Biomedical subjects
Publications and source records attributed to C H Yu.
This paper introduces the principles, the structure, the working mode of a dual-purpose ultraviolet sterilizing light. It is based on the principles of cool and heat air exchanging and laminar flow for sterilization and disinfection.
The aim of this study is to evaluate the sonographic characteristics of alobar holoprosencephaly (AH) in utero. Seventeen cases were diagnosed at 16-30 weeks' gestation by two-dimensional and three-dimensional ultrasound from October 1994 to December 1998. In this series, the prenatal prevalence was 1 out of 415 and the detection rate of AH by prenatal ultrasound was 100%. Eleven cases (64.7%) had concurrent facial anomalies. Cleft lip and hypotelorism were the most common associated facial anomalies (72.7%). Two cases (11.8%) were twin pregnancy with one fetus affected. We present one of the largest series in the literature and compare it with previous reports. From this series, we concluded that: (1) intracranial findings, including monoventricle, fused thalami, and the absence of midline structures, were reliable sonographic characteristics for prenatal diagnosis; (2) cleft lip and hypotelorism seemed to be more common associated facial malformations than cyclopia or cebocephaly with AH; and (3) although three-dimensional ultrasound did not change the diagnosis of AH made by two-dimensional ultrasound in this series, three-dimensional ultrasound does assist in defining the severity and extent of AH.
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The purposes of this study were to use quantitative three-dimensional (3-D) ultrasonography to establish the normal charts of three fetal ear-growth indexes, (ear length, ear width and ear area), and to validate their efficacy in the prenatal diagnosis of fetal trisomies, either separately or as a combination. Using quantitative 3-D ultrasonography, we performed a prospective study to measure the three fetal ear growth indexes (i.e., ear length, ear width and ear area) in 129 singleton pregnancies, including 122 normal fetuses and 7 trisomies. The ear shape was also evaluated in these fetuses using both 2-D and 3-D ultrasonography. Our results showed that: First, 3-D ultrasonography offers better visualization and easier evaluation of fetal ears than 2-D ultrasonography. Second, when using the quantitative assessment of 3-D ultrasonography, the measurements of ear length, ear width and ear area were all correlated significantly with gestational age in normal pregnancies (r = 0.881, 0.848, and 0.890, respectively). In addition, 3 of 7 fetal trisomies had ear length below the tenth percentile, 1 had ear width below the tenth percentile, and 2 had ear area below the tenth percentile. Furthermore, with the combination of these three measurements, (including ear length, ear width and ear area), the sensitivity in detecting fetal trisomies was elevated to 57.1% and the specificity was 83.2%. In conclusion, 3-D ultrasonography reduces the limitations of 2-D ultrasonography in the evaluation of fetal ears. However, fetal ear measurement may not be used as a single ultrasonographic parameter in identifying aneuploid fetuses. We recommend using the combination of these three ear growth indexes to enhance the detection rate of aneuploidy.
