Glycosylation of polyclonal and paraprotein IgG in multiple myeloma

It has previously been shown that in multiple myeloma (MM) each IgG paraprotein exhibits a unique oligosaccharide profile. It has been assumed that this results from a clone specific glycosylation machinery. However, the abnormal physiological environment of the bone marrow in this disease may also affect normal plasma cells producing polyclonal IgG. We present data to show that this is so and that, in two cases, the oligosaccharide profile of the polyclonal IgG reflected that of the paraprotein from the same patient rather than that of normal polyclonal IgG.

Induction of oligodendrocyte apoptosis by C2-ceramide

Tumor necrosis factor-alpha induces oligodendrocytes apoptosis, and is known to stimulate the hydrolysis of sphingomyelin to form the lipid mediator, ceramide. These data encouraged us to determine whether ceramide itself is able to induce apoptosis in oligodendrocytes. For this purpose the cell-permeable ceramide analog, C2-ceramide was used. Treatment of bovine oligodendrocyte cell cultures with this compound induced cell death in a time- and concentration-dependent manner. The induction of cell death was specifically associated with the action of C2-ceramide and could not be elicited by dioctanoylglycerol (DC8) or phorbol 12-myristate 13-acetate (PMA). Treatment of the cultures with neutral sphingomyelinase, which increased the hydrolyses of endogenous sphingomyelin, resulted in oligodendrocyte death, whereas exposure of the cells to phospholipase C and A2 did not. C2-ceramide treatment caused DNA fragmentation. Morphologic analysis of the cells showed that C2-ceramide treatment resulted in a loss of their processes, reduction of cell volume, chromatin condensation, and formation of apoptotic bodies. These results indicate that ceramide can induce oligodendrocyte apoptosis, and suggest that sphingolipid metabolism plays a key role in the regulation of this process.

Study of the interaction of the myelin monomeric GTP-binding proteins with other brain proteins

Although several monomeric GTP-binding proteins have been found in myelin, the signaling pathways in which they operate are not known. To define these signaling pathways we searched for specific target proteins that interact with the myelin monomeric GTP-binding proteins. A blot overlay approach was used. Bovine white matter homogenate, myelin, and oligodendrocyte proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted onto nitrocellulose membranes. The presence of proteins that interact with the myelin GTP-binding proteins was explored by incubating those blots with an enriched fraction of 22- and 25-kDa myelin GTP-binding proteins labeled with radioactive guanine nucleotides. When the GTP-binding proteins were in the inactive state (GDP-bound) they interacted with 28-, 47-, and 58-kDa oligodendrocyte polypeptides. Only the 28-kDa protein was present in myelin. In the active state (GTP-bound), they interacted only with a 47-kDa protein in myelin but with 31-, 38-, 47-, 58-, 60-, 68-, and 71-kDa proteins in oligodendrocytes and total homogenate. Under these experimental conditions the 28-kDa protein did not interact with the GTP-binding proteins. The fact that the myelin GTP-binding proteins in the active state formed complexes with a different set of proteins than when in the inactive state is a strong indication that these proteins are effector proteins. With the exception of the 31- and 38-kDa proteins that were detected only in the cytoplasmic fraction, these polypeptides were detected in the cytosolic fraction and total membrane fraction. The 25-kDa GTP-binding protein was present in all the complexes. Immunoblot analysis indicated that the 28-kDa polypeptide is RhoGDI, an effector protein that is known to regulate the activation and movement of several GTP-binding proteins between different cellular compartments. Thus, this study opens the way to identify the macromolecules participating in the myelin signaling pathway involving monomeric GTP-binding proteins.

Antisense oligonucleotide to the 70-kDa heat shock cognate protein inhibits synthesis of myelin basic protein

Transfection of rat oligodendrocytes with an oligonucleotide sequence complementary to the mRNA encoding the initial ten amino acids of the rat 70-kDa heat shock cognate protein (HSC70) resulted in a rapid (within 24 h) and significant reduction in HSC70 synthesis (69% of control cells transfected with sense oligonucleotide). A further decrease to approximately 44% of controls was detected after 2 days. At that time, HSC70 protein content fell to approximately 49% of controls, and a significant reduction in the synthesis of myelin basic protein (MBP) was first detected (66% of controls). After 5 days, HSC70 synthesis returned to control levels. As HSC70 protein content recovered, so did the synthesis of MBP. Throughout the 5-day experimental period, only minor changes were detected in cell morphology, overall pattern of protein synthesis and the synthesis and content of proteolipid protein (PLP) and the pi isoenzyme of glutathione-S-transferase (pi). These data show that when HSC70 protein content is sufficiently reduced by antisense oligonucleotide, synthesis of MBP (but not PLP or pi) is correspondingly down-regulated, and provide evidence consistent with the role of HSC70 as a chaperone for MBP.

