The role of alpha-amylase in the perception of oral texture and flavour in custards

The role of salivary alpha-amylase in odour, flavour, and oral texture sensations was investigated in two studies in which the activity of salivary amylase present in the mouth of human subjects was either increased by presenting custards with added alpha-amylase or decreased by presenting custards with added acarbose, an amylase inhibitor. For starch-based vanilla custard desserts, amylase resulted in increased melting and decreased thickness sensations, whereas acarbose had the opposite effect, i.e., decreased melting and increased thickness. Other affected attributes included creamy mouth feel, creamy after feel, and fatty after feel. Creaminess, which is considered to be a highly desirable food quality, decreased by as much as 25% with added amylase and increased by as much as 59% with added acarbose. Neither additional amylase nor acarbose affected sensations for a nonstarch-based carboxy methylcellulose (CMC) vanilla custard dessert. This indicates that the effects of amylase on viscosity-related sensations of starch-based custards, such as perceived melting and thickness, are caused by amylase-induced breakdown of starch. Partial Least Square (PLS) analysis indicated that the effects of amylase and acarbose on perceived creaminess are not only driven by their effects on perceived melting and thickness, but also by their effects on perceived flavour.     

Microdialysis study of release of adenine nucleotide breakdown products into the myocardial intercellular space during ischemia and reperfusion

Laboratory of Experimental Pharmacology, and Laboratory of Experimental Pathology of the Heart, Institute of Experimental Cardiology, All-Union Cardiologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Smirnov). Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 9, pp. 278–280, September, 1990.     

The aerobic energy metabolism of the juvenile Fasciola hepatica

Juvenile Fasciola hepatica were isolated immediately after in vitro emergence from the metacercarial cysts and incubated with uniformly labelled glucose. Under aerobic conditions, carbon dioxide was the main end product of glucose breakdown. In the absence of oxygen, glucose was fermented mainly to propionate and acetate in a molar ratio of 2 : 1, with lactate as a minor product. This anaerobic end-product pattern closely resembles that of the adult liver fluke. In the presence of oxygen and 1 mM cyanide, lactate accumulated. The difference between anaerobic glucose breakdown and that in the presence of cyanide is explained by an inhibitory effect of cyanide on the malic enzyme (EC 1.1.1.40) of the juvenile mitochondria. A substantial Pasteur effect is calculated from these incubations. The oxygen consumption of the juveniles was completely cyanide-sensitive. From these results it is concluded that in aerobic conditions the juvenile liver flukes have an aerobic energy metabolism. Since they can survive prolonged periods of anaerobiosis, they should be called facultative anaerobes.     

In-situ evaluation of barrier-cream performance on human skin using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was used to evaluate the effect of barrier creams (skin protective creams) on human skin. A Nd: YAG laser at 1,064 nm was used with a pulse energy of 100 mJ. A method was developed to measure the effectiveness of barrier creams against zinc ion absorption from aqueous zinc chloride solution and oil paste zinc oxide, which represent model hydrophilic and lipophilic metal compounds, respectively. Zinc was chosen since it posed no risk to human skin. 3 representative commercial barrier creams advertised as being effective against lipophilic and hydrophilic substances were evaluated by measuring zinc absorbed through the stratum corneum. 4 consecutive skin surface biopsies (SSB) were taken from biceps of the forearms of 6 volunteers at time periods of 0.5 h and 3 h after application of the protective cream. Results were compared with control skin where no barrier cream was used. The zinc atomic emission line at 213.9 nm was selected. Gate delay and gate width time was optimized to obtain the best signal-to-noise ratio (SNR) and precision. This method provided a facile and rapid screening of the effectiveness of skin barrier creams against zinc ion penetration. The barrier creams were shown to provide appreciable protection against the penetration of both ZnCl2 and ZnO into the skin.     

锰 铬对体外培养小鼠卵母细胞减数分裂的影响

采用卵母细胞体外培养的方法 ,研究了硫酸锰、氯化铬对小鼠卵母细胞的成熟和减数分裂的影响。结果表明 ,二者均能抑制体外培养卵母细胞的第一极体释放 ,降低体外培养卵母细胞的存活率 ,在培养 8h时都能够抑制卵母细胞的生发泡破裂。实验结果还显示 ,氯化铬比硫酸锰对卵母细胞的损伤作用更大。提示 ,硫酸锰和氯化铬都可以破坏卵母细胞的成熟和减数分裂 ,有明显的生殖毒性。     

Variants of the receptor/channel clustering molecule gephyrin in brain: Distinct distribution patterns,developmental profiles,and proteolytic cleavage by calpain

The postsynaptic molecule gephyrin is involved in clustering neurotransmitter receptors. To test for protein variants that correspond to alternatively spliced gephyrin mRNAs, antibodies were made against 1) an amino-terminal domain of gephyrin (GN_N) and 2) its invariant carboxy-terminus (GN_C). Both antibodies recognized an antigen with the expected molecular weight of 93–95 kDa in rat and human brain tissue, as well as five additional proteins between 90 and 108 kDa. Most of these variants were found distributed throughout the brain, and their developmental profiles paralleled those of synaptic markers. Interestingly, the pattern of antigens immunostained across brain regions by anti-GN_N was markedly distinct from that labeled by anti-GN_C, a difference consistent with carboxy-terminal modification. In control experiments in which hippocampal membranes were treated to activate endogenous proteases, there was no evidence that certain gephyrin variants originate from proteolysis. A subset of the antigens was, however, rapidly degraded during the treatment. A corresponding production of stable, carboxy-terminal gephyrin fragments of 48–50 kDa occurred within 1 min of proteolytic activation and was blocked by the selective calpain inhibitor CX295. These findings suggest that multiple gephyrin proteins are active in the brain and that some of their roles may require functional modulation by limited proteolysis. J. Neurosci. Res. 49:381–388, 1997. © 1997 Wiley-Liss, Inc.     

贝尔克血透机常见故障维修

我院自2006年起投入使用5台贝尔克血透机,最近一段时间,这批机器出现故障较为频繁。现结合维修经过总结了故障原因和维修经验．并提出维护保养的方法。     

The energy metabolism of Fasciola hepatica during its development in the final host

Mature liver flukes, Fasciola hepatica, of different ages were isolated from the bile ducts of experimentally infected rats. Their energy metabolism was studied during aerobic incubation with [6-14C]glucose. The results showed that the aerobic potentials of the parenchymal liver flukes are not lost immediately after arrival in the bile ducts, but in a later phase. During the development of the newly excysted juvenile into the mature adult the major part of ATP production in aerobic incubations is successively contributed by three different pathways of glucose breakdown. The Krebs cycle, which is by far the main energy-yielding pathway of the juvenile fluke, is gradually replaced by aerobic acetate formation and, finally, by the anaerobic dismutation reactions of the adult liver fluke. This observed decrease in Krebs-cycle activity per mg protein is not the result of a decrease in activity per individual fluke. The Krebs-cycle activity per fluke actually increases enormously during its whole development. This indicates that the aerobic potential of adult F. hepatica is not just a remnant of earlier aerobic stages but that classical, mammalian type mitochondria are produced during the entire development of the fluke. Calculations are presented which demonstrate that the Krebs-cycle activity of the developing F. hepatica is directly proportional to the surface area of the fluke. This supports our view that Krebs-cycle activity is limited by the diffusion of oxygen and can only occur in the outer layer of the liver fluke during its entire development in the final host.