Tumor necrosis factor expression during mouse hepatitis virus-induced demyelinating encephalomyelitis

Neutralizing anti-tumor necrosis factor alpha (TNF-alpha) antibody treatment of mice infected with the neurotropic JHMV strain of mouse hepatitis virus showed no reduction of either virus-induced encephalomyelitis or central nervous system demyelination. TNF-alpha-positive cells were present in the central nervous system during infection; however, TNF-alpha could not be colocalized with JHMV-infected cells. In vitro, TNF-alpha mRNA rapidly accumulated following JHMV infection; however, no TNF-alpha was secreted because of inhibition of translation. Both live and UV-inactivated virus inhibited TNF-alpha secretion induced by lipopolysaccharide. These data show that TNF-alpha is not secreted from infected cells and indicate that if contributes to either JHMV-induced acute encephalomyelitis nor primary demyelination.

A new model of subretinal neovascularization in the rabbit

PURPOSE

To establish a new model of subretinal neovascularization (SRN) in the rabbit by implanting basic fibroblast growth factor (bFGF)-impregnated gelatin microspheres beneath the retina.

METHODS

Basic fibroblast growth factor-impregnated gelatin microspheres were prepared by forming a polyion complex between gelatin and bFGF. The microspheres, containing 2.5 micrograms of bFGF, were injected into the subretinal space of rabbit eyes (n = 29). Control eyes (n = 10) received bFGF-free gelatin microspheres. Eyes were followed up for 3 days to 8 weeks by ophthalmoscopy, photography, fluorescein angiography, light microscopy, and transmission electron microscopy.

RESULTS

Twenty of 24 experimental eyes (83%) showed fluorescein leakage from SRN 2 weeks after implantation of the bFGF-impregnated microspheres. This leakage continued for 2 to 6 more weeks. In striking contrast, control eyes showed no fluorescein leakage. Histologic examination revealed SRN in all the experimental eyes but in none of the control eyes.

CONCLUSIONS

Subretinal implantation of bFGF-impregnated gelatin microspheres induces reproducible SRN in the rabbit.

In vitro studies of human choroidal endothelial cells

Vascular endothelial cells play an important role in progression or healing of various retinal or choroidal diseases and they have a broad organ specificity. We have grown and studied human choroidal endothelial cells (CECs) cultured in a collagen gel, where they form tube-like structures. CECs were differentially isolated from choroidal tissues and cultured to near homogeneity. The cells were embedded in a type I collagen gel in 24-well culture dishes and incubated with M199 medium containing 10% fetal calf serum. Gels were observed using phase contrast microscopy and were evaluated histologically by light and electron microscopy. The CECs were strongly positive for factor VIII-related antigen and actively ingested diI-acetylated LDL, indicating their endothelial nature. Ultrastructural analysis of the tube-like structures revealed a central lumen surrounded by cells joined apically by junctions and showing prominent pinocytotic activity, fenestrations and basement membrane formation; these features are typical of CECs in vivo. This preparation should be a useful tool to study the development of physiology and pathology of choroidal endothelium.

Macrophages regulate induction of delayed-type hypersensitivity and experimental allergic encephalomyelitis in SJL mice

The relationship between the delayed-type hypersensitivity (DTH) response and susceptibility to experimental allergic encephalomyelitis (EAE) was examined using a unique age-dependent defect in the DTH response in an EAE-susceptible mouse strain. Young adult male SJL mice ( < 10 weeks of age) are defective in DTH responses following immunization with a variety of soluble antigens. By contrast, they respond to antigens applied to the skin, demonstrating a normal contact sensitivity response. In this report, we show that the non-responder male SJL are also unable to mount a DTH response to soluble neuroantigens or neuroantigens emulsified in complete adjuvant, and are additionally resistant to actively induced EAE. This contrasts with the DTH response in older males ( > 10 weeks of age) and young adult females (6 weeks of age), which are both DTH responders and susceptible to EAE. By contrast, all three groups are susceptible to EAE mediated by the transfer of activated effector T cells, suggesting that the defect in young adult males is in the induction of effectors. Furthermore, transfer of a macrophage population from female responders to young male non-responders mediates the induction of both DTH responsiveness and EAE susceptibility. The phenotype of this antigen-presenting cell is (I-A+, Mac-1+, Mac-2-, Mac-3+), identical to the phenotype of the macrophage regulating DTH responsiveness in this strain of mice. These data are consistent with the hypothesis that a defect in this cell inhibits induction of both CD4+Th1 DTH and EAE effector T cells.

Gamma interferon expression during acute and latent nervous system infection by herpes simplex virus type 1

This study was initiated to evaluate a role for gamma interferon (IFN-gamma) in herpes simplex virus type 1 (HSV-1) infection. At the acute stage of infection in mice, HSV-1 replication in trigeminal ganglia and brain stem tissue was modestly but consistently enhanced in mice from which IFN-gamma was by ablated monoclonal antibody treatment and in mice genetically lacking the IFN-gamma receptor (Rgko mice). As determined by reverse transcriptase PCR, IFN-gamma and tumor necrosis factor alpha transcripts were present in trigeminal ganglia during both acute and latent HSV-1 infection. CD4+ and CD8+ T cells were detected initially in trigeminal ganglia at day 5 after HSV-1 inoculation, and these cells persisted for 6 months into latency. The T cells were focused around morphologically normal neurons that showed no signs of active infection, but many of which expressed HSV-1 latency-associated transcripts. Secreted IFN-gamma was present up to 6 months into latency in areas of the T-cell infiltration. By 9 months into latency, both the T-cell infiltrate and IFN-gamma expression had cleared, although there remained a slight increase in macrophage levels in trigeminal ganglia. In HSV-1-infected brain stem tissue, T cells and IFN-gamma expression were present at 1 month but were gone by 6 months after infection. Our hypothesis is that the persistence of T cells and the sustained IFN-gamma expression occur in response to an HSV-1 antigen(s) in the nervous system. This hypothesis is consistent with a new model of HSV-1 latency which suggests that limited HSV-1 antigen expression occurs during latency (M. Kosz-Vnenchak, J. Jacobson, D.M. Coen, and D.M. Knipe, J. Virol. 67:5383-5393, 1993). We speculate that prolonged secretion of IFN-gamma during latency may modulate a reactivated HSV-1 infection.

SV40-immortalized and primary cultured human retinal pigment epithelial cells share similar patterns of cytokine-receptor expression and cytokine responsiveness

Retinal pigment epithelial (RPE) cells produce and respond to a variety of cytokines; however, molecular and biochemical studies are restricted by the limited access to large numbers of pure cells and the variability associated with different donor sources. Despite success in establishing primary human RPE (HRPE) cell cultures, the inability to sustain consistent proliferation rates and morphology over several passages remains a concern. This problem was approached by using an immortalized line of simian virus (SV)40 transformed fetal HRPE cells (SVRPE). Cytokine production, receptor expression and responsiveness in the SVRPE cell line was analyzed to determine the usefulness of this model for studying HRPE-cytokine interactions. Using reverse transcriptase polymerase chain reaction (RT-PCR), HRPE and SVRPE cells demonstrated an identical pattern of interleukin-1 receptor (IL-1R), IL-2R (alpha sub-unit), IL-6R, interferon (IFN)-gamma R and tumor necrosis factor-alpha (TNF)R p55 expression. No amplification products for TNFR p75 or granulocyte/macrophage colony stimulating factor (GM-CSF)R were demonstrated in either population. IFN-gamma stimulation induced surface human leukocyte antigen (HLA)-DR in both SVRPE and HRPE, while TNF treatment induced surface expression of intercellular adhesion molecule (ICAM)-1 on SVRPE and upregulated ICAM from basal levels on HRPE. Both cell types showed amplification products for interleukin (IL)-1 beta, IL-6 and transforming growth factor (TGF)-beta 1 using RT-PCR. The bioassays demonstrated that both populations of unstimulated cells constitutively secrete very low levels of TGF-beta and no IL-6.(ABSTRACT TRUNCATED AT 250 WORDS)

