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Biomedical subjects

M Cheang

Publications and source records attributed to M Cheang.

At least 37 records · Page 2Linked to original sources
PubMed1997

Antibody to chlamydial hsp60 predicts an increased risk for chlamydial pelvic inflammatory disease.

To determine whether serum antibody to Chlamydia trachomatis antigens alters the risk of C. trachomatis pelvic inflammatory disease (PID), 280 female sex workers were prospectively evaluated over a 33-month period for incident C. trachomatis and Neisseria gonorrhoeae cervical infection and for clinical PID. At enrollment, women were tested for antibody to C. trachomatis elementary bodies by an indirect microimmunofluorescence assay and to recombinant chlamydial hsp60 (Chsp60) by an ELISA format. At each follow-up visit, women were tested for cervical chlamydial and gonococcal infection and were identified as having clinical PID if they complained of lower abdominal pain and were found to have uterine and adnexal tenderness on pelvic examination. The data demonstrate that antibody to Chsp60 predicts a 2- to 3-fold increased risk for C. trachomatis PID.

Adolescent↗
PubMed1997

A citywide analysis of the utilization of common laboratory tests and imaging procedures in ICUs.

OBJECTIVE: To identify and discriminate between patient and institutional determinants of investigation costs in the ICU. DESIGN: Retrospective survey. SETTING: All seven hospitals in the city of Winnipeg, Manitoba, Canada. PARTICIPANTS: One hundred consecutive admissions to each of 11 ICUs. Two teaching hospitals (TH1 and TH2) each have three units (medical, surgical, and coronary care), the five community hospitals (CHs) have single combined units. TH1 operates an information-based management system. MEASUREMENTS: Each admission was categorized as MEDICAL, SURGICAL, or CARDIAC. The frequency and cost of 17 laboratory or imaging procedures were collected for each admission. Demographic data included age, length of ICU stay, APACHE II (acute physiology and chronic health evaluation) score, therapeutic intervention scoring system (TISS) data, and ICU survival. The primary diagnosis on admission and acquisition of significant problems or complications after admission were collected. RESULTS: Multivariate models revealed that length of stay, TISS score, and acquisition of a problem after ICU admission were strongly associated with increased costs in all categories (p=0.0001). Admission to TH2 was associated with greater costs in all categories (p=0.0001 MEDICAL and CARDIAC; p=0.0016 SURGICAL). Admission to a CH was associated with lower cost for SURGICAL admissions (p=0.0014), but costs at CHs were not significantly lower than at TH1 for MEDICAL (p=0.18) or CARDIAC (p=0.22) admissions. CONCLUSIONS: ICU investigation costs vary significantly between institutions and are not always linked to patient-dependent factors. Acquisition of nosocomial and iatrogenic events during ICU admission increases costs dramatically. Costs are not necessarily greater in teaching hospitals.

APACHE↗
PubMed1996

Long-term outcome of radical radiation therapy for prostatic carcinoma: 1967-1987.

PURPOSE: This study was done to review long-term results of radical radiotherapy for prostate cancer. METHODS AND MATERIALS: The records of 674 patients with Stage T1a, T1b, T2a, T2b, T3, and any T,N1,M0 disease, treated with external beam radiotherapy between January 1, 1967 and December 1987, were reviewed. These patients were treated to an average total dose of 66 Gy, with an average fractional dose of 2.05 Gy, using megavoltage. The duration of follow-up for surviving patients ranged from a minimum of 7 years to more than 20 years. RESULTS: The survival for 151 Stage T1a,T1b patients was 98.5% at 5 years, 93.6% at 10 years, and 75.2% at 15 years. Survival for 346 Stage T2a,b patients was 94.4% at 5 years, 67.9% at 10 years, and 41.5% at 15 years. Survival for 92 Stage T3 patients was 87.3% at 5 years, 54% at 10 years, and 26.6% at 15 years. The survival for 85 any T,N1,M0 patients was 73.9% at 5 years, 34.4% at 10 years, and 8.5% at 15 years. At 15 years, 75.2% of Stage T1a,b patients, 41.5% of Stage T2a,b patients, 21.7% of Stage T3 patients, and 8.5% of Stage T,N1,M0 patients remained free of local recurrence and distant metastases. The elevation of prostatic acid phosphatase prior to radiotherapy was an unfavorable prognostic factor, with impact on both loco-regional recurrences and survival. CONCLUSIONS: The external beam radiotherapy for localized carcinoma of the prostate produced a good loco-regional control, NED, and overall survival. Patients with smaller tumors and low grade fared better than the ones with more aggressive and/or bulky tumors. The weakness of this study is the absence of serial prostate-specific measurements, which were not available during the period under study. The complication rate requiring surgical intervention was low, i.e. 0.4%.

