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Biomedical subjects

K P Koskinen

Publications and source records attributed to K P Koskinen.

18 recordsLinked to original sources
PubMed1985

An electron microscopic demonstration of induction of chondrogenesis in neonatal rat muscle outgrowth cells in monolayer cultures.

Second passage fibroblast-like cells grown from explants of neonatal rat muscle continue to demonstrate fibroblast-like properties for many days when cultured on plastic surfaces. Such cells can be induced to change to a chondrocyte-like mode of expression by the addition of effector materials prepared from bovine cortical bone decalcified with 0.6 N HCl. Other studies show that similar demineralized bone particles and extracts from them have, in vivo, osteoinductive properties. Optimum conditions for this differentiation in monolayer culture were found in the use of 2% fetal calf serum with Dulbecco's modified Eagles medium. At 10% fetal calf serum the chondrogenic changes could not be detected. Light microscopy showed a sequence of morphological changes, after 36 h in culture, which resembled those seen at the beginning of osteogenesis in vivo. Induced cultures showed abundant extracellular proteoglycan production. Isotope incorporation studies showed stimulation of glycosaminoglycan synthesis in response to effector materials in soluble form. Type II collagen could be detected after three days. Electron microscopic analysis of induced and control cultures showed unequivocal evidence for marked production of an extensive extracellular matrix in the region of effector particles. The cells themselves change shape and develop an abundant system of lysosome-like vesicles and a very active, highly engorged endoplasmic reticulum and Golgi apparatus. After nine days in culture, evidence for the formation of a ruthenium red stained structure on the surface of the cells in contact with inductive particles, was observed. The simple monolayer culture system described provides a direct means by which the presence of active chondrogenic fractions may be assessed, and in which the mechanism of action of the effectors can be studied.

Animals↗
PubMed1981

Cytotoxicity of some solutions used for root canal treatment assessed with human fibroblasts and lymphoblasts.

The cytotoxicity of seven solutions used in root canal therapy was tested in human fibroblast and lymphoblast cultures. The amount of cell damage was assessed by measuring the release of 51Cr from labeled cells into the medium. The solutions, when applied at therapeutic concentrations, displayed high toxicity in vitro and differences in cytotoxicity were seen between different solutions. Generally, lymphoblasts were found to be more sensitive than fibroblasts. The cytotoxic profiles of the two cell types resembled each other except when 5% sodium hypochlorite or 0.2% Hibitane was used. When the criterion of total cell lysis was 50% 51Cr release, the toxic concentrations of the solutions tested ranged between 1:25 and 1:900 (v/v) for fibroblasts. For lymphoblasts the corresponding concentration range was between 1:40 and 1:750. Despite technical simplicity and good reproducibility the 51Cr release method proved unreliable for testing the cytotoxicity of endodontic solutions. Because the methodological errors cannot be foreseen the 51Cr release method requires supporting evidence from other methods.

Cells, Cultured↗
PubMed1980

Appearance of chemically treated root canal walls in the scanning electron microscope.

The dissolving effects of seven endodontic solutions on unprepared root canal walls of young intact human premolars were evaluated with the scanning electron microscope. After incubation at 37 degrees C in distilled water or isotonic saline for 10 min the predentinal surfaces showed no changes as compared with untreated controls. The demineralizers Decal and Largal Ultra had little effect on the organic tissues but caused some decalcification where mineralized dentin was exposed. Nelex caused concentration-dependent coagulation of the residual pulp tissue, making typical ring structures on the surfaces. Sodium hypochlorite at 2.5% and 5.0% dissolved most of the predentin, exposing the globular appearance of the mineralizing front. Salvizol produced small globules on otherwise intact surfaces. Dissolution of both the organic and inorganic tissue of the root canal wall would require the combined use of two of the solutions studied.

Acetates↗
PubMed1980

Dissolution of bovine pulp tissue by endodontic solutions.

Pulpal tissue was incubated at 37 degrees C for 10 min with various solutions used for root canal therapy. The dissolved material was assayed for hydroxyproline (HYP) and total phosphate, and the insoluble residue for HYP and dry weight. Sodium hypochlorite (NaOCl) at 5% and diluted to 2.5% showed the strongest solvent capacity measured as loss of HYP and weight from the tissue. Dilution to 0.5% significantly decreased the effectiveness of NaOCl. The absence of HYP from the NaOCl extracts suggested decomposition of this amino acid. The other solutions tested were far inferior in their ability to dissolve pulpal tissue. The demineralizing solutions tested were poor solubilizers of soft tissue; however, they caused a considerable increase in the amount of phosphate released.

Acetates↗
PubMed1980

Appearance of chemically treated root canal walls in the scanning electron microscope.

The dissolving effects of seven endodontic solutions on unprepared root canal walls of young intact human premolars were evaluated with the scanning electron microscopy. After incubation at 37 degrees C in distilled water or isotonic saline for 10 min the predentinal surfaces showed no changes as compared with untreated controls. The demineralizers Decal and Largal Ultra had little effect on the organic tissues but caused some decalification where mineralized dentin was exposed. Nelex caused concentration-dependent coagulation of the residual pulp tissue, making typical ring structures on the surfaces. Sodium hypochlorite at 2.5% and 5.0% dissolved most of the predentin, exposing the globular appearance of the mineralizing front. Salvizol produced small globules on otherwise intact surfaces. Dissolution of both the organic and inorganic tissue of the root canal wall would require the combined use of two of the solutions studied.

Acetates↗