Differentiation of glial precursor cells from developing rat brain in vitro

We have previously shown that enriched preparations of oligodendrocytes from mature bovine brain or 30d rat brain contain 4-10% ganglioside-GD3+ glial precursor cells, which differentiate into astrocytes in culture. These findings are in contrast to those described by others in cultures of neonatal rat brain, which contain precursors that differentiate into both astrocytes and oligodendrocytes. We have extended this study to determine whether the properties of glial precursor cells vary during development. Cells isolated by the same technique from 5-, 10- and 20-day-old rats, were placed in culture and double-immunostained at 1,2,3,6 and 10 days in vitro (DIV) for GD3/glial fibrillary acidic protein (GFAP), galactosylceramide (GC)/GFAP, GD3/GC, GD3/antigen O4, GC/O4 and GFAP/O4. After 1 DIV the isolates from 5 day rats contained 30% GD3+ cells, 1% oligodendrocytes (GC+) and 3.5% astrocytes (GFAP+). The corresponding percentages from 10 day rats were: 35% GD3+, 3% GC+ and 3% GFAP+; and from 20 day rats: 28% GD3+, 35% GC+ and 1% GFAP+. Thus the number of oligodendrocytes in the initial isolate increased dramatically between 10 and 20 days. At all 3 ages immature cells were a major component of the total isolate. GFAP+ cells increased rapidly in all cultures. In all cultures the numbers of GFAP+/GD3+ cells reached a maximum and then declined coincident with the increase of GFAP+/GD3- cells, but there were many more of these double-stained cells in cultures from 20 day rats. Moreover, all cultures at 1 DIV contained some GFAP+/GD3- cells. Thus astrocytes appeared to derive both from pre-existing GFAP+/GD3- cells and from GD3+ cells, the latter pathway being more significant in the older rats. GC+ cells increased in cultures prepared from 5 day and 10 day rats, but remained relatively constant in cultures from 20 day rats. The number of GD3+/O4+ cells decreased coincident with an increase of GC+/O4+ cells (all GC+ cells were O4+), but the number of GC+/GD3+ cells was insignificant in any culture from any age animal. These findings in developing animals support the scheme shown by others in neonates that oligodendrocytes derive from GD3+ cells via O4+/GC-intermediate cells. These data show that more GD3+ cells differentiate into oligodendrocytes in 5- and 10-day-old animals than in 20-day-old animals, and a larger percentage differentiate into astrocytes in 20-day-old animals than in the younger animals. The most reasonable explanation of these results is that two committed populations of GD3+ precursor cells exist in the brain, and that the ratio of these populations changes during development. The implication of this conclusion is that bipotential progenitor cells do not persist beyond the neonatal period, but become committed to separate lineages during development.

Widespread differentiation stage-specific expression of the gene encoding phosphoprotein p19 (metablastin) in mammalian cells

p19 is a highly conserved 19 kD cytosolic protein that undergoes phosphorylation in response to diverse extracellular factors in mammalian cells. Its expression is abundant in brain and testis and is developmentally regulated. To gain insights regarding its function, we analyzed the expression of p19 mRNA in a variety of cell types during induction of differentiation. Murine erythroleukemia cells showed a moderate increase followed by a marked decrease in the abundance of p19 mRNA during induction of differentiation. In murine C2 myoblasts and primary fetal rat osteoblasts, p19 mRNA was abundant in replicating cells and decreased to undetectable levels during differentiation. In resting human peripheral blood lymphocytes, p19 mRNA was virtually undetectable but was strongly induced during blast transformation of both B and T cells. In rat liver, p19 mRNA was abundant on embryonic day 17 and decreased during early postnatal development. Upon fractionation of adult rat liver cells by centrifugal elutriation, p19 mRNA was not detected in hepatocytes while a low level was observed in a fraction enriched in non-parenchymal epithelial cells. CCl4-induced liver regeneration resulted in induction of p19 mRNA in hepatocytes. Primary cultures of embryonic and neonatal rat brain were analyzed by indirect immunofluorescence using co-staining with stage-specific markers. p19 expression was restricted to immature neurons and oligodendrocyte precursors. In contrast to the other cell types examined, the neuronal and glial precursors that express p19 were shown, using BrdU labeling, to be postmitotic both in primary culture and in vivo. The data demonstrate widespread, stage-specific expression of p19 and suggest that the protein exerts a general, lineage-independent function during induction of differentiation of mammalian cells. In view of the available evidence on the stimulation of serine phosphorylation of p19 by several growth factors, our working hypothesis is that phosphorylation of p19 may be involved in the mechanism by which growth factors control cell differentiation.

Non-specific oligodendrocyte cytotoxicity mediated by soluble products of activated T cell lines

Supernates from myelin basic protein (MBP)-reactive T cell lines have been tested by a battery of assays for cytotoxicity against oligodendrocytes in vitro. All supernates tested demonstrated cytotoxic activity in both a dose- and time-dependent manner that ranged from 29.1% to 55.8% after 48 h incubation. Oligodendrocyte cytotoxicity mediated by MBP-reactive T cell lines was not antigen specific since lines reactive with purified protein derivative (PPD) of tuberculin showed similar cytotoxicity. Supernates cytotoxic to oligodendrocytes were equally effective against syngeneic and non-syngeneic target cells, but had no effect upon astrocytes. Neutralization studies revealed that oligodendrocyte cytotoxicity mediated by MBP-reactive T cell supernates could only be partially attributed to lymphotoxin/tumor necrosis factor activity, and was not associated with perforin, serine proteinase or N-methyl-D-aspartate (NMDA) receptor agonists.

Cytokine cytotoxicity against oligodendrocytes. Apoptosis induced by lymphotoxin

The cytotoxic effect of recombinant human cytokines was tested on glial cells cultured from mature bovine brain. Lymphotoxin (LT) and TNF induced injury to oligodendrocytes in a time and dose-dependent fashion. The other cytokines tested, IFN-gamma, IL-6, and IL-2, did not affect oligodendrocytes in culture over a 72-h observation period. None of the cytokines injured astrocytes cultured from the same source. LT showed a much more potent cytotoxicity than TNF toward oligodendrocytes; cytotoxic changes were noted earlier (24 h) and at lower units of activity. Morphologic studies showed that the LT-mediated effects were associated with early retraction of cell processes, depolymerization of F-actin and subsequent nuclear degeneration. Lack of early cytoplasmic membrane injury as measured by 51Cr release and electron microscope studies demonstrating nuclear disintegration suggested an apoptotic mechanism of oligodendrocyte injury evoked by LT, which was supported by DNA integrity assay. These results demonstrate that LT possesses potent cytotoxic activity against oligodendrocytes and that the major mechanism involved in this process is DNA fragmentation.

