Decreased effectiveness of fiscal and monetary policies in Japan's aging society

This paper studies how an aging population affects economic performance and the effectiveness of fiscal and monetary policies. We develop a New Keynesian dynamic stochastic general equilibrium model with heterogeneous households, workers, and retirees. We demonstrate that an increase in the proportion of working population increases aggregate output, consumption, and investment by increasing total labor supply in the long run. It also increases wages and reduces social security burden of the government. This paper also finds that effectiveness of fiscal and monetary policies is weakened when the proportion of retirees becomes larger. This is the reason why recent monetary policies cannot recover the Japanese economy from the prolonged stagnation

The effectiveness of Japan's Negative Interest rate policy

This paper investigates the effect of zero and negative interest rate policy of Japan on the inflation rate and the role of exchange rate in conducting the zero and negative interest rate policy. The disappointing economic performance thus seems primarily due to a series of adverse economic shocks rather than an extraordinary policy error. The empirical analysis is based on, primarily, a stylized VAR model of the Japanese economy with the innovation that the interest rate policy, and the exchange rate—two important parameters for assessing the stance of monetary policy—are allowed to vary over time. Secondly, the estimated VAR model investigates whether alternative interest-rate policy approaches proposed in the literature could have improved macroeconomic performance. Though, Granger causality method has been used in the earlier literature to measure the causation of interest rate on inflation rate and it also used to see the block and instantaneous causality between the systems of variables. Next, using an estimated structural model, I identified a number of adverse shocks occurring after the 1990s. It thus follows that int. rate policy was not solely responsible for the stimulation neither in inflation growth performance nor in increasing the output growth. Aiming for a low inflation level and responding to the economy according to a conventional policy rule provided insufficient insurance against the contractionary shocks that occurred over the 1990s

Effects of acidic calcium phosphate concentration on setting reaction and tissue response to β-tricalcium phosphate granular cement

Beta-tricalcium phosphate granular cement (β-TCP GC), consisting of β-TCP granules and an acidic calcium phosphate (Ca-P) solution, shows promise in the reconstruction of bone defects as it sets to form interconnected porous structures, i.e., β-TCP granules are bridged with dicalcium phosphate dihydrate (DCPD) crystals. In this study, the effects of acidic Ca-P solution concentration (0–600 mmol/L) on the setting reaction and tissue response to β-TCP GC were investigated. The β-TCP GC set upon mixing with its liquid phase, based on the formation of DCPD crystals, which bridged β-TCP granules to one another. Diametral tensile strength of the set β-TCP GC was relatively the same, at approximately 0.6 MPa, when the Ca-P concentration was 20–600 mmol/L. Due to the setting ability, reconstruction of the rat’s calvarial bone defect using β-TCP GC with 20, 200, and 600 mmol/L Ca-P solution was much easier compared to that with β-TCP granules without setting ability. Four weeks after the reconstruction, the amount of new bone was the same, approximately 17% in both β-TCP GC and β-TCP granules groups. Cellular response to β-TCP granules and β-TCP GC using the 20 mmol/L acidic Ca-P solution was almost the same. However, β-TCP GC using the 200 and 600 mmol/L acidic Ca-P solution showed a more severe inflammatory reaction. It is concluded, therefore, that β-TCP GC, using the 20 mmol/L acidic Ca-P solution, is recommended as this concentration allows surgical techniques to be performed easily and provides good mechanical strength, and the similar cellular response to β-TCP granules

Histological comparison of three apatitic bone substitutes with different carbonate contents in alveolar bone defects in a beagle mandible with simultaneous implant installation

Since bone apatite is a carbonate apatite containing carbonate in an apatitic structure, carbonate content may be one of the factors governing the osteoconductivity of apatitic bone substitutes. The aim of this study was to evaluate the effects of carbonate content on the osteoconductivity of apatitic bone substitutes using three commercially available bone substitutes for the reconstruction of alveolar bone defects of a beagle mandible with simultaneous dental implant installation. NEOBONE®, Bio-Oss®, and Cytrans® that contain 0.1 mass%, 5.5 mass%, and 12.0 mass% of carbonate, respectively, were used in this study. The amount of newly formed bone in the upper portion of the alveolar bone defect of the beagle’s mandible was 0.7%, 6.6%, and 39.4% at 4 weeks after surgery and 4.7%, 39.5% and 75.2% at 12 weeks after surgery for NEOBONE®, Bio-Oss®, and Cytrans®, respectively. The results indicate that bone-to-implant contact ratio was the largest for Cytrans®. Additionally, the continuity of the alveolar ridge was restored in the case of Cytrans®, whereas the continuity of the alveolar ridge was not sufficient when using NEOBONE® and Bio-Oss®. Both Cytrans® and Bio-Oss® that has a relatively larger carbonate content in their apatitic structure was resorbed with time. We concluded that carbonate content is one of important factors governing the osteoconductivity of apatitic bone substitutes

マイクロファイバーを用いた多孔質炭酸アパタイト顆粒の開発とウサギ頭蓋骨における組織学的評価

Carbonate apatite (CO3Ap) granules are known to show good osteoconductivity and replaced to new bone. On the other hand, it is well known that a porous structure allows bone tissue to penetrate its pores, and the optimal pore size for bone ingrowth is dependent on the composition and structure of the scaffold material. Therefore, the aim of this study was to fabricate various porous CO3Ap granules through a two-step dissolution-precipitation reaction using CaSO4 as a precursor and 30-, 50-, 120-, and 205-μm diameter microfibers as porogen and to find the optimal pore size of CO3Ap. Porous CO3Ap granules were successfully fabricated with pore size 8.2-18.7% smaller than the size of the original fiber porogen. Two weeks after the reconstruction of rabbit calvarial bone defects using porous CO3Ap granules, the largest amount of mature bone was seen to be formed inside the pores of CO3Ap (120) [porous CO3Ap granules made using 120-μm microfiber] followed by CO3Ap (50) and CO3Ap (30). At 4 and 8 weeks, no statistically significant difference was observed based on the pore size, even though largest amount of mature bone was formed in case of CO3Ap (120). It is concluded, therefore, that the optimal pore size of the CO3Ap is that of CO3Ap (120), which is 85 μm