The aim of our study was to investigate the parameters of fetal circulation of normal pregnancies and their relationship to fetal cardiac output. We performed a cross-sectional study of 315 normal singleton pregnancies between 20 and 40 weeks' gestation without fetal chromosomal or structural malformations. After follow-up to delivery, 212 patients who fit all the criteria were enrolled for final analysis. Blood flow velocity waveforms were obtained from the tricuspid and mitral ventricular inflow, ascending aorta (AAO), pulmonary artery (PA), middle cerebral artery (MCA), renal artery (RA), umbilical artery (UA), descending aorta (DAO), inferior vena cava (IVC) and ductus venosus (DV) using duplex (real-time Doppler) ultrasound (US) scanner. The peak velocity of DV, AAO, PA and MCA were also obtained. At the intracardiac level, the ratio of peak flow velocity of E wave to peak flow velocity of A wave (E:A ratio) of mitral valve (MV) increased more rapidly than tricuspid valve (TV) E:A ratio. For the great vessels, aortic peak velocity remained higher than the pulmonary peak velocity with advancing gestation. The cardiac output closely correlated to the cardiac compliance and flow resistance indices at arterial and venous level. The acceleration time in the fetal arteries increased with advancing gestation in AAO, PA, MCA and DAO, but it decreased in RA and kept constant in UA. In addition, the acceleration time of UA was unrelated to cardiac output. The changes of the fetal intracardiac, arterial and venous impedances were remarkable through the gestation and related to cardiac output. Fetal cardiac output correlated well with the changes of arterial resistance, except with the DAO. The ventricular compliance increased with advancing gestation, especially in the left side, and was highly related to the change of cardiac output. The acceleration time in major arteries positively correlated with the gestational age and cardiac output, except in UA and RA; this indicates the difference of the changes of mean arterial pressure in uteroplacental circulation, fetal organs and great vessels. In conclusion, the fetal cardiac output correlated well with the ventricular compliance and was influenced by both hemodynamic changes in peripheral resistance and mean arterial pressure.
The purposes of this study were to assess the fetal cerebellar volume during normal gestation using three-dimensional (3-D) ultrasound (US) and to establish a normal chart of fetal cerebellar volume using Altman's model of statistics. In total, 231 healthy fetuses were studied for assessment of cerebellar volume using a 3-D US volume scanner. The fetuses to be studied were selected to give a cross-sectional series (i.e., each fetus was examined only once). Polynomial regression analysis was calculated to find the best-fit model using gestational age as the independent variable and cerebellar volume as the dependent variable. Altman's model was used to calculate the age-related reference centiles for the variance of cerebellar volume. In addition, common fetal growth indices, such as biparietal diameter, occipitofrontal diameter, head circumference, abdominal circumference, femur length and estimated fetal weight, were also measured for the correlation between cerebellar volume and these indices. Our results indicated that the fetal cerebellar volume was highly correlated with gestational age in normal pregnancies with the best-fit polynomial regression equation of a second-order (r = 0.91, p < 0.0001). In addition, fetal cerebellar volume in normal gestation is also highly correlated with common fetal growth indices, such as biparietal diameter, occipitofrontal diameter, head circumference, abdominal circumference, femur length and estimated fetal weight (all p < 0.0001). Following the Altman's model, a normal growth chart of fetal cerebellar volume was established for clinical reference. In conclusion, with 3-D US, the assessment of fetal cerebellar volume becomes feasible. We believe that fetal cerebellar volume assessed by 3-D US may be useful in detecting cerebellar hypoplasia and relevant syndromes prenatally.
Fetal cerebellum scanning by prenatal ultrasound (US) is very important for early detection of fetal central-nervous-system anomaly, as well as for the determination of gestational age (GA). Due to the small organ size and the unique shape of the fetal cerebellum (CL), accurate measurement of the dimensions of CL by two-dimensional (2-D) US is not easy if the appropriate plane cannot be reached. With the advent of three-dimensional (3-D) US, the disadvantages of 2-D US in assessing the fetal CL dimensions can be avoided. The purpose of this study was to assess the fetal cerebellar transverse diameter (CTD) and cerebellar antero-posterior diameter (CAD) using 3-D US. First, we compared the reproducibility of 2-D and 3-D US on the assessment of fetal cerebellar dimensions. Second, we prospectively measured CTD and CAD in 223 healthy fetuses using a cross-sectional design with an attempt to establish the normal growth charts of fetal CL. Our results showed 3-D US is superior to 2-D US in the reproducibility test of fetal cerebellar dimensions. In addition, with GA as the dependent variable, polynomial regression analysis showed that the best-fit equations for both CTD vs. GA and CAD vs. GA were the first-order. The best-fit predictive equation of GA by CTD was GA (week) = 9.0281 + 0. 58533 x CTD (mm) (r = 0.95, n = 223, SE = 1.82 weeks, p < 0.0001), and the best-fit predictive equation of GA by CAD was GA (week) = 10. 855 + 1.1672 x CAD (mm) (r = 0.82, n = 223, SE = 3.41 weeks, p < 0. 0001). Furthermore, all the correlation coefficients of CTD or CAD vs. the common fetal growth indexes were also highly significant (all p < 0.0001). In conclusion, our data of fetal CL dimensions assessed by 3-D US may serve as a useful reference in assessing fetal CL growth, dating GA or detecting fetal CL anomalies.
