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Biomedical subjects

A Schmidt

Publications and source records attributed to A Schmidt.

At least 541 records · Page 30Linked to original sources
PubMed1988

[Primary liver tumors in childhood: an analysis of 19 cases].

Nineteen patients were operated on for primary liver tumors at our hospital from 1970 to March 1987. Among malignancies, hepatoblastomas and hepatocellular carcinomas were equally often seen (7 cases each), among benign tumors, there were 3 hemangioendotheliomas and 2 hemangiomas. In 6 of the 14 children with malignant tumors, only a biopsy could be performed due to primary inoperability, tumor excision was possible in 8 cases. Following chemo-embolisation, tumor excision could be carried out in a second-look operation in one case. Six patients with hepatoblastoma died within 6 months following diagnosis, 2 of them, however, succumbed to therapeutical side effects. Four of the seven patients with hepatocellular carcinoma were alive after a mean follow-up of 6.4 years (2-15 years).

Adolescent↗
PubMed1988

Mechanical properties of isolated fetal miniature pig lungs after substitution with fluorocarbons.

In our present study we tried to inflate and stabilize isolated immature lungs of fetal minipigs in gestation age of 95 days (= 85% of total normal gestation period) with different fluorocarbons. Based on our previous experiences, the immature lungs at day 95 are almost non inflatable with air. For our experiments we used fluorocarbon 43 (FC-43) with a surface tension of 16 mN/m and fluorocarbon 72 (FC-72) with a surface tension of 12 mN/m. Eighteen fetal immature lungs were used. In group 1 the lungs were rinsed with FC-43; in group 2 the rinse solution was FC-72, and in group 3 the lungs were untreated. After removing the fluorocarbon, in the case of groups 1 and 2, the lungs were artificially ventilated. Pressure-volume (p-v) curves were registered in the beginning (immediately after FC lavage), after 10 and 20 min of artificial ventilation. Airway opening pressure (pi) and weight-specific end-inspiratory lung compliance (ci) were investigated. Statistically significant differences in weight-specific end-inspiratory compliance were found between FC groups and untreated group 3, but no stabilization could be seen during the investigation period of 20 min. No statistically significant improvement in weight-specific end-inspiratory compliance was observed between group 1 and 2, although the compliances of group 2 with FC-72 were better than those of group 1 with FC-43 in three p-v diagrams registered in the beginning and after 10 and 20 min of artificial ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Cell-associated proteoheparan sulfate from bovine arterial smooth muscle cells.

Cell-associated proteoheparan sulfate has been isolated from bovine arterial smooth muscle cells preincubated with [35S]sulfate or a combination of [3H]glucosamine and [35S]methionine. The purified proteoheparan sulfate had an apparent Mr of 200,000 on calibrated Sepharose CL-2B columns. The glycosaminoglycan component (Mr approximately 30,000) was identified as heparan sulfate by its susceptibility to specific enzymatic and chemical degradation. After degradation of the proteoheparan sulfate by microbial heparitinase the resulting protein core had an apparent Mr of 92,000 on SDS-polyacrylamide gels. Its mobility was similar in the absence and presence of reducing agents indicating that the protein core consists of a single polypeptide chain. Pulse-chase experiments revealed that about 40% of the cell layer-associated proteoheparan sulfate was released into the medium, while the remainder was internalized and converted to smaller species through a series of degradation steps. Initially there was a proteolytical cleavage of the protein core generating glycosaminoglycan peptide intermediates with polysaccharides chains similar in size to the original. The half-life of the native proteoheparan sulfate was found to be about 4 h.

Animals↗
PubMed1988

A 17-kDa protein induced in rat myometrium by hormonal treatment.

