Regulated expression of sodium-dependent glutamate transporters and synthetase: a neuroprotective role for activated microglia and macrophages in HIV infection?

It is now widely accepted that neuronal damage in HIV infection results mainly from microglial activation and involves apoptosis, oxidative stress and glutamate-mediated neurotoxicity. Glutamate toxicity acts via 2 distinct pathways: an excitotoxic one in which glutamate receptors are hyperactivated, and an oxidative one in which cystine uptake is inhibited, resulting in glutathione depletion and oxidative stress. A number of studies show that astrocytes normally take up glutamate, keeping extracellular glutamate concentration low in the brain and preventing excitotoxicity. This action is inhibited in HIV infection, probably due to the effects of inflammatory mediators and viral proteins. Other in vitro studies as well as in vivo experiments in rodents following mechanical stimulation, show that activated microglia and brain macrophages express high affinity glutamate transporters. These data have been confirmed in chronic inflammation of the brain, particularly in SIV infection, where activated microglia and brain macrophages also express glutamine synthetase. Recent studies in humans with HIV infection show that activated microglia and brain macrophages express the glutamate transporter EAAT-1 and that expression varies according to the disease stage. This suggests that, besides their recognized neurotoxic properties in HIV infection, these cells also have a neuroprotective function, and may partly make up for the inhibited astrocytic function, at least temporarily. This hypothesis might explain the discrepancy between microglial activation which occurs early in the disease, and neuronal apoptosis and neuronal loss which is a late event. In this review article, we discuss the possible neuroprotective and neurotrophic roles of activated microglia and macrophages that may be generated by the expression of high affinity glutamate transporters and glutamine synthetase, 2 major effectors of glial glutamate metabolism, and the implications for HIV-induced neuronal dysfunction, the underlying cause of HIV dementia.

Neuronal apoptosis in fatal familial insomnia

The possibility that neuronal loss in prion diseases occurs through an apoptotic process has been postulated and is consistent with the lack of inflammation in these disorders. In order to test this hypothesis in FFI, in which neuronal loss is the predominant neuropathological feature, we examined samples of thalamus, basal ganglia, cerebral cortex, cerebellum and medulla from 10 subjects with FFI. All the patients had the characteristic 178 N mutation of the PrP gene. Eight subjects were homozygous methionine/methionine at codon 129 and 2 were heterozygous methionine/valine. Apoptotic neurons were identified by in situ end labelling in all the FFI cases and in none of the controls. They were mostly found in damaged regions and their presence and abundance seemed to correlate closely with the neuronal loss. They were particularly abundant in the thalamus and medullary olives. In heterozygous cases who had a longer disease duration and more widespread cerebral changes, apoptotic neurons were also found in the neocortex and striatum. The abundance of apoptotic neurons also correlated well with microglial activation as demonstrated by the expression of major histocompatibility complex class II antigens. PrPres immunostaining was almost invariably negative, consistent with previous data showing the lack of obvious correlation between neuronal loss and PrPres deposits in prion diseases.

Devic disease with brainstem lesions

We describe a patient who suffered from an unusually severe form of neuromyelitis optica with a hyperacute time-course evolution requiring mechanical ventilation within 3 days. The patient died after 72 days and autopsy showed major spinal cord, optic nerve, and brainstem necrosis, and multifocal necrotic lesions on the cerebellum and cerebral white matter.

Search for the invisible decay of neutrons with KamLAND

The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or two-neutron intranuclear disappearance that would produce holes in the -shell energy level of (12)C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n--> 3v or nn--> 2v. The deexcitation of the corresponding daughter nucleus results in a sequence of space and time-correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: tau(n--> inv) > 5.8 x 10(29) years and tau (nn--> inv) > 1.4 x 10(30) years at 90% C.L. These results represent an improvement of factors of approximately 3 and >10(4) and over previous experiments.

Dilation of Virchow-Robin spaces in CADASIL

To precise the severity of dilated Virchow-Robin spaces (VRS) in CADASIL patients and to determine their correlation with clinical presentation and other abnormalities on cerebral Magnetic Resonance Imaging (MRI). Dilated VRS were previously associated with aging, hypertension, dementia, epilepsy or migraine. We already reported increased frequency of enlarged VRS in CADASIL patients when compared with family members without the affected haplotype. We analysed clinical and MRI data from 50 CADASIL patients collected prospectively in our center. The presence of dilated VRS was assessed in the subcortical white matter of temporal lobes, the centrum semi-ovale and the basal ganglia. Their severity in each region was evaluated according to the scale proposed by Heier. We compared the clinical data, the severity of white matter abnormalities and the presence of microbleeds in patients with and without dilated VRS. Seventy-eight percent of patients in our series had dilated VRS, mostly located in the lentiform nuclei (94%) and subcortical white matter of the temporal lobes (66%). The severity of these lesions was variable but not correlated neither to the extent of white matter abnormalities nor to the clinical presentation in our patients. Only the age was found to be related to the extent of dilated VRS. Dilated VRS are frequent in CADASIL and mostly located in the temporal white matter and basal ganglia. The dilation of perivascular spaces does not seem to be directly related to the occurrence of ischemic or hemorrhagic lesions in CADASIL. In contrast, the relation with age suggests that either aging, progression of vascular wall alterations during the course of the disease, or both of these processes can favour the extension of VRS in CADASIL.

