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Biomedical subjects

C K Wong

Publications and source records attributed to C K Wong.

At least 19 recordsLinked to original sources
PubMed1992

In vivo production of tumor necrosis factor for the treatment of mice bearing Ehrlich ascites tumor.

Tumor necrosis factor (TNF) was produced in mice bearing Ehrlich ascites tumor (EAT) by priming with zymosan and subsequently challenging with lipopolysaccharide. The optimal conditions for the in vivo production of TNF in treating EAT bearing mice were established. The endotoxin shock induced in mice during TNF production could be minimized by the combined administration of sulindac and mannoheptulose. The endogenous TNF produced could suppress proliferation of EAT cells as well as prolong the survival time of mice bearing small tumors.

Animals↗
PubMed1992

A randomized double-blind crossover study comparing the efficacy and tolerability of flecainide and quinidine in the control of patients with symptomatic paroxysmal atrial fibrillation.

Patients with paroxysmal atrial fibrillation (PAF) are prone to recurrence. We compared the efficacy and tolerability of flecainide acetate in the control of PAF by means of conventional treatment with quinidine in 19 patients without structural heart disease. A randomized, placebo-controlled, crossover protocol consisting of 8 weeks of treatment with either agent was used. The recurrence of PAF was documented in a symptom diary and confirmed by event ECG recording. Complete control of symptoms was achieved in 4 of 19 and 2 of 11 of patients with flecainide and quinidine, respectively. Both agents prolonged the time to the first recurrence and significantly reduced the total duration of PAF recurrence by 40% and 47%, respectively (p less than 0.05 compared with placebo). Compared with quinidine, flecainide significantly reduced the frequency of recurrence and the rate of PAF during a recurrent episode. However, treatment with flecainide was associated with a higher incidence of symptomatic sinus pauses and visual disturbances compared with a higher incidence of gastrointestinal side effects with quinidine. During a follow-up period of 32 months, satisfactory control was achieved in 74% of patients with the use of these two antiarrhythmic agents.

Adult↗
PubMed1992

Mitogenic and tumor necrosis factor producing activities of Pseudostellaria heterophylla.

Separation of mitogenic fraction (PH-I) from Pseudostellaria heterophylla and characterization of its biological activities were investigated. PH-I was isolated as an alcohol-insoluble fraction from the hot water extract obtained by heating the roots of P. heterophylla in water at 80 degrees C for 4 h. It is a water-soluble substance consisting of mainly carbohydrates (56.8%) and a small amount of proteins (7.6%). The incorporation of tritiated thymidine into the DNA of murine spleen lymphocytes could be stimulated by PH-I in a dose-dependent manner. PH-I could act as a priming agent for the release of tumor necrosis factor (TNF) in mice. Moreover, PH-I exhibited potent anti-tumor activities against Ehrlich ascites tumor (EAT) cells in vivo but not in vitro.

Animals↗
PubMed1992

Ventricular rate-adaptive pacing in the elderly.

The role of ventricular rate-adaptive pacing (VVIR) in the elderly was investigated in 12 patients with a mean age of 85 +/- 2 years (range 75-95 years) with implanted activity-initiated VVIR pacemakers. Although four patients had significant extracardiac diseases, all were capable of independent walking and self care. The pacing rate achieved during structured daily activities (walking, climbing stairs, washing, bed-making and scrubbing floors) were compared with those achieved by 10 age-matched healthy subjects. Apart from the more strenuous activities (ascending stairs and floor-scrubbing), the pacing rates achieved by the patients were comparable to those of the healthy subjects and occurred within an appropriate time. In a 4-weekly randomized, double-blind crossover protocol in the VVI and VVIR pacing modes, all patients underwent assessments in a 12-min walking distance test, a 24 h non-invasive ambulatory blood pressure recording and a symptomatic documentation. During VVIR pacing, the 12-min walking distance was significantly improved compared to VVI pacing (556 +/- 52 vs. 545 +/- 55 m, P less than 0.05). There was no difference between the recorded blood pressure and symptom scores between the two pacing modes, although most patients preferred VVIR pacing (P less than 0.05). It is concluded that VVIR pacing in this elderly population can improve exercise capacity, and the patients' preference for the VVIR mode was documented despite the absence of a measurable difference in symptomatology.

