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Biomedical subjects

L Levine

Publications and source records attributed to L Levine.

At least 19 recordsLinked to original sources
PubMed2006

A long term study of the desiccation resistance of Drosophila melanogaster and D. simulans from the Mexican nuclear power plant "Laguna Verde".

The generation of electricity through the use of radioactive material at the nuclear power plant is inevitably associated with the production of wastes, some of which have potential impact on the biosphere. The objective of the present investigation was to provide information for evaluating the presumed impact of the Mexican Nuclear Power Plant "Laguna Verde" on the natural populations. Two sibling species that live in the immediate vicinity, Drosophila melanogaster and D. simulans have been studied for several traits in a long term study. The present study describes results for the desiccation resistance (DR) trait obtained during the period from 1995 to 2002. Flies were collected at two sites, one near the reactors and another farther away. The data obtained confirmed that D. melanogaster had higher DR values than D. simulans at both sites. The analysis of the results obtained from both species of the site closer to the reactor indicated that the values of the DR in the operational stage did not change, compared with those in the preoperational stage previously analyzed. Therefore, the significant differences found between the monitored sites did not seem to be associated to the operation of the reactors.

Adaptation, Physiological↗
PubMed2004

Ten-year viability study on natural populations of Drosophila sibling species from Laguna Verde, Veracruz, México.

The generation of electricity in nuclear power plants produces an increase in background radiation that could possibly have some impact on the organisms that live in that area. In order to identify and quantify any such possible effect, the natural populations of two sibling species, D. melanogaster and D. simulans, that live in the immediate vicinity of the first Mexican Nuclear Power Plant were analyzed for a period of 10 years. Collections of flies were made at two sites, one close to and one farther from the power plant, during the pre and operational stages of the reactor, and their egg-to-adult viability was analyzed. The data obtained indicate that in both sites, the egg-to-adult viability was generally higher in D. melanogaster than in D. simulans. Further, a relationship was found between egg-to-adult viability and the season of the year (warm-wet or cool-dry season). Some differences were found between the two sites. It may be concluded that there is no negative impact on the Drosophila populations studied.

Air Pollution, Radioactive↗
PubMed2003

Radioresistance of sibling Drosophila species from Laguna Verde, Veracruz, México.

PURPOSE: To identify and quantify if the generation of electricity by nuclear power plants produces an increase in background radiation that might affect the radioresistance of organisms that live in that area. MATERIALS AND METHODS: Natural populations of two sibling species of Drosophila, D. melanogaster and D. simulans, living in the immediate vicinity of the Mexican Nuclear Power Plant in Laguna Verde were studied for 10 years. Collections of flies were made at two sites, one close to and one further from two reactors, during both the pre-operational and operational stages of the reactors. The effect of exposure to various doses of gamma-rays on egg-to-adult survival of the flies was analysed. RESULTS: The data obtained indicate that in both sites, egg-to-adult survival was higher in D. melanogaster than in D. simulans. There was an increase in the egg-to-adult survival during the pre-operational period of one of the reactors and the possible causes are discussed. No differences were found between the two sites. CONCLUSIONS: The analysis indicates that the reactors do not have a negative impact on the Drosophila populations studied.

Adaptation, Physiological↗
PubMed2002

Nuclear receptor agonists stimulate release of arachidonic acid from rat liver cells.

Release of arachidonic acid (AA) from rat liver cells is stimulated after a 6 h incubation with compounds that are members of the nuclear receptor superfamily, including vitamin D(3), clofibrate, 22(R) OH cholesterol, farnesol, progesterone, testosterone, 17beta-estradiol, hydrocortisone, 3,3'5 triiodothyronine, juvenile hormone III, WY14643, L -thyroxine, the tyrosine analog of thiazolidinediones, GW7845, tamoxifen, hydroxytamoxifen, 17alpha-estradiol and D -thyroxine. Squaline, lanosterol, cholesterol and the 17beta-estradiol antagonist, ICI-182,780, do not stimulate. ICI-182,780 inhibits the release stimulated by 17beta-estradiol, vitamin D(3), 22(R) OH cholesterol, celecoxib or indomethacin. Actinomycin D abolishes the release stimulated by 15-deoxy-delta(12,14) PGJ(2), but is less effective at inhibiting the release stimulated by all of the agonists listed above as well as the release stimulated by 9-cis retinoic acid, all trans -retinoic acid, the thiazidinedione, ciglitazone and the non-steroidal anti-inflammatory drugs, indomethacin and celecoxib. Based on the effects of the 17beta-estradiol antagonist, ICI-182,780, the release of AA appears to be a membrane effect and may not be mediated by the classical estrogen receptors. From the results obtained with actinomycin D, some stimulations may require transcription.

