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Biomedical subjects

D S Smith

Publications and source records attributed to D S Smith.

At least 253 records · Page 14Linked to original sources
PubMed1984

Dosimetry of computerized tomography in the evaluation of hip dysplasia.

The usefulness of computerized tomography (CT) in the assessment of hip dysplasia has recently been given attention in the literature and concern regarding radiation dose has been raised. This study was undertaken to measure the radiation dose, both in and out of plaster, for plain films, arthrography, tomography, and CT. A method is suggested to reduce dosage by 80% without compromising diagnostic information. Our experience with 25 scans of patients aged 4 months to 39 years is presented.

Acetabulum↗
PubMed1984

Atypical 'fibrillar' flight muscle in strepsiptera.

The fine structure of the principal and ancillary metathoracic flight muscle fibres in the adult male of a strepsipteran, Elenchus tenuicornis, is described. Power-producing dorsal longitudinal and dorso-ventral flight muscles show features consistent with myoneural asynchrony: myofibrils are large and discrete and are separated by large closely packed mitochondria; the sarcoplasmic reticulum is very reduced but engages with T-system membranes in dyads at the mid-sarcomere H-band level. With respect to other asynchronous insect flight muscles, the fibres of Elenchus are anomalous (i) in the small fibre diameter, (ii) in the variable contour of the myofibrils and (iii) in the absence of tracheolar invagination. The functional significance of these structural features is discussed. Ancillary metathoracic muscles are structurally comparable with other synchronous fibres in possessing an extensive SR compartment. Structural evidence for asynchrony in the flight mechanism of Strepsiptera is considered in the context of the evolution of this mechanism throughout the insect Orders.

Actins↗
PubMed1984

Effects of sufentanil on regional cerebral glucose utilization in rats.

Sufentanil, a narcotic five to ten times more potent than fentanyl, reduces cortical cerebral blood flow and oxygen consumption in rats, with seizure activity occurring in some animals. However, the effects of sufentanil on blood flow and metabolism in subcortical structures have not been defined clearly. The present study examines the effects of intravenous sufentanil (40 or 160 micrograms/kg) on regional cerebral glucose utilization (r-CMRgl) in paralyzed, mechanically ventilated rats using 2-deoxy-D-[14C]glucose and autoradiography. Regional cerebral glucose utilization was decreased in all cortical areas examined in rats receiving either dose of sufentanil; the larger dose of sufentanil (160 micrograms/kg) decreased r-CMRgl in cortical structures 20-45% below control values. Two subcortical structures, the caudate nucleus and the ventral thalamic nucleus, manifested a 39-54% decrease in r-CMRgl at each dose of sufentanil. Limbic system structures responded differently. Sufentanil 40 micrograms/kg produced focal areas of markedly increased r-CMRgl in the amygdala of two of six rats; sufentanil 160 micrograms/kg produced marked increases in r-CMRgl in focal areas of hippocampus (four of eight rats) and amygdala (seven of eight rats). EEG activation suggestive of seizure activity was evident in the two low-dose sufentanil and six of the seven high-dose sufentanil rats that had focally increased r-CMRgl in the amygdala. Sufentanil causes a selective increase in r-CMRgl in subcortical limbic nuclei, particularly the amygdala, in the rat. EEG patterns of seizure activity may reflect subcortical, rather than cortical activation.

Anesthetics↗
PubMed1984

Single-reagent polarization fluoroimmunoassay for barbiturates in urine.

We describe a rapid polarization fluoroimmunoassay for screening for the presence of barbiturates in urine. The single reagent is prepared by pre-mixing antiserum with a fluorescein-labeled barbiturate derivative as tracer. Use of a mixture of two sheep antisera, raised against different barbiturate immunogens, results in an assay with a broad cross-reactivity spectrum for most common barbiturates. One adds urine to the pre-mixed reagent, incubates the solution for a few minutes at room temperature, and measures the fluorescence polarization. The tracer/antiserum reagent is stable for at least six months at 4 degrees C. Results compare favorably with two other commonly used screening techniques for barbiturates, thin-layer chromatography and the EMIT-stTM (Syva) system. Although designed as a qualitative screen, some drugs can be quantified by means of a standard curve of the relevant barbiturate.

Barbiturates↗
PubMed1983

Polarisation fluoroimmunoassay of serum and salivary cortisol.

Polarisation fluoroimmunoassays for serum and salivary cortisol were developed using the steroid labelled at the 3-position with fluorescein and antiserum raised in sheep. To avoid interfering factors present in the biological fluids, cortisol was extracted with dichloromethane prior to assay, which was then accomplished without the need for any further separation or blank-correction procedures. The methods were sufficiently sensitive to cover the normal morning ranges for serum and salivary cortisol and correlated acceptably with established fluorimetric and radioimmunoassay techniques. The salivary cortisol assay was more precise than the serum assay, reflecting the greater case with which cortisol may be extracted from saliva. The potential usefulness of salivary cortisol assays was illustrated by a preliminary study showing that the circadian variation in three children was similar to that in an adult.

Adult↗
PubMed1983

Actin-myosin interaction: the role of myosin in determining the actin pattern in self-assembled 'hybrid' contractile units.

