Genotype polymorphisms of genes regulating nitric oxide synthesis determine long-term arteriovenous fistula patency in male hemodialysis patients.

OBJECTIVES: Nitric oxide (NO) is a pivotal vasoactive substance modulating arteriovenous fistula (AVF) patency for hemodialysis (HD). Since genetic background could be the predicting factor of AVF malfunction, we aimed to investigate whether the NO-related genotype polymorphisms determine AVF survival rates. METHODS: This is a retrospective, observational, multi-center study involving eight HD units in Taiwan, enrolled 580 patients initiating maintenance HD via AVFs. Genotype polymorphisms of NO-biosynthesis regulating enzymes (DDAH-1, DDAH-2, eNOS and PRMT1) were compared between HD patients with (n = 161) and without (n = 419) history of AVF malfunction. Subgroup analyses by gender were performed to evaluate the genetic effect in difference sexes. RESULTS: In overall population, statistically significant associations were not found between AVF malfunction and the genetic polymorphisms. In the male subgroup (n = 313), a single nucleotide polymorphism (SNP) of PRMT1, rs10415880 (IVS9-193 A/G), showed a significant association with AVF malfunction. Male patients with AA/AG genotype had inferior AVF outcomes compared to GG genotype, regarding primary patency (70.6% vs. 40.9%, p = 0.001), assisted primary patency (81.0% vs. 58.4%, p < 0.001) and secondary patency (83.7% vs. 63.3%, p < 0.001) at a 5-year observation period. From multivariate Cox regression model, the AA/AG genotypes of PRMT1 were an independent risk factor for AVF malfunction in men (HR: 4.539, 95% CI 2.015-10.223; p < 0.001). However, such associations were not found in women. CONCLUSIONS: rs10415880, the SNP of PRMT1 could be a novel genetic marker associated with AVF malfunction risk in male HD patients. Those with AA and AG genotypes of rs10415880 may predict a poorer long-term patency of AVF.

Energy harvesting thermoelectric generators manufactured using the complementary metal oxide semiconductor process.

This paper presents the fabrication and characterization of energy harvesting thermoelectric micro generators using the commercial complementary metal oxide semiconductor (CMOS) process. The micro generator consists of 33 thermocouples in series. Thermocouple materials are p-type and n-type polysilicon since they have a large Seebeck coefficient difference. The output power of the micro generator depends on the temperature difference in the hot and cold parts of the thermocouples. In order to increase this temperature difference, the hot part of the thermocouples is suspended to reduce heat-sinking. The micro generator needs a post-CMOS process to release the suspended structures of hot part, which the post-process includes an anisotropic dry etching to etch the sacrificial oxide layer and an isotropic dry etching to remove the silicon substrate. Experiments show that the output power of the micro generator is 9.4 mW at a temperature difference of 15 K.