis C Virus (HCV) through nosocomial spread. This paper presents the first part of a study on epidemiology and management of HCV, in a haemodialysis population, conducted by the EDTNA/ERCA Research Board. Data on HCV management and infection control procedures was collected from 136 European centres using an electronic questionnaire. The study identifies a number of possible risk factors for transmission of the virus: failing to disinfect devices between patients, sharing of single‐use vials to prepare drugs or infusions for different patients, inadequate sterilisation or cleaning of machines between dialysis sessions, unsatisfactory environmental cleaning and distance less than one metre between chairs.     

Subpopulations of fetal-like gingival fibroblasts: characterisation and potential significance for wound healing and the progression of periodontal disease

Wound healing in the adult is commonly compromised by excessive scar formation. In contrast, fetal wound healing is a regenerative process characterised by the conspicuous absence of scarring. Available evidence suggests that phenotypic differences between fetal and adult fibroblasts are important determinants of these distinct modes of tissue repair. In this context, a number of groups (including our own) have documented differences between fetal and adult fibroblasts with respect to such potentially relevant characteristics as migratory activity, motogenic response to cytokines and the synthesis of motility factors, cytokines and matrix macromolecules. The oral mucosa appears to be a privileged site in the adult in that it continues to display a fetal-like mode of wound healing. Data are presented in this review indicating that a subpopulation of gingival fibroblasts expresses several 'fetal-like' phenotypic characteristics. These observations are discussed in terms of both the continued expression of a fetal-like mode of wound healing in the oral mucosa and the possible differential involvement of distinct fibroblast subpopulations in the progression of periodontal disease.     

A study on BMI among the Bhotia of Uttaranchal,India

ObjectiveTo investigate the nutritional status of the males and females in two subgroups of the Bhotia tribe (Marcha and Tolcha) inhabiting in three different altitudes in Uttaranchal, India.MethodsData were collected from the Tolcha and Marcha, two sub-groups of the Bhotia, inhabiting in Chamoli district of Uttaranchal. Bhotia adults of both sexes were considered. Field investigation was conducted in three ecological zones (high, middle and low altitude) of the district during April-August, in the years 2002-2004. Anthropometric measurements were obtained in accordance with the techniques recommended by Weiner and Lourie (1981). The variables like height, weight, waist circumference, hip circumference, waist-hip ratio and blood pressure were studied in relation to BMI.ResultsRelatively higher value of mean BMI is recorded among the females than that of the males, which is true for different altitudes, in both subgroups. The BMI also indicates an inverse relationship with altitude, except for the Tolcha males in high altitude. Lowest mean BMI is recorded in middle altitude among the Tolcha subgroup. Chronic energy deficient (CED) individuals are much more than twice the number among the males of both the subgroups inhabiting in different altitudes. Interestingly, the percentage of CED individuals increases with the altitude.ConclusionsRegression analysis indicates that height, weight, hip circumference and waist circumference are dependent on body mass index in the studied populations. Probable reason for poor nutrition status among the Tolcha and Marcha of high altitude might be due to the fact that the Tolcha and Marcha of high altitude consume lesser amount of proteins, fat, milk and milk products in general than their counterpart inhabit in lower and middle altitude.     

Increased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia

Background and purpose:

There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries.

Experimental approach:

Vascular reactivity to ET-1 and ET_A and ET_B receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET_A and ET_B receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [¹²⁵I]-ET-1.

Key results:

HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET_A or ET_B receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET_A but not of ET_B receptors abolished enhancement in HHcy tissues. ET_A and ET_B receptor gene expressions were not up-regulated. ET_A receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A₂ receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO.

Conclusions and implications:

Increased ET_A receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET_A receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility.British Journal of Pharmacology (2009) 157, 568–580; doi:10.1111/j.1476-5381.2009.00165.x; published online 9 April 2009This article is part of a themed section on Endothelium in Pharmacology. For a list of all articles in this section see the end of this paper, or visit: http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009     

Novel PLA/Chitosan Composite Materials Prepared by SCF-CO2 Technique

Because of the incomparable merits （nontoxicity, non-remainder, fast transfer mass） of supercritical carbon dioxide fluid technique（SC-CO2）, it was used to developed a series of novel biodegradable tissue engineering scaffold materials in this research. The novel PLA/chitosan composite materials could be molded to different shapes, and the porosity of the materials were over 200 lam and connected. Chondrocyte cultivation, subcutaneous and intramuscular implantation were mainly discussed this paper. The results showed that the cells could well adhere, grow and multiplicate on the surface of the materials, which indicated good biocompatibility of the composite materials. The plantation test revealed that the PLA materials had already dismissed 2 month late in the body, while the composite materials could still keep certain strength and shape, and the most important things is the response of the tissue toward the implanted PLA/chitosan composite materials was mild and had far less inflammation than PLA materials. 8 to 16 weeks later, fiber membrane was stable; degradation of the materials was seen clear and tissue had already spread into it.     

Dose resolution in radiotherapy polymer gel dosimetry: effect of echo spacing in MRI pulse sequence

In polymer gel dosimetry using magnetic resonance imaging, the uncertainty in absorbed dose is dependent on the experimental determination of T2. The concept of dose resolution (Dpdelta) of polymer gel dosimeters is developed and applied to the uncertainty in dose related to the uncertainty in T2 from a range of T4 encountered in polymer gel dosimetry. Dpdelta is defined as the minimal separation between two absorbed doses such that they may be distinguished with a given level of confidence, p. The minimum detectable dose (MDD) is Dpdelta as the dose approaches zero. Dpdelta and the minimum detectable dose both give a quantifiable indication of the likely practical limitations and usefulness of the dosimeter. Dpdelta of a polyacrylamide polymer gel dosimeter is presented for customized 32-echo and standard multiple-spin-echo sequences on a clinical MRI scanner. In evaluating uncertainties in T2, a parameter of particular significance in the pulse sequence is the echo spacing (ES). For optimal results, ES should be selected to minimize Dpdelta over a range of doses of interest in polymer gel dosimetry.