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L Righi

Publications and source records attributed to L Righi.

14 recordsLinked to original sources
PubMed2001

Neutron diffraction study of phi-Bi(8)Pb(5)O(17): structure refinement and analysis of cationic ordering.

The triclinic crystal structure of the varphi phase in the structure of the Bi(2)O(3)-PbO phase diagram has been recently solved by the synergetic use of electron and X-ray diffraction on a polycrystalline Bi(8)Pb(5)O(17) sample. In the present work the problem is re-examined on the basis of powder neutron diffraction data: the structure has been confirmed and refined by the Rietveld method. The increased accuracy of the O-atom positions allowed the study of the cationic ordering in this structure by means of bond-valence calculations and charge distribution analysis. The results, confirmed by the refinement of the site occupancies, indicate that the structure is ordered to a large extent, with Bi and Pb atoms occupying preferentially different lattice sites. In this frame, the varphi phase being the most ordered one in the considered region of the Bi(2)O(3)-PbO phase diagram, it should represent the thermodynamically stable low-temperature polymorph.

Journal Article↗
PubMed2001

An additional structural and electrical study of polymeric haloplumbates(II) with heterocyclic diprotonated amines.

The crystal structures of three polymeric bidimensional piperazinium, N,N'-dimethylpiperazinium, and N-benzylpiperazinium hydrate haloplumbates(II) and one polymeric monodimensional N,N'-dimethylpiperazinium hydrate haloplumbate(II) were determined by means of X-ray analysis. The (pipzH2)[PbCl4] salt is monoclinic, space group P2(1)/c, with a = 5.778(2) A, b = 22.612(26) A, c = 9.061(4) A, beta = 95.37(6) degrees, Z = 4; (me2pipzH2)[PbBr4] crystallizes in the monoclinic P2(1) space group with a = 6.101(3) A, b = 18.822(12) A, c = 6.229(2) A, beta = 98.62(4) degrees, Z = 2; the crystals of (me2pipzH2)2[Pb3I10].4H2O are monoclinic, space group P2(1)/c, a = 19.054(4) A, b = 12.239(3) A, c = 18.273(4) A, beta = 93.42(12) degrees, Z = 4; (benzpipzH2)3[Pb2Br10].2H2O crystallizes in the monoclinic P2(1)/c space group with a = 22.380(22) A, b = 9.304(15) A, c = 24.577(25) A, beta = 94.28(11) degrees, Z = 2. Different model type structures, such as one-dimensional linear chain, ribbonlike, and perovskite-like, were observed, and factors governing these structural arrangements are pointed out. The compounds were also investigated by means of thermal and electrical measurements, and correlations between electrical properties and crystal structures were noted.

Journal Article↗
PubMed2001

Expression of CD31 by cells of extensive ductal in situ and invasive carcinomas of the breast.

CD31, an adhesion molecule expressed by endothelial cells, leukocytes, and platelets, is used in surgical pathology as a marker of normal and neoplastic vascularization. During the assessment of angiogenesis in breast carcinomas, CD31 expression was observed in a single case of large (5.2 cm diameter) high nuclear grade ductal carcinoma in situ (HG-DCIS) associated with poorly differentiated invasive ductal carcinoma (G3-IDC). Expression was limited to the cell membrane. This study focused on 32 HG-DCIS> or = 2 cm, either pure or associated with IDC. Cancer cells wereCD31(+) in 11 cases. Double staining using anti-CD31 monoclonal antibody (MAb) and anti-CD44 MAb, the anti-hyaluronate receptor, showed that foci of CD31(+) and CD44(-) tumour cells could be traced throughout the glandular tree, marking the intraductal diffusion of tumour up to Paget's cells at the nipple. The associated G3-IDC and their lymph node metastases were instead CD31(+) and CD44(+). CD31(+) tumours were oestrogen receptor (ER)(-), frequently p53(+) and c-erb-B2(+), and infiltrated by CD4(+) T lymphocytes. Normal and hyperplastic epithelia were constantly CD31(-). Other endothelial markers (e.g Factor VIII-RA and CD34) were not expressed by carcinoma cells, as was CD38, the CD31 ligand. In conclusion, CD31 expression is a feature acquired by breast cancer cells in the DCIS model. CD31 expression mainly correlates with tumour cells spreading within the ductal system. Finally, the invasive phenotype requires the co-expression of CD31 and CD44.

