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Biomedical subjects

J C Boyd

Publications and source records attributed to J C Boyd.

83 records · Page 5Linked to original sources
PubMedDate not supplied

The time course of creatine kinase elevation following concentric needle EMG.

The electromyographic (EMG) exam and creatine kinase (CK) are commonly used to evaluate patients with neuromuscular diseases. Prior studies have demonstrated minimal elevation of CK following monopolar needle examination, indicating that a false positive elevation does not occur in normal individuals. We studied the magnitude and time course of CK change resulting from concentric (CNEMG) and monopolar (MNEMG) needle EMG examination on healthy volunteers. CK increased in all subjects following CNEMG and MNEMG. Statistically significant mean CK elevations over baseline were observed at 4, 8, 12, and 24 hours for CNEMG and at 12 and 24 hours for MNEMG. Maximum elevation occurred at 12 and 24 hours for both CNEMG (mean, 178% of baseline) and MNEMG (mean, 134% of baseline). CK returned to baseline by 48 to 72 hours. In 25-30% of subjects CK elevation significantly exceeded the normal range. The magnitude of CK elevation is greater and the time course more prolonged than previously reported. CK measurements should be avoided 4 to 48 hours following CNEMG because of the potential for false positive results. Measurements immediately after and at 72 hours are not affected by the CNEMG or MNEMG. The time course for CK change following MNEMG is similar to CNEMG, but the magnitude is less.

Adult↗
PubMedDate not supplied

Kinetics of the human medulloblastoma cell line, D283 Med, maintained in an organ culture system. Autoradiographic study after cumulative labelling in vitro: similarities to the kinetics of human medulloblastoma in situ.

Cells of the human D283 Med medulloblastoma cell line were collected by gravity sedimentation and maintained in vitro in an organ culture system. The explants grew as clusters of small cells with scanty cytoplasm; some cells were arranged in solid trabeculae, sometimes forming rows and columns, and occasionally rosettes. The kinetic parameters were estimated after 6 days in vitro by cumulative labelling of the cultures with tritiated thymidine in three different experiments. The length of G2 phase (TG2) was obtained from an analysis of the fractions of continuously labelled mitoses (FCLM), the length of S phase (TS) from the median values of grains over mitotic figures (grain index, GI), and the other parameters from mathematical models that related growth fraction (GF), TG2, total cell cycle time (TC) and labelling index (LI) as a function of time. Mean GF, TC, TG1, TS and TG2 were estimated respectively to be 0.35, 30 h, 13 h, 10 h, and 7 h. These estimates correspond to those reported for human medulloblastomas in situ and confirm previous in vitro experiments which suggest that the organ culture technique is a suitable system for the study of cell kinetics in human malignant gliomas and for an analysis of the in vitro effects of chemotherapeutic agents.

Autoradiography↗
PubMedDate not supplied

Adaptation of EMIT drug assays to a random-access automated clinical analyzer.

Enzyme multiplied immunoassay technique (EMIT) assays for theophylline, carbamazepine, phenytoin, phenobarbital, valproic acid, acetaminophen, gentamicin and tobramycin, have been adapted to the Technicon RA-1000 random access analyzer. Working reagents are stable for a period of at least one week, and calibration need only be performed when preparing fresh reagents. Between-day precision ranged from 2.2 to 5.5 percent and correlations with similar EMIT assays performed on a centrifugal analyzer were satisfactory. Excellent results were obtained on proficiency testing samples when analyzed for theophylline, phenobarbital, phenytoin and acetaminophen. The procedures have been adapted to emergency testing of these four drugs.

Autoanalysis↗
PubMedDate not supplied

Optimization and evaluation of cardiac enzymes and isoenzymes measured on a random access analyzer.

Four serum enzymes and isoenzymes used in the diagnosis of acute myocardial infarction (AMI), lactate dehydrogenase LD and LD-1, creatine kinase (CK), and CK-MB have been adapted to the Technicon RA-1000 automated clinical chemistry analyzer. Analytical parameters have been adjusted to provide clinically acceptable precision for all four assays. Correlations with centrifugal analyzer procedures gave correlation coefficients ranging from 0.998 to 0.999. A limited clinical study of the CK-MB assay indicated that a discriminant value of 13 U per L could separate AMI from non-AMI patients.

Autoanalysis↗
PubMedDate not supplied

Enzymatic assay for creatinine with fixed-time kinetics on a centrifugal analyzer.

A method is described for enzymatic measurement of serum creatinine using a centrifugal analyzer. The method employs fixed-time kinetics and a true serum blank. The method required 100 microliters of serum and is linear to 90 mg per L. Day-to-day precision studies revealed a standard deviation (coefficient of variation) of less than +/- 0.5 mg per L (7.4 percent) at a mean creatinine concentration of 6 mg per L and +/- 0.5 mg per L (1.8 percent) at a mean value of 28 mg per L. The method was free of interferences from acetoacetic acid, ascorbic acid, bilirubin, and hemoglobin. The speed, precision, and accuracy of the method suggest that it represents a useful alternative to methods using the alkaline picrate procedure.

Amidohydrolases↗
PubMedDate not supplied

Measurement of glycosylated hemoglobins using boronate affinity chromatography.

A boronate affinity column method for the measurement of glycosylated hemoglobins was evaluated. In the procedure the glycosylated hemoglobins were bound by immobilized boronic acid to separate them from nonglycosylated hemoglobins. Elution of bound glycosylated hemoglobins was carried out with sorbitol buffer, and the absorbance was read at 414 nm. The method was linear to a glycosylated hemoglobin concentration of at least 20 percent. The precision of the method ranged from 1.2 to 2.8 percent (C.V.) within-run, and 3.4 to 5.3 percent day-to-day. The reference interval was 4.8 to 6.4 percent. The method correlated with a cation exchange resin mini-column method (r = 0.94) and a colorimetric method (r = 0.93) but results from the boronate affinity method were higher in diabetic patients. The measured glycosylated hemoglobin was significantly correlated with estimated one-day-mean plasma glucose in diabetic patients (r = 0.54, n = 52, p less than 0.002). The affinity method provides an attractive alternative to earlier methods for measuring glycosylated hemoglobins.

Adolescent↗