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Biomedical subjects

J M Leger

Publications and source records attributed to J M Leger.

At least 19 recordsLinked to original sources
PubMed2005

Electrochemical and optical characterization of p- and n-doped poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene].

We study electrochemical p- and n-type doping in the well-known light-emitting polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). Doping reactions are characterized using cyclic voltammetry. Optical measurements including photoluminescence and UV/Vis/NIR transmission were performed on doped samples. We find that oxidation in MEH-PPV is a highly reversible reaction resulting in stable freestanding doped films, while the reduced form is unstable and the reaction irreversible. We discuss the dependence of doping reactions on scan rate, film thickness, salt type and concentration, and working electrode type. We observe the development of two additional broad absorption bands in both lightly and heavily doped films accompanied by a slight blueshift in the primary optical transition, suggesting bipolaron band formation. Finally we find that both p and n dopings result in extremely sensitive photoluminescence quenching. We propose a physical model for understanding electrochemical doping in MEH-PPV and the implications this has on the development of such technologies as polymer light-emitting electrochemical cells, electrochromic devices, actuators, and sensors.

Journal Article↗
PubMed2005

Enantioselective synthesis of 2- and 3-substituted 2,3-dihydro[1,4]dioxino[2,3-b]pyridine derivatives and enantiomeric purity control by capillary electrophoresis.

A rapid and simple procedure for enantioselective preparation of 2- and 3-substituted 2,3-dihydro[1,4]dioxino[2,3-b]pyridine derivatives (A and B, respectively) is described. The enantiomeric purity of each isomer was determined by capillary electrophoresis using a dual-cyclodextrin system (S-beta-CD/beta-CD) dissolved in formic acid-ammonia buffer (pH 4, ionic strength 50 mM).

Electrophoresis, Capillary↗
PubMed2002

Anterior interosseous nerve and multifocal motor neuropathy.

We report the case of a 47-year-old woman with a left anterior interosseous nerve palsy. Surgical release of the anterior interosseous nerve was initially proposed, but electrodiagnostic evaluation demonstrated that the neuropathy was due not to compression or to neuralgic amyotrophy but to a proximal conduction block. At that time, the conduction block could be defined only by indirect electrodiagnostic criteria. A multifocal motor neuropathy with persistent conduction block was subsequently diagnosed, and the patient was treated with intravenous immunoglobulins. The efficacy of this treatment and the subsequent disclosure of conduction block in the right posterior interosseous and peroneal nerves definitively confirmed the multifocal motor neuropathy.

Female↗
PubMed2000

Physicochemical and crystallographic evidence for polymorphism of the racemic ethyl (2-chloromethyl-2,3-dihydro-5H-oxazolo [3, 2-a]pyrimidin-5-one)-6-carboxylate.

The various crystalline forms of an original bicyclic compound [ethyl (2-chloromethyl-2,3-dihydro-5H-oxazolo[3, 2-a]pyrimidin-5-one)-6-carboxylate); EOC] have been obtained and characterized by powder and single-crystal X-ray diffraction, differential scanning calorimetry (DSC), and infrared (IR) and Raman spectroscopy. At 4 degrees C in methanol, a monoclinic racemate (form II) crystallized from the racemic mixture, whereas at 20 degrees C, an orthorhombic racemate (form I) was isolated in trichloroethylene. By increasing the temperature, a solid-solid transition from the stable form II to the stable form I was observed with a Guinier-Simon camera. A I --> II transformation was observed at ambient temperature by DSC.

Crystallography, X-Ray↗
PubMed2000

Synthesis of diaryl-substituted imidazo[l,2-a]pyridines designed as potential aromatase inhibitors.

From a pharmacophore model of bicyclic heterocycles as aromatase inhibitors we have designed three series of imidazo[1,2-a]pyridine derivatives. The synthesis and the spectroscopy determination of various compounds are reported. The crystal data of one of these compounds (10b) was obtained. The aromatase inhibition potency was evaluated in vitro and no activity was found.

