犬の同種腎移植に関する基礎的研究 : 特に免疫抑制剤の使用方法と腎機能、肝機能について

人医界においては慢性腎不全に対する治療方法として，血液透析と腎移植が代表的である。しかし，血液透析は1回4～6時間，週に数回病院内で治療を行なわなければならない。一方，腎移植では，一旦移植腎が機能を開始すると，入院の必要はなく免疫抑制剤の投与以外，通常に近い日常生活を営むことも可能である。　小動物臨床においても高年齢化にともない慢性腎不全症例は増加する傾向にあり，適切な治療の実施が望まれている。このような慢性腎不全の治療方法として犬においても腎移植が効果的かつ経済的であると考えられるが，ヒトのような確実な腎移植方法とくに免疫抑制剤の投与方法については未だに確立されていない。ヒトの腎移植においては，ヒトリンパ球抗原系(human leukocyte antigen，HLA)を検査し主要組織適合性抗原(major histocompatibility complex，MHC)を出来るだけ合致させた移植腎の受給者(recipient)と提供者(donor)を選択している。しかし，犬においてはリンパ球抗原(dog leukocyte antigen，DLA)を検査し，確定することは現在のところ困難であり，犬の腎移植においてはヒトよりもより高度の免疫抑制法の確立が必要である。そこで著者は，recipientと同様にdonorにも移植前に免疫抑制剤を投与するという新しい方法を考案し，犬の腎移植について，腎機能はもちろん肝機能にも影響が少なく長期間生存が可能な免疫抑制剤の適切な投与方法を開発する目的で実験を行なった。1.自家腎移植群ならびに非免疫抑制群　腸骨窩を移植腎の移植床とし，腎動脈・外腸骨動脈吻合，腎静脈・総腸骨静脈吻合ならび尿管・膀胱吻合を行う手術方法が有効であることを確認するために5頭の雑種成犬を用いて自家腎移植を行なった。また，生存期間を比較するための対照群として雑種成犬を無作為に抽出し，2頭を一対とした非免疫抑制腎移植群(10頭)を作成した。　自家腎移植群(第1群)においては，腎機能の指標である血清クレアチニン(Cr)ならびに血液尿素窒素(BUN)値は1週間の観察期間を通じて正常範囲内で推移した。このことから，この移植手術手技が腎臓にほとんど障害を与えない有効な方法であることが確認された。　非免疫抑制群(第2群)での生存日数は，8.7±2.4日(平均±標準偏差)であり，生存期間は雑種成犬を使用した従来の報告とほぼ同様であった。この群では，移植後数日で血清CrならびにBUNの値が上昇したことから移植後短期間で拒絶反応により腎機能が喪失したものと考えられた。2.免疫抑制剤短期間投与群　ここでは，アザチオプリン(azathioprine，Az)，ミゾリビン(mizoribine，Mz)ならびにプレドニゾロン(prednisolone，Pr)の3種の免疫抑制剤を2剤または3剤併用することによって，免疫抑制効果を最大限に利用し，副作用を最小限とする投与方法を確立する目的で実験を行なった。免疫抑制剤はdonorとrecipientの両者に移植5日前から移植前日まで投与し，さらにrecipientには移植後7日目まで投与し，投与期間中の腎臓ならびに肝臓の機能に対する影響について観察した。その後は拒絶反応を誘発する目的で，recipientの免疫抑制剤の投与を中止した。免疫抑制方法は，次の4群に分けて行なった。AzとPrの2剤を投与した群，すなわち移植5日前よりdonorとrecipientの両者にAz 2.5mg/kg，3日前よりPr 1mg/kgをそれぞれ1日1回経口投与し，移植当日からはrecipientにAz，Pr共に1.0mg/kgを7日目まで投与したAz(2.5mg/kg)/Pr群(第3群:10頭)。移植5日前より両者にAz 5.0mg/kgを，3日前よりPr 1.0mg/kgを1日1回経口投与し，移植当日からはrecipientにAz，Pr共に1.0mg/kgを7日目まで投与したAz(5.0mg/kg)/Pr群(第4群:12頭)。MzとPrの2剤を投与した群，すなわち移植5日前よりMz 5.0mg/kg，3日前よりPr 1.0mg/kgをそれぞれ1日1回経口投与し，移植当日からはMz 2.5mg/kg，Pr 1.0mg/kgを7日目まで投与したMz(5.0mg/kg)/Pr群(第5群:10頭)。移植5日前よりMz 5.0mg/kg，3日前からAz 2.0mg/kg，Pr 1.0mg/kgを1日1回毎日経口投与し，移植当日からはMz 2.5mg/kg，Az 1.0mg/kgならびにPr 1.0mg/kgを投与したAz，Mz，Prの3剤投与群(第6群:10頭)である。　第3群と第6群の生存日数はそれぞれ，16.2±4.1日ならびに14.0±2.6日であった。生存日数について，対照群(第2群)に対して第3群と第6群には有意な延長が観察された。しかし，この2群間には有意差は認められなかった。　腎機能では，第3群と第6群では免疫抑制剤の投与期間中に異常所見は認められなかったが，第5群では免疫抑制剤投与中も拒絶反応によると考えられる腎機能の低下が認められた。全群共に免疫抑制剤の投与中止後は数日内に拒絶反応の発現によって腎機能は消失した。　肝機能を示す，血清アラニンアミノトランスフェラーゼ(ALT)ならびにアルカリフォスファターゼ(ALP)値は，AzとPrの2剤を併用した群において，Az，Mz，Prの3剤を併用した群あるいはMz，Prの2剤を併用した群よりも上昇する傾向が観察され，Azを高用量使用した第4群においては重度の肝障害が観察された。AzとPrの2剤の組み合わせでは，長期間投与に伴って肝障害を起こすことが考えられた。　以上の結果より，腎移植後，長期間免疫抑制剤を投与する最も有効な方法は，Az，Mz，Prの3剤投与法(第6群)であることが示唆された。　そこで，この免疫抑制方法が従来のAzとPrの2剤を投与する方法に比較してより有効な方法であることを確認する目的で，Az，Mz，Prの3剤投与法を雑種成犬ならびにビークル成犬に腎移植後長期間実施しその有用性を確認した。3:免疫抑制剤長期間投与群　第6群でのAz，Mz，Prの3剤投与方法を実験犬の死亡時まで，雑種成犬8頭(第7群)とビーグル成犬8頭(第8群)に実施した。また，ビーグル成犬群には著者が開発した急性拒絶反応の診断基準(1:血清Cr値が1日で0.5mg/dl以上上昇したこと，あるいは2:血清Cr値が2.0mg/dl以上に上昇したこと)を適用して治療(デキサメサゾン1.0mg/kg，1日1回3日連続静脈内投与)し長期生存に努めた。生存日数は，雑種成犬群ならびにビーグル成犬群それぞれ44.5±20.5日ならびに142.5±111.4日であり，両群共に生存日数の有意な延長が認められた。　腎機能は，両群共に免疫抑制下で正常に保たれていた。しかし，一旦拒絶反応が発現するとCrならびにBUNは上昇した。このような場合ビーグル成犬群には，拒絶反応の基準に準じて急性拒絶反応の治療を行なった結果，処置後2～3日で治療前に回復し効果が認められた。また，ビーグル成犬群に行なった静脈性腎盂造影ならびに内因性クレアチニンクリアランス(CCr)では，急性拒絶反時には腎機能が低下し，治療後回復することが分かった。なお，拒絶反応後の血清Cr値は数日で回復するものの，CCr値はさらに数日遅れて正常に回復した。このことは，腎機能を判断するうえで，血清Cr値よりもCCr値は，より的確に腎機能を把握できるものと考えられた。ビークル成犬群において長期間生存した例においてCrは正常範囲内で推移しているにもかかわらず，BUNの中程度の上昇がみられた。このことは，長期間生存例においては何らかの腎機能低下あるいはその前駆症状を示していることが示唆された。腎臓の組織学的検査では，糸球体内微小血栓を含むリンパ球と形質細胞を主体とする細胞介在性の急性拒絶反応ならびに長期間生存例では糸球体硬化を主病変とする慢性拒絶反応によるものと思われる所見が観察された。肝機能においては，ALP，ALTならびに，γ-グルタミールトランスフェラーゼ(GGT)を測定した結果，移植後一過性にこれらの酵素値は上昇し，その後徐々に低下する傾向にあった。長期間生存例ではこれらの値はほぼ正常値に回復した。また，ビーグル成犬群(第8群)で行なったALPの電気泳動法では，免疫抑制剤投与初期に認められたALPの上昇はほとんどステロイド誘発性であることが確認された。