Cefepime-related neurotoxicity in a haemodialysis patient.
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Adult↗
Biomedical subjects
W K Chan
Publications and source records attributed to W K Chan.
Troponin-I, myoglobin, and mass concentration of creatine kinase-MB in acute myocardial infarction.
Myoglobin, creatine kinase-MB (CKMB) mass concentration and troponin-I are newer biochemical markers for the diagnosis of acute myocardial infarction (AMI). We conducted a prospective study to formulate a model for the collective interpretation of these three markers in the diagnosis of AMI. Eighty-seven patients with AMI had serial serum samples taken to establish the time-frame sensitivity of individual markers. None of the markers had a good sensitivity within the first 4 h of infarction. Myoglobin and CKMB (mass) had sensitivities of 92.3% and 96.2%, respectively, at 4-8 h post infarct. CKMB (mass) and troponin-I had sensitivities >92% at 8-24 h. Troponin-I maintained sensitivity >93% until 72 h. A guideline was formulated based on the results. Our data suggest that troponin-I, myoglobin and CKMB (mass) yield satisfactory diagnostic sensitivity when used with reference to specific time frames. The combined use of these markers can provide valuable information for clinicians in managing AMI patients.
Adult↗
Ten-year cardiovascular risk in a Hong Kong population.
BACKGROUND: Cardiovascular disease is a major health issue in Hong Kong. We conducted a screening program to assess the 10-year risk for the population and to assess the potential benefit of large-scale screening in Hong Kong. METHOD: A local screening program for cardiovascular risk was carried out in a health service network with a total of 17,716 participants. Retrospective data analysis for the prevalence and distribution of the various risk factors was performed. The data were then applied to calculate the 10-year risk of each individual, according to the European Task Force coronary risk chart. RESULTS: Of the participants, 54.2% had total cholesterol levels > 5.2 mmol/l; 28.7% had body mass index > 25 kg/m2; 18.5% were hypertensive; 15.1% were smokers; and 3.7% had diabetes mellitus. There were 35.5% of the screened population who had at least two risk factors and 10.9% had at least three risk factors. A total of 9049 individuals satisfied the criteria for the European Task Force guidelines and were selected for 10-year cardiovascular risk analysis. We calculated that 68.0% of the male population had at least 10% risk and 41.5% had at least 20% risk of developing a coronary heart event within 10 years. Among women, 48.2% of the population carried at least 10% risk and 2.8% carried at least 20% risk. CONCLUSION: The calculated 10-year risk of the population, particularly for men, is significant. Our study demonstrated that mass screening is feasible, and has the benefit of early identification of high-risk individuals, which could be a reasonable strategy for cost-effective medicine.
Adolescent↗
Excimer laser photorefractive keratectomy for the correction of myopia.
AIM OF STUDY: To ascertain the efficacy, predictability, safety and stability of photorefractive keratectomy (PRK) for the correction of myopia. METHODS: Nine-hundred and seventy-one eyes of 628 patients had PRK performed for the correction of myopia. The mean pre-operative myopia was -5.7 D +/- 2.21 D (range -1.0 D to -15.25 D). The mean attempted correction was -5.0 D +/- 1.9 D (range -1.0 D to -9.90 D). RESULTS: Four-hundred and sixty-seven eyes had a follow-up of 6 months or more. Ninety-three percent of low myopic eyes (pre-operative myopia of less than or equal to 6.0 D) and 75% of high myopic eyes (pre-operative myopia of more than 6.0 D) attained an unaided visual acuity of 6/12 or better. Seventy-four percent of low myopic and 50% of high myopic eyes were within 1 D of the intended correction. The mean post-operative refraction at 6 months was 0.60 D +/- 1.46 D. Eight eyes in the high myopia group and 1 eye in the low myope group lost 2 or more lines or best-corrected visual acuity. CONCLUSION: PRK was safer and produced better results for low myopes.
Adult↗
Excimer laser phototherapeutic keratectomy for recurrent corneal erosions.
