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Biomedical subjects

M K Lim

Publications and source records attributed to M K Lim.

At least 37 records · Page 2Linked to original sources
PubMed2000

Validity and cost-effectiveness of diagnostic procedures in CS2 poisoning.

To determine relatively useful diagnostic procedures of carbon disulfide (CS2) poisoning in terms of validity and cost-effectiveness, several diagnostic tests are evaluated on 1,552 people by prevalence ratio (exposed/nonexposed), dose-response relationship, sensitivity and specificity, and the cost of the tests. Several symptoms with high kappa indices are found to be useful in various combinations, showing a consistent dose-response relationship and high exposed-nonexposed ratio. In clinicopathologic tests on functions of the kidney, liver and hematopoietic systems, eight items out of 22 have been shown to have significant dose-response relationship, mostly in liver function tests. A thorough dental examination failed to identify any useful indicator peculiar to the CS2 poisoning. Unlike Western people, the prevalence of coronary heart disease among Koreans was too low to be useful in the diagnosis of CS2 poisoning. Among four elective tests, i.e., Minnesota Multiphasic Personality Inventory (MMPI), Brain magnetic resonance imaging (MRI), nerve conduction velocity (NCV), and fluorescent angiography (FAG), the NCV appeared to be a more sensitive and specific test than the others are. Combinations of the tests improved the probability of diagnosing CS2 poisoning cases when any one test out of four was positive. Addition of other valid tests increased the probability of excluding non-cases. It was concluded that diagnosis of CS2 poisoning could be made validly and inexpensively if the diagnostic tests were carefully chosen step by step.

Adolescent↗
PubMed1999

Induction of NADPH diaphorase/nitric oxide synthase in the spinal cord motor neurons of rats following a single and multiple non-penetrative blasts.

The present study has demonstrated the induction of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity and nitric oxide synthase-like immunoreactivity (NOS-LI) in the ventral horn motoneurons of the spinal cord in rats subjected to a single or multiple underground, or a single surface blast. Both enzyme activities were first detected in some motoneurons in laminae VIII and IX of Rexed, 3 hours after the blast. Some NADPH-d and NOS-LI positive neurons were also distributed in laminae VI and VII. The number and intensity of the labelled cells appeared to increase progressively, peaking at 2-3 days after the blast but were drastically reduced thereafter, so that at 7 days after the blast only a few positive neurons were observed. In rats killed at 2 weeks and in longer surviving intervals, i.e. up to 1 month, NADPH-d/NOS reactivity in the ventral horn motor neurons had diminished. The functional significance of the transient expression of neuronal NADPH-d/NOS after the blasts remains uncertain, although from a speculative point of view, the induction of these enzymes probably would reflect an increased production of nitric oxide (NO). In view of the lack of atrophic changes in most, if not all, of motor neurons, it is suggested that the increased levels of NO production after the blast injury may be involved in a neuroprotective function.

Animals↗
PubMed1999

1998 Andre Allard Lecture. Aerospace medicine in the 21st century--reaching for the stars.

The 21st century will be an era of unprecedented scientific achievements, one in which man will continue to overcome limits rather than be overcome by them. Aerospace medicine will continue to make significant contributions as aviation and space activities intensify, and as new technologies pose new aeromedical challenges. More than that, aerospace medicine's role will prove decisive in man's quest for his ultimate destiny in the universe.

Aerospace Medicine↗
PubMed1998

Esophageal rupture during balloon dilation of strictures of benign or malignant causes: prevalence and clinical importance.

PURPOSE: To review the prevalence and clinical importance of esophageal rupture during balloon dilation for treatment of esophageal stricture. MATERIALS AND METHODS: Fluoroscopically guided esophageal balloon dilation was performed within 9 years in 96 consecutive patients with esophageal strictures. Esophageal rupture was classified into three types: type 1 was intramural; type 2, transmural; and type 3, transmural with mediastinal leakage. RESULTS: Each patient underwent one to seven procedures, for a total of 191 procedures. Esophageal rupture occurred in 20 patients (21%). Type 1 esophageal rupture occurred in eight patients, type 2 in 11, and type 3 in one. All esophageal ruptures were detected immediately after the procedure. Sixteen patients were treated with fasting, parenteral alimentation, and antibiotics; two were treated surgically; and two were treated with stent placement. No treatment-related deaths occurred. CONCLUSION: The overall prevalence of esophageal rupture was 21%. A substantial number of patients who developed type 1 rupture had associated clinical symptoms, such as pain and fever, but responded to conservative management and are thus included as having complications of esophageal balloon dilation.

