Biomedical subjects

C Y Chan

Publications and source records attributed to C Y Chan.

165 records · Page 10Linked to original sources

PubMedDate not supplied

Detection of fluoroquinolones in urinary specimens from patients undergoing anti-tuberculous therapy.

A paper strip impregnated with ferric chloride has been developed for visual detection of fluoroquinolones in urine based on a change of colour due to the chelation of the transition metal ion to the beta-oxo acid array in the 4-oxo-1,4-dihydropyridine-3-carboxylic acid moiety of the fluoroquinolone molecule. In urine specimens, the detection limit of the strip was 100 mg/l for pefloxacin, 200 mg/l for ciprofloxacin, fleroxacin, levofloxacin, norfloxacin, ofloxacin and sparfloxacin, and 300 mg/l for trovafloxacin. In 193 urine specimens taken from 138 patients on ofloxacin therapy and 55 controls preliminary evaluation of the strip showed that all the 55 specimens from control patients were negative, while 112 out of the 138 ofloxacin-treated patients were positive. Quantitative analysis by high-performance liquid chromatography of the 26 strip-test-negative specimens taken from patients with ofloxacin treatment indicated that these urinary specimens contained less than 200 mg/l of the antimicrobial, mostly because of poor renal function and in some occasions, non-compliance. This strip method would provide a convenient way of monitoring drug compliance in patients who receive fluoroquinolone therapy for tuberculosis.

Anti-Infective Agents↗

PubMedDate not supplied

Matrix metalloproteinase-8 in sera and from polymorphonuclear leucocytes in rheumatoid arthritis: in vitro characterization and correlation with disease activity.

OBJECTIVES: To determine matrix metalloproteinase-8 (MMP-8) secretion from rheumatoid arthritis (RA) peripheral blood polymorphonuclear leucocytes (PMNs), in response to immune complexes (IC), cytokines and their combinations, and to study correlation of serum MMP-8 with disease activity. METHODS: PMNs from RA patients and controls were stimulated in vitro with interleukin-15 (IL-15), IL-18, adherent immune complexes, rabbit anti-human immunoglobulin G (anti-HIgG), human immunoglobulin G (HIgG), and their F (ab') 2 prongs, phorbol myristate acetate (PMA) or combinations of above. Supernatants from these experiments and sera from both groups were assayed for MMP-8 using ELISA and correlated with disease activity measures in patients. RESULTS: MMP-8 secretion from stimulated PMNs was compared to unstimulated PMNs. Immune complexes elicited significant MMP-8 secretion (p = 0.006 and 0.001, control and RA respectively). Unlike HIgG and its F (ab')2 fragment, very high secretion was elicited by anti-HIgG (242.37 +/- 10.85 ng/ml) and its F (ab')2 prong (195.85 +/- 28.67 ng/ml). IL-15 did not elicit any secretion. IL-18 with PMA increased secretion significantly only from RA PMNs (p = 0.003). Serum MMP-8 correlated positively with serum CRP (p = 0.017) and not with disease activity score (p = 0.199). CONCLUSIONS: We for the first time demonstrate that immune complexes elicit MMP-8 secretion from PMNs. Except for higher secretion from RA PMNs in response to combination of IL-18 and PMA, both control and RA PMNs respond similarly to various stimuli. Secretion by anti-HIgG occurs by a mechanism independent of Fc receptor. Correlation with CRP suggest that serum MMP-8 may be an indicator of acute inflammatory activity.

Adult↗

PubMedDate not supplied

Magnetic resonance imaging for the detection of nasopharyngeal carcinoma.

BACKGROUND: Endoscopic guided biopsy (EGB) is performed after an initial endoscopy for the investigation of patients with suspected nasopharyngeal carcinoma (NPC). The aim of the study was to determine whether MR imaging has the potential to replace invasive EGB in patients with a normal endoscopy. PATIENTS AND METHODS: Data from 2 groups of patients was reviewed, group 1 with proved NPC for MR staging (n = 456) and group 2 with suspected NPC (n = 77). The sensitivity was calculated for group 1 and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for group 2. RESULTS: In group 1, which included 118 of 456 (26%) with stage 1 disease, cancer was detected in all patients, giving a sensitivity of 100%. In group 2, MR imaging was negative for NPC in 70 (91%) patients, and no cancer has been detected on follow-up (follow-up range, 1-90 months; mean, 36 months). MR imaging was positive for NPC in 7 (9%) patients and NPC was confirmed by biopsy in 3 (4%). Two of these 3 patients had undergone negative endoscopy and biopsy before the MR imaging. NPC was not present in the remaining 4 patients, 2 of whom were found to have lymphoid hyperplasia. MR imaging had a sensitivity of 100%, specificity of 95%, NPV of 100%, PPV of 43%, and accuracy of 95%. CONCLUSION: MR imaging has the potential to screen healthy patients who do not require EGB and direct the site of biopsy in small cancers that may be missed by endoscopy. On the basis of these results, a prospective study is planned.

Adolescent↗