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At least 649 records · Page 36Linked to original sources
PubMed1997

Monitoring the abundance of Aedes (Ochlerotatus) albifasciatus (Macquart 1838) (Diptera: Culicidae) to the south of Mar Chiquita Lake, central Argentina, with the aid of remote sensing.

Surges in the size of adult populations of the flood-water mosquito Aedes albifasciatus can produce important economical losses because of the way this species irritates livestock. Although this species is also the main vector of west equine encephalitis in Argentina, little is known about the factors affecting its population dynamics, as it is difficult to obtain data on its abundance over a large area. However, the results of intensive study of the mosquito in a few sites might reasonably be extrapolated to a regional scale by the use of remotely sensed data. The adult, larval and pupal stages of Ae. albifasciatus were sampled at five field sites to the south of Mar Chiquita Lake, either once a month (during the dry, cold season) or once a fortnight (during the warm, rainy season), between August 1992 and April 1993. The measured abundance of adults or pre-adults and a meteorological coefficient useful for the estimation of larval abundance each showed significant correlation with various statistics derived from normalized-difference, vegetation indices (NDVI) calculated from satellite (NOAA-AVHRR) imagery. A linear discriminant analysis, using data on NDVI, rainfall and temperature, accurately identified periods with and without pre-adults. The satellite imagery was also useful in the estimation of larval abundance and consequently could be used to predict adult abundance 7 days in advance. Even though the satellite data employed have poor spatial resolution, their high temporal resolution makes them very useful in studies of the population dynamics of mosquitoes in general, at least once the relevant variables and their relationships with mosquito breeding and survival have been identified.

Aedes↗
PubMed1989

A comparison of two ambulatory blood pressure monitors, the Del Mar Avionics Pressurometer IV and the Spacelabs 90202.

The purpose of this study was to evaluate the accuracy of two noninvasive ambulatory blood pressure (BP) monitors, the new Del Mar Avionics Pressurometer IV (PIV) and the second generation Spacelabs 90202. Two sets of comparisons were made between two trained observers and the monitors on 17 normotensive and 28 hypertensive subjects. The result of the first comparison showed that the average difference between observers and the PIV was 1.2/-2.2 mm Hg for systolic and diastolic BP. Comparisons of both monitors to the observers showed differences of 0.9/1.0 mm Hg for the PIV and 0.3/0.8 mm Hg for the 90202 (systolic/diastolic). Correlations between the average observer reading and the monitors over both sets of comparisons ranged from 0.90 (diastolic 90202 vs observer) to 0.98 (systolic PIV vs observer). The percentage of readings within 5 mm Hg between observer and monitor over all comparisons ranged from a low of 68% (90202, systolic and diastolic) to a high of 83% (PIV, diastolic). In general, both devices are satisfactory and reliable machines for ambulatory BP monitoring, but each has a slightly different bias compared to auscultatory readings.

Adult↗
PubMed1997

Cells strongly expressing Ig(kappa) transgenes show clonal recruitment of hypermutation: a role for both MAR and the enhancers.

The V regions of immunoglobulin kappa transgenes are targets for hypermutation in germinal centre B cells. We show by use of modified transgenes that the recruitment of hypermutation is substantially impaired by deletion of the nuclear matrix attachment region (MAR) which flanks the intron-enhancer (Ei). Decreased mutation is also obtained if Ei, the core region of the kappa3'-enhancer (E3') or the E3'-flank are removed individually. A broad correlation between expression and mutation is indicated not only by the fact that the deletions affecting mutation also give reduced transgene expression, but especially by the finding that, within a single mouse, transgene mutation was considerably reduced in germinal centre B cells that poorly expressed the transgene as compared with strongly expressing cells. We also observed that the diminished mutation in transgenes carrying regulatory element deletions was manifested by an increased proportion of B cells in which the transgene had not been targeted at all for mutation rather than in the extent of mutation accumulation once targeted. Since mutations appear to be incorporated stepwise, the results point to a connection between transcription initiation and the clonal recruitment of hypermutation, with hypermutation being more fastidious than transcription in requiring the presence of a full complement of regulatory elements.

Animals↗
PubMed2005

Induction of transcription within chromosomal DNA loops flanked by MAR elements causes an association of loop DNA with the nuclear matrix.

