Thermal-diffusivity measurements of an oriented superconducting-film–substrate composite using the mirage technique

When one measures the thermal diffusivity χ of a thin film on a substrate by the mirage method, the photothermal deflection of the probe beam is caused by the heat field contributed by both the film and the substrate which are heated by the pump beam. To include the effects due to the presence of the substrate, we present a method to measure the diffusivities of both the film and substrate in one set of mirage detection. Using the off-axis magnetron sputtering process, we fabricated YBa2Cu3O7-δ thin films of suitable thickness (∼60 nm) on SrTiO3 as our sample for χ measurements along the c and b axes. Our results are consistent with published ones.published_or_final_versio

Paediatric hepatoblastoma and hepatocellular carcinoma: retrospective study.

OBJECTIVES: To compare and contrast clinical characteristics and outcomes of hepatoblastoma or hepatocellular carcinoma in paediatric patients. DESIGN: Retrospective study. SETTING: University teaching hospital, Hong Kong. PATIENTS AND METHODS: Medical records of 22 paediatric patients with hepatoblastoma (n=11) or hepatocellular carcinoma (n=11) admitted to Queen Mary Hospital between 1989 and 2000 were reviewed. Data gathered included demographic data, results of liver function tests, hepatitis A, B, and C titres, and alpha-foetoprotein levels, and imaging studies including chest X-ray, ultrasound study, computed tomography scan, and magnetic resonance imaging/hepatic angiogram for tumour staging and resectability. RESULTS: The mean age of patients with hepatoblastoma was 18 months (range, 5 months to 3 years), while that of patients with hepatocellular carcinoma was 10.2 years (range, 2 to 16 years). Females predominated in the hepatoblastoma group (female:male, 8:3) and males in the hepatocellular carcinoma group (male:female, 10:1). None of the patients with hepatoblastoma were hepatitis B surface antigen positive, in contrast to 64% of the hepatocellular carcinoma group. Only 45% of the hepatocellular carcinomas were resectable at presentation and this figure remained unchanged following chemotherapy. A total of 91% of hepatoblastomas were resectable, four at presentation, and a further six after chemotherapy. Tumour rupture was more common in patients with hepatoblastoma than in those with hepatocellular carcinoma (36% versus 9% of cases, respectively). Mortality rates were considerably higher among the hepatocellular carcinoma group than the hepatoblastoma group in this series. CONCLUSION: Childhood hepatoblastoma and hepatocellular carcinoma differ with respect to age and tumour stage at presentation, hepatatis B surface antigen status, tendency to rupture, chemosensitivity, and prognosis.published_or_final_versio

Prophylactic thyroidectomy in ethnic Chinese patients with multiple endocrine neoplasia type 2A syndrome after the introduction of genetic testing

Objective: To evaluate the impact of genetic testing in the management of familial multiple endocrine neoplasia 2A patients. Design: Retrospective study. Setting: University teaching hospital, Hong Kong. Patients: Twenty-two patients from eight multiple endocrine neoplasia 2A families underwent prophylactic total thyroidectomy based on a positive RET mutation genetic testing. All mutations were located at codon 634 of exon 11. Nineteen patients had preoperative basal serum calcitonin measured, and the 12 with normal levels had pentagastrin stimulation tests. Preoperative thyroid ultrasound examination was performed for 17 patients. Results: There were 13 females and 9 males with a median age of 25.1 (range, 6.1-71.9) years. Histopathology revealed medullary thyroid carcinoma in 17 (77%), C-cell hyperplasia in four (18%), and normal pathology in one (5%) of the patients. Five patients with either C-cell hyperplasia or normal pathology were among the youngest (age range, 6-9 years). The youngest patient with medullary thyroid carcinoma was nearly 9 years old. The median size of medullary thyroid carcinomas was 8.3 (range, 0.1-18) mm, but there were no lymph node metastases. Of 15 patients with normal basal calcitonin levels, 10 had medullary thyroid carcinoma, though two tested negative with the pentagastrinstimulated calcitonin assay. Five of six patients with normal preoperative ultrasonographic examinations had medullary thyroid carcinoma. Three (14%) of the patients were prescribed long-term calcium and vitamin D supplementation. After a median follow-up of 49 (range, 13-128) months, no patient had recurrence of medullary thyroid carcinoma. Conclusions: Genetic testing has replaced conventional biochemical and radiological modalities to identifying multiple endocrine neoplasia 2A carriers, in order to offer them prophylactic thyroidectomy. Chinese multiple endocrine neoplasia 2A patients with codon 634 mutation seem to have less aggressive forms of medullary thyroid carcinoma, for whom prophylactic thyroidectomy can be considered at the age of 8 years.published_or_final_versio