Adolescent↗
PubMed1998

Carotid artery dissection presenting as a painless Horner's syndrome in a pilot: fit to fly?

We describe a case of a middle-aged Caucasian pilot who presented to us with a painless left Horner's syndrome due to a focal dissection of the infra-petrous portion of the ipsilateral internal carotid artery. He did not suffer symptoms of cerebral ischemia at the time of onset, or during the following 2 yr. The Horner's syndrome persisted unchanged throughout follow-up. Serial magnetic resonance angiograms showed some regression of the focal stenosis at 12 mo, with no further change over the next 10 mo. The literature suggests that the risk of stroke after onset of dissection is usually in the first month, and the risk of recurrence of dissection is about 1% per year after the first year. Our patient was prescribed aspirin 300 mg.d-1, and certified to fly as or with a co-pilot commencing 1 yr after onset of his symptoms.

Aerospace Medicine↗
PubMed1998

A comparison of maximum oxygen consumption, aerobic performance, and endurance in young and active male smokers and nonsmokers.

The purpose of this study was to compare 2.4-km running performance in 2,639 smoking (SM) and nonsmoking (NS) male conscripts aged 18 to 26 years. Maximum oxygen consumption (VO2max) and aerobic exercise endurance were also compared between SM and NS subjects (N = 156) stratified into various running performance bands. SM subjects ran significantly slower (10.59 +/- 1.17 minutes) than NS subjects (10.32 +/- 1.03 minutes) in the 2.4-km run test (p < 0.001). The mean VO2max of SM subjects (53.38 +/- 8.58 ml kg-1 min-1) was not significantly different from that of the NS subjects (54.42 +/- 7.82 ml kg-1 min-1) (p > 0.05). Exercise endurance time on the treadmill protocol (EXtm) was significantly longer in the NS group only among those who completed the 2.4-km run in < 9.01 minutes (p < 0.05). Maximum minute ventilation (VEmax) was also significantly higher in the NS group in the < 9.01-minute performance band. No other significant differences were found between SM and NS subjects in EXtm and VEmax. Mean maximum heart rate achieved during the tread-mill test ranged from 180 +/- 4 to 191 +/- 12 beats per minute in the SM group and from 183 +/- 5 to 188 +/- 19 beats per minute in the NS group. These were not significantly different (p > 0.05). In conclusion, smoking habit was shown to influence aerobic performance in the 2.4-km run, VEmax, and EXtm only during high-intensity aerobic exercise. VO2max was not influenced by smoking habit when aerobic performance was held constant.

Adolescent↗
PubMed1997

Macrophages/microglia as 'sensors' of injury in the pineal gland of rats following a non-penetrative blast.

The pineal gland of adult rats was examined immunohistochemically and electron microscopically following exposure of the animals to a single blast equivalent to 110 kg TNT explosive. The most dramatic feature in rats killed at 7, 14 and 21 days after the blast was the upsurge of a large number of macrophages/microglia intensely immunostained with OX-42, OX-18, OX-6 and ED1 antibodies. These antibodies recognise the complement type three (CR3) receptors, major histocompatibility complex class I and class II (MHC I and MHC II) antigens and monocyte/macrophage antigens. Cell counts in OX-42 immunostained sections showed a two-fold increase at these intervals but returned to normal values at 28 days. The immunolabelled cells appeared extremely hypertrophic after the blast when compared with those in normal rats. In the latter and in rats killed at 28 days after the blast, immunoreactive cells were sparsely distributed. Ultrastructural study confirmed a wider occurrence of perivascular macrophages/microglia after the blast and the cells were laden with massive amounts of phagosomes resembling degenerating pinealocyte processes. It is concluded that the seemingly quiescent macrophages/microglia present normally in pineal gland were activated by the external blast force. The induced changes including the increase in cell numbers and endocytosis, however, were reversible in longer surviving animals.

