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Biomedical subjects

J Chow

Publications and source records attributed to J Chow.

At least 37 records · Page 2Linked to original sources
PubMed2000

PM10 dispersion modeling for Treasure Valley, Idaho.

The recorded exceedances of the 24-hr PM10 National Ambient Air Quality Standard (NAAQS) in Treasure Valley, Idaho, have been associated with prolonged stagnation periods during the winter. A comprehensive modeling study of PM10 impact in Treasure Valley was performed to support the State Implementation Plan (SIP). The study included base-year and short-term episodic conditions. The ISCST3 (Industrial Source Complex Short Term 3) model, using the base-year meteorology and gridded emissions of mobile sources, point sources, and wood burning as input, generally agreed well with measurements in both temporal patterns and annual averages. The WYNDvalley model was evaluated using monitoring data and was used to simulate the PM10 impact for episodic exceedances during stagnant winter conditions. An emission inventory was prepared for a base year (1995) and then extrapolated to the years 2000, 2005, 2010, and 2015 in order to determine air quality planning requirements. According to the simulations using base-year emissions and meteorology, exceedances are not expected. However, exceedances at some stations could be expected using projected emissions and episodic meteorology. Results from emission control strategies we developed indicate that mobile-source emissions have the most significant impact; reduction of 25% would be needed to eliminate the simulated exceedances in all projected years.

Air Pollution↗
PubMed2000

Glucose-based oligosaccharides exhibit different in vitro fermentation patterns and affect in vivo apparent nutrient digestibility and microbial populations in dogs.

To evaluate the potential of indigestible oligosaccharides (OS) to serve as "dietary fiber-like" ingredients, it is necessary to determine their extent of indigestibility. In vitro fermentation characteristics of two novel OS, alpha-glucooligosaccharides (GOS) and a maltodextrin-like OS (MD), were compared to those of fructooligosaccharides (FOS), gum arabic (GA), guar gum (GG) and guar hydrolysate (GH). Total short-chain fatty acid (SCFA) production (micromol/g dry matter) as a result of MD fermentation was higher initially compared with GA (P<0.01), but GA was more extensively fermented at 24 h (P<0.01). Total SCFA production for GOS was similar to that for FOS, GG, GH and GA. In the second experiment, GOS and MD were added at 6% to an enteral formula control diet (Control) and fed to ileal-cannulated dogs in a 3x3 replicated Latin-square design. Ileal digestibility of glucose was lower (P<0.05) and carbohydrate (CHO) numerically lower (P = 0.08) for both GOS and MD compared with the Control. Total tract digestibility of CHO and glucose was lower only for MD (P<0.01) compared with the Control. Total fecal weights were higher (P<0.01) for both GOS and MD treatments. Fecal concentration of bifidobacteria was numerically increased by GOS and MD supplementation (P = 0.13 and 0.23, respectively). Thus, GOS and MD are indigestible yet fermentable OS, and may act as "dietary fiber-like" ingredients.

Animals↗
PubMed1999

Economic implications of an early postoperative enteral feeding protocol.

OBJECTIVE: To study the cost-effectiveness of an early postoperative feeding protocol for patients undergoing bowel resections. DESIGN: A nonrandomized, prospective, clinical trial. Surgeons elected to participate in the treatment arm before the study's outset. SUBJECTS/SETTING: Treatment (n = 66) and control (n = 159) patients were admitted to a nonprofit general teaching hospital in the Texas Medical Center for similar diagnoses and subsequent bowel resections during an 18-month period. INTERVENTION: Treatment patients who met specific inclusion criteria had a jejunal feeding tube placed during surgery. Tube feedings were initiated within 12 hours after surgery. Control patients who met the same inclusion criteria received usual care. OUTCOMES: A successful outcome was defined as a patient developing no postoperative infection. The average cost of a nosocomial infection is presented. Variable direct and total costs (fixed plus variable) are compared between patient groups. STATISTICAL ANALYSIS: Mean cost was adjusted for rate of success in each patient group according to an analytic model. The mean cost difference between groups was analyzed by independent-samples t tests. Nonparametric Mann-Whitney rank sum tests were used to determine the cost significance of a nosocomial infection. RESULTS: The average variable direct cost savings per successful treatment patient was $1,531, which required an additional variable cost of $108.30 for the dietitian's time. The protocol resulted in a total cost savings of $4,450 per success in the treatment group. CONCLUSION: An early postoperative enteral feeding protocol as part of an outcomes management program for patients undergoing bowel resection is cost-effective.

