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Biomedical subjects

W Schmidt

Publications and source records attributed to W Schmidt.

At least 595 records · Page 33Linked to original sources
PubMed1983

[Significance of ERA for differentiating hearing disorders of different origins].

The reliability on audiometric findings in hearing disorders of different genesis has been considerably improved by the ERA. By no means, the ERA can replace the conventional hearing tests, rather it is an additional technique of examination. Apparently it does not reveal specific findings of psychogenic hearing disorders - unless the prolongation of the cortical response as repeatedly seen by us. In case of aggravation ERA renders us possible to detect the kind of hearing defects and the actual threshold - e.g. with respect to high frequency range by brain stem responses, for 500 and 1,000 Hz according to the cortical responses. The neural hearing impairment caused by tumours always exhibits extremely prolonged latencies even at high intensities, eventually concomitant with a response threshold elevated versus the subjective threshold. These reactions, above all, become apparent in the brain stem rather than in the cortex. In contrast to this the sensoric hearing disorders the ERA elucidates even objectively the recruitment: normal latencies at high intensities. The latency of the objective response, thus, corresponds to the sound stimulus is perceived loud, and it is long for stimuli perceived relatively low - even in spite of great intensity. Comprising the ERA the quote of audiometric failures in excluding an acoustic neuroma is reduced to a minimum.

Adolescent↗
PubMed1982

Expression of murine H-2Kb histocompatibility antigen in cells transformed with cloned H-2 genes.

Cosmids containing H-2 histocompatibility antigen genes of the H-2b haplotype have been isolated. One of these genes expresses a 45,000 molecular weight protein, indistinguishable from H-2Kb when introduced into mouse L cells. These H-2Kb transformed L cells can be killed by allospecific anti-H-2Kb cytotoxic T cells. Moreover, when infected with influenza virus, they can be killed by an H-2Kb-restricted, influenza virus-specific cytotoxic T cell line. These results show that expression of the H-2Kb gene product on the L-cell surface is sufficient to make it a target for specific T-cell killing.

Animals↗
PubMed1982

[Cell-mediated immune reactivity in skin tests in chronic liver diseases].

For the judgment of cell-mediated immune reactivity in patients with chronic liver diseases in comparison to healthy test persons tests of the skin were performed by means of the neoantigen DNCB and the recall antigens tuberculin and streptokinase. Depending on the degree of severity of the hepatopathies the intensity of reaction decreased in the DNCB-test. There were no relations to the etiopathogenetic factors of the liver diseases. The results speak for the fact that the disturbed immune reactivity to DNCB is to be regarded as sequela of the disease. The anamnestic immune response controlled by means of the two recall antigens did not show any quantifiable differences to the reference collective in the chronic hepatopathies. It is concluded that the findings of skin tests are not able to contribute to the indication for immunosuppressive or immune modulating therapeutic methods.

Chronic Disease↗
PubMed1982

Resistance to cell-mediated cytotoxicity is correlated with reduction of H-2K gene products in AKR leukemia.

AKR leukemia cell lines differing in the amount of H-2K and H-2D antigens expressed on the cell surface were used to assess cell-mediated immune responses in syngeneic mice against Gross/AKR murine leukemia virus (MuLV)-induced tumors. Leukemic cells with reduced expression of H-2Kk antigens were inactive as inducers of Gross-MuLV/H-2k-specific cytotoxic T lymphocytes (CTL) and resistant to lysis by CTL raised against H-2Kk positive AKR leukemia cells. H-2Kk positive leukemias induced cytotoxic effectors, which upon restimulation in vitro, lysed the stimulating and other H-2Kk positive leukemia cells. In antibody inhibition experiments, T-cell-mediated cytotoxicity to these leukemias could only be inhibited by antisera and monoclonal antibodies specific for the H-2Kk antigens. Due to this specific role of H-2Kk antigens in T-cell cytotoxicity to Gross/AKR MuLV-induced tumors, reduced expression of H-2Kk antigens on spontaneous AKR leukemic cells could have important implications for surveillance of these neoplastic cells.

AKR murine leukemia virus↗
PubMed1982

Aspects in diagnostics of central neural hearing disorders.

