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Biomedical subjects

K H Lim

Publications and source records attributed to K H Lim.

At least 37 records · Page 2Linked to original sources
PubMed2001

Awake respiratory function in patients with the obstructive sleep apnoea syndrome.

INTRODUCTION: The flow-volume curves of patients with obstructive sleep apnoea (OSA) obtained during the awake state are frequently abnormal. OBJECTIVE: To determine 1) the relationship between the awake respiratory function and the severity of sleep-disordered breathing in a group of Malaysian patients with the OSA syndrome and 2) the frequency of flow-volume curve abnormality in these patients. MATERIALS AND METHODS: A retrospective analysis of the data from respiratory function tests during wakefulness and nocturnal polysomnography was performed on 48 patients with OSA. The severity of OSA was defined by the apnoea-hypopnoea index (AHI) and the lowest oxygen saturation during sleep (SpO2nadir). RESULTS: AHI had a significant relationship with alveolar-arterial oxygen gradient (r = 0.34, p = 0.046) and SpO2nadir (r = -0.49, p < 0.001) but not with any anthropometric parameter or the other awake respiratory function variables measured. SpO2nadir had a significant relationship with body mass index (r = -0.54, p < 0.001), neck circumference (r = -0.39, p = 0.013), awake room air PaO2 (r = 0.61, p < 0.001), alveolar-arterial oxygen gradient (r = -0.41, p = 0.015) and baseline supine SpO2 (r = 0.53, p < 0.001). There was no correlation between SpO2nadir and any spirometric or static lung volume parameters. The maximum inspiratory and maximum expiratory flow-volume curves of 26 patients (54%) showed a ratio of forced expiratory flow to forced inspiratory flow at mid-vital capacity (FEF50/FIF50) greater than one. In addition, flow oscillations (the "sawtooth" sign) were noted in the inspiratory and/or expiratory flow-volume curves of 21 patients (44%), 9 of whom did not have an FEF50/FIF50 > 1. Altogether, the maximum flow-volume curves during wakefulness of 35 (73%) of the 48 patients showed variable upper airway obstruction and/or flow oscillations. However, the presence of these two upper airway abnormalities, either occurring alone or together did not have an effect on the severity of OSA as measured by the AHI or SpO2nadir. CONCLUSIONS: Abnormalities of the flow-volume loop consistent with inspiratory flow limitation and/or upper airway instability during wakefulness are common in patients with the OSA syndrome. The degree of oxygen desaturation during sleep in these patients is related to their awake oxygenation status.

Adult↗
PubMed2001

Relationship between symptoms and objective measures of airway obstruction in asthmatic patients.

The objective of this study was to determine the relationship between asthma symptoms and the degree of airway obstruction as measured by the forced expiratory volume in one second (FEV1) and peak expiratory flow rate (PEFR) in a group of 64 asthmatic patients with clinically stable disease attending a university-based urban asthma clinic. Asthma symptoms did not correlate with the degree of airway obstruction as measured by prebronchodilator PEFR (total asthma symptom score vs PEFR: r = -0.214, p = 0.104, n = 59) and only correlated poorly with prebronchodilator FEV1 (total asthma symptom score vs FEV1: r = -0.256, p = 0.041, n = 64). These results lend support to the recommendation that airway obstruction should be measured objectively when assessing patients with chronic persistent asthma.

Administration, Inhalation↗
PubMed2000

Protection of hearts from reperfusion injury by propofol is associated with inhibition of the mitochondrial permeability transition.

