Infection of Glia by Human Pegivirus Suppresses Peroxisomal and Antiviral Signaling Pathways.

Human pegivirus (HPgV) infects peripheral leukocytes but was recently shown to be a neurotropic virus associated with leukoencephalitis in humans. In the present study, we investigated the neural cell tropism of HPgV as well as its effects on host immune responses. HPgV wild type (WT) and a mutant virus with a deletion in the HPgV NS2 gene (ΔNS2) were able to productively infect human astrocytes and microglia but not neurons or an oligodendrocyte-derived cell line. Of note, the ΔNS2 virus replicated better than WT pegivirus in astrocytes, with both viruses being able to subsequently infect and spread in fresh human astrocyte cultures. Infection of human glia by HPgV WT and ΔNS2 viruses resulted in suppression of peroxisome-associated genes, including PEX11B, ABCD1, PEX7, ABCD3, PEX3, and PEX5L, during peak viral production, which was accompanied by reduced expression of IFNB, IRF3, IRF1, and MAVS, particularly in ΔNS2-infected cells. These data were consistent with analyses of brain tissue from patients infected with HPgV in which we observed suppression of peroxisome and type I interferon gene transcripts, including PEX11B, ABCD3, IRF1, and IRF3, with concurrent loss of PMP70 immunoreactivity in glia. Our data indicate that human astrocytes and microglia are permissive to HPgV infection, resulting in peroxisome injury and suppressed antiviral signaling that is influenced by viral diversity. IMPORTANCE Human pegiviruses are detected in 1 to 5% of the general population, principally infecting leukocytes, although their effects on human health remain uncertain. Here, we show that human pegivirus infects specific neural cell types in culture and human brain and, like other neurotropic flaviviruses, causes suppression of peroxisome and antiviral signaling pathways, which could favor ongoing viral infection and perhaps confer susceptibility to the development of neurological disease.

Quantitative Assessment of the Risk of Release of Foot-and-Mouth Disease Virus via Export of Bull Semen from Israel.

Various foot-and-mouth disease (FMD) virus strains circulate in the Middle East, causing frequent episodes of FMD outbreaks among Israeli livestock. Since the virus is highly resistant in semen, artificial insemination with contaminated bull semen may lead to the infection of the receiver cow. As a non-FMD-free country with vaccination, Israel is currently engaged in trading bull semen only with countries of the same status. The purpose of this study was to assess the risk of release of FMD virus through export of bull semen in order to estimate the risk for FMD-free countries considering purchasing Israeli bull semen. A stochastic risk assessment model was used to estimate this risk, defined as the annual likelihood of exporting at least one ejaculate of bull semen contaminated with viable FMD virus. A total of 45 scenarios were assessed to account for uncertainty and variability around specific parameter estimates and to evaluate the effect of various mitigation measures, such as performing a preexport test on semen ejaculates. Under the most plausible scenario, the annual likelihood of exporting bull semen contaminated with FMD virus had a median of 1.3 * 10-7 for an export of 100 ejaculates per year. This corresponds to one infected ejaculate exported every 7 million years. Under the worst-case scenario, the median of the risk rose to 7.9 * 10-5 , which is equivalent to the export of one infected ejaculate every 12,000 years. Sensitivity analysis indicated that the most influential parameter is the probability of viral excretion in infected bulls.

HIV eradication symposium: will the brain be left behind?

On 18 July 2014, the National Institute of Mental Health in collaboration with ViiV Health Care and Boehringer Ingelheim supported a symposium on HIV eradication and what it meant for the brain. The symposium was an affiliated event to the 20th International AIDS Conference. The meeting was held in Melbourne, Australia, and brought together investigators currently working on HIV eradication together with investigators who are working on the neurological complications of HIV. The purpose of the meeting was to bring the two fields of HIV eradication and HIV neurology together to foster dialogue and cross talk to move the eradication field forward in the context of issues relating to the brain as a potential reservoir of HIV. The outcomes of the symposium were that there was substantive but not definitive evidence for the brain as an HIV reservoir that will provide a challenge to HIV eradication. Secondly, the brain as a clinically significant reservoir for HIV is not necessarily present in all patients. Consequently, there is an urgent need for the development of biomarkers to identify and quantify the HIV reservoir in the brain. Lastly, when designing and developing eradication strategies, it is critical that approaches to target the brain reservoir be included.

