Un particolare metodo per la determinazione di autovalori di matrici tridiagonali simmetriche

In this paper we given an algorithm of low computational complexity which determines the eigenvalues of a symmetric tridiagonal matrix. The algorithm uses the technique of spectrum slicing together with methods for finding the zeros of polynomials. An application of algorithm for computing Gauss quadrature formulas is given.

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Lavoro svolto nell'ambito del Gruppo Nazionale di Informatica Matematica del C.N.R.     

Flow-cytometric detection of the RI alpha subunit of type I cAMP-dependent protein kinase in human cells

cAMP-dependent protein kinase (PKA) is composed of two genetically distinct catalytic (C) and regulatory (R) subunits. There are two different classes of PKA, designated as type I and type II, which contain distinct R subunits (RI or RII, respectively) but share a common C subunit. Enhanced expression of type I PKA has been correlated with cell proliferation and neoplastic transformation. Detection of the different PKA subunits is usually performed by photoaffinity labeling with 8-N3-32P-cAMP or by radioimmunolabeling techniques. Both techniques are time consuming and require a high number of cells and the use of radioactive reagents. Using the MCF-10A normal human mammary cell line infected with a recombinant retroviral vector containing the human RI alpha gene (MCF-10A RI alpha), we have developed a flow-cytometric assay to detect the intracellular content of RI alpha protein in human cells. MCF-10A and MCF-10A RI alpha cells were fixed in 1.5% paraformaldehyde at 37 degrees C for 15 min and permeabilized by methanol and acetone (1:1) at -20 degrees C for 5 min before staining with a specific IgG2a MoAb followed by a FITC-conjugate rabbit-anti mouse IgG. This procedure was also successfully utilized to recognize RI alpha protein content in human peripheral blood lymphocytes. Flow-cytometric detection of the RI alpha subunit in human cells is feasible and allows the study of the role of type I PKA in cell growth and neoplastic transformation.     

Artificial neural network identification of heterotrophic marinebacteria based on their fatty-acid composition

The traditional approach to biochemical identification of marine fresh isolates requires considerably long culture preparation times and large quantities of expensive materials and reagents, and the results are not very reliable. On the other hand, taxonomy tests based on DNA composition, although sensitive and reliable, require long execution times and high costs, A method is presented for the classification of fatty-acid profiles, extracted from marine bacteria strains, at genus level based on supervised artificial neural networks. The proposed method allows the correct identification of all patterns belonging to the training set and almost all patterns belonging to the test set. Moreover, a quantitative measure of the importance of each fatty acid for bacterial classification is also achieved. This measure allows the determination of a cluster of fatty acids to be controlled with greater care. The results show that the proposed method is reproducible and rapid, so that it can be routinely used in the marine microbiology laboratory to identify fresh isolates     

Presence of a non-NMDA glutamate receptor subtype in the sympathetic nervous system of neonatal swine

Calcium-dependent protein kinases (CDPKs) in plants are characterized by a four-domain structure including conserved sequences in the catalytic domain, and in the C-terminal calmodulin-like domain. Based on this conservation we have PCR-amplified and isolated a potato cDNA clone (StCPK1) from a library representing an early stage of tuber development. DNA sequence analysis revealed that in the catalytic domain, StCPK1 shares more homology with CDPK-related kinases than with CDPKs; however, like CDPKs, it possesses canonical EF-hands at the calmodulin-like 3' end. StCPK1 exists in a few copies in the potato genome and is abundantly expressed in the sepals of mature flowers. Floral expression of genes homologous to StCPK1 appears to be widespread in the family Solanaceae.     