Clinical Protocols↗
PubMed1999

Early effects of hormone replacement therapy on bone.

Estrogen replacement is currently the preferred therapy for postmenopausal osteoporosis, although its mechanism of action remains poorly understood. Its primary action on bone is generally considered to be antiresorptive, but there is evidence in animals to suggest a stimulatory effect on bone formation. We have now attempted to detect a similar effect in humans by administering hormone replacement therapy (estradiol valerate 2 mg/day and dydrogesterone 5 mg/day given in a continuous, combined manner) to ten postmenopausal women. We carried out histomorphometric analyses of transiliac bone biopsies after quadruple tetracycline labeling, which was commenced before and continued during the first 4 weeks of hormone replacement therapy. Biochemical markers of bone turnover suggested that bone resorption decreased, but no significant effects on histomorphometric parameters of bone formation were detected. We conclude that hormone replacement therapy at the dose given does not stimulate bone formation in the iliac crest as assessed by histomorphometry.

Absorptiometry, Photon↗
PubMed1998

The role of functional endoscopic sinus surgery in asthmatic patients.

OBJECTIVE: This study was conducted to determine the efficacy of FESS (functional endoscopic sinus surgery) on sinus and asthma symptoms. METHOD: Seventy-nine patients with asthma and medically unresponsive sinusitis were evaluated. Maximal medical therapy was attempted to relieve both sinus and asthma symptoms. The surgical procedures involved standard FESS techniques. Fifty-six percent of patients had undergone a sinus procedure prior to the FESS. Nasal polyposis was noted in 73% of the group. The majority of patients had pansinusitis. RESULTS: Eighty-six percent of patients stated that FESS improved their sinusitis. Nine of 11 sinus symptoms recorded preoperatively diminished significantly (p < .05) following surgery. Eighty percent of patients noted improvement of their asthma following FESS. The factors associated with treatment failure and the unique characteristics of this disease process were evaluated. CONCLUSIONS: FESS is a viable option in the treatment of asthma when medical therapy fails.

Adolescent↗
PubMed1997

Potent tetracyclic guanine inhibitors of PDE1 and PDE5 cyclic guanosine monophosphate phosphodiesterases with oral antihypertensive activity.

Tetracyclic guanines have been shown to be potent and selective inhibitors of the cGMP-hydrolyzing enzymes PDE1 and PDE5. In general, these compounds are inactive or only weakly active as inhibitors of PDE3, which is a major isozyme involved in cAMP hydrolysis. Structure-activity relationships are developed at N-1, C-2, N-3, and N-5 on the core nucleus. Compound 31, with an IC50 of 70 pM, is the most potent inhibitor of PDE1, while 50, with an IC50 of 4 nM, is the most potent inhibitor of PDE5. Compounds 20, 22, 30, and 50 are potent dual inhibitors with IC50 values below 30 nM for both PDE1 and PDE5. Compounds 12, 20, and 28 reduced blood pressure by more than 45 mmHg when administered orally at 10 mg/kg to the spontaneously hypertensive rat (SHR).

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1997

Nasal lymphoma: results of local radiotherapy with or without chemotherapy.

BACKGROUND: Primary nasal lymphoma is a rare disease. Although most patients are initially seen in early Ann Arbor stages, their prognosis is poor. The prognostic significance of local tumor bulk has not been well studied. METHODS: Twenty-one patients with nasal lymphoma treated between 1985 and 1992 were retrospectively studied. Sixteen patients (76%) below the age of 75 years received combined radiotherapy and chemotherapy. One young patient with early disease and 4 elderly patients had radiotherapy alone. Twelve cases (57%) were diagnosed as pleomorphic T-cell lymphoma based on typical histologic features alone. Immunophenotyping was performed in 10 cases; 8 were T cell and 2 were B cell. Seventeen patients (81%) had Ann Arbor clinical stage IE disease, and 4 had stage IIE disease. The local tumor extent was assessed by endoscopy in all patients and by computerized tomography (CT) in 14 patients. Eleven local tumors (52%) extended to the posterior ethmoids, sphenoid sinus, orbit, or beyond. Using a T-stage system, the prognostic significance of local tumor bulk was evaluated for stage IE patients. RESULTS: At a median follow-up time of 16.8 months, the lymphoma recurred in 13 patients; 10 patients had systemic relapse and 10 patients, local relapse. The 5-year actuarial overall survival rate was 24%. Complete response to chemotherapy was achieved in 5 of 16 patients (31%). Four of the 6 patients who remained alive and disease-free were chemotherapy complete responders. Among stage IE patients, those with early and those with advanced local disease did not have significantly different survival. CONCLUSIONS: In view of the high systemic and local relapse rates, more-effective chemotherapy is needed to improve the survival rates, and the role of combined chemotherapy and radiotherapy should be evaluated. Further studies are required to identify patients at high risk of relapse for clinical trials with investigational treatment.