Tumor necrosis factor-induced proliferation of astrocytes from mature brain is associated with down-regulation of glial fibrillary acidic protein mRNA

Previous results from this laboratory have shown that tumor necrosis factor (TNF) is mitogenic for bovine astrocytes in chemically defined (CD) medium. The maximum mitogenic response was detected with 200 U/ml at 48 h. We have now extended these studies to assess the effect of TNF on message levels for the intermediate filament proteins glial fibrillary acidic protein (GFAP) and vimentin. The results have shown that, whereas TNF had only a slight effect on vimentin mRNA, TNF induced a marked decrease to 4.3 +/- 2.0% of controls in GFAP mRNA which was both time and dose dependent. The lowest effective dose was 50 U/ml and the maximal effective dose was 200 U/ml. Kinetic analysis of this response demonstrated that a marked decrease in GFAP mRNA was present at 12 h and continued to decrease through 72 h. To determine the reversibility of the TNF effect, astrocyte cultures were exposed to 200 U/ml TNF for varying periods of time and then cultured in fresh CD medium. A 1-h pulse with TNF was sufficient to reduce GFAP mRNA levels when measured 24 h later. However, cultures incubated with 200 U/ml TNF for 48 h followed by incubation in CD medium without TNF for 7 days showed that GFAP mRNA levels had returned to 60% of the control values. Nuclear runoff assays showed that the effect of TNF on GFAP mRNA was at the posttranscriptional level. Polyacrylamide gel electrophoretic analysis of astrocyte cytoskeletal proteins demonstrated that GFAP levels were reduced after a 5-day incubation with 200 U/ml TNF whereas protein levels of vimentin and actin were not significantly changed.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokine cytotoxicity against oligodendrocytes. Apoptosis induced by lymphotoxin

The cytotoxic effect of recombinant human cytokines was tested on glial cells cultured from mature bovine brain. Lymphotoxin (LT) and TNF induced injury to oligodendrocytes in a time and dose-dependent fashion. The other cytokines tested, IFN-gamma, IL-6, and IL-2, did not affect oligodendrocytes in culture over a 72-h observation period. None of the cytokines injured astrocytes cultured from the same source. LT showed a much more potent cytotoxicity than TNF toward oligodendrocytes; cytotoxic changes were noted earlier (24 h) and at lower units of activity. Morphologic studies showed that the LT-mediated effects were associated with early retraction of cell processes, depolymerization of F-actin and subsequent nuclear degeneration. Lack of early cytoplasmic membrane injury as measured by 51Cr release and electron microscope studies demonstrating nuclear disintegration suggested an apoptotic mechanism of oligodendrocyte injury evoked by LT, which was supported by DNA integrity assay. These results demonstrate that LT possesses potent cytotoxic activity against oligodendrocytes and that the major mechanism involved in this process is DNA fragmentation.

Glutamine synthetase in oligodendrocytes and astrocytes: new biochemical and immunocytochemical evidence

The results of recent immunocytochemical experiments suggest that glutamine synthetase (GS) in the rat CNS may not be confined to astrocytes. In the present study, GS activity was assayed in oligodendrocytes isolated from bovine brain and in oligodendrocytes, astrocytes, and neurons isolated from rat forebrain, and the results were compared with new immunochemical data. Among the cells isolated from rat brain, astrocytes had the highest specific activities of GS, followed by oligodendrocytes. Oligodendrocytes isolated from white matter of bovine brain had GS specific activities almost fivefold higher than those in white matter homogenates. Immunocytochemical staining also showed the presence of GS in both oligodendrocytes and astrocytes in bovine forebrain, in three white-matter regions of rat brain, and in Vibratome sections as well as paraffin sections.

Proliferation of astrocytes in vitro in response to cytokines. A primary role for tumor necrosis factor

The effect of cytokines on astrocytes cultured from mature bovine brain was determined both in a serum-containing medium and in a chemically-defined medium. The results showed that in serum-free medium, human TNF and, to a lesser degree, IL-6 and lymphotoxin, were mitogenic for astrocytes. Increased uptake of [3H]thymidine could be detected within 36 h in vitro and its presence in astrocytes was confirmed by autoradiography. In contrast, neither IL-1 alpha nor IL-1 beta induced astrocyte proliferation in serum-free medium but showed some synergistic effect with serum after 72 h. The proliferative effect of TNF and IL-6 was confirmed by cell counting. None of the cytokines tested was toxic for astrocytes as measured by 51Cr release. No mitogenic effect for oligodendroglia, purified from the same source, was detected. The results support a role for products of activated inflammatory cells in the development of astrocyte proliferation that may contribute to the reactive gliosis found in white matter diseases of the central nervous system such as multiple sclerosis.

Proliferation of astrocytes in vitro in response to cytokines. A primary role for tumor necrosis factor

The effect of cytokines on astrocytes cultured from mature bovine brain was determined both in a serum-containing medium and in a chemically-defined medium. The results showed that in serum-free medium, human TNF and, to a lesser degree, IL-6 and lymphotoxin, were mitogenic for astrocytes. Increased uptake of [3H]thymidine could be detected within 36 h in vitro and its presence in astrocytes was confirmed by autoradiography. In contrast, neither IL-1 alpha nor IL-1 beta induced astrocyte proliferation in serum-free medium but showed some synergistic effect with serum after 72 h. The proliferative effect of TNF and IL-6 was confirmed by cell counting. None of the cytokines tested was toxic for astrocytes as measured by 51Cr release. No mitogenic effect for oligodendroglia, purified from the same source, was detected. The results support a role for products of activated inflammatory cells in the development of astrocyte proliferation that may contribute to the reactive gliosis found in white matter diseases of the central nervous system such as multiple sclerosis.

Maintenance of DNA methylation level in SV40-infected human fibroblasts during their in vitro limited proliferative life span

Methylation level as expressed by the molar ratio of 5-methylcytosine content to the combined content of cytosine and 5-methylcytosine was determined by HPLC and uv adsorption of cellular DNA extracted from SV40-infected and pretransformed MRC-5 human diploid fibroblasts (HDFs) during their limited in vitro life span. The level decreased slightly during early passages, and then was maintained within a certain range in the subsequent pretransformed stage of serial passages. When HDFs were treated with 5-aza-2'-deoxycytidine (5-aza-CdR) at an effective concentration shortly after the SV40 infection, the level decreased and then increased or was maintained again within a certain range in the subsequent pretransformed state. The proliferative life span potential of SV40-infected HDFs was not significantly decreased by the 5-aza-CdR treatment. These results are in contrast to the established observations for uninfected HDFs, that methylation level decreases during serial passages, and that, after treatment with 5-aza-CdR, the level, as well as the proliferative life span, is decreased in comparison to untreated populations. These results show that SV40-infected pretransformed HDFs are in an intermediate state between normal finite growth and an established permanent line, in that they retain limited in vitro cell proliferation, while acquiring the ability to maintain methylation levels.

