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Biomedical subjects

W Davidson

Publications and source records attributed to W Davidson.

At least 37 records · Page 2Linked to original sources
PubMed1994

Relation between physician characteristics and prescribing for elderly people in New Brunswick.

OBJECTIVE: To determine whether there is a relation between physician characteristics and prescribing for elderly patients. DESIGN: Descriptive study linking two provincial databases. SETTING: New Brunswick. PARTICIPANTS: All general practitioners (GPs) in New Brunswick who ordered at least 200 prescriptions for elderly beneficiaries of the New Brunswick Prescription Drug Program between Apr. 1, 1990, and Mar. 31, 1991; eligible GPs accounted for 376 (40%) of all physicians with a general licence in New Brunswick. MAIN OUTCOME MEASURES: GPs' personal and professional characteristics (age, sex, family practice accreditation, country of training and number of years in practice), practice characteristics (number of practice days, number of patients seen and medical services provided per day, average amount of billing per patient, total number of patients seen and their average age, and total amount of billings) and number of prescriptions by category of drug. RESULTS: High prescribers and low prescribers did not differ significantly in age, number of years in practice, mean practice size or patient age. Compared with the low prescribers the high prescribers were more likely to be male, have been trained in Canada and be qualified by the Canadian College of Family Physicians. Also, they had more practice days, saw more patients per day, performed more services per day, billed more per patient and billed on average 30% more during the study period. Overall, the high prescribers ordered on average 45% more prescriptions than the low prescribers. CONCLUSION: There is a significant relation between certain physician characteristics and prescribing behaviour. Further study is required to examine the relation between these variables and patient outcomes.

Accounting↗
PubMed1993

High dose rate intraluminal radiation in a combined modality treatment plan for carcinoma of the esophagus.

We have previously reported results for treatment of adenocarcinomas and squamous cell carcinomas of the mid and distal esophagus as well as the use of intraluminal high-dose rate radiation (HDR-RT) for palliation of carcinoma of the esophagus. In this report we describe the results of a chemotherapy/HDR-RT/esophagectomy management program. Examination of the surgical specimens revealed a complete response in only 13% of patients and locoregional recurrence was disappointing. There were no operative deaths nor were there major complications attributable to the preoperative treatment. Two-year survival was 33%, only slightly better than that previously achieved by us with either primary surgery or primary external beam radiation among "curative" candidates with locoregional disease. HDR in combination with our selected chemotherapy regimen is insufficient for locoregional control and must be supplemented either by esophagectomy or external beam radiation for even modest long-term survival.

Adenocarcinoma↗
PubMed1992

Arteriovenous malformation of scrotum: a case report.

Arteriovenous malformations of the scrotum are rare. We report a case of arteriovenous malformation involving the scrotal vessels. The patient presented with painful scrotal swelling, which was mainly in the skin and the Dartos layers. Vascular lesions of the scrotum are rare. By far the most common condition is varicocele. Our patient was examined by 2 other urologists before us and no one made the diagnosis of arteriovenous malformation on clinical examination. Diagnosis was made by auscultation with the Doppler stethoscope. We suggest that the possibility of a scrotal arteriovenous malformation and hemangiomas should be entertained in patients with unilateral scrotal swelling.

Arteriovenous Malformations↗
PubMed1991

Squamous carcinoma of the distal esophagus: a survival study.

A survival study for squamous carcinomas of the distal esophagus treated by the Southern California Permanente Medical Group in the interval of 1954 to 1988 was undertaken. We found radiation therapy and surgery equally efficacious in terms of cure for patients without distant disease and performance status sufficient to tolerate treatment. We did not find survival benefit for patients treated with palliative surgery, and plan less invasive endoscopic means along with chemotherapy and radiation for palliation, reserving surgery for special circumstances.

Adenocarcinoma↗
PubMed1991

Acute myeloid leukemia induction by amphotropic murine retrovirus (4070A): clonal integrations involve c-myb in some but not all leukemias.

Amphotropic murine retrovirus 4070A was demonstrated to be highly leukemogenic when inoculated intravenously into adult DBA/2 mice that were undergoing an intense chronic inflammatory response, but was nonleukemogenic in the absence of inflammation. The virus-induced promoonocytic leukemias, designated AMPH-ML, are similar morphologically and in cell surface marker expression to monocytic leukemias, called MML and MF-ML, previously shown to be induced by Moloney murine leukemia virus and MF-3 virus (a recombinant between Friend murine leukemia virus and Moloney murine leukemia virus) and resemble certain mature acute monocytic leukemias in humans (AML subtype M5). Approximately two-thirds of the AMPH-MLs (subgroup I) were demonstrated to have alterations in the 5' end of the c-myb locus, an event which occurs in 100% of MML and MF-ML. Data indicate that proviral insertions in AMPH-ML subgroup I resulted in aberrant c-myb mRNA expression and truncation of its translation product at the amino terminus. Approximately one-third of the AMPH-MLs (subgroup II) had not undergone any DNA rearrangements at the c-myb locus. In addition, their transcripts and protein products were of normal size. These latter leukemias also had not undergone DNA rearrangements in c-myc, although retroviruses expressing myc have previously been shown to induce monocyte-macrophage tumors in mice undergoing a chronic inflammation. That subgroup II leukemias had at least one clonal viral insertion suggests that there may be other sites in the cellular genome that can be activated by insertional mutagenesis in these murine acute monocytic leukemias.

Animals↗
PubMed1991

Squamous carcinoma of the mid-esophagus. A survival study.