Adult↗
PubMed1997

Cloning, sequence, and expression of the L-(+) lactate dehydrogenase of Streptococcus bovis.

The ldh gene encoding the fructose-1,6-diphosphate-dependent L-(+) lactate dehydrogenase from the ruminal bacterium Streptococcus bovis was cloned and sequenced. A genomic library of S. bovis JB1 DNA was constructed in lambda ZAP II and screened by use of a heterologous probe derived from the cloned Streptococcus mutans ldh gene. Several clones were isolated that contained a common 2.9-kb fragment as determined by restriction analysis. Nucleotide sequence analysis revealed a 987-bp open reading frame with extensive homology to Streptococcus thermophilus and S. mutans ldh nucleic acid and amino acid sequences. Expression of the cloned S. bovis ldh gene in Escherichia coli was confirmed by the ability to complement the ldh mutation of E. coli FMJ39, by using an in-gel activity screen and by enzymatic assay. Increased LDH activity was observed in S. bovis JB1 containing the cloned ldh genes on a multicopy plasmid.

Amino Acid Sequence↗
PubMed1997

Carbamazepine-induced lymphadenopathy mimicking Ki-1 (CD30+) T-cell lymphoma.

A 22 year old male receiving carbamazepine for a bipolar affective disorder presented with pyrexia, generalized rash, lymphadenopathy and hepatosplenomegaly. He was thrombocytopenic and liver function tests revealed a hepatitic picture. Lymph node histology suggested a T-cell lymphoma with many large cells possessing blastic features, and expressing CD3 and CD30 antigens. The abnormalities resolved completely within nine weeks of discontinuing carbamazepine, indicating that the presenting lymphadenopathy was secondary to lymphoid activation, ie; a pseudolymphoma rather than a malignant lymphoma. This is the first reported case of carbamazepine-induced lymphadenopathy with CD30+ cells. It illustrates the potential danger of relying too heavily on CD30 positivity as an indicator of malignancy.

Adult↗
PubMed1996

Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. A randomized controlled trial. Nutritional Prevention of Cancer Study Group.

OBJECTIVE: To determine whether a nutritional supplement of selenium will decrease the incidence of cancer. DESIGN: A multicenter, double-blind, randomized, placebo-controlled cancer prevention trial. SETTING: Seven dermatology clinics in the eastern United States. PATIENTS: A total of 1312 patients (mean age, 63 years; range, 18-80 years) with a history of basal cell or squamous cell carcinomas of the skin were randomized from 1983 through 1991. Patients were treated for a mean (SD) of 4.5 (2.8) years and had a total follow-up of 6.4 (2.0) years. INTERVENTIONS: Oral administration of 200 microg of selenium per day or placebo. MAIN OUTCOME MEASURES: The primary end points for the trial were the incidences of basal and squamous cell carcinomas of the skin. The secondary end points, established in 1990, were all-cause mortality and total cancer mortality, total cancer incidence, and the incidences of lung, prostate, and colorectal cancers. RESULTS: After a total follow-up of 8271 person-years, selenium treatment did not significantly affect the incidence of basal cell or squamous cell skin cancer. There were 377 new cases of basal cell skin cancer among patients in the selenium group and 350 cases among the control group (relative risk [RR], 1.10; 95% confidence interval [CI], 0.95-1.28), and 218 new squamous cell skin cancers in the selenium group and 190 cases among the controls (RR, 1.14; 95% CI, 0.93-1.39). Analysis of secondary end points revealed that, compared with controls, patients treated with selenium had a nonsignificant reduction in all-cause mortality (108 deaths in the selenium group and 129 deaths in the control group [RR; 0.83; 95% CI, 0.63-1.08]) and significant reductions in total cancer mortality (29 deaths in the selenium treatment group and 57 deaths in controls [RR, 0.50; 95% CI, 0.31-0.80]), total cancer incidence (77 cancers in the selenium group and 119 in controls [RR, 0.63; 95% CI, 0.47-0.85]), and incidences of lung, colorectal, and prostate cancers. Primarily because of the apparent reductions in total cancer mortality and total cancer incidence in the selenium group, the blinded phase of the trial was stopped early. No cases of selenium toxicity occurred. CONCLUSIONS: Selenium treatment did not protect against development of basal or squamous cell carcinomas of the skin. However, results from secondary end-point analyses support the hypothesis that supplemental selenium may reduce the incidence of, and mortality from, carcinomas of several sites. These effects of selenium require confirmation in an independent trial of appropriate design before new public health recommendations regarding selenium supplementation can be made

