Sex- and region-specific differences in microglia phenotype and characterization of the peripheral immune response following early-life infection in neonatal male and female rats

Early-life infection has been shown to have profound effects on the brain and behavior across the lifespan, a phenomenon termed "early-life programming". Indeed, many neuropsychiatric disorders begin or have their origins early in life and have been linked to early-life immune activation (e.g. autism, ADHD, and schizophrenia). Furthermore, many of these disorders show a robust sex bias, with males having a higher risk of developing early-onset neurodevelopmental disorders. The concept of early-life programming is now well established, however, it is still unclear how such effects are initiated and then maintained across time to produce such a phenomenon. To begin to address this question, we examined changes in microglia, the immune cells of the brain, and peripheral immune cells in the hours immediately following early-life infection in male and female rats. We found that males showed a significant decrease in BDNF expression and females showed a significant increase in IL-6 expression in the cerebellum following E.coli infection on postnatal day 4; however, for most cytokines examined in the brain and in the periphery we were unable to identify any sex differences in the immune response, at least at the time points examined. Instead, neonatal infection with E.coli increased the expression of a number of cytokines in the brain of both males and females similarly including TNF-α, IL-1β, and CD11b (a marker of microglia activation) in the hippocampus and, in the spleen, TNF-α and IL-1β. We also found that protein levels of GRO-KC, MIP-1a, MCP1, IP-10, TNF-α, and IL-10 were elevated 8-hours postinfection, but this response was resolved by 24-hours. Lastly, we found that males have more thin microglia than females on P5, however, neonatal infection had no effect on any of the microglia morphologies we examined. These data show that sex differences in the acute immune response to neonatal infection are likely gene, region, and even time dependent. Future research should consider these factors in order to develop a comprehensive understanding of the immune response in males and females as these changes are likely the initiating agents that lead to the long-term, and often sex-specific, effects of early-life infection.

Cerebellar bacterial brain abscess: report of eight cases

PURPOSE

To analyze the clinical characteristics and therapeutic outcome of patients with solely cerebellar bacterial brain abscess (BBA).

CASE REPORT

Eight patients with solely cerebellar BBA, collected during a period of 23 years from 210 BBA patients, were included in this study. The eight patients were five men and three women, aged 5-54 years (mean, 36.6 years). Six of them were adults, one was a child, and one was an adolescent. Six patients had underlying medical/surgical problems. Of the clinical presentations, dizziness was the most common (87.5%, 7/8), followed by headache (62.5%, 5/8), altered consciousness (62.5%, 5/8), fever (50%, 4/8), ataxia (25%, 2/8), hearing impairment (12.5%, 1/8), dysarthria (12.5%, 1/8), and hemiparesis (12.5%, 1/8). The Image Severity Index (ISI) scores of these eight patients ranged from 6 to 12 points. All eight patients received both medical and surgical treatment. One patient died owing to a complication in the neurosurgical procedure and the remaining patients survived. The therapeutic outcome was quantified one month after discharge by modified Rankin scale (mRS) and the result showed six of the seven survivors had good outcomes, while the other one had a poor outcome (ataxic gait).

CONCLUSION

Cerebellar BBA accounted for 3.8% (8/210) of the overall BBA. In cerebellar BBA, dizziness is a frequent symptom. Early diagnosis and a combination of antimicrobial and neurosurgical intervention is important for its treatment. The small case number is a limitation of this study; therefore, further large-scale study of cerebellar BBA is needed for better delineation of the clinical characteristics, therapeutic outcome, and prognostic factors.

Lyme disease of the brainstem

Lyme disease is a multisystem infectious disease caused by the tick-borne spirochete, Borrelia burgdorferi. Central nervous system (CNS) involvement typically causes local inflammation, most commonly meningitis, but rarely parenchymal brain involvement. We describe a patient who presented with clinical findings suggesting a brainstem process. Magnetic resonance imaging (MRI) and positron emission tomography (PET) suggested a brainstem neoplasm. Prior to biopsy, laboratory evaluation led to the diagnosis of Lyme disease. Clinical and imaging abnormalities improved markedly following antimicrobial therapy. We describe Lyme disease involvement of the cerebellar peduncles with hypermetabolism on PET. Although MRI is the primary imaging modality for most suspected CNS pathology, the practical applications of PET continue to expand.

[Pathomorphology of cerebral cryptococcosis in immunodeficiencies of various etiology]

A wide spectrum of pathomorphological changes in the brain was revealed. They reflect various periods of cryptococcal infection under various conditions of immunodeficiency. In cases of brain cryptococcosis in HIV-infection, a significant spread of necrotic changes was noted. The dependence of structural changes severity in the brain on the size of fungal burden is found. It is shown that the disturbance of structural integrity of microvessel wall, its destruction under the influence of cryptococci is a major factor causing penetration of this infection directly into the substance of the brain.