肝臓の組織学的検査においては，ステロイド性肝症と考えられる種々の程度の肝細胞の空胞化が観察された。しかしながら，その他には免疫抑制剤の副作用と考えられる異常所見は観察されなかった。とくにビーグル成犬群では手術中に肝生検を実施し，剖検時の所見と比較した。その結果，剖検時には数例にステロイド性肝症が観察されたが，免疫抑制剤の投与期間あるいは免疫抑制剤の総投与量と肝臓の病変の程度には関係は認められなかった。　以上の結果より，ステロイド性肝症に関しては，今後Pr減量を含む長期間投与方法を検討する必要性が示唆されたが，著者の行なったMz，Az，Prの3剤をdonorとrecipientの両者に移植の5日前より前処置として投与する免疫抑制方法は数カ月から半年間は移植腎の機能を維持でき，犬における慢性腎不全の治療として腎移植が臨床的に応用可能であることが確認された。Chronic end-stage renal diseases are common in dogs. Treatments for end-stage renal failure, such as hemodyalysis and continuous ambulatory peritoneal dialysis, have been reported in veterinary medicine. However, there is no effective procedure for maintaining long-term renal function. The high success rate of kidney transplantation in humans gives patients having end-stage renal diseases a good quality of life. There have been many investigations and clinical trials of kidney transplantation for the treatment of renal failure in dogs. There are no effective methods for resolving complications from rejection of transplanted kidneys at this point. In this study, mizoribine (4-carbamoyl-1-β-D ribofuranosylimidazolium 5-olate), azathioprine, and prednisolone were the immunosuppressive drugs used. Mizoribine is a nucleoside antibiotic from the culture filtrate of Eupenicillium brefeldianum. The immunosuppressive mechanism is the inhibition of ribonucleic acid and deoxyribonucleic acid synthesis causing lymphocyte toxicities. Mizoribine also has less hepatic toxicity than azathioprine. Cyclosporine has been widely used as an immunosuppressive drug in human organ transplantations. However, renal toxicity has been reported in long-term survival patients and it is the most expensive immunosuppressive drug for canine renal transplantation when used in effective immunosuppressive dosages. Mizoribine is a relatively inexpensive drug and its toxicity is lessened when used with combinations of other immunosuppressive drugs. Therefore, it is a better choice. The purpose of this study is to determine the efficacy of combination immunosuppressive protocols with pre-treatments for canine kidney transplantation to increase survival times and decrease side-effects, especially those affecting the liver. 1: The first experiment; Groups of auto kidney transplantation and kidney transplantation without immunosuppression (control) The body weight of recipients (R) and donors (D) were paired as equally as possible in each group. There was no significant statistical difference in body weight between each group. The dogs were also paired on the basis of direct cross-matches (recipients\u27 plasma against donors\u27 RBCs and vice versa). Commercial dry food and water were provided. Anesthesia was induced intravenously with thiamylal sodium (25 mg / kg) and maintained with halothane in combination with oxygen. Recipient and donor dogs were treated with oral antibiotics (amoxiciline 20 mg / kg BID) 5 days prior to the operation, intravenous ampicilline ( 25 mg / kg TID ) for 3 days postoperatively, and then switched to the oral protocol used before surgery at the same dosage until the end of study. Lactated Ringer\u27s solution (2 mg / kg / hour) was transfused intravenously during surgery and 1 mg / kg furosemide was injected intravenously after the re-perfusion of renal vessels. The donors\u27 kidney was flushed with 50 ml of 5 % glucose lactated Ringer\u27s solution (room temperature) and another 50 ml of the same solution cooled to 4℃. The removed kidney was kept in ice cold, 5 % glucose lactated Ringer\u27s solution until renal vascular anastomosis. The donor\u27s kidney was placed in