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Biomedical subjects

R Koppang

Publications and source records attributed to R Koppang.

At least 19 recordsLinked to original sources
PubMed2000

Production of cloned pigs from in vitro systems.

Here we describe a procedure for cloning pigs by the use of in vitro culture systems. Four healthy male piglets from two litters were born following nuclear transfer of cultured somatic cells and subsequent embryo transfer. The initiation of five additional pregnancies demonstrates the reproducibility of this procedure. Its important features include extended in vitro culture of fetal cells preceding nuclear transfer, as well as in vitro maturation and activation of oocytes and in vitro embryo culture. The cell culture and nuclear transfer techniques described here should allow the use of genetic modification procedures to produce tissues and organs from cloned pigs with reduced immunogenicity for use in xenotransplantation.

Animals↗
PubMed1995

A method for testing denture adhesives.

An in vitro test is described that simulates the in vivo fate of a denture adhesive, namely destruction, dilution, and dissolution of the adhesive, by repeated measurement of tensile bond strength for the adhesive in isotonic saline over time. The bond strengths were measured under two different settings of the testing machine. The main compositions of three denture adhesive pastes, Fittydent, Fixodent, and Super Poli-Grip and one powder adhesive, Super Wernet's, were determined by infrared spectroscopy. The tensile bond strengths of these adhesives and those of pure tragacanth gum were subjected to a three-way analysis of variance. The Fittydent and Super Poli-Grip adhesives exhibited the best results over time. The most appropriate of the described methods for testing denture adhesives seem useful; however, when seen in relation to the results of a published clinical study where the patients were asked to evaluate the retention and the duration of some of these adhesives, there are indications that the clinical validity of the method might be improved if paste adhesives are tested at temperatures above 35 degrees C.

Adhesives↗
PubMed1993

Assessment in rats of a new bioerodible bone-wax-like polymer.

Holes drilled in rats' skull, iliac crest, and tibia were filled with beeswax or with a new, wax-like, bioerodible polyorthoester (Alzamer). Empty drill-holes served as controls. In addition, beeswax and polyorthoester were deposited between the left and the right oblique abdominal muscles, respectively. In muscle, both the beeswax and polyorthoester elicited a transient foreign body reaction. The beeswax was not resorbed in bone or muscle, whereas the polyorthoester was. Bone healing was inhibited in the iliac crest and the tibiae filled with beeswax, whereas holes filled with polyorthoester healed readily.

Abdominal Muscles↗
PubMed1992

Identification of common foreign material in postendodontic granulomas and cysts.

The present investigation was undertaken to identify commonly occurring foreign material in postendodontic periapical granulomas and cysts. 29 biopsies from such lesions with observed foreign material were routinely processed, stained with H&E, von Kossa and Calcofluor White and investigated by light, polarization and fluorescence microscopy. Applying back-scattered SEM images, the foreign material was subjected to energy dispersive X-ray analysis. 4 groups of foreign material were observed: 1. Black/brownish fragments and yellow/brown granules containing Au, Ag, Cu, Hg, Sn and Zn compatible with amalgam. 2. Fine black/brown/yellow granules compatible with endodontic sealer components revealing Ag, Ba, Bi, Cu, S, Ti and Zn. 3. Basophilic fragments compatible with Ca salts from Ca(OH), extruded periapically and containing Ca and P. 4. Elongated/rounded/oval/kidney-shaped, colourless to slightly basophilic, birefringent structures revealing C and O and with a slit-like central canal and a bright, pale-blue fluorescence specific for cellulose.

Calcium Hydroxide↗
PubMed1991

A method for testing denture adhesives.

An in vitro test method is described simulating the in vivo fate of a denture adhesive, i.e., destruction of the adhesive, dilution, and dissolution, by measuring the bond strength for the adhesive placed between acrylic resin plates. Between each measurement, the adhesive was exposed to isotonic saline. The bond strength for two ointment denture adhesives, Super Corega and Fixodent, was measured and the results were compared with those obtained for one of them in a previous in vivo test. The test method described for denture adhesives seems useful to depict the fate of a denture adhesive in clinical use.

Adhesives↗
PubMed1989

Cellulose fibers from endodontic paper points as an etiological factor in postendodontic periapical granulomas and cysts.

Histological sections of eight periapical granulomas and cysts developing after conventional endodontic therapy and displaying faintly hematoxylinophilic, birefringent foreign bodies were investigated by light and polarization microscopy, scanning electron microscopy, energy-dispersive X-ray, and chemical analysis. In addition to a variably dense mononuclear infiltrate, the granulomas and cysts revealed varying amounts of giant cells associated with the birefringent foreign bodies. These structures were identified as cellulose fibers, most probably originating from endodontic paper points, which in our opinion can be held responsible for the initiation and perpetuation of chronic postendodontic periapical lesions.

Cysts↗
PubMed1987

Identification of cellulose fibers in oral biopsies.

Oral biopsies comprising five periapical cysts, three cases of exuberant granulation tissue in extraction sockets and one case of a mandibular radiopaque structure, all displaying material consistent with cellulose fibers on routine histologic examination, were subjected to histochemical, polarization, fluorescence and scanning electron microscopical, energy dispersive X-ray and chemical investigations. Routine screening of periapical lesions with polarization microscopy and identification of possible cellulose fibers with Calcofluor White is advocated. Further, attention is drawn to endodontic paper point material as an etiologic factor in postendodontic periapical inflammatory processes.

Adolescent↗
PubMed1979

[Fissure sealants].

Explore the source record for details and available documents.

Acid Etching, Dental↗
PubMed1975

Elution of cadmium from dentures.

Heat-cured, pink-pigmented (light veined) Stellon maxillary acrylic denture blanks were shaken in 150 ml synthetic saliva varied from 0.15 to 1.05 mug independently of elution time. With o.1N CH3COOH the amount of cadmium, varying from 1,20 to 2.55 mug, increased slowly with elution time. Another batch of Stellon gave higher values in 0.1N CH3COOH.

Acrylic Resins↗