Biomedical subjects

A Léon

Publications and source records attributed to A Léon.

At least 19 recordsLinked to original sources

PubMed2003

Gemcitabine/vinorelbine in metastatic breast cancer patients previously treated with anthracyclines: results of a phase II trial.

This phase II study was designed to evaluate the response rate (RR) and toxicity of gemcitabine/vinorelbine in patients with metastatic breast cancer. All patients had previously received anthracyclines. Treatment consisted of gemcitabine 1200 mg/m2 and vinorelbine 30 mg/m2 on days 1 and 8, every 3 weeks. Twenty-five patients were enrolled. Median age was 59 years (range, 33-73 years). Ten patients had received only adjuvant therapy with anthracyclines. The remaining 15 patients had received chemotherapy for metastatic disease, including taxanes in 11 cases. Four patients could not be evaluated for response. By intent-to-treat analysis, the overall RR was 44% (95% CI, 24.4%-65%). Median duration of response and median time to treatment failure were 21 and 17 weeks, respectively. The main toxicity was hematologic, with grade 3/4 neutropenia occurring in 13 patients and 1 patient developing febrile neutropenia. Two deaths from pneumonia occurred. These results reveal an encouraging activity with a reasonable toxicity profile in a patient population with an unfavorable prognosis. Our group is conducting a randomized study to compare this combination with vinorelbine alone in patients with metastatic breast cancer after failure to respond to anthracyclines and taxanes

Adult↗

PubMed2001

Tween-20 activates and solubilizes the mitochondrial membrane-bound, calmodulin dependent NAD+ finase of Avena sativa L.

Among different treatments assayed, a mix of a nonionic detergent (5% Tween-20) with 0.5 m NaCl was found to solubilize a large part of the calmodulin-dependent NAD+ kinase bound to the inner mitochondrial membrane. It also stimulated its activity by increasing 7 times the maximal velocity. Activity stimulation was also observed with phosphatidylcholine, phosphatidylethanolamine and with reductants (HSO3 and DTT). This solubilized NAD+ kinase and the calmodulin-dependent cytosoluble isoform displayed distinct molecular masses, as well as different kinetic parameters. We propose that solubilization of membrane-bound NAD+ kinase could occur in vivo in Avena sativa and could generate a soluble isoform.

Avena↗

PubMed2001

Shear-induced first-order sponge-to-lamellar transition in a lyotropic surfactant system.

We report a shear-induced sponge (L3) to lamellar (L(alpha)) transition in a surfactant system. Under a constant shear rate, after a delay time t(n) we observe random nucleation and subsequent growth of the L(alpha) phase, demonstrating that the shear-induced transition is first order. A simple argument for the energy of a two-dimensional nucleus accounts for the observed delay and its shear-rate dependence.

Journal Article↗

PubMed2001

Allogeneic peripheral blood stem cell transplantation with reduced-intensity conditioning: results of a prospective multicentre study.

Reduced-intensity conditioning (RIC) regimens for allogeneic haematopoietic stem cell transplantation (SCT) have been shown to lead to engraftment of donor stem cells without the severe extra-haematological toxicities of traditional myeloablative transplants. Between December 1998 and December 2000, 76 patients underwent a RIC peripheral blood SCT in a prospective multicentre study. The median age was 53 years, and 57 patients were beyond the early phase of their disease. The conditioning regimens consisted of fludarabine (150 mg/m2) plus melphalan (140 mg/m2) or busulphan (10 mg/kg). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporin A plus short-course methotrexate. The preparative regimens were well tolerated. All patients experienced severe pancytopenia, but haematological recovery was prompt in all but two cases (early deaths). The 100-d probability of developing grade II-IV acute GVHD was 32% (10% grade III-IV), and the 1-year probability of developing chronic extensive GVHD was 43%. Early complete donor chimaerism was observed in 52/68 patients, and 16 evaluable patients were in complete chimaerism 1 year post transplant. With a median follow-up of 283 d (355 in 48 survivors), the 1-year probability of transplant-related mortality was 20%, and the 1-year overall and progression-free survivals were 60% and 55% respectively. In conclusion, RIC regimens lead to low early toxicity after allografting, with stable donor haematopoietic engraftment, with an apparent low risk of acute GVHD. Chronic GVHD, however, develops in a significant proportion of patients.

Adolescent↗

PubMed2000

Adenoviral transduction of human 'clinical grade' immature dendritic cells enhances costimulatory molecule expression and T-cell stimulatory capacity.

