Hajime Yamada

Effects of human PTH-related peptide and human PTH on cyclic AMP production and cytosolic free calcium in an osteoblastic cell clone

Recently, human parathyroid hormone-related peptide (hPTHrP) has been purified and its amino acid sequence determined. Within the amino-terminal 13 residues of hPTHrP, 8 amino acids were found homologous between hPTHrP and human PTH (hPTH). This peptide was reported to stimulate cyclic AMP (cAMP) production in osteoblastic cell lines (UMR106 and ROS17/2.8). However, whether or not this peptide affects another second messenger, i.e., cytosolic free calcium ([Ca2+]i), in osteoblasts has not yet been determined. Therefore, in the present study, we examined the effects of synthetic amino-terminal fragments of hPTHrP (Tyr40hPTHrP1-40 and hPTHrP1-34) on intracellular cAMP production and [Ca2+]i in an osteoblastic cell line (MC3T3-E1) and compared them with those of hPTH1-34. Human PTHrP1-34, Tyr40hPTHrP1-40 and hPTH1-34 stimulated cAMP production in an equipotent manner at concentrations ranging from 2.5 x 10(-10) to 1.3 x 10(-6) M. Human PTH1-34 at concentrations from 2.5 x 10(-7) to 1.3 x 10(-6) M significantly (P less than 0.05) increased [Ca2+]i, but hPTHrP1-34 and Tyr40hPTHrP1-40 at the same concentrations did not. These results suggest a different receptor-mediated mechanism for [Ca2+]i increase between hPTHrP and hPTH, although these two peptides appear to share the same receptor site(s) which is coupled to the cAMP system in MC3T3-E1.

Oncogenic ras induces gastrin/CCKB receptor gene expression in human colon cancer cell lines LoVo and Colo320HSR

Gastrin has the ability to stimulate cell growth in some colorectal cancer cells and some of these cells also express gastrin/CCKB receptors, suggesting that gastrin and its autocrine loop are involved in their proliferation. We previously reported that oncogenic ras induced gastrin gene expression in colon cancer cells. The aim of this study was to investigate whether oncogenic ras also induces gastrin/CCKB receptor gene expression. A transiently transfected activated ras vector stimulated gastrin/CCKB receptor transcriptional activities in both Colo320HSR and LoVo cells, but these ras-increased activities were inhibited by a specific MEK inhibitor, PD98059. An RPA demonstrated that activated ras increased endogenous gastrin/CCKB receptor mRNA levels and PD98059 decreased them in LoVo cells. These findings suggest that oncogenic ras induces gastrin/CCKB receptor gene expression through some intracellular signaling pathways, including MEK, in colon cancer cell lines.

Bioavailability of Oyster Shell Electrolysate

Balance studies were conducted on 4 normal elderly subjects, 2 males and 2 females, ranging in age between 66 and 86 years in order to compare the bioavailability of oyster shell electrolysate with that of calcium carbonate and calcium lactate, in a crossover design. In each subject, 600 mg oyster shell electrolysate was more effective than calcium carbonate or calcium lactate containing the same 600 mg calcium to restore the negative calcium balance found on 600 mg/day calcium intake, suggesting a better bioavailability of oyster shell electrolysate than the two kinds of calcium salts.

Quantitative computed tomography: Comparison of two calibration phantoms

Vertebral trabecular mineral density of healthy Japanese (91 females and 67 males) was measured using the quantitative computed tomography (QCT) technique in a cross-sectional study. We compared estimates of vertebral bone density using two calibration phantoms: the Genant K2HPO4 phantom developed by Genant and a solid CaCO3 phantom developed by Chugai Pharmaceutical. Using the CaCO3 phantom, the rate of decrease of spinal trabecular mineral with age in control females averaged 1.1% per year from age 20 to 80, with an accelerated loss demonstrated at menopause (1.8%). Trabecular bone mass in male controls declined an average 0.9% per year. There was a highly significant correlation between the results obtained with each phantom (r=0.980, p<0.001). This relation was linear over the range of bone mass (60 –172 mg K2HPO4/cm3), and was expressed by the equation y(CaCO3)=1.26×(K2HPO4)+12.3 There was, however, some dispersion of the data around the regression. The calibration phantom used for the measurement of the vertebral trabecular bone should need to be more consistent in longitudinal studies. Apart from this consideration, a solid Chugai phantom can be said to be useful having practical advantages in its flexibility.

Arachidonic acid stimulates cell growth in an osteoblastic cell line, MC3T3-E1, by noneicosanoid mechanism

SummaryArachidonic acid, added to α-minimum essential medium containing 10% fetal bovine serum at the final concentration of 10−4 M, significantly increased DNA content of an osteoblastic cell line, MC3T3-E1, along with an increase of DNA synthesis. No growth-stimulatory effect of arachidonic acid was observed under serum-free condition. α-Linolenic acid, which cannot be converted to arachidonic acid, also increased DNA content at 10−4 M. Additionally, the stimulatory effects of these fatty acids were not inhibited by simultaneous addition of 10−5 M of indomethacin. Indomethacin, when added to α-minimum essential medium with 10% fetal bovine serum, also significantly increased DNA content of MC3T3-E1 cells. These results suggest that arachidonic acid may potentiate the growth-stimulatory effect of serumderived growth factors probably via noneicosanoid mechanism. Rat osteogenic sarcoma cell line, UMR106, also showed an increase in DNA content with arachidonic acid treatment. Hence, it is suggested that arachidonic acid may stimulate proliferation of cells of osteoblastic lineage. It is also suggested that indomethacin, probably by blocking endogenous prostaglandin E2 synthesis, stimulates cell growth in MC3T3-E1 cells.