A 17-kDa protein mainly recovered in the myometrium fraction sedimenting at 10,000 g has been induced by estradiol treatment in spayed rats. Tamoxifen completely inhibited the effect of estradiol, and progesterone decreased it by 50%. The protein was scarce in unspayed animals and the level after estradiol treatment remained much lower than in spayed rats. Oral doses of the potent antiprogesterone RU 38486 increased the level of the 17-kDa protein in unspayed animals. It was not present in immature or gestating rats or in the endometrium or myometrial cell cytosol of any of the rats. Following electrophoretic purification, it bound calmodulin, but was not phosphorylated by cAMP protein kinases.

Animals↗
PubMed1988

New generator for low pressure lithotripsy with the Dornier HM3: preliminary experience of 2 centers.

The technical innovation of a low pressure generator with a standard ellipsoid installed into the Dornier HM3 lithotriptor leads to a decrease in pressure at the second focus by 30 per cent. The preliminary experience with 273 patients treated at 2 centers is presented. The success rate in terms of stone disintegration was similar compared to the old generator (96 versus 97 per cent). However, the rate of secondary treatments increased from 8 to 15.5 per cent, respectively. Owing to the lower peak pressures at the second focus, an additional 700 impulses per session were necessary. The method of anesthesia was changed to a combination of an anxiolytic and analgesic drug in the majority of the patients. Treatment was judged as free of pain or with easily tolerable pain in 93 and 88 per cent of the patients, respectively.

Anesthesia, Epidural↗
PubMed1988

Ergogenic effect of inhaled beta 2-agonists in asthmatics.

To investigate the effect of beta 2-agonists on exercise performance, eight asthmatics performed an incremental exercise test on a treadmill. Five minutes before the start of the exercise, they were treated with inhaled salbutamol or placebo in a double-blind manner. The exercise started at a low intensity (2 mph, 10% inclination), and every 3 min the speed was increased by 0.5 mph at the same inclination until the subjects were exhausted. Every minute peak expiratory flow, heart rate, blood lactate concentration, and rating of perceived exertion were measured. The same parameters were also measured following the completion of the exercise. No significant difference was seen in total working time, maximal lactate concentration, heart rate, or rating of perceived exertion, whereas the decrease in peak expiratory flow was reduced following pretreatment with salbutamol. It is concluded that the release of inhaled beta 2-agonists for use in competitive events is justified as no ergogenic effect was seen.

Adrenergic beta-Agonists↗
PubMed1988

Ligand-induced stimulation of epidermal growth factor receptor mutants with altered transmembrane regions.

The epidermal growth factor (EGF) receptor is a transmembrane glycoprotein composed of a large extracellular ligand-binding region connected to the cytoplasmic kinase domain by a single transmembrane (TM) region. To explore the role of the TM region in the process of receptor activation, we have generated EGF-receptor mutants with altered TM regions by utilizing in vitro site-directed mutagenesis. The TM regions of two mutant receptors were either extended (designated i626-3) or shortened (designated d625.3) by three hydrophobic amino acid residues. In the other two mutant receptors, hydrophobic amino acids were substituted by charged residues--i.e., Val-627 was replaced by glutamic acid (designated V627E) or Leu-642 was replaced by an arginine residue (designated L642R). NIH 3T3 cells lacking endogenous EGF receptors were transfected with constructs encoding either wild-type or mutant receptors and shown to express the receptor molecules using 125I-labeled EGF binding and immunoprecipitation experiments. The mutant receptors were expressed on the cell surface as polypeptides of Mr 170,000 exhibiting typical high- and low-affinity binding sites for 125I-labeled EGF. Similar to its effect on wild-type receptors, phorbol 12-myristate 13-acetate abolished the mutant-receptor high-affinity binding sites for EGF. Moreover, EGF was able to stimulate the kinase activities of wild-type and mutant receptors both in vitro and in living cells. The mutant receptors were also able to undergo EGF-induced receptor dimerization as revealed by cross-linking experiments with a bifunctional covalent cross-linking agent. These results are compatible with an intermolecular allosteric oligomerization model for receptor activation rather than with a model based on an intramolecular mechanism for receptor activation.

Animals↗
PubMed1988

Pathophysiology of unstable angina pectoris--correlations with coronary angioscopic imaging.

