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Biomedical subjects

H Sigel

Publications and source records attributed to H Sigel.

At least 73 records · Page 4Linked to original sources
PubMed1981

The coordinating properties of d-biotin.

The coenzyme d-biotin offers in its anionic form to metal ions 3 possible binding sites: the carboxylate group of the valerate side chain, the ureido residue of the 2-imidazolidone ring, and the thioether sulfur of the tetrahydrothiophene ring; the coordinating properties of these groups are summarized and compared. Hydrogen bond formation of the ureido group has also been observed, and hydrogen bonding may possibly be important in biotin-bicarbonate recognition. The aliphatic part of the valeric acid side chain can undergo hydrophobic interactions. Such interactions and/or the stereoselective sulfur-metal ion coordination could be the means for a correct 'fixation' of the biotinyl moiety at the surface of a protein, thus creating the active enzyme-substrate complex.

Binding Sites↗
PubMed1981

[Quantitative left ventriculography: comparative investigations in normal patients (author's transl)].

In 17 patients with no demonstrable cardiac disease, analysis of the ventriculogram with respect to regional wall motion was performed. These normal patients formed the basis for establishing the normal ranges for 6 different methods of regional wall motion analysis (3 chord, 2 radial, 1 area). In each method, analysis of regional shortening showed a Gaussian distribution. The normal range of a segment was defined as the mean +/- 2 standard deviations, hence comprising 95% of normals. Comparing our 6 normal ranges with the ranges as initially described by their respective authors, the general shape of our curves was largely in agreement with the original curves. In detail, the amount of regional shortening showed some discrepancies, and only our normal range curve, calculated according to the method of Leighton, was highly comparable to the original range of the author, as well as to the one of Brower. Reasons for the discrepancies using other methods may be accounted for by different catheter conditions, different patient material and a subjective variation in delineating the contours of diastole and particularly of systole. It is concluded that normal ranges of a method for wall motion analysis cannot be applied directly from the literature without their prior verification under the special conditions of the angiographic technique and evaluation used.

Heart Ventricles↗
PubMed1981

[Assessment of left ventricular regional function by means of radioactive isotopes (author's transl)].

Extensive analysis of heart function by scintigraphy yields global parameters of ventricular volumes and their changes during the heart cycle (ejection fraction, enddiastolic and endsystolic volumes, velocity of contraction and relaxation). Additionally, information regarding localized disorders of wall motion may be obtained in a qualitative and quantitative manner by the parameters "phase" and "amplitude". These parameters can be computed from regional time-activity curves by Fourier analysis. The radionuclide ventriculogram at rest is suitable for the detection and follow-up of asynergies caused by acute and chronic infarction. In can also be used as a method of distinguishing between reversible and irreversible asynergy by therapeutical intervention (intervention ventriculography). Abnormalities of regional wall motion which develop during exercise may indicate hemodynamically relevant coronary artery stenoses.

Cardiac Output↗
PubMed1981

[Quantitative evaluation of regional and global parameters of left ventriculography with different methods in an intra- and interobserver test (author's transl)].

In 17 patients without evidence of regional wall motion abnormality a determination of the variation of global and regional parameters of two contour delineations was attempted by the same (intraobserver) and by an independent observer (interobserver). In the intraobserver comparison all computed comparison all computed parameters showed excellent correlation coefficients: enddiastolic volume (EDV) r = 0.97, endsystolic volume (ESV) r = 0.94, ejection fraction (EF) r = 0.93. In the interobserver comparison, the correlations were slightly lower (EDV: r = 0.94, ESV: r = 0.93, EF: r = 0.85). Absolute differences in volumes and ejection fractions were for the EDV 3.0 +/- 11.8 ml (+/- 1 SD), for the ESV 2.6 +/- 4.9 ml, and for EF 1.9 +/- 4.1%. Additionally, the three contour tracings were subjected to an analysis of regional wall motion using nine different methods. With most of the methods applied, the analysis showed areas near valves and the cardiac apex, where small changes in contour tracings resulted in statistically significant differences in wall motion (p less than 0.05). Therefore, using each method described, it was possible to determine, which regions demonstrated the greatest variation in interpretation of quantitative regional wall motion. Finally we conclude, that enddiastolic and endsystolic volumes and ejection fraction can be subjected to repeated estimation by the same or an independent observer with sufficient accuracy.