OBJECTIVE: Diminishing oxidative stress may protect the heart against ischaemia-reperfusion injury by preventing opening of the mitochondrial permeability transition (MPT) pore. The general anaesthetic agent propofol, a free radical scavenger, has been investigated for its effect on the MPT and its cardioprotective action following global and cardioplegic ischaemic arrest. METHOD: Isolated perfused Wistar rat hearts were subjected to either warm global ischaemia (Langendorff) or cold St. Thomas' cardioplegia (working heart mode) in the presence or absence of propofol. MPT pore opening was determined using [3H]-2-deoxyglucose-6-phosphate ([3H]-DOG-6P) entrapment. The respiratory function of isolated mitochondria was also determined for evidence of oxidative stress. RESULTS: Propofol (2 micrograms/ml) significantly improved the functional recovery of Langendorff hearts on reperfusion (left ventricular developed pressure from 28.4 +/- 6.2 to 53.3 +/- 7.3 mmHg and left ventricular end diastolic pressure from 52.9 +/- 4.3 to 37.5 +/- 3.9 mmHg). Recovery was also improved in propofol (4 micrograms/ml) treated working hearts following cold cardioplegic arrest. External cardiac work on reperfusion improved from 0.42 +/- 0.05 to 0.60 +/- 0.03 J/s, representing 45-64% of baseline values, when compared to controls (P < 0.05). Propofol inhibited MPT pore opening during reperfusion, [3H]-DOG-6P entrapment being 16.7 vs. 22.5 ratio units in controls (P < 0.05). Mitochondria isolated from non-ischaemic, propofol-treated hearts exhibited increased respiratory chain activity and were less sensitive to calcium-induced MPT pore opening. CONCLUSION: Propofol confers significant protection against global normothermic ischaemia and during cold cardioplegic arrest. This effect is associated with less opening of mitochondrial MPT pores, probably as a result of diminished oxidative stress. Propofol may be a useful adjunct to cardioplegic solutions in heart surgery.

Analysis of Variance↗
PubMed2000

Application of breath-hold T2-weighted, first-pass perfusion and gadolinium-enhanced T1-weighted MR imaging for assessment of myocardial viability in a pig model.

The purpose of this study was to correlate the abnormal signal area on various magnetic resonance (MR) images to the infarct area on pathologic examination and to assess the myocardial viability on the basis of MR images. T2-weighted, first-pass perfusion, and delayed gadolinium-enhanced T1-weighted images were used as "one-stop examinations" in a pig model of reperfused myocardial infarction. The results of each MR image were compared with those of 2,3, 5-triphenyltetrazolium chloride (TTC) staining. The abnormal signal areas on T2-weighted and Gd-enhanced T1-weighted images were larger than the infarct areas on TTC staining (34.7% and 32.3% vs. 28.3%; P< 0.05), whereas the nonperfused areas on perfusion images were correlated (25.6% vs, 28.3%; P = 0.139). Electron microscopic examination showed severely distorted ultrastructures in the infarct areas and mildly damaged ultrastructures in the peri-infarct areas. Perfusion images probably reflected the infarct areas, whereas T2-weighted and Gd-enhanced T1-weighted images seemed to include peri-infarct as well as infarct areas.

Animals↗
PubMed2000

Causes of pleural exudates in a region with a high incidence of tuberculosis.

OBJECTIVE: To define the causes of exudative pleural effusions in our region. METHODOLOGY: A retrospective study was performed on consecutive patients with exudative pleural effusion seen in our hospital during a 4-year period. RESULTS: Of 186 patients with a mean age (+/- SD) of 51.2 (+/- 19.2) years with exudative pleural effusions, 131 (70.4%) were males and 55 (29.6%) were females. The most frequent cause of exudative pleural effusions was tuberculosis (44.1%), followed by malignancy (29.6%). The majority (94.5%) of malignant pleural effusions were due to lung cancer. Apart from a patient with bilateral pleural effusions due to cryptococcosis, patients with tuberculous pleural effusion (mean age (+/- SD), 39.7 (+/- 17.5)) were significantly younger than the rest (P < 0.05). Tuberculous effusions were most frequent in the first five decades (60/82, 73.2%) and were the most common type of pleural effusion, accounting for 60 (69.8%) of 86 cases, in this age range. Malignant effusions were more frequent among the older age groups, 74.5% (41/55) of patients with malignant effusions being older than 50 years. Most types of pleural effusions showed a preference for the right side. Of the 44 cases of large effusions, 28 (63.6%) were caused by malignancy. CONCLUSIONS: In our region with a high incidence of tuberculosis, the most frequent cause of pleural exudates is tuberculosis followed by malignancy, particularly lung cancer.

