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Biomedical subjects

P Dessi

Publications and source records attributed to P Dessi.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1996

[Partial lower turbinectomy in children: indications, technique, results].

Inferior turbinate surgery has been proposed as a treatment modality in severe childhood hypertrophic rhinitis refractory to medical treatment. The authors present a series of 38 children treated in the otorhinolaryngology department of the Timone University Hospital, Marseille, and the Rangueil University Hospital, Toulouse. Thirty eight children between 9 and 16 years of age (27 males and 11 females) underwent a bilateral inferior turbinectomy, and followed-up for a period of 6 months to 4 years. Allergy was fund in 19 patients, asthma in 11 patients, and an underlying sinus pathology associated in 9 patients. Turbinate surgery was isolated in 16 cases, and in 22 cases, it was associated with an adenoidectomy, a septoplasty, and/or an ethmoidectomy. The authors discuss the operative indications, and describe the turbinectomy technique in children. Post-operative complications are rare (no crusting rhinitis, one non symptomatic synechia). One case of nasal bleeding was noted after nasal packing removal. Functional obstructive symptoms were improved in near 90% of cases. Asthma was improved or disappeared in 27.3% of cases, and no cases of worsening asthma was noted. The authors conclude that this type of turbinectomy is efficient and non-iatrogenic when a precise indication and a rigorous technique are applied.

Adolescent↗
PubMed1995

Role of magnetic resonance imaging in predicting late facial motor function after removal of vestibular schwannomas by the translabyrinthine approach.

Facial motor function was assessed in 61 patients 18 months after surgical resection, by the translabyrinthine approach, of vestibular schwannoma involving both the cerebellopontine angle (CPA) and the auditory canal. Pre-operative magnetic resonance imaging (MRI) was performed to measure the maximum extracanalicular diameter of the tumour between the porus and the farthest extension in the CPA on transverse slices and to calculate extracanalicular tumour volume. Post-operative facial motor function was graded according to the House and Brackmann system. There was a statistically significant relationship between late facial motor function and extracanalicular diameter. The best cut-off point for good and poor results was 20mm. There was no relationship between the tumour volume and the late post-operative facial motor function grade. In this study the best pre-operative radiological predictor of the late facial motor function in patients operated on by the translabyrinthine approach was the maximum diameter measured by MRI.

Adult↗
PubMed1994

[Intra-sphenoidal prolapse of the internal carotid artery. Computed tomography of 300 sinuses].

OBJECTIVES: Endonasal sphenoidotomy is a high risk operation: fatal complications due to direct lesion to the internal carotid artery have been reported. We conducted a prospective analysis of carotid prolapse within the sphenoid cavity in order to draw attention to this dangerous anatomic variant. METHODS: Tomodensitometry of the sinuses was performed in 150 patients (mean age 35 years; range 20-70) with inflammatory nasal symptoms of less than one year duration (mean 5.2 months). Cases with benign or malignant tumours, polyposis or a past history of sinus trauma were excluded. Transversal sections were analyzed by one radiologist and one ear-nose-throat specialist. The diagnosis of carotid prolapse was defined as an intrasphenoid protrusion of the artery at least as long as one-third of its circumference. Results of the analysis were expressed as percent for 300 sinuses. RESULTS: Prolapse of the internal carotid was found in 20.3% of the sinuses (n = 61). In all cases a thin (> 1 mm) bony structure surrounded the artery. No prolapse was observed into the posterior ethmoid cells. CONCLUSIONS: Intrasphenoid prolapse of the internal carotid artery is a major risk factor in nasal and sinus surgery. The high incidence (1 out of 5 sinuses) indicates the need for routine preoperative imagery to reduce surgical risk.

Adult↗
PubMed1994

Protrusion of the optic nerve into the ethmoid and sphenoid sinus: prospective study of 150 CT studies.

Damage to the optic nerve is a serious complication of intranasal sinus surgery. Protrusion of the optic canal into the sphenoid sinus is a major risk factor. In this prospective study of 150 CT studies, we found this anatomical variation in 8% of cases. It was consistently associated with pneumatisation of the ipsilateral anterior or clinoid process. Protrusion of the optic nerve into the posterior ethmoid cells was never observed. CT is a useful part of the preoperative investigation of patients undergoing intranasal sinus surgery. Axial and coronal images obtained or by direct acquisition by reconstructions are necessary to show the position of the optic nerve.

Adult↗
PubMed1994

Major complications of sinus surgery: a review of 1192 procedures.

