Massive gene losses in Asian cultivated rice unveiled by comparative genome analysis

<p>Abstract</p> <p>Background</p> <p>Rice is one of the most important food crops in the world. With increasing world demand for food crops, there is an urgent need to develop new cultivars that have enhanced performance with regard to yield, disease resistance, and so on. Wild rice is expected to provide useful genetic resources that could improve the present cultivated species. However, the quantity and quality of these unexplored resources remain unclear. Recent accumulation of the genomic information of both cultivated and wild rice species allows for their comparison at the molecular level. Here, we compared the genome sequence of <it>Oryza sativa </it>ssp. <it>japonica </it>with sets of bacterial artificial chromosome end sequences (BESs) from two wild rice species, <it>O. rufipogon </it>and <it>O. nivara</it>, and an African rice species, <it>O. glaberrima</it>.</p> <p>Results</p> <p>We found that about four to five percent of the BESs of the two wild rice species and about seven percent of the African rice could not be mapped to the <it>japonica </it>genome, suggesting that a substantial number of genes have been lost in the <it>japonica </it>rice lineage; however, their close relatives still possess their counterpart genes. We estimated that during evolution, <it>O. sativa </it>has lost at least one thousand genes that are still preserved in the genomes of the other species. In addition, our BLASTX searches against the non-redundant protein sequence database showed that disease resistance-related proteins were significantly overrepresented in the close relative-specific genomic portions. In total, 235 unmapped BESs of the three relatives matched 83 non-redundant proteins that contained a disease resistance protein domain, most of which corresponded to an NBS-LRR domain.</p> <p>Conclusion</p> <p>We found that the <it>O. sativa </it>lineage appears to have recently experienced massive gene losses following divergence from its wild ancestor. Our results imply that the domestication process accelerated large-scale genomic deletions in the lineage of Asian cultivated rice and that the close relatives of cultivated rice have the potential to restore the lost traits.</p

Suzaku Results on the Obscured Low-Luminosity Active Galactic Nucleus in NGC 4258

In 2006 June, the obscured low luminosity active galactic nucleus in the nearby Seyfert 1.9 galaxy NGC 4258 was observed with Suzaku for ~ 100 ks. Utilizing the XIS and the HXD, the nucleus emission was detected over 2 to 40 keV range, with an unabsorbed 2--10 keV luminosity of 8 x 10 40 erg / s, and varied by a factor of ~ 2 during the observation. Its 2--40 keV spectrum is reproduced by a single power law with photon index of ~ 2.0, absorbed by an equivalent hydrogen column of ~ 1.0 x 10 23 cm2. The spectrum within 4' of the nucleus required also a softer thin-thermal emission, as well as an intermediate hardness component attributable to integrated point sources. A weak neutral Fe-Kalpha florescence line was detected at an equivalent width of ~ 40 eV. The cold reflection component was not required by the data, with the reflector solid angle Omega seen from the nucleus constrained as Omega / 2 pi < 0.3 assuming a general case of 60 deg inclination. The results suggest that the cold reflecting material around the nucleus is localized along our line of sight, rather than forming a thick torus.Comment: PASJ, NGC4258, Suzaku, 12 pages, 11 figure

Discovery of a bright transient ultraluminous X-ray source Suzaku J1305-4931 in NGC 4945

This paper reports the discovery of a bright X-ray transient source, Suzaku J1305-4913, in the south-west arm of the nearby Seyfert II galaxy NGC 4945. It was detected at a 0.5 -- 10 keV flux of $2.2 \times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ during the Suzaku observation conducted on 2006 January 15 -- 17, but was undetectable in a shorter observation on 2005 August 22 --23, with an upper limit of $1.7 \times 10^{-14}$ erg cm$^{-2}$ s$^{-1}$ (90% confidence level). At a distance of 3.7 Mpc, the bolometric luminosity of the source becomes $L_{\rm bol} = 4.4 \times 10^{39} \alpha$ erg s$^{-1}$, where $\alpha = (\cos 60^\circ / \cos i)$ and $i$ is the disk inclination. Therefore, the source is classified into so-called ultraluminous X-ray sources (ULXs). The time-averaged X-ray spectrum of the source is described by a multi-color disk model, with the innermost accretion disk temperature of $T_{\rm in} = 1.69_{-0.05}^{+0.06}$ keV. During the 2006 January observation, it varied by a factor of 2 in intensity, following a clear correlation of $L_{\rm bol} \propto T_{\rm in}^4$. It is inferred that the innermost disk radius $R_{\rm in}$ stayed constant at $R_{\rm in} = 79_{-3.9}^{+4.0} \alpha^{1/2}$ km, suggesting the presence of a standard accretion disk. Relating $R_{\rm in}$ with the last stable orbit around a non-rotating black hole yields a rather low black hole mass, $\sim 9 \alpha^{1/2}$ solar masses, which would imply that the source is shining at a luminosity of $\sim3 \alpha^{1/2}$ times the Eddington limit. These results can be better interpreted by invoking sub-Eddington emission from a rapidly spinning black hole with a mass of 20 -- 130 solar masses.Comment: 21 pages, 10 figures, Accepted for PASJ 2nd Suzaku special issu

