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Biomedical subjects

W Steinke

Publications and source records attributed to W Steinke.

71 records · Page 4Linked to original sources
PubMed1989

High-resistance Doppler flow pattern in extracranial carotid dissection.

Internal carotid artery dissection is an increasingly recognized cause of cerebrovascular events. The diagnosis is conventionally established on the basis of characteristic clinical symptoms and arteriographic findings. However, the presence of characteristic hemodynamic features detected by ultrasound may already suggest the diagnosis, even in atypical cases. This is demonstrated in 16 (76%) of 22 patients with internal carotid artery dissection. An intense systolic low-frequency Doppler signal of alternating flow direction accessible in the neck, either along the extent of a luminal tapering stenosis or proximal to a severe obstruction at the skullbase, indicated this diagnosis. Resolution or decreasing stenosis may similarly be diagnosed noninvasively, as shown by results from subsequent arteriograms in 14 patients (64%). This occurred suddenly during sequential follow-up between 2 days and 30 weeks (mean, 6 weeks) after the diagnosis was made.

Adolescent↗
PubMed1989

Good recovery after sublethal ethylene glycol intoxication: serial EEG and CT findings.

The case of a young man with sublethal ethylene glycol poisoning is reported. Complete recovery occurred after 12 days of deep coma and a prolonged flaccid tetraplegia. The lesions of gross degree in the CNS, demonstrated by serial CT, resolved and electrophysiological testing as well as neuromuscular signs improved. The recovery, clinically and radiographically, over 35 days was dramatic. Ethylene glycol intoxication should always be considered in the differential diagnosis of acute severe encephalopathy because complete recovery is possible with correct therapy.

Adult↗
PubMed1989

[Duplex sonography of the internal jugular vein].

Based on defined diagnostic criteria high-resolution Duplex sonography allows the accurate evaluation of normal and pathological jugular vein. Compared to examinations with only the B-mode the diagnostic accuracy is higher with the duplex system with additional display of venous flow signals. Normal findings and results of duplex sonography in patients with venous inflow congestion, thrombosis and aneurysm of the jugular vein are presented, and their clinical relevance of the method discussed.

Aneurysm↗
PubMed1989

Autoradiographic localization of [125I]endothelin-1 and [125I]atrial natriuretic peptide in rat tissue: a comparative study.

The autoradiographic localization of [125I]endothelin-1 (ET-1) and [125I]atrial natriuretic peptide (ANP) after i.v. administration has been investigated in rats. Labeled peptides are rapidly distributed to tissues and peripheral organs. After administration of [125I]ET-1 (1-21), the highest enrichment of radioactivity was found in the lung, kidney, liver, adrenal gland, and heart. After administration of [125I]ANP (1-28), the highest levels of radioactivity could be observed in the kidney, adrenal gland, and endocardium. Compared to blood levels in both cases, a relative enrichment of radioactivity is also found in the vascular wall of the aorta. For ANP, no distribution of radioactivity in the lung could be observed. Other organs, especially the kidney and the adrenal gland, showed a similar distribution pattern with respect to substructures.

Animals↗
PubMed1989

Doppler color flow imaging of carotid body tumors.

Doppler color flow imaging is a new ultrasound method for the simultaneous spatial display of tissue and vessel morphology (B-mode echotomograms) and of color-coded blood flow velocity information (Doppler-mode analysis). This new method is particularly useful in the neck, not only for the assessment of brain arteries but also for the safe and valid identification of carotid paragangliomas compared with other neck tumors. Early clinical detection of carotid paragangliomas is difficult since these lesions often occur sporadically and the patients remain symptom-free until the tumor becomes noticeable. Doppler color flow imaging allows the diagnosis of even small paragangliomas, which may improve management because of existing complications of surgical therapy.

Adult↗
PubMed1989

Pharmacokinetics of rioprostil in rats.

The pharmacokinetics of rioprostil in rats has been investigated following a single intravenous or oral dose of rioprostil between 0.004 and 10 mg/kg. Rioprostil is eliminated from plasma following an intravenous dose rapidly (t1/2 = 0.22 h) and nearly exclusively by biotransformation. The high total clearance (CL = 5.4 l.h-1.kg-1) indicates an additional extrahepatic metabolism. A systemic bioavailability of 2%, in spite of a rapid and nearly complete absorption (fa = 90%), indicates an extended first-pass effect. Twenty-four hours after the administration of [3H]rioprostil the residual radioactivity in the animal amounted to less than 1% of the dose administered.

Animals↗
PubMed1989

Pharmacokinetics of acarbose. Part II: Distribution to and elimination from tissues and organs following single or repeated administration of [14C]acarbose to rats and dogs.