The therapeutic use of dendritic cells (DC) in antigen-specific anti-tumor vaccines, requires sufficient numbers of functional DC, the preparation of which should comply with the code of Good Manufacturing Practice. In addition, the expression of tumor specific antigen should be possible in these DC. As a preclinical step, the method reported here was developed in healthy volunteers. Monocytes (Mo) were isolated by leukapheresis from 12 donors, purified by elutriation and then cultured for 6 days in sealed bags in AIM-V serum free medium with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-13 (IL-13). Between 6x10(8) and 1x10(9) immature DC (iDC) could be differentiated from one leukapheresis. Cells displayed a characteristic iDC phenotype (CD1a(+), CD14(-), CD80(+), CD86(+), HLA DR(+), CD83(-)), and had potent allogeneic and antigen dependent autologous T cell-stimulatory capacity. Moreover, iDC could be further differentiated into mature DC by CD40 ligation as assessed by CD83 expression and the upregulation of HLA-DR and costimulatory molecules. After infection with a recombinant adenovirus encoding for beta-galactosidase (betaGal), 50% to 80% of iDC expressed betaGal without toxicity. Adenovirus infection increased the expression of both costimulatory molecules and CD83, and also increased allogeneic stimulatory capacity. Thus, the method developed here allows us to use large numbers of functional iDC as will be required for therapeutic uses in man. These DC can express a transgenic protein.

Adenoviridae↗

PubMed2000

[Peripheral stem cell collection, search for predictive factors: a multicenter study. Working Group on Transfusion and Therapeutic Techniques of the French Blood Transfusion Society ].

AIMS: A multicentric study involving 12 centers was made to investigate the results of peripheral stem cell collection carried out between 1996 and 1997 from 655 patients with hemopathic syndromes or malignant tumors, The aim of this investigation was to determine the predictive factors for transplant quality, and to thereby optimize collection procedures. PATIENTS AND METHODS: Information sheets were completed for 1,346 cytapheretic sessions, i.e., 655 grafts. The samples were taken after induction chemotherapy and exposure to hematopoeitic colony-stimulating growth factors (except the LMCs). Each graft was defined as being of good or bad quality depending on the number of CD34+ cells that it contained. Based on the data available in the literature, a workgroup consensus was reached that a level of CD34+ cells +/- 2.10(6)/kg recipient body weight constituted a good transplant criterion. The 2 subgroups (good graft versus lower quality graft) were compared by univariate analysis followed by discriminant multivariate analysis. RESULTS: It was established that a number of parameters were significantly linked to the criterion of collection quality; however, 3 predictive factors emerged from the multivariate analysis--the level of circulating CD34+ cells; the number of cytaphereses; the number of blood volumes treated. CONCLUSION: It was concluded that the level of circulating CD34+ cells seems to be an essential aspect in predicting the quality of the transplant and the number of cytaphereses required to obtain a sufficiently rich collection. Moreover, it also appears that at least 2 blood volumes should be treated to optimize the results.

Adult↗

PubMed2000

Fas-mediated apoptosis of mouse embryo stem cells: its role during embryonic development.

PROBLEM: Fas antigen (APO-1/CD95) can regulate the activity of various cells during adulthood. This study aimed at determining whether Fas may also be involved in the regulation of very early events such as the embryo preimplantation stage. METHOD OF STUDY: We used mouse embryo stem (ES) cell line as a model for testing the effect of Fas crosslinking upon anti-Fas monoclonal antibody (MoAb) treatment. In addition, this treatment was also applied to in-vitro mouse-embryo culture. RESULTS: Flow-cytometry analysis of cultured ES cells demonstrated an increase in Fas expression. unchanged in the presence of mouse interleukin-2, while greatly upregulated in the presence of lipopolysaccharide (LPS). As determined by various means, ES cells may undergo a Fas-mediated apoptosis, slightly but significantly intensified by the addition of LPS to cell cultures. We also report that anti-Fas MoAb directly inhibited two-cell stage mouse-embryo (preimplantation) development in in-vitro culture conditions. CONCLUSION: These data suggest a novel mechanism controlling the regulation of physiological cell turnover as well as blastocyst implantation in early embryo development.

Animals↗

PubMed1998

[Blood volume changes caused by position under general anesthesia].

