PubMed Health⌕ Search

Biomedical subjects

H Robert

Publications and source records attributed to H Robert.

At least 19 recordsLinked to original sources
PubMed2001

Polycomb group genes control pattern formation in plant seed.

Transcriptional activators of the Trithorax group (TRX-G) and repressors of the Polycomb group (Pc-G) are involved in multiple aspects of embryogenesis in Drosophila and the mouse [1, 2] and appear to have a conserved role in the zygotic control of the development of the anterior-posterior axis [3, 4, 5]. In the model plant Arabidopsis, three Pc-G genes have been isolated and characterized to date. CURLY LEAF (CLF) represses the expression of a floral homeotic gene in vegetative tissues but does not appear to have a role in plant embryogenesis [6]. Two other Pc-G genes, FIS1/MEDEA [7, 8, 9], and FIS3/FIE [8, 10] have been characterized in studies of mutants that produce seeds in the absence of fertilization. Seeds resulting from autonomous development in fis mutants do not contain an embryo but only endosperm, the second product of double fertilization in flowering plants [11, 12]. Thus, FIS genes are considered to be repressors of endosperm development before fertilization. We report that when fis ovules are fertilized, the endosperm patterning along the major polar axis is perturbed. Posterior structures develop in more anterior domains of the endosperm. This correlates with the ectopic expression of a posterior molecular marker. FIS genes appear to be potent regulators of the establishment of the anterior-posterior polar axis in the endosperm.

Arabidopsis↗
PubMed2001

Circular polarization excitation and detection in (14)N NQR.

Circular polarization excitation and detection of (14)N NQR signal are reported. A theoretical model is presented in terms of fictitious spin-1/2 operators and is compared to experiments performed on a powder crystalline sample of RDX. It is shown that in spin-1 systems with finite asymmetry--unlike previously reported NMR and symmetric spin-3/2 NQR systems (Chen et al., J. Magn. Reson. 54, 324--327, 1983; Weber and Hahn, Phys. Rev. 120, 365--375, 1960)-the circular polarization nature of the signal is due to powder orientation effects in polycrystalline samples. Sensitivity improvements up to a factor of the square root of 2 are reported using the same hardware and switching modes from linear polarization to circular polarization; this also is shown to result from the polycrystalline nature of the samples.

Journal Article↗
PubMed2001

Solid state proton imaging detected by quadrupole resonance.

A double resonance method for imaging of solid materials containing quadrupole nuclei via the coupled protons is reported. The technique uses a static field gradient to encode the position on the protons and the method of double resonance spin-echo to detect the occurrence of proton resonances by affecting the zero-field echo signal from the quadrupole system. The double resonance imaging method offers the advantages of higher spatial resolution and straightforward image reconstruction for powder samples compared with rotating-frame and Zeeman-perturbated nuclear quadrupole resonance encoding techniques.

Journal Article↗
PubMed2001

Improving resolution in fast rotating-frame experiments.

The rapid rotating-frame technique allows significant reduction in data-acquisition time compared with the two-dimensional method by stroboscopic observation of the nuclear magnetization during its evolution in the rotating frame. A onefold reduction in the dimensionality of the original rotating-frame experiment is achieved by using a train of strong radiofrequency pulses separated by short acquisition windows. The penalty for shortening experimental time is a reduction in spectral resolution compared with the two-dimensional method due to relaxation of transverse magnetization components during the observation windows. A variant of the rapid-rotating frame technique for improving spectral resolution based on undersampling and self-phase encoding is presented. An M-fold resolution improvement requires M experiments, thus, making possible a tradeoff between spectral resolution and experimental time. The technique was applied for spatial localization of quadrupole nuclei in powder solids, and resolution improvement is demonstrated on one- and two-dimensional NQR images.

Journal Article↗
PubMed2001

Influence of seven beverages on salicylate disposition in humans.

