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Biomedical subjects

W Gründer

Publications and source records attributed to W Gründer.

32 records · Page 2Linked to original sources
PubMed1990

[Biophysical research on condylar temporomandibular joint growth].

On the basis of results obtained from the study of mechanically induced potentials and pulsed 1H-NMR investigations of the condylar cartilage of the TMJ in vitro, the hypothesis is advocated that the internal regulation of condylar growth takes place with the aid of bioelectric signals. Reference in made to the importance of the studies for a future noninvasive diagnosis of condylar growth in the course of functional orthopedic treatment, using "dynamic" magnetic resonance imaging.

Animals↗
PubMed1990

[NMR-microscopic studies of the condylar cartilage of the temporomandibular joint].

The objectifying of growth mechanisms of the TMJ is very important for orthodontic diagnosis, treatment as well as clinical research. Condylar cartilage of the TMJ from neonatal pigs was investigated on in vivo preparations by NMR-microscopy. NMR-micro-pictures and histologic slide preparations of condylar cartilage were compared and discussed in connection with its implications for treatment with functional appliances.

Animals↗
PubMed1990

[The effect of L-carnitine on the energy metabolism of isolated rat heart perfused by Langendorff's method using 31P-NMR spectroscopy].

31P-NMR spectroscopy is a method for continuous, noninvasive determination of high-energy phosphates in the intact organ. On the isolated Langendorff perfused rat heart the effect of L-carnitine on concentration of cytosolic ATP and phosphocreatine was studied under influence of a single or repeated periods of 20 min ischemia. On reperfusion the carnitine-treated hearts showed higher CP/Pi values and an increase of the energy index (CP + ATP)/(C) + ATP + Pi) then did control hearts. An improved ischemia tolerance was demonstrated.

Adenosine Triphosphate↗
PubMed1989

Nitrogen-15 NMR studies of rat liver in vitro and in vivo.

In the present 2.1 T15N NMR study two different kinds of experiments are presented. In one we show that metabolic reactions of 15N-labelled glycine can be followed in the isolated rat liver. In the second we demonstrate that [15N]glycine can be detected using NMR in vivo. For quantification and identification of glycine and metabolites 15N-isotope analysis (emission spectrometry technique) was used. To our knowledge, this is the first demonstration of 15N NMR for study of the metabolism of 15N-labelled compounds in vivo.

Animals↗
PubMed1989

PGE1 and iloprost affect the high energy phosphates in the global ischemic and reperfused rat heart: a 31P-NMR study.

The influence of PGE1, iloprost and a combination of both on high energy phosphate levels in isolated rat hearts reperfused 1 h following 20 min of global ischemia was investigated employing 31P-NMR-spectroscopy. Whereas PGE1 induced a slight reduction in the decline of the creatine phosphate/inorganic phosphate. ATP/inorganic phosphate ratio and NMR-energetic index during ischemia, iloprost application was followed predominantly by a temporary but marked improvement of the creatine phosphate/inorganic phosphate ratio during the early period of reperfusion. The best results in preservation of high energy phosphates were achieved after simultaneous application of PGE1 and iloprost. It is presumed that the accelerated normalization of the heart function observed immediately after ischemia in the eicosanoid treated hearts is related to the more rapid recovery of intracardial high energy phosphate level.

Adenosine Triphosphate↗
PubMed1988

Action of iloprost and PGE1 on global ischemic and reperfused myocardium: a 31P-NMR-study.

The influence of iloprost, PGE1 and of the combined application of iloprost and PGE1 on high energy phosphate contents was investigated in isolated rat hearts perfused aerob at 37 degrees C in Langendorff mode. Changes in creatine phosphate, ATP and inorganic phosphate were registered during 20 minutes of global ischemia and 56 minutes of reperfusion with 31P-NMR-spectroscopic methods starting drug application prior to ischemia simultaneously with onset of heart perfusion. Most effective in preservation of high energy phosphates was the combined application of PGE1 and iloprost resulting in a creatine phosphate/inorganic phosphate ratio of 103.2 +/- 30.9% of pre-ischemia values compared to 52.5 +/- 6.1% in control group without drug application 0-5 minutes after onset of reperfusion, 148.8 +/- 24.8% vs 78.8 +/- 15.2% at 6-11 minutes of reperfusion and 116.6 +/- 16% vs 68.9 +/- 12.7% at 12-17 minutes of reperfusion. The same trend was observed employing ATP/inorganic phosphate ratio. The improved energy state in reperfused hearts following application of PGE1 and iloprost in combination is presumed to be supported by a reduction of the loss of high energy phosphates (HEP) during global ischemia and by a cytoprotective effect of iloprost immediately after starting reperfusion.