A survival study for squamous carcinomas of the mid-esophagus treated by Southern California Permanente Medical Group in the interval of 1954 to 1988 was undertaken. Radiation therapy and surgery were equally efficacious in terms of 5-year survival for patients without distant disease and performance status sufficient to tolerate treatment (11% and 16%, respectively). There was no survival benefit for patients treated with palliative surgery. Less invasive endoscopic means along with chemotherapy and radiation for palliation are recommended except for special circumstances. Optimal treatment combinations remain to be discovered.

Carcinoma, Squamous Cell↗
PubMed1990

Adenocarcinoma of the esophagus: a survival study.

A 35 year review of adenocarcinomas of the esophagus was undertaken. We found the disease to be one of increasing incidence afflicting white males disproportionately. Risk factors remain to be clarified. Radiation therapy in curative doses and complete resection were competitively effective in terms of long-term survival. No survival advantage was found with palliative surgery compared with other means of therapy. Optimal combinations of treatment remain to be discovered.

Adenocarcinoma↗
PubMed1988

Conservation surgery for T2 and T3 carcinomas of the supraglottic larynx.

The treatment of choice for supraglottic carcinomas of intermediate size (stages T2 and T3) remains controversial. Between 1974 and 1983 in our institution, 139 patients with supraglottic carcinoma of intermediate size were judged retrospectively to have been technically amenable to conservation surgery. Primary disease control at three years was achieved in 100% of the patients treated by supraglottic laryngectomy, 91% (34 patients) of those treated by total laryngectomy, and 69% (81 patients) of those treated by radiotherapy. Of the latter group, 62% were salvaged by total laryngectomy yielding a net three-year local control of 85%. Determinate five-year survival rates were 89% for supraglottic laryngectomy, 78% for total laryngectomy, and 70% for radiotherapy. Significant problems with aspiration occurred in four patients (16%) who were treated by conservation surgery, and two patients (8%) required a permanent tracheostomy. The results of this study show that supraglottic laryngectomy with postoperative radiotherapy as indicated is a highly effective method for the local control of supraglottic carcinoma of intermediate size that is amenable to conservation surgery.

Adult↗
PubMed1988

Studies on measurement of plasma magnesium: application of the Magon dye method to the "Monarch" centrifugal analyzer.

The "Magnesium Liquid Stable Reagent Set" from Medical Analysis Systems, Inc., is evaluated. The method, which involves Magon dye binding and bichromatic absorbance measurements, was used in a Monarch centrifugal analyzer. Results were compared with those by atomic absorption spectrometry. The calibration curve for the Magon method is linear to 2.5 mmol/L, with a 2-microL sample volume. Analytical recovery of magnesium added to human plasma ranged from 95 to 102%. The working reagent is stable for at least five days at 15 degrees C. At concentrations of 0.54 and 1.20 mmol/L, the respective CVs were 2.15 and 3.60% within batch, and 3.13 and 3.24% between batch. We analyzed 150 clinical samples for magnesium by both methods. Absorbance readings at 520/600 nm rather than 520/690 nm improved the correlation (r = 0.9777 and r = 0.9428, respectively). Calcium, albumin, phosphate, or bilirubin did not significantly interfere.

Animals↗
PubMed1987

Pharmacological evaluation of an intra-oral fluoride-releasing device in adolescents.

The purpose of this study was to quantify fluoride (F) concentrations in body fluids of adolescents wearing two intra-oral fluoride-releasing devices (IFRDs) designed to release 0.10 mg F/day. Fluoride concentrations were determined potentiometrically. No significant increases occurred in urine or serum F concentrations during the 26-week device phase. Elevated salivary F concentrations were maintained throughout the device phase when broken or depleted IFRDs were replaced. However, salivary F concentrations returned to pre-device phase values by 26 weeks when the original IFRDs were maintained. These findings suggest that IFRDs can significantly elevate salivary F concentrations of adolescents without significant elevations in systemic F concentrations.

Adolescent↗
PubMed1986

A GABA cardiovascular mechanism in the dorsal raphe of the rat.

An injection of gamma-aminobutyric acid (GABA) and the GABA agonist, muscimol, into the dorsal raphe reduced both heart rate and blood pressure in the urethane-anesthetized rat. Picrotoxinin (3.4 nmol) did not affect blood pressure and slightly reduced the heart rate when injected into the dorsal raphe, but it blocked the decrease in both cardiovascular responses produced by GABA. These decreases in heart rate and blood pressure most likely result from stimulation of a GABAA receptor, as the GABAB agonist, baclofen, appeared to elevate heart rate and blood pressure by a mechanism occurring outside the dorsal raphe area. The changes in blood pressure and heart rate induced by muscimol occurred whether or not respiration was supported. Finally, it can be inferred that these GABAergic actions on blood pressure and heart rate probably involve both an inhibition of central sympathetic outflow and an excitation of parasympathetic outflow, as the quaternary muscarinic blocker, atropine methyl nitrate, blocked the decrease in heart rate induced by muscimol, but not the decrease in blood pressure.

Animals↗
PubMed1984

Disulfiram implantation: a dose response trial.

Alcoholic volunteers (N = 120) were assigned at random to receive an 800 mg, 1200 mg, or 1600 mg subcutaneous disulfiram implant. Patients were followed for a 2-year period. Although all groups showed an increase in sobriety following implantation, there was no significant dose-response relationship. There were no significant between-group differences in the incidence of disulfiram-ethanol reaction.

Adult↗