OBJECTIVE: Aspirin administered orally is one of most widely self-prescribed drugs to treat headaches or other pains. The aim of this study was to evaluate whether the influence of different beverages may be used to help in the ingestion of an aspirin tablet on the pharmacokinetic parameters of this drug. METHOD: This study was undertaken in five healthy volunteers. Seven beverages were tested: water, tea, coffee, orange juice, milk, beer and 40 degrees distilled alcohol. After plasma extraction, aspirin and salicylic acid were measured by HPLC with UV detection. The main pharmacokinetic parameters were determined by the compartimental method and drug disposition profiles by the Wagner-Nelson modified method. RESULTS: Elimination was not modified by any of the beverages but absorption was affected. Two opposing effects were observed: 40 degrees alcohol seemed to increase AUC and Cmax. Milk and beer seemed to decrease these parameters. With 40 degrees alcohol and tea, the amount absorbed and the disposition rate were higher. For milk and orange juice, the amount absorbed was lower and the disposition rate was unaffected. For beer, both the amount absorbed and the disposition rate increased. For coffee, both the amount absorbed and disposition rate were not significantly modified. CONCLUSION: The bioavailability of salicylates on the healthy volunteers in this study was significantly affected by concomitant administration of 40 degrees alcohol (spirit), beer and milk. The beverages seem to interfere with aspirin absorption and the drug disposition profile was modified.

Administration, Oral↗
PubMed2000

Glycine betaine, carnitine, and choline enhance salinity tolerance and prevent the accumulation of sodium to a level inhibiting growth of Tetragenococcus halophila.

Natural-abundance (13)C-nuclear magnetic resonance was used to probe the intracellular organic solute content of the moderately halophilic bacterium Tetragenococcus halophila. When grown in complex growth media supplemented or not with NaCl, T. halophila accumulates glycine betaine and carnitine. Unlike other moderate halophiles, T. halophila was not able to produce potent osmoprotectants (such as ectoines and glycine betaine) through de novo synthesis when cultured in defined medium under hyperosmotic constraint. Addition of 2 mM carnitine, glycine betaine, or choline to defined medium improved growth parameters, not only at high salinity (up to 2.5 M NaCl) but also in media lacking NaCl. These compounds were taken up when available in the surrounding medium. The transport activity occurred at low and high salinities and seems to be constitutive. Glycine betaine and carnitine were accumulated by T. halophila in an unmodified form, while exogenously provided choline led to an intracellular accumulation of glycine betaine. This is the first evidence of the existence of a choline-glycine betaine pathway in a lactic acid bacterium. An assay showed that the compatible solutes strikingly repressed the accumulation of glutamate and slightly increased the intracellular potassium level only at high salinity. Interestingly, osmoprotectant-treated cells were able to maintain the intracellular sodium concentration at a relatively constant level (200 to 300 nmol/mg [dry weight]), independent of the NaCl concentration of the medium. In contrast, in the absence of osmoprotectant, the intracellular sodium content increased sharply from 200 to 2,060 nmol/mg (dry weight) when the salinity of the medium was raised from 1 to 2 M. Indeed, the imported compatible solutes play an actual role in regulating the intracellular Na(+) content and confer a much higher salt tolerance to T. halophila.

Adaptation, Physiological↗
PubMed2000

[Radiotherapy of localized prostatic cancer: follow-up of 48 patients. G.C.C.P. (Cooperative Group for the Study of Prostatic Cancer)].

OBJECTIVE: To evaluate the safety and long-term efficacy of curative-intent radiation therapy in patients with apparently localized prostate cancer. METHOD: 48 patients with T < 3 M0 prostate cancer recruited between 1981 and 1985 received regular clinical follow-up for at least ten years or until their death. Radiation therapy was given according to the protocols established by Ray and Bagshaw. RESULTS: Radiation therapy was safe and effective in most patients. The rate of escape phenomenon was less than 10% after two years. Tumor control rates were greater than 80% after five years and 50% after ten years. Unfortunately, local remission, even when prolonged, did not necessarily indicate a complete cure: 20% of local recurrences developed five to 11 years after radiation therapy. CONCLUSION: Radiation therapy may be the best first-line treatment in men older than 75 years of age and in those whose life expectancy seems shorter than ten years, but should probably not be considered curative.

Aged↗
PubMed1999

Phase-modulated rotating-frame NQR techniques for spatial encoding

The rotating-frame method of localization for spatially resolved spectroscopy and imaging in the pure quadrupole regime relies on a gradient B(1) field in which spins experience a flip angle dependent on their position in the B(1) field strength. So far, the techniques have been implemented as amplitude-modulated methods, i.e., the spatial nuclear quadrupole distribution is encoded in the amplitude of the free-induction decay signals. In this work, we describe the implementation of phase-modulated variants of both two-dimensional and rapid rotating-frame imaging techniques. The experiments are discussed for both single crystalline and powder samples. The phase-modulated experiment offers some advantages over the amplitude-encoding technique: It enables one to distinguish the sign of the spatial coordinate and the signal-to-noise ratio is higher than for the simplest amplitude-encoding method. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Iron deficiency in older people: interactions between food and nutrient intakes with biochemical measures of iron; further analysis of the National Diet and Nutrition Survey of people aged 65 years and over.