Acid Phosphatase↗
PubMed1996

Epidemiology of chronic arthritis in childhood.

This study was performed to review reports of the descriptive epidemiology of chronic arthritis in childhood and to analyze the factors that may explain differences in its reported frequency. Articles were retrieved by searching MEDLINE and EMBASE under the following index terms: juvenile rheumatoid arthritis (JRA), juvenile chronic arthritis (JCA), spondyloarthropathy, epidemiology, prevalence, and incidence. For reports published between 1977 to 1982, the Index Medicus was used. All original articles that provided prevalence or incidence rates, population size, or number of cases, were reviewed and entered into the analysis. Variables analyzed were disease prevalence and incidence. Modifier variables investigated were diagnostic criteria, source population, geographic origin of the report (Europe or North America), duration of the study, and race of the population studied. Diagnostic criteria had no effect on reported prevalence or incidence rates. Prevalence per 100,000 at risk obtained from population studies (132, 95% CI: 119, 145) was significantly higher than values derived from practitioner- (26, 95% CI: 23, 29) or clinic-based studies (12, 95% CI: 10, 15) (P = .02). North American clinic-based studies had higher prevalence values compared with European reports (32, 95% CI: 26, 38 versus 8, 95% CI: 5, 11, P = .009). None of the factors analyzed accounted for the variability in reported incidence rates. An effect of race was detected only in the distribution of patients among onset subsets. Thus, the percentage of patients with pauciarticular JRA was highest in series of North American and European caucasian patients (58, 95% CI: 56, 60) compared with series of East Indian (25, 95% CI: 20, 31), native North American Indian (26, 95% CI: 15, 37), or other races (31, 95% CI: 28, 35) (P = .001). In contrast, the percentage of patients with polyarticular JRA was lowest in the former (27, 95% CI: 25, 28) compared with the other racial groups (East Indian, 61, 95% CI: 55, 66; native North American Indian, 64, 95% CI: 53, 76; other races, 34, 95% CI: 30, 38) (P = .004). Although an effect of source population on reported prevalence was confirmed, the effect of geographic origin suggests that environmental or ethnic differences also may influence the prevalence of chronic arthritis in children. Differences in the percentages of patients with pauciarticular and polyarticular JRA may reflect racial differences in the prevalence of these conditions.

Arthritis↗
PubMed1996

The epidemiology of Chlamydia trachomatis within a sexually transmitted diseases core group.

Female sex workers in Nairobi were prospectively evaluated for risk factors of incident Chlamydia trachomatis infection. Independent risk factors included cervical ectopy (P=.007), gonococcal infection (P=.002), human immunodeficiency virus (HIV) seropositivity (P=.003), HIV seroconversion (P=.001), and duration of prostitution (P=.002). Eighteen different C. trachomatis outer membrane protein (omp1) genotypes were identified, with the allelic composition of the C. trachomatis population changing significantly over time (P=.005). Seventeen of 19 reinfections > or = 6 months apart were with different C. trachomatis omp1 genotypes. Women with HIV infection had an increased proportion of visits with C. trachomatis infection (P=.001) and an increased risk of reinfection (P=.008). Overall, the data demonstrate significant fluctuations in the genotype composition of the C. trachomatis population and a reduced rate of same-genotype reinfection consistent with the occurrence of strain-specific immunity.

