Masaaki Fukase

Effect of elevated extracellular calcium on the proliferation of osteoblastic MC3T3-E1 cells:its direct and indirect effects via monocytes.

There has been evidence that elevated calcium concentration at the resorptive site of the bone directly regulates osteoclast function. In the present study, in order to clarify the role of elevated calcium concentration at the resorptive site in the regulation of osteoblast function, not only direct but also indirect effect via human monocytes of the increase in extracellular calcium (Cae) on the proliferation of osteoblastic MC3T3-E1 cells have been investigated in serum-free condition. The increase in Cae enormously stimulated osteoblast proliferation at the concentration of 3 to 20 mM. When human monocytes were cultured at the elevated Cae concentration, monocyte-conditioned medium-induced stimulation of osteoblast proliferation was significantly amplified. Present data demonstrate that elevated Cae has pronounced stimulatory effect on osteoblast proliferation not only directly but also indirectly via monocytes. Calcium released from bone matrix at the resorptive sites might be linked to the coupling of osteoclast and osteoblast functions.

Ectopic production of human chorionic gonadotropin in malignant tumors

The prevalence of human chorionic gonadotropin (hCG) was estimated by measuring immunoreactive hCG in plasmas and tumor tissues from patients with various neoplasms. To detect small amount of plasma hCG in the presence of luteinizing hormone (LH), plasma hCG level was measured by heterologous radioimmunoassay using anti‐hCG‐β antiserum and compared with plasma LH level measured by heterologous radioimmunoassay using anti‐LH‐β antiserum. All 56 samples obtained from control subjects were found to be negative for hCG, while 10 of 100 plasma samples from patients with malignancies were positive for hCG. The prevalence of hCG in 64 tumor tissues was 42% (27/64); it was 32% (8/25) in so‐called amine precursor uptake and decarboxylation (APUD) tumors and 49% (19/39) in non‐APUD tumors. The difference in the prevalence of hCG in APUD vs. non‐APUD tumors was not statistically significant. However, the amounts of hCG in APUD tumors were found to be less than 50 ng/g wet tissue, whereas those of non‐APUD tumors ranged from several ng to thousands of ng/g wet tissue. These results suggest the APUD tumors produce less amounts of hCG than do non‐APUD tumors. Cancer 42:2328–2333, 1978.

Effects of ascorbic acid on alkaline phosphatase activity and hormone responsiveness in the osteoblastic osteosarcoma cell line UMR-106

SummaryL-ascorbic acid at physiological concentrations (10 μg/ml) increased alkaline phosphatase activity in the osteoblastlike rat osteosarcoma cell line, UMR-106. The increase was dose-dependent and detectable at 6 hours after the addition of 100 μg/ml ascorbic acid to the medium. Treatment of the cells with 100 μg/ml ascorbic acid potentiated the response of cAMP to both PTH and PGE1, while cell growth was inhibited. Furthermore, the number of colonies formed by the cells grown, in the soft agar was significantly reduced by increasing concentrations of ascorbic acid. These results indicate that ascorbic acid might play some role in the differentiation of osteoblasts.

Autocrine effect of endothelin on DNA synthesis in human vascular endothelial cells

To elucidate the role of endogenous endothelin on DNA synthesis in endothelial cells, we have investigated the effects of rabbit anti-ET gamma globulin on DNA synthesis in cultured human vascular endothelial cells. DNA synthesis was markedly inhibited by anti-ET gamma globulin in a concentration dependent manner in the presence of fetal calf serum(FCS) (x5000;34%, x2500;54%, x1000;70%), but not in the absence of FCS. These data suggest that endogenous ET modulates FCS-stimulated DNA synthesis in an autocrine fashion.

The expression of parathyroid hormone-related protein in human breast cancer with skeletal metastases

The relationship between the expression of parathyroid hormone-related protein (PTHrP) by breast cancer and skeletal metastases, was investigated using a monoclonal antibody against human PTHrP (4133). The immunohistochemical localization of PTHrP was studied in sections of formalin-fixed, paraffin-embeded tissues from 28 breast cancers obtained surgically between 1980 and 1985. Of the 28 patients, 12 developed skeletal metastases, 8 developed lung metastases, and the other 8 were alive and disease-free at the time of this study. Sixteen of the 28 (57%) tumors showed positive immunoreactivity to 4133, the PTHrP positive ratio being 83% in the patients who developed skeletal metastases, 38% in those who developed lung metastases, and 38% in those without recurrence, respectively. Thus, a significantly higher proportion of the patients who developed skeletal metastases were positive for PTHrP than the other two groups (P < 0.05). Furthermore, the level of positive staining was strongly related to positivity for estrogen and progesterone receptors (P < 0.01). These results are consistent with the hypothesis that PTHrP might be necessary for metastases to erode bone and grow in skeletal sites, and its expression could be related to certain hormones.

Effects of continuous infusion of parathyroid hormone and parathyroid hormone-related peptide on rat bone in vivo: comparative study by histomorphometry.

