Biomedical subjects

K K Cheng

Publications and source records attributed to K K Cheng.

At least 91 records · Page 5Linked to original sources

PubMed1991

Electropharmacological effects of sandostatin in human atrial fibers.

We studied the actions of sandostatin (0.1-1000 nM), an analogue of somatostatin, on human atrial tissues obtained from hearts of 20 patients undergoing corrective cardiac surgery. In 3 preparations showing fast response action potential in normal [K]0 Tyrode solution, sandostatin induced little effect, even at the highest concentration (1 microM). In 10 preparations showing a slow rate of phase-0 depolarization when atrial fibers were depolarized (maximum diastolic potential near -40 mV) in high [K]0 (27 mM), sandostatin at concentrations as low as 1 nM decreased significantly the velocity of the upstroke, and the amplitude of slow response of the action potential as well as the force of contraction. In 6 experiments on spontaneously active atrial fibers (maximum diastolic potential = -53.8 +/- 2.7 mV), sandostatin increased the spontaneous cycle length in a fashion dependent upon concentration. The decrease in spontaneous rate of firing was associated with an inhibition of the late diastolic slope, a change also induced by somatostatin. A longer period of washout, however, (30 min or longer) was required for complete recovery from the depressant effects. Sandostatin (0.1-100 nM) also depressed triggered activity induced by cardiotonic agents. The present findings indicate that sandostatin induces a prolonged action in human atrial cells. Sandostatin may depress abnormal automatic rhythms through an inhibition of transmembrane influx of calcium.

Action Potentials↗

PubMed1991

Initial results of laser angioplasty under angioscopic guidance for salvage of an ischemic lower limb: preliminary report.

From March to July 1989, nine patients at risk for peripheral artery disease underwent intraoperative Nd:YAG laser angioplasty using angioscopy at the Veterans General Hospital (Taipei, Taiwan, Republic of China). Following the laser angioplasty, balloon dilatation was performed in all cases. Eight men and one woman at an average age of 68 were included in the study (range: 58 to 78 years old). Ischemic symptoms included five patients with disabling claudication, four with pain at rest and one with gangrene on the toes. Eight of the nine patients had complete occlusions ranging from 2 to 19 cm in length. Two patients had high degree multiple segmental stenosis of the superficial femoral artery from 1 to 2 cm in length. Initial clinical success (indicated by relief of symptoms and increase in Doppler ankle pressure and index) and improvement in the angiographic luminal diameter was noted in 9 of 10 occluded vessels (90%) that underwent Nd:YAG laser treatment which was delivered at 10 to 12 watts through laser probes. Prelaser intraluminal diameter increased from 0.05 +/- 0.07 to 0.53 +/- 0.07 mm, Doppler ankle pressure index rose from 0.51 +/- 0.12 to 0.81 +/- 0.12, Doppler ankle pressure increased from 62.44 +/- 16.10 to 104 +/- 21.21 mmHg and the amplitude of pulse volume recorder at ankle level rose from 5.77 +/- 2.80 to 12.11 +/- 2.77 mm as compared with prelaser therapy (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1991

Transatrial-transpulmonary repair of tetralogy of Fallot: extensive infundibular septum resection.

Twenty-seven patients with tetralogy of Fallot underwent total correction during the period from February 1988 through October 1989. Their ages ranged from 11 months to 12 years (mean 3.3 +/- 4.9 years). For 11 patients, the repair was made via the conventional transventricular approach and a partial resection of the infundibular septum. On the other 16 patients, a transatrial-transpulmonary approach was used with total resection of the anterior deviated infundibular septum, with or without a miniventriculotomy incision (1-10 mm). The exposure of the ventricular septal defect (VSD) through the right atrium, and the right ventricular outflow tract (RVOT) through the pulmonary artery in patients with tetralogy of Fallot was excellent. There were no significant differences between transatrial-transpulmonary repair and transventricular repair of the tetralogy of Fallot with respect to pulmonary artery (PA) index (273.2 +/- 36.6 versus 249.9 +/- 63.2 mm2/BSA) or the postoperative ratio of right ventricle/left ventricle (RV/LV) systolic pressure (0.55 +/- 0.16 versus 0.61 +/- 0.17). Postoperative intensive care was simple and uncomplicated, with a significantly lower catecholamine demand, less bleeding, fewer blood transfusions, and shorter stays in the cardiac Intensive Care Unit (ICU). There was no mortality in this series. This method of repair can be successfully accomplished in most patients with tetralogy of Fallot, with resultant preservation of right ventricular function (intact right ventricle).

