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Biomedical subjects

G W White

Publications and source records attributed to G W White.

At least 37 records · Page 2Linked to original sources
PubMed1988

Effects of photoperiod and intermittent lighting on reproduction in pheasant hens.

Forty 28-wk-old ring-necked pheasant hens were equally distributed among 5 treatment groups and exposed to the following light schedules for 36 wk: Treatment 1 - 16L:8D; Treatment 2 - 1L:11D:4L:8D; Treatment 3 - 1L:13D:2L:8D; Treatment 4 - 1L:14D:1L:8D; and Treatment 5 - 1L:14.5D:0.5L:8D. The number of days from stimulatory lighting to the first egg was significantly (P<0.05) greater under the intermittent schedules (20.3, 29.5, 40.3, 44.4, and 57.7 d, respectively) when the subjective daylength was shorter than 13 h. Despite the delay in initiation of laying, average egg production was higher under intermittent lighting (23.0, 36.0, 48.6, 43.8, and 42.3% or 58.0, 93.0, 122.5, 110.4, and 106.6 eggs). Patterns of oviposition indicated a tendency in the birds exposed to intermittent lighting to have synchronized laying, with the period opposite the longest scotoperiod provided by their light schedule; thus subjective daylengths of 13, 11, 10 and 9.5 h, respectively, were created. Fertility was significantly (P<0.05) lower under intermittent lighting and was apparently associated with a high proportion of eggs in the late stages of oviducal development at the time of insemination.

Journal Article↗
PubMed1984

Videogame adaptation for patients with high-level cervical injury.

Any device that will help improve the quality of life for the patient with high-level cervical injury should be of interest to rehabilitation workers. A new option in this area, not yet widely appreciated or exploited, is the home videogame system. We describe certain modifications needed to adapt such games to the use of cervical injury patients.

Humans↗
PubMed1983

Specific micro-radioimmunoassay for prednisolone in serum.

Use of an 125I radioimmunoassay involving antiserum coupled to magnetizable cellulose, after prednisolone-21-phosphate interference is removed by dichloromethane extraction at pH 7.4 and endogenous glucocorticoid interference is removed by selective chemical derivatization with Girard's Reagent T [(carboxymethyl)trimethylammonium chloride hydrazide], allows determination of prednisolone in 10 microL of serum. Results correlate well with those of an established liquid-chromatographic method for separating prednisolone from its metabolites.

Chromatography, Liquid↗
PubMed1982

Fluoroimmunoassay of digoxin in serum.

A heterogeneous (solid-phase separation) fluoroimmunoassay for digoxin in serum was developed employing antibodies coupled to magnetisable cellulose/iron oxide particles and a fluorescein-labelled digoxin derivative as tracer. Intrinsic fluorophores and other potentially interfering components of serum samples were reliably and completely removed at the separation and wash steps of the assay procedure which were facilitated by magnetic sedimentation. In order to attain adequate sensitivity (detection limit 0.2 micrograms/l (0.26 nmol/l) serum digoxin), a sample volume of 500 microliters was necessary. Assay results for patients' specimens correlated well with those obtained using established charcoal--separation (r = 0.96) and magnetisable solid-phase (r = 0.95) radioimmunoassays. The feasibility of a "stat" adaptation of the fluoroimmunoassay that involved only two standards (0.5 and 4 micrograms/l digoxin) was demonstrated. The stat method would be suitable for the assay of urgent or single specimens.

Antibody Specificity↗
PubMed1981

Magnetisable solid-phase separation fluoroimmunoassay for total oestriol in pregnancy serum.

A rapid separation fluoroimmunoassay for serum or plasma levels of total oestriol in pregnancy was established, based on the use of fluorescein-labelled oestriol and sheep anti-oestriol serum covalently linked to magnetisable particles. Equilibrium was attained within 10 min, and the fluorescence of the bound fraction of labelled ligand was quantitated fluorimetrically after elution from the magnetisable particles. Results for pregnancy serum samples correlated well with an established radioimmunoassay technique and the sensitivity, precision and accuracy were appropriate for clinical use. Advantages of this system as compared with radioimmunoassay include the speed and simplicity of end-point detection, prolonged shelf-life of the labelled reactant and absence of any health hazard. The separation step enabled the removal of any endogenous fluorophores or other interfering factors present in biological samples.

Animals↗
PubMed1981

Direct determination of propranolol in serum or plasma by fluoroimmunoassay.

A fluoroimmunoassay for the determination of serum of plasma levels of propranolol was developed using antibodies to propranolol coupled to magnetizable solid-phase particles and fluorescein-labeled propranolol as tracer. The method was sufficiently sensitive, precise, and specific for application to routine monitoring of propranolol therapy, and gave good correlation (r = 0.99) with a widely used ultraviolet fluorometric method in the assay of patients' specimens. The fluoroimmunoassay involves the same instrumentation as the fluorometric assay and has practical advantages, including greater sensitivity (only 100 microliters of sample required), avoidance of an extraction step, and visible-wavelength fluorometry, which permits the use of disposable plastic apparatus throughout the entire procedure.