The central neural hearing disorders - in contrast to central cortical lesions - can be concretely defined audiometrically, and they can be localized realiably within the 2nd-4th neurons. For this purpose a definite test program is needed; especially indicative are the behavior of the acoustico-facial stapedius reflex and the results in dichotic discrimination and ERA. SISI and difference limen mostly point to a neural dysfunction, but - in distinct patterns of impairment - they may correspond to the picture of a peripheral hearing disorder as well. A fatigue of hearing apparently only appears if the myelin is damaged, at - perhaps additional - axonal lesions it shows up less clearly or not at all. The deficiency pattern of the stapedius reflex reflects up less clearly or not at all. The deficiency pattern of the stapedius reflex reflects the course of the reflex arc within the brain stem; accordingly, more central lesions of the auditory pathway do not affect the reflex. ERA mostly makes perceivable a lesion of synchronization, which only becomes noticeable at fast repetition rates with ultra short stimuli (1/4 ms), i.e., solely in the responses of the brain stem. The cortical responses, on the contrary, are not impaired more than the subjective threshold renders to be expected, they even show the same values of the pure tone audiogram. The dichotic discrimination is nearly always disturbed unilaterally, at processes of the brain stem homolaterally, at cortical foci predominantly leftside, perhaps because the left hemisphere dominates in speech discrimination. The otologist should know how to make use of the possibility of neuro-otologic diagnostics.

Adult↗
PubMed1982

Ultrasonographic diagnoses of major lymphatic system abnormalities prior to 20 weeks of pregnancy.

Prenatal ultrasound diagnoses of severe lymphatic system abnormalities were obtained in three fetuses. In all three cases the diagnosis was established prior to 20 wk of pregnancy, i.e. early enough to allow selective termination. In all three cases male fetuses with a chromosomal anomaly were found. Alpha-fetoprotein values were not elevated. In all cases the fetal abnormalities were of such size that surgical excision could not be taken into consideration to provide satisfactory results for the infants.

Abortion, Therapeutic↗
PubMed1982

On the environment and the rotational motion of amphiphilic flavins in artificial membrane vesicles as studied by electron paramagnetic resonance spectrometry.

This paper continues the studies of vesicle-bound flavins ('anisotropic flavin chemistry'). It is possible to anchor the flavin nucleus in various modes within the lipids/water interface by means of long aliphatic chains and using different saturated lipids, thereby mimicking the specific binding of the coenzyme to the apoprotein in flavoproteins. Based on absorption spectroscopy and EPR spectroscopy studies we explored the rotational mobility and the microenvironment of membrane-bound amphiflavin radicals. N(5)-unsubstituted amphiflavin radicals exhibit a similarly high disproportionation constant as known from isotropic flavin chemistry. However, reasonable stabilization of the radical was achieved by introduction of an alkyl group in position 5 in the reduced state prior to the one-electron oxidation. Adopting the fine structure of the corresponding EPR spectra as assay for the mobility of the semiquinone, we determined rotational relaxation times ranging from 60 ns in the crystalline state down to 10 or 15 ns in the liquid-crystalline state of the membrane. The solvatochromic effect shown by absorption spectra of the membrane-bound flavin radicals reflects a dielectric constant of the microenvironment of c = 30-40, corresponding to the lipid/water interface region. The results obtained in this study are consistent with those obtained previously, from fluorescence analyses, supporting our former conclusions.

Flavins↗
PubMed1982

[Comparative studies of various echomammography techniques].

Until now it is not clear which echographic scanning technique is most effective and economic for breast examination. To answer this question we examined in a special study 189 patients with the following scanning units: 1. automated immersion scanning technique, 3 MHz (Octoson, Ausonics) 2. manual compound scanning unit (skin contact), 5 MHz (80 LDI, Picker) 3. linear array realtime scanner (skin contact), 5 MHz (SAL 20, Toshiba). Two examiners evaluated the image quality with regard to the visualisation of the histologically confirmed malignant lesions (n = 78). For testing the spatial resolution, we developed a tissue--mimicking phantom including cyst-like structures of different sizes. The clinical and technical advantages and disadvantages respectively of these three methods are discussed.

Breast Neoplasms↗
PubMed1982

[Diagnosis of intra-uterine growth retardation by intensive ultra-sound biometry].

