Redox control of exofacial protein thiols/disulfides by protein disulfide isomerase

Protein disulfide isomerase (PDI) facilitates proper folding and disulfide bonding of nascent proteins in the endoplasmic reticulum and is secreted by cells and associates with the cell surface. We examined the consequence of over- or underexpression of PDI in HT1080 fibrosarcoma cells for the redox state of cell-surface protein thiols/disulfides. Overexpression of PDI resulted in 3.6-4. 2-fold enhanced secretion of PDI and 1.5-1.7-fold increase in surface-bound PDI. Antisense-mediated underexpression of PDI caused 38-53% decreased secretion and 10-33% decrease in surface-bound PDI. Using 5,5'-dithio-bis(2-nitrobenzoic acid) to measure surface protein thiols, a 41-50% increase in surface thiols was observed in PDI-overexpressing cells, whereas a 29-33% decrease was observed in underexpressing cells. Surface thiol content was strongly correlated with cellular (r = 0.998) and secreted (r = 0.969) PDI levels. The pattern of exofacial protein thiols was examined by labeling with the membrane-impermeable thiol reactive compound, 3-(N-maleimidylpropionyl)biocytin. Fourteen identifiable proteins on HT1080 cells were labeled with 3-(N-maleimidylpropionyl)biocytin. The intensity of labeling of 11 proteins was increased with overexpression of PDI, whereas the intensity of labeling of 3 of the 11 proteins was clearly decreased with underexpression of PDI. These findings indicated that secreted PDI was controlling the redox state of existing exofacial protein thiols or reactive disulfide bonds.     

Identification and characterization of a lysis module present in a large proportion of bacteriophages infecting Streptococcus thermophilus

A lysis module encoded by the temperate bacteriophage phiO1205 was identified. This lysis module contains a lysin gene, designated lyt51, and two putative holin-encoding genes, designated lyt49 and lyt50. lyt51 encodes a lytic enzyme specifically directed against streptococcal cell walls. Similar to other phage-encoded lysins, Lyt51 appears to have a modular design in which the N-terminal portion corresponds to its enzymatic activity while the C-terminal region is responsible for its substrate binding specificity. The two putative holin-encoding genes, lyt49 and lyt50, located immediately upstream of lyt51, were identified on the basis of their homology to other identified holin-encoding genes. Expression of lyt49 or lyt50 in Escherichia coli was shown to cause cell death and leakage of the intracellular enzyme isocitrate dehydrogenase into the growth medium without apparent lysis of the cells. Southern blotting experiments demonstrated that at least one of the three components of the identified lysis module is present in all members of a large collection of bacteriophages, indicating that components of this lysis module are widespread among bacteriophages infecting Streptococcus thermophilus.     

Crosstalk degradation caused by optical amplification in amultichannel FSK heterodyne system

The crosstalk degradation caused by an optical amplifier in a four-channel FSK (frequency-shift-keyed) heterodyne communication system is measured. A bit error rate (BER) floor of 3×10^-4 is observed when the channels are spaced by 200 MHz, FSK modulation at 45 Mb/s, and when the optical input signal is large enough such that the gain is compressed by 2 dB relative to its small-signal value. The receiver is substantially improved by reducing the optical power amplifier input. However, the sensitivity increases only to a maximum value beyond which it degrades as the optical power of the demodulated channel becomes small relative to the noise of the optical amplifier. The combined effect of the crosstalk and the amplifier noise yields an optimum sensitivity of 250 photons/b for BER=10^-9. This result is 5 dB poorer than the sensitivity obtained in the absence of an optical amplifier     

心电图仪设计综述

介绍了心电图仪(ECG或EKG)的基本架构及心电信号的电子测量和显示的基本原理,探讨了ECG设备的模拟前端(AFE)及信号通道对心率信号实现数字化的问题,并讨论了各种ECG应用,包括自动体外除颤仪(AED)、病人监护仪和高端诊断型ECG及其所提供的多种功能。     

Telerehabilitation: Expanding access to rehabilitation expertise

The potential of modern telecommunications and computing technologies as tools in the delivery and evaluation of assistive technology (AT) has been discussed and has been termed telerehabilitation. The problems of providing AT in rural areas parallels the delivery of health care to rural areas where the proportion of people with chronic illnesses is higher and the means to pay for them is reduced. Large distances mean long travel times, increasing costs associated with any service delivery, and consuming valuable time skilled professionals could be using to provide services elsewhere. The technology available for practising telerehabilitation is significant and expanding at a rapid rate. Currently, plain old telephone systems (POTS) and broad-band videoconferencing equipment, Internet and World Wide Web, and embedded processor systems are most widely available. These technologies continue to evolve as well as emerging technologies such as wearable sensors that will have telehabilitation applications. Issues of payment, safety liability, and licensure need to be resolved, as legislation lags the development of new technologies     

The relationship between clients' expected and actual treatment duration.

Investigated the relationship of clients' expected and actual treatment duration in 148 outpatients (mean age 27 yrs) treated by 20 therapists. Data from questionnaires suggest that clients expected and attended a relatively low number of visits; these patterns were discrepant with the therapists' duration preferences. A stepwise regression analysis indicated that clients' expected number of visits was the only variable that incrementally increased the predictability of client visits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formation of artifact methylmercury during extraction from a sediment reference material.

We examined monomethylmercury (MMHg) in sediment reference material IAEA-405 and sediments from Long Island Sound. MMHg was extracted by both aqueous distillation and leaching with dilute solutions of nitric acid. MMHg was formed from both ambient and added inorganic mercury in extracts of IAEA-405 by either technique. Artifact MMHg in IAEA-405 was related linearly with ambient reactive mercury (HgR) in leachates having > 1.2 M acid, but little or no artifact was measured in less acidic extracts. Addition of potassium chloride enhanced extraction of HgR from LAEA-405 but had no effect on artifact MMHg for each leachate molarity tested. Mercury methylation occurred in solution and was a function of both the availability of HgR and a methylation potential, being limited by HgR in less acidic solutions (0.5-1.2 M) and by the methylation potential in more acidic ones (> 1.2 M). Formation of artifact MMHg in Long Island Sound sediments was inconclusive, but additions of inorganic mercury demonstrated that a potential exists. A potential for abiotic mercury methylation seems always present in sediment, and the availability of HgR appears to control MMHg production under environmental conditions. Abiotic methylation of mercury may occur in environs where the reactivity of inorganic mercury is enhanced, such as river-seawater mixing zones.