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Biomedical subjects

L A Edwards

Publications and source records attributed to L A Edwards.

15 recordsLinked to original sources
PubMed2001

Critical Incident Stress Management with inmates: an atypical application.

In March 2001, Centerstone Community Mental Health Centers, Inc.'s CISM Team was asked to debrief 14 inmates after a murder in a rural county jail. We had no specific experience providing CISM in this particular setting, so we contacted ICISF and local law enforcement personnel for their input. We found that neither had a significant amount of experience with this population. In general, although our Team found significant differences related to the restrictions inherent in the environmental setting and the overall group dynamic, we also found similarities in the general manner in which the CISM model was utilized.

Adult↗
PubMed1995

Comparison of the distinct effects of epidermal growth factor and betamethasone on the morphogenesis of the gas exchange region and differentiation of alveolar type II cells in lungs of fetal rhesus monkeys.

To compare the effects of epidermal growth factor (EGF) and betamethasone on the morphogenesis of the gas exchange region and the differentiation of the alveolar type II cell during fetal lung development, fetal rhesus monkeys (78% gestation) were treated in utero with EGF (5.33 mg/kg total dose), beta-methasone (2.6 mg/kg total dose) or the carrier, saline (control), every other day for 7 days. EGF-treated monkeys had significantly increased body and adrenal weights. Betamethasone-treated monkeys had significantly decreased body and adrenal weights. Exogenous EGF reduced cytoplasmic glycogen and increased the cytoplasmic organelle and SP-A content within alveolar type II cells. In contrast, exogenous betamethasone did not alter alveolar type II cell cytodifferentiation. Neither EGF nor betamethasone treatment significantly altered the structure of the gas exchange region as shown by a lack of change from controls in alveolar airspace size or in the fraction of the gas exchange region that was potential airspace. We conclude that at clinically relevant doses, EGF greatly accelerates the maturation of alveolar type II cells, whereas betamethasone does not. Exogenous EGF may act directly on alveolar type II cells because these cells contain EGF receptor. Neither EGF nor betamethasone had dramatic effects on the morphogenesis of the gas exchange region.

Amniotic Fluid↗
PubMed1991

A highly reactive beta-galactosidase (Escherichia coli) resulting from a substitution of an aspartic acid for Gly-794.

The beta-galactosidases of several mutagenized strains of Escherichia coli K12 which grew on lactobionate were found to be heat labile. Sequence analysis of the lacZ gene (ligated into Bluescript) of one of these strains (E. coli REH4) showed that the only change in the amino acid sequence was a substitution of an Asp for Gly-794. This change caused a dramatic increase of the activity when lactose was the substrate. The kcat of the purified enzyme from E. coli REH4 (G794D-beta-galactosidase) with lactose as the substrate was five to six times as large as the kcat of the normal enzyme with lactose. Purified G794D-beta-galactosidase was, however, less stable to heat and also to chymotrypsin (which cleaves next to Trp-585) than was normal beta-galactosidase. G794D-beta-Galactosidase bound substrates and substrate analog inhibitors less well than did normal beta-galactosidase while planar transition state analog inhibitors were more strongly bound. The ability to bind 2-amino-D-galactose (a positively charged transition state analog inhibitor) was either unaltered or was decreased somewhat. The data showed that the alteration in structure caused an increase in the value of k2 (the rate constant for the step in which the glycosidic bond is cleaved) with each substrate tested (the increase was at least 25-fold when lactose was the substrate) while k3 was decreased about 4-fold (k3 is the rate constant for the common hydrolysis step with each substrate). Since k2 is rate determining when lactose is the substrate of the normal enzyme, the increase in k2 resulted in a large increase in rate despite the fact that the value of k3 decreased. Large rate increases were not found with the other two substrates because the k2 values were not increased by large factors and because the decrease in the value of k3 negated the effects of the increased k2 values. The destabilization of the substrate binding coupled with a stabilization of the binding of a planar transition state is a possible cause of the significant increase in the value of k2 and of the enhanced activity with lactose.

Aspartic Acid↗
PubMed1989

Neurogenically mediated contractions of dog basilar artery involve the release of a thromboxane-like substance.

