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Biomedical subjects

W Davidson

Publications and source records attributed to W Davidson.

53 records · Page 3Linked to original sources
PubMed1981

Two-dimensional echocardiographic assessment of electrocardiographic criteria for right atrial enlargement.

Right atrial (RA) size was determined with two-dimensional echocardiography using the apical four-chamber view in 45 adult patients with various echocardiographic criteria for RA enlargement and in 25 normal controls. RA size varied from 11.4-24.0 cm2 (mean 16.1 cm2) in controls. RA enlargement (greater than or equal to 25 cm2) was found in only two of 11 patients with P pulmonale (predictive value [PV] = 18%) and one of five with prominent positive P-wave forces in lead V1 (PV = 20%). However, RA enlargement ws found in eight of eight patients with a qR pattern in lead V1 in the absence of clinical indications of coronary artery disease (PV = 100%). RA enlargement was also found in 13 of 28 patients with a total QRS amplitude in lead V1 of 6 mm or less and a threefold or greater ratio of total QRS amplitude in lead V2 relative to that in V1(V2/V1 greater than or equal to 3) (PV = 48%). A V2/V1 ratio of 4 or more detected 11 of 13 patients with RA enlargement, with six false-positive diagnoses (sensitivity = 85%, specificity = 60%, PV = 65%). The combination of total QRS amplitude in V1 of 4 mm or less, together with a V2/V1 ratio of 5 or more, detected six of 11 with RA enlargement, with one false-positive diagnosis (sensitivity = 46%, specificity = 93%, PV = 86%). We conclude that ECG criteria for RA enlargement that primarily use increased P-wave amplitude have a limited PV. The qR pattern in lead V1 appears to be extremely accurate in detecting RA enlargement. ECG criteria in leads V1 and V2 using decreased amplitude in leads V1 and a V2/V1 greater than or equal to 3 are of some value in detecting RA enlargement.

Adult↗
PubMed1978

An apparatus to assess function of the hand.

An apparatus was developed to study the movement, strength, and manipulative ability of the hand. To obtain normal values, measurements were made on 80 women and 65 men between the ages of 17 and 70 years. As a comparison, 30 female patients with severe rheumatoid arthritis were studied. There was little difference in the motion between men and women and among the different age groups. In pinch strength men were 40 percent stronger than women, but in grip strength men were twice as strong. In manipulative ability, there was a decline with age. The arthritic patients were compromised severly in both active motion and strength. In the latter they were between one third and one tenth of normal. Manipulative ability was one half of normal. A measurement system, such as described, could be used for the evaluation of results of various operative procedures.

Adolescent↗
PubMed1977

Cephalic kinetics of intra-arterially injected lidocaine.

The intravenous injection of 3 mg./kg. of lidocaine into the facial artery resulted in internal carotid artery blood levels between 5 and 7 microgram/ml. 15 seconds thereafter. Internal and external jugular vein blood levels exceeded 30 microgram/ml. at the same time. When the same amount of lidocaine was injected into the facial vein, carotid blood levels were less than 3 microgram/ml., peaking at 30 seconds. Concentrations of the local anesthetics in the jugular vein peaked at 15 seconds, exceeding 35 microgram/ml. The feasibility of local anesthetic drugs reaching the cerebral circulation through a retrograde pathway was indicated, suggesting that this mechanism may be the route for some of the untoward reactions observed after the injection of local anesthetics in the head and neck area.

Animals↗
PubMed1977

The relationship between sexual and aggressive behaviour, and pituitary and testicular activity during the seasonal sexual cycle of rams, and the influence of photoperiod.

