Biomedical subjects

M Owens

Publications and source records attributed to M Owens.

At least 37 records · Page 2Linked to original sources

PubMed1992

Case report: hemolytic anemia produced by tolmetin.

Tolmetin, a nonsteroidal anti-inflammatory drug, was found to be the etiologic agent in a case of drug-induced hemolytic anemia. A 35-year-old female who had ingested tolmetin sporadically in the past took two doses that resulted in acute hemolysis. Two days after taking the second dose, she had a hemoglobin of 7.0 g/dL, increased serum lactate dehydrogenase, reticulocytosis, and indirect reacting hyperbilirubinemia. The direct antiglobulin test was weakly positive with anti-IgG and anticomplement reagents. The patient's serum was nonreactive with reagent red cells in the absence of tolmetin, but addition of tolmetin to the serum resulted in strong agglutination of all reagent red cells tested. Serologic evaluation of this patient's serum indicated that tolmetin caused hemolysis by an immune complex mechanism. Hemolysis subsided and anemia improved spontaneously.

Journal Article↗

PubMed1991

Cryopreserved platelets have decreased adhesive capacity.

The technique of freezing blood platelets has proven very useful in transfusion support of some patients who have become alloimmunized by prior transfusions. Although transfused frozen platelets have an acceptable life span in vivo, functional defects have been found when these cells were tested in vitro. The adhesive properties of frozen platelets were investigated by use of a modified Baumgartner chamber to perform paired perfusion studies of fresh versus frozen platelets or fresh versus 5-day-stored platelets from the same whole blood unit. Platelets were either frozen in liquid nitrogen with dimethyl sulfoxide as the cryopreservative or stored under standard blood bank conditions for 5 days. The freeze-thaw recovery of platelets was 73 +/- 8 percent. Frozen platelets exhibited a significant decrease in platelet adhesion as compared to fresh platelets from the same unit; adhesion of frozen platelets was only 53 percent of that of fresh platelets (p = 0.04). A slight, but insignificant decrease was noted with platelets stored for 5 days (86%, p = 0.197). These findings indicate that frozen-thawed platelets have a significant defect in adhesive capacity as compared to fresh platelets, and that platelets stored under blood bank conditions for 5 days maintain adhesive capacity well.

Blood Platelets↗

PubMed1991

Effects of various fixatives and fixation conditions on DNA ploidy analysis. A need for strict internal DNA standards.

DNA ploidy and cell cycle analyses are being used with increasing frequency as additional, sometimes independent, biologic prognosticators of various malignancies. For obvious reasons, most of the large studies published are retrospective, using archival paraffin-embedded tissues likely to have been fixed and processed differently. To assess the effect of various fixation conditions on ploidy analyses, the authors performed a comprehensive study in which five contiguous aliquots from 26 tissue samples were fixed in formalin for 8. 24, and 48 hours; B5; and the ethanol-based fixative Omnifix (Omni, Xenetics Biomed Inc., Irvine, CA), respectively. The samples were prepared and stained with the use of Hedley's method; the DNA analyses were done with a Coulter EPICS V flow cytometer (Coulter Electronics, Hialeah, FL); and the resulting histograms were interpreted with Multicycle software (Phoenix Flow Systems, San Diego, CA). Mean channels and coefficients of variation (CVs) of the G0/G1 peaks were compared. Increasing fixation times in formalin produced slight shifting to the left on the G0/G1 peaks with differences up to 13 channels. Omni caused similar but more conspicuous changes, with maximal shifting of 51 channels. B5 created the opposite effect, with right-shifted G0/G1 peaks up to 22 channels. The CVs deteriorated progressively with increasing fixation times in formalin. B5 and Omni fixatives conferred the worse histograms, with 6 and 15 cases, respectively, displaying CVs greater than 8. Such significant differences preclude the use of any other internal standard but adjacent normal tissue that was processed exactly the same as the tumor. The validity of DNA results obtained otherwise should be considered questionable. These findings may explain some of the previously published controversial reports and emphasize the need to use an internal standard and more stringent criteria to define aneuploidy in paraffin-embedded tissue.

Cell Cycle↗

PubMed1991

Effect of calcium and calcium antagonists on phospholipid secretion induced by lung inflation in newborn rabbits.

