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Biomedical subjects

C Chow

Publications and source records attributed to C Chow.

At least 55 records · Page 3Linked to original sources
PubMed1995

Differences in diaphragm fiber types in SIDS infants.

The diaphragm is a vital respiratory muscle in the sleeping infant. Any changes in diaphragm fiber type number or size could represent either a primary developmental delay or a secondary reaction to increased workload, and could give a clue as to the pathogenesis of sudden infant death syndrome (SIDS). We therefore quantitated by point counting on ATPase histochemistry the numbers and areas of type 1 and 2 fibers in the diaphragm, external intercostal and psoas muscles of 37 SIDS and 20 control infants. The amount of slow, fast and fetal myosin in the diaphragm and psoas muscles was measured by electrophoresis to check the ATPase quantitation. There were fewer type 1 fibers in SIDS (median 30.0%) compared with control (median 40.0%) infants (p < 0.02), whereas the diameter of type 1 fibers in SIDS (median 33.9 microns) was larger than in control (median 30.3 microns) infants (p < 0.007). The total cross-sectional area occupied by type 1 and 2 fibers was similar in both groups. No changes were found in the external intercostal or psoas. The amount of slow and fast myosins correlated well with type 1 and type 2 fibers, respectively. The finding of fewer type 1 (fatigue-resistant) fibers of large diameter in SIDS diaphragms suggests that differences in muscle fiber types may predispose these infants to diaphragm fatigue and respiratory failure.

Diaphragm↗
PubMed1995

Genital Group B Streptococcus carriage in the antenatal period: its role in prom and preterm labour.

Of 326 high vaginal swabs taken during the antenatal period, Group B Streptococcus (GBS) was isolated from the birth canal in 46 women, giving a carrier rate of 14.1%, which is within the often quoted range of between 5% - 25% in different parts of the world. Carriage rates were similar at different gestations. In a subgroup of 34 women, 2 swabs taken at least 5 weeks apart yielded results which were discordant in over one fifth of the time. This knowledge of the natural history of GBS carriage questions the practice of treating asymptomatic carriers of GBS in the antenatal period to prevent transmission of GBS to the neonate. The group of women with positive swabs in the antenatal period did not have a significantly higher incidence of preterm labour and/or prelabour rupture of membranes (PROM) compared with the group of women with negative swabs. Routine screening of the antenatal population for GBS carrier status prior to 32 weeks gestation may not identify women at high risk of PROM or preterm labour.

Adult↗
PubMed1994

Listeriosis--a review of eighty-four cases.

OBJECTIVE: To review the epidemiology, risk factors for acquisition, clinical features and outcomes of Listeria monocytogenes infection in Sydney. DESIGN: A retrospective study over the period 1983-1992 at four university teaching hospitals in Sydney. Cases were identified from microbiology laboratory records of the isolation of L. monocytogenes from sterile sites. RESULTS: Eighty-four cases were reviewed, with 72 patients (86%) having a predisposing underlying condition, including 13 perinatal patients (15%). Septicaemia (56%) and central nervous system disease (41%) were the major clinical presentations. Nineteen patients (23%) had hospital-associated infection. A mortality of 21% (18 patients) was directly attributable to L. monocytogenes infection, with another 10% (nine patients) dying of their underlying disease during admission. The 84 cases represented 80% of all L. monocytogenes cases occurring in Sydney during the study period. CONCLUSIONS: Listeriosis is predominantly a disease of the elderly or of immunosuppressed individuals, pregnant women and neonates. The presentation and outcome in these groups are similar to those reported in other Western countries. A significant feature of this study was the number of cases occurring in already hospitalised patients, suggesting that L. monocytogenes may be an important hospital-associated pathogen in immunocompromised patients.

Adult↗
PubMed1994

The HLA association with Graves' disease is sex-specific in Hong Kong Chinese subjects.

OBJECTIVE: Graves' disease is associated with different HLA genes in Caucasians and the Chinese, in whom the HLA associations may be stronger in males than females. Common HLA-associated susceptibility in both races may occur at the HLA-DQ loci. The aims of this study were to examine the HLA-A, B, DR and DQ associations with Graves' disease in a Hong Kong Chinese population and to determine whether the HLA associations differ between the sexes and between subjects with and without thyrotoxic periodic paralysis. DESIGN: HLA-A, B and DR types were determined by serological typing and DQA1 and DQB1 alleles by oligonucleotide probing of the respective enzymatically amplified gene. PATIENTS: Ninety-seven Chinese patients with Graves' disease (31 males with, 35 males without and 31 females without thyrotoxic periodic paralysis) and 105 racially matched healthy controls. MEASUREMENTS: Frequencies of HLA types/alleles at each locus were compared between patients and controls and between the Graves' subgroups using the chi 2-test. RESULTS: HLA-B46, DR9 and DQB1*0303 were associated with Graves' disease in males only; these associations were weaker in males with thyrotoxic periodic paralysis. DR12, DQA1*0401 and DQB1*0301 were protective, regardless of sex or the presence of thyrotoxic periodic paralysis. The positive HLA associations in the Hong Kong Chinese were distinct from those in Caucasians whereas the protective haplotype was similar to that described in Caucasians. CONCLUSIONS: These findings call in question the role of HLA genes in disease susceptibility but suggest a role for HLA in protection from Graves' disease.

