The development of non-resorbable bone allografts: Biological background and clinical perspectives.

Bone grafts are typically categorized into four categories: autografts, allografts, xenografts, and synthetic alloplasts. While it was originally thought that all bone grafts should be slowly resorbed and replaced with native bone over time, accumulating evidence has in fact suggested that the use of nonresorbable xenografts is favored for certain clinical indications. Thus, many clinicians take advantage of the nonresorbable properties/features of xenografts for various clinical indications, such as contour augmentation, sinus grafting, and guided bone regeneration, which are often combined with allografts (e.g., human freeze-dried bone allografts [FDBAs] and human demineralized freeze-dried bone allografts [DFDBAs]). Thus, many clinicians have advocated different 50/50 or 70/30 ratios of allograft/xenograft combination approaches for various grafting procedures. Interestingly, many clinicians believe that one of the main reasons for the nonresorbability or low substitution rates of xenografts has to do with their foreign animal origin. Recent research has indicated that the sintering technique and heating conducted during their processing changes the dissolution rate of hydroxyapatite, leading to a state in which osteoclasts are no longer able to resorb (dissolve) the sintered bone. While many clinicians often combine nonresorbable xenografts with the bone-inducing properties of allografts for a variety of bone augmentation procedures, clinicians are forced to use two separate products owing to their origins (the FDA/CE does not allow the mixture of allografts with xenografts within the same dish/bottle). This has led to significant progress in understanding the dissolution rates of xenografts at various sintering temperature changes, which has since led to the breakthrough development of nonresorbable bone allografts sintered at similar temperatures to nonresorbable xenografts. The advantage of the nonresorbable bone allograft is that they can now be combined with standard allografts to create a single mixture combining the advantages of both allografts and xenografts while allowing the purchase and use of a single product. This review article presents the concept with evidence derived from a 52-week monkey study that demonstrated little to no resorption along with in vitro data supporting this novel technology as a "next-generation" biomaterial with optimized bone grafting material properties

Comparison of the effects of recombinant human bone morphogenetic protein-2 and -9 on bone formation in rat calvarial critical-size defects.

OBJECTIVES Among bone morphogenetic protein (BMP) family members, BMP-2 and BMP-9 have demonstrated potent osteoinductive potential. However, in vivo differences in their potential for bone regeneration remain unclear. The present study aimed to compare the effects of recombinant human (rh) BMP-2 and rhBMP-9 on bone formation in rat calvarial critical-size defects (CSD). MATERIALS AND METHODS Twenty-eight Wistar rats surgically received two calvarial defects bilaterally in each parietal bone. Defects (n = 56) were allocated into four groups: absorbable collagen sponge (ACS) alone, rhBMP-2 with ACS (rhBMP-2/ACS), rhBMP-9/ACS, or sham surgery (control), on the condition that the treatments of rhBMP-2/ACS and rhBMP-9/ACS, or the same treatments were not included in the same animal. Animals were sacrificed at 2 and 8 weeks post-surgery. The calvarial defects were analyzed for bone volume (BV) by micro-computed tomography and for percentages of defect closure (DC/DL), newly formed bone area (NBA/TA), bone marrow area (BMA/NBA), adipose tissue area (ATA/NBA), central bone height (CBH), and marginal bone height (MBH) by histomorphometric analysis. RESULTS The BV in the rhBMP-2/ACS group (5.44 ± 3.65 mm3, n = 7) was greater than the other groups at 2 weeks post-surgery, and the rhBMP-2/ACS and rhBMP-9/ACS groups (18.17 ± 2.51 and 16.30 ± 2.46 mm3, n = 7, respectively) demonstrated significantly greater amounts of BV compared with the control and ACS groups (6.02 ± 2.90 and 9.30 ± 2.75 mm3, n = 7, respectively) at 8 weeks post-surgery. The rhBMP-2/ACS and rhBMP-9/ACS groups significantly induced new bone formation compared to the control and ACS groups at 8 weeks post-surgery. However, there were no statistically significant differences found between the rhBMP-2/ACS and rhBMP-9/ACS groups in any of the histomorphometric parameters. The ATA/NBA in the rhBMP-2/ACS group (9.24 ± 3.72%, n = 7) was the highest among the treatment groups at 8 weeks post-surgery. CONCLUSIONS Within the limits of this study, it can be concluded that rhBMP-2/ACS induced a slight early increase in new bone formation at 2 weeks and that rhBMP-9/ACS provided comparable new bone formation to rhBMP-2/ACS with less adipose tissues after a healing period of 8 weeks in rat CSD. CLINICAL RELEVANCE RhBMP-9/ACS treatment provided new bone formation with less adipose tissues compared with rhBMP-2/ACS