The effect of calcium and selected calcium antagonists on the lung phospholipid secretion associated with lung distension was examined in newborn rabbits. Lung distension was produced by saline lavage or air inflation in freshly killed pups. Calcium or calcium antagonists were added to the lavage solution. The fractional stimulation of secretion with 1.0 mM calcium was 1.94 +/- 0.28 (p less than 0.01), but ethylene diamine tetraacetic acid (EDTA) did not have the expected inhibitory effect. There was dose-related inhibition of phospholipid secretion induced by the calcium antagonist, lanthanum, the fractional recovery decreasing from 1.0 +/- 0.23 at 10(-5) molar, to 0.43 +/- 0.19 at 0.5 x 10(-4) molar, to 0.22 +/- 0.03 at 10(-4) molar and 0.19 +/- 0.05 at 10(-3) molar (p less than 0.001). This inhibition was significantly reversed by the addition of 10 mM calcium. Although nifedipine and verapamil had no effect, nickel and cadmium also inhibited secretion. Therefore, it is likely that lanthanum acted as a calcium channel blocker, suggesting the importance of extracellular calcium. The observation that intense calcium chelation with ethylene glycol bis-aminoethylether tetraacetic acid-bis-aminophenoxyethane tetraacetic acid (EGTA-BAPTA) had a significant inhibitory effect, supports the conclusion that a superficial calcium pool in the plasma membrane may be an important stimulus for phospholipid secretion during lung distension. The inhibitory effect of neomycin, a drug known to displace superficial calcium, was consistent with this conclusion.

Animals↗

PubMed1991

An algorithm for angiographic estimation of blood vessel diameter.

This study was carried out in an attempt to develop an objective and robust method for measuring changes in the diameters of small blood vessels from X-ray angiographic images. Recognizing potential problems with edge detection methods applied to cylindrical vessels in which the contrast diminishes as the boundary is approached, we have attempted to utilize the X-ray absorbance data across the entire cross section of the vessel. Then, assuming a cylindrical geometry, the absorbance data are fit to the cylindrical absorbance function by use of nonlinear regression analysis. The method was tested and calibrated using glass tubes filled with various concentrations of contrast medium. The diameters of small pulmonary arteries were estimated by applying the method of angiograms obtained from an isolated dog lung lobe. The structure of the residuals obtained after the fitting procedure was analyzed to test the appropriateness of the model for use with images of vessels. The results suggest that this approach will have utility for systematically quantifying vessel dimensions.

Algorithms↗

PubMed1991

Lanthanum inhibits surfactant secretion stimulated by lung distension in newborn rabbits.

The effect of lanthanum on lung phospholipid secretion stimulated by lung distension was examined in 29.5-d gestation newborn rabbits. Lung lavage with saline alone produced 608 +/- 109 micrograms phospholipid/lung (mean +/- SEM), whereas lavage with 10(-3) M lanthanum produced only 153 +/- 40 micrograms phospholipid/lung (p less than 0.05), the difference in yield being attributed to inhibited lavage-induced secretion with lanthanum. If this interpretation is correct, then an increased residual tissue surfactant should be found in lanthanum-lavaged lungs. Postlavaged lung was separated into IA, IB, and IC fractions by homogenization and then centrifugation with 0.25 and 0.65 M sucrose. The surfactant IB fraction was 763 +/- 65 micrograms phospholipid/g wet lung for saline-lavaged lungs, but 1002 +/- 90 micrograms phospholipid/g wet lung for lanthanum-lavaged lungs (p less than 0.002). This confirms that decreased secretion with lanthanum was associated with increased residual surfactant in postlavaged lung. It is concluded that lanthanum is a potent inhibitor of surfactant secretion stimulated by lung distension.

Animals↗

PubMed1990

Degradation of 2-phosphoglycerate by cytotoxin B of Clostridium difficile.

Cytotoxin B of C. difficile was highly purified by selective ammonium sulfate precipitation, Biogel A5m chromatography, phenyl boronate hydrophobic interaction chromatography and ultracentrifugation. The final cytotoxic product had a specific activity of 7.8 X 10(8) units/mg protein and showed a single protein band with an estimated molecular weight of 163,000 when subjected to SDS-PAGE. Immunoelectrophoresis of the final product showed a single precipitin arc. The addition of cytotoxin B to imidazole-HCl buffer (pH 7.4) containing MgSO4, KCl and the substrate 2-phosphoglycerate resulted in the formation of phosphoenolpyruvate as demonstrated by spectrophotometric analysis. Phosphoglycerate conversion was absent when the cytotoxin was heat-inactivated of reacted with specific antitoxin prior to assay.

Adrenal Glands↗

PubMed1990

T lymphocyte surface antigen markers in osteoporosis.

Two distinct syndromes of osteoporosis have been postulated: type I, which is characterized by accelerated bone loss occurring in women during the early postmenopausal period; and type II, an age-related process of bone loss affecting both men and women in and after the seventh decade. Recently there has been indirect evidence linking local products of the immune system with bone remodeling. We therefore studied peripheral blood profiles of specific lymphocyte phenotypes in women with type I osteoporosis and in older women and men with type II osteoporosis. The ratio of CD4-bearing (T helper) cells to CD8-bearing (T cytotoxic-suppressor) cells (CD4/CD8 ratio) was elevated in women with symptomatic type I disease. In addition there was a significant negative correlation (r = -0.62, P less than 0.001) between the CD4/CD8 ratio and the spinal bone mineral density measured by dual-photon absorptiometry. In contrast, older men with a history of fracture (hip or spine) had CD4/CD8 ratios similar to control men. The number of T cells bearing IL-2R or VLA-1 was not different between osteoporotic subjects and controls in either men or women. This study supports the concept that local products of the immune system may be directly or indirectly involved in the pathogenesis of type I osteoporosis.