The purpose of this paper was to review the Singapore National Eye Centre's (SNEC) experience with excimer laser phototherapeutic keratectomy (PTK) for treating recurrent corneal erosions (RCE). Thirty-five eyes of 32 patients who had PTK between 1992 and 1997 in SNEC were studied retrospectively. There was a history of previous ocular trauma in 15 eyes. Sixteen eyes had anterior corneal dystrophy. All had received conventional therapy without improvement in symptoms. The mean duration of symptoms prior to PTK was 19 months (range 1 to 71 months). PTK was performed with one of two 193 nm excimer lasers (Summit UV200LA, Summit Technology, Waltham, USA or Visx 20/20B, Visx Corp, Santa Clara, USA). An average of 30 laser pulses were delivered to Bowman's membrane after debridement of the corneal epithelium. The mean follow-up time was 12 months (range 0 to 56 months). Among those with adequate length of follow-up, 26/27 eyes (96%) were symptom-free for 3 months, 19/22 eyes (86%) were symptom-free for 6 months and 9/13 eyes (69%) were symptom-free for 1 year. Three eyes had repeat PTK. Mild corneal haze was seen in 3 eyes. No visually threatening complications were encountered. PTK is a safe and effective procedure for RCE refractory to conventional treatment.
Adult↗
Important role of cardiac spect imaging in patients undergoing percutaneous transluminal coronary angioplasty.
OBJECTIVE: To examine the utilization and contribution of cardiac perfusion scans to patients undergoing percutaneous transluminal coronary angioplasty. METHODS: From July 1996 to January 1998, 34 patients underwent percutaneous transluminal coronary angioplasty and cardiac SPECT imaging was studied. Twenty-five patients had pre-procedure SPECT scans. The agreement between angioplasty strategies and SPECT findings of ischemia and hypokinesia was examined. RESULTS: When radionuclide imaging was performed before revascularization procedures, 84% of the patients had intervention strategies guided by scan findings. Perfusion scan findings including extent and severity of ischemia, degree of hypokinesia directed the selection of target vessel for angioplasty in the patient subgroup with multi-vessel disease. Post-angioplasty radionuclide cardiac scans were performed only on symptomatic patients, demonstrating ischemia and hypokinesia in most of them, conceivably reflected the selection bias. CONCLUSION: We recommend routine pre- and post-angioplasty radionuclide imaging with multigated scans for wall motion assessment for all patients receiving coronary intervention.
Aged↗
Novel cytokine release inhibitors. Part III: Truncated analogs of tripterine.
Truncated analogs of tripterine as cytokine (IL-1 alpha, IL-1 beta, TNF-alpha, IL-6, and IL-8) release inhibitors are discussed.
Cells, Cultured↗
Novel cytokine release inhibitors. Part I: Triterpenes.
Tripterine and closely related triterpenoid derivatives as IL-1 beta release inhibitors are discussed.
Animals↗
The cloning, expression and characterization of a cellobiase gene encoding a secretory enzyme from Cellulomonas biazotea.
A 4.7-kb DNA insert encoding a secretory cellobiase (Cba) was cloned from Cellulomonas biazotea in Escherichia coli using an excretion vector, pM. Host cells transformed with the recombinant construct, designated pBZ4.7, were able to utilize cellobiose as the sole carbon source. Part of the Cba activity encoded by pBZ4.7 could be detected in the periplasm and even in the culture supernatant. The Cba protein was purified from the culture supernatant and analyzed by SDS-PAGE to have an apparent M(r) of 86,000. The insert consisted of two PstI fragments with lengths of 0.75 and 3.95 kb, both of which were found to be crucial for expressing the Cba activity. Sequencing of the first 3.95 kb of the insert revealed that the coding sequence for Cba, designated the cba gene, was 2484 bp long. Comparison of the deduced Cba sequence with those of published beta-glucosidases revealed a potential active site located at the N-terminal portion of the former. The cba gene has a high G + C content of 76.4% and is flanked by a putative ribosome-binding site and potential transcriptional termination signals upstream and downstream from its coding sequence, respectively.
Amino Acid Sequence↗
The prediction of surgically induced refractive change from corneal topography.
