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Biomedical subjects

D Rollins

Publications and source records attributed to D Rollins.

16 recordsLinked to original sources
PubMed2001

Knowledge, attitudes and practices regarding evidence-based medicine and outcome assessment: a survey of British Columbia cataract surgeons.

BACKGROUND: While the advantages of practising evidence-based medicine are well-documented, it is frequently suggested that doctors' attitudes are a major roadblock to its implementation. We carried out a survey to determine the knowledge, attitudes and practices of British Columbia cataract surgeons regarding evidence-based medicine and outcome assessment. METHODS: The survey was conducted in the spring of 1999. The study population was drawn from the directory of the British Columbia College of Physicians and Surgeons. A 16-item questionnaire designed to elicit the knowledge of, attitudes toward and use of evidence-based medicine and outcome assessment was sent to all surgeons performing cataract surgery in British Columbia. RESULTS: Of the 103 eligible participants, 70 (68%) returned completed questionnaires. Surgeons affiliated with the University of British Columbia were more likely to respond than those not affiliated with the university (81% vs. 58%) (p < 0.05). Most surgeons (89%) viewed the responsibility of monitoring quality of care as primarily their own. Although 79% of the respondents felt that outcome assessment is an effective method for determining quality of care, less than half (49%) reported that they routinely include some form of outcome assessment in their clinical practice. There was wide variation in the respondents' understanding of the nature of outcome assessment and evidence-based medicine. Respondents professed little inclination or motivation to committing time or resources to an outcome program. They also expressed concerns over the use of outcome data for external management activities. INTERPRETATION: Cataract surgeons in British Columbia clearly appreciate the advantages of outcome assessment, but translation of this understanding into practice is limited. There appears to be a need for further education on outcome assessment and evidence-based medicine through academic bodies and professional societies.

British Columbia↗
PubMed2001

Interpreting physical evidence of predation on hoofstock and management alternatives for coping with predators.

Predation on domestic and wild hoofstock is a serious management constraint, especially for small ruminants and neonates. Diagnosis of the species of predator responsible for livestock losses relies on the ability to interpret direct and indirect evidence of predation. This article summarizes the physical evidence associated with depredation events and includes the most common species of predators encountered in North America. Management alternatives for coping with predators are discussed.

Animal Husbandry↗
PubMed1998

Spatial changes in the transmembrane potential during extracellular electric stimulation.

The purpose of this study was to determine the spatial changes in the transmembrane potential caused by extracellular electric field stimulation. The transmembrane potential was recorded in 10 guinea pig papillary muscles in a tissue bath using a double-barrel microelectrode. After 20 S1 stimuli, a 10-ms square wave S2 shock field with a 30-ms S1-S2 coupling interval was given via patch shock electrodes 1 cm on either side of the tissue during the action potential plateau. Two shock strengths (2.1+/-0.2 and 6.5+/-0.6 V/cm) were tested with both shock polarities. The recording site was moved across the tissue along fibers with either 200 micrometer (macroscopic group [n=5], 12 consecutive recording sites over a 2. 2-mm tissue length in each muscle) or 20 micrometer (microscopic group [n=5], 21 consecutive recording sites over a 0.4-mm tissue length in each muscle) between adjacent recording sites. In the macroscopic group, the portion of the tissue toward the anode was hyperpolarized, whereas the portion toward the cathode was depolarized, with 1 zero-potential crossing from hyperpolarization to depolarization present near the center of the tissue. In the microscopic group, only 1 zero-potential crossing was observed in the center region of the tissue, whereas, away from the center, only hyperpolarization was observed toward the anode and depolarization toward the cathode. Although these results are consistent with predictions from field stimulation of continuous representations of myocardial structure, ie, the bidomain and cable equation models, they are not consistent with the prediction of depolarization-hyperpolarization oscillation from representations based on cellular-level resistive discontinuities associated with gap junctions, ie, the sawtooth model.

Animals↗
PubMed1995

Quantitative analysis of THC, 11-OH-THC, and THCCOOH in human hair by negative ion chemical ionization mass spectrometry.

