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Biomedical subjects

G Dreyfus

Publications and source records attributed to G Dreyfus.

At least 127 records · Page 7Linked to original sources
PubMed1984

The epsilon subunit as an ATPase inhibitor of the F1-ATPase in Escherichia coli.

The isolation of protein ATPase inhibitor was attempted directly from Escherichia coli membrane extracts to examine the possible presence of a Pullman-Monroy-type inhibitor [M. E. Pullman and G. C. Monroy (1963) J. Biol. Chem. 238, 3762-3769] distinct from the epsilon subunit of E. coli ATPase. Purification to homogeneity was achieved in a sequence of steps involving trichloracetic acid precipitation, DEAE-cellulose, Sephadex G75 chromatography, and a terminal isoelectric focusing step. An inhibitory protein was obtained and was identified by its physicochemical and inhibitory properties as the epsilon subunit of E. coli ATPase. The other inhibitory fraction observed in the purification procedure consisted of aggregated epsilon subunits.

Amino Acids↗
PubMed1984

Isolation of the mitochondrial F1-F0 adenosine triphosphatase by Sepharose-hexylammonium chromatography: properties and reconstitution in liposomes.

Lauryl dimethylamino oxide, a zwitterionic detergent, was employed to solubilize the H+ ATPase from beef heart mitochondria. A simple preparation procedure has been devised to obtain F1-F0 based on a method described to purify F1 ATPase (M. Tuena de Gómez-Puyou and A. Gómez-Puyou, 1977, Arch. Biochem. Biophys. 182, 82-86) which consists of the selective adsorption of F1 to Sepharose-hexylammonium beads. The preparation showed approximately 18 bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis; 5 correspond to F1 subunits and the rest probably to the stalk and hydrophobic sector F0. The binding of [14C]dicyclohexylcarbodiimide to a low-molecular-weight component of this preparation was demonstrated. The F1-F0 complex was reconstituted into phospholipid vesicles which displayed ATP-Pi exchange and ATP-dependent 9-aminoacridine fluorescence quenching, both sensitive to proton channel inhibitors.

Adenosine Triphosphatases↗
PubMed1984

Low molecular weight (LMW) heparin derivatives in experimental extra-corporeal circulation (ECC).

Low molecular weight (LMW) heparin has been shown to prevent experimental venous thrombosis. In order to investigate its biological action and its potential use in open heart surgery, we have conducted an experimental study using extracorporeal circulation (ECC) in sheep as an experimental model. 18 sheep were randomly selected to receive either LMW heparin (2 mg/kg), high dose heparin (HD; 160 U/kg), or low dose heparin (LD; 60 U/kg). The HD heparin yielded the same circulating anti-activated factor X (anti-Xa) activities as the LMW heparin and the LD heparin yielded the same anti-thrombin activity. LMW heparin and HD heparin were both effective in preventing blood clotting in the ECC circuit, demonstrating the antithrombotic activity of the LMW heparin. Clotting in the circuit was observed following LD heparin administration showing that the efficacy of LMW heparin does not only rely upon its weak anti-activated partial thromboplastin time (APTT) and anti-thrombin activity. Fibrinogen, fibrinogen degradation products (FDP), factor V (FV), platelet count, antithrombin III (AT III), fast acting antiplasmin (AP) were evaluated during and after ECC. The defects in hemostasis were similar in the three groups. Conclusions were: (1) heparin chain depolymerization diminishes the anti-APTT activity without altering the anti-thrombotic property; (2) LMW heparin is an effective alternative to heparin in cardiac surgery; (3) the absence of postoperative circulating anti-APTT activity might be associated with a reduced incidence of hemorrhagic complication, but we were not able to demonstrate it.

Animals↗
PubMed1983

Regulation of the synthesis and hydrolysis of ATP by mitochondrial ATPase. Role of the natural ATPase inhibitor protein.

The action of the natural ATPase inhibitor protein of Pullman and Monroy (Pullman, M. E., and Monroy, G. C. (1963) J. Biol. Chem. 238, 3762-3769) on the mechanisms of energy conservation of heart mitochondria has been explored. The synthesis and hydrolysis of ATP and the Pi-ATP exchange reaction were studied in submitochondrial particles that possess the ATPase-inhibitor protein complex in two distinguishable states. In addition to their different rates of hydrolysis, the two states of the complex have been identified from their different accessibility to antibodies directed against the inhibitor protein, and from the different action of antibodies and trypsin on the ATPase activity of the two types of particles studied. The steady state rates of hydrolysis and of the Pi-ATP exchange reaction of the particles are determined by the state in which the ATPase-inhibitor complex exists. Apparently by modifying the rate of one of the steps involved in the catalytic reaction of the ATPase, the inhibitor protein determines the extent to which the enzyme is able to catalyze ATP hydrolysis and the Pi-ATP exchange reaction. This action of the inhibitor protein also reflects the rate at which the particles carry out oxidative phosphorylation.

Adenosine Triphosphate↗
PubMed1983

[Surgery of recurrent aortic dissection. Apropos of 6 cases].

The authors report a series of 6 cases of recurrent dissection, 4 of which were treated surgically, out of a total of 64 acute dissections of the aorta referred to the CMC Foch, between January 1969 and October 1981. Three types of recurrent dissection were identified: --"de novo" recurrent dissection: a new dissection occurring in part of the aorta previously unaffected with a new intimal tear; --recurrent dissection due to extension of the previous dissection; --"in situ" recurrent dissection. Surgery is the treatment of choice because of the poor prognosis. Extensive resection (sometimes carried out in several stages) and deep hypothermia are valuable techniques when part of the aorta giving off arteries to vital organs has to be replaced. The use of GRF biological glue in the treatment of the original acute dissection has been a significant advance in the prophylaxis of recurrent dissection as it ensures better repair of the distal false lumen (27% persistent false lumens). With respect to an extensive replacement of the dissected vessel, the authors advise operation in several stages, especially in young subjects with Marfan's syndrome who are at high risk of recurrent dissection. All cases of acute dissection of the aorta, operated or not, should be followed up indefinitely with clinical and radiological examination, completed, when necessary, by an angioscan and an aortography.

Adult↗
PubMed1981

Modified technique for correction of tricuspid atresia.

This study presents a new technique for correction of tricuspid atresia. All 13 patients operated upon had the same form of the anomaly, with the great arteries normally related. The principle is to conserve the pulmonary valve and anulus of the patient in its anatomic position and to exclude the hypoplastic right ventricle. Because there is no need for closing the ventricular septal defect, the risk of heart block and residual left-to-right shunts is avoided. Deaths are related to questionable indications for two patients and to a bilateral pneumothorax for the third one. The long-term follow-up (5 years for the first patient) shows good results for the 10 survivors. Six of them are in Class 1 of the New York Heart Association and four are in Class II.

Adolescent↗
PubMedDate not supplied

Toward a principled methodology for neural network design and performance evaluation in QSAR. Application to the prediction of logP.

The prediction of properties of molecules from their structure (QSAR) is basically a nonlinear regression problem. Neural networks are proven to be parsimonious universal approximators of nonlinear functions; therefore, they are excellent candidates for performing the nonlinear regression tasks involved in QSAR. However, their full potential can be exploited only in the framework of a rigorous approach. In the present paper, we describe a principled methodology for designing neural networks for QSAR and estimating their performances, and we apply this approach to the prediction of logP. We compare our results to those obtained on the same molecules by other methods.

Algorithms↗