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Biomedical subjects

W Cammer

Publications and source records attributed to W Cammer.

At least 55 records · Page 3Linked to original sources
PubMed1990

Mechanisms and suppression of inflammatory demyelination.

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease of the central nervous system commonly used as a model for multiple sclerosis. In both of these diseases demyelination occurs association with perivascular infiltrates of T-cells and macrophages. The similarities in immunopathology suggest that these two diseases share common mechanisms of tissue destruction. We have proposed a general mechanism to explain the clinical and histopathological features of EAE. T-cells sensitized to the inducing antigen, myelin basic protein (MBP), react with antigen-presenting cells (possibly endothelial cells, microglia or astrocytes) in the central nervous system. As a consequence of this reaction, T-cells release lymphokines which activate macrophages, stimulate an augmenting inflammatory response, and, through the action of vasoactive amines, induce vasospasm and breakdown of the blood-brain barrier. The activated macrophages secrete inflammatory mediators, including plasminogen activator and other proteinases, which, in concert with serum plasminogen and complement, initiate myelin destruction. The macrophage products also serve to enhance the inflammatory response and vascular permeability. In support of this hypothesis we find that: (1) macrophage-secreted proteinases can degrade MBP in lyophilized myelin and that proteolysis is amplified in the presence of plasminogen; (2) proteolysis of proteins in fresh myelin by macrophage proteinases and plasminogen or by plasmin is potentiated by complement; (3) removal of macrophages from the circulation suppresses EAE; (4) proteinase inhibitors suppress EAE; and (5) prazosin, an alpha 1-adrenergic receptor antagonist, suppresses the clinical signs of EAE and the increased vascular permeability but only delays the inflammatory response. We believe that prazosin acts on the vascular alpha 1-adrenergic receptor to inhibit vasospasm and prevent opening of the blood-brain barrier. Thus it is possible to suppress both clinical signs and pathology by interceding at several steps of the cell-mediated immune reaction.

Animals↗
PubMed1989

Gliosis in the spinal cords of rats with experimental allergic encephalomyelitis: immunostaining of carbonic anhydrase and vimentin in reactive astrocytes.

Spinal cord sections from rats sensitized to develop experimental allergic encephalomyelitis (EAE) were immunostained with antibodies against glial fibrillary acidic protein (GFAP), carbonic anhydrase, and vimentin, to see whether the latter two antigens could be detected in GFAP-positive reactive astrocytes. Sixteen days after sensitization (16 dpi) there was intense carbonic anhydrase immunostaining in GFAP-positive cells in the spinal cords of EAE rats, particularly in the white matter. At 13 and 20 dpi carbonic anhydrase immunostaining in astrocytes was less intense, and in the spinal cord white matter of control animals carbonic anhydrase was not detected in the few GFAP-positive cells. In the spinal cords of EAE rats vimentin immunostaining was observed in inflammatory cells and astrocytes. In the latter, GFAP and carbonic anhydrase were colocalized with vimentin. The data suggest that carbonic anhydrase expression in astrocytes is an acute response to injury and that vimentin can be detected in astrocytes, as well as inflammatory cells, as early as 16 dpi.

Animals↗
PubMed1989

Differential localization of glutathione-S-transferase Yp and Yb subunits in oligodendrocytes and astrocytes of rat brain.

Glutathione-S-transferase Yb subunits were recently identified in rat brain and localized to astrocytes, ependymal cells lining the ventricles, subventricular zone cells, and tanycytes. Another isoform, Yp (pi family), was detected in rat brain by immunoblotting, and its mRNA was detected by Northern hybridizations. Double immunofluorescence localized Yb and Yp in different glial cells. The strongly Yp-positive cells were identified as oligodendrocytes by virtue of their arrangement in rows in white-matter tracts, colocalization in strongly carbonic anhydrase-positive cells, and association with myelinated tracts in the corpus striatum. Ependymal cells in the choroid plexus and ventricular lining were also strongly Yp positive, whereas Yb was not detected in the choroid plexus. The occurrence of Yp at low levels in astrocytes was indicated after immunostaining by a sensitive peroxidase-antiperoxidase method, which revealed weak staining of those cells in the molecular layer of the cortex. The data suggest that Yb and Yp subunits are primarily localized to astrocytes and oligodendrocytes, respectively, and that both are absent from neurons. The glutathione-S-transferase in oligodendrocytes may participate in the removal of toxins from the vicinity of the myelin sheath. The finding of glutathione-S-transferases in ependymal cells and astrocytes in the brain also suggests that this enzyme could be a first line of defense against toxic substances.