Six adult Soay rams were housed under artificial lighting conditions with alternating 16-week periods of long (16 h light: 8 h darkness) and short days (8L:16D) During long days the rams were reproductively quiescent: the abrupt change from long to short days induced a specific succession of responses in the reproductive system. Plasma LH and FSH levels began to increase after 2-4 weeks, followed almost immediately by a rise in plasma testosterone levels accompanied by growth of the testes. Testicular activity continued to increase during short days and the greatly elevated androgen levels apparent after 5-10 weeks caused changes in the peripheral target organs, including growth of the epididymides, development of the sexual flush on the exposed ventral skin and heightened genital sensitivity. High testosterone levels were also associated with an increase in aggressive (scored by a mechanical device) and sexual (incidence of Flehmen) behavior which was at peak about 1 month after the start of the peak androgen levels. The change to long days was associated with a decrease in plasma gonadotrophin levels within 2 weeks followed by a progressive decline in all reproductive parameters measured. Implantation of a low dose of testosterone (200 mg) during the period of reproductive quiescence induced the development of the sexual flush and an increase in genital tactile sensitivity, although behaviour was not significantly affected. The annual changes in reproductive physiology and behaviour of 12 Soay rams living under natural lighting conditions were recorded for comparison with the experimental situation. The nadir of the sexual cycle was in the spring and early summer, and the sequence of events culminating in the mating season in the autumn was similar to that induced experimentally.

Aggression↗
PubMed1977

Muscle disease associated with renal failure.

A 54-year-old woman had muscle disease that terminated fatally with complete body paralysis. The patient had renal failure, which progressed concurrently with her muscle weakness. Myoglobinuria was not demonstrated during the active stage of her illness. Renal biopsy specimens demonstrated immune deposits in the glomeruli, and, at autopsy, there was a generalized glomerulonephritis. We believe the muscle disease was a consequence of acute rhabdomyolysis, hyperacute polymyositis, or virus infection. Regardless of the nature of the muscle disease, an immune mechanism may have been responsible for the associated renal failure.

Acute Kidney Injury↗
PubMed1976

Vaccine and Mycostatin in treatment of cryptococcosis of the respiratory tract.

Three cases of respiratory crytococcosis are described, one diagnosed only after thoracotomy and two after cytology. All were confirmed by cultures, biological and biochemical tests. The patients are alive and well 14 years, 5 years, and 5 years after treatment with crytococcal vaccines and mycostatin. Vaccines proved very effective when given intradermally in small doses and no dangerous reactions were encountered. Cytology of the sputum appears to be a very useful tool in diagnosis of fungal infections of the respiratory tract, especially when supravital staining is used. Difficulties in diagnosis, treatment, and significance of positive sputum findings are discussed.

Adult↗
PubMed1975

Betamethasone valerate in the treatment of summer hay fever.

Betamethasone valerate nasal aerosol in a daily dose of 400 micrograms was compared with a placebo in a double-blind trial involving 103 patients with summer hay fever. The patients' and physicians' preference for the active compound was statistically significant (P less than 0.001), with 88% of the patients receiving betamethasone valerate obtaining substantial relief of symptoms. The analysis of patients' daily symptom scores showed that nasal symptoms were significantly reduced by the active aerosol (P less than 0.001). A day-by-day comparison of nasal symptom scores with pollen counts indicated a decreasing allergic response as the season progressed; possible reasons for this are discussed. No clinically significant side effects were observed. Short tetracosactrin tests from ten randomly chosen patients on betamethasone valerate showed no abnormality and nasal swabs for Candida culture from a further thirty-two patients were negative. It is concluded that intranasal betamethasone valerate is an effective and safe form of therapy for seasonal rhinitis.

Administration, Intranasal↗
PubMedDate not supplied

The characterization of crude products from solid-phase peptide synthesis by mu-HPLC/fast atom bombardment mass spectrometry.

Crude product mixtures from the solid-phase synthesis of a series of peptides were analyzed by on-line packed, fused silica column mu-HPLC/Continuous Flow Fast Atom Bombardment Mass Spectrometry (mu-HPLC/CF-FABMS). The technique is superior to the direct FAB analysis of crude product mixtures since competitive ionization and suppression effects are not generally observed. Positive correlation between a chromatographic peak and the desired synthetic product may be obtained. An accurate assessment of peptide deprotection can be made without ambiguity arising from the MS fragmentation of the more labile t-butyl and BOC protecting groups used in FMOC-based solid-phase peptide synthesis strategies. mu-HPLC combined with in-line UV detection and MS analysis allows the use of minimum sample and injection volumes, typically 10-50 pmol contained in 0.2-0.5 microliters.

Amino Acid Sequence↗