QRS、QT、QTc及LVEF预测心源性猝死的价值分析

摘要 目的：探讨QRS时限值（QRS）、QT间期延长（QT）、QTc间期（QTc）及左室射血分数（LVEF）预测心源性猝死的价值分析。方法：选择2018年1月至2019年12月川北医学院附属医院心血管内科治疗的356例心源性猝死患者进行研究,设为病例组,并选择同期体检的健康人200例作为对照组,分析QRS、QT、QTc及LVEF水平变化情况及其预测价值。结果：病例组QRS、QTc水平显著高于对照组,QT、LVEF水平显著低于对照组,差异显著（P＜0.05）;轻度QRS、QTc显著低于中度、重度患者,QT、LVEF水平显著高于中度、重度患者;中度患者QRS、QTc显著低于重度患者,QT、LVEF水平显著高于重度患者,差异显著（P＜0.05）;ROC结果显示,QRS预测心源性猝死的AUC为0.989,灵敏度△为84.59%,特异度为87.68%,截断值为115.59ms;QT预测心源性猝死的AUC为0.944,灵敏度85.12%,特异度为88.45%,截断值为21.69ms;QTc预测心源性猝死的AUC为0.984,灵敏度为86.05%,特异度为88.61%,截断值为416.39ms,LVEF预测心源性猝死的AUC为0.997,灵敏度87.15%,特异度为89.05%,截断值为45.63%,（P＜0.05）。结论：QRS、QT、QTc及LVEF在心源性猝死患者中检查,可显著提高心源性猝死临床诊断效能。     

The influence of the reference electrode location on the M−wave characteristics in the quadriceps

IntroductionIn the compound muscle action potential (M wave) recorded using the belly-tendon configuration, the contribution of the tendon electrode is assumed to be negligible compared to the belly electrode. We tested this assumption by placing the reference electrode at a distant (contralateral) site, which allowed separate recording of the belly and tendon contributions.MethodsM waves were recorded at multiple selected sites over the right quadriceps heads and lower leg using two different locations for the reference electrode: the ipsilateral (right) and contralateral (left) patellar tendon. The general parameters of the M wave (amplitude, area, duration, latency, and frequency) were measured.Results(1) The tendon potential had a small amplitude (<30%) compared to the belly potential; (2) Changing the reference electrode from the ipsilateral to the contralateral patella produced moderate changes in the M wave recorded over the innervation zone, these changes affecting significantly the amplitude of the M−wave second phase (p = 0.006); (3) Using the contralateral reference system allowed recording of short-latency components occurring immediately after the stimulus artefact, which had the same latency and amplitude (p = 0.18 and 0.25, respectively) at all recording sites over the leg.ConclusionsThe potential recorded at the “tendon” site after femoral nerve stimulation is small (compared to the belly potential), but not negligible, and makes a significant contribution to the second phase of belly-tendon M wave. Adopting a distant (contralateral) reference allowed recording of far-field components that may aid in the understanding of the electrical formation of the M wave.     

Classifying behavior from short‐interval biologging data: An example with GPS tracking of birds

1. Recent advances in digital data collection have spurred accumulation of immense quantities of data that have potential to lead to remarkable ecological insight, but that also present analytic challenges. In the case of biologging data from birds, common analytical approaches to classifying movement behaviors are largely inappropriate for these massive data sets.
2. We apply a framework for using K‐means clustering to classify bird behavior using points from short time interval GPS tracks. K‐means clustering is a well‐known and computationally efficient statistical tool that has been used in animal movement studies primarily for clustering segments of consecutive points. To illustrate the utility of our approach, we apply K‐means clustering to six focal variables derived from GPS data collected at 1–11 s intervals from free‐flying bald eagles (Haliaeetus leucocephalus) throughout the state of Iowa, USA. We illustrate how these data can be used to identify behaviors and life‐stage‐ and age‐related variation in behavior.
3. After filtering for data quality, the K‐means algorithm identified four clusters in >2 million GPS telemetry data points. These four clusters corresponded to three movement states: ascending, flapping, and gliding flight; and one non‐moving state: perching. Mapping these states illustrated how they corresponded tightly to expectations derived from natural history observations; for example, long periods of ascending flight were often followed by long gliding descents, birds alternated between flapping and gliding flight.
4. The K‐means clustering approach we applied is both an efficient and effective mechanism to classify and interpret short‐interval biologging data to understand movement behaviors. Furthermore, because it can apply to an abundance of very short, irregular, and high‐dimensional movement data, it provides insight into small‐scale variation in behavior that would not be possible with many other analytical approaches.

