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Biomedical subjects

B Rihn

Publications and source records attributed to B Rihn.

At least 19 recordsLinked to original sources
PubMed2002

Development and validation of a new bitumen fume generation system which generates polycyclic aromatic hydrocarbon concentrations proportional to fume concentrations.

Bitumen fumes emitted during road paving and roofing contain polycyclic aromatic compounds (PACs) of potential health concern. Little information is available for an experimental device devoted to inhalation experiments with animals exposed to bitumen fumes, and in all studies the systems were never validated for a range of fume concentrations, which prohibited their use for toxicological concentration-effect studies. Therefore, the purpose of this study was to validate a new experimental device able to generate bitumen fumes at different total particulate matter (TPM) concentrations with a linear correlation between TPM and the concentrations of different PACs, thus allowing toxicological dose-response studies with fumes representative of those in the field. Atmosphere samples collected from an animal exposure chamber allowed the determination of TPM, toluene soluble matter, polycyclic aromatic hydrocarbons (PAHs) and semi-volatiles. The particulate size distributions were determined in order to assess the deposition pattern in the respiratory tract. The temperature of 170 degrees C was chosen by analogy with the upper range of the temperature used during paving operations. The temperature of the air passing over the fume emission area was regulated to 20 degrees C and stirring of the heated bitumen was restricted to 90 r.p.m. The data show that the objective of developing a static fume generation system that reproducibly produces fumes in the inhalation chamber for specified target concentrations (TPM) were successful. The within-day variation coefficients for TPM were between 2.5 and 6.1%. The day-to-day variations for TPM concentration were between 4.1 and 5.8%. The concentrations of the 4-5 ring PAHs and the polycyclic aromatic sulphur heterocycles were proportional to the TPM concentration. The 2 and 3 ring PAH concentrations showed a deviation from proportionality with the TPM, probably due to their re-evaporation during sampling. The mass median aerodynamic diameter of airborne particles varied from 1.4 micro m at a fume concentration of 5 mg/m(3) to 3.2 micro m at 100 mg/m(3). In conclusion, this equipment was suitable for nose-only inhalation studies in the 5-100 mg/m(3) range of TPM. Bitumen fumes were generated with a good reproducibility under well-controlled conditions. Finally, the PAH profiles from atmospheric samples were in good agreement with those measured during road paving.

Hydrocarbons↗
PubMed2001

From ancient remedies to modern therapeutics: pine bark uses in skin disorders revisited.

The effect of French maritime pine bark extract (PBE) on the gene expression profile of HaCaT human keratinocytes was studied using high density filter arrays. The expression profile of both control and PBE-treated cells was determined. Interestingly, PBE was shown to downregulate both calgranulin A and B genes which are known to be upregulated in psoriasis and various dermatoses. Thus, PBE could be considered in human dermatoses.

Cell Line↗
PubMed2001

[Gene expression profiling in human mesothelioma cells using DNA microarray and high-density filter array technologies].

Although the use of asbestos has been banned in most industrialized countries, it is still a major public health concern. Asbestos fibers are mutagenic and carcinogenic for humans, classified as "carcinogen category 1 (T, R45: can cause the cancer)" in the 25th adaptation of the directive 67/548/EEC. In France, asbestos is thought to be responsible each year for many pulmonary diseases: pleural plaque, bronchogenic carcinoma and mesothelioma (malignant tumor of pleura). In order to better understand the transformation process of pleural cells, we compared the gene expression of mesothelium cells (Met-5A) and mesothelioma cells (MSTO-211H) using high-density filter array (588 genes) and microarray (6.969 genes). Results of both technologies were compared and expression levels of several genes were confirmed by quantitative RT-PCR. Data analysis with GemtoolsTM 2.4 software allows us hierarchical classification of genes of known functions by enzyme, function and pathway clusters and leads to characterize both malignant and normal phenotypes. Finally, the comparison between the two cell lines provides new markers of mesothelioma and pleura. They could be useful for diagnostic, prognostic and therapeutic.

