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Biomedical subjects

R Chan

Publications and source records attributed to R Chan.

At least 91 records · Page 5Linked to original sources
PubMed1997

STD/AIDS knowledge and risk behaviour among masseuses and bar hostesses in Singapore.

Sex workers are not confined to brothels, they also include a variety of individuals who practise part-time in establishments conductive to sexual liaisons. We undertook to study the extent of sex work among masseuses and nightclub hostesses and the level of AIDS and STD knowledge in these 2 groups. The studies were conducted in 1993 and 1996. Altogether 1244 masseuses and 746 hostesses attended educational sessions at the STD clinic, during which they were also surveyed for knowledge on AIDS and STDs, and practices which may put them at risk of infection; they were also offered tests for HIV and syphilis. Knowledge on AIDS transmission was good, knowledge of other aspects of AIDS and STDs was not. Sexual activities resulting from the conduct of their work was practised by only a minority of masseuses (13.5%) and hostesses (7.9%). Among those who engaged in sexual activities at work, masseuses practised safe sex more commonly than hostesses (83.5% vs 27.6%). The prevalence of HIV (0.175% in hostesses, 0% in masseuses) and syphilis (0.87% in hostesses and 1.7% in masseuses) was very low in both groups.

Acquired Immunodeficiency Syndrome↗
PubMed1997

A knowledge, attitudes, beliefs and practices (KABP) survey on HIV infection and AIDS among doctors and dental surgeons in Singapore.

An anonymous postal questionnaire survey studying the knowledge, attitudes, beliefs and practices on human immunodeficiency virus (HIV) infection was conducted among all registered medical and dental practitioners in Singapore in 1996. In all, 1523 replies were received, yielding a response rate of 29.3%. The level of knowledge regarding transmission and prevention was generally good, although there were a number who believed that HIV could be transmitted by the respiratory and oral routes. However, knowledge regarding diagnosis and medical management was unsatisfactory. Although a large majority felt they had the ethical obligation to treat HIV patients, only half of them indicated their willingness to do so if they were given the choice. The majority (62.3%) supported the idea of routine preoperative HIV testing for patients, but fewer (40%) supported mandatory HIV testing for health care workers. Dentists seemed more sensitive to issues involving transmission in the workplace, and 95% of them practised universal precautions. Continuing medical education on HIV infection is required to improve and maintain the level of knowledge and competency of doctors and dentists in Singapore.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Sexually-transmitted diseases in Singapore--trends in the last two decades.

We review the epidemiology and trends of sexually transmitted diseases (STDs) in Singapore from 1977 to 1996. There has been a progressive decline in the incidence of bacterial STDs over the period of observation. However, viral STDs have not shown the same trends, remaining at a relatively constant level. Early detection and treatment of STDs, and health education and prevention measures targeting sex workers have been a major factor in controlling STDs. Vigilant monitoring of antibiotic resistance patterns in Neisseria gonorrhoeae has allowed timely changes to recommended treatment regimens. The advent of the human immunodeficiency virus (HIV) infection pandemic in the 1980s and public education campaigns have contributed to the success of the STDs control programme. In view of the incurable nature of many viral STDs, prevention and counselling have become a cornerstone of STD control. Surveillance and monitoring of STD trends will continue to provide important information regarding the effectiveness of existing health programmes and help us formulate new plans for the future.

Female↗
PubMed1996

Postural stability of the head in response to slowly imposed, small elastic loads.

To examine postural stability of the head, slow, undetectable rotations of small amplitude were imposed about a vertical axis while human subjects maintained a stationary body. Six normal subjects were used. The rotations were imposed through an elastic linkage, and lasted 4 s. The amplitude of head rotation was small, approximately 0.002 rad. The imposed perturbations commenced from an unloaded resting position with the head facing forward, under four conditions (1) relaxed, eyes closed; (2) relaxed, eyes open; (3) still, eyes closed; and (4) still, eyes open. The terms "relaxed' and "still' refer to the prior instructions given to the subjects regarding how they were to hold their head. There was a near linear relationship between average torque and average head angle. The effective stiffness of the head on the neck was notably low, approximately 10 Nm rad-1. Two-way analysis of variance (ANOVA) demonstrated ability to increase mean stiffness between "relaxed' and "still' conditions by 51% (P < 0.02). Visual input did not change mean stiffness significantly. Therefore, for the rotations to have been imperceptible, either the visual shifts involved must have been imperceptible, or the eyes must have counterrotated.

