Transgenic mice expressing the E7 protein of HPV16 from the keratin 14 promoter demonstrate increasing thymic hypertrophy with age. This hypertrophy is associated with increased absolute numbers of all thymocyte types, and with increased cortical and medullary cellularity. In the thymic medulla, increased compartmentalization of the major thymic stromal cell types and expansion of thymic epithelial cell population is observed. Neither an increased rate of immature thymocyte division nor a decreased rate of immature thymocyte death was able to account for the observed hypertrophy. Thymocytes with reduced levels of expression of CD4 and/or CD8 were more abundant in transgenic (tg) mice and became increasingly more so with age. These thymic SP and DP populations with reduced levels of CD4 and/or CD8 markers had a lower rate of apoptosis in the tg than in the non-tg mice. The rate of export of mature thymocytes to peripheral lymphoid organs was less in tg animals relative to the pool of available mature cells, particularly for the increasingly abundant CD4lo population. We therefore suggest that mature thymocytes that would normally die in the thymus gradually accumulated in E7 transgenic animals, perhaps as a consequence of exposure to a hypertrophied E7-expressing thymic epithelium or to factors secreted by this expanded thymic stromal cell population. The K14E7 transgenic mouse thus provides a unique model to study effects of the thymic epithelial cell compartment on thymus development and involution.

Aging↗

PubMedDate not supplied

Polyol-combinant saliva stimulants and oral health in Veterans Affairs patients--an exploratory study.

An exploratory study investigated the root caries incidence in Department of Veterans Affairs patients with exposed root surfaces. For a period of six to 30 months, the subjects were systematically assigned to groups which used chewable dragees or chewing gums that contained either xylitol or sorbitol as bulk sweeteners. The mean treatment time was 1.8 years (standard deviation = 0.8). The consumption levels of both polyols was up to 8.5 g daily, used typically in five episodes during a 16-hour period. The subjects were examined every six months in connection with their standard scheduled visits at the Veterans Affairs Medical Center. The risk for a root-surface lesion in the xylitol group was only 19% of that for a surface in the sorbitol group (relative risk, 0.19; 95% confidence interval, 0.06-0.62; p < or = 0.0065). Simultaneous study in periodontal patients showed that both polyols significantly reduced the gingival index scores, and slightly (but not significantly) reduced the plaque index scores. Collectively, both studies suggest that frequent daily consumption of chewable, saliva-stimulating products containing essentially nonfermentable or slowly fermentable dietary carbohydrate sweeteners (xylitol and sorbitol) may have an oral-health-improving effect in Department of Veterans Affairs Medical Center patients. It is necessary to evaluate if these procedures would be efficacious in larger and expanded patient cohorts.

Aged↗

PubMedDate not supplied

Packaging of intravenous solutions.

Until recently, polypropylene was not used extensively in the packaging of intravenous (i.v.) solutions. Despite the excellent moisture-barrier properties and the high purity level of polypropylene, the prevailing i.v.-solution packaging concepts are based on plasticized polyvinyl chloride (PVC), glass, and polyethylene. In the light of an article that appeared in the March/April issue of Medical Device Technology, in which Wilhelm Striepe justifies the use of PVC in the manufacture of medical products, this article looks at alternatives to PVC for the packaging of i.v. solutions.

Glass↗

PubMedDate not supplied

Complement activation and leucopenia on cellulosic haemodialyzers: influence of the membrane area and role of hydroxyl moieties.

We analysed the impact of the area of the dialysis membrane and of its content in hydroxyl moieties on the magnitude of haemodialysis-induced complement activation and leucopenia. First, in five patients successively treated with cellulose acetate membranes of different areas, we found that increase of the area results in an increase in complement activation determined by C3a levels before and at 15 min of dialysis. The levels of leucopenia were similarly affected, and a significant correlation was found between complement activation and leucopenia (r = 0.89, P less than 0.05). When we compared the biocompatibility characteristics of a dialyser made of saponified cellulose ester with those of two dialysers made of cellulose acetate, we found that index of complement activation (18.1 +/- 2 vs 9.9 +/- 1.1 and 11.5 +/- 1.1, P less than 0.01) as well as index of leucopenia (69 +/- 4 vs 40 +/- 2 and 37 +/- 3, P less than 0.001) were significantly higher on the saponified cellulose ester dialysers suggesting that hydroxyl groups of cellulosic membranes play an important role in the pathophysiology of dialysis-induced changes.

Biocompatible Materials↗

PubMedDate not supplied