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Biomedical subjects

M Thelen

Publications and source records attributed to M Thelen.

At least 379 records · Page 21Linked to original sources
PubMed1984

[Computer tomographic determination of left ventricular muscle mass].

Left ventricular muscle mass LVMM) was determined by computed tomography in 19 dogs (33 in vivo and 19 postmortem studies). CT values obtained with 4 models were compared with the actual LVMM at autopsy. Excellent correlation was achieved by volumetric analysis (model A; r = 0.95-0.96). Accurate assessment of LVMM was also obtained using a two-axis method (model B), an area-length method (model C), or a representative cross-sectional volume (model D). There was no significant difference between in vivo and postmortem studies. We conclude that CT can provide reliable estimates of LVMM in vivo. Volumetric analysis is not dependent on mathematical models of the left ventricle. However, this method is very time-consuming. The other CT-models are simple enough to permit clinical application. In comparison with other experimental and clinical methods of LVMM quantitation, CT is superior to chest X-ray, ECG, VCG, and M-mode echocardiography, while similar good results can be obtained with two-dimensional echocardiography as well as conventional and digital angiocardiography.

Animals↗
PubMed1983

Drug-induced lipid peroxidation in mice--V. Ethane production and glutathione release in the isolated liver upon perfusion with acetaminophen.

Isolated liver from phenobarbital-induced male mice was perfused using infusions of cytochrome c pulses as quality control of the system. Livers spontaneously evolved 1.1 pmoles ethane g-1 liver min-1, exogenous pentane disappeared with 0.6 pmoles g-1 min-1. Infusion of 0.26 mmoles/l. FeCl2 led to immediate ethane production followed later on by lactate dehydrogenase release from the liver. Infusion of acetaminophen resulted in hepatic ethane production at drug concentrations greater than 0.1 mmoles/l. A maximum effect was observed at 2 mmoles/l. of acetaminophen infused while higher concentrations, up to 10 mmoles/l. delayed ethane release although they enhanced the rate of glutathione depletion. This glutathione efflux decreased from 12 nmoles/g-1 min-1 observed after perfusion of medium alone to 2.9 nmoles/g-1 min-1 when AAP was infused. The slope of the pseudo first order depletion kinetics depended on the acetaminophen concentrations. This glutathione release represents the perisinusoidal portion of the total efflux measured here independently from the biliary secretion. The results show that in agreement with the in vivo findings acute intoxication of liver with high doses of this drug lead to lipid peroxidation, while in vitro an apparent antioxidative effect was measured. The implications for drug screening are probably important.

Acetaminophen↗
PubMed1983

[Surgical treatment in acute pancreatitis. The change as influenced by sonography and computer tomography].

The diagnosis of acute pancreatitis is based on anamnestic, clinical and chemical data. Ultrasound and computed tomography permit direct visualisation of the pancreas and establish the diagnosis. In cases of haemorrhagic-necrotising pancreatitis they demonstrate the extent of morphological changes and permit exclusion of other causes of an acute abdomen. The imaging methods support indications for operation in cases of subtotal or total parenchymatous necrosis and in pancreatic abscesses. Conservative expectant approaches in patients with severe clinical course and slight morphological changes as well as in agreement of clinical and morphological findings are facilitated. Complete demonstration of parenchymatous and peripancreatic necroses furnishes useful additional information for total extirpation. Gallstone disease can be demonstrated or excluded preoperatively. Since introduction of ultrasound and computed tomography for the diagnosis of acute pancreatitis a marked diminution of early surgical intervention and delayed operation has been achieved.

Acute Disease↗
PubMed1982

[Diagnosis of the site of insulinomas: percutaneous transhepatic portal vein catheterisations with selective blood sampling for hormone determination (author's transl)].

Percutaneous transhepatic portal vein catheterisation with blood sampling from the various areas of drainage, especially the pancreatic veins, was undertaken in seven patients with insulinoma to diagnose its site. In six patients measurement of serum-insulin levels revealed an abrupt rise in the vascular area later found to drain the area of the insulinoma. Insulin measurement in one patient with insulinoma in the head of the pancreas falsely indicated an islet-cell tumour in the region of the tail of the pancreas. C-peptide concentration in serum followed the concentration of insulin, but did not show such a marked rise. The method of percutaneous transhepatic portal vein catheterisation with selective blood sampling for the measurement of hormonal concentration was superior to ultrasound, computer tomography or coeliacography for determining the site of the tumour.