Migration of retinal pigment epithelium cells in vitro is regulated by protein kinase C

The migration of retinal pigment epithelial (RPE) cells is an important step in various pathologic conditions, including subretinal neovascularization (SRN) and proliferative vitreoretinopathy (PVR). Therefore, elucidation of the mechanism of RPE migration may be useful in devising effective treatment for these disorders. Since protein kinase C (PKC) has been shown to regulate the migration of other cell types, we studied the effects of PKC agonists and antagonists on RPE migration. We used an in vitro wound healing model in which a small area of a confluent monolayer of bovine RPE cells was denuded with a razor blade. The cultures were subsequently incubated with agents known to stimulate [phorbol 12-myristate 13-acetate (PMA)] or inhibit (calphostin C, staurosporine) PKC. After 20 hr, migration was measured as the number of cells that had entered the denuded area. We also measured the translocation of PKC from the cytosol to the membrane in order to determine the activation or inhibition of PKC by PMA and calphostin C in the cells. The phorbol ester PMA stimulated migration by 41%, and calphostin C and staurosporine inhibited migration by 38% and 31%, respectively, in a medium supplemented with 10% serum. To determine the requirement for serum in this modulation, we also measured the effects of PMA and calphostin C on RPE migration in serum-free medium. Under these conditions, basal migration was greatly decreased, but PMA stimulated migration by 177% and calphostin C inhibited migration by 93%. Since PKC modulation is known to induce the proliferation of cells, we also tested the effects of these agents on growth-inhibited migration by pretreating the cells with the antiproliferative drug mitomycin C. We found that modulation of PKC under these conditions equally affected growth-inhibited and growth-dependent migration. Therefore, based on the increase in RPE migration induced by a PKC agonist, and the decrease in migration caused by PKC antagonists, it is suggested that PKC-mediated signal transduction plays a crucial role in RPE cell migration. This knowledge may be useful in devising effective treatments for SRN and PVR.

Effect of tecogalan sodium on angiogenesis in vitro by choroidal endothelial cells

PURPOSE

To examine the possible inhibitory effect of tecogalan sodium, derived from bacteria, on three important components of in vitro angiogenesis (endothelial proliferation, migration, and tube formation in a collagen gel) using bovine choroidal endothelial cells (CECs).

METHODS

The effects of tecogalan sodium (1, 5, 25, 125, and 250 micrograms/ml) on cultured CECs were examined when basic fibroblast growth factor (bFGF, 10 ng/ml), vascular endothelial growth factor (VEGF, 50 ng/ml), a combination of bFGF (10 ng/ml) and VEGF (50 ng/ml) (bFGF/VEGF) and 10% fetal calf serum (FCS) were used as angiogenic stimulants. For the proliferation assay, CECs were cultured and the cell numbers counted on days 1, 3, and 5. For migration assay, CECs were seeded in the upper half of a Boyden chamber while an angiogenic growth factor was loaded in the lower half. After 6 hours of incubation, cell migration was evaluated by counting the numbers of migrated cells per microscopic field on the lower side of the filter. For the tube-forming assay, CECs were seeded in a type I collagen gel, and the length of the tube-like structures (an indicator of angiogenesis) formed by CECs per microscopic field was quantified by image analysis. The effect of neutralizing antibody for bFGF also was tested in these three assays.

RESULTS

All tested angiogenic stimulants induced CEC proliferation. The stimulatory effect of bFGF and bFGF/VEGF was reduced by tecogalan sodium (IC50 for bFGF effect, 26.1 micrograms/ml). However, the effect of VEGF and of 10% FCS was not altered by low doses of tecogalan sodium (< 25 micrograms/ml). Chemotaxis of CECs was stimulated by bFGF alone and by bFGF/VEGF, and this effect was inhibited by tecogalan sodium (IC50 for bFGF, 3.2 micrograms/ml). Stimulation of chemotaxis by VEGF alone and by 10% FCS was not affected by tecogalan sodium in low doses but was inhibited by high doses. Tube formation was stimulated by administration of each of the factors. Stimulation of tube formation by bFGF and by bFGF/VEGF was inhibited by tecogalan sodium (IC50 for bFGF, 18.2 micrograms/ml). High doses of tecogalan sodium (125 and 250 micrograms/ml) also inhibited 10% FCS-induced proliferation, migration, and tube formation.

CONCLUSION

bFGF, VEGF, and a combination of bFGF and VEGF stimulated proliferation, migration, and tube formation by CECs in vitro. These stimulatory effects, but especially those of bFGF, were inhibited by tecogalan sodium. If tecogalan sodium can be shown to have a similar effect in vivo, it might have the potential for pharmacologic control of subretinal neovascularization.

High-dose tamoxifen in treatment of brain tumors: interaction with antiepileptic drugs

The incidence of seizures related to primary brain tumors is 20-80%. High-dose tamoxifen was recently reported as a novel treatment for patients with malignant gliomas who have failed standard therapies. Tamoxifen inhibits protein kinase C (PKC) in vitro and thus may regulate glioma cell growth by modulating intracellular signal transduction. We report a patient with a recurrent supratentorial pilocytic astrocytoma who had an untoward interaction between high-dose tamoxifen therapy and phenytoin (PHT), drugs that share a common enzyme for metabolism, therefore emphasizing the need to monitor concomitant antiepileptic drug (AED) levels when high-dose tamoxifen therapy is instituted.

Vessel formation by choroidal endothelial cells in vitro is modulated by retinal pigment epithelial cells

OBJECTIVE

To elucidate the mechanism of bovine choroidal endothelial (BCE) cell angiogenesis and, in particular, the role of retinal pigment epithelial (RPE) cells by use of an in vitro coculture assay system.

METHODS

The BCE cells were isolated from choroidal tissues and cultured. They were embedded in type I collagen gel and incubated. The gel-embedded BCE cells were then covered with a monolayer of RPE cells, pericytes, choroidal fibroblasts, or additional BCE cells on culture day 0 or day 14. The BCE cells in culture formed a meshwork of tubelike structures. The length of the tubelike structures (micrometers per field) was quantified by image analysis, as an indicator of angiogenesis. The effect of RPE cells on normal and growth-arrested BCE cell tube formation was evaluated in this assay system. The mechanism of RPE-induced angiogenesis was studied by parallel experiments with the use of neutralizing antibodies against specific growth factors (basic fibroblast growth factor, vascular endothelial growth factor, and transforming growth factor beta).

RESULTS

Ultrastructural analysis revealed that the tubelike structures had features typical of choroidal endothelial cells. Cocultures initiated on day 0 revealed that BCE cell angiogenesis was promoted by overlying RPE cells and, to a lesser extent, by pericytes, choroidal fibroblasts, and additional BCE cells when compared with BCE cells without covering cells. In cocultures initiated after BCE tube formation (day 14), there was inhibition of BCE angiogenesis by overlying RPE cells when compared with cultures without overlay or with an overlay of BCE cells. The RPE cells stimulated tube formation of growth-arrested BCE cells less effectively than did normal BCE cells. Neutralizing antibody for basic fibroblast growth factor and vascular endothelial growth factor, but not transforming growth factor beta, inhibited control and RPE-induced tube formation by BCE cells.