Ganglioside and lipid composition of bulk-isolated rat and bovine oligodendroglia

We have examined the ganglioside composition of 30-day and 60-day postnatal rat oligodendroglia, adult bovine oligodendroglia, gray matter, white matter, and myelin and also the total lipid composition of the oligodendroglial preparations. The ganglioside patterns of rat and bovine oligodendroglia, as previously found for human oligodendroglia, were more complex than those of myelin. These data indicate that oligodendroglial perikarya can synthesize many brain type gangliosides, not all of which are incorporated into the compact myelin. Alternatively, the ganglioside composition of myelin may be altered in situ by the myelin-associated neuraminidase. In these two species, as in human, GM4 appears specific to oligodendroglia and myelin, while GD3 and GM3 are enriched in oligodendroglia but not myelin. In bovine oligodendrocytes GD3 is the major ganglioside. The total lipid concentration, as well as the percentage of cholesterol, sphingomyelin, phosphatidylinositol, and phosphatidylserine, differ for 30- and 60-day-old rat oligodendroglia and may be developmentally correlated with changes in myelin composition during myelinogenesis. There are also marked differences in the lipid composition of bovine oligodendroglia compared to rat oligodendroglia, with the former having more galactolipid and less ethanolamine phosphoglycerides.

Astrocytes cultured from mature brain derive from glial precursor cells

We have previously shown that enriched preparations of oligodendrocytes from either mature bovine brain or 30-d-old rat brain, when cultured in serum-free medium, yield mixed cultures of oligodendrocytes and astrocytes even though no GFAP+ cells were present after 24 hr in culture (Norton et al., 1986, 1988). To test the possibility that the astrocytes in these cultures arose from glial precursor cells, we followed the expression of ganglioside GD3, galactosylceramide (GC), glial fibrillary acidic protein (GFAP), and vimentin in the cultures. GD3 has already been shown to be a marker of immature neuroectodermal cells, which in the postnatal brain are glial progenitor cells (Goldman et al., 1984, 1986). The cultures from both species contained at 1 DIV only two populations of cells; 90-95% GC+/GD3- oligodendrocytes and 4-10% GD3+/GC- small, round cells. With time, the oligodendrocytes remained GD3-/GFAP-/vimentin-. The kinetics of antigen expression of the GD3+ cells could best be interpreted by the following sequence: (sequence; see text) We interpret these results to show that the astrocytes arose from a small population of GD3+ glial precursor cells present in the brain that were co-isolated with oligodendroglia. No evidence was obtained that these GD3+ cells could also differentiate into oligodendrocytes.

Gangliosides of cultured astroglia

Cultured astrocytes prepared from newborn rat brain and 13-day-old chick embryonic brain were analyzed qualitatively and quantitatively for ganglioside content. All preparations contained approximately the same total level: 2.4-3.4 micrograms N-acetylneuraminic acid (NeuAc)/mg protein. In contrast, the value for primary cultures of neurons from chick embryonic brain was 5.9. The non-hexosamine-containing species, GM3 and GD3, comprised 75-85% of the total in astroglial cultures, the remainder consisting mainly of structural types other than the gangliotetraose series; choleragenoid assay revealed the latter to be virtually absent or to comprise at most a few percent. Deficiency of gangliotetraose synthesizing ability was indicated by the very low level of UDP-GalNac:GM3 N-acetylgalactosaminyltransferase detected in the cells. Treatment of cultured astrocytes with astroglial growth factor 2 or dibutyryl cyclic AMP caused little if any change in quantity or pattern of gangliosides. The large majority of cells stained in a manner characteristic of astrocytes: positive for glial fibrillary acidic protein, negative for galactosyl ceramides. Staining with cholera toxin and anti-GM1 antibody was essentially negative, as was that with tetanus toxin, A2B5 monoclonal antibody, and antibody to GD3. All evidence thus points to cultured astrocytes of rat and chick brain containing appreciable gangliosides, most of which are GM3 and GD3 with the majority of the remainder comprising structures other than the gangliotetraose type.

Ganglioside content of astroglia and neurons isolated from maturing rat brain: consideration of the source of astroglial gangliosides

Previous biochemical and histochemical studies have failed to clarify the nature or quantity of gangliosides in CNS astrocytes. Using improved methodologies for bulk isolation of both neurons and astrocytes as well as for ganglioside purification, we find significantly higher ganglioside concentration in astrocytes and very similar thin-layer chromatography (TLC) patterns for the two cell types. However, in vivo labeling of glycoconjugates via intracerebral injection of [3H]glucosamine prior to cell isolation revealed a different picture: whereas glycoproteins were well-labeled in both cell types after labeling periods of 1-2 h, gangliosides were appreciably labeled only in neurons. With longer time periods (8-48 h) between injection and sacrifice, there was convergence of specific radioactivity of gangliosides from the two isolated cell preparations. These changes are compared to those observed in synaptosomes and microsomes that were isolated simultaneously. The results suggest limited ganglioside synthetic ability in astrocytes as compared to neurons, a conclusion supported by assay of UDP-galNAc:GM3 N-acetylgalactosaminyltransferase in the isolated cells. Nevertheless, the presence of ganglioside GM1 in a substantial portion of bulk-isolated astrocytes was demonstrated by indirect immunofluorescent detection of cholera toxin binding. Ideas on the reconciliation of these apparently contradictory phenomena, including the possibility of intercellular transfer and/or phagocytosis are discussed.