Aromatase Inhibitors↗
PubMed1999

Detection of depression in elderly hospitalized patients in emergency wards in France using the CES-D and the mini-GDS: preliminary experiences.

OBJECTIVE: The purpose of this study was to evaluate the mini-GDS and the CES-D as instruments to detect depression in elderly hospitalized patients in emergency wards in France. METHODS: The CES-D was used on two cohorts of 60 non-cognitively impaired patients aged 70 or more. The mini-GDS was also used on the second of the two cohorts administered by a medical intern. These ratings were compared with a diagnosis of depressive disorder by ICD-10 criteria. RESULTS: The study population had a high (58%) prevalence of depression and a low level of active psychiatric referral. Mini-GDS and CES-D scores were well correlated (0.72, p < 0.001); the mini-GDS, with a cutoff score of 1, gave optimum sensitivity (88%) and specificity (63%). CONCLUSION: The use of the mini-GDS may aid the detection of depression in patients in emergency wards.

Aged↗
PubMed1999

[Cryoglobulinemia and hepatitis c: worsening of peripheral neuropathy after interferon alpha treatment].

We report 4 cases of peripheral neuropathy induced by type II IgM kappa mixed cryoglobulinemia associated with hepatitis C virus infection. Worsening of peripheral neuropathy was observed 2 to 13 weeks after the initiation of interferon. The evolution of the hepatic and neurological diseases did not coincide, as all patients decreased or normalized transaminases with interferon. After stopping interferon, peripheral neuropathy worsened (1 case), stabilized (1 case), improved (2 cases). Low doses of interferon alpha may cause worsening of peripheral neuropathy in patients with hepatitis C virus infection associated with mixed cryoglobulinemia.

Aged↗
PubMed1997

Efficacy of amineptine in the prevention of relapse in unipolar depression.

The clinical properties of amineptine, a mainly dopaminergic antidepressant, were assessed in a double-blind controlled study involving patients fulfilling Diagnostic and Statistical Manual of Mental Disorders (DSM-III) criteria for unipolar depression. The aim was to determine how relapses could be prevented in this frequently recessing disorder. The study was a two-phase, 12-month, multicentre trial of patients suffering from major depression or dysthymia, diagnosed using DSM-III criteria and evaluated on the Montgomery-Asberg Depression Rating Scale and the Mood, Anxiety, Retardation, Danger scale. Phase I was an open-label 3-month period, with the patients being given 200 mg amineptine per day. The second, 9-month period was a placebo-controlled prophylactic phase. A total of 458 patients were initially included in the study. Of the 376 who completed phase I, 303 (66%) were responders; 284 entered the prophylactic study, randomly assigned to two groups. Of the 134 patients in the placebo group who completed phase II, 25 (18.7%) suffered a relapse, compared with nine out of the 136 (6.6%) in the amineptine group. After resolution of an acute episode of major depression or dysthymia, long-term antidepressant therapy with amineptine significantly reduced the relapse rate.

Adult↗
PubMed1997

A randomised clinical trial comparing interferon-alpha and intravenous immunoglobulin in polyneuropathy associated with monoclonal IgM. The IgM-associated Polyneuropathy Study Group.