Brain damage after heat stroke

Cerebellar syndromes and radiologic cerebellar atrophy after hyperpyrexia have occasionally been reported, mostly in neuroleptic malignant syndromes, but neuropathologic studies are extremely rare. We studied 3 patients (a 74-year-old woman, a 63-year-old man, and an 80-year-old man) who had heat stroke during heat waves in France. One patient had generalized seizures and died 28 hours after admission. The other patients survived one month and 2 months after admission; both had palatal myoclonus, and in one case, magnetic resonance imaging showed high signal intensity in the cerebral peduncles. The main neuropathology in the 3 cases was severe diffuse loss of Purkinje cells associated with heat shock protein 70 expression by Bergmann glia. In situ end labeling was negative in surviving Purkinje cells, suggesting that the mechanism of neuronal death was not apoptosis. Degeneration of Purkinje cells axons resulted in myelin pallor of the white matter of the folia and of the hilum of the dentate nuclei. DNA internucleosomal breakages were identified by in situ end labeling in the dentate nuclei and centromedian nuclei of the thalamus and were associated with degeneration of the cerebellar efferent pathways: superior cerebellar peduncles, decussation of the superior cerebellar peduncles (Wernekinck commissure), and dentatothalamic tract. These findings suggest that the mechanisms of neuronal death in the dentate nuclei and centromedian nuclei of the thalamus was different from that in Purkinje cells and more likely resulted from deafferentation. Ammon's horn and other areas susceptible to hypoxia were spared. These observations confirm the selective vulnerability of Purkinje cells to heat-induced injury and involvement of the cerebellar efferent pathways in palatal myoclonus.

Central nervous system immune reconstitution disease in acquired immunodeficiency syndrome patients receiving highly active antiretroviral treatment

Highly active antiretroviral therapy (HAART)-induced immune restoration has been very beneficial for acquired immunodeficiency syndrome (AIDS) patients. In rare instances, HAART may induce a paradoxical clinical deterioration due to an immune reconstitution inflammatory syndrome (IRIS). This syndrome has been described with a wide variety of systemic infections and, in the central nervous system, with Cryptococcus neoformans infection, cytomegalovirus retinitis, and progressive multifocal leukoencephalopathy (PML). The authors have examined brain tissue in eight cases of IRIS: two autopsy cases and three biopsy cases of HIV encephalitis with IRIS and one autopsy case and two biopsy cases of PML with IRIS. All the patients presented with clinical deterioration following initiation of HAART and imaging showed contrast enhancement of the lesions. The symptoms regressed in four patients whereas the other four patients died. Neuropathological examination revealed severe inflammatory and demyelinating lesions with marked intraparenchymal and perivascular infiltration by macrophages and T lymphocytes. In some cases abundant viral proliferation was identified by immunocytochemistry or in situ hybridization, but in others the infectious agent could only be detected using PCR. T lymphocytes were predominantly CD8(+). In those cases with the more favorable course, inflammation was less severe with marked macrophage activation and a number of CD4(+) lymphocytes; in contrast, in the lethal cases inflammation was severe and mostly composed of CD8(+) cytotoxic lymphocytes. We conclude that HAART-induced paradoxical aggravation of HIV encephalitis or AIDS-related PML due to IRIS is reversible in most cases but may be lethal in others. In fatal cases, fulminant viral infection and/or acute perivenous leukoencephalitis may result from a dysregulation of the CD8(+)/CD4(+) T-cell balance.

Experimental investigation of geologically produced antineutrinos with KamLAND

The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.

Fulminant inflammatory leukoencephalopathy associated with HAART-induced immune restoration in AIDS-related progressive multifocal leukoencephalopathy

HAART-induced immune restoration is beneficial for patients with AIDS-related progressive multifocal leukoencephalopathy (PML). However, in rare instances, an immune-reconstitution inflammatory syndrome (IRIS) may cause paradoxical clinical deterioration. We report the neuropathological study of an AIDS patient who presented with progressive cognitive deterioration; CD4(+) count was 117 and the HIV viral load >10(4); imaging showed non-enhancing lesions consistent with PML. Following initiation of HAART, CD4(+) was 300 and HIV viral load <10(3), but his neurological symptoms continued to deteriorate. Imaging revealed an increase in the size and number of lesions and enhancement of all the lesions. A stereotactic biopsy showed severe inflammatory and demyelinating lesions with marked infiltration by macrophages and T lymphocytes in the absence of a detectable infectious agent. Despite high doses of steroids, the patient died 3 months after admission. Autopsy showed two types of lesions: (1) active inflammatory PML changes with abundant JC virus, and intraparenchymal and perivascular infiltration by T lymphocytes, and (2) acute perivenous leukoencephalitis devoid of JC virus. Most lymphocytes were CD8(+) lymphocytes; CD4(+) lymphocytes were virtually absent. Two pathological reactions were associated with the paradoxical clinical deterioration related to dysregulation of the immune response characteristic of IRIS in PML: (1) an accentuation of JCV infection, and (2) a nonspecific acute perivenous leukoencephalitis. We suggest that both these types of lesions are due to an imbalance of CD8(+)/CD4(+) T cells, with massive infiltration of the cerebral parenchyma by CD8(+) cytotoxic T lymphocytes in the absence of sufficient CD4(+) response. Better understanding of the mechanisms of the IRIS may enable prevention or cure of this severe, sometimes fatal complication of HAART.

Measurement of neutrino oscillation with KamLAND: evidence of spectral distortion

We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.

