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Biomedical subjects

G Mayer

Publications and source records attributed to G Mayer.

At least 415 records · Page 23Linked to original sources
PubMedDate not supplied

[Rate of maturation of osteons].

This paper examines the dynamics of Havers'ian remodelling and the concept of maturation rate of poly-chrome fluorescence-labeling osteons by means measurements of bone formation. It was used cortical bone of rabbit and merino sheep on various experimental conditions (Normal bone growth in the diaphysis of large bone and cortical bone of iliac crest, secondary fracture healing in tibia osteosyntheses with external fixation and oligotrophic pseudoarthrosis in rabbit. Gap healing of fractures in tibia osteosyntheses with external fixation and compression in the sheep). The diameters of labels were measured and the mathematical function of maturation rate of osteons was made out. The results were compared on the different experiment conditions. Statistical analyses have shown that the results of mathematical function and the values of their constants are not significantly different. These results seem to suggest that the rate of formation of the osteon is optimal on the various conditions and it is not use stimulating the osteoblastic activity with stimulation-therapy. The described model shows important informations of bone remodeling and adds new facts to the understanding of formal genesis of bone growth and fracture healing.

Animals↗
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Immunomodulating and antimetastatic activity of thymic peptides in BALB/c mice.

The immunomodulating and antimetastatic activity of a clinically approved low molecular weight, standardized thymic peptide (TP) preparation was evaluated in BALB/c-mice. Daily subcutaneous application of TP (7 consecutive days, 1 and 10 micrograms per mouse) upregulated counts and activity of peripheral blood cells, as measured on day 14. To check the influence of TP on experimental liver metastases (liver colonization), RAW H10 lymphosarcoma cells were intravenously inoculated into BALB/c-mice. TP (1,10,100 micrograms/mouse) was subcutaneously administered daily for 7 consecutive days starting 24 hrs after tumor cell challenge. Liver colonization was investigated on day 14 after tumor cell inoculation and demonstrated a statistically significant (p < 0.05) reduction of experimental liver metastases for TP treated mice.

Adjuvants, Immunologic↗
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The recombinant human histones H1 zero and H1.2 cause different toxicity profiles on the human leukemia cell line K562.

The human histones H1 zero and H1.2 were expressed in E. coli and purified to homogenity. Their cytotoxicity on the human leukemia cell line K562 and on PBMC from healthy volunteers was compared with the cytotoxic effect of a bovine histone H1 preparation. In this preparation, histone H1.2 was identified as the main compound. All three histone preparations induced a significant dose-dependent toxicity on the leukemia cell line. Compared with the recombinant histone H1 zero, the bovine preparation and recombinant H1.2 showed stronger cytotoxicities. Cytotoxic effects on K562 cells were observed immediately after addition of the histones, whereas the histone preparations failed to induce significant cytotoxicity on PBMC during the first hour of incubation. However, after 24 hours all three histone preparations induced toxic effects on PBMC which were comparable to those observed on the leukemia cell line.

Animals↗
PubMedDate not supplied

Low molecular thymic peptides stimulate human blood dendritic cells.

Dendritic cells are considered to be the most potent antigen-presenting cells and are thus promising new tools for the immunotherapy of cancer. They respond to various stimuli by differentiation (expression of CD83) and up-regulation of costimulatory surface molecules. Thymic peptides have immunostimulatory and immunomodulating properties. Their therapeutic potential in immunotherapy of cancer has been discussed. To test whether thymic peptides act on dendritic cells, we examined the effects of a standardized thymic peptide preparation on cultured human monocyte-derived dendritic cells. Addition of thymic peptides resulted in enhanced expression of the specific differentiation marker CD83 in a dose dependent manner. Moreover, thymic peptides induced the up-regulation of costimulatory molecules including CD86, CD80, HLA-DR and HLA-ABC. After priming with thymic peptides dendritic cells showed an enhanced expression of IL-8 and TNF-alpha mRNA and protein release. Dendritic cells stimulated with thymic peptides were able to induce proliferation of autologous T cells as measured by 3H-thymidine incorporation in mixed Lymphocyte reaction. In combination with a low dosage of keyhole limpet hemocyanin, thymic peptides showed additive effects in the up-regulation of CD83 and costimulatory surface markers. Our findings indicate that thymic peptides per se act on professional antigen-presenting cells in a stimulatory manner and were presented by these cells. Furthermore, thymic peptides enhance the response of dendritic cells to low dosages of a standard nominal antigen. Therefore, thymic peptides could improve the immunological activity especially against low amounts of endogenous antigens.

Amino Acid Sequence↗
PubMedDate not supplied

Thymic humoral factor-gamma 2 augments immune cell response and exerts antitumor activity in murine model systems.

The immunomodulatory and antimetastatic/antitumor activity of thymic humoral factor-gamma 2 (THF-gamma 2) was evaluated in BALB/c-mice. Daily subcutaneous applications (7 consecutive days, 20, 200 ng of THF-gamma 2 per injection/mouse) upregulated counts of thymocytes and peripheral blood cells in tumor bearing mice. To check the influence of THF-gamma 2 treatment on the growth of experimental metastases, RAW 117 H10 lymphosarcoma cells or L-1 sarcoma cells were intravenously inoculated into BALB/c-mice to establish liver or lung metastases, respectively. Local tumor growth was induced by subcutaneous injection of L-1 sarcoma cells. THF-gamma 2 was subcutaneously administered daily for 7 consecutive days starting 24 hrs after tumor cell challenge. Organ colonization as well as local tumor growth were investigated on day 14 after tumor cell inoculation and demonstrated a statistically significant (p < 0.05) reduction of experimental liver and lung metastases and local tumor growth for THF-gamma 2 treated mice.

Adjuvants, Immunologic↗
PubMedDate not supplied

[Psychometric aspects of age-related changes in attention--demonstration in a rat].

Knowledge of human brain functions can often be obtained from psychobiological experiments carried out with animals. Lack of specification and sensitivity of the applied psychometric procedures may occasionally considerably limit the quality and degree of interpretation of the obtained results. The test here described is the first to offer the possibility of isolated quantitative identification of sensory and cognitive attention. It demonstrates the age-related effects on behavior-controlling attention functions in rats. What is assumed to be a general impairment of cognitive function in old age, might possibly turn out to be secondary effects of primarily altered attention thresholds.

Aging↗