PURPOSE: To develop a method to predict the refractive power of the cornea from corneal topography. METHODS: We reviewed preoperative and postoperative cycloplegic refraction, keratometry, and corneal topography in 40 eyes of 40 patients who had undergone photorefractive keratectomy, radial keratotomy, myopic keratomileusis in situ, or hyperopic lamellar keratoplasty. For each axial dioptric power map, we calculated the aspheric ellipsoid that best fit that map. Central corneal points were weighted more heavily than peripheral points, based on the Stiles-Crawford effect. The equation of the best-fit ellipsoid yielded the spherical and astigmatic power and axis for each cornea preoperatively and postoperatively. RESULTS: The preoperative corneal spherical and astigmatic powers measured by the best-fit method were consistent with the spherical and astigmatic powers measured by keratometry and simulated keratometry. The change in corneal spherical power predicted by the best-fit method was significantly (P < .05) more accurate at predicting the change in spherical equivalent refraction than change either in spherical equivalent keratometry or in spherical equivalent simulated keratometry. The prediction of the astigmatic change was less precise than that of the spherical, but the best-fit method was the most accurate. CONCLUSIONS: The best-fit method is more accurate than simulated keratometry and standard keratometry are in evaluating corneal refractive power after refractive surgery. An improved method of calculating corneal refractive power may facilitate subjective refraction after refractive surgery, improve the accuracy of intraocular lens power calculation for eyes that have had previous refractive surgery, and improve ablation profiles for excimer laser refractive surgery.
Astigmatism↗
Injection sclerotherapy in the treatment of rectal prolapse in infants and children.
PURPOSE: The aim of this study was to examine the efficacy of injection sclerotherapy as treatment for persistent rectal prolapse. METHODS: The records of 28 patients with rectal prolapse treated with injection sclerotherapy over a 16-year period were reviewed. Initial management included assessment and correction of predisposing factors. If rectal prolapse persisted or if the prolapse required repeat emergency or operating room reduction, injection sclerotherapy was performed. The sclerosing agent included D50W in 21 patients (sole agent in 15, combined with ethanolamine oleate in four, and with phenol 5% in two). Phenol 5% alone was used in six patients, and 25% saline was used in one patient. Number of injections, recurrences, and complications were reviewed. RESULTS: Two patients were lost to follow-up, and one patient was cured once a polyp was recognized and removed. Of the remaining 25 patients, 21 were cured. Sixteen required one injection, three required two injections, and two required three injections (64% cure rate after one injection, 84% cure rate after three injections). There were 4 of 25 failures: two went on to low anterior resection after having failed two injections each; one patient was treated with Thiersch cerclage and injection after two failed injections; and one patient did not respond after three injections but had less severe prolapses. Of those injected with D50W alone, 13 of 14 were cured with injection sclerotherapy. Nine received one injection, two received two injections, and two received three injections (64% cure rate after one injection, 93% cure rate after three injections). The only complication was excessive oozing at the injection site in one patient. He was simply observed in hospital overnight. Follow-up averaged 33 months. The only significant underlying abnormality in our patient population was spina bifida in one patient. This patient was cured with injection therapy. Cystic fibrosis was ruled out by clinical examination and sweat chloride test in all patients. Constipation was the most common condition identified with the onset of rectal prolapse (15 of 28). CONCLUSIONS: Injection sclerotherapy is simple and should be considered as the first line treatment of recurrent rectal prolapse after failure of conservative measures. D50W is effective, easily available, inexpensive, and associated with few complications.
Causality↗
Mechanism-based inactivation of human cytochrome P450 3A4 by grapefruit juice and red wine.
Grapefruit juice is well documented to cause clinically significant increases in the plasma concentrations of many therapeutic agents. These interactions are believed to be mediated via inhibition of intestinal cytochrome P-450 3A4 (CYP3A4) by flavonoids and/or other chemicals in grapefruit juice, although the mechanism of that inhibition has not been fully characterized. Like grapefruit juice, red wine contains large amounts of flavonoids and other xenobiotics which could also mediate CYP3A4 inhibition. In this study, we investigated the mechanism of inhibition of CYP3A4 by grapefruit juice and also examined the ability of red wine to inhibit this enzyme. Both red wine and grapefruit juice potently inhibited CYP3A4 activity in a concentration-dependent manner. At 8% of natural strength, enzyme activity was inhibited almost 90 and 84%, respectively, by grapefruit juice and red wine. In contrast, white wine did not appreciably inhibit CYP3A4 activity. Grapefruit juice irreversibly inactivated CYP3A4 in a time- and NADPH-dependent manner. The rate of inactivation mediated by grapefruit juice was similar to that mediated by troleandomycin, a potent mechanism-based inhibitor of CYP3A4. Red wine also inactivated CYP3A4 but at a rate approximately 16% that of grapefruit juice. Inhibition of CYP3A4 by red wine is primarily reversible in nature. The clinical implications of this research are discussed.
