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Biomedical subjects

M Lüning

Publications and source records attributed to M Lüning.

At least 19 recordsLinked to original sources
PubMed1992

Electron microscopic and 31-P NMR studies of ischemic injured rat livers during preservation and reflow.

Ischemic injury induced during preservation and reperfusion contributes to post-operative failure in liver transplantation. Hepatic injury and recovery from preservation was studied in an isolated rat liver model reperfused with oxygenated erythrocytes. In order to correlate morphological and functional findings, 31-P nuclear magnetic resonance spectroscopy and electron microscopy were used to investigate metabolic and ultrastructural changes during 6 hours of reperfusion. Following cold preservation, EM's showed a primary sinusoidal cell injury, whereas the hepatocytes were well maintained. During reperfusion, hepatocytes displayed further damage. The simultaneous presence of vacuolarly degenerated mitochondria and mitochondria of increased activity was noted. 31-P NMP spectra demonstrated initially a partial ATP-recovery. The maximum level of 60% of the control ATP-value could not be further increased. EM and 31-P NMR indicate that the progressive injury to the liver is due to microcirculatory malfunction induced by an endothelial cell damage, followed by injured hepatocytes themselves, and the consequent intracellular energy crisis that is produced.

Animals↗
PubMed1992

[The place of computed tomography in the staging of bronchial carcinoma. A retrospective study].

The conventional radiological and CT findings in 347 patients with confirmed bronchial carcinomas have been compared. In 184 patients subjected to surgery, the post-operative TNM classification was compared with the pre-operative CT staging. It was found that CT staging of the T-classification was correct in 82% and of the lymph nodes in 62.5% of cases. CT had a sensitivity of 92% and 95% for the recognition of mediastinal and bronchopulmonary lymph nodes, respectively, and a specificity of 68% and 57%. In 163 patients not subjected to surgery the reasons for avoiding operation were also studied. In more than 80% of these patients it was the CT findings which had indicated that the patient was inoperable.

Adenocarcinoma↗
PubMed1991

Effect of pentoxiphylline on the recovery of the preserved rat liver: 31P NMR and ultrastructural studies.

Hepatic failure often occurs following transplantation. This is primarily due to cold ischemia during preservation, warm ischemia during implantation, and finally reperfusion damage after transplantation and reflow. The possibility that this ischemia and reperfusion-induced damage can be reduced by preischemic application of a xanthine derivative (pentoxiphylline) was examined using 31P NMR spectroscopy and electron microscopy (EM) studies of bioenergetic and ultrastructural changes in oxygenated erythrocyte-perfused rat livers. EM illustrated that the hepatocytes and the mitochondria appeared to be relatively unaffected by cold preservation of the liver, whereas the endothelial cells lining the sinusoids became disrupted. After reperfusion, NMR spectroscopy showed a partial recovery of ATP levels, and EM indicated progressive mitochondrial injury. This progressive injury to the liver was probably due to endothelial cell damage which resulted in microcirculatory malfunction and free radical formation during reperfusion. Pentoxiphylline pretreated livers showed better preservation of the cell morphology and exhibited better ATP recovery than untreated livers. Pentoxiphylline is known to prevent the loss of precursors of ATP resynthesis by inhibiting AMP dephosphorylation during ischemia and improves the microcirculation via vasodilatory properties following ischemia. Thus, it is concluded that pentoxiphylline may ameliorate ischemia-induced cell damage during transplantation.

Adenosine Monophosphate↗
PubMed1991

[The accuracy of the imaging procedures (sonography, MRT, CT, angio-CT,nuclear medicine) in characterizing liver tumors].

In a prospective study, an attempt was made to determine the specificity of various imaging methods for defining tumours of the liver rather than their ability to demonstrate them. It was based on 130 patients with histologically confirmed lesions (33 haemangiomas, 17 FNH, 4 hepatocellular adenomas, 28 HCC, 36 adenocarcinoma metastases). The methods were MRT (130 cases), sonography (119), CT (122), dynamic arterial angio-CT (15), 99TC-EHIDA or blood pool scintigraphy (4 FNH, haemangiomas, HCC, 44 cases). MRT showed somewhat better results (accuracy 80%) than CT (73%) and angio-CT (73%) in demonstrating the type of lesion. The results of scintigraphy (53%) and sonography (69%) were rather worse. The range of accuracy for MRT, CT and sonography varied from 94% (haemangiomas with MRT) to 47% (FNH with sonography).

Biopsy↗
PubMed1991

[Value of CEA determination in follow-up of patients with liver metastasis of colorectal cancers with loco-regional chemotherapy].

The importance of carcinoembryonic antigen as a tumor marker to the follow-up of patients with liver metastases from colorectal cancer was investigated. It was reported about 29 patients receiving chemotherapy. We estimated the effect of therapy according to sonographic and computer tomographic criteria and related to the CEA-level. The correlation of the growth of cancer and the level of the CEA was positive in 81% of the patients. We do not consider as sufficient the measurement of CEA as an exclusive method for the follow-up of colorectal cancer and recommend the monthly measurement of CEA in connection with radiological examinations in the period of 3-4 month.

Adult↗
PubMed1990

[A frequency analysis and evaluation of the criteria for dynamic CT and a test of the CT diagnosis of space-occupying lesions of the liver].

