Asunto(s)

RESUMEN

AIM: To assess the value of postmortem bacteriology in necropsy practice, with specific emphasis on bacterial invasion of blood and cerebrospinal fluid (CSF). METHODS: A review of published articles on postmortem bacteriology. Studies were selected to cover the full range of necropsy practice including adults, the perinatal period, and infancy. The review covers over 5000 necropsies, mainly in adults, but including 1108 perinatal cases and 468 cases of sudden unexpected death in infancy. Data are available on 4992 blood cultures, 1168 specimens of CSF, and 743 cultures of spleen. RESULTS: Studies in which careful precautions have been taken to reduce contamination show that approximately two thirds of blood cultures are negative, two in nine yield a single isolate, and one in nine have a mixed growth. The postmortem interval has only a small effect on the isolation rate. A pure growth of a known pathogen has a more than 50% likelihood of being found in association with genuine infection in adults and in the perinatal period. CONCLUSIONS: The main postmortem artefact is contamination, but this can be considerably reduced by careful technique. Agonal spread is less common than is often assumed. Postmortem translocation is not a problem if the body is appropriately stored. A pure growth of a pathogen in blood or CSF should be regarded as a possible contributing factor to death at all ages.

Asunto(s)

Asunto(s)

RESUMEN

Antibodies to human fetal aortic elastin were isolated from sheep immunized with alpha-elastin peptides. In preliminary tests of specificity using passive hemagglutination, partial cross-reactivity was demonstrated with alpha-elastin from other species. However, in a double antibody radio-immunoassay alpha-elastin peptides from other mammalian species failed to compete with 125I-labelled human alpha elastin. These results suggest the existence of at least two different antigenic sites on the elastin molecule. One, a high affinity site, demonstrates species specificity at low antigen/antibody concentrations. The other, a low affinity site, is common to mammalian elastins and is demonstrated at high antibody/antigen concentrations. In the radioimmunoassay the antibodies showed considerably less avidity for adult human alpha-elastin than for the fetal antigen. This implies that the species specific site is age-dependent and probably involves the cross-linking region of the elastin molecule. Using the sheep antiserum immunohistochemical staining of elastic tissue has been developed. This should prove to be a useful technique for studying polymeric elastin in intact tissue by light microscopy and at the ultrastructural level.

Asunto(s)

RESUMEN

Indirect immunofluorescence with a purified antiserum to human foetal elastin has identified newly synthesized elastin on the membranes of neoplastic epithelial cells in human mammary carcinoma.

Asunto(s)

RESUMEN

Soluble elastin was isolated from lathyritic chick aorta using neutral salt solutions in the presence of beta-amino propionitrile. The effect of a carboxy-methylation step in conjunction with proteolytic inhibitors was investigated. Hydrodynamic (Stokes) radii of soluble elastins were measured by gel filtration and the molecular size and weight distribution in purified fractions are reported.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

The coacervate phase produced by raising the temperature of solutions of blocked alpha-elastin has water content and fibrillar structure at electron microscope level similar to fibrous elastin (Cox, B.A., Starcher, B.C., Urry, D.W. (1973) Biochim, Biophys. Acta 317, 209-213). The stability ranges of the coacervates under varying conditions of temperature, pH, salt concentration and concentration of added organic solvent have been investigated with results that suggest a marked sensitivity of elastin conformation to solution conditions.

Asunto(s)

RESUMEN

Four extracellular proteolytic enzymes (I-IV) (EC 3.4.22.-) were identified in static cultures of Chromobacterium lividum (NCIB 10926) by agar gel electrophoresis and isoelectric focusing. Proteinases I-III were freed of non-enzymic protein by chromatography on TEAE-cellulose and CM-cellulose. The enzyme mixture was then fractionated in a pH gradient by isoelectric focusing. All three enzymes were shown to be heat-labile metallo-enzymes. Optimal activity occurred at pH 5.6 for enzyme I and at pH 6.2 for enzymes II and III. Remazolbrilliant Blue-hide powder was a sensitive substrate for these enzymes. Proteinase I was also shown to degrade haemoglobin and casein effectively, but not myoglobin, ovalbumin or bovine serum albumin. Proteinases I-III exhibited molecular weight values of 75 000, 72 000 and 67 000 by exclusion chromatography and 71 000 and 66 000 by sodium dodecyl sulphate-poly-acrylamide-gel electrophoresis for enzyme I and II, respectively. The amino acid compositions of enzymes I and II were somewhat similar. Proteinase I was inhibited by EDTA, 1,2-di(2-aminoethoxy)ethane-N,N,N',N'-tetraacetic activity. Mg2+ could substitute for Ca2+ or Mn2+ for Co2+. The interrelationship of proteinases I-III is discussed.

Asunto(s)

RESUMEN

A column packed with calcium-free bovine aorta elastin provided good separations of mixtures of bile salts when water was the moving phase. Tritium-labelled cholesterol was applied to the column using dilute solutions of taurodeoxycholate in Tris-NaCl buffers as solvent. The cholesterol was quantitatively eluted as a narrow peak in a rising gradient of taurodeoxycholate. When Na+ in the buffer was replaced by Ca2+ elution of the labelled cholesterol was delayed. Control experiments in which the elastin fibres were replaced as the column packing by an inert stationary phase consisting of n-butanol immobilized by silane-treated Celite showed that the effect of the change from Na+ to Ca2+ on the solvent properties of taurodeoxycholate was small and in the opposite direction. The experiments indicated that the replacement of sodium by calcium as the ionic environment of fibrous elastin produced a configurational change towards increasing hydrophobic character.

Asunto(s)

RESUMEN

The isolation of a salt-soluble homogeneous elastin from the aortas of lathyritic chicks by chromatography on DEAE-cellulose and salt precipitation is described. These new techniques, as well as some previously published by other workers, were evaluated with the help of antiserum raised in sheep against insoluble chick elastin. The purified elastin was very basic and behaved in a predictable manner in coacervation studies. The protein migrated in sodium dodecyl sulphate-polyacrylamide gels as a single band moving slightly faster than pyruvate kinase (mol.wt. 57000).

Asunto(s)

RESUMEN

This paper describes the isolation and amino acid analysis of un-cross-linked elastin obtained by neutral salt extraction from the ligamentum nuchae of a calf fed from birth to 9 months on a diet low in copper.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)