Morphological and Flow Cytofluorometrical Analyses of Regenerated Rat Thymus after Irradiation.

Fujikura, Yoshihisa; Wang, Yu-Hsueh; Tsuchida, Masahiro; Ohba, Yukio; Konishi, M; Yamauchi, M; Kawamura, H.; Sawada, Teruo; Tokuda, Nobuko; Choi, Mi‐Jin; Naito, Katsusuke; Fukumoto, Tetsuo

doi:10.1679/aohc.60.79

Cited by 12 publications

(8 citation statements)

References 11 publications

(10 reference statements)

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“…2b) appears to parallel the in situ phagocytosis event reported by Fujikura et al, who employed similar irradiation conditions to those described in the present study. 8 The authors clearly showed phagocytosis of apoptotic thymocytes by macrophages using transmission electron microscopy. After 6-Gy X-irradiation, the number of macrophages that phagocytosed the dead thymocytes in rat thymus dramatically increased in a time-dependent manner.…”

Section: Discussionmentioning

confidence: 99%

“…21 Egg PC, at a ®nal concentration of 480 mM with 0Á1 mCi 1,2-di [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]palmitoyl PC, was dried under N 2 stream in the presence of 5 mM oleate and 1 mM PA. To this lipid mixture, an aqueous solution containing 10 mM CaCl 2 , 25 mM KF, 1Á5% (vol/vol) ethanol, and 50 mM HEPES, pH 7Á0, was added and sonicated in a bathtype sonicator for 1 min at room temperature. After addition of 20 ml of crude membrane suspension, the reaction mixture was incubated for 90 min at 308.…”

Section: Enzyme Sourcesmentioning

confidence: 99%

“…6 In fact, macrophages phagocytosing apoptotic thymocytes in situ are found in thymus during radiation-induced apoptosis. 7,8 Investigating lipid-metabolizing enzymes in conjunction with in vivo apoptotic processes is potentially of great importance because altered lipids are not only linked to the celldeath signal pathway but also participate in the modi®cation of cellular membrane structure that is indispensable for explaining the morphological changes such as cell shrinkage, membrane blebbing and clearance by phagocytosis. However, little is known of the modulations of membrane lipids during in vivo apoptosis.…”

Section: Introductionmentioning

confidence: 99%

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Elevation of oleate‐activated phospholipase D activity during thymic atrophy

et al. 2002

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SUMMARYVarious phospholipases are thought to be associated with the in vitro apoptosis of thymocytes. In the present study, the in vivo phospholipase D (PLD) activity of rat thymus was studied after wholebody X-irradiation or injection of dexamethasone (DEX). Using exogenous [14 C]dipalmitoyl phosphatidylcholine (PC) as the substrate, an elevation of oleate-activated PLD activity was observed during thymic atrophy. The activity increases were sevenfold at 48 hr after 5-Gy irradiation and fourfold at 72 hr after injection of 5 mg/kg DEX. The elevation of PLD activity appeared to parallel extensive thymus shrinkage. An increased level of thymic phosphatidic acid (PA), the presumed physiological product of PLD action on PC, was also detected. By comparing the acyl chains of PA with those of other phospholipids, PA appeared to originate from PC. To assess the role of PLD during thymic atrophy, thymocytes and stromal cells were isolated. Although thymocytes themselves exhibited signi®cant PLD activation, the major elevation in PLD activity (greater than fourfold) was found in isolated stromal cells. PLD was also activated during in vitro phagocytosis of apoptotic thymocytes by the macrophage-like cell line P388D1. This in vitro phagocytosis was signi®cantly inhibited by PLD action blockers, such as 2,3-diphosphoglycerate and 1-butanol. These observations strongly suggest that the alteration of oleate-activated PLD activity is part of an in vivo event in the progression of thymic atrophy, including phagocytic clearance of apoptotic thymocytes.

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Section: Discussionmentioning

confidence: 99%

Section: Enzyme Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Elevation of oleate‐activated phospholipase D activity during thymic atrophy

et al. 2002

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“…1). On day 7 the vascular structure of the thymus had almost recovered [19], and the proportion of S-phase cells was 1.5 times greater than that of the normal control rats [8]. On day 14 the thymus mass had recovered to about 70% of normal [2,17], and the percentages of CD4 + CD8…”

Section: Discussionmentioning

confidence: 99%

“…We previously investigated the effects of radiation exposure on rat thymus at various doses [2,8,11,17,19]. In these studies, irradiation damaged not only thymocytes but also stromal components and vascular structures.…”

Section: Introductionmentioning

confidence: 99%

MHC Class II Antigen Expression was Different from MHC Class I Antigen Expression in Irradiated and Recovering Rat Thymus.

Tokuda

Katsube

Sakuragi

et al. 2002

Acta Histochem. Cytochem

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We exposed rats to a heavy, but sublethal, dose of X-radiation that was calculated as the maximum that left them alive. Immediately after irradiation the rats lost body and thymus weight. The number of thymocytes decreased and the structure of the thymus was destroyed. The thymus weights then increased rapidly for a few days from day 7 followed by a slower increase. Immunohistochemically, the recovery of major histocompatibility complex (MHC) class II-positive cells in the thymus was slower than that of MHC class I-positive cells. Recovery of MHC Class II-positive and ED1-positive cells in the thymus was slow, especially in the medulla. Thymus structure appeared similar to normal control animals on day 14, although the number of MHC class II-and ED1-positive cells in the medulla was lower than that of controls even 21 days after radiation exposure. The delay in recovery of MHC class II-positive stromal cells might affect the regeneration of thymocyte subpopulations after irradiation.

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