Adult↗
PubMed2000

Irreversibly damaged myocardium at MR imaging with a necrotic tissue-specific contrast agent in a cat model.

PURPOSE: To investigate the capability of a necrosis-avid magnetic resonance (MR) contrast agent, bis-gadolinium mesoporphyrins, for assessment of irreversibly damaged myocardium and to evaluate the time course of signal enhancement in the reperfused myocardium. MATERIALS AND METHODS: Nine cats were subjected to 90 minutes of occlusion of the left anterior descending coronary artery followed by 90 minutes of reperfusion. Contrast material-enhanced T1-weighted spin-echo images were obtained for 12 hours in five cats and 6 hours in four cats. Pathologic examinations of the resected specimens were performed with 2'3'5-triphenyl tetrazolium chloride (TTC) histochemical staining and electron microscopy. The size of enhanced area on MR images was compared with that of irreversibly damaged myocardium with TTC staining. The time course of signal enhancement was evaluated. RESULTS: The size of enhanced area on MR images was well correlated with that of irreversibly damaged myocardium with TTC staining. Maximum enhancement occurred 1-3 hours after administration of the contrast material, with mean enhancement of 171% that of normal myocardium. Electron microscopic examinations showed severe myocardial damage in the irreversibly damaged myocardium but only mild edematous changes in the reversibly damaged myocardium. CONCLUSION: MR images enhanced with bis-gadolinium mesoporphyrins provide accurate sizing of irreversibly damaged myocardium with a strong and persistent signal enhancement in the reperfused myocardium.

Animals↗
PubMed2000

Placental peroxisome proliferator-activated receptor-gamma is up-regulated by pregnancy serum.

Lipid metabolism plays an important role in normal pregnancy adaptation and in pathological pregnancy (e.g. preeclampsia). In the current studies we examined the expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) in tissues and cells relevant to human pregnancy. We found that PPARgamma is expressed in placental cytotrophoblasts in vivo and in trophoblasts (primary and choriocarcinoma cells) and fetal endothelial cells in vitro. We characterized primary cytotrophoblasts and two cell lines with which to study PPARgamma regulation in human pregnancy. Like primary cytotrophoblasts, the choriocarcinoma cell line JEG-3 has endogenous PPARgamma expression. Normal positive and negative PPARgamma regulation was observed in the latter cells. We also created a new JEG-3-derived cell line (EP-JEG) by stable insertion of a PPAR response element-luciferase reporter gene construct. Together, these cell lines are useful for studying PPARgamma expression and activation in human trophoblasts. We examined PPARgamma regulation in these cells by human serum and found that PPARgamma protein expression and activation are dramatically increased by sera from pregnant women. Preliminary characterization of the regulatory principle(s) is consistent with a prostanoid or fatty acid derivative. The results suggest that increased activation of PPARgamma may play an important role in maternal metabolism during human pregnancy.

Adult↗
PubMed2000

Taraxacum officinale inhibits tumor necrosis factor-alpha production from rat astrocytes.