Alprostadil↗
PubMed1988

Effect of pentoxifylline on the ischemic rat kidney monitored by 31P NMR spectroscopy in vivo.

The effect of pentoxifylline on the recovery of renal energy metabolism after ischemia and reperfusion was studied by 31P nuclear magnetic resonance spectroscopy in vivo. Rat kidneys were exposed to 15, 30 and 60 min, respectively, of ischemia by clamping the arteria renalis. Pre-ischemic application of pentoxifylline improves the recovery of renal energy metabolism. The concentration of ATP was found to be higher in pentoxifylline pretreated kidneys than in controls after ischemia. The 5'-nucleotidase inhibiting activity of pentoxifylline is suggested to be the mechanism responsible for the protective effect of the drug. 31P NMR spectroscopy proved to be a powerful tool for continuous follow-up of drug effects on metabolic processes.

Adenine Nucleotides↗
PubMed1987

31P-NMR spectroscopy and ultrastructural studies on nephrotoxicity of cyclosporine A.

NMR-spectroscopy and electron microscopy were applied in order to find out whether nephrotoxic effects of cyclosporine A in combination with ischaemia on rat kidney are of significance for the energy metabolism of the organ. CSA was administered in daily doses of 15 mg/kg rat over 20 days. Use was made of the particular advantage of 31P-NMR-spectroscopy to follow up the dynamics of high-energy phosphate concentrations in the same tissue. Ultrastructural changes were observed in the region of the proximal tubule. Some mitochondria showed degenerative changes, others increased density of cristae. The total number of mitochondria was increased. This observation together with the coexistence of vacuolarly degenerated mitochondria and mitochondria with increased activity after CSA treatment is interpreted as expression of a compensatory mechanism that keeps constant the totality of high-energy phosphates despite damage to some mitochondria.

Adenine Nucleotides↗
PubMed1987

31-P-NMR-spectroscopy on ischemic and reperfused rat hearts: effects of iloprost.

Effects of iloprost on the behaviour of high energy phosphate contents were investigated in global ischemic and reperfused rat hearts prepared according to Langendorff. Iloprost application before and after 20 min of ischemia at a dosage of 9-12 pg/g heart weight x min improved the availability of high energy phosphates as was shown by CP/Pi ratio during the first hour of reperfusion.

Animals↗
PubMed1985

[31P NMR studies in isolated rat kidney].

The conventional 31P-NMR technique can be used to get valuable information on the state of isolated organs from the time course of changes in high-energy metabolites. This is demonstrated for the rat kidney measured under various ischemic conditions. The used technique is presented. In addition, in studies using superconducting NMR systems, changes of ATP beta-resonances were detected. Relations of the observed changes in the 31P-NMR spectra to tissue damage are discussed.

Adenosine Monophosphate↗
PubMedDate not supplied

[The effect of temperature on preservation of swine articular cartilage--an NMR study].

The influence of temperature on stored porcine articular cartilage was studied and the factors underlying degradation identified. For these investigations, specimens measuring 18 mm in diameter were punched out of the articularis humeri of juvenile pigs. These samples were investigated by MR microimaging immediately after preparation, and after storage for three days at +4 degrees C and -18 degrees C. Five smaller (3 mm) cylindrical specimens were then obtained and compared with one another using MR-spectroscopy, relaxometry and biochemical assays. From the experiments we conclude that all analytical methods--with the exception of MR microimaging--are capable of detecting changes in cartilage, and that it is not advisable to keep cartilage frozen, since marked changes, presumably at the cellular level, occur. Storage at +4 degrees C also requires the use of preserving chemicals, as otherwise, the polymers of the extracellular matrix degrade.

Animals↗
PubMedDate not supplied

New gadolinium complexes as magnetic resonance imaging--contrast agents.

We have investigated the physicochemical and paramagnetic properties of the new gadolinium complexes of N-(pyrid-2-yl-methyl)-ethylenediamine-N,N,N-triacetic acid (Gd-PEDTA) and N-tris(2-aminoethyl)amine-N,N,N,N,N,N+hexaacetic acid(Gd-TTAHA). The relaxivities as well as the thermodynamic and conditional stability constants of these complexes with respect to the physiological relevance were determined and discussed in comparison with the commercially available gadolinium (III) diethylenetriaminpentaacetic acid/gadopentate dimeglumine (Gd-DTPA, Magnevist). In case of Gd-TTAHA a twofold higher relaxivity and a complex stability similar to Gd-DTPA were determined. It is shown, that lower concentrations of Gd-TTAHA are sufficient for the same signal enhancement in the T1-weighted MR image compared with Gd-DTPA and, thus, the use of the new contrast agent Gd-TTAHA should diminish risks for health. Therefore, Gd-TTAHA might be used potentially as a new contrast agent for clinical MRI application.

Acetates↗