A role for cyclooxygenase in aging-related changes of β-adrenoceptor-mediated relaxation in rat aortas

β-Adrenoceptor-mediated vasorelaxation decreases with age in various vascular beds. The present study investigated the roles of cyclooxygenase (COX) on β-adrenoceptor vasorelaxation by isoprenaline in 8- and 54-week-old rat aortas. The vasorelaxation responses by isoprenaline (0.03–3 μM) were significantly reduced in 54-week-old aortas compared to 8-week. Addition of the non-selective COX inhibitors indomethacin (10 μM) or aspirin (10 μM) restored isoprenaline vasorelaxation of 54-week-old aortas to levels found in 8-week-old aortas. This suggests the involvement of COX prostanoids in the age-related reduction of β-adrenoceptor vasorelaxation. Immunohistochemistry revealed greater levels of COX-1 and COX-2 staining in 54-week-old aortas compared to 8-week with expression located mainly in medial smooth muscle. An age-linked increase in COX-1 and COX-2 protein was found in cremaster arterioles of 54-week-old rats (compared to 8-week) mainly in the endothelial layer. The age-related increase in COX-1 and COX-2 protein led to elevation of prostacyclin (measured as 6-keto prostaglandin ) and thromboxane A₂ (measured as thromboxane B₂) in 54-week compared to 8-week-old aortas. Endothelium removal in 54-week aortas markedly reduced the 6-keto prostaglandin level, thus suggesting an endothelial source for elevated prostacyclin. These findings in combination with the effects of COX inhibitors suggest that the age-related decrease in β-adrenoceptor vasorelaxation by isoprenaline is due to an age-linked increase in COX expression, which elevates production of COX-derived vasoactive prostanoids.     

Mechanism of human accommodation as analyzed by nonlinear finite element analysis

Results of nonlinear finite element analysis support the Schachar theory of accommodation and demonstrate that the long-held Helmholtz theory of accommodation is impossible.     

Composite lymphoma of Hodgkin lymphoma and mycosis fungoides: previously undescribed in the same extracutaneous site.

Mycosis fungoides (MF), diagnosed and limited to the skin, has been associated with the subsequent development of Hodgkin lymphoma (HL), most commonly of the nodular sclerosing (NS) subtype. In the previously described cases, there are none in which the extracutaneous tissue was simultaneously involved by HL and residual/relapsing MF. Here we report a case of HL, mixed cellularity (MC) subtype, arising in an inguinal lymph node in a patient with a previous diagnosis of MF. We describe the immunophenotypic, histologic and immunohistochemical findings of a composite lymphoma containing the HL, MC subtype and MT. The importance of detecting MF in addition to the HL in the extracutaneous site with available diagnostic modalities is highlighted.     

Alanine aminotransferase is an inadequate surrogate marker for detecting lamivudine resistance

AIM: To investigate the accuracy of serum alanine aminotransferase (ALT) in diagnosing lamivudine resistance and factors that contributed to abnormal serum ALT.METHODS: This was a retrospective study of chronic hepatitis B patients on lamivudine therapy who were followed for 3-mo with liver function tests and hepatitis B virus (HBV) DNA measurement. Lamivudine resistance was defined as HBV DNA ≥ 1 log from nadir on at least 2 occasions, confirmed by genotyping. Serum ALT levels in patients with lamivudine r...