Abeta-related angiitis: primary angiitis of the central nervous system associated with cerebral amyloid angiopathy

Idiopathic or primary angiitis of the CNS (PACNS) and cerebral amyloid angiopathy (CAA) are unusual vasculopathies generally regarded as unrelated disorders. A few case reports have, however, described granulomatous angiitis in patients with sporadic, amyloid beta peptide (Abeta)-related CAA. Here we describe the clinical, neuroradiological and neuropathological features of nine patients with Abeta-related angiitis (ABRA). Combining these with the individual case reports drawn from the literature has allowed us to define ABRA as a clinical entity and to compare its features with those of PACNS. The mean age of presentation of ABRA (67 years) is higher than that of PACNS but lower than that of sporadic non-inflammatory Abeta-related CAA. Alterations in mental status (59%), headaches (35%), seizures and focal neurological deficits (24%) are common. Hallucinations are a presenting manifestation in 12% of cases. Most patients have white matter hyperintensities on MRI but these are of similar appearance to those in PACNS. Cerebrospinal fluid usually shows modest elevation of protein and pleocytosis. Neuropathology reveals angiodestructive inflammation, often granulomatous, and meningeal lymphocytosis. Abeta is consistently present in abundance in affected blood vessels but usually scanty within the parenchyma of the cerebral cortex. However, the cortex includes numerous activated microglia, occasionally in a plaque-like distribution and containing cytoplasmic Abeta. The cerebral white matter shows patchy gliosis and rarefaction, in some cases marked. Our findings (i) help to dissect one separate clinicopathological entity from what is likely to be a spectrum of primary angiitides of the CNS; (ii) have important therapeutic implications for one category of patients with amyloid-related vasculopathy; and (iii) may provide valuable insights into the development of amyloid-associated inflammation, of relevance not only to ABRA but also to Abeta-immunization-related encephalitis and to Alzheimer's disease.

Cerebral CD8+ lymphocytosis in HIV-1 infected patients with immune restoration induced by HAART

In HIV infected persons, highly active antiretroviral therapy (HAART) has reduced both the morbidity and incidence of several disorders. Its effects on direct HIV-induced damage to the CNS remain controversial. In addition, HAART may provoke an "immune reconstitution inflammatory syndrome" (IRIS). Herein we report two patients who, despite HAART, developed a diffuse encephalopathy. Their clinical, radiological and neuropathological features are described. Immunohistochemical and PCR analyses were used to detect HIV and to exclude other viruses in brain tissue. The unusual inflammatory reaction in the brain tissue was defined by immunohistochemistry. Both patients had advanced HIV disease with low CD4 counts and high HIV "viral loads" before starting HAART. In both, HAART induced an increase in CD4 count and a marked reduction in HIV viral load, which was accompanied, in patient one, by worsening of pre-existing, and, in patient two, by development of, acute encephalopathy. At post-mortem examination, the brain of patient one showed HIV encephalitis. In addition, the brains of both patients revealed HIV-DNA by PCR, diffuse microglial hyperplasia and massive and diffuse perivascular and intraparenchymal infiltration by CD8+/CD4- lymphocytes. We suggest that the rapid immune reconstitution induced by HAART in these two patients led to a redistribution of lymphocytes into peripheral blood. This was followed by recruitment of CD8+ lymphocytes into the brain, which resulted in the diffuse infiltration described. The appearances in patient two further suggest that HIV brain infection, even without encephalitis, is sufficient to trigger this response.

The neuropathology of septic shock

The neuropathological correlates of encephalopathy and autonomic dysfunction in septic shock are unclear. We performed post mortem analysis of 5 brain areas susceptible to ischemia and 5 autonomic nuclei (AN) in 23 patients who had died in our intensive care unit (ICU) from septic shock and 8 dying from non-septic shock as well as 5 controls who had died suddenly from extracranial injury. Proinflammatory cytokine (IL1-beta and TNF-alpha) and inducible nitric oxide synthase (iNOS) expression was assessed by immunocytochemistry. Abnormalities in septic shock were: hemorrhages (26%), hypercoagulability syndrome (9%), micro-abscesses (9%), multifocal necrotizing leukoencephalopathy (9%) and ischemia (100%). The incidence of cerebral hemorrhage or hypercoagulability syndrome was not related to clotting disturbances. The intensity of ischemia within susceptible areas was the same in both ICU groups, but more pronounced in the autonomic centers of septic patients (P < 0.0001). Neuronal apoptosis assessed using anti-caspase 3 immunocytochemistry and in situ end labeling was more pronounced in the autonomic nuclei of septic patients. (P < 0.0001). TNF-alpha expression did not differ between groups but vascular iNOS expression assessed by immunocytochemistry was higher in sepsis (P<0.0001) and correlated with autonomic center neuronal apoptosis (P < 0.02). We conclude that septic shock is associated with diffuse cerebral damage and specific autonomic neuronal apoptosis which may be due to circulating factors particularly iNOS.

Neurotoxicité et neuroprotection, les deux facettes de l’activation microgliale au cours de l’infection par le virus de l’immunodéficience humaine (VIH)

Microglial cells and macrophages are the only cells within the central nervous system, in which productive HIV infection has been unquestionably demonstrated. Those cells play a key role in the origin of the neuronal dysfunction underlying HIV-related cognitive disorders. The neurotoxicity of the cells is both direct, related to HIV proteins, and indirect, through the release by activated macrophages and microglial cells (AMM) of multiple neurotoxic factors. The mechanisms of neuronal damage, the final irreversible stage of which is neuronal apoptosis, are only partly understood but appear to involve oxidative stress and glutamate-receptor mediated toxicity. On the other hand, recent experimental in vitro and in vivo studies, and neuropathological studies in HIV infected patients at different stages of the disease, tend to show that AMM express excitatory amino acid transporters (EAAT) suggesting that in addition to their neurotoxic properties, they also have a neuroprotective role by clearing extra-cellular glutamate and producing antioxidant glutathione. This neuroprotective role could counteract, at least in the early stages of the disease, the neurotoxicity of AMM explaining the discrepancy between the conspicuous microglial activation at that stage and the absence of cognitive disorder, neuronal loss and neuronal apoptosis. It could also explain the regression of the cognitive disorders in some patients who received highly active antiretroviral treatment.