the recipients\u27 lower abdominal cavity. End-to-end, renal-to-common iliac artery and end-to-side, renal-to-common iliac vein anastomoses were performed. After anastomosis, the ureter and urinary bladder were anastomosed with Murry\u27s method. The recipients\u27 own renal artery, vein, and ureter were ligated. For 3 days after transplant surgery, recipients were not given any food or water, but were given 60 ml / kg / day of 5 % glucose lactated Ringer\u27s solution intravenously. On the fourth day after surgery, feeding was started gradually. The clinical status of the dogs were observed daily and blood sampling were performed prior to feeding. Blood was obtained for analysis every day. Complete blood counts, serum creatinine concentration, BUN, serum alanine aminotransferase activity (ALT), and alkaline phosphatase activity (ALP) were analyzed until end of the study. The dogs that became severely azotemic were euthanatized. There were no significant changes of serum creatinine and BUN during one week of observation period in group 1. Therefore, this procedure of kidney transplantation is sufficient method for canine kidney transplantation. The survival time of group 2 was 8.7 ± 2.4 days. This data is similar to other reported control data of mongrel dogs. Therefore, there is no problem to use this control data to compare to other immunosuppressive groups. In this group, serum creatinine and BUN levels were increased a few days after surgery because the loss of renal function occured relatively soon after transplantation due to acute graft rejection. Based upon the first experiment, this surgical and postoperative procedures were adequate to perform the safe canine kidney transplantation and data of the control group was sufficient. Therefore, the second experiment which was determined the best immunosuppressive protocol without significant side-effects was planed for serial combination immunosuppressive protocols.2: The second experiment;Groups of combination immunosuppression Beagle and mixed-breed dogs were obtained. The dogs were randomly divided into 4 groups and each received a different immunosuppressive protocol. The body weight of recipients (R) and donors (D) were paired as equally as possible in each group. There was no significant statistical difference in body weight between each group. The dogs were also paired on the basis of direct cross-matches (recipients\u27 plasma against donors\u27 RBCs and vice versa). Commercial dry food and water were provided. The surgical procedure of kidney transplantation was done same as the first experiment. Four groups of transplantations were performed depending upon immunosuppressive drugs and dosages. All immunosuppressive protocols were discontinued on the eighth day after transplantation.Az(2.5) & Pr group: Daily oral administration of azathiopurine [Imuran, Burroughs Wellcome Co., NJ, U.S.A.] (dosage, 2.5 mg / kg of body weight once a day) was started at 5 days prior to transplantation. Prednisolone (dosage, 1.0 mg / kg of body weight once a day) was started 2 days prior to transplantation. On the day of transplantation, azathiopurine was reduced to 1.0 mg / kg once a day. Both drugs were given until the seventh day after transplantation.Az(5.0) & Pr group: Daily azathioprine (dosage, 5 mg / kg once a day) was administered prior to surgery and reduced to 1.0 mg / kg once a day after surgery. Prednisolone was administrated according to the method used for group receiving Az and Pr.Mi(5.0) & Pr group: Mizoribine [Bredenine, Toyo Jozo Co. Ltd., Tokyo, Japan] (dosage, 5 mg / kg of body weight