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Biomedical subjects

T Clark

Publications and source records attributed to T Clark.

At least 91 records · Page 5Linked to original sources
PubMed1984

Clinical evaluation of the Abbott TDx fluorescence polarization immunoassay analyzer.

The Abbott TDx fluorescence polarization immunoassay (FPIA) system was evaluated and compared with well-established enzyme multiplied immunoassay technique (EMIT) and radioimmunoassay (RIA) methods utilizing five high-volume drug assays including theophylline, gentamicin, phenytoin, phenobarbital, and digoxin. These drug assays were evaluated for precision, calibration stability, specificity, and accuracy. Within-run precision studies utilizing control samples (n = 20) in the subtherapeutic, therapeutic, and toxic ranges resulted in coefficients of variation (CV) of less than 4.0% for the theophylline, gentamicin, phenytoin, and phenobarbital assays and of less than 9.5% for the digoxin assay. Between-run precision studies based on an initial TDx calibration curve over a 2-3 week period yielded CVs of less than 8% for all five drug assays. Cross-reactivity of the FPIA gentamicin assay with concurrently used aminoglycosides such as tobramycin and amikacin was less than 0.1%, and interference due to hemolysis and lipemia was negligible. Highly icteric specimens resulted in clinically significant decreases in theophylline and phenytoin concentrations, but this problem can be corrected by subtraction of blank intensity values. Comparison of the FPIA method with the EMIT and RIA methods indicated an extremely good analytical correlation (r greater than 0.97) for all five comparisons. The Abbott TDx FPIA system offers significant advantages in calibration and reagent stability, and greater sensitivity in the low drug concentration ranges while maintaining accuracy and precision comparable with those of established EMIT and RIA procedures.

Digoxin↗
PubMed1973

Cocaine.

Explore the source record for details and available documents.

Chemical Phenomena↗
PubMed1971

Persistent phenothiazine dyskinesia treated with tetrabenazine.

Six patients with persistent phenothiazine dyskinesia were treated in a double-blind controlled trial with tetrabenazine 100 mg in divided dosage. In three patients the abnormal movements were abolished and in two others there was some improvement, but this was no greater than that achieved with the diazepam control. Tetrabenazine may be useful in the treatment of some patients with persistent phenothiazine dyskinesia.

Aged↗
PubMedDate not supplied

A quantum mechanical/neural net model for boiling points with error estimation.

We present QSPR models for normal boiling points employing a neural network approach and descriptors calculated using semiempirical MO theory (AM1 and PM3). These models are based on a data set of 6000 compounds with widely varying functionality and should therefore be applicable to a diverse range of systems. We include cross-validation by simultaneously training 10 different networks, each with different training and test sets. The predicted boiling point is given by the mean of the 10 results, and the individual error of each compound is related to the standard deviation of these predictions. For our best model we find that the standard deviation of the training error is 16.5 K for 6000 compounds and the correlation coefficient (R2) between our prediction and experiment is 0.96. We also examine the effect of different conformations and tautomerism on our calculated results. Large deviations between our predictions and experiment can generally be explained by experimental errors or problems with the semiempirical methods.

Journal Article↗
PubMedDate not supplied

A temperature-dependent quantum mechanical/neural net model for vapor pressure.

We present a temperature-dependent model for vapor pressure based on a feed-forward neural net and descriptors calculated using AM1 semiempirical MO-theory. This model is based on a set of 7681 measurements at various temperatures performed on 2349 molecules. We employ a 10-fold cross-validation scheme that allows us to estimate errors for individual predictions. For the training set we find a standard deviation of the error s = 0.322 and a correlation coefficient (R(2)) of 0.976. The corresponding values for the validation set are s = 0.326 and R(2) = 0.976. We thoroughly investigate the temperature-dependence of our predictions to ensure that our model behaves in a physically reasonable manner. As a further test of temperature-dependence, we also examine the accuracy of our vapor pressure model in predicting the related physical properties, the boiling point, and the enthalpy of vaporization.

Journal Article↗
PubMedDate not supplied

MR imaging of anterior cruciate ligament repair.

Magnetic resonance (MR) imaging is an accurate means of analyzing disruptions of the native anterior cruciate ligament (ACL). Various techniques may be used to repair a disrupted ACL. A common repair is the MacIntosh lateral-substitution over-the-top repair in which a strip of fascia lata from the iliotibial band is used as a "neoligament." The results of 27 MR examinations of 17 athletes with this repair were analyzed to determine the appearance of the neoligament on MR. Thirteen of the 17 patients had returned to full athletic activity and four were capable of strenuous activity. Examinations were made at both 0.5 and 1.5 T in varied extents of external rotation from 0 to 20 degrees, and at variable time intervals after surgery from 1 to nearly 40 months. Only two patients clinically required postrepair arthroscopy, but both had normal repairs. Neoligaments were classified as well-defined (n = 6 studies), ill-defined (n = 10), and not discernible (n = 11), based on clarity of appearance. Reasons for this variable appearance include the variable presence of fibrous and fatty tissue investing the neoligament. We conclude that the normal neoligament, unlike the normal active ACL, has a variable appearance, including nonvisualization on MR and that criteria used in evaluating the native ligament will be inadequate to assess the repair.

Adolescent↗
PubMedDate not supplied

On the early recognition of neuroleptic malignant syndrome.

Neuroleptic Malignant Syndrome, a serious and sometimes fatal complication, has been reported to occur in some patients with the administration of neuroleptic medications. Clinically it is manifested by four groups of symptoms which include muscular hypertonicity, autonomic instability, altered consciousness, and hyperthermia. Laboratory findings such as elevated creatinine phosphokinase and leukocytosis are also seen. While it is true that the incidence of the full blown clinical picture of this syndrome is rare, the authors report that only muscular hypertonicity and autonomic instability have occurred frequently in their setting leading to discontinuation of neuroleptics. Such abortive cases may go undetected. If properly diagnosed, the occurrence of this syndrome is not as rare as the published reports indicate. Second, it is reported that rechallenge with neuroleptics may not induce Neuroleptic Malignant Syndrome again. The authors noted recurrence of fever after rechallenge with a different neuroleptic drug. This article describes the method of early recognition and prevention of morbidity as well as mortality.

Adult↗