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J A Gutierrez Diaz

Publications and source records attributed to J A Gutierrez Diaz.

11 recordsLinked to original sources
PubMed1988

Freeze-fracture cytochemistry of cholesterol content in neuronal plasma membrane following cerebral ischaemia.

Minor changes on the neuronal perikaryon cytoplasm and large alterations in neuronal processes have been demonstrated with transmission electron microscopy after 60 minutes of focal and selective cerebral ischaemia. The distribution of cholesterol in neuronal plasma membrane and perikarya plasmalemma of normal and ischaemic caudate nucleus was investigated with the polyene antibiotic filipin, a morphological probe for membrane cholesterol domains in freeze-fracture replicas. After filipin incubation of prefixed vibratome slices, filipin-cholesterol complexes appeared as 20-30 proturberances and pits on P- and E-faces. Distinct patterns of filipin-cholesterol complexes were found in non-ischaemic and ischaemic neuronal membrane. The filipin-treated specimens showed a 35-40% drop in cholesterol content in the neuronal plasmalemma one hour after cerebral ischaemia.

Animals↗
PubMed1985

Absence of filipin-sterol complexes from the ciliary necklace of ependymal cells.

The polyene antibiotic filipin reacts specifically with membrane cholesterol and produces membrane perturbations. Prefixed vibratome slices of cat ependymal cells were treated with a glutaraldehyde solution containing 300 microM filipin. Freeze-fracture of these cells revealed numerous 25-30 nm protuberances on fracture faces (filipin-sterol complexes) in the ciliary membrane. In the ciliary necklace, however, these filipin-sterol complexes were absent. These results suggest that the ciliary necklace has a low cholesterol content.

Animals↗
PubMed1985

Disturbance of plasmalemmal astrocytic assemblies in focal and selective cerebral ischemia.

Selective cerebral ischemia was induced in the caudate nucleus of seven normothermic anesthetized cats through transorbital clamping of the anterolateral penetrating lenticulostriated arteries. The plasmalemma of astrocytic foot processes has been studied with the freeze-fracture technique and conventional electron microscopy 10, 15 and 30 min after ischemia. After 15 min of circulatory arrest, assemblies of intramembrane particles (IMPs) disappear in some areas of astroglial perivascular plasmalemma in the ischemic caudate nucleus. Interastrocytic gap junctions do not change significantly. 30 min after ischemia, the pericapillary astroglial end foot is expanded and organelles are greatly perturbed (cytotoxic edema). Although the function of astrocytic intramembrane particle assemblies is unclear, it is postulated that the disappearance of this membrane specialization may play a role in the pathophysiology of cytotoxic astroglial edema.

Animals↗
PubMed1985

Possible role of endothelium in the orientation of smooth muscle cells in experimental neointima.

Myointimal cells (MIC) orientation and intimal thickening evolution, induced by grafting an autogenous venous patch onto the rat common carotid artery, were studied with light microscopy at different times until 14 months after surgery. Intimal thickenings in the venous patch were most prominent at an intermediate postoperative period, after which their mean size did not change significantly. In host artery neointima, the greatest MIC proliferation was observed at a late stage of evolution. MIC arrangement was predominantly circumferential to the blood stream in venous patch neointima, whereas it was mostly axial in the host artery. The interaction between MIC orientation and endothelial regeneration in the operated vessel is discussed.

Animals↗
PubMed1984

Aspects of interastrocytic gap junctions in blood-brain barrier in the experimental penumbra area, revealed by transmission electron microscopy and freeze-fracture.

Interastrocytic gap junctions in the blood-brain barrier of the experimental penumbra area were studied in the cat caudate nucleus 1 h after ischemia. Transmission electron microscopy and freeze-fracture studies revealed only slight changes in gap junctions between astrocytes, indicating that these junctions are very resistant to hypoxia.

Animals↗
PubMed1984

Assemblies of intramembranous particles in astrocytoma: a preliminary report.

A human astrocytoma has been studied with the freeze-fracture technique. The astrocytic membrane presents many assemblies formed by aggregations of intramembranous particles (5.8-7.8 nm in diameter) in P-face arranged in a square, and complementary pit assemblies in E-face. In the interastrocytic gap junctions the connexions are packed in a crystalline array.

Astrocytoma↗
PubMed1982

Specific endothelial granules in venous patch neoendothelium in the rat.

Weibel-Palade bodies were observed in the neoendothelium and capillaries of vasa vasorum of autologous 'venous patches' grafted in the common carotid artery of the rat. These corpuscles varied in number and distribution but were most frequently found in the luminal area of endothelial cytoplasm. In venous patch neoendothelium, the shape, size and substructure of Weibel-Palade bodies were similar to those in other types of vascular endothelium. These specific endothelial granules were more numerous during the week following neoendothelium formation. It is proposed that these corpuscles may play a role in the proliferation of endothelial cells in venous patches.

Animals↗