Amino Acid Sequence↗
PubMed1996

Risk factors for Chlamydia trachomatis pelvic inflammatory disease among sex workers in Nairobi, Kenya.

Among 302 female sex workers in Nairobi, Kenya, who were followed for 17.6 +/- 11.1 months, 146 had one or more infections with Chlamydia trachomatis; 102 had uncomplicated cervical infection only, 23 had C. trachomatis pelvic inflammatory disease (PID), and 21 had combined C. trachomatis and Neisseria gonorrhoeae PID. As determined by multivariate logistic regression analysis, risk factors for C. trachomatis PID included repeated C. trachomatis infection (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.3-2.4; P = .0004), antibody to C. trachomatis heat-shock protein 60 (OR, 3.9; CI, 1.04-14.5; P = .04), oral contraceptive use (OR, 0.28; 95% CI, 0.08-0.99; P = .048), and number of episodes of nongonococcal nonchlamydial PID (OR, 1.7; 95% CI, 1.1-2.7; P = .02). Among human immunodeficiency virus (HIV)-seropositive women, a CD4 lymphocyte count of <400/mm3 was an additional independent risk factor for C. trachomatis PID (OR, 21.7; 95% CI, 1.2-383; P = .036); among HLA-typed women, HLA-A31 was independently associated with C. trachomatis PID (OR, 5.6; 95% CI, 1.1-29.4; P = .043). The results suggest an immune-mediated pathogenesis for C. trachomatis PID.

Adult↗
PubMed1996

The M1 gene is associated with differences in the temperature optimum of the transcriptase activity in reovirus core particles.

The reovirus core is a multienzyme complex that contains five different structural proteins and 10 segments of double-stranded RNA. The core is responsible for transcribing mRNA from the enclosed double-stranded RNA. The reovirus transcriptase has an unusual temperature profile, with optimum transcription occurring at approximately 50 degrees C and little activity occurring below 30 or above 60 degrees C. Purified reovirus serotype 1 Lang (T1L) cores transcribed most efficiently at 48 degrees C. The transcriptase temperature optimum of purified reovirus serotype 3 Dearing (T3D) cores was 52 degrees C. In addition, T1L cores produced more mRNA per particle than did T3D cores at their respective temperature optima. Core particles were purified from T1L x T3D reassortants and were used to map these differences. The M1 gene, which encodes minor core protein mu 2, was uniquely associated with the difference in temperature optimum of transcription (P = 0.0003). The L1 gene, which encodes minor core protein lambda 3 (previously implicated as the RNA polymerase), and the M1 gene were associated with the difference in absolute amounts of transcript produced (P = 0.01 and P = 0.0002, respectively). These data suggest that minor core protein mu 2 also plays a role in reovirus transcription.

Animals↗
PubMed1995

Analysis of Tcrvb8, Il4, and Ifg as genetic predisposition factors for atopic IgE response in a murine model.

Allergen-induced synthesis of lgE Abs in genetically predisposed individuals constitutes the hallmark of allergic diseases; however, the molecular basis of this genetic predisposition remains unknown. T cell cytokines lL-4 and IFN-gamma reciprocally regulate lgE synthesis and are potential genetic factors governing atopy. To examine the inheritance patterns of IgE responsiveness and address the role of these cytokines as genetic predisposition factors, in this study we established a MHC-identical mouse colony comprising crosses between two inbred strains of mouse, A.SW and SJL, respectively representing high and low IgE responder phenotypes. Segregation analysis with 149 [(A.SW x SJL)F1 x SJL] backcross and 148 [(A.SW x SJL)F1 x F1]F2 mice suggested that persistent high IgE responsiveness was inherited as a simple Mendelian dominant trait under the control of a single non-MHC, autosomal gene of major effect in these strains. Since SJL lacked Tcrvb8 genes, we examined the possibility of Tcrvb8 as a candidate gene for IgE responsiveness. The results suggested association of neither the Tcrvb8 gene nor its expression with allergen-induced IgE phenotype. Furthermore, microsatellite marker and gene sequencing analyses revealed that neither of the ll4 and lfg genes was associated with IgE phenotype. Moreover, correlation studies between IgE and cytokine levels in splenocyte cultures indicated that IgE levels were moderately to poorly correlated with IL-4 and IFN-gamma levels. It is concluded that even though expression of Tcrvb8, II4, and Ifg genes may play pivotal roles in IgE regulation, these genes per se do not contribute to genetic predisposition of allergen-induced IgE hyperresponsiveness in these strains of mice.

