Search PubMed⌕ Search

Biomedical subjects

J Guignard

Publications and source records attributed to J Guignard.

At least 19 recordsLinked to original sources
PubMed1999

The role of bradykinin in neonatal hemodynamic effects of ACE inhibition.

Angiotensin-converting enzyme (ACE) inhibitors exert their effects by inhibiting angiotensin II (AII) production, but also by inhibiting bradykinin (BK) degradation. In order to clarify whether BK is involved in the systemic effects of ACE inhibition in the newborn period, we investigated the effect of perindoprilat (20 microgram/kg i.v.) in newborn rabbits, with or without the blockade of BK beta(2)-receptors (Hoe 140, 300 microgram/kg s.c.). The bolus infusion of perindoprilat resulted in a marked fall in mean arterial blood pressure (MBP) and a slight decrease in heart rate. BK receptor blockade had no effect on the perindoprilat-induced hypotension but the negative chronotropic effect of ACE inhibition was partly prevented by pretreatment with Hoe 140. We therefore conclude that BK is not involved in neonatal blood pressure regulation but that the ACE inhibition-induced neonatal bradycardia is at least partly BK- mediated.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

[Lipid peroxidation in the presence of inorganic compounds. Relation to oxidative stress mechanisms].

Oxidizing activity study of inorganic compounds is based on a mechanistic approach. This approach implies research of the capacity of these materials, after interaction with molecular oxygen, to generate activated oxygen species (AOS) in aqueous medium. These electrophilic species are able to participate in oxidative stress processes and some AOS differ in their oxidizing power; highly oxidizing species (A*) and entities (P*) less oxidizing than A*. These AOS are capable of initiating linolenic acid peroxidation leading to formation of different degradation products such MDA, monoaldehydes, conjugated dienes and trienes, hydroperoxydes, and ethane. The detection of these products allows to reveal the presence of AOS. Our data show that the global assessment of lipid peroxidation should be established from the whole of formed peroxidation products and not from one type of degradation products.

Asbestos, Serpentine↗
PubMed1993

Radical oxidation reactions of the purine moiety of 2'-deoxyribonucleosides and DNA by iron-containing minerals.

The radical oxidation capability of several classes of iron minerals, including biotite, hematite, magnetite, minette, nemalite, pyrite, vivianite and two chrysotiles (asbestos), was investigated by using a double experimental approach. One involved the electron spin resonance spin-trapping measurement of organic radicals obtained by the reaction of activated oxygen species, released upon incubation of the minerals in phosphate buffered solutions with formate used as the target molecule. In addition, the formation of mineral-mediated oxidation purine decomposition products, including 7,8-dihydro-8-oxo-2'-deoxyguanosine and 7,8-dihydro-8-oxo-2'-deoxyadenosine, was searched within nucleosides and DNA by using specific and sensitive HPLC electrochemical assays. Emphasis was placed on the mechanistic aspects of the radical oxidation reactions involved in the formation of the two C(8) hydroxylated purine decomposition products.

Adenine↗
PubMed1993

The spleen at risk after penetrating trauma.

UNLABELLED: In contrast to blunt splenic trauma where nonsurgical management is an option, splenorrhaphy is the current preferred approach for penetrating trauma. Splenectomy, however, may be required because of hemodynamic instability, the extent of the trauma, or when a pancreatic injury requires distal pancreatectomy. We evaluated our attempts at splenic preservation in 69 patients (1988-1992) in whom the spleen was at risk for removal. Fifty-seven patients had penetrating injury to the spleen and 12 patients had distal pancreatectomy. Splenic Trauma (n = 57): 6 patients (mean Abdominal Trauma Index 45) died within 24 hours of extensive injuries. All had splenectomy. Thirty-seven of the remaining 51 (72.5%) had successful splenorrhaphy, 85% with stab wounds (SWs) and 65.5% with gunshot wounds (GSWs). Splenic salvage was 100%, 100%, 92%, 37%, and 0%, respectively, for grades I-V injuries. Absorbable mesh splenorrhaphy improved splenic salvage in grade III and IV injuries from 67% and 0% in previous years (1983-1987) to 92% and 37% in recent years (1988-1992), p < 0.01. The use of the mesh did not increase septic complications, even in the presence of enteric perforation. Distal Pancreatectomy (n = 12): 1 died intraoperatively. The spleen was not injured in 6 and was preserved in all 6. The overall 54.5% splenic salvage rate was achieved without increasing morbidity or the number of transfusions. CONCLUSIONS: (1) Splenorrhaphy should be possible in the great majority of stable patients after penetrating trauma. (2) Absorbable mesh is a valuable adjunct that may facilitate the repair of more severe grades of splenic trauma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Production of free radicals arising from the surface activity of minerals and oxygen. Part I. Iron mine ores.

