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Biomedical subjects

W Schmidt

Publications and source records attributed to W Schmidt.

At least 397 records · Page 22Linked to original sources
PubMed1990

[Choroid metastases in metastatic breast cancer--a rare metastatic site].

Between 1985 and 1989, four patients with uvea metastases of breast cancers were treated in the Dept. of Gynaecology and Obstetrics of the University of the Saar, Medical School, in Homburg/Saar. One of these patients developed binocular metastases. The patient's age at the primary diagnosis of breast cancer was 48 years (median), the others were in pre- or peri-menopausal status. Uvea metastases appeared in median five years after primary diagnosis, always in coincidence with at least one more metastasis of different localisation. All cases with uvea metastases have been treated by radiation therapy with 40 gy reference dose. In three out of five cases, complete remission of the visus restriction could be achieved. In a further case, a temporary partial remission occurred. Two relapses were observed after remission induction, one and four years after treatment respectively.

Adult↗
PubMed1990

[Ultrasound diagnosis of fetal urinary tract abnormalities--incidence, therapy and follow-up].

561 severe foetal malformations were seen from 1975 to 1986 in a total of 17,057 births (3.3%). The urogenital tract was involved in 164 cases only (1.0%). The proportion of malformations of the urinary tract was 29% of all observed anomalies. In 31% of the cases (51 of 164) there were isolated malformations, and in 20% (33 of 164) combined malformations of the urinary tract. 58% (96 of 164) of the urinary tract anomalies definitely belonged to syndromes (e.g. Potter's syndrome). Of 68 newborns with correctable urogenital changes, 42 were diagnosed as obstructive uropathy, 7 of which with urethral valves. A highly critical view is taken of the possibilities of intrauterine therapy in obstructive uropathies.

Abnormalities, Multiple↗
PubMed1990

A transcription factor interacting with the class I gene enhancer is inactive in tumorigenic cell lines which suppress major histocompatibility complex class I genes.

AKR leukemias display different amounts of major histocompatibility complex class I antigens on the cell surface. The absence of H-2Kk molecules correlates with the ability of these cell lines to form tumors in vivo as well as to escape lysis by cytotoxic T lymphocytes in vitro. In this report it is shown that the 5' regulatory area of the H-2Kk gene failed to activate transcription in H-2Kk-negative cells. Examination of the proteins interacting with the H-2Kk enhancer in expressing and nonexpressing cells revealed clear differences. In particular, the level of a nuclear protein interacting at position -166 was greatly reduced in the negative cell lines. A transcription factor, known as H2TF1 or KBF1, has been shown previously to interact with this binding site and to be essential for the expression of certain class I genes as well as the expression of beta 2-microglobulin. These results demonstrate that the molecular mechanism of class I gene suppression in malignant tumor cells is at the level of transcription and is most probably modulated by H2TF1/KBFI. In addition, it is shown that the same transcription factor is only present in mouse tissues expressing class I antigens.

Animals↗
PubMed1990

Differential regulation of plasminogen activator and plasminogen activator inhibitor by osteotropic factors in primary cultures of mature osteoblasts and osteoblast precursors.

Plasminogen activators (PA) and plasminogen activator inhibitors (PAI) have been implicated in the process of extracellular matrix degradation. To study their role in bone matrix turnover, we examined the activity and regulation of PA and PAI in cultures of periosteal osteoblast-like precursor cells and mature osteoblast-like cells from fetal rat calvariae. Both cell populations released PA activity of the tissue type and a 50K PAI species into the culture medium. However, mature osteoblasts had a strikingly lower PA activity and higher PAI activity than periosteal precursor cells, indicating that osteoblast differentiation is associated with a marked decrease in the PA/PAI ratio. PTH and prostaglandin E2 transiently increased PA activity and decreased PAI activity. In contrast, transforming growth factor-beta decreased PA activity and increased PAI activity. Differential effects of these factors on PA and PAI activity may be involved in the regulation of extracellular matrix deposition by osteoblasts.

Animals↗
PubMed1990

[Animal experiments for testing the behavior of compacted bone sections using compression osteosynthesis after hyperthermic denaturation].

In animal experiments on domestic pigs the behaviour of hyperthermically denatured autogenic compact bone grafts after orthotopic replantation was investigated histologically. It was shown that the inductive osteogenetic celldifferentiation of the lair tissue caused by the autogenetic osteoimplantation depends on the location relationship of the replanted bone grafts to the lair bone tissue. This differentiation had progressed after 14 and 21 days further in the upper indifference area than in the contact and fissure healing area.