Substance P (SP) can stimulate production of tumor necrosis factor-alpha (TNF-alpha) from astrocytes stimulated with lipopolysaccharide (LPS). The objective of the current study was to determine the effect of Taraxacum officinale (TO) on the production of TNF-alpha from primary cultures of rat astrocytes. TO (100 and 1000 microg/ml) significantly inhibited the TNF-alpha production by astrocytes stimulated with LPS and SP. Interleukin-1 (IL-1) has been shown to elevate TNF-alpha production from LPS-stimulated astrocytes while having no effect on astrocytes in the absence of LPS. We therefore examined whether IL-1 mediated inhibition of TNF-alpha production from primary astrocytes by TO. Treatment of TO (100 and 1000 microg/ml) to astrocytes stimulated with both LPS and SP decreased IL-1 production significantly. Moreover, the production of TNF-alpha by LPS and SP in astrocytes was progressively inhibited with increasing amount of IL-1 neutralizing antibody. Our results suggest that TO may inhibit TNF-alpha production by inhibiting IL-1 production and that TO has an antiinflammatory activity in the central nervous system.

Animals↗
PubMed2000

Differences in pleural fluid characteristics, white cell count and biochemistry of tuberculous and malignant pleural effusions.

Tuberculosis and malignancy are two common causes of exudative pleural effusions. In this retrospective study of 52 patients with tuberculous pleural effusions and 32 patients with malignant effusions, the median age of patients with malignant effusions (68.5 years) was older than that of patients with tuberculous effusions (34.5 years) (p < 0.001). Both types of effusion occurred more frequently on the right side and there was no difference between them in terms of right-sided dominance. A higher percentage of patients with malignant pleural effusions (44%) presented with large effusions than patients with tuberculous effusions (12%) (x2 = 11.33, p = 0.001). A higher proportion of patients with tuberculous effusion had lymphocyte predominant effusions and tuberculous effusions had higher lymphocyte percentage, lower red cell count, and higher protein content. However, there was considerable overlap of these characteristics of both types of effusions.

Adult↗
PubMed2000

Lung cancer in patients younger than 40 years in a multiracial Asian country.

OBJECTIVE: This study aimed to determine whether the clinicopathological features of lung cancer in patients younger than 40 years differ from that of older patients in an Asian country. METHODOLOGY: We undertook a review of the clinicopathological data of all patients with confirmed primary lung cancer at the Department of Medicine, University of Malaya Medical Centre, Kuala Lumpur, Malaysia, from October 1991 to September 1999. RESULTS: Of the 580 patients with lung cancer, 36 (6.2%; 23 males, 13 females) were 21-39 years old at diagnosis. The percentage of people who had never smoked was higher among the younger patients (58.3% vs 19.1%, P < 0.001). Although adenocarcinoma was the most common cell type in both groups, its incidence was higher in the younger patients (24/36 (66.7%) vs 228/544 (41.9%), P = 0.007). The mean World Health Organization performance status at presentation was worse in the younger patients (2.4 vs 2, P = 0.007). In the case of non-small cell lung cancer, all the younger patients presented with either stage IIIb or metastatic disease compared to 77.2% of the older patients (P < 0.001). CONCLUSIONS: Younger lung cancer patients were more likely than older patients to have never smoked, to have adenocarcinoma, and to present with poorer performance status and with more advanced-stage non-small cell lung cancer.

Adenocarcinoma↗
PubMed2000

Intravenous followed by oral ofloxacin in the treatment of community acquired lower respiratory tract infections in adults requiring hospitalisation.

Forty patients were treated with ofloxacin for community acquired lower respiratory tract infections. Eighteen pathogens were isolated in sputum; Streptococcus pneumoniae (4) and Haemophilus influenzae (4) were the most common, followed by Klebsiella pneumoniae (3), Klebsiella spp. (2), Staphylococcus anreus (2), Pseudomonas spp. (2), and Pseudomonas aeruginosa (1). Ofloxacin 200 mg every 12 hours was administered for an average of 3.7 days intravenously followed by 5.4 days orally. Response to therapy was judged to be cure in 38 (95%; 95% C.I., 85%-95%) patients, failure in one (2.5%) and "indeterminate" in one (2.5%).

Administration, Oral↗
PubMed2000

Acceptance of the Accuhaler, a multi-dose powder inhaler, among asthmatic patients: a comparison with the pressurized metered-dose inhaler.

