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Biomedical subjects

W Cheng

Publications and source records attributed to W Cheng.

At least 73 records · Page 4Linked to original sources
PubMed1998

A 20-year experience with the Hancock porcine xenograft in the elderly.

BACKGROUND: The availability of 20 years of follow-up data on the Hancock porcine valve (Medtronic Inc, Irvine, CA) allows determination of long-term actual and actuarial failure rates in the elderly. METHODS: We analyzed outcomes after mitral or aortic valve replacement with the Hancock porcine valve in 491 consecutive patients, comparing actual and actuarial valve failure rates in the elderly (age 65 or older) with those in younger patients. RESULTS: The average age of aortic valve replacement recipients was 68+/-14 years (N = 243) and of mitral valve replacement recipients, 64+/-12 years (N = 248). Average follow-up was 7.0 years (1,673 patient-years) for aortic valve replacement and 7.3 years (1,781 patient years) for mitral valve replacement recipients. The median time to reoperation or structural failure was 15.9 years for aortic valve replacement patients and 14.3 years for mitral valve replacement patients. However, few elderly patients survived to 15 years (22% of the elderly aortic valve replacement and 13% of the older mitral valve replacement patients). The 15-year actual reoperation rate was therefore only 10% in the elderly aortic valve replacement compared to 30% in the younger aortic valve replacement patients. For mitral valve replacement, the 15-year actual reoperation rate was 11% in the elderly and 36% in the younger patients. The lifetime reoperation risk (the maximum potential number of patients who might ever undergo reoperation during their lifetime) is the sum of actual survival and actual reoperation rates. The lifetime reoperation risk was 20% or less for elderly aortic valve replacement patients and 18% or less for elderly mitral valve replacement patients. CONCLUSION: These data suggest that about 1 in 10 elderly patients (65 years or older) receiving a Hancock valve will require reoperation within 15 years and less than one in five will ever require reoperation in their lifetimes.

Actuarial Analysis↗
PubMed1998

Gadolinium-infusion magnetic resonance angiogram: a new, noninvasive, and accurate method of preoperative localization of impalpable undescended testes.

PURPOSE: This study investigates the usefulness of Gadolinium (Gd)-infusion magnetic resonance angiogram (MRA) in the detection of impalpable undescended testes. METHODS: Magnetic resonance (MRI) examination was performed in 14 patients with 17 impalpable undescended testes (unilateral, n = 11; bilateral, n = 3). MRAwasthen performed as follows: Gadolinium-DTPA-BMA (Omniscan) at 0.3 mmol/kg body weight was injected intravenously, and dynamic coronal examination using fast spoiled gradient recalled sequences was obtained with images taken at early arterial and delay venous phases. The testis was located by detection of the enhanced pampiniform venous plexus. RESULTS: Of the 17 undescended testes, 11 canalicular hypoplastic testes and 3 intraabdominal testes were detected in both routine MRI and MRA. Three atrophic testes were found in the scrotum by MRA but not detected by routine MRI. The detection rates of impalpable testes by MRI and MRA were 82.4% and 100%, respectively. All imaging findings were confirmed by surgical exploration. There was no morbidity associated with MRA. CONCLUSION: Gd-infusion MRA is an accurate and sensitive method of preoperative localization of impalpable testes and is superior to conventional MRI in the detection of atrophic testes.

Adolescent↗
PubMed1998

The involvement of two or more systems and the severity of associated anomalies significantly influence mortality in esophageal atresia.

PURPOSE: The aim of this study was to examine the influence of associated anomalies in babies born with esophageal atresia (EA). METHODS: A retrospective review of the records of 41 consecutive cases of esophageal atresia managed over an 11-year period was undertaken. RESULTS: A higher incidence of associated anomalies was seen in those babies with lower birth weights. Although all five (100%) babies with EA who weighed less than 1,800 g had associated anomalies, those who weighed 1,800 to 2,500 g and more than 2,500 g were associated with 67% (10 of 15) and 43% (9 of 21) anomalies, respectively. The most common system in which anomalies occurred was the cardiovascular system (37%) followed by gastrointestinal (24%), musculoskeletal (17%), genitourinary (7%), chromosomal (5%), and others (12%). All 17 (41%) babies with no associated anomalies survived. Four of the 10 babies who had two or more systems involvement died, whereas only one of 31 babies with less than two systems involvement died; the difference between these two groups was highly significant (Fisher's Exact test, P = .009). The overall mortality rate was 12%. Three of the deaths were associated with severe anomalies that were incompatible with life such as bilateral renal agenesis, trisomy 18, and complex cardiac anomalies. CONCLUSION: The association of two or more system anomalies and the severity of associated anomalies influence mortality in esophageal atresia.

