Search PubMed⌕ Search

Biomedical subjects

P Giraud

Publications and source records attributed to P Giraud.

At least 55 records · Page 3Linked to original sources
PubMed2000

[Use of radiotherapy in cardiovascular disease. Radiophysical basis, current results, indications and perspectives].

Restenosis is the main limitation of percutaneous angioplasty, especially in vessels of small diameters such as the coronary arteries, the femoro-popliteal and tibial-peroneal arteries and the arterio-venous dialysis grafts. The extensive use of tents has not entirely prevented its occurrence, whereas treating in-stent restenosis gives even more uncertain results. Endovascular radiotherapy has emerged over the past few years as a promising approach to both prevent and cure it. The analogy between the tumour-like cellular proliferations observed in post-angioplasty restenosis and tumour processes prompted pioneering works to study the effect of ionizing radiations in animal models of arterial restenosis. The demonstrated feasibility, tolerance and efficacy of this approach lead to test this strategy in humans. The results of 3 recently presented randomized double-blind trials in the treatment of coronary in-stent restenosis have been so promising that endovascular brachytherapy might now be considered the treatment of choice in this indication. Other randomized trials are currently carried out to test whether endovascular brachytherapy may prevent restenosis in coronary and femoro-popliteal arteries as well as in hemodialysis shunts. In the present review, we describe the basics of the biological effects of ionizing radiations, the technical modalities to deliver endovascular radiations, our current knowledge about their effects on the vascular wall and the restenosis mechanisms, and the results of the first clinical studies. Finally, we address the remaining problems in the use of endovascular curietherapy and question the promises and challenges of its clinical application.

Angioplasty, Balloon, Coronary↗
PubMed2000

Ultrastructural pathology of Creutzfeldt-Jakob disease and fatal familial insomnia.

In this study we examined well fixed brain biopsies of 9 sporadic CJD, 9 iatrogenic CJD cases, 2 hereditary CJD (Gly200Lys and Val203Iso), a case of vCJD and a case of fatal familial insomnia (FFI) from a new French family collected over the years at the Service de Neuropathologie, Hopital Neurologique, Lyon, France. Tubulovesicular structures (TVS) were found in every case including FFI and nvCJD. Thus, TVS, as we suggested previously are important pathologic structure which significance should be more extensively studied.

Amino Acid Substitution↗
PubMed1999

[Creutzfeld-Jakob disease].

Described in the early 1920s in Germany, Creutzfeldt-Jakob disease now comprises 4 entities: 1. familial forms are linked to mutations of the gene coding for prion protein (about 8% of the cases); 2. iatrogenic forms are due to interventions using contaminated material or human extracts (about 5% of the cases); 3. sporadic forms represent the majority of the cases (about 87%) without any established explanation; 4. recently described new variant, related to bovine spongiform encephalopathy, remains quite rare (41 known cases). In all its forms, the disease is constantly mortal after a usually short course. Major signs are rapidly evolving; dementia with myoclonus, ataxia, and electroencephalographic abnormalities (periodic activity). Formal diagnosis is histologic.

Animals↗
PubMed1999

Combination antiretroviral therapy including ritonavir in children infected with human immunodeficiency.

OBJECTIVE: To assess the efficacy of combination therapy that includes ritonavir in HIV-1 infected children. DESIGN: A monocentric retrospective study. PATIENTS AND METHODS: Twenty-two children with a minimum follow-up of 6 months under triple therapy including ritonavir were analysed for treatment efficacy. At entry, all the patients were protease inhibitor naive and all but two had received previous antiretroviral therapy during a median period of 5 years. Their initial median CD4+ lymphocyte count and viral load were 121 x 10(6)/l and 5.08 log10 copies/ml, respectively. Clinical and biological evaluation included clinical assessment every 6 weeks and determination of CD4 cell count and HIV-RNA concentration every 3 months. RESULTS: Median length of follow-up on triple therapy was 15 months (range: 7-21 months). Neither progression in the CDC classification nor death occurred. No significant change in mean weight SD scores was noted when baseline values were compared with values obtained after 1 year of triple therapy. Median CD4 count increases were of 210 x 10(6)/l, 415 x 10(6)/l, and 472 x 10(6)/l cells at 6, 12, and 18 months, respectively. Among the patients baseline characteristics, neither age nor initial CD4 cells count influenced the magnitude of immunologic improvement. There were median decreases of 1.14, 0.95, and 1.5 log10 per ml of plasma in the concentration of viral RNA at 6, 12, and 18 months respectively. Seven patients maintained an undetectable viral load when under treatment. The introduction of at least one new reverse transcriptase inhibitor at the initiation of triple therapy correlated significantly with a greater viral suppression. CONCLUSION: Despite variable viral response, antiretroviral-experienced HIV-infected children demonstrated a substantial CD4 cell increase during a median period of 15 months of ritonavir containing combination therapy.

