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Biomedical subjects

H S Lim

Publications and source records attributed to H S Lim.

At least 55 records · Page 3Linked to original sources
PubMed1996

Maximal airway narrowing on the dose-response curve to methacholine is increased after exercise-induced bronchoconstriction.

The changes in airway responsiveness between before and after exercise in asthma are not well defined. We investigated the effect of exercise on PC20 (bronchial sensitivity) and maximal airway narrowing (MAN) on the dose-response curve to methacholine in 56 mildly asthmatic children. High-dose methacholine inhalation tests were performed before and 7 hr after exercise challenge. Methacholine PC20 was not changed by exercise, irrespective of exercise-induced bronchoconstriction (EIB). However, the subjects with (+)EIB displayed increased MAN after exercise, whereas those with (+/-)EIB or (-)EIB did not. The results showed that EIB may be followed by increased MAN but not by the change of bronchial sensitivity.

Administration, Inhalation↗
PubMed1995

In vitro metabolism of testosterone by gonads of the grouper (Epinephelus tauvina) before and after sex inversion with 17 alpha-methyltestosterone.

The steroidogenic potential of gonadal tissues of the protogynous grouper (Epinephelus tauvina) was examined before and after sex inversion with 17 alpha-methyltestosterone. Incubations of gonadal tissues of the fish with [3H]testosterone resulted in the biosynthesis of 5 beta-androstane-3 beta, 17 beta-diol and 5 beta-dihydrotestosterone as the only metabolites in the female phase. Although the production of these 5 beta-reduced androgens persisted in the male phase, there was a shift toward the production of 11 beta-hydroxytestosterone and 11-ketotestosterone as major metabolites.

Androstane-3,17-diol↗
PubMed1995

Association of exposure to polycyclic aromatic hydrocarbons (estimated from job category) with concentration of 1-hydroxypyrene glucuronide in urine from workers at a steel plant.

OBJECTIVES: Increased risk of lung cancer has been associated with employment in the steel industry. This association is thought to be due in part to increased concentrations of polycyclic aromatic hydrocarbons (PAHs) in air found in this work environment. Measurement of PAH metabolites in human urine provides a means of assessing individual internal dose of PAHs. This study examined the relative contribution of occupation and smoking to urinary concentration of 1-hydroxypyrene glucuronide (1-OHPG) among a group of workers at a steel plant. METHODS: Concentrations of 1-OHPG in urine from 44 workers with jobs associated with increased air concentrations of PAHs and 40 workers with jobs with low or no exposure to PAHs were measured. 20 workers in each group were not current smokers. Urinary 1-OHPG was measured by synchronous fluorescence spectroscopy after immunoaffinity chromatography specific for PAH metabolites. RESULTS: Mean (SEM) urinary 1-OHPG concentration was 2.16 (0.42) pmol/ml urine among the 44 occupationally exposed workers compared with 0.38 (0.05) among the 40 workers with no or low exposure (P < 0.0001). Mean urinary 1-OHPG concentration was 1.82 (0.41) pmol/ml urine among the 44 current smokers compared with 0.75 (0.20) among the 40 non-smokers (P < 0.005). Mean 1-OHPG concentrations in non-smokers were 0.26 (n = 20), 0.70 (n = 15), and 2.84 pmol/ml urine (n = 5) for strata of exposure to PAHs (no or low, mid, and high) based on job category; the corresponding values in smokers were 0.55 (n = 20), 0.94 (n = 12), and 4.91 pmol/ml (n = 12), respectively. Multiple linear regression showed significant differences between subjects in different PAH exposure with increased concentrations of 1-OHPG in urine. Amounts of foods containing PAHs ingested by this group of workers were relatively low and did not contribute significantly to urinary 1-OHPG concentrations. CONCLUSIONS: These results indicate that 1-OHPG is a common urinary metabolite in people with recent occupational exposure to PAHs and is associated with both job category and estimated stratum of PAH exposure.

Adult↗
PubMed1995

Reading-related wavelength and spatial frequency effects in visual spatial location.

