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Biomedical subjects

D Kranz

Publications and source records attributed to D Kranz.

At least 55 records · Page 3Linked to original sources
PubMed1979

[Autoradiography of neurogenesis and morphogenesis of the regio cingularis of the rat. IV. Quantitative studies on the times of cell origins in the cortical lamina].

In 171 embryonic and neonatal rats has been investigated the time of origin of cells in the cortical laminae by means of autoradiographs, after injection of tritiated thymidine. It was made a comparison between the Regio cingularis mesoneocorticalis, Regio cingularis mesoarchicorticalis, Area praecentralis agranularis and Area postcentralis by the laminar differential labeling index. The time of origin indicates for each layer a principal day and three secondary days. In all regions the time of origin of cells is identically for the hylogenetic old layers VI and V, differences exist in the supragranular layers: the cells are generated earlier in the phylogenetic old areas than in the young areas.

Age Factors↗
PubMed1978

[Adenyl cyclase activity and the stimulation of adenosine 3',5'-cyclic monophosphate in blood vessel walls during ageing and under stress (author's transl)].

It is well-known that the cAMP-adenylate cyclase system is important in mediating the effects of numerous hormones. We investigated the age-dependent behaviour of this system in aortas and femoral arteries of male Wistar rats (at the age of 10 days, 1, 4, 8, 12, and 22 months). It was found that: The basic adenylate cyclase activity had considerably been decreased beyond the first month of life, thereafter it was almost constant. The response of adenylate cyclase to guanylyl-imidodi-phosphate and NaF had essentially been elevated since the 4th month of age. The possibility of stimulating the cAMP generation due to epinephrine and histamine had substantially been increased since the 12th month of age. Besides the ability of adrenaline and histamine to stimulate the formation of cyclic AMP was investigated in broken cell preparation and intact cells of smooth muscle of the aorta and femoral artery of rats which had been subjected to daily intermittend immobilization of 1, 3, and 17 weeks. It was found that this type of stress led to an instability of the blood pressure which was associated with an increase in the sensitivity of adenylate cyclase in the broken cell preparations from the arteries to adrenaline and histamine and with a heightened cyclic AMP response to the two hormones in the intact arterial smooth muscle cells. The sensitivity of cardiac adenylate cyclase for adrenaline remained unchanged.

Adenylyl Cyclases↗
PubMed1978

[Hair cell noise damage after improved hypoxia tolerance (author's transl)].

UNLABELLED: Guinea pigs were gradually adapted to a simulated altitude of 10,000 m. The round window microphone potential (RMP) frequency response was measured 24 hours after pure tone exposition (2.7 kHz, 130 dB, 1 hr). The electrophysiologically demonstrable sound induced damage of the organ of Corti of the adapted guinea pigs was significantly smaller than those of the nonadapted (normal) group. Altitude adapted animals: m = 18, Hb: 18.5 +/- 1.8 g%, Hc: 57.3 +/- 4.4+ RMP mean loss: 1.7 +/- 0.8 dB. CONTROLS: n = 18, Hb: 12.7 +/- 1.8 g%, Hc: 40.5 +/- 1.6%. RMP mean loss: 5.8 +/- 2.4 dB. All differences significant p less than 0.001. The evident possibility to reduce noise induced hair cell damage by means of previous adaptation to high altitude might be explained by the greater hypoxia tolerance and perhaps additional better oxygen supply to the receptor cells.

Adaptation, Physiological↗
PubMed1978

[Initial results of investigations into the proliferation kinetics of enterocytes (author's transl)].

The changes of absorption appearing in man and caused by aging are probably due to disturbances of the proliferation and exfoliation kinetics of the enterocytes of the small intestine mucosa. The relevant experimental examinations available are insufficient because the results were obtained from a few animals only. Our own systematic autoradiographic examinations of rats are designed to contribute to a clarification of this problem which is important for practice.

Adolescent↗
PubMed1978

[Autoradiographic studies of the neurogenesis and morphogenesis of the cingulate region in the rat. I. Proliferation patterns in different pre- and postnatal stages].

