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Biomedical subjects

A Bignami

Publications and source records attributed to A Bignami.

At least 73 records · Page 4Linked to original sources
PubMed1984

Glial fibrillary acidic (GFA) protein in Müller glia. Immunofluorescence study of the goldfish retina.

Glial fibrillary acidic protein, the subunit of intermediate filaments specific for astrocytes, was localized by immunofluorescence in the Müller glia of goldfish retina. Based on previous studies reporting the localization in Müller glia of carbonic anhydrase C, an oligodendrocyte marker, we suggest that the main type of neuroglia in the retina combines properties which in the brain are specific for astrocytes and oligodendrocytes.

Animals↗
PubMed1984

Expression of the 70 kdalton neurofilament protein in clonal lines of mouse neuroblastoma.

The expression of the neurofilament (NF) protein triplet (70, 150 and 200 k daltons (K)) was studied by immunofluorescence in two clones of murine C-1300 neuroblastoma. Clone 1 formed clumps of round cells with few processes, while in clone 2 the cells were more dispersed and extended many processes. In both clones selective decoration of tight bundles of filaments was only observed with anti-NF 70 K. Round cells contained curvilinear bundles with the appearance of whorls and ringlets , while in cells extending processes the bundles were more rectilinear in shape. Ringlets were the most prominent feature in large clumps of cells. Antisera to vimentin, the mesenchymal-type intermediate filament (IF) protein, decorated the neuroblastoma cells with a different pattern. Treatment of the two clones with dibutyryl cAMP, a neurite-inducing agent, did not result in the expression of NF 150 K and NF 200 K, although many cells had extended processes and the shape of the NF bundles had changed accordingly.

Animals↗
PubMed1984

Formation of 10-nanometer filaments from the 150K-dalton neurofilament protein in vitro.

In the present study we report self-assembly of individual neurofilament (NF) triplet proteins (70K, 150K, and 200K daltons) isolated by anion exchange chromatography from bovine spinal cord. Formation of smooth 10-nm filaments by both NF 150K and NF 70K is shown. Optimal conditions for NK 150K filament formation were incubation in 100 mM MES, 0.2 M NaCl, 1 mM DTT, 0.5 mM EGTA, pH 6.5, at 37 degrees C for 24 hr. Under the same assembly conditions, NF 200K formed 7-nm coiled structures. These thin filaments were similar to those formed by NF 70K and 150K under less than optimal conditions. Our results indicate that NF 150K is an integral part of the filament (self-assembly of NF 70K was previously demonstrated by others). We suggest that the optimal conditions resulting in the formation of a 10-nm 200K homopolymer remain to be determined and that the thin coiled structures formed by all three NF proteins are protofilaments that coalesce to form a double helical 10-nm filament.

Animals↗
PubMed1984

Masking of epitopes in tissue sections. A study of glial fibrillary acidic (GFA) protein with antisera and monoclonal antibodies.

Antisera to chicken brain antigen (CBA) isolated by hydroxyapatite chromatography from 8 M urea extracts following repeated extractions with phosphate buffer selectively decorate neurofilaments (NF) in neuronal perikarya, dendrites and axons. The antisera also reacted with GFA protein, the astrocyte-specific intermediate filament protein, as indicated by the adsorption of NF immunoreactivity following passage of the antisera through columns prepared with purified GFA protein. Moreover, the antisera stained the polypeptides of the NF triplet (70 kd, 150 kd, 200 kd) and GFA protein by the immunoblotting procedure. Monoclonal antibodies selectively decorating NF in tissue sections were isolated from a fusion of mouse myeloma cells with spleen cells of mice immunized with CBA. By the immunoblotting procedure the antibodies decorated the 150 kd NF polypeptide and GFA protein. No staining of glial filaments or any other structure on tissue sections was also observed with antibodies derived from another fusion strongly reacting with GFA protein on immunoblots. All antibodies (monoclonal and polyclonal) appeared to react with the same region of the GFA polypeptide as indicated by immunoblots of cleavage products.

Animals↗
PubMed1984

Amyloid-like (Congophilic) neurofibrillary tangles do not react with neurofilament antisera in Alzheimer's cerebral cortex.

