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Biomedical subjects

C K Yeung

Publications and source records attributed to C K Yeung.

At least 19 recordsLinked to original sources
PubMed2006

Quantum diffusion of H on Pt(111): step effects.

Using a linear optical diffraction technique, we have systematically investigated the defect effects on quantum surface diffusion of hydrogen on Pt(111) surfaces. The quantum tunneling effect was clearly observed for hydrogen diffusion at low temperatures as manifested by a leveling off of the diffusion coefficient on flat surfaces. The strong influence of surface defects on the quantum diffusion is in good agreement with the creation of an inhomogeneous surface with adsorption sites of different binding energies.

Journal Article↗
PubMed2006

A hepaticojejunostomy: technical errors with 'twists and turns'.

Excision of a choledochal cyst followed by biliary reconstruction with a Roux-en-Y hepaticojejunostomy is the treatment of choice for type I and IV choledochal cysts. We present a rare complication which was identified 8 years after the original reconstructive surgery. Conventional imaging modalities failed to identify the pathology. Only a contrast enhanced CT scan supported by image rendering software allowed for the visualization of the underlying chronic obstruction of part of the mesentery.

Anastomosis, Roux-en-Y↗
PubMed2006

Seven-day is more effective than 4-day ranitidine bismuth citrate-based triple therapy in eradication of Helicobacter pylori in children: a prospective randomized study.

BACKGROUND: Helicobacter pylori infection is common in paediatric population. To date, there is still no universally accepted recommendation on the treatment of this infection in children. Ranitidine bismuth citrate-based triple therapy has been shown to be effective in H. pylori eradication in adults but its use has rarely been validated in children. AIM: To investigate the efficacy of ranitidine bismuth citrate-based triple therapy in eradication of H. pylori in children and to determine the shortest duration of treatment required. PATIENTS AND METHODS: We conducted a prospective randomized study comparing ranitidine bismuth citrate plus amoxicillin plus clarithromycin given for 4 days vs. 7 days in H. pylori-infected children diagnosed by (13)C-urea breath test. Eradication was evaluated by repeat (13)C-urea breath test at 6 weeks after treatment. RESULTS: A total of 206 children were recruited (median age 12 years, 97 boys and 109 girls). Ninety-eight (47.6%) and 108 (52.4%) children were randomized to receive 7-day and 4-day regimen respectively. The eradication rate of 4-day treatment arm was 77.8% (both intention-to-treat and per protocol) compared with 88.8% (intention-to-treat, P = 0.036) and 89.7% (per protocol, P = 0.022) of 7-day regimen. There was no statistical difference in terms of side effects between the two groups. CONCLUSIONS: Seven-day ranitidine bismuth citrate-based triple therapy is an effective and well-tolerated treatment for eradication of H. pylori in children.

Adolescent↗
PubMed2006

Half-day urotherapy improves voiding parameters in children with dysfunctional emptying.

OBJECTIVES: Children with voiding dysfunction benefit from intensive bladder emptying re-education; however, hospitalization for such training is not always financially viable or realistic. The aim of this study was to evaluate whether half-day voiding re-education in pairs improved immediate and mid-term voiding parameters. METHODS: 48 children (mean age, 8.9 years; 54% male) identified in the urotherapy clinic as having either (1) abnormal uroflow curves, (2) a postvoid residual urine (PVRU)>10% of voided volume, or (3) proven dysfunctional voiding, were recruited and age- and gender-matched. Training over a half day included postural instruction, abdominal wall muscle pattern recognition, pelvic floor muscle relaxation training, and supervised voiding. Data from the initial clinic visit was compared to that after training, and at 1 and 3 mo follow-up. Families completed a questionnaire after the session. RESULTS: Urine flow curves were abnormal in 76.2% of initial clinic visit voids, 14% of patients after the half-day training session, and 11.7% of children at the 3-mo follow-up. Initial emptying efficiency (voided volume as a percentage of total bladder volume for that void) and mean PVR significantly improved following half-day training with gains maintained at both follow-up visits. CONCLUSION: Training children in pairs over a half day resulted in significantly improved bladder emptying that was sustained at the 3-mo follow-up.

Adolescent↗
PubMed2006

Development of a validated quality of life tool specific to children with bladder dysfunction.