In a prospective study on 125 maternity patients with suspected intra-uterine growth retardation, simple ultrasound biometry (measuring of the distance) and intensive ultra-sound biometry (measurement of the circumference and the surface) were compared. Of 85 newborn born within two weeks following the biometry 34 newborn had intra-uterine growth retardation with a weight percentile smaller than 5, and 32 newborn were growth retarded with a percentile of 5-10. In 19 cases no growth retardation was found. (12 newborn in this group had a weight percentile 10-25). The measurement of the biparietal diameter was capable of diagnosing at the most 50% of the growth retardations (percentile under 5). The accuracy of the diagnosis of intra-uterine growth retardation increased to 85% with the thoraco-abdominal transverse diameter. The so-called borderline cases (percentile 5-10) were diagnosed with the bi-parietal diameter in 38 percent of the cases and by the transverse thoracic diameter in 41% of the cases. Measurement of the circumference of the head resulted in no better measurements than the bi-parietal diameter. The addition of the measurement of the thoracic circumference increased the diagnosis of severe fetal growth retardation (percentile under 5) to 90% and in borderline cases to 88%. The head thorax index and the ratio of head circumference and thoracic circumference increase in our investigation the accuracy of the diagnosis of intra-uterine fetal growth retardation substantially.

Female↗
PubMed1982

[Diagnosis of intrauterine growth retardation--comparison of clinical findings, total oestrogen determination from 24-hour urine and ultrasound biometry (distance measurement, biparietal head diameter and thoraco-abdominal transverse diameter) considering the antepartal and subpartal CTG's].

This article presents the results of clinical examination, total oestrogen determination from 24-h urine and ultrasound biometry -- measurement of the biparietal head diameter and the thoraco-abdominal transverse diameter (under routine conditions) -- for diagnosing intrauterine growth retardation (IUGR). In addition, the antepartal and subpartal CTG's are evaluated in cases of foetal retardation of growth "Single determinations" are confronted with so-called "serial examinations (= observation of the course)". Repeated clinical examinations and multiple determinations of the total oestrogen elimination with the 24-h urine did not result in any clear improvement of the detection rates of deficient development of the foetus (discovery rate with clinical examination = 54%, total oestrogen determination = 60%); there was, in fact, a relatively high rate of false-positive diagnosis (false-positive diagnoses on clinical examination = 31%). On the other hand, simple ultrasound biometry (distance measurements) led to the discovery of about 78% of all foetal growth retardations (perc. less than 10), the false-positive diagnoses rate being only 9%. Pathological antepartal CTG's (less than 8 points according to the Meyer-Menck score) were seen in about 27% of the cases with growth retardation -- with, however, an approximately equal rate of pathological CTG's in newborn of "normal weight". The discovery rate of deficient development of the foetus has been increased by combining ultrasound biometry with the total oestrogen determination from the 24-h urine, to 88% (perc. less than 10). The same applies to the combination of ultrasound biometry with the clinical examination (rate of detection: 87%). Up to 77% of all cases with IUGR have been discovered both by combining the clinical examination with the total oestrogen determination or antepartal CTG, as well as by combining total oestrogen determination with antepartal CTG.

Abdomen↗
PubMed1982

[The maternal perception of fetal movements during the last trimester of pregnancy].

In a prospective study the foetal movements were simultaneously registered with two real time ultra-sound instruments and compared with the maternal perception of the movements. 35 patients were studied with a mean investigation time of 20 minutes per patient. The mothers pushed a button when they perceived a movements. Synchronous to this registration and storage on a tape were done of the movements of the upper and lower extremities the body movements and the foetal respiratory movements, the foetal heart rate and the uterine contractions. The mothers noticed a total of 38% of all foetal movements. Most frequently the mother noticed in 78% of the cases total foetal movements of the body and extremities. Isolated movements of the foetal body without movements of the extremities were only perceived by the mothers in 31% of the cases and isolated movements of the extremities were only perceived in 15%. In 69% of the cases the mothers correctly indicated that foetal movement took place. In 31% of all maternal signals there was no sonographic evidence of foetal movements of the body or the extremities. In 24% of these cases foetal respiratory movements were evident and in 23% of the cases Braxton-Hicks contractions were found. In 54% of these cases the signal button was used by the mothers without detectable reason. This high failure rate of maternal perception of foetal movements needs to be considered in the evaluation of foetal movements by the mother.

Adolescent↗