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71.
72.
J. Mehlsen K. Pagh J. S. Nielsen L. Sestoft S. L. Nielsen 《Clinical physiology and functional imaging》1987,7(2):115-124
Summary. Heart rate responses to stepwise and periodic changes in lung volume were studied in seven young healthy males. Stepwise inspiration and expiration both resulted in an increase in heart rate followed by a rapid decrease in heart rate. The fastest heart rate was reached in 1·6 ± 0·5 s and in 3·6 ± 1·4 s in response to inspiration and expiration, respectively (P < 0·01). The slowest heart rate was reached in 4·8± 1·0 s and in 7·6± 1·9 s in response to inspiration and expiration, respectively (P < 0·01). Following this biphasic change the heart rate returned to a steady level. The difference between the fastest and the slowest heart rates was significantly larger in response to inspiration (21·7 ± 7·3 beats per minute) than in response to expiration (12·0±7·3 beats per minute; P < 0·01). Periodic changes in lung volume were performed with frequencies from 3·0 to 12·0 respirations per minute (r.p.m.). The changes in heart rate showed a constant amplitude in the frequency range below 5·5 r.p.m. Maximal heart rate changes were found at frequencies of 5·5 to 7·0 r.p.m. Changes in heart rate decreased in a linear manner on a log-log scale in the frequency range above 7·0 r.p.m. The relation between frequency and changes in heart rate is explained by interference between the transient changes in heart rate induced both by inspiration and by expiration. It is concluded that if heart rate changes in response to periodic changes in lung volume are to be used as a measure of vagal function a number of factors have to be taken into consideration and to simplify the analysis of heart rate responses to breathing we recommend, instead, the use of the transient changes in heart rate induced by stepwise changes in lung volume. 相似文献
73.
Margaret Sullivan Pepe Ziding Feng Gary Longton Joseph Koopmeiners 《Statistics in medicine》2009,28(5):762-779
Development of a disease screening biomarker involves several phases. In phase 2 its sensitivity and specificity is compared with established thresholds for minimally acceptable performance. Since we anticipate that most candidate markers will not prove to be useful and availability of specimens and funding is limited, early termination of a study is appropriate, if accumulating data indicate that the marker is inadequate. Yet, for markers that complete phase 2, we seek estimates of sensitivity and specificity to proceed with the design of subsequent phase 3 studies. We suggest early stopping criteria and estimation procedures that adjust for bias caused by the early termination option. An important aspect of our approach is to focus on properties of estimates conditional on reaching full study enrollment. We propose the conditional‐UMVUE and contrast it with other estimates, including naïve estimators, the well‐studied unconditional‐UMVUE and the mean and median Whitehead‐adjusted estimators. The conditional‐UMVUE appears to be a very good choice. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
74.
Jennifer L. King Rita J. Miller James P. Blue Jr. William D. O'Brien Jr. John W. Erdman Jr. 《Nutrition Research》2009
Epidemiological studies have shown dietary magnesium (Mg) intake and serum Mg levels to be inversely correlated with the development of atherosclerosis. We hypothesized that low levels of Mg would promote atherosclerotic plaque development in rabbits. New Zealand white rabbits (4 months old, n = 22) were fed an atherogenic diet containing 0.12% (−Mg), 0.27% (control), or 0.43% (+Mg) Mg for 8 weeks. Blood samples were obtained at baseline, 2, 4, 6, and 8 weeks and were assayed for total cholesterol, high-density lipoprotein (HDL), non-HDL, triglycerides (TG), C-reactive protein, serum Mg, and erythrocyte Mg. Aortas from −Mg had significantly more plaque, with an intima thickness 42% greater than control and 36% greater than +Mg. Serum cholesterol levels rose over time, and at 8 weeks, −Mg had the highest and +Mg the lowest total and non-HDL cholesterol and TG levels, although these results did not reach significance. Over time, serum Mg levels increased, and erythrocyte Mg levels decreased. C-reactive protein significantly increased in all groups at 4 and 6 weeks but returned to baseline levels by 8 weeks. This study supports the hypothesis that inadequate intake of Mg results in an increase in atherosclerotic plaque development in rabbits. 相似文献
75.