Pure astrocyte cultures derived from cells isolated from mature brain

Enriched preparations of oligodendrocytes, isolated either from adult bovine brain or from 30-day-old rat brain, eventually yield cultures in MEM-15% calf serum that contain, in addition to oligodendrocytes, proliferating astrocytes and variable numbers of fibroblast-like cells. If these cultures are switched to a serum-free defined medium during the 1st week, mixed cultures containing only oligodendrocytes and astrocytes are obtained. Bovine cultures can be replated and purified by selective adhesion to yield cultures that are greater than 99% astrocytes; similar procedures were not successful with rat cultures. Cytoskeletal preparations of the purified astrocyte cultures from mature bovine brain contain both vimentin and glial fibrillary acidic protein (GFAP), but vimentin is by far the major intermediate filament protein. Thus, the intermediate filament composition of these astrocytes is similar to that of astrocytes in primary cultures obtained from neonatal rat brain. Immunofluorescent studies of these cultures at 24 hr in vitro show that there are no GFAP+ cells in cultures of either species; the bovine cultures contain greater than 95% GC+ cells; and the rat cultures contain 90% GC+ cells. After a few days in vitro flat cells appear that are vimentin+/GFAP-/GC-. In serum-free medium these cells eventually become vimentin+/GFAP+. We propose that the astrocytes that grow in these cultures arise from a population of glial precursor cells, which are present even in adult brain and are isolated together with oligodendroglia, and that they do not derive from contaminating mature astrocytes. Thus, the astrocytes in our cultures may have the same origin as astrocytes grown in culture from dissociated neonatal brain.

Differential expression of isoforms of the regulatory subunit of type II cAMP-dependent protein kinase in rat neurons, astrocytes, and oligodendrocytes

The RII-B isoform of the regulatory subunit (R) of cAMP-dependent protein kinase II is abundantly and selectively expressed in cerebral cortex (Erlichman, J., Sarkar, D., Fleischer, N., and Rubin, C. S. (1980) J. Biol. Chem. 255, 8179-8184). In contrast to the cytosolic RII-H isoform from heart and other non-neural tissues, a substantial fraction of cerebral cortex RII-B is tightly associated with cell organelles. In order to study the cellular basis for the localization and abundance of RII-B in this complex and heterogeneous tissue, rat cerebral cortex was fractionated into highly purified populations of neurons, astrocytes, and oligodendrocytes. In neurons and astrocytes more than 80% of the total cAMP-binding activity is contributed by RII subunits, whereas the myelin-producing oligodendrocytes contain nearly equal proportions of RI (from protein kinase I) and RII. Approximately 70% of RII and RI subunits are associated with the particulate fraction in each of the three types of brain cells. The nature of the RII isoforms expressed in the cytosolic and particulate fractions of the purified brain cells was established by performing Western immunoblot and indirect immunoprecipitation analyses with selective and sensitive polyclonal antibodies directed against RII-B. Astrocytes and neurons exhibit high levels of RII-B, whereas oligodendrocytes contain the RII-H isoform. Thus, the expression of RII isoforms is not uniform among brain cells that are anatomically and developmentally related. Rather, it appears that RII-B and RII-H are expressed in a cell-specific fashion within cerebral cortex and this might reflect an RII-mediated adaptation of protein kinase II to the specialized metabolic and functional roles of neurons, astrocytes, and oligodendrocytes.

Experimental autoimmune encephalomyelitis. Augmentation of demyelination by different myelin lipids

Alterations in the effect of a known encephalitogenic dose of myelin basic protein (MBP) when inoculated in combination with various myelin lipids have been examined in guinea pigs. A previous study demonstrated that, when MBP was given with galactocerebroside, it produced an acute autoimmune encephalomyelitis similar to that induced by whole white matter in which both inflammation and demyelination were features of the central nervous system lesions. MBP alone, on the other hand, resulted in inflammation only, without demyelination. The present study examined combinations of MBP with the myelin lipids galactocerebroside, sulfatide, ethanolamine phosphoglycerides, and serine phosphoglycerides. The lipids were given with or without MBP, in the same ratio as in intact central nervous system myelin, and were emulsified with complete Freund's adjuvant. An additional group received galactocerebroside and bovine serum albumin in complete Freund's adjuvant. These groups were compared with animals receiving either bovine white matter or MBP in complete Freund's adjuvant. Clinical autoimmune encephalomyelitis was observed in animals receiving bovine white matter, MBP, and all lipid-MBP emulsions; the bovine white matter, galactocerebroside/MBP, sulfatide/MBP, and ethanolamine phosphoglycerides/MBP groups demonstrated central nervous system lesions with a similar picture consisting of inflammation with demyelination, whereas inflammation without demyelination was seen in the MBP and serine phosphoglycerides/MBP groups. Thus, the addition of myelin lipids to MBP leads to the augmentation of demyelination in autoimmune encephalomyelitis lesions in the guinea pig. This might suggest that the immune response against MBP is enhanced by other myelin components. The relevance of these findings to human demyelinating disorders is discussed.

The long term culture of bulk-isolated bovine oligodendroglia from adult brain

Oligodendroglia isolated from adult bovine brain by the method of Farooq et al. could be plated on polylysine-coated plastic dishes with an efficiency of 55-80%, and maintained in culture for as long as 4 months. The addition of cytosine arabinoside to the nutrient medium resulted in cultures that were approximately 90% oligodendroglia and 10% large fibroblasts. From 50 g of white matter 100-160 X 10(6) oligodendroglia, containing approximately 6-10 mg protein, could be obtained in culture. These small round cells started to send out processes at 5 days in vitro and by 2 weeks they formed an extensive network of processes. By immunofluorescence, all cells of this morphology were positive for galactocerebroside (GC) and myelin basic protein (MBP), and negative for glial filament protein and fibronectin. Most of the large flat cells were positive for fibronectin and negative for GC, MBP and glial filament protein. As the cultures aged the oligodendroglia tended to clump and blebs formed on the surface of both perikarya and processes. By 4 months they showed evidence of degeneration and detached from the substrate. Electron microscope examination showed that the cells had the appearance typical of oligodendroglia in situ. The somata were round to elliptical, with eccentrically placed nuclei, and were larger than freshly isolated cells. They grew directly on the substrate or on the surface of the fibroblasts. In older cultures the cells formed tight nests. The somata were enveloped by sheets of oligodendrocyte cytoplasm, sometimes having a myelin-like appearance. Gap junctions and small desmosomes were seen between oligodendroglial processes and between oligodendroglia and fibroblasts. The cytoplasm was characterized by a prominent Golgi apparatus, many mitochondria and lysosomes, scattered rough endoplasmic reticulum, free ribosomes, frequent centrioles and an abundance of microtubules. In cells from older cultures large vacuoles were common, and rarely they had multilamellar walls with alternating major and minor dense lines resembling myelin.

