In vitro velocity measurements down strem from the lonescu-Shiley aortic bioprosthesis in steady and pulsatile flow

Velocity measurements were made in vitro using laser Doppler anemometry (LDA) downstream from an lonescu-Shiley (IS) bioprosthetic aortic heart valve. Velocity measurements were made in both steady and pulsatile flow. A systematic, flow mapping approach to the measurement methodology showed that the IS valve generated a large jetlike flow constriction. The acceleration ratio, defined as the maximum mean velocity for the IS valve divided by that for no valve obstructing the flow, was as high as 2·4 for steady flow and 2·6 for pulsatile flow. It was concluded that the IS valve generated a flow quite unlike that observed by other in vestigators for the natural human aortic valve, after which the leaflet design of the IS valve was modelled. In addition, a comparative analysis of steady and pulsatile results was undertaken. It was found that the pulsatile flow results for the systolic ejection interval could be divided into three phases, denoted early, mid, and late systole, as defined by the flow structure at the data plane location. Only during midsystole were the pulsatile flow results approximated by the steady flow results. Also, it was found that the magnitude of the flow disturbance measured in steady flow tended to be an upper bound on that measured for pulsatile flow.     

A fast perfusion system for single cell physiology optimized for microscopes with water immersion objectives

A perfusion system was constructed which allows the fast application of different solutes underneath a water immersion objective. The perfusion system is mounted into the immersion objective by milling a slot into the frontal metal plate of the lens holder. It consists of a five-channel pipette fixed to the objective and solution reservoirs gated by computer controlled magnetic valves. Up to five different solutions can be applied to the specimen under study. The solution between objective and specimen is completely exchanged after 1–2 s as determined from fluorescence measurements. This arrangement is optimized for [Ca²⁺] measurements with a fluorescence measurement system in tissue slices, where upright microscopes are required. It offers the advantage of saving a micromanipulator for the perfusion pipette and facilitates a fast, reproducible and precise positioning of the perfusion system.     

Physical parameters in Japanese newborns

Summary A total of 19 physical parameters of the head, face, chest, and the fingers were examined in Japanese 50 male and 50 female newborns, measured 8 to 64 hr after birth. Exceptional values were excluded referring to the estimated mean and standard deviations. Normal values are presented as mean ±2 S.D. for each sex. As compared with Caucasian newborns, the Japanese newborns showed longer inner canthal and shorter outer canthal distances, shorter ear lengths, and longer palm and middle finger lengths.     

Pretherapeutic flow cytometric DNA investigations in radiotherapy patients with maxillo-facial carcinomas

In order to analyze the possible meaning of cellular DNA content and cell cycle phases for the radiosensitivity and the prognosis of human malignant tumors, flow cytometric measurements have been performed in biopsies of 131 patients with histologically proven squamous cell carcinomas of the maxillo-facial region. In two-thirds of the patients (88/131; 67%), aneuploid tumor cell lines have been found, only 33% (43/131) had a diploid DNA distribution pattern. The average DNA index (DI) of the aneuploid carcinomas was 3.4 +/- 0.6 (normal nonmalignant tissue DI = 2.0). The frequency of S-phase cells, which represents the "proliferative activity", was between 4.8 and 63.2%, regardless of the ploidy stages. The aneuploid carcinomas had about twice as many S-phase cells (mean 23.7 +/- 11.8%) than diploid tumors (mean 12.7 +/- 4.8%). Mean survival for patients with diploid carcinoma and aneuploid carcinoma was 12 and 9.5 months, respectively. Concerning the relationship of S-phase frequency and survival times in our material there was a high negative statistical correlation (Spearman-Rank test) in patients with diploid carcinomas. A high S-phase fraction resulted in short survival times. No correlation was found in the aneuploid carcinomas: patients with tumors in high S-phase values in their biopsies showed no difference in prognosis in comparison to tumors with lower S-phase fractions.     