The IL-6 gene expression by leukemic cells from acute lymphoblastic leukemia common and T type and modulation of IL-6 production by TNF

The tumour necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) mRNA accumulation and the release of the cytokines TNF-alpha and IL-6 was determined in leukemic cells isolated from bone marrow biopsy from patients with acute lymphoblastic leukemia: ALL-common type (cALL), 11 patients; ALL-T type, nine patients. The non-leukemic bone marrow cells (BMMC) and peripheral blood mononuclear cells (PBMC) from healthy donors were used as a control. The mRNA was assessed by fluorescent in situ hybridization in cell suspension and analyzed with flow cytometry. The accumulation of cytokine mRNA was higher in cALL cells as compared to ALL-T and PBMC (control) and was comparable to cytokines mRNA accumulation in BMMC. The production of IL-6 by leukemic cells from both types of leukemia was significantly lower than in BMMC. The bioactive TNF was not detected in either of the leukemia groups studied. TNF-alpha protein was produced by ALL-T cells and BMMC but not by cALL type of leukemic cells. The synthesis of IL-6 was significantly enhanced by TNF-alpha in BMMC and ALL-T while the presence of TNF-alpha had no effect on IL-6 synthesis in the culture of cALL leukemic cells. It was concluded that despite IL-6 and TNF-alpha mRNA contents, leukemic cells representing early stage of B-cell development (CD10+) showed disregulation of production of these cytokines.     

Homer regulates the association of group 1 metabotropic glutamate receptors with multivalent complexes of homer-related, synaptic proteins

OBJECTIVE: The study aimed to assess the frequency, indications, and outcome of additional ocular procedures after initial treatment of vitrectomy (VIT) or tap-biopsy (TAP) for patients with endophthalmitis after cataract extraction. DESIGN: The study design was an analysis of observational data collected as part of a multicenter, randomized clinical trial. PARTICIPANTS: Of the 420 patients enrolled in the Endophthalmitis Vitrectomy Study, the 148 who had additional procedures were compared with the 272 who did not. MAIN OUTCOME MEASURES: The types, indications, and number of additional ocular procedures were assessed. A masked examiner measured visual acuity 9 to 12 months after study entry. RESULTS: Within 1 week of study entry, 8% of VIT eyes and 13% of TAP eyes underwent additional procedures, 14% for complications of the initial procedure and 86% for worsening ocular inflammation or infection. Cultures were obtained in 33 of the 38 eyes operated on for worsening inflammation or infection and were positive in 42%. Cultures obtained from the early additional procedures were positive more frequently in eyes with an initial TAP (71%) than in eyes with an initial VIT (13%). Both virulence of initial microbiologic organism isolated and poor presenting vision were risk factors for requirement of reoperation. In all cases in which a single organism was cultured at the initial procedure, when the reculture was positive, it was the same organism. Late additional procedures (after 7 days) were required in 27% of patients. Visual outcome was much worse for eyes that had an additional procedure compared to eyes that did not, and this was especially the case for eyes that had an early additional procedure. Only 15% of eyes that had an early additional procedure achieved 20/40 visual acuity as compared to 57% of eyes that did not. CONCLUSION: Need for an additional procedure was a marker of more severe disease, and patients who underwent additional procedures achieved poorer visual acuity at final follow-up.     

Why minority group members perceive or do not perceive the discrimination that confronts them: The role of self-esteem and perceived control.

Self-esteem and perceived control were examined to explain why minority group members sometimes perceive discrimination but, more often, minimize the discrimination. Women (Study 1), and Asians and Blacks (Study 2) reacted to negative feedback after information about the probability for discrimination. Minority group members tended to minimize discrimination and attributed their failure to themselves. By perceiving discrimination as a reason for failure, minority group members protected their performance state self-esteem. In contrast, by minimizing discrimination, they protected their social state self-esteem and maintained the perception of control in the performance and social domains. Results suggest that minority group members minimize discrimination because the consequences of doing so are psychologically beneficial. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Partial purification and some properties of wheat (Triticum aestivum) o-diphenolase

o-Diphenolase extracted from Triticum aestivum (cv. Nettuno) and purified in various steps gave a 250-fold purification over the crude extract. This purified enzyme showed maximum relative activity towards 4-methylcatechol, generally high or moderate activity towards di- and polyphenols, and very low activity towards monophenols. Total activity, determined at each step of purification, showed that treatment with ammonium sulphate and calcium phosphate gel gave rise to an activation of o-diphenolase, thus revealing a latency of enzymatic activity. In the pH profile activity towards 4-methylcatechol two optima at pH 5.3 and 6.9 were observed.