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Biomedical subjects

A Arnaud

Publications and source records attributed to A Arnaud.

At least 19 recordsLinked to original sources
PubMed2006

[Implementation of transabdominal ultrasound image guided conformal intensity modulated radiotherapy].

PURPOSE: Optically guided ultrasound imaging has been used in our department since 2003 in order to implement an on line correction scheme in intensity modulated radiation therapy of prostate carcinoma. PATIENTS AND METHODS: The corrections observed during the initial time period of the system (17 patients) are compared to those observed more recently (10 patients). Treatment margins are calculated. RESULTS: Overall systematic errors decreased between 2003 and 2006, and are presently statistically not different from zero. Random errors remain the same (max 4.3 mm). Proposed margins are 7 mm both in lateral and longitudinal direction and 8.4 mm in anteroposterior. CONCLUSION: Ultrasound can be used for on line correction of both positioning and internal organs motion errors and allows reduction of the margins between clinical and planning volume.

Abdomen↗
PubMed2004

Exogenous nucleosides modulate the expression of rat liver extracellular matrix genes in single cultures of primary hepatocytes and a liver stellate cell line and in their co-culture.

BACKGROUND & AIMS: We have previously reported the antifibrotic effect of dietary nucleotides in cirrhotic rats. In this work, we used primary rat hepatocytes, a liver stellate cell line (CFSC-2G) and co-cultures of both cell types to investigate the effects of exogenous nucleosides on the gene expression of various extracellular matrix components and on markers of liver function, and to ascertain whether the effects found in vivo are due to CFSC-2G, hepatocytes, or are the consequence of cell-cell interactions. RESULTS: Nucleosides enhanced fibronectin, laminin, and alpha1(I) procollagen levels in CFSC-2G and hepatocytes, as well as collagen synthesis and secretion in CFSC-2G. In contrast, nucleosides lowered fibronectin, laminin and alpha1(I) procollagen levels, and decreased collagen synthesis in co-cultures. Matrix metalloproteinase-13 content and collagen secretion increased in co-cultures incubated with nucleosides. Albumin increased in hepatocytes and co-cultures incubated in the presence of nucleosides. CONCLUSIONS: Nucleosides modulate the production of extracellular matrix in single cultures of hepatocytes and of CFSC-2G, and in co-cultures. This effect seems to be regulated at the translational level. The opposite behavior of single cultures and co-cultures is probably due to the fact that the latter model reproduces many of the physical and functional relationships observed in vivo between hepatocytes and stellate cells.

Animals↗
PubMed2003

Exogenous nucleosides alter the intracellular nucleotide pool in hepatic cell cultures. Implications in cell proliferation and function.

BACKGROUND & AIMS: Dietary nucleotides are reported to influence the growth and functioning of the liver. The objective of the study was to evaluate the uptake and incorporation of exogenous nucleosides by hepatic cells, and the potential implications for cell proliferation and function. METHODS: Liver stellate cell line CFSC-2G and primary hepatocytes in single and mixed cultures were exposed to mixtures of nucleosides and the concentrations of nucleoside derivatives were determined in the cultures, by high-performance liquid chromatography. Cell proliferation (DNA synthesis, cell cycle) and function (adenylate charge, albumin content, mitochondrial succinate dehydrogenase activity) were also evaluated. RESULTS: The exogenous nucleosides increased the intracellular concentrations of UTP, UDP-glucose, CDP-choline and NAD(+), in the single cultures of CFSC-2G and hepatocytes. Modification of the intracellular nucleotide pool paralleled changes in cell functional status, as indicated by increased adenylate charge and albumin content in hepatocyte cultures and in their co-cultures with CFSC-2G, and by increased succinate dehydrogenase activity in hepatocytes. CONCLUSION: Exogenous nucleosides were taken up by CFSC-2G and hepatocytes, which modified the intracellular concentrations of nucleotides, improved the functional status of hepatocytes, and partially restored the impaired adenylate charge of the co-cultures.

Albumins↗
PubMed2002

Chronic cough induced by abacavir apart from a context of hypersensitivity.

We report the case of an HIV-infected woman, who presented with chronic and productive cough without sign of hypersensitivity (fever, cutaneous eruption, gastrointestinal disorders), while taking abacavir. All complementary exams being negative, the involvement of abacavir has been suspected. So the drug was stopped leading to a rapid disappearance of cough. It is the first report of chronic cough with abacavir apart of a context of hypersensitivity reaction.

