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Biomedical subjects

R C Chan

Publications and source records attributed to R C Chan.

At least 19 recordsLinked to original sources
PubMed1992

Epidemiology and aetiology of acute bronchiolitis in Hong Kong infants.

The epidemiological, clinical and virological features of 1220 children with acute bronchiolitis admitted to the Prince of Wales Hospital, Hong Kong, from 1985 to 1988 are reported. They accounted for 6.6% of total paediatric admissions and provided a case incidence of bronchiolitis requiring admission to hospital of approximately 21 per 1000 children 0-24 months of age. The clinical course and outcome was in general benign. The average hospital stay was 5 days and there were no deaths. Ten per cent of patients were repeatedly admitted to hospital with recurrent wheezing after discharge. Two infants developed bronchiolitis obliterans. Respiratory syncytial virus (RSV) was shown by direct immunofluorescence, virus culture and serology to be the commonest cause of acute bronchiolitis in Hong Kong. Other aetiological agents included parainfluenza and influenza viruses, adenoviruses, and Mycoplasma pneumoniae. In contrast to western countries, a seasonal variation of bronchiolitis was found with a peak incidence in the summer months. The significance of these observations is discussed.

Acute Disease↗
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

Motor unit potential analysis under submaximal contraction: ADEMG study in normal and radiculopathy subjects.

The purpose of this study was to investigate the motor unit potential (MUP) morphology in different degrees of muscle contraction. Fourteen normal volunteers and 8 patients with C7 radiculopathy were included. The extensor digitorum communis muscle was kept in minimal contraction and 5%, 10%, 30% and 50% of maximal contraction under the guidance of strain gauge. Automatic motor unit potential analysis was done by automatic decomposition electromyography for each epoch of muscle contraction in both normal and radiculopathic groups. The results revealed that as muscle contraction increased, the observed MUPs had higher amplitude, rising ratio and firing rate, while the duration became shorter, but no regular change was found in turns reading. These tendencies were found in both normal and radiculopathic groups. This study enhanced the understanding of morphology of MUPs with higher threshold, and proved the usefulness of ADEMG in differentiating normal from cervical chronic radiculopathy condition. It is suggested that the examiner should observe both lower and higher threshold MUPs during clinical needle examination to make diagnosis more accurately.

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

Common bile duct stones: a cause of chronic salmonellosis.

A chronic carrier state of Salmonella spp is present in 0.15% of the population, and is believed to be related to the presence of a diseased gallbladder. We present a patient with common bile duct (CBD) stones, whose bile cultures repeatedly indicated Salmonella typhi, despite an adequate course of antibiotic treatment. The carrier state was abolished after removal of the CBD stones 4 months later. The chronic carrier state may be related to biofilm formation on the surface of the CBD stones. The removal of the biliary stones, which are the most likely reservoir for Salmonella spp, may be a crucial step in eradication of the carrier state.

Aged↗
PubMed1991

Quantitative comparison of motor unit potential parameters between monopolar and concentric needles.

This study quantitatively compared the simultaneous recording of the "same" motor unit potentials recorded by closely positioned concentric and monopolar needles. The motor unit potentials from the anterior tibialis of 12 young subjects were analyzed independently by both needles being connected to 2 sets of EMG-computer combinations. Recordings of the same motor unit potentials were confirmed by triggering and averaging of the 2 sets of motor unit potentials with identical firing patterns on both EMG screens. Automatic analysis disclosed the monopolar recordings had a significantly higher mean amplitude (2.05 times), larger surface area (2.64 times), and longer duration (1.86 times) than the concentric recordings, while the mean number of phases (1.58 times) and turns (1.35 times) revealed no statistical differences. Both active recording and reference electrodes contributed to these differences.

Action Potentials↗
PubMed1991

A new approach to the management of patients at risk of ovarian hyperstimulation in an in-vitro fertilization programme.

In this study, we report an alternative method of management of patients at a potential risk of ovarian hyperstimulation syndrome (OHSS) in an in-vitro fertilization (IVF) programme, by the use of gonadotrophin releasing hormone analogue (GnRHa). Thirty eight women considered at risk of this syndrome, having serum oestradiol greater than 4000 pg/ml following ovarian stimulation, received a GnRHa nasal spray for induction of the preovulatory endogenous luteinizing hormone surge for follicular maturation prior to oocyte recovery. Oocyte recovery (mean oocytes per cycle 18.60 +/- 4.79; range 15-35) and IVF were successfully completed in 27 cycles. Twenty six women had embryos replaced and 11 pregnancies occurred (28.9% per operation, 42.3% per replacement cycle). None of the patients developed OHSS. Where there is a risk of OHSS, the use of GnRHa to induce the preovulatory surge of endogenous luteinizing hormone for final follicular maturation provides a successful and more economical alternative to cancellation of cycles.

Adult↗
PubMed1991

[Median nerve lesions at wrist in cyclists].

The purpose of this study is to detect the median nerve lesions at wrist in professional cyclists. Totally 14 national representative cyclists were included. Each subject was questionnaired and asked to draw their site of hand discomfort, followed by hand grip power test with grasp, lateral pinch and palmar pinch. A control group of 30 medical students were also tested for grip power. Electrodiagnostic examination of bilateral median nerves was then done on every cyclist, including motor and sensory nerve conduction studies, and needle EMG on abductor pollicis brevis and other associated muscles. Of the 28 hands in 14 cyclists, 7 in 4 subjects had neurologic symptoms related to median nerve, and 5 in 4 subjects had abnormal electrodiagnostic examinations. The grip power was significantly better in cyclists than in control. The prevalence of median nerve lesions at wrist in cyclists, although usually mild, was substantially higher than expected. Electrodiagnosis can be used as a sensitive detector for neuropathy even at subclinical stage. It is suggested that cyclists and trainers should be aware of the median nerve lesion during cycling and training in order to take early preventive, diagnostic and therapeutic procedures.