Animals↗
PubMed1990

[Incidence of pathologic ammonia concentrations in the plasma in children with seizure disorders treated with Convulsofin/Convulex and other anticonvulsants in comparison with children with brain damage and healthy children].

In healthy children plasma ammonia concentrations show values from 12.3 to 57.2 mumol/l (80%-range) (group I). We also measured plasma ammonia in epilepsy patients with valproate therapy (group II) and epilepsy patients treated with other anticonvulsiva (group III). In a fourth group there were children with various cerebral lesions without episodes and without anticonvulsiva therapy. There were significant differences between group I and group II and group II and group IV respectively. But no significant differences were found between the patients who were treated with valproate and the patients with cerebral lesions. The data does not allow the plasma ammonia concentration to be taken as a control parameter in children treated with valproate. Ammonia estimation at the beginning of therapy, however, may be used as risk indicator.

Adolescent↗
PubMed1990

Role of leukotrienes as mediator compounds in brain edema.

Leukotrienes accumulate in brain tissue after cerebral ischemia and in brain tumors. Thus, their release might contribute to the blood-brain barrier damage observed under these conditions and, hence, brain edema. The effect of these substances on the permeability of pial vessels and whether inhibition of LT synthesis reduces cold injury brain edema were studied. The pial vasculature of cats was studied by fluorescence microscopy. The cortex was superfused with LTC4, LTD4, or LTE4 via a cranial window. Na(+)-fluorescein was intravenously administered as blood-brain barrier indicator. LT concentrations up to 2 microM did not induce any leakage of the blood-brain barrier indicator into the parenchyma. However, all LTs tested constricted pial arteries and veins. Brain edema formation was studied in rabbits with cold injury. BW755C, an inhibitor of cyclooxygenase and lipoxygenase preventing formation of LTs, was given before and after trauma. Control animals received saline only. BW755C was ineffective in attenuating cold injury edema. Hemispheric swelling in control animals was 7.8 +/- 1.1%, and 7.7 +/- 0.4% in animals with treatment. LTs, even when administered to the brain in concentrations exceeding levels occurring under pathological conditions, did not induce barrier damage, nor did inhibition of LT synthesis attenuate formation of vasogenic edema. The results provide further evidence against LTs as mediator compounds of this process.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1990

[Bilateral dacryocystography using digital subtraction technic for kinetic evaluation of the lacrimal passage].

For dacryocystography we used the following procedure: after bilateral intubation of either the inferior or superior canaliculi with two galactography tubes connected with an Y-adapter, aqueous contrast medium (Ultravist 370) was injected. The lacrimal pathways were then imaged with the digital subtraction technique (Siemens Polytron), as well as with conventional film. In cases of postsaccal stenosis, the relative delay of contrast medium passage--compared with the normal side--could be specified. A diverticulum of the canaliculus and a transitional cell carcinoma of the lacrimal sac could be demonstrated with both techniques. For the purpose of the post-operative follow-up after dacryocystorhinostomy, bilateral digital dacryocystography is particularly helpful because of the good documentation provided on pathway kinetics. However, digital subtraction dacryocystography cannot fully replace conventional dacryocystography.

Adult↗
PubMed1990

[Calculation of the relative biological efficiency (RBE) of neutron radiation].

The Relative Biological Effectiveness (RBE) of radiation with different LET has to be recognized in the planning of radiation therapy especially if one type of radiation should be replaced by another type or if both should be used within the same irradiation course. In radiation therapy it is suitable to consider the RBE in connection with dose dependent cell survival rates. These rates can be described by means of corresponding mathematical models. A simple way to calculate the RBE on the basis of the modern LQ-model is demonstrated. In that procedure the alpha/beta-ratios which are known at least approximatively for many organs and tissues can be used. The proposed method is demonstrated for the human skin and lung. For these organs we obtained RBE ranges from 3.4 to 1.2 and from 3.8 to 0.8, respectively, considering increasing doses. Thereby, for the lung it can be observed that the dose dependency of the RBE for small doses is especially strong. The obtained results are in good coincidence with experiences in clinical practice.

Dose-Response Relationship, Radiation↗
PubMed1990

[Principles of selective decontamination from the radiobiological point of view].

Presented is the method of selective decontamination by van der Waaj. It is based on the conception of colonisation resistance deduced from animal experiments. So it means the concurrence of defense mechanisms which prevent the settlement of pathogenic germs and stabilize the normal microflora. First clinical and experimental results are reported.

Animals↗
PubMed1989

[The familial carcinoma burden and indications for subcutaneous mastectomy].

