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Biomedical subjects

A Chua

Publications and source records attributed to A Chua.

At least 19 recordsLinked to original sources
PubMed2001

A window on the current status of diabetes mellitus in Singapore--the Diabcare-Singapore 1998 study.

The Diabcare-Singapore project was carried out in 22 clinics (general hospitals, GH and primary healthcare centres, PHC) to provide an overview of diabetes management and metabolic control status. Data from 1697 diabetic patients were collected on paper forms and analysed centrally. Type 2 diabetes mellitus patients constituted 91.4% and type I patients constituted 8.1% of population. The proportion of type I patients was greater in GH (18.1%) vs PHC (3.4%). The mean age (+/- SD) was 58.1 +/- 14.4 years and mean duration of diabetes was 10.1 +/- 7.5 years. Mean body mass index (BMI) was 25.1 +/- 4.4 kg/m2 and more than half (53%) of patients were overweight (BMI >25 kg/m2). Mean HbA1c and FBG levels were 8.0 (1.9% and 9.1 +/- 3.1 mmol/l. A total of 51% of patients had HbA1c (1% above the Upper Limits of Normal (ULN). Fasting blood glucose (FBG) was >7.8 mmol/l in 61% of patients. The majority (70%) had satisfactory levels of fasting lipids (triglycerides, total cholesterol and HDL-cholesterol). Only 19.7% practised home blood glucose self-monitoring, while 99% reported receiving some diabetes education. Sixteen percent of patients had abnormal levels of protein (>500 mg/24 h) in the urine, 3% had elevated serum creatinine levels and 36% had microalbuminuria. Retinopathy (12%), cataract (16%) and neuropathy (12%) were commonly reported diabetic complications. The data revealed suboptimal glycaemic control in about half of patients studied.

Adolescent↗
PubMed2001

The status of diabetes mellitus in primary care institution and restructured hospitals in Singapore.

The Diabcare-Asia Singapore 1998 project was carried out using data from 22 centres collected on paper forms to provide an overview of diabetes management and metabolic control status in 1697 diabetic patients from both primary health care clinic (PHC) (67%) and restructured hospital (RH) (33%) settings. PHC patients were on average older than RH patients (61.3 +/- 11.2 years vs 51.5 +/- 17.7 years), and had a shorter duration of diagnosed diabetes (9.2 +/- 6.8 years vs 12.0 +/- 8.5 years). The mean body mass index (BMI) for PHC patients was 25.5 +/- 4.4 kg/m2 vs 24.5 +/- 4.2 kg/m2 for RH patients. Proportionately more PHC than RH patients were overweight (BMI >25 kg/m2) (49% vs 42%). Patients with type I diabetes constituted 3.5% of PHC vs 18.1% of the RH cohort. HbA1c information was available for 92.5% of RH vs 69% of PHC patients. HbA1c measurements were <1% above ULN in 50% of PHC vs 37% of RH patients, while FBG was >7.8 mmol/l in >61% of all patients. Proteinuria (>500 mg/24 hrs) was reported in 13% of PHC vs 26% of RH patients tested. Microalbuminuria (20-300 mg/l) was noted in 36% of 171 RH patients tested. Oral hypoglycaemic agents were used as sole therapy in 83.5% of PHC vs 43% of RH patients. Eye, feet, renal and severe late complications were more commonly reported by RH than PHC patients. There is a variation in the patient profiles and care between PHC and RH patients.

Diabetes Complications↗
PubMed2000

Central Nervous System Toxoplasmosis in HIV Pathogenesis, Diagnosis, and Therapy.

In patients with HIV, Toxoplasma gondii is the most frequent infectious cause of focal brain lesions. Particularly in advanced HIV disease, it can cause significant morbidity and mortality. Current clinical practice involves empiric therapy with pyrimethamine and sulfadiazine, upon a presumptive diagnosis of toxoplasmic encephalitis, based on serologic, clinical, and radiological features. This approach continues to evolve, as new diagnostic strategies, such as the use of immunoglobulin G antibody titers and polymerase chain reaction, prophylaxis against opportunistic infections, and highly active antiretroviral therapy--HAART--come into play. Primary and secondary prophylaxis are the mainstay of treatment. There remains a continuing need for development of new anti-Toxoplasma therapy.