[The neuropathology of HIV infection in the era of highly active antiretroviral therapy]

Introduction of Highly Active Antiretroviral Treatment (HAART) which is available for most AIDS patients in France since 1996, has resulted in a dramatic improvement of the disease course. From the survey of our autopsy series of (AIDS) cases and the review of other neuropathological studies from different developed countries, we found quantitative and qualitative changes in the pattern of human immunodeficiency virus (HIV) neuropathology. Quantitatively, there was a dramatic decrease in the number of autopsy cases but brain involvement remained a major cause of death in AIDS patients. There was an overall decrease of cerebral toxoplasmosis, cytomegalovirus encephalitis (CMVE) and HIV encephalitis (HIVE) for which successful treatment is available. This contrasted with the unchanged incidence of progressive multifocal leucoencephalopathy (PML) and primary malignant non Hodgkin brain lymphomas (PMBL). However, when looking closer at the last three years, the incidence of diseases affecting patients with severe immunodepression (CMVE, PML, PMBL) decreased in 2000-2002, whereas infections occurring in patients with milder immunodeficiency (toxoplasmosis, varicella-zoster encephalitis (VZVE) or herpes simplex virus encephalitis (HSVE) became more frequent. Qualitatively, there were uncommon types of brain infections, such as BK virus encephalitis or general paresis. Finally, new forms of HIVE were reported: severe leukoencephalopathy with intense perivascular macrophage and lymphocyte infiltration possibly due to an exaggerated response from a newly reconstituted immune system; and also chronic "burnt out" forms of HIVE as VZVE, toxoplasmosis, or PML in which no inflammation and no infectious agent could be detected, likely due to prolonged survival.

Expression of excitatory amino acid transporter-1 in brain macrophages and microglia of HIV-infected patients. A neuroprotective role for activated microglia?

Recent experimental studies showed that activated macrophages/microglia (AMM) express excitatory amino acid transporters (EAATs), suggesting that, in addition to their neurotoxic properties, they also have a neuroprotective role by clearing extracellular glutamate and producing antioxidant glutathione. To test this hypothesis in human, the brain of 12 HIV-positive patients and 3 controls were immunostained for EAAT-1. EAAT-1 was expressed by AMM in all HIV-infected cases but not in HIV-negative controls. Expression varied according to the disease stage. In 5 cases with active HIV-encephalitis (HIVE), AMM strongly expressed EAAT-1 in the white matter and basal ganglia, analogous to HLA-DR and CD68 expression. There was weaker expression in the cortex and perineuronal microglial cells were not involved. In a case with "burnt out" HIVE following highly active antiretroviral therapy (HAART), EAAT-1 expression was mild, identical to that of HLA-DR and CD68 in the white matter and cortex and involved perineuronal microglial cells. In 3 AIDS patients without HIVE and in 3 pre-AIDS cases, EAAT-1 expression in the white matter was weaker than HLA-DR and CD68 expression; there was stronger correlation in the gray matter where perineuronal microglial cells were stained predominantly. Our findings in humans tend to confirm that AMM, particularly perineuronal microglial cells, play a neuroprotective role in the early stages of HIV infection and, possibly, following treatment. This is in keeping with the early microglial activation seen in pre-AIDS cases, and the late occurrence of neuronal loss. It may also explain the reversible cognitive disorders following treatment in some cases.

The changing pattern of HIV neuropathology in the HAART era

Highly active antiretroviral treatment (HAART), which has been available for most AIDS patients in France since 1996, has resulted in a dramatic improvement of the progression of the disease. From the survey of our series of 343 brains with acquired immunodeficiency syndrome (AIDS) from patients who died between 1985 and 2002, we found both quantitative and qualitative changes in the pattern of human immunodeficiency virus (HIV) neuropathology. Quantitatively, despite a dramatic decrease in the number of autopsies, brain involvement remained a major cause of death. There was an overall decrease in incidence of cerebral toxoplasmosis, cytomegalovirus encephalitis (CMVE), and HIV encephalitis (HIVE), for which successful treatment is available. This contrasted with the unchanged incidence of progressive multifocal leukoencephalopathy (PML) and malignant non-Hodgkin lymphomas (MNHL). However, when looking closer at the 3 last years, the incidence of diseases affecting patients with severe immunodepression (CMVE, PML, and MNHL) decreased between 2000 and 2002, whereas infections occurring in patients with milder immunodeficiency, toxoplasmosis, varicella-zoster encephalitis (VZVE), or herpes simplex virus encephalitis (HSVE) became more frequent. In addition, we found uncommon types of brain infection such as BK virus encephalitis or general paresis. Finally, we described new variants of HIVE: severe leukoencephalopathy with intense perivascular macrophage and lymphocyte infiltration, possibly due to an exaggerated response from a newly reconstituted immune system, and chronic "burnt out" forms of HIVE as VZVE, toxoplasmosis, or PML, possibly associated with prolonged survival, in which neither inflammation nor organisms could be detected. These findings are compared with those reported in other neuropathological studies from different developed countries.