Specific deficits in the processing of transient visual stimuli have been identified in reading-disabled children, and it has been shown that the filtering out of some medium to high spatial frequencies and some visible wavelengths impacts on their performance in a number of visual tasks. To assess further how these light diffusing and colour filtering manipulations might mediate visual processing, this study compared the letter-naming accuracy and visual spatial location judgements of eighteen poor readers with those made by eighteen good readers of the same age. Naming and spatial discrepancy measures were recorded for briefly displayed target letters at varying eccentricities, for each child, under a normal (NI) condition and wearing blue (Be), yellow (Yw), diffusion (Dn), blue with diffusion (BeDn), and yellow with diffusion (YwDn) optical framed lenses. A preliminary analysis of the data detected larger spatial discrepancies for the poor readers, and this finding was consistent with the presence of a deficit in transient (or magnocellular) activity in these children. Both the naming accuracy data and the spatial location data showed filter-dependent differences in reading ability. The letter-naming data showed that the addition of the blue filter to the diffusion lens significantly depressed performance only for the good readers, and that the addition of the yellow filter to the diffusion lens significantly improved performance only for the poor readers. Comparison of the spatial discrepancies showed that the rate at which location accuracy declined with increasing target eccentricity was smaller for the blue and yellow lenses than for normal viewing in the case of the good readers but not in the case of the poor readers.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1994

Airway responsiveness to allergen is increased 24 hours after exercise challenge.

Although exercise is one of the most ubiquitous triggers of acute bouts of asthma, the changes in airway responsiveness before and after exercise are not well defined. Specifically, the effect of the changes in airway responsiveness induced by exercise has not been studied on subsequent allergen exposure. To test whether the reactivity to allergen is altered by preceding exercise and to define possible factors determining it, we subjected 24 children with atopic asthma to the relevant allergen challenge on two occasions: one as a control without a preceding procedure and the other 24 hours after exercise challenge. Mean postallergen maximal percent falls in forced expiratory volume in 1 second from baseline (delta FEV1) of the whole group were higher after the exercise challenge compared with those of control in both early (< 1 hour) and late (3 to 10 hours) phases. The changes of postallergen maximal delta FEV1 between the control and post-exercise allergen challenges were not related to the early bronchial response to the preceding exercise challenge. Late asthmatic responses to exercise developed in six children, and the changes in both early and late phases were significantly higher in these children, compared with those without late asthmatic responses. Furthermore, the changes were well correlated with the magnitude of the late-phase response to preceding exercise in the group as a whole. It is concluded that an increased airway responsiveness to allergen occurs 24 hours after exercise in some patients with asthma. As the changes are related to a late bronchial response to exercise, late asthmatic response to exercise, when it occurs, may be associated with increased asthmatic symptoms for as long as 24 hours after exercise.

Adolescent↗
PubMed1994

Airways of allergic rhinitics are 'primed' to repeated allergen inhalation challenge.

The hypothesis that repeated exposure to a specific allergen will further increase bronchial responsiveness to that allergen is supported by indirect evidence. However, it has not been tested as intensely in the laboratory setting, and in some cases, conflicting results are presented. In order to test the hypothesis in the atopic subjects, allergen inhalation challenge tests were performed in 29 house dust mite (Dermatophagoides pteronyssinus) sensitive subjects with allergic rhinitis. Nine subjects displayed early asthmatic responses (EARs) to the first challenge (Group I). Twenty subjects with no significant airway response were submitted to the second challenge 24 h later. Thirteen subjects showed EARs (Group II) and two of these showed late asthmatic responses (LARs) as well. In Group II, there were significant changes between the first and second challenge in post-allergen early phase FEV1 (88.1 +/- 4.2 vs 71.7 +/- 4.2% baseline, P < 0.05) and in post-allergen late phase FEV1 (93.1 +/- 3.4 vs 86.6 +/- 7.8, P < 0.05). After the second challenge, PD20 (provocative dose of methacholine required to produce a 20% fall in FEV1) decreased significantly from the baseline values. When challenged separately with twofold dose of allergen, only three and one of the Group II showed EAR and LAR respectively. PD20 did not change significantly after this challenge. These results indicated that two repeated exposure to allergen dose, which is not enough to cause significant airway responses at a time, may provoke asthmatic airway responses in the subjects with allergic rhinitis and that this effect of priming is not attributed to the cumulative dose but to the consequent effect of repeated allergen exposure.