The proliferation of the matrix-cells in the limbic cortex of 219 embryonic rats has been investigated by means of autoradiographs, after injection of tritiated thymidine at different stages of foetal life. The course of the labeling index indicates that matrix-cells represent a cell population in which cell multiplication is both rapid and continuous. Moreover the number of labeled cells decreases following the migration of labeled neuroblasts to another site. Because the beginning of migration retards after a division a proliferative compartment and a differentiating compartment were found in the subventricular and the ventricular zone. The migration appears in waves not before 24 hours after division of cells. We have found that, between the second and the third day and between the third and the fourth day after injection, migrating cells arise with 1/2 or 1/4 of the number of silver grains respectively. Cell division and migration both indicate in the brain a sequential nature; after each mitosis only one of the daughter-cells retains their proliferative capacity, the other becomes differentiated into neuroblast and leaves the proliferative compartment.

Animals↗
PubMed1977

[Wound healing in old age (experimental studies on rats) (author's transl)].

Autoradiographic studies on wound healing after experimental myocardial infarction in rats aged 6 weeks, 5 and 21 months gave the following results: 1. The interval between damage, DNA-replication and mitotic activity of the cells is age-dependent. 2. Age does not influence the capacity of the connective-tissue cells to synthesize tropocollagen. However, the number of synthesizing fibroblasts is reduced. 3. The collagen changes occuring during wound healing are not of primary, but of secondary nature; they take place if the mucopolysaccharide content is reduced. As a result, there is a decrease in the ground-substance synthesis in ageing granulation tissue. In cicatricial tissue the content of amorphous ground-substance remains greatly constant. 4. Consequently, the ageing of the collagen is governed by a biologically regulated process whose control mechanism is inherent in the cells.

Age Factors↗
PubMed1976

The influence of hyperthyroidism and hypothyroidism on the wound healing of experimental myocardial infarction in the rat.

In hyperthyroid and hypothyroid rats myocardial infarction was produced by coronary artery ligature. At different times following the ligature the animals were given 3H-thymidine or 3H-proline. The following parameters were determined: the number of DNA- and tropocollagen-synthesizing connective-tissue cells at the infarction border and at the infarction site; the mean silver-grain density above the nuclei or cells; the duration of one cell cycle; and the number of mitoses. The labelling and mitotic indices as well as the percentage of the standard deviation from the mean values were estimated. The following results were obtained: 1. In hyperthyroidism wound healing is accelerated. The number of DNA-synthesizing connective-tissue cells is increased. The cell-cycles are shorter. The release of tropocollagen by the fibroblasts takes place at a strikingly fast rate. 2. In hypothyroidism wound healing is delayed. The 3H-thymidine and mitotic indices are lowered. The release of tropocollagen is slowed down. The granulation tissue contains localized accumulations of mucopolysaccharides.

Animals↗
PubMed1976

[The adaption growth of the heart in the higher (experimental autoradiographic researches in rats) (author's transl)].

There was examined the influence of the age on the development of a compensatory hypertrophy of the heart in 4 to 16 month old masculin Wistar-rats autoradiographically. The valuation took place at various times after stenosing of the aorta and application of 3H-thymidine separatly in both ventricular walls by counting of the nuclei of the marked muscle- and connective tissue cells of the heart and their mitosis. For the connective tissue cells computation of the 3H-thymidin- and of the mitotic index. Determination of the body- and heart weight.

Aging↗
PubMed1976

[Age dependence of adenylate cyclase activity and cAMP generation in aortas and femoral arteries of rats (author's transl)].

UNLABELLED: It is well-known that the cAMP-adenylate cyclase system is important in mediating the effects of numerous hormones. We investigated the age-dependent behaviour of this system in aortas and femoral arteries of male Wistar rats (at the age of 10 days, 1, 4, 8, 12, and 22 months). RESULTS: 1. The basic adenylate cyclase activity had considerably been decreased beyond the first month of life, thereafter it was almost constant. 2. The response of adenylate cyclase to guanylyl-imidodiphosphate and NaF had essentially been elevated since the 4th month of age. 3. The possibility of stimulating the cAMP generation due to epinephrine and histamine had substantially been increased since the 12th month of age.