Self-assembly of actin-myosin filamentous complexes was assayed by polymerizing rabbit G-ADP actin on formed filaments of lobster myosin. The resulting contractile units indicate a 12-member actin orbital rather than the six-member orbital obtained previously using rabbit myosin and actin. Furthermore, the pattern of actin distribution surrounding the myosin filament is similar to that of the lobster tonic muscle sarcomere rather than the trigonal actin position characteristic of vertebrate muscle. The results show that the pattern and mode of actin complexing is determined by the specific myosin and the arrangement of the cross-bridges on the organized filament.

Actins↗
PubMed1983

Assessment of a latex-agglutination-inhibition card test for serum gentamicin, with a study of the effects of potential interfering factors.

A latex-agglutination-inhibition test for serum gentamicin, based on inhibition by gentamicin of antibody-induced agglutination of gentamicin-coated latex particles, was found to be sufficiently reliable for use in therapeutic monitoring and to correlate well with a variety of established immunoassays. The test (a nonseparation, nonisotopic immunoassay) is performed on cards and has a simple visual end point by inspection for the presence or absence of agglutination. Severely elevated bilirubin or lipid levels, or gross hemolysis (which may cause interference with other nonseparation immunoassays) had no effect on the card test. With raised rheumatoid factor or complement, the cards gave accurate recovery of added gentamicin at 5 and 10 mg/L but low recovery at 2 mg/L. Of 67 patients' sera, three from one individual caused nonspecific agglutination of the latex and could not be assayed. The card test can be recommended for laboratories handling infrequent or small numbers of samples and for those without access to instrumentation.

Fluorescent Antibody Technique↗
PubMed1983

Recurrence phenotypes and establishment of latency following rabbit keratitis produced by multiple herpes simplex virus strains.

Distinct high frequency recurrence (HFRc) or low frequency recurrence (LFRc) phenotypes were observed following rabbit keratitis with three type 1 and five type 2 herpes simplex virus strains. LFRc strains were found to have latently infected the animal but were detected very rarely, if at all, in the eye following the acute phase. The recurrence phenotypes defined in singly infected animals remained unchanged following bilateral infection of the same animal with strains of opposite phenotype. Cocultivation of virus from bilaterally infected animals showed that both virus strains were capable of latently infecting the same animal. Restriction enzyme analysis of plaque-purified virus revealed that some ganglia were latently infected with both parental strains. Recombinants were also found. Some latently infected animals could be re-infected acutely. However, establishment of latency by the superinfecting strain was inhibited.

Animals↗
PubMed1983

A further example of the low frequency antigen Pta.

The third Pt(a+) family is described and it has been shown that the red cell antigen is denatured when treated with proteolytic enzymes, but unaffected by neuraminidase and 2-aminoethylisothiouronium bromide treatment.

Blood Group Antigens↗
PubMed1983

Predictors of mortality and disability in stroke.

The increasingly accurate prediction of survival and functional recovery in patients with stroke will be of value in planning both their individual management and the health and social services needed. To establish the independent predictive effects of a range of personal and clinical characteristics, data on 900 patients admitted to Northwick Park Hospital with stroke were analysed by stepwise multiple regression. Older patients who lose consciousness at the outset and show signs of multiple neurological deficits, abnormal pupils, and conjugate deviation of the eyes are more likely to die within a year than those without these characteristics. Those who survive the acute episode and are discharged alive are more likely to die within a year if they are old and have sensory loss with severe physical disability. Older female patients who are incontinent, lose consciousness at the onset of stroke, sustain extensive motor deficits in combination with other neurological deficits, and have residual disabilities from previous strokes are particularly likely to be severely disabled on discharge from hospital. Routinely collected clinical data enable useful forecasts about mortality and disability after stroke. The accuracy of these forecasts can probably be improved further.

Adult↗
PubMed1983

Polarization fluoroimmunoassay of 11-deoxycortisol in serum and saliva.

We developed polarization fluoroimmunoassays for 11-deoxycortisol in serum and saliva. To avoid interfering factors, the steroid was initially extracted from the biological fluids with dichloromethane. Assays could then be completed without any further separation procedures or need to correct for blank signals. The serum assay was suitable for following the response to the metyrapone test and results correlated acceptably with those by an established, specific, direct 125I-radioimmunoassay. The method is not sufficiently sensitive to detect 11-deoxycortisol in normal saliva, but greatly increased concentrations were found in post-metyrapone saliva and results agreed well with those by the radioimmunoassay as modified for salivary assay. Salivary 11-deoxycortisol assay would provide a convenient means of monitoring results of the metyrapone test.

17-Hydroxycorticosteroids↗
PubMed1983

Plasmapheresis in Rh hemolytic disease: the danger of amniocentesis.

We have treated 25 women with poor obstetric histories and high levels of anti-Rh antibodies by plasmapheresis during pregnancy. One baby was Rs negative, but 13 of the remaining 24 babies survived. Most of the foetal deaths were associated with a rapid rise in antibody level uncontrollable by plasmapheresis and which followed either amniocentesis or intra-uterine transfusion. Plasmapheresis throughout pregnancy with early delivery and avoidance of amniocentesis is recommended.

Amniocentesis↗