Cardiac Volume↗
PubMed1980

[On the perforation of central venous catheters; radiological aspects of diagnosis and prevention (author's transl)].

Three cases of cardiac tamponade resulting from perforation of central venous catheters are presented. Purpose of the case reports and of the brief literature review is to derive criterions for X-ray examination of the catheter position since only routine roentgenographic control can prevent the occurrence of catheterization -- induced complications significantly. The catheter tip should not exceed the right sternoclavicular border by more than two centimeters. Roentgenograms of catheters inserted via the brachial venous route have to be obtained with the arm abducted 90 degrees. On adequately exposed Roentgen films the vertebral column should be clearly discernible within the cardiac shadow. Injection of radiopaque dye through the catheter helps to locate its tip and, in addition, confirms the diagnosis of catheter perforation and concomitant pericardial tamponade.

Barbiturates↗
PubMed1980

Metal ion/buffer interactions. Stability of binary and ternary complexes containing 2-[bis(2-hydroxyethyl)amino]-2(hydroxymethyl)-1,3-propanediol (Bistris) and adenosine 5'-triphosphate (ATP).

The acidity constant of protonated 2-[bis(2-hydroxyethyl)amino]-2(hydroxymethyl)-1,3-propanediol (Bistris) has been measured. The influence of hydroxo groups on the basicity of Bistris and related bases is discussed. The interaction of Bistris with the metal ions (M2+) Mg2+, Ca2+, Sr2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ was studied by potentiometry and spectrophotometry in aqueous solution (I = 1.0 M, KNO3; 25 degrees C) and the stability constants of the M(Bistris)2+ complexes were determined. Unexpectedly Ca(Bistris)2+ is the most stable among the alkaline earth ion complexes (log KCaCa(Bistris) = 2.25; the corresponding values for the Mg2+, Sr2+ and Ba2+ complexes are 0.34, 1.44 and 0.85, respectively). The ions of the 3d series follow the Irving-Williams sequence: log KMnMn(Bistris) = 0.70, for Cu2+, 5.27 and Zn2+ 2.38. Ternary complexes containing ATP4- as a second ligand were also investigated: the values for delta log KM (= log KM(ATP)M(ATP)(Bistris) -log KMM(Bistris) are in general negative (e.g. delta log KCa = -0.40 or delta log KCu = -1.65), thus indicating that the interaction of Bistris with M(ATP)2- is somewhat less pronounced tan with M2+. However, even in mixed-ligand systems, complex formation may still be considerable, hence great reservations should be exercised in employing Bistris as a buffer in systems containing metal ions. Moreover, in several cases delta log KM is relatively high [for Mg2+-ATP4- -Bistris even positive], indicating some cooperativity between the coordinated ligands, possibly hydrogen-bond formation. Distributions of the complexes in dependence on pH are given, and the structures of the binary M(Bistris)2+ and the ternary M(ATP) (Bistris)2- complexes are discussed. The participation of Bistris hydroxo groups in complex formation is evident.

Adenosine Triphosphate↗
PubMed1980

Assessment of left ventricular function during angina pectoris from the mitral valve echogram.

The echocardiographic motion pattern of the anterior mitral valve (aMV) has been shown to be related to left ventricular function. In an attempt to quantify the changes of aMV motion in patients during myocardial ischemia, the following motion phases of the aMV echo were determined in 12 patients with coronary artery disease: DE slope, EF slope, the closure slope of the aMV, as determined by joining points B and C (or in the absence of a clearly definable B point the AC slope), and the systolic motion pattern. Following coronary angiography, measurements of the aMV echo were performed in the resting state and during angina pectoris immediately after rapid atrial pacing at comparable heart rates. DE slope and EF slope showed only minor and insignificant changes during angina in the post-pacing period. The aMV closing velocity (BC or AC slope) was significantly reduced from 225.9 +/- 56 mm/sec during the control period to 177.9 +/- 43 mm/sec during angina (p < 0.01). After recovery from anginal pain measurements of the final closing velocity revealed a return to the control values with an average slope of 240.4 +/- 40 mm/sec. In 3 of 12 patients there was evidence of systolic mitral valve prolapse during the post-pacing anginal episode. Our results suggest that final mitral valve closing velocity reflects changes in left ventricular function during myocardial ischemia in the early isovolumetric phase of ventricular systole. In some patients mitral valve prolapse during angina may indicate ischemic dysfunction of the papillary muscles during the ejection of phase of systole.

