High resolution micro arthrography of hard and soft tissues in a murine model.

OBJECTIVE: Recent developments on high resolution micro computed tomography (µCT) allow imaging of soft tissues in small animal joints. Nevertheless, µCT images cannot distinguish soft tissues from synovial fluid due to their similar mass density, limiting the 3D assessment of soft tissues volume and thickness. This study aimed to evaluate a lead chromate contrast agent for µCΤ arthrography of rat knee joints ex vivo. DESIGN: Intact tibiofemoral rat joints were injected with the contrast agent at different concentrations and imaged using a µCT at 2.7 µm isotropic voxel size. Cartilage thickness was measured using an automated procedure, validated against histological measurements, and analyzed as a function of µCT image resolution. Changes in hard and soft tissues were also analyzed in tibiofemoral joints 4 weeks after surgical destabilization of the medial meniscus (DMM). RESULTS: The contrast agent diffused well throughout the whole knee cavity without penetrating the tissues, therefore providing high contrast at the boundaries between soft tissues and synovial fluid space. Thickness analysis of cartilage demonstrated a high similarity between histology and µ-arthrography approaches (R(2) = 0.90). Four weeks after surgical DMM, the development of osteophytes (Oph) and cartilage ulcerations was recognizable with µCT, as well as a slight increase in trabecular bone porosity, and decrease in trabecular thickness. CONCLUSIONS: A lead chromate-based contrast agent allowed discriminating the synovial fluid from soft tissues of intact knee joints, and thus made possible both qualitative and quantitative assessment of hard and soft tissues in both intact and DMM tibiofemoral joints using high resolution µCT.

Bone reaction adjacent to microplasma-sprayed calcium phosphate-coated oral implants subjected to an occlusal load, an experimental study in the dog.

BACKGROUND: A new microplasma spraying equipment (MSE) to deposit calcium phosphate (CaP) ceramic coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the low heat power of the microplasma jet, overheating of the powder particles as well as excessive local overheating of the substrate are diminished. Furthermore, because of the small laminar plasma jet, it is possible to achieve high spray efficiency in the case of spraying for dental implants. Also, the low level of noise (25-50 dB) and hardly any dust makes it possible to operate MSE under conditions of normal workrooms. OBJECTIVE: The aim was to investigate, in a mandibular dog model, the effect of functional load on soft-tissue adaptation as well as crestal bone-level changes around titanium implants provided with newly developed microplasma-sprayed CaP coatings. MATERIAL AND METHODS: For histomorphometrical evaluation, 56 screw-type titanium implants were inserted into the mandibles of seven adult Beagle dogs. The implants were either acid etched without an additional coating, coated with a conventionally plasma-sprayed CaP ceramic (PS), coated with a microplasma-sprayed CaP ceramic (MPS) or with a microplasma-sprayed coating at only the apical part (aMPS). To assess the effect of occlusal loading, a split-mouth design was used. Six weeks after implantation, the implants in one half of the mandible of each dog were functionally loaded whereas the contra lateral implants served as control. One year after loading, the animals were sacrificed. Soft-tissue dimension as well as marginal bone level were histologically assessed. RESULTS: Histometric analysis of undecalcified histologic sections included the evaluation of the sulcus depth, the dimension of the junctional epithelium and the connective tissue as well as the first bone-to-implant contact. For MPS-surfaced implants, functional loading was associated with--compared with the non-loaded state--unchanged soft-tissue dimension. Furthermore, the soft-tissue dimension did not differ from the dimensions around non-coated, PS and aMPS implants. Moreover, the first bone-to-implant contact was not significantly altered by functional loading and comparable non-coated, PS and aMPS implants. CONCLUSION: Within the limits of the experiment, we conclude that, in comparison, functional loading does not affect the marginal soft-tissue response to MPS CaP-coated implants. However, in comparison, functional loading might affect marginal bone response to MPS CaP-coated implants.

Loaded microplasma-sprayed CaP-coated implants in vivo.

Microplasma spray equipment to deposit calcium phosphate ceramic (CaP) coatings has been developed. Fifty-six titanium implants were inserted into the mandibles of 7 adult beagle dogs. The implants were either acid-etched (NC), conventionally plasma-sprayed (PS), micro-plasma-sprayed (MPS), or micro-plasma-sprayed (aMPS) only at the apical part. After 6 weeks, implants in one half of the mandible were subjected to load. Fifty-two weeks thereafter, the animals were killed. Regardless of load, bone healing was comparable for all surfaces tested. It was concluded that loading of MPS CaP-coated implants evokes a favorable bone response, and that the bone response does not differ from that of PS CaP-coated implants. However, functional loading of PS as well as MPS CaP-coated implants might be associated with increased crestal bone maintenance as compared with non-coated implants.

Bone reaction adjacent to microplasma-sprayed CaP-coated oral implants subjected to occlusal load, an experimental study in the dog. Part I: short-term results.

