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Biomedical subjects

L Politi

Publications and source records attributed to L Politi.

At least 19 recordsLinked to original sources
PubMed2006

Clinical implications of hepatitis C virus infection in MALT-type lymphoma of the ocular adnexa.

BACKGROUND: A pathogenic link between hepatitis C virus (HCV) and MALT-type lymphomas has been suggested. However, studies assessing the role of HCV infection separately in different forms of MALT lymphomas are not available. PATIENTS AND METHODS: The prevalence and clinical implications of HCV seropositivity were analyzed in 55 patients with ocular adnexa lymphoma (OAL) of MALT-type. RESULTS: HCV seropositivity was detected in seven (13%) patients. At presentation, HCV infection was significantly associated with concomitant extra-orbital disease, lymph node dissemination and involvement of additional extranodal organs. HCV seropositivity was associated also with a higher relapse rate and worse progression-free survival. In fact, 16 patients experienced relapse after first-line treatment: five (71%) were HCV-seropositive and 11 (23%) were HCV-seronegative, with a median TTP of 31 and 50+ months (P = 0.01), and a 5-year progression-free survival of 43 +/- 18% and 77 +/- 7% (P = 0.005), respectively. HCV-seropositive patients experienced frequent relapses despite further lines of therapy; relapses were systemic in all cases but one; multiple subcutaneous nodules were common at relapse. CONCLUSIONS: HCV seropositivity is present in 13% of OAL of MALT-type. Concomitant HCV infection is associated with more disseminated disease and aggressive behavior in OAL, with a consequent potential negative impact in patients managed with radiotherapy alone.

Adult↗
PubMed2005

Repeated occurrence of diverse extended-spectrum beta-lactamases in minor serotypes of food-borne Salmonella enterica subsp. enterica.

Screening of Greek nontyphoid salmonellae from 2000 to 2002 yielded three extended-spectrum beta-lactamase (ESBL)-producing human isolates. Salmonella enterica serotype Brandenburg harbored a multiresistant SHV-5 gene-carrying plasmid. S. enterica serotype Blockley and S. enterica serotype Hadar harbored a TEM-52 gene-carrying plasmid. An S. enterica serotype Virchow strain producing plasmid-mediated CTX-M-32 was isolated twice from poultry end products. All ESBL plasmids were self-transferable and carried by clones currently common in Greece.

Aged↗
PubMed2004

[Indications, techniques, complications and results of sleeve lobectomy].

AIM: The authors analyse their personal series and compare it with reported data in order to assess the functional results sleeve lobectomy offers with respect to traditional techniques. METHODS: Sixty-six sleeve lobectomies were carried out from 1986 to 2000. In 49 cases the operation was carried out on the basis of criteria of choice and in 17 of functional necessity. Three vascular sleeves and 5 tangential vascular plastic operations were associated. The disparity of lumen was corrected with oblique sections on the intermediate bronchus according to Merendino. In the case of reimplantation of the intermediate on the left main bronchus high frequency jet ventilation was necessary. The anatomoses were covered with broad pedunculated pleural strips. In 3 cases extramucosal myectomy of the medio-thoracic esophagus was carried out associated in 1 case with mucous resection and subsequent direct suture. RESULTS: Morbility was 34.5% (21% atrial fibrillation, 7.5% parenchymal complications, 4.5% anastomotic complications and 1.5% mediastinitis). Mortality at 30 days was 6% (massive hemoptysis in 3 cases and respiratory failure in 1 case). The pTNM of the 57 survivors was IB in 35 cases, IIB in 6 and IIIA in 16. Follow-up showed 5-year survival of 62% for stage IB and 24% for stage IIIA. CONCLUSIONS: On the basis of their experience, with a postoperative mortality and a rate of complications comparable to literature data, the authors consider that sleeve lobectomy, although it presents postoperative problems requiring more prolonged clinical control, is preferable to traditional operations because of the functional advantages it offers patients with lung cancer.

Female↗
PubMed2004

[Intrathoracic omentoplasty in the treatment of pleural cavity secondary to stabilized bronchial fistula].

AIM: The aim of this paper was to verify the effectiveness of omentoplasty, either single or associated to other procedures, in the treatment of permanent fistula of the main bronchi. METHODS: The authors report their experience of 10 intrathoracic omentoplasties for pleural cavity from fistula of the main bronchus. In 2 cases a single omentoplasty was performed, while 8 patients had an associated procedure (4 thoracoplasties, 7 mioplasties and 2 mammoplasties). In 8 cases the vascular pedicle used for the omentum was the right gastroepiploic artery, and the left one in the remaining 2 patients. The omentum was mobilized through an opening in the diaphragm and anchored to the bronchial stump. In the combined plasties it was then covered by chest wall (thoracoplasty), muscles (mioplasty) or mammary gland (mammoplasty); in the single omentoplasty omentum was also sutured to the chest wall. Indication for combined procedures was high bacterial contamination of the pleural cavity; single omentoplasty was performed for small cavities, where other procedures had previously failed. Only in the single omentoplasties a pre-operative selective angiography of the gastroepiploic arteries was performed. RESULTS: Such procedures were resolutive in 9 patients; 1 needed an endoscopic application of fibrin glue. CONCLUSION: Intrathoracic omentoplasty is an effective procedure to solve both pleural cavity and stabilized bronchial fistula, mostly because of plastic and immunologic features of the omentum.

