Search PubMed⌕ Search

Biomedical subjects

P K Tam

Publications and source records attributed to P K Tam.

At least 19 recordsLinked to original sources
PubMed2003

Knowledge of cardiopulmonary resuscitation among the public in Hong Kong: telephone questionnaire survey.

OBJECTIVES: To evaluate the knowledge of basic life-support and training experience in cardiopulmonary resuscitation among the public in Hong Kong and to identify areas for improvement in public education. DESIGN: Telephone interview using a structured multiple-choice questionnaire. SETTING: Random cross-section of the Hong Kong public, from mid-March to May 2002. PARTICIPANTS: Men and women aged 16 years and older selected using random telephone dialling. MAIN OUTCOME MEASURE: Overall score in the cardiopulmonary resuscitation knowledge questionnaire. RESULTS: Of the 357 participants, approximately 12% had received cardiopulmonary resuscitation training. Cardiopulmonary resuscitation knowledge in Hong Kong was poor, even among the previously trained and especially with regard to circulatory maintenance. The most common reason for not taking cardiopulmonary resuscitation training was lack of time. CONCLUSION: The degree of citizen preparedness in initiating cardiopulmonary resuscitation is very poor in Hong Kong. Intensified educational efforts and exploration of new approaches to improve this first stage in the chain of survival are warranted.

Adolescent↗
PubMed2001

CDX-1 and CDX-2 are expressed in human colonic mucosa and are down-regulated in patients with Hirschsprung's disease associated enterocolitis.

Caudal type homeobox gene-1 and -2 (CDX-1 and CDX-2), homologues of the Drosophila homeobox gene caudal, encode transcription factors in endoderm derived tissues of the intestine. CDX genes control proliferation and differentiation of intestinal mucosal cells and colon cancer cells. Hirschsprung's Disease (HD) or congenital intestinal aganglionosis, a major developmental anomaly of intestine, which causes functional intestinal obstruction, is frequently associated with enterocolitis. Aetiology of HD-associated enterocolitis (HDEC) remains obscure. Reduction of gut mucosal enteroendocrine cells, and inefficient transfer of the secretory immunoglobulin A across the gut mucosal cell were shown to be associated with enterocolitis in HD patients suggesting that mucosa may directly involve in the pathophysiology of HDEC. This study aims to ascertain whether the CDX-1 and CDX-2 genes, that control the proliferation and differentiation of mucosal cells, play a role in HDEC. Using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridisation, we analysed the expression of CDX-1 and CDX-2 genes in colon specimens of normal controls, necrotising enterocolitis (NEC) infants, and HD patients with and without enterocolitis. We showed for the first time that CDX-1 and CDX-2 genes were expressed in the colonic mucosal epithelium in normal, NEC and in HD infants. However, the expressions of both genes were reduced in patients with HDEC. Our findings suggest that reduced expression of CDX-1 and CDX-2 genes in mucosa may be associated with the development of HDEC.

CDX2 Transcription Factor↗
PubMed2001

Solid-cystic papillary tumor of the pancreas in children.

Solid-cystic papillary tumor (SCPT) of the pancreas is a rare neoplasm in children. The current study attempted to estimate the incidence and possible pathological origin of the tumor. Clinicopathologic features of the children under the age of 16 years with pancreatic tumors managed in a single institution between January 1993 and November 1999 were reviewed. Representative blocks of SCPT specimens were immunostained for neuron-specific enolase (NSE) chromogrannin, synaptophysin, insulin, glucagon, somatostatin, and gastrin. There were three SCPTs, two pancreatic endocrine tumors, and one acinar cell carcinoma during the study period. The estimated yearly incidence in the referral area of 2 million population is about 0.01 pediatric SCPT per year per 100,000 population. The children underwent surgical removal of the tumors. Postoperatively, they were followed up for 6 months to 4 years and were well. Immunostaining for NSE, chromogranin, synaptophysin, insulin, somatostatin, and gastrin was negative in all cases. SCPT may thus be the most common pancreatic tumor in the Asian pediatric population. The pathological origin of the tumor remains unclear and requires further investigations.

Adolescent↗
PubMed2001

H-type tracheo-oesophageal fistula: appearance on three-dimensional computed tomography and virtual bronchoscopy.

H-type tracheo-oesophageal fistula (TOF) is a rare type of fistula without oesophageal atresia. The symptoms are usually present at birth, but the diagnosis is often delayed. Traditionally, contrast oesophagography and/or fiberoptic bronchoscopy are used to confirm the diagnosis. We describe the imaging features of a case of H-type TOF seen on three-dimensional computed tomography and virtual bronchoscopy and the usefulness of these techniques in pre-operative evaluation.