Effectiveness of dietary advice given by community dietitians to men with elevated blood cholesterol in a clinical setting: a pilot study

OBJECTIVE

To compare the effect of two types of dietary advice given by community dietitians on subsequent dietary intake in Scottish men, over 8 weeks.

DESIGN

A parallel design intervention study was employed. Twenty-five men with elevated blood cholesterol levels were randomly assigned to Group 1 (advice to reduce dietary fat only) or Group 2 (advice to reduce dietary fat and sugar).

RESULTS

Neither group significantly reduced fat intakes, yet both groups self-rated their fat intake as being lower at the end than at the start of the study. Group 2 reduced per cent energy from sugar and increased per cent energy from starch without significantly changing per cent energy from total carbohydrate. No significant change in blood cholesterol levels were observed.

CONCLUSIONS

Advice to reduce dietary fat was not effective in this group of subjects. Advice to reduce both fat and sugar resulted in a decrease in sugar intake only. Both groups wrongly rated their fat intake to be lower at the end of the study. This may be a barrier to further dietary advice.

Expression of excitatory amino acid transporter-2 (EAAT-2) and glutamine synthetase (GS) in brain macrophages and microglia of SIVmac251-infected macaques

Na+-dependent transporters for glutamate (excitatory amino acid transporters, EAATs) clear extracellular glutamate in the brain and prevent excitotoxic neuronal damage. Glutamine synthetase (GS) provides metabolic support for neurones by producing the neurotrophic amino acid glutamine. EAAT and GS expression has recently been demonstrated in macrophages and microglial cells in vitro, and in two models of acute inflammation in vivo. This observation might modify our current understanding of brain inflammation, which considers activated microglia and brain macrophages as the main neurotoxic cells through their production of a variety of neurotoxins, including glutamate. EAAT and GS expression by these cells would entail neuroprotective and neurotrophic properties, counterbalancing the deleterious consequences of microglial activation. Macaque infection by the simian immunodeficiency virus (SIV) is considered the most relevant model for human acquired immunodeficiency syndrome (AIDS), including chronic inflammation of the brain at the early asymptomatic stage of the infection, followed by an AIDS-like disease where neuronal death occurs. We studied the expression of EAAT-2 and GS in the brains of three SIVmac251-infected and two noninfected cynomolgus macaques. We found that both microglia and brain macrophages expressed EAAT-2 and GS in infected primates, suggesting that these cells might, like astrocytes, clear extracellular glutamate and provide glutamine to neurones. Microglia and macrophages could thus have neuroprotective and neurotrophic properties in addition to their production of neurotoxins. This finding might explain the contrast between early intense microglial activation and the late occurrence of neuronal apoptotic cell death, which is mainly observed at the terminal stage of the disease.

Multifocal necrotizing leukoencephalopathy in septic shock

OBJECTIVE

Multifocal necrotizing leukoencephalopathy, characterized by multiple microscopic foci of necrosis involving the white matter of the pons, has been described mainly after chemotherapy or radiotherapy for brain cancer and in HIV infection. The role of circulating cytokines has been suggested but remains to be assessed.

DESIGN

Prospective case series.

SETTING

A 26-bed general medical intensive care unit at a university hospital.

PATIENTS

Septic shock patients. MEASUREMENTS AND PATIENTS: In three patients who died from septic shock, careful postmortem examination of the brain was performed, including studies of neuronal apoptosis and cytokine expression.

MAIN RESULTS

In one patient, typical lesions of multifocal necrotizing leukoencephalopathy were seen. As compared with control 1 and control 2 who did not have multifocal necrotizing leukoencephalopathy, marked lesions of the pons, including vacuolization, apoptosis, microglial activation, and expression of tumor necrosis factor-alpha and interleukin-1beta, were observed in the case. Simultaneously, case 1 had markedly increased circulating levels for tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, interleukin-8, interleukin-10, soluble tumor necrosis factor receptor II, and for interleukin-1 receptor antagonist.

CONCLUSION

Septic shock is a newly described cause of multifocal necrotizing leukoencephalopathy, probably mediated by an excessive systemic inflammatory response.

[Physiopathology of meningoencephalitis caused by Cryptococcus neoformans]

Cryptococcus neoformans is an encapsulated yeast mainly responsible for meningoencephalitis, especially in AIDS patients. Recent observations using an experimental model of systemic cryptococcosis that mimics the human infection have reinforced the knowledge on the pathogenesis of cryptococcosis. Cryptococcosis may occur several years after inhalation of infecting particles from the environment. A stage of fungemia that reflects the dissemination of infection usually precedes the development of meningoencephalitis. The capsule mainly composed of glucuronoxylomannan constitutes the main virulence factor of C. neoformans. It has several deleterious effects including the inhibition of the host immune responses. The central nervous system involvement differs between AIDS patients and HIV-negative patients. In AIDS patients, histological studies of the brain show numerous cryptococci without significant inflammatory cell response. In other immunodepressed hosts, a granulomatous inflammation containing few yeasts is usually seen. This may reflect an altered local immunological defect against C. neoformans in AIDS patients with cryptococcosis.

