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Biomedical subjects

D Church

Publications and source records attributed to D Church.

At least 19 recordsLinked to original sources
PubMed2000

Time estimation by pigeons on a fixed interval: the effect of pre-feeding.

Pigeons well trained on a fixed interval 10-s schedule of reinforcement were tested on the peak procedure. In a successive conditions design, they were either pre-fed or not in the experimental setting. Pre-feeding decreased the rate of responding. It also led to a maximum rate of responding that occurred 2-3 s later than in the control condition, where the maximum occurred at the usual time of reinforcement. The shift in peak time in response to pre-feeding shows that peak time may not be a pure measure of timing. The results are also interpreted in terms of timing theories.

Journal Article↗
PubMed2000

Short-course moxifloxacin therapy for treatment of acute bacterial exacerbations of chronic bronchitis. The Bronchitis Study Group.

Chronic bronchitis is common among adults and infectious exacerbations contribute considerably to morbidity and mortality. We aimed to compare the safety and efficacy of moxifloxacin to clarithromycin for the treatment of patients with acute bacterial exacerbations of chronic bronchitis (ABECB) using a prospective, randomized, double-blind, parallel group trial. Between November 21, 1996 and April 7, 1998, 936 patients with acute exacerbations of chronic bronchitis (AECB) were enrolled at 56 centers across the United States of which 491 (52%) had ABECB (i.e. pretherapy pathogen). Patients were randomized to either oral moxifloxacin 400 mg administer once daily, for either 5 or 10 days, or clarithromycin 500 mg bid for 10 days. For the purpose of study blinding, the patients taking moxifloxacin received placebo to maintain uniform dosing. The main outcome measures were bacteriological response at the end of therapy (post-therapy days 0-6) and follow-up (7-17 days post-therapy) visits, as well as overall clinical response, clinical response at the end of therapy and clinical response at follow-up. Two patient populations were analyzed: efficacy-valid (i.e., those with a pretherapy pathogen) and intent-to-treat (i.e., all subjects that took drug). In 420 efficacy valid patients with a pretherapy organism, overall clinical resolution was 89% for 5 days moxifloxacin vs. 91% for 10 day moxifloxacin vs. 91% for 10 day clarithromycin. Bacteriological eradication rates at the end of therapy were 94% and 95% for 5-day moxifloxacin and 10-day moxifloxacin, respectively, and 91% for the clarithromycin group. Eradication rates at follow-up were 89% and 91% for 5-day moxifloxacin and 10-day moxifloxacin respectively, and 85% for the clarithromycin group. Among 926 intent-to-treat patients (312 5-day moxifloxacin, 302 10-day moxifloxacin and 312 clarithromycin), drug-related events were reported for 26%, 30% and 35%, respectively. Moxifloxacin 400 mg once daily, as a 5 or 10 day regimen, was found to be clinically and bacteriologically equivalent to 10 day clarithromycin for the treatment of ABECB. Given its favorable safety and tolerability profile, moxifloxacin administered once daily for 5 days may be as effective and a more convenient treatment than a standard course of clarithromycin for patients with ABECB.

Acute Disease↗
PubMed2000

Efficacy and safety of ten day moxifloxacin 400 mg once daily in the treatment of patients with community-acquired pneumonia. Community Acquired Pneumonia Study Group.