Based on this review of 1192 intranasal sinus procedures under endoscopic control with video assistance, the risk of major complications was estimated to be about 1.3 per cent. Ethmoidectomy was the most hazardous procedure. Operation by a right-handed surgeon standing on the right side of the patient was an added risk factor. We stress ways of achieving prevention, peroperative recognition of cerebrospinal fluid leaks and proper management of complications.

Adolescent↗
PubMed1994

Difference in the height of the right and left ethmoidal roofs: a possible risk factor for ethmoidal surgery. Prospective study of 150 CT scans.

A prospective study of 150 CT scans showed that the right ethmoidal roof was lower than the left in 8.6 per cent of cases. The reverse situation, i.e. the right higher than the left, was observed in only 1.2 per cent of cases. This finding could account for the higher reported incidence of endocranial complications associated with right ethmoidectomy. Coronal CT scans allowing comparison of the right and left ethmoidal roofs should always be made before undertaking intranasal ethmoidectomy.

Adult↗
PubMed1994

Effect of heavy smoking on nasal resistance.

Smoking is a part of our sociocultural environment. Its medical consequences are probably still underestimated. In this prospective clinical study, we explored the relationship between heavy smoking and nasal resistance. Anterior rhinomanometry was performed in 26 smokers and 26 non-smokers. Each group contained 13 men and 13 women. Analysis of variance of nasal resistance measurements using age and weight as covariables showed no significant difference between sexes. In contrast, a highly significant increase was noted between smokers and non-smokers. Age and weight had no influence on these results. Rhinomanometry proved to be an excellent method of detection for these modifications. Similar studies on the effects of passive smoking and of atmospheric and occupational pollutants should follow in the near future.

Adult↗
PubMed1994

Dehiscence of the lamina papyracea of the ethmoid bone: CT findings.

PURPOSE: To describe the CT findings characterizing dehiscence of the lamina papyracea. METHODS: Axial and coronal CT scanning of the paranasal sinuses was performed on 783 patients. RESULTS: Dehiscence of the lamina papyracea was noted incidentally in six patients. In all cases dehiscence was characterized by protrusion of orbital fat through a gap in the anterior ethmoid. The posterior limit of the dehiscence was always the basal lamella. The anterior limit varied. CONCLUSION: CT scans are often taken to detect polyps or assess chronic sinusitis. Awareness of dehiscence of the lamina papyracea is important to avoid misdiagnosis as infectious or tumoral process and possible injury of the orbit during endoscopic surgery.

Congenital Abnormalities↗
PubMed1993

[Rhinosinusal manifestations of cystic fibrosis].

The generalized disorders which characterize cystic fibrosis often involve the nose and paranasal sinuses and may frequently lead to the development of nasal polyps. A retrospective study of 78 patients with cystic fibrosis, 3 to 28 years old, was undertaken in order to determine the incidence of nasal involvement and to define an approach to the treatment of disabling recurrent nasal polyposis. 65% of these patients presented chronic symptoms such as rhinorrhea, nasal obstruction and disturbances of smell. Nasal polyps were found in 50% of patients and were more frequent in adults than in children. Clinical symptoms were directly related to the extent of polyp development which could be classified according to 3 groups. CT scans showed maxillary sinus involvement in almost all patients. The incidence and extent of ethmoidal sinus involvement on CT scans was correlated to the grade of polyp development. Medical treatment of polyposis failed in all cases. Polypectomy was always followed by recurrence. Intranasal ethmoidectomy seems to be an interesting alternative, since 73% of patients undergoing this procedure had clinical improvement.

Adolescent↗
PubMed1992

Intranasal ethmoidectomy in nasal polyposis in children. Indications and results.

Nasal polyposis in children is a rare pathology that is difficult to treat, with results that are often disappointing. The aim of this paper is focused on the surgical possibilities of ethmoidectomy by endonasal approach. Thirty-nine ethmoidectomies were performed in 24 children with a mean age of 12 years (cystic fibrosis, n = 7; Woakes' syndrome, n = 2; isolated polyposis, n = 15). The decision for surgical treatment was based upon the severity of initial symptoms, principally nasal obstruction, lack of improvement after medical treatment, and the assurance of good surgical follow-up. Twenty-three children were followed up for a mean of 3 years. Complete recurrence was noted in 13% of the cases (n = 3). In all the other cases, including those with partial recurrence, the lives of the children were transformed. Ethmoidectomy by endonasal approach is reliable if the appropriate surgical techniques are strictly followed. It has proven its efficacy in children with nasal polyposis with results that are very encouraging compared to previously proposed therapies.

Adolescent↗