Animals↗
PubMed2002

Characterization of two New York City Jewish populations at six short tandem repeat loci.

The Hasidic and non-Hasidic Jewish communities of New York City represent two subpopulations with long-documented histories of restrictive marriage patterns and a high degree of endogamy. As part of a continuing study into their genetic structure, allele frequencies were determined for the six tetrameric short tandem repeat (STR) loci: FESFPS, F13AO1, vWA, CSF1PO, TPOX, and THO1. All loci were tested for Hardy-Weinberg equilibrium (HWE) by three tests: chi-square analysis, Monte Carlo chi-square analysis. and the exact test. The non-Hasidic population failed to meet HWE at the F13A01, FESFPS, and CSF1PO loci by all three tests. The Hasidic population also failed to meet HWE at the same loci by some of the tests. Comparison of the Hasidic to the non-Hasidic population using an R x C contingency table demonstrated a similarity at only the vWA locus. Significant differences exist when comparing the two Jewish populations to a reference Caucasian population.

Alleles↗
PubMed2001

Effect of hemodilution on tissue perfusion and blood coagulation during radical hysterectomy.

OBJECTIVE: The goal of this study was to evaluate the safety of hemodilution on global and splanchnic perfusion and blood coagulation during radical hysterectomy. METHODS: A pulmonary artery catheter and a gastric tonometry catheter were placed in 16 patients with cervical carcinoma. Global perfusion indices, splanchnic perfusion index, and coagulation tests were obtained. Blood was removed to achieve a hemoglobin measurement of 8-9 9 g/dL. Three more measurements were repeated after hemodilution, at the end of surgery, and after the retransfusion of blood. Analysis of variance was used to determine statistical significance. RESULTS: Sixteen patients with cervical carcinoma had 1.0 +/- 0.3 L (mean +/- SD) of blood removed and had a blood loss of 0.8 +/- 0.7 L. Hemodiluted preoperative hemoglobin was 8.7 +/- 1 g/dL. All of the global perfusion indices, except for arterial pH and oxygen consumption, decreased after hemodilution and recovered with the retransfusion of blood (P < or = 0.004). Splanchnic perfusion and coagulation tests were unchanged (P > or = 0.1). Major complication was pulmonary edema in one patient. CONCLUSION: Hemodilution during radical hysterectomy, in this select group of patients, does not appear to compromise tissue perfusion or coagulation.

Adult↗
PubMed2001

Stimulated release of arachidonic acid from rat liver cells by celecoxib and indomethacin.

The selective cyclooxygenase-2 (COX) inhibitor, celecoxib, and the non-selective COX-1 and COX-2 inhibitor, indomethacin, at microM concentrations, stimulate the release of arachidonic acid from rat liver cells (the C-9 cell line). Other non-steroidal anti-inflammatory drugs were tested, including salicylic acid, acetylsalicylic acid, sulindac sulfone, sulindac sulfide, ibuprofen, piroxicam and the selective COX-2 inhibitor, rofecoxib, and the analgesic, acetaminophen. These compounds do not stimulate the release of arachidonic acid. The stimulated release by celecoxib is not affected by dexamethasone or the translation and transcription inhibitors, actinomycin and cycloheximide. The increased arachidonic acid release may be associated with induction of apoptosis.

Animals↗
PubMed2001

Stimulated release of arachidonic acid by agonists of the peroxisome proliferator-activated receptor and retinoic acid receptors.

Release of arachidonic acid from rat liver cells is stimulated after a 6-hour incubation with 9-cis retinoic acid, all trans retinoic acid, the selective peroxisome proliferator-activated receptor-gamma synthetic thiazolidinedione, ciglitazone, the cyclopentenones, 15-deoxy-Delta(12,14) PGJ2 and PGA1 and the non-steroidal anti-inflammatory drugs, celecoxib and indomethacin. The rates of the release stimulated by 15-deoxy-Delta(12,14) PGJ2 differ from those observed with celecoxib. Arachidonic acid release by9-cis retinoic acid in the presence of either ciglitazone or trans retinoic acid is synergistic. It is additive in the presence of celecoxib. Cycloheximide and actinomycin inhibit the release of arachidonic acid stimulated by 15-deoxy-Delta(12,14) PGJ2 but not by celecoxib. The findings indicate that agonists of the peroxisome proliferator-activated receptor-gamma and retinoic acid receptors stimulate the release of arachidonic acid. The mechanisms involved may differ in the cases of 15-deoxy-Delta(12,14) PGJ2 and celecoxib.