A sensitive and specific method was developed for the quantitative analysis of delta9-tetrahydrocannabinol (THC), 11 -hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH) in human hair. Deuterated internal standards were added to hair samples, and samples were digested overnight in 1 N NaOH at 37 degrees C. Digest solutions were extracted with a liquid-liquid extraction procedure, which was previously developed in our laboratory for the analysis of plasma and whole blood. Derivatized extracts were analyzed on a Finnigan 4500" mass spectrometer in negative ion chemical ionization mode using methane as the reagent gas, hydrogen as the carrier gas, and a Restek Rtx 200-15M-0.25-microm capillary column. The assay was linear up to 50 ng/mg hair (r, 0.99) for all three compounds and was capable of detecting 10 pg THC and THCCOOH and 100 pg 11-OH-THC on column. The intra-assay precision ranged from 2.1 to 11.2% for the three analytes; the interassay precision ranged from 4.4 to 13.0%. The method was used to detect and quantitate the presence of THC, 11-OH-THC, and THCCOOH in human hair obtained from eight regular users of cannabis. THC, but not 11-OH-THC or THCCOOH, was detectable in the hair shaft above the assay limit of quantitation. Four laboratory wash procedures were also evaluated for their effect on the measured concentration of THC in hair. in seven of eight subjects, a methylene chloride wash procedure substantially reduced the measured THC concentration by up to 50%. The gas chromatographic-mass spectrometric assay is currently being used to support pharmacokinetic studies of drug disposition into the hair of humans and animals.

Boranes↗
PubMed1994

Improving antibiotic delivery time to pneumonia patients: continuous quality improvement in action.

A multidisciplinary team simplified the process of antibiotic delivery to patients admitted with community-acquired pneumonia and successfully implemented key changes that resulted in improved clinical practice and patient satisfaction at Providence Medical Center. Within 6 months of implementing an emergency room preadmission procedure, an antibiotic treatment protocol, and a sputum collection protocol, the average antibiotic initiation time dropped from 6.8 hours to 3.6 hours. Recommendations made for antibiotic selection and dosing led to a cost savings of over $109,000 per year. Highlighted in this article are several quality improvement tools, as well as practical tips and advice on effective team building.

Anti-Bacterial Agents↗
PubMed1993

Colonization of broiler chickens by waterborne Campylobacter jejuni.

Chickens on a broiler farm in southern England were found to be colonized with Campylobacter jejuni of a single serotype, Lior 1 Penner 4. The farm was the sole supplier of a local slaughterhouse associated with a campylobacter outbreak in 1984 caused by this serotype. The serotype persisted on the farm for at least 18 months after the outbreak; its prevalence in the human population served by the farm remained high until it disappeared from the farm in 1986. The possible sources and routes of transmission of C. jejuni to the broilers on the farm were investigated. The results showed that vertical transmission, feed, litter, small mammals, and environmental or airborne cross-contamination between sheds or successive crops could be excluded as persistent sources of C. jejuni. The predominant source of C. jejuni on the farm was shown to be the water supply. Direct microscopy and fluorescent antibody methods revealed presumptive campylobacters throughout the farm's water system. Campylobacter-free chickens raised in an animal house and given water from the farm supply became colonized with the serotype of C. jejuni endemic on the farm (Lior 1 Penner 4). An intervention program based on water chlorination, shed drinking system cleaning and disinfection, and withdrawal of furazolidone from feed reduced the proportion of birds colonized with campylobacter from 81 to 7% and was associated with a 1,000- to 10,000-fold reduction in campylobacters recoverable from the carcasses. Two months after the end of the intervention program colonization of the birds returned to high levels (84%), indicating that there was a temporal association between intervention and reduced colonization with C. jejuni. Investigations continue to establish the general applicability of these findings.

Animal Feed↗
PubMed1991

Defibrillation with low voltage using a left ventricular catheter and four cutaneous patch electrodes in dogs.

The purpose of this study was to determine a lower limit of defibrillation thresholds (DFTs) that could be used to evaluate nonthoracotomy lead configurations for implantable defibrillators. A lead configuration that consisted of a left ventricular catheter and four circumferential cutaneous patches was tested because it was hypothesized to create a relatively uniform electric field for defibrillation. In eight anesthetized dogs, three 8F defibrillating catheters with 6 cm platinum clad titanium tips were inserted into the right ventricle (R), right ventricular outflow tract (O), and left ventricle (L). Four cutaneous patch electrodes (4P), each with a surface area of 42 cm2, were placed on the left lateral, right lateral, anterior and posterior thorax. DFTs for ten lead configurations, consisting of different combinations of these electrodes, were evaluated. DFTs were determined by using a modified Purdue technique and applying a single capacitor biphasic shock with both phases 6 ms in duration after 15 sec of electrically induced fibrillation. The L(-)----4P+ configuration produced a lower DFT than R(-)----4P+ (3.2 +/- 1.6 J vs 8.0 +/- 4.2 J, P less than 0.001) with reduced current (2.6 +/- 0.7 A vs 4.1 +/- 1.2 A, P less than 0.001). Lowering the impedance by a mean of 40%, configurations that used four patches produced lower DFTs than those that used a single left lateral patch. The use of an O catheter produced lower DFTs only when used in conjunction with an R catheter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Lower extremity vasospasm associated with ischemic neuropathy, dermal fibrosis, and digital gangrene in a patient with carcinoid syndrome.

