Two-wavelength holographic interferometry for the measurement of large deformations

in SPIE's International Technical Working Group Newsletter : Holography (1995), 5(2), 5

La robotique pédagogique en Belgique : quelques éléments de bilan, 'Acquisition de l'autonomie dans ses apprentissages par une pédagogie de projet : le cas de la technologie'

Conference (1995, July)

Substituent effect in anionic polymerization of β-lactones initiated by alkali metal alkoxides

in Macromolecular Rapid Communications (1995), 16(7), 513-519

The influence of methyl substituent on the mechanism of the ring-opening polymerization of -lactones initiated by alkali metal alkoxides is discussed. Attention has been paid to the effect of the ... [more ▼]

The influence of methyl substituent on the mechanism of the ring-opening polymerization of -lactones initiated by alkali metal alkoxides is discussed. Attention has been paid to the effect of the substituent position in the monomer molecule on the ring-opening mechanism, the 3,3-dimethyl-2-oxetanone (pivalolactone), 4-methyl-2-oxetanone (beta-butyrolactone) and 2-oxetanone (beta-propiolactone) being chosen as model monomers. Moreover, it was found unexpectedly that in the case of pivalolactone polymerization, besides open-chain polymers, cyclic oligomers are produced. [less ▲]

Diaspirin Crosslinked Hemoglobin (Dclhb): Absence of Increased Free Radical Generation Following Administration in a Rabbit Model of Renal Ischemia and Reperfusion

in Free Radical Biology & Medicine (1995), 19(1), 1-9

In control rabbits, a renal ischemia of 60 min followed by 10 min of reperfusion resulted in an enhanced free radical production in cortical tissue, as assessed by a significant decrease of free ... [more ▼]

In control rabbits, a renal ischemia of 60 min followed by 10 min of reperfusion resulted in an enhanced free radical production in cortical tissue, as assessed by a significant decrease of free glutathione (42%), protein-bound GSH (17%), and vitamin E (49%). In contrast, catalase or glutathione peroxidase activities were not affected by these experimental conditions. Free radical production in this model was also measured directly using electron spin resonance (ESR) spectroscopy associated with a PBN (alpha-phenyl N-tert-butyl-nitrone) spin trap agent in the venous blood arising from the ischemic kidney. The signal consisted of a triplet of doublets. In contrast, no signal could be detected in control blood samples taken prior to inducing ischemia. The burst of free radical production occurred in the early phase after restoration of flow in the kidneys rendered ischemic, as evidenced by a signal of weak intensity which generally appeared within the third minute after reperfusion and progressively increased to form a well-defined asymmetric signal following 10 min of reperfusion. The precise nature of free radicals trapped by the PBN agent remains, however, to be elucidated, but analysis of the coupling constants (aN = 14.5-15 G; a beta H = 2.5-3 G) and asymmetry of the central doublets suggests that the ESR signal may arise from a nitorxy-radical adduct resulting from the spin trapping by PBN of both oxygen- or carbon-centered radicals of lipid origin. As evidenced by both direct and indirect measurements, exchange of rabbit blood immediately after inducing renal ischemia with 30 ml/kg of Diaspirin Crosslinked Hemoglobin (7.5 g/dl in lactated electrolyte) or human serum albumin (7.5 g/dl in lactated electrolyte) did not exacerbate free radical production mediated by an ischemia reperfusion phenomenon, a typical situation found in a resuscitation setting. [less ▲]

Fractionation and partial characterization of proteins extracted from the bovine fallopian tube: preparation of tools for further purifications

in Theriogenology (1995), 44(1), 95-107

Described in the present paper is a combined biochemical and immunological approach to study oviductal proteins in the bovine. Antisera were raised against semi-purified proteins extracted from bovine ... [more ▼]

Described in the present paper is a combined biochemical and immunological approach to study oviductal proteins in the bovine. Antisera were raised against semi-purified proteins extracted from bovine tubal mucosal tissue and were characterized. These antisera are available to monitor puritications of specific oviductal proteins in the future. Oviducts from 170 cyclic cows were collected at a slaughterhouse, and high amounts of mucosal proteins were extracted. The proteins were fractionated after precipitation with ammonium sulfate, anti-bovine serum albumin (bSA) and anti-bovine immunoglobulins bIg) afiinity chromatography and ion exchange chromatography. Each of the 12 fractions obtained after ion exchange chromatography was used to immunize a rabbit. Conditioned media were recovered from bovine oviduct cell monolayers cultured without serum to cot&m the oviductal origin of the extracted proteins. After Western blot analysis, 15 proteins were detected in the bovine oviductal extracts, and their molecular weights and isoelectric points were determined by 2 dimensional electrophoresis. Among these 15 proteins, 11 were also detected in conditioned media of bovine oviductal cells. These results demonstrate an oviductal origin of the 11 detected proteins and strongly suggest their secretion by the oviductal cells. [less ▲]