Adolescent↗
PubMed1991

[Electrodiagnostic evaluation of conservative treatment in carpal tunnel syndrome].

The incidence of carpal tunnel syndrome ranks first by far among all entrapment neuropathies. Many foreign studies have been reported over the years concerning the diagnosis of carpal tunnel syndrome, but very few about its treatment effects. Moreover, data have been based on the patients' subjective reports of their symptoms. Our data, however, are wholly derived from objective electromyographic examination. Five treatment approaches were compared for patients suffering from carpal tunnel syndrome in this study. Ninety-nine hands of 61 patients were divided into five treatment groups vitamins B6 & B12, steroid injection, hand splint, splint combined with vitamins, and splint combined with injection. Each patient was evaluated with electrodiagnostic study before the treatment, and 1 and 2 months after the treatment. Treatment with hand splinting, local injection at wrist, and combined therapies were all superior in effect to vitamins B6 & B12 alone in sensory nerve conduction study. The effects of treatment appeared faster in the groups with local injection and local injection combined with hand splinting in the sensory and motor nerve conduction studies. The results of this study suggest that treatment with vitamins B6 & B12 alone does not suit carpal tunnel syndrome well and that hand splint combined with steroid injection is the better conservative treatment.

Adult↗
PubMed1990

The effect of obstruction on the biliary excretion of cefoperazone and ceftazidime.

The biliary excretion of cefoperazone and ceftazidime was studied by endoscopic cannulation of the common bile duct, in patients with complete biliary obstruction and in an unobstructed control group. Patients were given each drug prophylactically for 24 h before endoscopy and as a single dose at the time of cannulation. In unobstructed patients biliary excretion of ceftazidime was passive. At the time of cannulation bile contained 10% of the peak serum concentration, rising to 20% 90 min later. Cefoperazone excretion was active. At cannulation biliary concentrations were 200% of the serum peak, 900% at 60 min and 700% at 90 min. In obstructed patients, bile sampled immediately at decompression contained neither antibiotic. Passive excretion of both drugs occurred rapidly after relief of obstruction and biliary concentrations were 20% of maximum serum levels at 60 min. Twenty-four hours later passive excretion had further improved, but the active excretion mechanism of cefoperazone had still not recovered. We conclude that obstruction impairs active as well as passive biliary excretion of antibiotics, that drainage is essential for the control of sepsis in obstructed cholangitis, and that both cefoperazone and ceftazidime achieve similar and therapeutic concentrations in bile during the 24 h after decompression.

Adult↗
PubMed1989

RNA-electrophoresis as a typing method for nosocomial rotavirus infection in a special-care baby unit.

During January and February 1988 an outbreak of nosocomial rotavirus infection occurred in a special-care baby unit (SCBU). Seven infants were affected, of whom five had symptoms of diarrhoea. Typing by RNA electrophoresis (electropherotyping) demonstrated that a single rotavirus strain was responsible for the outbreak. The epidemic electropherotype was introduced by an infant with diarrhoea admitted directly into the SCBU from the community. Eight other electropherotypes were identified during January and February in patients with community-acquired rotavirus diarrhoea on other paediatric wards, but the outbreak strain occurred only on the SCBU. Electropherotyping is a useful and rapid method for tracing the epidemiology of hospital-acquired rotavirus infection.

Communicable Disease Control↗
PubMed1989

Prevalence of cytomegalovirus cervical excretion in pregnant women in Hong Kong.

In 1986 a study was made on the prevalence of cervical colonization by cytomegalovirus (CMV) in normal third trimester pregnant Chinese women in Hong Kong. Seven out of 95 unselected subjects had positive CMV culture, making a prevalence of 7.4%. This is a low prevalence when compared with the prevalence found in other people of Asian origin and similar to the prevalence found in the Caucasians.

Cervix Uteri↗
PubMed1989

[Surface area--a new parameter for CMAP reading].

The purpose of this study is to determine a data range of the surface area of compound muscle action potential (CMAP) in normal abductor pollicis brevis and abductor digiti minimi. 256 median nerves and 317 ulnar nerves which were proved to be normal by NCV and EMG studies were included. Computer-aided measurement of distal latency, amplitude and nerve conduction velocity plus author-designed negative surface area reading was done. The surface areas of different age groups ranged from 28.6 to 35.3 ms*mV in abductor pollicis brevis and 30.0 to 31.5 ms*mV in abductor digiti minimi. There is no significant difference between different ages and between both sexes. The surface area showed statistically significant correlation with amplitude but no correlation with distal latency and nerve conduction velocity. It is concluded that as the concept of surface area is widely accepted and the measurement technique is more easily available, to set up a normal data base of surface area of the routinely examined muscle is very important and the surface area of CMAP should be included into the interpretation of routine nerve conduction studies.

Action Potentials↗
PubMed1988

In vitro fertilization in women with "frozen pelvis": clinical outcome of treatment.

The outcome of 93 consecutive cycles of in vitro fertilization (IVF) and embryo transfer (ET) treatment in 52 women with "frozen pelvis" is reported. The treatment termination rate due to inadequate ovarian stimulation was 20%. The mean +/- standard deviation of the number of follicles of mean diameter greater than or equal to 15 mm, oocytes recovered and fertilized per operation, and embryos replaced per cycle were 4.80 +/- 2.07, 4.02 +/- 2.32, 2.54 +/- 2.06, and 2.57 +/- 1.30, respectively. The pregnancy rate per ET was 29.6%. These data compare with those of other treated women with adhesion-free ovaries over the same period, suggesting that pelvic adhesive disease has no adverse effect on outcome of IVF-ET.

Adnexal Diseases↗