Assimilation of cholesterol by yeast strains isolated from infant feces and Feta cheese

Eight yeast strains isolated from infant feces and the traditional Greek Feta cheese, selected for their probiotic properties, were tested along with a commercially available strain of Saccharomyces boulardii for their ability to remove cholesterol from a growth medium (yeast extract glucose peptone broth) supplemented with 0.3% Oxgall. The amount of cholesterol removed during 72 h of growth at 37 degrees C revealed significant variations among the yeast strains examined. Two isolates from infant feces, namely Saccharomyces cerevisiae KK1 and Isaatchenkia orientalis KK5.Y.1 and one isolate from Feta cheese, namely S. cerevisiae 832, along with the commercial strain S. boulardii, were able to remove cholesterol from the growth medium after 48 h of incubation at 37 degrees C. However, Saccharomyces strains proved to be able to remove cholesterol even after 24 h of growth at 37 degrees C. The cholesterol removed from the growth medium was not metabolically degraded but was rather assimilated into the yeast cells. The ability to assimilate cholesterol in vitro and to tolerate low pH levels, gastric juice, and bile indicate that S. cerevisiae 832, and especially S. cerevisiae KK1 and I. orientalis KK5.Y.1 (being more bile and gastric juice tolerant because of their human origin) may be promising candidate strains for use as probiotics.     

Some probiotic properties of yeast isolates from infant faeces and Feta cheese

The use of modified atmospheres to prevent fungal growth and mycotoxin production in cheese was evaluated. Eight fungal species: Mucor plumbeus, Fusarium oxysporum, Byssochlamys fulva, B. nivea, Penicillium commune, P. roqueforti, Aspergillus flatus and Eurotium chevalieri were inoculated onto cheese and incubated under conditions of decreasing concentrations of O2 (5% to < 0.5%) and increasing concentrations of CO2 (20-40%). Fungal growth was measured by colony diameter and ergosterol content. All fungi examined grew in atmospheres containing 20% and 40% CO2 with 1% or 5% O2, but growth was reduced by 20-80%, depending on species, compared with growth in air. The formation of aflatoxins B1 and B2, roquerfortine C and cyclopiazonic acid was greatly decreased but not totally inhibited in these atmospheres. At 20% or 40% CO2 with < 0.5% O2, only B. nivea exhibited growth, which was very slow. Growth of F. oxysporum, B. fulca, P. commune and A. flavus showed good correlations between colony diameter and ergosterol content. However, for the other species correlations were inconsistent.     

D-STATCOM不平衡负荷补偿电流的优化设计

在介绍不平衡负荷的电纳补偿原理的同时,分析了其不足之处,即在负荷严重不平衡的情况 下,三相补偿装置分担的负荷不均衡,限制了装置的补偿能力,也容易导致一相或两相过流;针对不 平衡负荷补偿的特殊工况,提出了补偿电流优化设计的目标,即三相电流大小均衡。文中给出了补 偿电流优化设计的理论依据和前提条件:首先,通过选择合适的电路连接方式,电流是多样可选择 的;从数学上证明了提出的优化设计目标的合理性,并给出了优化补偿电流的计算方法。通过 MATLAB计算,与传统补偿思路进行了基波电流、电容电压波动等多项指标的比较,证明优化设 计原理在各项指标上部具有明显的优势。PSCAD仿真和10 kVA样机实验结果表明,优化设计原 理可以实现且效果良好。     

Urban heat island in southern Europe: The case study of Hania, Crete

The aim of the present paper is to analyze the results of the urban heat island research for a coastal densely built small Mediterranean town namely Hania, Crete, Greece. The specific research targets to verify the existence, the intensity, the size and the form of the urban heat island phenomenon in the specific region as well as to understand its correlation with the local weather conditions. Nine urban and three rural meteorological stations are used for this study. Temperature and relative humidity measurements are collected from May 26, 2007 until October 24, 2007. In parallel, meteorological data including wind speed and direction, barometric pressure, sunlight and precipitation for the specific region are collected and elaborated for cross-correlation with the appearance of the urban heat island (UHI) phenomenon. During summer period, where the temperature is high, the UHI takes its maximum intensity, of about 8 °C. Also, the form of the UHI is strongly influenced from the wind speed and direction. The northern winds expand the UHI front, while the western winds contribute to the UHI reduction. Finally the Discomfort Index (DI) is calculated for the 2007 summer period to indicate the outdoor living conditions.     

Characterization of the human SDHC gene encoding of the integral membrane proteins of succinate-quinone oxidoreductase in mitochondria

The neurological manifestations of multiple sclerosis (MS) have been considered to result from demyelination of axons with relative preservation of axonal integrity. This concept has been challenged recently by a landmark pathological study, published in the New England Journal of Medicine, which has demonstrated that axonal degeneration is also present. The authors of the study hypothesized that axonal degeneration is the pathological correlate of the irreversible neurological impairment in this disease. However, this hypothesis cannot be reconciled with the clinical results obtained with transcranial applications of AC pulsed electromagnetic fields (EMFs) of picotesla flux density which have shown rapid and sustained improvement of symptoms including normalization of evoked potential responses in patients with chronic progressive or secondary progressive MS without demyelinated areas first undergoing remyelination or transected axons undergoing regeneration. Biochemical studies have shown that MS patients are serotonergically depleted with the extent of cerebral depletion correlating with the degree of motor disability and a chronic progressive course. It is believed that progressive serotonergic neuronal atrophy with synaptic inactivation, not axonal degeneration, are the hallmarks of the disease and that administration of AC pulsed magnetic fields improves symptoms of MS partly through reactivation of serotonergic neurons and amplification of synaptic serotonergic transmission.     

执行器失效不确定时滞系统的指定衰减度鲁棒可靠控制

针对一类含有时变时滞的不确定参数线性系统,研究了在执行器发生故障情况下的鲁棒可靠控制器设计问题.系统中的参数不确定性满足广义匹配条件,时变时滞的大小及其变化率有界,并假设故障执行器元件的输出为零.经过适当的模型变换,将原系统的鲁棒指数镇定问题转化为另一个等价系统的鲁棒镇定问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMI)方法,分别给出了鲁棒可靠控制器存在的时滞无关和时滞相关充分条件.仿真结果表明了该控制器设计方法的有效性.     

ATP-dependent proteolysis in mitochondria. m-AAA protease and PIM1 protease exert overlapping substrate specificities and cooperate with the mtHsp70 system

To analyze protein degradation in mitochondria and the role of molecular chaperone proteins in this process, bovine apocytochrome P450scc was employed as a model protein. When imported into isolated yeast mitochondria, P450scc was mislocalized to the matrix and rapidly degraded. This proteolytic breakdown was mediated by the ATP-dependent PIM1 protease, a Lon-like protease in the mitochondrial matrix, in cooperation with the mtHsp70 system. In addition, a derivative of P450scc was studied to which a heterologous transmembrane region was fused at the amino terminus. This protein became anchored to the inner membrane upon import and was degraded by the membrane-embedded, ATP-dependent m-AAA protease. Again, degradation depended on the mtHsp70 system; it was inhibited at non-permissive temperature in mitochondria carrying temperature-sensitive mutant forms of Ssc1p, Mdj1p, or Mge1p. These results demonstrate overlapping substrate specificities of PIM1 and the m-AAA protease, and they assign a central role to the mtHsp70 system during the degradation of misfolded polypeptides by both proteases.