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E Patrone

Publications and source records attributed to E Patrone.

At least 37 records · Page 2Linked to original sources
PubMed1986

A simple model for DNA elution from filters.

DNA chain scission, induced both in vitro and in vivo by various agents, is an event of great biological relevance. The damage is currently evaluated by empirical membrane separation techniques; the results are quite reproducible and the sensitivity higher than 1 single strand break per 10(9) Daltons. We outline a simple theory of the filtration of coiled macrosolutes, having a random size distribution, through porous membranes, considered as being in quasi-steady flow. The basic transport equation Jj = cj (1 - sigma)Jv is solved by considering that the value of sigma j, the reflection coefficient of component j, (1 less than or equal to j less than or equal to N), is given by (1 - KjRj), where Kj is the partition constant between pore and solution, a function of the conformational entropy loss of the coil, and Rj accounts for the frictional force experienced by a particle moving along the pore. The problem of evaluating the volume Vs filled up with solute has been approached according to a simplified theory of the excluded volume for flexible polymers; the result is Vs = sigma nj4/3 pi(rGj)3 where rGj is the jth radius of gyration. The solution of the resulting set of N differential equations gives nj, the number of molecules of component j remaining on the filter, as a function of the elution volume V. The theory demonstrates that the process is governed by the average dimensions of the coil, so affording a universal calibration of filter elution methods, in excellent agreement with the experiments.

Animals↗
PubMed1983

Quaternary and quinternary structures of native chromatin DNA in liver nuclei: differential scanning calorimetry.

Differential scanning calorimetry of chromatin isolated from rat liver cells revealed three discrete thermal transitions whose temperatures and melting enthalpies depend on ionic strength in the range 0 to 600 millimolar NaCl. Intact nuclei showed a fourth thermal transition at a lower temperature and different melting enthalpies for the other three transitions still present at temperatures similar to those obtained in isolated chromatin. The data are discussed in terms of the tertiary, quaternary, and quinternary structures of chromatin DNA.

Animals↗
PubMed1983

Higher-order structure of chromatin from resting cells. II. High-resolution computer analysis of native chromatin fibres and freeze-etching of nuclei from rat liver cells.

Non-destructive electron microscopy of native chromatin from rat liver nuclei reveals that the 30 nm fibre is formed of four 11 nm nucleofilaments, arranged in a coiled-coil (or rope-like) conformation. At low ionic strength, native fibres show an alternating pattern of compact and unwound regions. Freeze-etching experiments carried out on the same nuclei are compatible with the existence of periodic attachments of the fibres to the nuclear envelope near the pores in a regular, drapery-like fashion. For the first time, computer image analysis has been applied to electron micrographs of giant chromatin fibres and a few essential geometrical parameters characterizing the conformation of the higher-order structures have been determined. No significant difference has been found between calf thymus and rat liver chromatin.

Animals↗
PubMed1983

Higher-order structure of chromatin from resting cells. I. Electron microscopy of chromatin from calf thymus.

Extremely large domains of the genome of resting cells (calf thymus) have been visualized in the electron microscope by combining mild extraction procedures with a non-artifactual method of mounting the sample (the phospholipid monolayer technique). The observed chromatin strands, free from distortion, reach contour lengths up to 60 micrometers. After lysis of the nuclei, four classes of fibres may be identified on the basis of their diameters (30, 24, 18 and 11 nm, respectively). The morphology of giant chromatin strands is strikingly regular; long trains of equally sized, arc-shaped segments are observed, their length being, in many cases, multiples of a fixed value. The inflection points delimiting contiguous segments are often associated with laminar fragments of the nuclear envelope or, less frequently, linked to fibrillar elements. It appears that higher-order structures of chromatin in resting cells conform, to a large extent, to a so called 'drapery-like' mode, according to which a continuous strand runs between contiguous anchorage sites placed on the nuclear envelope. Because of the presence of regularly spaced inflection points, this organization is much more ordered than expected. Spontaneous unwinding of the fibres at low ionic strength, limited nuclease digestion, and relaxation in the presence of ethidium bromide, have been used as probes of the conformation. All these experiments rule out its identification with a single-strand helix. The final ordered state is attained by folding the basic 11 nm strand and by winding up this configuration on itself. This leads to a coiled-coil or 'rope-like' model. The 11 nm strand is 'punctuated' by sharp kinks. Roughly, it may be assimilated to a chain of semirigid, freely joined elements. As a consequence, local flexibility is greatly enhanced, so allowing the assembly mode described.

