Biomedical subjects

W L Cheung

Publications and source records attributed to W L Cheung.

18 recordsLinked to original sources

PubMed2006

Cost of tobacco-related diseases, including passive smoking, in Hong Kong.

BACKGROUND: Costs of tobacco-related disease can be useful evidence to support tobacco control. In Hong Kong we now have locally derived data on the risks of smoking, including passive smoking. AIM: To estimate the health-related costs of tobacco from both active and passive smoking. METHODS: Using local data, we estimated active and passive smoking-attributable mortality, hospital admissions, outpatient, emergency and general practitioner visits for adults and children, use of nursing homes and domestic help, time lost from work due to illness and premature mortality in the productive years. Morbidity risk data were used where possible but otherwise estimates based on mortality risks were used. Utilisation was valued at unit costs or from survey data. Work time lost was valued at the median wage and an additional costing included a value of USD 1.3 million for a life lost. RESULTS: In the Hong Kong population of 6.5 million in 1998, the annual value of direct medical costs, long term care and productivity loss was USD 532 million for active smoking and USD 156 million for passive smoking; passive smoking accounted for 23% of the total costs. Adding the value of attributable lives lost brought the annual cost to USD 9.4 billion. CONCLUSION: The health costs of tobacco use are high and represent a net loss to society. Passive smoking increases these costs by at least a quarter. This quantification of the costs of tobacco provides strong motivation for legislative action on smoke-free areas in the Asia Pacific Region and elsewhere.

Absenteeism↗

PubMed2006

Promoting smoking cessation among the elderly: what are the predictors of intention to quit and successful quitting?

PURPOSE: To assess the predictors of smoking cessation and intention to quit among the Chinese elderly smokers. DESIGN: A cross-sectional survey of elderly smokers. SETTING: Shamsuipo district, Hong Kong. SUBJECT: A total of 1,318 elderly were interviewed (response rate = 83%). MEASURES: A structured questionnaire was used for data collection. The questionnaire sought information on the subject's sociodemographic background and smoking habits. The predictors for successful quitting and intention to quit were assessed by chi-square tests and multiple logistic regression. RESULTS: Of the respondents, 20.2% were current smokers, 25.4% were ex-smokers, and 54.4% were never smokers. Of the smoker (current and ex-smokers) respondents, 55.7% (335/601) had successfully quit at the time of enumeration. The predictors of quitting were living with others, receiving assistance for mobility, being nondrinkers, smoking for shorter duration, and smoking more cigarettes per day. Having health problems in the past, smoking for shorter duration, and smoking fewer cigarettes per day were predictors of intention to quit smoking. CONCLUSION: The study identified several predictors of successful quitting that could help improve the provision of current smoking cessation services. Population-based smoking cessation programs, especially those targeted to elderly, should take these predictors into consideration in the design of interventions.

Aged↗

PubMed2003

Acute bacterial gastroenteritis: a study of adult patients with positive stool cultures treated in the emergency department.

OBJECTIVES: To investigate the presenting clinical features of acute bacterial gastroenteritis in adult patients treated as outpatients in the emergency department (ED), and the pathogens responsible in this setting and population; and to identify the frequency with which positive stool culture result changes management. METHOD: This was a retrospective study of all patients who attended the accident and emergency department of an university affiliated hospital in Hong Kong over a 12 month period, who satisfied the following inclusion criteria: (a) age >/=16, (b) presented with acute gastroenteritis, (c) treated as outpatients with or without observation, and (d) had positive stool cultures. RESULTS: One hundred and thirty patients were included. Pathogens identified were Vibrio parahaemolyticus (42.3%), Samonella spp (34.6%), Plesiomonas spp (9.2%), Campylobacter spp (6.9%), Aeromonas spp (6.9%), and Shigella spp (6.2%). Mean highest body temperature was 37.5 degrees C (95% confidence intervals (CI) 37.3 to 37.6). Bloody diarrhoea was present in 14 patients (10.8%). Mean duration of diarrhoea, from onset to the completion of stay in ED, was 2.2 days (95% CI 1.7 to 2.7). Likewise, mean duration of abdominal pain was 1.8 days (95% CI 1.5 to 2.1). Mean number of unformed stools per day was 9.3 (95% CI 8.3 to 10.3). Change of management, subsequent to the availability of positive stool culture results, was not required in 115 (88.5%) patients. Ciprofloxacin resistance occurred in eight (6.2%) cases, and seven of nine campylobacter isolates. Campylobacter positive patients had a significantly longer duration of abdominal pain (p=0.0236) and were less likely to be dehydrated (p=0.0103). CONCLUSIONS: Most patients with bacterial gastroenteritis do not present with high fever, bloody diarrhoea, or persistent diarrhoea, but generally have quite severe diarrhoea. Stool cultures do not change management for most patients. Vibrio parahaemolyticus is the commonest bacterial pathogen identified.