Acarbose (O-4,6-dideoxy-4-[[1S,4R,5S,6S)-4,5,6-trihydroxy-3- (hydroxymethyl)-2-cyclohexen-1-yl]amino]-alpha-D-glucopyranosyl- (1----4)-O-alpha-D-glucopyranosyl-(1----4)-D-glucopyranose, Bay g 5421) labelled with 14C was administered to male rats, pregnant and lactating rats as well as to female dogs with single intravenous or oral doses (2 or 4 mg.kg-1) and with repeated oral doses of 2 mg.kg-1 to male rats for 3 weeks. The distribution of radioactivity to organs and tissues, the placental transfer and the secretion into milk was studied using whole-body autoradiographic methods and/or quantitative determination of total radioactivity after autopsy. Unchanged [14C]acarbose was distributed predominantly in the extracellular space, as observed after intravenous dosing to rats. According to the main excretion route, high concentrations were found in kidneys and urine and additionally in blood, lung, and connective tissue or interstitial space. The permeability of the blood/brain barrier for [14C]acarbose and/or its metabolites was very low. No indication was found for distinct differences in the distribution patterns in rats and dogs after intravenous and also in dogs after oral administration. In contrast, in rats after oral dosing the distribution pattern of radioactivity was different with relatively high concentrations in liver, kidney, adrenal gland, spleen, and intestinal mucosa. Due to the slow absorption of the microbial degradation products of [14C]acarbose from the intestine maximum concentrations in the different tissues were reached 8-24 h after dosing.(ABSTRACT TRUNCATED AT 250 WORDS)

Acarbose↗
PubMed1989

Autoradiographic localization of 125J-endothelin in rat tissues.

A potent peptidergic vasoconstrictor in vitro and in vivo termed endothelin has been isolated from the supernatant of cultured endothelial cells. The autoradiographic localization of 125J-endothelin has been studied after intravenous administration in rat tissues. Highest enrichment of radioactivity was found in kidney and lung. Activity was also detected, especially in vascular wall of the aorta and adrenal gland.

Animals↗
PubMed1988

The pharmacokinetics of nitrendipine. II. Distribution to and elimination from organs and tissues of rats and dogs after single or repeated administration of [14C]nitrendipine.

[14C]nitrendipine (3-ethyl 5-methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridine dicarboxylate, Bay e 5009, Baypress, Bayotensin) was administered to male rats, pregnant and lactating female rats, and female dogs intravenously or orally once as well as to male rats repeatedly over a period of 4 weeks (rat 5 (and 10) mg/kg, dog approximately 3 mg/kg). The distribution of radioactivity (unchanged compound and metabolites) was investigated using whole-body autoradiography as well as quantitative measurements of the organ and tissue concentrations of radioactivity after necropsy. [14C]nitrendipine was distributed rapidly and heterogeneously into the organs and tissues of rats. Already 24 h after administration most of the radioactivity had reached the gastro-intestinal (GI) tract via biliary secretion. High concentrations were also detectable in liver and kidneys. The radioactivity was eliminated from the tissues with terminal half-lives lying between 52 (plasma) and 360 h (muscle). Only 0.13% of the administered radioactivity was detectable in the body (excl. GI-tract) after 10 days. In dogs, the distribution pattern was similar to that observed in rats. After 28 daily administrations of [14C]nitrendipine to male rats the plasma and tissue equivalent concentrations were 3 (plasma) to 12 times (adipose tissue) higher than after single administration. The half-lives were increased by 20 to 70%, lying between 2 and 15 days. There were no indications for any specific retention of the radioactivity. The radioactivity from [14C]nitrendipine was secreted into the milk of lactating rats and crossed the placental barrier.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗
PubMed1986

Distribution of [14C]-ciprofloxacin in experimentally induced intramuscular abscesses of rats.

Wistar rats were infected by injection of 0.05 ml of a dense oily suspension of Staphylococcus aureus into the posterior thigh muscles of the hind leg. Three days later, solid abscesses had formed which were characterized by a peripheral accumulation of polymorphocytes and incipient central necrosis. At this time, 10 mg/kg of [14C]-ciprofloxacin (1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-piperazin-1-ylquino line-3-carboxylic acid, Bay o 9867; designated tradename: Ciprobay) were administered intravenously. The animals were sacrificed at various time intervals after treatment and the distribution of radioactivity was examined by whole-body autoradiography. Five min after administration of ciprofloxacin, the radioactivity was found to be differentially distributed among all organs and tissues, but no radioactivity was detectable in the abscess. Beginning from 1 h post appl., increasing relative amounts of radioactivity were seen inside the abscesses. The relative enrichment as compared to the surrounding muscle tissue was most pronounced after 5 h, indicating that the radioactivity was eliminated more rapidly from the muscle than from the abscess. Some radioactivity was still present in the abscess 8 h after treatment of the animals. The comparison of autoradiograms and corresponding histological sections revealed a distinct affinity of [14C]-ciprofloxacin and/or its potential radioactive metabolites to the areas of inflammatory cellular infiltrates.