CONCLUSIONS

Overlying RPE cells stimulate the formation of tubelike structures by choroidal endothelial cells more effectively than do fibroblasts or pericytes but inhibit BCE tube formation in older cultures. The effect involves endothelial proliferation and differentiation. The stimulatory effect of overlying RPE cells can be inhibited by neutralizing antibodies to vascular endothelial growth factor and basic fibroblast growth factor, which suggests that these growth factors play an important role in this phenomenon.

Lymphocytic adenohypophysitis: contrast-enhanced MR imaging in five cases

PURPOSE

To describe observations of adenohypophysitis on magnetic resonance (MR) images.

MATERIALS AND METHODS

Clinical, enhanced MR imaging, surgical, and histologic findings were retrospectively studied in four female patients and one male patient with adenohypophysitis who presented with headaches, pituitary insufficiency, or hyperprolactinemia. Results were compared with MR imaging, surgical, and pathologic findings in 128 consecutive cases of newly diagnosed pituitary adenomas.

RESULTS

In two of the four female patients, disease onset was not associated with a recent history of pregnancy. Imaging findings included a slightly lobulated, intensely enhancing pituitary mass (n = 5); enhancement along the infundibulum (n = 4); and adjacent dural enhancement (n = 4). Four patients had extrapituitary involvement. Some of these findings were noted in patients with pituitary adenomas complicated by infarction, hemorrhage, or necrosis.

CONCLUSION

The observed clinical and MR imaging findings are suggestive of adenohypophysitis; the latter, however, are not specific and may be seen in some complicated cases of pituitary adenoma and other rare forms of pituitary inflammation. Biopsy may be needed to establish the correct diagnosis if a trial of steroid therapy fails.

Magnetic resonance imaging of cystic meningiomas and its surgical implications

Our purpose was to document the incidence and imaging features of cystic meningiomas, to correlate the imaging features of cystic meningiomas with the histopathological findings, and to analyze the surgical implications of the imaging features of cystic meningiomas. The imaging studies, clinical histories, operative findings, and histopathological findings of a total of 128 patients with meningiomas were reviewed retrospectively. The 15 cystic meningiomas in our series could be morphologically divided into three major types: cystic areas contained wholly within the tumor (6 meningiomas), cystic areas at the periphery of, but wholly within, the margins of the tumor (5 meningiomas), and cystic areas peripheral to the tumor, lying on the adjacent brain (4 meningiomas). A majority of cystic meningiomas were histopathologically diagnosed to be meningothelial (8 of 15 meningiomas). Cellular atypia was seen in many patients. Meningiomas may simulate astrocytomas or metastatic lesions on imaging studies. Magnetic resonance imaging had a diagnostic accuracy of 80% (12 of 15 patients), which was significantly better than the computed tomography diagnostic accuracy of 50% or less. Magnetic resonance imaging with contrast enhancement could distinguish Type 2 (cyst wall containing tumor cells) and Type 3 (cyst wall containing gliotic tissue without tumor invasion) cystic meningiomas. Cyst wall enhancement was seen in Type 2, but not in Type 3, cystic meningiomas. Cystic meningiomas represented approximately 10% of all meningiomas in our series. Histiologically, they were usually relatively aggressive, which probably partly explains why cystic changes may be secondary to tumor necrosis or hemorrhage. Recognition of the diagnostic features of cystic meningiomas is important, because they may mimic metastatic neoplasms or primary gliomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Paradoxical elevation of Ki-67 labeling with protein kinase inhibition in malignant gliomas

The monoclonal antibody Ki-67 recognizes a nuclear antigen expressed in the G1, S, G2, and M phase of the cell cycle and has been used extensively as an indicator of cellular proliferation in malignant gliomas, both in the laboratory and clinically. Recently, protein kinase C (PKC) inhibitors have been demonstrated to inhibit malignant glioma growth both in in vitro and in vivo. This study was undertaken to determine whether Ki-67 could function as an indicator of cellular proliferation rate after PKC inhibition in gliomas and to explore cell cycle specificity of such inhibition. Both established and low-passage malignant glioma cell lines have previously been shown to be sensitive to growth inhibition by the PKC inhibitors staurosporine and tamoxifen in vitro (IC50 in the nanomolar and micromolar ranges, respectively), as measured by cell numbers, [3H]thymidine uptake, and flow-cytometric DNA analysis. However, in the same cells that are inhibited by staurosporine and tamoxifen on these assays, and on the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay in the present study, the Ki-67 labeling index paradoxically increased in a dose-related manner with the same treatments, as measured by immunohistochemistry and confirmed by flow cytometry. For example, in established line U-87, a 20.5% decrease in thymidine uptake and a 28.5% decrease in absorbance on the MTT assay produced by tamoxifen at 1 microM was associated with an increase in Ki-67 labeling from 42% to 62%; staurosporine, which produces a 78.8% decrease in thymidine uptake in cell line A-172 at 10 nM, produced an increase in Ki-67 labeling from 19% to 32%. In this regard, Ki-67 labeling of glioblastoma tissue from a patient treated with high-dose tamoxifen yielded results within the range of 10% to 15% (consistent with values seen in untreated glioblastoma), despite tumor regression with treatment. The authors' interpretation of these results is that these PKC inhibitors are halting the cell cycle in the G1 phase or the G1-S transition (beyond G0 but before S-phase), resulting in a paradoxical increase in labeling while arresting growth. Two important implications from these observations are that Ki-67 is not a reliable indicator of cellular proliferation after treatment with PKC inhibitors and that these inhibitors used at the doses given above halt cell growth in a phase-specific manner.

Mouse hepatitis virus-specific cytotoxic T lymphocytes protect from lethal infection without eliminating virus from the central nervous system

Acute infection of the central nervous system by the neurotropic JHM strain of mouse hepatitis virus (JHMV) induces nucleocapsid protein specific cytotoxic T lymphocytes (CTL) not found in the periphery (S. Stohlman, S. Kyuwa, J. Polo, D. Brady, M. Lai, and C. Bergmann, J. Virol. 67:7050-7059, 1993). Peripheral induction of CTL specific for the nucleocapsid protein of JHMV by vaccination with recombinant vaccinia viruses was unable to provide significant protection to a subsequent lethal virus challenge. By contrast, the transfer of nucleoprotein-specific CTL protected mice from a subsequent lethal challenge by reducing virus replication within the central nervous system, demonstrating the importance of the CTL response to this epitope in JHMV infection. Transfer of these CTL directly into the central nervous system was at least 10-fold more effective than peripheral transfer. Histological analysis indicated that the CTL reduced virus replication in ependymal cells, astrocytes, and microglia. Although the CTL were relatively ineffective at reducing virus replication in oligodendroglia, survivors showed minimal evidence of virus persistence within the central nervous system and no evidence of chronic ongoing demyelination.

Effect of intravitreal administration of indomethacin on experimental subretinal neovascularization in the subhuman primate

OBJECTIVE

To examine the effect of indomethacin, a cyclooxygenase (CO) inhibitor, on laser-induced subretinal neovascularization (SRN) in the monkey. The CO pathway of arachidonic acid metabolism plays an important role in angiogenesis, and the inhibition of CO is known to inhibit angiogenesis in the cornea and in certain tumors.

MATERIALS AND METHODS

A cannula was implanted into the vitreous cavity of 11 eyes of six monkeys and connected to an osmotic minipump. Indomethacin (25 micrograms/d) was delivered into the vitreous through the cannula for 14 days (seven eyes). Vehicle alone was injected for 14 days as a control (four eyes). Argon laser photocoagulation was then performed (eight spots at the posterior pole in each eye) to induce SRN. Fundus photographs and fluorescein angiograms were taken periodically to document the evolution of SRN. Light and electron microscopic examination was performed on two eyes of each group 8 weeks after photocoagulation.

