Changes in silicon elastomeric surface properties under stretching induced by three surface treatments.

Poly(dimethylsiloxane) (PDMS) substrates are used in many applications where the substrates need to be elongated and various treatments are used to regulate their surface properties. In this article, we compare the effect of three of such treatments, namely, UV irradiation, water plasma, and plasma polymerization, both from a molecular and from a macroscopic point of view. We focus our attention in particular on the behavior of the treated surfaces under mechanical stretching. UV irradiation induces the substitution of methyl groups by hydroxyl and acid groups, water plasma leads to a silicate-like layer, and plasma polymerization causes the formation of an organic thin film with a major content of anhydride and acid groups. Stretching induces cracks on the surface both for silicate-like layers and for plasma polymer thin coatings. This is not the case for the UV irradiated PDMS substrates. We then analyzed the chemical composition of these cracks. In the case of water plasma, the cracks reveal native PDMS. In the case of plasma polymerization, the cracks reveal modified PDMS. The contact angles of plasma polymer and UV treated surfaces vary only very slightly under stretching, whereas large variations are observed for water plasma treatments. The small variation in the contact angle values observed on the plasma polymer thin film under stretching even when cracks appear on the surface are explained by the specific chemistry of the PDMS in the cracks. We find that it is very different from native PDMS and that its structure is somewhere between Si(O2) and Si(O3). This is, to our knowledge, the first study where different surface treatments of PDMS are compared for films under stretching.

Dacarbazine, fluorouracil, and leucovorin in patients with advanced neuroendocrine tumors: a phase II trial.

Chemotherapy of neuroendocrine tumors must be improved. The most widely used regimen, which combines streptozotocin with fluorouracil, commonly obtains poor results. The best response rate that has been reported for carcinoid tumors is 33%. From July 1991 through September 1994, 18 patients who had advanced neuroendocrine tumors-including nine carcinoid tumors, seven neuroendocrine tumors of unknown primary site, one insulinoma, and one paraganglioma-were treated with a regimen of dacarbazine, 400 mg/m2/day, plus fluorouracil, 1 g/m2/day, with leucovorin, 200 mg/m2/day, for 2 days every 21 days (DTIC-LVFU2 protocol). The results were assessed according to the World Health Organization criteria of toxicity and response. Toxicity was moderate. The most severe side effects were grade 3 vomiting in two patients, grade 3 leukopenia in three patients, and grade 3 mucositis in one patient. The overall response rate was 27%, with only one partial response for carcinoid tumors but one complete and three partial responses for the other tumor types. Efficacy was insufficient in patients who had carcinoid tumors but the combination of dacarbazine with fluorouracil and leucovorin could be an effective regimen for the treatment of neuroendocrine tumors of unknown primary site.

Restriction of V beta gene usage of liver-derived lymphocytes in chronic hepatitis B and C.

T lymphocytes have been reported to be the predominant inflammatory cells in the liver of patients with chronic viral hepatitis. Their presence may reflect either nonspecific inflammation or a virus-specific immune response. To assess the repertoire of intra-hepatic T cells, we investigated the TCR V beta gene usage of T cells in 10 patients with chronic hepatitis B and 15 with chronic hepatitis C. Liver-derived lymphocytes and peripheral blood lymphocytes were analyzed by flow cytometry. Five out of the 10 hepatitis B patients were found to have an accumulation of certain V beta T cells in the liver (V beta 6.7; V beta 6.7; V beta 3.1, V beta 5.1, and V beta 6.7; V beta 3.1; V beta 12.1, respectively). Four out of the 15 hepatitis C patients were found to have an accumulation of certain V beta T cells in the liver (V beta 5.1; V beta 8 and V beta 5.2 and 5.3; V beta 3.1 and V beta 5.2 and 5.3; V beta 3.1 and V beta 12.1, respectively). Despite a limited screening of V beta subfamilies, this study indicates that, in patients with chronic hepatitis B and C, T cells using a certain V beta gene may accumulate in the liver. This suggests that intra-hepatic T cells are oligoclonal and possibly virus specific. Our results argue against the role of a superantigen in perpetuating liver disease. In addition, this study supports a role for T lymphocytes in the pathogenesis of chronic hepatitis C.

Providing infertility care.

In recent years nurse practitioners have expanded their repertoire of ob/gyn skills to include the provision of infertility care. To minimize the stresses involved in an infertility investigation, couples benefit from a care provider who can educate them about the factors, testing, and treatments involved in infertility. They also need a provider who can support them emotionally through a work-up that touches upon the sensitive aspects of their sexuality, partner relationship, and self-esteem. Nurse practitioners have demonstrated an aptitude in providing competent medical care and health education in the context of a therapeutic relationship. Utilization of the physician/nurse practitioners collaborative team approach offers one successful model for integrating nurse practitioners into the practice of infertility.