Aged↗
PubMed1992

Disparate efficacy of tobramycin on Ca(2+)-, Mg(2+)-, and HEPES-treated Pseudomonas aeruginosa biofilms.

Mucoid exopolysaccharide (MEP) obtained from Pseudomonas aeruginosa 579 was suspended in 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) pH 7.2 containing 0.1-10.0 mM of CaCl2.2H2O or MgCl2.4H2O. MEP treated with HEPES or < 5.0 mM of the Ca2+ or Mg2+ salts remained soluble and bound tobramycin in an equilibrium dialysis bioassay. MEP treated with 5.0 or 10.0 mM of the Ca2+ or Mg2+ salts did not bind tobramycin. Five and 10 mM Ca(2+)-treated MEP precipitated but Mg(2+)-treated MEP did not. Pseudomonas aeruginosa 579 biofilms formed using a defined growth medium having < 1 mM Ca2+ or Mg2+ were treated for 1 h with 10 mM HEPES +/- 5.0 mM CaCl2.2H2O or MgCl2.4H2O, prior to an 8-h exposure to HEPES, or the defined growth medium, +/- 125 micrograms/mL of tobramycin. The tobramycin kill kinetics for the HEPES-, Mg(2+)-, and Ca(2+)-treated biofilms were similar and gradual from T = 0-6 h. The viability of the HEPES- and Mg(2+)-treated populations declined sharply (from 6 to 8 h). Bacteria dispersed from the MEP in control biofilms at 0 and 8 h did not grow in the presence of 7.81 micrograms/mL of tobramycin. Thus, binding of tobramycin of P. aeruginosa 579 MEP may not be as influential to the impediment of tobramycin diffusion as is the steric hindrance imposed by the Ca2+ condensation of the polymer.

Binding Sites↗
PubMed1992

Hypocalcemia and myocardial function in uremia.

To investigate whether hypocalcemia affects cardiac performance in uremic patients, we studied the hemodynamic changes with short- and long-term correction of hypocalcemia in 4 uremic patients on dialysis using continuous wave Doppler study. At rest, 1 h of intravenous calcium infusion increased calcium level from 1.74 +/- 0.17 to 1.92 +/- 0.16 mmol/l (p less than 0.05). Cardiac output represented by minute distance increased from 10.5 +/- 2.0 to 12.1 +/- 2.5 m (p less than 0.05), but heart rate and blood pressure were unchanged. The peak velocity and acceleration of ascending aortic blood flow increased during calcium infusion. With long-term replacement, calcium level increased from 1.74 +/- 0.17 to 1.94 +/- 0.15 mmol/l (p less than 0.05), but resting hemodynamics were unchanged. On exercise testing, exercise duration increased from 10.6 +/- 1.6 min to 12.9 +/- 1.5 min (p less than 0.01), but hemodynamic parameters at peak exercise were similar. We conclude that acute calcium replacement enhanced cardiac contractility in uremic patients, but cardiac performance at rest and peak exercise was not improved with long-term therapy. This reflects different cardiac responses to acute versus chronic calcium replacement.

Adult↗
PubMed1992

Idiopathic hypercalciuria causing osteoporosis and hypocalcemia.

Idiopathic hypercalciuria, though a common cause of nephrolithiasis, has not been recognized to cause hypocalcemia and severe bone disease. We describe an adolescent with idiopathic hypercalciuria who presented initially with severe hypocalcemia and osteoporosis and this was later complicated by recurrent renal calculi formation after calcium and vitamin D supplement. After treatment with thiazide, hypercalciuria was controlled and serum biochemistry normalized. While idiopathic renal hypercalciuria may cause a negative calcium balance in adults, a variant of this syndrome with severe renal calcium leak occurring in a growing subject could lead to severe hypocalcemia and osteoporosis.