The immunohistological properties of Alzheimer's neurofibrillary tangles (NFT) were studied by immunofluorescence with neurofilament (NF) antisera and with antiserum raised to paired helical filaments (PHF) in NFT preparations, brain smears, and cryostat sections. NFT decorated by NF antisera were Congo red-negative. Conversely, PHF antisera stained Congo red-positive NFT but failed to decorate NF-positive NFT. It is concluded that NF do not cross react with typical NFT, i.e., NFT displaying amyloid-like birefringence, under the conditions reported in this study.

Alzheimer Disease↗
PubMed1984

Cell-specific domains of glial- and muscle-type intermediate filament proteins. Immunoaffinity chromatography and immunoblotting study of GFA protein and desmin.

In order to localize the cell specific domains of glial- and muscle-type intermediate filaments, the purified subunits (bovine GFA protein and chicken desmin) were fragmented and the digests passed through immunoaffinity columns or stained by the immunoblotting procedure to determine which fragments reacted with the monospecific polyvalent antisera. The following fragments were found immunoreactive according to these criteria: 30 K (GFA) and 33 K (desmin) N-bromosuccinimide fragments (tryptophan cleavage); 35 K (GFA) and 39 K (desmin) 2-nitro-5-thiocyanobenzoic acid fragments (cysteine cleavage); 18 K (GFA) and 9 K (desmin) cyanogen bromide fragments. Fragmentation of GFA protein was also accomplished using proteolytic digestion with chymotrypsin and trypsin. Two resistant core polypeptides, one about 37 K and stable in the chymotryptic digests and one about 21 K and stable in the tryptic digests bound specifically to the immunoaffinity columns. The 21 K tryptic fragment was found to contain the 18 K cyanogen bromide fragment. The fragmentation patterns support recently published structural domain models for intermediate filament proteins. The immunochemical findings indicate that the immunoreactive regions of GFA protein are located in the aminoterminal region of the middle domain of these models (coil I), while they appear to be situated in the aminoterminal headpiece of the protein in the case of desmin.

Amino Acid Sequence↗
PubMed1984

Regenerating dorsal roots and the nerve entry zone: an immunofluorescence study with neurofilament and laminin antisera.

Dorsal spinal roots were crushed in 30 rats at the lumbar or thoracic level. Peripheral roots, nerve entry zone, and spinal cord were studied 3 to 5 weeks after operation by immunofluorescence with neurofilament, glial fibrillary acidic (GFA), and laminin antisera. As previously shown in sciatic nerve undergoing Wallerian degeneration, reactive Schwann cells forming the bands of Büngner stained intensely with laminin antisera. Within these bands bundles of regenerating axons were present as indicated by double staining with laminin and neurofilament antisera. With very few exceptions, regenerating axons were not observed in the laminin-negative intramedullary division of the root. This also appeared to be the case when the dome-shape protrusion of central nervous system tissue forming the intramedullary division was surrounded by regenerating fibers. Compared with GFA antisera, laminin antisera allowed a better identification of the boundary between the central and peripheral nervous systems. In the central nervous system only blood vessels were laminin-positive, whereas Schwann cells' processes were decorated by GFA antisera in peripheral roots, the staining being stronger in reactive Schwann cells.

Animals↗
PubMed1984

Laminin in rat sciatic nerve undergoing Wallerian degeneration. Immunofluorescence study with laminin and neurofilament antisera.

Immunofluorescence with laminin antisera revealed a striking change in the localization of this basal membrane glycoprotein in rat sciatic nerve as a result of Wallerian degeneration. The staining was confined to the endoneurium in normal sciatic nerve and during the first days of degeneration. On day 11 endoneurial tubes were no longer identified in the distal stump of crushed nerves or of nerves that had been transected and tightly ligated to prevent regeneration. In both crushed and ligated nerves proliferating Schwann cells forming the cell-bands of Büngner were intensely laminin positive. With double-labeling experiments, laminin and neurofilament antisera revealed similar but not identical staining patterns in crushed nerves, which suggests a close relation between laminin and regenerating axons. Crushed nerves had recovered their normal appearance 18 days after operation while anti-laminin reactivity was decreased in parts of ligated nerves undergoing fibrosis. The localization of laminin in reactive Schwann cells was confirmed by electron microscopy using the indirect immunoperoxidase procedure. Axons did not contain reaction product.