Brain abscess secondary to the middle ear cholesteatoma: a report of two cases

We experienced two cases of brain abscess secondary to middle ear cholesteatoma. One, a 61-year-old woman, presented with left otalgia, appetite loss and nausea. The computed tomography obtained on admission revealed a middle ear cholesteatoma. The magnetic resonance image showed the presence of a brain abscess in the cerebellum. The brain abscess was drained and the cholesteatoma was removed using the canal down procedure under general anesthesia. Part of the cholesteatoma invaded the posterior cranial fossa was could not be removed from the otological surgical field. The patient has been under observation as an outpatient for 6 months already and no abnormal signs have been detected. The other patient, a 55-year-old man, was admitted to our hospital for a detailed examination because he had right otalgia and progressive headache. The examination of spinal fluid obtained by lumbar puncture showed marked elevation of the white blood cells count. Computed tomography revealed a middle ear cholesteatoma. The magnetic resonance image obtained on admission showed an area of low-intensity encapsulated by an area of high-intensity in the right temporal lobe. The abscess was drained and the cholesteatoma was removed using the canal down procedure under general anesthesia. The patient has been under observation for 1 year already and has presented no signs of recurrence.

Sequential activation of constitutive and inducible nitric oxide synthase (NOS) in rat cerebellar granule neurons by Pseudomonas fluorescens and invasive behaviour of the bacteria

Previous studies have shown that Pseudomonas fluorescens and its lipopolysaccharide (LPS) exert dose-related cytotoxic effects on neurons and glial cells. In the present work, we investigated the time course effect of P. fluorescens MF37 and its LPS on cultured rat cerebellar granule neurons. The kinetics of binding of P. fluorescens to cerebellar granule neurons is rapid and reaches a mean of 3 bacteria/cell after 5 h. As demonstrated by measurement of the concentration of nitrite in the culture medium, P. fluorescens induces a rapid stimulation (3 h) of the nitric oxide synthase (NOS) activity of the cells. In contrast, LPS extracted from P. fluorescens requires a long lag phase (24 h) before observation of an activation of NOS. Measurement of the membrane resting potential of granule neurons showed that within 3 h of incubation there was no difference of effect between the action of P. fluorescens and that of its endotoxin. Two complementary approaches allowed to demonstrate that P. fluorescens MF37 presents a rapid invasive behaviour suggesting a mobilisation of calcium in its early steps of action. The present study reveals that P. fluorescens induces the sequential activation of a constitutive calcium-dependent NOS and that of an inducible NOS activated by LPS. Our results also suggest that in P. fluorescens cytotoxicity and invasion are not mutually exclusive events.

[Occipital dermal sinus associated to a cerebellar abscess. Case]

Congenital dermal sinuses are tubular tracts which communicate the skin with deeper structures. It is a manifestation of defective separation of the ectoderm and neuroderm. The incidence is 1/2500-3000 births alive. Almost 10 % of congenital dermal sinuses are localized in the occipitocervical region. They are usually asymptomatic, unless an infectious process is concurrent (meningitis, abscess). We are presenting the case of a 12 months girl with unnoticed cutaneous stigmata in the occipital region, who was admitted with a meningeal syndrome and secondary neurological impairment. She had a cerebellar abscess and was treated with decompression by puncture of the abscess and antibiotics. When infection was resolved, congenital dermal sinus was excised. Process solves without morbidity. We reviewed the clinical and therapeutic features in cases reported previously in the literature.

Protective role of NF-κB1 (p50) in experimental pneumococcal meningitis

Nuclear factor-kappaB (NF-kappaB) is a critical regulator of many genes involved in the pathogenesis of bacterial meningitis. Recently, activation of NF-kappaB was shown to be a key event in the inflammatory host response and the development of intracranial complications during experimental pneumococcal meningitis. Since the p50 subunit of NF-kappaB lacks a transactivation domain and can therefore act as a transcriptional repressor, we investigated whether NF-kappaB1 (p50) exerts anti-inflammatory effects in pneumococcal meningitis. p50-deficient mice had higher cerebellar pneumococcal titers (10.06+/-0.47 vs. 8.51+/-1.06 log colony-forming units [cfu]/cerebellum), cerebrospinal fluid (CSF) leukocyte counts (11,475+/-2340 vs. 8444+/-1405 cells/microl) and brain concentrations of interleukin-1beta (125.9+/-50.3 vs. 58.5+/-52.2 pg/mg protein) than their wild-type littermates. With ceftriaxone therapy, none of the wild-type mice but 43% of the p50-deficient animals died. In conclusion, lack of NF-kappaB1 (p50) was associated with impaired bacterial clearing, enhanced inflammatory host response and increased mortality during pneumococcal meningitis.

Direct detection of leptospiral material in human postmortem samples

Leptospiral culture, direct immunofluorescence, and the polymerase chain reaction (PCR) were used to detect leptospiral material in postmortem specimens collected from eight patients who died of leptospirosis. Diagnosis of leptospiral infection was based on clinical summary (premortem) and confirmed by serological analysis and/or culture of leptospires. Leptospiral culture was the least sensitive technique, yielding two isolates (3%) from 65 samples. Both isolates were from the aqueous humour and cerebrospinal fluid of the same patient. Direct immunofluorescence was of intermediate sensitivity for detection of leptospires, confirming the presence of leptospires in 11% (2 of 18) of tissue samples from three patients. PCR analysis was the most sensitive technique for detection of leptospiral material in tissue samples, being positive in 20% (11 of 56) of samples from eight patients. Both samples (cerebellum and liver) positive by immunofluorescence were also positive by PCR. The sensitivity of the PCR assay was 1-10 leptospires ml(-1) sample, and the assay was specific for Leptospira pathogenic species. Multi-system involvement was indicated based on successful amplification of leptospiral DNA from more than one tissue sample, which corroborated with the clinical and pathologic findings. The results suggest that in acute and/or fatal leptospirosis, the pathogenesis of the pathologic features are related to the presence of the organisms in the tissues. In conclusion, PCR combined with serology appears to be a useful tool for diagnosis of leptospirosis and may be invaluable in epidemiological studies.