Beverages↗
Catalase prevents estradiol-induced chondrocyte cytotoxicity.
Osteoarthritis is a common geriatric disease and estrogen may play an important role in this disease. Estradiol may cause chondrocyte damage as suggested by in vitro and in vivo data. One of the possible mechanisms of estradiol-induced chondrocyte damage was thought to be related to free radicals. Whether catalase, a known free radical scavenger, can prevent estradiol-induced chondrocyte damage was tested using a chondrocyte culture system. The results of this study suggest that catalase can significantly reduce the estradiol-induced damage to chondrocytes. Apparently, catalase alters the molecular structure of estradiol as indicated by the absorption spectrum of estradiol with time. The modified estradiol may decrease its toxicity to the chondrocytes. However, the contents of free radicals in the treated chondrocytes have no significant difference from the untreated control cells. Studies to further investigate the mechanism or prevention of estradiol-induced chondrocyte damage in osteoarthritis are warranted.
Animals↗
Weekly etoposide, epirubicin, cisplatin, 5-fluorouracil and leucovorin: an effective chemotherapy in advanced gastric cancer.
In order to optimize the therapeutic index of combining etoposide, epirubicin, cisplatin, 5-fluorouracil (5-FU), leucovorin (EEPFL) chemotherapy in the treatment of advanced gastric cancer, a trial of a novel schedule of weekly administration was conducted. Weekly EEPFL treatment consisted of a concomitant boost of etoposide 40 mg m(-2) i.v. over 30 min, epirubicin 10 mg m(-2) i.v. over 5 min to a backbone regimen, weekly PFL chemotherapy with cisplatin 25 mg m(-2), 5-FU 2200 mg m(-2), leucovorin 120 mg m(-2) given simultaneously by 24-h i.v. infusion. Response, survival and toxicity were evaluated. Forty-two patients were studied. Median age was 69 (range 31-84) years. Twenty-six per cent of patients showed complete response and 45% partial response. The overall response rate was 71% (95% confidence interval 58-84%). For a total of 507 weekly EEPFL cycles delivered, the incidence of grade 4 leucopenia was 1% of cycles. One patient died of neutropenia septicaemia. There was no other grade 4 toxicity. Grade 3 and 2 leucopenia occurred in 7% and 14% of cycles. The incidence of grade 3 and 2 mucositis was 1% and 3% of cycles. Grade 3 and 2 diarrhoea occurred in 0.4% and 1.6% of cycles. Overall median survival was 10 months (range 3-41+ months). Weekly EEPFL chemotherapy is an effective regimen with tolerable toxicities in the treatment of advanced gastric cancer. A randomized controlled clinical trial to formally assess the efficacy and benefit of EEPFL chemotherapy is under way.
Adult↗
Phase II and pharmacokinetic study of paclitaxel therapy for unresectable hepatocellular carcinoma patients.
Hepatocellular carcinoma (HCC) is a common lethal disease in Asia and there is no effective chemotherapy. Identification of new effective drugs in the treatment of inoperable HCC is urgently need. This is a phase II clinical study to investigate the efficacy, toxicity and pharmacokinetics of paclitaxel in HCC patients. Twenty patients with measurable, unresectable HCC, normal serum bilirubin, normal bone marrow and renal functions were studied. Paclitaxel 175 mg m(-2) was given intravenously over 3 h every 3 weeks. No complete or partial responses were observed. Five patients had stable disease. Major treatment toxicities (grade 3-4) were neutropenia (25%), thrombocytopenia (15%), infection (10%) and allergy (10%). Treatment-related deaths occurred in two patients. The median survival was 12 weeks (range 1-36). Paclitaxel is metabolized by the liver and the pharmacokinetics of paclitaxel in cancer patients with liver involvement or impairment may be important clinically. Pharmacokinetic study was completed in 13 HCC patients. The paclitaxel area under the curve was significantly increased (P < 0.02), clearance decreased (P < 0.02) and treatment-related deaths increased (P = 0.03) in patients with hepatic impairment. In conclusion, paclitaxel in this dose and schedule has no significant anti-cancer effect in HCC patients. Paclitaxel should be used with caution in cancer patients with liver impairment.
Adult↗
Beef color update: the role for vitamin E.
