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Biomedical subjects

J Standefer

Publications and source records attributed to J Standefer.

14 recordsLinked to original sources

Evaluation of CK and CK-MB in alcohol abuse subjects with recent heavy consumption.

We analyzed CK and CK-MB levels over 24 h in 15 male subjects admitted for alcohol detoxification following recent heavy ingestion. None had clinical or electrocardiographic evidence of myocardial ischemia or infarction. The mean 0-hour serum alcohol level +/- SD was 342 +/- 101 mg/dl. CK levels were measured by Kodak Ektachem and Abbott IMx assays, and CK-MB levels were determined by these assays and the Hybritech isoenzyme test. In 36% of the patients elevated 0-hour CK levels by the IMx and Ektachem assays were observed. The CK levels measured every 8 h decreased so that by 24 h CK was elevated in 1 patient by the Ektachem assay and in 2 by the IMx assay. Only 1 patient (7%) had an elevated 0-hour CK-MB value by two of the three assays, and it is unclear whether the source was cardiac or extracardiac. We conclude that: (1) elevated CK levels are common in heavy alcohol use patients without evidence of myocardial ischemia; (2) CK values over the first 24 h are decremental, not rising and falling as is typical of myocardial infarction and (3) current isoenzyme immunoassays eliminate a cardiac cause for elevated CK in most of these patients. These findings may assist in the evaluation of alcoholic patients with chest pain.

Adult↗

Enzymatic method for measuring ethylene glycol with a centrifugal analyzer.

We describe a semiautomated, enzymatic method of analysis for ethylene glycol in plasma. Glycerol dehydrogenase (EC 1.1.1.6) from Enterobacter aerogenes, which has high specificity for ethylene glycol, is mixed with 3 microL of specimen in a centrifugal analyzer. NAD+ is added to initiate the reaction, and 450 s after an initial 90-s delay, the absorbance at 340 nm is measured. Monthly calibration with a five-point calibration curve is sufficient to provide between-day precision (CV) of 2% to 5%. The detection limit is 0.3 mmol/L with a CV of 10%. There is no significant interference from ethanol, methanol, isopropanol, acetone, lactate, or glycerol.

Centrifugation↗

Effect of norfloxacin on theophylline metabolism.

The purpose of this study was to investigate the effect of norfloxacin on theophylline elimination. Ten normal volunteers were studied. In a randomized crossover sequence, each subject received 6 mg of aminophylline per kg of body weight by a 30-min intravenous infusion on day 4 of taking norfloxacin (400 mg every 12 h) or while drug free. Mean theophylline clearance decreased and mean elimination half-life increased after norfloxacin administration (from 0.036 +/- 0.006 to 0.033 +/- 0.004 liter/h per kg and from 8.7 +/- 1.2 to 9.5 +/- 1.5 h, respectively; P less than 0.05, Wilcoxon signed-ranks test). We conclude that norfloxacin taken in recommended doses for 3 days has a small inhibitory effect on theophylline metabolism that would probably not cause clinically important elevations in theophylline concentrations in most patients.

Adult↗

Combined intracranial and extracranial excision of nasopharyngeal angiofibroma.

Of all angiofibromas, 10% to 20% may have intracranial extensions or receive vascular supply from the internal carotid artery. Until recently, the treatment of intracranial involvement has been radiation therapy. However, with improved anesthetic and neurosurgical techniques, transfusion capabilities and embolotherapy, the combined intracranial and extracranial excision of an angiofibroma has resulted in a low morbidity and mortality and a greater chance for complete excision of the tumor. The authors present the management of three patients with intracranial involvement of their tumors. Use of the midfacial degloving approach to the nasal cavity and paranasal sinuses has resulted in a significant improvement in the cosmetic appearance postoperatively.

Adolescent↗

Prehepatic insulin production in man: kinetic analysis using peripheral connecting peptide behavior.

The prehepatic production of insulin in normal man was evaluated by kinetic analysis of connecting peptide (C-peptide) behavior in the plasma in men and women. Studies were performed during suppression of endogenous insulin secretion (induced by both fasting and exogenous insulin injection) as well as during stimulation of secretion (induced by oral glucose ingestion) and iv glucose injection. Least squares spline fitting of the C-peptide data by interactive computer analysis permitted evaluation of the precursor production of insulin using a two-compartment model for C-peptide removal. Basal prehepatic insulin production averaged 15-4 mU/70 kg.min in 20 subjects and was reduced to 0.9 +/- 2.2 mU/70 kg.min after 84 h of fasting. The injection of exogenous iv insulin resulted in suppression of endogenous production to 0 +/- 2.5 mU/70 kg.min. Maximum prehepatic insulin production induced by a 100-g oral glucose tolerance test was 91 +/- 1.2 mU/70 kg.min, with a cumulative hormone secretion of 11.4 +/- 2.0 U over the 5 h of observation. After the acute iv injection of 25 g glucose, production rose to 465 +/- 108 mU/70 kg.min at 2 min post injection and rapidly returned toward basal. Levels of insulin in the portal vein calculated from this analysis were markedly elevated relative to simultaneous peripheral venous levels. These results quantitate prehepatic insulin production and portal venous insulin concentration from an analysis of the behavior of C-peptide within the plasma in both the steady state and the nonsteady state in man.