Cell Adhesion↗
PubMed2000

A convenient semi-quantitative method for the diagnosis of Epstein-Barr virus reactivation.

A semi-quantitative determination of Epstein-Barr virus (EBV) viremia has been devised. Peripheral blood mononuclear cells are recovered by Ficoll gradient and numerated. Five microl aliquots of recovered cell suspension and 5 microl of two standard dilutions (containing 500 and 100 cells, respectively) are subjected to a nested polymerase chain reaction (PCR). This technique has been evaluated over 3 years for the follow-up of 45 patients attending the Bone Marrow Transplantation Unit of the "Centre Hospitalier et Universitaire de Nancy". EBV reactivation was diagnosed in 13 patients (28%). Positivity of PCR for 100 cells was found in 9 patients of whom 6 developed lymphoma or lymphoproliferative disorder. This technique is easy to perform and doesn't necessitate any specific material besides the one necessary for routine genic amplification.

Adolescent↗
PubMed2000

Evaluation of a supplemental assay for the diagnosis of hepatitis C virus infections.

OBJECTIVES: A supplemental test was evaluated for hepatitis C virus (HCV). METHODS: One hundred forty-six sera that were inconclusive or discrepant in two screening tests for HCV infection were evaluated using a supplemental test, MATRIX-HCV2 (Abbott Laboratories, Chicago, IL, USA). Results of the supplemental test were compared to the detection of HCV RNA by a nested polymerase chain reaction after a step of reverse transcription (RT-PCR). RESULTS: Thirty-nine RNA-containing sera (positive with RT-PCR) of 40 (97%) reacted with at least one antigen in the supplemental test. Reactivity with one to three antigens also was observed with 77 PCR-negative sera (66%). Twenty-nine sera were found negative with both techniques. CONCLUSIONS: Despite clear results and good sensitivity, the MATRIX-HCV2 assay was poorly predictive of viremia in patients with indeterminate results in initial screening assays.

Evaluation Studies as Topic↗
PubMed2000

Inhaled crocidolite mutagenicity in lung DNA.

We used transgenic mice carrying the lacI reporter gene to study the mutagenesis potential of asbestos crocidolite. The animals were exposed by nose-only inhalation to an aerosol containing 5.75 mg/m(3) crocidolite dust for 6 hr/day and 5 consecutive days. After 1, 4, and 12 weeks, we examined four end points: the cytology of bronchoalveolar lavage, the lung load of crocidolite, the hydrophobic DNA adducts, and the mutations in the lacI reporter gene. Twelve weeks after exposure, nearly 10% of the inhaled fibers remained in the lung (227 +/- 103 ng/mg lung). There was evidence of a typical inflammatory response consisting of multinucleate macrophages at weeks 4 and 12, whereas immediately after the exposure, we observed numerous polymorphonuclear neutrophils. The mutant frequency significatively increased during the fourth week after the exposure: 13.5 [time] 10(-5) in the exposed group versus 6. 9 10(-5) in the control group. The induction factor, defined by the ratio of checked mutants of exposed mice to checked mutants of control mice, was 1.96. The mutation spectrum of control lung DNA and exposed lung DNA was similar, suggesting the possible involvement of a DNA repair decrease in crocidolite-treated animals. We used the (32)P-postlabeling method and did not detect any increase of either 5 mC or bulky adduct in treated mice. This is the first study that demonstrates asbestos mutagenicity in vivo after a nose-only inhalation.

Air Pollutants↗
PubMed1999

Detection by immunohistochemistry of c-erbB2 oncoprotein in breast carcinomas and benign mammary lesions.

