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P Dessi

Publications and source records attributed to P Dessi.

At least 19 recordsLinked to original sources
PubMed2001

Protein import into plant mitochondria: precursor proteins differ in ATP and membrane potential requirements.

The import pathways of the alternative oxidase and the F(A)d subunit of the ATP synthase from soybean were characterised. The F(A)d precursor does not require extramitochondrial ATP for import and this was shown to be a characteristic of the mature protein. The alternative oxidase and F(A)d precursors were shown to differ in their requirement for a membrane potential. The membrane potential was modified using malonate, a competitive inhibitor to complex II. The alternative oxidase could be imported at higher malonate concentrations compared to the F(A)d. This difference could not be ascribed to the number of positive charges in each presequence as would be predicted from similar studies in fungi.

Adenosine Triphosphate↗
PubMed2000

[Epistaxis].

Epistaxis is a frequent clinical sign, but it can bring vital prognosis. Therefore a local or general cause must be searched without delay for stopping bleeding. We propose to pass in review etiologies, actual treatments and management of epistaxis.

Adult↗
PubMed2000

Radiological follow-up of inverted papilloma.

The aim of this study was to describe cross-sectional imaging features of recurrent papilloma of the nasal fossa and paranasal sinuses and to evaluate the role of MR and CT in the postoperative follow-up of this lesion. Magnetic resonance imaging and CT of ten patients who presented recurrence of inverted papilloma were reviewed and correlated to initial imaging, endoscopy, and surgical reports. Imaging patterns of recurrent inverted papilloma are identical to those of initial tumors and recurrence location is closely related to the site of the former lesion. Magnetic resonance is more efficient than CT for the diagnosis and evaluation of extensions. Magnetic resonance supplies the deficiencies of endoscopy in case of extensions to the frontal sinus or the lateral recess of the antrum, especially if mucosal hyperplasia or sinusitis is associated. Magnetic resonance imaging is the first imaging modality to perform in the follow-up after removal of inverted papilloma.

Adult↗
PubMed2000

Studies on the topology of the protein import channel in relation to the plant mitochondrial processing peptidase integrated into the cytochrome bc1 complex.

The mitochondrial processing peptidase (MPP) specifically cleaves N-terminal targeting signals from hundreds of nuclear-encoded, matrix-targeted precursor proteins. In contrast to yeast and mammals, the plant MPP is an integral component of the respiratory cytochrome bc1 complex. The topology of the protein import channel in relation to MPP/bc1 in plants was studied using chimeric precursors containing truncated cytochrome b2 (cyt b2) proteins of 55-167 residues in length, fused to dihydrofolate reductase (DHFR). The DHFR domain could be tightly folded by methotrexate (MTX), generating translocation intermediates trapped in the import channel with only the cyt b2 pre-sequence/mature domain protruding into the matrix. Spinach and soybean mitochondria imported and processed unfolded precursors. MTX-folded intermediates were not processed in spinach but the longest (1-167) MTX-folded cyt b2-DHFR construct was processed in soybean, while yeast mitochondria successfully processed even shorter MTX-folded constructs. The MTX-folded precursors were cleaved with high efficiency by purified spinach MPP/bc1 complex. We interpret these results as indicating that the protein import channel is located distantly from the MPP/bc1 complex in plants, and that there is no link between protein translocation and protein processing.

Biological Transport↗
PubMed2000

[Essential parathyroid cysts: a misleading lesion].

Though a rare lesion, non-functioning parathyroid cyst is of clinical significance because it usually mimics a thyroid nodule. The cyst can be ectopic in location and therefore constitutes a differential diagnosis to a bronchial or thymic cyst. Two recent cases of non-functioning parathyroid assay are reported. Needle puncture with estimation of the level of parathyroid hormone in the aspirate allows the diagnosis to be made before surgery.

Adult↗
PubMed1999

Integration of the mitochondrial-processing peptidase into the cytochrome bc1 complex in plants.

The plant mitochondrial cytochrome bc1 complex, like nonplant mitochondrial complexes, consists of cytochromes b and c1, the Rieske iron-sulfur protein, two Core proteins, and five low-molecular mass subunits. However, in contrast to nonplant sources, the two Core proteins are identical to subunits of the general mitochondrial processing peptidase (MPP). The MPP is a fascinating enzyme that catalyzes the specific cleavage of the diverse presequence peptides from hundreds of the nuclear-encoded mitochondrial precursor proteins that are synthesized in the cytosol and imported into the mitochondrion. Integration of the MPP into the bc1 complex renders the bc1 complex in plants bifunctional, being involved both in electron transport and in protein processing. Despite the integration of MPP into the bc1 complex, electron transfer as well as translocation of the precursor through the import channel are independent of the protein-processing activity. Recognition of the processing site by MPP occurs via the recognition of higher-order structural elements in combination with charge and cleavage-site properties. Elucidation of the three-dimensional (3-D) structure of the mammalian cytochrome bc1 complex is highly useful for understanding of the mechanism of action of MPP.