Animals↗
PubMed1989

Immunocytochemical staining of astrocytes, tanycytes, immature glial cells and ependymal cells in the central nervous system of the normal rat and the myelin-deficient mutant.

Central nervous system (CNS) tissue from young myelin-deficient (md) mutant rats and male littermate controls was immunostained with antibodies against the following glial-cell antigens: glial fibrillary acidic protein (GFAP), glutamine synthetase, vimentin, the Yb isozyme of glutathione-S-transferase (Yb) and carbonic anhydrase. Gliosis was most severe in spinal-cord 'white-matter' tracts in the md rat. The most dramatic differences between astrocytes in the md and normal animals were revealed with anti-GFAP and anti-vimentin. Ependymal cells and tanycytes were quite similar in the md and normal CNS. Among the glial-cell antigens, Yb showed the broadest distribution, which included astrocytes, ependymal cells and tanycytes.

Animals↗
PubMed1988

The astrocyte as a locus of carbonic anhydrase in the brains of normal and dysmyelinating mutant mice.

There is some controversy in the literature whether carbonic anhydrase occurs in astrocytes, as well as in oligodendrocytes and myelin, in the mammalian brain. In the present study this issue was addressed by double immunostaining for carbonic anhydrase and two astrocytic "markers" in the brains of normal mice and two dysmyelinating mutants, jimpy and shiverer. In the brains of young mice, carbonic anhydrase and glutamine synthetase were colocalized in astrocytes in the cortical gray matter. In gray matter of the adult mouse brain, it was possible to immunostain both carbonic anhydrase and glial fibrillary acidic protein (GFAP) in the same cells. However, in contrast to the findings in gray matter, in and near subcortical white matter carbonic anhydrase could be detected only in oligodendrocytes and myelinated fibers. In the brains of jimpy mice, virtually all the carbonic-anhydrase-positive cells were also GFAP positive, even in regions normally occupied by white matter. In the brains of young and adult shiverer mice, carbonic anhydrase was localized in astrocytes in the gray matter, but in and near the tracts normally occupied by white matter carbonic anhydrase could be detected only in oligodendrocytes and their abundant processes. The findings confirmed the oligodendrocyte-myelin unit to be the primary locus of carbonic anhydrase in the normal mouse brain and showed the astrocytes in gray matter normally to be a secondary locus of carbonic anhydrase. The immunostaining in the jimpy mouse brain suggested further that reactive astrocytes, in particular, might be rich in carbonic anhydrase.

Animals↗
PubMed1988

Acetyl-CoA carboxylase in rat brain. I. Activities in homogenates and isolated fractions.

Acetyl-CoA carboxylase (ACC) catalyzes the rate-limiting and/or first committed step in fatty acid biosynthesis. Because fatty acids must be synthesized as components of the galactolipids and phospholipids in myelin, high specific activities of ACC would be expected in brain during myelination and in the myelinating cells, the oligondendroglia, in particular. Under reaction conditions where ACC was linear with time and protein concentration, we found specific activities of 1.7 and 3.1 nmol/min/mg protein in supernatants from forebrains and brainstems, respectively, of 20-day-old rats. In both regions, ACC declined during development, particularly after the age of 20 days. To separate forebrain into discrete fractions containing cells, membrane vesicles, and other components, without destroying the ACC, it was necessary to modify the published methods by adding citrate to the isolation medium and by omitting trypsin. A fraction which sedimented over 1.2 M sucrose showed the highest specific activities and recoveries of ACC. This fraction was rich in small cells, many of which immunostained with antibodies against galactocerebroside and carbonic anhydrase, both of which are localized in oligodendrocytes and immature glial cells. The cells in this fraction also immunostained with antibodies against ACC. The results are consistent with the hypothesis that ACC is an oligodendrocyte-associated enzyme, although it probably is not exclusive to cells of that type.