The spatial organization of an approximately 170 kb region of human chromosome 19, including CD22 and GPR40-GPR43 genes, was studied using in situ hybridization of a set of cosmid and PAC probes with nuclear halos prepared from proliferating and differentiated HL60 cells. The whole region under study was found to be looped out into the nuclear halo in proliferating cells. It is likely that the loop observed was attached to the nuclear matrix via MAR elements present at the flanks of the area under study. Upon dimethyl sulfoxide-induced differentiation of the cells the looped fragment became associated with the nuclear matrix. This change in the spatial organization correlated with the activation of transcription of at least two (CD22 and GPR43) genes present within the loop. The data obtained are discussed in the framework of the hypothesis postulating that the spatial organization of chromosomal DNA is maintained via constitutive (basic) and facultative (transcription-related) interactions of the latter with the nuclear matrix.

Base Sequence↗
PubMed2006

A prospective multicentre study of the role of anaemia as a risk factor in haemodialysis patients: the MAR Study.

BACKGROUND: Retrospective studies have shown hospitalization and mortality rates during haemodialysis (HD) to be associated with anaemia. METHODS: The prospective, multicentre Morbidity-and-mortality Anaemia Renal (MAR) study was designed to establish the burden of anaemia by controlling for other risk factors. Charlson index was used for comorbid adjustment. Finally, 1428 patients from 119 centres (60% men, aged 64.4 years, time on HD 15.3 months, Charlson comorbidity index 6.5 +/- 2.3) completed follow-up. They had hypertension (75.8%), diabetes mellitus (25.9%), heart failure (13.9%) and coronary disease (16.7%). Of the total patients, 94.8% were receiving erythropoietin (111.6 +/- 70.6 U/kg/week) and 76.7% i.v. iron, and haemoglobin (Hb) at inclusion was 11.7 +/- 1.5 g/dl. RESULTS: Hospitalization rate was 1.1 admissions/patient/year. Yearly mortality was 12% [35% cardiovascular (CV)]. The relative risk and confidence interval (CI) for hospitalization and death were 0.86 (0.81-0.91) and 0.82 (0.73-0.91), respectively, per 1 g/dl increase in initial Hb after adjustment for comorbidity, vintage, aetiology, access type, albumin and Kt/V. The probability of remaining free from hospitalization (CI) was 0.34 (0.27-0.41) for initial Hb <10 g/dl, 0.47 (0.41-0.53) for Hb 10-11 g/dl, 0.54 (0.49-0.59) for Hb 11-12 g/dl, and 0.63 (0.59-0.67) for Hb >12 g/dl. Same analysis for patient survival was 0.77 (0.71-0.83) for Hb <10 g/dl vs 0.82 (0.77-0.87) for Hb 10-11 vs 0.89 (0.86-0.92) for Hb 11-12 vs 0.92 (0.90-0.94) for Hb > 12 g/dl, P < 0.001. The Cox regression model for hospitalization-free survival included the risk factors initial Hb (relative risk 0.86 per 1 g/dl increase, P < 0.001) Charlson, albumin and prior CV event. CONCLUSION: Hb level predicted 1-year-survival and hospitalization. This effect persisted after adjustment for comorbidity and other prognostic factors.

Aged↗
PubMed1996

Microdosimetric-based risk factors for radiation received in space activities during a trip to Mars.

A system for evaluating quality factors, Q, based on the microdosimetric distribution of the radiation field of interest has been set up; it makes use of a specific quality function (SQF) to obtain--given microdosimetric spectra--values for Q. The advantages of a system based on lineal energy are well recognized. Furthermore, recent studies have shown that spectra in 1-microm diameter tissue-equivalent spherical volumes reproduce correctly (in the sense of this formalism) measured RBE values, and thus a proportional counter would be usable as a practical instrument for radiation protection. All specific quality functions, q(y), available to date have been calculated from in vitro cellular data. To extend this approach to radiations of interest in space activities we have recently obtained a new function q(y) for in vivo radiogenic neoplasia using data on the Harderian gland of the mouse. These data were obtained for charged particles and energies relevant to space exposures. Furthermore, we introduce a new procedure that allows one to obtain--here with the use of microdosimetric distributions for the Hiroshima-Nagasaki radiation fields--risk factors scaled from the A-bomb survivorship results. We apply these concepts to particles and energies representing the galactic spectrum. We estimate that for a trip to Mars (450 d) the excess lifetime cancer mortality due to galactic cosmic ray (GCR) radiation is 0.037. This is about 50% lower than the risk coefficient obtained with the aid of standard (LET-based) quality factors.

Aerospace Medicine↗
PubMed1988

A validation study of the Del Mar Avionics Pressurometer IV according to AAMI guidelines.