Pathogenesis of cerebral Cryptococcus neoformans infection after fungemia

The pathogenesis of cerebral infection after Cryptococcus neoformans fungemia in outbred mice was investigated. Confocal microscopy and cultures on ficoll-hypaque gradient-separated blood cells were used to detect yeasts in the cytoplasms of monocytes. In semithin brain sections, poorly capsulated yeasts were seen in macrophages in the leptomeningeal space, in monocytes circulating in leptomeningeal capillaries, or in the endothelial cells themselves, strengthening the hypothesis that monocytes and endothelial cells play key roles in the pathogenesis of cryptococcal meningitis. Similar fungal loads and cellular reactions were seen in mice and in 1 patient with acquired immune deficiency syndrome (AIDS), all with acute cryptococcal meningoencephalitis, and in mice and in 1 patient with AIDS, all with cured cryptococcal infection. Immunostaining revealed both the presence of cryptococcal polysaccharide in various brain cells and antigenic variability both from yeast cell to yeast cell and over time. Thus, our data established the relevance and interest that this experimental model has for investigation of the pathogenesis of human cryptococcal meningitis.

Severe progressive form of congenital muscular dystrophy with calf pseudohypertrophy, macroglossia and respiratory insufficiency

A novel form of congenital muscular dystrophy in four unrelated patients is proposed. Congenital hypotonia, markedly increased CK, calf pseudohypertrophy and proximal weakness were common early findings. Two cases were severely affected since infancy and never walked. The phenotypical homogeneity was not very evident until advanced stages of the disease. All the patients showed catastrophic progression of the weakness, severe restrictive respiratory insufficiency, macroglossia, peculiar extreme amyotrophy of hands and feet, and a round and 'puffy' face. All patients became tetraplegic and required mechanical ventilation. Two cases had signs of mild cardiac involvement. The only non-tracheotomised patient died of respiratory complications. No mental retardation or specific brain abnormalities were observed. All patients showed secondary deficit of laminin 2 and up-regulation of laminin 5 in muscle. Expression of -dystroglycan was severely reduced in two available muscle samples. The known loci for congenital muscular dystrophies were excluded in the only consanguineous case by linkage analysis. Clinical, immunohistochemical and genetic findings strongly suggest a distinct entity.

[Brain biopsy in systemic diseases]

In systemic diseases, brain biopsy is an exceptional diagnostic procedure which must be restricted to those rare forms involving only the central nervous system, at least clinically, and when a treatable disease is suspected the treatment of which requires a precise histological diagnosis. According to the clinical presentation and radiological appearance, an open biopsy or a stereotactic biopsy under radiological control will be proposed. In this paper, will be reviewed the indications and neuropathological findings in systemic amyloidoses extending to the central nervous system, cerebral angiitis, sarcoidosis, Whipple's disease, Langerhans'cell as well as non-Langerhans'cell systemic histiocytoses and paraneoplastic encephalomyelitis.

[Hashimoto's encephalopathy: an anatomicoclinical observation]

Hashimoto's encephalopathy (HE) is a rare neurological complication of chronic lymphocytic thyroiditis. As its clinical presentation is aspecific, other etiologies of acute encephalopathy have to be ruled out. We report the case of a 29-year old woman with neuropsychiatric signs preceding coma, myoclonus and epileptic seizures. Clinical and electroencephalographic features were consistent with the diagnosis of new variant of Creutzfeldt-Jakob disease. However, high titres of antithyroid antibodies in serum directed towards the diagnosis of HE. Despite oral steroids, the patient died five months later. Neuropathological findings ruled out spongiform encephalopathy and disclosed aspecific activated microglia. Our observation suggests that this process could be involved in the pathogenesis of HE. Even in the absence of clinical dysthyroidism, HE diagnosis has to be suspected in the settings of acute encephalopathy associated with seric antithyroid antibodies.

Depletion of neurohypophyseal content of vasopressin in septic shock

OBJECTIVES

To assess the mechanisms underlying the inappropriately low plasma vasopressin levels reported in septic shock.

DESIGN

Prospective case series.

SETTING

A 26-bed general medical intensive care unit at a university hospital.

PATIENTS

Septic shock patients.

MEASUREMENTS AND MAIN RESULTS

In three consecutive patients with septic shock, plasma vasopressin levels, circulating vasopressinase activity, baroreflex sensitivity, and neurohypophyseal vasopressin content were assessed. Plasma vasopressin concentration was unexpectedly within normal range in two patients (1.6 pg/mL and 1.8 pg/mL) and increased in one (16 pg/mL). In all cases, vasopressinase activity was undetectable, baroreflex sensitivity was decreased, and the high signal intensity of the posterior lobe of the pituitary gland on T1-weighted magnetic resonance images was absent. Magnetic resonance imaging and plasma vasopressin levels normalized after recovery from shock in the patient who survived.

CONCLUSION

These data suggest that in septic shock, inappropriately low plasma levels of vasopressin are at least partly related to a depletion of vasopressin stores in the neurohypophysis.

Symmetrical necrosis of the solitary tract nuclei as a contributory cause of death

A 64-year-old man died in spite of surgery 4 days after attempting suicide. He first tried to hang himself with a rope and when the hanging did not succeed, he cut his throat with a knife. The autopsy showed four sutured cervical wounds with laryngeal wounds but without associated important vascular injury. The neuropathological study revealed two watershed-type haemorrhagic infarcts, involving the left occipital lobe and the left cerebellum. It also showed a symmetrical necrosis of solitary tract nuclei in the medullary tegmentum. Such a lesion is likely to result from sudden acute transient circulatory failure and might have played a role in the secondary autonomous cardiac and respiratory dysfunctions following a non-lethal trauma.