OBJECTIVES: The polyneuropathy associated with a monoclonal IgM directed to the myelin associated glycoprotein (MAG) is a specific entity with a putative causal link between the IgM and the neuropathy. The small benefit offered by alkylating agents or plasma exchanges in these patients justifies the search for alternative treatments. METHODS: A 12 month multicentre, prospective, randomised, open clinical trial was carried out comparing intravenous immunoglobulin (IVIg; 2g/kg and then 1 g/kg every three weeks) and recombinant interferon-alpha (IFN-alpha; 3 MU/m2 subcutaneously three times weekly). The main end point was a clinical neuropathy disability score (CNDS) after six months of treatment. Twenty patients were enrolled; 10 were assigned to IVIg and 10 to IFN-alpha. RESULTS: At six months, one out of 10 patients treated with IVIg had a CNDS improvement of more than 20% whereas eight out of 10 patients treated with IFN-alpha had such an improvement (P=0.005). The mean CNDS worsened by 2.3 (SD 7.6) (8%) in the IVIg group whereas it improved by 7.5 (SD 11.1) (31%) in the IFN-alpha group (P=0.02). This improvement persisted after 12 months and was mainly related to an improvement of the sensory component (P=0.02) whereas the motor component was unchanged (P=0.39). Electrophysiological data did not show improvement of motor nerve conduction velocities whereas sensory nerve conduction velocities improved in the upper limbs. A decrease in the level of the monoclonal IgM was seen in two patients treated with IFN-alpha. At the end of the treatment, antibody activity to MAG was still detected in the serum of all patients. CONCLUSION: IVIg, as used in this study, did not improve patients with polyneuropathy and monoclonal IgM. By contrast, although its mechanism of action remains to be fully elucidated, IFN-alpha was effective in eight out of 10 patients at six months.

Adult↗
PubMed1994

Mixed cryoglobulinemia and hepatitis C virus.

BACKGROUND: Mixed cryoglobulinemia (MC) is frequently associated with clinical and biological evidence of liver disease and has recently been reported in cases of hepatitis C virus (HCV) infection. The aim of this study was to assess prospectively in a large series of MC patients: (1) the prevalence of HCV markers (anti-HCV antibodies and HCV RNA in serum and cryoprecipitate); (2) the main clinical, biologic and liver histologic features in patients with or without HCV infection. PATIENTS: One hundred fifteen consecutive unselected MC patients were studied: 45% had well-defined underlying diseases ("nonessential" MC). Fifty-five percent with no cause of MC were considered to have "essential" MC and were subjected to in-depth examination. METHODS: Patients were considered to have MC if two successive determinations of their serum cryoglobulin level were above 0.05 g/L. Anti-HCV antibodies (Ab) were detected in all patients by second-generation tests (ELISA, RIBA). We also looked for HCV RNA sequences amplified by polymerase chain reaction (PCR) in the sera and cryoprecipitates of 39 patients; HBs antigen, anti-HBs Ab and anti-HBc Ab in all patients; and HBV DNA in 20 sera and 17 cryoprecipitates. Quantitative HCV Ab and RNA studies were performed on whole serum, cryoprecipitates, and supernatants. Clinical features were recorded retrospectively for each patient. Liver biopsies from 23 anti-HCV Ab-positive and 7 anti-HCV Ab-negative patients were examined histologically, with qualitative and quantitative analysis. RESULTS: Anti-HCV Ab were found in 47/115 (41%) patients by ELISA and RIBA: 33/63 (52%) essential MC and 14/52 (27%) nonessential MC. Among the 63 essential MC patients, the 33 anti-HCV Ab-positive (Group 1) were compared to the 30 anti-HCV Ab-negative patients (Group 2). Group 1 patients had more cutaneous involvement (Raynaud's phenomenon, purpura, livedo, distal ulcers, or gangrenous changes) (17 versus 5: p = 0.004), higher alanine aminotransferase levels (110 +/- 22 versus 41 +/- 10 IU; p < 0.005), higher serum cryoglobulin levels (0.35 +/- 0.07 versus 0.12 +/- 0.04 g/L; p = 0.01), lower CH50 (28 +/- 3 versus 44 +/- 2 CH50/mL; p = 0.0001) and lower C4 levels (0.20 +/- 0.02 versus 0.29 +/- 0.03 g/L; p < 0.04). The prevalence of HBV serum markers was low in both groups, and HBV DNA was never detected in any of the sera and cryoprecipitates tested. HCV RNA sequences were detected in 10/16 (63%) sera and 12/16 (75%) cryoprecipitates from Group 1 patients, whereas they were not in the sera or cryoprecipitates from 23 Group 2 patients. Using quantitative PCR, HCV RNA in cryoprecipitates was concentrated 20 to 100 times despite the absence of significant anti-HCV Ab concentration in these samples. Histologic examination of liver biopsies revealed a spectrum of lesions ranging from chronic active hepatitis to cirrhosis, but Knodell's score did not differ between the groups. CONCLUSION: (1) About 50% of the essential MC patients had anti-HCV Ab, and these patients had more severe cryoglobulinemia-associated clinical and biological signs; (2) HCV RNA sequences were found in the large majority of sera and cryoprecipitates from patients with essential MC and anti-HCV Ab and were more concentrated in cryoprecipitates than in supernatants. These results suggest a role for HCV in the pathogenesis of MC and indicate that many cases of essential MC may be secondary to HCV infection and thus nonessential.