Animals↗
PubMed1995

Haemodynamic instability and myocardial ischaemia during carotid endarterectomy: a comparison of propofol and isoflurane.

The purpose of this study was to compare two anaesthetic protocols for haemodynamic instability (heart rate (HR) or mean arterial pressure (MAP) < 80 or > 120% of ward baseline values) measured at one-minute intervals during carotid endarterectomy (CEA). One group received propofol/alfentanil (Group Prop; n = 14) and the other isoflurane/alfentanil (Group Iso; n = 13). Periods of haemodynamic instability were correlated to episodes of myocardial ischaemia as assessed by Holter monitoring (begun the evening before surgery and ceasing the morning of the first postoperative day). In Group Prop, anaesthesia was induced with alfentanil 30 micrograms.kg-1 i.v., propofol up to 1.5 mg.kg-1 and vecuronium 0.15 mg.kg-1, and maintained with infusions of propofol at 3-12 mg.kg-1.hr-1 and alfentanil at 30 micrograms.kg-1.hr-1. In Group Iso, anaesthesia was induced with alfentanil and vecuronium as above, thiopentone up to 4 mg.kg-1 and maintained with isoflurane and alfentanil infusion. Phenylephrine was infused to support MAP at 110 +/- 10% of ward values during cross-clamp of the internal carotid artery (ICA) in both groups. Emergence hypertension and/or tachycardia was treated with labetalol, diazoxide or propranolol. Myocardial ischaemia was defined as ST-segment depression of > or = 1 mm (60 msec past the J-point) persisting for > or = one minute. For the entire anaesthetic course (induction to post-emergence), there was no difference between groups for either duration or magnitude outside the < 80 or > 120% range for HR or MAP. However, when the period of emergence from anaesthesia (reversal of neuromuscular blockade to post-extubation) was assessed, more patients were hypertensive (P = 0.004) and required vasodilator therapy in Group Iso (10/13 vs 5/14; P = 0.038 Fisher's Exact Test). The mean dose of labetalol was greater in Group Iso (P = 0.035). No patient demonstrated myocardial ischaemia during ICA cross-clamp. On emergence, 6/13 patients in Group Iso demonstrated myocardial ischaemia compared with 1/14 in Group Prop (P = 0.029). Therefore, supporting the blood pressure with phenylephrine, during the period of ICA cross-clamping, appears to be safe as we did not observe any myocardial ischaemia at this time. During emergence from anaesthesia, haemodynamic instability was associated with myocardial ischaemia. Under these specific experimental conditions, with emergence, hypertension and myocardial ischaemia were more prevalent with more frequent pharmacological interventions in patients receiving isoflurane.

Aged↗
PubMed1995

Geographic similarities between varicella and multiple sclerosis: an hypothesis on the environmental factor of multiple sclerosis.

The environmental factor causing multiple sclerosis (MS) is unknown. Kurtzke et al. (Neurology 1979; 29: 1228-1235) depicted a north to south diminishing gradient in the case/control ratios for MS among American veterans in the United States. A similar, but less precise, gradient emerged when the incidence rates of varicella from 37 states during 1978-91 were compared. A loose correlation appears to exist between the mean incidence of varicella and the MS risk ratio (n = 0.344 Spearman rank correlation coefficient, p = 0.037). Further, the data on the fat of migrants moving from a high risk MS country to a low risk country and the reverse, plus the great importance of the age at migration, raise the question of a possible connection between the two diseases. Because of these epidemiological and other similarities between the two diseases a further comparative study was suggested.

Adolescent↗
PubMed1995

Varicella zoster virus and multiple sclerosis in a Hutterite population.