The cardiovascular changes in response to general anaesthesia are related to several interacting mechanisms. In addition to the intrinsic effects of anaesthetic agents on the heart and vessels which depress the physiological mechanisms of adaptation, the additive independent effects of posture and mechanical ventilation on intravascular blood volume have to be considered. Physiopathologic studies show that the ultimate related mechanism is the decrease of venous return to the heart. The major effect of posture is the change in the distribution of the blood volume, as the posture modifies the influence of gravity in addition to direct vascular compression and stretching. The deterioration of the cardiac venous return results in dramatic or insidious clinical consequences which lead finally to a low cardiac output. As cardiac function is not a limiting factor of output, any decrease of blood pressure in a patient with a healthy heart must be considered as an hypovolaemic state due to an abnormal contents to container ratio, and must be managed as such.

Anesthesia, General↗

PubMed1997

[Bilateral sciatica: a predictive sign of extradural hematoma after lumbar disk herniation].

The authors analyse five cases, in order to recognize a sensitive early clinical feature of extradural haematoma following lumbar diskectomy. Neither time delay (time from surgery to the suspicion of the diagnosis) nor pain intensity (a subjective factor which might be obtunded by an analgesic drug) are valuable features. The only reliable predictive sign is bilateral sciatica, which occurred in all cases, before the diagnosis was confirmed by a sensitive and motor deficit in the lower limbs.

Adult↗

PubMed1996

[Problems posed by spinal anesthesia in a patient with Gélineau disease].

A 44-year-old patient, with narcolepsy-cataplexy, underwent surgery for lumbar disk hernia under spinal anaesthesia. Our purpose was to prevent an interaction between the patient's disease and general anaesthetic agents with the risk of postoperative hypersomnia. During surgical procedure, two narcolepsy fits occurred, without clinical consequences. The postoperative course was uneventful. However, spinal anaesthesia cannot be considered as a technique of choice because of the risk of narcolepsy-cataplexy fits with loss of consciousness and atonia, during regional anaesthesia. General anaesthesia seems to be the best choice for these patients cholinergic agents and mainly the alpha1 adrenergic blocking drugs are contra-indicated as they increase the risk of narcolepsy-cataplexy fits. Anaesthetic sleep, narcolepsy, cataplexy and epilepsy are clinically rather similar. The EEG does not allow to differentiate between narcolepsy and anaesthetic-sleep, whereas cataplexy and epilepsy result in specific EEG patterns.

Adrenergic alpha-Antagonists↗

PubMed1995

Corticosteroids plus pulse cyclophosphamide and plasma exchanges versus corticosteroids plus pulse cyclophosphamide alone in the treatment of polyarteritis nodosa and Churg-Strauss syndrome patients with factors predicting poor prognosis. A prospective, randomized trial in sixty-two patients.

OBJECTIVE: To define the most effective treatment for severe polyarteritis nodosa (PAN) and Churg-Strauss syndrome (CSS) and to investigate the indication for plasma exchange treatment. METHODS: We conducted a prospective, randomized, multicenter trial in which 62 patients were randomly assigned to receive either prednisone plus cyclophosphamide (intravenous bolus) (group A; n = 28) or prednisone plus cyclophosphamide (intravenous bolus) plus plasma exchanges (group B; n = 34) as first-line treatment for severe PAN or CSS. Factors predicting poor prognosis were renal symptoms, gastrointestinal tract involvement, cardiomyopathy, central nervous system involvement, weight loss > 10% of body weight, and age > 50 years old. Patients with hepatitis B virus-related PAN were not included in this study. The end point of the study was control of the disease (recovery or remission) or death. RESULTS: Clinical symptoms and laboratory findings did not differ significantly in the 2 groups. Initial control of the disease was similar in both groups. Relapse after initial control of the disease was observed in 7 patients (4 in group A and 3 in group B). The mean +/- SD followup period was 31.1 +/- 20 months for group A and 35.9 +/- 16.8 months for group B. At 5 years of followup, 38 patients (61.3%) were cured (16 in group A and 22 in group B), and 5 (8.1%) were in remission without treatment but had not yet completed the cure-defining period of 18 months (3 in group A and 2 in group B). Eight (12.9%) (2 in group A and 2 in group B) were considered to be in clinical remission and required a maintenance regimen of low-dose corticosteroids. Eleven patients died during the study period (7 in group A [25%], 4 in group B [11.8%]). Uncontrolled vasculitis was responsible for 4 deaths (2 in each group), and treatment side effects caused the death of 1 patient in group A. There was no significant difference between the 5-year cumulative survival rates of the 2 groups (75% and 88%, respectively). CONCLUSION: Based on our data, combined treatment with prednisone, cyclophosphamide, and plasma exchanges is not superior to treatment with prednisone and cyclophosphamide alone, and plasma exchanges should not be systematically proposed for initial treatment of severe PAN or CSS.