The excess incidence of lung cancers observed in many metal mines probably is not only correlated with radioactivity but also with the inhaled dusts. In an attempt to determine a possible mechanism of carcinogenicity related to the surface activity of dusts, using the spin-trapping agent and ESR spectroscopy, one can demonstrate that some mineral dusts from iron ore mines are very active in an oxidative process in aqueous medium, implying the formation of radical oxygen species on reducing surface sites of the solid. This reducing surface activity of the dusts depends on the presence of Fe2+ ion in the lattice and on the process of activation and passivation of the surface sites. The more simple process of activation is the dissolution of the oxidized coating on the particle surface. Among the oxides, oxyhydroxides, carbonates, and silicates, the magnesium-iron phyllosilicates (chlorite, biotite, berthierine) appear the most active. The siderite FeCO3 is also active, but the iron oxides and oxyhydroxides are generally nonactive.

Free Radicals↗
PubMed1989

Production of free radicals arising from the surface activity of minerals and oxygen. Part II. Arsenides, sulfides, and sulfoarsenides of iron, nickel, and copper.

The excess incidence of lung cancers observed in metallic mines other than iron mines probably can be correlated not only to radioactivity, but also to dust pollution. The present work investigates the role of surface properties of sulfides and arsenides, which are present in metal mines, in oxidizing mechanisms capable of inducing oxidative stress and, possibly, of participating in carcinogenesis. Using added spin-trapping agent followed by ESR spectroscopy, it was observed that nickel and copper arsenides can be very active in the oxidation of formate or DMSO, by reducing the oxygen dissolved in a cell-free medium. Sulfides, on the other hand, are not active, except for the iron sulfides, which are very active as an air-aged powder. The process of activation and rendering the particle surface passive was investigated. Surface dissolution and moderate grinding were found to be activating factors, while air-aging generally rendered the particle surface passive. The critical factor in determining activity is the availability of reducing species of iron, copper, or nickel on the surface of the minerals.

Arsenates↗
PubMed1989

Production of oxygen radicals by the reduction of oxygen arising from the surface activity of mineral fibres.

According to certain hypotheses, the production of oxygen radicals within the biological medium (the phenomenon of oxidative stress) may play an important role in fibrosis and in certain steps of carcinogenesis. The mineral fibres of various materials are capable of participating in this phenomenon, owing to the reducing nature of their surface activity, so that OH. radicals can be produced from oxygen in 3 steps. The surface activity of inorganic materials which are insoluble or only very slightly soluble is due to the presence of electron donor active sites, generally linked to Fe2+ ions found in the neighbourhood of the surface. In biological systems, these sites may emerge on the surface as a result of the partial dissolution of the particle, the action of a biological reducing agent, the phenomenon of deposition on the surfaces or cation exchange. We have explored the reducing properties of the surfaces of a certain number of mineral fibres, in aqueous buffer medium, by electron paramagnetic resonance (EPR) measurement of the adduct with the radical-trapping agent 5,5'-dimethyl-l-pyrrolidine-N-oxide (DMPO), produced from the radicals initially formed (OH. or R.). We have found certain fibres to be highly effective in producing radicals from dissolved oxygen (Canadian chrysotile, nemalite, freshly ground amphiboles) while others have little effect. The reducing activity of certain fibres may be markedly increased by prior treatment in the presence of a ferrous salt (as in the case of erionite) or by the addition of glutathione to the reaction medium (as in the case of UICC crocidolite). It is suggested that the carcinogenic activity of certain inorganic materials at the pulmonary level is the result of their surface reducing properties. These reducing properties may either be present at the time of inhalation or acquired in the biological medium. This hypothesis is not in conflict with the observation of the role of the dimensional characteristics of fibres in mesothelioma.