Brain morphometric correlates of metabolic variables in HIV: the CHARTER study.

Obesity and other metabolic variables are associated with abnormal brain structural volumes and cognitive dysfunction in HIV-uninfected populations. Since individuals with HIV infection on combined antiretroviral therapy (CART) often have systemic metabolic abnormalities and changes in brain morphology and function, we examined associations among brain volumes and metabolic factors in the multisite CNS HIV AntiRetroviral Therapy Effects Research (CHARTER) cohort, cross-sectional study of 222 HIV-infected individuals. Metabolic variables included body mass index (BMI), total blood cholesterol (C), low- and high-density lipoprotein C (LDL-C and HDL-C), blood pressure, random blood glucose, and diabetes. MRI measured volumes of cerebral white matter, abnormal white matter, cortical and subcortical gray matter, and ventricular and sulcal CSF. Multiple linear regression models allowed us to examine metabolic variables separately and in combination to predict each regional volume. Greater BMI was associated with smaller cortical gray and larger white matter volumes. Higher total cholesterol (C) levels were associated with smaller cortex volumes; higher LDL-C was associated with larger cerebral white matter volumes, while higher HDL-C levels were associated with larger sulci. Higher blood glucose levels and diabetes were associated with more abnormal white matter. Multiple atherogenic metabolic factors contribute to regional brain volumes in HIV-infected, CART-treated patients, reflecting associations similar to those found in HIV-uninfected individuals. These risk factors may accelerate cerebral atherosclerosis and consequent brain alterations and cognitive dysfunction.

Apolipoprotein E4 genotype does not increase risk of HIV-associated neurocognitive disorders.

This is a cross-sectional, observational study to evaluate the hypothesis that HIV-seropositive (HIV+) apolipoprotein E4 (APOE4) carriers are at increased risk for HIV-associated neurocognitive disorders (HAND) compared to APOE4 noncarriers with HIV in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) Group sample. APOE genotype was determined in 466 CHARTER participants with varying disease stages and histories of antiretroviral treatment who did not have severe psychiatric or medical comorbid conditions that preclude diagnosis of HAND. HAND diagnoses were based on results of comprehensive neurobehavioral evaluation and use of current neuroAIDS diagnostic criteria. HAND status consists of two levels: neuropsychologically normal status (i.e., no HAND) and any HAND diagnosis (i.e., asymptomatic neurocognitive impairment, minor neurocognitive disorder, HIV-associated dementia). Logistic regression analyses revealed no association between APOE4 carrier status and HAND, and there were no interactions between APOE4 carrier status and ethnicity, age, substance use disorders, duration of infection, or nadir CD4. Results did not differ when analysis was restricted to symptomatic HAND, and no APOE4 gene dose-dependent relationship to HAND emerged. APOE4 status was not associated with concurrent HAND in this large, well-characterized sample. This does not preclude emergence of an association between APOE4 status and HAND as this population ages. Prospective, longitudinal studies are needed to examine APOE4 as a risk factor for neurocognitive decline, incident HAND at older ages, and potential associations with cerebrospinal fluid amyloid.

Diagnosing symptomatic HIV-associated neurocognitive disorders: self-report versus performance-based assessment of everyday functioning.

Three types of HIV-associated neurocognitive disorders (HAND) exist that are distinguished by presence and severity of impairment in cognitive and everyday functioning. Although well-validated neurocognitive measures exist, determining impairment in everyday functioning remains a challenge. We aim to determine whether Self-Report measures of everyday functioning are as effective in characterizing HAND as Performance-Based measures. We assessed 674 HIV-infected participants with a comprehensive neurocognitive battery; 233 met criteria for a HAND diagnosis by having at least mild neurocognitive impairment. Functional decline was measured via Self-Report and Performance-Based measures. HAND diagnoses were determined according to published criteria using three approaches to assess functional decline: (1) Self-Report measures only, (2) Performance-Based measures only, and (3) Dual-method combining Self-Report and Performance-Based measures. The Dual-method classified the most symptomatic HAND, compared to either singular method. Singular method classifications were 76% concordant with each other. Participants classified as Performance-Based functionally impaired were more likely to be unemployed and more immunosuppressed, whereas those classified as Self-Report functionally impaired had more depressive symptoms. Multimodal methods of assessing everyday functioning facilitate detection of symptomatic HAND. Singular Performance-Based classifications were associated with objective functional and disease-related factors; reliance on Self-Report classifications may be biased by depressive symptoms.