Adult↗
PubMed1996

Early clinical experience with the Multi-Link coronary stent.

The Multi-Link coronary stent (Advanced Cardiovascular Systems, Santa Clara, CA) is a balloon expandable stent carved from a stainless steel cylinder and is composed of 12 corrugated rings connected by multiple links. This design gives the stent great flexibility and conformity as well as radial strength. For the 3 month period from November 1995 to January 1996, all patients undergoing stent implantation in our institution were treated with this device, except for vessels smaller than 2.7 mm or larger than 3.7 mm in diameter, left main disease, or those who could not tolerate anticoagulation therapy. Forty patients, with a total of 42 arteries or 44 lesions, were treated with 56 stents, or 1.33 stents per artery. Clinical presentation included stable angina in 13 (32.5%), unstable angina in 24 (60%), acute myocardial infarction in 2 (5%), of whom 1 was in cardiogenic shock, and atypical symptoms with an abnormal thallium stress test in 1 (2.5%). According to the American College of Cardiology/ American Heart Association (ACC/AHA) classification, 8 lesions (18%) were type A, 14 (32%) type B1, 11 (25%) type B2, and 11 (25%) type C. Forty-three lesions (97.7%) were de novo and 1 (2.3%) restenotic. Stent delivery was successful in all patients. Complications included 1 balloon rupture at 7 atm but without sequelae, and 2 patients in whom the coronary guide wire became kinked and locked inside the catheter shaft of the stent delivery system but stent delivery was eventually successful. Mean diameter stenosis was reduced from 76 +/- 13% presenting to 2 +/- 9% poststenting and minimal lumen diameter increased from 0.87 +/- 0.38 to 2.82 +/- 0.34 mm. There were no acute-subacute stent thromboses, bleeding/vascular complications, or major cardiac events such as myocardial infarction, coronary artery bypass surgery, or death during a follow-up period of 2-5 months (mean 3.6 months). In conclusion, our early clinical experience with the Multi-Link stent is very encouraging, with a very high rate of successful delivery and minimal complications.

Adult↗
PubMed1996

Unusual cause of fever and diarrhea in a patient with AIDS. Penicillium marneffei infection.

Penicillium marneffei is an opportunistic pathogen predominantly found in Southeast Asia. Systemic infection of Penicillium marneffei has protean manifestations including fever, weight loss, anaemia, skin lesions, and lymphadenopathy. We report a rare case of penicillium colitis in an AIDS patient who responded successfully to a course of amphotericin B therapy.

AIDS-Related Opportunistic Infections↗
PubMed1996

The effect of a 4-mg preoperative intravenous dose of ondansetron in preventing nausea and vomiting after maxillofacial surgery.