Animals↗
PubMed1999

[Imaging of the adult sinusitis: indications for using conventional techniques, CT scan and MRI].

CT scanning has become the major investigation for sinusitis which is not acute, but chronic. It is a good diagnostic tool, but also allows follow-up assessment of progress, and preoperative evaluation of particular problems related to abnormalities or anatomical variations. MRI scanning has a lesser place, and is most useful in evaluating certain types of pseudo-tumorous sinus conditions, or excluding local complications (in the anterior cranial fossa or orbit).

Adult↗
PubMed1999

[Extramedullary plasmocytoma of the nasal cavity: a case report].

PURPOSE OF STUDY: To establish a diagnosis and therapeutic management in patients with extramedullar plasmocytomas. METHOD: There is no consensus concerning extramedullar plasmocytoma treatment. One patient with a nasal cavity tumor location and a review of literature are reported. RESULTS: Extramedullar plasmocytoma is a rare tumor that occurs most frequently in the upper respiratory tract. The most common location is the nasal cavity. Diagnosis can only be made after histological and immunohistochemical examinations. Localized tumors are treated by radiation therapy, combined or not with surgery. Disseminated diseases are treated by chemotherapy. CONCLUSION: Diagnosis can only be confirmed after the exclusion of a systemic disease (multiple myeloma).

Adult↗
PubMed1998

Postoperative follow-up of juvenile nasopharyngeal angiofibromas: assessment by CT scan and MR imaging.

The purpose of this study was to assess the radiological findings after surgical removal of juvenile nasopharyngeal angiofibromas (JNA). The postoperative CT and MRI scans of ten patients were reviewed. The cured group included six patients. The non-controlled group included six patients with eight recurrences. Two patients belonged to both groups as they were also followed and cured after surgery for relapse. Four recurrences were asymptomatic and diagnosed by imaging. The imaging patterns were matched to the patients clinical status and endoscopic findings. In the cured group, non-enhanced residual soft tissue masses were seen in all cases. In the non-controlled group, recurrence was always demonstrated on early postoperative CT or MR as a dramatically enhanced mass. The recurrence was located in the lateral or superior aspect of the nasopharynx (n = 3), deep to the fossa of Rosenmuller (n = 4) or out of the nasopharynx (n = 1). In two cases a remaining enhanced mass disappeared spontaneously on iterated examinations. Because of numerous asymptomatic relapses, a radiological workup is recommended four months after surgery, even in patients with normal endoscopy, to rule out posterolateral or extranasopharyngeal recurrences. Spontaneous evolution of residual masses must be appreciated on iterated imaging examinations.

Adolescent↗
PubMed1998

A matrix-located processing peptidase of plant mitochondria.

Nuclear-encoded mitochondrial precursor proteins are proteolytically processed inside the mitochondrion after import. The general mitochondrial processing activity in plant mitochondria has been shown to be integrated into the cytochrome bc1 complex of the respiratory chain. Here we investigate the occurrence of an additional, matrix-located processing activity by incubation of the precursors of the soybean mitochondrial proteins, alternative oxidase, the FAd subunit of the ATP synthetase and the tobacco F1 beta subunit of the ATP synthase, with the membrane and soluble components of mitochondria isolated from soybean cotyledons and spinach leaves. A matrix-located peptidase specifically processed the precursors to the predicted mature form in a reaction which was sensitive to orthophenanthroline, a characteristic inhibitor of mitochondrial processing peptidase (MPP). The specificity of the matrix peptidase was illustrated by the inhibition of processing of the alternative oxidase precursor in both soybean and spinach matrix extracts upon altering a single amino acid residue in the targeting presequence (-2 Arg to Gly). Additionally, there was no evidence for general proteolysis of precursor proteins incubated with the matrix. The purity of the matrix fractions was ascertained by spectrophotometric and immunological analyses. The results demonstrate that there is a specific processing activity in the matrix of soybean and spinach in addition to the previously well characterized membrane-bound MPP integrated into the cytochrome bcl complex of the respiratory chain.

Cell Nucleus↗
PubMed1998

[Medico-economic aspects of the management of perennial allergic rhinitis in general medicine].

