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Biomedical subjects

C H Chan

Publications and source records attributed to C H Chan.

At least 109 records · Page 6Linked to original sources
PubMed1993

Clinical and polygraphic characteristics of patients with respiratory dyskinesia.

Respiratory dyskinesia is characterized by irregularity in rate, rhythm and depth of breathing. This study reports on the clinical features of 11 patients with respiratory dyskinesia identified from a mental hospital in Hong Kong, together with the results of the 24-hour polygraphic recording of seven patients. Virtually all patients with respiratory dyskinesia had tardive dyskinesia. However, the condition was missed or misdiagnosed in all cases by the case psychiatrists. The respiratory irregularity persisted for most of the day and only disappeared when patients took a prolonged rest or fell asleep. A standardised clinical examination for respiratory dyskinesia is proposed.

Adult↗
PubMed1993

Serum concentration of soluble interleukin 2 receptors in asthma. Correlation with disease activity.

We evaluated whether serum soluble interleukin 2 receptor (sIL-2R), a marker of T lymphocyte activation in vivo, could be useful to monitor disease activity in asthma. Venous blood was collected from 26 patients with acute severe asthma prior to the commencement of systemic corticosteroid therapy (day 1), 15 with stable disease, and 13 normal control subjects. Serum sIL-2R level was significantly higher in acute asthma (462.7 +/- 36.1 U/ml; mean +/- SEM) than stable disease (328.5 +/- 30.4 U/ml, p = 0.013) which in turn, was significantly raised when compared with control subjects (239.0 +/- 22.9 U/ml; p = 0.0003 vs acute; p = 0.036 vs stable). Nevertheless, sIL-2R concentrations in 11 patients with acute and 11 with stable disease did not exceed the upper limit of normal, ie, mean +.2 SD of the value in control subjects = 404.4 U/ml. Repeated measurements of sIL-2R in 24 acute asthmatics on day 3 revealed no significant fall (464.6 +/- 37.2 U/ml, NS), although the reduction in sIL-2R was significantly correlated with the corresponding improvement in peak expiratory flow (r = -0.52, p = 0.005). Following resolution of the acute attack, further measurements performed in 11 of these subjects on day 28 showed a significant fall in sIL-2R (p = 0.016). Our data showed that although serum sIL-2R was raised in asthma and, to a certain extent, might reflect disease activity, the considerable overlap of values between asthma of differing severity and normal control subjects precludes its clinical use as an index of asthma severity.

Acute Disease↗
PubMed1993

Circulating adhesion molecules in tuberculosis.

Leucocyte-endothelial adhesion molecules have been implicated in the pathogenesis of inflammatory diseases. To evaluate their role as markers of disease activity in tuberculosis, we have used an antigen capture ELISA to measure the serum concentrations of circulating intercellular adhesion molecule-1 (cICAM-1), E-selectin (cE-selectin) and vascular cell adhesion molecule-1 (cVCAM-1) in 34 patients with active tuberculosis (27 with pulmonary disease and seven with lymph node disease) before the commencement of standard chemotherapy, 15 subjects who had previously completed treatment for pulmonary tuberculosis, and 27 healthy volunteers. Circulating ICAM-1 and E-selectin levels were significantly elevated in patients with active tuberculosis when compared to those with treated disease (P < or = 0.01), and healthy controls (P < 0.02). Circulating VCAM-1 was raised in patients with active or old pulmonary tuberculosis (P < 0.02 versus healthy controls) but not in those with tuberculous lymphadenitis. Significant correlations were observed between the levels of cICAM-1 and cE-selectin (p = 0.63, P = 0.0001), and between cICAM-1 and cVCAM-1 (p = 0.28, P = 0.016). Taking the mean +2 s.d. of the serum level in healthy controls as the upper limit of normal range, circulating ICAM-1 had the best discriminative power in identifying active tuberculosis, being elevated in about 80% of patients but was raised in only 6.7% of subjects with treated disease and in 3.7% of normal subjects. Our data support the possibility that three adhesion molecules may be involved in the pathogenesis of tuberculosis and cICAM-1 may be a useful marker of disease activity.