Comparison of antero-posterior and lateral measurements of the vertebral mineral contents by dual-energy x-ray absorptiometry

Bone mineral measurements of the 2nd and 3rd vertebrae were made using dual energy x-ray absorptiometry (DEXA) in both antero-posterior (AP) and lateral (Lat) projections in 49 women (Group I; 24 young controls, II; 11 elderly controls, III; 14 osteoporotics). The coefficients of variation of the AP and Lat measurements of BMC in 3 young women were 2.2% and 8.4% of the respective mean values. In Group I, BMCs obtained by the Lat measurement were 11.6±15.7% below BMCAP (p<0.05). In Group II and III, on the other hands, BMCLat was as low as below 34.2±11.9% (Group II) and 40.1±21.5% (Group III) of respective AP contents (p<0.01). This discrepancy between BM CLat and BMCAP in Group II and III could not be acounted by the measurement error of Lat determination alone. Furthermore, the difference of bone mineral density (BMD) between Group I and II (or III) appeared to be much more pronounced when compared by the data obtained from the Lat measurements than the comparison using BMDAP. Extra-skeltal calcification projected on the AP plane, including calcified aorta and ligaments, may attribute such a difference between AP and Lat measurements. Our observation indicated the possibility of an overestimation of BMC and BMD by the AP determination of the spine. Therfore, an improvement of the reproducibility to measure the spine by the Lat determination with DEXA is mandatory for the detection of subclinical osteoporosis.

The human parathyroid hormone -related protein mimics the action of human parathyroid hormone in an osteoblastic cell line, MC3T3-E1

The effects of amino-terminal fragments of human parathyroid hormone (hPTH 1-34) and the human parathyroid hormone-related protein (hPTHrP 1–34, Tyr40-hPTHrP 1–40) on cell growth and alkaline phosphatase activity were studied in an osteoblastic cell line, MC3T3-E1. The three peptides were equipotent in suppressing DNA synthesis and alkaline phosphatase activity. These results suggest that the three peptides have similar post-receptor effects in osteoblasts probably through the same receptor sites.

Factors associated with complicated erosive esophagitis: A Japanese multicenter, prospective, cross-sectional study

AIM To assess the clinical characteristics of patients with complicated erosive esophagitis (EE) and their associated factors. METHODS This prospective, cross-sectional study included patients diagnosed with EE by upper gastrointestinal endoscopy between October 2014 and March 2015 at 106 Japanese hospitals. Data on medical history, general condition, gastrointestinal symptoms, lifestyle habits, comorbidities, and endoscopic findings were collected using a standard form to create a dedicated database. Logistic regression analysis was used to calculate adjusted odds ratios (aOR) and 95%CI for the association with complicated EE. RESULTS During the study period, 1749 patients diagnosed with EE, 38.3% of whom were prescribed proton pump inhibitors (PPIs) were included. Of them, 143 (8.2%) had EE complications. Esophageal bleeding occurred in 84 (4.8%) patients, esophageal strictures in 45 (2.6%) patients, and 14 (0.8%) patients experienced both. Multivariate analysis showed that increased age (aOR: 1.05; 95%CI: 1.03-1.08), concomitant use of psychotropic agents (aOR: 6.51; 95%CI: 3.01-13.61), and Los Angeles grades B (aOR: 2.69; 95%CI: 1.48-4.96), C (aOR: 15.38; 95%CI: 8.62-28.37), and D (aOR: 71.49; 95%CI: 37.47-142.01) were significantly associated with complications, whereas alcohol consumption 2-4 d/wk was negatively associated (aOR: 0.23; 95%CI: 0.06-0.61). Analyzing associated factors with each EE complication separately showed esophageal ulcer bleeding were associated with increased age (aOR: 1.05; 95%CI: 1.02-1.07) and Los Angeles grades B (aOR: 3.60; 95%CI: 1.52-8.50), C (aOR: 27.61; 95%CI: 12.34-61.80), and D (aOR: 119.09; 95%CI: 51.15-277.29), while esophageal strictures were associated with increased age (aOR: 1.07; 95%CI: 1.04-1.10), gastroesophageal reflux symptom (aOR: 2.51; 95%CI: 1.39-4.51), concomitant use of psychotropic agents (aOR: 11.79; 95%CI: 5.06-27.48), Los Angeles grades C (aOR: 7.35; 95%CI: 3.32-16.25), and D (aOR: 20.34; 95%CI: 8.36-49.53) and long-segment Barrett’s esophagus (aOR: 4.63; 95%CI: 1.64-13.05). CONCLUSION Aging and severe EE were common associated factors, although there were more associated factors in esophageal strictures than esophageal ulcer bleeding. Despite the availability and widespread use of PPIs, EE complications are likely to remain a problem in Japan owing to the aging population and high-stress society.