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D Simpson

Publications and source records attributed to D Simpson.

15 recordsLinked to original sources
PubMed1992

Urinary amphetamines, benzodiazepines and methadone: cost-effective detection procedures.

Cost-effective immunoassays for the detection of amphetamines, benzodiazepines, and methadone in urine have been developed using Syva EMIT reagents and a Cobas Bio centrifugal analyser. With this method up to 2470 samples can be assayed with a single 100 test EMIT kit while maintaining acceptable precision. Mean CVs of 3.8-6.6% were obtained for concentrations around the manufacturer's recommended threshold level (300 micrograms/l). Comparison of the methods with the Abbott TDx system showed good correlation for methadone. The methods compared less well for amphetamines, and it was not possible to obtain a useful correlation for benzodiazepines. Heat treatment prior to analysis did not affect the detection of benzodiazepines and methadone; there was a mean decrease of 14% for amphetamines.

Amphetamines↗
PubMed1991

Structure of a lactone, 2,4,6-trideoxy-4,6-dimethyl-2-(2-oxopropyl)-7-O- (phenylmethyl)-L-glycero-D-manno-heptono-1,5-lactone 3-(3,5-dinitrobenzoate).

C26H28N2O10, Mr = 528.5, triclinic, P1, a = 9.524 (1), b = 11.8187 (8), c = 12.615 (1) A, alpha = 66.512 (7), beta = 83.321 (9), gamma = 88.758 (8) degrees, V = 1293.0 (4) A3, Dx = 1.357 g cm-3, Z = 2, lambda(Cu K alpha) = 1.54178 A, mu = 8.99 cm-1, F(000) = 556, T = 293 K, final R = 0.039, wR = 0.048 for 2425 reflections with I greater than 3 sigma(I). The tetra-substituted valerolactone ring has a boat conformation and the relative stereochemistries of the three pairs of adjacent substituents are cis-trans-trans.

Lactones↗
PubMed1991

Structure of a lactone, (3 alpha,4 alpha,6 alpha)-4-(tert- butyldimethylsiloxy)-3,4,5,6-tetrahydro-6-methyl-3-(2-oxopropyl)- 2H- pyran-2-one.

C15H28O4Si, Mr = 300.5, monoclinic, P2(1)/a, a = 11.194 (4), b = 10.944 (3), c = 14.815 (5) A, beta = 95.01 (3) degrees, V = 1808 (2) A3, Dx = 1.104 g cm-3, Z = 4, lambda(Mo K alpha) = 0.71069 A, mu = 1.43 cm-1, F(000) = 656, T = 293 K, final R = 0.052, wR = 0.058 for 1630 reflections with I greater than 3 sigma(I). The valerolactone ring is in a boat conformation and the three ring substituents are cis.

Models, Molecular↗
PubMed1991

Comparison of vibrotactile thresholds with physical examination and electrophysiological assessment.

Measurement of cutaneous vibrotactile thresholds may be useful for assessment of the functional integrity of the somatosensory system. To validate a rapid method of determining vibrotactile thresholds that uses a commercially available electromechanical device, vibrotactile thresholds were compared with standardized physical examination findings of sensory function and electrophysiological parameters in 79 patients referred to the Mount Sinai Hospital Neurophysiology Laboratory for clinical electrophysiological evaluation. A statistically significant monotonic association between graded physical examination of vibration perception and vibrotactile threshold was observed for all digits tested in the upper and lower extremities. Statistically significant associations were also observed between vibrotactile thresholds and a variety of electrophysiological measures of the median, ulnar, tibial, peroneal, and sural nerves. The strongest associations were observed between great toe vibrotactile thresholds and late response latencies measured in nerves in the lower extremities. Determination of vibrotactile thresholds may be useful in settings where quantitative measures of large fiber nerve function are desirable and electrophysiological study is not feasible.

Action Potentials↗
PubMed1991

Detection of cannabinoids in urine: a cost-effective low risk immunoassay procedure.

Using Syva EMIT reagents and a Cobas Bio centrifugal analyser we have developed a cost-effective assay for the detection of cannabinoids in urine. With this method, up to 1500 samples can be assayed with a single 100 test kit while maintaining acceptable precision. A mean CV of 6.1% was obtained for the concentration range 80-130 micrograms/l. The method is suitable for high-risk urines since heart treatment may be performed prior to analysis. There was no significant change in the measured concentration of cannabinoids in urine samples on storage in plastic containers, refrigerated or frozen, for up to seven weeks.

Cannabinoids↗
PubMed1978

Assembly of viral membranes: maturation of the vesicular stomatitis virus glycoprotein in the presence of tunicamycin.

The role of glycosylation in the maturation of the vesicular stomatitis virus (VSV) glycoprotein was studied by use of the antibiotic tunicamycin. Tunicamycin-treated VSV-infected cells synthesize an unglycosylated form of the VSV glycoprotein (R. Leavitt, S. Schlesinger, and S. Kornfeld, J. Virol. 21:375--385, 1977). We have found that tunicamycin has no effect on the attachment of the glycoprotein to intracellular membranes or on the transport of protein to the lumen of the endoplasmic reticulum. However, tunicamycin prevented the migration of the glycoprotein from the rough endoplasmic reticulum to smooth intracellular membranes.

Cell Line↗
PubMed1978

The peak monitor of the Technicon SMAC system.

The peak-monitor software of the Technicon SMAC system has been investigated by experiments designed to test its ability to detect abnormally shaped peaks, deliberately produced by presenting serum samples of inadequate volume for analysis. The software provided by the manufacturer is shown to detect faulty peaks inefficiently, and a set of modified parameters has been identified which greatly improves the performance of the peak-monitor software.

Autoanalysis↗
PubMed1977

Nightingale.

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England↗