Animals↗
PubMed1984

Early appearance of desmin, the muscle-type intermediate filament protein, in the rat embryo.

Antisera raised to desmin, the protein subunit of muscle-type intermediate filaments (IFs), were used to study by indirect immunofluorescence and immunoperoxidase procedures the early development of skeletal muscle in the rat embryo. The specificity of the antisera (Dahl D, Bignami A: J Histochem Cytochem 30:207, 1982) was confirmed by immune blotting on chicken gizzard extracts and purified antigen. Desmin-positive cells were first observed on day 12 by immunofluorescence and on day 13 by the immunoperoxidase procedure. Desmin immunoreactivity was not found in caudal somites in which the dermatome was present, i.e., somites where the dorso-lateral part had maintained its definite boundaries and epithelioid characteristics. Desmin-positive cells were observed within the myotome of cranial somites where the dermatome had disappeared. Compared to day 13, desmin-positive cells had extended ventrally on day 14, while on day 15, they were found in the skeletal musculature of the trunk and the limbs.

Animals↗
PubMed1983

Two spinal cord lesions in a patient with ankylosing spondylitis and cervical spine injury.

A patient with ankylosing spondylitis sustained C3-C4 vertebral subluxation and C4-C5 myelopathy after a hyperextension trauma. Autopsy showed that several segments below the main cervical cord lesion at the fractured site, there was a second spinal cord lesion at the T1 vertebral level with no corresponding local bony or ligamentous damage. The thoracic cord lesion was probably secondary to traction of the upper thoracic cord, where the blood supply is poor, in a narrow and rigid spinal canal at the moment of extreme hyperextension.

Fractures, Bone↗
PubMed1982

Plasminogen activators in rat neural tissues during development and in Wallerian degeneration.

The fibrinolytic activity of blood is caused by plasminogen activators (PA) converting plasminogen to plasmin, the active fibrinolytic protease. PA activity in rat neural tissues was studied by Todd's fibrin slide technique. Cryostat sections overlayed with a film of plasminogen and fibrin were incubated for 60-90 min. PA activity was related to the size of the zone of fibrinolysis surrounding the sections. No lysis occurred with fibrin alone. In rats perfused with saline prior to decapitation the size of the zone of lysis was approximately the same as in non-perfused animals. PA activity was compared in the following tissues: adult (2-3 month) cerebellum and 6-14-day postnatal cerebellum; normal sciatic nerve and transected sciatic nerve 1-9 weeks after operation (in these experiments the sciatic nerve was crushed on the left side, on the right side it was transected and the stumps were tightly ligated to prevent regeneration); normal optic nerves and optic nerves undergoing Wallerian degeneration 1-2 weeks after enucleation of the eye. As compared to normal cerebellum PA activity was increased in 6-14-day cerebellum. PA activity was also markedly increased in both crushed and ligated sciatic nerves 1-4 weeks after operation while no differences were observed between normal sciatic nerves and sciatic nerves 9 weeks after ligation. The zone of fibrinolysis surrounding normal optic nerves and the optic nerves of blinded rats was approximately the same. It is proposed that the fibrinolytic system may be relevant to the problem of CNS regeneration.

Animals↗
PubMed1982

Posttraumatic anterior spinal cord syndrome: pathological studies of two patients.

Two patients sustained acute anterior spinal cord injury associated with a posteriorly displaced bone fragment and herniated cervical disc. Postmortem examination of both spinal cords showed extensive destruction of the cord at the site of injury with sparing of the posterior portion of the dorsal columns; the anterior spinal artery was patent. We conclude that posttraumatic anterior spinal cord syndrome can be caused by damage to the anterior part of the cord without involvement of the anterior spinal artery.

Adult↗
PubMed1982

Vimentin in the central nervous system. A study of the mesenchymal-type intermediate filament-protein in Wallerian degeneration and in postnatal rat development by two-dimensional gel electrophoresis.

