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Biomedical subjects

A Roussel

Publications and source records attributed to A Roussel.

At least 19 recordsLinked to original sources
PubMed1992

Solution conformation of human neuropeptide Y by 1H nuclear magnetic resonance and restrained molecular dynamics.

The solution structure of human neuropeptide Y has been solved by conventional two-dimensional NMR techniques followed by distance-geometry and molecular-dynamics methods. The conformation obtained is composed of two short contiguous alpha-helices comprising residues 15-26 and 28-35, linked by a hinge inducing a 100 degree angle. The first helix (15-26) is connected to a polyproline stretch (residues 1-10) by a tight hairpin (residues 11-14). The helices and the polyproline stretch are packed together by hydrophobic interactions. This structure is related to that of the homologous avian pancreatic polypeptide and bovine pancreatic polypeptide. The C- and N-terminii, known to be involved in the biological activity for respectively the receptor binding and activation, are close together in space. The side chains of residues Arg33, Arg35 and Tyr36 on the one hand, and Tyr1 and Pro2 on the other, form a continuous solvent-exposed surface of 4.9 mm2 which is supposed to interact with the receptor for neuropeptide Y.

Amino Acid Sequence↗
PubMed1990

Conformational flexibility of a scorpion toxin active on mammals and insects: a circular dichroism study.

Three scorpion toxins have been analyzed by circular dichroism in water and in 2,2,2-trifluoroethanol (TFE) solutions. These toxins were chosen because they are representative of three kinds of pharmacological activities: (1) toxin AaH IT2, an antiinsect toxin purified from the venom of Androctonus australis Hector, which is able to bind to insect nervous system preparation, (2) toxin Css II, from the venom of Centruroides suffusus suffusus, which is a beta-type antimammal toxin capable of binding to mammal nervous system preparation, and (3) the toxin Ts VII from the venom of Tityus serrulatus, which is able to bind to both types of nervous systems. In order to minimize bias, CD data were analyzed by a predictive algorithm to assess secondary structure content. Among the three molecules, Ts VII presented the most unordered secondary structure in water, but it gained in ordered forms when solubilized in TFE. These results indicated that the Ts VII backbone is the most flexible, which might result in a more pronounced tendency for this toxin molecule to undergo conformational changes. This is consistent with the fact that it competes with both antiinsect and beta-type antimammal toxins for the binding to the sodium channel.

Amino Acid Sequence↗
PubMed1990

Three-dimensional structures of complexes of Lathyrus ochrus isolectin I with glucose and mannose: fine specificity of the monosaccharide-binding site.

The structure of the methyl-alpha-D-mannopyranoside-LOL I complex has been solved by the molecular replacement method using the refined saccharide-free LOL I coordinates as starting model. The methyl-alpha-D-mannopyranoside-LOL I complex was refined by simulated annealing using the program X-PLOR. The final R-factor value is 0.182 [Fo greater than 1 sigma(Fo)]. The isostructural methyl-alpha-D-glucopyranoside-LOL I complex was refined by X-Ray coupled energy minimization using the methyl-alpha-D-mannopyranoside-LOL I structure as a starting model to an R factor of 0.179 (all data). In both crystal forms, each dimer binds two molecules of sugar in pockets found near the calcium ions. The two saccharide moieties, which are in the C1 chair conformation, establish the same hydrogen bond pattern with the lectin. However, the van der Waals contacts are different between the O2, C2, C6, and O6 atoms of the two molecules and the backbone atoms of residues 208-211. Mannose, due to its axial C2 conformation, encloses the backbone atoms of the protein in a clamplike way. Van der Waals energy calculations suggest that this better complementarity of the mannoside molecule with the lectin could explain its higher affinity for isolectin I.

Binding Sites↗
PubMed1990

CRYStallize: a crystallographic symmetry display and handling subpackage in TOM/FRODO.

We have implemented in TOM/FRODO a protein crystallographic symmetry display and handling package, called CRYStallize. This package is designed as an aid in solving protein structures by molecular replacement methods. It allows the rotation/translation solutions provided by molecular replacement programs to be checked in a fast and easy way. Using CRYStallize, approximate solutions can also be improved by manual modifications. Symmetry-related objects, represented as surfaces, can be generated and handled in the same way as the reference molecules, thus permitting an efficient analysis of crystal packing and site accessibility. This program is available in the TOM/FRODO software release, which runs on the Silicon-Graphics workstations.

Computer Graphics↗
PubMed1989

Palliative therapy of inoperable oesophageal carcinoma with radiotherapy and methotrexate: final results of a controlled clinical trial.

Between May 1976 and January 1982, 170 patients were entered in a randomized study comparing a combined treatment consisting of methotrexate followed by irradiation versus radiotherapy alone in patients with non metastatic inoperable oesophageal cancer. Methotrexate was administered subcutaneously in 4 days to a total dose of 24 mg/m2. Radiotherapy was performed, in both groups, at a dose of 56.25 Gy in 25 fractions (5 weeks). The administration of methotrexate did not lead to an increased intolerance to radiotherapy but severe hematological toxicities were observed in 7.8% of the cases. No difference in the duration of survival was detected. Initial performance status of the patients and their weight loss prior to entry on trial were the factors that were most predictive of the patient's prognosis.