Cliniconeuropathologic correlates of human immunodeficiency virus in the era of antiretroviral therapy.

The objective of this study was to examine the spectrum of human immunodeficiency virus (HIV) brain pathology and its clinical correlates in the antiretroviral era. We carried out a cross-sectional survey, analyzing prospective clinical and neuropathological data collected by the National NeuroAIDS Tissue Consortium (NNTC), comprising 589 brain samples from individuals with advanced HIV disease collected from 1999 onwards. We assessed gender, ethnicity/race, mode of transmission, age, year of death, nadir CD4, plasma viral load, last antiretroviral regimen, presence of parenchymal HIV brain pathology, HIV-associated neurocognitive disorder, and major depressive disorder. We compared cohort demographic variables with Centers for Disease Control and Prevention US HIV/AIDS statistics and examined associations of parenchymal HIV brain pathology with demographic, clinical, and HIV disease factors. With regard to Centers for Disease Control and Prevention US data, the NNTC was similar in age distribution, but had fewer females and African Americans and more Hispanics and men who have sex with men. Only 22% of the brains examined were neuropathologically normal. Opportunistic infections occurred in 1% to 5% of the cohort. Parenchymal HIV brain pathology was observed in 17.5% of the cohort and was associated with nadir CD4 and plasma viral load. Brains without parenchymal HIV brain pathology often had other noninfectious findings or minimal nondiagnostic abnormalities that were associated with HIV-associated neurocognitive disorder. Clinically, 60% of the cohort reported a lifetime episode of major depressive disorder and 88% had a HIV-associated neurocognitive disorder. No pathological finding correlated with major depressive disorder. Both antiretroviral treatment regimen and elevated plasma HIV viral load were associated with presence of parenchymal HIV brain pathology; however, multivariate analyses suggest a stronger association with plasma viral load. The frequency of HIV brain pathology was lower than previous pre-antiretroviral reports, and was predicted by lower nadir CD4 and higher plasma viral load. Noninfectious pathologies and minimal changes correlated with HIV-associated neurocognitive disorder, suggesting a shift in pathogenesis from florid HIV replication to other, diverse mechanisms.

Structural changes in lysosomes from cultured human fibroblasts in Duchenne's muscular dystrophy.

We have previously reported a decreased activity of the lysosomal enzyme dipeptidyl aminopeptidase-I (DAP-I) in cultured fibroblasts from patients with Duchenne's muscular dystrophy (DMD). Here we report that electron microscope examination of these cells reveals the presence of abundant lamellar bodies, a morphologic abnormalities commonly associated with impaired lysosomal function. Morphometric analysis of these cytoplasmic figures in dystrophic cells shows a sevenfold increase relative to normal controls (P less than 0.01). Analysis of lysosomal density profiles by density gradient centrifugation reveals similar patterns in normal and DMD cells. Treatment of lysosomes wit the nonionic detergent Triton X-100 causes an activation of DAP-I. This activation, attributable to structure-linked latency, is markedly diminished in DMD cells which show an optimal activation of only 180% compared to 255% for control fibroblasts (P less than 0.01). These data suggest an alteration in the properties of the lysosomal membrane in DMD fibroblasts. This suggestion is also supported by studies on the release of DAP-I from lysosomes by osmotic shock which show it to be a membrane-associated enzyme with membrane-binding characteristics intermediate between those of tightly bound beta-glucosidase and those of unbound N-acetylgalactosaminidase. The latency characteristics of these other lysosomal enzymes are not altered in the DMD cells, indicating that the effect is specific for DAP-I.

Cerebrospinal Fluid Ceruloplasmin, Haptoglobin, and Vascular Endothelial Growth Factor Are Associated with Neurocognitive Impairment in Adults with HIV Infection.