Adult↗
PubMed1994

Multiple antibiotic resistance in Klebsiella spp. and other Enterobacteriaceae isolated in Singapore.

A common pattern of multiple antibiotic resistance has been noted in bacteria isolated from Singaporean patients. The resistance pattern includes: ampicillin, cefuroxime, ceftazidime and other third generation cephalosporins, aztreonam, gentamicin and other aminoglycosides. The bacterial species implicated are Klebsiellas and other members of the Enterobacteriaceae. Preliminary laboratory investigation with a disk-diffusion augmentation test suggests the presence of extended-spectrum beta-lactamases. A retrospective study of laboratory blood culture records shows a rising incidence of resistance in Klebsiella spp. since 1985. Antimicrobial susceptibility results suggest a high degree of co-transfer of aminoglycoside resistance. The high frequency of this type of multiple antibiotic resistance should result in greater caution in the selection of presumptive antibiotic therapy for septicaemia, in order to avoid treatment failure and further selection of resistant strains.

Anti-Bacterial Agents↗
PubMed1994

Increasing prevalence of antimicrobial resistance among organisms isolated from blood culture in a Singapore hospital.

The blood culture isolates obtained over the period 1985-1990 in a general teaching hospital were reviewed to determine trends in the prevalence of resistance to antimicrobial drugs. The percentages of Staphylococcus aureus isolates resistant to methicillin increased each year. Resistance among coagulase negative staphylococci also increased in prevalence: by 1990 approximately 50% of such isolates were resistant to methicillin, erythromycin, co-trimoxazole and gentamicin, 24% were resistant to clindamycin, 20% to fucidic acid but only 0.5% to vancomycin. Isolates of Enterobacteriaceae, excluding community-acquired salmonellae, showed increasing prevalence of resistance to beta-lactams, as did Acinetobacter spp isolates to gentamicin, co-trimoxazole and ceftriaxone. The isolates of Pseudomonas aeruginosa were exceptional, having no evident increase in the prevalence of resistance during the period. The rapid increases observed in relation to the other pathogens indicate the need for an antibiotic policy based on continuous surveillance of susceptibility patterns in the hospital.

Anti-Bacterial Agents↗
PubMed1994

Identification and characterisation of alcohol-induced flushing in Caucasian subjects.

The prevalence of the alcohol-flushing reaction was assessed in a group of healthy Caucasian medical students (200) by self-reporting and was found to occur in approximately 50% of female and 8% of male subjects. In most of the alcohol flushers there were other family members similarly affected. The presence of this side-effect after a small quantity of alcohol did not necessarily decrease the amount of alcohol consumed. A test dose of ethanol (0.4 g/kg body weight) confirmed the presence of the alcohol-induced flushing, which was of much shorter duration and intensity than that of the Oriental alcohol-induced flusher, as measured by laser Doppler velocimetry, and was not associated with high circulating concentrations of acetaldehyde. Topical administration of 5 M acetaldehyde showed an enhanced erythema in Caucasian flushers compared to non-flushing controls. This effect was not observed with topical ethanol. Low erythrocyte ALDH1 activity was found in all Caucasians (n = 30) who showed the alcohol-induced flushing reaction.

Acetaldehyde↗
PubMed1993

Comparison of shell vial culture and the suspension-infection method for the rapid detection of herpes simplex viruses.

Shell vial culture (SVC) and suspension-infection (SI) (simultaneous seeding of culture cells and inoculation of sample) were compared for the detection of herpes simplex virus (HSV) in clinical specimens. Conventional culture methods using mink lung cells or the Vero cell subline C1008 were also compared with each other and with SVC and SI. Additionally, SVC and SI were compared for quantitative determination of HSV infectivity. Compared with conventional culture with mink lung cells, culture with C1008 cells was 98% sensitive, and the sensitivities of SVC and SI were 94% and 93%, respectively. In quantitative determinations, titers of infectious HSV in positive clinical samples were a mean of five- to six-fold higher, as detected in SVC compared with SI titrations. For quantitative detection of infectious HSV, SVC was more sensitive than SI; however, for diagnosis of HSV in clinical specimens, no significant difference was observed between SI and SVC.

Female↗
PubMed1993

Phase I study of high-dose piroxantrone with granulocyte colony-stimulating factor.