Journal Article↗
PubMed1998

Survival of Helicobacter pylori in milk and tap water.

The survival capacity of Helicobacter pylori in artificially contaminated milk and tap water was investigated in the study. Helicobacter pylori could survive for up to 10 days in milk at 4 degrees C storage but only 4 days in tap water with a steady decrease of colony forming units. However, electron microscopy clearly showed that the non-culturable coccoid form was present in tap water which had been kept at 4 degrees C for 7 days. It is concluded that H. pylori may survive in tap water as well as in milk, with the implication that they may, thereby, act as a vehicle of transmission.

Animals↗
PubMed1995

Molecular analysis of Helicobacter pylori populations in antral biopsies from individual patients using randomly amplified polymorphic DNA (RAPD) fingerprinting.

In the present study, randomly amplified polymorphic DNA (RAPD) fingerprinting has been used to analyse multiple single colony isolates of Helicobacter pylori from antral biopsies in an attempt to ascertain whether or not multiple strains are present in individual patients using single biopsy samples. The RAPD fingerprints derived from single colonies obtained from the same biopsy specimen were in all cases indistinguishable. The previously noted heterogeneity between H. pylori strains from different individuals was confirmed. RAPD fingerprinting, combined with a simple method of template preparation, was shown to be an excellent method for H. pylori strain differentiation. The results of this study indicate that the H. pylori population is homogeneous in individual patients at a single gastric site.

Bacterial Typing Techniques↗
PubMed1995

Increased gastric production of interleukin-8 and tumour necrosis factor in patients with Helicobacter pylori infection.

AIMS: To investigate the role of interleukin-8 (IL-8) and tumour necrosis factor (TNF) in patients infected with Helicobacter pylori. METHODS: The study population comprised 52 patients with dyspepsia attending for upper gastrointestinal endoscopy. Of these patients, 35 were infected with H pylori. IL-8 and TNF concentrations in plasma, gastric juice, and gastric biopsy homogenate supernatant fluid were measured by radioimmunoassay and L929 cell bioassay, respectively. RESULTS: The concentrations of IL-8 and TNF in gastric juice and gastric biopsy homogenates were substantially greater in patients infected with H pylori. In H pylori positive patients IL-8 concentrations in gastric juice and gastric biopsy homogenates were higher in those with moderate gastritis than in those with mild gastritis. There was a positive correlation between IL-8 and TNF concentrations in gastric juice and gastric biopsy homogenate supernatant fluid from H pylori positive patients. There were no significant differences between H pylori positive and negative patients with respect to IL-8 and TNF plasma concentrations. CONCLUSION: This study suggests that increased gastric production of IL-8 and TNF may be implicated in the pathogenesis of H pylori associated gastroduodenal disease.

Adult↗
PubMed1995

Helicobacter pylori-induced lipid peroxidation in peripheral blood lymphocytes.

Several lines of evidence implicate Helicobacter pylori infection in the pathogenesis of gastritis and peptic ulceration. To investigate whether H. pylori can cause lipid peroxidation in lymphocytes in vitro and to look for experimental evidence of lipid peroxidation induced by H. pylori, the lipid peroxide (LPO) level in peripheral blood lymphocytes was measured using the thiobarbituric acid fluorescence method. In the absence of added H. pylori, the LPO level in lymphocytes was 0.133 +/- 0.033 nmol/10(6) cells, and in the co-culture of H. pylori with peripheral blood mononuclear cells 0.340 +/- 0.097 nmol/10(6) cells. A significant difference was found between the two groups (p < 0.001). Antioxidants, either superoxide dismutase or catalase, could inhibit LPO production in lymphocytes. The present data provide further evidence that H. pylori can induce lipid peroxidation, which may be responsible for the pathogenesis of H. pylori-associated mucosal damage.

Catalase↗
PubMed1994

Gastric T lymphocyte responses to Helicobacter pylori in patients with H pylori colonisation.