The presence of the c-erbB2 oncoprotein was demonstrated by immunohistochemistry in a study involving 173 mammary lesions. The lesions included infiltrating cancers, non-invasive neoplasia, as well as atypical and benign lesions. Our aim was to investigate the correlation between the c-erbB2 oncoprotein overexpression and the morphological features of the different mammary tissues analyzed to obtain a better characterization for the growth potential of certain lesions, with emphasis placed on the non-invasive neoplasia and the atypical lesions. Nearly 30% of infiltrating ductal carcinomas (27/89 cases) and 2 out of 24 infiltrating lobular carcinomas were positive. The comedocarcinomas were mostly stained (83%). In contrast, the intraductal carcinomas of cribriform or papillar patterns were consistently negative. No staining was observed in the atypical epithelial hyperplasia located in the vicinity of positive cancers for anti-oncoprotein c-erbB2 antibody. Furthermore, the only 5 positive cases for c-erbB2 out of 32 cancer-free cases were three fibroadenomas and two fibrocystic diseases with atypical ductal hyperplasia. A close correlation was thus observed between c-erbB2 oncoprotein overexpression and cancerous cell morphology, characterized by a marked nuclear hypertrophy often associated with cellular pleomorphism. However, predictive abnormalities of malignant transformation in non-neoplastic epithelial proliferation was difficult to identify, considering only the c-erbB2 expression. A group of tumors with little nuclear abnormalities were found positive for c-erbB2 immunostaining. These probably corresponded to a particular cellular phenotype. Further studies involving other oncogenes should lead to a better characterization of the different tumor phenotypes and help to clarify breast carcinogenesis.

Breast Neoplasms↗
PubMed1998

Selective inhibition of NF-kappaB activation by the flavonoid hepatoprotector silymarin in HepG2. Evidence for different activating pathways.

The bioflavonoid silymarin is found to potently suppress both nuclear factor kappa-B (NF-kappaB)-DNA binding activity and its dependent gene expression induced by okadaic acid in the hepatoma cell line HepG2. Surprisingly, tumor necrosis factor-alpha-induced NF-kappaB activation was not affected by silymarin, thus demonstrating a pathway-dependent inhibition by silymarin. Many genes encoding the proteins of the hepatic acute phase response are under the control of the transcription factor NF-kappaB, a key regulator in the inflammatory and immune reactions. Thus, the inhibitory effect of silymarin on NF-kappaB activation could be involved in its hepatoprotective property.

DNA↗
PubMed1998

Genital mycoplasmas in patients with acquired immunodeficiency syndrome.

To determine whether Mycoplasma fermentans. Mycoplasma genitalium and Mycoplasma penetrans were present in the genitourinary tract of HIV infected patients in Nancy, France, we have used culture and polymerase chain reactions on urine from 54 HIV-infected patients. Both techniques failed to reveal these bacteria. This renders their presence very unlikely in our population.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Identification of human complement factor H as a chemotactic protein for monocytes.

We used chromatographic separation to purify to homogeneity a monomeric monocyte chemotactic protein of 150 kDa contained in mesothelioma pleural effusions. It was identified by N-terminal amino acid sequencing and immunoblotting as complement factor H, an inhibitor of the alternative complement pathway. Specific antibodies against factor H inhibited the monocyte chemotactic activity of the purified protein, which was most active at 10 nM. Factor H is a restrictive factor of alternative complement pathway activation. The new chemotactic function assigned to factor H in recruiting monocytes to the mesothelioma site might contribute to malignant cell phagocytosis via the iC3b/complement receptor type 3 pathway. These functions link the humoral and cellular immune systems.

Amino Acid Sequence↗
PubMed1996

Short-term crocidolite inhalation studies in mice: validation of an inhalation chamber.

A nose-only inhalation chamber is described: this chamber being computer automated has been particularly designed for mice on which it was validated using a crocidolite aerosol at a nominal concentration of 13.6 mg/m3, 6 h/day during 5 days. A month later the mice showed typical inflammatory bronchoalveolar liquids with many polynucleated or activated macrophages and asbestos bodies. The burden of crocidolite fibers ranged from 345,000 to 1,300,000 fibers per mg of dried lung. This study demonstrates that during the month that followed a short-term mice exposure to crocidolite fibers, the inflammatory response was still persistent. These toxicological endpoints validate the nose-only inhalation chamber to be useful for common or transgenic mice.