Child↗

PubMed1990

Smoking among young doctors in Hong Kong: a message to medical educators.

A survey was conducted using a self-administered questionnaire to examine the smoking habits, attitudes and practices of 151 doctors in their pre-registration year. The response rate was 88%. Over 80% of the respondents had never smoked. Less than 7% of the men smoked daily and none of the women smoked. Despite a very low smoking rate among the respondents, there were shortcomings in attitudes and practices. The study demonstrated that even in a place like Hong Kong, where the social climate on smoking is already changing in a healthy direction, significant deficiencies in our graduates can still arise if teaching on smoking and its control is undertaken in an uncoordinated manner. We argue that a specific course on the important aspects of smoking and health should be introduced into all undergraduate curricula. This is of special importance in countries where smoking is one the increase and where governmental actions on smoking control are inadequate in comparison with the marketing efforts of powerful multinational tobacco companies. Considering the magnitude of smoking as a global health problem, it is the very least that medical educators should do in combating this pandemic.

Adult↗

PubMed1990

Risk factors of suicide among schizophrenics.

This case control study included 74 Chinese schizophrenics (DSM-III criteria) who died of suicide and 74 age- and sex-matched nonsuicide schizophrenics. Sociodemographic variables were unrelated with suicide. Associations were found between suicide and severity of illness (more frequent admissions, higher dose of medication and earlier appointments), history of major depressive episodes and suicidal attempts, last admission for reasons other than schizophrenic symptoms alone, and suicidal ideas on mental state examination. The last 2 factors, together with the maintenance dose of medication, were identified as the most important risk factors by logistic regression analysis.

Adult↗

PubMed1990

Experimental implantation of human umbilical vein grafts in dogs.

Locally produced human umbilical vein grafts (HUVG), using glutaraldehyde as a stabilizing agent, were implanted into 24 mongrel dogs. Different arterial bypass procedures, using HUVG, were carried out in three experimental groups. In Group I, 2 dogs underwent femorofemoral crossover bypass procedures and 6 dogs received aortoiliac bypass procedures. Thrombus formation was found in all HUVG implants of Group I. In Group II, 8 dogs received abdominal aorta HUVG interposition. In Group III, 8 dogs received abdominal aorta HUVG bypass procedures. Patent HUVG implants without thrombus formation, demonstrated by postoperative angiogram, were found in 6 dogs of Group II and 5 dogs of Group III. Morphological and histological studies of the patent HUVG implants retrieved after sacrifice showed on sign of rejection, biodegeneration, or aneurysmal formation. Our preliminary experience with this cost-effective locally produced human umbilical vein graft material was promising and may pave the way to further clinical applications.

Animals↗

PubMed1990

Radionuclide transit studies for esophageal function before and after esophageal transection and devascularization.

Nonobstructive swallowing disturbance is a common complication following esophageal transection and devascularization to control bleeding from esophageal varices. From July 1983 to July 1984, 12 patients underwent both a radionuclide esophageal transit study (RETS) and a barium swallowing fluoroscopic study (BSFS) before and after surgery to evaluate esophageal function. Before surgery, 9 of the 12 patients had no swallowing disturbance and the RETS was normal in 8 cases, and the BSFS was normal in all cases. Three patients who received sclerotherapy on more than 3 occasions suffered from swallowing disturbances and both the RETS and BSFS detected their defective passage. The average distal 1/3 segmental and total esophagus transit times were 11.5 +/- 9.9 seconds and 13.0 +/- 10.6 seconds among symptom-free patients; and 24.8 +/- 11.8 seconds and 30.1 +/- 14.6 seconds among swallowing-disturbance patients. The time prolongation was significant (p less than 0.005). After surgery, 5 of 9 preoperative symptom-free patients suffered from swallowing disturbances for 10 days and then became symptom free. Their serial follow-up RETS and BSFS at 1 month, 3 months and 6 months all showed normal results. One preoperative symptom-free patient suffered from a mild swallowing disturbance for 2 months. However, only RETS, but not BSFS, demonstrated the prolonged proximal segmental esophageal transit time at 1 month postoperatively. The remaining 6 patients suffered from prominent swallowing disturbances and their initial postoperative RETS demonstrated prolonged defective transit or the presence of gastroesophageal (GE) reflux. All these events were confirmed by both tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

[Results of vascular reconstruction in lower limbs ischemia: a six-year clinical experience].