Dual Role of Superoxide Dismutase 2 Induced in Activated Microglia: OXIDATIVE STRESS TOLERANCE AND CONVERGENCE OF INFLAMMATORY RESPONSES

Microglia are activated quickly in response to external pathogens or cell debris and clear these substances via the inflammatory response. However, excessive activation of microglia can be harmful to host cells due to the increased production of reactive oxygen species and proinflammatory cytokines. Superoxide dismutase 2 (SOD2) is reportedly induced under various inflammatory conditions in the central nervous system. We herein demonstrated that activated microglia strongly express SOD2 and examined the role of SOD2, focusing on regulation of the microglial activity and the susceptibility of microglia to oxidative stress. When rat primary microglia were treated with LPS, poly(I:C), peptidoglycan, or CpG oligodeoxynucleotide, respectively, the mRNA and protein levels of SOD2 largely increased. However, an increased expression of SOD2 was not detected in the primary neurons or astrocytes, indicating that SOD2 is specifically induced in microglia under inflammatory conditions. The activated microglia showed high tolerance to oxidative stress, whereas SOD2 knockdown conferred vulnerability to oxidative stress. Interestingly, the production of proinflammatory cytokines was increased in the activated microglia treated with SOD2 siRNA compared with that observed in the control siRNA-treated cells. Pretreatment with NADPH oxidase inhibitors, diphenylene iodonium and apocynin, decreased in not only reactive oxygen species generation but also the proinflammatory cytokine expression. Notably, SOD2 knockdown largely potentiated the nuclear factor κB activity in the activated microglia. Taken together, increased SOD2 conferred tolerance to oxidative stress in the microglia and decreased proinflammatory cytokine production by attenuating the nuclear factor κB activity. Therefore, SOD2 might regulate neuroinflammation by controlling the microglial activities.This work was supported in part by KAKENHI Grants 26740024, 30291149, and 22310041 from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (to Y. I., K. I., and T. Y.); a grant from the Fujii Foundation (to Y. I.); and a grant from the Hiroshima University Education and Research Support Foundation (to Y. I.)

Evaluation of Apoptotic Cells Induced by Ultraviolet Light B Radiation in Epidermal Sheets Stained by the TUNEL Technique

Two major components of epidermal cells, keratinocytes and Langerhans cells, are injured by ultraviolet light B radiation, resulting in sunburn cell (apoptotic cell) formation, impaired function, and a reduced number of Langerhans cells. Quantitative analysis of Langerhans cell damage is usually performed using epidermal sheets, whereas that of keratinocytes has been performed by counting the number of sunburn cells in vertical tissue sections. In this study we assessed the influences of ultraviolet light B radiation on epidermal cells by apoptotic cell formation, using murine epidermal sheets stained by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique. Ten to 75 mJ per cm2 of ultraviolet light B radiation induced apoptotic cells in abdominal skin of C3H mice. The cells were induced in 6 h after 50 mJ per cm2 of ultraviolet light B irradiation with the peak in number in 24 h, 18.8 ± 5.0 per mm2 and 97.7 ± 7.4 per mm2, respectively. One week later, the apoptotic cells were not visualized. As C3H/He, BALB/C, and C57BL/6 mice showed almost the same frequency of apoptosis in epidermal sheets from 50 mJ per cm2 ultraviolet light B-irradiated skin, the induction of the cells by ultraviolet light B radiation did not depend on the genetic trait of the mouse. Xeroderma pigmentosum type A gene-deficient mice, however, showed a greater induction of apoptotic cells (216.9 ± 25.2 per mm2) by ultraviolet light B radiation than xeroderma pigmentosum type A wild-type mice (89.5 ± 13.6 per mm2) and conventional mice. Pretreatment with a SPF 60 sunscreen agent was quite effective in reducing the induction of apoptotic cells. Using confocal laser scanning microscopy and double staining, 1.5 ± 2.7% of apoptotic cells were Ia-positive cells in 24 h after 50 mJ per cm2 of ultraviolet light B radiation. Apoptotic Ia-positive cells were not observed 48 h after the radiation. On the other hand, no apoptotic dendritic epidermal T cells were observed in up to 75 mJ per cm2 of ultraviolet light B radiated skin. Thus, nearly all apoptotic cells were keratinocytes, and Langerhans cells and dendritic epidermal T cells appeared resistant to ultraviolet light B-induced apoptosis. Compared with the assessment in vertical tissue sections, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique with epidermal sheets appeared to be a more physiologically relevant method for quantitative evaluation of apoptotic epidermal cells induced by ultraviolet light B radiation

