[Basic study of chemo-embolization of the liver using hydroxyapatite granules]

The purpose of this study was to elucidate the availability of hydroxyapatite (HAp) granules as a chemoembolic agent in chemo embolization therapy. A mixture of adriamycin (ADM) and an embolic agent (HAp, Lipiodol) was injected via hepatic artery in normal Wistar rats. Then the concentration of ADM in the liver serum transaminase level were measured serially. The remaining ADM in the liver was higher in groups with HAp granules than the others. The serum transaminase, however, were lower in the HAp groups. There are some advantages of HAp using as a chemo embolic agent. (1) HAp is a physiological biomaterial and seem to be safe for human. (2) HAp granules injected into the liver are easily detectable by X ray and ultrasonography. (3) HAp granules have a large surface area and this characteristic is suitable for a carrier of drugs. It is concluded that HAp granules have some necessary prerequisites for a chemo embolic agent and the application to clinical practice may be expected.

Electrically-induced collagen calcification in pig skin. A histopathologic and histochemical study

Deposition of calcium salts on collagen fibres in skin of fully anaesthetized pigs was induced by exposure to direct current (d.c.). In biopsies obtained from cathode areas successively from day 1 to day 7 after exposure the histopathologic and histochemical changes before and after the initial deposition of calcium salts have been examined. For comparison skin sites with intradermal injected calcium hydroxyapatite crystals were studied in addition. Small areas of calcified collagen and elastic fibres were noted in viable tissue 2 days after d.c. exposure. In succeeding days the calcified areas enlarged with new deposits always more superficial and closer to the epidermis than the original calcium deposits. Preconditions for calcification appear to be (1) a pH change in basic direction and/or the electrochemical processes specific to the cathode area and (2) a viable tissue. Elastic fibres appear to have a lower calcification threshold than collagen fibres. A positive staining for glycoproteins (PAS) and glycosaminoglycans (alcian blue pH 2.5) was noted in the calcified collagen fibres simultaneously with the calcification. In succeeding days the intensity of the staining reactions increased. Whether changes in the glycoproteins, collagen and its intimately bound glycosaminoglycans precede the calcification or the staining reactions develop secondarily to this deposition is not known. However, seven days after intradermal injections of Ca-apatite crystals in pig skin small and large crystals were observed ultrastructurally without any relation to collagen fibrils, but the calcified tissue presented a positive PAS and alcian blue reaction from day 2. Thus the PAS and alcian blue stainings in this model develop secondary to the deposition of calcium salts.

Examination of new bone growth on aluminium oxide implant contact surfaces after oral administration of ossein-hydroxyapatite compound to rats

In view of the many disadvantages of transplantation of autologous bone tissue, factors must be found which locally and systemically will adjust the balance between bone resorption and deposition in favour of new bone growth. The present study was undertaken, therefore, to examine whether oral administration of ossein-hydroxyapatite compound (OHC) could stimulate new bone growth on aluminium oxide implant surfaces and, if so, whether it was the mineral or organic part of the compound which was responsible. Whilst under anaesthesia, adult male Wistar rats each had 2 holes drilled into the femur and 2 precisely fitting aluminium oxide implants inserted. The animals were divided into 5 groups each of 5 rats and the groups received oral daily doses of 20 mg OHC, 100 mg OHC, 10 mg hydroxyapatite, 50 mg hydroxyapatite or no supplement (controls), respectively. After 20 days, each implant was evaluated by 5 cuts through the marrow area and the thickness of the newly grown layer of bone measured by a morphometric procedure. The results showed a significant increase in new bone growth for the 100 mg OHC group in comparison to the control group, and in comparison to the hydroxyapatite group. Because both supplemented groups received equivalent dosages of calcium and phosphate, the additional stimulation of new bone growth must have been due to the organic part of OHC (ossein). It is suggested that these results should stimulate in particular the clinical use of OHC in the critical initial phase of implant healing and delayed fracture healing.(ABSTRACT TRUNCATED AT 250 WORDS)

[Animal experiment studies of callus formation by hydroxyapatite injection]

Hydroxy-apatite may be suspended well in liquid high-molecular gelatine. This renders possible an application by local injection. By means of experimental animal investigations in 64 rabbits it could be proved, that hydroxy-apatite stimulates osteogenesis and local callus formation when being injected at artificial bone defects. Gelatine on its own without any HA-grains only leads to a callus-free bridging of the bone defect. In case of an injection of the HA-suspensions to muscular soft tissue, no stimulation of the osteogenesis could be proved. It has to be concluded, that hydroxy-apatite stimulates osteogenesis. To achieve this effect, a direct contact to osteogenetic cells is necessary.