AIMS: To date there have not been any generic or continence-specific measurement tools that allow clinicians to investigate quality of life in children with bladder dysfunction. The aim of this research was to create a cross-cultural tool to assess and measure the wider psychosocial impact of current and new interventions for bladder dysfunction in children. MATERIALS AND METHODS: The study was conducted in three parts: expert consultation with continence clinicians; design and administration of a child-completed international questionnaire; item analysis, validity and reliability testing, and design of a new tool. RESULTS: The need for a pediatric incontinence QoL measure evaluation was strongly endorsed by clinicians. Data from 156 child-completed questionnaires collected in 10 countries was analyzed for item characteristics and found to be free of item correlation and ceiling and floor effects. Factor analysis revealed 2 factors, which were labeled intrinsic and extrinsic. Rasch analyses showed the internal validity of both subscales was reasonable good. Cronbach's alpha for each factor was 0.91 and 0.72. After analysis, items were selected for the new tool, PinQ, and evaluated for ambiguity, clarity, comprehension level required, choice of words and phrases, and age-appropriate concepts. Twenty-one items were finally selected and randomly positioned within the tool. CONCLUSIONS: A cross-cultural tool that quantifies the holistic effect of bladder dysfunction in children has been designed and tested for validity.

Adolescent↗
PubMed2006

Renal and bladder functional status at diagnosis as predictive factors for the outcome of primary vesicoureteral reflux in children.

PURPOSE: We studied the relationship between renal and bladder functional status at diagnosis and spontaneous resolution of reflux in young children with primary vesicoureteral reflux. MATERIALS AND METHODS: Children with grade III or greater vesicoureteral reflux were recruited for the study. At entry each patient underwent voiding cystourethrogram, renal ultrasound, isotope renogram, and natural filling and conventional filling urodynamic studies. Patients were then divided into 4 groups-group 1 had normal renal and bladder function, group 2 had abnormal renal and normal bladder function, group 3 had normal renal and abnormal bladder function, and group 4 had abnormal renal and bladder function. Correlation between renal and bladder functional status with reflux resolution at a minimum followup of 24 months was evaluated. RESULTS: A total of 82 patients (mean age 3.8 years) were prospectively evaluated and followed. There were 18 patients (13 males and 5 females) in group 1, 19 (13 and 6) in group 2, 19 (18 and 1) in group 3 and 26 (22 and 4) in group 4. Complete resolution of vesicoureteral reflux occurred in 17 patients (94%) in group 1 and 7 (37%) in group 2. None of the patients from group 3 or group 4 achieved complete vesicoureteral reflux resolution. Reflux grade remained unchanged in 15 patients (79%) in group 3 and 20 (77%) in group 4. CONCLUSIONS: Resolution of vesicoureteral reflux significantly correlated with renal and bladder functional status at diagnosis. Normal renal and bladder function at diagnosis is highly predictive of complete resolution of vesicoureteral reflux, whereas abnormal renal and bladder function is prognostic for persistence of reflux.

Child↗
PubMed2006

Nocturnal enuresis in adolescents and adults is associated with childhood elimination symptoms.

PURPOSE: Since nocturnal enuresis in adults and adolescents is rarely monosymptomatic, we identified the prevalence of childhood bladder and bowel dysfunction, and compared findings to those in a normative cohort. MATERIALS AND METHODS: Childhood and current bladder and bowel dysfunction were investigated in 56 consecutive adolescents and adults attending a public nocturnal enuresis service and in 293 normative adults using a self-administered questionnaire. Analysis involved descriptive statistics, the chi-square and Kruskal-Wallis tests, and regression analysis with p <0.05 considered significant. RESULTS: Adolescents and adults attending a public nocturnal enuresis service had significantly higher childhood scores than normative adults, and significantly more childhood urgency, frequency, urge incontinence, infrequent voiding and small volume, high urge voids. Infrequent bowel action and fecal soiling in childhood were also significantly more common in those with nocturnal enuresis than in controls. Adult symptoms of urge incontinence, general bowel symptoms and nocturnal enuresis were significantly more common in adults and adolescents with nocturnal enuresis. Significant associations were found between childhood symptoms and adult overactive bladder, and childhood emptying dysfunction and adult voiding dysfunction. Higher childhood scores in adults and adolescents with nocturnal enuresis correlated significantly with current adult symptoms of urge, urge leakage, stress incontinence, hesitancy, incomplete emptying and UTI within the last year. CONCLUSIONS: Significant childhood bladder and bowel symptoms along with more adult urge and bowel dysfunction were found in adults and adolescents with nocturnal enuresis. The association with adult urgency and urinary tract infection supports the likelihood of underlying bladder and or voiding dysfunction in unremitting nocturnal enuresis.

