Kokichi Yamamoto

Affinity labeling displays the stepwise activation of ICE-related proteases by Fas, staurosporine, and CrmA-sensitive caspase-8.

The activation of multiple interleukin-1β converting enzyme-related proteases (caspases) in apoptotic mammalian cells raises questions as to whether the multiple active caspases have distinct roles in apoptotic execution as well as how these proteases are organized in apoptotic signaling pathways. Here we used an affinity-labeling agent, YV(bio)KD-aomk, to investigate the caspases activated during apoptotic cell death. YV(bio)KD-aomk identified six distinct polypeptides corresponding to active caspases in Fas-stimulated Jurkat T cells. On staurosporine treatment, four polypeptides were detected. Competition experiments showed that the labeled caspases have distinct substrate preferences. Stepwise appearance of the labeled caspases in each cell death event was consistent with the view that the activated caspases are organized into protease cascades. Moreover, we found that stepwise activation of caspases similar to that induced by Fas ligation is triggered by exposing non-apoptotic Jurkat cell extracts to caspase-8 (MACH/FLICE/Mch5). Conversely, CrmA protein, a viral suppressor of Fas-induced apoptosis, inhibited the protease activity of caspase-8. Overall, these findings provide evidence that caspase-8, a CrmA-sensitive protease, is responsible for initiating the stepwise activation of multiple caspases in Fas-stimulated cells.

Fulminant hepatitis B following bone marrow transplantation in an HBsAg-negative, HBsAb-positive recipient; reactivation of dormant virus during the immunosuppressive period

It is widely accepted that seroconversion of HBsAg to HBsAb indicates clearance of hepatitis B virus. We describe a 50-year-old man with chronic myelocytic leukemia who developed lethal hepatitis B 22 months after allo-BMT. He had been negative for HBsAg and positive for HBsAb before BMT. Hepatitis B virus latently existing in the liver cells before BMT proliferated during the immunosuppressed period causing fatal hepatitis. Recipients with positive HBsAb should be considered to have the potential for active hepatitis B to emerge after BMT. Bone Marrow Transplantation (2000) 25, 105–108.

Diagnostic accuracy of cardiac metaiodobenzylguanidine scintigraphy in Parkinson disease

Background and purpose:  To estimate the diagnostic accuracy of cardiac 123I‐metaiodobenzylguanidine (MIBG) scintigram for detection of Parkinson disease.

Leukotriene B4-activated human endothelial cells promote transendothelial neutrophil migration.

We explored the effect of leukotriene B4 (LTB4) on endothelial cells in LTB4‐induced transendothelial migration (TEM) of neutrophils as an in vitro model of neutrophil extravasation. Chemotactic response of human neutrophils to LTB4 was significantly lower than that in response to N‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP), whereas the extent of TEM in response to LTB4 was significantly higher than that to fMLP. The study on random migration induced by LTB4 and fMLP also showed similar results, which indicated that LTB4 might affect the human umbilical cord vein endothelial cell (HUVEC) barrier. Neutrophil TEM was induced by pretreatment of HUVEC monolayer with LTB4 but not with fMLP. Treatment of endothelial cells by ONO‐4057, a LTB4 receptor antagonist, abolished the effect of LTB4 almost completely whereas neutrophils treated with ONO‐4057 could transmigrate through HUVEC treated with LTB4. These findings indicated that LTB4 could induce neutrophil TEM by acting on HUVEC. J. Leukoc. Biol. 62: 203–209; 1997.

The expression of co-stimulatory molecules and their relationship to the prognosis of human acute myeloid leukaemia : poor prognosis of B7-2-positive leukaemia

We examined the expression of co‐stimulatory molecules on leukaemic cells of 52 adult patients with acute myeloid leukaemia (AML) (34 men and 18 women) and analysed the relationship between these expressions and the patients prognosis. B7‐1 was not expressed in any of the 23 patients investigated, whereas B7‐2 was expressed in 26/52 patients (50.0%). B7‐2 was expressed in all AML patients with monocytic morphology (M4 or M5) and in 16/42 cases without monocytic morphology. CD54 was expressed in 28/37 patients examined (75.7%), and CD58 was expressed in all of the AML patients except one (M7). The overall survival of the 26 B7‐2‐positive leukaemia patients (1–24 months, median survival 11.5 months) was significantly shorter than that of the 26 B7‐2‐negative leukaemia patients (1–71+ months, median 35.1 months) (P = 0.0080). In addition, the B7‐2‐positive patients exhibited significantly shorter disease‐free survival periods compared to the B7‐2‐negative patients (P = 0.021). There was no significant difference in age, sex, haematological data and complete remission rate between the B7‐2‐positive and B7‐2‐negative patients. Our results indicated that B7‐2 is one of the most crucial factors in the prognosis of adult acute leukaemia and can be expected to have an important role in tumour immunity.

