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Biomedical subjects

K K Cheng

Publications and source records attributed to K K Cheng.

At least 73 records · Page 4Linked to original sources
PubMed1996

Mutations in the RNA polymerase II transcription machinery suppress the hyperrecombination mutant hpr1 delta of Saccharomyces cerevisiae.

The soh1, soh2 and soh4 mutants were isolated as suppressors of the temperature-dependent growth of the hyperrecombination mutant hpr1 of Saccharomyces cerevisiae. Cloning and sequence analysis of these suppressor genes has unexpectedly shown them to code for components of the RNA polymerase II transcription complex. SOH2 is identical to RPB2, which encodes the second largest subunit of RNA polymerase II, and SOH4 is the same as SUA7, encoding the yeast transcription initiation factor TFIIB. SOH1 encodes a novel 14-kD protein with limited sequence similarity to RNA polymerases. Interestingly, SOH1 not only interacts with factors involved in DNA repair, but transcription as well. Thus, the Soh1 protein may serve to couple these two processes. The Soh1 protein interacts with a DNA repair protein, Rad5p, in a two-hybrid system assay. Soh1p may functionally interact with components of the RNA polymerase II complex as suggested from the synthetic lethality observed in soh1 rpb delta 104, soh1 soh2-1 (rpb2), and soh1 soh4 (sua7) double mutants. Because mutations in SOH1, RPB2 and SUA7 suppress the hyperrecombination phenotype of hpr1 mutants, this suggests a link between recombination in direct repeats and transcription.

Adenosine Triphosphatases↗
PubMed1995

Stopping drinking and risk of oesophageal cancer.

OBJECTIVE: To examine the effect of stopping drinking on the risk of oesophageal cancer. DESIGN: Hospital based case-control study. SETTING: Surgical departments of four district general hospitals and general practices in Hong Kong. SUBJECTS: Cases were 400 consecutive admissions of patients with histologically confirmed diagnosis of oesophageal cancer during a 21 month period in 1989-90 (87% response rate). Controls were 1598 patients selected from the same surgical departments as the cases and from the general practices from which the cases were originally referred (95% response rate). MAIN OUTCOME MEASURE: Relative risk of developing oesophageal cancer after stopping drinking (adjusted for age, education, place of birth, smoking, and diet). RESULTS: Current light drinking (< 200g ethanol/week) was not associated with significant increase in risk. Among former drinkers risk fell more quickly in moderate (200-599 g/week) than heavy (> or = 600 g/week) drinkers. Even among heavy drinkers, however, risk had dropped substantially after five to nine years of not drinking. The results suggest that the time taken for risk to return to that in subjects who never drink was 10-14 years for moderate drinkers and 15 years or more, if ever, for heavy drinkers. CONCLUSION: Risk of oesophageal cancer decreases fairly rapidly with time after abstaining from drinking. This new finding could be used in health promotion to encourage behavioural changes, especially in heavy drinkers, who have a very high risk of developing oesophageal cancer. It also suggests that alcoholic beverages have a strong effect on the late stage of carcinogenesis.

Adenocarcinoma↗
PubMed1995

Oesophageal cancer in never-smokers and never-drinkers.

Alcohol, tobacco and diet are the most important determinants of oesophageal cancer. Previous studies which examined smoking in non-drinkers and drinking in non-smokers did not report the main effects of dietary factors or the smoking and drinking effects adjusted for dietary factors. Data from a hospital-based case-control study in Hong Kong Chinese were used to examine the effects of dietary variables as well as tobacco and alcohol in never-drinkers and never-smokers. Among the 400 cases, there were 68 never-smokers and 53 never-drinkers; 540 were never-smokers and 407 were never-drinkers among 1598 controls. In never-smokers, alcohol drinking was strongly associated with risk. Use of green leafy vegetables and citrus fruits was protective. Among never-drinkers, smokers had increased risk, but the protective effect of vegetables and fruits did not reach statistical significance. In never-smokers and in never-drinkers alike, frequent consumption of pickled vegetables and being born in Teochew or Hokkien were associated with increased risks. This study provides further support for the independent effects of alcohol, tobacco and diet in oesophageal cancer.

Aged↗
PubMed1995

Animal study of phoenix total artificial heart implantation.

BACKGROUND: It is well accepted that a total artificial heart (TAH) can be used as a bridge to heart transplantation during the waiting period for organ donation. A series of combined studies, conducted by the Kaohsiung Veterans General Hospital, National Yang-Ming Medical College and Municipal Tainan Hospital, has been performed to improve the Phoenix artificial heart developed by Dr. Kevin Kuo-Tsai Cheng. METHODS: In growing calves (weighed about 80 kg), standard procedures were used to remove the hearts and replace them with the TAHs. Records were made of hemodynamic data, physiological responses, blood biochemistry data and physical activities after operation and until the death of the calves. Finally, autopsies were used to determine the causes of death. RESULTS: A total of 23 calves were studied. Twenty-two of them survived 1 to 12 days, or an average 4.95 days. One survived more than 30 days. All the calves could breathe, stand, eat and void by themselves two hours after operation. Respiratory failure was the major cause of death. CONCLUSIONS: No thrombus within the TAH was noted in the last five cases, meaning that turbulent flow or dead space of the TAH was improved. Better intensive care and prevention of infection will be the next challenge for long-term use of TAH.