Adolescent↗
PubMed1993

The effects of inhaled corticosteroids on chronic airflow limitation.

A placebo-controlled, double blind, cross-over study of inhaled budesonide was carried out to examine its effectiveness in the treatment of chronic airflow limitation (CAL). Fourteen patients (11 males, mean age 66 years) with stable CAL received placebo treatment for four weeks followed by inhaled budesonide 400 micrograms BD for eight weeks. Response was assessed by measuring forced expiratory volume in one second (FEV1). There was no significant improvement in the overall spirometric measurements and symptom scores except a reduction in daily peak expiratory flow rate fluctuation (p < 0.05). However, individual patients showed significant increase in FEV1. Two patients (14%) had greater than 30% increase in FEV1 in response to inhaled corticosteroids. This response could not be predicted from history of allergy, skin test, bronchial challenge test, peripheral blood or sputum eosinophilia. We conclude that only a minority of patients with stable CAL may respond to inhaled budesonide. Nonetheless, patients who are symptomatic despite treatment with maximum doses of bronchodilators may have a trial of inhaled corticosteroids in order to demonstrate any additional benefit.

Administration, Inhalation↗
PubMed1992

Clinical manifestations of taeniasis in Taiwan aborigines.

From 1974 to 1989, a total of 24,500 aborigines at 67 villages in ten mountainous districts/towns in Taiwan were examined for the Taiwan Taenia infection and 12% were found to be infected. In order to define the clinical manifestations of taeniasis caused by the Taiwan Taenia, 1661 aborigines in ten mountainous districts were surveyed. The overall clinical rate was 76%. The clinical rate was highest among Atayal aborigines (81%), followed by Bunun (66%) and Yami (61%) aborgines and lowest among Ami aborigines (40%). Among 1153 infected people, 10% had passed gravid segments in the faeces for less than 1 year, 24% for 1-3 years, 17% for 4-5 years, 23% for 6-10 years, 16% for 11-20 years, 7% for 21-30 years, and 3% over 30 years. Twenty-six occurrences of gastrointestinal and neurological symptoms were reported by 1258 infected persons. Passing proglottides in the faeces (95%) was the most frequent sign, followed by pruritus ani (77%), nausea (46%), abdominal pain (45%), dizziness (42%), increased appetite (30%), headache (26%), etc.

Animals↗
PubMed1992

Characterization of cytokine gene expression in CD4+ and CD8+ T cells after activation with phorbol myristate acetate and phytohaemagglutinin.

Cytokines are important mediators involved in the development of effector cells and in the regulation of immune responses. The gene expression of these mediators in T cell subset has yet to be fully elucidated. Using sensitive reverse transcription-polymerase chain reaction (RT-PCR), the kinetics of cytokine gene expression in human CD4+ and CD8+ T cells were examined. CD4+ T cells were more readily activated by phorbol myristate acetate (PMA) and phytohaemagglutinin (PHA) than CD8+ T cells in terms of the IL-2 receptor (IL-2R) mRNA expression. Quantitative differences in cytokine gene expression between CD4+ and CD8+ T cells were confirmed and higher levels of cytokine mRNAs were induced in CD4+ than in CD8+ T cells. Early induction of IL-2 mRNA was observed in both T cell subsets. The demonstration of different kinetics of cytokine gene expression illustrates one of the examples of the complexity of immunoregulation. The differential response of cytokine gene expression in different T cell subsets should be taken into consideration when clinical studies in cytokine production by peripheral blood mononuclear cells are interpreted.

Base Sequence↗
PubMed1992

Mycobacteria as a cause of infective exacerbation in bronchiectasis.

In 91 patients with bronchiectasis seen over 6 years, a positive mycobacterial culture was obtained in 12 cases (13%). The organisms isolated were Mycobacterium tuberculosis in nine cases, Mycobacterium avium in two cases and Mycobacterium tuberculosis and chelonei were obtained on separate occasions in one case. Computed tomography and/or bronchography showed that the bronchiectatic changes commonly involved the lower lobes and to a lesser extent, the middle and lingula lobes. In none of these 12 cases was tuberculosis strongly suspected on clinical or radiological grounds. We conclude that mycobacterial infections are common in patients with bronchiectasis and sputum should be cultured for mycobacteria periodically in these patients. In doubtful cases, bronchoscopy may be helpful to obtain a positive mycobacterial culture.