PURPOSE: We performed a phase I trial of piroxantrone with and without granulocyte colony-stimulating factor (G-CSF) to determine whether the use of this cytokine would enable us to increase the dose-intensity of piroxantrone. PATIENTS AND METHODS: Thirty-eight patients received 121 courses of piroxantrone administered once every 21 days. Initial patient cohorts received piroxantrone alone starting at 150 mg/m2 and the dose was escalated in subsequent patients until dose-limiting toxicity (DLT) was reached. Patient cohorts then received escalating doses of piroxantrone starting at 185 mg/m2 administered with G-CSF beginning day 2. RESULTS: Dose-limiting neutropenia occurred in three of six patients treated with 185 mg/m2 piroxantrone; the maximum-tolerated dose (MTD) of piroxantrone alone was 150 mg/m2. Three of six patients treated with piroxantrone and G-CSF exhibited dose-limiting thrombocytopenia at 445 mg/m2; the MTD of piroxantrone with G-CSF was thus 355 mg/m2. Seven patients developed symptomatic congestive heart failure (CHF) at cumulative piroxantrone doses ranging from 855 to 2,475 mg/m2 and two have died of cardiotoxicity. Of these patients, six of seven had previously received doxorubicin. Other nonhematologic toxicity was mild. CONCLUSION: The use of G-CSF results in a more than twofold increase in the MTD of piroxantrone. However, symptomatic cardiotoxicity is prominent, especially in patients who have received prior treatment with anthracyclines.

Adult↗
PubMed1993

Lung cysts associated with Pneumocystis carinii pneumonia: radiographic characteristics, natural history, and complications.

OBJECTIVE: The purpose of our study was to characterize the radiographic features of thin-walled air-filled structures (cysts) related to Pneumocystis carinii pneumonia in a large series of patients, determine the natural history of the cysts, and test the hypothesis that the cysts are associated with an increased risk of pneumothorax. MATERIALS AND METHODS: Of 100 patients with proved pneumocystis pneumonia, 34 (34%) had cysts shown on chest radiographs. The size, number, and location of the cysts and their natural history and association with pneumothorax were determined. A control group consisting of a random sample of 30 patients was selected from the 66 patients who had pneumocystis pneumonia but no cysts to assess the frequency of pneumothorax in this population. RESULTS: Of 34 patients with cysts, 32 (94%) had multiple cysts that were 1.0-5.0 cm in diameter. Most cysts were in the upper part of the lungs. Most patients had complete or partial resolution of the cysts after the acute episode of pneumonia. Pneumothoraces occurred in 12 (35%) of the 34 patients with cysts, but in only two (7%) of the 30 who did not have cysts (p = .007). CONCLUSION: Cysts related to pneumocystis pneumonia are usually multiple, occur most often in the upper parts of the lungs, and tend to decrease in size or resolve after the acute stage of the infection. In patients with pneumocystis pneumonia, the prevalence of pneumothorax is significantly higher in those who have cysts than in those who do not. The cysts are similar to pneumatoceles and the high prevalence of pneumothorax may be due to the subpleural location of some cysts.

Adult↗
PubMed1992

Fetal laryngeal obstruction: sonographic detection.

A patient was referred at 21 weeks' gestation for unexplained fetal lung hyperechogenicity and ascites. Amniocentesis was normal. Fetal lung biopsy was consistent with the clinical diagnosis of cystic adenomatoid malformation of the lungs. However, autopsy of the stillborn infant demonstrated a cartilaginous bar, causing total laryngeal obstruction. The distinctive ultrasonographic appearance is presented.

Journal Article↗
PubMed1992

Antimicrobial resistance: patterns and trends in the National University Hospital, Singapore (1989-1991).

The commonly isolated organisms, Staphylococcus aureus, Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, Acinetobacter species, Proteus species and Enterobacter species from clinical material other than blood, cerebrospinal fluid and stool, were analysed for their incidence and increasing trends of resistance to the commonly used antimicrobials. Staphylococcus aureus was tested against penicillin, methicillin, erythromycin, gentamicin and co-trimoxazole; Pseudomonas aeruginosa against amikacin, ceftazidime, gentamicin, piperacillin and cefsulodin; and gram negative bacilli against ampicillin, co-trimoxazole, cephalexin, cefuroxime, ceftriaxone, nalidixic acid and nitrofurantoin. Methicillin sensitive Staphylococcus aureus exhibited a high degree of resistance to penicillin only (83%), but methicillin resistant Staphylococcus aureus (34-46%) showed nearly 100% resistance to all drugs tested except for co-trimoxazole over the period of study. A high incidence of resistance was found among Klebsiella species, Enterobacter species, Acinetobacter species and Pseudomonas species. Increasing trends of resistance against cephalosporins were noticed with respect to Acinetobacter species, Klebsiella species and Enterobacter species for cefuroxime and ceftriaxone; Pseudomonas aeruginosa for ceftazidime and cefsulodin. The overall resistance of organisms is notably high. Methicillin-resistant S. aureus is endemic and accounts for about 39% of all S. aureus isolates. The typical nosocomial organisms like Acinetobacter species and Klebsiella species are increasingly developing resistance to useful drugs such as gentamicin, cephalexin and ceftriaxone.