[Hereditary cerebral amyloid angiopathies]

Cerebral amyloid angiopathies are defined by the presence of amyloid substance in the walls of cerebral vessels. All amyloid substances have a particular physico-chemical structure, which imparts certain specific staining properties, but the biochemical composition of different amyloid types varies. Different forms of cerebral amyloid angiopathy have been identified, based on the biochemical nature of the protein deposited (e.g. beta-amyloid, cystatin C, transthyretin, gelsolin, amyloid protein Bri, prion protein). Some cerebral amyloid angiopathies are familial; these prompted genetic studies which in turn led to a better understanding of the genes coding for different amyloid proteins. As a group, cerebral amyloid angiopathies have certain neuropathological lesions in common. Infiltration by amyloid substance results in weakening of the small vessel walls and secondary complications responsible for changes such as microinfarcts and miliary haemorrhages in the cerebral cortex, lobar haemorrhages and/or leucoencephalopathy. These changes form the basis of the neurological complications: meningeal and cerebral haemorrhages, transient ischaemic episodes, vascular dementia. However each type of hereditary cerebral amyloid angiopathy has individual clinical and histopathological features reflecting the severity of arterial involvement, the extent of amyloid deposition within or outside the central nervous system, and the association with other neurodegenarative changes.

Neuropathology and neurodegeneration in human immunodeficiency virus infection. Pathogenesis of HIV-induced lesions of the brain, correlations with HIV-associated disorders and modifications according to treatments

A variety of HIV-induced lesions of the central nervous system (CNS) have been described, including HIV encephalitis, HIV leukoencephalopathy, axonal damage, and diffuse poliodystrophy with neuronal loss of variable severity resulting, at least partly, from an apoptotic process. However, no correlation could be established between these changes and HIV dementia (HIVD). From our study of HIV infected patients, it appeared that neuronal apoptosis is probably not related to a single cause. Microglial and glial activation, directly or indirectly related to HIV infection, plays a major role in neuronal apoptosis possibly through the mediation of oxidative stress. In our patients with full-blown AIDS, this mechanism predominated in the basal ganglia and correlated well with HIVD. Axonal damage, either secondary to microglial activation, or to systemic factors also contributes to neuronal apoptosis. Although massive neuronal loss may be responsible for HIVD in occasional cases, we conclude that neuronal apoptosis is a late event and does not represent the main pathological substrate of HIVD. The dementia more likely reflects a specific neuronal dysfunction resulting from the combined effects of several mechanisms, some of which may be reversible. Introduction of highly active antiretroviral therapy dramatically improved patient survival, however, its impact on the incidence and course of HIVD remains debatable. In our series, the incidence of HIVE has dramatically decreased since the introduction of multitherapies, but a number of cases remain whose cognitive disorders persist, despite HAART. The poor CNS penetration of many antiretroviral agents is a possible explanation, but irreversible "burnt out" HIV-induced CNS changes may also be responsible.

Precise measurement of the positive muon anomalous magnetic moment

A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.

[Familial orthochromatic leukodystrophy: clinicopathological study of two cases]

This paper reports the clinico-pathological data in a French family with orthochromatic leukodystrophy. The parents were first cousins and had seven children. Among those, two sisters and one brother presented with neurological signs, with onset around the 5(th) decade, including a dementing syndrome of frontal type, a tetrapyramidal syndrome, seizures, and, in one sibling, a cerebellar syndrome. CT scan or MRI showed diffuse involvement of the white matter. The neurological signs worsened progressively leading to death within 11 and 22 months. Neuropathological examination was performed in two cases. It revealed characteristic orthochromatic leukodystrophy. In one case, the presence of pigmented macrophages and astrocytes was suggestive of Van Bogaert and Nyssen disease. However there were some atypical features including the absence of pigmented cells in the second case whose clinical course was shorter, and the cavitary appearance of the white matter changes with a relative increase in the number of oligodendrocytes raising the issue of a possible link between this condition and cavitary orthochromatic leukodystrophies.

Progressive multifocal leukoencephalopathy and oligodendroglioma in a monkey co-infected by simian immunodeficiency virus and simian virus 40

A rhesus monkey experimentally inoculated with simian immunodeficiency virus (SIV) mac251 was killed 42 months later because of poor general condition. CD4 lymphocyte count which was 3,430/mm3 before inoculation, had decreased to 638/mm3 2 months before death. Neuropathological examination revealed changes characteristic of progressive multifocal leukoencephalopathy (PML) in the white matter of the cerebral hemispheres and brain stem. In situ hybridization was negative for JC virus but markedly positive for simian virus 40 (SV40) in the nuclei of many oligodendrocytes. Many oligodendrocytes also expressed p53. Within an area involved by PML, there was a densely cellular tumor with honeycomb appearance and elongated vessels characteristic of oligodendrogliomas. Within the tumor in situ hybridization for SV40 and immunocytochemistry for p53 were negative. Opportunistic infection by SV40 has been occasionally reported in experimentally SIV-infected monkeys resulting in PML or malignant astrocytoma. Association of JC virus-induced PML and astrocytomas has been reported in three human cases without AIDS. In those cases, as in our monkey, polyomaviruses (SV40 or JC virus) were expressed in the areas with PML but not in the glial tumor. Association of PML and oligodendroglioma has not been reported previously to our knowledge. The relationship between oligodendrocyte proliferation and polyomavirus infection of oligodendrocytes is unclear. Our findings suggest that binding of the viral protein to p53 may result in inactivation of the pro-apoptotic protein favoring the proliferation of a randomly occurring tumoral clone of oligodendrocytes.

Corneal endothelial cell apoptosis in patients with Fuchs' dystrophy

PURPOSE

To investigate whether apoptosis plays a notable role in degeneration of corneal endothelial cells in patients with Fuchs' dystrophy.