Electrical field stimulation of dog isolated basilar artery produced neurogenically mediated contractions which were unaffected by phentolamine (1 microM), atropine (1 microM), ketanserin (1 microM) or methiothepin (0.1 microM). Responses were abolished by GR32191 (1-10 nM), BM 13.177 (0.1-10 microM) or flurbiprofen (0.5 microM) and markedly attenuated by dazoxiben (1-10 microM). Removal of the endothelium by Triton X-100-perfusion did not modify the magnitude of contractions to electrical stimulation and GR32191 still abolished the responses. GR32191 (1-10 nM) did not modify neurogenically mediated contraction of rabbit ear artery or potassium chloride-induced contraction of dog basilar artery. The results suggest that electrical field stimulation of dog basilar artery causes contractions which are mediated via a cyclo-oxygenase product with characteristics similar to thromboxane. This thromboxane-like substance is not endothelial in origin, nor released by contraction of the cerebrovascular smooth muscle per se and is therefore derived from a subendothelial, possibly neuronal, source.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1989

Studies on the mechanism of the iodination of tyrosine by lactoperoxidase.

Studies with lactoperoxidase showed that a highly reactive intermediate is produced (on the enzyme) from I- and H2O2 which then diffuses from the enzyme and very rapidly and indiscriminately iodinates any Tyr or peptides containing Tyr which are in the same solution. The evidence supporting these conclusions follows. 1) The rate followed the Michaelis-Menten pattern with I- and H2O2 while the concentration of Tyr peptides had no measurable effect on the rate; 2) the rates of reaction were independent of the type of peptide in which Tyr was located; 3) the amount of iodination which had occurred after the reaction had gone to completion and the amounts of monoiodination and diiodination after completion of the reaction were independent of the peptide type, the pH, the solvent polarity, or the ionic strength; 4) competition for reaction by two very different Tyr peptides depended only on their initial concentrations; and 5) iodination of a large protein occurred through a dialysis membrane. Free Tyr was iodinated at the same rate as Tyr peptides by lactoperoxidase, but monoiodotyrosine and m-fluorotyrosine were iodinated at one-half that rate. The results also showed that one can choose ratios of [peptide] to [H2O2] such that monoiodination is maximized relative to diiodination. It was also found that the iodination capacity of a mixture of I- and H2O2 with lactoperoxidase (when Tyr was absent) was only slowly dissipated. Finally, the results showed that lactoperoxidase can be used to brominate and chlorinate Tyr peptides at a slow rate.

Buffers↗
PubMed1988

The use of limited proteolysis to probe interdomain and active site regions of beta-galactosidase (Escherichia coli).

Limited proteolysis by pancreatic elastase (EC 3.4.21.36) and chymotrypsin (EC 3.4.21.1) was used to study the domain structure and active site of beta-galactosidase (EC 3.2.1.23) (Escherichia coli). Treatment with elastase resulted in a rapid cleavage between residues Ala-732 and Ala-733. No inactivation accompanied this cleavage suggesting that this bond is in a hinge region of the protein. Some slow cleavages beyond the initial one were observed to occur and were accompanied by inactivation. Treatment of beta-galactosidase with chymotrypsin resulted in cleavages first between Trp-585 and Ser-586 and then between Phe-601 and Cys-602. The first of these cleavages resulted in total inactivation of beta-galactosidase. The presence of monovalent ions or isopropyl-beta-D-thiogalactopyranoside protected against the cleavages but when Mg2+ or Mn2+ was present in the reaction mixture, the bond between Trp-585 and Ser-586 was more susceptible to the action of chymotrypsin. These data demonstrate that the conformation of beta-galactosidase around Trp-585 and Ser-586 is dramatically affected by the binding of ions and isopropyl-beta-D-thiogalactopyranoside. The mutant M15 beta-galactosidase, which is missing residues 11 through 41 and is an inactive dimer rather than an active tetramer, was found to be much more labile to proteases than native beta-galactosidase, but the same initial cleavages were found to occur. In addition, trypsin cleaved the M15 protein between Arg-431 and Trp-432 while native beta-galactosidase was stable to trypsin.