Dysregulated iron transport and a compromised blood-brain barrier are implicated in HIV-associated neurocognitive disorders (HAND). We quantified the levels of proteins involved in iron transport and/or angiogenesis-ceruloplasmin, haptoglobin, and vascular endothelial growth factor (VEGF)-as well as biomarkers of neuroinflammation, in cerebrospinal fluid (CSF) from 405 individuals with HIV infection and comprehensive neuropsychiatric assessments. Associations with HAND [defined by a Global Deficit Score (GDS) ≥ 0.5, GDS as a continuous measure (cGDS), or by Frascati criteria] were evaluated for the highest versus lowest tertile of each biomarker, adjusting for potential confounders. Higher CSF VEGF was associated with GDS-defined impairment [odds ratio (OR) 2.17, p = 0.006] and cGDS in unadjusted analyses and remained associated with GDS impairment after adjustment (p = 0.018). GDS impairment was also associated with higher CSF ceruloplasmin (p = 0.047) and with higher ceruloplasmin and haptoglobin in persons with minimal comorbidities (ORs 2.37 and 2.13, respectively; both p = 0.043). In persons with minimal comorbidities, higher ceruloplasmin and haptoglobin were associated with HAND by Frascati criteria (both p < 0.05), and higher ceruloplasmin predicted worse impairment (higher cGDS values, p < 0.01). In the subgroup with undetectable viral load and minimal comorbidity, CSF ceruloplasmin and haptoglobin were strongly associated with GDS impairment (ORs 5.57 and 2.96, respectively; both p < 0.01) and HAND (both p < 0.01). Concurrently measured CSF IL-6 and TNF-α were only weakly correlated to these three biomarkers. Higher CSF ceruloplasmin, haptoglobin, and VEGF are associated with a significantly greater likelihood of HAND, suggesting that interventions aimed at disordered iron transport and angiogenesis may be beneficial in this disorder.

Decreased lysosomal dipeptidyl aminopeptidase I activity in cultured human skin fibroblasts in Duchenne's muscular dystrophy.

Several lysosomal enzymes were assayed in cultured human skin fibroblasts from patients with Duchenne's muscular dystrophy (DMD) and age- and sex-matched control patients (N). The activity of four glycosidases, cathepsin B(1), and total autoproteolysis at pH 4.0 were unchanged between the groups, but dipeptidyl aminopeptidase I (DAP-I, or cathepsin C) in the DMD cells was found to be only 30% as active as in the control cells (P < 0.003). This difference is not the result of a redistribution or loss of enzyme during homogenization because the difference occurs in all homogenate fractions. DAP-I activity existing in N and DMD fibroblasts behaves identically with respect to activation by chloride ion, activation by the sulfhydryl reducing agent dithiothreitol, changes in hydrogen ion concentration (pH), changes in substrate concentration (i.e., apparent K(m) values), and changes in temperature (i.e., apparent activation energies). Mixtures of N and DMD cell sonicates display an additivity in DAP-I activity. These results support the conclusion that the catalytic function of the DAP-I molecule is equivalent between N and DMD fibroblasts, and that the decrease in tissue-specific DAP-I activity probably results from the fact that fewer enzyme molecules are present in the DMD cells. These results are also an indication that these nonmuscle cells are expressing some of the phenotypic aspects of the genetic defect in DMD. Cultured human skin fibroblasts may therefore be a useful cellular model in DMD research.

Interrater reliability of the Psychiatric Research Interview for Substance and Mental Disorders in an HIV-infected cohort: experience of the National NeuroAIDS Tissue Consortium.

The interrater reliability of the Psychiatric Research Interview for Substance and Mental Disorders (PRISM) was assessed in a multicentre study. Four sites of the National NeuroAIDS Tissue Consortium performed blinded reratings of audiotaped PRISM interviews of 63 HIV-infected patients. Diagnostic modules for substance-use disorders and major depression were evaluated. Seventy-six per cent of the patient sample displayed one or more substance-use disorder diagnoses and 54% had major depression. Kappa coefficients for lifetime histories of substance abuse or dependence (cocaine, opiates, alcohol, cannabis, sedative, stimulant, hallucinogen) and major depression ranged from 0.66 to 1.00. Overall the PRISM was reliable in assessing both past and current disorders except for current cannabis disorders when patients had concomitant cannabinoid prescriptions for medical therapy. The reliability of substance-induced depression was poor to fair although there was a low prevalence of this diagnosis in our group. We conclude that the PRISM yields reliable diagnoses in a multicentre study of substance-experienced, HIV-infected individuals.