Adult↗
PubMed1992

A prospective study of community-acquired pneumonia in Hong Kong.

A prospective study of community-acquired pneumonia in Hong Kong was carried out between January and December, 1988. Ninety adults (57 male) with a mean age of 57.3 years were admitted to the Prince of Wales Hospital with community-acquired pneumonia. The etiologic diagnosis of pneumonia was made in 37 cases (41 percent). Pneumococcal infection was diagnosed in 11 patients (12 percent). The same number of patients had pulmonary tuberculosis presenting as acute pneumonia. It could not be differentiated from other causes of pneumonia on clinical and radiologic grounds, although pleural effusion and upper lobe involvement were more common in patients with tuberculosis. Chlamydia species were identified in five patients (6 percent) and Mycoplasma pneumoniae was identified in three patients (3 percent). There was no case of Legionnaires' disease. The etiologic agent could not be identified in 59 percent of cases. The low incidence of etiologic diagnosis of community-acquired pneumonia was probably related to the widespread use of antibiotics in private practice. Tuberculosis is an important cause of community-acquired pneumonia in Hong Kong and this diagnosis should be considered in patients who fail to respond to first-line antibiotics.

Adult↗
PubMed1992

Hypercalcemia in active pulmonary tuberculosis and its occurrence in relation to the radiographic extent of disease.

The prevalence of hypercalcemia in tuberculosis in Hong Kong and its occurrence in relation to the radiographic extent of disease were studied in 57 patients with sputum smear (n = 44) and/or culture positive (n = 13) pulmonary tuberculosis and in five patients with military tuberculosis prior to treatment. Only one (1.6%) patient had a corrected plasma calcium level above the reference range for our laboratory. There was a positive relationship between the corrected plasma calcium levels and the radiographic extent of disease (r = 0.37), p < 0.01). As the occurrence of hypercalcemia in tuberculosis is known to be influenced by the calcium intake, our finding of a low prevalence of "absolute" hypercalcemia in Hong Kong could be related to the low dietary calcium intake in these subjects.

Adult↗
PubMed1992

Bronchoscopy and tuberculostearic acid assay in the diagnosis of sputum smear-negative pulmonary tuberculosis: a prospective study with the addition of transbronchial biopsy.

A prospective study of the efficacy of bronchoscopy and tuberculostearic acid assay in the diagnosis of sputum smear-negative pulmonary tuberculosis (TB) was carried out in 39 patients with symptoms and radiographic changes suggestive of active pulmonary TB. The diagnosis of TB was confirmed in 15 patients, probable TB was diagnosed in eight and 16 patients did not have TB. An early diagnosis of TB was made by bronchoscopy in six patients (40 per cent). Culture of sputum obtained before bronchoscopy was positive in nine patients (60 per cent) while combined with bronchoscopy specimens, a positive mycobacterial culture was obtained in 12 patients (80 per cent). Mycobacteria were cultured from transbronchial biopsy specimens from five patients (33 per cent) but none of these was exclusively positive. Histological examination of transbronchial biopsy tissue was diagnostic of TB in four patients and it was the exclusive means of early diagnosis in two. Transbronchial biopsy also provided an alternative diagnosis in four other patients. Tuberculostearic acid assay had a sensitivity of 0.40 in bronchial aspirate, 0.80 in bronchoalveolar lavage fluid, and 0.27 in transbronchial biopsy specimens: the combined result was 0.87. In nine patients with pulmonary TB in whom an early diagnosis could not be made, the tuberculostearic acid assay was positive in seven (78 per cent). We conclude that bronchoscopy with bronchoalveolar lavage and transbronchial biopsy is helpful in providing early diagnosis and positive culture results. Assay of tuberculostearic acid in bronchoalveolar lavage fluid is a useful adjunct to early diagnosis. However, mycobacterial culture and assay of tuberculostearic acid in transbronchial biopsy specimens have little diagnostic value.

