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Ultrastructural study of the clearance of intracerebrally infused
native and modified albumin-gold complexes
D.H. Dobrogowska1, A.S. Lossinsky2 and A.W. Vorbrodt1
1New York State Office of Mental Retardation and Developmental
Disabilities, Institute for Basic Research in Developmental Disabilities,
Staten Island, New York and 2Huntington Medical Research Institutes, Neurological
Research Laboratories, Pasadena, USA
Offprint requests to: A.W.
Vorbrodt, New York State Office of Mental Retardation and Developmental
Disabilities, Institute for Basic Research in Developmental Disabilities,
1050 Forest Hill Road, Staten Island, New York 10314, USA. FAX: 719-982-6346.
Summary. 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 µl) 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. Histol.
Histopathol. 13, 647-656 (1998)
Key words: Intracerebral infusion,
Clearance of albumin, Albumin-gold complex, Reverse transport, Blood-brain
barrier
DOI: 10.14670/HH-13.647
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