The longevity of anti NSP antibodies and the sensitivity of a 3ABC ELISA - A 3 years follow up of repeatedly vaccinated dairy cattle infected by foot and mouth disease virus.

ELISA tests for detection of anti NSP antibodies are extensively used in surveys estimating exposure of livestock to foot and mouth disease virus as a part of endemic and post epidemic surveillance programs. Yet, estimation of the longevity of anti NSP antibodies in naturally infected cattle and the sensitivity of ELISA tests based on them were rarely studied to date. Our research aim was to estimate the long term (up to 1118 days after exposure) change in levels of anti NSP antibodies in dairy cattle individuals naturally infected by FMDV and to evaluate the sensitivity of a commercially available ELISA kit in detecting anti NSP antibodies during the follow up period. A 3ABC blocking ELISA kit (PrioCHECK(®) FMDV NS) was used in a 3 years follow up study of repeatedly vaccinated cattle, which were found to be NSP positive during an FMD outbreak in a dairy farm. In order to rule out the possibility of a recurrent FMD outbreak involving the study population we combined clinical and laboratory monitoring: Cattle which were located in the same herd and were previously found as negative to anti NSP antibodies were followed and did not present FMD symptoms or a serological conversion. The overall sensitivity for infection detection was calculated using two approaches. When a conservative approach was taken and equivocal results (45%≤PI≤55%) were treated as negative, the sensitivities were 95% (CI95%=75.1-99.9%), 88.2% (CI95%=63.6-98.5%) and 76.9% (CI95%=46.2-95%) 311, 689 and 1118 days after the outbreak, respectively. However, when equivocal results were treated as positive, the sensitivities were 100% (CI95%=83.2-100%), 94.1% (CI95%=71.3-99.9%) and 92.3% (CI95%=64-99.8%) 311, 689 and 1118 days after the outbreak, respectively. We therefore conclude that this test can serve as a valuable tool for detection of previous FMDV infection in cattle in endemic countries, where routine vaccinations are implied, even several years after exposure.

Seroprevalence of bovine ephemeral fever virus in domesticated and wildlife species during epidemic and inter-epidemic periods (2000-2009) in Israel.

Bovine ephemeral fever (BEF) is an economically important vector-borne viral disease of cattle and buffalo. It has been reported from most of the world's tropical and subtropical regions. In the last few decades, outbreaks of BEF have occurred in Israel almost every other year. Several serological studies have demonstrated a wide range of wild animal species that are positive for BEF virus (BEFV) antibodies. However, the question of whether wild animals and domesticated species other than cattle also play an important role in the maintenance and transmission of BEFV in Israel remains. Here, we examined the prevalence of anti-BEFV antibodies in 942 samples collected from various wild, semi-captive and domesticated animal species during the years 2000-2009 using the serum neutralization (SN) method. SN test revealed the presence of BEFV-neutralizing antibodies in nine samples (0.96%), from three species: Bubalus bubalis (4/29, 13.79%), Gazella g. gazella (3/68, 4.44%) and Dama d. mesopotamica (2/296, 0.68%). All positive samples were collected in areas of earlier outbreaks. The low prevalence of positive animals and the solid correlation with prior outbreaks indicate that the tested species probably do not serve as virus reservoirs and may play only a minor role in the maintenance of BEFV in the Middle East.

Microglial cell activation in aging and Alzheimer disease: partial linkage with neurofibrillary tangle burden in the hippocampus.

Microglial cells are the main component of the brain's resident immune system and are activated in Alzheimer disease (AD). We quantified the density of activated microglial cells (AMG) in 8 sectors of human hippocampus to determine if their density is correlated with senile plaque (SP) and neurofibrillary tangle (NFT) formation. Ferritin-stained microglia, Bielschowsky-stained neuritic plaques, and perikarya containing NFTs were counted in 8 young adults, 9 nondemented elderly adults, and 9 demented patients with AD. Microglial cell activation was moderately higher in elderly nondemented subjects. In AD there was a more striking activation in all sectors of the hippocampus. Most AMGs were distributed diffusely in neuropil and were not delimited to SPs or NFTs. Senile plaque counts were not linked with AMG counts within any sector. Neurofibrillary tangle counts were correlated significantly with AMG counts within one sector, the subiculum. When variations within and between sectors were factored out statistically, the burden of AMGs was correlated significantly with the burden of NFTs (r = 0.34; p < 0.005), but not SPs. Neuropathologic changes at the origin of the perforant pathway were correlated significantly with orthograde microglial cell activation in the termination field. These observations show that correlations between microglial cell activation and pathologic features of AD are only rarely significant. When significant linkage was present, it involved NFTs and not SPs, and depended on which sector of hippocampus was examined.