Animals↗
PubMed1997

Idiopathic pulmonary fibrosis vs. pulmonary involvement of collagen vascular disease: HRCT findings.

The purpose of this study is to assess the differences of high-resolution CT (HRCT) findings in patients with idiopathic pulmonary fibrosis (IPF) and pulmonary involvement of collagen vascular disease (CVD). We analyzed the HRCT findings of 33 patients with IPF and 23 patients with CVD in terms of predominant pattern, site of involvement, mediastinal lymph node enlargement, pleural change, and pulmonary volume loss. The predominant HRCT pattern was honeycombing for IPF (58%), and ground-glass opacity for CVD (57%). Predominantly subpleural involvement was seen in 90% of IPF and 83% of CVD patients. Mediastinal lymph node enlargement was seen in 61% of the patients with IPF and 13% with CVD (p = 0.0004). Pleural thickening was seen in 97% of the patients with IPF and 35% with CVD and the severity of pleural thickening is statistically significant (p = 0.00001). Pleural effusion was seen in 6% of the patients with IPF and 26% with CVD (p = 0.0351). The hilar height ratio was more than 1.5 in 52% of the patients with IPF and 30% with CVD (p = 0.2620). Although HRCT findings of IPF and pulmonary involvement of CVD are similar and overlap considerably, but patients with IPF showed a tendency to more progressed fibrosis than patients with CVD.

Adult↗
PubMed1997

Burkholderia pseudomallei infection in the Singapore Armed Forces from 1987 to 1994--an epidemiological review.

Between 1987 and 1994, twenty-three cases of Burkholderia pseudomallei infection (melioidosis) were diagnosed in persons serving in the Singapore Armed Forces. There were four deaths resulting from complications of the infection. Unlike the situation in the general population, where the affected are mainly the elderly with underlying illness, the majority of cases in the Singapore Armed Forces were otherwise fit and healthy young servicemen. Serological surveys have shown the prevalence of the infection in Singapore to be 0.2% in the military as well as civilian population. As physical contact with soil is an unavoidable part of military training, military personnel continue to be at risk of exposure to this soil-related disease.

Adolescent↗
PubMed1997

Ultrastructural changes of macroglial cells in the rat brain following an exposure to a non-penetrative blast.

The present study examined the ultrastructural changes in astrocytes and oligodendrocytes in rats following an exposure to a non-penetrative blast. At 1 and 7 days after the blast, the astrocytes in the cerebral and cerebellar cortex were hypertrophied; their end-feet associated with the blood vessels were also swollen, bearing sparsely distributed organelles. The above changes were not observed in experimental rats when the survival interval was prolonged. It is concluded from this study that the blast could have disrupted the integrity of the blood-brain barrier resulting in possible abnormal entry of serum-derived substances thereby leading to astrocytic hypertrophy. The reversible nature of the changes is evidenced by the seemingly normal appearance of astrocytes in rats killed at 14, 21 and 28 days after the blast. Oligodendrocytes remained unaffected at various time intervals after the blast.

Animals↗
PubMed1997

Rubella seroprevalence in the Singapore Armed Forces (SAF) and the changing need of the SAF rubella immunisation programme.

A seroepidemiological study on the prevalence of rubella antibodies in a cohort of Singapore Armed Forces (SAF) recruits was conducted in 1994, twelve years after rubella immunisation was routinely given to primary 6 school boys in 1982. The results showed a high level of immunity (97.1% seropositive) in the study cohort. The implication of this finding is that it may no longer be necessary to routinely immunise recruits on entry into the SAF against rubella; the latter can be limited to those with no evidence of prior rubella immunisation.

Adult↗
PubMed1997

Doctors' fees.

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Ethics, Medical↗
PubMed1997

Smoking in the Singapore Armed Forces.