RESULTS

Subretinal neovascularization developed from 2 to 4 weeks after photocoagulation. The incidence of SRN, indicated by fluorescein leakage, was significantly lower (P < .05) in the group treated with indomethacin (14.3%, eight of 56 lesions) than in the control group (37.5%, 12 of 32 lesions). After 8 weeks, no fluorescein leakage was found in either the control or indomethacin-treated groups. Scar formation was found on histologic examination in both groups. No histologic evidence of indomethacin toxicity was seen in the adjacent retina.

CONCLUSIONS

Intravitreal administration of indomethacin inhibits the formation of laser-induced SRN in monkey eyes. This is consistent with the participation of the CO pathway in the process of SRN formation and suggests that this pathway could be a potential target in the treatment of SRN.

Thrombin induced cytoskeletal change in cultured bovine corneal endothelial cells mediated via protein kinase C pathway

We studied the participation of the protein kinase C pathway in thrombin-induced cytoskeletal alterations in confluent cultured bovine corneal endothelial (BCE) cells. Cultured BCE cells were exposed to alpha-thrombin (0.1-10 U/ml for 15-60 min) and the distribution of F-actin and vinculin plaques was examined using immunofluorescent staining and electron microscopy. Phorbol 12-myristate 13-acetate (PMA, 10 nM for 15 min), the broad spectrum protein kinase inhibitors staurosporine (10 nM) and H-7 (10 nM), and highly specific PKC inhibitor calphostin C (10 nM) were used to evaluate the role of PKC/phosphorylation in this phenomenon. HA-1004 (10 nM) was used as a negative control for these inhibitors. In a parallel experiment, PKC activity of cytosol and membrane of BCE cells was also evaluated. In control samples, F-actin was distributed mainly at the periphery of cells, where it formed dense peripheral bundles; vinculin plaques were also present at the cell boundary. Exposure of BCE cells to thrombin changed the distribution of F-actin and vinculin into a diffuse pattern; a similar alteration was also induced by incubation with PMA. These phenomena were blocked by incubation with H-7, staurosporine and calphostin C. Both cytosolic and membrane PKC activity was increased after 5 to 30 min exposure of alpha-thrombin and returned to the control level after 1 h. alpha-Thrombin induces alteration in the cytoskeleton of BCE cells, and this message is transduced at least in part by PKC dependent pathways. PKC/phosphorylation may thus play an important role in physiological processes that involve alterations of the cytoskeleton.

MDR1 gene expression in brain of patients with medically intractable epilepsy

Why some patients with seizures are successfully treated with antiepileptic drugs (AEDs) and others prove medically intractable is not known. Inadequate intraparenchymal drug concentration is a possible mechanism of resistance to AEDs. The multiple drug resistance gene (MDR1) encodes P-glycoprotein, an energy-dependent efflux pump that exports planar hydrophobic molecules from the cell. If P-glycoprotein is expressed in brain of some patients with intractable epilepsy and AEDs are exported by P-glycoprotein, lower intraparenchymal drug concentrations could contribute to lack of drug response in such patients. Eleven of 19 brain specimens removed from patients during operation for intractable epilepsy had MDR1 mRNA levels > 10 times greater than those in normal brain, as determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method. Immunohistochemistry for P-glycoprotein from 14 of the patients showed increased staining in capillary endothelium in samples from epileptic patients as compared with staining in normal brain samples. In epileptic brain specimens with high MDR1 mRNA levels, expression of P-glycoprotein in astrocytes also was identified. Last, steady-state intracellular phenytoin (PHT) concentrations in MDR1 expressing neuroectodermal cells was one fourth that in MDR1-negative cells. MDR1 expression is increased in brain of some patients with medically intractable epilepsy, suggesting that the patients' lack of response to medication may be caused by inadequate accumulation of AED in brain.

Transcription and translation of proinflammatory cytokines following JHMV infection

Infection with JHMV results in the transcriptional activation of two host cell genes encoding proinflammatory cytokines, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta. Analysis of irradiated mice showed that IL-1 beta mRNA accumulation in the central nervous system was predominantly derived from the mononuclear infiltrate. By contrast, accumulation of TNF-alpha mRNA was unaffected by immunosuppression, suggesting that resident cells were the source of this cytokine. Infected mice were treated with anti-TNF antibody to determine if TNF-alpha contributed to either the encephalomyelitis or demyelination associated with JHMV infection. Surprisingly, neither the cellular infiltrate nor demyelination were affected. In vitro analysis showed that IL-1 beta but not TNF was secreted from JHMV infected macrophages. The absence of TNF secretion is due to a block in translation of the TNF mRNA which accumulates during infection.

Lovastatin induces growth inhibition and apoptosis in human malignant glioma cells

The competitive HMG-CoA reductase inhibitor lovastatin has been shown to suppress growth and induce morphological changes in a variety of non-glioma tumor cell lines. This study assesses the effects of this agent on the growth and survival of the human malignant glioma cell lines A172 and U87-MG. The response to the drug was investigated using a cell proliferation assay which revealed significant dose-dependent growth inhibition. Treatment with as little as 100 nM lovastatin over a period of 72 hours led to DNA degradation into nucleosome-sized fragments characteristic of apoptosis. Our data suggest that HMG-CoA reductase inhibitors such as lovastatin merit further investigation as potential therapeutic agents for the treatment of malignant gliomas.

Multifocal inflammatory leukoencephalopathy associated with levamisole and 5-fluorouracil: case report

Levamisole and 5-fluorouracil have now become the standard chemotherapeutic regimen for patients with Stage III colon carcinoma. A case of multifocal inflammatory leukoencephalopathy secondary to levamisole alone or combination of levamisole and 5-fluorouracil is reported. Magnetic resonance imaging with gadolinium demonstrated multifocal contrast-enhancing frontal, parietal, occipital, and periventricular white matter lesions. A stereotactic biopsy revealed reactive gliosis and macrophage infiltration, without evidence of metastatic tumor. Despite continuation of 5-fluorouracil, resolution of contrast-enhancing lesions on magnetic resonance imaging without further neurological sequelae occurred when levamisole was stopped. The patient died with evidence of systemic metastasis 6 months later. Autopsy examination of the brain revealed multifocal demyelinating lesions, with no evidence of metastatic tumor. Immunoperoxidase studies of demyelinated lesions demonstrated infiltrating macrophages strongly positive for Class II antigens, interleukin-6, and interleukin-1 alpha. Surrounding astrocytes were positive for granulocyte macrophage colony-stimulating factor. Small numbers of perivascular T cells were present. This patient represents the first autopsy documented case of levamisole associated multifocal inflammatory leukoencephalopathy.

Effect of TGF-beta on interferon-gamma-induced HLA-DR expression in human retinal pigment epithelial cells

PURPOSE

Retinal pigment epithelial (RPE) cells express human leukocyte antigen (HLA)-DR (class II) antigens when stimulated with interferon gamma (IFN-gamma) and may be capable of local antigen presentation. The authors examined the effect of transforming growth factor-beta (TGF-beta), a cytokine normally found in the eye, on the expression of these immunoregulatory molecules in vitro and attempted to determine the mechanism by which this cytokine acts.

METHODS

Human RPE cells were cultured in the presence of IFN-gamma and then stained immunohistochemically for HLA-DR antigens. TGF-beta 1 or TGF-beta 2 was added simultaneously with IFN-gamma or after 3 days of IFN-gamma treatment. In parallel experiments, RPE cells were pretreated with 4-phorbol-12 myristate-13 acetate (PMA), staurosporine, or calphostin C before stimulation with IFN-gamma or TGF-beta. Quantitative analysis was performed by fluorescence-activated cell sorting.

