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Biomedical subjects

R Perrin

Publications and source records attributed to R Perrin.

At least 19 recordsLinked to original sources
PubMed2005

Treatment and valorisation of winery wastewater by a new biophysical process (ECCF).

Taking account of the high specificity of the organic load of winery effluents, a new biophysical treatment using the stripping of ethanol combined with a final concentration by evaporation has been studied. Two options are proposed: full treatment and pre-treatment. The study of the composition of winery wastewater has shown the large, dominant part of ethanol in the organic load (75 to 99% of the COD). According to a linear correlation between COD and ethanol concentration, the determination of ethanol concentration can be used to estimate the organic load of winery wastewater. Full treatment by stripping and concentration at a pilot plant allows the separation of the wastewater into highly purified water (COD elimination > 99%), a concentrated alcoholic solution usable as bio-fuel and a concentrated by-product. Stripping alone represents an advantageous pre-treatment of winery wastewater. The purification rate reaches 78 to 85% and ethanol is recovered. The process facilitates discharge into a sewage system in view of treatment with domestic effluents and can also improve the efficiency of overloaded or old purification plants. The economical approach of this method demonstrates its competitiveness in comparison with biological treatments: low energy consumed, no sludge.

Biodegradation, Environmental↗
PubMed2001

Plant mitochondrial polyadenylated mRNAs are degraded by a 3'- to 5'-exoribonuclease activity, which proceeds unimpeded by stable secondary structures.

Recently, we and others have reported that mRNAs may be polyadenylated in plant mitochondria, and that polyadenylation accelerates the degradation rate of mRNAs. To further characterize the molecular mechanisms involved in plant mitochondrial mRNA degradation, we have analyzed the polyadenylation and degradation processes of potato atp9 mRNAs. The overall majority of polyadenylation sites of potato atp9 mRNAs is located at or in the vicinity of their mature 3'-extremities. We show that a 3'- to 5'-exoribonuclease activity is responsible for the preferential degradation of polyadenylated mRNAs as compared with non-polyadenylated mRNAs, and that 20-30 adenosine residues constitute the optimal poly(A) tail size for inducing degradation of RNA substrates in vitro. The addition of as few as seven non-adenosine nucleotides 3' to the poly(A) tail is sufficient to almost completely inhibit the in vitro degradation of the RNA substrate. Interestingly, the exoribonuclease activity proceeds unimpeded by stable secondary structures present in RNA substrates. From these results, we propose that in plant mitochondria, poly(A) tails added at the 3' ends of mRNAs promote an efficient 3'- to 5'- degradation process.

Base Sequence↗
PubMed2001

Golgi enzymes that synthesize plant cell wall polysaccharides: finding and evaluating candidates in the genomic era.

Although the synthesis of cell wall polysaccharides is a critical process during plant cell growth and differentiation, many of the wall biosynthetic genes have not yet been identified. This review focuses on the synthesis of noncellulosic matrix polysaccharides formed in the Golgi apparatus. Our consideration is limited to two types of plant cell wall biosynthetic enzymes: glycan synthases and glycosyltransferases. Classical means of identifying these enzymes and the genes that encode them rely on biochemical purification of enzyme activity to obtain amino acid sequence data that is then used to identify the corresponding gene. This type of approach is difficult, especially when acceptor substrates for activity assays are unavailable, as is the case for many enzymes. However, bioinformatics and functional genomics provide powerful alternative means of identifying and evaluating candidate genes. Database searches using various strategies and expression profiling can identify candidate genes. The involvement of these genes in wall biosynthesis can be evaluated using genetic, reverse genetic, biochemical, and heterologous expression methods. Recent advances using these methods are considered in this review.

Amino Acid Sequence↗
PubMed2000

Combined minimaly invasive surgery for coronary bypass and abdominal aortic occlusion.

