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Biomedical subjects

B W Smith

Publications and source records attributed to B W Smith.

At least 19 recordsLinked to original sources
PubMed1992

Estimating the severity of osteoarthritis with magnetic resonance spectroscopy.

This study explores the possibility of estimating the severity of osteoarthritis in the elderly through magnetic resonance measurements of proton relaxation times in articular cartilage. Twenty-five paired samples were cut from eight cartilage specimens. The specimens had been taken in the normal course of knee surgery from patients aged 60 years or older. The reciprocal of the T1 relaxation time (1/T1) was found to have a negative association with the histological-histochemical grade of the severity of osteoarthritis. A revised, weighted version of the Mankin-Dorfman severity scale yielded stronger correlations with 1/T1 and with percent water. A nonlinear regression equation expressing osteoarthritis as a function of 1/T1 explained 38% of the variation in the severity of osteoarthritis as measured by the new scale. A superior methodology for estimating the severity of osteoarthritis on the basis of contour maps of the magnetic resonance response is suggested.

Aged↗
PubMed1991

Accuracy and consistency of quadratic odds estimates.

In medical practices that do not have rosters, only the number of patients who come to the practice can be enumerated: the number who might have visited if they had had a reason to do so remains unknown. The Quadratic Odds Estimator is a technique for estimating the total number of patients cared for by a primary care medical practice, including the non-visitors. A revised version of the model is shown to have an error of less than 1% in predicting the number of patients at risk of visiting a primary care medical practice. Aggregate and sex-specific estimates of total practice size are shown to be comparable to within 2%. The model estimates the prevalence of hypertension among the patients of two family practice resdencies as 18 and 11%. The rationale for employing unconventional regression weights and dual regressions is explained.

Family Practice↗
PubMed1991

Derotational analysis of Cotrel-Dubousset instrumentation in idiopathic scoliosis.

Ten patients with idiopathic scoliosis were treated with posterior spinal fusion and Cotrel-Dubousset instrumentation. Computed tomographic scans and intraoperative photographs were used to evaluate the derotational effect of the Cotrel-Dubousset instrumentation. The frontal deformity was corrected from an average of 51 degrees to 15 degrees and the kyphosis from 9.5 degrees to 18 degrees. The amount of preoperative vertebral rotation was variable, however, and insignificant postoperative changes were documented in the majority of cases.

Adolescent↗
PubMed1990

Long path atomic/ionic absorption spectrometry in an inductively coupled plasma.

A novel approach was taken to increase the atomic/ionic absorption path length in an inductively coupled plasma (ICP) by using a water-cooled quartz "T-shaped" bonnet. Atomic and ionic absorption spectrometry was performed utilizing a continuum source and line sources. Absorption spectra of synthetic multielement solutions were collected with a photodiode array. Sample introduction into the ICP was accomplished with an ultrasonic nebulizer. To prevent the bonnet from cracking, low radio frequency powers were utilized (i.e., 400-600 W). Plasma diagnostics were performed to study the plasma temperature and electron number density within the "T-shaped" bonnet. Analytical figures of merit were found to be better than those obtained from previous work attempted with inductively coupled plasma atomic absorption spectroscopy and approaching that of flame atomic absorption spectroscopy.

Spectrophotometry, Atomic↗
PubMed1990

Laser-excited atomic fluorescence in a pulsed hollow-cathode glow discharge.

A pulsed glow discharge with low background noise is evaluated as an atom reservoir for laser-induced atomic fluorescence spectroscopy. Aqueous solutions are dried in graphite electrodes that are used as disposable hollow cathodes. Atomic vapor is produced in a flowing-gas glow discharge with a water-cooled cathode holder. A dye laser triggers a switching circuit that pulses that glow discharge, and fluorescence measurements are made 100 microseconds after the discharge is extinguished. The atomic population is large during this dark period, while the background emission is negligible. Linear calibration curves are obtained by nonresonance fluorescence for two elements, Pb and Ir. The detection limits for Pb are 100 pg/mL and 500 fg, and for Ir are 6 ng/mL and 20 pg. The experimental detection limit for Pb is compared to the intrinsic detection limit.

Lasers↗
PubMed1989

Continuum source atomic absorption spectrometry in a graphite furnace with photodiode array detection.