Animals↗
PubMed1980

Isolation and characterization of multiple forms of renin from bull kidney.

Different forms of renin have been purified from bull kidney by combined gel filtration, affinity chromatography and ion-exchange chromatography. The specific activity of the enzyme was determined by a biochemical method of synthetic substrate and by radioimmunoassay on both synthetic and natural substrates; molecular characterization was carried out by molecular weight determinations, polyacrylamide gel electrophoresis, isoelectric focusing, amino acid analysis and optical rotatory dispersion. Three forms (renin C, D, E) are distinct on the basis of amino acid composition and chromatographic behavior, while possessing the same molecular weight, and displaying only minor differences in specific activity, alpha-helix content and isoelectric point; the occurrence of a group of renin isoenzymes may be suggested. Another form (A) has a lower specific activity and a higher molecular weight (57 000) compared with C, D and E and further differs markedly in chromatographic behavior, amino acid composition, alpha-helix content and isoelectric point, as well as in substrate specificity; it may be regarded as a pseudorenin. The fifth form (B) possesses the highest specific activity and does not correspond to a single molecular form; the presence of two components of different molecular weight (27 000 and 46 000 respectively) has been established both by polyacrylamide gel electrophoresis and isoelectric focusing.

Amino Acids↗
PubMedDate not supplied

Conformation dependent pro-apoptotic activity of the recombinant human prion protein fragment 90-231.

The transition of prion protein from a mainly alpha-structured isoform (PrPC) to a beta sheet-containing protein (PrPSc) represents a major pathogenetic mechanism in prion diseases. To study the role of PrP structural conformation in prion-dependent neurodegeneration, we analysed the neurotoxicity of PrP in alpha and beta conformations, using a recombinant protein encompassing amino acids 90-231 of the human PrP (hPrP90-231). Using controlled thermal denaturation (53 degrees C, 1h) we converted hPrP90-231 in a structural isoform displaying PrPSc-related characteristics: high beta sheet content, increased aggregability and a slight increase in the resistance to protease K. In virtue of these structural changes, hPrP90-231 powerfully affected the survival of SH-SY5Y cells, inducing a caspase-3 and p38- dependent apoptosis. Conversely, in the native alpha-helix-rich conformation, hPrP90-231 did not show significant cell toxicity. The relationship between the structural state of hPrP90-231 and its neurotoxicity was demonstrated, inducing the thermal denaturation of the peptide in the presence of Congo red that prevented both the transition of hPrP90-231 into a beta-rich isoform and the acquisition of toxic properties. In conclusion, we report that the toxicity of hPrP90-231 is dependent on its three-dimensional structure, as is supposed to occur for the pathogen PrP during TSE.

Amyloid↗
PubMedDate not supplied

[Efficacy and safety of simvastatin in the treatment of hyperlipidemia in uremic patients undergoing hemodialysis treatment].

The efficacy, tolerability and safety of simvastatin in the treatment of hyperlipemia in uremic patients undergoing hemodialysis were evaluated in 6 patients; a further 6 patients were treated with placebo and represented the control group. All patients treated completed the study. No clinical or laboratory side-effects were noted during the entire period of observation. Simvastatin caused a significant 26% reduction in total cholesterol, a 36% reduction in LDL cholesterol and a 28% reduction in triglycerides; HDL cholesterol and Apolipoprotein A increased by 19% and 12% respectively.

Aged↗