Intermediate filament proteins were identified by two-dimensional gel electrophoresis in urea extracts of rat optic nerves undergoing Wallerian degeneration and in cytoskeletal preparations of rat brain and spinal cord during postnatal development. The glial fibrillary acidic (GFA) protein and vimentin were the major optic nerve proteins following Wallerian degeneration. Vimentin was a major cytoskeletal component of newborn central nervous system (CNS) and then progressively decreased until it became barely identifiable in mature brain and spinal cord. The decrease of vimentin occurred concomitantly with an increase in GFA protein. A protein with the apparent molecular weight of 61,000 and isoelectric point of 5.6 was identified in both cytoskeletal preparations of brain and spinal cord, and in urea extracts of normal optic nerves. The protein disappeared together with the polypeptides forming the neurofilament triplet in degenerated optic nerves.

Aging↗
PubMed1982

Ultrastructural localization of neurofilament proteins in aluminum-induced neurofibrillary tangles and rat cerebellum by immunoperoxidase labeling.

The localization of neurofilament proteins was investigated at the light and electron microscopic levels by the peroxidase-antiperoxidase procedure in the motor neurons of rabbit spinal cord accumulating bundles of filaments (neurofibrillary tangles) consequent to the intrathecal injection of aluminum and in rat cerebellum. As indicated by immunoaffinity chromatography the antisera used in this study reacted with 72,000- and 150,000-dalton polypeptides of the mammalian neurofilament "triplet". In the motor neurons of rabbit spinal cord neurofibrillary tangles were prominently stained. Regions of cytoplasm surrounded by the tangles were negative. In the cerebellar cortex the reaction product was confined to structures containing large amounts of neurofilaments, particularly the terminal branches of basket axons surrounding Purkinje cells. The absence of staining in the outer molecular layer containing processes with other types of filaments, that is, Bergmann glia (gliofilaments) and thin parallel fibers (microtubules), served as control for the specificity of the reaction. In both spinal cord and cerebellum the reaction product appeared as elongated strands. In spinal cord, filaments cut in cross-section had the appearance of peripherally stained circular structures approximately 250 A in diameter.

Aluminum↗
PubMed1982

Immunohistological localization of desmin, the muscle-type 100 A filament protein, in rat astrocytes and Müller glia.

The distribution of glial fibrillary acidic (GFA) protein and desmin was compared in cryostat sections of rat brain, spinal cord, and eye by immunofluorescence and peroxidase-antiperoxidase (PAP) staining. Desmin antisera were raised to antigen purified from chicken gizzard. In rat brain and spinal cord, GFA protein and desmin were selectively localized in astrocytes. Neurons and axons were not stained. The only difference between GFA and desmin antisera was the staining of smooth muscle in small arteries with anti-desmin. It was only in retinal glia that a difference in the localization of the two proteins was apparent. As previously reported, only the glia limitans on the inner surface of the retina was demonstrated with GFA antisera in the normal eye. With anti-desmin Müller fibers spanning the whole thickness of the retina were stained. It is concluded that GFA and desmin form two distinct systems of 100 A filaments in astroglia, as previously reported for GFA and vimentin.

Animals↗
PubMed1982

Glial fibrillary acidic (GFA) protein in Schwann cells: fact or artifact?

Antisera to the glial fibrillary acidic (GFA) protein stained a subpopulation of Schwann cells in cryostat sections of rat sciatic nerve by indirect immunofluorescence and by the peroxidase-antiperoxidase (PAP) procedure. The staining pattern was entirely different from that obtained with vimentin antisera, which uniformly decorated endoneurial tubes. Electron microscopic examination of sciatic nerve provided a possible explanation for the relatively small number of Schwann cells decorated by GFA antisera: 10 nm filaments were mainly confined to Schwann cell processes surrounding nonmyelinated axons. A marked increase in GFA-positive Schwann cells and in Schwann cells containing filaments by electron microscopy was observed in sciatic nerves undergoing Wallerian degeneration. Conversely, immunochemical procedures failed to demonstrate the presence of antigen reacting with GFA antisera in extracts of sciatic nerve, both normal and degenerated. These include absorption experiments, double immunodiffusion, immunoaffinity chromatography, and immunoradiometric assay. Two explanations may be considered for these findings: i) Schwann cell intermediate filaments and GFA protein share common antigenic determinants, the immunohistological methods being more sensitive to detect cross-reactivity as compared to immunochemical procedures on tissue extracts; and ii) the binding of anti-GFA to Schwann cell 10 nm filaments is not due to immunological cross-reactivity.

Animals↗