Adult↗
PubMed1996

Intrahepatic hepatitis C RNA levels do not correlate with degree of liver injury in patients with chronic hepatitis C.

The balance between a direct cytopathic effect by hepatitis C virus (HCV) and immune-mediated injury remains unclear. This report aims to test the following hypotheses: (1) that intrahepatic HCV load would correlate with the degree of liver injury; (2) that interferon alfa (IFN-alpha) would decrease intrahepatic HCV-RNA levels. Liver tissues (n = 56) were obtained from 47 patients with chronic HCV (9 before and after IFN-alpha therapy). Total RNA was isolated and quantitated for specific HCV RNA by dot-blot polymerase chain reaction (DB-PCR) using a standard curve created from synthetic HCV RNA of known titer to calculate actual RNA levels. A multivariate analysis was undertaken to determine the relationship of intrahepatic HCV-RNA levels with risk factors, length of HCV exposure, and histological injury scores. The confounding effect of HCV genotype was examined by direct sequencing of the NS5b region. Liver HCV RNA ranged from 10(2) to 3.1 x 10(7) molecules per microgram total liver RNA. The multiple regression analysis showed no effect of length of HCV exposure, risk factors, degree of bile duct damage, steatosis, or total Scheuer or Knodell score on RNA levels. No significant confounding effect of HCV genotype on the degree of liver injury was observed. However, genotype 1b had a significantly higher mean intrahepatic HCV-RNA load compared with the other genotypes detected. In the 9 patients who received IFN-alpha, treatment, 7 had no detectable HCV after treatment. This was associated with a significant decrease in intrahepatic HCV-RNA levels (7.57 +/- 2.53 X 10(5) to 1.82 +/- 1.80 x 10(3) molecules per microgram total liver RNA +/- SEM, n = 9, P = .0005). These results do not directly support our hypothesis that increased intrahepatic HCV load is associated with more severe liver injury. Intrahepatic viral load appears to be significantly increased in patients with genotype lb. IFN-alpha treatment does significantly lower intrahepatic HCV load.

Adult↗
PubMed1996

Laparoscopic intra-arterial catheter implantation for regional chemotherapy of liver metastasis.

In patients with unresectable metastatic disease confined to the liver, intra-arterial regional chemotherapy with implantable systems in an attractive option. Since April 1992, laparoscopic colorectal resections have been performed in our institution. Within this series of patients, three cases with bilateral liver metastasis from colon cancer were observed and underwent laparoscopic intra-arterial catheter implantation in the gastroduodenal artery for regional chemotherapy. In two patients the metastases were synchronous, and in both cases a laparoscopic colon resection was also performed, for tumors located in the cecum and in the sigmoid colon, respectively. The laparoscopic surgical technique for intra-arterial catheter implantation is described in detail. In this limited experience the procedure, from a purely technical point of view, was not considered difficult and was completed in 70 min on average. No complications were observed and the patient with metachronous liver metastasis was discharged on 3rd postoperative day.

Antineoplastic Agents↗
PubMed1996

Accuracy and efficiency of X-ray requests initiated by triage nurses in an accident and emergency department.

A study was carried out from 1 March 1995 to 31 March 1995 in the Accident & Emergency department, Pamela Youde Nethersole Eastern Hospital, Hong Kong. The aim was to assess the feasibility of requesting X-rays by triage nurses based on a pre-set protocol prior to patients being seen by a doctor. Judgement of the attending physician was used as the gold standard by which to judge the need for radiographs requested by the triage nurse. In addition, the senior medical officer or consultant would judge whether the triage nurse had applied the protocol correctly. A total of 934 patients were included in the study and 883 (94.54%) patients had X-rays requested by the triage nurse. Only 5.44% of the radiographs requested by nurses were considered to haven been unnecessary by the doctor. There was no statistically significant difference in agreement for the child and adult groups. In 917 (98%) of cases, nurses had adhered to the protocol. A saving of an average of 18.59 minutes of total service time was obtained during the study. Requesting of X-ray by triage nurse was feasible

Adult↗
PubMed1996

Tuberculosis among elderly Chinese in residential homes: tuberculin reactivity and estimated prevalence.