Helicobacter pylori has been identified as a dominant factor in the pathogenesis of duodenal ulcer. The aim of this study was to examine peripheral blood and gastric lymphocyte proliferation and cytokine production in patients with H pylori colonisation. Sixty five dyspeptic patients attending for endoscopy were studied; 35 of these were H pylori positive and 30 H pylori negative as assessed by culture, histology, and rapid urease test. H pylori antigen was capable of stimulating peripheral blood lymphocyte proliferative responses even in H pylori negative patients. Peripheral blood lymphocyte proliferative responses to H pylori (but not to purified protein derivative or phythaemagglutinin) were significantly lower in H pylori positive than H pylori negative patients. Similarly, antigen specific proliferative responses and interferon gamma production by gastric lamina propria lymphocytes were also depressed in H pylori positive patients compared with H pylori negative patients. CD8 and CD22 positive lamina propria lymphocytes were increased in H pylori positive patients. These data show that antigen specific responses to H pylori are significantly lower in H pylori positive patients and could indicate activation of antigen specific suppression.

Adolescent↗
PubMed1993

Interferon-gamma and tumour necrosis factor production in patients with Helicobacter pylori infection.

The production of the cytokines, interferon-gamma and tumour necrosis factor by human antral mucosa cells and stimulated peripheral blood mononuclear cells were determined by enzyme linked immunosorbent assay and L929 bioassay respectively. Tumour necrosis factor production by peripheral blood mononuclear cells in response to Helicobacter pylori stimulation was depressed in Helicobacter pylori positive individuals, compared to Helicobacter pylori negative individuals (P < 0.05). There was no difference in tumour necrosis factor production by peripheral blood mononuclear cells in response to purified protein derivative. However, tumour necrosis factor production by cells isolated from gastric mucosa during short term culture was significantly higher in Helicobacter pylori positive patients (P < 0.05) than negative patients, indicating a probable macrophage response. Levels of interferon-gamma did not differ significantly in the gastric explant culture from the two groups. The results show that Helicobacter pylori negative patients have a stronger peripheral cellular immune response to Helicobacter pylori infection. The higher levels of tumour necrosis factor production by antral mucosa cells in Helicobacter pylori positive patients may reflect the infiltration of T lymphocytes and macrophages within the local mucosa.

Adult↗
PubMed1993

Non-surgical approaches to stones in the biliary tree.

Medical treatment of cholesterol gall stones aims to dissolve the stones leaving the biliary tract stone-free and the gall bladder in situ. The introduction of extracorporeal shock wave lithotripsy and contact solvent therapy with methyl tert butyl ether have revolutionised the medical management of both gall bladder stones and bile duct stones which are too large to be treated by sphincterotomy. Both approaches represent a major advance over cheno- and ursodeoxycholic acid which are effective in less than 30% of cases and require prolonged therapy. All medical treatments require a functioning gall bladder and suffer from relapse rates in the order of 10% per annum. Secondary prophylaxis is expensive and the rate of compliance and long term safety have yet to be established.

Bile Acids and Salts↗
PubMed1992

Central serotonin receptors and delayed gastric emptying in non-ulcer dyspepsia.

OBJECTIVE: To determine whether central serotonin receptors are involved in the pathophysiology of non-ulcer dyspepsia. DESIGN: Between subjects study of solid phase gastric emptying and prolactin response to buspirone challenge. SUBJECTS: 12 patients fulfilling criteria for non-ulcer dyspepsia and 12 age and sex matched controls. MAIN OUTCOME MEASURES: Solid phase gastric emptying measured by scintigraphic assessment of the movement of a standard meal labelled with technetium-99m and indium-111; responsiveness of central serotonin 1A receptors measured by the prolactin release following challenge with oral buspirone 60 mg. RESULTS: Solid phase gastric emptying was significantly delayed in the patients with non-ulcer dyspepsia (t 1/2 = 90.6 (SD 14.5) minutes in patients and 54.6 (10.7) minutes in controls; 95% confidence interval 24.7 to 46.7 minutes, p < 0.001). Prolactin release was significantly greater in patients compared with controls (1272.7 (1039.9) mU/l v 292.9 (136.1) mU/l; 352.1 to 1607.5 mU/l, p < 0.01). Gastric emptying and prolactin release were significantly correlated (r = 0.59, p = 0.04) in the patients but not in the controls (r = 0.23). CONCLUSION: Central serotonin 1A receptors may have a role in the pathophysiology of non-ulcer dyspepsia of the dysmotility subtype.

Adult↗
PubMed1991

A comparison of the mental status, personality profiles and life events of patients with irritable bowel syndrome and peptic ulcer disease.