Bilateral lower extremity vasospasm associated with severe pain and hyperesthesias in the legs, and digital gangrene in both feet developed in a 50-year-old man with carcinoid syndrome. Nifedipine and chemical lumbar sympathectomy were partially effective in relieving the vasospasm. Electromyographic findings were consistent with ischemic neuropathy. A skin biopsy specimen showed striking dermal fibrosis. Serotonin and other vasoconstrictor substances released from the tumor may be responsible for the vasospasm, the dermal sclerosis, and the ischemic neuropathy. The early use of lumbar sympathectomy in patients with lower extremity vasospasm may prevent these irreversible ischemic complications.

Bronchial Neoplasms↗
PubMed1987

Popliteal-to-tibial in situ saphenous vein bypass for limb salvage in diabetic patients.

This study has summarized our results with popliteal-tibial in situ saphenous vein bypass in 26 patients, 25 of whom were diabetic, over a 2 year period. Both above- and below-knee popliteal inflow sites were used for bypass of limb-threatening ischemia. Distal calf or pedal outflow sites were required in all but two patients who had sequential bypass performed to tibial sites. Postoperative ankle-brackial indices were calculated. Eleven patients had transcutaneous mapping surrounding the pedal skin envelope injuries. The mean lowest and highest transcutaneous oxygen values have been reported as a guide to successful healing.

Adult↗
PubMed1987

B-mode ultrasonic imaging in the preoperative evaluation of saphenous vein.

This prospective study was undertaken to determine if B-mode ultrasonic imaging of the greater saphenous vein can provide reliable information about anatomy, sites of valves, and location of major tributaries or duplicate systems. Preoperative ultrasonic imaging was performed on 15 consecutive patients prior to in situ saphenous bypass. The findings of the ultrasonic evaluations were compared with the intraoperative findings. Preoperative assessment of the greater saphenous vein was performed with a high resolution real-time B-mode ultrasonic imager. The procedure was performed with the patient seated with the leg extended. The saphenous vein was imaged starting at the ankle. A waterproof pen was used to mark the vein. The locations of valves and tributary vessels were marked and the diameter of the saphenous vein was recorded. These results were compared with operative findings. In all 15 patients, the saphenous vein was imaged. There was 100 per cent accuracy in the detection and location of valve sites. In one patient, the proximal portion of the vein was thrombosed and this was detected by the B-mode scan. There was exact correlation in 14 of 15 limbs (93%). The one error was due to the examiners' failure to identify a triple venous system; only a double venous system was identified by scan in this patient. The actual venous diameter was consistently within 0.5 mm of that measured by the ultrasound imager. In all patients, the ultrasound image demonstrated the correct anatomic location and size of the vein. In conclusion, B-mode ultrasonic imaging provides an accurate description of the anatomy of the saphenous vein, without the morbidity associated with contrast venography.

Aged↗
PubMed1986

Metabolism of 14C-estazolam in dogs and humans.

14C-Estazolam (2 mg) administered orally to dogs and human subjects was rapidly and completely absorbed with peak plasma levels occurring within one hour. In humans, plasma levels peaked at 103 +/- 18 ng/ml and declined monoexponentially with a half-life of 14 h. The mean concn. of estazolam in dog plasma at 0.5 h was 186 ng/ml. Six metabolites were found in dog plasma at 0.5 and 8 h, whereas only two metabolites were detected in human plasma up to 18 h. Metabolites common to both species were 1-oxo-estazolam (I) and 4-hydroxy-estazolam (IV). Major metabolites in dog and human plasma were free and conjugated 4-hydroxy-estazolam; the concn. were higher in dogs. After five days, 79% and 87% of the administered radioactivity was excreted in dog and human urine, respectively. Faecal excretion accounted for 19% of the dose in dog and 4% in man. Eleven metabolites were found in the 0-72 h urine of dogs and humans; less than 4% dose was excreted unchanged. Four metabolites were identified as: 1-oxo-estazolam (I), 4'-hydroxy-estazolam (II), 4-hydroxy-estazolam (IV) and the benzophenone (VII), as free metabolites and glucuronides. The major metabolite in dog urine was 4-hydroxy-estazolam (20% of the dose), while the predominant metabolite in human urine (17%) has not been identified, but is likely to be a metabolite of 4-hydroxy-estazolam. The metabolism of estazolam is similar in dog and man.

Administration, Oral↗
PubMed1983

Phagocytic, lambda light chain, plasma cell myeloma.