Adolescent↗
PubMed1992

Tripe palms: a significant cutaneous sign of internal malignancy.

Tripe palms is a paraneoplastic keratotic skin sign of great predictive value. It is characterized clinically by a curious rugose thickening of the palms with an accentuation of the normal dermatoglyphic ridges and sulci. Histological examination reveals an undulant epidermis with hyperkeratosis, acanthosis and papillomatosis. More than 80 cases have been reported in the literature; 90% of them were associated with an internal malignancy, mostly a carcinoma of the lung or stomach. We herein report a 66-year-old Chinese man with adenocarcinoma of the lung who presented typical tripe palms. Recognition of this distinctive pattern should prompt a meticulous search for an underlying malignancy, particularly lung or gastric carcinoma.

Adenocarcinoma↗
PubMed1992

Psychiatric morbidity in a Chinese primary school in Hong Kong.

The psychiatric morbidity among 718 Chinese primary school children from a lower middle social class area in Hong Kong was studied, using a two-stage design. The screening procedures included two parts, a multi-component scale and a battery of probing questions. The screening procedures achieved an overall sensitivity of 75% and a specificity of 97%. The findings on prevalence were: (i) a total prevalence of all definite psychiatric cases of 16.3%; (ii) prevalence according to diagnostic categories: emotional disorder, 8.8%; conduct disorder, 2.0%; mixed disturbance of emotion and conduct, 3.0%; hyperkinetic syndrome, 1.0%; hyperkinetic conduct disorder, 1.0%; and Gilles de la Tourette's syndrome, 0.4%; (iii) boys 2.7 times more affected than girls; (iv) emotional disorder much more common than conduct disorder, even in boys; and (v) the prevalence of borderline cases was 19.5%. The mean duration of morbidity for all definite cases was 41.7 months. About half of all definite cases were seriously impaired in one or more areas of functioning and the other half moderately impaired. These results were compared with findings obtained from studies done in other countries.

Affective Symptoms↗
PubMed1992

[Leukemia cutis: clinical and histopathological analysis of 14 cases].

We report 14 cases of leukemia cutis registered at Department of Dermatology, Veterans General Hospital Over a period of 18 years. There were one patient with acute lymphocytic leukemia (ALL), one with chronic lymphocytic leukemia (CLL), seven with acute monocytic leukemia (AMOL), one with acute myelomonocytic leukemia (AMML), and four with chronic myelocytic leukemia (CML). Multiple papules and nodules were the most frequent clinical lesions. Metastatic skin lesions occurred most commonly on legs (71%), followed by arms (64%), back (50%), anterior chest (50%), scalp (14%), and face (14%). The feet (7%) were rarely involved while palms and soles were rarely involved. Cutaneous leukemic lesions may be concomitant with or after, but never before the diagnosis of systemic leukemia in our series has had such change. In general, the histopathology of leukemia cutis showed diffuse or nodular infiltration of leukemic cells in the dermis and subcutaneous tissue, often typing of leukemia relays on more confirmative studies of peripheral smear and bone marrow biopsy. Leukemia cutis seems to be dissemination of systemic leukemia to the skin, and the presence of cutaneous leukemic lesions are associated with a very poor prognosis. Most patients (85%) died within 4 months after appearance of skin metastasis.

Adolescent↗
PubMed1992

Hepatitis B virus infection among aboriginal children in eastern Taiwan.

