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Biomedical subjects

C B Lim

Publications and source records attributed to C B Lim.

16 recordsLinked to original sources
PubMed2003

A new formulation of nasal fentanyl spray for postoperative analgesia: a pilot study.

Twenty-four gynaecological patients receiving postoperative patient-controlled analgesia were enrolled in an open cross-over pilot study evaluating two new formulations of nasal fentanyl spray. The primary outcome was the bioavailability of nasal fentanyl in comparison with intravenous fentanyl. This manuscript describes the clinical outcomes of quality of postoperative analgesia and patient acceptability. There were 21 complete data sets for both sequences of the cross-over design. In randomised order, patients received approximately 50 microg of fentanyl in a single dose by intranasal and intravenous administration, but separated by at least 2 h. Analgesia was of rapid onset (within 5 min) and similar quality. There was no significant difference in side-effects. Four patients experienced mild nasal stinging and although 10 (42%) preferred intravenous administration, seven (29%) preferred intranasal and six (25%) had no preference. We conclude that these formulations of fentanyl, delivered as nasal spray, have potential clinical utility.

Administration, Intranasal↗
PubMed2003

Morbidity in Alagille syndrome in 6 Malaysian children.

We retrospectively studied the records of 6 Malaysian children who were diagnosed with Alagille Syndrome (AGS) according to this criteria from January 1999 to January 2001, at the Institute of Paediatrics, Kuala Lumpur Hospital. Four patients (66%) had a positive family history. Thirteen individuals (6 patients and 7 relatives) were diagnosed with AGS in these 5 families. Only 6/13 (46%) of them presented with liver involvement. All 6 patients presented with typical facies and cholestasis (100%). Three (50%) presented with portal hypertension (PHT) with synthetic liver dysfunction (1 died), 1/6 (17%) have PHT and normal synthetic liver function. Two have cleared their jaundice but have biochemical evidence of hepatitis and hepatomegaly, four have congenital heart disease 5/6 posterior embryotoxon, 2/6 butterfly vertebrae, 4/6 hyperlipidaemia and 4/6 failure to thrive. One patient has a Jagged-1 gene disruption at the translocation breakpoint locus 20p12.3 2n = 46,XX,t(12.20) (q22, p12.3). 5/6 (83%) are still alive. Two-thirds of our patients developed chronic liver disease by 3 years of age. Two-thirds of the index patients have a family history. Only 46% of individuals in these families have clinical evidence of liver involvement. Mortality depends on cardiac/renal disease, end-stage liver failure and intercurrent infection.

Alagille Syndrome↗
PubMed2001

Development of multipurpose laboratory XIEES spectrometer and its application to surface XAFS analysis of Al2O3 films.

A new laboratory spectrometer for X-ray Induced Electron Emission Spectroscopy (XIEES) has been developed. This spectrometer is suitable for measurements of X-ray Absorption Fine Structure (XAFS) spectrum in surface sensitive fluorescence and electron emission detection modes as well as in standard transmission mode. It is the advantage of this spectrometer that a wide range of x-ray energy scanning between 0.48 and 41 keV is available. At the Cu K-edge, a energy resolution of about 2 eV has been achieved. The spectrometer has been used to analyze the Al2O3 (40 A and 500 A)/Si(100) with total electron yield measurement.

Journal Article↗
PubMed2001

The sleeper Bostrichthys sinensis (family Eleotridae) stores glutamine and reduces ammonia production during aerial exposure.