Adolescent↗
PubMed1999

[Severe lactic acidosis and thiamine deficiency during parenteral nutrition in a child].

We report the case of a leukemic child treated with chemotherapy and parenteral nutrition for three weeks, who developed a severe lactic acidosis. Clinical features included both digestive and neurological disorders associated with a moderate cardiovascular collapse. After elimination of a toxic, a neoplastic or a septic cause, a thiamin (or vitamin B1) deficiency was suspected because of the lack of vitamin supply to parenteral nutrition. Intravenous administration of thiamin rapidly controlled lactic and clinical features. The diagnosis was confirmed by a low plasmatic concentration of thiamin. Thiamin deficiency must be suspected in case of severe lactic acidosis during parenteral nutrition and systematically prevented by supply of vitamins.

Acidosis, Lactic↗
PubMed1998

Low-dose splenic irradiation in the treatment of immune thrombocytopenia in HIV-infected patients.

PURPOSE: To determine the effect of low-dose splenic irradiation on severe Zidovudine-resistant, HIV-1-associated thrombocytopenia (HAT). METHODS AND MATERIALS: Between September 1994 and October 1996, 17 patients were included in a prospective study. The patients met the following criteria for inclusion: hemorrhagic symptoms or a platelet count below or equal to 50 x 10(9)/l and normal numbers of megakaryocytes on bone aspiration. The mean baseline platelet count was 20.3 (+/- 14.4) x 10(9)/l; four patients had a platelet count inferior to 10 x 10(9)/l. Splenic volume was defined by ultrasonography. A total dose of 9 Gy was given using an isocentric parallel pair field technique. RESULTS: One month after the end of treatment six patients had a significant rise in their platelet count. Clinically, hemorrhagic symptoms stopped for all patients that were symptomatic. Unfortunately, duration of response was short because for one patient only the platelet count remains stable with a follow-up of 6 months. All patients are alive and in recent evaluation, with four out of eight patients receiving a combination of antiretroviral therapy had a platelet count above 50 x 10(9)/l. CONCLUSION: Our results are disappointing concerning the duration of response, especially comparatively to those reported in autoimmune thrombocytopenia. Mechanisms of HAT are more complex, and megakaryocytes' infection may play an important role. Splenic irradiation should be considered as palliative treatment for the minority of patients with severe bleeding that does not respond to standard medical treatment.

Adult↗
PubMed1998

Multiple pathways regulate the expression of genes encoding sodium channel subunits in developing neurons.

In primary cultures of fetal neurons, activation of sodium channels with either alpha-scorpion toxin or veratridine caused a rapid and persistent decrease of mRNAs encoding beta2 and different sodium channel alpha mRNAs. In contrast, beta1 subunit mRNA was up-regulated by sodium channel activation. This phenomenon was calcium-independent. The effects of activating toxins on mRNAs of different sodium channel subunits were mimicked by membrane depolarization. An important aspect of this study was the demonstration that cAMP also caused rapid reduction of alphaI, alphaII and alphaIII mRNA levels whereas beta1 subunit mRNA was up regulated and beta2 subunit mRNA was not affected. Sodium channel activation by veratridine was shown to increase cAMP immunoreactivity in cultured neurons, but alphaII mRNA down-regulation induced by activating toxins was not reversed by protein kinase A antagonists, indicating that this phenomenon is not protein kinase A dependent. The effects of cAMP and membrane depolarisation were antagonized by the PKA inhibitor H89. These results are indicative of the existence of multiple and independent regulatory pathways modulating the expression of sodium channel genes in the developing central nervous system.

Animals↗
PubMed1998

Expression of the mRNA for the beta 2 subunit of the voltage-dependent sodium channel in rat CNS.

Expression of the voltage-dependent sodium channel has been analysed in adult rat central nervous system by Northern blotting and in situ hybridization. Northern blots showed that all the territories studied express beta 2 transcripts, albeit with widely varying levels (with cerebellum >> hippocampus > brain > brainstem > spinal cord). In situ hybridization confirmed that in these structures, all the neuronal cell bodies contain beta 2 mRNA; expression was particularly high in the granule cells of the cerebellum, in both pyramidal cell layer and dentate gyrus in the hippocampus, and in spinal cord motor neurons. Northern blots also showed that RNA extracted from optic nerve and cultured cortical astrocytes contained beta 2 mRNA, while it was totally absent from sciatic nerve. In situ hybridization evidenced the presence of a numerous population of beta 2-positive cells in cerebellum white matter, spinal cord white matter, and in corpus callosum, where frontal sections showed labelled cells arranged in the chain-like or row pattern typical of interfascicular oligodendrocytes. Combination of antiglial fibrillary acid protein (GFAP) immunofluorescent histochemistry with detection of beta 2 mRNA evidenced that expression of the transcripts was indeed restricted to GFAP-negative cells in white matter.