Acute Disease↗

PubMed2001

Histone H3 lysine 4 methylation is mediated by Set1 and required for cell growth and rDNA silencing in Saccharomyces cerevisiae.

Histone methylation is known to be associated with both transcriptionally active and repressive chromatin states. Recent studies have identified SET domain-containing proteins such as SUV39H1 and Clr4 as mediators of H3 lysine 9 (Lys9) methylation and heterochromatin formation. Interestingly, H3 Lys9 methylation is not observed from bulk histones isolated from asynchronous populations of Saccharomyces cerevisiae or Tetrahymena thermophila. In contrast, H3 lysine 4 (Lys4) methylation is a predominant modification in these smaller eukaryotes. To identify the responsible methyltransferase(s) and to gain insight into the function of H3 Lys4 methylation, we have developed a histone H3 Lys4 methyl-specific antiserum. With this antiserum, we show that deletion of SET1, but not of other putative SET domain-containing genes, in S. cerevisiae, results in the complete abolishment of H3 Lys4 methylation in vivo. Furthermore, loss of H3 Lys4 methylation in a set1 Delta strain can be rescued by SET1. Analysis of histone H3 mutations at Lys4 revealed a slow-growth defect similar to a set1 Delta strain. Chromatin immunoprecipitation assays show that H3 Lys4 methylation is present at the rDNA locus and that Set1-mediated H3 Lys4 methylation is required for repression of RNA polymerase II transcription within rDNA. Taken together, these data suggest that Set1-mediated H3 Lys4 methylation is required for normal cell growth and transcriptional silencing.

Animals↗

PubMed2001

Community-acquired pneumonia--implementation of a prediction rule to guide selection of patients for outpatient treatment.

The aim of this study was to determine the outcomes of outpatient treatment of community-acquired pneumonia (CAP) when a prediction rule was followed by emergency physicians to guide the selection of patients. This was a prospective observational study conducted at the emergency department of a university-affiliated hospital in Hong Kong, China. A clinical prediction rule was implemented to guide the selection of patients with CAP for outpatient treatment. All subsequent hospitalizations gial presentation were recorded, and the reasons were assessed. The utilization of the observation unit was incorporated into the treatment algorithm. Of 72 patients with CAP followed up as outpatients, 60 (83.3%) were treated successfully, nine (12.5%) required subsequent hospitalization within 30 days, and three (4.2%) were lost to follow-up. None of the patients died, and none required admission to the intensive care unit. Factors associated with subsequent hospitalization include: tuberculosis, underlying malignancy, persistent fever, comorbidity (rheumatoid arthritis and severe osteoporosis), intravenous drug addiction and alcoholism. The observation ward was utilized in 10 (16.7%) patients successfully treated as outpatients. It is concluded that the prediction rule can be safely implemented as a guide for emergency physicians. The short-stay observation unit may be usefully employed for treating low-risk CAP.

Adolescent↗

PubMed2000

Acetylation and chromosomal functions.

Since the initial discovery of histone acetyltransferases, numerous reports have established that histone acetyltransferases and histone deacetylases regulate transcription by acetylating and deacetylating histones, respectively. Recent studies have focused on the effects of histone acetylation on gene expression regulation during development and the roles of histone hypoacetylation in the maintenance of centromeric structure, X-inactivation and genomic imprinting. Recent findings have also shown that the functions of non-histone proteins can also be regulated by acetylation. Together, these data highlight the importance of acetylation of histones and non-histone proteins in a variety of chromosomal functions.

Acetylation↗

PubMed2000

Synergistic coupling of histone H3 phosphorylation and acetylation in response to epidermal growth factor stimulation.

Histone acetylation and phosphorylation have separately been suggested to affect chromatin structure and gene expression. Here we report that these two modifications are synergistic. Stimulation of mammalian cells by epidermal growth factor (EGF) results in rapid and sequential phosphorylation and acetylation of H3, and these dimodified H3 molecules are preferentially associated with the EGF-activated c-fos promoter in a MAP kinase-dependent manner. In addition, the prototypical histone acetyltransferase Gcn5 displays an up to 10-fold preference for phosphorylated (Ser-10) H3 over nonphosphorylated H3 as substrate in vitro, suggesting that H3 phosphorylation can affect the efficiency of subsequent acetylation reactions. Together, these results illustrate how the addition of multiple histone modifications may be coupled during the process of gene expression.

