Biomedical subjects

W Cheng

Publications and source records attributed to W Cheng.

At least 91 records · Page 5Linked to original sources

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↗

PubMed1997

A prospective randomized study of wound approximation with tissue glue in circumcision in children.

OBJECTIVE: Bleeding and wound infection are the most common complications of circumcision. Cyanoacrylate tissue glue has been claimed to have the advantage of being haemostatic, bacteriostatic and easy to use. The purpose of this study is to assess the feasibility of using the tissue glue in approximation of circumcision wound in children. METHODOLOGY: A prospective randomized trial was carried out on 86 boys consecutively admitted into the Duchess of Kent Children's Hospital, Hong Kong. The results of wound approximation with cyanoacrylate tissue glue and suturing with interrupted 4/0 plain catgut were compared. The operations were carried out by the same surgeon using identical technique except for the wound approximation. The wound was assessed 1 day, 2 days, 3 days, 1 week and 1 month postoperatively. RESULTS: There was no statistically significant difference between the two groups in the rates of wound inflammation, infection, bleeding, dehiscence and cosmetic appearance, but the duration of operation was longer using tissue glue (19.8 min vs 16.5 min, P = 0.002). CONCLUSIONS: We conclude that tissue glue approximation of circumcision wounds in children is a feasible alternative, but it offers no extra advantage when compared to suturing.

Child↗

PubMed1997

Myocardial infarction alters myofilament calcium sensitivity and mechanical behavior of myocytes.

To determine whether myocardial infarction leads to alterations in myofilament isometric tension as a function of Ca2+ concentration, unloaded shortening velocity, and sarcomere compliance, these properties were examined in skinned myocytes 7 days after coronary artery occlusion. Changes in myofilament proteins were also evaluated Myocardial infarction was characterized by a 10-15% reduction in myofilament isometric tension at submaximum Ca2+ levels in the physiological range. However, developed tension at maximum activation was unaltered. Conversely, unloaded shortening velocity was decreased by 31% in the remaining viable cells, whereas resting tension was increased by 30-40%. The regulatory protein troponin I content was reduced, but phosphorylation of troponin I and troponin T was increased. Myosin isoenzymes and troponin T contents were not altered. In conclusion, molecular responses occurred acutely after myocardial infarction, and these adaptations may depress the mechanical behavior of the unaffected cells, contributing to acute impairment in global cardiac pump function beyond that resulting from myocyte loss.

Actin Cytoskeleton↗

PubMed1997

Ileoileocolic intussusception in children: diagnosis and significance.

The ileoileocolic type of childhood intussusception is difficult to diagnose pre-operatively and is associated with increased morbidity. This study describes the clinical and imaging features of 10 consecutive ileoileocolic intussusceptions diagnosed ultrasonically in 10 patients over a 36 month period. Ultrasound-guided hydrostatic reduction using Hartmann's solution was attempted in all 10 patients. Clinical and imaging features were compared with those of 28 ileocolic intussusceptions in 25 patients diagnosed and treated using the same methods during the same period. Most of the clinical and plain radiographic features of the patients with the ileoileocolic and ileocolic types of intussusception were similar. The two types of intussusception had the classical doughnut or pseudokidney, or both, signs on pre-reduction ultrasound scans. During the reduction process, when surrounded by fluid within the caecal lumen, the ileoileocolic type of intussusception had a typical complex appearance due to frond-like loops of intussuscepted small bowel. This finding was present in all cases. The hydrostatic reduction rate was only 10% (1/10) for ileoileocolic intussusception, compared with 92.9% (26/28) for the ileocolic type. All unsuccessfully-reduced cases underwent surgery, with surgical confirmation of the intussusception type in all cases. Only one patient was found to have a lead point, caused by a Meckel's diverticulum. In conclusion, the diagnosis of ileoileocolic intussusception can be made pre-operatively and these patients require surgical management.

Child↗

PubMed1997

Treatment of biliary atresia by portoenterostomy and liver transplantation: The Queen Mary Hospital, Hong Kong experience.

Ninety three out of 96 patients with biliary atresia (BA) underwent Kasai 1 portoenterostomy and 11 children subsequently underwent 12 liver transplantation (LTX) procedures which included 8 living related liver transplants (LRLT), 3 reduced-size liver transplants (RSLT) and 1 orthotopic liver transplantation (OLT). During a follow-up period of 3-206 months (mean, 73 months) after portoenterostomy and 3-63 months after LTX, 50% of 96 patients are alive and well with total clearance of jaundice while 12% are mildly jaundiced, 10% are deeply jaundiced and 28% have died. Two of the 3 patients who did not undergo portoenterostomy and 25 from the portoenterostomy group have died. Of the latter group, 22 deaths occurred before, and 3 after the introduction of LTX therapy respectively. Of the 68 long-term survivors, 32 are less than 5, and 36 are 6-17 years old. Complete clearance of jaundice was achieved in 55% of patients irrespective of whether portoenterostomy was initially performed at < 10 or between 10 and 12 weeks. Portoenterostomy performed beyond 13 weeks was associated with declining results. We conclude that (1) portoenterostomy combined with liver transplantation, when indicated, has given patients with BA a much better prognosis and (2) pediatric LTX in our institute is a well established procedure with 100% patient and 88% primary graft survival.