Adenoma, Islet Cell↗
PubMed1981

Studies on the molecular basis of H+ translocation by cytochrome c oxidase.

We report here studies which characterize further the interaction of N,N'-dicyclohexylcarbodiimide with cytochrome c oxidase leading to inhibition of H+ translocation by the enzyme. Further evidence is presented to show that the inhibition results from a real interaction of DCCD with the enzyme and cannot be accounted for by uncoupling and, contrary to recent criticisms, this interaction occurs specifically with subunit III of the enzyme even at relatively high inhibitor-to-enzyme stoichiometries. Use of a spin-label analogue of DCCD has enabled us to demonstrate that the carbodiimide-binding site is highly apolar and may not lie on the pathway of electron transfer.

Animals↗
PubMed1981

Treatment of idiopathic varicoceles by transfemoral testicular vein occlusion.

Percutaneous transfemoral occlusion of the testicular vein is a new alternative in the treatment of idiopathic varicocele. Embolization with the Gianturco coil was done on 27 patients. The occlusion was performed immediately after diagnostic phlebography. The results of followup for 1 year are available for 18 patients. In 1 patient the coil had to be removed because of persistent pain, although cause and effect could not be proved. Two patients had a recurrence. The urographic findings were normal 1 year after embolization. No dislocation of the foreign body was observed. Two patients reported that their wives were pregnant.

Adolescent↗
PubMed1981

[Animal studies of quantitative renal occlusion scintigraphy (author's transl)].

Radio-active plastic microspheres with an average diameter of 15 mu were used in eight dogs to measure renal perfusion and the results compared with time-activity curves before and after constriction of the left renal artery. It was shown that the values obtained for renal blood flow by functional scintigraphy are not accurate, particularly for moderate or low blood flow. The reason for this is primarily the distortion of the intravenously injected radio-active bolus and the consequent deviation from the so-called delta function.

Animals↗
PubMed1981

[Superselective embolisation in the urogenital tract with tissue adhesives (author's transl)].

The tissue adhesive butyl-2-cyanoacrylate mixed with lipiodol and tantulum powder is an excellent agent for superselective catheter embolisation of small vessels. The mixture is low viscous and can be injected through fine catheters. Occlusion is independent of blood clotting and is permanent. A coaxial catheter technique is recommended or, in cases of difficulty, a ballon catheter can be floated in. Super-selective embolisation was used in 15 patients, in seven for the kidney in eight for the pelvis. Indications were bleeding from the kidney, partial defunctioning of the kidney, tumours in single kidneys and bleeding from carcinomas in the bladder, prostate or cervix.

Adenocarcinoma↗
PubMed1981

[B-scan sonography of the carotid artery. Technique, results and indications (author's transl)].

Three hundred and forty-six carotid arteries were examined with a two-dimensional 3.5 MHz real time scanner in 173 patients with evidence of cerebral ischaemia; 62 carotid arteries were investigated by selective trans-femoral angiography in 36 of these patients at the same time. Sonography and angiography agreed in 20 (91%) of 22 angiographically normal cases, in all cases (10) with haemodynamically insignificant plaques, in eight (66%) of 12 stenosis of less than 50%, in nine (90%) of ten stenosis of more than 50% and in four (44%) of nine total occlusions. Sensitivity of carotid sonography varied with the severity of the lesion from 44 to 100%. Its specificity was 91%. B-scan sonography of the carotid artery, in the presence of cerebro-vascular lesions (transitory ischaemia, cerebral infarcts) and in the presence of non-specific symptoms and of asymptomatic vascular murmurs, may provide indications for the use of angiography. Its values as a screening procedure remains to be assessed.

Arteriosclerosis↗
PubMed1981

[B-scan sonography for tumour localisation in hyperparathyroidism (author's transl)].

Thirty-four patients with known primary, secondary or tertiary hyperparathyroidism were examined sonographically in order to localise the enlarged glands. Of 40 tumours found at operation, 27 (67%) could be demonstrated sonographically as oval or round structures with low echoes. The smallest tumour diagnosed pre-operatively was 10 x 5 x 4 mm. Sonography is useless for adenomas in the mediastinum. Sonographic localisation is desirable before primary operations for hyperparathyroidism, although it is not indispensable for the experienced surgeon. Sonography is essential before surgery for recurrences and should be performed before CT, arteriography or selective parathormone sampling.