Asbestos↗
PubMed1986

Studies on surface properties of asbestos. IV. Catalytic role of asbestos in fluorene oxidation.

To determine whether asbestos is a basic catalyst, catalytic oxidation of fluorene to fluorenone in a heterogeneous system was tested. It was shown that oxidation was quantitatively possible on the surface of all basic minerals, such as asbestos (chrysotile and crocidolite) and magnesia, but was not possible with acidic mineral materials such as silica. The effects of different factors are discussed.

Adsorption↗
PubMed1985

[Hospitals transfers of children of Maghreb countries. Reflections on current problems and short- and long-term solutions].

Every year, several thousands of North African children receive transfers to France for hospitalization. The need for these medical transfers is linked to a rapidly expending population, improving diagnostic techniques and inadequate therapeutic technology. Affected children are referred most often for cardiac and oncological diseases. Efforts have been made to discern the medical indications for such transfers, to facilitate the acceptance by social aid agencies and to provide the best possible psychosocial and educational settings for the children involved. Yet, many problems remain, such as advanced disease states and associated diseases at the time of transfer, affective disorders, worsened by the prolonged stay in hospital. Solutions must be found for these problems. Examples would include close collaboration between referred North African and French medical teams, and the existence in France of cultural environment sensitive to the needs to the North African patients. Because transfers are responsible for a high financial and affective cost, and for a dependent relationship between countries, long-term solutions must be considered and could include the transfer of technology and cooperation in research rather than medical care.

Africa, Northern↗
PubMed1981

Respiratory function is impaired less by transverse than by median vertical supraumbilical incisions.

Respiratory function in the first four days after elective cholecystectomy has been compared in 15 women in whom abdominal incision was transverse and 15 in whom it was median vertical. Ventilatory function (vital capacity and forced expiratory volume in one second) and blood gas tensions (partial pressures of oxygen and of carbon dioxide in arterial blood, arterial whole-blood carbon dioxide, and alveolo-arterial oxygen tension difference) were determined on the day before operation and on the first, second and fourth postoperative days. Ventilatory function was depressed postoperatively in all the patients, but the depression was significantly less, and of significantly shorter duration, after the transverse than after the median vertical approach. Significant changes in blood gas tensions were noted postoperatively after both incisions, but without significant difference between the two groups.

Abdomen↗
PubMed1977

[The value of early routine radiological examination following esophagectomy for carcinoma of the lower third of the esophagus].

An early upper gastrointestinal series may be carried out on a routine basis after recovery of the postoperative ileus and makes it possible to confirm the good quality of the anastomoses or, by contrast, reveal a benign fistula. Under some circumstances, it may be carried out very early following the development of postoperative complications: pain, fever, respiratory, circulatory and renal insufficiency or in the presence of abnormal discharge from the drains. It then shows whether this complication is due to an oesophagomediastinal or pleural fistula.

Adult↗
PubMed1977

[Pulmonary complications of esophagectomy for carcinoma of the middle third of the esophagus].

The authors studied 20 patients undergoing operation for a carcinoma of the middle third of the oesophagus during the period January 1972 to April 1975. Postoperative pulmonary complications are extremely common in such patients. All the patients had pulmonary function study results which were compatible with this type of surgery. All underwent resection with oesophagogastric anastomosis via a left thoracophrenolaparotomy. Of the 20 patients, 14 suffered from one or more episodes of acute respiratory insufficiency, some related to pneumonia. On the basis of various associated clinical, radiological, biological, evolutive and histopathological criteria, five types of pulmonary complication were distinguished: 1-Shock lung; 2-Infective pneumonia; 3-Traumatic pulmonary disease; 4-Acute cor pulmonale; 5-Lung disease of undetermined origin. Twelve patients died as a result of pulmonary complications, 11 early (before the 16th day). One patient only died as a result of rupture of the oesophagogastric anastomosis.

Esophageal Neoplasms↗