Biomedical subjects

R Guillermo

Publications and source records attributed to R Guillermo.

10 recordsLinked to original sources

PubMed2005

A case study of personal exposure to nitrogen dioxide using a new high sensitive diffusive sampler.

Personal NO(2) exposure measurements were achieved during two campaigns in a large northern France city. These campaigns were following an innovating approach based on sequential exposure measurements by diffusive samplers distinguishing four categories of microenvironments ("home", "other indoor places", "transport" and "outdoors"). The objective of these campaigns was to obtain NO(2) personal exposure data in different microenvironments and to examine the determinants of personal exposure to this pollutant. Each campaign comprised two 24-h sampling periods: one during a working day and the second during the weekend. The average total NO(2) personal exposure ranged from 17 microg m(-3) for the summer weekend samplings to 38 microg m(-3) for the winter weekday samplings. The highest levels were found in transports and outdoors, the intermediate ones in other indoor places and the lowest in homes. Despite their weak levels, indoor environments contributed for more than 78% to total NO(2) personal exposure because of more time spent in these living places. A Multiple Correspondence Analysis (MCA) highlighted the determinants of NO(2) personal exposure in the "home" and "transport" microenvironments. This led to a classification of NO(2) personal exposure levels according to different means of transport: from the lowest to the highest exposure levels, train, tramway or underground, bicycle, car or motorcycle. In homes, the rise of NO(2) personal exposures is mainly due to the use of gas stoves and gas heating and the absence of automatic airing system. A classification of NO(2) personal exposure levels was set up according to the characteristics of homes. An analysis of correlations between the home NO(2) personal exposures and outdoor concentrations measured by fixed ambient air monitoring stations showed weak relations suggesting that the data of these stations are poor predictors of NO(2) personal exposures in homes.

Air Pollutants↗

PubMed2003

Validation tests of a new high uptake rate passive sampler for nitrogen dioxide measurements.

This study explains the main characteristics of a new passive sampler which is able to give reliable nitrogen dioxide measurements for short time sampling. The sampling rate was found to be on average 0.89 cm3 s(-1) for indoor sampling and 1.00 cm3 s(-1) for outdoor sampling. The detection limit was evaluated at 11 microg m(-3) for a one-hour measurement. In field conditions, the passive sampler measurements were in agreement with those of the chemiluminescent NOx monitors. Measurement uncertainties were estimated at 34% and 38% for laboratory tests in conditions corresponding respectively to indoor and outdoor measurements and were evaluated at 28 to 37% depending on the nitrogen dioxide concentration for field experiments. The effects of various factors on the passive sampler were determined in an exposure chamber. The sampling rate of the retained sampler version was not significantly influenced by wind speeds superior to 0.3 m s(-1). A decrease of the uptake rate is observed for high nitrogen dioxide doses. The sampling rate increases linearly with temperature (2% per degree C). The relative humidity has only a weak effect.

Air Pollutants↗

PubMed2002

Characterisation of NMHCs in a French urban atmosphere: overview of the main sources.

Continuous hourly air quality data involving 37 C2-C9 non-methane hydrocarbons (NMHC) over 4 years are reported for the first time in Lille metropol, northern France, at two urban roadside and background sites. The data have been analysed in two complementary steps: univariate statistics which define the spatial and temporal characteristics of NMHC by constructing the seasonal and daily concentration profiles, and multivariate statistics based on principal component analysis (PCA). A number of important sources have been clearly identified depending on the season: (1) motor vehicle exhaust, which dominates the NMHC distribution and particularly in winter, even for isoprene; (2) wintertime stationary combustion and activities related to fossil fuel consumption in general, such as natural gas leakage of ethane and propane; (3) summertime evaporative emissions from fuel and solvent; and (4) summertime biogenic emissions through isoprene behaviour and their dependence on temperature.

Journal Article↗

PubMed2002

Performances and application of a passive sampling method for the simultaneous determination of nitrogen dioxide and sulfur dioxide in ambient air.

The performances and applicability of a diffusion tube sampler for the simultaneous measurements of NO2 and SO2 in ambient air were evaluated. SO2 and NO2 are collected by the passive sampler using triethanolamine as trapping agent and are determined as sulphate and nitrite with ion chromatography. The detection limit (2.3 microg m(-3) of NO2 and 4.2 microg m(-3) of SO2 for two weeks sampling) is adequate for the determination of concentrations in urban and industrial areas. Precision of the method as RSD is in mean 5% for NO2 and 12% for SO2 at the concentration levels in urban areas. Calibration of the method was performed in the field conditions by comparison between the responses of sampler and the concentrations measured by the continuous monitors. High degree of linearity (correlation coefficients > 0.8) is found between the passive sampler tube and the continuous monitor data for both NO2 and SO2. To reduce the wind velocity influence on passive sampling of diffusion tubes, a protective shelter was tested in this study. The overall uncertainty of one measure for the optimised method is estimated at 5 microg m(-3) for NO2 and 6 microg m(-3) for SO2. Suitability of this passive sampling method for air pollution monitoring in urban areas was demonstrated by the results shown in this paper on a campaign carried out in the French agglomeration.