Acetyl-CoA Carboxylase↗
PubMed1988

Acetyl-CoA carboxylase in rat brain. II. Immunocytochemical localization.

Acetyl-CoA carboxylase (ACC) catalyzes the first and, possibly, the rate-limiting step in fatty acid biosynthesis. Because oligodendrocytes must synthesize large amounts of lipid during myelination, the hypothesis was proposed that ACC might be localized in cells of that type. In sections from the brains of 12-day-old rats, ACC immunostaining was observed in glial cells in white matter and gray matter. These cells resembled carbonic anhydrase-positive oligodendrocytes at mature and immature stages of their development. Cells resembling typical oligodendrocytes were also ACC-positive in white matter from the forebrains and brainstems of 15-17 day-old-rats. In both the gray matter and the white matter of 21-day-old rats there were intensely ACC-positive cells that strongly resembled oligodendrocytes. Oligodendrocytes in the brains of adult rats also were ACC-positive. While recognizing that some ACC must be present at lower levels in other types of cells and at all ages, it was concluded that the present findings are consistent with its primary locus as the oligodendrocytes, particularly during myelination. Further, enrichment of ACC and carbonic anhydrase in the same type of cell suggested that carbonic anhydrase might serve in providing a substrate, bicarbonate, to be utilized by ACC.

Acetyl-CoA Carboxylase↗
PubMed1988

Localization of glial cell antigens in the brains of young normal mice and the dysmyelinating mutant mice, jimpy and shiverer.

Tissue sections from the brains of normal, jimpy, and shiverer mice were immunostained by the peroxidase antiperoxidase method for carbonic anhydrase (CA) and the putative astrocytic "markers" glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP). The cells in normal gray matter that immunostained with anti-CA and anti-GS were similar to one another in size and process elaboration. In the normal gray matter there were relatively few GFAP-positive astrocytes. When present, these cells resembled the CA- and GS-positive cells; however, the GFAP appeared to be concentrated in the astroglial processes, as distinguished from the cell bodies. Glial cell processes, immunostained for CA or GS, surrounded blood vessels and unstained neurons in the normal gray matter. The glial cells in shiverer gray matter were similar to those in the normal gray matter. When stained for GS or GFAP, the glial cells in the jimpy gray matter appeared to be somewhat hypertrophied, and when the glial cells in this mutant were stained for CA, the nuclei appeared to be swollen. It was concluded that some of the CA-positive cells in the gray matter of the normal and of each mutant mouse brain could be astrocytes. The patterns of immunostaining in the white matter emphasized the different complements of glial cells in the mutants. In the normal and shiverer mouse corpus callosum, CA, in particular, was detected only in the oligodendrocytes, their processes, and myelin. However, the data concerning the jimpy mouse suggested that the few CA-positive cells in the corpus callosum of that mutant could be astrocytes.

Animals↗
PubMed1988

Characterization and localization of glutathione-S-transferases in rat brain and binding of hormones, neurotransmitters, and drugs.

Rat brain glutathione-S-transferases are rich in Yb type subunits with major RNA transcripts coding for a relatively uncommon Yb3 form. The Yb-containing isoenzymes of brain cytosol bind glucocorticoids and are covalently labeled with dexamethasone 21-methanesulfonate. Certain neurotransmitters, hormones, and drugs, such as serotonin, dopamine, glucocorticoids, thyroxine, apomorphine, and benzodiazepine derivatives, are effective inhibitors of brain glutathione transferase activity. Immunocytochemical studies show that Yb forms are localized in ependymal cells, subventricular zone cells, astrocytes, tanycytes, and astrocyte foot processes on blood vessels, but Yb was not detected in oligodendrocytes or neurons. Based on their localization and binding properties, brain glutathione-S-transferases have the potential to function in intracellular binding of a variety of compounds and thereby govern their uptake and release in brain, transport to neurons, as well as in their detoxification.

