Current therapy of multiple sclerosis

The list of medications for both immune modulation and symptomatic relief continues to grow. Ideally, however, drug therapy should be part of a multidisciplinary approach that also includes such elements as patient education and physical therapy.

Cortical MRI findings associated with rapid correction of hyponatremia

The authors describe two patients with clinical manifestations of the osmotic demyelination syndrome (ODS) and unusual MRI findings of gadolinium-enhancing peripheral cortical abnormalities. They propose that these represent extrapontine manifestations of ODS because neither patient had a notable hypoxic-ischemic insult. Recognizing this imaging appearance is important because prognosis in ODS may be less uniformly grim than for hypoxia-ischemia.

Intravascular lymphomatosis: contribution of cerebral MRI findings to diagnosis

Intravascular lymphomatosis (IL) is a rare variant of non-Hodgkin's lymphoma with an unusual predilection for the central nervous system (CNS). Most cases are not diagnosed until postmortem because of variable clinical presentation and nonspecific laboratory findings. Neuroimaging findings vary widely and range from diffuse involvement of the deep white matter to infarct-like lesions. Cerebral magnetic resonance imaging (MRI) may show parenchymal and meningeal gadolinium enhancement. The authors describe brain MRI findings of linear, punctate, and patchy enhancement suggestive of CNS IL in two patients confirmed by brain biopsy/histologic studies. High index of clinical suspicion and careful interpretation of MRI (including gadolinium contrast studies) may contribute to premortem diagnosis and early intervention of this often-missed disease.

Calciphylaxis mimicking dermatomyositis: ischemic myopathy complicating renal failure

BACKGROUND

Among the complications of chronic renal failure is a syndrome of medial calcification of small- to medium-sized arteries associated with ischemic necrosis of the skin and other organ systems, leading to gangrene and a poor prognosis. The syndrome has been reviewed in the renal, dermatologic, and surgical literature under the term calciphylaxis, which describes a postulated pathogenetic mechanism whereby sensitization to an endogenous or exogenous substance (such as parathyroid hormone) predisposes to calcium deposition after exposure to a challenging agent. Myopathy has rarely been reported as the presenting feature, and the syndrome has not been discussed in the neurologic literature.

METHODS

We report two patients with renal failure and systemic calciphylaxis who presented to our hospital with myopathic complaints and signs suggesting dermatomyositis. We also discuss possible disease mechanisms and treatment.

CONCLUSIONS

Because early treatment (including aggressively lowering the calcium and phosphate levels and parathyroidectomy) may improve the outcome, early recognition of the syndrome of calciphylaxis is essential.

Dizzy patients: the varieties of vertigo

Some vertigo results from acute viral labyrinthitis or a cerebrovascular event; many cases are due to loose particulate matter within the semicircular canals. In the vast majority of patients, a careful history and appropriate clinical tests will suffice to identify the cause of the vertigo--and with benign paroxysmal positional vertigo, a simple clinical maneuver can also provide a cure.

Approach to the patient with migraine

Women with migraine often experience a worsening of symptoms at menopause. Use of exogenous estrogens is not helpful and may even exacerbate the condition. Although initial pharmacologic management generally is focused on control of individual headaches, attempts to stabilize the underlying migraine mechanism through serotonin receptor downregulation are likely to provide a better outcome.

Correlation between detection of herpes simplex virus in oral secretions by PCR and susceptibility to experimental UV radiation-induced herpes labialis

We examined the oral secretions of 25 patients for herpes simplex virus (HSV) at the time of and following experimental UV radiation (UVR). HSV was detected in one or more oral secretion specimens in 5 of 12 (42%) cases by cell culture and in 8 of 12 (67%) cases by PCR. On the day of UVR, HSV was detected in 1 of 12 (8%) patients who developed a lip lesion and 2 of 16 (13%) patients who did not (the difference is not significant). We conclude that PCR is more sensitive than culture in the detection of HSV and that HSV is not shed with increased frequency from the oral cavity before the development of UVR-induced herpes labialis.