A case of phagocytic, lambda light chain, plasma cell myeloma was characterized by its clinical, morphologic, cytochemical, immunologic, and cell kinetic features. A 40-year-old man presented with Coombs-negative hemolytic anemia, hepatosplenomegaly, lytic bone lesions, lambda light chain monoclonal gammopathy, and infiltration of the bone marrow by dysplastic plasma cells, 10% of which demonstrated phagocytosis of erythroid cells. Electron microscopy demonstrated myeloma cells with prominent cytoplasmic microfilaments and erythroid cells in intracytoplasmic vacuoles. The myeloma cells did not phagocytose staphylococci in vitro. Phagocytic and nonphagocytic myeloma cells were tartrate-sensitive, acid-phosphatase positive, alpha-napthyl butyrate esterase negative, and did not form E rosettes or EAox(IgG) rosettes. The tumor cells were Tdt, Ia antigen, and SIg negative. Immunofluorescent staining for cytoplasmic light chains showed a monoclonal lambda pattern in nonphagocytic myeloma cells, and a probable monoclonal lambda pattern in phagocytic myeloma cells. These findings characterize the neoplasm as a monoclonal proliferation of differentiated plasma cells with the capability of erythrophagocytosis. Erythrophagocytosis by myeloma cells may have been responsible for the hemolytic anemia. The tritiated thymidine labeling index (LI%) was high (8%), suggesting a poor prognosis, despite a dramatic initial response to chemotherapy.

Adult↗
PubMed1983

Advances in the hemodialysis management of phenobarbital overdose.

When a comatose man requiring ventilatory support for acute ingestion of phenobarbital was admitted to the University of Utah Hospital, he was managed by a multispecialty team, which included a nephrologist and a clinical pharmacologist. Since the patient could not be moved to the dialysis unit, a mobile dialysis machine was used. A negative-pressure adapter was used in conjunction with a batch-type dialysis machine to create a single-pass dialysate delivery system. Blood was delivered to the dialyzer and returned to the patient through bilateral femoral catheters that had been placed percutaneously. Pharmacokinetic studies were performed and compared to the disappearance of phenobarbital by conservative measures alone after the patient had awakened and dialysis was discontinued.

Adult↗
PubMed1981

Glutathione and gamma-glutamyl cycle enzymes in human fetal liver.

Human fetal and adult liver were found to have similar concentrations of acid soluble sulfhydryl (SH) groups (7.4 mmol/kg) in the same range as is found in adult mouse and rat liver. The concentration was 4-fold higher than in human fetal adrenal gland tissue. Methods specific for glutathione (GSH) associated SH groups revealed that the postmortem levels of GSH is very low (0.4 mmol/kg) in relation to total SH groups. In contrast, the levels of cysteine were high (2.8 mmol/kg), indicating a rapid cleavage of GSH. Only negligible amounts of gamma-glutamylcysteine and cysteinylglycine were measured. Our findings may be explained by high fetal activity of gamma-glutamyl transpeptidase (which metabolizes GSH) that has been documented previously both in man and in experimental animals. High activities of the two GSH-synthesizing enzymes, gamma-glutamylcysteine synthetase and GSH synthetase were found in the human fetal liver (7.1 and 3.0 mukat/kg, respectively). The activities of these enzymes were in the same range as in human adult liver, whereas that of gamma-glutamyl transpeptidase was 3-fold higher in the fetal liver. Our results demonstrate the presence of high concentration of SH groups and capacity to synthesize GSH already in the first and second trimester of the human fetal gestation. This has more than theoretical interest, since we assume that the SH groups (GSH) have importance for the protection of the fetus against drugs and foreign compounds and their (toxic) metabolites, the formation of which is catalyzed by the fetus itself.

Adrenal Glands↗
PubMed1979

Intraindividual similarity in the metabolism of amitriptyline and chlorimipramine in depressed patients.

The two structurally similar tricyclic antidepressant drugs amitriptyline (AT) and chlorimipramine (CI) were administered to 15 patients in a cross-over study. Approximately equimolar daily doses of the two drugs (5 mumol/kg body weight) were given as commercial tablets. Steady state plasma levels of the parent drugs and the demethyl metabolites were determined by high performance liquid chromatography. An about 5-fold interindividual variation was found in plasma levels of all four compounds. As the reciprocal plasma level during multiple dosing is proportional to the clearance of a compound, this parameter was used for linear regression analysis. In the 15 patients there was a significant correlation between the reciprocal plasma levels of CI and its metabolite demethylchlorimipramine (r = 0.76; p less than 0.001) and also between AT and its metabolite nortriptyline (r = 0.52; p less than 0.05). The reciprocal plasma levels of the parent compounds AT and CI were closely correlated (r = 0.87; p less than 0.001). A similar correlation was found for the demethyl metabolites (r = 0.77; p less than 0.001). The results indicate that similar factors control the plasma levels of AT and CI during treatment and that similar enzymes may be involved in the metabolism of the two drugs.

Amitriptyline↗