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D S Smith

Publications and source records attributed to D S Smith.

At least 271 records · Page 15Linked to original sources
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

A novel non-separation fluoroimmunoassay for thyroxine.

It has proved possible to develop a novel non-separation fluoroimmunoassay for thyroxine employing antibodies both to thyroxine and to fluorescein incorporated into immune complexes by addition of a common species-specific anti-immunoglobulin G serum. The labelled hapten could bind to antibody of either specificity but not to both at the same time. Binding to anti-fluorescein markedly reduced fluorescence whereas binding to anti-thyroxine did not. Unlabelled thyroxine competed with the labelled hapten only for anti-thyroxine binding sites and, as a result, more of the labelled thyroxine was bound to anti-fluorescein with a decrease in total fluorescence.

Animals↗
PubMed1982

Development of Fluoroimmunoassays for the determination of individual or combined levels of procainamide and N-acetylprocainamide in serum.

A fluoroimmunoassay has been developed for the simultaneous determination of serum levels of procainamide and its active metabolite N-acetylprocainamide. It employs procainamide linked through its aromatic amino group to fluorescein isothiocyanate as tracer and an antiserum raised against procainamide conjugated to human thyroglobulin through the same position. Separation is rapidly and simply achieved by covalently linking the antiserum to magnetisable microparticles and use of a magnet. Specific magnetisable particle fluorimmunoassays were also developed for procainamide and for N-acetylprocainamide by the use of suitable immunogens and fluorescein-labelled tracers. That for procainamide uses an antiserum raised to a procainamide-enzyme conjugate and fluorescein-labelled p-aminobenzoic acid while the fluoroimmunoassay for N-acetylprocainamide employs an antiserum against a N-acetylprocainamide-enzyme conjugate and fluorescein-labelled p-acetamidobenzoic acid.

Acecainide↗
PubMed1982

The effects of high-dose fentanyl on cerebral circulation and metabolism in rats.

There is considerable controversy with respect to the effects of narcotics on the cerebral blood flow (CBF) and the cerebral metabolic rate for oxygen (CMRo2). The present study examined the effects of high doses of intravenous fentanyl (25-400 micrograms/kg) on the CBF and CMRo2 in rats. Cerebral cortical blood flow and metabolism were measured using the 133Xenon modification of the Kety-Schmidt technique. Fentanyl produced a dose-related decrease in both the CBF and the CMRo2. CBF and CMRo2 were maximally depressed by 50 and 35%, respectively, in rats given fentanyl 100 micrograms/kg compared with nitrous oxide-oxygen ventilated controls. The values for CBF and CMRo2 were 168 +/- 15 ml . 100 g-1 . min-1 and 10.3 +/- 0.7 ml . 100 g-1 . min-1, respectively in the nitrous oxide controls compared with 85 +/- 3 ml . 100 g-1 . min-1 and 7.1 +/- 0.1 ml . 100 g-1 . min-1 in animals receiving fentanyl 100 micrograms/kg. Higher doses of fentanyl did not further decrease either CBF or CMRo2 (108 +/- 12 ml . 100 g-1 . min-1 and 7.0 +/- 0.4 ml . 100 g-1 . min-1, respectively for fentanyl 400 micrograms/kg); however, seizures activity was noticed in about 25% of the rats receiving either 200 or 400 micrograms/kg fentanyl. The seizures seemed to be related to the narcotic in that they could be abolished by injections of naloxone. The seizure activity appeared to increase the CMRo2 relative to animals who received the same dose of fentanyl but did not have seizures. The CBF was not affected. The results confirm that narcotics in high enough doses may depress the CBF and CMRo2.

Animals↗
PubMed1982

Direct determination of phenobarbital in serum or plasma by polarization fluoroimmunoassay.

A polarization fluoroimmunoassay for the direct determination of phenobarbital in serum or plasma was developed, optimized, and validated. The drug was derivatized by the introduction of a p-amino function in the phenyl group to enable coupling to carrier protein (used to raise antiserum in sheep) and to fluorescein label. The assay required simply the mixing of prediluted sample, labeled drug, and antiserum, followed by a short incubation and measurement of fluorescence polarization. Normal reliability criteria were satisfied and there was good correlation with established chromatographic and radioimmunoassay methods. Nonseparation, nonisotopic immunoassays are inherently susceptible to sample interferences, but it was shown that the polarization fluoroimmunoassay was subject to inaccuracy only in the presence of markedly elevated levels of bilirubin (above 500 mumol/L), or with gross hemolysis or lipemia.

Antibodies↗
PubMed1982

Intensive immunosuppression versus prednisolone in the treatment of connective tissue diseases.

Intensive immunosuppression (IIS) was compared with prednisolone alone over a 2-year period in the treatment of severe connective tissue diseases. IIS consisted of 15 daily infusions of 750 mg antilymphocyte globulin (ALG), azathioprine 2.5 mg/kg/day, and prednisolone reducing from 150 mg, followed by maintenance azathioprine and prednisolone. The initial dose for prednisolone by itself was 60 mg and patients not responding to this regimen over a minimum of one month were then given IIS. Forty-one patients with life-threatening or severely disabling polyarteritis nodosa (PAN), dermatomyositis/polymyositis (DM), or systemic lupus erythematosus received one or other treatment. All 11 patients who received IIS for PAN remitted. Ten of these had renal impairment which was reversed or halted with IIS, and in 6 of these renal function had been deteriorating with prednisolone alone. One patient died of pneumonia in renal failure 9 months later but with PAN in remission. Two further patients, neither having renal involvement, achieved remission with prednisolone alone. Early cytotoxic treatment would seem to be indicated in PAN when there is renal involvement. Two patients with DM entered remission or prednisolone alone. The remaining 12, of whom 5 had failed steroid therapy, received IIS. Improvement or halting of deterioration was achieved in all 12 with best results in those without marked muscle wasting consequent to disease of long duration. The results suggest that IIS may be a useful adjunct in those patients failing to respond to prednisolone. IIS seemed no more effective than prednisolone alone in the treatment of the 14 patients with SLE and in particular lupus nephritis. Flares in disease activity were common in both groups and appeared to be related to prednisolone dosage. IIS was generally well tolerated, though infection occurred in 2 patients. Vertebral collapse or osteonecrosis of the femoral head occurred in 3 patients following IIS, all of whom had been previously receiving prednisolone for long periods.

Adolescent↗
PubMed1982

Salivary cortisol determination: adaptation of a commercial serum cortisol kit.

The determination of cortisol levels in saliva offers a number of significant advantages as compared with plasma or serum measurements, and radioimmunoassay is the technique of choice because of the greater sensitivity required. To date, the assay of salivary cortisol has been limited to only a few centres employing 'in-house' reagents. We describe some simple modifications of a commercial kit, designed for the assay of cortisol in serum and urine, which allow direct and rapid determination of the steroid in saliva. These modifications enable any laboratory with access to a gamma counter to perform large numbers of salivary cortisol assays at relatively low cost.

Adult↗
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↗