This study aimed to evaluate dry powder inhaler naive asthmatic patients' perception and preference of the Accuhaler, a multidose dry powder inhaler and the pressurized metered dose inhaler (pMDI). After the first instruction, 66.7% of 48 patients enrolled in the study could demonstrate the correct use of the Accuhaler. When the patients were asked to compare the pMDI and the Accuhaler after using the Accuhaler to administer salmeterol for 4 weeks, the Accuhaler scored significantly better than the pMDI for the following features: knowing how many doses are left, presence of an attached cover, taste, instruction for use, attractiveness, ease of use, ease of holding, shape, and comfortable mouthpiece. The pMDI scored better to the Accuhaler in terms of size. More patients preferred the Accuhaler than the pMDI; the presence of a dose counter and perceived ease of use were the main reasons cited for their preference for the Accuhaler.

Administration, Inhalation↗
PubMed1999

Giant cell arteritis presenting as chronic cough and prolonged fever.

A 62-year-old man presented with a 3-month history of chronic non-productive cough and unexplained fever. Further questioning revealed that he had headaches and myalgia. Bilateral thickened temporal arteries were noted on physical examination. The erythrocyte sedimentation rate was 96 mm in 1 h. A biopsy specimen of the left temporal artery showed inflammatory changes consistent with the diagnosis of giant cell arteritis. Commencement of prednisolone resulted in rapid and dramatic resolution of his symptoms. Physicians should be aware of respiratory symptoms in patients with giant cell arteritis in order to avoid delay in diagnosis and therapy of this condition.

Chronic Disease↗
PubMed1999

Massive pleural effusions in cryptococcal meningitis.

Cryptococcal infection uncommonly presents with pulmonary manifestations and even more rarely so as massive bilateral effusions. Pleural involvement is usually associated with underlying pulmonary parenchymal lesions and is unusual while on antifungal therapy. We report a patient with cryptococcal meningitis who, while on intravenous 5-flucytosine and amphotericin B, developed life-threatening bilateral massive pleural effusions with evidence of spontaneous resolution, consistent with prior hypothesis of antigenic stimulation as the cause of pleural involvement.

Adult↗
PubMed1999

Attitudes and knowledge of newly diagnosed tuberculosis patients regarding the disease, and factors affecting treatment compliance.

SETTING: An urban university teaching hospital. OBJECTIVES: To determine patients' attitudes to tuberculosis and their knowledge of the disease, and factors associated with treatment compliance. DESIGN: All adult patients commenced on treatment for tuberculosis from September 1994 to February 1996 were interviewed on initiation of treatment. To assess patient compliance with treatment, hospital clinical records were reviewed retrospectively. RESULTS: A total of 135 patients with a mean age (+/-SD) of 41.9 (+/-17.4) years (range 15-84 years) were interviewed. The patients had limited understanding and knowledge about tuberculosis. There was a negative correlation between patient age and tuberculosis knowledge score (r = -0.18, P = 0.038). Patients with tertiary education had better knowledge than the others. Of 118 patients who were followed-up in our chest clinic, 80 (67.8%) completed the prescribed treatment. Compliance with treatment and follow-up was not affected by age, sex, ethnic group, educational level, occupation, extent of knowledge, tuberculosis symptoms, hospitalisation for tuberculosis or duration of the prescribed treatment regimen. There was a trend toward poorer compliance among patients who equated disappearance of tuberculosis symptoms with cure of the disease. CONCLUSIONS: Malaysian patients with newly diagnosed tuberculosis attending a university teaching hospital had misconceptions and limited knowledge about the disease and its treatment. Educational background was an important determinant of a patient's level of knowledge about tuberculosis. Compliance was not affected by patient characteristics. Adequate counselling and education of patients and close relatives on tuberculosis and the necessity for prolonged treatment may help to improve treatment compliance.

Adolescent↗