耐熱性ウェルシュ菌 (Clostridium perfringens) に関する研究 : 健康人におけるその分布および血清学的型別とそれに起因する食中毒について

「ヒト」のウェルシュ菌食中毒を細菌学的に証明し、その原因菌を決定するにあたって、解明しておかねばならない前提となる基礎的事項について、一連の調査研究を実施し、本菌に起因する食中毒の実験室診断のための細菌学的、血清学的基礎資料を得ることができた。以上実験目的、方法および結果について項を追って概要を述べる。　1．健康人における耐熱性ウェルシュ菌の分布と排菌の推移　ウェルシュ菌に起因する食中毒を論じるに当って、まず当面する問題は、細菌分類学上本菌種に属する菌が食品をはじめ広く自然界に分布しているばかりでなく、常に「ヒト」の重要な腸内常在菌の一種として存在するという真実であろう。云うまでもなく、腸管常在性ウェルシュ菌には腸炎起病性はないとされていたが、それらの存在がウェルシュ菌食中毒の原因決定に多大の混乱と困難を招来してきた。　1957年にはじめてHobbsらがウェルシュ菌食中毒の菌学、疫学を確立した報告のなかで、「ヒト」に腸炎起病性を有するウェルシュ菌は、患者ふん便中では100℃1～5時間の加熱に耐える芽胞を形成している“いわゆる耐熱性ウェルシュ菌”（以下、耐ウ菌と略す）であることを指摘している。この報告が契機となり諸外国ならびに我が国においても数多くの本菌食中毒例が報告されるようになったが、耐ウ菌の生態、とくに健康人の排菌をめぐって諸報告に一致をみないために、赤痢菌やサルモネラ菌等の代表的腸管病原菌のごとく、耐ウ菌の存在が直裁に腸炎の原因であると結論できるか否かの問題が未解決なまま残されてきた。これまでの諸報告を総合していえることは、健康者の耐ウ菌検出率は、調査地域、年齢、居住環境の違いに左右されるとはいえ、5.2～62.0%と広い範囲を示している。こうした成績は本菌食中毒の菌学的決定に大きな支障となってきた。ここで、食中毒推定の一つの重要な根拠としてあげられるのは、すでにHobbsらが指摘したように、本菌食中毒発生地域の健康者の耐ウ菌正常検出率の正確な把握であろう。つまり、Hobbsらが細菌学的に耐ウ菌食中毒を決定する際に不可欠な条件として、食中毒が発生した地域に在住している健康人ふん便からの耐ウ菌検出率を上廻る高率な耐ウ菌の検出が患者ふん便に認められなければならないと指摘している点が第一に重視されなければならない。　以上の理由から、一連の調査の第一段階として、1966～1968年の3ヵ年間にわたって、都市環境に生活している健康人の耐ウ菌保有率を検討した。調査対象とした健康人は、1～3才の乳幼児43名、6～11才の小学校児童1,088名、15～17才の高等学校生徒350名、20～50才の成人145名および60～80才の老人65名の5つの年齢層からなる計1,688名である。健康人から採取されたふん便は、チオグリコレード培地に接種後100℃で60分間加熱し、冷却後37℃で24～48時間培養したのち、その２白金耳を5%卵黄加CW寒天平板に塗沫し、嫌気培養を行い、出現した疑わしい集落を釣菌し、その生物学的諸性状を調べて型のごとく同定した。その結果、調査対象1,688名中236名（14.0%）が耐ウ菌陽性であることが判明した。これを年齢別にみると、その検出率は1～3才の乳幼児では48名中12名（25.0%）、6～11才の学童では1,080名中139名（12.9%）、15～17才の高校生では350名中40名（11.4%）、20～50才の成人では145名中25名（17.2%）および60～80歳の老人の場合は65名中20名（30.8%）と、それぞれ年齢層によりわずかな検出率の差を示した。しかし、同一年齢層の中でも、地域の異なる小学校に通学している6群の学童で、耐ウ菌の検出率が最低6.3%から最高37.1%と大きなばらつきが認められたことからみて、以上の年齢層別検出率に有意差を求めることはできなかった。　次に、上記の健康人のうち、同じ生活環境で、同一の食事を取って集団生活をしている人達の耐ウ菌排菌状況の推移を調べるために、上記健康人のうち、都内某乳児院に収容されている乳幼児48名および某養老院生活者65名を選び、隔月および逐月に連続3回本菌の検索を行ない、その検出率は調査時点により10.4～30.8%と大きく変動する事が知られた。さらに、これら検出菌株について、Hobbs型1～13の抗血清を用いて型別を行なってみた結果、同一個人から時期をへだてて採取した検体から3回連続して同一血清型の耐ウ菌を検出することのできた例は全く認められず、健康人の耐ウ菌の帯留は一過性のものであろうと結論された。　ただ、この調査を通じて得られた菌株772株中既知のHobbs型1～13（この調査の時点では13型迄しか確立されていなかった）のいずれかの血清型に型別されたものは304株（39.4%）にすぎず、残りの468株（60.6%）が型別不能であり、これら耐ウ菌の病原的役割の解明の必要に迫られた。しかし、その実験的追求は現段階では不可能に近いので、それらの型別の確率、その腸炎への応用を企図した。　2．Hobbs型に属さない耐熱性ウェルシュ菌の血清学的型別　上記のごとく、健康人ふん便由来耐ウ菌の約60%がHobbs型抗血清により型別不能であったことから、それらの血清型別を試みるためにそのなかから最初に20菌株を任意に選び出し、Hobbsらの方法に準じてそれぞれの抗血清を作成した。得られた20の抗血清は交叉吸収、凝集反応により異同をたしかめ、これらの抗血清により型別不能の菌株からさらに任意の菌株を選出し、同様な方法で抗血清を作り、未型別菌株を得て、さらに同じ方法を繰り返すという順序で耐ウ菌株を型別し、最終的にHobbsの1～17型に該当しない健康人由来株を新たに56抗原型に型別することができた。この56の抗原型に対応する各血清型をTW型1～56と仮称することとした。　以上のTW血清型が明らかになった時点で、その抗血清を用い、主として、Hobbs型に属さない耐ウ菌の分布状況を把握する目的で第二回目の調査を1969～1970年の2ケ年にわたって、前回同様合計1,091名の健康人から得られたふん便について実施した。対象健康人の内訳は、6～11歳の小学校児童が362名、15～17のの高等学校生徒350名および20歳以上の成人172名であり、耐ウ菌型別対象株は本菌が検出された161件歳ふん便からそれぞれ5個づつの集落を釣菌した計805株である。これら805株中318株（39.5%）は既知のHobbs型1～17のいずれかに型別されたので、残り487株についてTW型血清による型別を試みた。その型別状況を供試菌株の由来別にみると、学童ふん便来由株168株中163株（97.0%）、高校生ふん便由来株147株中128株（87.1%）および成人ふん便由来株172株中155株（90.1%）がTW型1－53のいずれかに型別された。　すなわち、今回TW型別の対象とした487株中446株（91.6%）がTW型1～56のいずれかに型別され、残りの41株（8.4%）がこれらの新しいTW型別法によっても型別不能であった。なお比較的高頻度に検出されたTW型菌は、1、5、6、11、20、21、31、44および52などであった。　3．東京都内に発生したTW型耐熱性ウェルシュ菌に起因する食中毒の疫学ならびに細菌学的検討　Hobbs型耐ウ菌の腸炎起病性については、広く承認されているが、反面、これらに型別されないために、耐ウ菌食中毒でありながら原因不明とされてきた事例の存在する可能性は否定できないであろう。上述のTW型別の食中毒原因究明への菌学的応用はHobbs型菌以外の耐ウ菌の腸炎起病性の確認するうえで重要な手段となるといえる。ここではTW型に属する菌に起因した食中毒事例の発生の概要を述べ、これらの腸炎起病性への疑問の解答を与えることとした。　この検討は1968年以降、東京都内に発生した集団食中毒を対象に加えられた。その結果、著者が明らかにしたTW型4ならびにTW型6による各1事例、さらにTW型4と45およびHobbs型11と15の4者の混合感染と推定される1事例を明らかにすることができた。　