A graphite furnace continuum source atomic absorption spectrometer using a photodiode array detector is described that provides high-resolution wavelength versus absorbance spectra over a 2.5-nm range for a single atomization step. The multiwavelength detection power allows the simultaneous determination of several elements, reduces problems caused by spectral interferences, and automatically corrects for nonzero background absorbance. Each spectrum is acquired in 0.33 s, and several successive spectra can be obtained during a single run. Three-dimensional wavelength-absorbance-furnace temperature spectra can be obtained by using ramped heating steps to provide a rough separation of elements in a mixture. Limits of detection calculated for 19 elements range from 0.1 pg for magnesium to 700 pg for arsenic. The sampling precision was found to be better than 10% relative standard deviation in all cases, with the precision for a single atomization being greatly increased when multiple absorption lines for a single element are observed in the spectrum. The error found for the measurement of the iron concentration in an NBS standard bronze was 8.5%, with the calculated concentration agreeing with the certified concentration within 95% confidence limits.

Metals↗
PubMed1989

Fourier transform atomic absorption flame spectrometry with continuum source excitation.

The design and performance of a Fourier transform atomic absorption flame spectrometer (FT-AAS) is presented. A 300-W xenon arc continuum source and a Michelson interferometer are used. A signal to noise disadvantage arising from the multiplex feature of FT-AAS is demonstrated by varying the photon flux at the detector without changing the exciting radiation. A grating is used for dispersion of the radiation before the interferometer to reduce the spectral window at the photomultiplier tube. Detection limits for several elements are generally an order of magnitude poorer than those obtained by continuum atomic absorption methods using echelle-grating spectrometers. Line profiles and absorption spectra, within the region of the spectral window selected by the grating, can be obtained with this method. Standard curves for sodium were constructed to extend the linear calibration range, by using absorbances measured at the absorption maximum and 0.022 nm off-line.

Fourier Analysis↗
PubMed1989

Therapy for osteosarcoma in dogs with intravenous injection of liposome-encapsulated muramyl tripeptide.

Canine osteosarcoma is a spontaneous malignancy in dogs, characterized by micrometastasis to pulmonary and extrapulmonary tissues at the time of diagnosis. Standard treatment involves amputation of the affected leg, but median survival time is 3-4 months with death due to metastasis. A randomized double-blind trial was conducted to evaluate liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (liposome/MTP-PE) as a treatment for metastasis in dogs undergoing amputation for osteosarcoma. Fourteen dogs were treated with liposome/MTP-PE, and 13 were treated with empty liposomes. Median survival time was 222 days for dogs treated with liposome/MTP-PE, compared to 77 days for dogs treated with empty liposomes (P less than .002). In the liposome/MTP-PE-treated group there were still four dogs alive and free of metastasis at greater than 1 year post surgery. Treatment was well tolerated; no significant toxic effects were noted except for mild elevations in body temperature (1-2 degrees C) for 2-6 hours post injection.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1989

Continuity, family involvement, and clinical content in a year-long ambulatory care clerkship.

Entries in student logbooks for the Ambulatory Care Clerkship at the Michigan State University College of Human Medicine were tabulated by microcomputer for 38,430 patient encounters in five community campuses in 1985 and 1986, and by hand for 32,182 patient encounters in Grand Rapids from 1983 to 1987. The repeat visit rate recorded toward the end of the clerkship by students in family practice settings was approximately 60% of the rate recorded by students taking the clerkship with internists or pediatricians. Students in family practice and in pediatrics had the same degree of exposure to patient families; however, family exposure in internal medicine and in pediatrics was limited to other family members of the same generation as the patient. Distributions of the kinds of patient problems seen were distinctive by specialty and were stable across 5 years.

Ambulatory Care↗
PubMed1988

Plasma and erythrocyte magnesium concentrations and correlations with maximum oxygen consumption in nine- to twelve-year-old competitive swimmers.

Twenty-two competitive swimmers (9 males, 13 females) were compared with 18 controls (11 males, 7 females) for body composition, intakes of selected nutrients, VO2max, hemoglobin, hematocrit and magnesium concentrations in plasma, erythrocytes and whole blood. Subjects ranged in age from 9.5 to 12.9 years. Male swimmers had 6.5% less body fat than did male controls (p less than 0.05) whereas there was no significant difference in body fat between female swimmers and controls. Energy, protein and magnesium intakes for swimmers and controls of the same gender were similar. VO2max was significantly higher in swimmers than in controls for both sexes. Magnesium concentrations in plasma, erythrocytes and whole blood were similar for swimmers and controls. However, concentrations of magnesium expressed as milligrams/deciliter in plasma were 8% higher in male swimmers than in female swimmers (p less than 0.05). There was a significant (p less than 0.05) positive correlation between plasma magnesium and VO2max in males, r = +0.42, but not in females.

Body Composition↗