Community-acquired pneumonia (CAP) remains a common and serious illness with approximately 2-4 million cases reported annually. Management of CAP is therapeutically challenging due to the increasing prevalence of penicillin- and macrolide-resistant pneumococci and beta-lactamase producing Haemophilus influenzae, as well as the increased recognition of 'atypical' pathogens, such as Chlamydia pneumoniae and Mycoplasma pneumoniae, and the frequent need for empiric therapy. We aimed to evaluate the safety and efficacy of moxifloxacin in the treatment of patients with CAP. To do this we carried out a prospective, uncontrolled, non-blind, Phase III clinical trial, in 27 U.S. centers. Patients included in the study were over 18 years of age with signs and symptoms of CAP confirmed by evidence of a new or progressive infiltrate on chest radiograph. The intervention used was moxifloxacin 400 mg PO once daily for 10 days. Sputum samples were collected pretherapy for Gram stain and culture for typical organisms. Culture and serological testing for Chlamydia pneumoniae and Mycoplasma pneumoniae was also performed. Susceptibility to moxifloxacin was determined by disk diffusion and MIC. Clinical and bacteriological responses were determined at the end of therapy (0-6 days post-therapy), follow-up (14-35 days post-therapy) and overall (end of therapy plus follow-up). Analyses were performed on both valid for efficacy and intent-to-treat populations. The primary efficacy variable was overall clinical resolution. Of 254 patients enrolled in the Study, 196 patients were included in the efficacy analyses. The majority of patients were male (58%) and Caucasian (85%) with a mean age of 49 years (range: 18 to 85 years). Only 3% of patients were hospitalized pretherapy. The most common pretherapy organisms identified, by culture or serology, in the valid for efficacy population (i.e. 147 organisms among 116 patients), were: Chlamydia pneumoniae (n=63; 54%), Mycoplasma pneumoniae (n=29; 25%), Streptococcus pneumoniae (n=14; 12%) and Haemophilus influenzae (n=13; 10%). End of therapy, follow-up and overall clinical resolution rates for the valid for efficacy population were 94%, 93% and 93%, respectively. The 95% CI for the overall clinical resolution rate was 88.1%, 95.9%. The overall bacteriological response for patients diagnosed by culture or serological criteria, was 91% (95% CI=84%, 96%). For patients who only met serological criteria for infection, the overall bacteriological response was 94% (60/64). Bacterial response rates for the four most commonly isolated pathogens were: 89% (56/63) for C. pneumoniae, 93% (27/29) for M. pneumoniae, 93% (13/14) for S. pneumoniae and 85% (11/13) for H. influenzae. Drug-related adverse events were reported in 33% (85/254) of moxifloxacin-treated patients. Nausea (9%), diarrhea (6%) and dizziness (4%) were the most commonly reported adverse events. Atypical organisms were isolated in high frequency among patients with CAP. Moxifloxacin 400 mg once daily for 10 days was effective and well-tolerated in the treatment of these adult patients with CAP. Moxifloxacin offers an effective treatment alternative for CAP due to both typical and atypical bacterial pathogens.

Adolescent↗
PubMed2000

The safety and efficacy of short course (5-day) moxifloxacin vs. azithromycin in the treatment of patients with acute exacerbation of chronic bronchitis.

Chronic bronchitis is common among adults and infectious exacerbations contribute considerably to morbidity and mortality. We aimed to compare the safety and efficacy of moxifloxacin to azithromycin for the treatment of patients with acute exacerbations of chronic bronchitis (AECB) of suspected bacterial origin. Between October 1998 and April 1999, 567 patients with AECB were enrolled at 37 centers across the United States and Canada of which 280 (49%) had acute bacterial exacerbation of chronic bronchitis (i.e. pretherapy pathogen). Patients were randomized to either oral moxifloxacin 400 mg administered once daily for 5 days or azithromycin for 5 days (500 mg qd x 1, then 250 mg qd x 4). For the purpose of study blinding, all patients received encapsulated tablets. The main outcome measure was clinical response at the test-of-cure visit (14-21 days post-therapy). Secondary measures included bacteriologic response and a time-course of bacteriological eradication (one center only). Three patient populations were analysed for efficacy: clinically-valid, microbiologically-valid (i.e. those with a pretherapy pathogen), and intent-to-treat (i.e. received at least one dose of study drug). For the efficacy-valid group, clinical response at the test-of-cure visit was 88% for patients in each treatment group. In 237 microbiologically-valid patients, corresponding clinical resolution rates were 88% for 5-day moxifloxacin vs. 86% for 5-day azithromycin. Bacteriological eradication rates at the end of therapy were 95% for 5-day moxifloxacin and 94% for the azithromycin group. Corresponding eradication rates at the test-of-cure visit were 89% and 86%, respectively. Of note, eradication rates at test-of-cure for Haem. philos influenzae and H. parainfluenzae for moxifloxacin were 97% and 88% compared to 83% and 62% respectively for azithromycin. Among 567 intent-to-treat patients (283 moxifloxacin and 284 azithromycin), drug-related events were reported for 22% and 17%, respectively. Diarrhea and nausea were the most common drug-related events reported in each treatment group. Moxifloxacin 400 mg once daily for 5 days was found to be clinically and bacteriologically equivalent to 5-day azithromycin for the treatment of AECB of proven bacterial etiology. Given its excellent in-vitro activity, especially against antibiotic-resistant respiratory pathogens, and its acceptable safety profile, moxifloxacin should be considered an effective alternative therapy for patients with AECB of suspected bacterial origin.