Adult↗
PubMed1994

Human immunoglobulin treatment of multifocal motor neuropathy and polyneuropathy associated with monoclonal gammopathy.

Intravenous human immune globulin (IVIg) has been proposed for the treatment of various peripheral neuropathies that are considered to be immunemediated. The results are reported of an open trial conducted in multifocal motor neuropathy and polyneuropathy associated with monoclonal gammopathy. Six cases with multifocal motor neuropathy, selected on clinical and electrophysiological criteria (four of six patients also had significantly high anti-GM1 titres), received IVIg monthly, at doses varying from 1.6 to 2.5 mg/kg, over three to 13 months. The initial response to treatment was dramatic in 3/6 cases (with improvement of at least two grades on the MRC scale in the five more severely affected muscles). The final evaluation showed a good result in 4/6 cases, but the conduction blocks were not significantly reduced. In 13 other cases with polyneuropathy associated with IgM monoclonal gammopathy of unknown significance, IVIg was of benefit, with improvement of at least one grade on the Prineas score, in 4/7 cases previously treated with immunosuppression and 2/3 cases not treated before IVIg. In the last group of four patients with polyneuropathy and IgG monoclonal gammopathy, IVIg was followed by clinical improvement in the two cases with a chronic demyelinating polyneuropathy.

Humans↗
PubMed1994

Indolent anti-Hu-associated paraneoplastic sensory neuropathy.

Paraneoplastic sensory neuropathy (PSN) usually runs a subacute progressive course, leaving the patient with severe sensory dysfunction in weeks to months. We describe five patients with PSN, high titers of anti-Hu antibodies (type 1 antineuronal nuclear autoantibodies), and an indolent clinical course. The patients had a median age of 55 years (range, 41 to 72). Four had small-cell (3) or undifferentiated large-cell (1) lung cancer. Patients presented with mild, asymmetric sensory symptoms; in two, the neuropathy was predominant in the arms. Two patients also had a visceral neuropathy causing gastrointestinal dysfunction. The PSN was stable or progressed very slowly without treatment for a median of 18 months (range, 5 to 32) and remained so after treatment with immunoglobulins (1 patient), chemotherapy (3), or both therapies (1). All patients were ambulatory, leading an independent life up until the time of the last visit or until death from the tumor (2 patients). The median follow-up was 36 months (range, 22 to 52). A paraneoplastic origin should be considered in patients with mild, very slowly progressive sensory neuropathies.

Adult↗
PubMed1993

Asymptomatic cerebral involvement in Sjögren's syndrome: MRI findings of 15 cases.

Fifteen patients with Sjögren's syndrome without clinical evidence of central nervous system disease were studied by MRI. Signal abnormalities were observed in 9 (60%). They were always visible on T2-weighted images as small punctate areas of high signal in the basal ganglia and the white matter of the cerebral hemispheres. Abnormalities were less frequently seen on T1-weighted images. Enlargement of cerebral sulci was observed in 6 cases. The specificity and significance of these abnormalities are discussed.

Adult↗