PURPOSE: The efficacy of a preoperative 4-mg dose of ondansetron given intravenously in preventing postoperative nausea and vomiting after maxillofacial surgery was evaluated in a double-blind randomized study. PATIENTS AND METHODS: Sixteen patients had intravenous ondansetron, and an equal number had normal saline as a placebo immediately before induction of anesthesia. After intubation, a nasogastric tube was inserted, and general anaesthesia was induced with thiopentone, suxamethonium, fentanyl, nitrous oxide, enflurane, and vecuronium. Anesthesia lasted more than 1 hour in all patients. Postoperatively, episodes of vomiting were recorded, and nausea was assessed on a visual analog scale at 1, 4, and 24 hours from the time of awakening. RESULTS: Eight patients in the ondansetron group, compared with six in the placebo group, had nausea, and six in the ondansetron group and three in the placebo group vomited. Of the six patients who vomited in the ondansetron group, five vomited more than 8 hours from the injection of ondansetron. No significant adverse effects could be directly attributable to ondansetron. CONCLUSION: Four milligrams ondansetron given intravenously preoperatively was ineffective in controlling postoperative nausea and vomiting after maxillofacial surgery. Possibly, a larger dose or a second dose given 8 hours after the first dose may be effective.

Adult↗
PubMed1996

Flexibility of the NSAID binding site in the structure of human cyclooxygenase-2.

The first crystal structure of human cyclooxygenase-2, in the presence of a selective inhibitor, is similar to that of cyclooxygenase-1. The structure of the NSAID binding site is also well conserved, although there are differences in its overall size and shape which may be exploited for the further development of selective COX-2 inhibitors. A second COX-2 structure with a different bound inhibitor displays a new, open conformation at the bottom of the NSAID binding site, without significant changes in other regions of the COX-2 structure. These two COX-2 structures provide evidence for the flexible nature of cyclooxygenase, revealing details about how substrate and inhibitor may gain access to the cyclooxygenase active site from within the membrane.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Monoclonal gammopathy of unknown significance and malignant paraproteinemia in Hong Kong.

The incidence of multiple myeloma is lower in Southeast Asia than in the West. However, there are few reports on the overall incidence of paraproteinemia and its disease-associations in the Chinese. Therefore, the authors have correlated the laboratory features with the eventual clinical diagnosis in patients with paraproteinemia in a Hong Kong general/teaching hospital. Over 18 months, 1,600 patients were investigated for the presence of paraproteinemia. Paraproteinemia was detected in 157 (10%) patients. In 11 patients, investigations could not be completed. The remaining 146 patients were subjected to detailed clinical, radiologic, and laboratory investigations. Eighty-seven (59.6%) had monoclonal gammopathy of unknown significance (MGUS), 44 (30.1%) myeloma and 15 (10.3%) other lymphoproliferative disorder (LPD). There was no significant difference in the paraprotein concentration, frequency of hypogammaglobulinemia of Bence Jones proteinuria (BJP) or concentration of nonparaprotein immunoglobulin (Ig) between the myeloma and LPD groups. The overall kappa:lambda light chains ratios were 2.9, 1.6 and 3.3 in the MGUS, MM and LPD groups, respectively. Polyclonal Ig elevation was rare with myeloma (4.5%) but was detected in 33% of patients with LPD (P < .02) and 40% of those with MGUS (P < .0001). Biclonal (and one triclonal) gammopathy was detected in 11.5% of patients with MGUS, 11% with LPD and 4.5% with myeloma. In the MGUS group, infection was the commonest associated clinical disorder (29.3%). Moreover, 70% of patients with biclonal gammopathy and MGUS had an infection. Five of 15 patients with LPD had a T-cell malignancy, including 3 lymphomas and 2 large granular cell leukemias. Only one patient had primary systemic amyloidosis. It is concluded that the high frequency of biclonality and its association with infection, of paraproteinemia in association with T-cell malignancy and of kappa light chains in the MGUS and LPD groups are at variance with reports from the West and probably reflect local differences.

Adolescent↗
PubMed1996

Small cell variant of Ki-1 lymphoma associated with myelofibrosis and a novel constitutional chromosomal translocation t(3;4) (q13;q12).

An unusual case of small cell variant of Ki-1 non-Hodgkin's lymphoma diagnosed one year after an original diagnosis of idiopathic myelofibrosis is reported. On the second occasion, the patient presented with fever, lymphadenopathy and hepatosplenomegaly. A lymph node biopsy specimen confirmed a diagnosis of small cell variant of Ki-1 lymphoma. A repeat bone marrow biopsy specimen showed myelofibrosis with no evidence of lymphomatous infiltration, but cytogenetic studies on blood, bone marrow and skin fibroblasts revealed a novel chromosomal translocation t(3,4)(q13;q12).

Chromosome Mapping↗