Acute Disease↗
PubMed2000

Quantitative gram stain interpretation criteria used by microbiology laboratories in Alberta, Canada.

Microbiology laboratories in Alberta, Canada, were surveyed to determine the quantitative interpretive criteria used to routinely read and report Gram stains. There was a wide variability in the quantitative reporting criteria cited for both cells and bacteria, with only 11 of 32 (34.4%) laboratories surveyed using the criteria recommended by the external proficiency-testing program. Lack of standardized criteria not only poses a problem in the grading of proficiency testing results but may also impact the quality of patient care.

Alberta↗
PubMed2000

Moxifloxacin versus cephalexin in the treatment of uncomplicated skin infections.

The efficacy and safety of oral moxifloxacin (400 mg once daily, 7 days) versus cephalexin (500 mg three times daily, 7 days) were compared in a prospective, multicentre, randomised, double-blind trial in 401 adults with uncomplicated skin infections. Clinical outcome was evaluated in 351 patients. Moxifloxacin proved to be as effective as cephalexin both clinically (90% versus 91%, respectively) and bacteriologically in eradicating the most frequently isolated pathogen Staphylococcus aureus (92% and 93%, respectively). Moxifloxacin was more effective than cephalexin in eliminating Streptococcus spp. (90% and 82%, respectively). Drug-related adverse events were comparable in both treatment groups with the most frequently reported being nausea in the moxifloxacin-treated patients and headache in the cephalexin-treated patients. Medication was discontinued due to unwanted reactions in 3% of the moxifloxacin- and 4% of the cephalexin-treated patients. Moxifloxacin, 400 mg once daily for 7 days, is as safe and effective as cephalexin 500 mg three times daily for 7 days in the treatment of uncomplicated skin infections.

Adolescent↗
PubMed1999

Surface ultrastructure of pit organ, spectacle, and non pit organ epidermis of infrared imaging boid snakes: A scanning probe and scanning electron microscopy study.

Boid snakes possess unique infrared imaging pit organs. The ultrastructure of the surfaces of these organs scatter or reflect electromagnetic radiation of specific wavelengths. Pit organ epidermal surfaces of boid snakes are covered with arrays of pore-like structures called micropits. In order to determine the dimensions of this complicated surface structure, we have performed the first ultrastructural analysis on snake epidermis by high-resolution microscopy techniques. Using scanning probe microscopy and scanning electron microscopy, we found that the epidermis of pit organ, maxillary non pit organ, spectacle, and ventral scales contain arrays of micropits. These scale surfaces also contain major surface features of overlapping plate-like structures. Pit organ micropits averaged 319 nm in diameter and 46 nm in depth and were spaced an average of 808 nm from each other. These micropits were significantly deeper, of greater diameter, and spaced at greater distances apart than those of the other scales. Plate structures of the pit organs had a mean distance between plates of 3.5 microm and a mean plate step height of 151 nm. These differences serve to strengthen the argument that arrays of micropit and plate surface structures function as spectral filters or anti-reflective coatings with respect to incident electromagnetic radiation.

Animals↗
PubMed1999

Efficacy of suramin against human prostate carcinoma DU145 xenografts in nude mice.

PURPOSE: Toward developing a model to study the mechanism of action of suramin against prostate cancer, we identified the effect of suramin on the growth of xenografts of the androgen-independent human prostate carcinoma DU145 cell line and our subline of suramin-resistant (SR) DU145 cells which are less responsive to suramin in vitro. METHODS: Athymic nude mice bearing DU145 or SR DU145 xenografts were treated intraperitoneally (IP) once weekly with normal saline (vehicle control) or suramin in normal saline. For data analysis mice were grouped as follows: 0 mg/kg (controls), < 210 mg/kg, 210 to 260 mg/kg, or >260 mg/kg suramin. RESULTS: The growth of DU 145 xenografts was slowed by treatment with 210 to 260 mg/kg suramin IP once weekly: differences in tumor volume for the 210 to 260 mg/kg group compared with the control group on days 29 and 57 showed growth inhibited by 43% and 55%, respectively. At the same time, growth of SR DU 145 xenografts generally was not slowed by suramin treatment at any dose, but appeared to be enhanced to some degree by all doses of suramin during the typical slower initial growth phase of xenografts of this cell line: differences in tumor volume compared with control on day 29 showed growth enhanced by 100% to 342%. Mice treated with 210 to 260 mg/kg maintained nadir suramin plasma levels near our clinically relevant target of 1 x 10(-4) M. CONCLUSIONS: Suramin, without concomitant corticosteroid therapy, was effective in slowing the growth of DU145 xenografts in nude mice at clinically relevant plasma suramin levels. The data showing efficacy for DU145 xenografts was supported by the lack of efficacy at the same time for xenografts of cells known to be less responsive to suramin in vitro, i.e. the SR DU145 cells, at similar doses and nadir plasma suramin levels. In discussions on the utility of suramin our data should be considered as support for continuing the study of suramin in the treatment of advanced, androgen-independent prostate cancer.

