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Biomedical subjects

B L Evans

Publications and source records attributed to B L Evans.

14 recordsLinked to original sources
PubMed1997

Analysis of esterification of retinoids in the retinal pigmented epithelium of the Mitf-vit (vitiligo) mutant mouse.

PURPOSE: Mice homozygous for the vitiligo mutation of the microphthalmia (Mitf) gene have a retinal degeneration characterized by slow loss of photoreceptor cells and compromised retinal pigment epithelial (RPE) structure and function. The levels of retinyl esters, which are essential for generation of 11-cis-retinaldehyde for the formation of rhodopsin, were reported previously to be elevated by 6 weeks postnatally in the RPE of vitiligo mutant mice. The purpose of the present study was to determine whether this elevation was due to increased activity of lecithin:retinol acyl transferase (LRAT) the enzyme that converts all-trans-retinol to retinyl esters. METHODS: Retinoids extracted from the RPE and neural retina of mutant and normal mice ages 2, 4, 6 and 8 weeks were analyzed by reversed-phase HPLC. The esterification capacity of the RPE to convert 3H-retinol to 3H-retinyl ester was determined by HPLC in mutant and normal mice at 3 and 9 weeks. RESULTS: Retinyl ester levels were elevated significantly in the mutant RPE as early as postnatal week 2 and were four-fold greater by 8 weeks. The esterification assay indicated no significant differences between mutants and controls at 3 weeks. At 9 weeks, the esterification activity of the mutant RPE was significantly reduced compared to controls rather than elevated. CONCLUSIONS: The data suggest that the accumulation of retinyl esters is not due to increased LRAT activity. Alternative explanations for the retinyl ester accumulation are discussed.

Acyltransferases↗
PubMed1994

Cough induced by quinapril with resolution after changing to fosinopril.

OBJECTIVE: To report a case of chronic, nonproductive cough secondary to the angiotensin-converting enzyme (ACE) inhibitor quinapril, with complete resolution after switching to another ACE inhibitor, fosinopril. DATA SOURCES: All relevant articles from January 1985 through February 1993 were identified, primarily through MEDLINE search and review of pertinent articles' bibliographies. CASE SUMMARY: A 68-year-old woman developed a dry, irritating cough within one month of starting quinapril therapy for the treatment of essential hypertension. The patient was a nonsmoker with no respiratory illnesses. The cough continued for the duration of therapy with quinapril. One month after changing to fosinopril therapy, the patient reported complete resolution of the cough. She remains cough-free to date. DISCUSSION: Cough induced by ACE inhibitors is a frequently documented adverse effect. It is severe enough to require discontinuation of therapy in 1-10 percent of patients. The cough is considered to be a class-related adverse effect with cross-reactions between ACE inhibitors routinely reported. At this time, changing to another ACE inhibitor or additive therapy with nonsteroidal antiinflammatory drugs is not recommended. Discontinuation of the ACE inhibitor results in rapid alleviation of the cough, although this is not always necessary, as most patients may experience a cessation or decrease in cough. We report a case of cough following the administration of quinapril, with complete resolution after changing to the alternative ACE inhibitor fosinopril in a patient with essential hypertension. CONCLUSIONS: Cough has been encountered commonly after the administration of ACE inhibitors. Frequency of cough is variable and although this complication has been described as a class effect, patients with a persistent, severe ACE inhibitor-induced cough may benefit from a trial of fosinopril therapy. This may be particularly useful in patients unable to tolerate an alternative class of antihypertensive agents.

Aged↗
PubMed1993

Respiratory and immunological responses of guinea pigs to enzyme-containing detergents: a comparison of intratracheal and inhalation modes of exposure.

Guinea pigs were exposed once a week for 10 weeks by intratracheal exposure to solutions of 3, 1, 0.3, or 0.1 micrograms of the enzyme protein, Subtilisn Carlsberg (Alcalase), in 250 micrograms of a detergent base. Other groups of guinea pigs were exposed by inhalation (6 hr per day, 4 days a week) to 1 mg/m3 of the aerosolized detergent base containing either 3.5, 1.1, 0.3, or 0.1% Alcalase protein. Evaluations of gross respiratory responses immediately following each intratracheal exposure revealed a significant dose response in respiratory symptoms measurable after the fourth exposure and continuing throughout the study. In the inhalation experiment, during Weeks 4 through 10, animals were observed to have respiratory symptoms which were dependent upon both the dose of enzyme and on total exposure to the enzyme/detergent atmosphere. For both intratracheal and inhalation routes of exposure, the initial appearance of respiratory symptoms coincided with the first appearance of measurable serum allergic antibodies specific to Alcalase. The allergic antibody levels increased with time and dosage by both routes of exposure, and the antibody titers generated by the intratracheal administration of antigen were comparable to those generated by the inhalation route of exposure. These results indicate that the intratracheal technique is appropriate for the evaluation of the respiratory allergic response to a protein.

Administration, Inhalation↗
PubMed1991

Lack of genotoxicity of cross-linked acrylate polymers in four short-term genotoxicity assays.

Three cross-linked polyacrylate polymers containing either methylenebis-acrylamide (MBA), trimethylolpropane triacrylate (TMPTA), or triallylamine (TAA) cross-linkers were tested for genotoxicity with the Salmonella mammalian microsome assay, the L5178Y mouse lymphoma TK +/- assay, the unscheduled DNA synthesis assay in primary cultures of rat hepatocytes, and the in vivo bone marrow cytogenetic assay. The results indicate that none of the three polymers was genotoxic in these assays.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Genotoxicity of zinc in 4 short-term mutagenicity assays.