Bronchial Fistula↗
PubMed2004

The ''central'' quadrantectomy. Introducing a new reconstruction technique after excision of the central sub- and periareolar portion of the breast.

A new method is presented for the closure of a central cylindrical breast exeresis, embracing, full thickness, the skin and the gland. For this reconstruction, performed without altering the original shape of the breast, without removing any additional healthy tissue, we used a skin-gland flap rotated from the inferior quadrant to correct the defect.

Breast Neoplasms↗
PubMed2001

Crystallization and X-ray diffraction measurements of a thermophilic archaeal recombinant amidase from Sulfolobus solfataricus MT4.

Recombinant amidase is a 55.8 kDa enzyme from the thermophilic archaeon Sulfolobus solfataricus MT4 that catalyses the hydrolysis of aliphatic amides of 2-6 C atoms as well as many aromatic amides. Single crystals of purified amidase were obtained by the hanging-drop method at 294 K. Diffraction data for the native protein (2.55 A resolution) and a putative derivative (2.20 A) have been collected at low temperature using synchrotron radiation. The crystals belong to the rhombohedral space group R3. Structure determination by multiple isomorphous replacement is in progress. It is expected that structural information from this signatured thermostable amidase will increase our knowledge of the molecular mechanisms employed to maintain high-temperature stability in thermophilic proteins.

Amidohydrolases↗
PubMed2001

Molecular and biochemical characterization of the recombinant amidase from hyperthermophilic archaeon Sulfolobus solfataricus.

We have cloned, sequenced, and overexpressed in Escherichia coli the amidase gene from the hyperthermophilic archaeon Sulfolobus solfataricus (strain MT4). The recombinant thermophilic protein was expressed as a fusion protein with an N-terminus six-histidine-residue affinity tag. The enzyme, the first characterized archaeal amidase, is a monomer of 55,784 daltons, enantioselective, and active on 2- to 6-carbon aliphatic amides and on many aromatic amides, over the pH range 4-9 and at temperatures from 60 degrees to 95 degrees C. The S. solfataricus amidase belongs to the class of amidases that share a characteristic signature, GGSS(S/ G)GS, located in the central region of the protein, and which show remarkable variability in their individual substrate specificities, can hydrolyze aliphatic or aromatic substrates, and share a large invariance of their primary structure.

Amidohydrolases↗
PubMed2001

Effects of docosahexaenoic acid on retinal development: cellular and molecular aspects.

We have recently shown that docosahexaenoic acid (DHA) is necessary for survival and differentiation of rat retinal photoreceptors during development in vitro. In cultures lacking DHA, retinal neurons developed normally for 4 d; then photoreceptors selectively started an apoptotic pathway leading to extensive degeneration of these cells by day 11. DHA protected photoreceptors by delaying the onset of apoptosis; in addition, it advanced photoreceptor differentiation, promoting opsin expression and inducing apical differentiation in these neurons. DHA was the only fatty acid having these effects. Mitochondrial damage accompanied photoreceptor apoptosis and was markedly reduced upon DHA supplementation. This suggests that a possible mechanism of DHA-mediated photoreceptor protection might be the preservation of mitochondrial activity; a critical amount of DHA in mitochondrial phospholipids might be required for proper functioning of these organelles, which in turn might be essential to avoid cell death. Müller cells in culture appeared to be involved in DHA processing: they took up DHA, incorporated it into glial phospholipids, and channeled it to photoreceptors in coculture. Both Müller cells, when cocultured with neuronal cells, and the glial-derived neurotrophic factor (GDNF) protected photoreceptors from cell death. These results suggest that glial cells may play a central role in regulating photoreceptor survival during development through the provision of trophic factors. The multiple effects of DHA on photoreceptors suggest that, in addition to its structural role, DHA might be one of the trophic factors required by these cells.

Animals↗
PubMed2001

[Pleuro-pneumo-phreno-pericardiectomy with pericardial and diaphragmatic plasty].

Aim of the paper is to evaluate 43 extrapleural pneumonectomy performed from 1988 to May 2000. Criteria for extrapleural pneumonectomy were pleural biopsy by thoracoscopy, potentially completely resectable unilateral disease by computed tomography and predicted postresection forced expiratory volume >1,3 L/sec. The resections regarded 33 pleural mesothelioma, 9 pleural lung-carcinosis and 1 pleural melanoma effusion. The perioperative mortality rate was 2,2% (1 death) and morbidity 21,4%.

