Cytochemical study of the involvement of cell organelles in formation and accumulation of fibrillar amyloid in the pancreas of NORbeta transgenic mice.
Journal - Histology and histopathology (Spain )
Phosphatase ultrastructural cytochemistry was used to evaluate the participation of cytoplasmic organelles in the accumulation of fibrillar amyloid beta (Abeta) in exocrine acinar cells and in macrophages of the pancreas of transgenic mice overexpressing a carboxy-terminal fragment of Abeta protein precursor (ABPP). Nucleoside diphosphatase (NDPase) and glucose-6-phosphatase (G6Pase) were used as cytochemical markers of the endoplasmic reticulum (ER), thiamine pyrophosphatase (TPPase) as a marker of the Golgi apparatus (GA), and acid phosphatase (AcPase) as a marker of lysosomes. Monoclonal antibody 4G8 raised against the 17-24 aa sequence of human Abeta protein was used for immunogold localization of fibrillar Abeta. The results of this study indicate that the formation of Abeta in acinar cells occurs directly in the vacuolar areas of the rough ER (RER) without evident participation of the elements of the GA, whereas an intimate structural relation with primary lysosomes suggests their role in modification or digestion of the deposited amyloid. In macrophages, fibrillar amyloid was present in numerous cytoplasmic vacuoles located frequently in close proximity to flattened saccules of the ER. This structural pattern revealed similarity to that observed previously in microglial cells producing fibrillar PrP amyloid in scrapie-infected mice and Abeta in brains of human elderly patients and in Alzheimer's type brain pathology.
|ISSN : ||0213-3911|
|Mesh Heading : ||Acid Anhydride Hydrolases Acid Phosphatase Amyloid beta-Protein Animals Glucose-6-Phosphatase Golgi Apparatus Immunohistochemistry Lysosomes Macrophages Mice Mice, Transgenic Neurofibrils Organelles Pancreas Thiamine Pyrophosphatase Transgenes metabolism metabolism metabolism enzymology enzymology enzymology enzymology enzymology enzymology metabolism|
|Mesh Heading Relevant : ||metabolism metabolism metabolism cytology metabolism|
Increased blood-brain barrier permeability and endothelial abnormalities induced by vascular endothelial growth factor.
Journal - Journal of neurocytology (UNITED STATES )
The early effects of intracerebrally infused vascular endothelial growth factor (VEGF) on the blood-brain barrier (BBB) to endogenous albumin were studied using a quantitative immunocytochemical procedure. In addition, transmission electron microscopy was used to observe morphological changes induced in brain vasculature. A solution of VEGF in saline (40 ng/10 microliters) was infused into the parieto-occipital cortex of mice, which were killed 10 min, 30 min, and 24 h afterwards. Untreated mice and mice that received infusion of saline only were used as controls. For immunocytochemical evaluation, ultrathin sections of immersion-fixed brain samples embedded in Lowicryl K4M were exposed to anti-albumin antiserum followed by protein A-gold. Simultaneously, other brain samples embedded in Spurr resin were used for ultrastructural examination. Morphometric and statistical analysis indicated that as soon as 10 min after infusion of VEGF, 33% of vascular profiles were leaking albumin, and this value increased at 30 min to 92%. This effect of VEGF appears to be of rather short duration because after 24 h, only 27% of vascular profiles showed signs of leakage. The results of ultrastructural observations indicate that VEGF (30 min post-infusion) induces several changes in microvascular segments located in the area of intracerebral infusion of VEGF. These changes consist of the appearance of interendothelial gaps; fragmentation of the endothelium with formation of segmental, fenestrae-like narrowings; degenerative changes of the vascular basement membrane; and the appearance of fibrin gel in the vessel lumen. At 24 h post-infusion, solitary diaphragmed fenestrae appeared in attenuated segments of the endothelium in a few microvascular profiles. These changes, which are interpreted to be preparatory steps for angiogenesis, affect the structural integrity of the vascular segments, leading to extravasation of blood plasma proteins, including albumin.
|ISSN : ||0300-4864|
|Mesh Heading : ||Albumins Animals Blood-Brain Barrier Brain Endothelial Growth Factors Endothelium, Vascular Immunohistochemistry Lymphokines Male Mice Mice, Inbred BALB C Microscopy, Electron Neovascularization, Physiologic Permeability Vascular Endothelial Growth Factor A Vascular Endothelial Growth Factors metabolism blood supply drug effects|
|Mesh Heading Relevant : ||drug effects pharmacology drug effects pharmacology drug effects|
Quantitative immunocytochemical study of blood-brain barrier glucose transporter (GLUT-1) in four regions of mouse brain.