Guidelines for the evaluation of automatic non-invasive blood pressure (BP) measurement devices have recently been established by the Association for the Advancement of Medical Instrumentation (AAMI). We evaluated the Del Mar Avionics Pressurometer IV (P4) in tests on 109 subjects, according to these guidelines. Three readings by two observers using a double stethoscope were first compared to each other to determine a standard and then averaged and compared to readings obtained using the P4. The two observers agreed within +/- 6 mmHg or 90% of the readings for both systolic and diastolic BP, with correlations of 0.99 and 0.98 for systolic and diastolic BP, respectively. The observers and the P4 in turn agreed to within +/- 6 mmHg for 85% of the readings for systolic BP, with a correlation of 0.98, and 65% of the readings for diastolic BP, with a correlation of 0.69. The correlations for both systolic and diastolic BP increased to 0.99 when readings were restricted to those obtained in individuals who fulfilled our previously defined calibration criterion of +/- 5 mmHg. In addition, we evaluated nine measurements of performance over 60 ambulatory recordings. The most serious problem was that of missing data which occurred in 85% of the recordings, primarily during sleep hours, and was generally attributed to either detection of Korotkoff sounds below 40 mmHg or a failure to detect Korotkoff sounds.

Adult↗
PubMed2001

Role of the mar locus in virulence of Salmonella enterica serovar Typhimurium DT104 in chickens.

The virulence of a Salmonella enterica serovar Typhimurium DT014 strain in which marA was insertionally inactivated was compared to its isogenic parent in vitro and in vivo. In vitro, the numbers of the marA mutant phagocytosed by porcine lung macrophages were significantly increased, while survival at 24 h inside macrophages and adherence to human gut cells were significantly reduced in comparison with the parent strain. In vivo, the marA inactivated strain, in competition with its parent strain, persisted for a shorter period in chickens, was present in the caeca at significantly lower levels and invaded the deeper organs to a significantly lesser extent. Therapeutic antibiotic treatment of one group of chickens with oxytetracycline favoured the persistence of both the parent strain and, to a lesser extent, the marA inactivated strain; but interestingly, increased tetracycline resistance of Salmonella isolates after treatment of birds with antibiotic was seen only for the parent strain. Further work is needed to elucidate how mar is involved in virulence and if its inactivation can minimise the ability of bacteria to become antibiotic-resistant in vivo.

Animals↗
PubMed2005

Transport of Mars-crossing asteroids from the quasi-Hilda region.

We employ set oriented methods in combination with graph partitioning algorithms to identify key dynamical regions in the Sun-Jupiter-particle three-body system. Transport rates from a region near the 3:2 Hilda resonance into the realm of orbits crossing Mars' orbit are computed. In contrast to common numerical approaches, our technique does not depend on single long term simulations of the underlying model. Thus, our statistical results are particularly reliable since they are not affected by a dynamical behavior which is almost nonergodic (i.e., dominated by strongly almost invariant sets).

Journal Article↗
PubMed1979

Prader-Willi syndrome and chromosomal mosaicism 46,XY/47,XY,+mar in two cases.

Two cases of the Prader-Willi syndrome with 46,XY/47,XY,+mar are reported. The majority of Prader-Willi patients with chromosome abnormalities have either 15/15 translocations or mosaicism. Both of these aberrations presumably occur after fertilization. A possible relationship between high parental age and chromosome abnormalities in the Prader-Willi syndrome is discussed.

Child↗
PubMed2001

Mars and Venus: unequal planets.

Self-help books, a pervasive and influential aspect of society, can have a beneficial or detrimental effect on the therapeutic process. This article describes a thematic analysis and feminist critique of the best-selling self-help book, Men are from Mars, Women are from Venus. This analysis revealed that the author's materials are inconsistent with significant family therapy research findings and key principles of feminist theories. His descriptions of each gender and his recommendations for improving relationships serve to endorse and encourage power differentials between women and men.

Books↗
PubMed2003

Discovery of olivine in the Nili Fssae region of Mars.

We have detected a 30,000-square-kilometer area rich in olivine in the Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of grabens and fractures related to the formation of the Isidis impact basin. We propose that post-impact faulting of this area has exposed subsurface layers rich in olivine. Linear mixture analysis of Thermal Emission Spectrometer spectra shows surface exposures of 30% olivine, where the composition of the olivine ranges from Fo30 to Fo70.

Journal Article↗
PubMed1995

Development of multiple-antibiotic-resistant (Mar) mutants of Pseudomonas aeruginosa after serial exposure to fluoroquinolones.

