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Biomedical subjects

M Tse

Publications and source records attributed to M Tse.

12 recordsLinked to original sources
PubMed1998

Membrane-limited expression and regulation of Na+-H+ exchanger isoforms by P2 receptors in the rat submandibular gland duct.

1. Cell-specific reverse transcriptase-polymerase chain reaction (RT-PCR), immunolocalization and microspectrofluorometry were used to identify and localize the Na+-H+ exchanger (NHE) isoforms expressed in the submandibular gland (SMG) acinar and duct cells and their regulation by basolateral and luminal P2 receptors in the duct. 2. The molecular and immunofluorescence analysis showed that SMG acinar and duct cells expressed NHE1 in the basolateral membrane (BLM). Duct cells also expressed NHE2 and NHE3 in the luminal membrane (LM). 3. Expression of NHE3 was unequivocally established by the absence of staining in SMG from NHE3 knockout mice. NHE3 was expressed in the LM and in subluminal regions of the duct. 4. Measurement of the inhibition of NHE activity by the amiloride analogue HOE 694 (HOE) suggested expression of NHE1-like activity in the BLM and NHE2-like activity in the LM of the SMG duct. Several acute and chronic treatments tested failed to activate NHE activity with low affinity for HOE as expected for NHE3. Hence, the physiological function and role of NHE3 in the SMG duct is not clear at present. 5. Activation of P2 receptors resulted in activation of an NHE-independent, luminal H+ transport pathway that markedly and rapidly acidified the cells. This pathway could be blocked by luminal but not basolateral Ba2+. 6. Stimulation of P2U receptors expressed in the BLM activated largely NHE1-like activity, and stimulation of P2Z receptors expressed in the LM activated largely NHE2-like activity. 7. The interrelation between basolateral and luminal NHE activities and their respective regulation by P2U and P2Z receptors can be used to co-ordinate membrane transport events in the LM and BLM during active Na+ reabsorption by the SMG duct.

Adenosine Triphosphate↗
PubMed1995

Propranolol disposition in Chinese subjects of different CYP2D6 genotypes.

Propranolol pharmacokinetics among different genotypes of CYP2D6 was compared in this study. The Chinese (Han) population consisted of 44 healthy unrelated individuals living in southern Taiwan. Endonuclease tests based on polymerase chain reaction were used to determine C/T188 genotypes of CYP2D6 in leukocyte deoxyribonucleic acid. Based on codon 188 genotypes, subjects were categorized into three groups: homozygous C/C188 (n = 13), heterozygous C/T188 (n = 14); and homozygous T/T188 (n = 17). Each subject was given a 40 mg propranolol tablet. Blood samples were drawn before and 12 hours after propranolol administration to measure propranolol and 4-hydroxypropranolol. Three genotypes showed distinct time profiles of plasma propranolol and 4-hydroxypropranolol. The area under plasma concentration curve values (mean +/- SEM), were 322.0 +/- 40.8, 481.6 +/- 77.5, and 766.1 +/- 92.8 nmol.hr/L, respectively, for C/C188, C/T188, and T/T188 subjects (p < 0.05). The 48-hour excreted amount of 4-hydroxy-S-propranolol-O-glucuronide, but not 4-hydroxy-R-propranolol-O-glucuronide, was significantly higher for C/C188 than for T/T188 subjects (p < 0.05). This study shows a different propranolol disposition in Chinese subjects of different CYP2D6 genotypes.

Adrenergic beta-Antagonists↗
PubMed1995

Asthma management and morbidity in Australian general practice: the relationship between patient and doctor estimates.

The aims of this study were to describe asthma management and morbidity in patients attending general practitioners in Australia, and to assess the relationship between patient reports and those of their general practitioner (GP). The sample comprised consecutive patients attending 46 general practitioners chosen at random in five regions of New South Wales, Australia. A total of 4538 patients were screened, 607 (13.4%) reported ever having diagnosed asthma, and the 501 who reported asthma in the previous 12 months completed a detailed questionnaire. Three hundred and thirty-four patients also had information about their asthma management recorded by their GP. The patient questionnaire asked about asthma symptoms, therapy, lung function measurement, and asthma-related morbidity. The GP questionnaire asked the doctor to record similar information about the patients. Two-thirds of the patients used regular inhaled beta 2-agonist medication, and one-half reported using preventive therapy. Only 24% owned a peak flow meter and 9% had a written plan of action for asthma attacks. Although preventive therapy and airway function assessment were more common in those with frequent symptoms (> 2-3 times per week), this group were still sub-optimally managed. In the matched sample (n = 334), doctors reported prescribing bronchodilator and preventive medication, measuring airway function and recommending peak flow meter use more often than suggested by patient-reported data. The study concludes that many patients do not attend for regular review, and that management remains sub-optimal, particularly in young adults. Data from patient surveys may underestimate clinical practice, as assessed from doctors' records. This should lead to patient-derived estimates of management being interpreted with caution in epidemiological studies. Further attention to patient understanding and compliance with prescribed asthma management advice is needed in order to better manage asthma in the community.

Adolescent↗
PubMed1993

Asthma management in general practice.

OBJECTIVE: To provide guidelines for management of asthma in general practice. DATA SOURCES: Selected articles, particularly those relating to general practice. CONCLUSION: Better management of asthma requires strategies for dealing with long-term management as well as acute attacks. Planning such strategies and implementing personal management plans for each patient requires assessment of asthma severity; determination and maintenance of best achievable lung function, with avoidance of trigger factors, regular monitoring, and appropriate drug therapy; a written self-management plan as a basis for patient and family education; and regular review.