Age Factors↗

PubMed1997

[Effect of nickel sulfate on the concentrations of T3, T4 and TSH in serum of rat].

The effect of nickel sulfate on the concentrations of T3, T4 and TSH in sera of rats was studied. Forty wistar male rats were divided into four groups. The rats in groups 1, 2 and 3 were injected with 0.005 mol/L NiSO4, 0.01 mol/L NiSO4 and 0.02 mol/L NiSO4 [1 ml/(kg x d)] respectively, while the rats of group 4 were injected with normal saline, serving as control. Forty days later, the concentrations of T3 and T4 in sera of 0.01 mol/L NiSO4 and 0.02 mol/L NiSO4 groups were obviously decreased (P<0.05 or P<0.01). The concentrations of T4 in sera of 0.005 mol/L NiSO4 group was also decreased, compared with control group. There was no difference in the concentrations of T3 and T4 in sera among the groups with different doses of NiSO4. Between different dose groups and the control group, the concentrations of TSH in sera showed no significant difference (P>0.05). The proliferation of the epithelial cells of thyroid gland was noticed. The rough endoplasmic reticulam was exceedingly expanded. The nuclei were transformed. The results suggest that Ni may injure thyroid gland.

Animals↗

PubMed1996

Overexpression of insulin-like growth factor-1 in the heart is coupled with myocyte proliferation in transgenic mice.

Transgenic mice were generated in which the cDNA for the human insulin-like growth factor 1B (IGF-1B) was placed under the control of a rat alpha-myosin heavy chain promoter. In mice heterozygous for the transgene, IGF-1B mRNA was not detectable in the fetal heart at the end of gestation, was present in modest levels at 1 day after birth, and increased progressively with postnatal maturation, reaching a peak at 75 days. Myocytes isolated from transgenic mice secreted 1.15 +/- 0.25 ng of IGF-1 per 10(6) cells per 24 hr versus 0.27 +/- 0.10 ng in myocytes from homozygous wild-type littermates. The plasma level of IGF-1 increased 84% in transgenic mice. Heart weight was comparable in wild-type littermates and transgenic mice up to 45 days of age, but a 42%, 45%, 62%, and 51% increase was found at 75, 135, 210, and 300 days, respectively, after birth. At 45, 75, and 210 days, the number of myocytes in the heart was 21%, 31%, and 55% higher, respectively, in transgenic animals. In contrast, myocyte cell volume was comparable in transgenic and control mice at all ages. In conclusion, overexpression of IGF-1 in myocytes leads to cardiomegaly mediated by an increased number of cells in the heart.

Animals↗

PubMed1996

Programmed myocyte cell death affects the viable myocardium after infarction in rats.

To determine whether apoptotic and necrotic myocyte cell death occur acutely and chronically after infarction, the formation of DNA strand breaks and the localization of myosin monoclonal antibody labeling were analyzed in the surviving myocardium from 20 min to 1 month. DNA strand breaks in myocyte nuclei were detected as early as 3 h following coronary artery occlusion and were still present at 1 month. This cellular process was characterized biochemically by internucleosomal DNA fragmentation which produced DNA laddering on agarose gel electrophoresis. Quantitatively, 155 myocyte nuclei per 10(6) cells exhibited DNA strand breaks in the portion adjacent to the infarcted tissue at 3-12 h. This parameter increased to 704 at 1-2 days and subsequently decreased to 364 at 7 days, 188 at 14 days, and 204 at 1 month. In the remote myocardium, the number of myocyte nuclei with DNA strand breaks was 84 per 10(6) at 3-12 h and remained essentially constant up to 1 month. Programmed myocyte cell death was accompanied by a decrease in the expression of bcl-2 and an increase in the expression of bax. The changes in the expression of these genes were present at 1 and 7 days after coronary artery occlusion. In conclusion, the mechanical load produced by myocardial infarction and ventricular failure may affect the regulation of bcl-2 and bax in the viable myocytes, triggering programmed cell death and the remodeling of the ventricular wall.

Animals↗

PubMed1996

Isolation and sequencing of the cDNA encoding phosphatidylinositol transfer protein from rabbit lung.