RESULTS

IFN-gamma induced HLA-DR expression on RPE cells. Both TGF-beta 1 and TGF-beta 2 were able to inhibit this effect. These inhibitory effects of TGF-beta were augmented by pretreatment with either PMA or calphostin C. Pretreatment of the cells with PMA before stimulation with IFN-gamma downregulated HLA-DR expression. Staurosporine pretreatment suppressed HLA-DR expression by IFN-gamma-stimulated RPE cells, but this was not additive with TGF-beta.

CONCLUSIONS

The authors conclude that TGF-beta 1 and TGF-beta 2 strongly inhibit the IFN-gamma-induced upregulation of class II antigens on human RPE cells. The modulation of these IFN-gamma and TGF-beta effects by calphostin C, staurosporine, and PMA treatment suggests involvement of the protein kinase C pathway.

Multifocal inflammatory leukoencephalopathy associated with levamisole and 5-fluorouracil: case report

Levamisole and 5-fluorouracil have now become the standard chemotherapeutic regimen for patients with Stage III colon carcinoma. A case of multifocal inflammatory leukoencephalopathy secondary to levamisole alone or combination of levamisole and 5-fluorouracil is reported. Magnetic resonance imaging with gadolinium demonstrated multifocal contrast-enhancing frontal, parietal, occipital, and periventricular white matter lesions. A stereotactic biopsy revealed reactive gliosis and macrophage infiltration, without evidence of metastatic tumor. Despite continuation of 5-fluorouracil, resolution of contrast-enhancing lesions on magnetic resonance imaging without further neurological sequelae occurred when levamisole was stopped. The patient died with evidence of systemic metastasis 6 months later. Autopsy examination of the brain revealed multifocal demyelinating lesions, with no evidence of metastatic tumor. Immunoperoxidase studies of demyelinated lesions demonstrated infiltrating macrophages strongly positive for Class II antigens, interleukin-6, and interleukin-1 alpha. Surrounding astrocytes were positive for granulocyte macrophage colony-stimulating factor. Small numbers of perivascular T cells were present. This patient represents the first autopsy documented case of levamisole associated multifocal inflammatory leukoencephalopathy.

Cytokine expression in radiation-induced delayed cerebral injury

Radiation-induced delayed brain injury is a well-documented complication of both standard external beam radiation (teletherapy) and interstitial brachytherapy; however, the cause of this damage has not been determined. Cytokines and growth factors are important regulatory proteins controlling the growth and differentiation of normal and malignant glial cells, which have been implicated in the tissue response to radiation injury. Six snap-frozen brain biopsies showing radiation injury were obtained from four patients harboring malignant gliomas who underwent either postoperative external beam and/or stereotactic interstitial brachytherapy at standard dosages. The specimens showed variable amounts of gliosis, tissue necrosis, calcification, inflammation, and vascular proliferation and hyalinization. Frozen tissue sections were examined for the presence of infiltrating lymphocytes, macrophages, cytokines, and other immunoregulatory molecules by the use of a panel of specific monoclonal and polyclonal antibodies. All specimens showed diffuse T cell infiltration with both CD4+ and CD8+ cells. Infiltrating activated macrophages (CD11c+, HLA-DR+) were prominent in five of six cases. Tumor necrosis factor-alpha and interleukin-6 immunoreactivity was prominent in four of six cases and was predominately localized to macrophages. Transforming growth factor-beta astrocytic and macrophage immunoreactivity was present at moderate levels in all cases. This study suggests that in radiation necrosis, interleukin-1 alpha, tumor necrosis factor-alpha, and interleukin-6 are expressed, predominately by infiltrating macrophages.

Transforming growth factor-beta regulates human retinal pigment epithelial cell phagocytosis by influencing a protein kinase C-dependent pathway

BACKGROUND

Transforming growth factor-beta (TGF-beta) plays an important role in the pathogenesis of many ocular diseases, including proliferative vitreoretinopathy. We examined the effect of TGF-beta on the phagocytosis of rod outer segments by retinal pigment epithelium (RPE), which is a major function of RPE, and investigated the dependence of this effect on the protein kinase C (PKC) pathway.

METHODS

Phagocytotic uptake of fluoresceinated bovine rod outer segments was determined by flow cytometry. RPE cells were treated with TGF-beta 1 or TGF-beta 2 and their effects on phagocytosis were examined. The effects of various PKC inhibitors (calphostin C, staurosporine, and extended exposure to phorbol 12-myristate 13-acetate, PMA) and a stimulator (brief exposure to PMA) on RPE phagocytosis was evaluated.

RESULTS

Both TGF-beta 1 and TGF-beta 2 up-regulated RPE phagocytosis and PMA abolished the up-regulating effect of TGF-beta. In contrast, PKC inhibition by staurosporine and calphostin C resulted in increased phagocytosis. A combination of TGF-beta and PKC inhibitor treatment did not produced any additive effect on phagocytosis.

CONCLUSION

We concluded that TGF-beta up-regulates human RPE phagocytosis, but that this effect is counteracted by PKC activation. It is possible that this TGF-beta-induced effect is due, in part, to a negative modulation of the PKC-dependent pathway.

Exogenous tat protein activates central nervous system-derived endothelial cells

Tat protein, an HIV gene product known to be secreted extracellularly, was tested to determine its role in the dissemination of HIV into the central nervous system (CNS). Tat was shown to activate human CNS-derived endothelial cells (CNS-EC) by the increase in the expression of E-selectin, the synthesis of IL-6, and the secretion of plasminogen activator inhibitor-1 (PAI-1). Tat also functioned synergistically with tumor necrosis factor alpha (TNF). AIDS brains stained for tat in situ, demonstrated positive cells. These data suggest that secreted tat protein may increase leukocyte binding, and alter the blood-brain barrier permeability to enhance dissemination of HIV-infected cells into the CNS.

Hypericin: a potential antiglioma therapy

Hypericin, a polycyclic aromatic dione isolated from plants, is presently being clinically evaluated as an antiviral agent in the treatment of human immunodeficiency virus (HIV) infection. In addition, it is known to be a potent protein kinase C inhibitor. To evaluate its potential as an inhibitor of glioma growth, an established (U87) and low-passage glioma line (93-492) were treated with hypericin in tissue culture for a period of 48 hours after passage. Hypericin inhibited the glioma growth in a dose-related manner, with a marked inhibition of growth in the low-micromolar concentration range (e.g., in line U87 and low-passage line 93-492, a concentration of hypericin of 10 mumol/L produced 62 and 76% decreases in [3H]thymidine uptake, respectively). Because the reported inhibitory effects of protein kinase C are enhanced by visible light, [3H]thymidine uptake was measured in both the presence and the absence of visible light. In glioma line A172, the presence of light slightly increased the inhibitory effect of hypericin. Moreover, an apoptosis (i.e., programmed cell death) assay was performed to determine whether the treatment of glioma cells with hypericin was cytostatic or cytocidal. Cells were harvested, and purified deoxyribonucleic acid (DNA) was analyzed by agarose gel electrophoresis. DNA from cells treated with hypericin for 48 hours exhibited a classical "ladder" pattern of oligonucleosome-sized fragments characteristic of apoptosis. These data suggest that the proven safe drug hypericin may have potential as an antiglioma agent; we suggest clinical trials.