Aged↗
PubMed2001

Expression of apocrine differentiation markers in neuroendocrine breast carcinomas of aged women.

Neuroendocrine (NE) breast carcinomas are a rare entity in young women; however, their frequency increases in aged patients. The present work demonstrates that NE breast carcinomas in elderly women can also express an apocrine immunophenotype and analyzes the histological and clinical aspects of such differentiation. A selected series of 50 NE tumors (positive for NE markers in >/=50% of the cells) was tested for the immunocytochemical expression of gross cystic disease fluid protein-15 (GCDFP-15). The results demonstrated that about 50% of moderately (G2) and well-differentiated (G1) NE breast carcinomas (mucinous, solid papillary, and solid cohesive histotypes) coexpressed the apocrine marker. In these cases, specific mRNA for GCDFP-15 (PIP) and for chromogranin A (ChA) was demonstrated using in situ hybridization (ISH). Carcinomas of the alveolar subtype (G2) and poorly differentiated carcinomas (G3), including one case of atypical carcinoid, were pure NE carcinomas, devoid of apocrine differentiation. The steroid receptor status of these lesions was evaluated to test a possible involvement of androgen receptors in apocrine differentiation. We demonstrated that the level of AR and the mean age of patients at diagnosis were significantly higher in apocrine than in nonapocrine differentiated tumors. The histological grade and the expression of estrogen receptor (ER) significantly influenced the prognosis of these NE carcinomas, either pure or NE-apocrine differentiated. The most original result of our study is therefore the demonstration of a possible divergent apocrine differentiation of NE breast carcinomas that might be regulated by the activation of androgen receptors in elder patients. In addition, the possibility for using Chs or GCDFP-15 serum values in the follow-up of these patients, as demonstrated in two cases of the present series, can justify the immunophenotyping of the tumors.

Adenocarcinoma, Mucinous↗
PubMed2001

Clinical significance of neuroendocrine carcinoma of the breast.

BACKGROUND: Neuroendocrine (NE) carcinomas of the breast are defined by the diffuse expression of NE markers. This definition includes lesions with 'pure' NE phenotype as well as 'variants' which may co-express mucinous and/or apocrine phenotype. In the present work, the clinical significance of pure' NE differentiation in breast carcinoma and of its 'variants' will be analyzed. MATERIALS AND METHODS: Forty-three NE breast carcinomas immunocytochemically positive for chromogranins and/or synaptophysin in > or = 50% of cells were graded following the Elston and Ellis grading system for breast carcinomas. The production of mucin and the expressionof the apocrine marker Gross Cystic Disease Fluid Protein-15 (GCDFP-15) were correlated with the grade and the hormonal receptor status. The clinical outcome of patients was also analyzed. RESULTS: The histological grade highly influenced the clinical evolution of NE breast carcinomas. We confirmed that mucinous differentiation is an important indicator of low biological aggressiveness. Estrogen and progesterone receptor expression was also correlated with a better prognosis. Presence of androgen was correlated with the expression of GCDFP-15 in NE tumors. CONCLUSIONS: The histological grade overcomes the immunophenotype in determining the prognosis of NE differentiated carcinomas of the breast. Co-expression of exocrine products in such tumors is related to hormone dependency.

Apolipoproteins↗
PubMed2001

34betaE12 cytokeratin immunodetection in the differential diagnosis of neuroendocrine carcinomas of the breast.