A comparison of particulate and solid root forms of hydroxylapatite in dog extraction sites

A comparison of solid root forms and particulate hydroxylapatite implanted into dog tooth extraction sites showed both types of implants to be well tolerated. Neither prevented postextraction bone resorption, but the particles were better able physically to maintain ridge height and width than the root forms.

[The syndrome of enlarged orbits]

Combined orbital fractures cause hematomas and subsequent rigidity of the ligament apparatus around the inferior rectus muscles, while the few true blow-out fractures may lead to an adherence of connective tissues to the floor. The authors describe a third mechanism: Enlargement of the orbit impairs motility, especially the elevation of the globe: Diagnostic pressing of the orbital, parabulbar contents improves elevation. In 9 such cases that were free of the two other knows mechanisms motility was improved by reducing orbital volume. This was performed by implants (4 cases), by instillation of hydroxylapatite (4 cases) or by re-resection of the bony frame (1). Subsequent muscle surgery, if at all necessary, gave truly satisfactory results.

Experimental and preliminary clinical experience with absorbable calcium phosphate granules containing an antibiotic or antiseptic for the local treatment of osteomyelitis

Experimental studies on dogs with staphylococcal osteomyelitis showed that it is possible to reduce florid bone suppuration by the use of hydroxyapatite granules containing an antibiotic or antiseptic. In our series the use of flucloxacillin hydroxyapatite granules was superior to other treatment methods. Twelve patients were treated with thorough sequestrectomy, reliable wound closure and suitable stabilization supplemented with an implant of antibiotic or antiseptic hydroxyapatite granules, and an autologous spongiosa graft for large bone cavities or for discontinuity between the bone ends. The results of this preliminary study showed the treatment to be effective.

Histologic observation of soft tissue responses to implanted, multifaceted particles and discs of hydroxylapatite

The effects on soft tissue of short- and long-term implants of ceramic hydroxylapatite (durapatite) are reported. In rats, after one week and one, six, and 12 months of subcutaneous implantation of hydroxylapatite in multifaceted particle and disc form, neither particles nor discs had resulted in any microscopically remarkable inflammation. In beagle dogs, after subcutaneous implantation of hydroxylapatite as multifaceted particles and as discs for seven and 24 days, nine months, and two and six years, no implant migration was observed. Encapsulation of particles and discs of increasing thickness was seen throughout the six years of observation. Except for a few isolated macrophages seen within the connective tissue stroma at seven and 24 days, no evidence of inflammation was found. In tissue sections taken at six months from beagle dogs in which multifaceted particles had been placed subperiosteally beneath the gingiva, dense connective tissue was observed adjacent to and surrounding the individual particles. These results show that hydroxylapatite implanted subcutaneously in rats and dogs produces little or no inflammatory response and is compatible with tissue irrespective of the shape of the implant.

Apatite deposition disease. A new arthropathy

A method for identifying particles of crystalline calcium hydroxyapatite in synovial fluids and biopsy material has been developed with high-resolution scanning electron microscopy and an energy-dispersive micro-analytical system. Particles of hydroxyapatite were identified in the joints of six patients diagnosed as having osteoarthritis, three of whom had acute inflammatory episodes with effusions into the joints. Apatite was not identified in joints affected by rheumatoid arthritis and other types of arthropathy. Animal studies showed that hydroxyapatic crystals can cause an acute inflammatory reaction, and this has been confirmed by experimental studies in man. It is suggested that a third type of crystal-deposition disease should be recognised--namely, calcium-hydroxyapatite crystal-deposition disease.