Bostrichthys sinensis inhabits brackish water, living in the crevices of the river mouths of Shang Xi and Guangdong, China. In its natural habitat, it may encounter aerial exposure frequently during low tides, and it usually remains quiescent in the absence of water. Upon aerial exposure in the laboratory, the ammonia excretion rate decreased to one-fourth that of the submerged control. Although all the enzymes of the ornithine-urea cycle were detected in the liver of this fish, the activity of hepatic carbamoyl phosphate synthetase was too low for the cycle to be functioning. Indeed, ammonia accumulated in the tissues and was not converted to urea. Results indicate that ammonia produced through amino acid catabolism was detoxified to glutamine during the first 24 h of aerial exposure. The excess amount of glutamine stored in the muscle during this period couldaccount approximately for the reduction in ammonia equivalent excreted. There was indeed a significant increase in the activity of glutamine synthetase from the liver of specimens exposed to terrestrial conditions. In contrast to the production of alanine, formation of glutamine is energetically expensive. Since B. sinensis remained relatively inactive on land, the reduction in energy demand for muscular activity might provide it with the opportunity to exploit glutamine formation as a means to detoxify ammonia. After 72 h of aerial exposure, B. sinensis reduced internal ammonia production, possibly through reductions in proteolysis and amino acid catabolism, to avoid excessive accumulation of ammonia.

Adaptation, Physiological↗
PubMed2001

Reduction in the rates of protein and amino acid catabolism to slow down the accumulation of endogenous ammonia: a strategy potentially adopted by mudskippers (Periophthalmodon schlosseri snd Boleophthalmus boddaerti) during aerial exposure in constant darkness.

This study was designed to elucidate the strategies adopted by mudskippers to handle endogenous ammonia during aerial exposure in constant darkness. Under these conditions, specimens exhibited minimal locomotory activity, and the ammonia and urea excretion rates in both Periophthalmodon schlosseri and Boleophthalmus boddaerti decreased significantly. As a consequence, ammonia accumulation occurred in the tissues of both species of mudskipper. A significant increase in urea levels was found in the liver of P. schlosseri after 24h of aerial exposure, but no similar increase was seen in the tissues of B. boddaerti. It is unlikely that these two species of mudskipper detoxified ammonia to urea during aerial exposure since B. boddaerti does not possess a complete ornithine-urea cycle (OUC) and, although all the OUC enzymes were present in P. schlosseri, the activity of carbamoyl phosphate synthetase present in the liver mitochondria was too low to render the OUC functional for ammonia detoxification. Peritoneal injection of 15NH4Cl into P. schlosseri showed that this mudskipper was capable of incorporating some of the labelled ammonia into urea in its liver. However, aerial exposure did not affect this capability and did not induce detoxification of the accumulated ammonia to urea. Mudskippers exposed to terrestrial conditions and constant darkness did, however, show significant decreases in the total free amino acid content in the liver and blood, in the case of P. schlosseri and in the muscle of B. boddaerti. No changes in the alanine or glutamine content of the muscle were found in either species. Analyses of the balance between the reduction in nitrogenous excretion and the increase in nitrogenous accumulation further revealed that these two species of mudskipper were capable of reducing their protein and amino acid catabolic rates. Such adaptations constitute the most efficient way to avoid the build-up of internal ammonia, and would render unnecessary the detoxification of ammonia through energetically expensive pathways. This finding may be the first report of a teleost fish showing a reduction in proteolysis and amino acid catabolism in response to aerial exposure.

Air↗
PubMed2001

Helicobacter pylori: prevalence, clinical and endoscopic findings in children who underwnet upper endoscopy for abdominal ailments.

A total of 97 children aged 1 month to 16 years (mean 6.6 years) had upper endoscopies performed in Paediatric Institute, Kuala Lumpur Hospital between January 1997 and December 1999 for various gastrointestinal symptoms. Of these 70 children were tested for Helicobacter pylori. The four most common indications for upper endoscopy were recurrent abdominal pain, upper gastrointestinal bleeding, epigastric pain and vomiting. The overall prevalence of this infection in this heterogenous group of symptomatic children was 10% (7/70). This study shows that H.pylori positivity in a routine endoscopy population is low and does not appear to be associated with specific symptoms.

Abdomen↗
PubMed1999

Disseminated histoplasmosis in a non-immunocompromised child.

