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Biomedical subjects

M Levenson

Publications and source records attributed to M Levenson.

9 recordsLinked to original sources
PubMed2001

Certification of the methylmercury content in SRM 2977 mussel tissue (organic contaminants and trace elements) and SRM 1566b oyster tissue.

The methylmercury content in two new marine bivalve mollusk tissue Standard Reference Materials (SRMs) has been certified using results of analyses from the National Institute of Standards and Technology (NIST) and two other laboratories. The certified concentrations of methylmercury were established based on the results from four and six different (independent) analytical methods, respectively, for SRM 1566b Oyster Tissue (13.2 +/- 0.7 microg/kg) and SRM 2977 Mussel Tissue (organic contaminants and trace elements) (36.2 +/- 1.7 microg/kg). The certified concentration of methylmercury in SRM 1566b is among the lowest in any certified reference material (CRM).

Animals↗
PubMed2000

Certification by the Karl Fischer method of the water content in SRM 2890, Water Saturated 1-Octanol, and the analysis of associated interlaboratory bias in the measurement process.

The calibration of Karl Fischer instruments and reagents and the compensation for instrumental bias are essential to the accurate measurement of trace levels of water in organic and inorganic chemicals. A stable, nonhygroscopic standard, Water Saturated Octanol, which is compatible with the Karl Fischer reagents, has been prepared. This material, Standard Reference Material (SRM) 2890, is homogeneous and is certified to contain 39.24 +/- 0.85 mg water/mL (expanded uncertainty) of solution (47.3 +/- 1.0 mg water/g solution, expanded uncertainty) at 21.5 degrees C. The solubility of water in -octanol has been shown to be nearly constant between 10 degrees C and 30 degrees C (i.e., within 1% of the value at 21.5 degrees C). The results of an interlaboratory comparison exercise illustrate the utility of SRM 2890 in assessing the accuracy and bias of Karl Fischer instruments and measurements.

Journal Article↗
PubMed1999

Endoscopic/Microscopic approach to sphenopetroclival complex: an anatomical study.

A dilemma presents itself to the otoneurologist and neurosurgeon when determining the least invasive surgical approach to giant cholesterol cysts (GCC) of the petrous apex of the temporal bone. These lesions can be diagnosed with a fair degree of certainty with imaging studies. Transmastoid and subcochlear approaches may be inadequate to access these lesions, and the transcochlear approach results in the sacrifice of hearing. A minimally invasive, combined microscopic and endoscopic sublabial transsphenoid approach to drain and marsupalize these lesions has been chosen by the authors in those cases that are anatomically possible. The purpose of this article is to establish the feasibility of exenterating anterior petrous apex cells by way of this approach, and to better conceptualize the anatomy of the Spheno-Petro-Clival Complex (SPC). Ten Fresh cadaveric "whole head" specimens were dissected with, endoscopic/microscopic control, through midline, sublabial, transseptal, and transsphenoidal routes to the petrous apex. The three-dimensional relationships of the sphenoid sinus, petrous apex, and the clivus were further demonstrated by dissections of the same specimens from the posterior fossa. Sagittal cut sections were also performed. After confirming the feasibility of this approach by dissections, the technique was adopted for performing drainage of GCC of the petrous apex in clinical cases.

Journal Article↗
PubMed1991

Nurse burnout: work related and demographic factors as culprits.

This study was an examination of the combined ability of perceived work environment, demographic, and work-related variables to predict burnout among 314 nurses at a large metropolitan hospital. The three dimensions of burnout measured were emotional exhaustion, depersonalization, and personal accomplishment. High work pressure and low work involvement and supervisor support predicted emotional exhaustion. Task orientation, work pressure, work involvement, and age predicted both depersonalization and personal accomplishment. Burnout among nurses on each of the three work shifts also was examined. Results are discussed from the perspective of how to decrease or to prevent burnout among nurses.

Adult↗
PubMedDate not supplied

The plantar approach to heel surgery: a retrospective study.

The authors' present a plantar surgical approach for the patient with painful heel syndrome that is refractory to conservative care. Patient selection, methods, and results are discussed and analyzed. Twenty-two patients with 25 painful heels underwent the procedure. Retrospective analysis of these patients clearly shows this procedure is a viable alternative for heel surgery.

Adult↗