Noninvasive determination of cardiac output using single breath CO2 analysis

OBJECTIVE: To examine the utility of single breath CO2 analysis as a noninvasive measure of cardiac output. SETTING: An animal laboratory in a university-affiliated medical center. DESIGN: A prospective, animal cohort study comparing 21 parameters derived from single breath CO2 analysis with cardiac output determined by an ultrasonic flow probe. SUBJECTS: Six healthy adult sheep. METHODS: The single breath CO2 analysis station consists of a mainstream capnometer, a variable orifice pneumotachometer, a signal processor, and computer software with capability for both on- and off-line data analysis. Twenty-one derived components of the CO2 expirogram were evaluated as predictors of cardiac output. Cardiac output was manipulated by successive injections of a hydraulic constrictor placed around the inferior vena cava. MEASUREMENTS AND MAIN RESULTS: Thirty-four measurements of cardiac output were available for comparison with derived variables from the CO2 expirogram. Stepwise linear regression identified two variables that were most predictive of cardiac output: a) the angle between the slope lines for phase II and III of the CO2 expirogram divided by the volume of CO2 per breath (angle/mL CO2); and b) the slope of phase II. The multivariate equation was highly statistically significant and explained 94% of the variance (adjusted r2 = .94, p < .0001). The bias and precision of the calculated cardiac output were .00 and .23, respectively. The mean percent difference for the cardiac output estimate derived from the single breath CO2 analysis station was 0.36%. CONCLUSIONS: Our data indicate that analysis of the CO2 expirogram can yield accurate information about the cardiovascular system. Specifically, two variables derived from a plot of expired CO2 concentration vs. expired volume predict changes in cardiac output in healthy adult sheep with an adjusted coefficient of determination of .94. Prospective application of this technology in the setting of lung injury and rapidly changing physiology will be essential in determining the clinical usefulness of the technique.     

IL-10 inhibits alloreactive cytotoxic T lymphocyte generation in vivo

In this report, we present evidence that the CTL response directed against MHC Class I allo-determinants can be inhibited as a result of IL-10 expression in vivo. The presence of localized IL-10 secretion at the site of allogeneic tumor cell challenge resulted in marked inhibition of the CTL response and allowed growth of the tumor in the allogeneic host. Using purified CD4+ T cells from mice immunized in the presence or absence of IL-10, we have shown that the loss of alloreactivity as a consequence of IL-10 expression results from the inhibition of CD4+ T cell function. The expression of either IL-2 or IFN-gamma with IL-10 locally at the time of allogeneic cell challenge completely restored CTL alloreactivity, suggesting that the action of IL-10 could be bypassed by providing helper T lymphocyte-derived cytokines of the Th1 type at the site of immunization. Inhibition of alloreactivity by IL-10 was observed using either purified macrophages or dendritic cells as APC in an in vitro assay. Thus, the expression of IL-10 following antigenic challenge (such as that observed in Th2-like immune responses) may profoundly limit the ability for generating functional CTL in vivo.     

Hyperthermia following MDMA administration in rats: effects of ambient temperature, water consumption, and chronic dosing

In two experiments it was found that the hyperthermia which follows MDMA ("Ecstasy") results from an interaction of direct pharmacological effect of the drug and the prevailing environmental conditions in which it is administered. In Experiment 1, rats given fixed doses of either 2.5, 5.0 or 7.5 mg/kg MDMA or saline were injected on different days at ambient temperatures (Ta's) of 11, 24, and 30 degrees C. At each Ta drinking water was freely available following dosing on one session and temporarily unavailable on a second. The hyperthermic and hyperkinetic responses were monitored using remote biotelemetry. Experiment 2 used a between-subject design in which each group of rats received a standard 7.5 mg/kg dose of MDMA administered at only one of the three levels of Ta(24 degrees C) and at only one level of the water-availability factor. Dosing in some groups was continued for a further 13 days to test for tolerance or sensitization effects. Ambient temperature significantly affected the magnitude of the hyperthermia but not the hyperkinesis. Water deprivation during the drugged period significantly augmented the hyperthermia, but only in the high Ta (30 degrees C.) condition. Chronic dosing produced sensitization of both hyperthermic and hyperkinetic responses. The findings indicate that ambient temperature, water consumption and frequency of drug use affect the hyperthermia which follows MDMA administration.     