A cross sectorial epidemiologic study was conducted in daily medical practice on the cost of perannual rhinitis. This study on 2033 patients shows per consultation the following costs. Medical fees: 130 +/- 45 francs, pharmaceutical expenses: 141 +/- 59 francs, biological and imaging: 109 +/- 174 francs. The indirect costs link to the absent days are evaluated at 776 francs. This rhinitis costs 1156 francs or 380 francs according the fact that the patient stops working or not. The extrapolation of these results to the french population shows 3.42 billions francs for the direct costs and 6 billions for the indirect costs. By comparison to this total amount, medical and pharmaceutical expenses represent only 11.7% and 12.7%.

Absenteeism↗
PubMed1997

Temporal regulation of in vitro import of precursor proteins into tobacco mitochondria.

Protein import into isolated tobacco mitochondria was investigated using mitochondria from leaves harvested at different times of the day and night. Efficient import was only detected with mitochondria isolated from leaves harvested during the dark period of the growth cycle, only low levels of import were detected from leaves harvested during the light period. However, this temporal difference seen in import did not appear to be circadian in nature. This implies that the protein import process in mitochondria isolated from leaves is not constitutive. This has important implications for targeting specificity studies performed in transgenic plants, as unless the plants are tested at the time when import is occurring, the true in vivo targeting abilities of chimeric constructs will not be measured.

Biological Transport↗
PubMed1997

[Naso-sinusal polyposis in children. Mid-term results of sinusal surgery].

Nasosinusal polyposis in the pediatric population is uncommon and its etiology is unclear. In this eleven-year retrospective study, we describe the etiologic features and evaluate the effectiveness of endoscopic sinus surgery in 49 children. Patients were divided into three groups according to whether nasosinusal polyposis was either isolated (n = 14), or associated with either asthma (n = 5) or cystic fibrosis (n = 30). An allergy was present in 10% of patients with isolated polyposis, 80% of patients with polyposis associated with asthma, and 19% of patients with polyposis associated with cystic fibrosis. The indications for surgery were disabling symptoms, specially chronic nasal obstruction, rhinorrhea and mouth breathing, and failure to respond to medical treatment. No surgical complications were encountered. Most patients reported improvement in quality of life with reduction of nasal obstruction in 83% of cases and rhinorrhea in 61%. Minor asymptomatic recurrence (i.e. a few micropolyp localized on the roof of the ethmoid cavity) was observed in 22.7% of the cases in this series, and major recurrence with the same functional symptoms as before surgery in 13.6%. However, recurrences were higher in patients with cystic fibrosis, since minor recurrence with no clinical manifestation was observed in 28.6% of cases and major recurrence in 17.8%. Endoscopic sinus surgery must be decided in collaboration with the pediatric and pulmonary physicians, and must be performed skillfully. With a mean follow-up of 4 years, results in this series are encouraging.

Adolescent↗
PubMed1996

Characterization of the import pathway of the F(A)d subunit of mitochondrial ATP synthase into isolated plant mitochondria.

The synthetic precursor of the F(A)d subunit of mitochondrial ATP synthase was imported into isolated soybean cotyledon mitochondria. Import of the F(A)d precursor was accompanied by processing to a lower molecular weight mature form. The F(A)d precursor displayed the following import characteristics not seen before with plant mitochondria: efficient import in the absence of external ATP and import of wheat germ-translated precursor. Pretreatment of the F(A)d precursor with NEM did not inhibit import. Taken together with the lack of a requirement for external ATP, this indicates that this precursor does not require extramitochondrial ATP-dependent factors for import. Binding studies indicated that the F(A)d precursor bound to a proteinaceous component of the mitochondrial outer membrane. Inhibitor studies indicated that processing was most likely via the general mitochondrial processing peptidase. The results suggest that import of this subunit occurs via a pathway different from the general import pathway described for the majority of precursor proteins.

Biological Transport, Active↗
PubMed1996

Radiation dose to the lenses in CT of the paranasal sinuses.

The radiation dose to the lens during CT of the paranasal sinuses was measured in 20 patients. In 10 patients, a "standard" technique with axial and coronal sections was used. In the remaining 10 patients, overlapping axial sections for bidimensional reconstruction were obtained. Radiation dose was measured using thermoluminescent dosimeters. The mean dose was 22 mGy in patients who underwent "standard" CT and 42 mGy in those who underwent CT with overlapping sections. Dose was dependent on the total number of slices and of transorbital axial sections. Coronal sections did not statistically increase the radiation dose to the lenses. Although these doses were significantly below the critical dose for cataracts, CT with overlapping sections gives a considerably higher radiation dose. We recommend the bidimensional reconstruction technique only for selected cases (e.g. preoperative assessment of the roof of the ethmoid sinuses or in patients who can or should not maintain the hyperextended position required for coronal views.

Ethmoid Sinusitis↗