Neuroendocrine (NE) carcinomas of the breast share morphologic and immunohistochemical features with NE tumors of other sites, either resembling typical carcinoids or the highly aggressive small cell carcinoma. In addition, some mucinous carcinomas or solid/papillary carcinomas may show a major NE component. This is generally recognized by specific immunodetection of pan-endocrine markers, although this approach may fail to recognize NE tumors lacking immunoreactivity for some NE products, because the antigen is produced but not retained in the cytoplasm. It has recently been reported that high molecular weight (HMW) cytokeratin (CK), recognized by clone 34betaE12, immunostaining selectively labels non-NE carcinomas (squamous-cell and adenocarcinomas) of the aerodigestive tract and lung. The role of such CK immunodetection in the differential diagnosis of NE carcinoma of the breast was evaluated. Twenty-four cases of breast carcinomas having NE differentiation were selected. Twenty-four cases of non-NE invasive breast carcinomas served as controls. HMW CK immunoreactivity was found in all but one case of non-NE carcinomas, but in only two NE tumors (having scattered positive cells only). The authors conclude that in breast carcinomas the presence of HMW CK immunoreactivity favors the diagnosis of non-NE carcinoma, whereas its absence supports that of a NE tumor (either a carcinoid or a small cell carcinoma or a mucinous carcinoma). HMW CK can be added to the list of markers useful in the differential diagnosis of NE from non-NE tumors.

Biomarkers, Tumor↗
PubMed2001

Pseudokobusine.

The title compound, hetisan-6,11beta,15beta-triol, C20H27NO3, is a hetisane-type diterpenoid alkaloid. It consists of six six-membered rings and two five-membered rings. The fused-ring system contains three chair, two boat, one distorted boat and two envelope conformations. Intramolecular and intermolecular hydrogen bonds are present between the O atoms, with O...O separations of 3.006 (3) and 2.743 (3) A, as well as an O...N intermolecular interaction of 2.887 (3) A.

Bridged-Ring Compounds↗
PubMed2001

Aminopyrimidine-carboxyl(ate) interactions in trimethoprim maleate, an antifolate drug.

In the title cocrystal, trimethoprim maleate [2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium maleate], C(14)H(19)N(4)O(3)(+).C(4)H(3)O(4)(-), the trimethoprim molecule is protonated at N1. The carboxyl group of the maleate ion makes a specific double hydrogen bond of type N-H.O with the 2-amino group and the protonated N1 atom of the trimethoprim cation which is similar to the carboxylate-trimethoprim cation interaction observed in the complex of dihydrofolate reductase with trimethoprim. The pyrimidine moieties of trimethoprim cations are centrosymmetrically paired through a pair of N-H.N hydrogen bonds involving the 4-amino group and the pyridinium N3 atom of a symmetry-related molecule. One of the O atoms at the maleate carboxylate group bridges the 2-amino and 4-amino groups on either side of the paired trimethoprim cations. The other O atom of the carboxylate group forms an intramolecular O-H.O hydrogen bond with the carboxyl group. These characteristic hydrogen bonds result in infinite two-dimensional aggregation of rings into a supramolecular ladder, which is further crosslinked through weak C-H.O interactions with methoxy groups of neighbouring trimethoprim molecules to form a layered structure.

Crystallography, X-Ray↗
PubMed2000

Sperm washing and virus nucleic acid detection to reduce HIV and hepatitis C virus transmission in serodiscordant couples wishing to have children.

BACKGROUND: Use of a motile spermatozoa isolation process was assessed for reducing the transmission of HIV and hepatitis C virus (HCV) during artificial insemination in HIV-serodiscordant couples in which the man is infected. PATIENTS: Thirty-two HIV-1-infected clinically asymptomatic men, having a median CD4 cell count of 396 x 10(6)/l and a median blood plasma HIV-1 RNA content of 414 copies/ml. Of these, 16 were infected with both HIV and HCV. METHODS: Motile spermatozoa were isolated from 51 semen samples by density gradient and 'swim-up'. HIV-1 and HCV genomes were detected and quantified in the blood plasma and seminal plasma, and detected in seminal cell fractions obtained during spermatozoa isolation. RESULTS: HIV-1 RNA was detected in 30% of seminal plasma samples. HIV-1 genomes were found in 18% of seminal cell samples, but in none of the motile spermatozoa fractions after 'swim-up'. There was no correlation between the HIV-1 RNA concentrations in the blood and seminal plasma. HIV-1 genome was detected intermittently in patients who gave more than one sample. HCV RNA was detected in 20% of seminal plasma samples from HCV viraemic patients, but in no seminal cells or motile spermatozoa fractions. CONCLUSIONS: Purification of motile spermatozoa by density gradient plus 'swim-up' reduced the HIV-1 and HCV genomes in the semen of infected individuals to undetectable levels. This method, associated with a standardized virus assay, could be useful for serodiscordant couples (males infected) who wish to have children.

