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N Blaes

Publications and source records attributed to N Blaes.

26 records · Page 2Linked to original sources
PubMed1980

The programming of silk-gland development in Bombyx mori. I. Effects of experimental starvation on growth, silk production, and autolysis during the fifth larval instar studied by electron microscopy.

The cytological development of the silk gland has been studied by light and electron microscopy in silkworms experimentally starved at different periods of the natural feeding stage during the fifth instar. When newly molted animals are not provided with food, no sign of growth is observed. Starvation initiated early during the obligatory feeding period, stops cell growth and development of the organelles involved in protein synthesis and secretion, whereas it induces the appearance of organelles concerned with autolysis. These effects are reversible if starvation is not prolonged beyond two days. Starvation during the facultative feeding period, at the time of massive fibroin production, results in quantitative and qualitative modifications of organelles related to the decrease of fibroin production and the onset of autolysis. Rough endoplasmic reticulum, responsible for fibroin synthesis, forms transitory whorls. Fibroin transport via the Gjolgi apparatus and secretion of the protein into the gland lumen decrease parallel to fibroin synthesis, so that no fibroin storage can be detected in any organelle. After food deprivation, autophagosomes and secondary lysosomes rapidly develop in the cytopolasm, and if starvation continues portions opf the cytoplasm are sequestered and completely destroyed. If animals are refed, fibroin production is resumed and autolysis declines. These ultrastructural alterations of the silk gland during experimental starvation are very similar to those observed during the periods of physiological starvation (molt and cocoon spinning) and generally considered to be under hormonal control. Our results raise the question of the nature of interactions between alimentary and hormonal factors which control silk-gland development.

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PubMed1980

Variations in growth and cell cycle time of arterial smooth muscle cells cultured at low density.

The population kinetics of cultured rat arterial smooth muscle cells replated at various low densities were studied by direct counting and observation of the cells. Population doubling time decreases with increasing initial density of the culture. These variations in population doubling times depend on both the variation in the percentage of quiescent cells and on the variation of the mean cell cycle time of non-quiescent cells.

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PubMedDate not supplied

Use of human mesenteric arteries to study chronic vascular rejection in SCID/beige mice reconstituted with human spleen cells.

We wanted to establish a preclinical model of chronic vascular rejection (CVR) by transplanting small arteries from the mesentery of cadaveric organ donors by the rapid "sleeve" technique into SCID/beige mice reconstituted with human allogeneic spleen cells. After institutional authorization and with informed consent from relatives, we obtained tissues and cells from cadaveric organ donors. A piece of mesentery was recovered from the donor and kept in buffered solution at 4 degrees C until use. After dissection of the mesentery, small arteries of suitable size were transplanted in place of the infrarenal aorta of the mice. Cells for the immunological reconstitution of the mice were spleen cells from the same or other organ donors. Twenty-three suitable arterial segments were obtained from the mesentery of three cadaveric donors. Ten of the mice received 3 x 10(7) human spleen cells intraperitoneally 1 week after the arterial graft and they all showed circulating human CD3+ and CD19+ cells 2 weeks after injection. The mice were sacrificed 5 weeks after the arterial graft. SCID/beige mice reconstituted with allogeneic spleen cells showed a typical CVR, whereas mice that received no cells had a normal vascular anatomy. We believe our model is well suited for the study of treatment of CVR under human allograft conditions.

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PubMedDate not supplied

Chronic vascular rejection: histologic comparison between two murine experimental models.

BACKGROUND: We previously developed an experimental model to study chronic vascular rejection (CVR) in mice, the orthotopic aortic allograft. More recently we performed human arterial grafts into SCID/Beige mice reconstituted with human spleen cells. We report herein the differences in CVR lesions. MATERIAL AND METHODS: In the first model, recipient mice were C57BL/6 (H-2b), and donor mice were DBA/2 (H-2d). In the second model, terminal branches of the human superior mesenteric artery were transplanted into SCID/Beige mice in the infrarenal aorta. Human immune reconstitution was achieved by a single intraperitoneal injection of 30 x 10(6) human spleen cells. The presence of human lymphocytes and IgG was verified weekly. In both models, the vascular grafts were inserted in the infrarenal aortic position using the sleeve technique. The transplanted mice were sacrificed at 35 days after the operation. The grafts were analyzed by histology and morphometry. The mean intimal thickening was calculated based on transverse sections at 0.1-mm intervals. RESULTS: Typical CVR lesions developed with neointimal thickening, T-cell infiltration, and smooth muscle cell (SMC) proliferation in both models. In the mouse aortic model, disappearance of SMC in the media was noted in contrast to human arterial transplants, where the media remained intact. CONCLUSION: Other groups have noted that arteries conserve their media in clinical organ transplants. From this point of view, the lesions in the second experimental model (human arteries) better reflect the pathology of CVR in clinical transplantation than the murine aortic transplant model.

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PubMedDate not supplied

Human immune reconstitution with spleen cells in SCID/Beige mice.

BACKGROUND: We developed an original experimental model to study chronic vascular rejection (CVR) consisting of a graft of human mesenteric artery followed by human immune reconstitution into CB.17 SCID/Beige mice. Human immune reconstitution achieved after human PBMC injection has often been variable and incomplete. The aim of this work was to develop an alternative method to achieve a complete, functional human immune reconstitution. METHOD: After institutional authorizations, spleen cells were recovered from cadaveric organ donors. Single intraperitoneal injections of various doses of spleen cells were made into 70 CB.17 SCID/Beige mice. Reconstitution of the human immune system was monitored by flow cytometry (circulating human cells) and ELISA (human IgG). Colonization of murine lymphoid organs by human cells was studied by immunohistochemistry and flow cytometry. Evaluation of the immune function consisted of examination of CVR lesions in human arterial grafts. The animals were humanely killed at day 28. RESULTS: After injection of 30 to 40 x 10(6) spleen cells, the mice showed significant human CD3(+), CD19(+), and CD56(+) populations in peripheral blood. The mean human cells levels were, respectively, 8.2% +/- 5.4%, 2.9% +/- 1.2%, and 5.3% +/- 5.1%. Murine spleen and mesenteric lymph nodes were colonized by human T and B cells, while the murine thymus was only colonized by human T cells. Human IgG was detected in murine serum (65.9 +/- 63.3 mg/L) and typical CVR lesions were observed within the allogeneic grafts. CONCLUSION: Intraperitoneal injection of 30 to 40 x 10(6) human spleen cells into CB.17 SCID/Beige mice induces complete and functional human immune reconstitution allowing the study of CVR under human allogeneic conditions.

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