Abnormalities, Multiple↗
PubMed1998

Murine duodenum does not go through a "solid core" stage in its embryological development.

Embryological development of duodenum is believed to go through a "solid core" stage which subsequently vacuolizes. Failure of vacuolization is thought to be the cause of duodenal atresia. This study examines the embryological development of rat duodenum. Thirty-six time-mated Sprague-Dawley rats were studied. Six fetal duodenal specimens were obtained for each gestational day from day 9 to day 20. These specimens were fixed with formalin, sectioned, stained with haematoxylin and eosin and examined under microscope. The duodenal diameters and the lumen diameters at each gestational date were measured. The foregut started to form at the gestation stage of day 10. The lumen was narrowest on days 12 and 13, but the duodenum did not become a "solid core". No vacuolization was detected through out the development of the duodenum. Embryological development of rat duodenum did not go through a "solid core" stage.

Animals↗
PubMed1998

[Study on a deletion polymorphism of the angiotensin converting enzyme gene in pregnancy induced hypertension].

OBJECTIVE: To study a polymorphism and allele frequency of the angiotensin converting enzyme (ACE) gene in pregnancy induced hypertension (PIH). METHODS: Polymerase chain reaction (PCR) for detection of ACE gene polymorphism was performed to show the deletion/insertion (D/I) polymorphism in intron 16 of ACE gene. A 490 bp(I) and 190 bp(D) PCR products were identified, corresponding to the PCR amplification of the the allele with or without the insertion. RESULTS: Derived allele frequencies for insertion and deletion were the different between 35 PIH and 25 control subjects. Compared the frequency of D allele gene (0.76) and the percentage of the ACE DD genotype (65.7%) in the PIH patients with the frequency (0.28) and the percentage (8.0%) in the control population, they were significant higher in individuals with PIH (P < 0.001). CONCLUSIONS: There was an excess of DD genotype and the frequency of D allele gene in PIH, confirming the genetic variation in the ACE locus could be involved in the risk of PIH and suggesting the ACE gene may contribute to the pathogenesis of PIH.

Adult↗
PubMed1998

[Clinical study on effect of huancongdan capsule in treating senile vascular dementia].

OBJECTIVE: To observe the effect of Huancongdan (HCD) capsule on senile vascular dementia (SVD). METHODS: Seventy two cases of SVD were divided randomly into two groups. The HCD group (37 cases) were treated with HCD and the control group (35 cases) treated with Hydergine. RESULTS: After 2 months of treatment, the clinical symptoms, hyponeural defect, self-care capability and abnormal ratio of whole blood viscosity to plasma viscosity in HCD group were significantly different as compared with before treatment (P < 0.05). CONCLUSION: The effect of HCD for treatment of SVD was affirmative.

Aged↗
PubMed1998

Determination of intraocular lens tilt and decentration using simple and rapid method.

PURPOSE: To determine the tilt and decentration of implanted intraocular lens (IOL) in vivo one year postoperatively. METHODS: A retrospective study was performed on 67 eyes by the method introduced by Guyton using the third and fourth Purkinje imagesm through undilated pupil. RESULTS: The average decentration of implanted IOL was 0.68 mm, and the average tilt was 6.03 degrees. The result was similar to the histopathological study in postmortem eyes and the measurement in vivo. Linear-regression analysis showed there was no relationship between the tilt and decentration and the residual astigmatism, axial length, IOL power, etc. CONCLUSION: The result is similar to the other methods. The method using the third and fourth Purkinje images is simple and easy to perform. It can be used for determining the IOL position through undilated pupil and does not require special apparatus.

Adult↗
PubMed1997

Cloning and expression of a developmentally regulated transcript MXR7 in hepatocellular carcinoma: biological significance and temporospatial distribution.