OBJECTIVE: To quantitatively investigate relationships between food consumption, nutrient intake and biochemical markers of iron status in a population of older people. DESIGN: National Diet and Nutrition Survey: cross-sectional survey of a nationally representative population of men and women aged 65 y and over. SETTING: Mainland Great Britain SUBJECTS: 1268 participants (651 men and 617 women) who provided both dietary intake and blood biochemistry. 986 were living in private households and 282 were living in residential or nursing homes. RESULTS: Intakes of alcohol, vitamin C, protein, haem and non-haem iron and fibre were positively associated with iron status. Consumption of meat, poultry and fish were positively associated with six measures of iron status, and vegetables and potatoes with four measures. Calcium, dairy foods and tea generally had a negative association with most measures of iron status. CONCLUSIONS: A varied diet containing meat, poultry and fish, vegetables and fruit, with a moderate intake of alcohol will make a positive contribution to the iron status of elderly people.

Aged↗
PubMed1999

Clozapine-olanzapine: a potentially dangerous switch. A report of two cases.

BACKGROUND: Withdrawal symptoms associated with switch between two typical antipsychotics are generally rare and mild. In contrast, switching from clozapine to risperidone can be lead to severe withdrawal symptoms. Different pathophysiologic aetiologies have been suggested for explaining these severe symptoms, including cholinergic supersensitivity and rebound. Theoretically, the switch from clozapine to olanzapine should not lead to any problems because those two agents have the same affinity in vitro for muscarinic receptors. OBJECTIVE: This study reports two cases of switches from clozapine to olanzapine, in refractory schizophrenic patients, which were associated with severe withdrawal symptoms. RESULTS: After the switch, the two patients developed diaphoresis, hypersialorrhea, bronchial obstruction, agitation, anxiety and enuresis. The symptoms were treated with anticholinergic medication and by an increase in dose of olanzapine to 20 mg/day. For one of the patients this treatment led to normalization of secretion. For the other patient, a superinfection leading to a bilateral pneumopathy which required emergency hospitalization in a general hospital was observed. CONCLUSION: The symptomatology and the response to treatment lead to the hypothesis of a muscarinic from abrupt weaning. The withdrawal symptoms disappeared rapidly with an increase in olanzapine dosage and with anticholinergic started at the beginning of the switch. We recommend slow clozapine weaning over 3 weeks or more with concurrent anticholinergic treatment.

Adult↗
PubMed1999

Autologous chondrocyte implantation. A review of techniques and preliminary results.

The treatment of deep focal bone and cartilage defects in weight-bearing areas of the knee remains challenging. Autologous chondrocyte implantation is a recently introduced alternative to drilling and mosaicplasty and is gaining ground in France under the impetus of favorable results obtained in other countries in highly selected cases. The technique and preliminary results are discussed herein.

Cartilage, Articular↗
PubMed1998

Mapping molecular orientation in solids by rotating-frame NQR techniques

A multi-dimensional NQR technique to image both the spatial distribution of quadrupolar nuclei and the local orientation of the electric field gradient tensor at the quadrupole sites in solids is reported. The encoding procedure is based on the irradiation of the sample by a pulse sequence composed of spatially homogeneous and inhomogeneous radiofrequency fields. A method that encodes the spatial and orientation information in the amplitudes of the free-induction decay signals and a proper three-dimensional reconstruction procedure that yields the space-orientation-dependent NQR spectra are described. A two-dimensional variant allows rapid measurement of the spatially dependent orientation distribution of molecules, disregarding the spectroscopic information. Copyright 1998 Academic Press.

Journal Article↗
PubMed1997

[Medico-economic evaluation of treatment with clozapine versus treatment with previous neuroleptics].