Forty patients with a diagnosis of irritable bowel syndrome (IBS) and 32 patients with peptic ulcer disease underwent a full psychiatric assessment. All were rated using the Gastrointestinal Symptom Rating Scale (GSRS), the Comprehensive Psychopathological Rating Scale, the Life Experiences Survey and the Eysenck Personality Inventory. The 2 groups were not distinguishable on total GSRS scores or rates of DSM-III diagnosed mental disorder. However, greater trait scores for neuroticism and introversion were found in the IBS group, together with a greater reporting of life events perceived as negative.

Adult↗
PubMed1991

Dissolution of cholesterol gall stones using methyltertbutyl ether: a safe effective treatment.

Methyltertbutyl ether (MTBE) administered by percutaneous transhepatic catheter rapidly dissolves radiolucent cholesterol gall bladder stones. However, complete dissolution and clearance of non-cholesterol debris is essential to prevent recurrence. In this study we analysed 25 consecutive patients with reference to efficacy and recurrence based on the presence or absence of non-cholesterol stone fragments after dissolution. Placement of the catheter was successful in 24 patients, one patient requiring cholecystectomy for bile peritonitis. MTBE was infused and aspirated continuously, four to six cycles per minute, resulting in rapid stone dissolution (median six hours; range 4-23 hours for solitary stones and median seven hours, range 4-30 hours for multiple stones). In 18 patients who had complete dissolution, four (22%) had recurrent stones within six to 18 months. Five patients had residual debris which failed to clear completely despite bile acid treatment. One patient with an incomplete rim of calcium in a large stone did not respond to MTBE treatment. A further patient required cholecystectomy for symptomatic recurrence. There were no serious side effects observed. MTBE treatment is a rapid, safe, and effective treatment for patients who refuse surgery or who for medical reasons cannot undergo cholecystectomy. The results of this study confirm that complete dissolution of all fragments is essential and may prevent recurrence.

Adult↗
PubMed1990

Assessment of central noradrenergic functioning in irritable bowel syndrome using a neuroendocrine challenge test.

Desipramine, the monoamine reuptake inhibitor, acts predominantly on noradrenergic neurones, and via alpha-2 receptors brings about the release of growth hormone in normal healthy subjects. Thirteen patients with a diagnosis of irritable bowel syndrome, 10 normal controls and eight patients with peptic ulcer disease were each given a challenge test of desipramine 1 mg/kg body weight. Growth hormone release over a 3 h period was monitored. A blunted response was defined as a failure of growth hormone levels to rise at least 5 mU/l above baseline. Of the 13 patients with irritable bowel syndrome 11 showed such a blunting. The results suggest abnormal central alpha-2 receptor functioning in irritable bowel syndrome.

Adult↗
PubMed1990

Ultrasound as part of a 1-day gastroenterology clinic: advantages and problems.

Ultrasound was introduced into a 1-day gastroenterology clinic so that clinical assessment, endoscopy and ultrasound could be performed as appropriate in a single hospital visit. The findings in 602 patients are reported. A total of 256 (43%) patients underwent ultrasound, 35% of which showed positive findings including cholelithiasis in 12% and tumours in 7%. This system of referral for ultrasound is very convenient for patients and their general practitioner and is less costly than traditional referral methods. It is, however, time-consuming for the radiologist.

Adolescent↗
PubMed1990

Serotonin supersensitivity: the pathophysiologic basis of non-ulcer dyspepsia? A preliminary report of buspirone/prolactin responses.

Buspirone stimulates central 5-hydroxytryptamine (5HT) receptors and brings about the release of prolactin, and there is evidence to suggest that the extent of prolactin release after a challenge with buspirone is an indicator of the sensitivity of central 5HT receptors. Seventeen patients with a diagnosis of non-ulcer dyspepsia, eight normal healthy volunteers, and six patients with peptic ulcer disease were each given a challenge test of 60 mg buspirone orally, and prolactin release over a 3-h period was monitored. The mean prolactin response was significantly greater in patients with non-ulcer dyspepsia than in healthy controls and peptic ulcer disease patients. The results suggest that central 5HT receptors may be supersensitive in non-ulcer dyspepsia.

Buspirone↗