PubMed Health⌕ Search

Biomedical subjects

A Decker

Publications and source records attributed to A Decker.

At least 19 recordsLinked to original sources
PubMed2001

Microarray-based analysis of gene expression in very large gene families: the cytochrome P450 gene superfamily of Arabidopsis thaliana.

Cytochrome P450 (P450s) are heme-thiolate protein products of a very large gene superfamily, present in all kingdoms and involved in a variety of metabolic reactions. P450s are classified according to the degree of amino acid sequence identity, with P450s of the same family defined as having >40% identity, and P450s of the same subfamily having >55% identity. Currently, 273 P450 genes distributed over 45 families have been identified in Arabidopsis, and its genome is estimated to contain as many as 286. Genome-wide DNA microarrays make it possible to broadly correlate P450 gene activity with alterations in physiological or developmental states. A potential problem with microarray research is that sequence similarity between and within these families of closely related genes may lead to cross-hybridization. We designed experiments to systematically evaluate the specificity of P450 microarrays, and showed that conditions could be optimized to provide a very high degree of hybridization specificity. Under these conditions, and employing a 20% intensity value of maximum hybridization intensity as a cut-off, labeled P450 genes exhibited essentially no cross-hybridization between families and within subfamilies. We also compared the gene transcription levels of microarray probes derived from EST clones and from genomic DNA sequences for which ESTs were not available, using cDNA produced from RNA from various Arabidopsis tissue as the target. Many of the P450 genes displayed tissue-specific expression, leading to hypotheses as to the function of individual genes and their regulation. We also observed that several of the genomic sequences reported high levels of expression, highlighting the limitations of expression analysis based on ESTs alone.

Arabidopsis↗
PubMed2000

[Mechanics of palatal expansion in the occlusal plane].

The mechanics of a transpalatal arch in the occlusal plane (symmetrical V-bends, asymmetrical V-bends and step-bends) is studied through four methods: simulation of the teeth movements with a typodont, measure of the forces and the moments with a mechanical system composed of pulleys and dead load devices, photo-elastic stress analysis, finite element stress analysis. Typodont experimentations display the dental movements: the easiest one is rotation; it is more difficult to observe distalization and mesialisation that occur with a version of the tooth. An experimental apparatus, composed of pulleys and dead load devices, allows to measure forces and moments released by a transpalatal arch, depending on the level of the activations. The authors notice that the distalization force for an asymmetrical V-bend activation is low, about 0.2 Newton for 5 degrees of activation. Photo-elastic stress analysis affords a visualization of the shear stresses induced by a transpalatal arch within the supporting structures of a root, thanks to the observation of colored fringes in a model constituted with two molars included in a birefringent resin. Meanwhile, the manipulation of the photo-elastic resin is not easy and the interpretation of the results remains difficult. The finite element method is a numerical analysis and consists in the fragmentation of the studied structure in a certain number of elements, where forces and moments can be applied: the three dimensional program analyses the stress and strains in these elements. Thus, we can: 1.--visualize strains and stresses of a transpalatal arch, when it is inserted in the lingual molar sheaths; 2.--observe the dental movements due to the activations of the transpalatal arch (rotation, version, mesialisation, distalization); 3.--study the stress induced in the periodontal tissue. The results of these studies are complementary and in agreement. Particularly, the second method (measure of forces and moments) and the finite element method provide a mathematical and visual model that could explain clinical results: thus, the main purpose of this research is to understand the orthodontic mechanics used in the edgewise or segmented technique.

Adult↗
PubMed1998

Pressor and depressor responses in thermocoagulation of the trigeminal ganglion.

We have undertaken a retrospective analysis in 126 patients with trigeminal neuralgia on which a free-hand percutaneous thermocoagulation of the Gasserian ganglion was performed in our department. We focused on the occurrence of intraoperative vagal reactions, i.e. significant bradycardia and changes in blood pressure during the course of the procedure. Operative and anaesthetic records of patients who underwent the procedure were evaluated and correlated with clinical data from the patient's history. We observed the occurrence of vagal reactions i.e. significant bradycardia (< 50/min) or syncope in 20% of patients (p < 0.0002) during or immediately after penetration of the foramen ovale. No correlation between the operated side and the occurrence of vagal reactions was found. A significant rise in blood pressure levels (about 180 mmHg systolic) was observed in 36% of patients during thermocoagulation. We concluded that painful stimuli arising from lesioning in the course of the trigeminal nerve reach the mid-brain and may irritate the dorsal nucleus of the vagus nerve resulting in significant bradycardia or cardiac synode. To prevent haemodynamic deterioration i.v. atropine (0.5-2 mg) should be available when advancing the needle, while anti-hypertensive medication (Esmolol) may be needed during coagulation.

Blood Pressure↗
PubMed1993

MRI abnormalities in Creutzfeldt-Jakob disease.

Two patients with biopsy-proven Creutzfeldt-Jakob disease had MRI studies that revealed increased signal in the basal ganglia on T-2 weighted images, suggesting that MRI can be a useful diagnostic instrument in Creutzfeldt-Jakob disease.

Basal Ganglia↗
PubMed1987

Phase I-II trial of aclacinomycin A given in a four-consecutive-day schedule to patients with solid tumours. A South-East European Oncology Group (SEEOG) Study.

Aclacinomycin A (ACM) in a daily dose of 30 mg/m2 was infused over 1 h on 4 consecutive days to 50 patients. Myelotoxicity was acceptable, nausea and vomiting was frequent, hair loss was mild. Grade 1-2 cardiac rhythm abnormalities were observed in 12% of the patients. Between days 1 and 4 the heart rate and the corrected Q-T interval increased while the amplitude of the T wave decreased significantly, cardiac contractility remained unchanged. In 24 evaluable breast cancer patients 1 complete remission (4%) and 2 partial remissions (8%) lasting for only 2-3 months were seen. None of the 8 patients suffering from ovarial cancer benefitted from ACM therapy.

Aclarubicin↗
PubMed1987

Comparative evaluation of two administration schedules of cis-dichlorodiammineplatinum (DDP) in ovarian and head and neck cancers: a CMEA chemotherapy group study.

The therapeutic effectivity of two administration schedules of DDP were compared. The dose was either 100 mg/m2 infused for 4 h or 20 mg/m2 infused for 1 h on 5 consecutive days. The combined objective remission rate of the two regimens were 37/53 (23% CR ++ 44% PR) for ovarian cancer and 8/35 (9% CR + 14% PR) for head and neck cancer. WHO Grade 1-2 myelo- and nephrotoxicity was observed in 26% and 20%, respectively, out of the 105 cases evaluable for toxicity in the two groups. Nausea and vomiting was moderate to severe. Neither the remission rate nor the toxicity of the two schedules were significantly different.

Adult↗