Acetylation↗

PubMed2000

An international comparison of childhood injuries in Hong Kong.

OBJECTIVES: This study describes 7813 childhood injuries in Shatin, Hong Kong. Supplementary analyses include developmental specificity of external causes and comparison with international childhood injury data. METHODS: Children aged 0-15 attending the accident and emergency (A&E) department of the Prince of Wales Hospital in Hong Kong were recruited for the study. Attendance records of participants from the A&E department were analyzed. Details concerning the injury, including the International Classification of Diseases, ninth revision, external cause of injury (E code), nature of injury (N code), abbreviated injury scale, and injury severity scale constitute core measurements, along with participants' age, gender, and respective A&E procedural data. RESULTS: Males (65.7%) and fall related injuries (44.2%) predominate, while contusion (34.6%) is the prevailing nature of injury. Two age external cause dimensions are derived from a correspondence analysis. Children 0-1 years old are associated with falls, poisoning, scalds, and machinery related injury. Adolescents aged 12-15 are associated with motor related injury, animal related injury, and cuts/piercings. In comparison with international data, unintentional child injuries in Hong Kong comprised more falls but fewer poisonings and burns. CONCLUSION: A large proportion of falls, along with low proportion of poisonings and burns, are characteristics of childhood injury profile in Hong Kong. From the results of age external cause correspondence analysis, prevention strategies for different external cause should be developmentally specific.

Adolescent↗

PubMed1999

pRb is required for MEF2-dependent gene expression as well as cell-cycle arrest during skeletal muscle differentiation.

BACKGROUND: The onset of differentiation-specific gene expression in skeletal muscle is coupled to permanent withdrawal from the cell cycle. The retinoblastoma tumor-suppressor protein (pRb) is a critical regulator of this process, required for both cell-cycle arrest in G0 phase and high-level expression of late muscle-differentiation markers. Although the cell-cycle defects that are seen in pRb-deficient myocytes can be explained by the well-described function of pRb as a negative regulator of the transition from G1 to S phase, it remains unclear how pRb positively affects late muscle-gene expression. RESULTS: Here, we show that the myogenic defect in Rb-/- cells corresponds to a deficiency in the activity of the transcription factor MEF2. Without pRb, MyoD induces the accumulation of nuclear-localized MEF2 that is competent to bind DNA yet transcriptionally inert. When pRb is present, MyoD stimulates the function of the MEF2C transcriptional activation domain and the activity of endogenous MEF2-type factors. Co-transfection of MyoD together with an activated form of MEF2C containing the Herpesvirus VP16 transcriptional activation domain partially bypasses the requirement for pRb and induces late muscle-gene expression in replicating cells. This ectopic myogenesis is nevertheless significantly augmented by co-expression of an E2F1-pRb chimeric protein that blocks the cell cycle. CONCLUSION: These findings indicate that pRb promotes the expression of late-stage muscle-differentiation markers by both inhibiting cell-cycle progression and cooperating with MyoD to promote the transcriptional activation activity of MEF2.

Animals↗

PubMed1997

Potassium permanganate poisoning--a rare cause of fatal self poisoning.

Attempted suicide by self poisoning is common because of the ready availability of drugs, whether prescribed or bought over the counter. In some cases, the ingestion of seemingly innocuous household products or chemicals can result in death. Potassium permanganate is an example. Poisoning with potassium permanganate can be fatal when a significant amount is ingested, as shown by a patient who suffered both the corrosive and systemic toxic effects of this chemical.

Adult↗

PubMed1996

Inhibition of myogenic bHLH and MEF2 transcription factors by the bHLH protein Twist.

The myogenic basic helix-loop-helix (bHLH) and MEF2 transcription factors are expressed in the myotome of developing somites and cooperatively activate skeletal muscle gene expression. The bHLH protein Twist is expressed throughout the epithelial somite and is subsequently excluded from the myotome. Ectopically expressed mouse Twist (Mtwist) was shown to inhibit myogenesis by blocking DNA binding by MyoD, by titrating E proteins, and by inhibiting trans-activation by MEF2. For inhibition of MEF2, Mtwist required heterodimerization with E proteins and an intact basic domain and carboxyl-terminus. Thus, Mtwist inhibits both families of myogenic regulators and may regulate myotome formation temporally or spatially.

Animals↗

PubMed1991

Emergency surgical treatment for nonvariceal bleeding of the upper part of the gastrointestinal tract.