Histological examination of the surgical specimen was undertaken in 182 women (aged between 20 and 58 years, mean 44 years) after a subcutaneous mastectomy, which had been performed largely because the diagnosis of the breast lesion had been problematic. Among 46 patients, operated on exclusively because of either palpatory or radiological diagnostic problems, histological examination revealed occult carcinoma or precancerous lesion in two, while among 58 patients with combined palpatory and radiological diagnostic problems there were twelve with invasive or noninvasive carcinoma, and among seven with at least four preoperative biopsies there was none. Four of 41 patients who had previously had a modified radical mastectomy of the other breast for invasive breast cancer had invasive or noninvasive carcinoma, as well as 18 of 30 patients with biopsy-confirmed proliferative breast lesion. There was a statistically significant correlation between the incidence of occult carcinoma and familial incidence. The results indicate that subcutaneous mastectomy is justified in case of diagnostic problems only if (1) in the presence of an increased genetic risk neither palpatory nor radiological diagnosis is clearcut, (2) there is known contralateral carcinoma, or (3) preoperative examination demonstrates proliferative lesions with atypical epithelium.

Adult↗
PubMed1989

[The pharmacokinetics of antilipemic agents. 5. Is 2-(4-hydroxyphenoxy)-2-methylpropionic acid a metabolite of the antilipemic ciprofibrate?].

After oral administration of Ciprofibrate (1) to volunteers (n = 5) only its glucuronide, but no 1 and no 2-(4-Hydroxyphenoxy)-2-methyl-propionic acid (3) could be detected in the fresh urine. Its formation from 1 seems to be impossible on the basis of established biochemical reactions. Therefore, its presence in the urine of volunteers reported by other authors is refuted.

Clofibrate↗
PubMed1989

[The pharmacokinetics of hypolipemic agents. 6. Is 2-(4-(2,2-dichlorocyclopropyl)-phenoxy)-propane a metabolite of the hypolipemic ciprofibrate?].

According to earlier investigations 2-(4-(2,2-dichlorocyclopropyl)-phenoxy)-propane (4) ought to be a metabolite of the hypolipidemic agent ciprofibrate (1). However, 4 could not be detected in plasma or in urine after administration of a dose of 2100 mg 1 during the course of a multiple-dose-study. Therefore, the compound described in literature must be an unknown one and the existence of 4 as a metabolite of 1 is excluded.

Chromatography, High Pressure Liquid↗
PubMed1989

Glutaminase in the postnatally developing rat cerebellum: comparison of staining and immunocytochemistry activity.

Distribution patterns and developmental profiles of phosphate activated glutaminase (PAG) in the cerebellar cortex of the rat were demonstrated by enzyme activity staining (tetrazolium salt technique) and immunolabeling. Histochemical evaluation of enzyme activity stained sections revealed in the molecular and granular layer (i.e. premigratory zone and external germinal zone in neonate rats) an increase from postnatal day 2 to day 50 by 350 and 400%, respectively. The smallest elevation was found in Purkinje cell bodies (140%). Maximum rise of PAG-activity was observed for all of the areas examined between day 12 and 15. The immunocytochemical visualisation of PAG-like immunoreactivity resulted in spatial and developmental patterns which differed from those of PAG-activity staining and displayed, to some extent, dependency on the way of tissue preparation, especially the fixation procedure.

Animals↗
PubMed1989

Changes in plasma volume and red cell formation after a marathon competition.

The purpose of this study was to investigate middle-term influences of a marathon race on plasma volume (PV) and red cell production. We performed the following measurements in the blood of 15 male athletes: haemoglobin ([Hb]), haematocrit (Hct), plasma protein concentration ([Prot]), plasma osmolality, sodium concentration ([Na+]), potassium concentration ([K+]), aldosterone concentration ([Aldo]), haptoglobin concentration ([Hpto]), and the reticulocyte count, as well as the calculation of relative changes in PV, 3 days before and on 3-consecutive days after a marathon race. By the 2nd day of recovery PV had increased by 16%. Plasma osmolality and [K+] remained constant, whereas [Na+] had decreased slightly 2 days after the competition and [Aldo] tended to be elevated 1 day after the competition. [Hpto] was low before and 1 day after the competition and increased on the following days. Reticulocyte count was unaffected 1 day after the race, but increased by 106% on the 2nd day and was still elevated after 3 days. The causes for higher post-marathon plasma volumes and reticulocyte counts could be in the complex variations in hormonal regulation, which have not yet been sufficiently investigated.

Adult↗