Biomedical subjects
Publications and source records attributed to V Smith.
The excretion of oxprenolol and timolol in breast milk was examined by comparing their concentrations in milk with those in plasma. The mean milk to plasma ratio of oxprenolol was 0.29 (SD 0.14; that for timolol was 0.80 (SD 0.21). The total quantity of either drug ingested by a fully breast-fed infant is unlikely to be therapeutically significant.
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In seven patients with displacement of the macula in one eye caused by vitreoretinal traction from proliferative diabetic retinopathy, the macula was displaced toward the optic disk in all but one eye. The eyes with macular heterotopia showed (1) reduced visual acuity (ranging from 6/6 (20/20) to 6/24 (20/80), (2) reduced static perimetry sensitivity (particularly in the temporal field) with displacement of the peak sensitivity toward the blind spot, (3) loss of hue discrimination, and (4) metamorphopsia. In two eyes with macular heterotopia, Stiles-Crawford data provided evidence for photoreceptor disorientation; one eye had mixed orientation, and the other a displaced peak suggesting regular photoreceptor tilting. The proposed mechanisms of visual loss in eyes with macular heterotopia secondary to traction from proliferative diabetic retinopathy include detachment of the macula, disorientation of photoreceptors in the macula, and disturbance of normal neural connections within the retina caused by stretching of the retina.
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The authors describe a low-cost CT scanner integrated with a radiotherapy simulator and designed for treatment planning. The standard rotational gantry and x-ray tube of the simulator are used with a multiwire xenon lonization chamber and simple current-proportional readout system to measure patient attenuation, avoiding problems associated with diagnostic CT scanners in treatment planning. Although design constraints limit performance, software compensation techniques have reduced artifacts and given satisfactory images.
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This paper describes the experiences of seven women mental health professionals who met in a leaderless group over a period of a year and a half. There is a discussion of the conflicts for women in four major areas--competition, dependency needs, economic success and the search for role models, and the suggestion of possible successful resolutions in these conflict areas. The resolutions are a result of individual experiences and discussions in the group.
A rapid and sensitive high-pressure liquid chromatographic assay was developed for aspirin, salicylic acid, and salicyluric acid in plasma. The procedure involves the solvent extraction of these compounds from plasma and separation using a reversed-phase column eluted by acidified aqueous acetonitrile. Small quantitites of aspirin can be assayed directly in the presence of a large quantity of salicylic acid. The assay is also free from blank interference.
A rapid high-pressure liquid chromatographic assay is described for the quantitative determination of griseofulvin in plasma. An aliquot (25--10 microliter) of plasma was deproteinized by a simple procedure involving the addition of 2.5 volumes of acetonitrile, vortex mixing for a few seconds, and centrifugation for 1 min. The clear supernate, 50 microliter, was injected into the high-pressure liquid chromatograph. A reversed-phase column was used with a mobile phase of distilled water-acetonitrile (1:1) at a flow rate of 2 ml/min and was operated at ambient temperature. A fluorescent detector with an excitation wavelength of 260 nm was employed to monitor the column effluent. Griseofulvin had a retention time of 3.8 min. This procedure yields reproducible results with high sensitivity; plasma concentrations as low as 50 ng/ml can be measured. Several commonly used drugs do not interfere. Analysis of plasma samples collected from a rabbit injected with griseofulvin indicated that the procedure is suitable for pharmacokinetic studies and clinical monitoring of plasma concentrations in patients. Assay turnaround time is less than 6 min. For clinical monitoring of plasma griseofulvin concentrations, a sample volume as small as 10 microliter can be used.
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A rapid, specific method for measuring gentamicin in plasma by high-pressure liquid chromatography was developed. After deproteinization, gentamicin in the supernate was dansylated and extracted into ethyl acetate. The organic extract was chromatographed on a microparticulate reversed-phase column, which was eluted with aqueous acetonitrile. Use of the dansyl derivative enables fluorometry, for more sensitive quantitation. Various factors that could affect the assay sensitivity were investigated. With 0.2-ml plasma samples, the method can accurately measure as little as 1 mg of gentamicin per liter. We encountered no interferences from plasma supplemented with various drugs or plasma of patients who were on therapy with other drugs. This method can also separate gentamicin C1 from C1a and C2, all of which are present in various ratios in commercial dosage forms. This method is also applicable to gentamicin determination in urine.