Cephalosporins↗
PubMed1992

Prevalence of bacterial agents of diarrhoeal disease at the National University Hospital, Singapore and their resistance to antimicrobial agents.

Over a 50-month period, 4,508 stool specimens from patients with diarrhoea were bacteriologically examined at the National University Hospital, Singapore. Salmonella serotypes other than the typhoid and paratyphoid bacilli were the most common finding, being isolated in 10.8% of cases. Campylobacter jejuni was unexpectedly infrequent (1.9%); Aeromonas hydrophila was found in 1.8%. No other aerobic pathogen occurred in more than 1% of cases. Clostridium difficile was sought only when requested, and was isolated from 9.6% of cases tested. Testing for enteropathogenic Escherichia coli was limited to children under 1 year old. Gentamicin was active against the greatest number of aerobic isolates, followed by chloramphenicol and cotrimoxazole. The C. difficile isolates were all sensitive to metronidazole.

Aeromonas hydrophila↗
PubMed1991

T cell receptor beta-chain usage in experimental autoimmune uveoretinitis.

Genomic rearrangements to the T-cell receptor (TCR) V beta 8 gene locus were examined in T cells derived from the lymph nodes of Lewis rats immunized with either S-Antigen or peptides derived from interphotoreceptor retinoid binding protein (IRBP). The cells used in these studies are from T-cell lines that have been selected by several cycles of antigen/IL-2 stimulations, or clones isolated from these lines. No apparent rearrangement of the V beta 8 gene was observed by Southern analysis, suggesting that if indeed there are T cells using V beta 8 gene elements they represent small proportions of the cells in these T-cell lines that induce EAU (uveitogenic T cells) and that the lines may consist of large numbers of clones. On the other hand, we have demonstrated V beta 8 gene expression in uveitogenic T-cell populations by Northern analysis and by polymerase chain reaction (PCR). Although V beta 8 gene transcripts were detectable in pathogenic, but not in non-pathogenic, T-cell lines using a V beta 8 cDNA probe, RNA from pathogenic T cell lines did not hybridize to another probe specific for rat V beta 8.2. Taken together, these results suggest that, unlike the T-cell lines that mediate experimental allergic encephalomyelitis (EAE), some T-cell lines that induce EAU do not predominantly express V beta 8.2 gene but other member(s) of the V beta 8 family.

Animals↗
PubMed1991

A hamartoma of the colon with unusual features.

An unusual case of colonic hamartoma in a 67-year-old man is reported. Colonoscopy polyp surveillance revealed a polypoid lesion of the sigmoid colon which had the characteristics of a hamartoma on microscopic examination. The lesion, which was classified as a colonic hamartoma, is described. Review of the literature revealed no previous report of such a colonic poylp.

Aged↗
PubMed1991

Suitability of infection of cells in suspension for detection of herpes simplex virus.

Detection of herpes simplex virus in clinical specimens by the suspension-infection technique was compared with detection by conventional cell culture. The sensitivity and specificity of the suspension-infection technique compared with those of conventional culture were 95.9 to 98.2% and 97.5 to 100%, respectively, depending on the cell line used in the tests. The mean time to diagnosis by the suspension-infection technique was 1 day, compared with 4.8 days by conventional culture. Comparable detection of low-level positive specimens was observed with the methods. In a clinical setting, the isolation rates obtained by suspension-infection and conventional culture were indistinguishable. These results indicate that the suspension-infection method can be used for the detection of herpes simplex virus and can yield rapid diagnostic results without a time-consuming centrifugation step.

Animals↗
PubMed1991

A comparison of costs and effectiveness of the BACTEC NR-730 system and a conventional method of blood culture.

Results and costs of the first six months experience with BACTEC NR-730 were compared with a series of blood cultures performed by the conventional method previously used. The newer technology detected the growth of 14.1% of significant isolates on the day of receipt of the specimens. The previous method lacked blind subcultures on the day of receipt and therefore detected growth only after overnight incubation. No direct comparison of the sensitivities of the methods was possible, but the percentages of cultures yielding significant isolates were similar for the two methods. With the new method, technicians needed less time for daily screening of blood cultures, fewer subcultures were required and less contamination was observed. The method used to calculate the directly-related variable costs of the two methods is set out. In the particular situation reported, workload and labor costs were such that introduction of BACTEC NR-730 resulted in a saving on variable costs.

Bacteria, Aerobic↗