Alkynes↗
PubMed2001

Purification and characterization of an intracellular beta-glucosidase from a Candida sake strain isolated from fruit juices.

A yeast strain isolated in the laboratory from fruit juices was studied and classified as Candida sake. The strain produces an intracellular beta-glucosidase when grown with cellobiose as the carbon source. The enzyme was purified by ion-exchange chromatography and gel filtration. The molecular mass of the purified intracellular beta-glucosidase, estimated by gel filtration, was 240 kDa. The tetrameric structure of the beta-glucosidase was determined following treatment of the purified enzyme with sodium dodecyl sulfate. The enzyme exhibited optimum activity at 52 degrees C and pH 4.25 with citrate-phosphate buffer. The enzyme was active against soluble glycosides with the (1-->4)-beta configuration, and from Lineweaver Burk plots, a Km value of 6.9 mmol/L was found for p-nitrophenyl-beta-D-glucopyranoside. The beta-glucosidase was found to be tolerant to glucose inhibition with a Ki value of 0.2 mol/L.

Candida↗
PubMed1999

Transcriptional analysis of the nitrile-degrading operon from Rhodococcus sp. ACV2 and high level production of recombinant amidase with an Escherichia coli-T7 expression system.

Northern blotting analysis with RNA probes derived from amidase and nitrile hydratase genes from Rhodococcus sp. ACV2 revealed that both genes are part of the same operon. RNase protection mapping and sequence analysis indicated that the operon is probably under the control of a sigma 70-like promoter located upstream from the amidase gene. Plasmids were constructed with the cloned genes under tac and lac promoter control. Expression of amdA was demonstrated in Escherichia coli. In another construction, the amdA gene was inserted under the control of the bacteriophage T7 promoter. Large amounts of recombinant amidase (at least 20% of total proteins) in a soluble and active form were obtained with the E. coli-T7 expression system by lowering the growth temperature to 29 degrees C, without IPTG induction. The ratio of amidase activity of strain ACV2 to E. coli was approximately 1:3. Purification of the recombinant amidase was carried out in one chromatographic step, giving an enzyme preparation that could be used directly in a biotechnological process.

Amidohydrolases↗
PubMed1998

Long-term effects of cicletanine on secondary pulmonary hypertension.

Cicletanine, a furopyridine-derivative drug, was shown to enhance the production of endogenous prostacyclin. The potent vasodilating properties of prostacyclin are used to treat severe primary pulmonary hypertension. Prostacyclin has a short half-life and can be administered only as an i.v. infusion. The aim of this study was to evaluate the effects of cicletanine on pulmonary artery hypertension (PAH) resulting from chronic obstructive lung disease (COLD). In a double-blind controlled study, we evaluated the effects of short- and long-term administration of cicletanine (50 mg daily, orally) on hemodynamics and blood gases of patients with PAH resulting from COLD. The initial dose of 50 mg of cicletanine had no effect. A significant decrease in the mean pulmonary artery pressure (15%) and in total pulmonary resistance (20%) was observed after 3 or 12 months of treatment in the cicletanine group (11 patients), when compared with placebo (12 patients). PaO2 decreased slightly in the cicletanine group, but the difference from the control group was not significant. These results suggest that long-term treatment with cicletanine can induce effective pulmonary vasodilation in patients with PAH caused by COLD and that this is probably responsible for a small venous admixture.

Antihypertensive Agents↗
PubMed1998

Acyl transfer activity of an amidase from Rhodococcus sp. strain R312: formation of a wide range of hydroxamic acids.

The enantioselective amidase from Rhodococcus sp. strain R312 was produced in Escherichia coli and was purified in one chromatographic step. This enzyme was shown to catalyze the acyl transfer reaction to hydroxylamine from a wide range of amides. The optimum working pH values were 7 with neutral amides and 8 with alpha-aminoamides. The reaction occurred according to a Ping Pong Bi Bi mechanism. The kinetic constants demonstrated that the presence of a hydrophobic moiety in the carbon side chain considerably decreased the Km(amide) values (e.g., Km(amide) = 0.1 mM for butyramide, isobutyramide, valeramide, pivalamide, hexanoamide, and benzamide). Moreover, very high turnover numbers (kcat) were obtained with linear aliphatic amides (e.g., kcat = 333 s-1 with hexanoamide), whereas branched-side-chain-, aromatic cycle- or heterocycle-containing amides were sterically hindered. Carboxylic acids, alpha-amino acids, and methyl esters were not acyl donors or were very bad acyl donors. Only amides and hydroxamic acids, both of which contained amide bonds, were determined to be efficient acyl donors. On the other hand, the highest affinities of the acyl-enzyme complexes for hydroxylamine were obtained with short, polar or unsaturated amides as acyl donors (e.g., KmNH2OH = 20, 25, and 5 mM for acetyl-, alanyl-, and acryloyl-enzyme complexes, respectively). No acyl acceptors except water and hydroxylamine were found. Finally, the purified amidase was shown to be L-enantioselective towards alpha-hydroxy- and alpha-aminoamides.