Adolescent↗
PubMed2005

Fatal interaction between clarithromycin and colchicine in patients with renal insufficiency: a retrospective study.

BACKGROUND: Clarithromycin is frequently used to treat community-acquired pneumonia in elderly persons. Like erythromycin, it may interact with other drugs by interfering with metabolism by cytochrome P450 enzymes and with the P-glycoprotein transporter system. Colchicine, used for treatment of acute gout and for prophylaxis, may cause bone marrow toxicity. It is metabolized by CYP3A4 and is transported by P-glycoprotein. Initial case reports suggested potentially fatal interactions between clarithromycin and colchicine. METHODS: A retrospective study was conducted with 116 patients who were prescribed clarithromycin and colchicine during the same clinical admission. Case-control comparisons were made between patients who received concomitant therapy with the 2 drugs and patients who received sequential therapy. We assessed the clinical presentations and outcomes of the 2 patient groups and analyzed the risk factors associated with fatal outcomes. RESULTS: Nine (10.2%) of the 88 patients who received the 2 drugs concomitantly died. Only 1 (3.6%) of the 28 patients who received the drugs sequentially died. Multivariate analysis of the 88 patients who received concomitant therapy showed that longer overlapped therapy (relative risk [RR], 2.16; 95% confidence interval [CI], 1.41-3.31; P< or =.01), the presence of baseline renal impairment (RR, 9.1; 95% CI, 1.75-47.06; P<.001), and the development of pancytopenia (RR, 23.4; 95% CI, 4.48-122.7; P<.001) were independently associated with death. CONCLUSIONS: Clarithromycin increases the risk of fatal colchicine toxicity, especially for patients with renal insufficiency. Since there are other drugs for treatment of pneumonia and gout, these 2 drugs should not be coprescribed, because of the risk of fatality.

Aged↗
PubMed2005

Mal-positioned umbilical venous catheter causing liver abscess in a preterm infant.

Neonatal liver abscess is uncommon, carries a high mortality and is difficult to diagnose. We report an unusual case of liver abscess in a preterm infant presenting with abdominal distension and suspected gastrointestinal perforation, rather than the more usual features of fever, hepatomegaly, abdominal tenderness, right-sided pleural effusion, and leukocytosis. We discuss current treatments for neonatal liver abscess and argue that in view of the high mortality and difficulty in diagnosis, prevention should be the primary objective. We believe that mal-positioning the umbilical venous catheter in the liver substantially increases the life-threatening risk of this complication, and advocate extreme care in the placement and use of these catheters.

Catheterization, Peripheral↗
PubMed2005

Acupuncture for nocturnal enuresis in children: a systematic review and exploration of rationale.

OBJECTIVES: This review identified reports of acupuncture for childhood nocturnal enuresis, with the aim of ascertaining whether acupuncture is efficacious and or better than standard therapy for treating enuresis. MATERIALS AND METHODS: Studies of children of either gender <18 years of age who received acupuncture treatment for nocturnal enuresis, were considered. The primary outcome measure was change in the mean number of wet episodes following treatment. Electronic searching was supplemented by hand searching of western medicine and traditional Chinese medicine (TCM) journals along with English language alternative medicine journals. Trials were assessed for quality and sources of bias. Meta-analysis was performed and the overall weighted odds ratio (OR) and associated 95% confidence interval (CI) were computed using the fixed effect model; the Forest plot was used to demonstrate results. RESULTS: Two hundred six abstracts were identified, of which 11 studies were eligible for data extraction. All the trials were of low methodological quality. There was some evidence that acupuncture is useful for nocturnal enuresis when used in conjunction with other treatment that may also include a different form of acupuncture (OR 3.98, CI: 2.2-7.2). When one form of acupuncture is compared with another there was marked heterogeneity, implying that some forms of acupuncture are effective. CONCLUSION: This review provides tentative evidence for the efficacy of acupuncture for the treatment of childhood nocturnal enuresis. Due to the low methodological quality of studies, evidence to identify, which parameters of acupuncture work best, is lacking. More rigorous trials are clearly warranted.