Bronchoscopy↗
PubMed2001

Decreased tyrosine kinase C expression may reflect developmental abnormalities in Hirschsprung's disease and idiopathic slow-transit constipation.

BACKGROUND: Some patients with Hirschsprung's disease have refractory constipation following excision of aganglionic bowel, as do patients with idiopathic slow-transit constipation (STC). Gut motility depends on enteric neuronal development in response to expression of trophic factors and their receptors. Recent studies indicate the importance of neurotrophin 3 (NT-3) and its high-affinity receptor tyrosine kinase C (trk C) in enteric neuronal development. METHODS: Blinded quantitative immunohistochemical analysis of colon from patients with Hirschsprung's disease (aganglionic, hypoganglionic and normoganglionic) (n = 5), STC (n = 6) and appropriate age-matched control tissues (n = 5) was performed for NT-3 and trk C. Sural nerve morphometry and immunostaining were undertaken in three patients with STC who had abnormalities on limb autonomic and sensory testing. RESULTS: A significantly higher proportion of submucous plexus neurones was trk C immunoreactive in control infant than adult colon (mean(s.e.m.) 73(9) versus 16(3) per cent of the total; P < 0.001), in accord with a role in development. The proportion of submucous plexus trk C-immunoreactive neurones was reduced in colon from patients with Hirschsprung's disease (28(7) per cent of total in normoganglionic Hirschsprung's disease; P < 0.007 versus infant controls) and STC (10(1) per cent of total; P = 0.053 versus adult controls). No abnormalities of STC sural nerves were detected by morphometry or immunostaining. CONCLUSION: Decreased trk C expression may reflect developmental abnormalities in Hirschsprung's disease and idiopathic STC. Trk C activation by NT-3 or drugs may provide novel treatments. Presented in abstract form to the Pacific Association of Pediatric Surgeons, Las Vegas, Nevada, USA, May 2000

Adult↗
PubMed2001

Hirschsprung's disease: a more generalised neuropathy?

BACKGROUND/PURPOSE: Aberrant neural crest migration is implicated in the pathogenesis of hindgut aganglionosis in Hirschsprung's disease (HSCR). Neural crest progenitors also give rise to a variety of cell types outside the gut, including nerves of the inner ear and peripheral nervous system. This study aims to determine whether such nerves are also affected in HSCR. METHODS: Pure tone audiometry and oto-acoustic emission tests were performed on 53 patients with Hirschsprung's disease and 28 age-matched controls. Forty-two children with Hirschsprung's disease and 30 age-matched controls also underwent neurologic evaluation, including quantitative peripheral tests of sensory function. RESULTS: Moderate to severe sensorineural hearing loss (1 profound [Waardenburg syndrome] and 3 high frequency) was detected in 4 children (8%) from the Hirschsprung's group. Abnormal (absent or reduced) oto-acoustic emission was detected in 77 of 102 ears (41 of 51 patients) in the HSCR group and 8 out of 48 ears (6 of 24 children) in the control group (75% v 17%; P<.0001). Two HSCR children had marked abnormalities on tests of peripheral nerve function. Significantly higher thresholds for vibration sensation were detected in HSCR versus controls (P<.05). CONCLUSION: Hirschsprung's disease may have a more generalised neuropathy than just that involving the affected bowel.

Adolescent↗
PubMed2001

Role of CD4+ and CD8+ T cells in early and late acute rejection of small bowel allograft.

BACKGROUND/PURPOSE: Results of small bowel transplantation remain unsatisfactory because of severe immune rejection. The current study aims to elucidate the role of activation of CD4+ and CD8+ T cells in early and late acute rejection of small bowel allograft and, hence, provide the immunologic basis for developing new therapeutic strategies. METHODS: We used an MHC fully mismatched (DA to Lewis) heterotopic rat small bowel transplant model and a unique FK506-based immunosuppressive regimen, which suppresses early acute rejection but does not prevent late acute rejection. Flow cytometric analysis was used to quantitate the number of activated CD4+ and CD8+ T cells in graft and host mesenteric lymph nodes. RESULTS: The survival (mean +/- SD) of intestinal allograft was significantly prolonged, from 6.6 +/- 0.84 days for the untreated group to 40.7 +/- 14.1 days for the FK506-treated group. Activation of CD4+ cells was suppressed significantly in the FK506-treated group on postoperative day 7 compared with the untreated group (29.4% +/- 3.55% v 52.83% +/- 11.9%; P <.01). Activation of CD8+ cells was similarly suppressed (31.5 +/- 10.34% v 48.53 +/- 14.34%; P <.05). Interestingly, at late acute rejection, activated CD4+ and CD8+ T cells remained at almost the same low levels as those on postoperative day 7 in the FK506-treated group. The spleen to body weight ratio was significantly increased in the untreated group (0.53 +/- 0.07), and slightly increased in the FK treated group (0.27 +/- 0.07, on postoperative day 7; 0.24 +/- 0.07 at late acute rejection) compared with the syngeneic group (0.18 +/- 0.02). CONCLUSION: The activation of CD4+ and CD8+ T cells was suppressed effectively by early potent immunosuppressive treatment resulting in prolonged survival of intestinal allograft. At late acute rejection, the CD4+ and CD8+ T cells remained at low-level activation status, in contrast to the surge of CD4+ and CD8+ activation during early acute rejection. This suggests that persistent T cell activation even at low level is sufficient to cause the late acute rejection eventually. A therapeutic strategy targeting these cells is needed for long-term engraftment.