その3事例の疫学ならびに細菌学的成績の概要は次のごとくである。　事例1は、1968年6月19日、都内の某旅館に発生した集団食中毒である。原因追求の結果、耐ウ菌TW型4に起因する食中毒と推定された。原因食品は「鶏肉煮付」で、それを喫食した328名のうち156名が発病し、発病率は47.6%である。　この事例の平均潜伏時間は16.4時間で、主症状は腹痛（85.3）、水様性下痢（55.1%）、倦怠感（37.8%）頭痛（33.3%）および悪感（23.1%）である。少数例に発熱、嘔吐がみられた。　細菌学的検査は原因食の残品および患者ふん便を対象に実施された。　まず、原因食品からは、非加熱直接分離培養で食品1g当り3.7×10^3個のウェルシュ菌が検出され、それらの菌株の血清直別により、食品1g当りTW型4が2.6×10^3個、型別不能株が1.1×10^3個と算定された。Hobbs型菌は検出されていない。　患者の場合は、採取可能であった2病日患者便7件について100℃1時間加熱後耐ウ菌の検索を行ない、6例からTW型4を検出した。この型の菌は同じふん便の非加熱分離培養でも純培養状に検出された。すなわち、患者ふん便中には原因食品検出菌と同一菌型の耐ウ菌が多数排菌されていることが判明した。平行して行なった既知病原菌は陰性に終っている。　事例2は、1970年2月18日、都内某小学校において給食の「鯨肉煮付」を原因食として発生した食中毒である。本例は結果的には耐ウ菌TW型4、45とHobbs型11、15の混合感染によるものと推定された。　同時喫食者640名中196名（発病率30.7%）が発病し、平均潜伏時間は15.3時間、主症状は、水様性下痢（96.2%）と腹痛（75.6%）で、嘔気、嘔吐はなく、少数例に発熱が認められた。　原因食の残品と患者ふん便について実施した菌学的原因追求において、原因食品の「鯨肉煮付」からは、非加熱直接分離培養で食品1g当り1.7×10^5個のウェルシュ菌が検出され、それらの菌株から任意に選んだ20菌株について血清型別を行なった結果、20菌株中10株がHobbs型11、6株がHobbs型15で、TW型4および45がそれぞれ2づつであった。　患者については、192名の3～5病日ふん便が採取され病原菌の検索が実施され、うち178件（92.7%）が耐ウ菌陽性であり、他に既知病原菌は検出されていない。耐ウ菌陽性ふん便を検出菌型別に分けた成績では、Hobbs型11のみが検出されたふん便は23件、Hobbs型15が64件、TW型4が28件、TW型45が19件、Hobbs型11と15が共に検出されたもの12件、Hobbs型15とTW型4の両検出便15件、Hobbs型15とTW型45が5件、Hobbs型11とTW型4および45の3型陽性が2件、またHobbs型11と15およびTW型4の3者検出便が1件であった。　この成績は患者ふん便検出菌型と原因食検出菌のそれとの間に極めてよく一致していることを示している。　事例3は、1970年5月16日、都内某会社において社内給食の「ランチ」を原因食にして発生した食中毒で、原因菌の検索結果から耐ウ菌TW6型に起因すると推定された。　推定原因食の内容は、ポークカツ、スパゲティー、いり卵、八宝菜および米飯である。　「ランチ」喫食者213名中166名（発病率77.9%）が発病し、潜伏時間は平均12.3時間、主症状は下痢（94.6%）、腹痛（71.7%）で、そのほか少数例のものが倦怠感、嘔気、嘔吐、頭痛および発熱を訴えている。　原因菌の検索は、原因食品の残品および患者ふん便について実施され、原因食の「ランチ」からは、非加熱直接分離培養で食品１gあたり3.5×10^3個のウェルシュ菌が検出された。それらの検出菌株の血清型はTW型6であった。　患者の場合は、病原菌の検索のため2～4病日の患者便16件が採取され、うち13件（81.3%）から耐ウ菌が検出された。この事例では陽性件13中件12から原因食検出菌株の血清型と同じTW型6が分離されている。　本事例も、事例1の場合と同様に患者ふん便中の排菌状態を検討した結果、単一菌TW型6の排菌量の優位性が認められた　今回経験したTW型に起因すると推定された食中毒は、著者の血清型別を応用して明らかにされたものである。また、比較的長い検査期間でありながら、3例のTW型耐ウ菌食中毒が認められたことは、Hobbs型以外の耐ウ菌食中毒の発生頻度もかなり高い事が示唆される。4．食中毒事例由来ウェルシュ菌の耐熱性芽胞形成能について　一般に、細菌性食中毒の原因菌決定に際して必要な条件は、食中毒に罹患した患者のふん便から、「ヒト」に腸炎起病性のある細菌を分離同定すると同時に、推定原因食となった食品から、患者ふん便から検出されたものと同一の菌が分離されたことを確認することが、他の疫学的傍証と共に必要不可欠の条件である。ところが、耐ウ菌食中毒の場合には、ややその趣を異にし、推定原因食品から、耐ウ菌を検出するために、その食品乳剤を単にチオグリコレート培地に接種し、患者ふん便からの菌分離の際と同様に、100℃に1時間加熱したのち菌分離を試みたのでは、耐ウ菌の存在を証明する事ができないという難点がある。つまり、遺伝学的に耐熱性芽胞形成菌であっても、通常食品中に混在しているときは、必ずしも芽胞形成菌の形で存在せず大部分が栄養型の形をとっている。そのため食品を耐ウ菌分離の常法にしたがって直接加熱した場合には、それらの菌が死滅してしまい、その存在を証明することは不可能に近く、原因を明らかになしえない。　そこで著者は、食品からの耐ウ菌の証明には、加熱を行なわない検体からの分離菌について、それらが遺伝的に耐熱性芽胞を形成する能力があるかどうかを証明する必要があると考え、次の実験を行った。　食中毒事例からの分離菌を用いた実験に先立って、Hobbs型1～17型別参考菌株について現在ウェルシュ菌芽胞形成培地として報告されているEllnerの培地、Kimらの培地、Dancanらの培地、AngelottiらのSECブイヨンおよび西田らの肉カスブイヨンの5種類の培地の耐熱性芽胞形成能を比較検討した。各型別参考菌株を接種し、37℃で48時間培養した上記5種類の芽胞形成培地を、100℃60分間加熱し、冷却後その1白金耳を5%卵黄加CW寒天平板に塗沫して、上記の加熱条件に耐える芽胞を形成していたか否かを検討した。その結果、Kimらの培地が最もすぐれ、Dancanらの培地がこれについで良い成績を示すことが判明した。この成績に基づいて、以下各種条件で分離された食中毒患者および健康人由来、また推定原因食品由来の研究室保存株について耐熱性芽胞形成能をKimらの培地およびDancanらの培地を併用して比較検討した。　その結果、われわれの研究室で経験した8事例のウェルシュ菌食中毒の原因食品から、非加熱で分離された53菌株について耐熱性芽胞の形成能を調べたところ、50菌株（94.4%）に耐熱性芽胞形成能が認められた。　これに反し、健康人ふん便から非加熱直接培養で分離された96菌株のいずれもが耐熱性芽胞形成能を示さなかった。このことは、一見さきに示した健康人ふん便からの耐ウ菌検出の事実と矛盾するようであるが健康人の腸管常在性ウェルシュ菌の大部分は80℃30分の加熱で死滅する熱抵抗性の弱い芽胞形成性のウェルシュ菌で占められており、たとえ耐ウ菌が混在していても、その菌量は極めて少量であるため、健康人の非加熱ふん便から直接分離した菌株の中に耐ウ菌が混入してくる確率が極端に低いことを示したものであると考えた。　一方、上記8事例の患者ふん便から非加熱で分離された39菌株のウェルシュ菌の場合には、非加熱の状態で分離された菌株であるにもかかわらず、その全株が耐熱性芽胞形成能を持った菌であり、耐ウ菌食中毒の場合には、腸管常在ウェルシュ菌のそれをはるかに上廻る状態になるため、前記健康人ふん便からの分離菌の場合とは逆に、耐ウ菌のみが検出されたものである。　以上要約するに、健康人ふん便中に、「ヒト」の食中毒起因菌と同じ性状を持った耐ウ菌力広く分布していること、および血清学的には、それらからの分離耐ウ菌の約40%が、従来から知られているHobbsの1～17型菌で、残りの約60%が今回著者が明らかにしたTW1～56型菌から成り立っていたことを述べた。　