Air Pollutants↗

PubMed2000

Multi-element analysis by inductively coupled plasma optical emission spectrometry of airborne particulate matter collected with a low-pressure cascade impactor.

A method was developed for the elemental analysis of size segregated particles ranging from 0.03 to 10 microns. Sampling and analysis problems are discussed in this paper. Particles were collected with a Dekati low-pressure cascade impactor. PTFE filters coated with oleic acid were used as substrate. Particles were microwave digested in closed vessels. The optimum digestion mixture was composed of HNO3 (1 mL), HF (50 microL) and H2O (1 mL). The optimal power setting and digestion time were studied in order to achieve an efficient digestion. A ca. 35 min microwave digestion cycle at a 650 W maximum power allowed complete digestion of the samples. Special emphasis was placed on the pressure in the closed vessels to avoid sample losses. Solution samples were analysed by inductively coupled plasma optical emission spectrometry using an ultrasonic nebuliser for 18 elements (Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, S, Sr, Ti, V, Zn). This procedure was tested with NIST Standard Reference Material 1648 Urban Particulate. Recoveries for certified elements ranged from 95 to 105% except for Al (90%). The influence of cascade impactor materials was investigated with 44 field samples. Strong artefacts due to contamination were shown for analysis at environmental concentrations of Al, Cr, Mn and Ni.

Air Pollutants↗

PubMed1999

Identification of a peptide directed against the anti-CD34 antibody, 9C5, by phage display and its use in hematopoietic stem cell selection.

A peptide sequence was identified by phage display technology that could be used as an alternative to chymopapain for the release of hematopoietic progenitor cells captured by anti-CD34 monoclonal antibodies. This was achieved by affinity selection screening (biopanning) of a random hexapeptide sequence phage display library. Four rounds of biopanning were performed to enrich for phage clones with specific affinity for anti-CD34 monoclonal antibody, 9C5. DNA sequence analyses of these phage clones revealed an enrichment of two predominant sequences, QQGWFP and TQGSFW. These two clones also shared a consensus sequence motif, QGxF, that exhibited 50% and 67% homology with a region spanning amino acids 14-19 of the mature CD34 antigen. Based on these data, synthetic peptides were generated and assessed for their ability to release 9C5 from CD34+ cells. Using a flow cytometric assay, it was found that the synthetic peptide, 9069N, effectively released 9C5 from the CD34-expressing cell line, KG1a, in a concentration-dependent manner (77% and 99% release of 9C5 at 0.14 and 0.70 mM peptide concentrations, respectively). In the Isolex 300i immunomagnetic selection system, this peptide was shown to be effective at releasing 9C5 sensitized CD34+ hematopoietic progenitors from sheep anti-mouse IgG Dynabeads. Thus, a synthetic peptide, which specifically and efficiently released immunomagnetically selected hematopoietic progenitor cells from paramagnetic beads, was identified. This reagent is a significant advance in the selection of hematopoietic progenitors in that it does not alter cell surface antigens. As such, further phenotypic characterization or immunoselection can be performed.

Amino Acid Sequence↗

PubMed1998

Microbiological transformation of manoyl oxide derivatives by Mucor plumbeus.

Biotransformations of jhanol (18-hydroxymanoyl oxide) (2), jhanidiol (1beta,18-dihydroxymanoyl oxide) (3), and 1-oxo-jhanol (1-oxo-18-hydroxymanoyl oxide) (4) by the fungus Mucor plumbeus have been studied. In the incubation of 2 there exists a preference for hydroxylation at C-2(alpha) (8) and C-6(beta) (9-11) and, to a lesser degree, at C-1(alpha) (7), C-11(alpha) (6), and C-11(beta) (5 and 10). In the second substrate (3), the presence of a 1beta-hydroxyl group inhibits 6beta- or 11-hydroxylation. Epoxidation of the vinyl group constitutes the main reaction, with the positions 2alpha (14) and 3beta (15) being hydroxylated. In the incubation of 4, there was a preference for 6beta-hydroxylation (21) or epoxidation of the vinyl group (22). Other hydroxylations observed were at the 2alpha (19), 2beta (20), 3alpha (23), 3beta (24), and 11beta (18) positions.

Biotransformation↗

PubMed1998

Differential response of glomerular epithelial and mesangial cells after subtotal nephrectomy.