Acupuncture Therapy↗
PubMed2005

An 18-month follow-up study after randomized treatment of phimosis in boys with topical steroid versus placebo.

OBJECTIVE: To evaluate the treatment of phimosis using topical steroid. MATERIAL AND METHODS: This was a follow-up study after a prospective, randomized, double-blind study. A total of 137 boys with phimosis were randomly assigned to either betamethasone treatment or placebo for 4 weeks, with application of the cream twice daily. Non-responders to treatment were offered steroid treatment for a further 4 weeks. All patients were invited to a follow-up examination after 18 months. RESULTS: The mean pre-treatment phimosis grades in the steroid and control groups were 5.08+/-0.66 and 4.97+/-0.70, respectively. At the 4-week follow-up, 49 boys (74%) in the steroid group were cured, compared to only 31 (44%) in the control group. Fourteen boys were circumcised after another 4 weeks of treatment; 43 of the remaining 57 boys (17 in the steroid group; 40 in the control group) had been cured. After a total of 92 boys took part in the 18-month follow-up study: 79 had been cured and 13 had suffered a relapse. Twenty-six patients did not took part in the follow-up investigation. No side-effects were noted. CONCLUSIONS: When treatment is necessary for phimosis, we recommend application of topical steroid as first-line treatment because surgery can then be avoided in 85% of cases. This first randomized, double-blind, follow-up study shows that the treatment effect persists for at least 18 months.

Administration, Topical↗
PubMed2005

Endoscopic cross-trigonal ureteral reimplantation under carbon dioxide bladder insufflation: a novel technique.

PURPOSE: To report on a novel technique of endoscopic intravesical ureteral mobilization and cross-trigonal ureteral reimplantation under carbon dioxide insufflation of the bladder (pneumovesicum) for correcting primary vesicoureteral reflux (VUR) in infants and children. PATIENTS AND METHODS: Ten boys and six girls with dilating primary VUR (7 bilateral; 23 refluxing ureters) associated with recurrent urinary-tract infections and multiple pyelonephritic renal scars underwent endoscopic Cohen's cross-trigonal ureteral reimplantation with CO(2) pneumovesicum. Their ages ranged from 10 months to 13 years (mean 4.1 years). The endoscopic procedure was preceded by distention of the bladder with saline and insertion of a 5-mm Step port over the bladder dome under cystoscopic guidance. The bladder was then drained and insufflated with CO(2) to 10 to 12 mm Hg pressure with a suction catheter inserted per urethra to occlude the internal urethral meatus. A 5-mm 30 degrees endoscope was used to provide intravesical vision. Two more 3- to 5-mm working ports were inserted on the lateral bladder wall on either side. Endoscopic intravesical mobilization of the ureter, dissection of a submucosal tunnel, and a Cohen's type of crosstrigonal ureteral reimplantation using interrupted 5-0 monofilament sutures was then performed under videoscopic guidance. Bladder drainage by a urethral catheter was maintained for 24 hours postoperatively. RESULTS: Endoscopic cross-trigonal ureteral reimplantation under CO(2) pneumovesicum was successfully performed in all except one patient, who had displacement of a port into the extravesical space after completion of the ureteral reimplantation necessitating a small vesicotomy for closure of the mucosal defect. The mean operating time was 136 minutes (range 80-230 minutes), being 112 minutes for unilateral cases and 178 minutes for bilateral cases. Two boys developed mild suprapubic and scrotal emphysema postoperatively that subsided spontaneously. All other patients recovered uneventfully and remained well. Follow-up cystograms showed complete resolution of VUR in all except one unit that had persistent grade I reflux, thus giving a success rate of 96%. CONCLUSIONS: This early experience illustrates that endoscopic intravesical ureteral mobilization and crosstrigonal ureteral reimplantation can be performed safely and effectively with routine laparoscopic surgical techniques and instruments under CO(2) insufflation of the bladder, achieving a high success rate in reflux resolution that is equivalent to that obtained with the open technique but with minimal invasiveness and much faster recovery. The longer-term outcome and potential physiological effects of CO(2) pneumovesicum on the bladder and upper-tract function will need to be evaluated further.