Adult↗
PubMed2000

Structure determination of phi-Bi8Pb5O17 by electron and powder X-ray diffraction

The triclinic crystal structure of phi-Bi8Pb5O17, a ionic fast conductor material, has been determined by the synergy of both electron and powder X-ray crystallography. The heavy atom positions were found by direct methods on electron diffraction data and the structure was completed by iterative use of a priori information in direct methods and difference Fourier maps on both types of data. Structure refinement was performed by the Rietveld method on powder X-ray data. The results suggest that phi-Bi8Pb5O17 is an ordered phase, with Bi and Pb atoms occupying different sites of the lattice, at variance with the other structural phases known for similar composition in the Bi-Pb-O phase diagram, which are solid solutions characterised by a wide compositional range.

Journal Article↗
PubMed2000

Expression of the neuroendocrine phenotype in carcinomas of the breast.

Neuroendocrine (NE) features are detectable in carcinomas of the breast either as scattered cells immunoreactive for NE markers in carcinoma of the usual type (NOS), or as special type of tumors where the vast majority of the cells display NE characteristics. The former type of lesions, whose biological and diagnostic significance is not clear yet, might reproduce the same phenomenon known to occur in carcinomas of the gastrointestinal tract and pancreas. In the present review we focus on the latter type of lesions, a spectrum of breast tumors largely composed of NE cells. These carcinomas, that we consider the "NE differentiated carcinomas of the breast," are here distinguished from "breast carcinomas NOS with NE differentiation." The diagnostic and histogenetic features of the various types of "NE differentiated carcinomas of the breast," their histological and cytological features and the role and value of ancillary diagnostic techniques, are reviewed. Data of the literature are discussed and related to a relatively large personal series. In addition, divergent differentiation in NE carcinomas of the breast, which is a relatively frequent phenomenon of diagnostic interest but of unknown significance (mainly involving mucinous intra- and extracellular production) is discussed.

Biomarkers, Tumor↗
PubMed1983

[Short-term prognostic evaluation of acute myocardial infarct: comparison of 2-dimensional echocardiography, electrocardiography, and the MB-CK index].

To compare the non-invasive methods of quantification of acute myocardial infarction (AMI) [two dimensional echocardiography (2DE), standard 12-leads ECG, and enzymatic indices as MB-CK peak activity and MB-CK time activity curve expressed by an extension index (EI-MBCK)] in relation to their prognostic value, 79 patients with a first AMI were evaluated. We have observed in a three months follow-up a total mortality of 12.6%. The infarct size, calculated echocardiographically by a segment score, was correlated with the number of pathological Q waves in the standard ECG (rho= 0.83). Peak MB-CK enzyme and EI-MBCK correlated both with the segment score, but with a lower correlation coefficient (rho= 0.67). To identify patients at different risk, discriminant analysis was used which gave the following limit values for the patients at a very high risk: 2DE score = 17; number of Q waves = 7; peak MB-CK = 176 U/L; EI-MBCK = 54 grEq/m2; for the patients at a very low risk: score = 6; number of Q waves = 2; peak MB-CK = 35; EI-MBCK = 15. To verify if the association of these different techniques could improve the predictivity, a discriminant bivariate function analysis with three variables was calculated. The resulting equation was: Z = 2.31 X 2DE score + 8.59 X number of Q waves - 0.23 X peak MB-CK. Changing peak MB-CK value with EI-MBCK did not improve the statistical significativity. The results have confirmed that the integration of all the three variables improved the prognostic predictivity. According to the risk Z obtained, the patients were allocated into classes of different risk: values of Z greater than 57 or less than 18 could identify patients respectively at a very high or at a very low risk. For values between 37 and 42 the prognosis remains uncertain. Among the three variables, 2DE and ECG showed an equivalent prognostic accuracy, whereas enzyme indices had a lower prognostic influence, especially in the presence of large infarcts. Thus, 2DE, ECG and enzyme indices can identify patients at increased risk; the individual method seems to be inadequate; to obtain valid predictive informations it is necessary to integrate all the three non invasive techniques.

Adult↗