Abscess↗
PubMed1979

Antiphytoviral activity of 2,4 dioxo hexahydro triazine.

Three treatments with 2,4 dioxo hexahydro triazine (DHT) significantly reduced the concentration of potato virus X (PVX) in systemically infected tobacco plants. In hypersensitive plants DHT caused a reduction in the number of local lesions produced by PVX. In systemic and hypersensitive hosts, treatment with DHT resulted in a more or less marked reduction in the concentration of, and in the number of local lesions caused by, potato virus Y (PVY), potato virus A (PVA), tobacco mosaic virus (TMV), and cucumber mosaic virus (CMV). Three days after treatment with DHT the incorporation of 32P into TMV RNA was significantly reduced, while that into host RNA was less affected.

Antiviral Agents↗
PubMed1979

[Dioxohexahydrotriazine, a new synthetic antiphytoviral compound (author's transl)].

This paper reports the first results of studies made to determine the antiviral activity of dioxo hexahydro triazine, a newly developed antiphytoviral compound. After treatment with dioxo hexahydro triazine, the concentration of helical potato virus X in leaves of Nicotiana tabacum "Samsun" was found to be considerably reduced in both the serological test and local lesion test conducted on Nicotiana glutinosa at temperatures of 14 degrees C +/- 3 degrees C. In secondarily infected leaves, the reduction of the concentration of potato virus X in the range of from 1 mol/l to 10(-3) mol/l was so that it was no longer possible for viruses to be detected serologically. In vitro, however, dioxo hexahydro triazine, which was added to the inoculum, did not produce a significant change in the activity of the virion of potato virus X. Therefore, it is reasonable to assume that dioxo hexahydro triazine tends to affect replication steps of viruses. The use of dioxo hexahydro triazine also had the effect of greatly and highly significantly reducing the concentration of the isodiametric cucumber mosaic virus.

Antiviral Agents↗
PubMedDate not supplied

Posterior cerebral artery territory infarcts: clinical features, infarct topography, causes and outcome. Multicenter results and a review of the literature.

Only a few large series of posterior cerebral artery (PCA) stroke exist, and clinical features and causes have not been studied as extensively as in other vascular territories. The PCA syndrome includes more clinical signs than the well-known visual field deficits. Concomitant findings are frequently sensory, slight motor and neuropsychological deficits. Unilateral headaches are the common presenting symptom making complicated migraine an important differential diagnosis. Combined deep and superficial PCA territory infarcts involving the lateral thalamus are more frequent than commonly assumed and are mostly associated with sensory and reversible slight motor deficits. Occlusion of the precommunal PCA segment with associated paramedian midbrain infarction causes severe motor deficits, oculomotor signs, and decreased consciousness and has a poorer outcome than other PCA territory infarcts. Embolism from a cardiac or undetermined source is the leading mechanism accounting for up to half of the cases, whereas arterial embolism from significant proximal vertebrobasilar disease is less frequent. Local atherothrombotic stenosis or occlusion of the PCA is uncommon. In spite of thorough diagnostic evaluation, the etiology of PCA territory infarction cannot be determined in at least one quarter of patients. Among the rare causes of PCA territory infarction carotid artery disease is important while the significance of migraine remains controversial.

Cerebral Infarction↗
PubMedDate not supplied

Carotid artery disease assessed by color Doppler flow imaging: correlation with standard Doppler sonography and angiography.

Carotid artery disease was assessed in 180 patients by means of color Doppler flow imaging. Color Doppler findings in 360 carotid arteries were compared with the results of standard Doppler sonography, and color Doppler findings in 60 bifurcations were compared with the results of intraarterial angiography. The sensitivity of color Doppler for the detection of carotid disease was 100% when compared with angiography. The accuracy of color Doppler in classifying minor (40-60%), moderate (61-80%), and severe (81-90%) stenosis ranged from 91.3% to 97.8% vs standard Doppler sonography, and from 91.7% to 95.8% vs angiography. Whereas all occlusions were identified correctly by both color Doppler and angiography, four pseudoocclusions of the carotid artery were misdiagnosed as occluded. Characteristic features providing reliable criteria of the degree of stenosis are (1) intensity, extent, and duration of color fading; (2) postprocessed systolic peak frequency; (3) plaque extent on serial sonograms; and (4) poststenotic flow patterns. Display of hemodynamic disturbances induced by less pronounced plaques showed highly variable patterns that could not be anticipated from the plaque morphology alone. Thus, color Doppler preserves the advantages of standard Doppler and duplex sonography but provides additional information about otherwise anechoic necrotic and thrombotic material that often causes cerebral embolisms. With atherogenesis, repair mechanisms may be sustained or progression be stopped by reducing the risk factors and instituting medical treatment; thus, the application of this noninvasive technique is important.

Carotid Artery Diseases↗