BACKGROUND: A new microplasma spraying equipment (MSE) to deposit calcium phosphate ceramic (CaP) coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the low heat power of the microplasma jet, overheating of the powder particles as well as excessive local overheating of the substrate is diminished. Furthermore, because of the small laminar plasma jet, it is possible to achieve high spray efficiency in the case of spraying for dental implants. Also, the low level of noise (25-50 dB) and hardly any dust makes it possible to operate MSE under conditions of normal workrooms. OBJECTIVE: The aim was to investigate, in a mandibular dog model, bone biological properties and the occlusal loading effects of titanium implants provided with newly developed microplasma-sprayed CaP coatings. MATERIAL AND METHODS: For histomorphometrical evaluation, 48 screw-type titanium implants were inserted into the mandibles of six adult beagle dogs. The implants were either acid etched without additional coating, coated with a conventionally plasma-sprayed CaP ceramic, coated with a microplasma-sprayed CaP ceramic or with a microplasma-sprayed coating at the apical part only. To assess the effect of occlusal loading, a split-mouth design was used. Six weeks after implantation, the implants in one half of the mandible of each dog were functionally loaded, while the contra lateral implants served as control. Six weeks after loading, the animals were sacrificed and bone-to-implant contact as well as the amount of bone around the implants were assessed. RESULTS: Irrespective of surface and functional load, no statistically significant differences (P>0.05) were found either for bone-to-implant contact or for the amount of bone between the various implant surfaces. On the other hand, functional loading of the non-coated implants was associated with a tendency towards crestal bone loss. CONCLUSION: Within the limits of the experiment, we conclude that functional loading of MPS CaP coatings induces a favorable bone response, and furthermore, that the bone response, irrespective of the loading condition, does not differ from conventional plasma-sprayed CaP coatings.

Bone-supportive behavior of microplasma-sprayed CaP-coated implants: mechanical and histological outcome in the goat.

BACKGROUND: New microplasma spray (MPS) equipment to deposit calcium phosphate (CaP) ceramic coatings onto titanium substrates has been developed. With this apparatus, it is possible to spray fine particles, as well as to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the low heat power of the microplasma jet, overheating of the powder particles as well as excessive local overheating of the substrate is reduced. Furthermore, because of the small laminar plasma jet, it is possible to achieve high spray efficiency in the case of spraying of dental implants. Additionally, the low level of noise (25-50 dB) and hardly any dust makes it possible to operate the MSE under normal workroom conditions. OBJECTIVE: The aim of this study was to examine the biological properties of different MPS - CaP coatings on titanium implants when inserted into the femoral condyle of goats. MATERIAL AND METHODS: For histomorphometrical evaluation as well as mechanical testing, 48 screw-type titanium implants were inserted into the femoral condyles of 12 goats each. The implants were either coated with a conventionally plasma-sprayed CaP ceramic, MPS CaP ceramic, or acid-etched without an additional CaP coating. Six and 12 weeks after implantation, the animals were sacrificed and bone-to-implant contact, amount of bone, as well as mechanical bone fixation were evaluated. RESULTS: For bone-to-implant contact no statistically significant difference was found between the different CaP coatings. However, statistically significant differences were found between non-coated, acid-etched titanium implants and CaP-coated implants after 6 and 12 weeks of healing. The bone values were not statistically significantly different between the different CaP coatings at 6 and 12 weeks. Furthermore, CaP ceramic-coated implants showed statistically significantly higher torque values compared with the non-coated implants after 6 and at 12 weeks of healing. No significant differences existed between the various types of CaP coatings. CONCLUSION: On the basis of our observations, we conclude that conventionally plasma-sprayed CaP ceramic-coated implants, as well as MPS-coated implants have a comparable effect on adjacent bone response.

Application of an ion-selective field effect transistor with a photocured polymer membrane in nephrology for determination of potassium ions in dialysis solutions and in blood plasma.

Application of a potassium ion sensor based on an ion sensitive field effect transistor (ISFET) for ion control of a dialysis solution in an artificial kidney and in blood plasma of patients treated by hemodialysis is presented. Sensors and their long-term stability were characterised in constant contact with test solutions. Test results are compared to those obtained with conventional ion-selective electrodes and commercial blood ion analyser. Tested ISFET sensors showed high reliability in potassium ion measurements in the physiologically significant concentration range which, along with low cost of their production, makes them promising for cited application.

The solid-state catalytic synthesis of tritium labeled amino acids, peptides and proteins.

New catalytic reaction between a solid bioorganic compound and activated spillover tritium (ST), based on High-temperature Solid-state Catalytic Isotopic Exchange (HSCIE) was examined. The HSCIE mechanism and determination of the reactivity of hydrogen atoms in amino acids, peptides and proteins was investigated. Quantum mechanical calculations of the reactivity of hydrogen atoms in amino acids in the HSCIE reaction were done. The carbon atom with a greater proton affinity undergoes a greater exchange of hydrogen for tritium in HSCIE. The electrofilic nature of spillover hydrogen in the reaction of HSCIE was revealed. The isotope exchange between ST and the hydrogen of the solid organic compound proceeds with a high degree of configuration retention at the carbon atoms. The HSCIE reaction enables to synthesize tritium labeled proteins with a specific activity of 20-30 mCi/mg and kept biological activity.

Synaptonemal complex analysis of B-chromosome behavior in meiotic prophase I in the East-Asiatic mouse Apodemus peninsulae (Muridae, Rodentia).

The mitotic and meiotic chromosomes of four male East-Asiatic mice, Apodemus peninsulae, having three to seven chromosomes in addition to the standard karyotype (2n = 48), were investigated. B-chromosomes were represented by medium-sized metacentric and dotlike chromosomes. Mosaicism of bone marrow cells due to a numerical variation of accessory chromosomes was established for the males examined. Capacity of B-chromosomes to form axial elements and synaptonemal complexes in meiotic prophase I was revealed by electron microscopy. The occurrence of univalents of different morphology, bivalents, and multivalents, corresponding to B-chromosomes, was demonstrated. An increase in the number of B-chromosomes was found in spermatocytes at zygotene-pachytene relative to the number in bone marrow cells, which may be evidence of B-chromosome accumulation in the germ cell line of the East-Asiatic mouse.