Animals↗
PubMed1999

Cystic fibrosis clinical score: a new scoring system to evaluate acute pulmonary exacerbation.

Although pulmonary function tests are used to evaluate acute changes in obstructive airway disease in patients with cystic fibrosis (CF), these tests are relatively difficult to perform in young children or severely ill patients and may be costly. Other standard tests (eg, the Shwachman-Kulczycki and National Institutes of Health [NIH] scoring systems) evaluate disease severity and predict prognosis but do not measure day-to-day changes in clinical status. They thus provide little information for assessing the start of acute pulmonary exacerbation. Alternative scoring systems are needed to better identify the start of pulmonary exacerbation, to predict worsening or improvement of respiratory function after intervention, and to distinguish the scores from illness severity scores. This study was undertaken to compare a new 10-component, 50-point-maximum, acute clinical scoring system with forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) variables in children with CF who were experiencing an acute pulmonary exacerbation before antimicrobial therapy was initiated and until the end of therapy. One hundred thirty children aged 5 to 17 years (median age, 11 years) had a median NIH score of approximately 64 (range, 39 to 85) at admission. The cystic fibrosis clinical score (CFCS) at admission was found to correlate highly with the modified NIH score at study entry (r = -.68, P = 0.0001 ). The total CFCS at entry was correlated inversely with both FEV1 (r = -.57, P = 0.0001) and FVC (r = -.55, P = 0.0001) measurements; crackles, dyspnea, sputum production, and respiratory rate were the 4 components most highly associated with either pulmonary function variable. The change in total CFCS from start to end of antimicrobial therapy also correlated with changes in FEV1 (r = -.31, P = 0.0016) and change in FVC (r = -.47, P = 0.0001). Clinical improvement was observed in all patients at the end of therapy, and only 1 patient had an increase in total CFCS. Patients who experienced clinical relapse had a mean increase of 8.5 points in the CFCS from end of therapy to 2- to 4-week follow-up, indicating worsening signs and symptoms of acute exacerbation. These data suggest that the CFCS is a predictive and optional surrogate of pulmonary function in assessing the health of patients with CF. Following further validation, this scoring system could be used to evaluate health status in the outpatient setting, the need for hospitalization, and subsequent improvement during an acute pulmonary exacerbation, as well as to compare the efficacy of therapeutic regimens.

Adolescent↗
PubMed1999

Comparison of moxifloxacin and cefuroxime axetil in the treatment of acute maxillary sinusitis. Sinusitis Infection Study Group.

The aim of this prospective, multicenter, randomized, double-masked clinical trial was to compare the efficacy and safety of moxifloxacin with those of cefuroxime axetil for the treatment of community-acquired acute sinusitis. Five hundred forty-two adult patients with symptoms and radiographic evidence of acute maxillary sinusitis received a 10-day oral regimen of either moxifloxacin (400 mg once daily) or cefuroxime axetil (250 mg twice daily). Acute signs and symptoms at presentation had lasted >7 days but <4 weeks. Clinical response at the end of therapy (7 to 14 days after treatment) was the primary efficacy variable. Four hundred fifty-seven of the patients (223 moxifloxacin, 234 cefuroxime axetil) were included in the clinical efficacy analysis. Moxifloxacin was found to be similar in effectiveness to cefuroxime axetil at the end-of-therapy visit (90% vs. 89%, respectively; 95% confidence interval, -5.1% to 6.2%). Clinical relapse at the follow-up visit was reported for only 8 patients (3 moxifloxacin, 5 cefuroxime axetil). No clinically significant differences were observed with respect to the number of patients experiencing a successful clinical response based on demographic or infection characteristics. Five of the 542 enrolled patients were lost to follow-up. Of the 537 patients in the intent-to-treat population, drug-related adverse events were reported in 37% of moxifloxacin-treated patients and in 26% of cefuroxime axetil-treated patients (P = 0.006). Adverse-event profiles were comparable in the 2 treatment groups, with the exception of nausea, which was reported by 11% of moxifloxacin-treated patients compared with 4% of cef uroxime axetil-treated patients (P = 0.003). In this study, moxifloxacin was as effective as cefuroxime axetil in the treatment of community-acquired acute sinusitis.