Patterns of cerebral inflammatory response in a rabbit model of intrauterine infection-mediated brain lesion

Although the fetal inflammatory response syndrome seems crucial to the association between intrauterine infection and white matter disease in human preterm infants, the underlying mechanisms remain unclear. Using our previously described rabbit model of cerebral cell death in the white matter and hippocampus induced by intrauterine Escherichia coli infection, we investigated inflammatory and astroglial responses in placenta and brain tissues, in correlation with cell death distribution. Brains and placentas were studied 12, 24, or 48 h following intrauterine inoculation of E. coli or saline (groups G12, G24, and G48). Diffuse monocyte-macrophage infiltrates positive for inducible nitric oxide synthase (i-NOS) were significantly more marked in G24 and G48 placentas than in controls. In the G48 fetuses with both diffuse cell death and focal periventricular white matter cysts mimicking cystic periventricular leukomalacia, a strong rabbit macrophage and inducible nitric oxide synthase immunostaining was observed at the border of these cystic lesions. In contrast, in the fetuses with only diffuse and significant cell death, no inflammatory or astroglial responses were detected in the white matter or hippocampus. Cell death was accompanied by i-NOS immunostaining in the hippocampus but not the white matter. Hippocampal cells positive for i-NOS usually displayed a neuronal phenotype. In this model, focal white matter cysts are accompanied by a robust inflammatory response, and diffuse cell death, which may mimic the white matter and hippocampal damage seen in very and extremely pre-term infants, occur in the absence of a detectable brain inflammatory response.

Isolated intracranial infection with Mycobacterium avium complex

Mycobacterium avium-M. complex (MAC) has been linked to devastating respiratory and systemic illnesses in patients, especially in those who are immunosuppressed. The purpose of this study is to describe a case of isolated central nervous system (CNS) infection with MAC. This is a single case report of a patient with isolated intracranial mycobacterial infection.

SETTING

the patient was treated and the immunohistochemical investigations were undertaken at the National Institutes of Health in Bethesda, Maryland, USA.

INTERVENTION

the patient initially was treated with a cocktail of antimycobacterial medications. However, because his disease was refractory, he underwent a suboccipital craniotomy and evacuation of his cerebellar mass. The patient was determined to have a low production of interferon-gamma (INF-gamma) and tumor necrosis factor-alpha (TNF-alpha) when compared to normal values. Despite extensive radiographic imaging studies and biopsies, there was no evidence of another focus of MAC infection in this patient. We conclude that intracranial infectious lesions in patients such as ours should be treated with conventional systemic antibiotic regimens as the first-line of therapy. We suggest neurosurgical intervention in medically refractory cases of intracranial infections.

Toll-like receptor 2 participates in mediation of immune response in experimental pneumococcal meningitis

Heterologous expression of Toll-like receptor (TLR)2 and CD14 in Chinese hamster ovary fibroblasts was reported to confer responsiveness to pneumococcal peptidoglycan. The present study characterized the role of TLR2 in the host immune response and clinical course of pneumococcal meningitis. Pneumococcal infection of mice caused a significant increase in brain TLR2 mRNA expression at both 4 and 24 h postchallenge. Mice with a targeted disruption of the TLR2 gene (TLR2-/-) showed a moderate increase in disease severity, as evidenced by an aggravation of meningitis-induced intracranial complications, a more pronounced reduction in body weight and temperature, and a deterioration of motor impairment. These symptoms were associated with significantly higher cerebellar and blood bacterial titers. Brain expression of the complement inhibitor complement receptor-related protein y was significantly higher in infected TLR2-/- than in wild-type mice, while the expression of the meningitis-relevant inflammatory mediators IL-1beta, TNF-alpha, IL-6, macrophage-inflammatory protein (MIP)-2, inducible NO synthase, and C3 was similar in both genotypes. We first ectopically expressed single candidate receptors in HEK293 cells and then applied peritoneal macrophages from mice lacking TLR2 and/or functional TLR4 for further analysis. Overexpression of TLR2 and TLR4/MD-2 conferred activation of NF-kappaB in response to pneumococcal exposure. However, pneumococci-induced TNF-alpha release from peritoneal macrophages of wild-type and TLR2/functional TLR4/double-deficient mice did not differ. Thus, while TLR2 plays a significant role in vivo, yet undefined pattern recognition receptors contribute to the recognition of and initiation of the host immune defense toward Streptococcus pneumoniae infection.

Acute cerebellitis

Many recent reports of acute cerebellitis with a critical or potentially critical course have changed the conception of the disease from an acute cerebellar ataxia with a benign course to a notable disease entity with a heterogeneous pathogenesis. The most characteristic finding by magnetic resonance imaging is diffuse cortical swelling of the cerebellum, often complicated by hydrocephalus or tonsillar herniation. A timely assessment and appropriate choice of treatment, including surgical intervention when indicated, are key to improving the outcome of affected patients.