During the period between Dec. 1982 to Nov. 1988, a total of 412 patients with 471 limbs at risk of peripheral arterial occlusive disease underwent vascular surgical treatment at the Veterans General Hospital. There were 382 men and 30 women, who ranged in age from 20 to 84 years (mean 63.17 +/- 11.85 years). 95 cases were isolated aortoiliac occlusive disease, 94 cases were combined aortoiliac and femoropopliteal disease, 169 cases were femoropopliteal occlusive disease and 54 cases were femorotibialperoneal occlusive disease. Various reconstructive procedures were performed in the these patients. The cumulative limb salvage rate (LSR) exceeded cumulative patency rate (CPR) in all categories and the result of LSR and CPR were 97.6% and 91% for aortoiliac reconstructive surgery in six years, 96% and 77% for above-knee femoropopliteal saphenous vein bypass (SVB) in six years, 79% and 74% for below-knee femoropopliteal SBV and 63% and 34% for femoro-distal SVB in five years. 88% and 76% for above-knee femoropopliteal human umbilical vein (HUV) bypass in four years. 67% and 45% for femoro-distal HUV bypass in three years follow-up period individually. The immediate good symptomatic results of the vascular reconstruction was 88% encountered in isolated aortoiliac disease, 63% in combined aortoiliac and femoropopliteal disease, 70.4% in isolated femoropopliteal disease and only 26% in femorotibial-peroneal disease (FTP). No change symptoms was still higher (33%) in FTP than the other vascular reconstruction due to poor distal runoff in this series. The early postoperative mortality rate was 1.6%, the late mortality rate was 2.7%, the incidence of postoperative complication rate was 13.6%. The major lower limb amputation rate was low as 7% in our series.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Diagnostic value of glycosylated hemoglobin in intravascular hemolysis after cardiac surgery.

Glycosylated hemoglobin (GH), hemoglobin (Hb), hematocrit, LDH and serum bilirubin were measured pre-operatively, and 1-10 days and 11-42 d post-operatively in 42 patients undergoing cardiac surgery. Their mean age was 39.90 years, ranging from 4 to 68 yr. In the early post-operation days, Hb and hematocrit, but not GH percentage, were significantly decreased. This demonstrates that, at this stage, acute blood loss rather than hemolysis is more prominent. In the later post-operative days, GH, but not Hb or hematocrit, decreased significantly. This indicates the presence of chronic hemolysis with bone marrow compensation. In our study, the incidence of chronic mild hemolysis after cardiac surgery was very high (68.8%). We conclude that GH determination is a simple, easy and sensitive method to detect chronic hemolysis and we suggest measuring it in every case with suspicion of hemolysis.

Adolescent↗

PubMed1989

Role of acetylcholine in induction of repetitive activity in human atrial fibers.

The actions of acetylcholine and its interactions with epinephrine were studied in human atrial tissues by recording transmembrane potentials and contractile force. Acetylcholine (0.55-5.5 microM) reduced force, shortened the duration and shifted to more negative values the plateau of action potentials, abolished phase 4 depolarization, and suppressed the activity of spontaneous fibers. During the recovery, often there was a rebound increase in some parameters of the action potential and in force. Epinephrine (0.3-2.8 microM) induced oscillatory potentials and aftercontractions and acetylcholine abolished them. However, during the washout of acetylcholine in the presence of epinephrine, the oscillatory potentials and aftercontractions were larger than before acetylcholine, and repetitive activity was often induced. The inhibitory and excitatory effects of acetylcholine were mimicked by methacholine (5.1 microM) and abolished by atropine (1.5 microM). The postacetylcholine rebound was also potentiated by theophylline (0.6-2 mM) but was not blocked by propranolol (1-3.4 microM), prazosin (1 microM), and diltiazem (0.1 microM). It is concluded that in human atrial fibers acetylcholine has inhibitory as well as excitatory effects that are exaggerated in the presence of epinephrine and are mediated by the activation of the muscarinic receptor. The interaction between acetylcholine and epinephrine involves an antagonism at an intracellular level.