Animals↗
PubMed1994

Doctor-shopping in Hong Kong: implications for quality of care.

Doctor-shopping is defined as the changing of doctors without professional referral in the same illness episode. Two surveys on samples of patients attending Government Out-Patient Departments (GOPDs) in Hong Kong in 1989 (n = 869) and 1990 (n = 901) estimated the prevalence of shopping at nearly 40%, the main reason being a persistence of symptoms. Doctor-shoppers were likely to be younger with higher expectations of health care and who expressed dissatisfaction about aspects of the present service. In Hong Kong, patients perceive western medicine to be more effective and have high expectations of the effects of western drugs, in particular, in their administration by injection. Patients should be warned about iatrogenic health risks incurred from doctor-shopping; health education programmes are needed to modify unrealistic views about quality care. Health care providers in a mixed care system should promote greater continuity of care between doctors and both the public and private sectors, and identify and resolve problems which may be responsible for discontinuity of care.

Adult↗
PubMed1994

Epstein-Barr virus-associated lymphoproliferative disorders in oral cavity after heart transplantation: report of a case.

Clinical manifestations of Epstein-Barr virus associated with post-heart transplant lymphoproliferative disorders (PTLD) are variable. Over one-half of the PTLD express extranodal presentations, of which gastrointestinal symptoms are the most common. Development of oral ulcers is an extremely rare initial manifestation with only three such cases having been reported. A case of oropharyngeal presentation of PTLD is described here. The clinical presentations and pathologic spectrums of PTLD are discussed. Posttransplant lymphoproliferative disorders are considered to be iatrogenic and life-threatening and are associated with immunosuppressive agents and Epstein-Barr virus infection. Early diagnosis and appropriate management could prevent the fatal progression of such disorders. The need to analyse tumor clonality along with observation of clinical presentations and microscopic pathology in order to diagnose PTLD is discussed.

Adolescent↗
PubMed1992

Pickled vegetables in the aetiology of oesophageal cancer in Hong Kong Chinese.

Oesophageal cancer is common in Chinese populations, but individual-based epidemiological studies have provided little explanation. A case control study with 400 cases and 1598 controls (800 hospital and 798 general practice) was conducted among Hong Kong Chinese. In multivariate analyses, statistically significant effects on risk were detected for several potentially preventable exposures with high attributable risks (ARs). These included preference for consuming drinks or soups at high temperature (AR = 14%), infrequent consumption of green leafy vegetables (AR = 15%) and citrus fruits (AR = 26%), ingestion of pickled vegetables (AR = 29%), tobacco smoking (AR = 44%), and alcohol drinking (AR = 48%). On the assumption of multiplicative risk, the combined AR due to these exposures was 89%. This is the first case control study to show an association between pickled vegetable consumption and oesophageal cancer risk. The finding considerably strengthens the evidence for carcinogenicity of N-nitroso compounds in man and helps to explain the very high risk among Chinese.

Aged↗
PubMed1992

Psychiatric morbidity in a general medical ward. Hong Kong's experience.

The psychiatric morbidity of a general hospital's male medical ward in Hong Kong was studied using a one-stage single-rater method. Medical diagnoses were made according to ICD-9 on 91.5% of patients and 24% were diagnosed with DSM-III. The most common mental disorders included substance use disorder, dementia, and delirium. Of all the patients, 8.5% were not medically diagnosable and 5.3% were given only psychiatric diagnoses, the majority of which were substance use disorders.

Adolescent↗
PubMed1992

Social stress and atherosclerosis in roosters.

1. Socially stressed roosters fed either plain mash or an atherogenic diet had a greater incidence and severity of aortic atherogenesis than similarly fed non-stressed birds. 2. Results demonstrated a significant atherogenic effect of stress in chickens even in the absence of hyperlipidaemia. 3. Lack of appreciable differences in plasma lipids between stressed and non-stressed birds suggested that the atherogenic effects of stress may be attributable to neuroendocrine responses. 4. Levels of HDLc of plain mash groups were significantly higher than in the atherogenic fed groups. 5. Haemodynamic data showed no treatment-related differences.

Animals↗
PubMed1992

Oesophageal cancer mortality in Europe: paradoxical time trend in relation to smoking and drinking.