Herpes simplex virus genomes in human nervous system tissue analyzed by polymerase chain reaction

Herpes simplex virus (HSV) is known to establish latency in human trigeminal ganglia. It has been speculated that the virus might also be present in latent fashion in normal human brain, where it might be responsible for conditions such as herpes simplex encephalitis, and less plausibly as a cause for multiple sclerosis or Alzheimer's disease. To test the possibility that HSV exists in normal human brain, we utilized the polymerase chain reaction to assess the frequency and distribution of HSV genomes in the nervous system tissues of patients dying of nonneurological causes. Nine samples were obtained in a systematic fashion from olfactory bulb, gyrus rectus, hippocampus amygdala, calcarine cortex, pons, medulla, cerebellum, and trigeminal ganglia from each of 40 individuals dying of nonneurological disease. HSV genomes were sought in each sample using primers from four regions of the HSV genome. The primers were capable of detecting HSV genomic sequences from as little as 10 fg of DNA. HSV genomic sequences were identified in 26 (65%) of 40 samples of trigeminal ganglia. From 30 patients seropositive to HSV, sequences were amplified from 23 (77%). HSV genomic sequences could be amplified and detected in 14 (35%) of 40 brains. The positive areas included medulla, olfactory bulbs, pons, gyrus rectus, amygdala, and hippocampus. The study has confirmed the previous demonstration of latent HSV in trigeminal ganglia in normal humans. The frequency of latent HSV in trigeminal ganglia is in general agreement with results obtained by explanation of ganglia.(ABSTRACT TRUNCATED AT 250 WORDS)

Symptomatic hyponatraemia: can myelinolysis be prevented by treatment?

The treatment of hyponatraemia is controversial because of the risk of causing central or extrapontine myelinolysis (EPM). Rapid correction with hypertonic saline to a low normal sodium level has its proponents; others feel that slow correction to below normal sodium values is preventative. Most investigators feel that overcorrection should be avoided. It is not known whether the magnitude of serum sodium change is more important than the actual rate of correction. We present three patients with hyponatraemia ranging from 103 to 105 mmol/l who were corrected slowly with normal saline, corrected quickly with hypertonic saline, or rapidly overcorrected with hypertonic saline. All became comatose and died; all had EPM with or without central pontine myelinolysis (CPM). The rate of correction, the solution used, or the magnitude of correction did not seem to protect against demyelination. In a review of 67 reported CPM cases since 1983, no patients documented as having CPM or EPM by radiological studies or necropsy were treated with water restriction only. A group of 27 hyponatraemic patients treated only with water restriction and 35 with diuretic cessation alone did not develop CPM or EPM. This may be a reasonable approach to patients with symptomatic hyponatraemia and normal renal function.

Cerebrovascular syndromes following cardiac transplantation

Between 1985 and 1990, there were 275 orthotopic cardiac transplantations performed on 263 patients. To determine the frequency and define the clinical spectrum of cerebrovascular disease among these patients, we followed them over an average period of 18.5 months (range, 1 to 59 months). Cerebrovascular disorders developed in 24 of 263 patients. We established and classified stroke etiology directly related to transplant procedures or therapies in 13 cases. Nine of 11 cases not directly attributable to transplantation had presumed thromboembolic ischemic events. While stroke most commonly results from conditions unique to heart transplant patients, some disorders may develop from vascular conditions that antedate transplantation.

The numb chin in metastatic cancer

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Aseptic meningitis following cardiac transplantation: clinical characteristics and relationship to immunosuppressive regimen

Neurologic disorders are uncommon but alarming complications of cardiac transplantation. Of 29 patients from the Utah Cardiac Transplant Program (UCTP) who had lumbar puncture because of change in neurologic function, or to assess fever of uncertain etiology, CSF pleocytosis was present in 14 patients, 4 of whom had an active infectious process involving the nervous system. In 10 other patients, CSF pleocytosis with negative cultures appeared following treatment with OKT3 monoclonal antibody. The most prominent clinical signs of this aseptic meningitis syndrome are fever and transient cognitive dysfunction.

