Isolation impairs place preference conditioning to morphine but not aversive learning in mice

Morphine (8–100 mg/kg IP) induces place preference conditioning in mice. The effect of two different periods of isolation (15 and 30 days) was examined. Mice isolated for 15 days but not 30 days exhibited place preference conditioning to morphine (8 mg/kg). After 30 days of isolation morphine could not induce place preference conditioning with the following doses (8, 16, 64, 100 mg/kg). Social regrouping of male mice previously isolated for 30 days with naive female mice for 15 or 30 days resulted in a reappearance of the conditioned place preference to morphine (16 mg/kg). The specificity of this associative deficit was examined by testing learning in isolated compared to non-isolated mice in two distinct settings: escape learning in the Morris water maze and passive avoidance acquisition and retention. On the Morris water maze isolated mice did not differ from non-isolated mice regarding place learning, the probe trial or extinction. Isolated mice were unimpaired in passive avoidance acquisition and retention. It was concluded that the deficits in place preference conditioning were not the result of a global learning impairment in isolated mice. Received: 10 April 1996 /Final version: 20 September 1996     

Separation of two different populations of granulocytes of Nereis diversicolor (Annelida) by selective agglutination with lectins

Methods for obtaining coelomocyte populations from Nereis diversicolor by selective agglutination have been developed. Two main types of granulocytes have been successfully separated and recovered using respectively galactose and fucose specific lectins. 85 to 90% of the separated cells were viable.     

Effects of different cellulose derivatives on drug release mechanism studied at a preformulation stage.

As a matter of fact, in vitro dissolution is well known to be the method of choice for the pharmaceutical industry to develop effective medicines. However, many experiments must be performed all along a new product life and they represent an overcharge of work for researchers. The purpose of this paper was to assess the relevance of new parameters obtained during preformulation stage by Nuclear Magnetic Resonance (NMR) experiments to better understand drug release mechanism. This study was carried out with three cellulose derivatives currently used as carrier matrices (Microcrystalline cellulose (MCC), Hydroxypropylmethyl cellulose (HPMC) and Ethyl cellulose (EC)). Granules and tablets were produced with these three excipients (60% w/w) and theophylline as drug model (40%). On the one hand, in vitro dissolution studies were performed with the rotating paddle method displaying the different release behaviour of these three matrices (immediate release for MCC, steady release for HPMC and sustained release for EC). On the other hand, the evolution of the T2m spin-spin relaxation time in NMR experiments during granules hydration was recorded. NMR findings shore up dissolution data, both depending on interactions between the matrix and water. NMR spectroscopy appears to be a valuable tool for obtaining, at an earlier stage of drug development, more information about drug release mechanism.     

Laser tomography of heterogeneous scattering media using spatial and temporal resolution

Time-resolved tomography is performed in transillumination by using 527 nm picosecond pulses from a passively mode-locked doubled Nd/glass laser and a streak camera to select photons according to their flight time. This work reports on the increase in contrast of a time-resolved profile of a 2 mm radius opaque object embedded in a scattering medium, constituted of diluted milk in a 30 mm thick cell. For spatial analysis, the emerging photons are detected through a 6 mm slit at the outlet face of the cell. Transmission profiles obtained as a function of time show that the contrast is enhanced for the shortest flight times, while the ‘shadow’ of the object is no longer detected after about 100 ps. Moreover, improvements in contrast are studied for different configurations of the model, to analyse separately the role of collimated and scattered photons. It is expected that such a tomographic method based on time-resolved absorption could be applied to imaging for more complex biological structures in the red and near-infra-red range.     

Failing arteriovenous hemodialysis fistulas: assessment with magnetic resonance angiography

RATIONALE AND OBJECTIVES: The authors sought to evaluate prospectively magnetic resonance angiography (MRA) versus fistulography in the detection and characterization of complications associated with malfunctioning hemodialysis access fistulas (arteriovenous fistulas [AVF]). METHODS: Nineteen patients with clinical AVF dysfunction were studied by MRA and fistulography. Data from each study were collected prospectively and analyzed in a blinded manner. RESULTS: The main diagnosis was stenosis in eight patients, thrombosis in five patients (mural thrombosis with preserved flow in one), aneurysm without stenosis in two patients, and normal AVF in four patients. A hazy flow void, assumed to be related to turbulence, was observed in normal arterial anastomoses. When flow void was considered as a criterion of stenosis or thrombosis, one false-positive and one false-negative MRA study were determined, yielding a sensitivity and specificity of 92% and 86%, respectively. CONCLUSIONS: Magnetic resonance angiography is a feasible and sensitive technique with which to portray suspected malfunctioning hemodialysis access fistulas.     

Plants from new caledonia: alkaloids of stem-bark of Hernandia cordigera

The alkaloidal content of of the stem barks of Hernandia cordigera has been studied and compared to that of other Hernandia species. Main alkaloids are phenolic aporphines.     

Renal carcinoma: diagnosis of venous invasion with Gd-enhanced MR venography

The aim of this study was to evaluate the usefulness of gadolinium-enhanced time-of-flight magnetic resonance venography (MRV) in the diagnosis of bland thrombosis/tumoral invasion in the preoperative assessment of renal cell carcinoma. Preoperative precontrast and enhanced GRE fast low-angle shot (FLASH) images of 36 patients with renal adenocarcinoma were reviewed and compared with pre- and post-contrast T1-weighted images. All patients underwent surgery, and MR findings were blindly and prospectively compared with surgical and pathologic data, considered the standard. Renal vein and vena cava were involved in 17 and 9 patients, respectively; right atrial extension was present in one patient. Precontrast spin-echo (SE) and FLASH images were 88 % sensitive and 100 % specific in the detection of venous involvement, respectively, and enhanced FLASH images 100 % sensitive and 96 % specific. The nature of thrombus (neoplastic or bland) was more accurately assessed (McNemar's, p < 0.05) with FLASH-enhanced MR images (sensitivity 89 %; specificity 96 %) than with SE and precontrast FLASH images (sensitivity 79 %; specificity 94 %). Our data suggest that use of Gd-enhanced MRV might improve preoperative assessment of vascular involvement in renal carcinoma. Received: 7 September 1999; Revised: 26 November 1999; Accepted: 26 November 1999