Administration, Inhalation↗
PubMed1991

Pseudomonas stutzeri YPL-1 Genetic Transformation and Antifungal Mechanism against Fusarium solani, an Agent of Plant Root Rot.

An actively antagonistic bacterium that could be used as a biocontrol agent against Fusarium solani, which causes root rots with considerable losses in many important crops, was isolated from a ginseng rhizosphere and identified as a strain of Pseudomonas stutzeri. In several biochemical tests with culture filtrates of P. stutzeri YPL-1 and in mutational analyses of antifungal activities of reinforced or defective mutants, we found that the anti-F. solani mechanism of the bacterium may involve a lytic enzyme rather than a toxic substance or antibiotic. P. stutzeri YPL-1 produced extracellular chitinase and laminarinase when grown on different polymers such as chitin, laminarin, or F. solani mycelium. These lytic extracellular enzymes markedly inhibited mycelial growth rather than spore germination and also caused lysis of F. solani mycelia and germ tubes. Scanning electron microscopy revealed degradation of the F. solani mycelium. Abnormal hyphal swelling and retreating were caused by the lysing agents from P. stutzeri YPL-1, and a penetration hole was formed on the hyphae in the region of interaction with the bacterium; the walls of this region were rapidly lysed, causing leakage of protoplasm. Genetically bred P. stutzeri YPL-1 was obtained by transformation of the bacterium with a broad-host-range vector, pKT230. Also, the best conditions for the transformation were investigated.

Journal Article↗
PubMed1991

Lactobacillus casei subspecies casei endocarditis--a case report.

Lactobacillus sp., generally considered to be a harmless indigenous bacteria of the mucous membrane, occasionally causes serious infections. Lactobacillus endocarditis is a very rare disease, and no case has been reported in Korea. Gram-positive bacilli were isolated from blood cultures of a 41-year-old man with clinically suspected subacute bacterial endocarditis. The patient had a dental procedure 3 months prior to the infection. The isolate was identified as L. casei subsp. casei based on the cultural characteristics and gas liquid chromatography of metabolic products. The patient was treated with ampicillin and improved. When Lactobacillus is isolated from the blood of an endocarditis patient, the significance should be seriously considered.

Adult↗
PubMed1990

[A survey on the epidemiological factors of clonorchiasis in the Pohang industrial belt along the Hyungsan river, Kyongsangbuk-do].

The employees at the Pohang industrial area, where Clonorchis sinensis has been known to be endemic along the Hyungsan River, were examined parasitologically for clonorchiasis and a part of the infected cases were surveyed with a questionnaire to outline the recent infection status of C. sinensis and epidemiological parameters in the area. Total of 3,180 cases were tested by intradermal inoculation of C. sinensis antigen (Green Cross Co., Korea), and 834 (26.2%) were found positive. Out of the positive cases, 598 were subjected to fecal examination for helminth ova. The examination revealed 129 (21.6%) ova positive cases of C. sinensis, and Trichuris trichiura 1.7%, Ascaris lumbricoides 0.3%, and Metagonimus yokogawai 0.2%. The questionnaire analysis showed some significant differences between the infected and non-infected (control) groups. The infected cases were less educated than the control, and they lived at the closer area to the river, and most of them lived there over 20 years. Also they preferred eating raw fresh water fish. Most of the detected cases were treated with praziquantel and found negative for the eggs in 85.3% of them 1 year after the treatment. The present data reveal markedly decreased endemicity of clonorchiasis compared with previous prevalence rates but still clonorchiasis is endemic in the Hyungsan river basin. A comprehensive measure including case detection, treatment and education for parasite control should be applied to control clonorchiasis in such endemic areas.

Adult↗
PubMed1990

Manifestations and outcome of treatment of thyrotoxicosis: a clinical study.

