Parameters associated with residual insulin secretion during the first year of disease in children and adolescents with Type 1 diabetes mellitus

Factors associated with residual insulin secretion and spontaneous remission in Type 1 diabetic patients are important in the evaluation of treatment aimed at modifying the natural history of Type 1 DM. We investigated the effect of parameters at onset on residual beta cell function in 215 Type 1 DM children and adolescents. Blood gas analysis, HLA, GAD and IA-2 antibodies before the start of insulin treatment were recorded for each patient. Residual C-peptide secretion was assessed by the glucagon test, and parameters of metabolic control (HbA1c and insulin dose U kg(-1) day(-1)) were examined at disease onset and after 3, 6, and 12 months. Residual C-peptide secretion throughout the first year of disease was significantly reduced in patients with disease onset before age 5. Multiple regression analysis showed that low pH at onset showed a significant and independent association with reduced C-peptide at 3 months (p = 0.02) and that the detection of GAD antibodies had a significant independent association with decreased C-peptide secretion at 6 months of follow-up (p = 0.02). Insulin requirement was higher in the youngest patients group and in patients with GAD antibodies. Spontaneous insulin remission (HbA1c <6% and insulin <0.3 U kg(-1) day(-1)) occurred in 22/192 (11%) patients at 3 months of follow-up, in 15/190 (8%) patients at 6 months and in 8/169 (5%) patient at 12 months. Remission was more prevalent in older patients (p = 0.01) and in patients without detectable GAD antibodies: (14/64 vs 8/128, p = 0.001). Sex, IA-2 antibodies and HLA DR were not independently associated with C-peptide secretion, insulin requirement or remission in the first year of Type 1 DM. This study confirms the association of young age, severe acidosis at disease onset, and GAD antibodies with decreased residual beta-cell function and spontaneous remission during the first year of insulin treatment. These factors should be considered in trials evaluating therapies to retain beta-cell function and induce remission at and after disease onset.     

Evidence by allelic association-dependent methods for a type 1 diabetes polygene (IDDM6) on chromosome 18q21

Type 1 diabetes is a common polygenic disease. Fine mapping of polygenes by affected sibpair linkage analysis is not practical and allelic association or linkage disequilibrium mapping will have to be employed to attempt to detect founder chromosomes. Given prior evidence of linkage of the Jk-D18S64 region of chromosome 18q12-q21 to type 1 diabetes, we evaluated the 12 informative microsatellite markers in the region for linkage with disease by the transmission disequilibrium test (TDT) in a UK data set of type 1 diabetic families (n = 195). Increased transmission of allele 4 of marker D18S487 to affected children was detected (P = 0.02). Support for this was extended in a total of 1067 families from four different countries by isolating, and evaluating by the TDT, two novel microsatellites within 70 kb of D18S487. Evidence for linkage and association was P = 5 x 10(-5) and 3 x 10(-4), respectively. There was no evidence for increased transmission of associated alleles to nonaffected siblings. Analysis of an additional 390 families by the TDT did not extend the evidence further, and reduced support in the total 1457 families to P = 0.001 for linkage and P = 0.003 for association. However, evidence for linkage by affected sibpair allele sharing was strong (P = 3.2 x 10(-5)) in the second data set. Heterogeneity in TDT results between data sets was, in part, accounted for by the presence of more than one common disease-associated haplotype (allelic heterogeneity) which confounds the analysis of individual alleles by the TDT. Guidelines for strategies for the mapping of polygenes are suggested with the emphasis on collections of large numbers of families from multiple populations that should be as genetically homogeneous as possible.     

Color, iridescence, and thermoregulation in Lepidoptera

This paper examines evidence for the hypothesized connection between solar thermal properties of butterfly and moth (Lepidoptera) wings, iridescence/structural color, and thermoregulation. Specimens of 64 species of Lepidoptera were measured spectrophotometrically, their solar absorptances calculated, and their habitat temperatures determined. No correlation was found between habitat temperature and the solar absorptance of the wings. It was found, however, that the iridescent specimens exhibited, on average, substantially higher solar absorptance than noniridescent ones.     