Carbonic anhydrase, 5'-nucleotidase, and 2',3'-cyclic nucleotide-3'-phosphodiesterase activities in oligodendrocytes, astrocytes, and neurons isolated from the brains of developing rats

The activities of three myelin-associated enzymes, carbonic anhydrase, 5'-nucleotidase, and 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNP), were measured in oligodendrocytes, neurons, and astrocytes isolated from the brain of rats 10, 20, 60, and 120 days old. The carbonic anhydrase specific activity in oligodendrocytes was three- to fivefold higher than that in brain homogenates at each age, and, at all the ages, low activities of this enzyme were measured in neurons and astrocytes. The oligodendrocytes and astrocytes from the brains of rats at all ages had higher activities of the membrane-bound enzyme 5'-nucleotidase than was observed in neurons. In oligodendrocytes from 10- and 20-day-old rats, the 5'-nucleotidase activity was two-to threefold the activity in the homogenates (i.e., relative specific activity = 2.0-3.0), and the relative specific activity of this enzyme in the oligodendrocytes declined to less than 1.0 at the later ages, concomitant with the accumulation of 5'-nucleotidase in myelin. The CNP activity was always higher in oligodendrocytes than in neurons, but not appreciably different from that in astrocytes from 20 days of age onward. The relative specific activity of CNP was highest in the oligodendrocytes from 10-day-old rats but was lower, at all ages, than we had observed in bovine oligodendrocytes. These enzyme activities in oligodendroglia are quite different in amount and developmental pattern from those reported previously for myelin.

Glycerol phosphate dehydrogenase, glucose-6-phosphate dehydrogenase, and lactate dehydrogenase: activities in oligodendrocytes, neurons, astrocytes, and myelin isolated from developing rat brains

Glycerol phosphate dehydrogenase (GPDH), glucose-6-phosphate dehydrogenase (G6PDH), and lactate dehydrogenase (LDH) activities were determined in oligodendrocytes, neurons, and astrocytes isolated from the brains of developing rats. The activity of each enzyme was significantly lower in both neurons and astrocytes than in oligodendrocytes. The GPDH activity in oligodendrocytes increased more than 4-fold during development, and at 120 days cells of this type had 1.4-fold the specific activity of forebrain homogenates. The G6PDH activities in oligodendrocytes from 10-day-old rats were 1.4-fold the activities in the forebrain homogenates. The activities of this enzyme in oligodendrocytes were progressively lower at later ages, such that at 120 days the cells had 0.8 times the specific activities of homogenates. The oligodendrocytes had 0.6 times the homogenate activities of LDH at 10 days, and this ratio had decreased to 0.2 by 120 days. These enzymes were also measured in myelin isolated from 20-, 60-, and 120-day-old rats. By 120 days the specific activities of G6PDH and LDH in myelin were less than 8% of the respective activities in homogenates. The GPDH activity in myelin was, however, at least 20% the specific activity in the homogenates, even in the oldest animals. It is proposed that LDH could be used as a marker for oligodendroglial cytoplasm in subfractions of myelin and in myelin-related membrane vesicles.

Sialosyltransferase activity and specificity in the biosynthesis in vitro of sialosylgalactosylceramide (GM4) and sialosyllactosylceramide (GM3) by rat astrocytes, neuronal perikarya, and oligodendroglia

Total homogenates of astrocytes, neuronal perikarya, and oligodendroglia isolated from rat brain exhibited sialosyltransferase activity in the biosynthesis in vitro of GM3 from lac-cer and CMP-NeuNAc. This activity was highest in neuronal perikarya. In contrast, only oligodendroglia were found to be capable of catalyzing the transfer of NeuNAc from CMP-NeuNAc to gal-cer to form GM4. This activity was about three fold higher in oligodendroglia from 10-day-old rat brain than in those from 60-day-old animals; an intermediate activity was observed in oligodendroglia from 20-day-old rats. Purified preparations of myelin from 14-day-old rat cerebrum, cerebellum, and spinal cord did not show activity in the synthesis of either GM3 or GM4.

Augmentation of immune-mediated demyelination by lipid haptens

The encephalitogenic effects of bovine galactocerbroside and total myelin lipids given in the presence or absence of a known encephalitogenic dose of bovine myelin basic protein (MBP) in complete Freund's adjuvant have been examined in Hartley strain guinea pigs. The lipid haptens and MBP were given in the ratio in which they occur in intact myelin and were compared with experimental allergic encephalomyelitis (EAE) induced by whole bovine white matter in complete Freund's adjuvant. Clinically, bovine white matter- and MBP-induced EAE were similar, but in lesions in the central nervous system. Lipid/complete Freund's adjuvant emulsions were ineffective both clinically and histologically. In combination with MBP, galactocerebroside and total myelin lipids induced an EAE as severe as MBP-induced disease except that central nervous system lesions also showed demyelination. When given separately into opposite hindfeet, the lipid haptens and MBP produced EAE, but the lesions were not demyelinative. It appears, therefore, that lipid haptens have an augmenting effect on MBP when given in the same emulsion and produce central nervous system lesions which are both inflammatory and demyelinative.