We have investigated the actions of parathyroid hormone (PTH) and PTH-related peptide (PTHrP) on the bones of parathyroidectomized (PTX) rats by histomorphometric analysis. Miniosmotic pumps filled with either human PTH (hPTH)(1-34), hPTHrP(1-34) or vehicle were subcutaneously implanted on the backs of the rats. The peptides were continuously infused for 6 days at a rate of 15 nmole/kg/day. PTH and PTHrP exhibited similar hypercalcemic and hypophosphatemic actions on these PTX rats. No significant differences were noted in bone weight or calcium and phosphorus contents of the ashed bone among the 3 groups. By quantitative histomorphometric analysis, hPTH(1-34) and hPTHrP(1-34) were found similarly to enhance both bone formation and resorption. Peritrabecular fibrosis was observed only in the PTH-infused animals. PTHrP thus mimics the actions of PTH, but is not as effective in promoting mesenchymal cell proliferation along the bone trabeculae.

Successful treatment of hyperphosphatemic tumoral calcinosis with long-term acetazolamide.

We describe a patient with tumoral calcinosis, in which acetazolamide (ACZ) was, for the first time, tested for its therapeutic efficacy. The 19-year-old Japanese man had been suffering from multiple recurrent calcific masses with tenderness around the finger, knee, and toe joints since 10 months of age. Radiographs revealed several calcific subcutaneous masses around the finger joints, and calcific myelitis around the right knee joint and in the calvarium. The patient had hyperphosphatemia with elevated maximal threshold of renal phosphate excretion in the presence of normal kidney function and normocalcemia, suggesting a reduced ability to excrete phosphorus in the urine. A delay of disappearance of orally administered phosphate from the blood stream was found. A serum parathyroid hormone (PTH) level was normal, and responses to PTH and ACZ were also normal regarding the induction of phosphaturia. Since the masses tended to recur easily despite repeated surgical resections, we started medical treatment with phosphorus deprivation by oral aluminum hydroxide. However, the drug alone had no effect on hyperphosphatemia or calcific lesions, and ACZ was added in expectation of making the patients phosphorus balance negative by its phosphaturic effect. Fourteen years of administration of the two drugs apparently improved the patients symptoms, the biochemical findings, and the calcific lesions on radiographs. Thus, ACZ appeared to be useful for tumoral calcinosis resistant to phosphorus deprivation by aluminum hydroxide alone.

Possible discrimination of Gitelman's syndrome from Bartter's syndrome by renal clearance study: Report of two cases

We observed two patients who had hypokalemic metabolic alkalosis as well as hypomagnesemia and hypocalciuria with elevated serum renin levels. In renal clearance studies in our patients using furosemide or thiazide, urine volume and chloride clearance (CCI) were increased after furosemide administration but not after thiazide administration. Furthermore, the distal fractional chloride reabsorption [CH2O/(CH2O + CCI)] was dramatically decreased by furosemide administration in our patients, whereas thiazide had little effect on it, suggesting the presence of a defect in the distal tubule rather than in the thick ascending loop of Henle. These findings are compatible with the concept of Gitelmans syndrome, a variant form of Bartters syndrome.

Increase of bone mineral density by calcium supplement with oyster shell electrolysate

The effect of calcium supplementation, in patients with osteoporosis is still a matter of controversy. Oyster shell electrolysate (OSE) was reported to raise serum calcium and increase urinary calcium excretion in vitamin D-deficient states more readily than calcium carbonate. Since the effect of calcium salts on osteoporosis depends heavily on its bioavailability, the effect of 900 mg/day calcium as OSE was tested in 12 elderly osteoporotic females, using radial bone mineral density measured by single photon absorptiometry and spinal trabecular bone density measured by quantitative computed tomography (QCT) as indicated, in comparison with 21 untreated controls in the same geriatric hospital. Radial bone mineral density significantly increased from the pre-test value after 12 and 24 months in subjects given OSE by paired t-test, whereas it fell significantly in the controls. The spinal QCT value on OSE did not change significantly in either the subjects under treatment with OSE, or the controls. Thus OSE may favorably influence osteoporosis by providing a readily available source of calcium.

Quantitative computed tomography of lumbar vertebrae in Japanese patients with osteoporosis

Vertebral trabecular bone mineral density of both healthy Japanese subjects and Japanese patients with osteoporosis was measured by quantitative computed tomography (QCT) technique. The age-related reduction rate in vertebral trabecular bone mineral density of control females averaged 1.1% per year, from age 20 to 80, with an accelerated loss demonstrated after age 40. In the male controls, trabecular bone mineral density declined by an average of 0.9% per year. These values were found to be similar to the University of California at San Francisco (UCSF) QCT data (US Caucasians: 1.2% for female, 0.72% for male). Therefore, it appears that age-related rates of trabecular bone loss in the lumbar vertebrae may be similar for both Japanese and Caucasians. However, when compared to average values in UCSF QCT data of comparable age and sex, the mean values in Japanese appear to be approximately 10-20 mg/cm3 lower than Caucasian counterparts. All female patients with osteoporosis as evidenced by atraumatic vertebral fracture had QCT values below 50 mg/cm3. It is suggested that the Japanese may have lower trabecular bone mineral density than Caucasians but may also have a lower threshold for fracture of the vertebrae. Further studies are needed to establish the possible racial differences in vertebral trabecular bone mineral density, and to determine whether these possible disparities are related to genetic differences, or to differences in body size, dietary intake, physical activity or other lifestyle/environmental factors.