Different patho-anatomical and functional factors are considered to be involved in patients with unstable angina pectoris. Among these are a pre-existing plaque based on coronary atherosclerosis, the development of fissures or dissections of the plaque (often combined with thrombus formation at the site of the plaque) coronary vascular tone, and theoretically primary aggregation of platelets at a site of apparently normal vascular endothelium. Several comprehensive studies on patients who died from acute myocardial infarction or unstable angina, have convincingly shown that complications of an atherosclerotic plaque like fissures, dissections and thrombus formation may be present in 60 to 90% of cases. In addition, two groups of investigators, who have applied coronary angioscopy for direct visualization of offending coronary arteries, have confirmed these results, since in about 60-80% of patients with unstable angina complicated atheromata, i.e. rupture, ulceration, thrombus formation, could be documented, whereas in all patients with stable angina an uncomplicated atheroma was seen angioscopically. On the basis of these results a hypothetical sequence of events in patients with stable angina, unstable angina and acute myocardial infarction has been proposed. Stable angina pectoris may be seen in patients with uncomplicated atheroma in one of the major coronary artery branches. When dissections, ulcerations and thrombus formation occur as a complication of a formerly smooth plaque, patients show the clinical syndrome of unstable angina. If an occlusive thrombus develops, the patient will run into a fresh myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1988

A comparative study of the effects of two different doses of nedocromil sodium and placebo given by pressurised aerosol in exercise-induced bronchoconstriction.

Fourteen adult subjects with stable asthma were treated using a double-blind crossover, randomised protocol, with either nedocromil sodium (4 mg or 2 mg) or placebo. The agents were administered from matched pressurised aerosol inhalers 30 min before exposure to an exercise regimen which, on a previous screening day, resulted in a 24-53% (mean: 33.9%) decrease in peak expiratory flow (PEF). Both doses of nedocromil sodium were significantly superior to placebo in preventing the exercise-induced decrease in PEF and were without side effects. This study confirms and extends the results of earlier trials with nedocromil sodium and further supports the contention that this new agent may be of benefit in the treatment of reversible obstructive airways disease in the adult patient.

Administration, Inhalation↗
PubMed1988

Tyrosine O-sulfate ester in proteoglycans.

Tyrosine O-sulfate residues were detected in the protein core of sulfated proteoglycans. When cultured skin fibroblasts and arterial smooth muscle cells were incubated in the presence of [35S]sulfate, dermatan sulfate proteoglycan and chondroitin sulfate proteoglycan isolated from the culture medium contained tyrosine [35S]sulfate ester which accounted for 0.03%-0.82% of total 35S radioactivity incorporated into the sulfated proteoglycans. This corresponds to a tyrosine sulfation of every second (fibroblasts) and every 10th (smooth muscle cells) dermatan sulfate proteoglycan molecule. [3H]Tyrosine labeling of fibroblast dermatan sulfate proteoglycan gave a similar stoichiometry. However, the relative proportion of tyrosine [35S]sulfate in proteoglycans from arterial tissue was about 10 times higher than in that from cultured arterial cells. Pulse chase experiments with [35S]sulfate revealed that tyrosine sulfation is a late event in the biosynthesis of dermatan sulfate proteoglycan from fibroblasts and occurs immediately prior to secretion. Cultured skin fibroblasts from a patient with a progeroid variant (Kresse et al. 1987, Am. J. Hum. Gen. 41, 436-453) which exhibit a partial deficiency to synthesize dermatan sulfate proteoglycan were shown to form and to secrete a tyrosine-sulfated but glycosaminoglycan-free protein core, thus confirming a selective and independent [35S]sulfate labeling of the protein core.

Animals↗
PubMed1988

[Drug therapy of coronary heart disease following thrombolysis and PTCA or bypass operation].