Properties of bovine oligodendroglia isolated by a new procedure using physiologic conditions

A new class of procedures, previously shown to permit the isolation of pure oligodendroglia from whole rat cerebrum, has been applied with equal or greater success for the bulk isolation of this cell type from bovine white matter. Thus, the generality of this approach has been demonstrated. The bovine preparations have a purity of greater than 90% intact, phase-bright oligodendroglia and are obtained in a yield of 8 x 10(6) cells per gram of white matter. Within 1 day it is possible to obtain a preparation containing 60 mg of protein from a single cell type. These cells show a higher degree of ultrastructural preservation of all cytoplasmic constituents than previously obtained. The values for protein (33 pg/cell), DNA (5.4 pg/cell), and lipid (5-6 pg/cell) are very similar to those obtained with an earlier procedure. The cell lipids are rich in galactolipid, which comprises 20% of the total. The activity of the "myelin-specific" enzyme, 2',3'-cyclic nucleotide 3'-phosphohydrolase (EC 3.1.4.37), is 4.7 mumol/min/mg protein, similar to that obtained previously for isolated oligodendroglia and about 25-40% of that found in myelin. The activity of 5'-nucleotidase (EC 3.1.3.5) in the cells is about 10% of that in myelin or white matter.

Encephalitogenic properties of purified preparations of bovine oligodendrocytes tested in guinea pigs

The present study has investigated central nervous system disease in guinea pigs inoculated with emulsions containing purified preparations of bovine oligodendroglia and their fractions isolated with or without trypsinization, whole bovine white matter or myelin basic protein (MBP). The MBP content of the oligodendroglial fractions was determined by radioimmunoassay. It was found that oligodendroglia prepared from trypsinized fresh brain contained minute amounts of MBP and did not induce disease. The corresponding cell fraction from non-trypsinized frozen brain was rich in MBP and induced disease. Bovine white matter and MBP induced typical experimental allergic encephalomyelitis (EAE). The structural preservation of the non-encephalitogenic trypsinized MBP-poor cells was very good and that of the encephalitogenic MBP-rich non-trypsinized cells very poor. It has been concluded that the encephalitogenicity observed was due to MBP, rather than to a specific oligodendroglial antigen.

The isolation of cerebral neurons with partial retention of processes

A novel tissue disaggregation technique has been devised which permits the isolation of neurons with fairly extensive processes attached. Cortex is dissociated by aspiration through nozzles of decreasing size followed by agitation on a vortex mixer, rather than by the usual technique of forcing tissue through sieves. After each aspiration step, dissociated cells are separated from undisrupted tissue by coarse filtration and the latter is subjected to repeated treatment. This prevents unnecessary trauma to the free cells. After disruption is complete, small pieces of undisrupted tissue are removed from the cell suspension by floating on the foam created by degassing the suspension under vacuum. Cells are purified by conventional velocity-gradient centrifugation. This procedure has been applied successfully to fresh rat brain, with or without a preincubation with trypsin, frozen human brain and frozen bovine brain. The cell yields from rat brain were comparable to or better than, those obtained by other procedures (37 X 10(6) cells/g brain) while the purity was comparable. Cell yields from human brain were similar to those from rat brain but the purity was lower. The lowered particle purity of human and bovine cells can probably be attributed to the conditions of storage of the tissue and to trapping of free nuclei in the meshwork of dendritic processes. Values are given for the amount of protein, RNA and DNA per cell.

Severity of clinical manifestations of bilharziasis and egg output among children aged 4-5 years in the Egypt-49 project area

This paper describes a simple schedule which can be used to provide a numerical measure of the severity of infection with S. haematobium, S. mansoni or both, and compares the results obtained by use of this schedule and by use of egg counts. A check list gives a number of clinical signs and symptoms, some of which may be graded according to severity. A "severity factor" is assigned to each sign and symptom, such that the maximum possible score obtainable by summing the individual severity factors is 100. The disease is classified, on the basis of the total score, as asymptomatic, mild, moderate, severe or very severe. This method of grading has been tested on a group of 239 Egyptian children aged 4-5 years for whom egg counts were already available. The results are not conclusive, owing to the relatively small size of the sample studied, but they would seem to indicate that the method of clinical grading used will have to undergo considerable modification before it is suitable for practical use.

The effect of area-wide snail control on the endemicity of bilharziasis in Egypt

Molluscicides applied to two areas near Alexandria had a significant effect in reducing both incidence and prevalence of Schistosoma haematobium and S. mansoni infections. No decrease in either measure of endemicity was found in an adjacent untreated area. Bayluscide and sodium pentachlorophenate were equally effective in interrupting the transmission of S. haematobium, but Bayluscide was more effective against S. mansoni, probably because of the difficulty of applying sodium pentachlorophenate to drains, which are the primary habitats for the intermediate hosts of S. mansoni. The authors believe that the present experiment provides strong evidence of the interruption of transmission of bilharziasis in the Nile Valley or Delta.

The epidemiology of Schistosoma haematobium and S. mansoni infections in the Egypt-49 project area. 3. Prevalence of bilharziasis in relation to certain environmental factors

The influence of the size and location of communities in relation to the different types of watercourse, the availability of a protected water supply, types of housing and the presence of other sanitary facilities on the prevalence of bilharziasis in the Egypt-49 project area has been studied. There is no direct relationship between the size of village and the prevalence of bilharziasis. Main drains and distributaries are potent sources of infection and, in terms of the total population exposed, distributaries play the most significant role in the transmission of infection. Of the other factors, the availability of a protected water supply seems to have the greatest effect on the prevalence. Although the presence of a latrine in the dwelling does not of itself influence the extent of schistosome infection, which is caught from polluted water, the installation of latrines assists in the cultivation of healthy habits, thereby lessening the prevalence not only of bilharziasis but also of certain other infections.

The epidemiology of Schistosoma haematobium and S. mansoni infections in the Egypt-49 project area. 4. Measurement of the incidence of bilharziasis

The measurement of incidence, or the rate at which people become positive, for Schistosoma haematobium and S. mansoni was carried out in four parts of the Egypt-49 project area near Alexandria. For S. haematobium, rates as high as 22.8% per year were found for children 0-6 years old in a rural area; in the same area, the incidence of S. mansoni was 8.5% per year. The true incidence is underestimated because many cases become negative spontaneously. This loss rate of S. haematobium cases is 0.476 per year for children 0-4 years old, and 0.049 per year for those aged 5 and 6 years; for S. mansoni, the rates are 0.580 and 0.327, respectively. Despite the error, incidence is the most accurate and sensitive method of assessing the success of control operations, and is an important measurable parameter in epidemiology.

