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Biomedical subjects

F Lintner

Publications and source records attributed to F Lintner.

At least 55 records · Page 3Linked to original sources
PubMed1988

Endocrine regulation of the onset of parturition in rats.

The endocrine regulation of parturition exhibits several interspecies differences. Among the endocrine parameters considered to be the most important ones from the point of view of the regulation of parturition the concentration of oestrogens (oestradiol, oestriol and oestrone), progesterone, PGF2 alfa and its degradation product PGFM, was determined in both peripheral and uterine venous blood by RIA method in rats starting from the 15th day of pregnancy to the 3rd or 4th day following parturition. In the pregnant rat oestriol could only be detected on the day of parturition (21th day). Concentrations of oestriol and oestradiol were the highest on the day of parturition. An opposite tendency could be observed as far as progesterone concentration was concerned, i.e., the concentration decreased gradually from the 15th day of pregnancy onwards and the lowest value was reached on the day of parturition both in peripheral and uterine venous blood. PGF2 alfa and PGFM concentrations in the uterine vein increased gradually from the 15th day of pregnancy and the highest value could be detected peri partum. Our data, in accordance with those of others support the idea that the hormones investigated are involved in the process of parturition, i.e., characteristic changes of oestrogens, progesterone and prostaglandin levels ensue in the rat prior to parturition.

Animals↗
PubMed1987

Experimental osteoinduction in rats: collagen-apatite versus osteogenin-containing gelatine.

An experimental study in rats was done to investigate the bone-regenerating properties of collagen apatite (Collapat) and to compare it with osteoinduction dependent on osteogenin-containing gelatine (OCG). The test substances were implanted orthotopically (calvarial defect--7 mm in diameter) and heterotopically (paravertebral muscles, abdominal muscles). The results were evaluated histologically and enzymatically (alkaline phosphatase). Collapat caused neither osteoinduction in the heterotopic site nor healing of the bone defects. Foreign body reaction without new bone formation was encountered. OCG implantation leads to new bone formation in the muscles within 3 weeks, associated with a significant increase in alkaline phosphatase activity, and to extensive new bone formation in the calvarial defect within 4 weeks. The defects did not heal if left empty. The value of clinical application of Collapat appears to be doubtful. Osteoinduction with OCG requires further experimental investigation.

Animals↗
PubMed1987

[Morphology of the implant site in cemented and uncemented joint implants].

After the insertion of a joint endoprosthesis a healing process is initiated which is comparable to the fracture healing. Thus, a border zone is built up against the implant, being composed of lining cells, connective tissue, vessels, bone marrow and bone. The bone of the implant bed is subjected to a remodeling in order to adapt its structure to the change of the biomechanic stresses. The tissue of the implant bed may react to infection, degradation or wear of the materials and mechanical instability of the fixation as well. The characteristic feature of this reaction is cell and tissue proliferation which causes bone resorption and, possibly, loosening of the implant.

Biomechanical Phenomena↗
PubMed1986

Tissue reactions to titanium endoprostheses. Autopsy studies in four cases.

Four cementless prosthetic hip implants of Ti-6Al-4V-alloy with and without longitudinal grooves and Al2O2 ceramic ball heads, with implant periods of 3, 4, 5, and 10 months, were sectioned and examined histologically in undecalcified thin ground sections. Especially on the medial and lateral sides of the prostheses, there was direct bone-to-metal contact without interposed connective tissue, spreading to the dorsal and ventral areas of the prosthesis shaft, which was considered osseointegration. This is based mainly on the technique of implantation with primary stability in the cortical bone by press-fit and on the bioinertness of the titanium alloy. Ungrooved prosthesis areas seem to favor bone growth at the shaft. The secondary bone ring, occurring on the dorsal and ventral areas of the prosthesis, with evidence of further bone remodeling with the passage of time, indicates that osseointegration is a dynamic process that continues to improve prosthetic stability.

Aged↗
PubMed1986

Influence of trypsin on the regeneration of hyaline articular cartilage.

A purely chondral lesion was inflicted at the medial or lateral femoral condyle of the knee joints of 54 adult male rabbits in order to study hyaline cartilage regeneration. The experimental group was given a sequential intraarticular instillation of trypsin and autologous blood, the control groups were given trypsin or blood or nothing. Only the experimental group (trypsin and autologous blood) showed hyaline cartilage regeneration in 2/3 of the cases examined. Apparently neither the healthy cartilage nor the synovial membrane suffered damage from the trypsin injection. A possible mechanism of cartilage regrowth may be the inhibition of chalones by the fermentative effect of trypsin, which stimulates the aggregation of thrombocytes and fibrin from the injected blood on the chondral lesion, thus initiating the regeneration of hyaline cartilage.

Animals↗
PubMed1986

The effect of fetectomy on prostaglandin receptors of the rat myometrium.

It has been postulated that intrauterine volume plays a role in the timing of parturition. In previous studies we found that the onset of parturition in the rat was associated with significant increases in the concentration of receptors for PGF2 alpha in the myometrium. To determine the effect of intrauterine volume on the concentrations of this myometrial receptor, we compared receptor levels in pregnant and fetectomized horns from unilaterally fetectomized pregnant rats near the time of parturition (n = 3). Myometria from pregnant horns contained substantially greater concentration of protein than did those from the contralateral fetectomized horns. The amounts of receptors per horn for PGF2 alpha were about 3 times greater in myometria from pregnant horns than in those from fetectomized horns. However, near term the concentration of receptors per protein contents was the same in pregnant and fetectomized horns. These results suggest that uterine stretch causes hyperplasia and hypertrophy of the myometrium being indicative of more protein per pregnant than fetectomized horns. However, the rise in the concentration of receptors for PGF2 alpha about the time of labour appears to be induced by hormonal and not by physical factors.

Animals↗
PubMed1985

[A possibility of cutting frozen sections of bone tissue in routine pathology].

A low priced, efficient frozen section cutting device is described to produce 5 microns sections of frozen undecalcified bone specimen blocks in routine pathology. The device was developed by combining two commercially-available instruments, namely a frozen section microtome with methyl alcohol cooling and a hard tissue microtome. Bore holes were drilled in the hard tissue knife to permit cooling, using the methyl alcohol system of the other microtome.

Bone Neoplasms↗
PubMed1984

Contributions to the mechanism of action of beta-adrenergic stimulants.

Subcellar localization of ionic Ca was investigated by the Pb-acetate cytochemical method in rat myometrium on the 21st day of pregnancy, following oxytocin and Bricanyl treatment. Following Oxytocin treatment the amount of ionic Ca increased in the muscle cells of the uterus and decreased in the plasma membrane and mitochondria as compared with the control. Tocolytics given in the last four days of pregnancy caused a decrease in the cytoplasmic concentration of ionic Ca and increased the Ca++ content of Ca++ pools (plasma membrane, mitochondrium). The change in the intracellular distribution of Ca++ may be involved in the mechanism of action of tocolytics and in the development of the relaxation of smooth muscle.

Animals↗