Alitretinoin↗
PubMed2001

Preliminary report of immediately loaded Altiva Natural Tooth Replacement dental implants.

BACKGROUND: Osseointegration may be described as a direct contact between living bone and an alloplastic implant. It is thought that a period of undisturbed healing is required to ensure osseointegration. The length of the healing period is dependent on a number of factors, such as implant material, surface configuration, site preparation technique, bone quality, healing capacity of the osteotomy, and implant design. Elimination of the healing period offers distinct advantages in terms of cost of therapy and convenience to patients. Recently, a new one-piece implant design was proposed that provides improved stability of the implant to allow immediate support of an interim prosthesis. PURPOSE: This article presents the initial clinical experiences when the Altiva Natural Tooth Replacement one-piece implant was used in a human clinical trial. MATERIALS AND METHODS: This was a prospective multicenter study of the placement and immediate loading of the one-piece implant. A total of 142 implants were placed in the jaws of 93 patients. Implants were placed consecutively and were followed at specified intervals in three private clinical practices. Clinical performance was recorded relative to implant survival and prosthesis support. RESULTS: The implant survival rate was 93.7%, with similar responses in the maxilla (95.0%) and the mandible (92.7%). When implant failure occurred, it was observed as mobility without infection within 3 to 5 weeks of implant insertion. CONCLUSIONS: On the basis of this trial, there is promising evidence that this implant design can succeed at rates similar to other designs that require conventional healing times.

Adult↗
PubMed2001

Heat strain imposed by toxic agent protective systems.

This study evaluated physiological heat strain from two developmental toxic agent protective systems compared with the standard Toxicological Agent Protective (TAP) suit during exercise-heat stress. Eight subjects (six men, two women) completed three experimental trials, at 38 degrees C, 30% rh, wearing: 1) Self Contained Toxic Environment Protective Outfit (STEPO) with rebreather (STEPO-R); 2) STEPO with tether (STEPO-T) or 3) the standard TAP. The STEPO systems provided effective body cooling of: STEPO-R, 200 +/- 36 W; and STEPO-T, 186 +/- 59 W. TAP had no cooling. All experimental trials used treadmill walking at 0.89 m x s(-1), 0% grade at exercise/rest cycles of 20/10 min for 240 min. Metabolic rates for the treatments were: STEPO-R, 298 +/- 26 W; STEPO-T, 299 +/- 34 W; and TAP, 222 +/- 40 W. Rate of heat storage was less (p < 0.05) in STEPO-R (37 +/- 8 W x m(-2)) and STEPO-T (38 +/- 12 W x m(-2)) than in TAP (77 +/- 15 W x m(-2)). Sweating rate was less (p < 0.05) in STEPO-T (10.0 +/- 4.8 g x min(-1)) than in TAP (23.8 x 11.4 g x min(-1)). There was no difference between STEPO-R (12.3 +/- 5.6 g min(-1)) and the other two uniform systems. Subjects did not complete targeted exposure times of 240 min. Exposure time was longer (p < 0.05) in STEPO-R (83 +/- 22 min) and STEPO-T (106 +/- 39 min) than in TAP (46 +/- 10 min). Predicted time to 39.0 degrees C was less (p < 0.05) in TAP (69 +/- 20 min) than in either STEPO-R (226 +/- 124 min) or STEPO-T (244 +/- 170 min). The results of this study show that cooling in STEPO significantly reduced heat storage relative to TAP. The new generation toxic cleanup uniform systems effectively reduced heat stress and increased work capabilities compared with the standard TAP suit.

Adult↗
PubMed2001

Heat strain evaluation of chemical protective garments.

BACKGROUND: The purpose of this study was to compare thermoregulatory and subjective responses of 12 test subjects (10 male, 2 female) wearing 5 different Joint Service Lightweight Integrated Suit Technology (JSLIST) prototype and 3 different currently fielded control chemical/ biological (CB) protective overgarments. METHODS: The overgarments were compared while subjects attempted to complete 100 min of moderate exercise (400 W) in an environmental chamber (35 degrees C/50% rh). Rectal temperature (Tre), skin temperature, heart rate, sweating rate, and test time, as well as subjective symptoms of heat illness were measured. Data were analyzed for times earlier than 100 min because subjects were not usually able to complete the 100-min trials. RESULTS: At 50 min, of the 3 controls, the Army/Air Force Battledress Overgarment (BDO) imposed significantly greater heat strain (indicated by Tre 37.90 degrees C) than the Marine Saratoga (SAR) (Tre 37.68 degrees C) and Navy Chemical Protective Overgarment (CPO) (Tre 37.69 degrees C). The JSLIST prototype garments imposed heat strain (50 min Tre 37.73-37.86 degrees C) as well as subjective perception of heat strain, that ranged between the warmest and coolest controls. CONCLUSIONS: In the environmental and exercise test conditions of this study, we did not find the five JSLIST overgarments to be consistently different from one another. Subjects in the control garments were and felt generally warmer (BDO) or cooler (SAR, CPO) than in the JSLIST prototype garments.