Association of extracorporal assisted coronary bypass with peripheral vascular surgery is already commonplace in the therapeutic arsenal. This case report presents a combined cardiac and vascular surgery in a high risk patient, with unstable angina following myocardial infarction and critical ischemia of a single lower limb. Synchronous minimally invasive direct coronary bypass graft and extra-anatomic aorto-profundal bypass in one single sitting were performed. The procedure was successful at 6 months follow up. We believe that this type of synchronous procedure, minimising surgical aggression, could be effective in selected high risk patients.

Aged↗
PubMed1998

Augmentation of lung liquid clearance via adenovirus-mediated transfer of a Na,K-ATPase beta1 subunit gene.

Previous studies have suggested that alveolar Na,K-ATPases play an important role in active Na+ transport and lung edema clearance. We reasoned that overexpression of Na,K-ATPase subunit genes could increase Na,K-ATPase function in lung epithelial cells and edema clearance in rat lungs. To test this hypothesis we produced replication deficient human type 5 adenoviruses containing cDNAs for the rat alpha1 and beta1 Na,K-ATPase subunits (adMRCMValpha1 and adMRCMVbeta1, respectively). As compared to controls, adMRCMVbeta1 increased beta1 subunit expression and Na,K-ATPase function by 2. 5-fold in alveolar type 2 epithelial cells and rat airway epithelial cell monolayers. No change in Na,K-ATPase function was noted after infection with adMRCMValpha1. Rat lungs infected with adMRCMVbeta1, but not adMRCMValpha1, had increased beta1 protein levels and lung liquid clearance 7 d after tracheal instillation. Alveolar epithelial permeability to Na+ and mannitol was mildly increased in animals infected with adMRCMVbeta1 and a similar Escherichia coli lacZ-expressing virus. Our data shows, for the first time, that transfer of the beta1 Na,K-ATPase subunit gene augments Na,K-ATPase function in epithelial cells and liquid clearance in rat lungs. Conceivably, overexpression of Na,K-ATPases could be used as a strategy to augment lung liquid clearance in patients with pulmonary edema.

Adenoviruses, Human↗
PubMed1998

Resistance of Pseudomonas aeruginosa PAO1 phage F116 to sodium hypochlorite.

The development of viral resistance to sodium hypochlorite was investigated using the Pseudomonas aeruginosa bacteriophage F116 as a model system. This phage was chosen because of its structural characteristics and former investigations conducted in this laboratory. F116 was shown to be sensitive to a sodium hypochlorite concentration of 0.0075 gl-1 (available chlorine) which produced a 5 log10 reduction in titre in a suspension test. Survival bacteriophages challenged with this sodium hypochlorite concentration were isolated, propagated and challenged again with the same and higher concentrations of the biocide. It was observed that progeny virions were becoming increasingly resistant to sodium hypochlorite challenges up to a concentration of 0.0175 gl-1 of available chlorine. It was also noticed that 1-2 log10 of F116 virions from resistant phage lysates remained sensitive to the biocide. An electron microscopical investigation of F116 resistant lysates showed that the phage resistance to sodium hypochlorite was not caused by F116 particles aggregation. Furthermore, no morphological difference between the sensitive and resistant F116 particles to sodium hypochlorite was identified.

Adaptation, Biological↗
PubMed1998

Efficacy and mechanisms of action of sodium hypochlorite on Pseudomonas aeruginosa PAO1 phage F116.

The Pseudomonas aeruginosa PAO1 phage F116 was used to investigate the viricidal activity and the mechanism of action of sodium hypochlorite. The bacteriophage was inactivated with a low concentration (0.0005% available chlorine) of the biocide prepared in tap water but it was less sensitive to a sodium hypochlorite solution prepared in ultra-pure water (0.0075% available chlorine). For all the effective concentrations of sodium hypochlorite (i.e. producing at least 4 log reduction in phage titre), F116 was readily inactivated within 30 s. Electron microscopical investigations of the phage particles challenged with sodium hypochlorite showed a wide variety of deleterious effects, some of which have not been previously observed with other biocides. The wide range of structural alterations observed suggested that sodium hypochlorite has multiple target sites against F116 bacteriophage. A 30 s exposure to sodium hypochlorite (0.001% available chlorine) produced severe damage, the number and severity of which increased with a higher concentration (0.0075% available chlorine) and with a longer contact time. These observations suggested that sodium hypochlorite inactivated F116 bacteriophage by causing structural alterations to the phage head, tail and overall structure, hence possibly releasing the viral genome from damaged capsids in the surrounding media.