Adolescent↗
PubMed2005

Dysfunctional elimination symptoms in childhood and adulthood.

PURPOSE: The dysfunctional elimination syndrome (DES) is rare in adulthood. We evaluate the natural history of DES to identify aspects of the disorder that may be carried into adulthood. MATERIALS AND METHODS: A 2-part questionnaire was devised and self-administered to 191 consecutive women attending a urogynecological clinic (UG) and to 251 normal women. The first section asked for recall of childhood symptoms known to be associated with DES, while the lat-ter section explored current bladder and bowel problems. Data sets from the normal cohort (55) reporting current bladder problems were excluded. Descriptive statistics, chi-square and Mann-Whitney-U tests were used to compare variables. RESULTS: UG patients had significantly higher childhood DES scores than normal women. Overall 41.7% of UG patients could be labeled as having dysfunctional elimination as an adult. Symptoms reported significantly more often in childhood by UG patients than by control women were frequent urinary tract infection, vesicoureteral reflux, frequency, urge incontinence, slow and intermittent urine flow, small volume high urge voids, hospitalization for constipation, frequent fecal soiling and nocturnal enuresis. Higher DES scores correlated significantly with current adult urgency, urge leak, stress incontinence, incomplete emptying, post-void leak, hesitancy, nocturia and nocturnal enuresis. Constipation and fecal incontinence in adulthood also showed a significant association with high DES scores. Logistic regression revealed childhood urgency to be associated with adult DES. CONCLUSIONS: Childhood lower urinary tract dysfunction may have a negative impact on bladder and bowel function later life.

Adolescent↗
PubMed2005

Thoracoscopic repair of esophageal atresia and tracheoesophageal fistula: a multi-institutional analysis.

OBJECTIVES: For the past 60 years, successful repair of esophageal atresia (EA) and distal tracheoesophageal fistula (TEF) has been performed via a thoracotomy. However, a number of reports have described adverse musculoskeletal sequelae following thoracotomy in infants and young children. Until now, only a few scattered case reports have detailed an individual surgeon's success with thoracoscopic repair of EA/TEF. This multi-institutional review represents the largest experience describing the results with this approach. METHODS: A cohort of international pediatric surgeons from centers that perform advanced laparoscopic and thoracoscopic operations in infants and children retrospectively reviewed their data on primary thoracoscopic repair in 104 newborns with EA/TEF. Newborns with EA without a distal TEF or those with an isolated TEF without EA were excluded. RESULTS: In these 104 patients, the mean age at operation was 1.2 days (+/-1.1), the mean weight was 2.6 kg (+/-0.5), the mean operative time was 129.9 minutes (+/-55.5), the mean days of mechanical ventilation were 3.6 (+/-5.8), and the mean days of total hospitalization were 18.1 (+/-18.6). Twelve (11.5%) infants developed an early leak or stricture at the anastomosis and 33 (31.7%) required esophageal dilatation at least once. Five operations (4.8%) were converted to an open thoracotomy and one was staged due to a long gap between the 2 esophageal segments. Twenty-five newborns (24.0%) later required a laparoscopic fundoplication. A recurrent fistula between the esophagus and trachea developed in 2 infants (1.9%). A number of other operations were required in these patients, including imperforate anus repair in 10 patients (7 high, 3 low), aortopexy (7), laparoscopic duodenal atresia repair (4), and various major cardiac operations (5). Three patients died, one related to the EA/TEF on the 20th postoperative day. CONCLUSIONS: The thoracoscopic repair of EA/TEF represents a natural evolution in the operative correction of this complicated congenital anomaly and can be safely performed by experienced endoscopic surgeons. The results presented are comparable to previous reports of babies undergoing repair through a thoracotomy. Based on the associated musculoskeletal problems following thoracotomy, there will likely be long-term benefits for babies with this anomaly undergoing the thoracoscopic repair.

Cohort Studies↗
PubMed2004

Current indications for laparoscopy and retroperitoneoscopy in pediatric urology.