Animals↗
PubMed1988

Carbonic anhydrase immunostaining in astrocytes in the rat cerebral cortex.

Carbonic anhydrase is known to occur in the choroid plexus, oligodendrocytes, and myelin, and to be virtually absent from neurons, in the mammalian CNS; however, there is significant controversy whether it is also present in astrocytes. When brain sections from adult rats were stained for simultaneous immunofluorescence of carbonic anhydrase and the astrocyte marker glutamine synthetase, both antigens were detected in the same glial cells in the cortical gray matter, whereas the oligodendrocytes and myelinated fibers in and adjacent to the white matter showed immunofluorescence only for carbonic anhydrase. Some glial cells in the gray matter also showed double immunofluorescence for carbonic anhydrase and glial fibrillary acidic protein. These results indicate that there is carbonic anhydrase in some astrocytes in the mammalian CNS.

Animals↗
PubMed1987

Immunocytochemical localization of 5'-nucleotidase in myelinated peripheral nerves from the rat.

In sciatic and trigeminal nerves from the rat, 5'-nucleotidase immunostaining was observed on the surfaces of the myelinated fibers and in the membranes encircling the outermost loops of the myelin sheaths, the paranodal loops, and perhaps the inner loops, but neither in the compact myelin nor in the axoplasm. These results, which were consistent with previous biochemical data regarding sciatic nerve, suggest that the function of 5'-nucleotidase in myelinated fibers in the peripheral nervous system may be to promote diffusion of adenosine between the glial and neuronal compartments.

5'-Nucleotidase↗
PubMed1987

Immunocytochemical localization of carbonic anhydrase in myelinated fibers in peripheral nerves of rat and mouse.

Rat sciatic nerve, spinal root, and cranial nerve were immunostained with an antibody against rat brain carbonic anhydrase II (ca), to determine the localization of ca in the rat peripheral nervous system (PNS). Similar methods were applied to mouse nerves to see if that antigen could be detected in the PNS of this species. In rat nerves, intense immunostaining was observed in the axoplasm of many of the myelinated fibers, whereas others were stained less intensely or were negative. A heterogeneous pattern of immunostaining was also found in neuronal perikarya within the ganglia, and in some regions of the ganglia ca immunostaining was found in putative satellite cells and their processes. Ca in rat PNS therefore appears to occur at both neuronal and glial sites, whereas it is exclusively glial in the CNS. In longitudinal sections of some fibers within rat nerves, ca immunostaining could be detected at the inner boundaries of the myelin sheaths. In mouse nerves, axoplasmic staining was observed but it was fainter than in rat nerves. Interspecies differences were most obvious in the dorsal columns of the spinal cord. In rat, intensely stained axons proceeded through the roots into the gracilis or cuneate and often into the gray matter. In mouse, there was much less immunostaining of axons but more intense ca immunostaining in CNS myelin than in the CNS myelin in the rat cord. The implications concerning putative functions of ca in the rodent nervous system are discussed.

Animals↗
PubMed1986

Complement potentiates the degradation of myelin proteins by plasmin: implications for a mechanism of inflammatory demyelination.

A previous finding, that the basic protein in lyophilized bovine myelin was degraded by macrophage-conditioned media in the presence of plasminogen, suggested that the macrophage-secreted plasminogen activator, along with plasminogen, might have a role in destruction of myelin during inflammatory demyelination. To approximate more closely the conditions expected in vivo, plasmin, or macrophage supernatants plus plasminogen, were incubated with freshly homogenized bovine white matter or freshly isolated myelin, as distinguished from lyophilized myelin. Under these conditions basic protein was not degraded. Phospholipase or lysolecithin potentiated the degradation of basic protein in fresh bovine myelin by plasmin; however, the cultured macrophages did not secrete significant amounts of phospholipase and plasminogen activator simultaneously into the culture media after activation with any of several different agents. Recently myelin was shown to activate complement. After preincubation of fresh myelin with guinea pig serum, as a source of complement, the basic and proteolipid proteins were vulnerable to plasmin or to macrophage-conditioned media plus plasminogen. C3-depleted and C4-deficient sera were not effective, suggesting that these complement components were required for the serum effect. Hypothetically, then, degradation of myelin proteins in the CNS could be initiated by plasminogen activator, secreted by infiltrating macrophages, plus complement and plasminogen, which could enter the CNS through lesions in the blood-brain barrier.