[Role of non-spore-forming anaerobic microflora in the onset and development of otogenic abscesses of the brain and cerebellum]

The role of non-spore-forming anaerobic microflora in development of otogenic cerebral and cerebellar abscesses was studied in 49 patients with brain abscesses. Microfloral study of the middle ear discharge and content of cerebral abscess demonstrates that at present the role of pathogenic pyogenic staphylococci, streptococci and other kinds of purulent infection is lower than that of previously unreported non-spore-forming anaerobs in the pus of otogenic brain abscesses. It means that urgent sanation of the primary focus and cerebral abscesses should be supplemented with targeted combined antibacterial conservative therapy.

A case of aspergillosis in a broiler breeder flock

A case of aspergillosis in a broiler breeder flock having respiratory and nervous system problems caused by Aspergillus fumigatus and Aspergillus niger is documented. Dyspnea, hyperpnea, blindness, torticollis, lack of equilibrium, and stunting were observed clinically. On postmortem examination of the affected birds, white to yellow caseous nodules were observed on lungs, thoracic air sacs, eyes, and cerebellum. Histopathologic examination of lungs and cerebellum revealed classic granulomatous inflammation and cerebellar lesions, necrotic meningoencephalitis, respectively. No lesions were noted in the cerebrum histopathologically. Aspergillus hyphae were observed in stained sections prepared from lesioned organs. Fungal spores and branched septate hyphae were observed in direct microscopy. Aspergillus fumigatus and A. niger were isolated from the inoculations prepared from the suspensions of organs showing lesions.

Disseminated Cladophialophora bantiana infection in a heart transplant recipient

Cerebral phaeohyphomycosis caused by Cladophialophora bantiana, a dematiaceous fungus, is a rare disease. The majority of cases have been reported among immunocompetent patients; only 4 cases have been published that describe transplantation patients. The overall prognosis is poor. Surgical therapy in combination with chemotherapy with itraconazole is recommended. We report the case of a heart transplant recipient with cutaneous, cerebral, and lung manifestation of Cladophialophora bantiana who died despite surgical and systemic, high-dosage itraconazole treatment.

Multiple nocardial abscesses of cerebrum, cerebellum and spinal cord, causing quadriplegia

In this paper we present a case of a diabetic patient with nocardial abscesses of cerebrum, cerebellum and the spinal cord. The present case is the first case in the literature of solitary intramedullary abscess in cervical spinal cord, causing tetraplegia. Nocardia asteroides grew in a culture of the abscess pus. After either surgical excision or drainage of lesions, a triple combination regimen of chemotherapy (amikacin, ceftriaxone and trimethoprim-sulfamethoxazole) was given, but the patient was lost in the postoperative period. This case gives suggestive evidence of an association between cervical spinal cord involvement and poor prognosis in CNS nocardiosis.

Surgical treatment of coenurosis (gid) in sheep

During the past six years 623 cases of coenurosis (gid) in sheep have been treated surgically. Cysts were removed successfully from 573 of them (92 per cent) and 517 (83 per cent) were able to return to their flocks, although 36 showed no clinical improvement In 37 cases, the cyst could not be localised, and postmortem examinations showed that in nine cases the cyst was in the brainstem, and in 28 cases it was in the cerebellum. Fifty-six cases deteriorated gradually after surgery and in these cases more than one cyst was found postmortem. Thirteen cases died during surgery.

Flaccid quadriplegia from tonsillar herniation in pneumococcal meningitis

A young woman with fulminant pyogenic meningitis became quadriplegic, areflexic and flaccid due to herniation of the cerebellar tonsils and compression of the upper cervical cord. This state of spinal shock was associated with absent F-waves. Intracranial pressure was greatly elevated and there was an uncertain relationship of tonsillar descent to a preceding lumbar puncture. Partial recovery occurred over 2 years. Tonsillar herniation can cause flaccid quadriplegia that may be mistaken for critical illness polyneuropathy. This case demonstrates cervicomedullary infarction from compression, a mechanism that is more likely than the sometimes proposed infectious vasculitis of the upper cord.

Escherichia coli O157:H7 causes more-severe systemic disease in suckling piglets than in colostrum-deprived neonatal piglets

Our objective was to determine if suckling neonatal piglets are susceptible to enterohemorrhagic Escherichia coli (EHEC) O157:H7 disease. Surprisingly, EHEC O157:H7 caused more-rapid and more-severe neurological disease in suckling neonates than in those fed an artificial diet. Shiga toxin-negative O157:H7 did not cause neurological disease but colonized and caused attaching-and-effacing intestinal lesions.

Otogenic lateral sinus thrombosis in children

INTRODUCTION

The clinical picture of lateral sinus thrombosis (LST) has changed with the advent of antibiotics, as have the utility of various diagnostic tests. LST may appear in children as a complication of acute otitis media, but nowadays it is more frequently encountered in adults with long-standing chronic ear disease.

METHOD

A retrospective study of all the pediatric patients with LST between 1982 and 1997.