Adolescent↗

PubMed1994

Pharmacokinetics of ceftriaxone during plasma exchange in polyarteritis nodosa patients.

Plasma exchange (PE) is currently being used to treat a variety of disorders involving immune complexes, such as polyarteritis nodosa. This procedure removes endogenous toxic components that accumulate in patients with this disease, but it also removes drugs. Plasma-protein binding and the volume of distribution (V) are two kinetic parameters which strongly affect the efficiency of drug removal by PE. Drugs that are highly bound to plasma proteins and have a low V may show a marked decrease in plasma levels as a result of PE. Because ceftriaxone exhibits saturable plasma-protein binding, which influences its pharmacokinetic parameters, particularly its V, we evaluated its removal during PE therapy in this nonrandomized crossover study. Twelve polyarteritis nodosa patients undergoing PE were studied. Each patient was given ceftriaxone intravenously in doses of 1 and 3 g on days 4 and 11, respectively, immediately before (n = six patients; group I) and 6 h before (n = six patients; group II) PE. Plasma was assayed for ceftriaxone by high-pressure liquid chromatography. The mean amounts eliminated +/- standard deviations were 230.8 +/- 38.5 mg (1 g) and 750.0 +/- 168.5 mg (3 g) for group I and 161.0 +/- 66.0 mg (1 g) and 347.0 +/- 121.0 mg (3 g) for group II. The drug fractions eliminated by PE were 23.0% +/- 3.9% (1-g dose) and 24.9% +/- 5.6% (3-g dose) for group I (P > 0.05), and 16.6% +/- 5.9% (1-g dose) and 11.5% +/- 4.0% (3-g dose) for group II (P < 0.05). These results showed that the drug fraction eliminated decreased when V increased only when the distribution phase of ceftriaxone had been completed (group II). These findings suggest that PE may influence ceftriaxone disposition and that it would be better to administer the drug after PE to assure its therapeutic efficacy.

Adult↗

PubMed1994

[Anesthesia for lithotripsy].

Extracorporeal shock wave lithotripsy has become the standard method of treating renal stone disease. The appropriate choice of anaesthetic technique depends on the shock wave technic mode. Recent modifications of lithotriptors have reduced the physiological consequences of the procedure and most often these treatments can be performed without local or general anaesthesia. However, some sedation/analgesia may be necessary and a good knowledge of anaesthesia for lithotripsy remains most useful so as to meet any particular requirements.

Ambulatory Surgical Procedures↗

PubMed1994

Long-term plasma exchange. Analysis of indications, outcome and side effects.

In order to determine the characteristics and the course of diseases treated with long-term plasmapheresis (e.g., more than 25 plasma exchanges), we retrospectively studied 850 patients who underwent plasmapheresis. Long-term plasma exchange was prescribed to 38 patients who failed to respond to conventional therapy; cryoglobulinemias, peripheral neuropathies and monoclonal gammopathies were their most frequent underlying diseases. Improvement was noted in 65.8% cases. Only minor side effects were observed and the risk/benefit ratio for such therapy was excellent.

Adult↗

PubMed1993

[Synchronization of plasma exchange and cyclophosphamide in severe systemic diseases. A consecutive study of 10 patients].

Ten patients with severe systemic diseases, including systemic lupus erythematosus (n = 2), polymyositis (n = 2), essential mixed cryoglobulinaemia (n = 2), rheumatoid arthritis vasculitis (n = 3) and Wegener's granulomatosis (n = 1), were treated with 3 consecutive plasma exchanges synchronized with pulse cyclophosphamide. This therapeutic regimen was applied every 4 weeks initially and thereafter every 6 weeks in case of positive response after the first 3 cycles; it was combined in all patients with corticosteroid therapy. The treatment was administered for severe flare-up of the disease in 7 patients and for failure of previous treatments, including corticosteroids, cyclophosphamide and plasmapheresis, in 3 patients. Three kinds of response were observed: lasting complete remission without relapse after synchronization had ceased in 4 patients, partial clinical remission with post-synchronization relapse in 5 patients, and primary failure without any clinical response to treatment in only 1 patient. These results suggest that repeated plasma exchanges synchronized with cyclophosphamide are effective against progressive autoimmune diseases and in cases where conventionally administered immunosuppressive treatments had failed. However, this type of treatment cannot prevent long-term relapses, and only a prospective study can evaluate its success in terms of survival.