Animals↗
PubMed1986

Antibody against mouse liver 5'-nucleotidase immunostains white matter in the adult mouse central nervous system.

An antiserum against rat liver 5'-nucleotidase has been shown to immunostain myelinated fibers and oligodendrocytes in the rat CNS, consistent with evidence for 5'-nucleotidase activity in rat brain myelin and oligodendrocytes (Cammer, Sacchi and Kahn, Devel. Brain Res., 1985, 20: 89-96). However, in the mouse CNS, in which myelin also has 5'-nucleotidase activity, that antiserum stained only blood vessels. To obtain an antibody against the mouse enzyme, 5'-nucleotidase was partly purified from mouse liver membranes by detergent extraction, heat treatment, affinity chromatography, acidification, and ammonium sulfate fractionation. The preparation, which was enriched about 110-fold in 5'-nucleotidase specific activity, compared to the starting extract, was electrophoresed on a preparative slab gel containing Triton X-100, a strip was stained histochemically for 5'-nucleotidase, and the material corresponding to the stained band was used to immunize a rabbit. The immune IgG fraction, but not the preimmune IgG, reacted with mouse brain homogenates. The immune serum gave consistently greater inhibition of 5'-nucleotidase activity in mouse liver homogenates, mouse brain myelin and mouse brain homogenates, but not rat brain or liver homogenates, compared to the preimmune serum. The immune serum, but not the preimmune serum, immunostained white matter in the normal adult mouse brain and spinal cord. The findings suggest that the mouse may have one isozyme of 5'-nucleotidase similar to that in rat with respect to subunit sizes but differing in primary structure at one or more antigenic sites and support previous observations of 5'-nucleotidase activity in myelin from mouse brains and spinal cords.

5'-Nucleotidase↗
PubMed1986

5'-nucleotidase localization in the brains and spinal cords of adult normal and dysmyelinating mutant (shiverer) mice.

Immunocytochemical staining with the antibody against mouse liver 5'-nucleotidase revealed 5'-nucleotidase antigenicity in myelinated fibers in the brains and in myelinated fibers and some interfascicular oligodendroglia in the spinal cords of normal adult mice. Although the 5'-nucleotidase specific activity in adult shiverer mouse CNS tissue homogenates had been shown to be normal, immunocytochemical staining with anti-mouse-5'-nucleotidase could be demonstrated in CNS tissue sections from only 2 out of 10 of the mutant animals. In tissue from these animals the staining, which was relatively faint, was localized specifically to cell-bodies, usually arranged in rows, and to material oriented parallel to nerve fibers. This pattern of immunostaining with anti-5'-nucleotidase resembled the immunostaining with anti-carbonic anhydrase but not with anti-glial-fibrillary-acidic-protein. This suggested that the rows of cells were oligodendrocytes, not astrocytes, and that the material parallel to nerve fibers might consist of oligodendrocyte processes wrapped loosely around axons. The antibody against rat 5'-nucleotidase, as distinguished from mouse, immunostained only the blood vessels in the shiverer mouse CNS, a finding similar to a previous observation in the normal mouse CNS. From these findings it was inferred that the primary loci of 5'-nucleotidase in the shiverer mouse CNS were interfascicular oligodendrocytes, their processes, and blood vessels, and in the normal mouse CNS, the myelin in some tracts, the blood vessels, and some interfascicular oligodendrocytes.

5'-Nucleotidase↗
PubMed1986

Biochemical and immunocytochemical evidence for a deficiency of normal interfascicular oligodendroglia in the CNS of the dysmyelinating mutant (md) rat.