We studied a series of 89 consecutive patients who presented with thyrotoxicosis at a medical unit. Clinical parameters and laboratory abnormalities were recorded. Treatment was initiated and response in terms of side-effects, clinical and laboratory remissions were monitored. The frequency of the various clinical manifestations, cardiovascular and neurological complications were documented. Laboratory data on electrolytes, haematological changes and thyroid antibodies were noted. The treatment outcome revealed a relapse of 37.7% in patients with 6 months of treatment (90% occurred within the first year). We also noted that 6.7% of patients developed skin reaction. A treatment default rate of 30% was noted.

Adolescent↗
PubMed1990

Hypopituitarism following head injury--a case report.

A 16 year-old boy sustained fracture of the floor of the right orbital fossa in a road traffic accident with resultant diplopia and right enophthalmos. Symptoms of hypocortisolism subsequently developed. About two years after the trauma, pubertal changes which had occurred at 13-14 years had completely regressed. Endocrine testings confirmed clinical anterior hypopituitarism. Post-traumatic hypopituitarism may follow injury to the hypothalamus, the pituitary stalk or the pituitary itself. The normal thyroid stimulating hormone (TSH) response to thyrotropin releasing hormone (TRH) in this patient is in favour of a hypothalamic lesion. The patient has responded to replacement hormonal therapy.

Accidents, Traffic↗
PubMed1990

Effects of low dose guar in non-insulin dependent diabetic patients.

Thirteen non-obese, non-insulin-dependent diabetic patients were given guar granulate in an average dose of 7.1 grams daily for 8 weeks. The mean fructosamine fell from 3.3 +/- 0.69 mmol/L (p less than 0.01). Mean glycosylated haemoglobin (HbA1c) fell from 8.17 +/- 2.2% preguar to 7.67 +/- 1.81% (1 = ns) and to 7.39 +/- 1.23% (p = ns) at 8 weeks and 12 weeks postguar respectively. Eight weeks after the discontinuation of guar fructosamine rose to 3.61 +/- 0.95 mmol/L (p less than 0.05) while HbA1c rose to 8.23 +/- 2.08% (p = 0.05). There were no significant changes in fasting blood glucose, lipids, and body weight. Mild gastrointestinal side-effects occurred in 11 patients during the treatment with guar. It is concluded that daily ingestion of low dose guar modestly improves glycaemic control, such improvement dissipating by 8 weeks following cessation of its use.

Adult↗
PubMed1986

Legionnaires' disease--report of Singapore's first local case.

A previously healthy 27 year-old male plumber presented with six days of fever, nausea, vomiting, malaise and headache. The subsequent development of cough, dyspnoea and pleuritic pain coincided with the simultaneous development of progressive bilateral cavitary pneumonia with pleural effusion. Leucocytosis, thrombocytopenia, hyponatraemia, hypoalbuminaemia, hypophosphataemia and hypoxaemia were the main laboratory abnormalities. Clinical suspicion of Legionnaires' disease was confirmed by the presence of serum antibody to Legionella pneumophila (titre 1:512) by an indirect fluorescent antibody test. Treatment with erythromycin and rifampicin resulted in clinical recovery with minimal residual bilateral pleural effusion six months after presentation. This patient is the first to acquire Legionnaires' disease in Singapore.

Adult↗
PubMed1985

Fast fraction haemoglobin (HbA1) in the assessment of diabetes control.

The degree of control of 132 diabetic patients was assessed using historical data, urine glucose and blood glucose measurements. These were then related to HbA1, taken as the final arbiter of glycaemic control. Symptoms of hyperglycaemia and glycosuria were found to be not sensitive or specific indices of control, though symptomatic glycosuric patients tended to have higher HbA1. Fasting blood glucose correlated modestly with HbA1 (r = 0.60, p less than 0.001) but if used alone to determine degree of control, 21% and 9% of patients could be expected to be over or under assessed respectively. The assessment value of timed post-breakfast blood glucose applied only to 120 and 150 minutes post-breakfast blood glucose as they correlated well with HbA1 (r = 0.73, p less than 0.001 and r = 0.96, p less than 0.001 respectively). Clinically impression of degree of control based on a combination of historical data, urine glucose and blood glucose led to "undertreatment" in 41% and "overtreatment" in 27% of patients. The complementary value of a knowledge of HbA1 was thus highlighted.

Adolescent↗