Acylation↗
PubMed1998

[Case of superficial hemosiderosis of the central nervous system treated with trientine].

A 58-year-old woman, with recurrent headaches, exhibited cerebellar alaxic gait, anosmia, deafness and a pyramidal syndrome, with a progressive onset. In cerebrospinal fluid there was erythrocytes and siderophages. MRI on T2-weighted images revealed a marginal hypo-intensity, leading to the diagnostic of superficial siderosis of the central nervous system. None haemorragic lesion was found. The patient was given Trientine. Unfortunately she worsened on later examinations.

Brain↗
PubMed1998

Study of central and peripheral conductions to the diaphragm in 22 patients with definite multiple sclerosis.

Involvement of the diaphragm was evaluated electrophysiologically in 22 patients with definite multiple sclerosis. Magnetic transcranial stimulation (MTS), magnetic cervical stimulation at C4 level (MCS) and electric stimulation of the phrenic nerve at the neck (EPS) were performed for measuring latencies, motor conduction times and amplitudes of the responses recorded with a pair of surface or subcutaneous electrodes located at the xiphoid and the 8th costal interspace on the anterior axillary line. Latency of the motor evoked potentials (MEPs) was abnormal: in 9 patients following MTS, in 6 following MCS, in 2 following EPS. The motor conduction time between the cortex and the cervical spine, we called CMCT1, was abnormal in 11 patients and the motor conduction time between the cortex and the neck, we called CMCT2, was abnormal in 8 patients. However CMCT1 was more often unmeasurable than CMCT2 because the MEPs following MCS were unreliable in 4 patients. The conduction time between the cervical spine and the neck was abnormally long in 2 patients but it was paradoxically abnormally short in 3, probably because of the difficulties in locating exactly the place of the stimulation at the cervical C4 level. The MEP amplitude was not considered a reliable parameter because of the large range of the values in our controls, although the mean amplitude was significantly lower in the patients than in the controls. The amplitude of the compound muscle action potential (CMAP) following EPS was below the lower limit of the normal in 9 patients. The percentage of abnormal MEP latencies and CMCTs when both sides were combined was higher for the hemidiaphragms than for the upper limbs and was roughly the same for the hemidiaphragms and the lower limbs. Moreover electrophysiological study of the diaphragm was abnormal in 5 patients without pulmonary symptoms and with normal pulmonary function tests, demonstrating that this study is useful for revealing infraclinical demyelinating lesions on the central motor pathways down to diaphragm. In addition, alterations of the CMAPs in some patients suggest a possible extension of the lesions towards the anterior horns and anterior roots.

Adult↗
PubMed1997

[Multineuritis in essential hypereosinophilia syndrome].

A 72-old-man with a dramatic weight loss, exhibited a mononeuritis multiplex of subacute onset, and myalgia. There was hypoesthesia and weakness on median and ulnar nerves bilaterally, and weakness on left femoral nerve. Electrodiagnostical studies showed an axonal pattern of neuropathy. There was a considerable hypereosinophilia on blood count without any aetiologia found on exhaustive explorations. The idiopathic hypereosinophilic syndrome with a mononeuritis multiplex was suggested. Histological findings were an acute myelino-axonal degeneration with endoneural oedema, without vasculitis nor eosinophil cell on nerve-biopsy. Dramatic improvement occurred with corticosteroids and immunosuppressive treatment.

Aged↗
PubMed1996

Study of the amidase signature group.

Computer methods for database search, multiple alignment and cluster analysis indicated significant homology between amino-acid sequences of 21 amidases or amidohydrolases (EC 3.5). All of them were found to be involved in the reduction of organic nitrogen compounds and ammonia production. A conserved motif was found which may be important in amide binding and in catalytic mechanisms. Homology studies between these amidases and some ureases, nitrilases and acyl-transferases or enzymes with unknown functions provided new insight into the evolution of these proteins. Dissemination of these genes seemed to be facilitated by transfer of genetic elements such as transposons and plasmids.

