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Biomedical subjects

N Dubois

Publications and source records attributed to N Dubois.

26 records · Page 2Linked to original sources
PubMed1984

[Monitoring therapeutic arteriovenous fistulas in chronic hemodialysis patients. Value of the continuous Doppler test combined with real-time echotomography].

Continuous doppler investigation of functioning of therapeutic arteriovenous fistula is a well-established routine. The availability for the last few years of high frequency (10 mg/Hz) real-time ultrasound has enabled visualization of superficial arteries and veins. Total afferent and efferent branches of these therapeutic fistulae can be visualized. Examination should therefore include continuous doppler recordings combined with real-time ultrasound of both transverse and sagittal sections of the different arteries and veins participating in the fistula. The indication for examination is clinical in cases with low or high output or during the immediate postoperative period to detect early thrombosis.

Arteriovenous Shunt, Surgical↗
PubMed1982

Orthotopic nonauxiliary homotransplantation of part of the liver in dogs.

An experimental study was carried out investigating the feasibility of using only a portion of a donor liver in orthotopic, nonauxiliary transplantation, establishing a canine model. After being totally hepatectomized, 20 immunosuppressed adult beagles received a 60% donor liver graft, derived from tissue-typed identical littermates. Preservation time was 5 hr. In control experiments, 10 beagles, only half of them immunosuppressed, underwent an operation involving complete liver mobilization, vascular exclusion, cooling of the liver in situ, and a 40% partial hepatectomy with biliary anastomosis. The surgical procedure, including the method of cooling and preservation, is described in detail. Survival rate amounted to 90% for the control group and 50% for the transplanted group, while all surviving dogs were sacrificed 24 wk postoperatively. At sacrifice, the liver weight amounted to the weight of the total native liver at operation. Body weight profiles reflect good general condition of the surviving dogs. No major differences were noted between the immunosuppressed and the nonimmunosuppressed control dogs. No complications were related to the fact that only a partial liver was grafted or left in situ.

Animals↗
PubMedDate not supplied

Hemorrhoidectomy: Hospital Leopold Bellan procedure.

The authors describe their hemorrhoidectomy technique, a modification of Milligan-Morgan. It differs by the association of a posterior anoplasty (with internal sphincterotomy in the case of a fissure or sphincter hypertonia) and of a sub-mucocutaneous dissection of the security bridges. They report on their experience with 410 operations carried out during the year 1985. Immediate complications are mainly hemorrhage (2.68%) and urinary problems (9%). Average cicatrization time is about six weeks. At one year, there were no relapses nor fissures. A moderate stenosis was observed in 1.45% of the cases, and a hypocontinence to flatus in 2.3%. Use of a CO2 laser does not result in any modification of these results.

Fissure in Ano↗
PubMedDate not supplied

In vitro irreversible binding of ketoprofen glucuronide to plasma proteins.

Many aryl alkanoic acids are cleared as ester glucuronide excreted in urine. While conjugation with glucuronic acid is generally considered as a detoxication process, this conjugate has been shown over the past decade to be a potentially reactive metabolite, undergoing hydrolysis, intramolecular rearrangement, and irreversible binding to proteins. This study describes the in vitro degradation of biosynthetic ketoprofen glucuronide after incubation with human plasma, human serum albumin solutions at various concentrations (290 and 580 microM), and in protein-free buffer, in physiological conditions (pH = 7.4, 37 degrees C). The protein concentrations chosen correspond to that found in synovial fluid and plasma, respectively. Albumin catalyzed the hydrolysis of the glucuronide, but the extent of the reaction was not dependent on the protein concentration. The irreversible binding of ketoprofen was investigated in identical conditions. Maximal ketoprofen-adduct concentrations were achieved after 3 and 10 hr incubation, and were 6.65, 3.2, and 2.6% of initial ketoprofen in plasma and albumin solutions at 580 and 290 microM, respectively. The difference in binding between plasma and albumin (580 microM) could not be totally attributed to the other major plasma proteins, because no irreversible binding was detected with fibrinogen and gamma globulins, and only 0.14% of ketoprofen was bound to alpha and beta globulins after 3 hr incubation. The covalent interaction with albumin was proportional to conjugate concentration over the range studied (from 5 to 30 micrograms/ml or 11.62 to 69.72 microM).

Blood Proteins↗
PubMedDate not supplied

[Stereoselective protein binding of non-steroidal anti-inflammatory agents. Pharmacological implications].

Non steroidal anti-inflammatory drugs (NSAIDs) contain a chiral carbon alpha to carboxyl function. Except for naproxen, chiral NSAIDs are marketed for clinical use as racemate, ie an equimolar mixture of the two enantiomers R(-) and S(+). However, in vitro studies have shown that the anti-inflammatory activity exists almost solely in the S form. The unbound fraction is able to diffuse into tissues and to reach sites of action. It represents also the pharmacological active form. Stereoselective protein binding studies carried out at various concentrations of NSAIDs and albumin are used to evaluate the free fraction of the active enantiomer. Two optical isomers do not interact in the same manner with proteins and this binding stereoselectivity depends on NSAID and experimental conditions. Thus, it seems difficult to predict the in vivo free concentration of each enantiomer and protein binding experiments should be achieved taking into account the physiopathological parameters which influence this biological process. This enantioselectivity is determinant for the pharmacokinetic properties and could be responsible of the parameters variation obtained for each enantiomer. It could explain the variability in response to NSAIDs too. In fact, the anti-inflammatory effect is directly function of the free concentration of the S isomer. To correlate the NSAID dose with its activity, it should be better to determine this free fraction in the site of action, in particular in the synovial fluid. But the clinical response, as for example the antalgic effect, remains very far from the pharmacological activity, ie the cyclooxygenase inhibition.

Anti-Inflammatory Agents, Non-Steroidal↗