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Biomedical subjects

U Koehler

Publications and source records attributed to U Koehler.

61 records · Page 4Linked to original sources
PubMed1989

Distinct mouse DNA sequences enable establishment and persistence of plasmid DNA polymers in mouse cells.

Distinct elements isolated from mouse genomic DNA confer on plasmid DNA the ability to persist at high copy numbers in mouse L fibroblasts (1). Field inversion gel electrophoresis demonstrated that - in contrast to our previous assumption - the persisting plasmid DNA does not exist extrachromosomally but as clusters of tandem repeats integrated into genomic DNA. Digestion with restriction endonucleases that do not cut within the plasmid DNA results in fragments of 50-300 kb in length indicating reiteration of 10-50 plasmid DNA molecules. Restriction with several enzymes that cut once or twice within the plasmid sequences lead to fragment(s) indicative for head-to-tail tandem repeats. In situ hybridization revealed signals for a long homogeneously staining region (HSR) in one or two chromosomes per cell nucleus. Possibilities how these elements could act in the establishment and/or maintenance of the head-to-tail polymers of plasmid DNA in mouse cells are discussed.

Animals↗
PubMed1989

[Results of left heart catheterization study in 64 patients with nocturnal disorders of respiratory control (sleep apnea)].

Sleep apnea (SA) is associated with increased morbidity of the cardiovascular system, the interaction between the disordering of respiratory coordination and cardiovascular regulation being largely unknown. In 64 patients (age: mean = 54.1; range: 35-67 years) with an increased apnea index (AI greater than 10), a cardiac catheterisation investigation was performed to exclude coronary heart disease (CHD) or cardiomyopathy. CHD was excluded in 39 patients, 6 patients had coronary single-vessel disease, 9 patients coronary two-vessel, and 10 three vessel disease. In 10 patients, cardiomyopathy was detected, while high-grade impairment of the left ventricular ejection fraction (greater than 30%) was observed in five patients. With the exception of a single patient, CHD was observed only in patients in the over-fifty age group. Arterial hypertension was seen in 84% of the patients with, and in 69% of the patients without, CHD. The patient groups with and without coronary heart disease did not differ with respect to apnea index, ten minute index, or the average duration of the 30 longest apneic episodes. Anginal complaints, observed in a total of 72% of the patients, were one of the major indications for coronary angiography. These results do not support the assumption that SA is primarily a consequence of underlying cardiac disease, but do indicate that SA must be considered a cardiac risk factor, especially in view of the fact that pronounced nocturnal changes in blood gases and haemodynamics, together with malignant arrhythmias, are found in conjunction with this disturbance of breathing.

Adult↗
PubMed1985

Left ventricular enzyme activities of the energy-supplying metabolism in Goldblatt-II rats.

The hypertrophied left ventricles of renovascular hypertensive Wistar rats were examined for several enzyme activities 4-6 and 8-12 weeks after operation (Goldblatt-II), and compared with controls. The activities of beta-hydroxyacyl-CoA dehydrogenase in hypertrophied myocardial tissue were found to be markedly diminished, as were those of citrate synthase, although to a lesser degree. In both stages of left ventricular hypertrophy hexokinase activity was considerably increased, whereas that of lactate dehydrogenase was only initially slightly elevated. Both enzymes showed an altered isoenzyme composition. The possible reasons and consequences of these changes are discussed.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMedDate not supplied

The behavior of some enzymes of the hypertrophied and postnatally developing myocardium of the rat.

The present study was undertaken in order to investigate the behavior of lactate dehydrogenase (LDH) and hexokinase (HK) in the mechanically overloaded and the postnatally developing left ventricle of the rat. In Goldblatt rats (GBR) 2 to 4 months after operation total LDH activity was decreased by 7%, accompanied by an isoenzyme shift towards a higher M proportion. Swimming rats (SR) showed an 11% increase in LDH activity. HK activity was increased by 14% in GBR and unaltered in SR. Histochemical investigations revealed no indication of heterogeneous alterations in various areas of the myocardium. During postnatal development, a gradual increase of activity and H subunit proportion of LDH were observed. HK activity was increased after one week, but underwent a slow decreased thereafter. These changes are interpreted as processes of adaptation to the conditions of extrauterine life.

Aging↗