Amidohydrolases↗
PubMed1996

Amide metabolism: a putative ABC transporter in Rhodococcus sp. R312.

The DNA sequence has been determined upstream of the amiE structural gene in the amidase operon of Rhodococcus sp. R312 and a new ORF (amiS2) identified. The amiS2 gene encodes a potential 206 amino acid (aa) protein containing a high proportion of hydrophobic residues. The AmiS2 protein possesses high homology to the ORFP3, amiS and ureI gene products from the Mycobacterium smegmatis (Ms) acetamidase operon, Pseudomonas aeruginosa (Pa) amidase operon and Helicobacter pylori (Hp) urease operon, respectively. Hydropathic analysis and secondary structure prediction of AmiS2 suggested the presence of seven potential transmembrane (TM) alpha-helices. Sequence analysis of the amiB2 gene, located downstream of the Rhodococcus sp. R312 amiE gene, showed that it encoded a 351-aa protein containing a potential ATP-binding motif. AmiB2 showed significant homology with the ATP-binding subunit of the bacterial Clp protease and high homology with the amiB product located within the Pa amidase operon. AmiB2 and AmiS2 appear to be two components of a recently identified novel family of ABC transporters (Wilson et al., 1995) and might be responsible for the adsorption of amidase substrates or release of their hydrolysis products.

ATP-Binding Cassette Transporters↗
PubMed1996

Color density spectral array for quick evaluation of sleep during nasal continuous positive airway pressure.

EEG color density spectral array enables quick evaluation of sleep. The aim of the study was to evaluate if an easily calculated sleep score based on this method could be used to assess the improvement of sleep after nasal continuous positive airway pressure (CPAP) in patients with sleep apnea syndrome (SAS). Eight hours of sleep are displayed on a single sheet along with EEG amplitude, 2 EEG channel spectra (FFT), electromyogram envelope and electro-oculogram. The x-axis corresponds to time, the y-axis to EEG frequency (range 0-16 Hz), and the color to the frequency power. This system allows the detection of sleep spindles, REM sleep and deep sleep (stages 3 and 4) as well as the evaluation of the sleep cyclic organization and its fragmentation by apnea. Based on these findings a sleep score is calculated. Eight young normal subjects were successively recorded as well as 15 SAS patients and with and without nasal CPAP. During the 1st night, the sleep score was lower in SAS patients than in normal subjects. With CPAP the apnea number decreased and the sleep score returned to normal in all patients except 1. A positive correlation was found between sleep score and duration of stage 2, stage 3 or REM sleep. A negative correlation was found between sleep score and the apnea index. This sleep score enables a quick and reliable evaluation of sleep in patients with SAS before and during nasal CPAP.

Adult↗
PubMed1995

Cloning and sequencing of the beta-glucosidase-encoding gene from Candida molischiana strain 35M5N.

We have isolated a gene (bgln) encoding beta-glucosidase (beta Glu) from a cosmid library of the yeast, Candida molischiana 35M5N. The nucleotide sequence of bgln and its flanking regions was determined. This gene was found to be composed of 2289 bp and 763 amino acid (aa) residues encoding an 83.3-kDa protein. The aa sequence shared eleven putative N-glycosylation sites. Homology comparisons showed that this enzyme can be considered as a new member of the family-3 glycosyl hydrolases. Multiple alignment experiments revealed four conserved regions on aa sequences from beta Glu of this family.

Amino Acid Sequence↗
PubMed1995

Brevibacterium linens pBL33 and Rhodococcus rhodochrous pRC1 cryptic plasmids replicate in Rhodococcus sp. R312 (formerly Brevibacterium sp. R312).

The replication of two cryptic plasmids from Brevibacterium linens ATCC 9174 (pBL33) and Rhodococcus rhodochrous ATCC 4276 (pRC1) was investigated in Rhodococcus sp. R312 (formerly Brevibacterium sp. R312). The recombinant plasmids pSP33 (pBL33 derivative) and pSPC1 (pRC1 derivative) were found to be suitable for establishing new host-vector systems for Rhodococcus sp. R312. They all carry the Tn903 neomycin-resistance-encoding gene (aphI).

Bacterial Proteins↗