In a retrospective study the findings of dynamic CT investigations in 185 patients with histologically confirmed hepatic masses were analysed and related to 47 criteria which have been described in the literature. The criteria with the highest value for making a specific diagnosis have been defined for seven different lesions (abscess, adenoma, FNH, haemangioma, adenocarcinoma metastases, metastases from other tumours, HCC). We found agreement with the literature in the following: the target phenomenon for abscesses, central scarring for FNH, spreading enhancement for haemangiomas and irregularity of the liver contour in the absence of subcapsular tumours for HCC. By combining a number of criteria it was possible to suggest the type of lesion retrospectively. The predictive value was found to range from 73% to 100%, a definite diagnosis was possible in only 64%.

Diagnosis, Differential↗
PubMed1990

[Dynamic MRT after Gd-DTPA administration in kidney transplants: the susceptibility and T2 effects].

35 kidney transplanted patients (15 without pathological findings and 20 with histologically proven chronic rejection) were investigated with a combination of dynamic MR and bolus application of Gd-DTPA. The occurrence of susceptibility artifacts and T2 effects at the junction between papilla and renal calix were analysed. There are two groups of patients. The first one shows only artifacts due to susceptibility. The second group indicates the so-called "dark ring pattern" (susceptibility artifacts and T2 effects). These effects are discussed in terms of their dependence on concentration and their dependence on the degree of transplant malfunction. The appearance of "dark-ring patterns" and of susceptibility artifacts indicate the functional status of the glomerular filters.

Contrast Media↗
PubMed1990

[Differential diagnosis by MRT of cavernous hemangiomas and malignant tumors of the liver--advantages of the multi-echo technic].

With a retrospective analysis of images from 39 patients with histologically proven liver tumours we tried to determine the best MRT-parameter for detection of cavernous hemangioma (n = 19) and its differentiation from malignoma (metastases n = 17, HCC n = 5). The best differentiation was achieved with the contrast-to-noise ratio between lesion and liver in multi-echo-images with TR/TE = 2,000/210 ms and a definite limit with an accuracy of 84% for hemangioma and 91% for malignoma. The respective intensity ratios (lesion/liver) were 95% and 77%. T2-relation times and the T1- and T2-ratios were also calculated. In contrary to the literature we think that these parameters are not sufficiently discriminating.

Adult↗
PubMed1990

[The rational use of imaging technics for the diagnosis of abdominal tumors with particular reference to magnetic resonance tomography].

After introduction and using sonography and computed tomography over years magnetic resonance tomography is also being applied to clinical practice for various diseases. Considering the cost-benefit-risk new conceptions for the diagnostic strategy are necessary. With the presentation of the three supplementary and to some extent competitive cross sectional imaging procedures the diagnostic possibilities in space occupying processes of adrenals, kidneys, liver, and pancreas are discussed.

Abdominal Neoplasms↗
PubMed1990

[Diagnosis of the aortocoronary bypass--a comparison of MRT and CT].

Complaints of angina pectoris after aortocoronary bypass surgery can be due to the obturation of one or more bypasses. The aim of our study was the evaluation of magnetic resonance tomography for the investigation of bypass patency in comparison with computed tomography. We investigated 18 patients. 33 of 35 bypasses were safely detectable with spin-echo techniques and 32 with fast-scan-techniques and presentation in cine-mode. 25 of 33 bypasses were identified as open with the SE-technique, 27 of 32 with the "fast" technique. No safe decision was possible for 4 bypasses with SE-technique and for 1 bypass with the "fast" technique. The results are in good agreement with the reference investigation by CT. For the investigation of bypass patency with MRT neither x-rays nor contrast media are necessary. It is therefore recommended for patients with allergy to contrast media and cases with high radiation risk.

Adult↗
PubMed1989

[An intra- and interobserver study of the accuracy of dynamic CT of hepatic space-occupying lesions].

An intra- and interobserver study with 10 physicians was undertaken in order to determine the accuracy of differentiation regarding the type and benign/malignant of hepatic space-occupying processes. By "conditioning" of the observers a significant reduction of doubtful cases with a slight increase in diagnostic accuracy (10% in differentiating of benign/malignant and 5% of the type) relative to our first study was achieved. Marked increases were found for 3 little experienced observers. By informing the observers on the diagnostic criteria for hepatocellular carcinoma the percentage of correct decisions was significantly increased.

Humans↗
PubMed1989

[Computed tomographic false diagnoses in acute pancreatitis].

With computed tomography acute pancreatitis can be differentiated into an oedematous, serous-exudative, hemorrhagic-necrotizing, suppurative-abscessing and a postacute necrotizing form with high diagnostic accuracy (83.2%). Problems occur in distinguishing necrotizing from abscessing pancreatitis. False negative and false positive errors are less frequent in detecting necrosis and its differentiation from less serious forms (4.4% and 2.1%). Dynamic CT discovers also parenchyma losses not detectable without contrast medium and allows to prove subtotal or total necrosis in case of discrete changes in the native scans. Sonographic tomography contributes to diagnostics by proving acute necrotizing pancreatitis due to a chronic inflammatory pancreatic process.

Acute Disease↗
PubMed1989

[Experiences with CT-guided percutaneous drainage of pyogenic liver abscesses].

32 CT-guided percutaneous drainages of bacterial liver abscesses in 25 patients accomplished definitive sanitation in 18 of them (72%). In 7 cases surgical revision was required. Percutaneous drainage of abscesses was able to achieve a temporal improvement in these cases and therefore was an effective pre-surgical measure. There were no complications primarily due to the method itself. The average dwell-time of catheters during drainage of curative percutaneous drainage was 22.5 days. The new therapy concept has proven to be of little discomfort and complications together with high therapeutic effectiveness.

Adult↗