Objectives of this study were to determine the prevalence of positive tuberculin reactivity and associated factors among elderly nursing home residents in a population with a relatively high tuberculosis notification rate, to estimate the prevalence of active tuberculosis, and to assess tuberculin reactivity as a screening tool. A stratified, disproportional, randomized cluster sample of residents was selected and the Mantoux test (using 0.1 ml of 5 tuberculin units of purified protein derivative of tuberculin) carried out. All subjects with a positive test had a chest X-ray followed by sputum smear and culture if the X-ray was abnormal. Sputum examination was also carried out in a random sample of controls, matched for age and gender, drawn from subjects with a negative Mantoux test. Information regarding medical history, tobacco smoking habits, symptoms related to tuberculosis, and communal eating habits were gathered. Also anthropometric data were collected. Sixteen nursing homes in the catchment area of a major district hospital in Hong Kong comprising 587 residents (136 men, 451 women, mean age 80 +/- 8 years) participated in this study. The weighted prevalence of tuberculin reactivity was 43.8%. It was higher in men, among those who took their meals in a common area, in the younger age group, and in those with no previous history of hospitalization. No association was found between prevalence and duration of residence, smoking, skinfold thickness, past medical history, or any relevant symptoms. Following radiological and sputum examination, the estimated prevalence of active tuberculosis ranged from 1.2 to 2.6%. The sensitivity of the tuberculin test was 86, the specificity 30%. The prevalence of active tuberculosis in nursing homes in Hong Kong is high, but it is unclear whether cross-infection or poor health of the residents is the major contributing factor. Tuberculin skin testing does not appear to be a useful screening method in this population.

Aged↗
PubMed1996

Renal failure: why today's patients live better and longer.

The clinical courses of two older patients with progressive renal failure associated with hypertension are described. Their underlying disorders are similar, but there are stark contrasts between medical therapies available now and 50 years ago. Such advances include the development of antihypertensive drugs and antimicrobial medications that have reduced the incidence of renal failure. In addition, recombinant erythropoietin and calcitriol have decreased the morbidity associated with chronic renal failure. Finally, technologic breakthroughs in dialysis have made a once-fatal condition eminently treatable.

Acidosis↗
PubMed1995

Urocortin, a mammalian neuropeptide related to fish urotensin I and to corticotropin-releasing factor.

Corticotropin-releasing factor (CRF), a peptide first isolated from mammalian brain, is critical in the regulation of the pituitary-adrenal axis, and in complementary stress-related endocrine, autonomic and behavioural responses. Fish urotensin I and amphibian sauvagine were considered to be homologues of CRF until peptides even more closely related to CRF were identified in these same vertebrate classes. We have characterized another mammalian member of the CRF family and have localized its urotensin-like immunoreactivity to, and cloned related complementary DNAs from, a discrete rat midbrain region. The deduced protein encodes a peptide that we name urocortin, which is related to urotensin (63% sequence identity) and CRF (45% sequence identity). Synthetic urocortin evokes secretion of adrenocorticotropic hormone (ACTH) both in vitro and in vivo and binds and activates transfected type-1 CRF receptors, the subtype expressed by pituitary corticotropes. The coincidence of urotensin-like immunoreactivity with type-2 CRF receptors in brain, and our observation that urocortin is more potent than CRF at binding and activating type-2 CRF receptors, as well as at inducing c-Fos (an index of cellular activation) in regions enriched in type-2 CRF receptors, indicate that this new peptide could be an endogenous ligand for type-2 CRF receptors.

Adrenocorticotropic Hormone↗
PubMed1995

Detection of movements imposed on human hip, knee, ankle and toe joints.