Dietary supplementation of livestock with vitamin E results in improved quality of meat subsequently obtained from these animals. The effect is especially noteworthy in cattle, in which the primary effects are delayed discoloration and lipid oxidation. A threshold level of alpha-tocopherol in muscle ensures a detectable effect; dietary strategies for attaining this threshold must consider tocopherol status of cattle arriving at the feedyard and duration and level of supplementation. The alpha-tocopherol concentration in muscle must be determined before proper interpretation of experimental results can be made. Muscles vary in their color stability, and this relative difference is not changed by vitamin E supplementation. Several in vitro models have been used to characterize the interaction between alpha-tocopherol, lipid oxidation, and oxymyoglobin oxidation. Alpha-tocopherol seems to exert its color-stabilizing effect by indirectly delaying oxymyoglobin oxidation via direct inhibition of lipid oxidation. However, recent results demonstrating a protective effect of alpha-tocopherol toward oxymyoglobin in low-oxygen atmospheres indicate that additional mechanisms may exist. A better understanding of the fundamental bases for protection of water-soluble myoglobin by lipid-soluble alpha-tocopherol is needed to optimize this beneficial effect.
Animals↗
Effects of alpha-tocopherol on metmyoglobin formation and reduction in beef from cattle fed soybean or cottonseed meal diets.
Hereford-Angus crossbred heifers were fed a cottonseed meal-based diet containing gossypol (14 mg free gossypol x kg body wt(-1) x d(-1); CSM), a soybean meal-based diet (SBM), or alpha-tocopherol-supplemented diets (4,036 IU vitamin E x heifer(-1) x d(-1) for 90 d; CSM+E and SBM+E). The effects of diet on color stability and aerobic metmyoglobin reducing ability of beef longissimus lumborum (LL) and psoas major (PM) were evaluated. The CSM containing gossypol did not affect alpha-tocopherol concentration, a* value, or hue angle value of beef muscles obtained from control or vitamin E-supplemented cattle compared to their SBM counterparts. Vitamin E supplementation increased endogenous alpha-tocopherol concentrations and color stability in LL and PM muscles compared with controls from either diet (P < .05). In the aerobic metmyoglobin reducing ability study, LL and PM muscles were stored in 1% O2:99% N2 (a pigment-oxidizing atmosphere) for 48 h and subsequently stored aerobically for an additional 48 h. Within the LL, alpha-tocopherol supplementation delayed metmyoglobin formation in LL exposed to 1% O2 (P < .05). Within the PM, no differences in metmyoglobin formation were found between controls and vitamin E treatments in SBM or CSM diets. Relative aerobic metmyoglobin reduction was the same (P > .05) in LL and PM muscles within SBM or CSM diets for control and vitamin E treatments. Alpha-tocopherol did not seem to affect metmyoglobin aerobic reducing ability in LL and PM muscles.
Animals↗
Effect of Pseudomonas fluorescens on beef discoloration and oxymyoglobin oxidation in vitro.
The relationship between bacterial growth and oxymyoglobin oxidation in vitro and in meat was studied. In the in vitro study, oxymyoglobin was combined with Pseudomonas fluorescens or sterile nutrient broth (control) in an airtight vessel. P. fluorescens samples showed greater metmyoglobin formation and oxygen consumption than controls. The P. fluorescens population in the reaction vessels was correlated with metmyoglobin formation (r = 0.85, P < 0.05) and oxygen consumption (r = 0.91, P < 0.05). When P. fluorescens and oxymyoglobin were combined in an airtight vessel, reducing the headspace from 13 ml and 9 ml to 3 ml resulted in greater metmyoglobin formation (P < 0.05). In the meat study, beef cores prepared from longissimus lumborum were inoculated with P. fluorescens (10(7) CFU/cm2) or sterile peptone water (control), packaged under 1% O2 (+99% N2), air, or 100% O2 and stored at 4 degrees C. Inoculated beef cores showed higher bacterial loads and metmyoglobin formation than their respective controls during 10 h storage in 1% O2, 3 days in air, and 7 days in 100% O2 (P < 0.05). This finding indicated that P. fluorescens could accelerate beef discoloration. Overall, studies demonstrated that oxygen consumption concomitant with P. fluorescens growth decreased partial oxygen pressure, which accelerated oxymyoglobin oxidation.
Animals↗