Since clozapine has been introduced into the treatment of schizophrenia, pharmaceutical costs rised in hospital. However, this data is not sufficient to estimate its global effect on cost-effectiveness; that's why we studied the whole direct costs generated by schizophrenia, the clinical effectiveness as well as the impact of therapeutics on the patients' quality of life. This work is a retrospective study of cost-effectiveness of clozapine treatment within three french psychiatric hospitals. The study was divided into three parts: - a twelve-month period concerning the treatment before clozapine; - two twelve-month periods for the analysis of clozapine treatment. The clinical evaluation was based on the CGI and an autoevaluation scale. Whether schizophrenic patients were hospitalized or not and the importance of neuroleptic-associated medicines were taken into account to evaluate the Quality of Life. The economical assessment is represented by adding pharmaceutical costs, biological examinations costs and hospitalization costs. Thirty-seven patients, out of seventy-five, were being taken into account (26 men and 11 women). The results of the CGI and autoevaluation scale showed a global improvement in the pathology within the first year of treatment, which is confirmed during the second year. A statistically significant decrease in the length of full-time hospitalization was noticed; this profits to half-time hospitalization, indeed purely ambulatory. The direct costs per patient and per day insignificantly decreased between the first and the second period; on the other hand, the drop was statistically significant between the second and the third period. This study, based on a small amount of patients shows that the use of clozapine, which clearly helped the patients to improve, leads to a drop in global direct costs per patient, despite the high cost of the medicine itself, as well as an improvement in the quality of life.

Adult↗
PubMed1997

[Focal myositis in children. Apropos of a case].

An eleven year old boy presented with localized swelling of the left calf which had been developing for more than 5 years. Another smaller mass was found in the pretibial area. There was an invincible equinus deformity of the foot. Surgical biopsies revealed characteristic histological features of focal myositis showing necrotic and regenerating muscle fibers, randomly distributed, with inflammatory infiltration. An intense fibrotic reaction was observed. This constitutes to our knowledge the first reported case of focal myositis in which development of muscle sclerosis was so important that it was necessary to perform tenotomies one year after excision of the principal tumor in order to restore normal gait. A nearly two-years follow-up does not give evidence of recurrent lesion.

Achilles Tendon↗
PubMed1996

Determination of clozapine in serum by radioreceptor assay versus high-performance liquid chromatography: possible detection of hydroxy-metabolites.

Clozapine is an antipsychotic drug with few extra-pyramidal motor side-effects, used to treat schizophrenia which is resistant to classical neuroleptic therapy. This report shows that norclozapine but not clozapine-N-oxide has the same D2 receptor affinity as clozapine. Assay results suggest a bimodal distribution which may be explained by CYP1A2 polymorphism. Extensive metabolizers could produce other active metabolites, probably other hydroxy-clozapine derivatives.

Animals↗
PubMed1992

[Electrophysiologic data on myasthenic syndromes of the Lambert-Eaton type. A series of 23 cases].

The electrophysiological data of 23 adult patients with Lambert-Eaton myasthenic syndrome (LEMS) have been reviewed. Lung carcinoma was disclosed in 17. In six cases with an EMG follow-up ranging between one and 17 years no carcinoma was detected. The results of repetitive nerve stimulation test (RNS) were not statistically different between the 2 groups. Low CMAP ulnar amplitude was present in all patients (mean: 1.7 mV). Decremental response at low rate of stimulation (3 Hz) was present in 17/20 (means: 30%). An abnormal incremental response at high rate of stimulation was present in all cases (mean: 826%). The authors emphasize the interest of a 50 Hz stimulation for 4 s. Increase of the 'F-wave' amplitude was noticed in some cases. Electrophysiological changes suggestive of an associated mild neuropathy were noticed in eight patients but H-reflex was present in 3/3 cases. SFEMG abnormalities were found in 6/6 cases. In one case, stimulated SFEMG showed more blockings and an increased jitter with low rate of stimulation. In one case the electrical pattern of RNS could be misinterpreted as myasthenia gravis in one tested muscle only. The author's results suggest that CMAP amplitude and RNS test could be used to appreciate the short-term improvement of LEMS with treatment and in some cases for the long-term follow-up.

Adult↗
PubMed1990

A new series of antiarrhythmic procainamide derivatives: toxicity and activity-simulated passive absorption relation.

Several compounds derived from benzamidines and nicotinic pyridinic amidines with a structure similar to that of procainamide, exhibit notable antiarrhythmic properties after injection into animals. The diffusion rate of these different compounds through a solid lipidic artificial membrane was studied with Dibbern's apparatus. A statistical relation was established between the diffusion rate and the principal pharmacological parameters obtained after intraperitoneal injection (toxicity and anthiarrhythmic activity). Essential structural elements seem to determine a better bioavailability than procainamide: character of the substitution (in para) of the benzenic cycle; length of the lateral chain.

Absorption↗