Administration, Inhalation↗
PubMed1995

Evaluation of non-radioactive labelling and detection of deoxyribonucleic acids. Part One: Chemiluminescent methods.

The growth of analytical methods for the detection of nucleic acid from various biological samples reflects recent advances in biotechnology development especially in the areas of genetic, infections and cancer diagnosis. The target DNA is detected by hybridization techniques derived from Southern's blotting. However such assays, based on the use of 32P labelled DNA probes, bring with them the associated problems of handling radioactive materials. In order to overcome these difficulties, a number of chemiluminescent detection methods have recently been developed. These new, alternative probe labelling procedures and chemiluminescent detection methods are easy to use in routine assays performed in research laboratories as well as for medical applications, and can reach the level of sensitivity found in classical radiolabelling techniques. The techniques investigated include peroxydase, biotin 16-dUTP or digoxigenin 11-dUTP probe labelling. The target DNAs are transferred onto nitrocellulose or nylon membranes and further fixed by heat or UV crosslinking. Specific hybridization on the target DNA is finally revealed by the use of chemiluminescent substrates. For all these techniques the detection limit is 10 aM (attomol) of a 561 bp target DNA. However for the probes labelled with peroxydase and with digoxigenin the detection limit drops to 1.0 aM of the target DNA. In the present paper we shall compare several of these DNA labelling and detection procedures and show that the detection threshold can vary by as much as a factor of 20 from method to method. This is the first time that various chemiluminescent methods for label and detection of DNA are compared and evaluated in order to determine the best protocol.

Adamantane↗
PubMed1995

Evaluation of non-radioactive labelling and detection of deoxyribonucleic acids. Part Two: Colorigenic methods and comparison with chemiluminescent methods.

The diagnosis of genetic infections and cancerous diseases is carried out more and more often at a molecular level using Southern's technique which is based on the use of 32P-labelled DNA. In order to circumvent the risks and rapid decrease in radioactivity associated with these latter techniques, new colorigenic methods have been developed. In this work, we describe the use of dTTP analogues (digoxigenin-dUTP and biotin-dUTP) for the labelling of probes and detection of target DNA. Using digoxigenin-11-dUTP, 0.1 aM of a 561 bp target DNA was detected by using a modified Southern procedure. The reliability and the high sensitivity of such methods make them a good tool for DNA investigation in research as well as in testing laboratories.

Adenocarcinoma↗
PubMed1995

[Expression of the c-erbB-2 oncoprotein in mammary Paget's disease. Immunohistochemical study by using 3 antibodies].

An overexpression of the c-erbB-2 oncoprotein has been demonstrated in the breast cancer and has been associated with a poor prognosis. Our study involved 23 cases of mammary Paget's disease which was found to be associated with the intraductal carcinomas in 13 cases, the intraductal carcinomas supposed micro-invasive in 2 cases, the infiltrating ductal carcinomas with predominant intraductal component in 6 cases and the infiltrating ductal carcinomas in 2 cases. The presence of c-erbB-2 oncoprotein has been determined immunohistochemically with 3 different antibodies: rabbit anti-human c-erbB-2 oncoprotein A485 (Dako), c-erbB-2 oncoprotein (internal domain) mouse monoclonal antibody NCL-CB11 (Novocastra), and c-erbB-2 oncoprotein (external domain) mouse monoclonal antibody NCL-CBE1 (Novocastra). An overexpression of the c-erbB-2 oncoprotein has been observed in 21 of the 23 studied cases. We noted an intense membrane staining in the intraepidermal or intraglandular tumour cells of mammary Paget's disease. Any staining has been observed in 2 cases with glandular component of pure intraductal type. These results are identical whatever the antibody used. In a previous study concerning mammary Paget's disease, it has been noted a correlation between this overexpression and presence of large malignant cells. We also have found this notion in mammary Paget's disease where the c-erbB-2 positive neoplastic cells in the different tumour components were large with prominent cytoplasm. The obtained results argue strongly for adenocarcinomatous origin for mammary Paget's disease and exhibit that the overexpression of c-erbB-2 oncoprotein was not constantly in correlation with a poor prognosis.