Adult↗
PubMed1989

[Hydrocholecystitis in children and newborn infants. Apropos of 3 cases].

We report two cases of hydrocholecystitis in children and one in a neonate. One child had hepatitis A and the other had typhoid fever. A beta-hemolytic group B streptococcal infection was found in the neonate. In all three cases, the first manifestation was an abdominal mass and treatment of the causative disease ensured recovery. These three observations provided us with the opportunity for reviewing the literature. Isolated hydrocholecystitis is distinguished from hydrocholecystitis as a symptom. The clinical evaluation and diagnostic investigations are described in detail; special attention is given to abdominal ultrasonography. Etiology and pathophysiology, as well as management are discussed. Our three cases and the review of the literature confirm the benign prognosis of this condition.

Child, Preschool↗
PubMed1989

[Adjuvant radiochemotherapy in operable cancers of the thoracic esophagus. Preliminary results of a multicenter study. A study of 119 cases].

119 operable patients with an oesophageal squamous cell carcinoma were treated preoperatively by a combination of radiotherapy (37 Gy in two courses) and chemotherapy by cisplatin (delivered before each course of radiation). The response was evaluated on the resected specimen. 111 patients underwent operation and 101 tumours were resected. The toxicity was acceptable by reducing the Cisplatin dosage from 100 mg/m2 to 80 mg/m2 for the last 67 patients. A complete response was observed in 24 patients and a partial response in 46. The preliminary results show a 57% eighteen-month survival in the group of resected patients. A controlled study is needed to compare this combined regimen versus surgery alone in curatively resectable patients.

Adult↗
PubMed1989

Adjuvant radiotherapy and chemotherapy in resectable gastric cancer. A randomized trial of the gastro-intestinal tract cancer cooperative group of the EORTC.

One hundred and fifteen patients with curative and palliative surgery for gastric cancer were randomized to receive radiotherapy alone (1) or in combination with short-term (ST) 5-FU (2), long-term (LT) 5-FU (3), ST and LT 5-FU (4). The ST 5-FU was given at a daily dose of 575 mg/m2, every 4-6 h during the first 4 days of treatment before starting irradiation. The LT 5-FU was given at a dosage of 750 mg/m2 every 2 weeks for 18 months or until progression. The median survival times for treatment 1 to 4 was respectively 12, 10, 15 and 18 months. There was a statistically significant overall difference between the four treatments (P = 0.041). However, when the comparisons were adjusted for the most significant prognostic factors, the difference in survival disappeared. Moreover, no difference was found between treatments in terms of time progression. Nevertheless, among 22 patients with residual tumour, the three who were still alive without disease progression (with survivals of 19+, 49+ and 90+ months at the time of this analysis) had been treated with radiotherapy combined with ST and LT 5-FU.

Adenocarcinoma↗
PubMed1988

Hemibody irradiation in stage III multiple myeloma: results of 20 patients.

The advanced forms of multiple myeloma of bone, stage III, or those with a large tumoral mass, characterized by a considerable number of myeloma-cells, pose difficult problems in treatment. Little progress has been made since the introduction of the alkylating agents, and combined chemotherapy does not seem to be any more effective in terms of survival. It is these severe forms that culminate in painful symptoms which are often difficult to eliminate. The radiosensitivity of myeloma led us to treat 20 patients affected by severe forms of the disease by total body irradiation in two stages, and we analyse here the effects of treatment and the tolerance for this technique.

Female↗
PubMed1987

[Radiation enteritis after pelvic irradiation of cancer of the rectum. Prevention by omentoplasty and pelvic partitioning with polyglactin 910 mesh].

To prevent radiation enteritis during post-operative irradiation of the pelvis for rectal carcinoma, the greater omentum, fed by the left gastro-epiploic pedicle, is pulled down into the pelvis which is separated from the abdomen by an absorbable polyglactin 910 mesh. The mesh, under tension, is attached superiorly to the lips of the posterior peritoneal section and anteriorly to the upper border of the pubis. This procedure has been used in seven patients, four of whom have been irradiated post-operatively without any gastrointestinal complication.

Enteritis↗
PubMed1986

[Intraoperative abdominopelvic radiotherapy by single dose electrons].

Thirty-four patients received, during laparotomy, a 15-20 Gy localized irradiation from a 10-13 MeV beam of electrons supplied by a linear accelerator and focalized by means of a localizer especially designed for this purpose. This technique is indicated for localized residual tumours of the pelvis and intra-operative irradiation of the lumbar aorta, as part of a chemo-radiotherapeutic programme in patients with advanced cancer of the cervix. It is too early to evaluate the medium-term results, but the technique is very well tolerated immediately.

Abdominal Neoplasms↗