RANDOM MIGRATION OF POLYMORPHONUCLEAR LEUKOCYTES INDUCED BY GM-CSF INVOLVING A SIGNAL TRANSDUCTION PATHWAY DIFFERENT FROM THAT OF FMLP

Granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) Induced random migration of human polymorphonuclear leukocytes (PMNs) but not chemotaxis. Chemoattractants such as N‐formylmethionyl‐leucyl‐phenylalanine (fMLP), leukotriene B4 (LTB4), and interleukin‐8 (IL‐8) induced both random migration and chemotaxis. Other inflammatory cytokines, including granulocyte colony‐stimulating factor (G‐CSF), interleukin 1α (IL‐1α), and tumor necrosis factor α (TNF‐α), did not induce either movement. One‐minute exposure of PMNs to GM‐CSF was sufficient for the induction of random migration, whereas fMLP‐induced random migration required continued presence of fMLP. Inhibitors of phosphatidylinositol 3‐kinase (PI3‐K), protein kinase C (PKC), and protein tyrosine kinase (PTK) had no effect on random migration induced by GM‐CSF, whereas fMLP‐induced movements were partially inhibited by PTK inhibitors but not by inhibitors of PI3‐K inhibitors nor PKC inhibitors. Myosin light chain kinase inhibitors inhibited movements of PMNs induced by both GM‐CSF and fMLP. These findings also imply that some aspects of the signal transduction pathway of GM‐CSF leading to random migration is different from that of fMLP. Our findings suggest that cell movements are controlled through diverse signal transduction systems. J. Leukoc. Biol. 61: 500–506; 1997.

Transient calcium elevation in polymorphonuclear leukocytes triggered by thrombin-activated platelets.

Abstract:  The effect of thrombin‐activated platelets and their release products on the intracellular free calcium concentration ([Ca2+]i) of human polymorphonuclear leukocytes (PMNs) was studied by loading PMNs with a fluorescent indicator of calcium, fura‐2. [Ca2+]i of PMNs was transiently elevated by thrombin‐activated platelets. The supernatant of thrombin‐activated platelets also elicited a transient elevation of [Ca2+]i in PMNs. Pretreatment of the supernatant with hexokinase caused a decrease in the transient [Ca2+]i elevation of PMNs, while hexokinase abrogated the [Ca2+]i elevation of PMNs elicited by 80 μmol/1 adenosine triphosphate (ATP). Pretreatment of the supernatant with trypsin also decreased the magnitude of the elevation, while trypsin had no effect on the response to ATP. These findings suggest that thrombin‐activated platelets induce a transient [Ca2+]i elevation in PMNs by releasing ATP and some trypsin‐sensitive factor(s).

Phagocytosis and ingestion of influenza virus by human polymorphonuclear leucocytes in vitro: Electronmicroscopy studies

Interaction of human polymorphonuclear leucocytes (PMNL) and influenza virus (IFV) was studied in vitro. At 0 degree C, the viral particles were bound extensively to the surface of the PMNL membrane with a ratio of about 1000 virus particles to a single PMNL. The binding was sensitive to neuraminidase, suggesting attachment through sialo-compound receptors. At 37 degrees C, the virus particles disappeared rapidly from the cell surface, about half of them being eluted and the remainder being endocytosed into the cytoplasmic vesicles. Immuno-gold electronmicroscopy suggests that the virus particles are ingested into phagosomal vesicles and lysed.