Current status and future development of carbonate apatite as a bone substitute

A main inorganic component of human bone is not hydroxyapatite but carbonate apatite (CQ3Ap). Hydroxyapatite is not resorbed in the body but C03Ap can be resorbed and replaced with bone. We have succeeded in fabricating low crystalline CQ3Ap without sintering by dissolution-precipitation reaction using calcium hydroxide as a precursor. C03Ap showed excellent biocompatibility and faster bone formation compared to other bone substitutes (anorganic bovine bone and hydroxyapatite) in rabbit femur and dog mandible. Clinical study on effectiveness and safety of C03Ap granules in sinus floor augmentation was successfully concluded in 2016. CQ3Ap granules were approved by Japanese government in 2017, and marketed in 2018 as Cytrans® Granules. This comprehensive review explains the clinical cases of sinus lift and alveolar ridge augmentation of Cytrans® and its recommended clinical usage. Furthermore, we have succeeded in developing porous C03Ap and showed it was useful for reconstruction of mandibular bone defect in rabbit model and also aim to use it as a scaffold for bone regenerative medicine.ヒトの骨の無機主成分はハイドロキシアパタイトではなく，炭酸アパタイト (CO3Ap) である．ハイドロキシアパタイトは体内で吸収されないが，CO3Apは吸収されて骨と置換する．われわれは水酸化カルシウムを前駆物質として，焼結操作を用いずに溶解析出反応によって低結晶性の炭酸アパタイトを人工合成することに成功した．炭酸アパタイ卜顆粒は，ウサギ大腿骨とイヌ顎骨における実験で，他の骨補填材よりも骨が速く形成すること，優れた生体親和性を示すことを明らかにした．2016年に上顎洞底挙上術での臨床治験を成功裏に終え，2017年に炭酸アパタイト顆粒は薬事承認され，2018年からサイトランス® グラニュールとして市販された本総説では，サイトランス® による上顎洞底挙上症例と歯槽堤造成術症例を紹介すると共に，その臨床的推奨使用法を説明した．さらに，著者らは多孔質の炭酸アパタイトの作製に成功し，炭酸アパタイト多孔体がウサギの下顎骨欠損モデルにおいて骨再建に有用であることを示した．現在，炭酸アパタイト多孔体の骨再生医療用スキャフォールドヘの応用を目指している

Staged Sinus Floor Elevation Using Novel Low-Crystalline Carbonate Apatite Granules : Prospective Results after 3-Year Functional Loading

The aim of this study was to evaluate clinical outcomes of staged sinus floor elevation (SFE) using novel low-crystalline carbonate apatite (CO3Ap) granules. Patients who needed SFE for implant placement were recruited into this clinical trial. A staged procedure (lateral window technique using CO3Ap granules, followed by implant placement after 7 ± 2 months) was employed in 13 patients. Bone-height increase and insertion torque values (ITVs) were assessed along with histological evaluation. The survival and success rates of 3-year functioning implants were also evaluated. Mean of bone-height increase after SFE using CO3Ap granules was 7.2 ± 2.5 mm and this increase allowed implant placement in all cases (17 implants). Mean of ITV was 25.1 ± 13.2 Ncm and primary stability was achieved successfully in all cases. Histological analyses revealed mature new bone formation (36.8 ± 17.3%) and residual CO3Ap granules (16.2 ± 10.1%) in the compartment after SFE. The survival and success rates after 3-year functional loading were 100% and no complications were found. These results clearly indicate the clinical usefulness of CO3Ap granules for SFE

Reconstruction of rabbit mandibular bone defects using carbonate apatite honeycomb blocks with an interconnected porous structure

Carbonate apatite (CO3Ap) granules are useful as a bone substitute because they can be remodeled to new natural bone in a manner that conforms to the bone remodeling process. However, reconstructing large bone defects using CO3Ap granules is difficult because of their granular shape. Therefore, we fabricated CO3Ap honeycomb blocks (HCBs) with continuous unidirectional pores. We aimed to elucidate the tissue response and availability of CO3Ap HCBs in the reconstruction of rabbit mandibular bone defects after marginal mandibulectomy. The percentages of the remaining CO3Ap area and calcified bone area (newly formed bone) were estimated from the histological images. CO3Ap area was 49.1 ± 4.9%, 30.3 ± 3.5%, and 25.5 ± 8.8%, whereas newly formed bone area was 3.0 ± 0.6%, 24.3 ± 3.3%, and 34.7 ± 4.8% at 4, 8, and 12 weeks, respectively, after implantation. Thus, CO3Ap HCBs were gradually resorbed and replaced by new bone. The newly formed bone penetrated most of the pores in the CO3Ap HCBs at 12 weeks after implantation. By contrast, the granulation tissue scarcely invaded the CO3Ap HCBs. Some osteoclasts invaded the wall of CO3Ap HCBs, making resorption pits. Furthermore, many osteoblasts were found on the newly formed bone, indicating ongoing bone remodeling. Blood vessels were also formed inside most of the pores in the CO3Ap HCBs. These findings suggest that CO3Ap HCBs have good osteoconductivity and can be used for the reconstruction of large mandibular bone defects