     

On small-sample confidence intervals for parameters in discrete distributions

The traditional definition of a confidence interval requires the coverage probability at any value of the parameter to be at least the nominal confidence level. In constructing such intervals for parameters in discrete distributions, less conservative behavior results from inverting a single two-sided test than inverting two separate one-sided tests of half the nominal level each. We illustrate for a variety of discrete problems, including interval estimation of a binomial parameter, the difference and the ratio of two binomial parameters for independent samples, and the odds ratio.     

受损背根节神经元自发放电节律的整数倍模式及其动力学变化

本文记录了大鼠损伤背根节神经元的自发放电活动。采用背根节慢性压迫动物模型,记录慢性压迫手术后３－１０ｄ背根节的自发放电。在记录的１５６根纤维中,观察到１７根（占１１Ａ％）出现的动作电位峰峰间期以某一基础间期的整数倍模式出现的整数倍时间节律形式,其回归映射图为晶格状点阵结构,并且该时间形式受细胞膜上钠,钾通道的调控。     

In vitro determination of generation times for Entodinium exiguum, Ophryoscolex purkynjei and Eudiplodinium maggii

ABSTRACT. Most previously reported generation times for rumen ciliate protozoa are longer than would be required to prevent their being flushed out of the rumen. In an earlier study from this lab, using a sequential transfer procedure, generation times between 12 and 13 h were determined for both Epidinium caudatum and Entodinium caudatum . This would permit these species to be maintained in a rumen with a fluid volume turnover rate as rapid as twice a day. In this study, generation times were estimated for Entodinium exiguum (13.2 h), Eudiplodinium maggii (26.8 h), and Ophryoscolex purkynjei (29 h), by sequential transfer at both 12 and 24 h time periods. The generation time for E. exiguum is lower than reported for this and other Entodinium species as determined by logarithmic growth from a small inoculum, but similar to that obtained for Ent. caudatum using sequential transfer. Eudiplodinium maggii and O. purkynjei generation times are similar to previous estimates of 24- and 24–48 h, respectively. However, it was observed that after an adaptation period of 36 to 48 h (generally 3–4 transfers) cell concentrations decreased and generation times were markedly decreased, i.e. 12.2 h for Ent. exiguum , 15.0 h for E. maggii and 12.8 h for O. purkynjei . In a separate study, varying both the concentration of Epidinium and the quantity of substrate fed per cell had no effect on generation time.     

Statistical analysis of noninferiority trials with a rate ratio in small-sample matched-pair designs

Testing of noninferiority has become increasingly important in modern medicine as a means of comparing a new test procedure to a currently available test procedure. Asymptotic methods have recently been developed for analyzing noninferiority trials using rate ratios under the matched-pair design. In small samples, however, the performance of these asymptotic methods may not be reliable, and they are not recommended. In this article, we investigate alternative methods that are desirable for assessing noninferiority trials, using the rate ratio measure under small-sample matched-pair designs. In particular, we propose an exact and an approximate exact unconditional test, along with the corresponding confidence intervals based on the score statistic. The exact unconditional method guarantees the type I error rate will not exceed the nominal level. It is recommended for when strict control of type I error (protection against any inflated risk of accepting inferior treatments) is required. However, the exact method tends to be overly conservative (thus, less powerful) and computationally demanding. Via empirical studies, we demonstrate that the approximate exact score method, which is computationally simple to implement, controls the type I error rate reasonably well and has high power for hypothesis testing. On balance, the approximate exact method offers a very good alternative for analyzing correlated binary data from matched-pair designs with small sample sizes. We illustrate these methods using two real examples taken from a crossover study of soft lenses and a Pneumocystis carinii pneumonia study. We contrast the methods with a hypothetical example.     