Animals↗
PubMed2001

Ultrasound assessment of scald scars in Asian children receiving pressure garment therapy.

BACKGROUND/PURPOSE: Scar formation after scald injury in children is managed commonly by application of pressure garment. The duration of the treatment depends on clinical assessment. The objective of the study was to evaluate the efficacy of the pressure garment therapy and to correlate the clinical assessment scar thickness with ultrasound measurement. METHODS: Prospective study of children with hypertrophic scars receiving pressure garment therapy was carried out between 1993 and 1998. The scars were mapped with paper cutting. Representative scar sites were scored clinically according to Vancouver General Hospital Burn Assessment Scale (pigmentation, vascularity, pliability, height, pain, itchiness). Blind to the clinical results, 2 radiologists measured the scar thickness of the same sites with ultrasonography (5 to 10 MHz transducer, General Electric LOGIQ 500). The correlation between the clinical scores and ultrasound measurement of scar thickness were analysed using analysis of variance (ANOVA). RESULTS: The median age of 58 children with scald injury (M:F = 36:22) was 2.8 years (0.5 to 15.8 years). The mean percentage of scald was 8.8% (24% had scald area >10%). In addition, there were 5 children with burn from naked flame and 9 children with keloid secondary to surgical incisions. With pressure garment therapy, the scar thickness reached a plateau 1 (1/2) years after the injury and began to decline gradually thereafter. The clinical estimation of scar thickness correlated well with the ultrasound measurement (ANOVA, P =.003, Adjusted R square = 0.99). The accuracy rate of clinical thickness estimation was 67%. Overestimation and underestimation accounted for 15% and 18%, respectively. There also was good correlation between total clinical score and the ultrasound measurement (ANOVA, P <.001). CONCLUSIONS: In children with scald injury, the pressure garment needs to be continued for a minimum of 1 year. Ultrasound measurement correlates well with overall score of the Vancouver General Hospital Burn Assessment Scale but not individual components of the scoring system except wound height.

Adolescent↗
PubMed2001

Enteric nervous system, interstitial cells of cajal, and smooth muscle vacuolization in segmental dilatation of jejunum.

BACKGROUND/PURPOSE: The etiology of congenital segmental dilatation (CSD) of bowel remains elusive. Intestitial cell of Cajal plays a role in the pace making of the intestine. Its abnormality has been documented in a variety of conditions of abnormal intestinal motility. The current study attempts to evaluate the roles of intestitial cells of Cajal, enteric nervous system, and smooth muscle in segmental dilatation of small bowel. METHODS: Resected specimen from a neonate with segmental dilatation of jejunum was stained with H&E, Alcian blue, Periodic Acid-Schiff (PAS), and immunostained with S100, Ret, MAP5, and c-kit antibodies using the standard immunohistochemical process. RESULTS: The immunostaining of S100, Ret, MAP5 and c-kit of CSD specimen were positive. Localized vacuolization was, however, detected in the circular smooth muscle of the jejunum. The Alcian blue and PAS staining of the vacuolization were negative. CONCLUSIONS: CSD shows no abnormality in the enteric nervous system and pace makers. Localized vacuolization suggests myopathy to be a contributing factor to the disease. J Pediatr Surg 36:930-935.

Dilatation, Pathologic↗
PubMed2001

A prospective study of a one-week nonbismuth quadruple therapy for childhood Helicobacter pylori infection.