once a day) was administered 5 days prior to surgery and reduced to 2.5 mg / kg on the day of transplantation.Mi & Az & Pr group: Mizoribine and prednisolone were administrated according to the same method used for the Mi(5.0) & Pr group. Azathioprine (dosage, 2.0 mg / kg once a day) was started 2 days prior to surgery and reduced to 1.0 mg/kg on the day of transplantation. These immunosuppressive drugs were administrated daily at least 60 minutes prior to feeding. The clinical status of the dogs were observed daily and drug administration and blood sampling were performed prior to feeding. Blood was obtained for analysis every day. Complete blood counts, serum creatinine concentration, BUN, serum alanine aminotransferase activity (ALT), and alkaline phosphatase activity (ALP) were analyzed until end of the study. The dogs that became severely azotemic were euthanatized. Statistical analysis was performed using Student\u27s paired and unpaired t-tests, as appropriate. For all statistical analyses, a P value of 0.05 or less was considered significant. The mean survival times of each group were analyzed for statistical differences using Student\u27s unpaired t-test. Both the Az(2.5) & Pr group (mean survival time, 16.2 ± 2.4 days) and the Mi & Az & Pr group (mean survival time, 14.0 ± 2.6 days) had significantly longer survival times compared to the control group (mean survival time, 8.7 ± 2.4 days ; P<0.01). There was no significant differences in survival time between these groups. There were no significant change in clinical signs during pretreatment in all dogs. Feeding began on the fourth day after transplantation. At that time, there was no significant change of appetite in any dog. As renal function decreased, anorexia, vomiting and diarrhea became worse. Severity and duration of these clinical signs depended upon the degree and duration of renal dysfunction. There were mild decreased packed cell volumes and red blood cell counts in all groups because of daily blood sampling. There were mild increased white blood cell counts for 1 to 3 days after transplantation in all groups. There were no severe decreased white blood cell counts (less than 4000 / μl) during survival periods in any dogs. The mean creatinine level of the control group gradually increased after transplantation. There were no significant changes in the Az(2.0) & Pr and Mi & Az & Pr groups during the 7 days of immunosuppressive treatments. In the Az(5.0) & Pr group, there were fewer increased mean creatinine levels at time of death than in other groups even though the group\u27s mean survival time was the shortest. After discontinuation of immunosuppressive treatment, creatinine levels gradually increased in the Az(2.0) & Pr and Mi & Az & Pr groups. Changes in BUN levels in each group were mostly the same as changes in creatinine levels. There were significantly increased mean activities of alkaline phosphatase (ALP) in the control, Az(2.5) & Pr, and Az(5.0) & Pr groups after transplantation compared to their levels at 5 days prior to kidney transplantation. The Az(2.0) & Pr and Az(5.0) & Pr groups had significantly increased mean ALP activities at the day of or 1 day after transplantation and remained at significantly high levels in most cases until the end of the study. There was also significantly increased mean activity of alanine transaminase (ALT) in the control, Az (2.0) & Pr and Az (5.0) & Pr groups. The highest activity of ALT was in the Az(5.0) & Pr group at the day of transplantation. There were fewer changes in ALP and ALT levels in groups receiving mizoribine. The