Suppression of CH4 Emission by Rice Straw Removal and Application of Bio‐Ethanol Production Residue in a Paddy Field in Akita, Japan

To elucidate the effects of rice straw removal and rice straw‐based bio‐ethanol production residue application on rice growth and methane (CH4) emission from a paddy field, a lysimeter experiment with three treatments (application of rice straw after harvesting (the rice‐straw plot); removal of rice straw and the application of bio‐ethanol production residue (the Et‐residue plot); removal of rice straw (the no‐application plot)) was conducted over three years. Though the grain yields in the Et‐residue and no‐application plots tended to be slightly higher than that in the ricestraw plot, there were no significant differences among the plots (530–546 g∙m−2). Suppression of CH4 emission by the treatments was found clearly in the early part of the growing season. The total CH4 emissions during the rice‐growing season (unit: g∙C∙m−2∙period−1) followed the order of the noapplication plot (11.9) < the Et‐residue plot (14.6) < the rice‐straw plot (25.4), and a significant difference was found between the no‐application and rice‐straw plots. Consequently, bio‐ethanol production from rice straw and a following application of its residue to paddy fields is considered to be a promising technology which can obtain new sustainable energy and suppress CH4 emission without any inhibition on rice growth

Controlling Factors of Volatile Organic Compounds in Cloud Water at the Summit of Mt. Fuji in the Free Troposphere during the Summer

2010年から2018年までの7月と8月に富士山頂（標高3,776 m）で大気および雲水を採取して、27種類の人為起源揮発性有機化合物 (AVOCs) （塩素化炭化水素16種、単環芳香族炭化水素8種、二環芳香族炭化水素3種）と6種類の生物起源揮発性有機化合物を分析した。雲水中VOCs （体積加重平均VOCs濃度：2.07 nM、n=159）の約9割はAVOCsであり、主成分はトルエンであった。これは富士山頂における大気中トルエン濃度が高いことを反映していた。雲水中AVOCs濃度は空気塊が大陸南部から輸送されたときに高く、最低濃度を示した海洋由来時の約1.5倍であった。雲水中トルエン濃度は総無機イオンの低下とともに指数関数的に減少した。雲水中クロロホルム、o-キシレン、リモネン濃度は大気中濃度とヘンリー定数から求めた計算値に比べて実測値は数倍高く、ヘンリー則からの予測値以上に濃縮されていた。疎水性が高いVOCsほど雲水に高濃縮されており、自由対流圏における雲水でもHULIS （フミン様物質）のような界面活性物質がVOCsの高濃縮に関与していることが示唆された。At the summit of Mt. Fuji in July and August from 2012 to 2018, 27 kinds of anthropogenic volatile organic compounds (AVOCs) and 6 types of biogenic volatile organic compounds (BVOCs) in the air and in cloud water were determined. AVOCs occupied about 90% of the VOCs in the cloud water (volume-weighted mean VOCs concentration: 2.07 nM, n=159) and the main component was toluene, reflecting its high concentration in the ambient air. The concentration of the AVOCs in the cloud water was high when the airmass was transported from the southern continent and was about 1.5 times higher than that when it came from the ocean. The concentration of toluene in the cloud water decreased exponentially with the increase in the total ion concentration. The concentrations of some VOCs such as chloroform, o-xylene, and limonen in the cloud water were several times higher than their Henry’s law predicted values. Among the chlorinated hydrocarbons, highly hydrophobic chloroform was more concentrated than dichloromethane in the cloud water. Atmospheric surfactants such as HULIS (Humic-like Substances) could affect the enrichment of the VOCs in the cloud water even in the free troposphere