Adult↗

Modulation of basal ketone body concentration by cortisol in diabetic man.

This study explored the relationship between metyrapone blockade of endogenous cortisol secretion and the plasma concentration of basal ketone bodies in insulin-dependent diabetic man. Endogenous cortisol secretion was reduced with metyrapone administration (as assessed by a reduction in plasma cortisol and an increase in deoxycortisol concentration) and then simulated with two different schedules of exogenous cortisol administration. Our results demonstrate that administration of metyrapone suppresses plasma cortisol concentration which may then be elevated by the oral ingestion of cortisol. The suppression of endogenous cortisol secretion with metyrapone results in a 50% reduction in basal plasma ketone body concentration. When endogenous cortisol secretion was simulated with the oral administration of 30 mg cortisol, plasma ketone body concentration returned to that concentration observed in the control study. When 60 mg cortisol were administered in divided dosages to the diabetic subjects, hyperketonemia resulted. These results suggest that the normal diurnal variation in plasma cortisol concentration may modulate the basal plasma ketone body concentration in diabetic man. The mechanism of this modulation may be a direct effect of cortisol or may be secondary to cortisol's lipolytic activity and/or its effects on elevating plasma glucagon concentration.

Adult↗

Direct radioimmunoassay for serum estriol during pregnancy.

I describe an assay for serum estriol during pregnancy, which does not require prior extraction or chromatography of the serum. Fifty microliters of 20-fold diluted serum can be assayed to detect as little as 20 pg of estriol. For a 20 mug/liter serum estriol concentration the CV was 16%; for 100 mug/liter concentration it was 5%. There was no significant interference by serum "binding" proteins. The assay measures unconjugated estriol, estriol conjugated with either sulfate or glucuronide at the 3' position, and a portion of the estriol 16 alpha (beta-D-glucuronide). Serum estriol concentrations increase during gestation from a low at 20 weeks of less than 10 mug/liter to a high of 100-150 mug/liter at term. Serum estriol values correlate well with those for urinary total estrogens and with values for human placental lactogen in serum at various gestational ages.

Estriol↗

Cervical myelopathy: a comparison of magnetic resonance and myelography.

Fifty-seven patients with a strong clinical suspicion of cervical myelopathy were studied with body coil magnetic resonance (MR) and conventional myelography or CT myelography. Eight patients were believed to have normal studies with both modalities. There were six patients with syringomyelia; four with an intramedullary tumor; one with an arteriovenous malformation; 19 with cervical spondylosis at multiple levels; eight with cervical spondylosis at a single level; four with extensive rheumatoid arthritis; four with extradural neoplasm; two with trauma; and one patient with an epidural abscess. In this study, body coil MR was the superior examination for the evaluation of an intramedullary process. It was as diagnostic as myelography in one case of an extramedullary intradural lesion. In patients with extradural disease, body coil MR was the superior study in 45%, equivalent to myelography in 37%, and, although still diagnostic, inferior to myelography in 17%. In 8% of the cases, body coil MR was at best equivocal, whereas myelography was diagnostic. It appears that in technically adequate studies, MR is at least equivalent to myelography in its ability to delineate disease. A superior MR study provides a better appraisal of the size and character of the spinal cord as well as the degree of both anterior and posterior defects on the subarachnoid space and neural structures. In addition, MR is as good as conventional myelography for the identification of extrinsic cervical cord lesions producing cervical myelopathy. Finally, an additional small group of 30 patients were studied with a prototype surface coil to determine its advantages relative to body coil imaging. Each patient had correlative myelography. As with body coil MR, imaging with the surface coil was believed to be more informative than conventional myelography in four patients with intramedullary lesions. The remaining 26 patients suffered from cervical spondylosis. Surface coil MR was believed to be more informative than myelography in six cases (23%), equivalent to myelography in 19 (73%), and less diagnostic than myelography in one (4%). The improved spatial resolution with the use of the surface coil was believed to increase the accuracy of MR.

Adolescent↗