Adenoma↗
PubMed1981

Determination of liver and spleen perfusion by quantitative sequential scintigraphy: results in normal subjects and in patients with portal hypertension.

Quantitative sequential hepatosplenic scintigraphy was performed to determine the arterial and portal components of the total liver circulation in 135 patients (no liver disease in 20, liver cirrhosis and portal ;hypertension in 115). Portal circulation in healthy patients is calculated to be 70.4 +/- 6.2% of the total liver blood flow, whereas patients with portal hypertension showed a clear reduction of portal perfusion to 20.2 +/- 10.9%. Thirteen of 20 patients having portosystemic shunt surgery showed no portal perfusion. This new, noninvasive diagnostic technique yields vital information particularly useful in ;the surgical evaluation of portal hypertension. Other indications are also discussed.

Angiography↗
PubMed1981

Human body fluid ribonucleases: detection, interrelationships and significance.

Study of the RNases of human body fluids has been facilitated by use of activity staining following SDS-polyacrylamide gel electrophoresis. Commercial SDS preparations contain minor lipophilic contaminants (less than 0.1%) which interfere with enzyme renaturation and prevent activity staining unless gels are washed after electrophoresis in 25% isopropanol. Partial characterization of the RNases of serum, urine, and cerebrospinal fluid (CSF) is described, including evidence that the RNases comprising bands A-C of urine and 1-3 of CSF are glycoproteins. Evidence is presented that the major RNase activities of serum (RNases 1-5) and urine (band A) do not originate in pancreas, and that leukocytes are the source of band D RNase of urine, as well as of minor RNase activities of serum and CSF. Results are summarized suggesting that elevated plasma RNase levels may be of dubious utility in the diagnosis of most malignant diseases. Some elevated levels reported in the literature may reflect the advanced age of cancer patients, negative nitrogen balance, and other secondary effects of diseases, particularly kidney dysfunction.

Clinical Enzyme Tests↗
PubMed1980

Dicyclohexylcarbodiimide binds specifically and covalently to cytochrome c oxidase while inhibiting its H+-translocating activity.

We have investigated the covalent binding of dicyclohexylcarbodiimide (DCCD) to cytochrome c oxidase in relation to its inhibition of ferrocytochrome c-induced H+ translocation by the enzyme reconstituted in lipid vesicles. DCCD bound to the reconstituted oxidase in a time- and concentration-dependent manner which appeared to correlate with its inhibition of H+ translocation. In both reconstituted vesicles and intact beef heart mitochondria, the DCCD-binding site was located in subunit III of the oxidase. The apolar nature of DCCD and relatively minor effects of the hydrophilic carbodiimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide, on H+ translocation by the oxidase indicate that the site of action of DCCD is hydrophobic. DCCD also bound to isolated cytochrome c oxidase, though in this case subunits III and IV were labeled. The maximal overall stoichiometries of DCCD molecules bound per cytochrome c oxidase molecule were 1 and 1.6 for the reconstituted and isolated enzymes, respectively. These findings point to subunit III of cytochrome c oxidase having an important role in H+ translocation by the enzyme and indicate that DCCD may prove a useful tool in elucidating the mechanism of H+ pumping.

Animals↗
PubMed1980

[Computer tomographic and angiographic studies of histologically confirmed intrahepatic masses (author's transl)].

The computer tomographic and angiographic findings in 53 patients with intrahepatic masses were compared. The histological findings show that 17 were due to echinococcus, 12 were due to hepatic carcinoma, ten were metastases, five patients had focal nodular hyperplasia, three an alveolar echinococcus and there were three cases with an haemangioma of the liver and a further three liver abscesses. Computer tomography proved superior in peripherally situated lesions, and in those in the left lobe of the liver. Arteriography was better at demonstrating lesions below 2 cm in size, particularly vascular tumours. As a pre-operative measure, angiography is to be preferred since it is able to demonstrate anatomic anomalies and variations in the blood supply, as well as invasion of the portal vein or of the inferior vena cava.

Angiography↗