Thrombin-induced endothelial monolayer hyperpermeability is thought to result from increased F-actin stress fiber-related contractile tension, a process regulated by the small GTP-binding protein Rho. We tested whether this process was dependent on the Rho-associated protein kinase, ROCK, using a specific ROCK inhibitor, Y-27632. The effects of Y-27632 on thrombin-induced myosin light chain phosphorylation (MLCP) and tyrosine phosphorylation of p125 focal adhesion kinase (p125(FAK)) and paxillin were measured by Western blotting. F-actin organization and content were analyzed by digital imaging, and endothelial monolayer permeability was measured in bovine pulmonary artery endothelial cell (EC) monolayers using a size-selective permeability assay. Y-27632 enhanced EC monolayer barrier function due to a decline in small-pore number that was associated with increased EC surface area, reduced F-actin content, and reorganization of F-actin to beta-catenin-containing cell-cell adherens junctions. Although Y-27632 prevented thrombin-induced MLCP, stress fiber formation, and the increased phosphotyrosine content of paxillin and p125(FAK), it attenuated but did not prevent the thrombin-induced formation of large paracellular holes. These data indicate that thrombin-induced stress fiber formation is ROCK dependent. In contrast, thrombin-induced paracellular hole formation occurs in a ROCK-independent manner, whereas thrombin-induced monolayer hyperpermeability appears to be partially ROCK dependent.
This paper examines the control of electrical stimulators for restoring the standing function to paraplegics. Patient-driven controllers are based on the knowledge that standing, using support handles, is guided by the neurologically intact natural motor control system, acting through the arms. One category of patient-driven controller is CHRELMS (Control by Handle Reactions of Leg Muscle Stimulation). The first experiments with patient-driven controllers are reported. Experiments in the CHRELMS control of one volunteer are described. Proportional control did not allow the subject to stand up because of the strategy he used, but integral control was successful. With it, he could stand up and sit down slowly, entirely guided by himself, as well as making other manoeuvres. Without changing controller mode, and by leaning forwards and backwards, he could 'posture switch' his support muscles. These are significant achievements and justify a larger study of patient-driven controllers. The subject's control strategies are discussed.
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Nonsuppurative destructive cholangitis (NSDC), a process of T-cell-mediated destruction of biliary epithelia observed in primary biliary cirrhosis (PBC), graft-versus-host disease (GVHD), and hepatic allograft rejection (HAR), also occurs in the B10. D2-->BALB/c model of GVHD. To advance studies of immunopathogenesis in this murine model, we immortalized 4 BALB/c intrahepatic biliary epithelial cell (BEC) lines as a reliable source of target cells. Freshly isolated BEC, as well as each cell line, expressed cytokeratin-19 (CK-19), epithelial cell adhesion molecule (EPCAM) and cystic fibrosis transmembrane conductance regulator (CFTR). None expressed albumin. Immortalized cells also expressed SV40 large T antigen. Class I major histocompatibility complex (MHC) was expressed by >97% of immortalized cells, while class II MHC and intercellular adhesion molecule-1 (ICAM-1) expression ranged from 0% to 13% and 14% to 74%, respectively. Interferon gamma (IFN-gamma) induced aberrant class II MHC expression and increased expression of ICAM-1. Variable proportions of immortalized cells expressed B7-1/B7-2 molecules and FAS. IFN-gamma significantly reduced B7-1 expression in some lines and significantly increased B7-2 expression in others. Allografts of freshly isolated and immortalized BEC injected into subscapular fat pads spontaneously formed duct-like structures. Inflammation was absent in BALB/c recipients. In contrast, inflammatory lesions in B10.D2 recipients were reminiscent of NSDC. Our results indicate that BALB/c-immortalized intrahepatic biliary cells: 1) retain the phenotype of mouse BEC; 2) can be induced to express aberrant class II MHC and increased ICAM-1; 3) express costimulatory B7-1/B7-2 molecules and FAS; and 4) spontaneously form duct-like structures after in vivo injection that are immunogenic in B10.D2 mice. These cell lines should facilitate future studies of the immunopathogenesis of NSDC in the B10. D2-->BALB/c murine model.
