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Biomedical subjects

F Fischer

Publications and source records attributed to F Fischer.

At least 91 records · Page 5Linked to original sources
PubMed1994

A complex experimental assessment for objective description of hierarchical psychophysiological behavior as human regulatory phenotype.

For the objective and valid identification of different human regulatory phenotypes it should be useful to analyze the behavior of different regulatory subsystems (Anochin 1976) in one multivariate design. Therefore in a DARA supported project a fully computerized and reliable laboratory assessment was developed and tested. We used a set of electrophysiological parameters that should indicate the activity of different functional regulation systems on different "behavioral levels". Skin conductance, skin temperature and voice pitch were used as indicators of sympathico-parasympathical activity. Breathing, heart rate variability and bloodpressure should indicate cardiovascular activity and electromyogram and mimic variablity were thought as indicators of locomotional external behavioral activity. To identify physiological reactions which are influenced by emotional stress we used voice stress measures. Even in the field of aviation and space medicine there exist data about the correlation of voice pitch with emotional excitation (Hecker et. al. 1968, Williams et.al. 1969, Friedrich, Vaic 1978, Vaic et.al. 1981,1982, Griffin, Williams 1987). In our former study (MOSAIC-study, Johannes 1990) the voice pitch and its variation range correlated with perceived emotional excitation but were independent of real bloodpressure variations. Two different types of pitch reaction to this experimental design were correlated to psychological personality scales and assigned subjects to "sensitizers" and "suppressors".

Adult↗
PubMed1992

[Self-instruction expert systems in medicine. Presentation of knowledge, acquisition of knowledge, prediction of suicide as an example].

AIMS: 1. Description of how self-learning expert systems work, and 2. comparison of various algorithms for the establishment of a data base for suicide prediction. POINTS DISCUSSED: from exemplary patient data, self-learning expert systems obtain their expert knowledge which they subsequently employ to establish the diagnosis in new patients. Various possibilities of storing knowledge may be employed, for example the decision tree, classes of rules or neuronal networks. The various forms of representing knowledge are also presented. Taking the prediction of suicidal risk as an example, the effectiveness of the algorithm is tested with the aid of a patient questionnaire. CONCLUSIONS: Different fields of application require different systems. The diagnosis of such expert systems can at least prompt the care-providing physician to reconsider his own diagnosis.

Artificial Intelligence↗
PubMed1992

A DNA library from an individual Beta patellaris chromosome conferring nematode resistance obtained by microdissection of meiotic metaphase chromosomes.

We have used a standard protocol established for human chromosomes to create a chromosome-specific plasmid library from a Beta patellaris chromosome conferring nematode resistance. A monosomic addition line was chosen carrying 18 sugar-beet (Beta vulgaris L.) and one wild-beet (B. patellaris) chromosome. The wild-beet chromosome can readily be identified as a univalent during metaphase I of meiosis. Highly synchronized meiotic material was used to excise the univalents from four pollen mother cells. The chromatin was lysed in a 1 nl collection drop, the DNA purified and restricted with Rsa I, ligated into a vector containing universal sequencing primers, and amplified by the polymerase chain reaction. The amplified DNA was inserted into a standard plasmid vector and cloned. Approximately 23,000 recombinant plasmids were obtained of which 15,800 could be utilized. Their insert sizes ranged from 80 to 700 bp with an average of 130 bp. 61 clones were tested in more detail by genomic Southern hybridization with sugar-beet and wild-beet DNA. Of these 32 plasmids (52%) contained single-copy inserts, 11 (18%) were specific for wild-beet DNA indicating that the DNA cloned originates in the univalent chromosome. The application of this technique for establishing high-density RFLP maps for discrete regions of plant genomes is discussed.

Animals↗
PubMed1992

DNA markers closely linked to nematode resistance genes in sugar beet (Beta vulgaris L.) mapped using chromosome additions and translocations originating from wild beets of the Procumbentes section.

Genes conferring resistance to the beet cyst nematode (Heterodera schachtii Schm.) have been transferred to sugar beet (Beta vulgaris L.) from three wild species of the Procumbentes section using monosomic addition and translocation lines, because no meiotic recombination occurs between chromosomes of cultured and wild species. In the course of a project to isolate the nematode resistance genes by strategies of reverse genetics, probes were cloned from DNA of a fragmented B. procumbens chromosome carrying a resistance gene, which had been isolated by pulsed-field gel electrophoresis. One probe (pRK643) hybridized with a short dispersed repetitive DNA element, which was found only in wild beets, and thus may be used as a molecular marker for nematode resistance to progeneis of monosomic addition lines segregating resistant and susceptible individuals. Additional probes for the resistance gene region were obtained with a polymerase chain reaction (PCR)-based strategy using repetitive primers to amplify DNA located between repetitive elements. One of these probes established the existence of at least six different chromosomes from wild beet species, each conferring resistance independently of the others. A strict correlation between the length of the wild beet chromatin introduced in fragment addition and translocation lines and the repeat copy number has been used physically to map the region conferring resistance to a chromosome segment of 0.5-3 Mb.

Animals↗
PubMed1992

Right-sided cardiac thromboembolism and its successful treatment with streptokinase: case report.