Cryopreservation of canine spermatozoa: theoretical prediction of optimal cooling rates in the presence and absence of cryoprotective agents

In the present study a shape independent differential scanning calorimeter (DSC) technique was used to measure the dehydration response during freezing of ejaculated canine sperm cells. Volumetric shrinkage during freezing of canine sperm cell suspensions was obtained at cooling rates of 5 and 10 degrees C/min in the presence of extracellular ice and CPAs (6 different combinations of freezing media were used, ranging from a media with no CPAs, and those with 0.5%, 3%, and 6% glycerol and with 0.5% and 3% Me(2)SO). Using previously published data, the canine sperm cell was modeled as a cylinder of length 105.7mum and a radius of 0.32mum with an osmotically inactive cell volume, V(b), of 0.6 V(o), where V(o) is the isotonic cell volume. By fitting a model of water transport to the experimentally obtained volumetric shrinkage data the best fit membrane permeability parameters (L(pg) and E(Lp)) were determined. The "combined best fit" membrane permeability parameters at 5 and 10 degrees C/min for canine sperm cells in the absence of CPAs are: L(pg)=0.52x10(-15)m(3)/Ns (0.0029mum/min-atm) and E(Lp)=64.0kJ/mol (15.3kcal/mol) (R(2)=0.99); and the corresponding parameters in the presence of CPAs ranged from L(pg)[cpa]=0.46 to 0.53x10(-15) m(3)/Ns (0.0027-0.0031mum/min-atm) and E(Lp)[cpa]=46.4-56.0kJ/mol (11.1-13.4kcal/mol). These parameters are significantly different than previously published parameters for canine and other mammalian sperm obtained at suprazero temperatures and at subzero temperatures in the absence of extracellular ice. The parameters obtained in this study also suggest that optimal rates of freezing canine sperm cells ranges from 10 to 30 degrees C/min; these theoretical cooling rates are found to be in close conformity with previously published but empirically determined optimal cooling rates.     

Approaches to interval mapping of QTL in a multigeneration pedigree: the example of porcine chromosome 4

Quantitative trait loci (QTLs) have been mapped in many studies of F2 populations derived from crosses between diverse lines. One approach to confirming these effects and improving the mapping resolution is genetic chromosome dissection through a backcrossing programme. Analysis by interval mapping of the data generated is likely to provide additional power and resolution compared with treating data marker by marker. However, interval mapping approaches for such a programme are not well developed, especially where the founder lines were outbred. We explore alternative approaches to analysis using, as an example, data from chromosome 4 in an intercross between wild boar and Large White pigs where QTLs have been previously identified. A least squares interval mapping procedure was used to study growth rate and carcass traits in a subsequent second backcross generation (BC2). This procedure requires the probability of inheriting a wild boar allele for each BC2 animal for locations throughout the chromosome. Two methods for obtaining these probabilities were compared: stochastic or deterministic. The two methods gave similar probabilities for inheriting wild boar alleles and, hence, gave very similar results from the QTL analysis. The deterministic approach has the advantage of being much faster to run but requires specialized software. A QTL for fatness and for growth were confirmed and, in addition, a QTL for piglet growth from weaning at 5 weeks up to 7 weeks of age and another for carcass length were detected.     

Quality Control and Assurance: crucial for the sustainability of the applied phycology industry

The chemical and nutritional properties of microalgae are well known, which has led to an ever expanding industry for foods and dietary supplements both in terms of quantity and products. Little has been done to regulate or control quality and assurance in the applied phycology industry and it is known that it varies considerably. Nutritional aspects of produced biomass and consumption as dietary supplements have become issues of concern, especially since the industry is lucrative and fast growing. Various claims are made regarding dietary and food supplements that include health, nutrition, structure and functioning, many often unsubstantiated. Although quality is a subjective term many organisations are involved in testing, controlling and determining criteria. Today quality is more than just standards where it is an "integrated quality management approach" involving amongst others "hazard analyses and critical control points" (HACCP) practices. Microalgae are not recognised as a food or food supplement and they are also not categorised under herbals or botanicals, but as "other supplements". Produced microalgal biomass is subject to contamination from the entire range of contaminants and pathogens. Contamination of products by algal toxins in mixed culture populations also occurs. The industry has largely regulated itself, but there is considerable scope for improvement. There is a need for support and dissemination of information in the industry.