Az(5.0) & Pr group had the shortest mean survival time, which was same as the control group. Three dogs out of 6 at the day of death had serum creatinine levels less than 2 mg / dl and BUN levels less than 50 mg / dl in the Az(5.0) & Pr group. However, there were significantly high ALT and ALP activities in the same group. ALT activity was highest at the day of transplantation and gradually decreased. Significant elevations of ALT and ALP in the Az(5.0) & Pr group appeared to be caused by the hepatic side-effects of azathioprine and prednisolone even though the rejection reactions of transplanted kidneys were suppressed. The Mi(5.0) & Pr group had the second shortest survival time which was no different from that of the control group. Mean activities of ALT and ALP gradually increased during the 7 days of immunosuppression in this group. The protocol and dosage of mizoribine appeared to have inadequate immunosuppressive effects and was not effective for renal transplantation. Mizoribine itself might not be sufficiently immunosuppressive, as has been reported. However, this group had the least changes in ALT and ALP. The Az(2.5) & Pr and Mi & Az & Pr groups had significantly longer mean survival times than the control group. However, there was no difference in mean survival time between these groups. There were minimal changes in creatinine (less than 2 mg / dl) and BUN levels (less than 50 mg/ dl)in the Az(2.5) & Pr and Mi & Az & Pr groups during the 7 days of immunosuppressive treatment. After discontinuing immunosuppression, both levels increased by the fourth day in the Az(2.5) & Pr group and by the second day in the Mi & Az & Pr group. ALT activities were increased in both groups and there was a decreased tendency towards ALT activity in the Mi & Az & Pr group during the immunosuppressive period. ALT levels decreased by the eleventh day in the Az(2.5) & Pr group. The Az(2.5) & Pr group had ALP levels that were two times higher than the Mi & Az & Pr group. ALP activity remained at more than 200 IU/l in all dogs during the entire study. There were significant differences in ALP activity levels between before and after the administration of prednisolone. This might be explained by prednisolone\u27s ability to produce ALP in bile duct epithelial cells. Our study revealed that azathiopurine and prednisolone were relatively adequate when used for short-term immunosuppression, but it appears that this protocol may cause more significant liver damage when it is used for long-term immunosuppression. This study revealed that a combination of mizoribine, azathiopurine, and prednisolone with pretreatment of recipients and donors for immunosuppression (the Mi & Az & Pr group) had fewer hepatic side-effects and was a relatively effective immunosuppressant treatment method for canine kidney transplantation. Further study is needed to prove that survival is prolonged in dogs receiving kidney transplantations with this immunosuppressive protocol. The third experiment was planed to prove that this Mi & Az & Pr immunosuppressive protocol is sufficient for the long-term canine kidney transplantation.3: The third experiment;Groups of long-term immunosuppression after kidney transplantation. Dogs were divided into two groups: mongrel and beagle. Males and females were represented in both groups. The mean body weight was 13.4 ± 0.8 kg, ranging from 12.5 to 14.4 kg in the mongrel group and 11.5 ± 2.7 kg, ranging from 8.5 to 14.5 kg in the beagle group. The body weight of recipients (Rec) and donors (Don) were paired as equally as possible (Table 1). The dogs were