Adenylyl Cyclases↗
PubMed1976

[Hormonal stimulation of adenosine 3',5'-cyclic monophosphate formation in cell-free particles and intact cells of smooth muscle in the aorta and femoral artery of rats during immubilization stress].

The ability of adrenaline and histamine to stimulate the formation of cyclic AMP was investigated in broken cell preparation and intact cells of smooth muscle of the aorta and femoral artery of rats which had been subjected to daily intermittent immobilization for 1, 3, and 17 weeks. It was found that this type of stress led to an instability of the blood pressure which was associated with an increase in the sensitivity of adenylate cyclase in the broken cell preparations from the arteries to adrenaline and histamine and with a heightened cyclic AMP response to the two hormones in the intact arterial smooth muscle cells. The sensitivity of cardiac adenylate cyclase for adrenaline remained unchanged.

Adenylyl Cyclases↗
PubMed1975

The influence of age on the wound healing of experimental myocardial infarction in rats.

In 6-weeks-old, 5-months-old and 21-months-old rats myocardial infarction was induced by coronary artery ligature. After performing the ligature the animals were administered 3H-thymidine, 3H-proline or 35S-sulphate at different times. The following parameters were determined: number of DNA- and tropocollagen-synthesizing connective tissue cells at the infarction border and at the infarction site; mean silver grain density above the nuclei or cells; duration of a cycle; number of mitoses, and incorporation of radioactive sulphate at the infarction site. In addition, the labelling and mitotic indices as well as the percentage of the standard deviation from the mean values were estimated. The following results were obtained: 1. The rate of granulation tissue formation in the necrotic zone is determined by the mitotic activity of the cells. With advancing age the cell cycles are being prolonged which results in retardation of wound healing. 2. The disturbed DNA-replication in old age is not associated with a time shift in the occurrence of the mitotic and labelling peaks. 3. With advancing age the number of fibroblasts synthesizing collagen precursors decreases. There exists no age-dependence of the 3H-proline incorporation rate, of the intracellular transport, of the synthesis of collagen precursor and of the release of labelled tropocollagen. In all age-groups under study these processes last approximately 4 hours. 4. Collagen fibre formation is accompanied by an increased synthesis of acid mucopolysaccharides. In infarction callosities the content of acid mucopolysaccharides mostly is constant. 5. The proliferating endothelial cells have a pronounced metabolic activity and a markedly short generation time.

Age Factors↗
PubMed1975

[Contribution on the physiological heart growth. (Experimental autoradiographic studies in mice)].

After injections of 3H thymidine or 3H proline, the physiological hearth growth in mice of the CBA strain belonging to various age groups was studied by means of autoradiography. The most important results are the following: The duration of the postnatal growth period is determined by the degree of maturity of the heart at the time of birth. It varies from species to species. 2. In the perinatal developmental phase the percentage of the 3H thymidine-labelled connective-tissue nuclei is higher than that of the muscle nuclei. In this period the connective supporting tissue is considerably strengthened. 3. During the postnatal developmental phase the DNA synthesis in the muscle nuclei aids the preparation of mitoses. After the postnatal duplication of cells the mitotic genes are repressed. The further growth is effected by the increase in weight of the individual fibres. 4. The process of growth is substantially determined by the intracardiac or intramyocardiac pressure and thus by the extension of the muscle fibre. Prior to birth the percentage of the labelled nuclei of muscle cells and connective tissue cells in the right ventricle was higher than in the left ventricular wall. In the postnatal period we observed a shift in the percentage of the labelled cells towards the left ventricular wall. The basis and the median section of the ventricular wall. The basis and the median section of the ventricular wall contain a higher percentage of labelled cells than does the apex cordis. During the first two weeks of live most of the DNA synthesising nuclei of muscle and connective tissue cells are localized in the two inner muscle shells. Later in life no clear distinctions can be demonstrated between the individual ventricular layers.

Age Factors↗