The cDNA clones encoding rabbit lung phosphatidylinositol transfer protein (PI-TP) were isolated and sequenced. The putative polypeptide consisted of 270 amino acid (aa) residues, the same as human PI-TP, but one aa residue less than the PI-TP of rat and mouse. PI-TP RNA expression in various tissues of a pregnant rabbit was analyzed by Northern blot. Brain, placenta and fallopian tube had the highest PI-TP RNA expression. PI-TP RNA expression in alveolar epithelial type-II cells isolated from rabbit lung markedly increased after a 24-h culture, suggesting that PI-TP RNA expression in type-II cells can be modified by ambient factors.

Amino Acid Sequence↗

PubMed1996

Myocardial infarction is coupled with activation of cyclins and cyclin-dependent kinases in myocytes.

To determine whether the molecular components implicated in the regulation of the cell cycle are activated in myocytes after infarction, the expression of cyclins E, A, and B and the levels of their associated kinase activity were measured at 1 and 7 days following surgery. The quantity of cdk2 and cdc2 and the level of their kinase activity were also determined. Myocardial infarction was characterized by an increase in cyclins E, A, and B and cdc2 proteins in the surviving myocytes at 1 and 7 days. Cyclin E, A, and B and cdk2 and cdc2 kinase activity also increased. The quantity of cyclins E and A and the level of cyclin E-associated kinase activity in myocytes after infarction were comparable with those measured in neonatal myocytes. Moreover, cdc2 protein and cdc2 kinase activity in myocytes reached levels after infarction which were similar to those in neonatal myocytes. Thus, myocytes react to myocardial infarction by activating cyclins and cyclin-dependent kinases which may be coupled with the regeneration of muscle mass and recovery of ventricular function.

Animals↗

PubMed1996

Myocardial Infarction Is Coupled with the Activation of Cyclins and Cyclin-Dependent Kinases in Myocytes

Journal Article↗

PubMed1996

Activation of creatine kinase-B and phospholamban gene expression in transformed latissimus dorsi muscle: evaluation of mRNA by polymerase chain reaction.

Latissimus dorsi muscle (LDM) transformation following chronic stimulation is the critical requirement for its use in cardiac assist procedures. In order to identify one or two molecular markers that can be used to effectively monitor the LDM transformation, the modulation in the expression of creatine kinase (CK) and phospholamban (PLB) genes by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was examined. Continuous in situ stimulation of left LDM was performed in four dogs for a period of 10 weeks after a vascular delay period of 2 weeks following surgery. For RT-PCR, gene-specific radiolabeled primers and equal amounts of cDNA synthesized from total RNA extracted from the LDM biopsies obtained at 4, 7, and 10 weeks of stimulation were used. A 2.6-fold increase in creatine kinase (brain type) (CK-B) mRNA was observed at transformed LDM compared to the control (P = 0.004) following 10 weeks of stimulation. On the contrary, a 30% decline was observed in creatine kinase (muscle type) (CK-M) mRNA level. An increase up to eight-fold was also observed in PLB mRNA in stimulated LDM compared to the contralateral muscle (P = 0.002). The PLB mRNA level in transformed LDM reached plateau and became comparable to that of normal heart after 7 weeks of stimulation. However, a sustained increase in CK-B mRNA level was observed until 10 weeks of stimulation. The level of beta-actin mRNA used as control remained the same in both stimulated and control samples. Thus the increase in CK-B and PLB mRNA and downregulation of CK-M mRNA in transformed LDM, demonstrated here by RT-PCR, indicate a switch from anaerobic to aerobic potential of transformed LDM along with a change towards slow-twitch phenotype and provide valuable markers to monitor the effectiveness of muscle transformation in cardiomyoplasty.

Actins↗

PubMed1996

Insulin-like growth factor-1 and myocyte growth: the danger of a dogma. Part I. Postnatal myocardial development: normal growth.

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Cell Division↗

PubMed1996

Cutaneous stoma in the roux limb of hepaticojejunostomy (hepaticocutaneous jejunostomy): useful access for intrahepatic stone extraction.

A cutaneous stoma in the Roux limb of hepaticojejunostomy (hepaticocutaneous jejunostomy) was used for stone extraction in two children who had hepatolithiasis (14.5 and 15.5 years, respectively) after operation for choledochal cysts. In constructing the hepaticocutaneous jejunostomy, a short, straight proximal limb from the skin to the bilioenteric anastomosis is mandatory. It provides a pathway, superior to the T-tube tract, for repeated stone extraction, which can be performed under sedation, thus obviating repeat laparotomies. The stoma allows flexible choledochoscopy, balloon dilatation of intrahepatic duct strictures, and extraction of intrahepatic stones using grasping forceps, baskets, and balloons. The electrohydraulic lithotriptor may be applied to fragment larger stones.

Adolescent↗