Surgical implications of magnetic resonance-enhanced dura

The purpose of this study was to assess tissue changes responsible for dural enhancement of magnetic resonance imaging (MRI) and its clinical implications. A prospective surgical, histopathological, and MRI study was performed in 73 patients with various types of disease, including meningiomas (n = 29), craniofacial tumors with possible direct intracranial extension (n = 21), gliomas and brain metastasis in close proximity to the dura mater (n = 9), and a variety of nonneoplastic processes (n = 14). Contrast-enhanced MRI was obtained within 5 days before surgery and in some cases within 3 days after surgery as well. Histopathological examination of the dural specimens was performed in all 59 patients with neoplasia and in selected patients with nonneoplastic processes. Dural invasion was noted in 18 of 29 meningiomas, 15 of 21 craniofacial neoplasms, 3 of 5 gliomas, and 3 of 4 brain metastases. In these patients invasion was focal and in direct continuity with the tumors. MRI disclosed that dura invaded by the tumor had a break in the continuity of enhancement, or that there was no discernible enhancement. Association between patterns of dural enhancement and tumor invasion of dura was statistically significant (P < 0.001). The thickened-enhanced portion of the dura represented reactive changes. Postoperative enhancement was seen as early as 24 hours after surgery and was shown histologically to be associated with vasodilation and reactive changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Giant infectious intracavernous carotid artery aneurysm presenting as intractable epistaxis

Infectious intracavernous carotid artery aneurysms usually present with ophthalmoplegia and/or signs of cavernous sinus thrombosis. We report an unusual case in which a patient with AIDS presented with intractable epistaxis secondary to rupture of a giant infectious intracavernous carotid artery aneurysm. Culture of the aneurysm grew mycobacterium avium intracellulare (MAI). The patient was treated successfully by excision of the aneurysm and reconstruction of the internal carotid artery with a saphenous vein interposition graft.

Collagen gel contraction induced by retinal pigment epithelial cells and choroidal fibroblasts involves the protein kinase C pathway

Contraction of intraocular fibrous membranes is an important feature in the pathogenesis of retinal detachment in proliferative vitreoretinopathy (PVR). Collagen gel contraction is a useful in vitro model of membrane contraction in PVR. We studied the role of protein kinase C (PKC) in collagen gel contraction induced by bovine choroidal fibroblasts and retinal pigment epithelial (RPE) cells. Collagen gels embedded with the cells were formed in culture dishes and gel contraction was evaluated. The PKC stimulator, phorbol 12-myristate 13-acetate (PMA), and the protein phosphatase 1 and 2A inhibitor, okadaic acid (OA), were used to evaluate the role of the PKC-mediated phosphorylation system in this gel contraction. Fifteen min incubation with PMA stimulated gel contraction, but 180 min incubation had no effect. Choroidal fibroblast- but not RPE cell-induced gel contraction was stimulated by OA. These effects were inhibited by the broad spectrum protein kinase inhibitor staurosporine and the specific PKC antagonist calphostin C. Transforming growth factor-beta (TGF-beta)1 and TGF-beta 2, which are known to be present in eyes with PVR, were evaluated to determine their effect on gel contraction. Both TGF-beta 1 and 2 had a stimulatory effect on contraction of gels seeded with choroidal fibroblasts and RPE cells, but staurosporine and calphostin C inhibited this TGF-beta-induced gel contraction. These results indicate that activation of PKC/protein phosphorylation is an important factor in gel contraction caused by choroidal fibroblasts and RPE cells, and that TGF-beta-induced gel contraction is mediated at least in part via the PKC pathway.

Protein kinase C inhibitors induce apoptosis in human malignant glioma cell lines

Previous work has demonstrated the importance of the protein kinase C (PKC) system in regulating glioma growth, and has led to clinical trials utilizing PKC inhibitors as adjuncts in the therapy of patients harboring malignant gliomas. This study was performed to explore the possibility that inhibition of PKC in gliomas was triggering an apoptosis signal. Glioma cell lines were treated with PKC inhibitors staurosporine (10 nM), and tamoxifen (10 microM). DNA from cells treated with each of these drugs exhibited a 'ladder' pattern of oligonucleosome-sized fragments characteristic of apoptosis, thus suggesting that in glioma cells, these drugs may be cytocidal in action.

Somataglycan-S: a neuronal surface proteoglycan defines the spinocerebellar system

The formation and maintenance of functionally specific neuronal networks may depend on specific proteoglycans localized to the surface membranes of a subset of neurons. Monoclonal antibody (MAb) 6A2 labeled a distinct subset of CNS neurons: the somas and proximal dendrites of cells making up the spinocerebellar and reticular systems. These pathways contribute to proprioceptive and exteroceptive functions. Ultrastructurally, MAb 6A2 immunoreactivity was distributed focally along the cell surface membranes and the adjacent extracellular space. On western blots of immunoaffinity-purified preparations from cerebellar homogenates, a major, broad band of approximately 400 kDa is labeled by MAb 6A2. Increased electrophoretic mobility of the purified antigen after digestion with chondroitinase ABC and keratanase suggests that the antigen is a proteoglycan bearing chondroitin sulfate and keratan sulfate glycosaminoglycans. Unsulfated N-acetyl-galactosamine residues linked to unsaturated uronic acid constituted the initial disaccharide in the chondroitin sulfate glycosaminoglycan chains. N- and O-linked oligosaccharides on the core protein were detected by the biotinylated lectins wheat germ agglutinin and Jacalin, respectively, and by MAb anti-HNK-1. Lyase and glycosidase digests result in a 280-kDa band. This proteoglycan, somataglycan-S, may provide a key to the role of glycoconjugates in determining neuronal diversity and system specificity.

Dexamethasone induced proliferation of cultured retinal pigment epithelial cells

Dexamethasone (DEX) is a glucocorticoid that is widely used after vitreoretinal surgery and may have mitogenic properties. This study was initiated to determine if human cultured retinal pigment epithelium (RPE) cells express glucocorticoid receptor and proliferate in response to DEX stimulation. Glucocorticoid receptor mRNA was detected in RPE cells by means of reverse transcriptase polymerase chain reaction. To determine the effect of DEX on RPE cell proliferation in vitro, we cultured human RPE cells with various concentrations for DEX for 5 days and determined the effects on cell number and incorporation of tritiated thymidine. DEX treatment with a DEX dose of 1 microgram/ml in the presence or absence of serum resulted in a maximal 2-3 times increase in cell number. Autoradiography after thymidine incorporation revealed a greater than 2-fold increase in incorporating cells at this same dose. These results indicate that DEX causes cultured human RPE cells to proliferate and suggest that it may have a growth factor-like action.

Intercellular gap formation induced by thrombin in confluent cultured bovine retinal pigment epithelial cells

PURPOSE

Thrombin is formed at the site of intraocular hemorrhage and may be important in the development of progressive retinal damage. The authors observed that thrombin-treated bovine retinal pigment epithelial (RPE) cell cultures develop intercellular gaps and initiated this study to examine in detail the effects of thrombin on RPE cell morphology, adhesion, and cytoskeleton.

METHODS

Confluent cultures of bovine RPE cells were incubated for various times (0 to 24 hours) with alpha-thrombin (0.1 to 100 U/ml) or enzymatically inactive thrombin. Intercellular gaps were quantitated by light microscopy in ten representative fields (magnification X400) as number of gaps per field (gaps/f). RPE cytoskeleton was studied using immunofluorescent staining for vinculin and F-actin. The mechanism of thrombin-induced RPE cell gap formation was studied by preincubation with specific drugs, including a protein kinase inhibitor (staurosporine), protein kinase C inhibitors (H-7 and calphostin C), cyclic adenosine monophosphate (cAMP) inducer (forskolin), and cytoskeleton-disrupting agents (cytochalasin B or colchicine).