Recent studies in both human and experimental chronic renal disease suggest that there is a linkage between glomerular hypertrophy and glomerulosclerosis. To further define these relationships, we studied the changes in glomerular hypertrophy, procollagen alpha 1(IV) mRNA levels and glomerulosclerosis in rats undergoing 1 2/3 nephrectomy (Nx) or sham nephrectomy (SNx). Glomerular hypertrophy, measured biochemically by RNA/DNA and protein/DNA ratios, was significantly increased in Nx compared to SNx two days after subtotal renal ablation (RNA/DNA: Nx = 133 +/- 8%, SNx = 100 +/- 3% of the mean control value, P < 0.01; protein/DNA: Nx = 164 +/- 22%, SNx = 100 +/- 10%, P < 0.05) and remained elevated after 7 and 15 days (RNA/DNA: seven days Nx = 155 +/- 3%, SNx = 100 +/- 13%, P < 0.01; 15 days Nx = 303 +/- 21%, SNx = 100 +/- 24%, P < 0.001; protein/DNA: seven days Nx = 228 +/- 57%, SNx = 100 +/- 18%, P < 0.05; 15 days Nx = 341 +/- 23%, SNx = 100 +/- 18%, P < 0.01). Light microscopic measures of glomerular tuft volume (GTV) were too insensitive to detect glomerular enlargement until 15 days postoperatively, but GTV measured ultrastructurally demonstrated a 20% increment in Nx compared to SNx as early as two days postoperatively (P < 0.01). The latter increment in GTV was due exclusively to glomerular visceral epithelial cell (GVEC) expansion. Glomerular procollagen alpha 1(IV) mRNA levels were significantly elevated only 15 days after nephrectomy (Nx = 265 +/- 58% of the mean control value, SNx = 100 +/- 12%, P < 0.05; corrected for beta-actin mRNA levels). As this time, exuberant mesangial expansion measured ultrastructurally contributed to a 1.6 +/- 0.1-fold increase in GTV (P < 10(-5)), and to a relative decrement in the GVEC contribution to glomerular cells plus matrix (P < 0.01). Segmental sclerosis was observed only 15 days postoperatively in Nx (Nx = 1.3 +/- 0.4% of glomeruli evaluated, SNx = 0.0%, P < 0.05), and there was a strong correlation between the prevalence of segmental sclerosis and the procollagen alpha 1(IV) mRNA levels in Nx at 15 days (r = 0.93, P < 0.01). There was no significant correlation between the RNA/DNA and protein/DNA ratios and procollagen alpha 1(IV) mRNA levels. Thus, glomerular regions responded differentially to subtotal nephrectomy. Early epithelial cell expansion was followed by later mesangial expansion. Glomerular procollagen alpha 1(IV) mRNA levels were elevated only during the second (mesangial) phase of glomerular hypertrophy, when it correlated with glomerulosclerosis, but not during the initial (epithelial) phase, a pattern consistent with a mesangial origin of the procollagen alpha 1(IV) mRNA.

Animals↗

PubMed1994

The microbiological transformation of two ent-16 beta,17-epoxykaurane derivatives by Gibberella fujikuroi.

The biotransformation of ent-16beta-17-epoxy-7 alpha-hydroxykaurane by Gibberella fujikuroi affords ent-7 alpha,11 alpha,16 beta,17-tetrahydroxykaurane and ent-7 alpha, 9 alpha, 16 beta, 17-tetrahydroxykaurane. These results indicated that the presence of the 16 alpha, 17-diol group, into which the 16 alpha, 17-epoxy is transformed in the medium, inhibits oxidation at C-19 and favours hydroxylation at C-11(beta). Incubation of ent-16 beta, 17-epoxykauran-19-oic acid, via the 16 alpha, 17-diol, gave the 7-aldehyde of 16 alpha, 17-dihydroxy-GA12.

Biotransformation↗

PubMed1992

Early increased renal procollagen alpha 1(IV) mRNA levels in streptozotocin induced diabetes.

Changes in renal procollagen mRNA levels were measured shortly after the induction of streptozotocin induced diabetes in the rat. "Medullary" procollagen alpha 1(IV) levels seven days after diabetes induction was significantly higher in untreated diabetic rats (DM, N = 12; 244 +/- 57% of the mean control value), than in diabetic rats receiving small doses of insulin insufficient to achieve euglycemia (NPH, N = 10; 87 +/- 12%) and in diluent injected nondiabetic control rats (C, N = 15; 100 +/- 12%; P less than 0.01, DM vs. C and DM vs. NPH). "Medullary" procollagen alpha 1(I) mRNA levels were numerically increased in DM to a lesser degree (141 +/- 5%, ANOVA not significant) compared to C (100 +/- 13%), and this small increment was further normalized by insulin treatment (NPH, 120 +/- 11%). A trend for increased beta-actin mRNA levels in DM did not reach significance (P greater than 0.05). Increases in "medullary" procollagen mRNA levels did not correlate with kidney weight, glomerular tuft volume, creatinine clearance, food intake, or body weight gain, and occurred when renal morphology was normal by light microscopy. Statistically significant but weak correlations were noted between the serum glucose levels and "medullary" procollagen alpha 1(IV) mRNA levels (r = 0.43, P less than 0.05). In addition, weak correlations were noted between glycosuria and "medullary" procollagen alpha 1(I) levels (r = 0.38, P less than 0.05). In situ hybridization studies localized the increased procollagen alpha 1(IV) mRNA levels predominantly in the DM group primarily in the deep cortex and medullary outer stripe of proximal tubules. Glomerular procollagen alpha 1(IV), alpha 1(I), alpha 1(III) and beta-actin mRNA levels were not increased in untreated diabetic rats 7 or 28 days after diabetes induction. Thus, tubular procollagen alpha 1(IV) mRNA levels increased prior to any measurable change in glomerular levels and were ameliorated by insulin administration.

Animals↗