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Biomedical subjects

Klaus Hahn

Publications and source records attributed to Klaus Hahn.

42 records · Page 3Linked to original sources
PubMed2002

Early detection of myocardial microcirculatory disturbances after primary PTCA in patients with acute myocardial infarction: coronary blood flow velocity versus sestamibi perfusion imaging.

BACKGROUND: The extent of myocardial salvage after primary percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (AMI) is variable and can not be predicted on the basis of vessel patency. The aim of this study was to evaluate the tissue salvage and the microvascular integrity after successful intervention in AMI by coronary blood flow velocity and sestamibi perfusion imaging. METHODS: Twenty-two patients (17 m, 5f; mean age 57 +/- 14 yrs.) undergoing primary PTCA and stent implantation for AMI were studied. 99mTc Sestamibi was injected intravenously before intervention and single photon emission computed tomography (SPECT) was performed immediately after successful reperfusion to determine the area at risk before PTCA due to the minimal 99mTc Sestamibi redistribution. Sestamibi SPECT was repeated 3 days and 6 months after AMI. Area at risk (%) was determined automatically by myocardial perfusion tomography (PERFIT) with the use of a multistage, 3D iterative inter-subject registration of patient images to normal templates (2SD) and myocardial salvage was calculated. Coronary flow velocity was measured using a Doppler-tipped guidewire in the infarct-related artery after successful completion of primary PTCA and in an angiographically normal reference vessel. Absolute coronary flow reserve (CFR) and relative CFR (rCFR) were calculated using hyperemic to basal average peak velocity. RESULTS: Despite successful reperfusion of the target vessel (TIMI grade III flow) CFR and rCFR remained impaired (1.8 +/- 0.9 and 0.77 +/- 0.21). Area at risk decreased significantly from 21 +/- 9% to 9 +/- 10% (p < 0.05) corresponding to 11 +/- 8% myocardial salvage. Acute CFR and rCFR showed no correlation with the area at risk before and after primary PTCA. The increase of CFR within 6 months correlated with the myocardial salvage (p < 0.05). CONCLUSIONS: Despite successful primary PTCA in AMI, CFR and rCFR often remain impaired because of a significant loss of microvascular integrity. The long-term success of primary PTCA can be assessed by myocardial salvage and the change of CFR which might be a useful parameter for additional reperfusion strategies such as glycoprotein IIb/IIIA receptor inhibition.

Adult↗
PubMed2002

Live-cell fluorescent biosensors for activated signaling proteins.

A new generation of live-cell fluorescent biosensors enables us to go beyond visualization of protein movements, to quantify the dynamics of many different protein activities. Alternate approaches can report post-translational modifications, ligand interactions and conformational changes, revealing how the location and subtle timing of protein activity controls cell behavior.

Animals↗
PubMed2002

Post-therapeutic lymphedema: scintigraphy before and after autologous lymph vessel transplantation: 8 years of long-term follow-up.

The function of lymphatic vessel grafts was proved in 12 patients with lymphedema of the upper extremity by visual and semiquantitative evaluation of a preoperative baseline study and scintigraphic follow-up data for a period of 8 years after microsurgical treatment. The transplantation site was an upper extremity. In 11 of 12 patients, lymphatic function improved after autologous lymphatic vessel transplantation compared with preoperative findings. This could be verified by a statistically significant decrease of the transport index ( < 0.01), clear demonstration of lymph nodes, and a less diffuse distribution pattern of the Tc-99m-labeled nanocolloids. In three patients, the vessel graft could be detected by scintigraphy. Lymphoscintigraphy combined with semiquantitative evaluation of lymphatic transport kinetics has been shown to be an easy and reliable method to assess lymphatic function before and after autologous lymph vessel transplantation.

Adult↗
PubMed2002

Hippocampal changes in patients with a first episode of major depression.

OBJECTIVE: Previous work suggests that patients with unipolar depression may have structural as well as functional abnormalities in limbic-thalamic-cortical networks, which are hypothesized to modulate human mood states. A core area in these networks is the hippocampus. In the present study, differences in volumes of hippocampal gray and white matter between patients with a first episode of major depression and healthy comparison subjects were examined. METHOD: Thirty patients with a first episode of major depression and 30 healthy comparison subjects who were matched for age, gender, handedness, and education were examined with high-resolution magnetic resonance imaging. RESULTS: Male patients with a first episode of major depression had significantly smaller hippocampal total and gray matter volumes than healthy male comparison subjects. Both male and female patients showed significant alterations of left-right asymmetry and significant reductions of left and right hippocampal white matter fibers in relation to healthy comparison subjects. Hippocampal measurements were not significantly correlated with clinical variables, such as age at onset of illness, illness duration, or severity of depression. CONCLUSIONS: These results are consistent with findings of structural abnormalities of the hippocampal formation in patients with major depression that were more pronounced in male patients. The authors' findings support the hypothesis that the hippocampus and its connections within limbic-cortical networks may play a crucial role in the pathogenesis of major depression.

Adult↗
PubMedDate not supplied

Relationship between right ventricular ejection fraction and maximum exercise oxygen consumption: a methodological study in chronic heart failure patients.

BACKGROUND: Peak oxygen consumption at maximum exercise (peak VO(2)) predicts survival in chronic heart failure (CHF) patients. Right ventricular ejection fraction (RVEF) at rest has been reported to correlate with peak VO(2). We evaluated the strength and consistency of the association between peak VO(2) and RVEF measured by different radionuclide ventriculography (RNV) techniques in a prospective cohort study. METHODS AND RESULTS: In 58 consecutive CHF patients (mean age, 53 years; 39 patients with dilated cardiomyopathy; 48 men), upright symptom-limited bicycle ergometry was performed. During exercise, ventilatory and gas exchange data were recorded and peak VO(2) was calculated. RVEF was calculated by use of first-pass (FP) RNV with single and dual region of interest (ROI) acquisition and planar multigated acquisition (MUGA). Irrespective of the method used, RVEF showed no relevant correlation with the corresponding peak VO(2) value (r = 0.11 for FP single ROI, r = 0.06 for FP dual ROI, r = 0.16 for MUGA). Peak VO(2) or changes in peak VO(2) after 6 and 12 months of follow-up were not determined by RVEF measurements. CONCLUSION: In CHF patients no association was found between peak VO(2) at maximum exercise and RVEF at rest with different RNV techniques. Changes in exercise capacity are not reliably reflected by changes in RVEF measurements at rest.

Adult↗