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Biomedical subjects

P Chew

Publications and source records attributed to P Chew.

At least 19 recordsLinked to original sources
PubMed2003

Intraocular pressure and visual field loss in primary angle closure and primary open angle glaucomas.

AIM: To compare the correlation between visual field loss and the pretreatment intraocular pressure (IOP) in primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG). METHODS: In a cross sectional observational study of 74 patients (43 PACG, 31 POAG), pretreatment IOP was measured at presentation, before treatment was initiated. The severity of visual field loss was assessed by AGIS score, mean deviation (MD), pattern standard deviation (PSD), and corrected pattern standard deviation (CPSD). Glaucomatous optic neuropathy was assessed from simultaneous stereo disc photographs. RESULTS: There was a stronger correlation between pretreatment IOP and the extent of visual field loss in PACG subjects than in those with POAG for both MD (PACG: Pearson correlation coefficient (r) = 0.43, p = 0.002; r(2) = 0.19), (POAG: r = 0.21, p = 0.13; r(2) = 0.04) and AGIS score (PACG: r = 0.41, p = 0.003; r(2) = 0.17), (POAG: r = 0.23, p = 0.19; r(2) = 0.05 respectively). No such associations were seen for pattern standard deviation (PSD) or corrected pattern standard deviation (CPSD) in either group (p> 0.29). Both horizontal and vertical cup-disc ratio were well correlated with severity of field loss but not with presenting IOP for either diagnosis. CONCLUSIONS: This is consistent with the hypothesis of a greater IOP dependence for optic nerve damage in PACG than POAG and, conversely, a greater importance of other, less pressure dependent mechanisms in POAG compared to PACG.

Antimetabolites↗
PubMed2001

Diethyl phthalate, a chemotactic factor secreted by Helicobacter pylori.

The structure of a small-molecule, non-peptide chemotactic factor has been determined from activity purified to apparent homogeneity from Helicobacter pylori supernatants. H. pylori was grown in brucella broth media until one liter of solution had 0.9 absorbance units. The culture was centrifuged, and the bacteria re-suspended in physiological saline and incubated at 37 degrees C for 4 h. A monocyte migration bioassay revealed the presence of a single active chemotactic factor in the supernatant from this incubation. The chemotactic factor was concentrated by solid phase chromatography and purified by reverse phase high pressure liquid chromatography. The factor was shown to be indistinguishable from diethyl phthalate (DEP) on the basis of multiple criteria including nuclear magnetic resonance spectroscopy, electron impact mass spectroscopy, UV visible absorption spectrometry, GC and high pressure liquid chromatography retention times, and chemotactic activity toward monocytes. Control experiments with incubated culture media without detectable bacteria did not yield detectable DEP, suggesting it is bacterially derived. It is not known if the bacteria produce diethyl phthalate de novo or if it is a metabolic product of a precursor molecule present in culture media. DEP produced by H. pylori in addition to DEP present in man-made products may contribute to the high levels of DEP metabolites observed in human urine. DEP represents a new class of chemotactic factor.

Animals↗
PubMed2001

Quantitation of mitomycin C in human ocular tissues by high-performance liquid chromatography-photo-diode array detection.

A chromatographic method, which can quantitate mitomycin C (MMC) along with two antiglaucoma drugs, is described. The separation of MMC, alphagan and timolol was performed on a reversed-phase C18 column with water-methanol-trifluoroacetic acid (65:35:0.01, v/v) as the mobile phase. By monitoring at 360, 248 and 296 nm, the lower limits of detection for MMC, alphagan and timolol are, respectively, 1.0, 2.0 and 5.0 ng (injection amount) at three-time S/N ratio. The dynamic ranges of quantitation for the three drugs are, respectively, 1.0 ng-10.0 microg, 2.0 ng-10.0 microg and 5.0 ng-10.0 microg with linearity being larger than 0.9960. This method was applied to the determination of MMC levels in Tenon's and trabeculum tissues of 10 glaucoma patients. MMC levels in these tissues, which were obtained from glaucoma filtering surgery, were determined following a multiple extraction with methanol. The recovery of MMC for a two-batch extraction was better than 91.2%. The reproducibility of measurement for the MMC levels in these tissues is 2.5-6.0% RSD for triplicate injections. The intra-day variation of retention times for the MMC peaks was less than 1.6% RSD (n=3). The inter-day variation of retention times for the MMC peaks was less than 4.8% RSD (n=3). MMC was detectable in three trabeculum tissues out of 10 cases (ranging from 0.8 to 25.5 ng/mg specimen), while MMC was detected in nine Tenon's tissues out of 10 cases (ranging from 0.3 to 21.1 ng/mg specimen). The results obtained show that the method is sensitive and selective for the quantitation of MMC.

Antihypertensive Agents↗
PubMed2001

The pravastatin inflammation CRP evaluation (PRINCE): rationale and design.

BACKGROUND: Randomized, controlled trials demonstrate that HMG CoA reductase inhibition reduces coronary event rates in both primary and secondary prevention. In addition to reducing cholesterol levels, laboratory evidence suggests that statins also have anti-inflammatory activity, a property that may be critical for maintaining plaque stability. Recently, the inflammatory marker high-sensitivity C-reactive protein (hs-CRP) has been shown to predict vascular risk in individuals with and without hyperlipidemia. Furthermore, in the Cholesterol and Recurrent Events (CARE) trial, the relative efficacy of pravastatin in reducing events was greatest among those with elevated levels of hs-CRP. However, the time course and magnitude of this effect in both primary and secondary prevention is controversial. METHODS: PRavastatin Inflammation CRP Evaluation (PRINCE) is an investigator-initiated, multicenter, community-based trial that will evaluate the effects of pravastatin on hs-CRP in up to 1182 individuals with coronary artery disease and up to 1702 individuals without coronary artery disease. Lipid profiles and hs-CRP levels will be obtained at baseline, 12 weeks, and 24 weeks in all study participants. Patients with known coronary artery disease will receive 40 mg/d pravastatin, whereas those without coronary artery disease will be randomly assigned to receive placebo or 40 mg/d pravastatin. CONCLUSIONS: The potential clinical impact of the PRINCE trial is substantial because nearly 50% of myocardial infarctions in the United States occur in persons with normal cholesterol levels, and inflammatory markers such as hs-CRP may provide a means to detect such individuals at high risk who do not currently qualify for statin therapy. The PRINCE trial will determine the time course of effect of this statin on hs-CRP and whether any observed effect on hs-CRP is independent of pravastatin-induced changes in low-density lipoprotein cholesterol.

