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Biomedical subjects

G Fischer

Publications and source records attributed to G Fischer.

765 records · Page 43Linked to original sources
PubMedDate not supplied

[Analysis of myocardial evoked potentials in relation to ergometric load and heart rate for use in frequency-adaptive cardiac pacemakers].

The aim of this study was to evaluate the ventricular evoked response (VER) measured with unipolar fractally coated pacing leads for use with rate-responsive pacemakers. To this end, the morphology of the VER, its variation with pacing rate and various levels of physical loading, and the long-term stability of the signal were studied using the telemetric features of implantable pacemakers. Fractally coated electrodes were used in order to minimize the stimulation artefact, thus enabling a reliable unipolar measurement of the VER. The VER shows uniform basic morphology, and remains virtually unchanged after 3 months; moreover, frequency and load-dependent changes of VER morphology were identical for all patients. A special programming device has been developed to evaluate a rate adaptive algorithm for optimizing the pacing rate to the current loading situation, and was successfully tested in two patients. The algorithm was shown to be capable of calculating a heart rate adequate for haemodynamic demand.

Aged↗
PubMedDate not supplied

[Ambulatory geriatric screening--an overview. I: Concept and methodologic development].

Scientific literature reveals different levels of efficiency in geriatric screening in the primary care setting. Part I of our review deals with the development of geriatric screening up to the implementation of regular health checks in Great Britain. Studies in primary care show that through screening 1-2 previously unknown conditions per patient can be detected, with a particularly high prevalence of unknown problems in the following areas: vision and hearing, continence, mobility, cognitive function, mood, isolation, and lack of help. Further research is still required to transfer the results of screening studies into primary care, particularly in validating instruments of geriatric assessments and selecting risk groups.

Aged↗
PubMedDate not supplied

[Ambulatory geriatric screening--an overview. II: Evaluation of the effectiveness and current recommendations for screening implementation].

Geriatric screening detects many problems previously unknown to the primary health care physician. In spite of this, a valid judgement can only be made if the effectiveness of the induced intervention is proven. Prospective studies evaluating these screening-induced interventions show diverse results. Nevertheless, international task forces conclude from the evidence of existing studies that there are areas which are effective, efficacious, and enhance the quality of life. It remains a continuing task for research to develop geriatric assessment instruments as well as to set up objective guidelines of intervention in these areas.

Aged↗
PubMedDate not supplied

[Repair of recurrent osteo-meningeal lesions at the base of the skull].

Treatment of cerebro-spinal fluid rhinorrhea from traumatic or tumoral origin, by simple dural patching, is not always sufficient because of the possible necrosis of the patch, mainly in case of severe osteo-meningeal defects. After having pointed out the frequency of such recurrences (5 to 30%, according to the data of literature), the authors report 6 personal cases successfully reoperated in order to repair the osteo-dural lesions with autogenous aponeurosis and bone grafts. 4 were after traumatism and 2 after removal of a tumor, in fronto-ethmoido-sphenoidal base of the skull. The authors suggest to combine bone reconstruction by autograft to the dural repair, even in case of primary fistula, when there is a severe traumatic or tumoral bone defect, or when we are dealing with a spontaneous rhinorrhea which is known to be generally due to local C.S.F. hyperpressure.

Adolescent↗
PubMedDate not supplied

Influence of helix formation on cis/trans isomerism of Xaa-Pro bonds flanking the helical segment.

The trifluoroethanol (TFE)-induced formation of alpha-helical structures in the peptide hormone calcitonin (salmon) was studied using limited proteolysis combined with capillary zone electrophoresis. A low TFE content in TFE/buffer mixtures was insufficient to introduce secondary structure, but two Lys-Leu bonds were found to have become inaccessible to proteolysis with clostripain. The influence of increasing helical degree of the Thr6-Lys18 (or Thr6-Tyr22 in the trans conformation) segment on the cis/trans isomerization of the adjacent Tyr22-Pro23 peptide bond was examined by means of isomer specific proteolysis. Results indicate that the helix dipole does not influence the cis/trans equilibrium distribution of the flanking Tyr22-Pro23 bond but considerably increases its isomerization rate Ko-->t.

Amino Acid Sequence↗
PubMedDate not supplied

Quantification of tumor type M2 pyruvate kinase (Tu M2-PK) in human carcinomas.

Proliferating and tumor cells express a certain isoenzyme of pyruvate kinase, called PK type M2. This isoenzyme can be isolated in an active tetrameric and an inactive dimeric form. We have termed this form tumor type M2-PK. This tumor type pyruvate kinase can be quantified by a specific ELISA in blood sera and tumor homogenates. In this study we have compared 26 normal colon mucosa and colon cancer specimens from the same patients. The total specific pyruvate kinase activity and the amount of the tumour type M2-PK measured by ELISA was increased in the tumor samples compared to the normal colon mucosa of the same patient. In normal colon mucosa the specific PK-activity ranged between 0.21 and 1.25 U/mg protein whereas in colon carcinoma we found activities between 0.99 and 7.08 U/mg. The amount of tumor M2-PK measured by ELISA ranged between 0.82 and 27.10 U/mg protein in normal colon mucosa and between 1.96 and 242.40 U/mg protein in colon carcinoma. The tumor M2-PK content in the serum of 666 healthy blood donors was measured by ELISA and compared to sera from 15 colon carcinoma patients and showed a highly significant difference (Mann-Whitney rank sum test, p < 0.001). The values for the 50%-percentiles (median) of blood donors were 10.8 U/ml and 55.0 U/ml for colon carcinoma.

Adenocarcinoma↗