RESULTS

Thirteen cases of LST were diagnosed and treated by our department. In six cases, LST was due to acute otitis media and in the remaining cases it was due to chronic otitis media. Headache, fever, aural discharge and mastoid tenderness were the most frequent findings in these patients and four patients were initially diagnosed with meningitis. In the majority of the patients, LST was accompanied with other intracranial complications, such as perisinus abscess, brain abscess and meningitis. One patient with multiple brain abscesses, unresponsive to several drainage procedures, died. The other patients recovered and have since been followed-up as out-patients.

CONCLUSION

LST may be difficult to diagnose due to previous antibiotic treatment and to the overlap of clinical findings with other entities such as meningitis. Despite the value of modern imaging techniques in the investigation of the disease, a high index of suspicion based on the clinical picture is warranted. Our results are consistent with those of other recent studies, who found that mortality of LST has dropped below 10%.

Acute cerebellitis caused by Coxiella burnetii

We report a childhood case of severe acute cerebellitis caused by Coxiella burnetii. After 10 days of fever and headache, the patient fell into a drowsy state. Examination of the cerebrospinal fluid (CSF) revealed pleocytosis, an increased level of protein, and negative results in bacterial and viral studies. Magnetic resonance imaging demonstrated a herniated tonsil compressed by the swollen vermis. Administration of minocycline relieved the patient's clinical symptoms. C. burnetii was isolated from the CSF obtained during convalescence.

[Cerebral abscess of otogenic origin located simultaneously in the temporal and cerebellar regions]

A 28-year-old male was seen for chronic left ear disease. A brain abscess appeared in the left temporal lobe and later spread to the cerebellum. Diagnosis was clinical and radiological. Intravenous antibiotic treatment resulted in resolution of the temporal abscess on CT. However, a new abscess that appeared in the left cerebellar hemisphere required neurosurgical debridement. The patient's microbiological cultures and history suggested an otological origin. Brain abscess is a serious complication of ear disease that requires early diagnosis and treatment.

Nitric oxide and prostaglandin E2 formation parallels blood-brain barrier disruption in an experimental rat model of bacterial meningitis

During meningitis, the host produces a plethora of signaling agents as part of a coordinated defense mechanism against invading pathogens. Nitric oxide (NO) and prostaglandin E2 (PGE2) are two such inflammatory mediators produced in response to bacterial endotoxins. Disruption of the blood-brain barrier (BBB) is one of many pathophysiological consequences of meningitis. The present objective was to examine the time-course of NO and PGE2 production in relationship to BBB permeability alterations during experimentally-induced meningitis. Meningeal inflammation was elicited by intracisternal administration of the bacterial endotoxin, lipopolysaccharides (LPS; 200 microg), and NO, PGE2, and BBB integrity were monitored over the next 24 h. Meningeal NO production was assessed by headspace chemiluminescence; cerebrospinal fluid PGE2 was determined by enzyme-linked immunosorbent assay (ELISA) immunoassay; and BBB integrity was determined by the brain accumulation of 14C-sucrose. Similar time-course profiles for NO and PGE2 were observed, with a peak effect for both inflammatory mediators observed within 6-8 h after intracisternal LPS dosing. Statistically significant (p < 0.05) disruption of the BBB was observed in various brain regions. Strikingly similar temporal relationships were observed for NO and PGE2 production and BBB disruption. These results suggest the hypothesis that NO and PGE2 may act in conjunction to disrupt the BBB during experimental meningitis.

Central nervous system abscesses due to Coccidioides species

Meningitis occurs in one-third to one-half of patients with disseminated coccidioidomycosis, but mass lesions have rarely been described; these lesions are usually found at autopsy. We report six cases of disseminated coccidioidomycosis with central nervous system (CNS) abscesses. Four patients had cerebellar involvement, and two had spinal cord involvement. Four patients were diabetic, and two subsequently died. Review of the literature on CNS coccidioidomycosis indicated that parenchymal brain involvement occurs in 1%-33% of cases, and < 40 cases with mass lesions have been reported since 1905. Almost all patients were male and had other active disseminated foci of coccidioidomycosis. In approximately one-third of all cases, meningitis was absent. Brain lesions may be superficial or deep and multiple or single. In the absence of meningitis, serology of cerebrospinal fluid is negative. Hematogenous origin appears to be more common than direct extension from the meninges. Spinal cord involvement is rare. Diabetes was present in several cases, thus suggesting a vascular predisposition. We hope our experience will increase awareness of this entity, which appears to be more common than previously appreciated, and will facilitate diagnosis.

Myeloencephalitis associated with a viridans group Streptococcus in a colony of Japanese macaques (Macaca fuscata)

Five weaned immature Japanese macaques (Macaca fuscata), bred in captivity, showed nervous signs over a 12-month period. Hemorrhagic cerebral infarcts with vasculitis were detected in four necropsied animals. The distribution and nature of the lesions were consistent with bacterial embolism, and a Streptococcus isolate, biochemically similar to S. salivarius, was recovered from the cerebral lesions from three of the four necropsied macaques. Treatment with antibacterial agents (enrofloxacin) improved the clinical condition of the surviving affected animal. These observations strongly suggest that this Streptococcus spp., member of the viridans group, is responsible for this outbreak. Dental pulpitis, present in two of the four macaques, probably served as the entry for this bacterium.