Hepatitis B virus (HBV) infection is endemic in Taiwan, with 15-20% of the adult population carrying the surface antigen (HBsAg). Hualien in Eastern Taiwan is relatively isolated from other parts of the island by the Central Mountains. The status of HBV infection among mountain aborigines in Hualien has not been studied on a large scale before. A survey of serum HBsAg and its antibody (anti-HBs) was conducted in 1989. A total of 3,287 children from 27 primary schools in three mountainous counties of Hualien were tested. The carrier rate (HBsAg positive) for the whole group was 31.9%, and the infection rate (HBsAg and/or anti-HBs positive) was 80.7%. Both the carrier rate and infection rate of 1,618 boys were significantly higher than those of 1,669 girls (35.7% vs 28.3% and 83.0% vs 79.3%, respectively, p < 0.001). The carrier rates of children in the first to sixth grades were 29.4%, 35.0%, 31.5%, 30.8%, 33.3% and 32.0%, and the infection rates were 74.9%, 79.0%, 80.1%, 82.6%, 83.3% and 84.1%, respectively. The infection rate increased significantly with age (p < 0.05). The results show that HBV infection is a serious problem among the children of mountain aborigines in Hualien, with nearly one-third of them carrying HBsAg. Aggressive vaccination, as well as public health education programs, are greatly needed.

Carrier State↗
PubMed1991

Improvement of exercise capacity after nifedipine in patients with Eisenmenger syndrome complicating ventricular septal defect.

We investigated the potential benefit of a preferential pulmonary vasodilatory effect of nifedipine in 4 patients with Eisenmenger syndrome complicating ventricular septal defect. First-pass radionuclide scan was performed at rest to measure intracardiac shunting before and after nifedipine. Two hours after 20 mg sublingual nifedipine, right-to-left shunt increased from 16.3 +/- 1.4 to 20.4 +/- 1.5% (p less than 0.05), but systemic arterial oxygen saturation (SAO2) remained steady. With 4 weeks of maintenance nifedipine therapy, resting intracardiac shunting and SAO2 were unchanged from baseline. Symptom-limited cycle ergometry was performed before and after maintenance nifedipine with placebo control. Exercise duration was prolonged (8.7 +/- 0.6 vs. 6.8 +/- 0.9 min; p less than 0.02) and SAO2 at each stage of exercise was consistently increased in all patients after nifedipine. Cardiac output and the SAO2 at peak exercise were similar. Thus, chronic nifedipine therapy increases SAO2 on exercise and improves maximal exercise capacity in patients with Eisenmenger syndrome, which is not predicted by study of resting intracardiac shunting after acute therapy.

Administration, Oral↗
PubMed1991

Cerebral haemorrhage in anticoagulated patients with non-septic mechanical valvular prosthesis.

Cerebral haemorrhage in anticoagulated patients with mechanical valvular prosthesis poses an uncommon but difficult management problem. Four such patients are presented: one patient had delayed haemorrhagic transformation of a preexisting cerebral infarct, one probably had de novo haemorrhage complicating hypertension and in two patients cerebral haemorrhage was associated with excessive anticoagulation. Conservative management including the use of fresh frozen plasma, delayed heparinisation and warfarinisation was used. Both patients with anticoagulant overdose died as a result of extensive haemorrhage despite the drainage of cerebellar haematoma in one patient. The remaining two patients survived with minimal neurological deficits. Diagnosis of the underlying cause of cerebral haemorrhage, and the timing of heparinisation and anticoagulation are discussed.

Adult↗
PubMed1991

Dyschromatosis universalis with X-linked ocular albinism.

A 10-year-old Chinese boy with the characteristic skin manifestations of dyschromatosis universalis is described. In addition, the patient had congenital nystagmus with poor visual acuity, and ophthalmological examination revealed foveal hypoplasia and albino-like fundi. Histopathology showed giant pigment granules in the skin. Based upon the finding of giant pigment granules in clinically normal skin of the patient's mother, the patient was diagnosed as a case of dyschromatosis universalis with X-linked ocular albinism. To the best of our knowledge, this is the first documented case of this combination.

Albinism, Ocular↗