Antibodies, Monoclonal↗
PubMed1995

Use of non-radioactive methods for the determination of the expression, the sequence and the copy-number of transgene in mice.

Marshall's observation that "toxicology goes molecular", is turning out to be more true than ever; namely as it is observed that toxicological endpoints are the point of interaction between proteins and genes following the administration of toxicants. Transgenic mice represent a valuable tool for studying the adverse effects of chemicals in genetically engineered animals such as p53 deficient mice, or mice carrying the v-Ha-ras oncogene. The latter were used in our laboratory for such toxicological assessments of chemicals. In order to verify that the transgene was expressed in normal, as well as in tumor cells, the transgene was detected in different tissues fixed with various solutions using in situ hybridization. It was also specifically retrotranscribed from paraffin-embedded tissues and consequently sequenced using a Taq polymerase reaction. We found that the transgene was expressed in various organs. It carries a specific mutation of codon 12 leading to the activation of its encoded product (transducin: p21v-Ha-ras). Moreover using a laser scanning densitometer, it has been demonstrated that 2 to 3 copies of the transgene were present per genome-equivalent in some tissues. All experiments were realized using non-radioactive labelling and detection (chemiluminescent or colorigenic) methods. Indeed, the screening of such animals was realized in a easier and a safer manner using the methods described in this paper than the usual methods based on the use of radiolabelled precursors.

Animals↗
PubMed1995

Determination of amplification level of the c-erbB-2 proto-oncogene in human breast carcinomas: a comparative study between non-radioactive and radioactive labelling.

A quantitative method of polymerase chain reaction (PCR) using both digoxigenin and radioactive labelled probes has been used for the detection of the c-erbB-2 proto-oncogene amplification in breast carcinomas with formalin-fixed paraffin-embedded tissue sections. c-erbB-2 proto-oncogene amplification has been demonstrated in 14 infiltrating ductal carcinomas. The technique consisted of the co-amplification of c-erbB-2 and IFN-gamma (interferon-gamma) genes. The latter was considered as a single copy gene per genome-equivalent. The aim of this study was to compare two quantitative PCR techniques based on the incorporation of either digoxigenin-11-dUTP or 32P-dCTP, during amplification. For the colorigenic method, using the Dig system, after electrophoresis and transfer, the specific bands were revealed with a chromogenic substrate of phosphatase. Their intensity estimated by scanning photometry following blot transparisation. After electrophoresis, the radioactive gel was submitted to radioautography and the band intensities evaluated by scanning spectrophotometry. For the 14 samples, a good agreement between both methods was noted. The colorigenic method is a valuable alternative to radiolabelling due to: i) time saving, ii) reagent conservation, iii) safe manipulation and iv) sensitivity of the same order for both methods.

Base Sequence↗
PubMed1992

Comparative study of immunological properties and cytotoxic effects of Clostridium difficile toxin B and Clostridium sordellii toxin L.

We compared the immunological properties and cytotoxic effects of Clostridium difficile toxin B and Clostridium sordellii toxin L. These two cytotoxins are immunologically related in that the cytotoxic effect of either toxin can be neutralized by the polyclonal antiserum prepared against either cytotoxin. On the other hand, polyclonal antiserum prepared against Clostridium difficile enterotoxin A did not cross-react with the cytotoxins B and L when tested by cytotoxic neutralization test nor by double immunodiffusion assay. However, despite this immunological relationship between toxins B and L, the morphological modifications observed in MacCoy cells induced by treatment with these cytotoxins are clearly distinct. We describe the first quantitative analysis of specific cellular parameters which illustrates the morphological differences induced by these cytotoxins. Moreover, immunocytochemical experiments show that, whereas disruption of microfilaments is observed with toxin B- and L-treatments, alterations of F-actin network are different in the cells treated with toxin B or L. The observation that the cellular modifications induced by toxin B- and toxin L-treatment differ suggests that the molecular mechanisms involved in the respective cytotoxicities are also likely to be different.

Actin Cytoskeleton↗