Levels of CK MB mass in patients with acute myocardial infarct treatedwith fibrinolysis. Comparison with levels of CK, CKMB, CKMB mass and troponin T in the diagnosis of coronary ischemia]

In a group of 26 patients with AIM the CKMB value was raised above the discrimination level already on admission--on average 2.7 +/- 1.4 hours after development of ischaemic pain--in 46% patients. The maximal value of CKMB mass was achieved in the group with probable reperfusion 12.1 +/- 3.8 hours after the development of ischaemic pain and this value was elevated in relation to the discrimination value 41.5 +/- 17x and in relation to the so-called basal value 145 +/- 117x. In the group without probable reperfusion the maximal value was achieved significantly later, after 19.8 +/- hours and was elevated in relation to the discrimination value 31 +/- 17x and in relation to the final value 84 +/- 42 times. The value of CKMB mass increased above the discrimination limit from the onset of ischaemic pain after 4.0 +/- 1.5 and after 5.7 +/- 3 hours in the group with probable and without probable reperfusion and declined below the discrimination limit after 00 +/- 60 and 119 +/- 98.0 hours in the same groups. On comparison of CK, CKBM, CKBM mass and troponin T on admission the CKMB mass value was elevated in 46% patients, the value of CK in 23%, of CKMB in 27% and the troponin T value in 96% patients. With regard to the assembled experience that haemolytic serum raises false troponin T values, the percentage of elevated troponin T values on admission declines from the original 96% to 81% when all haemolytic samples are eliminated. The time of reaching maximal values of CKMB mass in patients with AIM and probable reperfusion was significantly shorter than in CK values and is similar as in CKMB values. The time taken to raise the CKBMB mass value above the discrimination value is significantly shorter than the time taken by CK levels, but significantly longer than the time before troponin T levels are raised. The time of total elevation of CKMB mass levels above the discrimination limit does not differ from the time taken to raise CK values, it is however shorter than the increase of troponin T values, although the exact time of persistence of raised levels of troponin T was not assessed in our work. The time of increase above and decrease below the discrimination limit was not assessed in CKMB values. Based on mutual comparison of the impact of indicators for assessment of the diagnosis of ischaemic heart attacks the authors consider it best regardless of financial costs--to assess troponin T, possibly along with levels of CKMB mass.     

Spread of excitation in 3-D models of the anisotropic cardiac tissue. III. Effects of ventricular geometry and fiber structure on the potential distribution

In a previous paper we studied the spread of excitation in a simplified model of the left ventricle, affected by fiber structure and obliqueness, curvature of the wall and Purkinje network. In the present paper we investigate the extracellular potential distribution u in the same ventricular model. Given the transmembrane potential v, associated with the spreading excitation, the extracellular potential u is obtained as solution of a linear elliptic equation with the source term related to v. The potential distributions were computed for point stimulations at different intramural depths. The results of the simulations enabled us to identify a number of common features which appears in all the potential patterns irrespective of pacing site. In addition, by splitting the sources into an axial and conormal component, we were able to evaluate the contribution of the classical uniform dipole layer to the total potential field and the role of the superimposed axial component.     

Novel insight into the copper-ligand geometry in the crystal structure of Ulva pertusa plastocyanin at 1.6-A resolution. Structural basis for regulation of the copper site by residue 88

The crystal structure of plastocyanin from a green alga, Ulva pertusa, has been determined at 1.6-A resolution. At its copper site, U. pertusa plastocyanin has a distorted tetrahedral coordination geometry similar to other plastocyanins. In comparison with structures of plastocyanins reported formerly, a Cu(II)-Sdelta(Met92) bond distance (2.69 A) is shorter by about 0.2 A and a Cu(II)-Sgamma(Cys84) distance is longer by less than 0.1 A in U. pertusa plastocyanin. These subtle but significant differences are caused by the structural change at a His-Met loop (His87-Met92) due to an absence of a O(Asp85)-Ogamma(Ser88) hydrogen bond which is found in Enteromorpha prolifera plastocyanin. In addition, poplar and Chlamydomonas reinhardtii plastocyanins with a glutamine at residue 88 have a weak cation-pi interaction with Tyr83. This interaction lengthens the Cu(II)-Sdelta(Met92) bond of poplar and C. reinhardtii plastocyanins by 0.14 and 0.20 A, respectively. As a result of structural differences, U. pertusa plastocyanin has a less distorted geometry than the other plastocyanins. Thus, the cupric geometry is finely tuned by the interactions between residues 85 and 88 and between residues 83 and 88. This result implies that the copper site is more flexible than reported formerly and that the rack mechanism would be preferable to the entatic theory. The His-Met loop may regulate the electron transfer rate within the complex between plastocyanin and cytochrome f.     