Porphyrin-laser photodynamic induction of focal brain necrosis

A noninvasive photodynamic method has been developed to produce focal brain necrosis using porphyrin activated in vivo with laser light. After peripheral injection of the photosensitive porphyrin derivative, Photofrin I, mice were irradiated on the posterior lateral aspect of the head through the intact depilated scalp with 632 nm argon-dye laser light. Animals were studied at one, two and seven days after irradiation. Blood-brain barrier damage was detected by the intravenous injection of Evans blue, horseradish peroxidase and heterologous immunoglobulins. At one and two days after irradiation, the lesions were characterized by extravasation of immunoglobulin and Evans blue, and by edema, ischemia and infiltration by monocytes. On the seventh day after irradiation, the lesion was smaller than it had been two days after irradiation, and had reactive changes at its edges and coagulative necrosis at its center. Extravasation of Evans blue and immunoglobulin was markedly reduced by the seventh day after irradiation, but uptake of horseradish peroxidase by macrophages located at the periphery of the lesion was evident.

Amaurosis fugax associated with antiphospholipid antibodies

In more than 50% of amaurosis fugax patients under 45 years of age no cause for the episodes of visual loss is identifiable. We have encountered 6 young adults (4 women and 2 men) with episodes of amaurosis fugax associated with elevated levels of antiphospholipid antibodies. Splinter hemorrhages of the nail beds were present in most patients. Treatment with antiplatelet medications and anticoagulants appeared to reduce the frequency of episodes and might prevent central retinal artery occlusions or stroke.

Scrapie infection diminishes spines and increases varicosities of dendrites in hamsters: a quantitative Golgi analysis

An altered morphology of neuronal dendrites has been shown to be associated with many degenerative diseases of the central nervous system (CNS). Scrapie is a CNS degenerative disorder caused by a novel infectious particle or prion. Golgi impregnation studies showed that neurons in the scrapie-infected brains of hamsters contained varicose swellings and diminished numbers of dendritic spines. In order to ascertain whether or not these differences were statistically significant, quantitative methods were applied to brain samples from scrapie-infected hamsters and compared to uninfected controls. Golgi impregnated layer III pyramidal neurons from both motor and visual cortex exhibited two types of changes in infected animals. First, loss of dendritic spines on the apical shaft of both motor and visual neurons were found from 50 to 200 microns from the cell body (p less than 0.001). Second, spherical varicosities on dendritic stalks ranging from 7 to 25 microns in diameter were found. The average number of varicosities per cell was 18.1 in infected animals with varicosities on dendrites of controls numbering less than 3 per cell. Less than 2% of the control cells exhibited these varicosities, while greater than 80% of the scrapie dendrites exhibited varicosities. These changes in scrapie are similar to those reported in Creutzfeldt-Jakob and Alzheimer's disease in human patients.

Nocardial cerebral abscess in the acquired immunodeficiency syndrome

Nocardial cerebral abscess is an unusual neurologic manifestation of the acquired immunodeficiency syndrome. A 20-year-old woman with the acquired immunodeficiency syndrome presented with headache and fever. Nocardia asteroides was cultured from a stereotaxic brain biopsy specimen. Despite antibiotic therapy to which the pathogen was sensitive, resolution of the abscess followed only after complete surgical excision.

Effect of antiviral agents on replication of herpes simplex virus type 1 in brain cultures