同時に、1968年から1970年に至る3年間の比較的短い期間に、今回著者が健康人のふん便中に存在することを明らかにしたTW型菌と全く同一の抗原型を有する耐ウ菌に起因する集団食中毒事例が3例東京都内に発生したことを、それらの疫学的調査結果をも含めて詳細に述べた。　さらに、従来、耐ウ菌食中毒事件の解明の際に、推定原因食品と患者発生の因果関係を証明することが困難であるとする原因の、食品中の耐ウ菌の証明を、非加熱食品の乳剤をいったん芽胞形成培地に接種して培養したのち、その耐熱性芽胞形成能を調べて間接的に耐ウ菌が存在したことを証明する方法を確立し、耐ウ菌食中毒の日常検査を容易にすることができた。Among the physiological characteristics of Clostridium perfringens in human feces, survival of the organism from heating at 100℃ for 1-5 hours is said to be one of indispensable characteristics for the identification of its pathogenicity in regard to the ability of the organism to be an etiological agent of human enteritis. Because, there are numerous type of organisms belonging to the species of Cl. perfringens not only in nature including foods but also in human intestine as a normal intestinal flora. On the other hand, since many investigators have reported the fact that the heat resistant Cl. Perfringens exists in the feces of healthy subjects in certain extent, a series of investigations was conducted for clarifing the incidence and serotypes of isolates of heat resistant Cl. perfringens in the feces of healthy Tokyoites, in the period from 1966 through 1970. In the early part of the investigation conducted in the period of 1966-1968, a total of 1,688 fecal specimens was collected from healthy subjects, consisting of 48 of 1-3 years old infants, 1,080 of 6-11 years old pupils, 350 of 15-17 years old senior high school pupils, 145 of 20-50 years old adults, and 65 of 60-80 years old adults, and each 1 gram of them was inoculated into 13 ml of thioglycolate medium, followed by heating at 100℃ for 60 minutes respectively in order to isolate the heat resistant strains. After cooling, they were incubated at 37℃ for 48 hours. Then, 2 loops of the cultures were transfered onto the CW agar plate with 5% egg-yolk and incubated anaerobically at 37℃ for 24 hours. Through the investigation, it was found that 236 (14%) out of 1,688 had involved more or less heat resistant Cl. perfringens in the fecal specimens. However, the detection rate of the organism from specimens in each group was varied from 6.3% to 37.1% according to the groups tested. It was also observed that the detection rate of the organism in particular age group also varied according to the area of dwellings or difference of investigation period. When serotyping was conducted on the 772 isolates obtained through this survey, only 304 (39.4%) isolates could be typed into the known Hobbs\u27 serotypes 1-13 (as of December 1968, there were only 13 serotypes), and remaining 468 isolates were untypable by her serotyping. In addition, the detection frequency of the same serotype of organism from feces of healthy individuals was found to be quite low, when followup investigation was made on the 339 fecal specimens obtained from 113 representative individuals, for the consecutive 6 months with a interval of 1 or 2 months. And in each specimen, there were always variety of organisms consisting of several serotypes of the ones. Since there were so many untypable isolates by the Hobbs\u27 typing procedure, antigenic analysis of the untypable strains was attempted. Discrimination and serogrouping of individual isolates by their antigenic composition were made by using antisera immunized rabbits with representative cultures selected systematically from all these untypable strains. Through the cross absorption and agglutination tests on the prepares immune sera with antigens of these untypable strains, it