The cortisol response to psychological stress in temporomandibular dysfunction

Recombinant antibody fragments can be produced in large quantities using bacterial expression systems and could potentially be useful for the generation of biofilters for the selective removal of viral particles from fluids. A human single chain-Fv antibody library, derived from synthetic repertoires of germ line VH-gene segments rearranged in vitro and paired to a single light chain (Nissim et al., 1994, EMBO J., 13, 692-698), has recently been used to isolate hundreds of different binding specificities by panning with antigen. Antibodies from this library typically have affinities in the 10(6)-10(7) M-1 range. Occasionally, better binders are isolated but at other times the affinities recovered are poor. In the latter situation binding cannot be detected with soluble antibodies, but only by high-avidity display of multiple copies of antibodies on phage. By panning with human cytomegalovirus (HCMV)-coated immunotubes, we have isolated a number of antibody clones from this library that bound to the antigen only if displayed on the filamentous phage, but not in soluble form. One of these clones was selected for an affinity maturation procedure, achieved by combinatorial mutagenesis of the complementarity determining region 3 (CDR3) of the antibody light chain, followed by selection of the resulting library for HCMV binding. By this means, we were able to isolate a number of binders, some of which exhibited specific HCMV binding in soluble form. The clone that gave the strongest ELISA signal was expressed in bacteria, purified in solution, characterised using a novel capture methodology with surface plasmon resonance detection on a BIAcore instrument and used for the production of an immunofilter for the removal of HCMV form human serum. The filter removed more than 99% of applied HCMV in 10 min circulation time, while the amount of HCMV retained non-specifically in a cartridge derivatised with a non-specific antibody was less than 10% under similar conditions.     

空间级联可调谐光滤波器方式实现光分插复用器

提出一种采用空间级联可调谐光滤波器方式实现的OADM.该器件不但具有集成度高、体积小、插入损耗低、信道间插入损耗差异小的特点,而且能够在控制电路的作用下灵活选择上下路波长及其数量,为构建灵活、高性能的WDM网络提供了选择.     

Proton MR spectroscopy and magnetization transfer ratio in multiple sclerosis: correlative findings of active versus irreversible plaque disease

PURPOSE: To characterize plaques of multiple sclerosis (MS) using both proton MR spectroscopy and magnetization transfer (MT) imaging. METHODS: The magnetization transfer ratio (MTR) was calculated from two series of three-dimensional gradient-recalled acquisition in the steady state (GRASS) images obtained with and without an MT saturation pulse. Proton spectra were acquired using the point-resolved spectroscopy (PRESS) sequence with a voxel size of 1.5 x 1.5 x 1.5 cm3. A total of 28 spectra were obtained in 13 patients who had clinically definitive MS. The spectra were analyzed together with the MTR. RESULTS: A positive relationship was found between the N-acetylaspartate (NAA)/creatine (Cr) ratio and the MTR in MS plaques, whereas no significant correlation was found between the metabolite ratios and the signal intensity on fast spin-echo T2-weighted MR images. CONCLUSION: Small changes in the MTR of MS plaques relative to the MTR of normal white matter may reflect inflammatory changes and edema, whereas larger changes in MTR correlate with decreased NAA/Cr ratio and therefore suggest demyelination and irreversible damage from chronic MS plaques.     

不同波长响应的Y2O2S:Er3+,Yb3+上转换发光材料的光谱特性

以Y2O2S为基质材料、Er2O3为激活剂、Yb2O3为敏化剂,采用固相反应法制备Y2O2S:Er3+,Yb3+上转换发光材料.采用X射线粉末衍射分析和荧光光谱分析表征样品的结构和发光性能,并分析上转换发光机理.结果表明:在980 nm和1 550 nm红外光激发下,样品发出源于Er3+的2H11/2→4I15/2、4...     

印染废水超滤工艺中操作方式对过滤速率的影响

对某印染厂废水处理站排水进行了回用处理研究.在恒压条件下,采用聚乙烯(PE)中空纤维膜,进行间歇曝气扫流过滤,分析了不同操作方式对超滤速率变化的影响.结果表明曝气在超滤中能够起到防止污染的作用,解除作用于颗粒上的抽吸力后再采用曝气扫流,则能达到更好的扫流效果.周期运行与非周期运行之间的差距较大,按"曝气过滤-暂停-曝气扫流"<"不曝气过滤-暂停-曝气扫流"<"连续曝气扫流"的顺序阻力增大,因此采用周期运行方式在一定程度上可以恢复超滤速率.印染废水过滤中,在抽吸压力小于0.08 MPa的范围内,可以不考虑沉积物的压缩性.