PURPOSE: In the eradication of Helicobacter pylori infection, a 1-week therapy improves patient compliance, but drug resistance may limit its efficacy. The effectiveness of the 1-week nonbismuth quadruple therapy was studied prospectively in children with proven H pylori infection in a population with a high rate of metronidazole resistance. METHODS: All pediatric patients who presented to our institutions with acute and chronic upper gastrointestinal conditions requiring endoscopy from June 1997 to February 2000 were investigated prospectively for H pylori infection. Gastric biopsy specimens were analyzed with rapid urease test and histopathology, H pylori-positive children were treated with omeprazole, clarithromycin, amoxicillin, and metronidazole for 7 days. The result of treatment was assessed 1 month after treatment with endoscopy and biopsy. The same treatment was repeated for 2 weeks if H pylori was still present. In patients who needed a third endoscopy, their biopsy specimens were cultured to determine antibiotic sensitivity. Results were correlated with patients' symptoms and endoscopic findings. RESULTS: Thirty-three children with acute (severe epigastric pain, n = 14; gastrointestinal bleeding, n = 9) and chronic (recurrent abdominal pain, n = 7; anemia, n = 3) conditions were treated for H pylori. Thirty-one (94%) were confirmed to have H pylori eradicated by a 1-week therapy, whereas 1 patient had eradication after a further 2-we'ek therapy (3.3%). The only unresponsive patient had H pylori resistant to both clarithromycin and metronidazole. All ulcers and erosions healed after the eradication of H pylori. Three patients had persistent recurrent abdominal pain despite H pylori eradication. CONCLUSIONS: The 1-week therapy with omeprazole, clarithromycin, amoxicillin, and metronidazole is an effective treatment of H pylori in children in a population with a high incidence of metronidazole resistant strain of H pylori. Peptic ulcers and erosions healed with the eradication of the bacteria.

Adolescent↗
PubMed2001

Novel capsaicin (VR1) and purinergic (P2X3) receptors in Hirschsprung's intestine.

BACKGROUND/PURPOSE: Studies of Hirschsprung's disease (HSCR) have shown that hypertrophic nerves in aganglionic bowel are mainly of extrinsic origin and may contain sensory elements. Recent advances have shown a specific capsaicin receptor VR1 (vanilloid receptor-1), and an ATP-gated ion channel P2X(3), which are expressed by sensory neurons. METHODS: This study investigated, for the first time, the distribution of VR1- and P2X(3)-immunoreactivity in normal adult, infant, and HSCR large intestine, using specific antibodies for immunohistochemistry. RESULTS: VR1-immunoreactive fibers and nerve fascicles, but not somata, were detected in all regions of the bowel in controls with few weakly immunostained fibers in the mucosa/lamina propria. Hypertrophic nerve bundles in hypoganglionic and aganglionic bowel showed intense VR1-immunoreactivity, whereas normoganglionic regions of HSCR were similar to controls. P2X(3)-immunoreactive neuronal cell bodies, in some instances with long axonal processes, were detected in the myenteric and submucous plexuses in control infant, adult, and ganglionic HSCR samples. Aganglionic samples showed weak P2X(3)-immunoreactivity in hypertrophic nerve fasciculi in the submucous and myenteric plexuses. CONCLUSIONS: The presence of VR1- and P2X(3)-immunoreactivities in aganglionic HSCR bowel indicates that sensory nerves may form a significant proportion of its hypertrophic innervation. The functional significance of P2X(3) and VR1 receptors in enteric nerves deserves further investigation.

Case-Control Studies↗
PubMed2001

Varicocele: Laparoscopic clipping and color Doppler follow-up.

PURPOSE: The aim of this study was to evaluate the results of laparoscopic treatment of varicocele and findings of testicular volume and blood supply using color Doppler ultrasound scan on follow-up. METHODS: Fourteen patients aged 7 to 15 years old (median, 12.3 years) with left varicocele (grade II, n = 4; grade III, n = 10) underwent laparoscopic clipping of internal testicular vein and artery. At follow-up, both testes were scanned by ultrasonography in axial and longitudinal planes, and at least 3 measurements-length, width, and thickness-were taken to calculate testicular volumes. Arterial perfusion of the testes also was assessed. RESULTS: Operating time ranged from 25 to 80 minutes (mean, 60 minutes). There was no perioperative complication. At a mean follow-up of 14 months (range, 2 to 39 months) all children were asymptomatic with disappearance of varicocele. The volumes of bilateral testes were equal (difference in volumes less than 10%) in 9 children. Ipsilateral testicular hypertrophy was found in 3 children. There was no difference in arterial perfusion between the testes in each patient. Small transient ipsilateral hydrocele was observed in 2 patients. CONCLUSION: Laparoscopic clipping of testicular vein and artery was simple and effective for varicocele treatment and did not compromise testicular blood supply.

Adolescent↗
PubMed2001

SOX10 is abnormally expressed in aganglionic bowel of Hirschsprung's disease infants.