A sixty-eight-year-old woman with a clinical diagnosis of pulmonary embolism and large right-heart embolus on echocardiography is presented. Because of the critical clinical condition of the patient and the inability to perform surgical intervention, thrombolytic treatment (streptokinase) was administered. The patient's condition improved, the right-heart embolus disappeared, and on the perfusion lung scan there was only one small perfusion defect in the right lung. The authors consider thrombolysis to be appropriate treatment for right-heart thromboembolism whenever surgical embolectomy is not possible.

Female↗
PubMed1990

[A clarification system for completing suicidal thoughts].

To improve the prediction of suicidal risk one has to understand the suicidal thoughts in individuals. We formalized these ideas and integrated them into an understanding system. In such a system the ideas concerning suicide cooperate in such a way so that the suicidal attempt appears to be the optimal solution for this patient. We discuss the question whether such an idiographic understanding system may help to understand other patients too.

Expert Systems↗
PubMed1990

[N-acetylneuraminic acid (sialic acid) as a tumor marker in head and neck cancers].

N-acetyl-neuraminic-acid (sialic acid) is a natural component of the cell surface. Cancer cells show a higher concentration of sialic acid in the cell membrane, and the serum also shows an elevated level of sialic acid. The concentration of sialic acid was measured in the serum of 76 new tumour patients and 113 previously treated patients who were clinically free of recurrence. The primary tumour was classified as T1-T4 according to the UICC classification. A further group consisted of patients with recurrent tumours. The values were compared with the sialic acid concentration in the sera of 63 healthy probands. Patients with manifest tumours showed an increased level of sialic acid that correlated with the extent of the tumour. The sialic acid level in 71% of patients with a recurrence lay above the upper limit of normal (82 mg/dl) recorded in the sera of healthy probands. The measurement of the serum sialic acid is a useful parameter for early detection of recurrence.

Biomarkers, Tumor↗
PubMed1989

Staurosporine stimulates expression of the urokinase-type (u-PA) plasminogen activator in LLC-PK1 cells.

In LLC-PK1 porcine epithelial cells, the urokinase-type plasminogen activator (u-PA) mRNA and protein can be induced either by stimulation of the protein kinase C (PKC) pathway using a tumor promoter (PMA) or by stimulation of the protein kinase A (PKA) pathway with calcitonin (SCT). By contrast, addition of 10(-7) M staurosporine, an inhibitor of PKC, to LLC-PK1 cells also stimulated urokinase production. In contrast to the in vitro situation (where staurosporine inhibited PKC activity), in the cell-culture system the microbial agent caused an early translocation of PKC and inhibited PKA. Addition of staurosporine together with PMA or with SCT further increased urokinase mRNA and protein synthesis. Maximal stimulation was obtained when all 3 agents were added together. We thus assume that in LLC-PK1 cells the PKA and PKC signal-transferring pathways can function independently.

Alkaloids↗
PubMed1989

Experimental autonomic neuropathy in the choroid of streptozotocin-diabetic rats. Electron microscopic observations.

The authors used transmission electron microscopy to examine the autonomic nerve plexus of the choroid, in Wistar albino rats with long-term streptozotocin diabetes. Axonal alterations included massive glycogen deposits, honeycomb arrangement of synaptic vesicles, and an accumulation of dense, lamellated, tubulovesicular and multivesicular bodies within the transmitter segments. The alterations affected not only the neuroeffector areas of arterial and venous vessels, but also the close contacts between transmitter segments and melanocytes. Morphometric analysis lead the authors to conclude that the axonal alterations do not simply represent accentuation of age-related phenomena. Instead, they should be considered as manifestations of diabetic autonomic neuropathy.

Animals↗
PubMed1989

[The lingual thyroid, an unexpected and rare intubation difficulty].

A patient scheduled for a gynecological operation could be intubated only after various repeated attempts. The cause of the airway obstruction was an ectopic thyroid at the right base of the tongue, which made visualization of the glottis impossible. Management and prevention of the unexpected difficult intubation are discussed.

Adult↗
PubMed1985

An improved preservation technique for cells of hemopoietic origin.

A new technique for the cryopreservation of cell lines of hemopoietic origin is described. It uses a combination of 10% polyvinylpyrrolidone or hydroxyethylstarch with 15% glycerol, a slow stepwise addition of the cryoprotectants before freezing, cooling at 4 degrees C/min, rapid rewarming, and a slow step-wise dilution after thawing. This technique has given improved recovery rates with a number of basophil/mast cell lines, as well as a wide range of hemopoietic cells including hybridomas.

Animals↗
PubMed1985

Growth-factor-independent proliferation in vitro and tumorigenicity in vivo are associated in basophil/mast-cell lines and their somatic hybrids.

According to a current model, leukemic cells arise from normal hemopoietic progenitors as a result of two phenotypic changes: (1) a shift from a high to a low probability of completing differentiation, and (2) the loss of requirement for physiological growth regulators, such as multilineage hemopoietic growth factor (MHGF). In agreement with this model, we have recently reported that the spontaneous, in vitro, malignant transformation of a factor-dependent basophil/mast-cell line was coincidental with the appearance of MHGF-independent proliferation in vitro. We have now fused the MHGF-independent cells with their nontransformed counterparts. In the present study, 29 out of 32 hybrid clones analyzed exhibited an association between, on the one hand, the absence of MHGF requirement in vitro and high tumorigenicity in vivo and, on the other hand, MHGF-dependent proliferation in vitro and a reduced capacity to make tumors in vivo. These data support the idea that the tumorigenic behavior of the transformed cells in vivo and their lack of requirement for MHGF in vitro are directly related.

Animals↗