Chinese patients with sporadic Hirschsprung's disease are predominantly represented by a single RET haplotype.

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A biodegradable polymer-based coating to control the performance of magnesium alloy orthopaedic implants

Magnesium and its alloys may potentially be applied as degradable metallic materials in orthopaedic implantations due to their degradability and resemblance to human cortical bone. However, the high corrosion rate and accumulation of hydrogen gas upon degradation hinders its clinical application. In this study, we adopt a new approach to control the corrosion rate by coating a controllable polymeric membrane fabricated by polycaprolactone and dichloromethane onto magnesium alloys, in which the pore size was controlled during the manufacturing process. The addition of the polymeric membrane was found to reduce the degradation rate of magnesium, and the bulk mechanical properties were shown to be maintained upon degradation. The in-vitro studies indicated good cytocompatibility of eGFP and SaOS-2 osteoblasts with the polymer-coated samples, which was not observed for the uncoated samples. The in-vivo study indicated that the uncoated sample degraded more rapidly than that of the polymer-coated samples. Although new bone formation was found on both samples, as determined by Micro-CT, higher volumes of new bone were observed on the polymer-coated samples. Histological analysis indicated no inflammation, necrosis or hydrogen gas accumulation on either of the samples during degradation. Collectively, these data suggest that the use of polymeric membrane may be potentially applied for future clinical use. © 2009 Elsevier Ltd. All rights reserved.postprin

Burden of postinfectious symptoms after acute Dengue, Vietnam.

We assessed predominantly pediatric patients in Vietnam with dengue and other febrile illness 3 months after acute illness. Among dengue patients, 47% reported >1 postacute symptom. Most resolved by 3 months, but alopecia and vision problems often persisted. Our findings provide additional evidence on postacute dengue burden and confirm children are affected

Ten-year experience with liver transplantation at Queen Mary Hospital: retrospective study.

OBJECTIVE: To report the experience with liver transplantation at the Queen Mary Hospital from 1991 to 2000. DESIGN: Retrospective study. SETTING: Liver transplant centre of a University teaching hospital, Hong Kong. PATIENTS: One hundred and forty-eight patients (127 adults and 21 children) who underwent a total of 155 liver transplants using 75 cadaver grafts (full-size, 67; reduced-size, 5; split, 3) and 80 living donor grafts (left lateral segment, 15; left lobe, 6; right lobe, 59) from October 1991 to December 2000 were reviewed. MAIN OUTCOME MEASURES: Graft and patient survival rate. RESULTS: The most common disease indications for liver transplantation were chronic hepatitis B-related liver disease (n=74) in adults and biliary atresia (n=14) in children. Eighteen patients had hepatocellular carcinoma. Forty-eight (31%) liver transplants (three ABO-incompatible) were performed in high-urgency situations for patients requiring intensive care. The proportion of living donor liver transplants was 47.7% in adults and 73.9% in children. The overall 1-year and 5-year patient survival rates were 82% and 77%, respectively. The survival of high-risk recipients, such as those with fulminant hepatic failure (80%), chronic hepatitis B (81%), or hepatocellular carcinoma (94%), was not inferior to that of other patients. CONCLUSION: Over the last decade, the promotion of (cadaver) organ donation through public education coupled with innovative techniques in living donor liver transplantation have enabled a liver transplantation programme to be established in Hong Kong with gratifying results.published_or_final_versio