Using the differential display method to analyze mRNA expression in hepatocellular carcinoma (HCC) and nontumor livers, we cloned a full-length cDNA of 2263 bp, which was designated GTR2-2 and was identical with MXR7. The MXR7 mRNA was detected in 143 of 191 (74.8%) primary and recurrent HCCs taken from 154 patients but only in 5 (3.2%) nontumor livers. MXR7 mRNA was detected in one of two hepatoblastomas but not in hepatocellular adenoma, cholangiocarcinoma, or metastatic carcinomas to the liver. In human cancer of other anatomical sites, MXR7 mRNA was detected in low levels in one Wilms' tumor and in 4 of 40 gastric adenocarcinomas but not in several other types of cancer and 21 nonhepatocellular human tumor cell lines examined. MXR7 mRNA was expressed in high levels in the placenta, fetal liver, lung, and kidney, but it was undetectable in adult liver and was expressed in very low levels in adult lung and kidney. Our observations suggest that the MXR7 gene is regulated developmentally and expressed preferentially in HCC. To study its potential biological significance, we selected 113 patients who had unicentric primary HCC and had been followed for more than 4 years for further analysis. The MXR7 mRNA expression correlated closely with elevated serum alpha-fetoprotein (AFP) levels (88 versus 55%; P = 0.0001) and with expression of AFP mRNA (87 versus 55%; P = 0.005) and CD24 mRNA in HCC (80 versus 50%; P < 0.04), high tumor grade (76 versus 56%; P = 0.05), and tumor invasion (76 versus 55%; P < 0.05), but not with patient outcome. In HCC < or =3 cm, the frequency (77%) of MXR7 mRNA expression was significantly higher than that of elevated serum AFP (43%; P < 0.007) and AFP mRNA expression in HCC (41%; P < 0.004). Thus, MXR7 may serve as a sensitive early tumor marker for HCC and warrants more study to better understand its biological function.

Adolescent↗
PubMed1997

Insulin-like growth factor-1 receptor and its ligand regulate the reentry of adult ventricular myocytes into the cell cycle.

To determine whether insulin-like growth factor-1 (IGF-1) stimulation in vitro of ventricular myocytes isolated from infarcted hearts is characterized by the reentry of cells into the cell cycle, the expression and kinase activity of cyclins E, A, and B and DNA synthesis were evaluated 5 days after coronary artery occlusion and 24 and 48 h following the addition of IGF-1. Myocytes surviving an acute myocardial infarction were employed because of their increase in surface insulin-like growth factor-1 receptors (IGF-1R). Western blot analysis documented that IGF-1 resulted in an upregulation of cyclins D1, E, A, and B in viable postinfarcted myocytes. Cyclin E- and A-associated histone H1 kinase activity and cyclin D1-associated retinoblastoma protein-associated kinase activity also increased, but cyclin B kinase activity was not enhanced by IGF-1. These changes in cyclins and kinase activities were characterized by a significant increase in the number of cells labeled by bromodeoxyuridine, from approximately 630/10(6) to nearly 9, 000/10(6) myocytes. This latter value was reduced by more than 50% by antisense oligodeoxynucleotide to IGF-1R mRNA. However, IGF-1 stimulation did not induce nuclear mitotic division and cytokinesis. In conclusion, the growth-promoting effect of IGF-1 on adult myocytes is regulated by the density of IGF-1R, which conditions the activation of the replicatory machinery of the cells. The failure of IGF-1 to enhance cyclin B kinase activity may be responsible for a block in the cell cycle and the inability of myocytes to progress through the M phase and subsequently divide.

Animals↗
PubMed1997

p53 Induces myocyte apoptosis via the activation of the renin-angiotensin system.

The mechanism by which p53 activates apoptosis in various cell systems is unknown. In the absence of an external death stimulus, p53 and p53-dependent genes, bcl-2 and bax, cannot trigger apoptosis. However, p53 may enhance not only transcription of bax and repress bcl-2, but also may upregulate the local renin-angiotensin system, inducing the formation and secretion of angiotensin II from the cells. To test this hypothesis, adult rat ventricular myocytes were infected with AdCMV.p53, which resulted in downregulation of Bcl-2, upregulation of Bax, and death of 34% of the cells. Gel retardation assays demonstrated p53 binding in the promoters of angiotensinogen and angiotensin II AT1 receptor subtype. Angiotensinogen and AT1 mRNAs increased in AdCMV.p53 cells and this phenomenon was associated with a 14-fold increase in the secretion of angiotensin II. The AT1 receptor blocker losartan and angiotensin II antibody prevented p53-induced apoptosis. Thus, p53 enhances the myocyte renin-angiotensin-system and decreases the Bcl-2/Bax ratio in the cells, triggering apoptosis. The identification of this new pathway in p53-mediated apoptosis may be critical in the alterations of myocardial function in the pathologic heart.

Adenoviridae↗
PubMed1997

Effect of nuclear protein HMG1 on in vitro slippage synthesis of the tandem repeat dTG x dCA.