BACKGROUND: The primary pathology of Hirschsprung's disease (HD) is a congenital absence of ganglion cells in the caudal most gut. The spastic aganglionic bowel is often innervated by a network of hypertrophied nerve fibres. Recently, mutations of SOX10 have been identified in patients with HD but only in those with Waardenburg-Shah syndrome. AIMS: To understand the molecular basis for the pathogenesis of HD we intended to determine the specific cell lineages in the enteric nervous system which normally express SOX10 but are affected in disease conditions. METHODS: We studied colon biopsies from 10 non-syndromic HD patients, aged three months to four years, and 10 age matched patients without HD as normal controls. The absence of mutation in the SOX10 gene of HD patients was confirmed by DNA sequencing. Expression and cellular distribution of SOX10 in bowel segments of normal and HD infants were examined by reverse transcription-polymerase chain reaction and in situ hybridisation. RESULTS: We found that in normal infants and normoganglionic bowel segments of HD patients, SOX10 was expressed in both neurones and glia of the enteric plexuses and in the nerves among the musculature in normal colon. In the aganglionic bowel segments of patients, SOX10 expression was consistently lower and was found to be associated with the hypertrophic nerve trunks in the muscle and extrinsic nerves in the serosa. CONCLUSION: We conclude that SOX10 is normally required postnatally in the functional maintenance of the entire enteric nervous system, including neurones and glia. In non-syndromic HD patients who do not have the SOX10 mutation, the SOX10 gene expressed in the sacral region may be involved in the pathogenesis of the abnormal nerve trunks through interaction with other factors.

Case-Control Studies↗
PubMed2001

Using gadolinium-infusion MR venography to show the impalpable testis in pediatric patients.

UNLABELLED: OBJECTIVE; This study evaluated the adjunctive value of gadolinium-infusion MR venography to locate the impalpable testis. SUBJECTS AND METHODS: Routine MR imaging and MR venography were performed in 34 patients presenting with impalpable testis. MR venography was performed by dynamic injection of gadopentetate dimeglumine bismethylamide with images taken at delayed venous phases. The site of the testis was determined by detection of the contrast-enhanced pampiniform venous plexus. RESULTS: A total of 44 impalpable testes were examined. Twenty-six hypoplastic canalicular testes, two testes at pelvic skinfold, four atrophic testes in the scrotum, and five intraabdominal testes were detected on both routine MR imaging and MR venography. Five "vanishing" testes in the scrotum and two at the groin region were detected by MR venography but not on MR imaging. CONCLUSION: Gadolinium-infusion MR venography is superior to MR imaging in the detection of atrophic testes. The method is a useful adjunct in patients with negative MR imaging findings.

Adolescent↗
PubMed2000

Cytotoxic chemotherapy has minimal direct effect on gastric myoelectric activity in children with 5HT(3) antagonist prophylaxis.

BACKGROUND: Cancer patients receiving cytotoxic chemotherapy frequently develop nausea and vomiting. The direct effect of chemotherapy on gastric pacemaker is not clear. The objective of this study was to assess the direct interference of gastric electrical activity by chemotherapeutic agents as a possible cause of vomiting using electrogastrography (EGG). PROCEDURE: Fasting surface EGGs were recorded in 24 children with malignancy and 24 age-matched controls. All oncology patients received the intravenous prophylatic ondansetron. According to the known emetic potential of the medications they received, the children were divided into mild, moderate, and severe groups. The EGG recordings of oncology patients were segmented into prechemotherapy period, chemotherapy period, and emetic period. The EGG data from each period were collected and analyzed (paired t-test and Mann-Whitney U test). RESULTS: There were 24 children (M:F ratio: 14:10), with a mean age of 9.6 years. Eight children vomited during the course of recording (0/3 from the mild group, 2/6 from the moderate group, and 6/15 from the severe group). The average duration of intravenous medication infusion was 7.8 hr (range 2 min to 24 hr). There was no difference between the EGG of normal control and the prechemotherapy EGG of the oncology patients. No difference was detected between the EGG data from the prechemotherapy period and the chemotherapy period. A statistically significant increase in tachygastria was detected in emetic periods (28 episodes, mean duration 5 min; P = 0.01). CONCLUSIONS: Insignificant EGG changes during chemotherapy suggest that chemotherapy has a minimal direct effect on gastric pacemaker. Tachygastria seemed to be a secondary effect of vomiting rather than the cause of it. These preliminary findings suggest that efforts to modify gastric electrical rhythm as a means of management of chemotherapy-induced vomiting may be futile. Further studies to identify factors responsible for vomiting are warranted.

Adolescent↗