Plankton Rotatoria in Japanese Inland Waters

Summary1.The present paper concerns the studies of the plankton rotifers of Japanese inland waters. For this purpose, the writer examined more than 1500 plankton samples from more than 200 localities which are distributed in almost all parts of Japan. They contained, though plankton samples, not a few number of creeping and sessil rotifers as temporal plankters.2.With the addition of previous records, the number of Rotatorian species of Japan has become 186, with 28 varieties and forms, which belong to 4 orders, 13 families and 45 genera. They are enlisted in table III.3.Japan is conveniently divided into 9 districts. The number of species recorded from each district is as follows: — 1) Hokkaidô, 68 species; 2) the north eastern district, 72 species; 3) the central mountainous district, 122 species; 4) the eastern Pacific coast district, 60 species; 5) the central district, 158 species; 6) the southern Pacific coast district (incl. Inland sea coast), 41 species; 7) the north eastern Japan Sea coast district, 31 species; 8) the western Japan Sea coast district, 25 species; 9) the western district, 38 species.4.Some species noteworthy from various viewpoints are described. As the majority of plankton rotifers are of universal distribution, they are commonly found everywhere. So far as the rare and unusual species are concerned, the creeping rotifers have become the main subject of study. Among the euplanktic rotifers, only a few species are mentioned to be rare in Japan, namely, Conochiloides coenobasis, Brachionus angularis var. chelonis, and Keratella javana.5.Those which are originated either in the boreal or in the austral region are noted. Most of the rotatorian species are cosmopolitan, and they may be found, with only a few exceptions, at any longitude, if the environmental conditions are suitable. Accordingly, when the problems toward the distribution are considered, either the latitude or altitude is of more interest than the longitude is. In Japan, the southern boundaries of boreal species could be clearly observed, while the northern boundaries of austral elements were comparatively vague.6.So far as the widely distributed rotifers are concerned, there can be seen a tendency that the wider the distribution area, the larger the occurrence rate of pelagic species.7.The samples obtained from brackish waters were not numerous. In the present study, Brachionus plicatilis, Keratella cruciformis var. eichwaldi, and Pedalia fennica were pointed out as the representative haline rotifers.8.Some rotifers are well-known for their morphological variations. Above all, the following species have very ample variability in morphlogical aspects; i.e., Brachionus calyciflorus, Brachionus quadridentatus, Keratella quadrata, Keratella valga and Keratella cochlearis. The last mentioned species are of most interest with respect to the difference of both the seasons and the localities.9.The annual succession of plankton rotifers was observed at the southern basin of Lake Biwa-ko. The average changes of the important species examined during they from 1927 to 1937 were figured in the diagram.

Nitric oxide derived from human umbilical vein endothelial cells inhibits transendothelial migration of neutrophils

We evaluated the roles of nitric oxide (NO) derived from endothelial cells in neutrophil transendothelial migration (TEM). Pretreatment of human umbilical vein endothelial cells (HUVECs) with NG-nitro-L-arginine methyl ester hydrochloride (L-NAME) or NG-monomethyl L-arginine (L-NMMA), which are inhibitors of NO synthases, enhanced neutrophil TEM. Similar augmentation of TEM was observed in the presence of an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy PTIO). Neutrophil TEM across L-NAME- or L-NMMA-treated HUVECs was inhibited by continuous NO supply by NO donors. These findings support the suggestion that continuous production of NO by endothelial cells suppresses neutrophil TEM. Flow cytometric analyses revealed that NO accumulates in neutrophils co-cultured with NO-producing HUVECs. A decreased amount of NO was detected in neutrophils co-cultured with L-NAME-treated HUVECs compared with neutrophils co-cultured with untreated HUVECs. Soluble guanylyl cyclase (sGC) is known as one of the most important targets of NO in neutrophils. 3-(5′-Hydroxymethyl-2′furyl)-1-benzyl indazole (YC-1), an activator of sGC, inhibited L-NAME-induced neutrophil TEM. It was interesting that inhibition of neutrophil sGC with 1-H[1,2,4-]oxadiazolo[4,3-a]quinoxalin-1-1 (ODQ) was sufficient to enhance TEM. These results suggest that NO derived from HUVECs acts on neutrophils to inhibit TEM, at least in part by activating sGC. Our findings imply the role of NO constitutively generated by HUVECs in protection against excessive neutrophil extravasation and unnecessary tissue damage under physiological conditions.