Adolescent↗
PubMed1992

Hydrazine--a possible cause of isoniazid--induced hepatic necrosis.

Pharmacokinetic parameters of isoniazid, hydrazine (a metabolite of isoniazid), rifampicin and pyrazinamide in a 74-year-old man with pulmonary tuberculosis who died of submassive hepatic necrosis eight days after starting antituberculosis therapy were compared with those of other elderly patients who did not develop hepatotoxicity. Steady-state plasma hydrazine and rifampicin concentrations in this patient exceeded twice the mean +/- 2 SD value for the group of patients without hepatotoxicity, while concentrations for isoniazid and pyrazinamide were comparable. The findings suggest that HYD may have a role in isoniazid-induced hepatic necrosis.

Age Factors↗
PubMed1991

[Involvement of the central nervous system in disseminated tuberculosis].

Four weeks after starting tuberculostatic treatment (with isoniazid, rifampicin, streptomycin and pyrazinamide) a 21-year-old man with pulmonary tuberculosis developed symptoms of a radiculomyelopathy as well as mild renal failure. After isoniazid and streptomycin had been discontinued and ethambutol and high doses of vitamin B6 had been added all signs and symptoms improved. However, 4 weeks later tuberculous meningitis occurred which at first seemed to respond to administration of 5 antituberculosis drugs and dexamethasone. But 3 weeks later the patient sustained a partial hemiparesis. Its cause was proven to be a tuberculoma in the region of the brainstem. During further administration of tuberculostatic drugs and glucocorticoids the symptoms gradually receded over 8 months. A 54-year-old man with pulmonary tuberculosis developed cranial nerve pareses and symptoms of cerebellar involvement (trunk ataxia, intention tremor, dysdiadochokinesia) 3 weeks after starting tuberculostatic treatment. Computed tomography revealed multiple intracerebral tuberculomas which gradually shrank with continuation of the tuberculostatic treatment plus glucocorticoids. These two case reports illustrate that in tuberculosis involvement of the CNS can express itself clinically through complex symptoms, sometimes even after the start of tuberculostatic treatment.

Adrenal Cortex Hormones↗
PubMed1991

A selective biotinylated probe for V1a vasopressin receptors.

We have designed and synthesized a biotinylated vasopressin antagonist which is a selective probe for studying the V1a subtype of vasopressin receptor. Initially we synthesized the novel vasopressin analogue d(CH2)5Tyr(Me)2LysNH2(9)AVP (ALVP). Biotinamidocaproate was subsequently coupled to the epsilon-amino group of ALVP to generate the novel biotinylated probe d(CH2)5Tyr(Me)2Lys(N epsilon-biotinamido-caproate)NH2(9)AVP (ALBtnVP). Pharmacological characterization of ALVP and ALBtnVP established that both ligands were high affinity antagonists at V1a receptors, and that both displayed marked V1a/V2 selectivity. The observation that receptor-bound ALBtnVP was bi-functional, and thereby able to bind conjugated derivatives of avidin or streptavidin, allowed ALBtnVP to be utilized as a selective probe for V1a receptors. This strategy allowed the visualization of V1a receptors on the surface of WRK-1 cells and hippocampal neurons, by using streptavidin-gold with electron microscopy and fluorescein-avidin with light microscopy. We conclude that ALBtnVP is a useful probe for V1a receptors.

Amino Acid Sequence↗
PubMed1991

Peptic ulcer disease. How to treat it now.

Options for treatment of peptic ulcer disease are becoming more diverse. Most new agents are effective yet offer no real advantage over more traditional therapy. However, omeprazole (Prilosec) may be of benefit owing to its potent inhibition of acid secretion, but it is not yet approved for this purpose. Whether treatment of Helicobacter pylori infection will prove beneficial is not yet known, but the answer should be forthcoming. Finally, as with any disease process, alleviation of risk factors is always important. Appropriate counseling regarding use of nonsteroidal anti-inflammatory drugs and cigarette smoking is a necessity.

Anti-Ulcer Agents↗