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Biomedical subjects

W Cheng

Publications and source records attributed to W Cheng.

At least 91 records · Page 5Linked to original sources
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↗
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

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.

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

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↗
PubMed1996

HMG box proteins interact with multiple tandemly repeated (GCC)n (GGC)m DNA sequences.

A number of tandemly repeated DNA sequences have the ability to form hairpin structures by forming non-standard base pairs. When (GCC)15 and (GGC)15 strands are annealed together, the expected duplex is the only product. However, when (GCC)15 is annealed with (GCC)10, depending on the relative concentrations, up to five complexes can be detected in native gels. Three of these species are susceptible to limited digestion by Exo VII, suggesting they are duplexes containing single stranded tails. The remaining two bands are resistant to the enzyme, and have low mobility on native gels, consistent with branched structures. The latter complexes bind HMG box proteins, members of a highly abundant class of non-histone proteins of the nucleus. These proteins, modeled in this study by the second box fragment from rat HMG1, HMGb, interact strongly with branched or chemically modified DNA, relative to normal duplexes. The expansion of triplet repeats in genomic DNA is associated with tumor formation as well with a variety of heritable neurologiocal disorders. It is our thesis that the stability of branched intermediate structures that arise in replication of these sequences and promote expansion can be influenced directly by the presence of two highly abundant proteins in the cell nucleus: the HMG box proteins, HMG1/2, and the histone H1, which associates with HMG1/2.

Bacterial Proteins↗
PubMed1996

Associations between ultrasound indices of follicular blood flow, oocyte recovery and preimplantation embryo quality.

The aim of this study was to elucidate possible relationships between ultrasound indices of follicular blood flow, oocyte recovery and the subsequent production and morphological quality of preimplantation embryos. A total of 27 women with bilateral tubal occlusion, undergoing treatment for infertility by in-vitro fertilization and embryo transfer, contributed data from 29 cycles. Transvaginal ultrasonography with colour Doppler imaging and pulsed Doppler spectral analysis was used to obtain indices of blood flow for each follicle immediately before it was aspirated. The main outcome measures for each follicle were the pulsatility index, peak systolic velocity, recovery or non-recovery of an oocyte and the subsequent production or non-production of an embryo. A total of 126 follicles were studied, 102 oocytes were recovered and 58 embryos (49 at grades I or II) were produced. There were six clinical pregnancies (pregnancy rate 27.3% per embryo transfer, 22.2% per patient). There was a significant correlation (P < 0.0001, chi2 test) between whether or not follicular blood flow was detected and whether or not an oocyte was recovered. The sensitivity of a test based on the presence of detectable blood flow and the subsequent recovery of an oocyte was 74% and the positive predictive value was 93%. The peak systolic velocity (PSV, measured in cm/s, mean +/- SD) in follicles with detectable blood flow was significantly higher in follicles that were associated with the production of a preimplantation embryo (19.7 +/- 10.8) compared with those that were not (9.9 +/- 5.3, P < 0.0001, Student's t-test). There was a 70% chance of producing a grade I or II embryo if the follicular blood velocity was >/=10 cm/s, compared with 14% if the PSV was <10 cm/s, or 18% if no blood flow was detected. We conclude that there is a physiological relationship between follicular blood velocity, oocyte recovery and the production of a high-grade preimplantation embryo, which may form the basis of a useful clinical test.

Adult↗
PubMed1996

Associated anomalies in patients with undescended testes.

Out of 252 patients with undescended testes admitted under our care between January 1984 and September 1992, 70 had bilateral undescended testes and 182 had unilateral undescended testes. Fifty-one (20 percent) patients had at least one associated anomaly. Thirteen (25 percent) patients had more than one anomaly. The anomalies included 20 patients with urogenital disorders, eight with gastrointestinal tract anomalies, seven with abdominal wall defects, and seven with cardiovascular anomalies. In addition there were 11 patients with intersexual disorders, six patients with autosomal disorders and six patients with well-recognized syndromes. We found that the incidence of intersexual disorders among the patients with undescended testes was 4.6 percent, but the incidence was much higher (55 percent) in the group of patients with both undescended testes and hypospadias. Patients with bilateral undescended testes had a much higher incidence (46 percent) of associated anomalies than those with unilateral undescended testes (10 percent).

