Biomedical subjects

C René

Publications and source records attributed to C René.

4 recordsLinked to original sources

PubMed2006

Update on orbital anatomy.

The orbit is a confined space bounded by four bony walls. Apart from the globe, orbital fat, and extraocular muscles it contains many important neurovascular structures. It is intimately related to the paranasal sinuses as well as the anterior and middle cranial fossae. Consequently, sinus pathology and intracranial disease may spread to involve the orbit and the converse applies. A thorough understanding of orbital anatomy is essential to fully appreciate the effects of disease on the orbit and is of paramount importance for performing safe orbital surgery. The anatomy of the orbit is discussed with reference to relevant orbital disease.

Cranial Nerves↗

PubMed2001

Interactions between carbamazepine and polyethylene glycol (PEG) 6000: characterisations of the physical, solid dispersed and eutectic mixtures.

The influence of a hydrophilic carrier (PEG 6000) on the polymorphism of carbamazepine, an antiepileptic drug, was investigated in binary physical mixtures and solid dispersions by means of differential scanning calorimetry (DSC), thermal gravimetry, hot-stage microscopy (HSM), and X-ray diffractometry, respectively. This study provides also an attempt to develop a method to calculate more precisely the eutectic composition. In rather ideal physical mixtures, carbamazepine was found as monoclinic Form III. In solid dispersions, the drug was found to crystallize as trigonal Form II; a eutectic invariant in the PEG 6000-rich composition domain (6% of carbamazepine mass) was evidenced by DSC experiments and confirmed by HSM observations. In the binary phase diagram the ideal carbamazepine liquidus curve was located at temperatures higher than the respective experimental ones. This suggests that drug can be maintained in the liquid state in the temperature-mass fraction (T--x) region between the two carbamazepine liquidus curves. This indicates in turn that attractive interactions occur between carbamazepine and PEG 6000-chains. These interactions have been also claimed to prevent carbamazepine from degradation into iminostilbene (a compound resulting from the chemical degradation of carbamazepine which is postulated to be responsible for the idiosyncratic toxicity of the drug) and thought to lead to the crystallization of metastable Carbamazepine II from melt. The negative excess entropy for eutectic mixtures indicated that the drug crystals are finely dispersed in the bulk of polymer chains.

Anticonvulsants↗

PubMed1993

[Ultradian variations of interleukin-1 beta concentration (IL-1 beta), interferon gamma (IFN-gamma) and soluble IL-2 receptors (RIL-2) in healthy volunteers humen].

The aim of this study consisted in underlining the concentrations' evolution in time of two cytokines: IL-1 beta and IFN-gamma, as well as that of RIL-2 (soluble receptor for IL-2), in healthy volunteers. Under normal physiological conditions, these molecules are secreted in small amounts, according to a sequential chronology. Thus, 25 blood samples were carried out from each of the four subjects included in the study, one every 20 minutes, during 8 hours. Concentrations were determined with the ELISA method. Spectral analysis was carried out using the Frequencies Spectrum method (Fourier Transform of a temporal series). This method allows a rhythm search over a milited number of values, in a short interval of time, provided having enough samples. Important variabilities have been observed between all subjects sera, particularly for IL-1 beta (Range (mean +/- SD): 132 +/- 34.6 pg/ml to 250 +/- 17.5 pg/ml, one subject had low values: 2.34 +/- 0.53 pg/ml) and RIL-2 (Range: 677 +/- 175 pg/ml to 1,187 +/- 46.2 pg/ml). Furthermore, ultradian serum variations, characterized by the relation ((Cmax-Cmin)/Cmax) x 100, have been assessed for each subject and each molecule: IL-1 beta (Range: 18.9 to 92.2%), IFN-gamma (Range: 66.3 to 74.2%) and RIL-2 (Range: 11.6 to 86.3%); they might be the manifestation of a periodicity; this hypothesis has been confirmed by the spectral analysis. Thus, the concentrations' variation with time showed a periodicity (Range: 80 mn to 240 mn, the most frequent period was 160 mn (2 h 40 mn)).

Activity Cycles↗

PubMed1989

[Prevention of cisplatin nephrotoxicity in cancer: adjusting the dosage with a computerized chrono-pump].

Platinum and its derivates are particularly efficient in treatment of ovarian and testis carcinomas. Nevertheless, the high nephrotoxicity of these drugs limits their use. It is known that nephrotoxicity appears when platinum plasmatic concentrations are higher than 1.5 mg/l. Moreover, the wide variability between patients and between cures, emphasizes the difficulties of utilization. Using a computerized pump and a program for individual dosage regimen, an efficient prevention of plasmatic overdosages have been realised and nephrotoxicity accidents have been avoided.

Aged↗