Biomedical subjects

O Fujimori

Publications and source records attributed to O Fujimori.

39 records · Page 3Linked to original sources

PubMed1980

Ultrastructural studies on the pancreatic polypeptide cell of the rat with special reference to pancreatic regional differences and changes induced by alloxan diabetes.

Rat pancreatic tissues were fixed with our modification of Dalton's fixative and the islets from various pancreatic regions were examined by electron microscopy. In addition, the effect of the alloxan-diabetic state on the pancreatic polypeptide cell was examined at the ultrastructural level. The results are as follows. (1) The islets of the rat contain four types of glandular cells: A, B, D and PP cells. (2) The PP cell is characterized by approximately 170-millimicron-sized secretory granules with a rather ill-defined core. The ultrastructure of this type cell is described in some detail. (3) In the pancreatic portion which hooks around posterior to the superior mesenteric vessels, PP cells are abundant and some of them are markedly degranulated. Their cell organelles, such as the nucleolus, granular endoplasmic reticulum and Golgi apparatus are well developed. (4) In alloxan-diabetic rats, B and PP cells show disappearance and numerical increase, respectively. In the PP cells, hypertrophy of the Golgi apparatus and appearance of extremely electron-translucent secretory granules are noted.

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PubMedDate not supplied

Microencapsulation of pancreatic islets. A technique and its application to culture and transplantation.

Hamster pancreatic islets were encapsulated by a biocompatible membrane composed of the molecular sequence of alginate-polylysine-alginate. The encapsulated islets released insulin into the culture medium in response to secretagogues in short-term incubation. In long-term culture, the encapsulated islets maintained their insulin-releasing capacity for 28 days at a level similar to that of the unencapsulated islets. No overgrowth of fibroblastic cells was observed inside the capsule even after 70 days of culture. Further, the encapsulated hamster islets were xenotransplanted to streptozotocin-induced diabetic rats intraperitoneally. Some of the encapsulated islets, which were recovered from a recipient 27 days after transplantation, were found to be viable, although prolonged normalization of fasting plasma glucose levels of the recipients could not been achieved. On the contrary, the unencapsulated islets were replaced by massive connective tissue elements and insulin-positive B cells were hardly detected within the grafts 22 days after transplantation. The results of this study seem to confirm the potential of the application of the encapsulating technique to primary culture of parenchymal cells and to transplantation of pancreatic islets.

Alginates↗

PubMedDate not supplied

Brain malformations caused by retroviral vector-mediated gene transfer of hippocampal cholinergic neurostimulating peptide precursor protein into the CNS via embryonic mice ventricles.

Hippocampal cholinergic neurostimulating peptide precursor protein (HCNP-pp) is a unique multifunctional protein, being not only the precursor of HCNP, which promotes the phenotype development of septo-hippocampal cholinergic neurons, but also the binding protein of phosphatidylethanolamine, ATP, Raf-1 kinase (known as "Raf-1 kinase inhibitory factor" in peripheral organs), and serine protease. We obtained a high-titer retroviral vector harboring HCNP-pp cDNA by the use of a modified packaging cell line and centrifugation, and by injecting it into embryonic mouse ventricles, we investigated the function of its gene product within the central nervous system (CNS). We found that efficient transduction into hippocampal pyramidal neurons can be achieved by injecting the vector into embryonic brain ventricles on embryonic day 14 (E14). Three days after receiving the intraventricular injection of the high-titer HCNP-pp retrovirus vector on E14, the tissues around the ventricles showed an overexpression of HCNP-pp. This was accompanied by a reduced amount of activated MEK and Erk (as analyzed by histochemical and Western blot methods), suggesting that HCNP-pp also regulates the MAP-kinase cascade within the CNS. Surprisingly, mouse brains that received the HCNP-pp retroviral vector showed massive malformation of the hippocampus and cerebellum when examined 30 days after birth. This shows that strictly regulated HCNP-pp gene expression is necessary for the normal development of the mouse brain, and that the moderate overexpression achieved by retroviral vector-mediated gene transfer is sufficient to cause severe abnormality of entire brain structures.

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