Adult↗

PubMed1993

Endotoxin-induced tissue factor messenger RNA in human monocytes is negatively regulated by a cyclic AMP-dependent mechanism.

Tissue factor (TF) is a transmembrane receptor that serves as the major cofactor for factor VIIa-catalyzed proteolytic activation of factors IX and X. In response to bacterial lipopolysaccharide (LPS), monocytes transcribe, synthesize, and express TF on their surface, thereby conveying to activated monocytes the ability to initiate the blood coagulation protease cascades. Agents that elevate cellular cyclic AMP (cAMP) inhibit the functional expression of TF by LPS-stimulated monocytes. In this study, we investigated the mechanism of this suppression. Northern blot analysis of total RNA from LPS-stimulated monocytes showed a concentration-dependent decrease in TF messenger RNA (mRNA) levels in response to dibutyryl-cAMP (dBt-cAMP). TF mRNA and procoagulant activity were inhibited as early as 1 hour after the addition of dBt-cAMP and the inhibition persisted through 4 hours. Suppression of specific mRNA abundance was also observed with agents, including forskolin and iso-butyl-methyl-xanthine (IBMX), that increase cAMP levels by independent mechanisms. Flow immunocytometric analysis confirmed that cell-surface TF protein levels declined in parallel with TF functional activity. The rate of decay of TF mRNA after the arrest of transcription by actinomycin D was not altered by the addition of dBt-cAMP, IBMX, or forskolin, thus excluding effects on TF mRNA stability. We conclude that elevated cAMP levels suppress TF mRNA by reducing the rate of TF gene transcription.

1-Methyl-3-isobutylxanthine↗

PubMed1993

[Intraoperative posture in the surgery of lumbar disk hernia].

For surgery of the lumbar disc, with a posterior route, the patient is placed either in a prone, or a knee-chest, or a lateral position. They aim at facilitating the surgical access in decreasing local bleeding and collapsing the dural sheath. This benefit, as a result of the maintenance of the pressure in the epidural venous system at a low level, is obtained through the absence of any abdominal compression as well as the posture. In the prone position, the abdominal compression and the increase of the physiologic lordosis impair the systemic venous return and carry the risk of cardiac arrest. In addition to these adverse effects, the conventional knee-chest position increases the haemodynamic repercussions in modifying the distribution of blood volume and increasing the potential risk of mediastinal compression and air embolism. The lateral position generates only minor haemodynamic modifications, except in the obese. However it is difficult to stabilize the patients' position and to maintain the alignment of the spine. Therefore it is used the less one. The postural risks of all three positions are numerous and include mainly the compression of nerves, vessels and skin. Finally the selection of the position depends basically on morphological criteria and the adaptative capacities of the patient. The optimal position is the one offering a low pressure level in the spinal venous system, while maintaining the venous return.

Anesthesia, General↗

PubMed1992

Pharmacokinetics of vidarabine in the treatment of polyarteritis nodosa.

The pharmacokinetics of vidarabine were studied in 8 patients with polyarteritis nodosa related to hepatitis B virus infection. The drug was administered by continuous infusion for three weeks at doses of 15 (1 week) and 7.5 (2 weeks) mg/kg per day, during which time 15 plasma exchanges were performed. Plasma was assayed for vidarabine and its principal metabolite, hypoxanthine arabinoside by high pressure liquid chromatography. Vidarabine was not detected in the plasma of any patients. Hypoxanthine arabinoside levels were used to evaluate vidarabine kinetics. The serum levels of hypoxanthine arabinoside ranged from 3.6 to 21.5 mg/l. The mean elimination half-life (+/- SD) was 3.0 +/- 1.7 h. The plasma clearance (mean +/- SD) was 195 +/- 270 ml/min when the dose was 7.5 mg/kg per day and 66.3 +/- 47 ml/min for a 15 mg/kg per day/dose (NS). Except for the elimination half-life, these results were not fully consistent with those observed in other studies. The influence of multiple plasma exchanges on vidarabine kinetics is limited and dosage adjustment is not required based on the continuous infusion of vidarabine.

Humans↗