There are similarities between multiple sclerosis and varicella. They are common in the same parts of the world and both are scarce in other areas. Immigration studies suggest the environmental cause of multiple sclerosis (MS) must be contracted prior to age 15 years and will usually remain dormant for years. At age 10 years varicella has occurred in greater than 95% of children living in the high-risk areas for both of these diseases. The varicella zoster virus (VZV) could be etiologically important in multiple sclerosis. The known host containment of the virus for decades with recrudescence and the variable cell-mediated immunity of the host, which can wax and wane without clinical manifestations, all lend themselves to the natural history of multiple sclerosis. A population-based study of the medical records of 5601 Hutterite Brethren was performed to determine the occurrence of multiple sclerosis, varicella, and herpes zoster. Compared to their matched non-Hutterite neighbors who acted as controls, these events were significantly less common among the Hutterites. Included in the study was an assessment of other common neurological diseases and "autoimmune" diseases among the Hutterites and the controls. There is evidence of a relationship between MS and VZV that may not be coincidental.

Adolescent↗
PubMed1994

Human immunodeficiency virus type 1 seroconversion in women with genital ulcers.

Genital ulcers are implicated as a risk factor enhancing susceptibility to human immunodeficiency virus type 1 (HIV-1) infection. A prospective study to determine the incidence of and risk factors associated with acquisition of HIV-1 in women with genital ulcers was done. HIV-1-seronegative women with genital ulcers attending a clinic for sexually transmitted diseases in Nairobi were followed to HIV-1 seroconversion over a 6-month period. Of 81 women, 10 seroconverted to HIV-1. The crude 6-month incidence of HIV-1 infection was 12%. Risk factors associated with seroconversion included cervical ectopy (rate ratio [RR], 4.9; 95% confidence interval [CI], 1.5-15.6) and pelvic inflammatory disease (RR, 6.3; 95% CI, 1.9-20.4). Thus, cervical ectopy and pelvic inflammatory disease may increase susceptibility to HIV-1 in women with genital ulcers.

Adolescent↗
PubMed1994

De Clerambault syndrome and medical practitioners: medico legal implications.

De Clerambault's syndrome or erotomania is a condition in which a patient, usually a woman, develops a delusional belief that a man, usually older and of higher social status, is in love with her. This paper describes such cases where medical practitioners were involved. In a case where a doctor was brought to court, the judge stressed that because of the nature of the allegation, it was vital that there be corroborative evidence. When faced with such patients, a prudent doctor would ensure that a nurse be in attendance at all times, that notes be carefully kept and phone calls recorded. Other measures might be necessary, depending on the situation.

Delusions↗
PubMed1994

Influenza immunization: knowledge, attitude and behaviour of health care workers.

Knowledge, attitude and behaviour regarding influenza immunization were evaluated in 519 health care workers (HCWs) from high risk hospital areas because of this target group's historically poor acceptance rates. The results of this self-administered questionnaire survey indicated that HCWs' knowledge regarding influenza and influenza vaccine was generally satisfactory. However, only approximately one half of the HCWs knew who should receive influenza vaccine and why it is important. HCWs with good knowledge of influenza and the influenza vaccine were more likely to recommend vaccine to their patients and to their co-workers/family, but were not more likely to receive it themselves. Experiencing post-vaccine symptoms for more than one day significantly reduced the willingness of HCWs to accept and to recommend vaccine. HCWs who heard about influenza vaccine from their doctors indicated significantly more willingness to receive vaccine and to recommend vaccine to co-workers and family. Questionnaire survey of willingness to accept influenza vaccine overestimated actual acceptance, as only 35.7% of the HCWs who had positive views regarding the influenza vaccine actually received the vaccine during the following influenza season. While knowledge about the vaccine, previous experience with perceived adverse symptoms and promotion by family doctor significantly influenced questionnaire responses, hearing about the vaccine from the occupational health department, being on a geriatric ward or being a unit assistant were the most significant factors in actually being vaccinated. Thus, occupational health departments must continue their efforts to promote the influenza vaccine actively and to make it as accessible as possible.

Adolescent↗