To measure the posture of a paraplegic while standing up, an economical method has been developed. Markers, glued over the joints, hook onto strings which run to rotary potentiometers mounted on a fixed frame. Springs maintain a near-constant small tension in the strings, and the potentiometers rotate as the strings wind onto pulleys. The positions are calculated by triangulation, using two potentiometers per joint, assuming that body segment lengths are constant, or three potentiometers without this assumption. Using a second-order polynomial fit, the random error in length measurement for each potentiometer is less than +/-2 mm for the string length from 0 mm to 1100 mm, or less than +/-1 mm in actual range from 600 mm to 1000 mm. With two potentiometers per joint, using a second-order polynomial fit and assuming the ankle position is known exactly, an estimate of the resulting errors in the knee and hip marker positions are 4 and 8.5 mm, respectively.
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OBJECTIVE: To examine the effect of age on body protein losses occurring during severe energy restriction in obesity. RESEARCH METHODS AND PROCEDURES: Weanling (young) Sprague-Dawley rats (YR) were fed a high fat (35% energy) diet (HFD) until mean body weight approached that of a group of chow-fed retired breeder (aged) rats (AR). Both groups were then fed HFD for an additional 2 weeks, after which selected controls from YR and AR groups were killed for baseline carcass analysis. Remaining rats were fed a very-low-energy diet (VLED, 33% kcal of HFD) for 3 weeks and then killed for carcass analysis. RESULTS: YR had greater fat stores before VLED, and lost proportionately more fat and less protein during VLED than did AR. Weight loss composition during VLED was 66.7% fat, 11.1% protein, and 22.2% water in YR, and 39.4% fat, 26.2% protein, and 34.3% water in AR. Greater YR fat loss during VLED (70.6+/-30.4 vs. 32.6+/-29.1 g in AR; mean+/-SD) was paralleled by significantly larger decreases in epididymal and retroperitoneal fat pad weights, mean adipocyte size, and lipoprotein lipase activity. Greater protein loss in AR (21.6+/-13.9 g vs. 11.8+/-10.7 g in YR) coincided with larger decreases in visceral organ weights and serum thyroxine and triiodothyronine. Energy expenditure changes during VLED were similar between groups. DISCUSSION: Dietary obese young rats appear better able than aged rats to conserve body protein while losing body fat during severe energy restriction.
Experimental evidence suggests that the myocardial phospholipase D (PLD)-phosphatidate phosphohydrolase (PAP) signalling pathway may regulate Ca2+ movements and contractile performance of the heart. As abnormal Ca2+ homeostasis is associated with diabetic cardiomyopathy, we examined the functional status of the PLD/PAP pathway in sarcolemmal (SL) membranes isolated from insulin-dependent diabetic rat hearts at 8 weeks after a single i.v. injection of streptozotocin (65 mh/kg b.w.). Compared to age-matched controls, SL PLD hydrolytic (producing phosphatidic acid, PtdOH) and transphosphatidylation activities were significantly depressed in diabetic animals, while SL PAP was significantly augmented. The net effect of the altered enzyme activities in diabetic animals was a severely diminished (by 67% of controls) membrane level of PLD-derived PtdOH. Two weeks of insulin therapy to the 6 week diabetic animals normalized PLD, while PAP activity and PtdOH level were significantly modified, but had not completely reverted to control values. The observed changes were not due to hypothyroidism associated to the diabetic model as the induction of hypothyroidism in healthy non-diabetic animals did not affect SL PLD and PAP. The results suggest that the severe reduction of PLD-derived PtdOH and increased production of sn-1,2-diacylglycerol by phosphatidate phosphohydrolase may lead to an impairment of the bioprocesses mediated by these signalling lipids.