also paired on the basis of direct cross matches (Recs\u27 plasma against Dons\u27 red blood cells and vice versa). Commercial dry food and water were provided for their needs. The kidney transplantation procedure was done as previously described. Both recipients and donors in mongrel and beagle groups were immunosuppressed by the same protocol. Mizoribine was administered a 5.0 mg / kg body weight once a day at 5 days prior to the surgery until the day of surgical. Three days prior to surgery, Azathiopurine and Prednisolone were also administered a 2.0 mg / kg and 1.0 mg / kg of body weight respectively once a day until surgery. From the day of surgery, Mizoribine a 2.5 mg/kg, Azathiopurine a 1.0 mg/kg and Prednisolone a 1.0 mg/kg of body weight once a day were administered until the end of the study. These immunosuppressive drugs were administered orally at least 60 minuets prior to feeding everyday. Everyday, the clinical status of the dogs was observed and serum biochemical analyses were performed before feeding until the fourteenth day after surgery. The serum biochemical analyses were performed every other day until day 28 and every third day until day 56 and two times a week until the end of study. The complete blood count and serum creatinine concentration, BUN, serum alanine aminotransferase activity, and alkaline phosphatase activity were analyzed until the end of study. Dogs that became severely azotemic were euthanatized. The criteria for acute rejection crisis was based upon changes of serum creatinine levels. We established two criteria for rejection: 1) when a change in serum creatinine levels within 24 hours was greater than 0.5 mg/dl; and 2) when serum creatinine level reached greater than 2 mg/dl regardless of the rate of increase before that day. Treatment for acute rejection crisis based on these criteria was performed using dexamethasone sodium phosphate only for the beagle group. We administrated the dexamethasone sodium phosphate a 1 mg/kg of body weight once a day intravenously for three days from the day when we decided the rejection occurred. Hepatic biopsy was done during transplantation in the beagle group, because of comparison of hepatic changes after immunosuppression. The complete necropsy was done at the end of study. All tissue sections of kidney and liver were fixed in 10% neutral buffered formalin, embedded in paraffin, processed routinely, cut in 6-μm sections and stained with Hematoxylin-eosin (HE), Periodic acid schiff (PAS), Phosphotungstic acid-hematoxylin (PTAH) and Masson\u27s trichrome stains. Statistical analysis was performed using Student\u27s paired and unpaired t-tests as appropriate. For all statistical analyses, a P value of 0.05 or less was considered significant. The survival time for allographt recipients of mongrel dogs was 44 ± 20.5 days (ranging from 24 to 65 days) which is significantly longer than our control group (7, 7, 7, 8, 10, 13 : 8.7 ± 2.4 days); (P<0.05) and beagle dogs was 142.5 ± 111.4 days (ranging from 48 to 277 days) which is also significantly longer than control group (11, 12, 13, 13, 14, 15, 15, 21 : 14.3 ± 1.1 days); (P<0.05 : data from Jpn J Transplant 1982: 17 (suppl): 617-627). All dogs recovered from transplant surgery without complication. They accepted food when they were fed on the day 4 after surgery. One dog from the mongrel group had vomitions and bloody diarrhea at day 26 after transplantation. However, these clinical signs were resolved within eight days after reducing the maintenance dosage of azathioprine by 50%. When they were having rejection episodes, they usually seemed depressed and exhibited decreased appetite. These clinical signs were resolved gradually when serum creatinine levels were decreased with steroid therapy. Red blood cell counts were gradually decreased in