Animals↗
PubMed1998

Gliomatosis cerebri: a rare cause of progressive headache.

A 49-year-old right-handed woman was admitted for an 8-month history of unusual headache and transient diplopia. Clinical examination and brain CT scan were normal. Two months later, symptoms of raised intracranial pressure developed and a brain CT scan showed small lateral ventricles and sulci without any abnormal contrast enhancement or tumor mass. Brain MRI with T2-weighted spin echo sequences revealed a hyperintense signal in the right temporoparietal region, whereas only a slight enlargement of this region was noted on T1 spin echo. The patient deteriorated rapidly and died with uncontrollable raised cerebrospinal fluid pressure. The diagnosis of gliomatosis cerebri was made at necropsy. Gliomatosis cerebri is a rare intracranial neoplasm of neuroepithelial origin. Spread of this tumor is particularly fast in the white matter compared with the gray matter and nuclei. Clinical symptoms are not specific. The diagnosis can be suspected by MFU showing an isointense or hypointense signal in the deep white matter on T1-weighted images, and largely a hyperitense signal on T2-weighted sequences. The diagnosis is confirmed by stereotactic biopsy or necropsy. No curative treatment is currently available. Radiotherapy can delay the rapidly fatal outcome. Our case illustrates the possible onset of this rare disease by isolated cephalgia with normal early CT scan.

Brain Neoplasms↗
PubMed1997

Down-regulation of voltage-dependent sodium channels coincides with a low expression of alphabeta1 subunit complexes.

The association between the beta1 subunit and the alpha subunit of the sodium channel from rat brain was studied in hippocampus during postnatal development and in cultures of fetal rat forebrain neurons and cerebellar granule cells, using an anti-beta1 antipeptide antibody to specifically immunoprecipitate alphabeta1 complexes labeled with [3H]saxitoxin. In the hippocampus, the increase in beta1 RNA expression during development was accompanied by an increase in immunoprecipitated alphabeta1 complexes. Most of the alphabeta1 complexes were constituted during the first 3 postnatal weeks, with the steepest rise between postnatal days 5 and 12. In cultured fetal neurons, the amount of beta1 RNA and of alphabeta1 complexes was approximately 3-4% of that found in the adult, whereas it reached 60-70% in cultured cerebellar granule cells. We had previously described a neurotoxin-induced internalization of sodium channels which occurred in immature neurons but not in adult tissue. Internalization decreased during development in neurotoxin-treated hippocampal slices, and resistance of plasma membrane sodium channels to internalization followed the same time course than the appearance of alphabeta1 complexes. Similarly, neurotoxin activation resulted in sodium channel internalization in fetal neurons, while cerebellar granule cells, which express high levels of beta1 RNA and of alphabeta1 complexes, did not internalize their [3H]saxitoxin receptors in that same conditions. These data suggested that the association of the beta1 subunit with the alpha subunit could provide a suitable marker for the stabilization and anchoring of sodium channels in discrete membrane domains which occur during neuronal development.

Aging↗
PubMed1997

[Somatosensory evoked potentials in rheumatoid polyarthritis with radiologic involvement of the cervical spine].

Somatosensory evoked potentials (SEP) have been recorded in 11 patients with cervical spine involvement, with or without signs of myelopathy due to rheumatoid arthritis (RA). In three patients, SEP have been recorded both before and after cervical spine surgery. In seven cases, the P14 (particularly the P9/P14 amplitude ratio) or P30 potentials were abnormal, whereas other potentials and conduction times were less often modified. Vertebral luxation sites that were predominantly observed at the upper cervical level account for these findings, thus supporting the diagnostic utility of P14 and P30 potentials which respectively take origin in the lower brain stem, close to or into the nuclei cuneatus and gracilis. Postoperative SEP were strongly correlated with the surgical outcome. SEP could be abnormal in the absence of overt clinical myelopathy or vertebral luxations, thus revealing infraclinical damage to the somatosensory pathways. This suggests that SEP recording is useful to discriminate RA patients with upper cervical cord dysfunction from those in whom vertebral lesion proves to have no direct impact on somatosensory conduction.

