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Biomedical subjects

G Fischer

Publications and source records attributed to G Fischer.

At least 523 records · Page 29Linked to original sources
PubMed1982

Cultivation of immature astrocytes of mouse cerebellum in a serum-free, hormonally defined medium. Appearance of the mature astrocyte phenotype after addition of serum.

A hormonally defined culture medium is described which supports survival and proliferation of astroglia from primary cultures of early postnatal mouse cerebellum. This medium consists of bovine serum albumin, insulin, transferrin, selenium, hyaluronic acid, protease inhibitor aprotinin, and epidermal growth factor. Trypsin-dissociated single cerebellar cell suspensions are plated in this medium on poly-l-coated glass coverslips and maintained for two weeks before subcultivation. After subcultivation into defined medium more than 99% of all cells are vimentin-positive and fibronectin- and almost completely glial fibrillary acid (GFA) protein-negative, indicating that these cells are less mature astrocytes. After replacement of defined medium by culture medium containing 10% horse serum, expression of GFA protein is detectable in addition to vimentin by indirect immunofluorescence.

Animals↗
PubMed1982

Cultivation of mouse cerebellar cells in serum free, hormonally defined media: survival of neurons.

A hormonally defined medium is described which facilitates the survival of small neurons in primary cultures of mouse cerebellum. The defined medium consists of bovine serum albumin, insulin, transferrin, selenium, thyroxine, and the protease inhibitor aprotinin. About 95% of all cells were identified as neurons using tetanus toxin as a marker in an immunocytochemical assay. They survive for more than 4 weeks, showing a tendency to grow in cell clusters with a dense network of processes. The remaining cells (approximately 5%) were identified as astrocytes by their expression of vimentin and GFA protein and the lack of expression of fibronectin.

Animals↗
PubMed1982

[Results of the School Health Service in La Chaux-de-Fonds between 1975 and 1979].

This is a balance sheet of the medical service in la Chaux-de-Fonds schools for the last five years (1975-1979). The activities of the School Medical Service (SMS) are clinical and paraclinical examinations, immunizations, and tuberculin tests, as well as health information. The number of students in three examined grades (1, 4, and 9) varies over the years, with a tendency of going down in the first grade since 1978. The following anomalies are checked and compared between grades and years; overweight, systolic murmurs, hernias, alterations of the tonsils and lymph glands, deviations of the vertebral column, genital anomalies in boys, age of puberty, troubles in visual and auditory acuity (the last being measured by audiometry), blood pressure troubles in students in the 9th grade. In that grade, paraclinical examinations such as ECG, pulmonary function, and blood groups are carried out. Students of that grade are questioned about their personal habits and previous illness. Immunizations and tuberculin tests done by the SMS are discussed. Health information its evolution are mentioned. In conclusion, one can say that the purpose of the SMS is promotion of school children's health during the compulsory school period.

Adolescent↗
PubMed1982

Failure to produce hypertension in rats by chronic exposure to cadmium.

Groups of ten male and ten female Sprague-Dawley rats were exposed for 92 and 84 wk, respectively, to increasing concentrations of cadmium (as the chloride) in their drinking-water. The exposure levels of Cd used were 0, 5, 12.6 and 31.5 ppm Cd, and 5 ppm Cd plus certain trace metals. Blood pressure was measured in unanaesthetized animals at regular intervals (46 times in females, 49 times in males) by an indirect method to which the animals were kept conditioned. At the end of the experiments blood pressure was also determined directly under sodium pentobarbital anaesthesia. Although the weight of the kidneys, Cd residues and the severity of histological alterations in the kidneys increased in a dose-related manner, the blood pressure and pulse rate were not significantly affected in any of the experimental groups. There was a dose-dependent decrease in water consumption; all other parameters remained unaffected.

Animals↗
PubMed1982

[Synthesis and enzymatic degradation of beta-casomorphin-5 (author's transl)].

The authors describe the synthesis of beta-casomorphine-5 (Tyr-Pro-Phe-Pro-Gly) by segment condensation and stepwise building-up. Intracerebroventricular application of the pentapeptide to the rat produces a long-lasting analgesia against thermal stimuli (which can be inhibited by naloxone) and counteracts the extinction of a passive avoidance reaction for no less than 4 days following post-shock application. beta-Casomorphin-5 is very rapidly degraded by dipeptidylpeptidase IV; the degradation starts from the N-terminus giving dipeptides. The degradation products are competitive inhibitors of this enzyme.