Carbonic anhydrase was assayed and carbonic anhydrase and 5'-nucleotidase were localized in the CNS of myelin-deficient mutant rats and normal littermates. The carbonic anhydrase specific activities were reduced by 61% and 29% in the mutants' forebrains and cerebella, respectively, and the total carbonic anhydrase activity in the spinal cords was reduced by 35%. Immunostained cells were found in gray matter from both normal and mutant rats, but, in the mutants, there was a marked deficiency of interfascicular oligodendrocytes in the regions that are normally occupied by white matter. It is suggested that a developmental study could indicate the step(s) at which normal differentiation of interfascicular oligodendroglia is blocked in this mutant.

5'-Nucleotidase↗
PubMed1985

Oligodendroglial structures and distribution shown by carbonic anhydrase immunostaining in the spinal cords of developing normal and shiverer mice.

The spinal cords of young and adult normal and dysmyelinating mutant (shiverer) mice were immunostained with anticarbonic anhydrase to investigate the distribution of oligodendroglial populations into the gray- and white-matter regions in the developing normal and mutant animals; the morphology of oligodendrocytes and their processes at the light microscopic level in gray matter and white matter; and the apparent gliosis in the gray matter, as well as the white matter, of the mutants. Immunocytochemistry and enzyme assays revealed consistent increases in carbonic anhydrase antigenicity and specific activity in controls and mutants between the ages of approximately 15 days and approximately 60 days. As shown previously in adult animals, oligodendroglia in larger than normal proportions were situated at the periphery of the "white-matter" columns, as compared to gray matter, in the shiverers, with, however, significant numbers of oligodendroglia were heterogeneous with respect to shapes, configuration of processes, and intensity of carbonic anhydrase immunostaining. In the shiverer "white matter" the oligodendrocytes were smaller than normal, and their shapes and arrangement were relatively irregular. In the normal gray matter short oligodendroglial processes appeared to be associated with neuronal perikarya, and those processes were more pronounced at approximately 90 days than at approximately 20 days of age. Background staining in normal gray matter suggested that oligodendroglial processes were, in addition, tightly wound around many axons. In shiverer gray matter the oligodendrocytes were smaller, and their processes appeared to be wrapped more loosely around smaller numbers of conspicuous axons and to be associated less frequently with neuronal perikarya. This finding suggests that the deficiency in the myelin basic protein in the mutant may affect interactions between oligodendrocytes and neurons in the gray matter as well as in the white matter. The astrocytic "marker," glial fibrillary acidic protein, was detected in gray and white matter of shiverers as young as 16 days, and the differences from carbonic anhydrase localization supported the conclusion that the processes enwrapping axons in the shiverer mouse CNS are derived from oligodendrocytes, not astrocytes.

Age Factors↗
PubMed1985

Immunocytochemical localization of 5'-nucleotidase in oligodendroglia and myelinated fibers in the central nervous system of adult and young rats.

Rat central nervous system (CNS) tissue sections were immunostained by the peroxidase-anti-peroxidase (PAP) method using a rabbit serum directed against rat liver 5'-nucleotidase. In paraffin sections from the brains of 60-day-old rats 5'-nucleotidase immunoreactivity occurred in the same white-matter regions as myelin-basic protein immunoreactivity and histological staining of myelin. The immunostaining of cerebral white matter for 5'-nucleotidase was more intense and wide-spread at the age of 120 days than at 60 days, and the choroid plexus and blood vessels were stained consistently. In the paraffin sections from the brains of younger (20-day-old) rats the staining of 5'-nucleotidase in the white matter was faint and patchy. In paraffin sections from spinal cord, 5'-nucleotidase immunoreactivity was observed throughout the lateral white-matter columns and, frequently, in the cell bodies of interfascicular oligodendroglia. Interfascicular oligodendroglia also showed 5'-nucleotidase immunoreactivity in vibratome sections from the CNS tissue of young and adult rats. The findings were consistent with histochemical and biochemical evidence for 5'-nucleotidase in rat brain myelin and oligodendroglia, with substantial increases in activity in the myelin as rats develop from the ages of 20 to 120 days. 5'-Nucleotidase immunoreactivity was not observed in any astrocytes or in oligodendrocytes in the gray matter; however, the enzyme may occur in those glial cells at levels lower than were detectable using the present method.

5'-Nucleotidase↗