Antiviral Agents↗
PubMed1995

Modified anterior approach to the cervicothoracic junction.

STUDY DESIGN: This study reports the experience with four patients regarding a modified anterior approach to the cervicothoracic junction. OBJECTIVES: This technique was evaluated with respect to extent of exposure, ease of technique, and postoperative morbidity. SUMMARY OF BACKGROUND DATA: Previously reported anterior approaches to the cervicothoracic junction have described either full sternotomy resection of the left sternoclavicular junction or osteotomy of the clavicle. A simplified approach was chosen using a partial sternotomy, which has not been described previously for approaches to the spine. METHODS: Four patients with metastatic disease, in the region of the cervicothoracic junction, required decompression and stabilization for palliation of symptoms. An anterior approach was required for decompression. A standard cervical approach was combined with a partial median sternotomy and transverse osteotomy through the synostosis between the manubrium and body of the sternum. In three patients, the left innominate vein was divided. Decompression and anterior stabilization were followed by posterior stabilization at an interval of 4 to 7 days. RESULTS: This procedure was simple to perform, requiring little additional operative time for opening or closure. It provided excellent exposure from C3-T4. There was no associated morbidity related to the division of the manubrium or innominate vein. CONCLUSION: Partial sternotomy combined with a standard cervical incision provides excellent exposure to the cervicothoracic junction from C3-T4. It is technically simple to perform and avoids the risk of injury to subclavian vessels inherent in resection of the clavicle or sternoclavicular junction. There is no additional morbidity associated with this approach.

Cervical Vertebrae↗
PubMed1995

Phialophora corneal ulcer.

BACKGROUND: A corneal fungal ulcer which appeared to be quite superficial clinically, was found by histologic examination to unexpectedly involve the full thickness of the cornea. METHODS: A patient with an apparent superficial corneal fungal ulcer due to Phialophora species was resistant to topical and intravenous antifungal therapy. RESULTS: Penetrating keratoplasty cured the condition with retention of normal vision with a follow-up of two years. CONCLUSIONS: If keratomycosis is unresponsive to topical and intravenous antifungal therapy, penetrating keratoplasty may be required to eliminate the infection. Resistance to medical therapy might suggest presence of fungus far deeper in the cornea than suspected clinically.

Adult↗
PubMed1993

Subcellular localization of cytochrome P450, and activities of several enzymes responsible for drug metabolism in the human brain.

We studied the subcellular distribution of cytochrome P450 and related monooxygenase activities in six regions of human brains removed at autopsy. The content of total cytochrome P450 was found to be at least nine times higher in the mitochondrial fraction than in the microsomes in all the regions studied. However, cytochrome P450-dependent enzymatic activities which are representative of different isoforms metabolizing exogenous molecules exhibited a microsomal prevalence, a situation previously observed in rat brain. The other drug-metabolizing enzymes catalysing functionalization and conjugation reactions, presented the following characteristics in human brain: (i) a low activity of NADPH-cytochrome P450 reductase, which also catalyses the reduction of some xenobiotics; (ii) a high specific activity of the membrane-bound epoxide hydrolase; (iii) among the enzymes catalysing conjugation reactions, 1-naphthol-UDP-glucuronosyltransferase activity was barely or not detectable, whereas the mean glutathione-S-transferase activity was 15 times higher than the activity measured in rat brain. The presence of several drug-metabolizing enzyme activities in human brain microvessels, and particularly the high activity of epoxide hydrolase, suggests a participation of these enzymes in the metabolic blood-brain barrier.

Aged↗
PubMed1991

Fulminant blastomycosis with blastomycotic infection of a cerebral glioma. Light microscopic and ultrastructural observations.