Analgesics↗
PubMed1982

[The modelling of growth processes].

Hitherto developed presentation of processes of growth will be tested in this paper. For this end a previous explained cybernetical structure is developed to a model of an analog-computer. In this way it is possible to simulate the growth function of the embryofetal curve of the length' increase of man and the curve of the mass' increase of rat. It turns out a very good correspondence between the measured and the simulated curves. There is given an algorithm to simulate every curve of growth of the examined type. Some remarks of the origin of the explained ideas will round this paper.

Animals↗
PubMed1982

[Studies on the influence of positive or negative small ions on the catechol amine content in the brain of the mouse following shorttime or prolonged exposure (author's transl)].

UNLABELLED: Mice were exposed to an atmosphere enriched with positive or negative small ions (density: 52000 each of positive or negative charge carriers/cm3 air); after the exposure times of 5, 30 min and 1, 3, 10 d, we determined the norepinephrine content of the brain. RESULTS: In the case of negative ionization of the air, no difference to untreated controls could be determined at any of the above exposure times. Positive ions, however, cause an elevated norepinephrine level after an exposure time of up to one day; after the exposure times of 3 to 10 d, a drop in the norepinephrine level could be observed in comparison to the control data. CONCLUSION: Negative ions have a neutral effect under the given bioclimatologic conditions. However, positive charge carriers cause stress after shorttime application in excess. After longer exposure, a state of exhaustion can be observed in the form of a lowered norepinephrine level.

Animals↗
PubMed1982

[Relations of physicalism and vitalism in biology: contribution to the year of Darwin 1982].

With help by an axiom established and some descriptions before this paper, it is possible to model successful processes of growth. In this description, it will be tried to explain in generally form this axiom and to classify it into our scientific system of world. With that comes a dialectical relation between Physicalism and Vitalism. Both continuous and statistical methods are known as possible and necessary forms of description of biological processes. By that the method of Newton can be transferred analogous into Biology with help from the field of information definited before this paper. The developed theoretical conceptions for analysis of growth are conformed also with the demands of system theory by v. Bertalanffy and they will derivated also from his system theory. This work will be finished with firstly ideas for application of this results and with relations of this theory and dialectic.

Biology↗
PubMed1982

[Electrolytic changes in the white mouse under the influence of weak magnetic fields].

On female white mice, the influence of weak magnetic fields on their electrolyte balance has been tested. Three types of magnetic fields, namely of a 50 HZ sinusoidal, a 50 Hz rectangular and a 10 Hz rectangular field have been applied, the latter mainly because of its similarity to some biologic rhythms and because some technical environments also tend to produce similar type of fields. The changes of electrolyte balance mentioned above were measured after one and seven days of exposure of the animals to those fields. The 50 Hz sinusoidal and 50 Hz rectangular type of the field shows - with the exception of Ca++ - no significant changes in the animals electrolyte balance, neither after one more after seven days. Ca++ levels however were in both cases significantly lower in test animals then in controls. A one days exposure to a 10 Hz rectangular field significantly lowers the Na+ and increases K+ levels. Almost reversed results are obtained after seven days, probably indicating overcompensation, after recovery. Since Na+ in liver homogenates after one days exposure is also low, we tend to hold the opinion that it must be excreted. Therefore it should be of some interest to check the balance of those hormones (e.g. angiotensin, vasopressin) which are closely connected with the above mentioned measured effects.

Animals↗
PubMed1982

[Definitions of biological characteristic quantities].

In this paper, the interaction is searched between a new biological field and a growing organism. There are just yielded many analogies to mechanic and electrodynamic. The special comparison between a biological axiom previously defined and the OHM's Law shows deep analogies to electrotechnic. Through that it's possible to understand better the new already used terms. With help by this comparison special electronical definitions can take over into biology. 2 examples shown the construction of statical biological characteristics from which altogether 10 characteristic values can derivated. Finally, a list shows all important relations of the framed hypothesis.

Biology↗