AIMS: To investigate the association between estimated glomerular filtration rate (eGFR) and total and cardiovascular mortality in a population-based cohort of diabetic subjects. METHODS: A longitudinal study using a population-based district diabetes register comprising 3288 subjects in South Tees, UK. The eGFR was calculated using the Modification of Diet in Renal Disease (MDRD) study equation. Patients were stratified by baseline eGFR into five stages as per the National Kidney Foundation guidelines: Stage 1, eGFR > 90; Stage 2, eGFR 60-89; Stage 3, eGFR 30-59; Stage 4, eGFR 15-29; and Stage 5, eGFR < 15 ml/min per 1.73 m(2). Main outcome was all-cause and cardiovascular mortality between 1 January 1994 and 31 July 2004. RESULTS: At baseline, mean age (58.4 years) differed between groups. Persons with lower eGFR were older (P < 0.001). Thirty-six percent (n = 1193, males 56%) had died by 10 years (cardiovascular cause in 60%). Median follow-up was 10.5 years amounting to 28 342 person years. Stages 4 and 5 (eGFR 相似文献
76.
Mohamed Eid Fawzy Mohamed Shoukri Walid Hassan Vijayaraghavan Nambiar Miltiadis Stefadouros Charles C Canver 《Catheterization and cardiovascular interventions》2007,69(1):40-46
BACKGROUND: The effect of mitral valve morphology (MVM) on the long-term results of mitral balloon valvuloplasty (MBV) is not well established. The aim of the study was to evaluate the impact of MVM on long-term outcome of MBV. METHODS: Five hundred and eighteen consecutive patients (mean age, 31+/-11 years) who underwent successful MBV were followed up for 0.5-16.5 (mean, 6+/-4.5) years. Patients were divided into two groups according to their mitral echo score (MES) before MBV: group A (n=340; MES8). RESULTS: We report the immediate and long-term clinical and echocardiographic results of the above-mentioned 518 consecutive patients. The mitral valve area was significantly larger in group A than in group B, both immediately after MBV (2.0+/-0.3 vs. 1.82+/-0.3 cm2, respectively; P<0.0001) and also at the last follow-up (1.8+/-0.33 vs. 1.5+/-0.33 cm2, respectively; P<0.0001). Restenosis occurred in 38/340 (11%) in group A vs. 73/178 (41%) in group B (P<0.0001). Actuarial freedom from restenosis at 5, 10, 15 years were 92+/-2%, 85+/-3%, 65+/-6% for group A vs. 72+/-4%, 44+/-5%, 9+/-6% for group B (P<0.001). Event-free survival rates at 5, 10, 15 years for group A were 93+/-1%, 88+/-2%, 66+/-6% vs. 82+/-3%, 59+/-6%, 8+/-7% for group B (P<0.0001). Stepwise Cox multivariate regression analysis identified MES, preprocedure functional class, and postprocedure mitral valve area相似文献
77.
围生期窒息发生率和死亡率近10年变迁及相关因素 总被引:2,自引:1,他引:1
目的 分析近10年来围生期窒息发生率和死亡率的变迁,探讨围生期窒息相关因素及开展新法复苏对围生期窒息发生率和死亡率的影响。方法对近10年郑州大学第三附属医院分娩的所有活产新生儿的病历资料进行回顾性分析,计算窒息的发生率、死亡率、病死率,观察上述指标的逐年变化趋势及季节变化的情况,并探讨性别、双/多胎、出生体质量、胎龄分娩方式对这些指标的影响。结果轻度窒息发生率在开展新法复苏后明显下降,并稳定在1.5%左右,而重度窒息的发生率和病死率均无明显变化。窒息儿的发生率以4月份最高,但死亡率和病死率以7月份最高。窒息的发生还与性别、双/多胎、出生体质量、早产以及阴道助产有关。结论围生期窒息的发生与性别、双/多胎、出生体质量、胎龄密切相关;新法复苏能显著降低轻度窒息的发生率,对重度窒息的发生率和窒息病死率无明显影响;窒息儿的死亡率和病死率与季节有关。 相似文献
78.