Endoscopic and biochemical data were collected prospectively from 1,530 patients admitted with nonvariceal bleeding of the upper part of the gastrointestinal tract between September 1985 and June 1989. Therapeutic endoscopy was done for 93 patients who underwent emergency surgical treatment for bleeding, subsequently required in 29 patients with seven postoperative fatalities. In contrast, 31 (15.7 per cent) of 198 patients (mortality rate of 9.6 per cent at 30 days) died in the hospital who had undergone emergency operation in whom therapeutic endoscopy had not been performed; data for this latter group is now presented. At admission, a greater likelihood of emergency operation was associated with a systolic blood pressure of 100 millimeters of mercury and endoscopic stigmatas of recent hemorrhage (ESRH) (p less than 0.001). Rebleeding rates for the presence of fresh blood, active spurting and oozing hemorrhage or visible vessel in an ulcer base were 26.5, 28.9 and 35.9 per cent, respectively. Endoscopic stigmatas were thus associated with an increased risk of bleeding (p less than 0.0001) and rebleeding led to a sixfold increase in the mortality rate. Congestive cardiac failure, chronic obstructive airway disease, chronic renal failure and a history of previous malignant disease were each associated with postoperative mortality rates of more than 50 per cent. An increased risk of mortality after emergency operation was related to age (p less than 0.0001), preoperative (p less than 0.002) and total (p less than 0.0001) blood transfusion requirement. Immediate operation after resuscitation and endoscopy was required in 87 patients; 11 deaths (hospital mortality rate of 12.7 per cent and 9.2 per cent at 30 days) occurred in this group compared with 20 fatalities (18.0 per cent) documented in 111 patients (9.9 per cent at 30 days) who underwent surgical treatment for rebleeding. We conclude that age, concomitant medical illness and preoperative and total transfusion requirements are each related to outcome after emergency operations. Such urgent intervention is best avoided if at all possible in patients with severe concomitant medical illness.

Acute Disease↗

PubMed1991

Risk factors for mortality in patients with gastric adenocarcinoma presenting with acute haemorrhage.

We collected clinical, laboratory and endoscopic data prospectively in patients presenting with acute non-variceal upper gastrointestinal bleeding admitted to the care of one surgical team. During a 30-month period 52 patients were subsequently proven to have gastric adenocarcinoma; 30 patients underwent elective operation, and emergency surgery for bleeding was performed on 14 occasions. There were 13 hospital deaths (25%), 13.5% at 30 days. Emergency surgery was associated with a higher mortality rate (42.9%) than elective procedures (13.3%) (P less than 0.03). Factors associated with a poor prognosis were active haemorrhage at initial endoscopy, an admission blood urea nitrogen greater than 16 mmol/l, preoperative transfusion greater than 4 units, total transfusion greater than or equal to 9 units and a lowest recorded haemoglobulin during hospitalization of less than 7.5 g/dl. The unacceptably high mortality rate associated with surgery for continued haemorrhage or rebleeding episodes suggest that earlier elective operative intervention be advocated in patients presenting with acute bleeding and in whom gastric cancer is visualized. This is recommended particularly if the initial bleeding episode is severe, or active haemorrhage is visualized during initial endoscopy.

Acute Disease↗

PubMed1990

Six-month combination chemotherapy for cervical tuberculous lymphadenitis.

A prospective study was undertaken to determine the effectiveness of a 6-month four-drug regimen in the treatment of 123 patients with cervical tuberculous lymphadenitis. The results showed that the disease was satisfactorily controlled with residual lymph nodes which did not necessitate further chemotherapy in 14.6% of patients at 3 years follow-up. Recurrence requiring further chemotherapy occurred in 3.3% of patients between 9 and 28 months. Wound sinuses occurred in 3.3% of patients and all healed with conservative treatment. The culture results and numbers of lymph nodes at presentation had no effect on outcome at 3 years. An excisional procedure was associated with a lower incidence of residual lymph nodes than an incisional biopsy. Minor gastrointestinal upset from drug treatment was common, but only 2.4% of patients needed a change of regimen. Six months of combination chemotherapy is adequate for the treatment of the disease.

Adolescent↗

PubMed1988

Tuberculous cervical abscess: comparing the results of total excision against simple incision and drainage.

In 40 patients with tuberculous cervical abscesses a prospective study was undertaken to determine the results of surgical treatment by either total excision or incision and drainage, together with 6 months of chemotherapy in both groups. While both procedures were well tolerated, the results showed that 17/22 (77 per cent) of those having a simple drainage procedure required a second operation to excise the residual infected lymph glands because of persistent sinus discharge, recurrent abscesses or enlarging lymphadenopathy. In contrast, 17/18 (94 per cent) of those having total excision as the primary procedure had no local ward problem afterwards. Most of the patients remained asymptomatic after completion of the chemotherapy but small painless lymph nodes might still be palpable during follow-up at 2 years.