Adult↗
PubMed2001

Meta-analysis of randomized controlled trials on the comparative efficacy and safety of azithromycin against other antibiotics for upper respiratory tract infections.

We carried out a meta-analysis of randomized controlled trials comparing 3-5 days of azithromycin with other antibiotics that are typically given in longer courses for the treatment of upper respiratory tract infections. For acute otitis media (19 comparisons including 3421 patients), acute sinusitis (11 comparisons including 1742 patients) and acute pharyngitis (16 comparisons including 2447 patients), azithromycin had similar clinical failure rates to the other antibiotics [random effects odds ratios 1.12, 95% confidence interval (CI) 0.81-1.54; 0.91, 95% CI 0.60-1.39; and 1.07, 95% CI 0.59-1.94, respectively]. The difference in clinical failures was <0.5%, and no 95% CIs exceeded 2.0%. There was no heterogeneity between studies. Subtle differences between comparators could have been due to chance. There were no significant differences in bacteriological outcomes. Azithromycin was discontinued because of adverse events in only 37 of 4870 (0.8%) patients. Short courses of azithromycin are as effective as longer courses of other antibiotics for upper respiratory tract infections. Convenience of dosing should be balanced against the increased cost of this regimen for the treatment of these common infections, where often no antibiotic may be indicated at all.

Acute Disease↗
PubMed2001

Meta-analysis of randomized controlled trials on the comparative efficacy and safety of azithromycin against other antibiotics for lower respiratory tract infections.

We carried out a meta-analysis of randomized controlled trials of azithromycin compared with other antibiotics in the treatment of lower respiratory tract infections, including acute bronchitis (five comparisons including 1372 patients), acute exacerbations of chronic bronchitis (13 comparisons including 1342 patients) and community-acquired pneumonia (18 comparisons with 1664 patients). For the first two indications, azithromycin did not offer any statistically significant reduction in clinical failures [random effects odds ratios 0.84, 95% confidence interval (CI) 0.54-1.31 and 0.64, 95% CI 0.31-1.32, respectively] and absolute risk differences were small. For community-acquired pneumonia, azithromycin significantly reduced clinical failures by about one-third (random effects odds ratio 0.63, 95% CI 0.41-0.95). The absolute incremental benefit was approximately one clinical failure prevented per 50 treated patients with community-acquired pneumonia. There was no significant heterogeneity for different comparators and for bacterial versus atypical pneumonias. Azithromycin was discontinued because of adverse events in only 23 of 3487 patients (0.7%). Although results should be interpreted cautiously as most trials were open-label and susceptible to bias, the meta-analysis indicates that, compared with antibiotics with traditional pharmacokinetics that require more prolonged courses, azithromycin offers no significant advantage for bronchitis, but may be more effective in community-acquired pneumonia.

Anti-Bacterial Agents↗
PubMed2000

Using focus group methods to develop multicultural cancer pain education materials.

Methods to treat cancer pain effectively have existed for more than 2 decades. However, the effective treatment of cancer pain continues to elude many patients with cancer who suffer from poor management. Although efforts to address the problem of cancer pain in the United States have acknowledged the importance of patient education and advocacy, few endeavors, to date, have attended to the special needs of inner-city, low-literacy, or socioeconomically disadvantaged patients from minority cultural groups. From 1992 to 1995, the Boston Cancer Pain Education Program, funded by the National Cancer Institute and the American Cancer Society, worked collaboratively with community representatives using focus group methods to develop a culturally sensitive, linguistically appropriate cancer pain education booklet in 11 languages and for 11 ethnic groups. The booklet serves as a guide for patients and families and is to be used as a teaching tool by clinicians. The focus group approach was used to develop materials that would empower patients and families to more effectively participate in pain management when working with health care providers from cultures other than their own. Qualitative data analysis methods were used to analyze transcripts of taped focus group sessions. Themes emerged from the data regarding pain and its culturally competent management as well as the group process of booklet development.

Boston↗
PubMed2000

Effect of remifentanil compared with fentanyl on intraocular pressure after succinylcholine and tracheal intubation.

Rapid sequence induction using succinylcholine is associated with an increase in intraocular pressure (IOP). This may lead to loss of ocular contents in open globe injuries. No method has previously been shown to prevent this increase in IOP. We investigated whether remifentanil, an ultra-short-acting opioid, could attenuate this increase in IOP during rapid sequence induction of anaesthesia. Forty-five patients were randomized blindly to receive remifentanil 1 microgram kg-1, fentanyl 2 micrograms kg-1 or placebo 1 min before thiopental, succinylcholine and tracheal intubation. IOP and haemodynamic variables were measured before, 1 min after the test solution, 30 s after thiopental, 30 s after succinylcholine, immediately after intubation and then every 3 min for 9 min. Remifentanil obtunded the increase in IOP after succinylcholine and intubation, so it could be suitable for use in open globe injuries.

Adult↗