Tandem repeats of simple doublet and triplet sequences occur with high frequency in the DNA of eucaryotes. Among the most frequent is the repeat of dTG, which has unusual structural properties. We show here that HMG1 (modeled by the second HMG box motif from HMG1 of the rat, HMGb) binds to complexes formed from annealing unequal lengths of dTG x dCA and inhibits the in vitro elongation of these complexes by the Klenow fragment of DNA polymerase I at 37 degrees C. At 46 degrees C, HMGb enhances the elongation. Polylysine inhibits elongation at both temperatures. These results show that the stability of this repeat in vivo can be influenced by the presence of basic proteins in general, and more selectively by the abundant nuclear protein HMG1.

Animals↗
PubMed1997

Apoptosis in the failing human heart.

BACKGROUND: Loss of myocytes is an important mechanism in the development of cardiac failure of either ischemic or nonischemic origin. However, whether programmed cell death (apoptosis) is implicated in the terminal stages of heart failure is not known. We therefore studied the magnitude of myocyte apoptosis in patients with intractable congestive heart failure. METHODS: Myocardial samples were obtained from the hearts of 36 patients who underwent cardiac transplantation and from the hearts of 3 patients who died soon after myocardial infarction. Samples from 11 normal hearts were used as controls. Apoptosis was evaluated histochemically, biochemically, and by a combination of histochemical analysis and confocal microscopy. The expression of two proto-oncogenes that influence apoptosis, BCL2 and BAX, was also determined. RESULTS: Heart failure was characterized morphologically by a 232-fold increase in myocyte apoptosis and biochemically by DNA laddering (an indicator of apoptosis). The histochemical demonstration of DNA-strand breaks in myocyte nuclei was coupled with the documentation of chromatin condensation and fragmentation by confocal microscopy. All these findings reflect apoptosis of myocytes. The percentage of myocytes labeled with BCL2 (which protects cells against apoptosis) was 1.8 times as high in the hearts of patients with cardiac failure as in the normal hearts, whereas labeling with BAX (which promotes apoptosis) remained constant. The near doubling of the expression of BCL2 in the cardiac tissue of patients with heart failure was confirmed by Western blotting. CONCLUSIONS: Programmed death of myocytes occurs in the decompensated human heart in spite of the enhanced expression of BCL2; this phenomenon may contribute to the progression of cardiac dysfunction.

Apoptosis↗
PubMed1997

Angiotensin II induces apoptosis of adult ventricular myocytes in vitro.

To determine whether angiotensin II (Ang II) activates the suicide program of myocytes, primary cultures of adult rat ventricular myocytes were exposed to 10(-9) M of Ang II, for 24 h. Ang II resulted in a five-fold increase in programmed myocyte cell death (PMCD) documented by the terminal deoxynucleotidyl transferase assay and confirmed by DNA agarose gel electrophoresis. Ang II stimulation was associated with translocation of the epsilon and delta isoforms of protein kinase C (PKC) which was coupled with an increase in cytosolic Ca2+ in the cells. The PKC inhibitor chelerythrine abolished Ang II-mediated increases in cytosolic Ca2+ and PMCD. Similarly, pretreatment of cells with the intracellular Ca2+ chelator BAPTA/AM inhibited the formation of DNA strand breaks. Conversely, the Ca2+ ionophore A23187 markedly increased PMCD. Finally, the AT1 receptor antagonist, losartan, completely blocked Ang II-induced PMCD, whereas the AT2 receptor antagonist, PD123319, did not attenuate this phenomenon. In conclusion, ligand binding of AT1 receptors on myocytes triggers PMCD by a mechanism involving PKC-mediated increases in cytosolic calcium, which result in internucleosomal DNA fragmentation.

Alkaloids↗
PubMed1997

Surface electrogastrography in children with esophageal atresia.

Surface electrogastrography was performed in 18 patients with esophageal atresia (EA) and 10 normal controls to investigate the possible role of a congenital enteric nerve defect as a cause of gastroesophageal reflux (GER), which is common after repair of EA. The means of the dominant frequencies and ranges of the frequency distribution were compared. The dominant frequencies (0.047+/-0.007 Hz) in the EA group did not differ significantly from those of the controls (0.050+/-0.007 Hz, P >0.1), although 2 patients had bradygastria and 2 had tachygastria in the EA group. The range of the frequency distribution was significantly wider in the EA group compared with normal children (P = 0.002). The wide frequency distribution in children with EA suggests disturbed electrical activity of the stomach, which could be associated with poor electromechanical coupling and, hence abnormal gastric contraction.

