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Biomedical subjects

B Carrozzini

Publications and source records attributed to B Carrozzini.

8 recordsLinked to original sources
PubMed2003

Solving non-periodic structures using direct methods: phasing diffuse scattering.

The problem of reconstructing the charge density of a non-periodic sample from its diffuse X-ray scattering is considered. For a sample known to be isolated, an artificial superlattice may be assumed and the numerical direct methods of crystallography applied to the continuous distribution of diffuse scattering in order to solve the phase problem. This method is applied to simulated soft-X-ray transmission speckle patterns from a two-dimensional array of gold balls of 50 nm diameter. The results are relevant to efforts to phase the scattering from many individual macromolecules that cannot be crystallized, and to the scattering from individual inorganic nanoparticles.

Journal Article↗
PubMed2000

SIR2000, a program for the automatic ab initio crystal structure solution of proteins.

A new phasing procedure is described working both in direct and in reciprocal space. The procedure has been implemented into the program SIR2000, the heir to SIR99, and it is able routinely to solve ab initio crystal structures of proteins without any use of prior information and any user intervention. The moduli and the flow diagram of SIR2000 are also described and its efficiency tested on several protein diffraction data sets. Success has been attained for crystal structures with up to almost 2000 non-hydrogen atoms in the asymmetric unit and resolution higher than 1.2 A. The phasing process is analysed to provide a better insight into the role of the various steps of the procedure.

Crystallography↗
PubMed1999

The joint probability distribution function of structure factors with rational indices. VI. Cases with reduced dimensionality.

The probabilistic formulas relating standard and mixed type reflections (these last show integral and half-integral indices) are derived. It is shown that probabilistic estimates can be obtained by using particular sections of the three-dimensional reciprocal space. The concept of structure invariant is extended to define the wider class of structure quasi-invariant. Their statistical behaviour is briefly discussed with the help of some practical tests.

Journal Article↗
PubMed1999

SIR99, a program for the automatic solution of small and large crystal structures.

The moduli and flow diagram of the program SIR99 are described. New phasing algorithms are proposed working both in direct and in reciprocal space. Their cooperative work is able to solve the structures of both small and large molecules. In particular, small proteins can be solved ab initio without any use of prior information and any user intervention. The efficiency of the various algorithms employed by SIR99 has been tested, and the role of the tangent formula clarified. The user is also provided with some practical information concerning the computer power needed.

Journal Article↗
PubMed1999

The probability distribution of structure factors with non-integral indices. II. The P1; case.

The probability distribution of the structure factors with non-integral indices is derived in P1;. For integral values of at least one of the indices, the intensity distribution coincides with that provided by Wilson's statistics, but may strongly differ when the indices are (or are close to) half-integers. The deviations are stronger when the integral part of the indices is small, and increase with the size of the structure. In favourable circumstances, moduli and phases of the reflections may be accurately estimated.

Journal Article↗
PubMed1982

[Therapy of hepatic diseases with alpha-mercaptopropionylglycine].

Thiopronine has been used to treat 88 patients suffering from chronic hepatitis (65), liver cirrhosis in ascitic phase (14), alcoholic hepatosis(5) and acute hepatitis (4). The drug was employed at the attack stage i.v. at a daily dose of 1-2 grams, and at maintenance phase orally at a dose of 0.750-1 gram. It led to a gradual, significant improvement in clinical symptomatology and hepatofunctional haematochemical indices in all chronic forms, only decompensated cirrhosis showing a slight regression. In hepatic forms, normalisation of subjective and objective parameters was particularly fast, between the 4th and 7th days. Tolerance was very good in 98% of cases.

Amino Acids, Sulfur↗