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Computational simulations of the spray combustion and emissions formation processes in a heavy-duty DI diesel engine and in a small-bore DI diesel engine with a complicated injection schedule were performed by using the modified KIVA3V, rel. 2 code. Some initial parameter sets varying engine operating conditions, such as injection pressure, injector nozzle diameter, EGR load, were examined in order to evaluate their effects on the engine performance. Full-scale combustion chamber representations on 360-deg, Cartesian and polar, multiblock meshes with a different number of sprays have been used in the modelling unlike the conventional approach based on polar sector meshes covering the region around one fuel spray. The spray combustion phenomena were simulated using the detailed chemical mechanism for diesel fuel surrogate (69 species and 306 reactions). The simulations have been performed for Isotta Fraschini (DI diesel, 7 sprays) and Volvo NED5 (DI diesel, 10 sprays) engines, which are currently under development. Numerical results were predicted in agreement with typical experimental trends for such engines.

The p16 gene, which encodes a physiological inhibitor of the cyclin D-CDK4 complex, is now considered as an important tumour-suppressor gene in a variety of tumours. A marked reduction of its expression has been reported to occur without significant genetic alterations in human pituitary adenomas, although rare point mutations of uncertain functional significance have been described. On the other hand, p16 gene silencing due to hypermethylation has been reported in several human primary tumours. The aim of this study was to further investigate the pathogenetic events leading to p16 gene inactivation in pituitary tumours.To screen a european series of human pituitary tumours for p16 gene alterations and possible gene hypermethylation.A representative series of 31 human pituitary tumours-30 macroadenomas, including a MEN-1 non-secreting pituitary adenoma and a non-MEN-1 familial giant GH-secreting adenoma, and one FSH-secreting pituitary carcinoma-was studied.Polymerase chain reaction/single strand conformation polymorphism (PCR-SSCP) analysis was used to screen for p16 gene alterations in all cases. Direct sequencing of PCR-products was obtained by the di-deoxynucleotide method where suspected abnormalities of the PCR-SSCP analysis were observed. In 24 samples, a methylation-specific PCR assay (MSP-PCR) was used to determine p16 gene methylation status.Two sporadic cases of pituitary adenomas had a similar single A to G base substitution leading to an heterozygous Ala140Thr p16 polymorphism, which has not previously been described in such tumours, but is known to be functionally silent. No other p16 abnormality could be suspected from PCR-SSCP analysis in this series. In contrast, the presence of methylated-specific PCR products was observed in 20/24 cases (83.3%).This study confirms that p16 gene mutations are not involved in the pathogenesis of human pituitary tumours, although polymorphisms can be demonstrated, depending on the population considered. In contrast, the high incidence of hypermethylation of the p16 gene suggests that such an alteration occurs early in pituitary tumours, and may play a role in pituitary tumorigenesis.

A retrospective review of 603 cases of intradural benign tumors of the cauda equina are presented (283 schwannomas and 320 ependymomas). For each tumor, the clinical course and long-term postoperative results were analyzed: it emerged that differential diagnosis between neurinomas and non tumoral lesions is not possible if based on clinical findings alone and that neuroradiological diagnosis is more accurate when MRI is employed. Long-term prognosis of neurinomas was always favourable, while in the ependymomas, early diagnosis gives excellent results because prognosis is apparently directly correlated to the length of preoperative clinical history.