Macrophage apolipoprotein synthesis and endoneurial distribution as a response to segmental demyelination.

The synthesis and endoneurial distribution of apolipoproteins in response to myelin degradation was elucidated morphologically and biochemically in rodent models of segmental demyelination. At the onset of acute demyelination induced by tellurium (Te) poisoning, macrophages infiltrated the endoneurium and then began to express cytoplasmic immunoreactivity for apolipoprotein E (apo E). When demyelinating nerve slices were incubated with S35-methionine, radiolabeled apo E was released, showing that apo E was actively synthesized by the macrophages. Macrophages secreted apo E into the endoneurial spaces, leading to dense endoneurial accumulations. Other apolipoproteins (apo A1 and albumin) were not synthesized in the endoneurium, but they entered edematous nerves, presumably through an early breakdown in the blood-nerve barrier. During the phagocytosis of myelin, plasma-derived apolipoproteins accumulated within some of the macrophages. In chronic demyelination caused by lead poisoning, the cellular and extracellular distribution of apolipoproteins was similar to Te neuropathy; the amount of apo E accumulation and the macrophage density were proportional to the prevalence of active demyelination in teased fibers. Similar patterns of endoneurial apo E were present in an inherited form of demyelination in the twitcher mouse, after antibody-mediated demyelination, and in demyelination secondary to axonal degeneration. Human sural nerve biopsies had patterns of apolipoprotein E antigenicity that were comparable to the rodent models. We conclude that secretion of apo E by infiltrating macrophages is a generalized response to demyelination, and that endoneurial edema leads to the accumulation of certain plasma apolipoproteins within macrophages. These data suggest that endoneurial apolipoproteins and macrophages might mediate important functions in patients recovering from primary and secondary demyelination.

Quantifying apoptosis in banked human brains using flow cytometry.

Fragmentation of genomic DNA, a major biochemical feature of programmed cell death (apoptosis), is easily detected when apoptosis is prevalent. In brain tissue apoptotic cells are usually scarce and detection requires more sensitive techniques. We describe a highly sensitive method to quantify apoptosis in frozen human brain tissue using flow cytometry. Nuclei from homogenized brain specimens were isolated to purity using discontinuous isopyknic centrifugation through 2.2 M sucrose. DNA strand breaks in apoptotic nuclei were conjugated with biotinylated-dUTP using terminal deoxynucleotidyl transferase (TdT) and tagged with streptavidin-conjugated FITC (TUNEL). Negative controls excluding the TdT step, and positive controls using DNAase pretreatment to create 3'-OH strand breaks were run in parallel. The proportion of nuclei with TdT-dependent labeling in adult brain specimens was < 0.01% in 6 out of 7 specimens. In 3 fetal brains it averaged 0.86 +/- 0.11%. Apoptotic cells were readily detected in 2 malignant glial neoplasms and in a patient with HIV encephalitis. Comparable frequencies of stained nuclei were present in adjacent specimens embedded in paraffin and labeled in situ. By screening millions of nuclei cytometry detected very rare apoptotic events, producing quantitative results using banked frozen brains. The method has potential applications to studies of human brain development, neurodegenerative diseases, and brain tumors.

Apolipoprotein E is released by rat sciatic nerve during segmental demyelination and remyelination.