Assessment of severity of disease caused by Schistosoma haematobium and S. mansoni in the Egypt-49 project area

The impact of bilharziasis on a community has been evaluated in terms of the stages and grades of severity of the disease; egg counts in faeces and urine were correlated with the clinical severity. At the time this study was carried out, the over-all prevalence of S. haematobium infection was 37.6%, that of S. mansoni infection 29.8% and that of mixed infections 17.1%.Of 579 people examined, 292 (58.2%) were excreting schistosome eggs. All except one person were classified as Stage III-asymptomatic, 122 (41.8% of those infected); mild, 74 (25.3%); moderate, 89 (30.5%); severe, 6 (2.1%). The remaining person was classified as Stage IV (moderate). Mixed infections produced a higher proportion of symptomatic cases (74.8%) than either infection alone (58.2%), and S. haematobium (57.1%) a higher proportion than S. mansoni (37.8%). The percentage of symptomatic cases was highest in those aged 10-14 years, who also had the highest prevalence of infection.On average, the egg output per infection was in the range 32-63 eggs for S. haematobium infections and 4-7 for S. mansoni in unit measure of urine and faeces, respectively. For S. haematobium infections, alone and in mixed infections, mean egg output increased with the severity of clinical symptoms. For S. mansoni infections, no such relation was established.It is concluded that the criteria of severity should be made more objective and that more satisfactory methods of determining egg counts should be adopted in an attempt to obtain more direct evidence of the validity of regarding egg count as a measure of worm load.

The behavioural pattern of social and religious water-contact activities in the Egypt-49 bilharziasis project area

Social and religious water-contact activities have been recorded over a period of one year in four villages situated on different types of watercourse in the Egypt-49 project area. Females have more frequent water contacts than males; females under 25 years old have more frequent contacts than older ones. Males are more active contaminators than females, among whom girls under 5 years old are the chief polluters. Summer is the period of most frequent, prolonged and extensive body-surface contact. One-quarter of all exposures take place between noon and 3 p.m., the period of maximum cercarial load. The most frequent activities during this critical period are washing of utensils, bathing and playing, and wadu (ritual washing). Peak exposures therefore coincide with the peak seasonal and diurnal cycle of infectivity of watercourses in the area.It is suggested that an index might be established that would take into account the frequency and duration of exposure and the amount of body-surface exposed and that could be related to the periodic variations of cercarial densities in the watercourses.

The epidemiology of Schistosoma haematobium and S. mansoni infections in the Egypt-49 project area. 1. Sampling techniques and procedures for measuring the prevalence of bilharziasis

A survey of the prevalence of bilharziasis has been made in the Egypt-49 Project Area, part of the Beheira province of Egypt with an area of 422 km(2) and a population of nearly 250 000 in 552 villages. The area has been classified into four divisions-Rural (Agricultural), Urban (Industrial), Reclamation (Resettlement) and Control, and subdivided into 23 sections bounded by irrigation canals or drains. Between April 1962 and March 1963, 11 944 individuals from 2573 households in 96 villages were examined.An over-all 5% two-stage cluster sample was obtained in each division, except in the Reclamation Division, where, because of the sparse population, a 10% systematic sample was used. The age and sex distributions of the samples were representative of those of the population as a whole. Larger villages tended to be over-represented, but there is no evidence that bilharziasis prevalence is related to village size.Bilharziasis was diagnosed by the detection of eggs in faeces or urine; details of the procedures are given. Examination of single samples, as in this study, leads to an underestimate of the extent of infection, by about 20% for S. mansoni infections and about 13% for S. haematobium; this fact has to be borne in mind in interpreting the prevalence data obtained.

The epidemiology of Schistosoma haematobium and S. mansoni infections in the Egypt-49 project area. 2. Prevalence of bilharziasis in relation to personal attributes and habits

The over-all uncorrected prevalence rates of bilharziasis determined in this survey were-Control Division, 59.5%; Rural and Reclamation Divisions, 35.9%; Urban Division, 21.0%. There are significant differences in rates of infection between sections within a division, between adjacent villages and even between different parts of one village. Prevalence increases rapidly with age up to about the age of 14 years, declines somewhat up to the age of 40 years and then remains fairly constant at a rate of about 30%; the age-group 0-8 years should provide the most sensitive group for the assessment of control measures. S. mansoni infection is acquired more slowly than S. haematobium infection during childhood and is more persistent among adults.Except for the youngest age-group, bilharziasis rates are higher in males than in females, but more detailed analysis shows that this is true only for farmers and farm labourers and for those who swim. In respect of occupational categories, farmers and farm labourers, with prevalence rates of 50.6% and 41.6%, respectivelx, bear the brunt of the infection, since they constitute 48% of the population, although fishermen (60.4%) and boatmen (52.0%) have higher infection rates.Differences in bilharziasis rates can also be related to differences in religion, educational attainment and domestic habits (swimming, washing clothes, utensils and cattle) according to the opportunity provided for contact with polluted water. Swimming, because of the thorough exposure to possible schistosome infection that it provides, is one of the most important activities involved in the transmission of bilharziasis.

Large-scale application of Bayluscide and sodium pentachlorophenate in the Egypt-49 project area. Evaluation of relative efficacy and comparative costs

A study has been undertaken to evaluate the comparative efficacy of two molluscicides-Bayluscide and sodium pentachlorophenate-in controlling the snail population in a complete watershed and to obtain an analysis of the comparative costs of application. Main canals were treated by the drip-feed method, utilizing the water-carriage system, and other watercourses by spraying. Both molluscicides were found to be highly effective, the snail mortality rates exceeding 98%. Treatment involving a first application in May and June and a second one some five months later kept snail densities very low throughout the year.When costs were compared on the basis of unit volume of water treated, for main canals and other watercourses separately, it was found that the chemical costs were very similar; so were the operational costs for the main canals, but in the other watercourses the cost of applying sodium pentachlorophenate was nearly three times that for Bayluscide. For this reason, and because of the toxic properties of the former compound, it is concluded that Bayluscide is the preferred molluscicide in the Egypt-49 project area and probably also in the rest of the Nile Delta area.