血清胱抑素C对高血压和糖尿病早期肾功能损伤的诊断价值 总被引:1,自引:0,他引:1
目的探讨血清胱抑素C(Cys-C)水平对高血压、糖尿病早期肾功能损害的临床价值。方法收集22例高血压患者、28例糖尿病患者及44例肾病患者的血清标本,用酶法测定血清肌酐、尿素氮,用颗粒增强免疫比浊法测定血清Cys-C,放射免疫法测定β2-微球蛋白。结果血清Cys-C和β2-微球蛋白的异常检出率显著高于血清肌酐、尿素氮;高血压及糖尿病两组患者血清Cys-C水平均较正常对照组明显升高(P<0.01);肾病组各项检测指标均显著高于高血压组、糖尿病组和正常对照组。结论对早期肾功能损害的诊断价值,血清Cys-C测定敏感性稍次于β2-微球蛋白,但其特异性优于血清β2-微球蛋白,综合比较,血清Cys-C可作为高血压及糖尿病早期肾功能损害的辅助诊断指标之一。 相似文献
79.
Masao Miyagawa Shuji Tanada Ken Hamamoto 《European journal of nuclear medicine and molecular imaging》1991,18(5):332-338
To evaluate the usefulness of myocardial scintigraphy as a monitoring tool for chronic doxorubicin (DXR) cardiotoxicity, a rat model was used to investigate the relationship between the myocardial uptake of thallium 201 (Tl) or rechnetium 99m pyrophosphate (99mTc-PPi) and histological changes of the heart. Although there was no significant difference in myocardial Tl uptake between control and DXR-treated rats at an early phase after Tl injection, late-phase Tl uptake was significantly higher in the DXR-treated rats than in the control rats, indicating a slow wash-out of Tl from the myocardium. The wash-out rate calculated from scintigraphic examination of DXR-treated rats was significantly decreased with increasing degree of cardiomyopathy. Since the Tl wash-out rate was sharply decreased even in animals with minimal histological changes, it may be a possible monitoring tool for the early detection of chronic DXR cardiotoxicity. On the other hand, myocardial99mTc-PPi images could be obtained only in rats with severe myocardial changes and hence would not useful for early detection. 相似文献
80.
Objective. The objective of our paper is to show that the spatio-temporal image correlation (STIC) and tomographic ultrasound imaging (TUI) is very convenient and helpful for the fetal screening of complex congenital heart defects (CHD).
Methods. Ultrasound examinations were performed using a Voluson 730 EXPERT or PRO system (GE Medical system, Kretztechnik, Zipf, Austria), and the transabdominal probe (RAB 4-8 MHz or 1-5 MHz) was used to acquire the STIC volumes. Various complex CHD including heterotaxia, ventricular septal defect (VSD), atrio-ventricular septal defect (AVSD), tetralogy of fallot (TOF), transposition of great artery (TGA), hypoplastic left heart syndrome (HLHS) were examined between 20 weeks and 35 weeks. After routine cardiac screening and examination by two-dimensional ultrasound, three- and four-dimensional ultrasound were performed by gray-scaled and color flow mapping. After the examination detailed analysis of CHD were performed by STIC and TUI.
Results. In the case of heterotaxia, STIC and TUI was useful for the detection of stomach and cardiac apex in the different slices. In the case of VSD and AVSD, they were useful for the exact determination of septal defect location. In the cases of TOF, TGA and HLHS, they were helpful for observation of outflow tract and exact diagnosis.
Conclusion. In the screening of complex CHD including heterotaxia, VSD, AVSD, TOF, TGA and HLHS, STIC is very useful and powerful tool. 相似文献
Methods. Ultrasound examinations were performed using a Voluson 730 EXPERT or PRO system (GE Medical system, Kretztechnik, Zipf, Austria), and the transabdominal probe (RAB 4-8 MHz or 1-5 MHz) was used to acquire the STIC volumes. Various complex CHD including heterotaxia, ventricular septal defect (VSD), atrio-ventricular septal defect (AVSD), tetralogy of fallot (TOF), transposition of great artery (TGA), hypoplastic left heart syndrome (HLHS) were examined between 20 weeks and 35 weeks. After routine cardiac screening and examination by two-dimensional ultrasound, three- and four-dimensional ultrasound were performed by gray-scaled and color flow mapping. After the examination detailed analysis of CHD were performed by STIC and TUI.
Results. In the case of heterotaxia, STIC and TUI was useful for the detection of stomach and cardiac apex in the different slices. In the case of VSD and AVSD, they were useful for the exact determination of septal defect location. In the cases of TOF, TGA and HLHS, they were helpful for observation of outflow tract and exact diagnosis.
Conclusion. In the screening of complex CHD including heterotaxia, VSD, AVSD, TOF, TGA and HLHS, STIC is very useful and powerful tool. 相似文献