Mechanism of tribofilm formation on Ti6Al4V oxygen diffusion layer in a simulated body fluid

An Oxygen Diffusion Layer (ODL) was generated on the surface of Ti6Al4V alloy by thermal oxidation treatment. In vitro tests for cytotoxicity were performed in the presence of Ti6Al4V and the ODL samples with the culture of G292 Cells using MTT assay. The results showed a similar cell viability in the presence of the both samples. Wear behaviour of Ti6Al4V and the ODL samples was investigated in a phosphate buffered saline solution under a normal load of 30N at a sliding velocity of 0.1m/s. The worn surface and subsurface of the samples were studied using SEM, STEM, TEM, XPS, AFM, nano-hardness and surface profilometry. A bio-tribofilm was observed on the worn surface of the ODL. TEM studies showed that the tribofilm had an amorphous structure and contained oxygen and phosphorous as confirmed by XPS and EDS analysis. AFM images also revealed that the tribofilm consisted of compacted fine debris. The formation of the tribofilm on the ODL with higher hardness and strength resulted in a decrease of about 95% in the wear rate compared with Ti6Al4V alloy.

Reduced postheparin plasma diamine oxidase activity in patients with chronic renal failure

The intestinal mucosa plays a fundamental role as the site for absorption of nutrients, and as an important barrier against potentially harmful agents in the gastrointestinal lumen. The functional integrity of the small bowel in patients with chronic renal failure was measured by post-heparin-diaminoxidase (DAO) activity in a low and safe dose of heparin (5000 IU) in patients with chronic renal failure participating in a hemodialysis program. The results of the study provide one of the first observations about a diminished DAO-response in patients with chronic renal failure reflecting a mucosal abnormality in these patients which has to be further characterized. Our findings also show that this reduced DAO activity is not caused by the effect of uremic toxins. These results further show that a smaller and safer i.v. dose of heparin (5000 IU or less) will release DAO activity as reliably as high doses used by others. We therefore conclude that postheparin DAO activity might be used as a new noninvasive test reflecting intestinal function in patients with chronic renal failure.

Watershed infarction in a case of polycythemia vera

Hyperviscosity of the blood is a known cause of ischemic cerebral infarction. A case of polycythemia vera complicated by a watershed infarction is presented.