[Cerebellar abscess by Nocardia: a case report]

The authors describe a case of cerebellar abscess by Nocardia in a patient with the acquired immunodeficiency syndrome (AIDS) that was submitted to a posterior fossa craniectomy for diagnosis and treatment. Pathological and neuroimage findings are discussed as well as the surgical approach taking into account literature data on the subject.

Teratogenic effects of neonatal arenavirus infection on the developing rat cerebellum are abrogated by passive immunotherapy

The effects of viral infection on the developing nervous system and the potential of passive immunotherapy to protect against infection were examined. When 4-day-old Lewis rats were injected intracerebrally with lymphocytic choriomeningitis virus (LCMV) the majority of stem cells within the external granular layer of the developing cerebellum became infected. The infection progressed to the molecular layer, internal granular layer, and the Purkinje cells. By 15 days postinfection the molecular and internal granular layers of LCMV-infected cerebella were noticeably thinner than those in the controls and the individual folia were smaller. Neurons remained infected for up to 40 days as determined by immunohistochemistry. However, in rats treated with rat monoclonal anti-LCMV antibodies the staining was limited to the cells of ependyma and choroid plexus and was not detectable by 15 days postinfection. Macroscopically the infection resulted in pronounced hypoplasia, with the cerebella of 21-day-old LCMV-infected rats weighing 52 +/- 10 mg compared with 159 +/- 30 mg for control rats. Antibody-treated rats exhibited normal cerebellar size and development. Neutralizing antibodies specific for the viral GP-1 glycoprotein were protective but nucleoprotein-specific antibodies were not. Furthermore, suckling rat pups born of and nursed by LCMV-immune mothers were spared from cerebellar disease following neonatal infection. These results suggest that passive immunotherapy of neonates can provide effective protection against teratogenic effects of neonatal viral infection on the developing CNS.

Intracerebral hemorrhages and syncytium formation induced by endothelial cell infection with a murine leukemia virus

The mechanisms of endothelial cell damage that lead to cerebral hemorrhage are not completely understood. In this study, a cloned murine retrovirus, TR1.3, that uniformly induced stroke in neonatal BALB/c mice is described. Restriction digest mapping suggests that TR1.3 is part of the Friend murine leukemia virus (FMuLV) family. However, unlike mice exposed to other FMuLVs, mice infected with TR1.3 virus developed tremors and seizures within 8 to 18 days postinoculation. This was uniformly followed by paralysis and death within 1 to 2 days. Postmortem examination of TR1.3-inoculated mice revealed edematous brain tissue with large areas of intracerebral hemorrhage. Histologic analysis revealed prominent small vessel pathology including syncytium formation of endothelial cells. Immunohistochemical analysis of frozen brain sections using double fluorescence staining demonstrated that TR1.3 virus specifically infected small vessel endothelial cells. Although infection of vessel endothelial cells was detected in several organs, only brain endothelial cells displayed viral infection associated with hemorrhage. The primary determinant of TR1.3-induced neuropathogenicity was found to reside within a 3.0-kb fragment containing the 3' end of the pol gene, the env gene, and the U3 region of the long terminal repeat. The restricted tropism and acute pathogenicity of this cloned murine retrovirus provide a model for studying virus-induced stroke and for elucidating the mechanisms involved in syncytium formation by retroviruses in vivo.

SSPE in Slovakia: immunocytochemical study

In a retrospective study of two patients from Slovakia with clinical, virological and histopathological diagnosis of subacute sclerosing panencephalitis (SSPE), measles virus antigen was detected by immunocytochemical labelling studies. The formalin fixed, paraffin-embedded thin brain sections labelled with anti-measles antibodies and avidin-biotin complex peroxidase were counterstained with haematoxylin. Only a single area of brain was examined in each patient: cerebellum and parietal lobe. Viral antigen positive reaction was identified within Purkinje cells and extending along dendritic processes in cerebellum, and also in oligodendrocytes of subparietal white matter.

Brain vascular endothelial cells express JC virus large tumor antigen in immunocompetent and cyclophosphamide-treated hamsters

When injected intracerebrally into newborn hamsters, the human polyomavirus JC virus (JCV) establishes a nonproductive infection resulting in brain tumor formation. Using immunostaining methods to detect the JCV regulatory protein, large tumor antigen (T antigen), we have now demonstrated JCV infection of brain vascular endothelial cells (EC) in infected hamsters. JCV T antigen was detected in lectin-labeled EC as well as in von Willebrand factor-expressing EC in both cyclophosphamide-treated and nonimmunosuppressed hamster brains 16, 21, and 31 days after birth. Cyclophosphamide-treated hamsters exhibited a greater number of JCV-infected EC, whereas T-antigen expression in nonvascular cells was not affected. The influence of cyclophosphamide was most pronounced in the cerebellum where increased numbers of JCV-infected EC were located predominantly at the internal granular layer-white matter junction, also a prominent location for T-antigen-expressing neoplastic foci. The hamster model demonstrates in vivo infection of EC by a human polyomavirus and directs interest toward the role of these cells in human JCV infection.