RESULTS

Intercellular gaps (20 to 80 microns in diameter) were markedly increased in number in thrombin-treated cultures in a dose-dependent and time-dependent manner and were associated with an alteration in the distribution of F-actin and vinculin. Whereas control cultures showed 3.3 +/- 2.4 gaps/f, incubation with 8 U/ml of alpha-thrombin for 3 hours resulted in 44.8 +/- 15.3 gaps/f. These changes were most prominent shortly after the 3-hour coincubation, but the cultures did return to their original confluent state within 24 hours. Cultures treated with an enzymatically inactive thrombin showed fewer intercellular gaps than those treated with enzymatically active thrombin but had significantly more intercellular gaps than control cultures. Thrombin-induced intercellular gap formation was blocked by preincubation with forskolin (14.6 +/- 7.1 gaps/f), staurosporine (10.2 +/- 5.0 gaps/f), or H-7 (24.5 +/- 9.8 gaps/f).

CONCLUSIONS

Exposure to an enzymatically active thrombin results in formation of intercellular gaps between cultured RPE cells. Inhibition of this phenomenon by protein kinase inhibitors and by a cAMP inducer suggests that this effect is mediated, at least in part, through protein kinase C- and cAMP-dependent pathways. Thrombin generation associated with intraocular hemorrhage may thus result in direct damage to the RPE monolayer, possibly via the same pathway(s).

Hemangiopericytoma of the temporal bone presenting as a retroauricular mass

An unusual case of a hemangiopericytoma arising from the temporal bone is presented. The patient was noted to have a postauricular mass and was neurologically asymptomatic. A preoperative magnetic resonance image and an angiogram revealed the tumor to be highly vascular. Preoperative embolization facilitated the surgical removal of the tumor by rendering it avascular. Current therapy consists of radical resection of the tumor with postoperative radiation therapy. Patients must be monitored carefully for local recurrence and systemic metastasis.

Dural invasion by craniofacial and calvarial neoplasms: MR imaging and histopathologic evaluation

The authors prospectively correlated results of magnetic resonance (MR) imaging and histologic examination of the dura in 17 patients with craniofacial and calvarial neoplasms and possible intracranial extension. Contrast material-enhanced MR imaging revealed dural enhancement in 14 patients and no enhancement in three. In four cases, the dura deep to the tumor appeared as a continuous band of enhancement and there was a thin unbroken hypointense zone between the dura and the tumor. Histologic examination in these four patients revealed only dural inflammation without neoplastic spread. In 10 patients, there was a break in the continuity of the enhancement of the underlying dura or a portion of the dura and overlying enhancing tumor could not be separated on MR images. The hypointense zone was focally absent in nine of these cases, and in all 10 there was invasion of the dura by adjacent tumor. Among the other three patients, in whom dural enhancement was not discernible, one had dural invasion by tumor while the other two did not.

Clinical and radiographic response in a minority of patients with recurrent malignant gliomas treated with high-dose tamoxifen

Previous work has demonstrated the importance of the Protein Kinase C (PKC) signal transduction system in regulating the growth rate of malignant gliomas in vitro. Tamoxifen inhibits PKC in a minority of malignant gliomas within the micromolar concentration range in vitro, a property distinct from its estrogen receptor blockade effect. Tamoxifen was administered orally in very high dosages to 11 patients (9 males:2 females, age range 26-73, mean 45 years) with malignant gliomas (anaplastic astrocytoma or glioblastoma multiforme) who had failed treatment with external beam radiation therapy (and additional chemotherapy in 2). The dosage administered was estimated to be that necessary to achieve tissue concentrations within the low micromolar range, shown necessary to inhibit PKC in these tumors in vitro, and is approximately 5 times that used for standard antiestrogen therapy. Tumor reduction on radiographic images (MRI and PET [18FdG uptake]) with clinical improvement occurred in 3 patients; halting of tumor progression clinically and radiographically occurred in an additional patient. Of the remaining seven patients, three patients had marked and rapid progression of their disease despite treatment (dead after 3, 4, and 6 months respectively). Complications of treatment included a deep venous thrombosis requiring anticoagulation in one patient, nausea in one patient, and "hot-flashes" in a third patient. Tumor biopsy and measurement of tamoxifen and its active metabolite within the tumor of one patient (non-responder) showed levels within the middle of the in vitro therapeutic range. Follow-up of alive patients ranges from 4-18 months (mean 10 months). These encouraging preliminary results in a minority of these patients suggests some potential for this type of therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of tumor necrosis factor-alpha on proliferation, cell surface antigen expression, and cytokine interactions in malignant gliomas

Tumor necrosis factor-alpha (TNF-alpha), a cytokine produced by astrocytes in vivo and in vitro, was tested for its effects on two malignant astrocytoma cell lines (A-172, U-87). Both lines were immunoreactive for glial fibrillary acidic protein, vimentin, Class I antigens, and interleukin-6. The lines differed in their expression of Class II and intercellular adhesion molecule-1 (ICAM-1) antigenic determinants: A-172 cells were negative for both Class II and ICAM-1 antigens, while U-87 cells were intensely positive for Class II and weakly positive for ICAM-1. When these astrocytoma cell lines were exposed to TNF-alpha, A-172 growth was stimulated while U-87 growth was inhibited. Furthermore, in U-87 cells, TNF-alpha enhanced both ICAM-1 and interleukin-1 beta (IL-1 beta) expression, and decreased immunoreactivity for transforming growth factor-beta (TGF-beta) protein. In contrast, in the presence of TNF-alpha, A-172 cells remained negative for IL-1 beta and TGF-beta, but showed an increased expression of ICAM-1. These results demonstrate that TNF-alpha can induce changes in growth rate, cytokine production, and surface antigen expression in malignant astrocytomas; however, the nature of these changes is dependent on the specific characteristics of these malignant astrocytomas. The resultant variability in the immunological microenvironment of these tumors may reflect differences in their growth potential.

Interaction of immune and central nervous systems: contribution of anti-viral Thy-1+ cells to demyelination induced by coronavirus JHM

The murine coronavirus JHM (JHMV or MHV-4) has been intensively studied as an experimental model of viral-induced demyelination; nonetheless, the degree to which demyelination results from direct viral cytolysis of oligodendroglia or immunological mechanisms remains controversial. To examine the contribution of immunity to the pathogenesis of JHMV in the central nervous system (CNS), mice were exposed to immunosuppressive doses of x-irradiation 3 days post infection and observed for clinical and pathological evidence of acute and subacute demyelination. Irradiated mice were found to have a nearly thousand-fold increase in central nervous system virus titer, as well as the presence of both abundant virus and viral antigen in white matter cells with the morphological characteristics of oligodendrocytes. Nonetheless, infected, irradiated mice had little or no evidence of demyelination or destruction of CNS cells. Adoptive transfers of spleen cells from syngeneic JHMV-immunized donors into irradiated JHMV-infected mice were carried out in order to determine the effect of immune reconstitution on pathogenesis. Splenocytes from JHMV-immune donors, but not naive donors or donors immunized with irrelevant antigen, completely restored demyelination in irradiated, JHMV-infected recipients. Depletion of Thy-1+ cells by treatment with monoclonal antibody and complement abolished the ability to transfer demyelination. We conclude that: 1) JHMV infection of the CNS does not result in acute or subacute demyelination in the absence of an intact immune response, and 2) viral-specific Thy-1+ cells are an essential element in the induction of demyelinating CNS lesions that result from JHMV infection.

Mosaicism for a specific somatic mitochondrial DNA mutation in adult human brain

The levels of a specific mitochondrial DNA deletion (mtDNA4977) measured in 12 brain regions of 6 normal adults 39 to 82 years old exhibited striking variation among anatomical locations. Comparisons of the same region among individuals showed an increase of mtDNA4977 with age. The three regions with the highest levels, caudate, putamen and substantia nigra, are characterized by a high dopamine metabolism. The breakdown of dopamine by mitochondrial MAO produces H2O2 which can lead to oxygen radical formation. We suggest that mtDNA4977 may be the "tip of the iceberg" of the spectrum of somatic mutations produced by oxidative damage.