The Singapore Armed Forces has, since 1986, established a comprehensive smoking control programme which combines health education, counselling and administrative measures aimed at discouraging non-smokers from smoking, and encouraging smokers to quit the habit. The prevalence of regular smoking decreased from 28.6% in 1987 to 20.7% in 1993. The latest, 1993 survey as in past surveys covered 3,545 respondents, made up of regulars (32.0%), NSF (62.2%) and NUSAF (5.6%). The 1993 survey revealed that the majority of smokers (88.9%) in the SAF who consist primarily of 18 to 20-year-olds, had started smoking before enlistment. Most acquired the habit on their own (49.8%) or through influences outside the SAF (40.3%). Very few smokers became smokers through the influence of fellow soldiers (4.9%). The majority (87.7%) of smokers readily agreed that smoking is harmful, but this is not translated into practice. Health education efforts need to focus more on bringing about positive attitudinal and behavioural changes, rather than merely give information and advice. The young age of smoking onset (mean age of 14.3 years) In the SAF population surveyed points to the need to focus preventive efforts further upstream than hitherto emphasised.

Humans↗
PubMed1996

Studies of the choroid plexus and its associated epiplexus cells in the lateral ventricles of rats following an exposure to a single non-penetrative blast.

The choroid plexus in rats exhibited ultrastructural changes following a non-penetrative blast. The immunophenotypic features of epiplexus cells associated with the choroid plexus epithelium were also altered. In rats killed at 1 and 7 days after the blast, the intercellular spaces between the epithelial cells were greatly widened, coupled with the massive eruption and possible extrusion of the apical cytoplasm into the ventricular lumen. Associated with these changes was the passage of some monocytes/lymphocytes across the epithelium. The incidence of such a migratory phenomenon was more frequent in rats killed 7 days after the blast. In rats killed 14 days after the blast, the ultrastructural changes of the epithelial cells became less pronounced. At 21 and 28 days after the blast, the ultrastructure of the choroid plexus was comparable to that of normal specimens. The immunoreactivity of epiplexus cells in terms of their cell number and staining intensity with the monoclonal antibodies OX-42, OX-18, OX-6 and ED1 was noticeably augmented at 7 and 14 days after the blast; this, however subsided at 21 and 28 days. It is concluded that the choroid plexus is extremely sensitive to a blast wave as manifested by its structural alterations and the vigorous expression of CR3 receptors and MHC antigens by the epiplexus cells. It is suggested that a possible immune response might have been triggered in the cerebrospinal fluid ventricular system following the blast.

Animals↗
PubMed1996

Transcatheter instillation of urokinase into loculated pleural effusion: analysis of treatment effect.

OBJECTIVE: Our objective was to evaluate the usefulness of intracavitary instillation of urokinase in the treatment of loculated pleural effusion. SUBJECTS AND METHODS: We analyzed CT and sonographic scans of 31 patients with loculated pleural effusion treated with intracavitary urokinase. When the drainage was less than 100 ml/day, urokinase was instilled through the catheter until the drainage was less than 50 ml/day. Response to the treatment was assessed on follow-up chest radiographs and classified into three groups: completely effective (lung expansion > 80%), partially effective (20-80%), and ineffective (< 20%). The sonographic pattern of pleural fluid was classified as anechoic, linear septated, or honeycomb, and the thickness of the parietal pleura was measured on CT scans. RESULTS: Of the 16 patients in whom treatment was completely effective, sonography showed an anechoic appearance in 12 and a linear septated appearance in four, and the thickness of the parietal pleura on CT scans was 2 mm in six, 3 mm in seven, and 4 mm in three. Of the nine patients in whom treatment was partially effective, sonography showed an anechoic appearance in six and a linear septated appearance in three, and the thickness of the parietal pleura on CT scans was 3 mm in five and 4 mm in four. Of the six patients in whom treatment was ineffective, sonography showed a linear septated appearance in one and a honeycomb appearance in five, and the thickness of the parietal pleura on CT scans was 3 mm in one, 4 mm in two, 5 mm in one, and 6 mm in two. CONCLUSION: Urokinase instillation through a percutaneous catheter was effective in the treatment of loculated pleural effusion in most patients but was not effective in patients whose pleural fluid had a honeycomb appearance on sonography or whose parietal pleura had a thickness of more than 5 mm on CT scans.

Adolescent↗