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Biomedical subjects

L L Smith

Publications and source records attributed to L L Smith.

At least 217 records · Page 12Linked to original sources
PubMed1979

High pressure liquid chromatographic separation of two major toxic compounds from Gymnodinium breve davis.

Cultured Gymnodinium breve cells were extracted in acidified ether and fractionated by a new, convenient procedure utilizing thin layer chromatography or elution dry column chromatography. The most toxic fraction was further separated either directly by analytical high pressure liquid chromatography (HPLC) or in subsequent work by preparative, followed by analytical HPLC. Two toxic compounds, designated T46 and T47, were isolated; purity of each was demonstrated by rechromatography in analytical HPLC with both adsorptive and reverse phase packings. Both the single pass and recycle modes of operation were used with two detector systems in each to demonstrate a single entity. UV, fluorescence, and stability data differentiated these compounds from previously described, less toxic components from G. breve.

Animals↗
PubMed1979

Denaturation of thymidylate synthetase from amethopterin-resistant Lactobacillus casei.

The effects of various concentrations of urea and guanidine hydrochloride on enzyme activity and on subunit association were determined. Incubation of thymidylate synthetase with buffered solutions of 3M to 3.5M guanidine hydrochloride or 5 M to 6 M urea resulted in the loss of about 90% of the enzyme activity. Under these denaturing conditions a red shift of the fluorescence emission maximum from 340 nm to 351 nm was observed together with a significant decrease in the relative fluorescence intensity of the protein. Studies at both 4 degrees C and 25 degrees C indicated that the enzyme was in the dimer form in 2 M guanidine hydrochloride but was dissociated into monomers in concentrations of this denaturant of 3 M and above. Although only monomeric species were evident at 4 degrees C in 6 M urea, at 25 25 degrees C this denaturant caused protein aggregation which increased with decreasing phosphate buffer concentration. Enzyme (5 mg/ml) in 0.5 M potassium phosphate buffer, pH 6.8, containing 4 M guanidine hydrochloride gave a minimum S20, w value of 1.22S at 25 degrees C. Sedimentation behavior of the native enzyme in the range of 5 to 20 mg/ml was only slightly concentration-dependent (4.28 S to 4.86 S) but extensive aggregation occurred above 20 mg/ml.

Chromatography, Gel↗
PubMed1979

Changes in transglutaminase activity in an experimental model of pulmonary fibrosis induced by paraquat.

An experimental model of pulmonary fibrosis has been developed by dosing rats with one-fifth the LD50 dose of the herbicide paraquat on 5 consecutive days. Approximately 50% of the rats died within 4 days of the completion of dosing, showing macroscopic changes and wet weight increases in the lung consistent with severe oedema. Those animals which died between Days 4 and 10 had markedly increased levels of hydroxyproline in the lung, maximum at Day 6, and increased prolyl hydroxylase activity, maximum at Day 4. These changes, together with an increase in thymidine incorporation into DNA, and increased lung DNA content, were consistent with the development of fibrosis. Measurement of transglutaminase activity in the lung showed marked increases at Days 4 and 10 after completion of dosing. This activity paralleled closely the changes in prolyl hydroxylase activity and became increasingly associated with particulate protein present in the "nuclear pellet" fraction. The presence of zymogen plasma transglutaminase trapped in lung homogenates could not be demonstrated but the contribution by the active plasma transglutaminase (Factor XIIIa) to increases shown at Day 4 cannot be ruled out.

Animals↗
PubMed1979

Helping to manage the emotional effects of arthritis.

Arthritis is a chronic disease that has no known cause or cure. The disease is often serious and can cause excruciating pain in the joints and other parts of the body. Some people recognize the physical problems associated with arthritis, but few realize the social and emotional impact it can have on the patient and the family. In this article the author discusses how social workers and other therapists can help arthritic patients cope with the disease and live more productively despite their physical limitations.

Adaptation, Psychological↗
PubMed1979

Age and sex differences on preferred listening rates for speech.

The preferred listening rate of speech was investigated in 30 men and 30 women aged 18--87 yrs. Ss were presented auditorially a reading of a standard prose passage and themselves adjusted a Varispeech I time compressor/expander to yield preferred listening rate. Differences in rate preference were significant for age but not for sex differences. Results support previous reports of auditory perceptual differences with increasing age and suggest that variability in previous reports of preferred listening rates may have been due in part to age differences of the Ss.

