Characterisation of bioactive glass coatings on titanium substrates produced using a CO2 laser

Titanium and its alloys are widely used in load-bearing bioinert implants. Bioactive glasses (BAGs) form a chemical bond with bone, but they are not suitable for load-bearing applications. Creating a BAG coating on a titanium implant could combine the best properties of both materials. The results tend to be poor when conventional firing methods are applied to coat titanium with BAG. A local application of heat to melt the glass can be achieved by a CO2 laser. A new method is introduced to create BAG coatings on titanium locally in a controlled manner, with a focused CO2 laser beam. The coatings produced by this method precipitate calcium phosphate in vitro. Processing parameters (number of coated layers, laser power, and processing atmosphere) providing a firm attachment of the glass and good in vitro bioactivity were identified. XRD analysis showed no crystallisation of the glass due to processing with the laser. EDXA indicated the formation of a calcium phosphate layer, which FTIR suggested to be a hydroxyapatite. The results show CO2 laser processing to be a promising technique for the manufacture of 30-40 microm BAG coatings on titanium.     

Effect of bioactive glass granules and polytetrafluoroethylene membrane on repair of cortical bone defect

The effect of bioactive glass (BG) granules and nonresorbable polytetrafluoroethylene (PTFE) membrane on the repair of cortical bone defects was studied. Monocortical holes (diameter 3.0 mm) were drilled in rabbit tibia. Sixteen holes were filled with BG granules (diameter 630–800 m). Twelve holes were left empty and covered with PTFE membrane. No material was used at ten control holes. All experiment areas were covered with periosteum attached to the soft tissue flap. Histomorphometric evaluation of resection specimens showed that new bone and glass particles formed a continuous bridge in the BG group at the upper part of the hole, occupying 73.6% and 61.7% of the defect at 6 and 12 weeks, respectively. If only the amount of bone but not glass particles was included in the measurements the corresponding figures were 31.4% and 41.5%. The bone repair in the PTFE group was 12.1% and 11.3% and in the control group 25.1% and 23.3% at 6 and 12 weeks, respectively. The results indicate that BG granules improve repair of cortical bone defects and PTFE membrane seems to impair bone formation in these defects.     

Diuretics and diabetes mellitus

The term "diuretics" describes a concerning pharmacological action and side effects heterogeneous class of drugs. The special advantage of using diuretics includes reducing edema and expanded plasma volume often associated with hypertension and cardiovascular disease. Diuretics are one of the 5 major classes of antihypertensive agents recommended for the initial drug therapy of hypertension. However, currently treatment of hypertension with diuretics is controversial, because of potentially adverse effects on the cardiovascular risk profile, including deterioration in glucose control especially in patients with impaired glucose tolerance. Additionally there is concern about excess mortality associated with diuretic therapy and diabetes mellitus. The metabolic side effects on glucose metabolism and lipid profile are related to the type of diuretic and its dosage. The adverse effects of thiazides on insulin action, glycemia and lipid profile are dose dependent and can be minimized by using low doses. In contrast, indapamide seems not to alter glucose metabolism and lipid profile. The choice of diuretic depends on concomitant disease. In patients with nephropathy potassium sparing agents should not be used, however furosemid can be used even in high doses. Beside focus on indication of diuretics in patients with diabetes and their metabolic side effects treatment of therapy resistant hypertension in these patients are discussed in this review.     

In Vitro Release Behavior of Toremifene Citrate from Sol-Gel Processed Sintered Silica Xerogels

Factors affecting the adsorption and desorption of toremifene citrate (TC) on sintered silica xerogels were investigated in vitro. TC was attached onto sol-gel processed sintered silica xerogel grains or disks by adsorption. The adsorption of TC on the surface of silica was pH dependent. The results support the conclusion that large pore size results in highest drug adsorption. Adsorption of TC was most effective in xerogels sintered at 700°C and containing the largest pores and lowest specific surface area of the silica xerogels studied in the adsorption tests. The release of TC from the xerogel matrix was linear with respect to the square root of time. The release of TC from the grains was very rapid for the first 5 hr, followed by a slower release. All drug was released from the grains, and 60% to 80% was released from the disks in 24 hr. All drug-silica xerogel formulations showed sustained in vitro release profiles.     