Analysis of Bovine Herpesvirus 4 Genomic Regions Located Outside the Conserved Gammaherpesvirus Gene Blocks

in Journal of General Virology (The) (1995), 76((Pt 7)), 1835-41

Bovine herpesvirus 4 (BHV-4) DNA sequences located outside the gene blocks conserved among the gammaherpesviruses BHV-4, herpesvirus saimiri (HVS) and Epstein-Barr virus (EBV) were analysed. Twelve ... [more ▼]

Bovine herpesvirus 4 (BHV-4) DNA sequences located outside the gene blocks conserved among the gammaherpesviruses BHV-4, herpesvirus saimiri (HVS) and Epstein-Barr virus (EBV) were analysed. Twelve potential open reading frames (ORFs) were found. Protein database comparisons showed that no ORF translation products were similar to proteins encoded by alpha- or betaherpesviruses. Nevertheless, six of the ORFs were homologous in amino acid sequences to proteins encoded by HVS but apparently not to those encoded by EBV. Furthermore, the location and orientation of these six ORFs in the BHV-4 genome were similar to the corresponding ORFs in the HVS genome. No genes homologous to known cellular genes were found in the BHV-4 genome; this feature is the major difference between the BHV-4 and HVS genomes with regards to the overall gene content. [less ▲]

"L'unité et la diversité de la francophonie dans l'enseignement du français aux étrangers"

Conference (1995, July)

Nuclear Lesions During Rat Hepatocarcinogenesis. II. Measuring the Micronuclei During Initiation, Promotion and Progression of Rat Hepatocarcinogenesis Induced with Diethylnitrosamine

in Mutation Research : Fundamental & Molecular Mechanisms of Mutagenesis (1995), 329(2), 161-71

We reported in our companion paper the strong correlation between elevated sister-chromatid exchange (SCE) frequencies and the initiation step of rat hepatocarcinogenesis. We have also shown that SCEs ... [more ▼]

We reported in our companion paper the strong correlation between elevated sister-chromatid exchange (SCE) frequencies and the initiation step of rat hepatocarcinogenesis. We have also shown that SCEs return to normal values during the promotion and the progression stages. In the present study, we evaluated the clastogenic activity of diethylnitrosamine (DEN) during initiation, promotion and progression of rat hepatocarcinogenesis. We measured, at various times after DEN administration, the number of micronuclei (MN) produced by the mitotic response to partial hepatectomy. The results established that the DEN treatment induces a great number of preclastogenic lesions. In subcarcinogenic conditions (initiation alone), the number of MN expressed after partial hepatectomy remains high regardless of the time interval between the end of the DEN treatment and the operation. In this condition, the preclastogenic lesions persist for up to 1 year after the DEN administration is discontinued. Conversely, in carcinogenic conditions (initiation + promotion + progression), the number of MN expressed after partial hepatectomy decreases during the promotion and progression stages. These observations indicate that promotion and progression but not initiation are associated with the expression of persistent preclastogenic lesions, resulting in the production of chromosomally abnormal hepatocytes. [less ▲]

Nuclear Lesions During Rat Hepatocarcinogenesis. I. Measuring the Sister-Chromatid Exchanges During Initiation, Promotion and Progression of Rat Hepatocarcinogenesis Induced with Diethylnitrosamine

in Mutation Research : Fundamental & Molecular Mechanisms of Mutagenesis (1995), 329(2), 153-9

Cytogenetic endpoints such as sister-chromatid exchanges (SCEs), chromosomal aberrations and micronuclei (MNs) have been widely used as indicators of genetic damage. However, no systematic attempts have ... [more ▼]

Cytogenetic endpoints such as sister-chromatid exchanges (SCEs), chromosomal aberrations and micronuclei (MNs) have been widely used as indicators of genetic damage. However, no systematic attempts have been made to correlate the levels of these cytogenetic endpoints with the different steps of carcinogenesis. In the present report, the induction, accumulation and persistence of SCEs and high frequency cells (HFCs) were measured in liver cells during the initiation, promotion and progression steps of rat hepatocarcinogenesis induced by diethylnitrosamine (DEN). The results indicate that lesions leading to SCEs accumulate during initiation only. When DEN administration is longer than the duration of this first step, SCE values stabilize. After stopping the carcinogenic treatment, the SCE levels decrease to control values whether or not promotion and progression occur. [less ▲]

Control of living anionic polymerization of (meth)acrylates : active complex species, macromolecular engineering and possible scaling-up

in Macromolecular Symposia (1995), 98

Tailored polymerization of acrylic and methacrylic esters, particularly methyl methacrylate (MMA), has been the topic of a frantic research effort during the last decade. It is the purpose of this paper ... [more ▼]

Tailored polymerization of acrylic and methacrylic esters, particularly methyl methacrylate (MMA), has been the topic of a frantic research effort during the last decade. It is the purpose of this paper to present one of the main lines of that quest, and to evaluate its potential versus other new approaches. [less ▲]