Acute Disease↗
PubMed1993

The impact of a mass communications campaign on the reported management of asthma by general practitioners.

There have been recent campaigns in many countries to address the increasing morbidity and mortality of asthma by promoting better management. This study aimed to evaluate the National Asthma Campaign (NAC), in Australia, and to assess the extent of its impact on reported asthma management. It was a cross-sectional, before and after study using the same self-administered questionnaire in postal surveys involving 472 general practitioners (GPs) before the campaign and 540 GPs 6 months after the start of the campaign. Both samples were random samples of GPs in active practice. The campaign was effective in making GPs more aware of the principles of good asthma management. Most (74%) GPs in the post-campaign survey were aware of a current asthma education programme compared with 53% in the pre-campaign survey, although only 23% cited the NAC. After the campaign there were significant improvements reported in airway function measurement practices, the use of preventive therapy and the use of written action plans.

Asthma↗
PubMed1993

Asthma in general practice. Opportunities for recognition and management.

OBJECTIVE: To describe the prevalence of asthma-related symptoms and asthma among patients attending general practitioners. SETTING: Sydney. DESIGN: Cross-sectional survey by written questionnaire. SAMPLE: 1933 patients of 21 general practitioners. RESULTS: 1. Wheeze and asthma were common in patients attending general practitioners; 19 per cent of patients reported recent wheeze, 9 per cent reported recent asthma. 2. Less than half of all patients with recent wheeze (47%) reported having asthma. 3. Recent wheeze without asthma was more common in boys (4.8%) than girls (0%) and more common in men (10%) than women (7%). 4. Although most patients reporting asthma (95%) had had their asthma treated by a doctor, three-quarters of those patients had experienced asthma related symptoms in the previous year. CONCLUSION: Asthma remains under-recognised and under-treated among patients attending general practitioners.

Adolescent↗
PubMed1991

Cardiac pacemaking in Hong Kong: report of a survey of general practitioners and internists.

A questionnaire study was carried out among cardiologists, internists, general practitioners, and final year medical students in Hong Kong concerning cardiac pacemaking. The response rate was 11.2%. Salient results include the misconception on the part of 40% and 12% of physicians, that general anesthesia and thoracotomy respectively, are commonly required for permanent pacing and that the procedure is associated with significant mortality (14.2% of physicians). Most would offer permanent pacing to patients with symptomatic complete atrioventricular block, but advanced age appeared to be considered as a barrier to permanent pacemaking. There was confusion about the need to pace asymptomatic sick sinus syndrome and bundle branch conduction diseases. Oral isoprenaline was still used to treat bradycardia by 16.6% of physicians. A similar deficiency in knowledge was found among the students. It is suggested that misunderstanding of cardiac pacing is common and may be a reflection of the lack of emphasis in undergraduate teaching. This deficiency may have prevented some patients from receiving the benefits of permanent pacing.

Adult↗
PubMed1991

Asthma management in general practice.

A postal survey of selected general practitioners from Brisbane, Melbourne, Sydney and rural New South Wales was conducted to compare general practitioners' self-reported asthma management practices with the Asthma Management Plan (1989) of the Thoracic Society of Australia and New Zealand. The results suggest that most general practitioners know and practise appropriate asthma management. Room for improvement, however, was detected in the following areas: 1. appropriate understanding of the use of theophyllines, 2. the use of preventive medications such as inhaled steroid and sodium cromoglycate, 3. use of crisis planning for severe asthma attacks, 4. lung function measurement.

Administration, Inhalation↗
PubMed1990

Rabbit ileal villus cell brush border Na+/H+ exchange is regulated by Ca2+/calmodulin-dependent protein kinase II, a brush border membrane protein.

Ileal brush border membranes contain an endogenous Ca2+/calmodulin (CaM)-dependent protein kinase activity that modulates the activity of the apical membrane Na+/H+ exchanger. To further characterize this kinase, synapsin I, a substrate for Ca2+/CaM-dependent protein kinases, was added to preparations of ileal brush border membranes. In the presence of Ca2+/CaM, synapsin I was phosphorylated. Phosphopeptide mapping demonstrated that the addition of Ca2+/CaM to brush border membranes stimulated the phosphorylation of sites in synapsin I specific for Ca2+/CaM-dependent protein kinase II. Immunoblots containing brush border and microvillus membrane proteins were probed with an antibody that recognizes the 50-kDa subunit of rat brain Ca2+/CaM-dependent protein kinase II. This antibody labeled major and minor species of 50 and 53 kDa, respectively, with more labeling of the brush border than the microvillus membranes. Right-side-out ileal villus cell brush border vesicles were prepared containing CaM, ATP, and 350 nM free Ca2+. Na+/H+ exchange was inhibited by the presence of Ca2+/CaM/ATP within the vesicles. A 21-amino acid peptide inhibitor of CaM kinase II was enclosed within some vesicle preparations by freeze-thaw. The effect on Na+/H+ exchange of Ca2+/CaM/ATP was partially reversed by the inhibitor peptide. These studies demonstrate the presence of Ca2+/CaM-dependent protein kinase II in rabbit ileal villus cell brush border membranes. Based on the effect of a specific inhibitor peptide of Ca2+/CaM kinase II, it is concluded that this kinase inhibits brush border Na+/H+ exchange, which participates in the regulation of ileal Na+ absorption.

Animals↗