METHODS

Forty-seven corneal buttons from 41 patients with Fuchs' dystrophy were studied. Nucleus labeling, transmission electron microscopy (TEM), and TdT-dUTP terminal nick-end labeling (TUNEL) were used to detect apoptosis. TEM and TUNEL were performed on sections of all 47 corneal buttons, and nucleus labeling was performed on the last 10 corneas. Seven human donor corneas, two corneal buttons from two patients with keratoconus, and one corneal button from a patient with interstitial keratitis were used as negative controls for detection of apoptotic endothelial cells. Negative controls were studied by means of nucleus labeling, TUNEL, and TEM.

RESULTS

In the nucleus labeling assay, the average percentage of apoptotic endothelial cells was 2.65% in the Fuchs' dystrophy group (n = 10) and 0.23% in the control group (n = 10; P = 0.0003). In the TUNEL assay, labeling of some endothelial cells was observed on 42 of 47 corneas in the Fuchs' dystrophy group, whereas it was absent on most specimens of the control group. In TEM, most endothelial cell nuclei had a normal appearance, and apoptotic endothelial cells featuring condensed nucleus and decreased cell size could be observed exceptionally. Some apoptotic cells were found in the basal epithelial cell layer by means of nucleus labeling, TUNEL, and TEM in the Fuchs' dystrophy group but not in the control group.

CONCLUSIONS

This study suggests that apoptosis plays an important role in endothelial cell degeneration in Fuchs' dystrophy. Because of a lack of conclusive evidence of increased endothelial apoptosis by TEM, further studies are needed to ascertain this finding.

Association of herpes simplex virus encephalitis and paraneoplastic encephalitis - a clinico-pathological study

A 57 year-old woman developed acute limbic encephalitis and brainstem dysfunction. Anti-HU antibodies were repeatedly detected in serum and CSF. Postmortem examination showed necrotic and hemorrhagic lesions in the temporal lobes characteristic of herpes simplex virus encephalitis, which was confirmed by immunocytochemistry, and Purkinje cell loss with proliferation of Bergman glia and myelin loss in the external aspect of the dentate nuclei characteristic of paraneoplastic encephalitis. PCR-assay performed on temporal tissue extracts was positive for HSV-1. There was no identifiable neoplasm. This unusual association raises the possibility of a link between the two diseases.

Neuronal apoptosis in human immunodeficiency virus infection

Neuronal apoptosis has been shown to occur in HIV infection by a number of in vivo and in vitro studies, however, the cause of neuronal damage in AIDS is still unclear and its relationships with the cognitive disorders characteristic of HIV dementia remain a matter of debate. In this review, based on our experience, we analyse the techniques used to identify neuronal apoptosis on post-mortem AIDS brains and describe the relationships of neuronal apoptosis with the stage of disease, a history of HIV-dementia, the degree of productive HIV infection, microglial activation, blood-brain barrier involvement and axonal damage. We conclude that the severity of neuronal apoptosis in the cerebral cortex correlates with the presence of cerebral atrophy, but not with the cognitive disorders. There is no global quantitative correlation between neuronal apoptosis and HIV encephalitis, microglial activation or axonal damage. However we found some topographical correlation between these changes. We conclude that neuronal apoptosis and consequent neuronal loss, in HIV infected patients, are probably not related to a single cause. It seems likely that microglial activation, directly or indirectly related to HIV infection of the CNS, plays a major role in its causation possibly through the mediation of oxidative stress. Axonal damage, either secondary to microglial activation, or to the intervention of systemic factors may also contribute to neuronal apoptosis.

[A case of progressive multifocal leukoencephalopathy in AIDS: neuroimaging with clinical and pathologic correlation]

We present the neuroimaging features with clinical and pathologic correlation in a case of Progressive Multifocal Leukoencephalopathy (PML) in AIDS. CT and MRI showed typical lesions of PML. At pathology examination, characteristic lesions of PML were found in association with HIV encephalitis due to CNS infection by the virus.

Cytokine profiles of AIDS patients are similar to those of mice with disseminated Cryptococcus neoformans infection

Cryptococcosis is an hematogenously disseminated meningoencephalitis during which the relationship between the disease severity and the immune response remains unclear. We thus analyzed, by enzyme-linked immunosorbent assay, proinflammatory (tumor necrosis factor alpha [TNF-alpha] and interleukin-6 [IL-6]) and anti-inflammatory (IL-10) cytokine levels in plasma at the time of diagnosis in 51 AIDS patients with culture-proven cryptococcosis. We used a murine model to determine the correlation between cytokine levels and fungal burden in blood and tissues and the kinetics of the immune response and of the formation of cerebral lesions. In AIDS patients, plasma TNF-alpha and IL-10, but not IL-6, levels were significantly higher in the case of fungemia or disseminated infection than in their absence, whereas the presence of meningitis had no influence on these levels. In mice, none of these cytokines were detected within the first day after inoculation. Later on, TNF-alpha and IL-10, but not IL-6, levels in plasma correlated significantly with the fungal burden in the blood and spleen but not the brain. In the brain, cytokine levels were low compared to those in other compartments, and tissue lesions and a degree of infection similar to those observed in humans were seen, further suggesting the relevance of this experimental model. Thus, AIDS patients with cryptococcosis produce an immune response that reflects the dissemination but not the meningeal involvement. This murine model of disseminated cryptococcosis can be used to investigate the pathophysiology of cryptococcosis and new therapeutic approaches.