Acetylcholine↗

PubMed1989

Smoking among medical students in Hong Kong.

A survey was conducted among two classes of medical students (N = 293) at the University of Hong Kong to study their smoking habits and knowledge of and attitudes toward smoking. The response rate was 97.3%. There was only one daily smoker (0.4%) and 21 occasional smokers (7.4%). While the respondents regarded health and self-discipline as the main reasons for not smoking, the social taboo against smoking among young people might have also deterred this educated elite from smoking. Many of them failed to identify the major causal role of smoking in smoking related diseases. The potential of prevention in encountering a smoking patient seen for reasons unrelated to smoking was not fully realised. There was disagreement in the banning of cigarette advertising and in increasing the price of tobacco products. In the face of aggressive marketing by the tobacco industry in the Asia-Pacific region, every undergraduate medical curriculum should include organized instruction on smoking and its control.

Adult↗

PubMed1989

Suicide among Chinese schizophrenics in Hong Kong.

A descriptive study of suicides in 74 Chinese schizophrenic out-patients (43 male) is presented. The mean age at death was 31.3 years. The mean duration of illness was 8.5 years and 50 of the 74 died within ten years of onset of illness. Only five lived alone; 35 were openly employed and 20 were married at the time of death. Twenty had a history of depression, and 27 had attempted suicide previously. More females had been depressed or had attempted suicide than males. Over half were last admitted for reasons other than schizophrenic symptoms alone and ten died within one month of discharge. Eight of 71 patients followed up expressed suicidal ideas at the last psychiatric contact, but only 15 were symptomatic. Jumping was the commonest method used. Analytical studies are needed to identify risk factors in Chinese schizophrenics.

Adult↗

PubMed1989

Legionnaires' disease following cardiac transplantation.

One case of Legionnaires' disease in cardiac transplant recipient is reported. She was diagnosed by immunofluorescence study of bronchoscopic lavage specimen and was treated by oral erythromycin successfully. The main presentations are fever and single pulmonary nodule with rapid progression and cavitation. In the literatures report, two complicated Legionnaires' disease was reported in cardiac transplant recipient. This case is less complicated than reported and is the first case in this country.

Adult↗

PubMed1989

[A new operation for the management of gastric varix bleeding].

Gastric varices is a special oriental type manifestation of gastroesophageal collaterals in portal hypertension patients. It has gained more attention in recent years following the popularity of endoscopy and sclerotherapy. Catastrophic bleeding from ruptures of gastric varices is a life threatening emergency. Gastric varices are generally located at the greater curvature side of the cardiofundic region. Neither a Sengstaken-Blakemore balloon tube nor a Linton balloon tube can stop the bleeding. This area is also beyond the field of sclerotherapy. Surgery is the only definite therapy. Devascularization procedures as described by Dr. Hassab sometimes fail to control active bleeding and also fail to adequately decongest the whole varices area. The radical resection procedures such as terminal esophagectomy, proximal gastrectomy or cardiectomy as proposed by Japanese groups interrupts the normal esophgo-gastric continuity and is also too invasive for a cirrhotic patient. In between, besides terminal esophago-proximal gastric devascularization and splenectomy, we use a TA-90 stapler to perform an oblique cardiofundectomy to resect en bloc the tortuous gastric varices area. From Nov. 1983 to May 1988, at the Veterans General Hospital-Taipei, 16 patients received this new operation to manage gastric varices bleeding. Ten of them were on an emergency basis and 6 were elective surgery. Only one patient in the emergency group died. All catastrophic bleeding in the emergency group was dramatically controlled and all other patients recovered rapidly. With a follow-up range from 6 months to 4.5 year and an average of 19 months, there was no recurrent bleeding and no hepatic encephalopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Esophageal and Gastric Varices↗

PubMed1988