Abscess↗

PubMed1987

Squamous cell carcinoma of the renal pelvis.

From 1970 to 1985 we treated 144 cases of malignant tumors of the kidney. Of these patients only 11 (8 per cent) had squamous cell carcinoma of the renal pelvis compared to transitional cell carcinoma of the renal pelvis in 53 per cent, renal cell carcinoma in 37 per cent and other types in 2 per cent. In all patients the squamous cell carcinoma was associated with chronically infected staghorn renal calculi of long duration. The patients usually presented late with extensive local infiltration, making surgical resection difficult. In addition, poor response to surgery, radiotherapy and chemotherapy resulted in a poor prognosis and short survival. A summary of our cases and a review of the literature are presented.

Adult↗

PubMedDate not supplied

Bleeding peptic ulcer: a prospective evaluation of risk factors for rebleeding and mortality.

Clinical, endoscopic, and laboratory data were collected prospectively in 701 patients with bleeding peptic ulcer. The overall rebleeding rate was 16.1% and increased the risk of a fatal outcome by 17 fold (1.2% versus 20.6%, p less than 0.001). Rebleeding was documented in more than 75% of the group who did not survive following initial conservative management. Rebleeding was more likely (24.1% versus 14.2%, p less than 0.02) when shock was present on admission and the risk of a rebleed was doubled in patients over 60 years of age (22.1% versus 10.9%, p less than 0.001). Ulcers greater than 1 cm in size carried twice the risk of rebleeding (23.9% versus 12.4%, p less than 0.002). Concomitant medical illness had a significant adverse effect on outcome (p less than 0.05). Shock on admission was associated with a doubling of mortality figures (9.5% versus 3.7%, p less than 0.01). The identification of endoscopic stigmata of recent hemorrhage (ESRH) tripled the risk of mortality (7.5% versus 2.4%, p less than 0.002), ESRH were more frequently encountered when ulcer size was larger than 1 cm (61.4% versus 39.8%, p less than 0.001). Respective mortality rates for ulcers less than or equal to 1 cm and greater than 1 cm in size were 1.6% and 12.5% (p less than 0.001), corresponding mortality figures for patients over 60 years of age being 4.4% and 16.4% (p less than 0.002). The risk of a rebleed tripled (6.7% versus 2.6%, p less than 0.02) when ESRH were evident. There was a 6-fold increase in mortality following emergency surgery when compared with conservative management of patients in whom no surgical intervention was necessary (2.6% versus 14.9%, p less than 0.001). In summary, age over 60 years, previous medical illness, shock on admission, large ulcer size, and ESRH were each associated with an increased risk of rebleeding and mortality.

Female↗

PubMedDate not supplied

Hypotension and endoscopic stigmata of recent haemorrhage in bleeding peptic ulcer: risk models for rebleeding and mortality.

Clinical and endoscopic data were collected prospectively in 1050 patients with bleeding peptic ulcer admitted between September 1985 and July 1989 to the care of one surgical team. Seventy-nine patients underwent therapeutic endoscopy soon after admission and in 129 patients either immediate or early elective surgery was performed. Eight hundred and forty-two patients, in whom therapeutic endoscopy was not performed at any stage, underwent initial conservative management and data from this latter group are now presented. Shock on admission was defined as systolic blood pressure (BP) less than or equal to 100 mmHg on presentation. There were 10 deaths of 147 shocked patients (6.8%) compared with only 25 deaths of 695 patients (3.6%) not in shock (P less than 0.08). Bleeding recurred in 30 patients (20.4%) shocked on presentation but in only 96 (13.8%) with a BP greater than 100 mmHg (P less than 0.05). Twenty-one of 358 patients (5.9%) with endoscopic stigmata of recent haemorrhage (ESRH) died, but only 14 of 484 patients (2.9%) without such stigmata (P less than 0.05) died. In shocked patients rebleeding was evident in 21 of 73 (28.8%) cases with ESRH but in only 9 of 74 (12.2%) patients in whom ESRH were absent (P less than 0.02). In the absence of fresh blood at endoscopy rebleeding occurred in 22 of 124 (17.8%) shocked patients and only 74 of 629 (11.8%) of those not shocked on presentation (P less than 0.07). When ulcer size was documented rebleeding rates for ulcers less than or equal to 1 cm, less than or equal to 2 cm and greater than 2 cm in size were 54 of 485 (11.1%), 30 of 142 (21.2%) and 12 of 44 (27.3%) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