Pericardial thickening or effusion in patients with pulmonary artery hypertension: a CT study

OBJECTIVE: The aim of the study was to determine the prevalence of pericardial thickening or effusion revealed by CT in patients with pulmonary artery hypertension. MATERIALS AND METHODS: Forty-five patients underwent pulmonary artery catheterization and CT of the thorax. On CT, we measured the maximum pericardial thickness, total pericardial score (the sum of four measures of pericardial thickness), and thickness of the anterior pericardial recess. Patients were grouped according to mean pulmonary artery pressure: group 1, less than 21 mm Hg (n = 15); group 2, 21-35 mm Hg (n = 15); and group 3, greater than 35 mm Hg (n = 15). RESULTS: The prevalence of an increased pericardial score and increased maximum pericardial thickening was higher in group 3 than in group 1 or group 2 (p = .02 and < .001, respectively). Anterior pericardial recess thickening was markedly increased in group 3 (p < .0001). For all patients, significant correlations (Spearman's rank correlation coefficient = .44-.56, p < .005-.0001) were found between mean pulmonary artery pressure and all pericardial measures. CONCLUSION: On CT, pericardial thickening or effusion is a frequent finding in patients with severe pulmonary hypertension.     

质子交换膜燃料电池的电响应研究

通过暂态实测方法,研究了质子交换膜燃料电池(PEMFC)的动态响应及电压建立。通过使用燃料电池测试系统、高精度示波器和自行设计的开关电路,在不同的运行条件下对PEMFC的电响应进行测量,实验结果证明PEMFC的动态响应和电压建立与其运行条件以及单体电池在电堆中的位置有非常紧密的联系。     

超滤运行过程中膜表面亲水性的变化特征

为了研究膜亲水性在超滤运行过程中的变化规律,采用小试装置,研究了在不同运行状况下的膜接触角变化。结果表明,在长期的运行过程中,膜接触角均不同程度地下降。单独水反冲洗和化学加强反洗对接触角的影响较小。膜接触角在过滤周期内先升高再降低。随着通量的增加,膜接触角逐渐降低。与沉后水相比,活性炭过滤出水更易引起膜接触角下降。随着pH升高,膜接触角会上升。化学清洗使膜接触角增加,当用NaOH清洗时,接触角变化不大;而用HCl和NaClO清洗时,接触角明显增加。总之,膜表面亲水性在运行过程中会发生一定变化,并且受到原水水质、操作参数和反冲洗方式等方面影响。     

光学旋光法的血糖浓度测量

采用光学法检测血糖浓度是现今国际研究的热门课题,目的是实现对糖尿病患者进行快速、无创、频繁、实时的血糖监测。本文介绍了光学旋光法检测血糖浓度的原理,对基于光学旋光法进行无创血糖检测技术的研究状况进行综述,讨论了各测量法的优缺点。     

Uniparental disomy for chromosome 6 results in steroid 21-hydroxylase deficiency: evidence of different genetic mechanisms involved in the production of the disease

Congenital adrenal hyperplasia (CAH) is an inherited recessive disorder of adrenal steroidogenesis caused by mutations in the steroid 21-hydroxylase gene (CYP21) in more than 90% of affected patients. The CYP21 gene is located within the HLA complex locus on chromosome 6 (6p21.3). During a molecular characterisation study of a group of 47 Mexican families with 21-hydroxylase deficiency, we identified nine in which the mutation or mutations found in the patient did not appear to originate from one of the parents. Through DNA fingerprinting, paternity was established in all nine families with a probability of non-paternity in the range of 10(-19) to 10(-23). Among these families, we identified one patient with exclusive paternal inheritance of all eight markers tested on chromosome 6p, despite normal maternal and paternal contributions for eight additional markers on three different chromosomes. We did not identify duplication of paternal information for markers in the 6q region, consistent with lack of expression of transient neonatal diabetes owing to genomic imprinting in this patient. Our results substantiate evidence for the existence of different genetic mechanisms involved in the expression of this recessive condition in a substantial portion (approximately 19%) of affected Mexican families. In addition to the identification of a patient with paternal uniparental disomy, the occurrence of germline mutations may explain the unusual pattern of segregation in the majority of the remaining eight families.     

In situ analysis of adhesion molecule expression in kidneys infected with murine malaria

Two toluene-sensitive mutants were generated from Pseudomonas putida IH-2000, the first known toluene-tolerant isolate, by Tn5 transposon mutagenesis. These mutants were unable to grow in the presence of toluene (log P(ow) 2.8) but they could grow in medium overlaid with organic solvents having a log P(ow) value higher than that of toluene such as p-xylene (log P(ow) 3.1), cyclohexane (log P(ow) 3.4) and n-hexane (log P(ow) 3.9). The Tn5 transposable element knocked out a cyoB-like gene in one mutant and a cyoC-like gene in the other mutant. Seven open reading frames were found in a 5.5-kb region containing the cyoB- and cyoC-like genes of strain IH-2000. ORFs 3.7 showed significant identity to the cyoABCDE gene products of Escherichia coli, but ORFs 1 and 2 showed no significant homology to any protein reported so far. The growth patterns of the Tn5 mutants with the inactivated cyo-like gene were similar to that of the wild-type strain in the absence of organic solvents, although the doubling times were slightly longer than that of the wild-type strain. Our findings indicate that cyo is an important gene for toluene tolerance, although its role is still unclear.