[Risk factor for residual deep vein thrombosis after fondaparinux administration in patients with postoperative replacement arthroplasty].

Deep venous thrombosis (DVT) is a life-threatening postoperative complication and occurs frequently after total-knee-replacement arthroplasty (TKA) and total-hip-replacement arthroplasty (THA). Fondaparinux (FPX) has been used to treat and prevent DVT, however interindividual difference of the drug efficacy exists. Therefore, this chart review was retrospectively conducted to research risk factors for a residual DVT after FPX treatment. Total of 112 patients undergone TKA or THA were treated with 2.5 mg FPX once a day between postoperative day (POD) 1 and 14 from July 2007 through December 2008. Among these patients, 30 patients who were detected DVT on POD 4 were enrolled in this study. Thirty patients were divided into two groups according to the presence (n=11) or absence (n=19) of DVT on POD14. The DVT (-) group had a significantly longer activated partial thromboplastin time (APTT, median 31.4 s) on POD 1 than the DVT (+) group (28.5 s) (p<0.02). Multivariate logistic regression analysis revealed that APTT lower than 28.5 seconds on POD1 was considered to be independent risk factor significantly contributing to residual DVT (odds ratio 17.5, 95% confidential interval 2.0-295.4, p=0.02). These findings should provide useful information for understanding the interindividual difference of the efficacy of FPX after TKA or THA.

Contribution of nitric oxide produced by inducible nitric oxide synthase to vascular responses of mesenteric arterioles in streptozotocin-diabetic rats.

1. The functional changes in mesenteric arterioles of streptozotocin-induced diabetes were investigated by intravital microscopy. The mesentery was exteriorized from anesthetized rats, spread in a chamber, and superfused with Tyrode solution. All drugs tested were applied to the superfusing Tyrode solution. 2. Compared with age-matched controls, the diabetic rats showed enhanced vascular sensitivity to phenylephrine, an alpha(1)-adrenoceptor agonist. The preincubation of the mesentery with N(G)-nitro-l-arginine (l-NNA), a nitric oxide synthase (NOS) inhibitor, shifted the phenylephrine-concentration-response curves to the left in both the diabetic and control rats. Even in the presence of l-NNA, the sensitivity to phenylephrine was higher in the diabetic rats than in the control. 3. Acetylcholine relaxed the mesenteric arterioles in both groups, but to a significantly greater extent in the control than in the diabetic rats. However, the l-NNA-induced constriction of arterioles did not differ significantly between the groups. In contrast, the amplitude of the constrictions of mesenteric arterioles induced by S-ethylisothiourea, an inducible NOS (iNOS) inhibitor, was significantly greater in the diabetic rats than in the control. 4. Immunostaining of the mesentery with a specific antibody for iNOS revealed iNOS in the microvessels of only the diabetic rats. 5. These results suggest that constrictor responses to alpha(1)-adrenoceptor stimulation are sensitized in the mesenteric arterioles of STZ-diabetic rats, and that iNOS expressed in the arteriolar smooth muscle plays a role in suppressing the basal tone and the reactivity of the arterioles in STZ-diabetic rats.