Successful thrombolysis with reperfusion and salvage of jeopardized myocardium frequently necessitates invasive therapeutic strategies such as angioplasty or bypass surgery. Medical treatment in this situation has to consider the possibility of recurrence of infarction before invasive measures can be obtained. It must be specially directed towards preventing such an event, besides applying therapeutic measures in the acute and subacute phase after myocardial infarction. Several different therapeutic principles were considered: 1. In the days after thrombolysis with or without PTCA anticoagulants, mostly in the form of heparin, are used routinely in an attempt to prevent reocclusion and reduce thromboembolic complications. The latter indication seems to yield the most benefit of this type of drug. 2. Platelet-modifying drugs reduce the risk of reocclusion after thrombolysis and PTCA. The vein graft patency seems to be higher after aspirin treatment than after coumarine therapy. A reduction of coronary events was reported especially in patients with non Q-wave infarction, a situation particularly liable for reinfarction. 3. Calcium antagonists are used widely after PTCA to attenuate coronary spasm. No global beneficial effects have been observed after bypass surgery and in the therapy of acute myocardial infarction. Special indications e.g. for certain types for arrhythmias remain unchanged after thrombolysis, PTCA and bypass surgery. 4. Antianginal drugs with nitrates and betablockers are indicated to relieve symptoms in the acute phase. In chronic treatment, prevention of reinfarction and reduction of mortality was reported after the use of betablockers, the latter mainly by increasing the fibrillation threshold, thus reducing deaths due to arrhythmias.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1988

[Information concerning radiation-induced sarcomas. Report on 2 cases].

Two cases of radiation-induced sarcomas are presented. Osteosarcomas developed in the frontal bone after a latency period of 36 years following operation for brain tumor with post-operative irradiation (48 Gy) in one patient and in the region of the right sacro-iliac joint after ablation of testis for seminoma with post-operative irradiation (60 Gy) in another patient. In the literature, the risk of developing an irradiation-induced sarcoma is considered to be low (0.05-0.2%). Both cases, however, underline the necessity of an exact indication for irradiation to avoid such complications.

Adolescent↗
PubMed1988

[Experimental studies in animals of the regeneration of peripheral nerves].

In bridging nerve gaps and studying the process of nerve regeneration the method of "tubulation" becomes of new worldwide importance during the last years. In this technique the both stumps are introduced in a preformed tube without tension, the further healing process is left to the neuron's potency for self-repair. Although until now the experimental results confirm the possibility of this management it is often impossible to compare the findings because of the insufficient quantitative analyses. In this paper the own results of bridging a 4-6 mm defect in rat sciatic nerves with a connective tissue-teflon-tube are presented including an extensive quantitative analysis with methods of computer-based multivariate data analysis. The theoretic advantages of this technique are discussed in relation to the autologous interfascicular nerve transplantation.

Animals↗
PubMed1988

Association of thrombospondin of endothelial cells with other matrix proteins and cell attachment sites and migration tracks.

Different biochemical and cytochemical techniques were applied to characterize the sites of localization of thrombospondin in cultured endothelial cells. The results obtained by [35S]methionine labeling, immunoblotting, immunoprecipitation, fluorescence microscopy, ultracytochemistry, immunogold labeling, and silver enhancement experiments revealed that thrombospondin secreted by endothelial cells is structurally organized together with proteoheparan sulfate in spherical granules at the cell surface. These granules are about 100 to 300 nm in size. Heparin or enzymatic degradation with heparitinase, but not with ABC lyase, release thrombospondin from the cell surface. Fibronectin is expressed in the extracellular matrix of endothelial cells in a fibrillar organization, clearly distinct from the punctate pattern of thrombospondin on the cell surface. Furthermore, secreted thrombospondin is highly enriched together with fibronectin and proteoheparan sulfate in cell attachment sites and in cell migration tracks. In cell migration tracks proteoheparan sulfate more clearly resembles the fibrillar distribution pattern of fibronectin, whereas thrombospondin reveals a rather monodisperse pattern. The obtained data suggest preferential sites of interaction between thrombospondin and heparan sulfate proteoglycans on the cell surface and a participation of thrombospondin in cell adhesion and cell migration.

Animals↗