Laboratory-derived fluoroquinolone-resistant mutants were created by serially passaging wild-type Pseudomonas aeruginosa on fluoroquinolone-containing agar to obtain high-level fluoroquinolone resistance (e.g., ciprofloxacin MIC of 1,024 micrograms/ml). With increases of 4- to 32-fold in MICs of fluoroquinolones, these organisms demonstrated (relative to wild-type) normal morphology, resistance to fluoroquinolones only, no change in fluoroquinolone uptake, and no change in lipopolysaccharide profiles or outer membrane protein profiles. Complementation with wild-type Escherichia coli gyrA restored fluoroquinolone susceptibility, suggesting that these were gyrA mutants. After 4- to 32-fold increases in fluoroquinolone MICs (with continued passage on fluoroquinolone-containing agar) isolates demonstrated altered morphology, a multiple-antibiotic-resistant (Mar) phenotype (including cross-resistance to beta-lactams, chloramphenicol, and tetracycline), reduced fluoroquinolone uptake and altered outer membrane proteins (reductions in the 25- and 38-kDa bands as well as several bands in the 43- to 66-kDa region). Complementation with wild-type E. coli gyrA partially reduced the level of fluoroquinolone resistance by approximately 8- to 32-fold, suggesting that these mutants displayed both gyrA and non-gyrA mutations.

Anti-Infective Agents↗
PubMed1970

Measurement of CO(2) Assimilation in Soils: an Experiment for the Biological Exploration of Mars.

A method is described for the measurement of CO(2) assimilation by microorganisms in soils. A determination involves exposing soil to CO(2), pyrolyzing the exposed soil, trapping the organic pyrolysis products on a column of firebrick coated with CuO, combusting the trapped organics by heating, and measuring the radioactivity in the CO(2) produced in the combustion. The detection of significant levels of C in the trapped organic fraction appears to be an unambiguous indication of biological activity. The CO(2) which is adsorbed or exchanged into soils by nonbiological processes does not interfere. The method easily detects the CO(2) fixed by 10 to 10 algae after light exposure for 3 to 24 hr. Assimilation of C is also demonstrable in dark-exposed soils containing 10 to 10 heterotrophic bacteria. Possible applications of the method in the biological exploration of Mars are discussed.

Journal Article↗
PubMed1971

Dry-heat resistance of bacterial spores recovered from mariner-Mars 1969 spacecraft.

The dry-heat resistances of 70 bacterial spore isolates recovered from Mariner-Mars 1969 spacecraft were determined and expressed as D values (decimal reduction times). Fifty per cent of the spore isolates had D values of 60 min or less at 125 C. Of organisms with D values greater than 60 min, four were selected for a study of the effect of sporulation medium and suspension menstruum on dry-heat resistance. Both sporulation medium and suspension menstruum were found to affect significantly the dry-heat resistance of the bacterial spores tested.

Journal Article↗
PubMed1971

Relative frequency distribution of d(125 C) values for spore isolates from the mariner-Mars 1969 spacecraft.

Bacterial spore crops were prepared from 103 randomly selected aerobic mesophilic isolates collected during a spore assay of Mariner-Mars 1969 spacecraft conducted by the Jet Propulsion Laboratory. D(125 c) values, which were determined by the fractional-replicate-unit-negative-most-probable number assay method using a forced air oven, ranged from less than 5 min to a maximum of 58 min. Subsequent identification of the 103 isolates indicated that there was no relationship between species and dry-heat resistance. A theoretical dry-heat survival curve of the "population" was nonlinear. The slope of this curve was determined almost exclusively by the more resistant organisms, although they represented only a small portion of the "population."

Journal Article↗
PubMed2006

Role for tandem duplication and lon protease in AcrAB-TolC- dependent multiple antibiotic resistance (Mar) in an Escherichia coli mutant without mutations in marRAB or acrRAB.

A spontaneous mutant (M113) of Escherichia coli AG100 with an unstable multiple antibiotic resistance (Mar) phenotype was isolated in the presence of tetracycline. Two mutations were found: an insertion in the promoter of lon (lon3::IS186) that occurred first and a subsequent large tandem duplication, dupIS186, bearing the genes acrAB and extending from the lon3::IS186 to another IS186 present 149 kb away from lon. The decreased amount of Lon protease increased the amount of MarA by stabilization of the basal quantities of MarA produced, which in turn increased the amount of multidrug effux pump AcrAB-TolC. However, in a mutant carrying only a lon mutation, the overproduced pump mediated little, if any, increased multidrug resistance, indicating that the Lon protease was required for the function of the pump. This requirement was only partial since resistance was mediated when amounts of AcrAB in a lon mutant were further increased by a second mutation. In M113, amplification of acrAB on the duplication led to increased amounts of AcrAB and multidrug resistance. Spontaneous gene duplication represents a new mechanism for mediating multidrug resistance in E. coli through AcrAB-TolC.

Anti-Bacterial Agents↗