Adult↗
PubMed2000

A combination of lactacystin and 12-O-tetradecanoylphorbol-13-acetate enhances the release of arachidonic acid from cells in cultures: release is reduced in confluent and serum deprived cells.

Lactacystin, a selective inhibitor of some proteasome activities, in the presence of 12-tetradecanoyl phorbol-13-acetate stimulates the release of arachidonic acid from the phospholipids of bovine pulmonary artery endothelial, bovine embryonic thoracic aorta smooth muscle, rat liver and rat glial cells. The enhanced release from rat liver cells is inhibited by dexamethasone, aspirin, Na salicylate and the immunosuppressive fungal metabolite, gliotoxin. The effects of aspirin plus dexamethasone are not additive, but those of gliotoxin plus dexamethasone are additive. The stimulated and unstimulated release from all four cells are decreased when these cells are grown to confluence or when they are growth arrested by serum deprivation. The unstimulated as well as the stimulated release is partially inhibited by the cytosolic phospholipase A2 inhibitor, methylarachidonyl fluorophosphonate. The enhanced release is reduced in the presence of the translation and transcription inhibitors, actinomycin and cycloheximide.

Acetylcysteine↗
PubMed2000

Lactacystin stimulates arachidonic acid metabolism in rat liver cells: effects of cell density on arachidonic acid release, PGI2 production and cyclooxygenase activity.

Lactacystin, an inhibitor of proteasome activity, amplifies prostaglandin I2 production by rat liver cells stimulated by 12-O-tetradecanoylphorbol-13-acetate, transforming growth factor-alpha or interleukin-1. Lactacystin also stimulates the cell's release of arachidonic acid (AA) and increases the cyclooxygenase activity in these cells. In serum deprived cells, the enhanced AA release is reduced, cyclooxygenase activity on exogenous AA is increased and endogenous production of prostaglandin I2 is unchanged. These findings suggest that, in vivo, the ratio of dividing to quiescent cells in a tissue may influence eicosanoid production. The increases in prostaglandin I2 production, AA release and cyclooxygenase activity on exogenous AA resulting from the combined lactacystin and 12-O-tetradecanoylphorbol-13-acetate treatment are inhibited by actinomycin or cycloheximide.

Acetylcysteine↗
PubMed2000

Evidence for palytoxin as one of the sheep erythrocyte lytic in lytic factors in crude extracts of ciguateric and non-ciguateric reef fish tissue.

The occurrence of palytoxin or its congener in fish extracts has been presented in this study. The presences of hemolytic factors in fish extracts of Hawaiian reef fish and their implication in ciguatera poisoning have been shown by the sheep erythrocyte assay. By use of the anti-palytoxin inhibition assay with fish extracts and sheep red blood cell (RBC), it was shown that palytoxin was one of the major factors in the lysis of sheep erythrocytes. Ouabain, an antagonist of palytoxin for the Na+/K+ ATPase receptor on RBC, also showed inhibition of sheep RBC lysis by fish extracts. From these results, it was concluded that, in part, palytoxin and other palytoxin-related, hemolysin-like factors in fish extracts were responsible for sheep cell hemolysis.

Acrylamides↗
PubMed1999

Fluorescence polarization in homogeneous nucleic acid analysis.

A new method for DNA diagnostics based on template-directed primer extension and detection by fluorescence polarization is described. In this method, amplified genomic DNA containing a polymorphic locus is incubated with oligonucleotide primers (designed to hybridize to the DNA template adjacent to the polymorphic site) in the presence of allele-specific dye-labeled dideoxyribonucleoside triphosphates and a commercially available modified Taq DNA polymerase. The primer is extended by the dye-terminator specific for the allele present on the template, increasing approximately 10-fold the molecular weight of the fluorophore. At the end of the reaction, the fluorescence polarization of the two dye-terminators in the reaction mixture are analyzed directly without separation or purification. This homogeneous DNA diagnostic method is shown to be highly sensitive and specific and is suitable for automated genotyping of large number of samples. [The data shown in Figure 3 are available as an online supplement at.]

DNA↗