Animals↗
PubMed1981

In vitro comparison of three new cephalosporins: LY-127935, cefotaxime and cefoperazone.

The comparative in vitro activity of three new cephalosporin antibiotics Ly-127935 (LY), cefotaxime (CTX) and cefoperazone (CFP) was examined. LY, CTX and CFP had similar activity against Staphylococcus aureus, Escherichia coli and Proteus mirabilis while CFP was less inhibitory than LY or CTX against Klebsiella spp.; indole + Proteus and gentamicin (GM)-susceptible Serratia. LY and CTX were effective while CFP was inactive against Enterobacter spp. and GM-resistant Serratia. CFP was more active than LY or CTX against GM-susceptible Pseudomonas aeruginosa but was the least active agent against GM-resistant isolates. Bacteroides fragilis were more susceptible to LY than CTX or CFP. Combination studies against P. aeruginosa with cephalosporin-GM pairs demonstrated synergy.

Bacteria↗
PubMed1980

Cortisol directly determined in serum by fluoroimmunoassay with magnetizable solid phase.

We developed a direct fluoroimmunoassay for cortisol in serum. This method involves cortisol labeled at the 3 position with fluorescein, and antibodies to cortisol coupled to magnetizable cellulose/iron oxide particles. Sodium salicylate is used as a blocking agent to prevent interference from endogenous binding proteins in serum. Serum sample and labeled cortisol are incubated with the antibody-coupled solid phase for 30 min. The solid phase is then separated and washed to remove free labeled cortisol and endogenous fluorophores of the sample. Finally we elute the antibody-bound fraction of the labeled cortisol into an alkaline methanolic medium and measure its fluorescence. The separation, wash, and elution steps are facilitated by magnetic sedimentation. The assay is sufficiently sensitive, specific, and reliable for routine use and correlates acceptably (r = 0.92) with an established radioimmunoassay. Precision (CV) ranged from 4 to 10% in experiments on three pooled sera; analytical recovery for sera supplemented with as much as 360 microgram of cortisol per liter was 91 to 109%.

Cross Reactions↗
PubMed1979

Comparative in vitro activity of azlocillin, ampicillin, mezlocillin, piperacillin, and ticarcillin, alone and in combination with an aminoglycoside.

The in vitro activities of the newer semisynthetic penicillins azlocillin, mezlocillin, and piperacillin were compared with those of ampicillin and ticarcillin by using 290 clinical laboratory isolates. Piperacillin and mezlocillin were the most active against Escherichia coli, Proteus mirabilis, Klebsiella spp., and Enterobacter spp. When Pseudomonas aeruginosa was tested, piperacillin and azlocillin were more active than either mezlocillin or ticarcillin. Streptococcus pneumoniae and Haemophilus influenzae species were highly susceptible to all of the penicillins tested. Ticarcillin had relatively poor activity against enterococci. The rate of bacterial killing with multiples of the minimal inhibitory concentration of azlocillin, ampicillin, or ticarcillin was tested for E. coli, P. mirabilis, P. aeruginosa, and Klebsiella spp. Increasing concentrations increased the bactericidal effect. The effect of combining azlocillin, ampicillin, or ticarcillin with an aminoglycoside was studied by using both killing curves and checkerboards. The isobolograms constructed from the checkerboards showed a synergistic pattern for the organisms tested, which included E. coli, P. aeruginosa, Klebsiella spp., P. mirabilis, and enterococci. However, the rate of killing was increased by the combination only for P. aeruginosa and enterococci.

Aminoglycosides↗
PubMed1979

LY-127935: a novel beta-lactam antibiotic with unusual antibacterial activity.

The in vitro activity of LY-127935, a new beta-lactam antibiotic, was examined by using 370 clinical bacterial strains. In comparison with several other beta-lactam agents, LY-127935 was the most inhibitory against the Enterobacteriaceae. It was remarkably active against multi-drug-resistant strains of Enterobacter spp., Serratia spp., and Pseudomonas aeruginosa. LY-127935 had four- to eightfold greater activity than did cefoxitin against Bacteroides fragilis. Production of beta-lactamase by Enterobacteriaceae did not influence the minimal inhibitory concentration of LY-127935. However, the beta-lactamase-producing strains of B. fragilis and Haemophilus influenzae had generally higher minimal inhibitory concentrations. LY-127935 was the least active agent tested against gram-positive aerobic cocci. Variations in pH, salt content, protein content, or inocula size had little influence on susceptibility to LY-127935. Although combination studies with LY-127935 and gentamicin demonstrated synergy for P. aeruginosa, the rates of killing for the combination and for gentamicin alone were similar.

Anti-Bacterial Agents↗
PubMed1978

Granulosa cell tumors. A clinical review of 61 cases.

Sixty-one patients with granulosa cell tumors of the ovary were treated in the A.M. Evans Clinic of the British Columbia Cancer Control Agency between 1944 and 1974. Their treatment and follow-up are reviewed, and while the 5-year survival rate was 78%, the 15-year rate fell to 50%. The material suggests that the trend to total hysterectomy and bilateral salpingo-oophorectomy has improved the prognosis, but other explanations are, of course, possible as this is a historical comparison.

Adolescent↗