Synthesis and Structural Analysis of Structured Triacylglycerols with CLA Isomers in the <Emphasis Type="Italic">sn</Emphasis>-2- Position

The present research deals with the chemical esterification of the sn-2- position of sn-1,3-diacylglycerol (sn-1,3-DAG) with 9cis,11trans (c9,t11) and 10trans,12cis (t10,c12) conjugated linoleic acid (CLA) isomers to obtain structured triacylglycerols (TAG); the sn-1,3-DAG substrates were produced from extra virgin olive oil by means of enzymatic reactions while CLA isomers were obtained using a three-step procedure based on alkaline hydrolysis of sunflower oil, urea purification of linoleic acid (LA) and alkaline isomerization of LA. The results showed good levels of CLA incorporation in structured TAG at the tested temperatures: 37.5% at 4 °C and 39.1% at 14 °C. To evaluate the incorporation of CLA isomers in sn-2- position of sn-1,3-DAG structural analysis of the newly synthesized TAG was carried out using an enzymatic and a chemical method. The results of the structural analysis also showed up the occurrence of acyl migration. The pancreatic lipase method allowed the direct determination of the fatty acid composition of TAG sn-2- position but this enzymatic method showed different results (p < 0.05) in respect to the chemical one; this occurrence could be due to an acylic specificity of the lipase. High incorporation of CLA isomers in sn-2- position of TAG was observed, 77.0% at 4 °C and 81.5% at 14 °C, considering the results of the chemical procedure.     

海洋菌株Mitsuaria sp. SH-50产嗜热性壳聚糖酶CsnSH50的酶学性质表征及其应用

实验室从中国海南滨海虾蟹养殖区泥土样品中筛选到一株高产壳聚糖酶的海洋菌株Mitsuaria sp. SH-50,优化后该菌株产酶时间仅为12 h,产酶活性可达26.6 U/mL。该研究对其胞外壳聚糖酶进行分离纯化和酶学性质表征并进行壳寡糖制备的小试放大试验,以期进一步明确该菌株在壳寡糖生产上的实际意义。结果表明：壳聚糖酶CsnSH50分子量约为41 ku,纯化后CsnSH50比酶活力为7 462.50 U/mg,最适反应pH值为4.5,温度为75 ℃,在pH值2.5~8.5及温度低于50 ℃条件下稳定性较好。最适条件下,稀释后CsnSH50的最大反应速率Vmax=29.41 U/mL,米氏常数Km=1.71 mg/mL,1 mmol/L的K+、Ca2+、Cu2+、Fe3+、Mn2+对CsnSH50的酶活力有明显正激活效应,10 mmol/L的Mn2+对其正激活效应可达412%。TLC和ESI-MS结果表明：CsnSH50水解壳聚糖的最终产物主要为壳二糖、三糖、四糖。小试放大试验结果显示：制备5%（m/V）壳寡糖溶液时,壳聚糖溶液的初始pH值3.5,温度75 ℃,水解120 min时壳寡糖产率达到92.1%,产物平均聚合度为10.2。综上,CsnSH50具有酶活性高、热稳定性好、耐酸等特性,同时是一种鲜有报道的嗜热性壳聚糖酶,具有良好的工业应用潜力。     

传热系统的最优设计

传热系统的最优设计成为当前化工过程最优化的重要研究课题之一,引起了国外很多研究者的兴趣。从Hwa1965年发表的利用可分规划(Separable programming)寻找传热系统的最优组合的论文算起,到目前为止已经发表了十多种组合方法。但是从公开发表的文献来看,还多处于探索性阶段,离实际应用还有一段距离。     

改进电子直线加速器束流品质的新方法

简单介绍了自适应前馈控制的工作原理、具体实现及其在速调管、微波枪和加速管上的应用,并对实现热阴极微波枪这种时变、非线性、大迟滞系统的控制作了重点介绍。     

复杂塔系统数学模型的稀疏矩阵解法

提出了一个具有复杂联接的精馏塔系统的模型,与通常的精馏塔不同,不仅维数增大,而且在物料平衡和焓平衡矩阵中出现了偏离三对角的元素.这就不能有效地利用通常的三对角矩阵的解法.本文采用Browne的解的格式,改进了他的收敛性判据,同时在算法和数据处理上采用了矩阵逆的消去形式和乘积形式.压缩了计算机的存贮,为大规模问题的计算提供了条件.用文献例题作为计算实例,结果十分吻合.