Fibroblast growth factor-2 (FGF-2), administered to the isolated rat heart by perfusion and under constant pressure, is protective against ischemia-reperfusion (I-R). Here we have investigated whether FGF-2 cardioprotection: (a) is dependent on flow modulation; (b) is linked to effects on contractility; (c) is mediated by protein kinase C (PKC); and (d) is linked to PKC and/or mitogen activated protein kinase (MAPK) associated with the sarcolemma. The isolated rat heart was used as a model. Under conditions of constant flow FGF-2 induced significant improvement in recovery of contractile function during I-R. Under constant perfusion pressure, FGF-2 induced a negative inotropic effect (15% decrease in developed pressure). Chelerythrine, a specific PKC inhibitor, prevented both the FGF-2-induced negative inotropic effect before ischemia, and cardioprotection during I-R. FGF-2 induced a chelerythrine-preventable, five-fold increase in sarcolemmal calcium-independent PKC activity. It also increased the association of PKC subtypes -epsilon and -delta with sarcolemmal membranes, detected by Western blotting, as well as, for PKC delta, by immunolocalization. FGF-2 increased the association of PKC epsilon with the membrane fraction of adult cardiomyocyte in culture, confirming that it can affect PKC signaling in cardiomyocytes directly and in a manner similar to its effects in situ. Finally, FGF-2 induced increased active MAPK at sarcolemmal as well as cytosolic sites. Active sarcolemmal MAPK remained elevated when the FGF-2-induced protection was prevented by chelerythrine. In conclusion, we have provided evidence that cardioprotection by FGF-2 is independent of flow modulation. PKC activation mediates both the FGF-2-induced negative inotropic effect before ischemia and the cardioprotective effect assessed during reperfusion, suggesting a cause and effect relationship. Furthermore, FGF-2 cardioprotection is linked to targeting of sarcolemmal sites by calcium-independent PKC.
Although fetal mediastinal teratomas may result in respiratory distress in the neonatal period and lead to perinatal mortality, they are rarely diagnosed prenatally. Furthermore, their impact on fetal hemodynamics has never been described. We report a case of a large fetal mediastinal teratoma prenatally visualized at 38 weeks' gestation by both two- and three- dimensional ultrasound. We also describe the associated changes in the Doppler flow velocimetry, namely, a decrease in cardiac output, prolonged acceleration time in the pulmonary artery and an increase in the umbilical artery S/D ratio. The baby was well at the 5-month follow-up after an operation in the neonatal period. From our case, we believe that accurate prenatal diagnosis and assessment by two- and three-dimensional ultrasound as well as Doppler flow velocimetry may contribute to a better perinatal outcome.
We report a case of the prenatal diagnosis of a very rare anomaly, namely isolated otocephaly, using two-dimensional and three-dimensional ultrasound at 24 weeks of gestation. Two-dimensional ultrasound revealed polyhydramnios, absence of a stomach shadow, hypotelorism and a proboscis-like mass. Three-dimensional ultrasound gave a precise demonstration of the striking craniofacial features of otocephaly including agnathia, synotia, microstomia and protuberance of the nose-mouth fusion. The use of three-dimensional ultrasound provided a whole view of the very rare lethal malformation in utero and contributed significantly to prenatal diagnosis.