农村居民吸烟行为的危险因素探讨

目的：调查农村居民吸烟情况及其危险因素。方法：通过整群抽样方法调查了12696名15岁以上农村居民的吸烟情况,同时收集其他相关信息。利用SAS软件包对这些资料进行卡方检验及logistic回归等分析。结果：观察烟者占3．12％,男性现吸烟率（61．68％）明显高于女性（3．37％）人群总戒烟率为11．78％,其中因“患病”而戒烟者占72．14％,经Loistic回归分析,发现性别、年龄、低文化程度、婚史、家庭成员有吸烟者均为吸烟行为的影响因素,结论：那些离异、文化程度低、年龄小于45岁的男性为吸烟行为的高危人群。     

Are We Being Fooled by Fluoroscopy? Distortion May Affect Limb-Length Measurements in Direct Anterior Total Hip Arthroplasty

BackgroundDistortion is an intrinsic phenomenon associated with image-intensified fluoroscopy that is both poorly understood and infrequently appreciated by orthopedic surgeons. Little information exists regarding its potential influence on intraoperative parameters during orthopedic surgery, let alone during direct anterior (DA) total hip arthroplasty (THA). The purpose of this study was to quantify the amount of potential error caused by fluoroscopic distortion during DA THA.MethodsIntra-operative fluoroscopic pelvic images from 74 DA THAs were reviewed by two independent readers. All images were obtained using the same fluoroscopic C-arm unit with a radiopaque grid attached to the image intensifier. The vertical distortion from a straight central horizontal line at the peripheries of images were measured and summed to yield the combined vertical distortion similar to how a surgeon calculates a side to side comparison of limb lengths. Simple linear regression was used to evaluate associations between total distortion and patient demographics, operating theaters, and various operative parameters.ResultsThe average combined distortion was 10.0mm (range 2.0-20.0mm). There was a significant difference in the average distortion observed in different theaters (P < .001). There was no association between distortion and patient demographics or fluoroscopic time (all, P > .05).ConclusionFluoroscopic distortion is unpredictable and can cause a substantial amount of error when comparing limb lengths during DA THA. This is a critical finding as this amount of inaccuracy could lead to unintended implant positioning and limb-length discrepancies if unaccounted for.     

Exploratory assessment of treatment‐dependent random‐effects distribution using gradient functions

In analyzing repeated measurements from randomized controlled trials with mixed‐effects models, it is important to carefully examine the conventional normality assumption regarding the random‐effects distribution and its dependence on treatment allocation in order to avoid biased estimation and correctly interpret the estimated random‐effects distribution. In this article, we propose the use of a gradient function method in modeling with the different random‐effects distributions depending on the treatment allocation. This method can be effective for considering in advance whether a proper fit requires a model that allows dependence of the random‐effects distribution on covariates, or for finding the subpopulations in the random effects.     

Revision of the Parenting Stress Index

To facilitate early identification of children at risk for developmentof behavioral or emotional disturbance, the Parenting StressIndex (PSI) is designed as a screening and diagnostic instrumentthat measures the relative magnitude of stress in the parent-childsystem. For this study, the most re cent revision of the PSI,Form 6, was evaluated for reliability and factorial validityusing a sample of 534 parents. Form 6 of the PSI was found tohave even higher reliability than previous forms, supportingits continued usefulness both for preliminary screening andfor pretesl/posttest measure ment of the effectiveness of counselingprograms and intervention tech niques. Form 6 of the PSI wasalso found to have high factorial validity, suggesting thatthe domain scores and subscale scores may be confidently utilizedto provide information about specific sources of stress in theparent-child system which should be the focus of further attentionand professional assistance.     

The contribution of bone loss to postmenopausal osteoporosis

We have addressed the relative importance of peak bone mass and subsequent rate of loss in determining postmenopausal women's bone mass in old age, by examining longitudinal measurements of radial mid-shaft bone mass on various samples of healthy white postmenopausal women. Using both the variance estimate of age-specific rates of bone loss and the population variance in bone mass, we determined that rates of loss could contribute importantly to future bone mass. However, since we found a small negative correlation between initial bone mass and rate of loss, it was necessary to estimate the effect of bone loss as the complement of the contribution of initial bone mass. We found that the influence of bone loss (relative to initial bone mass) increases as the women age, such that by about age 70, the contribution of initial bone mass and rate of loss approached equality. However, estimated rates of bone loss were not very stable over time, so it was difficult to identify long-term fast-losers. We conclude that the rate of postmenopausal bone loss is an important contributor to osteoporosis at old age, but it is difficult to identify long-term fast-losers, thereby reducing the clinical value of assessments of rates of change in bone mass early in the postmenopause.