Apolipoprotein E (apo E) is synthesized and released in greatly increased amounts by peripheral nerve following Wallerian degeneration; it has been suggested that this protein may function in the transport of degenerated myelin lipid. The purpose of this study was to determine if the amount of apo E released by rat peripheral nerve is increased following selective demyelination, in the absence of significant axonopathy. Using an immunoturbidimetric assay, release of apo E from excised sciatic nerve segments was measured during the phases of acute demyelination and remyelination caused by tellurium (Te) toxicity, during segmental demyelination in chronic lead (Pb) poisoning, and during Wallerian degeneration following nerve crush. Morphologic changes were examined in contralateral sciatic nerves by nerve-fiber teasing or by light and electron microscopy of transverse sections. As in previous studies, the amount of apo E released from the nerves was greatly increased following Wallerian degeneration due to nerve crush. In Te neuropathy, increased release of apo E was first detected on the fourth day of Te exposure, corresponding temporally to the acute onset of paralysis and segmental demyelination. Apolipoprotein E release rose steeply to a maximum of ten times the control values by day 9 and then gradually waned during the next five weeks, corresponding to a period of active remyelination and resolution of the neuropathy. In the demyelinating neuropathy of chronic lead poisoning, apo E release was increased four times over control animals after seven weeks of exposure, with less than 10% of teased fibers showing early paranodal demyelination and no evidence of remyelination.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased vulnerability to demyelination in streptozotocin diabetic rats.

Demyelination is a prominent feature in nerve biopsies of patients with diabetic neuropathy. The mechanism is unknown because diabetic rodents, unlike humans, do not consistently develop segmental demyelination. We examined how diabetes influences toxicant-induced demyelination, remyelination, Schwann cell nerve growth factor receptor (p75) expression, and endoneurial macrophage apolipoprotein E (apo E) synthesis in diabetic rats. Postnatal day 17 (P17) rats were given 110 mg/kg streptozotocin intraperitoneally and then fed a diet containing metallic tellurium (Te) from P20 to P27 to induce demyelination. Transverse electron micrographs and immunostained longitudinal cryosections were prepared from sciatic nerve during demyelination and remyelination. Diabetic rats had a mean serum glucose concentration of 490 mg/dl and consumed equivalent doses of peroral Te. The number of demyelinated fibers in electron micrographs was increased significantly by 17% (P < .0011). Endoneurial density of p75-stained Schwann cells was increased in diabetic rats in proportion to the increased number of injured internodes. Density of apo E- and ED1-positive macrophages also was significantly increased in diabetes. There was no delay in macrophage myelin clearance. and remyelination was not compromised. Increased Schwann cell vulnerability to stress, by increasing the turnover rate of myelinated units, may explain why myelin defects accumulate after long-standing diabetes.

Decreased structure-linked latency of lysosomal dipeptidyl aminopeptidase-I activity in Duchenne muscular dystrophy fibroblasts.

Crude lysosomal pellets were prepared from skin fibroblasts grown from patients having Duchenne muscular dystrophy, and from normal controls. Disruption of the lysosomes by nonionic detergents resulted in the expression of latent activity of the enzyme dipeptidyl aminopeptidase-I(DAP-I). Duchenne lysosomes showed less structure-linked latency than those from normal controls, and sedimentation studies demonstrated that the difference was not caused by increased leakage of the enzyme from lysosomes. Permeability properties of the lysosomes for an artificial substrate revealed no difference of the apparent Km. However, in intact lysosomes the apparent K, for Cl- of this chloride-requiring enzyme was found to be lower in DMD lysosomes. The apparent increase in entry for Cl- was closely related with the decreased amount of the DAP-I latency. High concentrations of extra-lysosomal Cl- corrected the abnormality.

A host defense role for a natural antiviral substance in the nervous system.

The pathogenesis of virus infections of the nervous system (NS) is regulated by host defenses. The defensive role of a major constitutive antiviral substance was studied by determining its distribution in the human nervous system, its concentration and the ability of this viral inhibitor to protect mice against viral infection. The 4000 kDa inhibitor complex in the human nervous system was detected in brain gray and white matter, spinal cord, and sciatic nerve but not in human cerebrospinal fluid. The inhibitor was found in the extracellular medium incubated with minced murine brain. The inhibitory titer ranged from approximately 50 to 200 antiviral units per gram against polio 1, Semliki Forest, Banzi, mengo, Newcastle disease and herpes simplex 1 viruses. The inhibitor is composed of lipid and essential protein and carbohydrate moieties as determined by enzymatic inactivation. Protection of inhibitor-treated mice was demonstrated against both an alphavirus and a picornavirus. Thus a natural defensive role for the broadly antiviral inhibitor is suggested by its constitutively high concentration, wide distribution in nervous system tissues, presence in extracellular fluid and its ability to provide protection in infected mice.