<ORIGINAL>A prospective randomized clinical study on the efficacy of CO_2 lasers on initial stage endodontics

The purpose of this study was to evaluate the clinical efficacy of the CO_2 laser in a prospective randomized trial. A total of 112 teeth in 112 patients, previously treated pulpectomy procedures were gathered and randomly divided into two groups composed of 56. Irradiation was performed on one group and non-irradiation forms of treatment were performed on the other group. On the first group of teeth, root canal enlargement was done and followed by exposure of the canal to a CO_2 laser light (5W, 200msec) using 3 cycles each at a rate of 15 seconds per cycle. The second group was not exposed to laser light following root canal enlargement. The laser was applied on the root canal for a controlled period of time. On the day following pulpectomy, a statistically significant (p < 0.05) fewer number of patients observed pain in the irradiation group compared to the non-irradiation group. The treatment times and the total treatment days in the irradiation group are shorter than in the non-irradiation group (p < 0.05). Multivariate analysis showed that the laser treatment was significantly associated with treatment times. This study shows that the degree of oral pain was greatly reduced in patients who underwent laser irradiation as compared to these who did not. Our study suggests that the use of laser treatment provide significant short-term improvement compared to conventional forms of treatment performed during pulpectomy

Broadly Tunable Sub-terahertz Emission from Internal Branches of the Current-voltage Characteristics of Superconducting Bi2Sr2CaCu2O8+d Single Crystals

Continuous, coherent sub-terahertz radiation arises when a dc voltage is applied across a stack of the many intrinsic Josephson junctions in a Bi2Sr2CaCu2O8+d single crystal. The active junctions produce an equal number of I-V characteristic branches. Each branch radiates at a slightly tunable frequency obeying the ac Josephson relation. The overall output is broadly tunable and nearly independent of heating effects and internal cavity frequencies. Amplification by a surrounding external cavity to allow for the development of a useful high-power source is proposed.Comment: 4 pages, 4 figures, accepted for publication in PR

Generation of electromagnetic waves from 0.3 to 1.6 terahertz with a high-T-c superconducting Bi2Sr2CaCu2O8+delta intrinsic Josephson junction emitter

To obtain higher power P and frequency f emissions from the intrinsic Josephson junctions in a high-T-c superconducting Bi2Sr2CaCu2O8+delta single crystal, we embedded a rectangular stand-alone mesa of that material in a sandwich structure to allow for efficient heat exhaust. By varying the current-voltage (I-V) bias conditions and the bath temperature T-b, f is tunable from 0.3 to 1.6 THz. The maximum P of a few tens of mu W, an order of magnitude greater than from previous devices, was found at T-b similar to 55K on an inner I-V branch at the TM(1,0) cavity resonance mode frequency. The highest f of 1.6 THz was found at T-b = 10K on an inner I-V branch, but away from cavity resonance frequencies. A possible explanation is presented

Longitudinal strain of right ventricular free wall by 2-dimensional speckle-tracking echocardiography is useful for detecting pulmonary hypertension