Except for isolated case reports, blastomycosis has not been identified as a significant problem in immunosuppressed patients. We describe an unusual case with blastomycotic infection of a cerebral glioma in a 56-year-old man who underwent radiotherapy for his tumor and died of fulminant blastomycotic pneumonia. This is believed to be the first reported case of Blastomyces dermatitidis infection of a cerebral glioma. The light microscopic and ultrastructural features of B. dermatitidis, the giant forms of which were encountered in our patient, are described, and thr role of immunosuppression due to steroid therapy in the pathogenesis of this fulminant infection are reviewed.

Blastomyces↗
PubMed1991

Enzyme mediated superoxide radical formation initiated by exogenous molecules in rat brain preparations.

The ability of brain tissue preparation to generate superoxide from xenobiotic interactions has been investigated. We showed that a significant superoxide production occurred with different molecules known to undergo a single electron reductive pathway of metabolism, both in a homogenate derived from neuronal and glial cells and in isolated cerebral microvessels which form the blood-brain barrier. Determination of the nucleotide cofactors requirement and data obtained with different subcellular fractions indicated that this production was largely associated with the microsomal fraction in a NADPH-dependent pathway and was probably mediated by NADPH-cytochrome P450 (c) reductase. A significant xenobiotic-mediated production of superoxide also occurred in mitochondria under in vitro conditions. Thus the evidence of reductive pathways of xenobiotic metabolism and the generation of oxygenated free radicals observed are of neurotoxicological significance.

Animals↗
PubMed1991

Identification of novel phencyclidine metabolites formed in vitro by rabbit microsomal metabolism.

1. Phencyclidine (PCP) was incubated with rabbit liver and brain microsomal fractions, and the structures of metabolites formed by oxidation determined by g.l.c.-mass spectrometry. 2. The formation of several known mono- and di-hydroxylated metabolites, as well as two new metabolites, was seen in the liver preparations. 3. Hydroxylated PCP metabolites were also formed after incubation of PCP with brain microsomes, indicating that PCP biotransformation may occur in the brain itself.

Animals↗
PubMed1990

Distribution of cytochrome P450 activities towards alkoxyresorufin derivatives in rat brain regions, subcellular fractions and isolated cerebral microvessels.

The regional and subcellular distributions of rat brain cytochrome P450 and cytochrome P450-dependent activities were examined. Cytochrome P450 was found to be mainly localized in mitochondria in all the six cerebral regions studied. The activities of the isoforms mostly implicated in drug metabolism, cytochromes P450 b and c, were measured by the dealkylation of two alkoxyresorufins, that are sensitive probe substrates for these isoforms. These activities have been measured in microsomal and mitochondrial fractions obtained from six different regions in male rat brains, as well as in microvessels. Resorufin derivatives dealkylation specific activities were higher in brain microsomal fractions than in hepatic ones in all the six regions examined when results were expressed per cytochrome P450 content. These brain microsomal specific activities were also higher than in mitochondrial fractions. Olfactory bulbs showed the highest cytochrome P450 content and activities in both microsomal and mitochondrial fractions. A sex-linked difference in cytochrome P450-dependent activities was also found. After an in vivo inducing pretreatment of rats, only 3-methylcholanthrene induced ethoxyresorufin O-deethylase activity, in the three preparations studied. These results provided (i) direct evidence that cytochromes P450 b and c isoforms are active in brain microsomal fractions, with regional and sex-linked differences, and (ii) the first demonstration of cytochrome P450-dependent activities in isolated rat brain microvessels.

Animals↗
PubMed1990

Small-incision cataract surgery using the Perrin intraocular cataract scissors and forceps.

An original operative technique for performing extracapsular cataract extraction through a small incision is described. The technique is both inexpensive and simple to perform. Intraocular cataract scissors are used to bisect the nucleus of the cataractous lens, and each of the halves of the bisected nucleus is removed with intraocular cataract forceps. Both the scissors and the forceps have been specifically designed for this task. The incision size of 7.5 mm allows insertion of currently available intraocular lenses. During the procedure viscoelastic is used to protect intraocular structures, in particular the corneal endothelium and the posterior capsule.

Cataract Extraction↗