Cytokines and immunoregulatory molecules in malignant glial neoplasms

Cytokines are important regulatory proteins controlling growth and differentiation of normal and malignant glial cells. Astrocytes and microglial cells produce and respond to many of the same cytokines employed by cells of the immune system. The authors have analyzed 15 histologically confirmed malignant glial neoplasms for the presence of infiltrating lymphocytes, macrophages, cytokines, and other immunoregulatory molecules using a panel of specific monoclonal and polyclonal antibodies on frozen-tissue sections. All neoplasms showed focal T-cell infiltration with CD8 cells predominating. Infiltration of activated macrophages (positive for CD11c, class II, and interleukin-2 receptor) was marked in all tumors. Within the neoplasm, tumor necrosis factor-alpha (TNF-alpha)- and interleukin (IL)-6-positive macrophages were prominent in five cases, while the tumor cells themselves were only weakly positive. In the other 10 cases, the numerous infiltrating macrophages were only rarely immunoreactive for TNF-alpha or IL-6. Transforming growth factor-beta (TGF-beta) immunoreactivity was most prominent in those tumors with little TNF-alpha-positive macrophage infiltration, although intratumoral variability was present. This study suggests that, in malignant gliomas, the cytokines TNF-alpha and IL-6, although weakly present in neoplastic cells, are most prominent in infiltrating macrophages and in those regions of the tumors that show little immunoreactivity for TGF-beta. The important interactions among neoplastic, reactive glial, and inflammatory cells, which regulate tumor growth, are likely to be in part mediated through these molecules.

Sequential infection of glial cells by the murine hepatitis virus JHM strain (MHV-4) leads to a characteristic distribution of demyelination

An antigenic variant of the neurotropic murine coronavirus JHMV, designated 2.2-V-1, causes marked demyelination in the relative absence of encephalitis. It is thus useful for the study of the pathogenesis of demyelinating lesions. To better understand the sequential events leading to demyelination, we have examined murine brain and spinal cord tissue at daily intervals after intracerebral inoculation, evaluating them for the distribution of viral antigen, leukocyte infiltration, and demyelination. Immunohistochemical staining indicated that virus established primary infection in the ependymal cells in both brain and spinal cord before spreading into nearby structures and along white matter tracts by cell-to-cell contact. Spread from brain to spinal cord appeared to occur via cerebrospinal fluid. Viral replication was focally cytocidal for ependymal cells, and essentially noncytocidal for other neural cells including glia. In brain, viral antigen and inflammation reached a peak at day 5 postinfection, and rapidly subsided by day 10 postinfection. In spinal cord, viral antigen was less abundant than in brain and was maximal between days 7 and 9 postinfection. The inflammatory response and demyelination, however, were more severe persisting from day 7 through day 19. In the spinal cord, demyelinating lesions developed initially in areas closer to the central canal and were detected most prominently in the anterior funiculi. This finding suggests that the permissiveness of the ependymal cell is crucial to viral entry and that sequential infection of glial cells leads to the characteristic distribution of demyelination.

Tumor necrosis factor-alpha in the retina in acquired immune deficiency syndrome

The presence of specific cytokines and the number and distribution of leukocytes were determined in the retinas of patients with acquired immune deficiency syndrome (AIDS). Using immunohistocytochemical techniques, three retinas from patients with AIDS had focal infiltration by T-lymphocytes and macrophages. These specimens stained positively for tumor necrosis factor-alpha (TNF-alpha) in cells identified morphologically as macrophages and glial cells and showed prominent reactive gliosis. The retinas from seven other affected patients had minimal leukocytic infiltration and no TNF-alpha reactivity; gliosis was present in only one. The retinas from clinically normal patients without human immunodeficiency virus (HIV) contained no TNF-alpha-positive cells. Using in situ hybridization for HIV, four of five patients with AIDS had rare positive cells. No interferon-gamma was detected in any of the retinal tissues tested. These data suggest a role for TNF-alpha in the development of AIDS-related retinal disease.

Nucleolar organizer regions in paragangliomas of the head and neck

The clinical behavior of head-and-neck paragangliomas cannot be accurately predicted using standard histologic criteria. Immunohistochemical profiles have proved to be prognostically helpful; however, other independent indicators of prognosis are needed. Tissue markers of proliferative activity include argyrophilic nucleolar organizer regions (AgNOR), which are proteins specifically associated with loops of transcriptionally active ribosomal DNA. Fifteen paragangliomas of the head and neck were divided into solitary nonrecurrent (n = 8), recurrent or locally invasive (n = 4), and multiple (n = 1), or malignant (n = 2) groups. The mean AgNOR count per cell was statistically different between the solitary nonrecurrent and the combined other poorer prognosis groups, suggesting that it may be useful as an independent indicator of biologic behavior. The wide variation in AgNOR counts within groups and the overlap of counts between groups limit, however, the predictive value of this technique for individual tumors.

Inflammatory leukocytes and cytokines in the peptide-induced disease of experimental allergic encephalomyelitis in SJL and B10.PL mice

Experimental allergic encephalomyelitis (EAE) was generated in SJL and B10.PL mice by using the synthetic myelin basic protein peptides. Inflammation in brain and spinal cord preceded clinical signs of disease. Infiltrating lymphocytes were predominantly Lyt1+ (CD5+), L3T4+ (CD4+) T cells, until day 18. After that, F4/80+ monocyte/macrophages outnumbered T cells. Ia+ cells were microglia, macrophages, and endothelial cells, but Ia was not detectable on astrocytes in this EAE model. Ia+ endothelial cells appeared later in the disease than Ia+ microglia and macrophages, suggesting that antigen presentation at the blood-brain barrier is not initially responsible for inflammation. Cells staining for interferon gamma, interleukin 2 (IL-2), and IL-2 receptors were more prominent than IL-4, IL-5, lymphotoxin (LT), and tumor necrosis factor alpha (TNF-alpha), which occurred transiently in the second week and were associated with fewer cells. TNF-alpha and LT were never seen in spinal cord, suggesting that these cytokines are not responsible for initiation of clinical disease. Few or no cells stained for IL-6, IL-1, or transforming growth factor beta. Control animals injected with complete Freund's adjuvant in saline or control antigen demonstrated no inflammatory cell infiltration or cytokine production. Thus, our findings suggest a peptide-induced EAE model in which Th1 T-cell-macrophage interactions result in the disease process.

Retinal degeneration in the macula of patients with Alzheimer's disease

Recent reports (Hinton et al. 1986; Blanks et al. 1989) document the involvement of the retina in the constellation of neurodegenerative changes present in Alzheimer's disease (AD). These studies demonstrate the degeneration of large numbers of optic nerve axons and loss of retinal ganglion cells (RGCs) in patients with AD, but the quantitative changes in the retina of patients with AD compared with age-matched controls have not been examined. An important question is whether the lesion affects the macula, the area of highest visual acuity and the region of the greatest density of cone photoreceptor cells and RGCs. Additionally, it is unknown if patients with AD have a uniform thinning of cells in the ganglion cell layer (GCL) or if there is a differential loss of the medium- to large-sized cells, as suggested earlier (Bassi et al. 1987) and documented histopathologically in some areas of the central nervous system of patients with AD (Kemper 1984). If patients with AD were to show a differential loss of large versus small RGCs with characteristic differences in density, distribution, central projections, and physiologic properties (see review by Rowe and Stone 1977), then a loss of the visual functions normally ascribed to these classes of mammalian RGCs might be expected. This quantitative study of the retinal lesions in the macula of patients with AD provides important data on the progression of the disease and may eventually be the basis for diagnostic procedures for assessing the severity of AD.