The genotoxicity of zinc was examined in 4 short-term mutagenicity assays. Zinc acetate produced dose-related positive responses in the L5178Y mouse lymphoma assay and an in vitro cytogenetic assay with Chinese hamster ovary cells, but was negative in the Salmonella mutation assay and did not induce unscheduled DNA synthesis in primary cultures of rat hepatocytes. Zinc-2,4-pentanedione produced frameshift mutations in Salmonella tester strains TA1538 and TA98, but did not induce unscheduled DNA synthesis in primary cultures of rat hepatocytes. The effect of ligand binding of zinc in the in vitro test systems is discussed.

Animals↗
PubMed1987

Yield, clinical significance, and cost of a combination BACTEC plus Septi-Chek blood culture system.

A blood culture was performed by adding a vented Septi-Chek bottle (Roche Diagnostics, Div. Hoffmann-LaRoche Inc., Nutley, N.J.) to a standard BACTEC system (Johnston Laboratories, Inc., Towson, Md.) blood culture. The yield of bacteremic patients, the clinical significance of organisms detected, and the cost of the combination system were compared with those of the standard BACTEC system alone. Each culture included 20 ml of blood divided among a BACTEC 6B aerobic bottle (5 ml), a BACTEC 7D anaerobic bottle (5 ml), and a Septi-Chek bottle equipped with a slide subculture attachment (10 ml). Significant isolates grew in 9.6% of the 2,269 cultures evaluated. The combination BACTEC plus Septi-Chek system detected 25% more bacteremic patients than the BACTEC system alone, 129 patients versus 103. The 26 bacteremic patients detected by only the added Septi-Chek bottle included 7 whose organism was isolated from blood alone and 19 whose organism was in mixed or pure culture from a second source. Detection of the organism resulted in alteration of antimicrobial therapy in 17 of these 26 patients. The combination system, which cultured a 20-ml blood volume, cost $11,000 more during the study period than the BACTEC system alone, which cultured a 10-ml volume. Reimbursement under the diagnosis-related group system was increased by $23,000 as a result of documentation of sepsis in these 26 patients. Blood volume and, possibly, the use of multiple blood culture systems are important factors when selecting a blood culture procedure for routine use.

Bacteriological Techniques↗
PubMed1986

DNA-repair studies with sodium fluoride: comparative evaluation using density gradient ultracentrifugation and autoradiography.

Sodium fluoride (NaF) was assayed for the induction of DNA-repair synthesis in WI-38 human diploid fibroblasts and in primary cultures of rat hepatocytes. DNA-repair synthesis in non-replicating DNA was measured by ultracentrifugation of density-labeled DNA in CsCl gradients. When this method was used, NaF did not induce DNA-repair synthesis in either of these cell types. However, when NaF was assayed for induction of unscheduled DNA synthesis (UDS) in rat hepatocytes by autoradiography, an increased net nuclear grain count was observed. Because the autoradiographic results were not confirmed by density-gradient ultracentrifugation of hepatocyte DNA, which is a more definitive technique, it is doubtful whether the autoradiographic results actually represent DNA-repair synthesis. Modifications of the UDS/autoradiography protocol to include more extensive washing resulted in no UDS response. Published reports (Hellung-Larsen and Klenow, 1969; Srivastava et al., 1981) describe the formation of precipitable complexes of Mg2+, F-, and [3H]thymidine triphosphate which suggests that autoradiographic measurement of UDS may lead to artifacts when testing NaF unless extensive washing of the cultures is employed.

Animals↗
PubMed1972

Bacteria of porcine skin, xenografts, and treatment with neomycin sulfate.

Homogenized 4-mm punch biopsies were taken from pigs and bacteriologically evaluated to determine the efficacy of surgical scrub procedures and the subsequent treatment of tissue with 0.5% neomycin sulfate-sodium bisulfite (neomycin-bisulfite) as a decontaminating agent. The majority of the lots of porcine skin taken directly from animals for xenografts in the treatment of burns contained viable bacteria at the time of grafting although scrubbing procedures substantially reduced the skin bacteria. The porcine bacteria consisted primarily of coagulase-negative staphylococci with most strains exhibiting caseinolytic and elastase activity. Staphylococci were the only abundant bacteria found in postscrub biopsies and in saline solutions used to wash the dermatome during its use. After an overnight exposure of grafting tissue soaked in neomycin-bisulfite, the spent neomycin-bisulfite solutions were tested for bacteriostatic and bactericidal activity by comparison to unused neomycin. All solutions tested were equal in bacteriostatic strength, but the bactericidal action of some spent solutions was decreased. Neomycin alone exerted a more lethal effect on sensitive bacteria than the neomycin-bisulfite solution. The desirability of having viable porcine skin for a xenograft necessitated using or discarding the tissue after storage in neomycin-bisulfite at 4 C for a maximum of 72 hr. Certain contaminating microorganisms were unaffected by antibiotic treatment, and the prolonged use of neomycin without bisulfite would have primarily eradicated only the porcine coagulase-negative staphylococci. Neither the presence of this group in grafting tissue nor their proteolytic activity had any observed adverse effect on xenografting success.

Animals↗