Aims Echocardiography is widely used for screening pulmonary hypertension (PH). More recently developed two-dimensional speckle-tracking echocardiography (2D-STE) can assess regional deformation of the myocardium and is useful for detecting left ventricular dysfunction. However, its usefulness to assess right ventricular (RV) dysfunction is not clear. Therefore, the aim of this study was to investigate the ability of peak systolic strain (PSS) and post-systolic strain index (PSI) at the RV free wall determined by 2D-STE to detect PH. Main methods Thirty-six images (27 images from PH patients, nine from patients with connective tissue disease without PH) obtained by 2D-STE were analysed. We investigated the relationship between RV hemodynamics measured by right heart catheterization and PSS, PSI and other echocardiographic parameters reflecting RV overload including RV end-diastolic diameter (RVDd) and tricuspid valve regurgitant pressure gradient (TRPG). Key findings PSS, PSI, RVDd and TRPG were all correlated with mean pulmonary arterial pressure (MPAP) and pulmonary vascular resistance (PVR). Furthermore, when PSS and MPAP were measured twice, the change in PSS was correlated with the change in MPAP (r = 0.633, p = 0.037). Multivariate logistic regression analysis identified PSS as the only independent factor associated with MPAP ? 35 mm Hg [odds ratio (OR), 1.616; 95% confidence interval (CI) 1.017-2.567; p = 0.042] and PVR ? 400 dyn・s・cm- 5(OR, 1.804; 95% CI 1.131-2.877; p = 0.013). Furthermore, the optimal PSS cut-off value to detect an elevated MPAP and PVR was - 20.75%, based on receiver operating characteristic curve analysis. Significance PSS of the RV free wall might serve as a useful non-invasive indicator of PH

Bousfield Classes and Ohkawa's Theorem

This volume originated in the workshop held at Nagoya University, August 28–30, 2015, focusing on the surprising and mysterious Ohkawa's theorem: the Bousfield classes in the stable homotopy category SH form a set. An inspiring, extensive mathematical story can be narrated starting with Ohkawa's theorem, evolving naturally with a chain of motivational questions: Ohkawa's theorem states that the Bousfield classes of the stable homotopy category SH surprisingly forms a set, which is still very mysterious. Are there any toy models where analogous Bousfield classes form a set with a clear meaning? The fundamental theorem of Hopkins, Neeman, Thomason, and others states that the analogue of the Bousfield classes in the derived category of quasi-coherent sheaves Dqc(X) form a set with a clear algebro-geometric description. However, Hopkins was actually motivated not by Ohkawa's theorem but by his own theorem with Smith in the triangulated subcategory SHc, consisting of compact objects in SH. Now the following questions naturally occur: (1) Having theorems of Ohkawa and Hopkins-Smith in SH, are there analogues for the Morel-Voevodsky A1-stable homotopy category SH(k), which subsumes SH when k is a subfield of C?, (2) Was it not natural for Hopkins to have considered Dqc(X)c instead of Dqc(X)? However, whereas there is a conceptually simple algebro-geometrical interpretation Dqc(X)c = Dperf(X), it is its close relative Dbcoh(X) that traditionally, ever since Oka and Cartan, has been intensively studied because of its rich geometric and physical information. This book contains developments for the rest of the story and much more, including the chromatics homotopy theory, which the Hopkins–Smith theorem is based upon, and applications of Lurie's higher algebra, all by distinguished contributors