Adult↗

PubMed1990

Ecological toxicology and human health effects of heptachlor.

The chlorinated cyclodiene heptachlor was registered in 1952 as an agricultural and domestic insecticide. By early 1984, registration for all purposes, except subterranean termite control and for limited use in the control of fire ants, had been cancelled. This restriction of use arose primarily from concerns over the environmental persistance and bioaccumulation potential of the organochlorine pesticides. Currently, sale of heptachlor has been voluntarily suspended over questions about its carcinogenic potential, and the absence of safe and effective application methods. As a persistent organochlorine pesticide, heptachlor residues are detected in all components of the environment. In historical use, heptachlor was directly applied to terrestrial systems, while air and water were secondarily contaminated via volatilization and land run-off, respectively. Within each environmental compartment, heptachlor undergoes a variety of metabolic and abiotic transformations. In vivo studies indicate that heptachlor epoxide is the predominant metabolite, formed as a product of the mixed-function oxidase system, while 1-hydroxychlordene is the major soil metabolite. For quantification, heptachlor and its metabolites are extracted from air, soil and sediment, water, or biological materials using various organic solvents and analyzed by gas chromatography or thin-layer chromatography. Residue reports comprise most of the literature concerning the effects of heptachlor on the biota. In many such reports, toxic effects cannot be conclusively attributed to heptachlor exposure. Toxicity to organisms seems more dependent on acute exposure, while the chronic effects of low level exposure to heptachlor are poorly defined. Maximal terrestrial residues coincide with temporal and spatial proximity to application; peak residues in aquatic systems on the other hand, correlate to periods of maximum run-off. The lipophilic nature of both heptachlor and heptachlor epoxide results in the potential for significant bioaccumulation in all lipid-type compartments in the environment. The toxic effects of heptachlor are not specific for any one organ system. The liver and the central nervous system are most significantly affected by heptachlor, although effects can also be seen in the reproductive, hematopoietic, immune, and renal systems. An important consideration is the relation of relevant environmental exposure levels to toxicity. The concentrations necessary to elicit results in laboratory experiments do not translate directly to the same results upon environmental exposure, nor do experimental laboratory animal models absolutely equate with native-state organisms or with humans.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Leading the way.

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Geriatric Nursing↗

PubMed1985

Affective disturbance in eating disorders.

Thirty-three bulimic and 14 restrictive anorexics were compared on DSM-III diagnoses of affective and anxiety disorders, observer-rated and self-rated measures of depression and anxiety, and family history. A subgroup of 18 eating disorder subjects was administered the dexamethasone suppression test. The same 18 subjects were compared to 13 subjects with affective disorder on the Schedule for Affective Disorders and Schizophrenia. It was found that a large group with bulimia and restrictive anorexia nervosa was subject to a depressive disorder. Thirty-eight percent of the sample fulfilled criteria for a major depressive episode. The dysphoric experience seemed as intense in the bulimic and restricter group. There was a high incidence of dexamethasone nonsuppression (55%), which was found to be related to various measures of depression. Bulimics and restricters differed in their family history of affective disorder. While 61% of bulimics had a positive history of depression, this was found in only 23% of restricters (p less than .03).

Adolescent↗

PubMed1984

Muscle protein synthesis: regulation of a translational inhibitor.

Insulin and branched-chain amino acids are known to stimulate protein synthesis in skeletal muscle. Extracts prepared from rat diaphragms after incubation in balanced salt solution and glucose alone yielded heat- and acid-stable, TCA-precipitable, nondialyzable factor(s) that inhibit protein synthesis when added to rabbit reticulocyte lysates. Polyribosomal profiles of inhibited lysates were consistent with a defect in peptide-chain initiation. Addition of insulin and amino acids to the diaphragm incubation media partially removed the inhibition seen with the muscle extract and was accompanied by an increase in polysomes and decreased subunits. Similarly, extracts prepared from rat hindlimb muscle 48 h after induction of diabetes were much more inhibitory in rabbit reticulocyte lysates than extracts from control rats. Polyribosomal profiles were consistent with defective peptide-chain initiation. Trypsin treatment before assay abolished the inhibitory activity of muscle extracts from diabetic rats. Because translation-inhibiting peptide(s) appear to be under metabolic and/or hormonal control, their possible role in muscle protein homeostasis warrants further study.

Amino Acids↗

PubMed1984