We describe a 2 year-old non-immunocompromised girl with disseminated histoplasmosis who presented with a 2-month history of fever and bloody diarrhoea. On presentation, she was severely wasted and anaemic. There were gross hepatosplenomegaly and multiple lymphadenopathy. A septic screen was negative. A subsequent stool culture isolated Salmonella enteriditis. Serial Widal-Weil Felix (WWF) titres showed serological response after 2 weeks of Ceftriaxone. However, she continued to have spiking fever, bloody diarrhoea and weight loss. She developed pancytopaenia and disseminated intravascular coagulation. A bone marrow aspirate and trephine, and lymph node biopsy showed the presence of Histoplasma capsulatum, confirmed by Gomori-Methenamine Silver staining. She responded to intravenous amphotericin B followed by fluconazole (intravenous then oral) for 6 months after discharge. Human Immunodeficiency Virus screening tests were negative. Complement and immunoglobulin levels were normal. T and B enumeration tests showed gross leucopaenia with very low T cell function with defective phagocytic function. A repeat T and B cell enumeration test and phagocytic function tests done 3 months later were normal.

Amphotericin B↗
PubMed1998

Cyanide exposure affects the production and excretion of ammonia by the mudskipper Boleophthalmus boddaerti.

The concentrations of ammonia in the plasma of the mudskipper Boleophthalmus boddaerti exposed to cyanide for 1-6 days were significantly greater than the respective values of the controls. This was due to an increase in the production of NH3 in the muscle and an increase in the retention of NH3 and/or NH4+ in the blood of the cyanide-exposed fish when compared to controls. Cyanide exposure significantly increased the specific activity of muscle AMP deaminase. Since adenylosuccinate synthetase and lyase were also present in the muscle, exposure to cyanide might increase the production of NH3 from the catabolism of purine nucleotides. B. boddaerti exposed to cyanide excreted significantly less ammonia than the control fish. Results indicate changes in the permeability of the epithelial surfaces of the cyanide-exposed fish to NH3 and/or NH4+. Since the tissues and organs needed time to activate the inducible cyanide detoxification mechanisms, the increase in the production of NH3 might be an important defensive mechanism for B. boddaerti during the early phase of cyanide exposure.

AMP Deaminase↗
PubMed1995

Truncation artifact reduction in transmission CT for improved SPECT attenuation compensation.

Transmission computed tomography (TCT) has been shown to be an accurate method of acquiring non-uniform attenuation maps for single-photon emission computed tomography (SPECT) attenuation compensation. One commonly encountered problem, especially for convergent beam geometries, is image truncation. We describe two methods for reducing associated truncation artifacts, with the goal of improving SPECT attenuation compensation without unduly increasing imaging or reconstruction times: (i) the two-scan method, which reduces the degree of truncation by combining two short-duration, patient-shifted scans, and (ii) a quantitative extrapolation method, which fills in truncated projections accounting for the correct amount of attenuating medium in the slice. The methods are evaluated by imaging two phantoms on a fan beam TCT system. Projection sets are truncated to various degrees with software, and reconstructed images are compared to both untruncated filtered backprojection and iterative reconstructions of truncated data. A fundamental analysis of SPECT attenuation factors is performed, and attenuation compensation of a cardiac insert is analysed. Results indicate the two-scan method can effectively reduce the degree of truncation in many cases, and the quantitative extrapolation method greatly improves SPECT attenuation compensation over using truncated maps.

Artifacts↗
PubMed1994

Significance of autoimmune haemolytic anaemia and immune thrombocytopenia (Evans' syndrome) in systemic lupus erythematosus.

Patients with systemic lupus erythematosus (SLE) have an extremely variable prognosis and mortality. The purpose of this report is to highlight the importance of looking for lupus parameters in patients with autoimmune haemolytic anaemia (AIHA) and/or immune thrombocytopenia (ITP) as this represents a subgroup of systemic lupus erythematosus (SLE) patients with a fairly good prognosis. We report a case of an 8-year-old Malay boy who was admitted to hospital with fever and gum bleeding. Physical examination revealed a malar rash, oral ulcers, petechial haemorrhages and bruises over the limbs, generalised lymphadenopathy and hepatosplenomegaly. Laboratory investigations confirmed the diagnosis of SLE. The patient's serum showing the presence of antinuclear factor, antiphospholipid antibodies and a biological false-positive test for syphilis. Immunological and haematological parameters were in keeping with combined AIHA and ITP (Evans' syndrome). No organ involvement was present and the patient responded well to corticosteroid therapy. This case demonstrates the importance of making an early diagnosis of SLE with haematological complications, in order to ensure full benefit of therapy and emphasises the good prognosis expected in this subgroup of SLE patients.