was found that there were additional 56 serotypes (TW 1-56) of the organisms, other than the ones known to have been classified into Hobbs\u27 1-17 serotypes. The latter half of the same sort of investigation was conducted in the period of 1969-1970, on the fecal specimens collected from 1,091 normal healthy Tokyoites, consisting of 362 of 6-11 years old pupils, 350 of 15-17 years old senior high school pupils, and 379 of adults greater than 20 year of their ages. All the specimens collected were treated and inoculated as in the same way as it was done at the first investigation. In this time, efforts were concentrated for the isolation and discrimination of the new TW-type organisms. Consequently, 487 out of 805 isolates were found to be the organisms other than Hobbs\u27 1-17 serotypes. Of them, 446 (91.6%) isolates were typed into the new 51 TW-types, while the rest of 41 (8.4%) isolates were untypable by the new anti-TW typing sera. Among the isolates typed, TW-1, 6, 11, 20, 44, and 52 were relatively dominant organisms detected. As for the occurrence of food poisoning outbreaks due to these new TW-type organisms, there were 3 proved outbreaks in Tokyo in the period of 1968-1970. In these eases, a total of 518 patients were involved, and most of them developed typical food poisoning symptoms 12-16 hours after the injestion of the incriminated foods. In every case a responsible organism for the outbreak was isolated in the state of pure culture, both from the incriminated food and from the feces of patients simultaneously. They were proved to be caused by TW-4, 6, and mixture of TW-4 and 45 types of organisms respectively. In addition to these surveys, an experimental study was made to establish a practical procedure for the determination of heat resistant characteristics of Cl. perfringens involved in foods, because it has been well known that the evidence of the existence of the heat resistant organism in food is quite difficult to prove, if homogenates of suspicious food stuffs are heated at 100℃ for 60 minutes, as in the case of patients\u27 feces. In the preliminary experiment, comparative studies were carried out on the Hobbs\u27 type pilot strains for the ability of the formation of the heat resistant spores having capable of surviving from heating at 100℃for 60 minutes by using five kinds of spore forming media, such as Ellner\u27s medium, Nishida’s chopped meat broth, Angelotti\u27s sporulation enrichment culture (SEC) broth, Kim\u27s medium, and Dancan\u27s medium. As a result, it was noticed that Kim\u27s medium was the most suitable one for this purpose, followed by Dancan\u27s medium and Angelotti\u27s SEC broth respectively, when all the 48 hour cultures of 17 Hobbs\u27 type pilot strains in the above mentioned 5 media were compared. When it was applied on the laboratory isolates, majority of isolates (144/149) derived from both incriminated food and patients\u27 feces on 13 food poisoning outbreaks due to Cl. Perfringens formed successfully heat resistant spores in Kim\u27s and Dancan\u27s media. While all the 96 isolates obtained from unheated feces of healthy subjects failed to produce any heat resistant spores in the same media. Thus, it was concluded that when it was required to determine the heat resistant characteristics of Cl. perfringens involved in food stuffs, Kim’s or Dancan’s spore forming media were advisable to be used, after the enrichment of the organism in specimens in thioglycolate medium.獣医学博士麻布大