1. The angular displacements necessary for 70% correct detection were determined in normal subjects at the hip, knee and ankle joints, and the interphalangeal joint of the big toe. Angular velocities between 0.1 and 50 deg s-1 were tested. The hip and knee joints were tested in slight flexion and the ankle and toe joints were tested in the mid-range of the normal excursion. The joints were carefully supported for testing and the muscles acting at the joints were relaxed. 2. When detection thresholds and velocities were assessed in terms of angular displacements and angular velocities, proprioceptive performances at the hip, knee and ankle joints were superior to that at the toe joint. 3. When detection levels and displacement velocities were expressed in terms of linear displacements and velocities at the tip of the extended toe for all four joints, instead of in angular terms, the ankle gave the best performance and the hip and knee the worst. 4. The detection level and velocity data were expressed also in terms of proportional changes in the fascicle lengths of muscles operating these joints. Analysis in these terms showed that performance was similar at the hip, knee and ankle joints, but that performance for the toe was much poorer than for the other joints. 5. These results for the hip, knee and ankle are similar to those previously measured for the elbow and distal interphlangeal joint of the finger, and are consistent with the theory that muscle fascicle length is the variable of significance to the central nervous system. However, the proprioceptive performance at the big toe is notably poorer than all other joints studied and analysed in terms of this variable.

Adult↗
PubMed1995

Oral versus intravenous antibiotics for community acquired lower respiratory tract infection in a general hospital: open, randomised controlled trial.

OBJECTIVE: To see whether there is a difference in outcome between patients treated with oral and intravenous antibiotics for lower respiratory tract infection. DESIGN: Open controlled trial in patients admitted consecutively and randomised to treatment with either oral co-amoxiclav, intravenous followed by oral co-amoxiclav, or intravenous followed by oral cephalosporins. SETTING: Large general hospital in Dublin. PATIENTS: 541 patients admitted for lower respiratory tract infection during one year. Patients represented 87% of admissions with the diagnosis and excluded those who were immunocompromised and patients with severe life threatening infection. MAIN OUTCOME MEASURES: Cure, partial cure, extended antibiotic treatment, change of antibiotic, death, and cost and duration of hospital stay. RESULTS: There were no significant differences between the groups in clinical outcome or mortality (6%). However, patients randomised to oral co-amoxiclav had a significantly shorter hospital stay than the two groups given intravenous antibiotic (median 6 v 7 and 9 days respectively). In addition, oral antibiotics were cheaper, easier to administer, and if used routinely in the 800 or so patients admitted annually would lead to savings of around 176,000 pounds a year. CONCLUSIONS: Oral antibiotics in community acquired lower respiratory tract infection are at least as efficacious as intraveous therapy. Their use reduces labour and equipment costs and may lead to earlier discharge from hospital.

Administration, Oral↗
PubMed1995

Crystal structure of the T4 regA translational regulator protein at 1.9 A resolution.

The translational regulator protein regA is encoded by the T4 bacteriophage and binds to a region of messenger RNA (mRNA) that includes the initiator codon. RegA is unusual in that it represses the translation of about 35 early T4 mRNAs but does not affect nearly 200 other mRNAs. The crystal structure of regA was determined at 1.9 A resolution; the protein was shown to have an alpha-helical core and two regions with antiparallel beta sheets. One of these beta sheets has four antiparallel strands and has some sequence homology to RNP-1 and RNP-2, which are believed to be RNA-binding motifs and are found in a number of known RNA-binding proteins. Structurally guided mutants may help to uncover the basis for this variety of RNA interaction.

Amino Acid Sequence↗
PubMed1995

Rat corticostatin R4: synthesis, disulfide bridge assignment, and in vivo activity.

We have synthesized significant amounts of the most potent member of the rat corticostatins that inhibits ACTH-induced corticosteroid and compared its structure to that of the natural hormone. The cystine bridging arrangement that corresponds to that reported for a human defensin (3-31, 5-20, 10-30) was determined. The in vitro corticostatic activity of the synthetic rat corticostatin R4 paralleled that of the natural R4. Biological studies in vivo showed that doses of 8 or 12 mg corticostatin/kg effectively interfered with corticosterone release in stressed rats. We conclude that in the assays that were used, the biological activity of the synthetic and natural molecules was identical. The availability of significant amounts of synthetic material will make possible studies investigating the physiological role played by corticostatins in modulating the activity of the hypothalamic-pituitary-adrenal axis.

