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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
PubMed1997

Delayed sequelae after acute overdoses or poisonings: cranial neuropathy related to ethylene glycol ingestion.

A 31-year-old woman came to the hospital with breathlessness, confusion, and a refractory anion gap metabolic acidosis; acute renal failure subsequently developed. Her blood ethylene glycol concentration was 390 mg/L, and she was treated with an intravenous ethanol infusion and hemodialysis. During the tenth and eleventh day after admission bilateral seventh cranial nerve paralysis developed, as well as bilateral dysfunction of cranial nerves II, V, VIII, IX, X and XII. Magnetic resonance imaging of her head showed gadolinium enhancement of the fifth cranial nerve bilaterally and a communicating hydrocephalus. Over the subsequent 11 months she recovered full function of her cranial nerves V, VII, IX, X, and XII, and she had subjective clinical improvement to baseline function in cranial nerves II and VIII. This case serves to introduce a discussion of agents that cause delayed complications after their acute toxic ingestion.

Adult↗
PubMed1996

Ultratrace determination of lead in whole blood using electrothermal atomization laser-excited atomic fluorescence spectrometry.

Laser-excited atomic fluorescence has been used to detect lead that was electrothermally atomized from whole blood in a graphite furnace. A 9 kHz repetition rate copper vapor laser pumped dye laser was used to excite the lead at 283.3 nm, and the resulting atomic fluorescence was detected at 405.8 nm. No matrix modification was used other than a 1:21 dilution of the whole blood with high-purity water. Using the atomic fluorescence peak area as the analytical measure and a background correction technique based upon a simultaneous measurement of the transmitted laser intensity, excellent agreement for NIST and CDC certified whole blood reference samples was obtained with aqueous standards. A limit of detection in blood of 10 fg/mL (100 ag absolute) was achieved.

Calibration↗
PubMed1995

Acute knee injuries: Part I. History and physical examination.

A thorough history and physical examination are helpful in the diagnosis of meniscal damage, cruciate and collateral ligament sprains and patellar instability, the four major acute knee injuries. When performing a physical examination in a patient with a knee injury, the uninjured knee should always be assessed first and used for comparison. Examination includes passive and active range-of-motion testing, palpation of the joint line spaces, and a variety of maneuvers to evaluate knee stability. Valgus and varus testing provides assessment of the collateral ligaments. The Lachman and pivot shift tests are useful in the evaluation of the anterior cruciate ligament. The posterior drawer and tibial sag tests are used to evaluate the posterior cruciate ligament. The bounce test, McMurray's test and Apley's grind test can aid in the diagnosis of meniscal injury.

Humans↗
PubMed1995

Treatment of ulnar shaft fractures: a prospective, randomized study.

The treatment of isolated ulnar shaft fractures is controversial. Previous studies comparing treatment options have been largely retrospective and nonrandomized. In this study, consecutive patients were randomized into treatment groups of long arm plaster immobilization, short arm plaster immobilization, or Ace Wrap bandage, based on the order of hospital admission. Thirty-one patients were followed until radiographic or clinical union, with no significant difference in time to union between groups. Age, sex, fracture pattern, and displacement did not significantly influence time to union or final angulation. Two patients in both the long arm cast group and the short arm cast group lost significant motion at final follow up. Seventy percent of patients in the Ace Wrap group failed treatment secondary to pain and were converted to plaster immobilization. Furthermore, patients in this group demonstrated significantly greater angulation than those treated in a long arm cast. Our results demonstrate that above-elbow plaster immobilization offers no advantage over below-elbow immobilization. We recommend short arm casting for a period of 8 weeks.

Adult↗
PubMed1995

Acute knee injuries: Part II. Diagnosis and management.

The most common acute knee injuries are collateral ligament sprains, meniscal damage, cruciate ligament sprains and patellar dislocation or subluxation events. Initial treatment for these soft tissue injuries includes rest, ice application, compression and elevation for the first 24 to 72 hours, as well as anti-inflammatory medication. Accurate assessment, utilizing a thorough history and physical examination and judicious use of radiographic studies, facilitates proper management and return to activity. Athletic patients should be offered the option of surgical reconstruction.

Acute Disease↗
PubMed1994

Capacitively coupled microwave plasma atomic emission spectrometer for the determination of lead in whole blood.

The determination of lead in whole blood by atomic emission spectrometry using a capacitively coupled microwave plasma and a tungsten filament electrode is presented. When the plasma-supporting electrode is also used as the sample holder, transfer of the sample to the plasma is 100%. Microwaves are used to dry the sample and, at higher powers, ignite a helium plasma which results in the atomization and excitation of Pb. Using this methodology, a detection limit of 3 pg of Pb was obtained using 5-microL aqueous samples. The precision was 9%. Whole blood samples were subjected to a drying stage similar to that of the aqueous samples. Following this drying stage, a low-power (30 W) helium plasma was ignited and used to ash the blood sample. Higher power plasmas (> 150 W) were used to atomize and excite the Pb. Recovery of Pb from the blood samples was 88%, when compared to aqueous standards.

Calibration↗
PubMed1994

Chaotic family dynamics.

This article illustrates the basic features of chaotic systems and demonstrates some of the differences between chaotic and nonchaotic systems. To facilitate the explanation of advanced mathematical ideas, this presentation is couched in terms of the interactions within two families: the Limit family and the Scroll family. A nonchaotic model of the Limit family leads to repetitive sequences of affection and hostility between husband and wife. The Scroll family model demonstrates the dynamics of a truly chaotic system; it leads to alternating episodes of mutual endearment and mutual aversion between mother and daughter. Problems of measurement that would accompany the use of these models are mentioned.

Adolescent↗
PubMed1993

Muramyl peptides augment the in vitro and in vivo cytostatic activity of canine plastic-adherent mononuclear cells against canine osteosarcoma cells.

A tumor cytostasis assay was developed that measured the effect of the immunomodulator muramyl dipeptide (MDP) on the in vitro cytostatic activity of canine plastic-adherent mononuclear cells. Mononuclear cells were isolated from the peripheral blood of healthy Beagle donors and allowed to adhere to a 96-well microtiter plate. The adherent cell population was characterized by cell morphology, non-specific esterase staining, and flow microfluorometry to be approximately 42% monocytes, 49% lymphocytes, and 8% eosinophils. Canine plastic-adherent mononuclear cells spontaneously caused cytostasis of D-17 canine osteosarcoma target cell proliferation. The spontaneous cytostatic activity of adherent mononuclear cells was significantly augmented by exposure to MDP or to lipopolysaccharide (LPS), with maximal cytostatic activity being observed after combined exposure to MDP and LPS. Mononuclear cell cytostasis toward D-17 canine osteosarcoma and A375 human melanoma cells was enhanced (P < 0.05) when normal dogs were administered liposome-encapsulated muramyl tripeptide phosphatidylethanolamine, a lipophilic derivative of MDP, by intravenous injection.

Acetylmuramyl-Alanyl-Isoglutamine↗
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↗