Diaphragm↗
PubMed2000

Protein stability in extremophilic archaea.

Extremophilic microorganisms have adapted their molecular machinery to grow and thrive under the most adverse environmental conditions. These microorganisms have found their natural habitat at the boiling and freezing point of water, in high salt concentration and at extreme pH values. The extremophilic proteins, selected by Nature to withstand this evolutionary pressure, represent a wide research field for scientists from different disciplines and the study of the determinants of their stability has been an important task for basic and applied research. A surprising conclusion emerges from these studies: there are no general rules to achieve protein stabilization. Each extremophilic protein adopts various strategies and the outstanding adaptation to extreme temperature and solvent conditions is realized through the same weak electrostatic and hydrophobic interactions among the ordinary amino acid residues which are also responsible for the proper balance between protein stability and flexibility in mesophilic proteins.

Adaptation, Physiological↗
PubMed1998

Cloning and sequencing of ISC1041 from the archaeon Sulfolobus solfataricus MT-4, a new member of the IS30 family of insertion elements.

A genomic fragment containing the insertion sequence ISC1041 has been cloned by PCR from the archaeon Sulfolobus solfaricus MT-4, an extremophilic microorganism which grows at 87 degrees C. The 1038 bp ISC1041 element contains an imperfect 18 nt repeat and a long open reading frame which encodes a polypeptide of 311 amino acid residues. The translated amino acid sequence shows a significant similarity to IS30-like transposases. Structural analysis indicates that ISC1041 is a novel member of the IS30 family and displays the DDE motif not previously seen in Archaea. This motif is believed to be involved in the integration mechanism of many mobile elements. As this motif is present in several integrases and transposases which, despite the lack of overall protein homologies, share topological homologies to the DDE motif, a common ancestor has been proposed. The finding of an IS30-like transposase in the archaeal kingdom may have relevance for horizontal gene transfer.

Amino Acid Sequence↗
PubMed1998

Protein thermostability in extremophiles.

Thermostability of a protein is a property which cannot be attributed to the presence of a particular amino acid or to a post synthetic modification. Thermostability seems to be a property acquired by a protein through many small structural modifications obtained with the exchange of some amino acids and the modulation of the canonical forces found in all proteins such as electrostatic (hydrogen bonds and ion-pairs) and hydrophobic interactions. Proteins produced by thermo and hyperthermophilic microorganisms, growing between 45 and 110 degrees C are in general more resistant to thermal and chemical denaturation than their mesophilic counterparts. The observed structural resistance may reflect a restriction on the flexibility of these proteins, which, while allowing them to be functionally competent at elevated temperatures, renders them unusually rigid at mesophilic temperatures (10-45 degrees C). The increased rigidity at mesophilic temperatures may find a structural determinant in increased compactness. In thermophilic proteins a number of amino acids are often exchanged. These exchanges with some strategic placement of proline in beta-turns give rise to a stabilization of the protein. Mutagenesis experiments have confirmed this statement. From the comparative analysis of the X-ray structures available for several families of proteins, including at least one thermophilic structure in each case, it appears that thermal stabilization is accompanied by an increase in hydrogen bonds and salt bridges. Thermostability appears also related to a better packing within buried regions. Despite these generalisations, no universal rules can be found in these proteins to achieve thermostability.

Adenylate Kinase↗
PubMed1995

[The role of surgery in the management of diffuse (N3) lung cancer].

The aim of the paper is to give a contribution to the understanding of the role of surgery in patients with N3 lung cancer. The A. describe their results on 32 patients with N3 lung cancer operated on mediastinectomy; histological examination of the specimens showed 27 squamous cell carcinomas and 5 adenocarcinomas. The operation was performed through a median sternotomy to gain access to the left and right paratracheal nodes, pretracheal, precarinal and subcarinal nodes, subaortic and left and right hilar nodes that were removed together with the fat of the mediastinum. Left pneumonectomy was performed in 5 patients. There was no operative mortality; 12 patients were irradiated in the postoperative period with 5,000 Rads (50 Gy), while 18 or the 27 patients with squamous cell carcinoma are still alive.

Adenocarcinoma↗
PubMed1995

[Tracheal sleeve lobectomy in the radical surgery for lung cancer].

Tracheal sleeve lobectomy is right upper lobectomy extended to include resection of the main bronchus, the carina and a segment of the trachea with end-to-end anastomosi of the trachea and end-to-side anstomosis of the intermediate bronchus on the main left bronchus, or the upper lobe on the trachea. This operation is possible with the aid of high frequency jet ventilation. The surgical indication of this operation is bronchoscopic and functional and guarantees a good oncological radicality in the presence of N0.

Anastomosis, Surgical↗