Anemia, Hemolytic, Autoimmune↗
PubMed1983

SPECT resolution and uniformity improvements by noncircular orbit.

A noncircular orbit implemented by a combination of rotational and translational motions in single photon emission computed tomography improves significantly the image resolution and uniformity. The former is realized by closer access of the detector to the object at each projection angle, and the latter by suppression of ring artifacts through the shifts in the distance between the centers of detector and object. This has been demonstrated by comparing the SPECT images for an elliptical orbit of 40 cm X 30 cm with the equivalent circular orbit of 40 cm diameter, performed by SPECT system with a high resolution collimator. Resolution FWHM improvements were 1.5-2.5 mm. Lesion contrast improved by a factor of 2.8 for a nonradioactive rod of 6 mm diam. In phantom images, the elliptical orbit showed better definition of lesion shape, sharper edge response, and clearly increased detectability. Translational motion reduced ring artifacts, particularly near the image center.

Models, Structural↗
PubMed1982

Lesion detection with single-photon emission computed tomography (SPECT) compared with conventional imaging.

We have evaluated analytically and experimentally the effectiveness of both conventional nuclear medicine imaging and single-photon emission computed tomography (SPECT) imaging to detect small photon-deficient areas (approximately the size of the system's resolution) with a relatively uniform background. The experimental model is based on the Tc-99m sulfur colloid study of the liver. The experimental data were obtained from a liver phantom containing two small photon deficient areas, nominally 1 and 1.5 cm in diameter. The liver phantom was placed in a water-filled Alderson body phantom and scanned with the cold defects located both centrally and peripherally. Lesion image contrast for both conventional and SPECT imaging is proportional to the lesion uptake ratio and is degraded by the system's finite spatial resolution and Compton-scattered photons. However, for conventional imaging the contrast is significantly degraded by the effect of radionuclide superposition (as modified by attenuation), while for SPECT imaging the contrast is essentially independent of these effects. This results in a significant increase in lesion-to-background contrast with SPECT as compared with conventional imaging. The measured SPECT image contrasts for the 1- and 1.5-cm areas of low uptake averaged more than five times the measured image contrasts for the conventional system.

Liver↗
PubMed1978

Performance evaluations of recent wide field scintillation gamma cameras.

Performance characteristics of four recent wide field scintillation gamma cameras were evaluated for 140-keV gamma imaging. Parameters measured included intrinsic spatial resolution, energy resolution, uniformity and linearity distortion, and count-rate capability and its influence on the spatial resolution. The system performance of the cameras was compared with representative parallel-channel collimators in terms of spatial resolution and relative sensitivity. Visual imaging comparisons of each camera system were performed by taking images of Rollo phantom containing four different lesion sizes, with four different contrast ratios, for equal imaging time.

Evaluation Studies as Topic↗
PubMed1977

Comparison of Ga-67 citrate images obtained with rectilinear scanner and large-field Anger camera.

Two methods for Ga-67 citrate imaging were compared on 20 patients. Scans were performed using approximately equal procedure time with two instruments: (A) a dual 5-in. rectilinear scanner with medium-energy collimator, with a single window spanning both the 93-keV and the 185-keV spectral peaks; and (B) a large-field (15-in. diam) Anger camera equipped with moving table, medium-energy collimator, and three windows covering the 93-keV, 185-keV, and 300-keV peaks separately. Sixteen abnormal sites and 24 normal sites were selected for comparison. Each site was evaluated by four physicians experienced in interpreting Ga-67 citrate images. The observers performed significantly better using the images obtained with the large-field camera (three windows) than with the dual 5-in. scanner (single window).

Citrates↗