Adrenal Glands↗
PubMed1995

Prevalence of hepatitis B virus (HBV) infection in Singapore men with sexually transmitted diseases and HIV infection: role of sexual transmission in a city state with intermediate HBV endemicity.

STUDY OBJECTIVES: To describe the prevalence of hepatitis B virus (HBV) infection in patients with sexually transmitted diseases (STD) and human immunodeficiency virus (HIV) infection, and to determine the role of sexual transmission of HBV infection in Singapore. DESIGN: A cross sectional study of all consecutive men presenting with a new episode of STD at a government outpatient clinic and all men with HIV infection on routine follow up at a government hospital. The prevalence of various HBV markers was compared with that of healthy males aged 15 years and above (controls). SETTING: Singapore, a city state of intermediate HBV endemicity. SUBJECTS: These comprised 497 STD patients, 47 HIV infected patients, and 418 controls. MAIN RESULTS: The overall seroprevalences of HBV infection in STD patients, HIV infected patients, and control subjects were 41.2%, 61.7%, and 33.3%, respectively (p < 0.001). The seroprevalences of hepatitis B surface antigen (6.2%, 8.5%, and 4.5%, respectively) were comparable in the three groups. Using stepwise logistic regression analysis, the adjusted seroprevalences of HBV infection in STD and HIV infected patients were respectively 2.4 times (95% confidence interval (CI), 1.7, 3.3) and 3.3 times (95% CI 1.7, 6.3) higher than in controls. HBV infection rates were higher among Chinese (odds ratio (OR), 1.9; 95% CI 1.6, 3.4) than non-Chinese, and among those aged 25-34 years (OR 2.4; 95% CI 1.6, 3.4), 35-44 years (OR 3.9; 95% CI 2.5, 5.9), and 45+ years (OR 6.2; 95% CI 3.8, 10.2) than in those aged 15-24 years. Sex related factors significantly associated with higher infection rates, independent of age and ethnic group, were reactive VDRL test (OR 2.4; 95% CI 1.2, 4.7), participation in anal intercourse (OR 2.3; 95% CI 1.2, 4.3), and having 10 or more lifetime sexual partners (OR 1.5; 95% CI, 1.0, 2.1). CONCLUSION: The importance of sexual transmission of HBV in an area of intermediate HBV endemicity was confirmed. Patients attending STD clinics should be routinely screened for HBV markers and those found to be seronegative should be strongly advised to be immunised against this virus.

Adolescent↗
PubMed1995

Evaluation of enzyme immunoassay for the detection of anogenital infections caused by Chlamydia trachomatis.

BACKGROUND--Infection caused by Chlamydia trachomatis is now recognised as the most prevalent sexually transmitted disease in many parts of the world. Anorectal infections caused by C. trachomatis is not uncommon. Enzyme-linked immunoassay (EIA) detects an antigen lipopolysaccharide (LPS) of C. trachomatis directly in clinical specimens. OBJECTIVE--Our aim was to compare an enzyme immunoassay, Wellcozyme Chlamydia (WZ04) with cell culture for the diagnosis of chlamydial infection of the anogenital tract. METHOD--Rectal swabs were taken from 100 prostitutes (80 females and 20 males) for chlamydia culture, WZ04 and direct immunofluorescence (DIF). In addition, endocervical specimens were obtained from the females for the above three tests. MAIN FINDINGS--All the positive rectal specimens were from females. Nine patients had a positive chlamydia culture from the rectum but negative WZ04 and DIF. Two patients had false positive results by WZ04 but negative culture and DIF. For cervical specimens, WZ04 identified 43% (3/7) of the culture positive cases. Specificity was 98.6%. WZ04 identified an additional specimen as positive which was also confirmed as positive by DIF. CONCLUSION--Our study shows that in our hands enzyme-linked immunoassays such as Wellcozyme Chlamydia are neither sensitive nor specific in detecting C. trachomatis infection of the rectum. For cervical infections, the sensitivity of WZ04 was 43% and the specificity 98.6% as compared to culture, with a positive predictive value of 75% and a negative predictive value of 94.7%.

Adult↗