Adolescent↗
PubMed1978

Development of an aftercare program in a nonmetropolitan area.

This article describes the development of a nontraditional aftercare program set in a predominantly rural area. The program was initiated by a citizen's board concerned with the lack of follow-up services provided to patients discharged from a distant state hospital. The planning format as conceived by representatives of this board is outlined and the steps involved in operationalizing specific services and a research program are described. Lastly, a number of limitations of the program and future directions are enumerated.

Aftercare↗
PubMed1978

Acute toxicity of hydrogen cyanide to freshwater fishes.

Acute toxicity of hydrogen cyanide was determined at various temperatures from 4 degrees to 30 degrees C and oxygen concentrations of 3.36 to 9.26 mg/L on different life history stages of five species of fish: fathead minnow, Pimephales promelas Refinesque; bluegill, Lepomis macrochirus Rafinesque; yellow perch, Perca flavescens (Mitchill); brook trout, Salvelinus fontinalis (Mitchill); and rainbow trout, Salmo gairdneri Richardson. Median lethal threshold concentrations and 96-hr LC50's were established by flow-through type biassays. Acute toxicity varied from 57 microgram/L for juvenile rainbow trout to 191 microgram/L for field stocks of juvenile fathead minnows. Juvenile fish were more sensitive at lower temperatures and at oxygen levels below 5 mg/L. For most species juveniles were most sensitive and eggs more resistant.

Aging↗
PubMed1978

Heparin activity monitoring during vascular surgery.

Twelve patients undergoing vascular surgery were administered heparin according to preexisting protocols. The response to heparin and the rate of decay were measured by use of the activated coagulation time (ACT). The results showed a significant patient variability to response to and decay of heparin. In addition, a dose-response curve for heparin administration was established in sixteen patients undergoing vascular surgery. The ACT proved to be a simple and accurate monitor of heparin activity. It also made possible a steady state of anticoagulation throughout the duration of the vascular procedure. The reversal of the heparin effect could also be precisely determined by this test.

Aged↗
PubMed1978

Social work with epileptic patients.

Although more than 4 million people in the United States have epilepsy, misconceptions about the disease are prevalent among the public. The author discusses some of the physical and psychosocial problems related to epilepsy and offers suggestions on how social workers can assist epileptic patients and their families.

Adaptation, Psychological↗
PubMed1977

Pulmonary ultrastructure after oral and intravenous dosage of paraquat to rats.

Paraquat was administered to rats by gavage or intravenously at doses which were approximately equitoxic (680 mu. moles/kh and 65 mu. moles/kg respectively) and the lungs examined by light and electron microscopy at intervals up to 48 hours. No significant changes were observed in alveolar endothelial cells at any of the time intervals studied. After intravenous administration the first ultrastructural changes were observed at 4 hr in the type I cells which were less electron dense and contained few organelles. At 8 hr these lesions were more marked and in some places the basement memebrane was denuded. Type II cells were also showing damage to mitochondria and loss of microvilli. After oral dosing, the type and sequence of changes was similar but the first changes were not seen until 22 hr. Intravenous injection of 0-03 micron carbon particles 1 hr before killing showed no significant leakage from the alveolar endothelium. This study provides no morphological evidence that the oedema of the lung caused by paraquat in rats is due to damage to endothelial cells. It appears that, following dosing by the two routes, the difference in interval between dosing and the development of lesions is due to the accumulation of paraquat. Lesions in type I cells therefore occurred when a certain concentration of paraquat is known to be present in the lung. It is suggested that a prime compartment into which paraquat is accumulated is the alveolar epithelial cell.

Animals↗
PubMed1977

Sterol metabolism. XL. On the failure of superoxide radical anion to react with cholesterol.

Superoxide radical anion (O-2) failed to react with cholesterol under a variety of conditions. In some instances products indicative of free radical oxidation by molecular oxygen (O2) were found, but no products of electronically excited (singlet) molecular oxygen (1O2) attack on cholesterol were detected. These results do not support a direct role of O-2 in lipid peroxidation of cholesterol-rich membranes or of the formation of 1O2 from O-2 dismutation.

Animals↗