Factors Relating to Coagulation, Fibrinolysis and Hepatic Damage After Liver Resection

A survey of the blood of twenty-two patients who had undergone hepatic resection was performed. Serum levels of α-2 plasmin inhibitor-plasmin complex initially decreased from 1.58 ± 0.31 μg/ml on the preoperative day (PREOP), to 0.92 ± 0.14 μ/ml on the first postoperative day (POD 1), and then increased to 3.13 ± 0.92 μg/ml on the seventh postoperative day (POD 7) (mean ± SE)). Thrombin-anti-thrombin III complex (14.2 ± 4.3 ng/ml on PREOP and 26.0 ± 4.1 ng/ml on POD 7 (mean ± SE)) and D-dimer (335 ± 96 ng/ml on PREOP and 1859 ± 258 ng/ml on POD 7 (mean ± SE)) increased in the early postoperative stage. The level of 6-keto-prostaglandin F1α increased after the operations (from 13.2 ± 1.8 pg/ml on PREOP to 37.8 ± 12.8 pg/ml on POD 7 (mean ± SE)). The level of thromboxane B-2 decreased at first, and then gradually increased and returned to its preoperative level on POD 7 (144.7 ± 43.8 pg/ml on PREOP, 57.6 ± 27.5 pg/ml on POD1 and 152.5 ± 58.4 pg/ml on POD 7 (mean ± SE)). Superoxide dismutase activity increased at first, and then gradually decreased, postoperatively (2.8 ± 0.5 NU/ml on PREOP, 4.8 ± 0.8 NU/ml on POD1 and 2.6 ± 0.3 NU/ml on POD 7 (mean ± SE)). That is, biodefensive reactions which protect patients against the shift to disseminated intravascular coagulation (DIC) were inferred with by the increase in antiplatelet aggregation, despite the activation of coagulation and fibrinolytic mechanisms after hepatic resection

