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Biomedical subjects

G Leone

Publications and source records attributed to G Leone.

At least 217 records · Page 12Linked to original sources
PubMed1997

[Evaluation of the respiratory function by lung scintigraphy in patients candidates for pulmonary resection].

Sixty-one patients undergoing pulmonary resection were studied pre- and post-operatively by spirometry, arterial gas determination, and quantitative ventilation/perfusion lung scanning. Our results showed that ventilation and/or perfusional scintigraphic scanning is currently the most reliable method in identifying patients at risk for postoperative respiratory insufficiency. Specifically, this technique was successful in detecting pulmonary areas other than those to be resected presenting ventilation or perfusional abnormalities. Therefore, the technique is particularly useful in predicting residual pulmonary function.

Adult↗
PubMed1996

Co-translational trimerization of the reovirus cell attachment protein.

The reovirus cell attachment protein, sigma1, is a trimer with a 'lollipop' structure. Recent findings indicate that the N-terminal fibrous tail and the C-terminal globular head each possess a distinct trimerization domain. The region responsible for N-terminal trimerization (formation of a triple alpha-helical coiled-coil) is located at the N-terminal one-third of sigma1. In this study, we investigated the temporality and ATP requirement of this trimerization event in the context of sigma1 biogenesis. In vitro co-synthesis of the full-length (FL) and a C-terminally truncated (d44) sigma1 protein revealed a preference for homotrimer over heterotrimer formation, suggesting that assembly at the N-terminus occurs co-translationally. This was corroborated by the observation that polysome-associated sigma1 chains were trimeric as well as monomeric. Truncated proteins (d234 and d294) with C-terminal deletions exceeding half the length of sigma1 were found to trimerize post-translationally. This trimerization did not require ATP since it proceeded normally in the presence of apyrase. In contrast, formation of stable FL sigma1 trimers was inhibited by apyrase treatment. Collectively, our data suggest that assembly of nascent sigma1 chains at the N-terminus is intrinsically ATP independent, and occurs co-translationally when the ribosomes have traversed past the midpoint of the mRNA.

Adenosine Triphosphate↗
PubMed1996

C-terminal trimerization, but not N-terminal trimerization, of the reovirus cell attachment protein Is a posttranslational and Hsp70/ATP-dependent process.

The C-terminal globular head of the lollipop-shaped final sigma1 protein of reovirus is responsible for interaction with the host cell receptor. Like the N-terminal fibrous tail, it has its own trimerization domain. Whereas N-terminal trimerization (formation of a triple alpha-helical coiled coil) occurs at the level of polysomes (i.e. cotranslationally) and is ATP-independent, C-terminal trimerization is a posttranslational event that requires ATP. Coprecipitation experiments using anti-Hsp70 antibodies and truncated final sigma1 proteins synthesized in vitro revealed that only regions downstream of the N-terminal alpha-helical coiled coil were associated with Hsp70. Hsp70 was also found to be associated with nascent final sigma1 chains on polysomes as well as with immature postribosomal final sigma1 trimers (hydra-like intermediates with assembled N termini and unassembled C termini). These latter structures were true intermediates in the final sigma1 biogenetic pathway since they could be chased into mature final sigma1 trimers with the release of Hsp70. Thus, unlike N-terminal trimerization, C-terminal trimerization is Hsp70- and ATP-dependent. The involvement of two mechanistically distinct oligomerization events for the same molecule, one cotranslational and one posttranslational, may represent a common approach to the generation of oligomeric proteins in the cytosol.

Adenosine Triphosphate↗
PubMed1996

Multiple ocular impairment in a patient affected by Waldenström's macroglobulinaemia.

BACKGROUND: We studied a bilateral tumefaction of the lacrimal gland in a female patient. METHOD: Ocular and general clinical examinations were carried out. RESULT: Computerized tomography (CT) of the cranial orbit showed a tumefaction of solid density in the lacrimal gland. Histological examination of material removed by needle aspiration revealed the presence of elements of a lymphoplasmacytoid nature. Fluorescein angiography showed dilatation of the veins, intraretinal flame haemorrhages and small ischaemic areas. Chest CT showed an increase in the size of the middle and upper mediastinal lymph nodes, and examination of a specimen of bone marrow from the chest revealed the presence of small lymphocytes with a plasmacytoid tendency. CONCLUSION: On the basis of the findings, we diagnosed Waldenström's disease with rare multiple ocular impairment (lacrimal gland and retina) in an early stage.

Aged↗