The main risk factors for oesophageal cancer previously identified in western Europe are tobacco smoking and alcohol drinking. However, a study of the time trend from 1951 to 1985 of the mortality from oesophageal cancer in 17 European countries shows that, except among the younger age groups in men, oesophageal cancer had either decreased or increased only slightly in most countries. This trend differed from that of lung cancer, cirrhosis and alcohol consumption which had in general increased substantially during the period. The results strongly suggest that population-wide changes in certain undetermined risk/protective factor(s), one possibility of which is the consumption of fruit, had overridden the effect of tobacco and alcohol and resulted in a reduction of oesophageal cancer risk. Apart from further efforts to reduce smoking and drinking, studies to identify the factor(s) will be of great public health importance to the prevention of oesophageal cancer.

Aged↗
PubMed1992

Surgical repair of ventricular septal defect without ventriculotomy in the first 12 months of life.

Sixty-eight infants with clinical evidence of a large ventricular septal defect (VSD), refractory to conventional medical treatment, underwent surgical closure within the first 12 months of life from August 1987 to June 1991. There were 43 males and 25 females. The ages of the patients ranged from two to 12 months, with a mean age of 6.6 months. The mean body weight of the patients was 5.4 kg (range, 2.3-10 kg). Surgery was performed because of intractable heart failure in 27 infants (39.7%), failure to thrive in 40 (58.8%), repeated pneumonia in 43 (63.2%) and prolonged endotracheal intubation in nine (13.2%). There were 21 patients with a supracristal VSD (30.9%) and 47 patients with perimembranous VSD (69.1%). Nine patients (13.2%) had preoperative cardiac catheterization. Transatrial repair of perimembranous VSDs and transpulmonary repair of supracristal VSDs was used exclusively without ventriculotomy. Surgically induced heart blocks did not occur in any of the patients. Only two patients (2.9%) died during the early postoperative period. Diagnosis in most cases was confirmed by the present advanced integrated color Doppler echocardiographic technology which is widely used by pediatric cardiologists. There was no need to perform cardiac catheterization in most patients with VSDs. The morbidity and mortality were very low. We strongly suggest that for infants with a large VSD, primary repair should be the procedure of choice.

Female↗
PubMed1991

A prospective study of post-transfusion non-A, non-B (type C) hepatitis following cardiovascular surgery in Taiwan.

In an attempt to investigate the incidence and clinical course of non-A, non-B (NANB) hepatitis following blood transfusion in Taiwan, 288 patients who underwent cardiovascular surgery and received blood transfusion were followed prospectively with serum liver aminotransferase levels and viral hepatitis markers for at least six months. None had any past history of liver disease or drug abuse. All blood donors were tested for serum hepatitis B surface antigen and alanine aminotransferase (ALT) (greater than 45 U/L). Thirty-seven (12.8%) patients developed PTH. 34 (91.9%) were considered to be cases of NANB hepatitis, 2 (5.4%) were cytomegalovirus hepatitis, and one (2.7%) was caused by Epstein-Barr virus. No one developed hepatitis B post-transfusion hepatitis (PTH). Of the 34 NANB PTH patients, 15 (44.1%) were asymptomatic, 16 (47.1%) had clinical symptoms, and 9 (26.5%) had serum total bilirubin levels higher than 2 mg/dl. There was no case of fulminant hepatic failure. Of 26 NANB PTH patients who were followed up for more than one year, 15 (57.7%) still had abnormal serum ALT levels. The incubation period of NANB PTH ranged from 2 to 16 (mean 6.1 +/- 3.2) weeks. Of the 37 PTH patients, 32 (86.5%) were found to have anti-HCV seroconversion during one year follow-up period. NANB PTH is as common in Taiwan as in the United States and Japan, and is demonstrated by this study to be due mostly to HCV.

Adolescent↗
PubMed1991

Electromechanical effects of angiotensin in human atrial tissues.

Effects of exogenous angiotensin I (AI) and angiotensin II (AII) on action potential and contractile force of isolated atrial trabeculae obtained at cardiac surgery were studied by means of a standard microelectrode technique. In trabeculae driven electrically at a cycle length of 1 s, AII (8.4 nM - 8.4 microM) increased the contractile force with a peak effect occurred near 0.84 microM. The inotropic effect of AII was markedly inhibited by 1 microM saralasin or 1 microM diltiazem. AI (0.65 nM - 6.5 microM) also induced positive inotropic effect in a concentration-dependent manner. This inotropic effect was decreased significantly after 3 microM captopril pretreatment. In trabeculae active spontaneously in normal Tyrode solution, AI and AII increased significantly rate of diastolic depolarization and spontaneous discharges as well as force of contraction. These chronotropic effects were inhibited by captopril and saralasin, respectively. Captopril (0.3 nM - 3 microM) or saralasin (0.001 - 1 microM) alone also induced dose-dependent negative chronotropic effects. The present findings suggest the existence of functional AII receptors in human atrial tissues. The stimulatory effects of angiotensin appear to be related to an increase in cellular calcium.

Action Potentials↗