Abnormalities, Multiple↗
PubMed1996

Does the amniotic fluid protein absorption contribute significantly to the fetal weight?

OBJECTIVE: This study was carried out to evaluate the significance of amniotic fluid protein ingestion and absorption on fetal growth. METHODOLOGY: Neonates with small bowel atresia during a 30 year period were studied retrospectively. RESULTS: There were 56 patients enlisted, 17 with duodenal atresia, 18 with jejunal atresia and 21 with ileal atresia. The percentage of mothers with polyhydramnios and the percentage of premature babies decreases as the intestinal atresia becomes more distal. The mean gestational age and the mean birthweight increase as the intestinal atresia becomes more distal. On the other hand, the percentage of the neonates with birthweight below the 50th and the 10th percentiles do not differ significantly as the intestinal atresia becomes more distal. CONCLUSIONS: It appears that the variation of birthweights in babies with different levels of small bowel atresia may be due to the difference in gestation caused by polyhydramnios. The effect of amniotic fluid protein absorption on fetal bodyweight could not be demonstrated clinically in this study.

Analysis of Variance↗
PubMed1996

Hepatitis C genotypes in Australian haemophilia patients.

BACKGROUND: Differences in the hepatitis C virus (HCV) genotype influence the severity of HCV related liver disease and response to interferon therapy. HCV infection is frequent in Australian haemophilia patients who have been exposed repeatedly to multiple HCV genotypes through non HCV virally inactivated clotting factor concentrates. The distribution of the various HCV genotypes in Australian haemophilia patients is unknown. AIM: To examine the HCV genotype distribution and clinical features of HCV associated liver disease in Australian haemophilia patients. METHODS: Forty patients with bleeding disorders who were known to be both HCV antibody and polymerase chain reaction (PCR) positive were evaluated by direct sequencing of the PCR products for the HCV genotype. RESULTS: Genotype 1 was found in 65% of patients (26/40), type 2 in 5% (2/40) and type 3 in 30% (12/40). No genotypes 4 to 6 were found. There was no association between the HCV genotype and the severity of haemophilia, alanine transaminase levels, or the presence of portal hypertension. Unlike European, Asian and American studies where the majority of type 1 infection is subclass 1b, in Australian haemophilia patients it is subclass 1a (73%-19/26) which may have a better prognosis and response to interferon. CONCLUSIONS: Despite patients with haemophilia being exposed to multiple HCV genotypes, it appears that there is no selection advantage of one genotype over another. Australian haemophilia patients with HCV have a different genotype distribution to that reported in other countries and care should be observed in interpreting non Australian studies concerning HCV.

Adolescent↗
PubMed1996

Necrotic and apoptotic myocyte cell death in the aging heart of Fischer 344 rats.

To determine the effects of aging on myocyte cell death, Fischer 344 rats at 3, 7, 12, 16, and 24 mo of age were injected with myosin monoclonal antibody for the localization and quantification of necrotic myocyte cell death in the left ventricle, interventricular septum, and right ventricle. Conversely, the presence of DNA strand breaks in myocyte nuclei, indicative of programmed cell death, was evaluated by the terminal deoxynucleotidyl transferase assay and confirmed by DNA laddering. Myocyte necrosis, which involved nearly 1,000 myocytes in the left ventricular free wall at 3 mo, progressively increased with aging, reaching a value of 13,600 myocytes at 24 mo. Corre- sponding values in the interventricular septum were 300 and 9,400 myocytes. In the right ventricle, there were 270 necrotic myocytes at 3 mo and 9,000 at 24 mo. Programmed myocyte cell death was restricted to the left ventricular free wall and included 140 cells at 3 mo. This form of myocyte cell death increased at the subsequent age intervals, resulting in the involvement of 874 cells at 24 mo. The combination of necrosis and apoptosis in the left ventricular free wall was associated with 1,150 cells dying at 3 mo and 14,500 at 24 mo. In conclusion, myocyte cell death, apoptotic and necrotic in nature, constitutes an important determinant of the aging process, possibly mediating the occurrence of ventricular dysfunction and failure in the old heart.

Aging↗