Mechanisms of reduction in hole concentration in Al-doped 4H-SiC by electron irradiation

Abstract From the temperature dependence of the hole concentration in unirradiated lightly Al-doped 4H-SiC epilayers, an Al acceptor with E V + 0.2 eV, which is an Al atom (Al Si ) at a Si sublattice site, and an unknown deep acceptor with E V + 0.35 eV are found, where E V is the top of the valence band. Both the densities are similar. With irradiation of 0.2 MeV electrons the Al acceptor density is reduced, while the unknown deep acceptor density is increased. Judging from the minimum electron energy required to displace a substitutional C atom (C s ) or the Al Si , the bond between the Al Si and its nearest neighbor C s is broken due to the displacement of the C s by this irradiation. Moreover, the displacement of the C s results in the creation of a complex (Al Si -V C ) of Al Si and a carbon vacancy (V C ), indicating that the possible origin of the deep acceptor with E V + 0.35 eV is Al Si -V C

Sodium benzoate attenuates 2,8-dihydroxyadenine nephropathy by inhibiting monocyte/macrophage TNF-α expression

Sodium benzoate (SB), a known D-amino acid oxidase (DAO) enzyme inhibitor, has an anti-inflammatory effect, although its role in renal damage has not been explored. 2,8-dihydroxyadenine crystal induced chronic kidney disease, in which TNF-α is involved in the pathogenesis, was established by oral adenine administration in C57BL/6JJcl mice (AdCKD) with or without SB to investigate its renal protective effects. SB significantly attenuated AdCKD by decreasing serum creatinine and urea nitrogen levels, and kidney interstitial fibrosis and tubular atrophy scores. The survival of AdCKD mice improved 2.6-fold by SB administration. SB significantly decreased the number of infiltrating macrophages observed in the positive F4/80 immunohistochemistry area and reduced the expression of macrophage markers and inflammatory genes, including TNF-α, in the kidneys of AdCKD. Human THP-1 cells stimulated with either lipopolysaccharide or TNF-α showed increased expression of inflammatory genes, although this was significantly reduced by SB, confirming the anti-inflammatory effects of SB. SB exhibited renal protective effects in AdCKD in DAO enzyme deficient mice, suggesting that anti-inflammatory effect of SB was independent of DAO enzyme activity. Moreover, binding to motif DNA sequence, protein level, and mRNA level of NF-κB RelB were significantly inhibited by SB in AdCKD kidneys and lipopolysaccharide treated THP-1 cells, respectively. We report that anti-inflammatory property of SB is independent of DAO enzymatic activity and is associated with down regulated NF-κB RelB as well as its downstream inflammatory genes such as TNF-α in AdCKD

The effect of aldosterone and aldosterone blockade on the progression of chronic kidney disease : a randomized placebo-controlled clinical trial

The progression of chronic kidney disease (CKD) cannot be completely inhibited. We first explored factors contributing to CKD progression in patients with CKD in a prospective observational study. In the next phase, we focused on the effects of aldosterone, conducting a single-blinded placebo-controlled study using the selective mineralocorticoid receptor antagonist (MRA), eplerenone (25 mg/day). We recruited patients with CKD stage 2 and 3 whose plasma aldosterone concentration was above 15 ng/dL based on the prior data of a prospective observational study. In the CKD cohort study (n = 141), baseline plasma aldosterone concentration was identified as an independent contributory factor for the future rate of change in estimated glomerular filtration rate (eGFR). When the cut-off value for aldosterone was set at 14.5 ng/dL, the decline rate was significantly higher in patients with higher plasma aldosterone concentration (− 1.22 ± 0.39 ml/min/1.73 m2/year vs. 0.39 ± 0.40 ml/min/1.73 m2/year, p = 0.0047). In the final intervention study, in the eplerenone group, eGFR dropped at 6 months after the initiation of the study, and thereafter eGFR was maintained until the end of the study. At 24 months and 36 months, eGFR was significantly higher in the eplerenone group than in the placebo group. In conclusion, MRA can be an effective strategy in preventing CKD progression, especially in patients with high plasma aldosterone