An in vitro tissue culture system consisting of reaggregated embryonic brain cells was used to evaluate the inhibition of herpes simplex type 1 (HSV-1) by several antiviral compounds. The efficacy of acyclovir, vidarabine, bromovinyldeoxyuridine, and 9-(1,3-dihydroxy-2-propoxymethyl) guanine in HSV-1-infected Vero cell monolayer cultures was compared with that seen with brain cell aggregates. At a mean 50% inhibitory dose with Vero cells, acyclovir showed a 99% reduction of virus titer in brain cell aggregates. Vidarabine and 9-(1,3-dihydroxy-2-propoxymethyl) guanine gave a dose-dependent reduction in virus titer with Vero cells; however, in aggregate cultures treated with the same drugs a dose-dependent decrease at 24 h was followed by an increase to a point of no inhibition at 72 h postinfection. Pretreatment of brain cell aggregates with a hybrid human leukocyte interferon (Le IF-AD) reduced virus titers at 48 h postinfection but did not maintain this reduction at 72 h. In contrast, infected Vero cell monolayer cultures demonstrated a dose-dependent reduction in virus titers with Le IF-AD. Postinfection treatment with Le IF-AD did not reduce plaque formation in Vero cells but was effective in reducing virus titer in HSV-1-infected brain cell aggregates at 48 h postinfection. Antiviral concentrations of up to 200 micrograms or 200,000 IU/ml for interferon did not appear morphologically toxic to brain cells. Antiviral therapy of HSV-1-infected brain cell aggregates may more closely mimic in vivo responses than monolayer cultures.

Replication of scrapie prions in hamster eyes precedes retinal degeneration

Progressive degeneration of outer retinal structures occurs in hamsters with scrapie. In order to determine the relationship between histopathologic changes and replication of the scrapie agent, hamsters were inoculated intracerebrally with approximately 10(7) ID50 units. Animals sacrificed at 50 days after inoculation showed no signs of neurologic dysfunction, but had high titers of the scrapie agent or prions in both neural and nonneural portions of the eye. Prion titers in retina were greater than 10(7) ID50 units/ml of 10% (w/v) homogenate and equal to those found in optic nerve and brain. No histopathologic changes were seen by light microscopy in any ocular structure. At 70 days after inoculation, neurologic dysfunction was profound. The titers of the scrapie agent in brain, lens, retinal pigment epithelium, cornea, retina, and optic nerve were not significantly changed compared to those found at 50 days; however, retinal degeneration was severe. No morphologic changes were observed in cornea, pigment epithelium or optic nerve. These findings show that scrapie prion replication to maximal levels precedes the onset of degenerative changes in retina. Furthermore, the retina is preferentially susceptible to the degeneration induced by the scrapie agent while the other ocular structures containing significant levels of prions seem to escape injury.

Use of aggregating brain cultures to study the replication of herpes simplex virus types 1 and 2 in central nervous system tissue

A novel tissue culture system consisting of reaggregated embryonic mouse brain cells was used to examine the replication of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) within central nervous system tissue. Brain aggregates cultured 30-40 days in vitro demonstrated progressive maturation and differentiation into cells recognizable as neurons, astrocytes and oligodendrocytes, with the latter cell type exhibiting myelin production. Mature aggregates were infected with HSV and sampled at timed intervals postinfection for morphological, virological, and biochemical assays. By electron microscopy mature nucleocapsids were observed in the nucleus of peripheral cells at 9 h and in all cell types by 33 h. Virus-specific antigens were observed, using the immunoperoxidase test, within peripheral cells at 12 h postinfection (p.i.). By 24 h p.i., antigen production had progressed throughout the infected aggregates. Growth curves of HSV-1 and HSV-2 for intracellular and extracellular infectious virus production correlated well with virus-induced morphological changes and antigen production. SDS-polyacrylamide slab gel electrophoresis of isotopically-labelled proteins and glycoproteins synthesized from 4 to 24 h p.i. in virus-infected aggregates revealed typical HSV-1 polypeptide profiles and HSV-1 and HSV-2 glycoprotein profiles. Our results suggest that aggregating brain cultures may provide a useful and more accurate in vitro model for the study of HSV-induced neurological disease.