Child↗
PubMed1997

Childhood intussusception: ultrasound-guided Hartmann's solution hydrostatic reduction or barium enema reduction?

A comparison was made of the efficacy of ultrasound guided Hartmann's solution hydrostatic reduction on 23 patients (US group) with the same number of consecutive patients in whom hydrostatic reduction was done by barium enema (BE group) under fluoroscopy for childhood intussusception. The US group was diagnosed by ultrasound scan and reduction was attempted under the guidance of ultrasonography with Hartmann's solution at 100 mm Hg pressure. Excluded were patients older than 12 years, patients in shock, patients with peritonitis, bowel perforation, and gross abdominal distension as well as recurrent intussusception of more than three episodes. There were three patients excluded in this group. The diagnosis of intussusception and complete reduction were confirmed by gastrografin enema. This US group had three recurrences (3 of 26, 11.5%), one lead point (1 of 23, 4.4%), and 19 successful reductions (19 of 26, 73%). Incidentally, there were also three patients excluded in this period of barium enema reduction. There was only one recurrence (1 of 24, 4.2%), one leadpoint (1 of 23, 4.4%), and 12 successful reductions (12 of 24, 50%) in these 23 BE patients. The success rates for the ileo-colic intussusceptions with Hartmann's solution reduction and barium enema reduction were 91% (19 of 21) and 55% (12 of 22), respectively (P = .00865). There was no complication in either group, and the accuracy of diagnosing a complete reduction was 100% in both forms of reduction. Hence, ultrasound-guided hydrostatic reduction for childhood ileocolic intussusception is preferred because it is safe, accurate, has a higher success rate, and can avoid radiation exposure risk.

Barium Sulfate↗
PubMed1997

Early and late results of excision of choledochal cysts.

BACKGROUND/PURPOSE: Reports on the late results of choledochal cyst excision with hepaticojejunostomy in children are relatively few. METHODS: Of the 84 patients who had choledochal cyst who came under our care, 79 have had definitive surgery, three are awaiting surgery, one is being observed with Caroli's disease, and the parents of one child have refused surgery. Thirty-eight patients treated decades ago had internal drainage procedures. Since 1972, 41 patients have had cyst excision with hepaticojejunostomy using a 40-cm Roux loop without an antireflux procedure. Early complications in those who underwent cyst excision with hepaticojejunostomy included anastomotic leak in three patients who required reoperation, cholangitis in two, and fluid collection in the gall-bladder bed that required no intervention in one. RESULTS: During a follow-up period ranging from 4 months to 17 years (mean, 8.5 years), anastomotic stricture, cholangitis, and intrahepatic stone formation developed in two children after being well for 8 years and over 11 years. These children required additional surgical procedures to overcome their problems. Asymptomatic intrahepatic stones 2 years after cyst excision with hepaticojejunostomy developed in a third child. There was no mortality in the entire group that underwent cyst excision and they are all enjoying a good quality of life. CONCLUSIONS: Careful, long-term follow-up is important in children who have choledochal cyst excision with hepaticojejunostomy.

Adolescent↗
PubMed1997

Abnormalities of neuropeptides and neural markers in the esophagus of fetal rats with adriamycin-induced esophageal atresia.

BACKGROUND/PURPOSE: To investigate the distribution of neural markers and neuropeptides in esophageal atresia (EA). METHODS: A fetal rat model with Adriamycin-induced EA was used. The animals were divided into four groups: (1) control group, (2) saline-injected group, (3) Adriamycin administered but without the development of EA, and (4) Adriamycin-induced EA group. Specimens of the distal esophagus from each group were immunostained using antibodies to S100, protein gene product 9.5 (PGP), somatostatin, vasoactive intestine peptide (VIP), bombesin, galanin, substance P, neuropeptide Y (NPY), calcitonin gene-related product (CGRP), met-encephalin, nitric oxide synthase, and tyrosine hydroxylase. RESULTS: The total cross-sectional area of the distal atretic esophagus was significantly smaller than controls (P = .01), the submucosa being the component most affected (0.0465 v 0.0234 mm). Immunoreactivity for S100 and galanin were significantly elevated in the atresia group (0.0288 v 0.0079 and .001 v 0.000). In addition, there was also an increase in CGRP and Substance P in the atretic group. CONCLUSION: The elevated levels of S100 and galanin could explain the disordered motility observed in patients who had esophageal atresia.

Animals↗