Acute Disease↗
PubMed1999

In vitro activity of several antimicrobial agents against 1003 isolates of Streptococcus pyogenes collected from Western Canada.

Streptococcus pyogenes is a common pathogen which may be associated with significant morbidity and mortality. Recent information is not readily available, in Canada, regarding the susceptibility of clinical isolates to penicillin, extended spectrum and/or newer agents. We collected and tested 1003 isolates of S. pyogenes to seven antimicrobial agents and found the following susceptibility rates: azithromycin 97%, ceftriaxone 100%, ciprofloxacin 99.4%, clarithromycin 98.5%, clindamycin 99.9%, erythromycin 96.5% and penicillin 100%. These results indicate that antimicrobial resistance is not yet a problem of S. pyogenes in Canada.

Adolescent↗
PubMed1999

Evaluation of the leukocyte esterase and nitrite urine dipstick screening tests for detection of bacteriuria in women with suspected uncomplicated urinary tract infections.

A positive dipstick urinalysis (i.e., leukocyte esterase test and/or nitrite test) did not reliably detect significant bacteriuria in 479 ambulatory women with suspected uncomplicated urinary tract infection; 18.9% of the urine samples that demonstrated significant bacteriuria would have been rejected by the laboratory based on a negative urinalysis screen.

Adolescent↗
PubMed1998

Predictors and outcome of admission for invasive Streptococcus pneumoniae infections at a Canadian children's hospital.

Rates of admission for invasive Streptococcus pneumoniae infection in children vary considerably between institutions. We performed a retrospective study to investigate factors used in the decision to admit patients with invasive S. pneumoniae infection to Alberta Children's Hospital. Of 254 patients who were initially assessed in the emergency department, 38.2% were admitted to the hospital. Significant risk factors for admission as determined by a logistic regression model included murmur (odds ratio [OR], 18.98; 95% confidence interval [CI], 4.08-88.23), focal infection (OR, 11.41; 95% CI, 5.07-25.67), and older age (OR, 2.72; 95% CI, 1.03-7.17). Higher hemoglobin level (OR, 0.96; 95% CI, 0.93-0.99) and temperature of > 38.5 degrees C (OR, 0.39; 95% CI, 0.18-0.85) were associated with a lower risk of admission. Two patients died (case-fatality rate, 0.7%). Despite the low rate of admission for invasive S. pneumoniae infections at our hospital, the mortality rate was comparable with those at institutions with higher rates of admission, thus suggesting that the factors we identified may be useful in deciding whether to admit patients with (or who are at high risk for) invasive S. pneumoniae infections.

Canada↗
PubMed1998

Renal clearance, tissue distribution, and CA-125 responses in a phase I trial of suramin.

Suramin was administered to 49 patients in a Phase I cancer trial with real-time pharmacokinetic monitoring and dose individualization to achieve targeted mean plasma concentrations of 210 and 155 mg/liter during the 7-day period between days 15 and 22. Pharmacokinetic sampling after doses on days 1, 3, 5, and 8 was used to modify weekly suramin doses, beginning on day 15, in an attempt to achieve specific averaged plasma concentrations of 210 and 155 mg/liter. A 200-mg test dose was not effective in prospectively determining individual pharmacokinetic parameters and dosage requirements. Patients with peak plasma suramin concentrations in excess of 350 mg/liter may be more likely to experience neurotoxicity (P = 0.06), but there was no statistically significant effect of peak suramin concentration or of cumulative dose. Biopsy and autopsy tissue samples demonstrated low penetration of suramin into brain tissue and muscle but good penetration into prostate and other visceral organs. Prospective use of surrogate substrates for CYP1A2, CYP3A3/4, and CYP2D6 showed no consistent effect of suramin on these enzymes. Although a correlation between creatinine clearance and suramin renal clearance was found (r2 = 0.38; P < 0.00005), there was no correlation between creatinine clearance and total suramin clearance (P = 0.21). No suramin dose modification for renal or hepatic dysfunction can be supported at this time. Three of four ovarian cancer patients demonstrated a drop in CA-125 serum concentrations during suramin treatment.

Adult↗