Molecular characterization of a JC virus (Sap-1) clone derived from a cerebellar form of progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by polyomavirus JC (JCV). In the majority of cases of PML the cerebrum is mainly affected (cerebral PML) but on rare occasions lesions are restricted to the cerebellum and brain stem (cerebellar PML). We report a rare cerebellar PML case which occurred in a Japanese patient undergoing prolonged hemodialysis treatment. To understand the molecular basis of the viral tissue tropism, we molecularly cloned JCV DNA and compared it with those of cerebral PML. Of ten clones analyzed nine showed identical fragment patterns after digestion with various restriction endonucleases, and we designated these clones Sap-1. It could be shown that the basic structures of the regulatory regions are similar between Sap-1 and isolates from cerebral PML. Restriction endonuclease mapping analysis was used to examine the genetic relationship between Sap-1 and urine-derived isolates containing the archetypal regulatory sequence. We found that Sap-1 was genetically related to an archetypal JCV isolate in Japan.

Borna disease: association with a maturation defect in the cellular immune response

Borna disease virus (BDV) is a negative-strand RNA virus which produces persistent infection in a variety of experimental animals. In the rat, the presence or absence of clinical signs of Borna disease, a characteristic, biphasic neurobehavioral illness, depends on host-related factors. A window of opportunity exists after birth wherein inoculation with BDV produces a persistently infected rat without signs of Borna disease or encephalitis (persistent, tolerant infection-newborn [PTI-NB] rat). Although immunopathological destruction of the nervous system does not occur in the PTI-NB rat, significant alterations in the development of the nervous system were noted, including site-specific lysis of neurons. Unlike the case with other pharmacologically produced, persistent, tolerant BDV infections, adoptive transfer of spleen cells from BDV-infected rats did not produce disease in the PTI-NB rats. PTI-NB rats developed Borna disease after being connected by parabiosis to rats with Borna disease. Bone marrow transplantation experiments revealed that bone marrow cells from PTI-NB rats produced Borna disease in lethally irradiated, BDV-infected recipient rats. Bone marrow from PTI-NB rats contained a complement of inflammatory cells capable of inducing Borna disease. Thus, the loss of BDV-specific cellular immunity appeared to occur after the release of cells from the bone marrow.

Natural scrapie: detection of fibrils in extracts from the central nervous system of sheep

Extracts from the cervical spinal cord and from the medulla, thalamus, cerebellum and cerebral cortex of the brains of 10 sheep, histopathologically confirmed as cases of scrapie, were examined by electron microscopy for the presence of scrapie-associated fibrils. Characteristic fibrils were observed in all the extracts except for that from the thalamus of one sheep. No fibrils were found in any extracts from three control sheep. A comparison of these results with a similar study of 22 cases of bovine spongiform encephalopathy (BSE) suggests that in cases of scrapie the area of the brain chosen for the detection of fibrils is less critical than in cases of BSE, in which fibrils are more readily extracted from areas of the brain stem.

South American blastomycosis: ophthalmic and oculomotor nerve lesions

A case of South American blastomycosis began with an oropharyngeal lesion which was followed by a granulomatous uveitis. The patient was treated with Amphotericin B and showed a clinical regression. Four months later, he developed a right 3rd cranial nerve palsy, aggravating the clinical aspect with a severe generalized involvement of the central nervous system and death. Necropsy showed blastomycotic meningoencephalitis.

Incubation periods and histopathological changes in mice injected stereotaxically in different brain areas with the 87V scrapie strain

After stereotaxic injection into five different brain areas (cortex, caudate nucleus, substantia nigra, thalamus and cerebellum) of IM mice with the 87V scrapie strain, the cerebellum had the shortest incubation period. The vacuolation pattern was similar regardless of the area injected with extensive vacuolation in the thalamus, mesencephalon and hypothalamus. The pattern of amyloid plaques differed markedly depending on the area injected. In particular, no plaques were seen anywhere in the brain after injection into intact cerebellum, whereas injection into the four cerebral areas yielded plaques in the forebrain but not in the cerebellum. The incubation period after injection into bisected cerebella was much longer than after injection into intact cerebella. Mice injected on one side of bisected cerebellum had amyloid plaques in the forebrain but not in the cerebellum. There is a discussion of the finding that, although no plaques and virtually no vacuolation were seen in the cerebellum, the shortest incubation period occurred after injection into intact cerebellum.

Ultrastructural and biochemical findings in brain cell cultures infected with canine distemper virus

To study the pathomechanism of demyelination in canine distemper (CD), dog brain cell cultures were infected with virulent A75/17-CD virus (CDV) and examined ultrastructurally. Special attention was paid to the oligodendrocytes, which were specifically immunolabelled. In addition, cerebroside sulfotransferase (CST), an enzyme specific for oligodendrocyte activity was assayed during the course of the infection. Infection and maturation as well as CDV-induced changes were found in astrocytes and brain macrophages. Infection of oligodendrocytes was rarely seen, although CST activity of the culture markedly decreased and vacuolar degeneration of these cells occurred, resulting in their complete disappearance. We concluded that the degeneration of oligodendrocytes and demyelination is not due to direct virus-oligodendrocyte interaction, but due to CDV-induced events in other glial cells.