Gene network analysis of candidate loci for human anorectal malformations

Posters: Complex Traits and Polygenic Disorders: abstract no. 1027TAnorectal malformations (ARMs) are birth defects that require surgery and carry significant chronic morbidity. Our genome-wide copy number variation (CNV) study had provided a wealth of candidate loci. To find out whether these candidate loci are related to important developmental pathways, we have ...postprin

HOXB5 Cooperates with NKX2-1 in the Transcription of Human RET

The enteric nervous system (ENS) regulates peristaltic movement of the gut, and abnormal ENS causes Hirschsprung's disease (HSCR) in newborns. HSCR is a congenital complex genetic disorder characterised by a lack of enteric ganglia along a variable length of the intestine. The receptor tyrosine kinase gene (RET) is the major HSCR gene and its expression is crucial for ENS development. We have previously reported that (i) HOXB5 transcription factor mediates RET expression, and (ii) mouse with defective HOXB5 activity develop HSCR phenotype. In this study, we (i) elucidate the underlying mechanisms that HOXB5 mediate RET expression, and (ii) examine the interactions between HOXB5 and other transcription factors implicated in RET expression. We show that human HOXB5 binds to the promoter region 5′ upstream of the binding site of NKX2-1 and regulates RET expression. HOXB5 and NKX2-1 form a protein complex and mediate RET expression in a synergistic manner. HSCR associated SNPs at the NKX2-1 binding site (-5G>A rs10900296; -1A>C rs10900297), which reduce NKX2-1 binding, abolish the synergistic trans-activation of RET by HOXB5 and NKX2-1. In contrast to the synergistic activation of RET with NKX2-1, HOXB5 cooperates in an additive manner with SOX10, PAX3 and PHOX2B in trans-activation of RET promoter. Taken together, our data suggests that HOXB5 in coordination with other transcription factors mediates RET expression. Therefore, defects in cis- or trans-regulation of RET by HOXB5 could lead to reduction of RET expression and contribute to the manifestation of the HSCR phenotype

Identification of a wide spectrum of ciliary gene mutations in nonsyndromic biliary atresia patients implicates ciliary dysfunction as a novel disease mechanism

Background: Biliary atresia (BA) is the most common obstructive cholangiopathy in neonates, often progressing to end-stage cirrhosis. BA pathogenesis is believed to be multifactorial, but the genetic contribution, especially for nonsyndromic BA (common form: > 85%) remains poorly defined. Methods: We conducted whole exome sequencing on 89 nonsyndromic BA trios to identify rare variants contributing to BA etiology. Functional evaluation using patients’ liver biopsies, human cell and zebrafish models were performed. Clinical impact on respiratory system was assessed with clinical evaluation, nasal nitric oxide (nNO), high speed video analysis and transmission electron microscopy. Findings: We detected rare, deleterious de novo or biallelic variants in liver-expressed ciliary genes in 31.5% (28/89) of the BA patients. Burden test revealed 2.6-fold (odds ratio (OR) [95% confidence intervals (CI)]= 2.58 [1.15–6.07], adjusted p = 0.034) over-representation of rare, deleterious mutations in liver-expressed ciliary gene set in patients compared to controls. Functional analyses further demonstrated absence of cilia in the BA livers with KIF3B and TTC17 mutations, and knockdown of PCNT, KIF3B and TTC17 in human control fibroblasts and cholangiocytes resulted in reduced number of cilia. Additionally, CRISPR/Cas9-engineered zebrafish knockouts of KIF3B, PCNT and TTC17 displayed reduced biliary flow. Abnormally low level of nNO was detected in 80% (8/10) of BA patients carrying deleterious ciliary mutations, implicating the intrinsic ciliary defects. Interpretation: Our findings support strong genetic susceptibility for nonsyndromic BA. Ciliary gene mutations leading to cholangiocyte cilia malformation and dysfunction could be a key biological mechanism in BA pathogenesis. Funding: The study is supported by General Research Fund, HMRF Commissioned Paediatric Research at HKCH and Li Ka Shing Faculty of Medicine Enhanced New Staff Start-up Fund