Antibodies↗
PubMed1986

Analysis of fluorine and iodine derivatives of tyrosine.

Separation of tyrosine, fluorotyrosine, monoiodotyrosine and diiodotyrosine was achieved by reversed-phase high-performance liquid chromatography (HPLC) using a gradient of acetonitrile with water and using trifluoroacetic acid for ion pairing. No derivatization of the amino acids, prior to separation, was needed. The spectral properties of Tyr and its fluorine and iodine derivatives and the dependence of their absorbance maxima on pH, made it possible to analyze and differentiate between these derivatives in the free amino acid form or in peptides. This analysis was accomplished by adjusting the post column HPLC eluate from two identical runs to different pH values and then comparing the spectra of the peaks from these two runs with a diode array detector. Hydrolysis in 6 M hydrochloric acid was totally destructive to mono- and diiodotyrosine. However, base hydrolysis in 13.5 M sodium hydroxide for 30 min at 121 degrees C in an autoclave caused no destruction and allowed excellent recovery of all of the Tyr derivatives. This is the first report of simple methods for the detection and analysis of these amino acids and of a hydrolytic method which protects against their loss. A method of storage was also proposed.

Amino Acids↗
PubMed1986

A detailed examination of the iodination of beta-galactosidase: stoichiometric inactivation by nonspecific iodination.

The incorporation of 125I, using lactoperoxidase, and the subsequent inactivation of beta-galactosidase in the period when incorporation and inactivation were stoichiometric were investigated in detail. The high pressure liquid chromatographic (HPLC) radioactive profiles of the tryptic peptides of samples taken in the stoichiometric period showed that, although two labelled peptides predominated, there were other labelled peptides. The predominating peptides were shown to be the mono- and di-iodinated forms of the peptide containing Tyr-253. This confirmed the result of an earlier study, but quantitation showed that this iodination accounted for only 15-18% of the total. To show that the other labelled peptides in the HPLC profiles were not merely oxidized or partially digested forms of the peptide containing Tyr-253, two experiments were carried out. In one of the experiments, two of the other labelled peptides were isolated and identified as iodinated forms of the peptide containing Tyr-285 (5-7% of the incorporation). In the other experiment, four additional labelled fractions from the HPLC eluate were treated further with trypsin. No further digestion was observed and thus these peptides did not result from incomplete digestion of the sequence containing Tyr-253. Overall, these results show that, although the incorporation of 125I was stoichiometric with inactivation, no single Tyr was responsible for the inactivation as was tentatively suggested previously. The competitive inhibitor isopropyl-beta-D-thiogalactopyranoside (IPTG) was effective in reducing the rates of inactivation of the enzyme and incorporation of 125I, but the same peptides were labelled in the presence of IPTG as in its absence.

Chromatography, High Pressure Liquid↗
PubMed1986

Family practice patients' perception of symptoms.

One hundred family practice patients aged 18 or greater were divided into infrequent and frequent user categories. They were surveyed regarding their perceptions about a list of 20 symptoms on 6 perceptual scales. Perception of symptoms was not related to frequency of attendance, sex of patient, education, or marital status. Age of the patient was the major factor influencing perception of symptoms. Probably due to the heterogeneity of the study population, several previously described factors which were thought to influence perception of symptoms and frequency of attendance were not replicated in this study.

Activities of Daily Living↗
PubMed1977

Symposium on diarrhea. 6. Infectious diarrhea.

Diarrhea may be primarily infectious in origin. Causes can be conveniently classified according to the etiologic agent, which may be viral, chlamydial, bacterial, protozoal, helminthic or fungal. The most common type of infectious diarrhea in Canada is viral. Bacterial infection, particularly staphylococcal and salmonellal, also is relatively common.

Anti-Infective Agents↗
PubMed1977

Meglumine iodipamide (Cholografin) hepatotoxicity.

Two cases of meglumine iodipamide (Cholografin) hepatotoxicity were confirmed by liver biopsy. The hepatic lesion was centrilobular in location and resolved within a short period of time. Nausea and vomiting commonly reported after intravenous cholangiography may be clinical manifestations of this entity.

Adult↗