Bisphosphonate treatment increases the size of the mandibular condyle and normalizes growth of the mandibular ramus in osteoprotegerin-deficient mice

Osteoprotegerin (OPG) is a novel secreted member of the tumor necrosis factor receptor family which plays a crucial role in negative regulation of osteoclastic bone resorption. OPG-deficient (OPG-/-) mice develop severe osteoporosis caused by significant enhancement of bone resorption by osteoclasts. We investigated the effect of administering bisphosphonate on mandibular growth and development in OPG-/- mice. Eight-week-old male OPG-/- mice and wild-type (WT) mice were administered bisphosphonate (1.25 mg/kg body weight) intraperitoneally once every 3 days for 30 days. All bone formation-related parameters and bone resorption-related parameters were significantly lower in OPG-/- mice with bisphosphonate than in those without bisphosphonate. The volume of the whole condyle and the mandibular length in OPG-/- mice without bisphosphonate were significantly smaller than in WT mice without bisphosphonate. Bisphosphonate treatment of the OPG-/- mice resulted in an increase in the volume of the mandibular condyle and mandibular ramus length. In fact, the mandibular ramus length in OPG-/- mice with bisphosphonate was similar to the length in WT mice without bisphosphonate. Histologically, the surface irregularity of the mandibular condyle that was observed in the OPG-/- mice without bisphosphonate tended to be less marked in the OPG-/- mice with bisphosphonate, and the proportion of the area of the cartilage layer relative to the whole condyle was significantly larger in OPG-/- mice with bisphosphonate than in those without bisphosphonate. In conclusion, bisphosphonate treatment results in an increase in mandibular condylar dimensions and normalization of mandibular ramus growth.

Malleus fixation: clinical and histopathologic findings

The goals of this study were to review important clinical and histopathologic features of malleus fixation. Ten clinical cases and 10 histopathologic cases of malleus fixation were identified. For the clinical cases, preoperative clinical data, surgical findings, and preoperative and postoperative audiometric findings were reviewed. Ninety percent of the clinical cases achieved significant reduction of the air-bone gap after operation. Two thirds of these cases had an air-bone gap of 10 dB or less, and the remainder had air-bone gaps between 20 and 28 dB after operation. For the temporal bone cases, clinical data, histopathologic findings, and other otologic diagnoses were reviewed. Malleus fixation can be idiopathic or a result of trauma, chronic otitis media, or developmental anomalies. It is a cause of hearing loss that is likely to be more common than the number of diagnoses would indicate. Certain audiometric findings may lead one to suspect the diagnosis. The surgical approach used depends on the individual anatomy, and surgery is usually highly effective in improving hearing.

HEAT STABILITY OF HUMAN PLACENTAL ALKALINE PHOSPHATASE

Alkaline phosphatase prepared from human placentae shows greater resistance to heat inactivation than any other known alkaline phosphatase of human origin. In the presence of magnesium this enzyme may be heated at 70 degrees C. for 30 minutes without loss of activity whereas other human alkaline phosphatases lose most of their activity on being heated at 56 degrees C. for this period of time. This heat stability is seen in freshly prepared enzyme, in alcohol-fractionated and freeze-dried material, and in the sera of individuals into whom placental alkaline phosphatase has been infused. The clinical implications of our observations are briefly indicated.

SOME ASPECTS OF CALCIUM METABOLISM IN MALIGNANT DISEASE OF BONE

The rate of calcification of new bone (accretion rate) was measured by a radioisotope technique in 20 patients with carcinoma of the breast, 14 patients with multiple myelomatosis, five patients with Paget's disease of bone, and in six patients with solitary, non-osseous tumours. The rate of bone destruction was assessed in these patients by the measurement of the rate of urinary calcium excretion. In the patients with carcinoma of the breast and bone metastases there was a marked increase both in the accretion rate and in the urinary calcium excretion suggesting an osteoblastic response to bone destruction. An osteoblastic response was also present in the patients with multiple myelomatosis but was not correlated with the urinary calcium excretion. In patients with Paget's disease of bone, high values of accretion rate were found indicating very active new bone formation.