Adult↗
PubMed1979

Metal ion/buffer interactions. Stability of binary and ternary complexes containing 2-amino-2(hydroxymethyl)-1,3-propanediol (Tris) and adenosine 5'-triphosphate (ATP).

The interaction of 2-amino-2(hydroxymethyl)-1,3-propanediol (Tris) with the metal ions (M2+) Mg2+, Ca2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ was studied by potentiometry and spectrophotometry in aqueous solution (I = 0.1 or 1.0 M, KNO3, 25 degrees C). Stability constants of the M(Tris)2+ complexes were determined; those constants which were measured by both methods agreed well. Ternary complexes containing ATP4- as a second ligand were also investigated and it is shown that in the presence of Tris, mixed-ligand complexes of the type M(ATP)(Tris)2- are formed. The values for delta log KM, where delta log KM = log KM(ATP)M(ATP)Tris--log KMM(Tris), are all negative, thus indicating that the interaction of Tris with M(ATP)2- is somewhat less pronounced than with M2+. However, it should be noted that even in mixed-ligand systems complex formation with Tris may still be considerable, hence great reservations should be exercised in employing Tris as a buffer in systems which also contain metal ions. Distributions of the complex species in dependence on pH are shown for several systems, and the structures of the binary M(Tris)2- and the ternary M(ATP)(Tris)2- complexes are discussed. The participation of a Tris-hydroxo group in complex formation is, at least for the M(Tris)2- species, quite evident.

Adenosine Triphosphate↗
PubMed1978

A proton nuclear-magnetic-resonance study of self-stacking in purine and pyrimidine nucleosides and nucleotides.

The concentration dependence of the chemical shifts of the protons H-2, H-8 and H-1' of ATP4- and of Mg(ATP)2- , of all non-labile protons of adenosine, of H-5, H-6 and H-1' of TUP, and of H-5, H-6, H-1', and H-2' of uridine have been measured. The results for the purine derivatives are consistent with the isodesmic model of indefinite non-cooperative stacking; for adenosine K = 15 +/- 2M-1, for ATP K = 1.3 +/- 0.2 M-1 and for Mg(ATP)2-K = 3.6 +/- 0.3 M-1. For the pyrimidines, uridine and TUP, stacking is much weaker and the stability constant could only be estimated; for uridine k is less than or equal to 0.5 M-1, and for UTP K approximately 0.3 M-1.

Adenosine↗
PubMed1978

[Radionuclide ventriculography. I. Fundamentals and methods (author's transl)].

Using local time activity curves parameters are calculated which depend on the local wall motion of the heart cavities. These functional parameters allow the determination of the contours of the heart cavities and the assessment of segmental wall motion disorders. The left ventricular ejection fraction has been calculated by enddiastolic and endsystolic counts using a method which takes into account background inhomogeneity.

Electrocardiography↗
PubMed1978

[Radionuclide ventriculography. II. Clinical results--parameters of global ventricular function (author's transl)].

The ejection fraction as determined by gated blood pool studies was compared with the ejection fraction as evaluated by the following conventional methods: 1) biplane cineangiography employing the Simpson rule. Correlation was r = 0.805 (n = 25); 2) the same patients using the area-length method (r = 0.88, n = 25); 3) monoplane cineangiography using the method of Greene et al. (5) (r = 0.86, n = 35). In 20 patients the maximal contraction velocity as evaluated by radionuclide ventriculography was compared with the mean systolic ejection rate. The observed correlation was weak (r = 0.62, n = 20); however, it should be noted that the radionuclide method determines the maximum contraction velocity whereas cinceangiography measures an average value over the whole systole.

Cineangiography↗
PubMed1978

[Radionuclide ventriculography. III. Clinical results--parameters of regional wall motility (author's transl)].

Radionuclide ventriculography and cineangiography were performed in 62 patients with suspected coronary artery disease. Regional wall motility irregularities could be demonstrated in 97% of those patients who revealed an irregularity in the cineangiogram. Two small scars of the posterior myocardial wall escaped detection. The sensitivity of the radionuclide ventriculography was 97%, the specificity was 80%, 4 patients with normal cineangiography showed small irregularities in the radionuclide ventriculogram. 70 patients with infarction revealed wall motility irregularities in 90%, whereas perfusion defects could be detected by thallium scintigraphy in 66% (young and old infarctions).

Cineangiography↗