Effect of heat acclimation on sweat minerals

PURPOSE: This study examined the impact of 10 d of exercise-heat acclimation on sweat mineral concentrations. METHODS: Eight male subjects walked on a treadmill at 3.5 mph, 4% grade for 100 continuous minutes or until rectal temperature reached 39.5 degrees C on 10 consecutive days in an environmental chamber set at 45 degrees C, 20% relative humidity. Arm sweat samples were collected during the first 30 min of exercise-heat stress on days 1 and 10 using a polyethylene arm glove. RESULTS: Final core temperature and HR values were significantly lower (P < 0.05) on day 10 versus day 1. Whole-body sweating rates increased by approximately 6% (P = 0.12). Sweat sodium concentration on day 10 (36.22 +/- 7.22 mM) was significantly lower than day 1 (54.49 +/- 16.18 mM) (P < 0.05). Sweat mineral concentrations of calcium (approximately 29%), copper (approximately 50%), and magnesium (approximately 43%) were also significantly lower on day 10 versus day 1 of heat acclimation (P < 0.05). A trend for lower sweat iron (approximately 75%; P = 0.07) and zinc (approximately 23%; P = 0.10) concentrations were observed from day 1 to day 10. The estimated hourly sweat mineral losses (arm concentration x whole-body sweat rate) were reduced for calcium (approximately 27%), copper (approximately 46%), and magnesium (approximately 42%) (P < 0.05), but not iron (75%) or zinc (approximately 16%) (P > 0.05), from day 1 to day 10. CONCLUSION: Exercise-heat acclimation conserves arm sweat mineral concentrations and possibly whole-body sweat losses of calcium, copper, and magnesium, and may reduce sweat iron and zinc concentrations.     

Role of TNF block genetic variants in HIV-associated sensory neuropathy in black Southern Africans

HIV-associated sensory neuropathy (HIV-SN) is a common neurological complication of HIV infection. The TNF block is a region within the central MHC that contains many immunoregulatory genes. Polymorphisms and haplotypes of the TNF block have been associated with increased risk of HIV-SN in Asians and whites. Here we investigated genetic associations with HIV-SN in 342 black Southern Africans (190 cases and 152 neuropathy-free controls) using single nucleotide polymorphisms (SNPs) spanning the TNF block and a set of haplotypes defined by 31 SNPs in Asian and white populations (denoted FVa). We included population-appropriate tagSNPs derived from an African population (Yoruban, YRI, HapMap) and derived extended haplotypes comprising 61 SNPs (denoted FVa_ext b). We found no association between HIV-SN and carriage of two SNPs (TNF-1031/rs1799964*C and BAT1 (intron10)/rs9281523*C) associated with HIV-SN in whites and Asians. Additionally, a haplotype containing TNF-1031/rs1799964*C associated with increased risk of HIV-SN in Asians, but was not present in this African population. However, alleles of seven SNPs associated with reduced risk of HIV-SN (corrected for age, height and multiple comparisons). These were rs11796*A, rs3130059*G, rs2071594*C, NFKBIL1-62/rs2071592*A, rs2071591*A, LTA+252/rs909253*G, rs1041981*C. One haplotype (FV18_ext1), not containing these alleles, was associated with increased risk of HIV-SN after correction for age, height and multiple comparisons. Our results confirm the involvement of genes in the TNF block in altering risk for HIV-SN, but genotypes critical in this African population differed from those affecting HIV-SN in whites and Asians. These differences support the need for genetic association studies in diverse populations.     

成纤维细胞生长因子对兔纤维环细胞转化生长因子β2的调节

目的:观察成纤维细胞生长因子对培养兔纤维环细胞转化生长因子β2表达的调节作用。方法:实验于2005-03/2006-04在华中科技大学同济医学院附属协和医院骨科实验室完成。培养4月龄雌性日本大白兔的纤维环细胞,在每次换液时加入成纤维细胞生长因子100μg/L,铺满后收集细胞,作纤维环细胞转化生长因子β2常规免疫组织化学研究,细胞呈棕黄色染色为阳性表达信号,同时为进一步明确纤维环细胞转化生长因子β2的定位进行免疫胶体金标记电镜观察。结果:光镜下细胞明显呈棕色,电镜下细胞膜表面有明显的胶金颗粒粘附。结论:成纤维细胞生长因子能促进纤维环细胞转化生长因子β2的表达。