Adult↗
PubMed1997

[Hyperfractionated reirradiation after salvage surgery in cervico-facial carcinoma. Result of a pilot study in 14 patients].

PURPOSE: Between November 1988 and May 1992, 14 patients were enrolled in a pilot study to evaluate the feasibility and results of hyperfractionated reirradiation for the treatment of head and neck recurrences or of second primary tumors developed in a previously irradiated volume. MATERIALS AND METHODS: All patients underwent a surgical resection for the treatment of their recurrence or second cancer. Reirradiation was proposed because of positive margins and/or lymph node metastasis with extra-capsular spread. The planned reirradiation dose was 60 Gy over 5 weeks, with two daily fractions of 1.2 Gy delivered 6-8 hours apart. RESULTS: Of the 14 patients, 10 received the reirradiation scheduled dose (ie, 60 Gy). All patients experienced an acute mucositis that never led to disruption of the treatment. Ten patients died 3 to 41 months after reirradiation (mean: 14 months), three were disease-free 48 to 71 months after reirradiation and one was alive with local progressive disease 74 months after reirradiation. The overall local control rate within the reirradiated volume was 43%. The 24- and 36-month overall survival rates were 50 and 35%, respectively. Overall, 13 late complications were noted: four were grade 1, seven were grade 2, and two were grade 3. Three patients still alive in September 1993 and whose initial files were available were enrolled in an additional study to assess from dose-volume histograms the cumulative doses delivered by the two irradiations. CONCLUSION: Despite poor local control, reirradiation using a hyperfractionation schedule with high dose level is feasible in terms of acute and late toxicity.

Adult↗
PubMed1997

[Predictive tests of response to radiotherapy. Assessment and perspectives in 1997].

The potential tailoring of radiotherapy modalities to the biological characteristics of individual tumours and normal tissues appears to be an exciting way to improve the therapeutic, ratio in radiation therapy patients. Numerous assays have been proposed to provide the clinician with the biological information necessary to predict the outcome after irradiation and to guide the treatment prescription, but none of them has made its way to daily practice. Major difficulties are due to the technical burden of the procedures, the poor characterization of the assayed cells, and, moreover, the high complexity of tumour and normal tissues biology. The present paper reviews the present status of the assessment of tumour cells radiosensitivity, proliferation and oxygenation. Research remains extremely active in the field of biological predictors of response to irradiation. Future steps forwards are expected from progress in the available technologies, (re-)discovery of apoptosis and investigation of normal tissue tolerance.

Apoptosis↗
PubMed1997

Predicting the efficacy of first iodine-131 treatment in differentiated thyroid carcinoma.

UNLABELLED: The purpose of this study was to search for predictors of (131)I first ablative treatment efficacy in patients with postsurgical remnants after total thyroidectomy for nonmedullary differentiated thyroid carcinoma with no known metastasis. METHODS: Thirty-seven patients were retrospectively studied. None presented antithyroglobulin antibodies. All patients received 111 MBq of (131)I for diagnostic purpose and, 9 days later, 3.7 GBq of (131)I for ablative therapy (IAT). To assess the efficacy of treatment, all patients were studied with (131)I and with thyroglobulin (Tg) plasma assays 6-15 mo later. Treatment was considered successful if no abnormal uptake was seen on whole-body scan and if the Tg plasma level was lower than 1 ng/ml. RESULTS: Ablative treatment was found to be successful in 17 patients [IAT(+)] and unsuccessful in 20 [IAT(-)]. There was no significant difference between the two groups for clinical and histological data, size of thyroid remnants on a 1:1 dot scan and TSH level just before treatment. Although Tg levels were not different in the two groups before scanning dose administration (D0), Tg levels were higher in IAT(-) group 9 days later, just before radioiodine treatment administration (D9) and, in contrast, Tg levels were higher in the IAT(+) group 5 days after treatment administration (D14). Tg percentage change between D9 and D14 was significantly higher in the IAT(+) group and, with an optimal cutoff value of 750%, this parameter would have been able to predict successful treatment in 9 of 10 cases and unsuccessful treatment in 18 of 21 cases. Conversely, Tg percentage change between D0 and D9 was significantly higher in the IAT(-) group and of 11 patients with more than 100% change, 10 belonged to this group. CONCLUSION: The increase in Tg during the first (131)I ablative treatment could be a good predictor of treatment efficacy for patients with nonmetastatic differentiated thyroid carcinoma. Conversely, the increase in Tg observed after the administration of the scanning dose of (131)I just before ablative therapy is associated with a more frequent incomplete ablation, perhaps reflecting a stunning effect on the thyroid remnants.

Adenocarcinoma, Follicular↗