Laparoscopy has raised great interest in the past few years in the field of pediatric urology. It has evolved from a simple diagnostic maneuver to complex operative procedures. The aim of this study was to review urologic laparoscopy literature and provide a critical review of this field to establish current indications for videosurgery in pediatric urology. In general, from an anatomic point of view, retroperitoneoscopy seems to be more suitable than the transperitoneal laparoscopic approach for reaching the upper urinary tract. It also is less invasive and complies with the criteria for open renal surgery. With respect to current indications for videosurgery in pediatric urology, the authors have identified several well-established clinical procedures, although no large series have been published for any of the procedures, except for the treatment of varicocele, nonpalpable testis, and nephrectomy. In conclusion, the data reviewed suggest that videosurgery is a safe and feasible technique in pediatric urology if performed by expert surgeons, and that it certainly will develop further in the next few years.

Child↗
PubMed2004

A review of non-invasive electro neuromodulation as an intervention for non-neurogenic bladder dysfunction in children.

AIMS: The use of electrotherapeutics to improve filling and emptying dysfunction of the adult bladder has been well established, however the practice in children is less well known. The purpose of this review is to summarize the rationale behind the use of electro neuromodulation in children, examine the reported efficacy of the intervention for different presentations of dysfunction, and establish the current limitations to knowledge and practice. MATERIALS AND METHODS: A modified systematic review was carried out on all Medline studies identified as considering the use of electrotherapy or neuromodulation in children with bladder problems. Literature relating to use of this approach in adults was also searched in order to present current understanding of the treatment rationale and modes of application. RESULTS: A Medline search and handsearch of relevant conference proceedings revealed six studies of neuromodulation in children with non-neurogenic bladder dysfunction. There were no reports of the intervention in children with isolated pelvic floor dyssynergia, irritative symptoms, structural changes predisposing the pelvic floor to weakness, or monosymptomatic nocturnal enuresis. One report of the favorable effect of neuromodulation on gut dysmotility was identified. Study design and quality generated level 4 evidence. Positive post-intervention changes reported included: increased bladder capacity, decreased severity of urge, improved continence, and decrease frequency of urinary tract infection. Significant improvement in the urodynamic parameters of bladder compliance, number of uninhibited contractions, and bladder volume at first detrusor contraction were also reported. CONCLUSIONS: There are clear benefits from the use of electroneuromodulation in children with differing forms of voiding dysfunction. The treatment approach is independent of cognitive and pharmacological therapy, is minimally invasive, and free of side effects. To date, there are no clinical variables that reliably predict efficacy of electrotherapy in the various presentations of over and under active detrusor, sphincter dyssynergia, or irritative symptoms.

Child, Preschool↗
PubMed2004

Urinary tract infection: the urological perspective.

Urinary tract infection in babies often presents with non specific symptoms and signs. It must be considered in the differential diagnosis of a febrile sick baby or any baby with failure to thrive. In a significant proportion of babies with recurrent urinary tract infection, urological abnormality is demonstrable. The diagnosis of urinary tract infection is confirmed by the presence of pus cells and growth of microorganism in a fresh urine specimen. The voidoing history and detailed ultrasound examination in the baby including a post void evaluation of the upper and lower urinary tract can lead to the possible diagnosis in the majority. Antibiotic therapy for urinary tract infection should be followed by consideration about the need for urinary drainage at the appropriate level, particularly in cases where resolution is delayed despite antibiotics. There is a role for prophylactic antibiotics after the resolution of acute infection, at least until detailed evaluation several weeks after the acute episode, has excluded any abnormality. Micturating cytourethrogram is usually done under antibiotic cover and better done in centres with facility for fluoroscopic examination. Isotope studies have to be evaluated in the light of inherent limitations. Transient urodynamic abnormality of the urinary bladder in infancy is being increasingly recognized and should be the subject of evaluation in specific circumstances. A multidisciplinary team improves the quality of investigations, subsequent interpretation and long term care of these children. A large majority of urological abnormality in infancy and early childhood can be effectively managed by endocopic procedures. Temporary urinary diversion may be required in a small proportion. Urological reconstruction should be approached with caution, after a detailed analysis of the evolving urological tract in a baby. An aggressive approach to early diagnosis and appropriate treatment of urinary tract infection and any underlying abnormality, has been shown to significantly reduce the incidence of chronic renal failure in long term longitudinal studies in children.

Child↗