Anchor structure of staphylococcal surface proteins. III. Role of the FemA, FemB, and FemX factors in anchoring surface proteins to the bacterial cell wall

Surface proteins of Staphylococcus aureus are covalently linked to the bacterial cell wall by a mechanism requiring a COOH-terminal sorting signal with a conserved LPXTG motif. Cleavage between the threonine and the glycine of the LPXTG motif liberates the carboxyl of threonine to form an amide bond with the pentaglycyl cross-bridge in the staphylococcal peptidoglycan. Here, we asked whether altered peptidoglycan cross-bridges interfere with the sorting reaction and investigated surface protein anchoring in staphylococcal fem mutants. S. aureus strains carrying mutations in the femA, femB, femAB, or the femAX genes synthesize altered cross-bridges, and each of these strains displayed decreased sorting activity. Characterization of cell wall anchor structures purified from the fem mutants revealed that surface proteins were linked to cross-bridges containing one, three, or five glycyl residues, but not to the epsilon-amino of lysyl in muropeptides without glycine. When tested in a femAB strain synthesizing cross-bridges with mono-, tri-, and pentaglycyl as well as tetraglycyl-monoseryl, surface proteins were found anchored mostly to the five-residue cross-bridges (pentaglycyl or tetraglycyl-monoseryl). Thus, although wild-type peptidoglycan appears to be the preferred substrate for the sorting reaction, altered cell wall cross-bridges can be linked to the COOH-terminal end of surface proteins.     

Features of the fine structure of ferrite in hot-stamped powder steel. III. Application of methods of x-ray diffraction analysis for determining deformation nonuniformity in hot-stamped powder steel

Using x-ray methods of analysis together with approximating functions and Fourier coefficients the deformation nonuniformity of the structure in different parts of a samples of hot-stamped powder steel as a function of the composition and technological parameters of the process is determined. It is shown that the deformation nonuniformity of the structure grows with increasing alloyability of the material.     

Isozyme multiplicity with anomalous dimer patterns in a class III alcohol dehydrogenase. Effects on the activity and quaternary structure of residue exchanges at "nonfunctional" sites in a native protein

The isozymes of class III alcohol dehydrogenase/glutathione-dependent formaldehyde dehydrogenase from cod were characterized. They exhibited three unexpected properties of general interest. First, these dimeric isozymes, derived from two types of subunit (h and l, for high- and low-activity forms), were recovered from liver preparations in only the homodimeric ll and heterodimeric hl combinations. Dissociation and reassociation of the isolated hl form in vitro also resulted in lower yields of the hh than the ll homodimer, although class III subunits are usually freely associable over wide borders of divergence (human and Drosophila). The h and l primary structures show that both chain types are characteristic of class III enzymes, without large amino acid replacements at positions of known subunit interactions. Hence, the hh dimer partial restriction indicates nontraditional alterations at h-subunit interfaces. The structure provides a possible explanation, in the form of h-chain modifications that may influence the anchoring of a loop at positions of two potentially deamidative beta-aspartyl shifts at distant Asn-Gly structures. Second the ll and hl forms differ in enzymatic properties, having 5-fold different K(m) values for NAD+ at pH 8, different K(m) values for S-(hydroxymethyl)glutathione (10 versus 150 microM), and different specific activities (4.5 versus 41 units/mg), with ll resembling and hl deviating from human and other class III alcohol dehydrogenases. However, functional residues lining substrate and coenzyme pockets in the known conformations of homologous forms are largely identical in the two isozymes [only minor conservative exchanges of Val/Leu116, Val/Leu203, Ile/Val224, and Ile/Val269 (numbering system of the human class I enzyme)], again indicating effects from distantly positioned h-chain replacements. Third, the two isozymes differ a surprising amount in amino acid sequence (18%, the same as the piscine/ human difference), reflecting a remarkably old isozyme duplication or, more probably, discordant accumulation of residue exchanges with greater speed of evolution for one of the subunits (h chain) than is typical for the slowly evolving class III alcohol dehydrogenase.