Pathogenesis and pathology of scrapie after stereotactic injection of strain 22L in intact and bisected cerebella

The mechanisms involved in the spread of scrapie within the brain remain unclear. To examine this issue the 22L scrapie strain was injected in one side of the cerebellum of mice in which the cerebellum had been bisected prior to injection. Another group of animals received the same injection into intact cerebella, i.e. without prior bisection. We found that bisection of the cerebella delayed the spread of scrapie agent from the injection site to the contralateral side of the cerebellum and that the occurrence of vacuolization was not as extensive and was markedly delayed in the uninjected side compared to its occurrence after injection in the intact cerebellum. Replication of agent in an area preceded the development of vacuolization in that area by several weeks. There was marked loss of Purkinje cells on the injected side of bisected cerebella, with no loss seen on the uninjected side. The incubation period of scrapie disease in mice injected after cerebellar bisection was significantly longer than after the injection of intact cerebella. The results in this study suggest that the scrapie agent spreads along intact nerve cell tracts, probably by axonal transport.

In ovo infection with the avian retrovirus RAV-1 leads to persistent infection of the central nervous system

The ability of an avian retrovirus to cause central nervous system (CNS) disease was investigated in chickens infected in ovo with Rous associated virus-1. Viral envelope and core proteins and mature virions were found throughout CNS parenchyma, with the highest amounts localized in the granular layer of the cerebellum, in blood vessel endothelium, and the choroid plexus. This distribution was established by the time of hatching and persisted throughout the 14 weeks of observation. The highest levels of integrated proviral DNA and viral mRNA, were present in the cerebellum, consistent with the distribution of viral antigens. Mononuclear cell infiltrates were evident throughout the CNS, consistent with an inflammatory process. However, demyelination or vacuolar changes, as observed in other retroviral-induced CNS diseases, were not detected. Clinical symptoms of progressive neurologic dysfunction, i.e., weakness or paralysis of the hindlimbs, imbalance, and ataxia, were present in 7 of 38 infected chickens before termination of the experiment at 14 weeks posthatch. Viral antigens or lymphocyte infiltration were not detected in peripheral nerves. These findings suggest that the avian system may provide a valuable model to analyze the mechanisms governing retroviral induced CNS disease.

Differences in virulence between two strains of Streptococcus suis type II after experimentally induced infection of newborn germ-free pigs

Fifteen newborn germ-free pigs were inoculated with 2 strains, D-282 and T-15, of Streptococcus suis type II. Some pigs also were preinoculated with Bordetella bronchiseptica, which successfully predisposed them to S suis infection. The 2 streptococcal strains were differentiated by muramidase treatment, which released certain high molecular-weight proteins, termed muramidase-released proteins (MRP), from the cell wall of strain D-282, but not from the cell wall of strain T-15. Only strain D-282 (MRP-positive) induced clinical signs of disease and markedly increased neutrophil numbers in pigs. Streptococci were more frequently isolated from fecal swab specimens obtained from pigs inoculated with strain D-282 (MRP-positive) than from specimens obtained from pigs inoculated with strain T-15 (MRP-negative). Both strains were isolated from nasal swab specimens obtained from all infected pigs. Postmortem examination revealed fibrinopurulent meningitis, polyserositis, and polyarthritis in pigs inoculated with strain D-282; this strain was isolated from the CNS, serosae, visceral organs, heart, and joints. Whereas strains D-282 caused several pathologic changes, strain T-15, isolated from the lungs, caused only pneumonia. Both strains were isolated from the tonsils of all pigs. Virulence differed distinctly between the MRP-positive and the MRP-negative strains.

Viral antigen distribution in the central nervous system of cattle persistently infected with bovine viral diarrhea virus

Distribution of viral antigens in the central nervous system of 25 cattle with a persistent bovine viral diarrhea virus (BVDV) infection was studied. Using a polyclonal antiserum produced in pigs and the direct immunofluorescence and immunoperoxidase technique, BVDV antigen was located exclusively in neurons. Predilection sites for viral persistence were cerebral cortex and hippocampus; in other areas of brain and spinal cord, viral antigens were in single neurons or small groups of neurons. There was no morphological evidence of cellular alteration due to viral persistence. Perivascular lymphocytic infiltrations were in affected nervous tissue. It is concluded that the central nervous system is an important location for persistence of BVDV.

Contrasting patterns of virus spread and neuropathology following microinjection of herpes simplex virus into the hippocampus or cerebellum of mice

Two strains of herpes simplex virus type 1 (HSV) were microinjected into either the hippocampus or cerebellum of two different mouse strains. Immunoperoxidase staining revealed rapid and extensive spread of virus within the hippocampus and certain of its afferent connections. In contrast, only scattered peroxidase positive cells were observed following cerebellar inoculation. Extensive lesions were observed only in animals surviving intrahippocampal inoculations. These results suggest that localization of the pathological process in HSV encephalitis is due in part to a selective vulnerability of telencephalic or limbic structures.

Ultrastructural changes associated with retroviral replication in central nervous system capillary endothelial cells

Widespread ultrastructural alterations in the vascular basal lamina were found in the central nervous system of symptomatic mice infected with three different neuropathogenic murine leukemia viruses. These changes appeared to progress in frequency and severity in parallel with the progression of spongiform lesions and clinical symptoms. Accumulations of pleomorphic, apparently degenerating, virions were frequently seen within areas that showed marked aberrations from the normal basal lamina ultrastructure. We suggest that the observed retrovirus-associated ultrastructural changes in the endothelial basal lamina may alter normal physiologic functions and thus play a primary role in the pathogenesis of retrovirus-induced spongiform disease.