Journal - The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society (UNITED STATES )
Application of immunogold cytochemistry revealed polar (asymmetric) distribution of GLUT-1 in mouse brain microvascular endothelia, representing the anatomic site of the blood-brain barrier (BBB). This polarity was manifested by an approximately threefold higher immunolabeling density of the abluminal than the luminal plasma membrane of the endothelial cells. The immunoreaction for GLUT-1 in nonbarrier continuous (skeletal muscle) or fenestrated (brain circumventricular organs) microvascular endothelial cells was absent. In the choroid plexus, the basolateral plasmalemma of the epithelial cells was labeled more intensely than the vascular fenestrated endothelium. Addition of morphometry to the applied immunogold technique makes it possible for even subtle differences to be revealed in the density of immunolabeling for GLUT-1 in blood microvessels located in four brain regions. We found that the density of immunosignals in the microvessels supplying the cerebral cortex, hippocampus, and cerebellum was essentially similar, whereas in the olfactory bulb it was significantly lower. Asymmetric distribution of GLUT-1 in the endothelial plasma membranes presumably leads to a reduced concentration of glucose molecules in the endothelial cells compared to blood plasma and also secures their more rapid transport across the abluminal plasmalemma to the brain parenchyma.
|ISSN : ||0022-1554|
|Mesh Heading : ||Animals Brain Cerebellum Cerebral Cortex Endothelium, Vascular Fixatives Glucose Transporter Type 1 Hippocampus Immunohistochemistry Mice Mice, Inbred BALB C Microcirculation Monosaccharide Transport Proteins Olfactory Bulb blood supply blood supply metabolism blood supply metabolism metabolism pharmacology blood supply metabolism drug effects blood supply metabolism|
|Mesh Heading Relevant : ||metabolism metabolism|
Ultrastructural study of the clearance of intracerebrally infused native and modified albumin-gold complexes.
Journal - Histology and histopathology (SPAIN )
The main objective of this ultrastructural study was to gain a better understanding of the involvement of brain vasculature in clearance of proteins from edematous fluid. For this purpose, both native and modified (cationized, glucosylated, and mannosylated) bovine serum albumin-gold complexes (BSA-G, catBSA-G, glucBSA-G and manBSA-G respectively) dissolved in phosphate-buffered saline (PBS) were infused (10 microliters) into mouse cerebral cortex. Samples of brain were taken at 30 min, 1 h, and 24 h post-infusion for electron microscopical examination. All BSA-G complexes were rapidly taken up and deposited inside the cytoplasm of pericytes and of various glial cells (microglia and eventually astrocytes) located in the area adjacent to the infusion site. Only glucBSA-G particles also appeared inside the nuclei of some cells. In the applied experimental conditions and at the examined time intervals, neither BSA-G nor catBSA-G and glucBSA-G complexes were transported back to the bloodstream, although they entered vascular basement membrane and were eventually internalized in the endosomes or multivesicular bodies of the endothelial cells. Only a few gold particles representing the manBSA-G complex were found inside the vascular lumen, suggesting their reverse transport to a rather small degree. The mechanism of this transport, however, remains unclear. Complexes of catBSA-G were apparently trapped by the negatively charged vascular basement membrane and remained in this structure without any further significant uptake by the endothelial cells. These observations suggest that large size and multimeric nature of albumin-gold complexes are limiting factors making it difficult to interpret the results and hampering their relevance to the clearance in vivo of native albumin from brain edematous fluid.
|ISSN : ||0213-3911|
|Mesh Heading : ||Animals Cations Cattle Cerebral Cortex Female Glycosylation Gold Colloid Male Mannose Mice Mice, Inbred BALB C Serum Albumin, Bovine ultrastructure metabolism|
|Mesh Heading Relevant : ||metabolism metabolism|