Retinal degeneration in experimental Creutzfeldt-Jakob disease

Mice with experimental Creutzfeldt-Jakob disease (CJD) develop a progressive retinal degeneration after a prolonged incubation period. Sections of the eyes stained with hematoxylin and eosin revealed pathologic changes in the optic nerve and a marked degeneration of photoreceptor cell inner and outer segment areas. Both peripheral and central retina, normally 10 cells thick, were reduced to one photoreceptor cell or less in thickness. Ultrastructural analysis revealed total loss of outer segment and most inner segment elements. Only Müller cell microvilli and macrophages remained in the subretinal space. Macrophages were also visible in the remnant photoreceptor cell layer. The inner nuclear layer and pigment epithelial cell layers appeared normal. Müller cell hypertrophy was evident but was not accompanied by spongiform vacuolation. Several of the degenerative changes of the eye in mice with experimental Creutzfeldt-Jakob disease differ from those observed for scrapie in rodents. The pathologic similarities between the retinal degenerations occurring in mice with experimental Creutzfeldt-Jakob disease and those found in some forms of human retinal degeneration are provocative. These similarities raise the question whether or not other retinal degenerative diseases might be caused by infectious agents such as prions or slow viruses.

Replication of the scrapie agent in hamster brain precedes neuronal vacuolation

The scrapie agent causes a degenerative neurological disorder in sheep and goats after a prolonged incubation period. Hamsters inoculated intracerebrally with 10(7) ID50 units of the scrapie agent develop clinical signs of neurological dysfunction 60-65 days later. The titers of scrapie agent in selected regions of the central nervous system (CNS) of hamsters were determined prior to the onset of clinical illness. At 48 days after inoculation, the cerebrum, cerebellum, brain stem, and spinal cord contained 9.3, 9.1, 9.3, and 8.6 log ID50 units/g of tissue, respectively. Sections from the cerebrum showed minimal vacuolation without any astrogliosis. The spinal cord and cerebellum revealed no lesions. At 71 days after inoculation, when clinical signs of scrapie were prominent, another group of hamsters was evaluated. The mean titers of the agent in the same CNS regions were virtually unchanged, but severe vacuolation and moderate astrogliosis were present in the cerebral cortex. A moderate degree of vacuolation and astrogliosis were observed in the cerebellum, brain stem, and spinal cord. These studies indicate that replication of the scrapie agent in the hamster is uniform throughout the CNS and precedes the development of pathological changes.

Impaired migratory and chemotactic activity of neutrophils during murine cytomegalovirus infection

Mice have been shown to have increased susceptibility to bacterial and fungal superinfections between days 1 and 5 of acute murine cytomegalovirus (MCMV) infection. The current study demonstrated that, during the same period of the MCMV infection, migration of neutrophils into a subcutaneous sponge was impaired (1,300-2,000 cells/mm3 in MCMV-infected animals vs 6,000-7,000 cells in controls; P less than 0.01) and chemotaxis of neutrophils harvested from the sponge was decreased (chemotactic index of 1.5-2.1 in infected animals vs 5.4-5.7 in controls; P less than 0.01). The number of neutrophils in peripheral blood was not altered. Infectious MCMV was present in the neutrophil-rich fraction of peripheral white blood cells, suggesting that direct viral infection of neutrophils may contribute to altered function. These studies suggest that abnormalities in neutrophil function during acute cytomegalovirus infection may contribute to the enhanced susceptibility to bacterial and fungal infections that occurs in both experimental animals and humans.

Comparative neurovirulence of herpes simplex virus type 1 strains after peripheral or intracerebral inoculation of BALB/c mice

Twenty-three strains of herpes simplex virus type 1 were compared for their pathogenicity in 4-week-old BALB/c mice after peripheral (footpad) or intracerebral inoculation. Among those strains examined were (i) six clinical isolates of brain or cerebrospinal fluid origin, (ii) seven clinical isolates of oral or genital origin, (iii) five prototype laboratory strains that have been passaged numerous times in culture, and (iv) five syncytial variants capable of producing cell fusion in culture. Based on comparative 50% lethal dose values, the strains appeared to segregate into one of three classes of neurovirulence. Class I strains were highly virulent by both the peripheral and intracerebral routes of inoculation, class II strains were highly virulent by the intracerebral route only, and class III strains were highly attenuated by both routes of inoculation. In vivo growth curves for whole brain homogenates infected with class III strains revealed titers of infectious virus approaching those found in the brains of animals infected with class I or II strains. These results would therefore suggest that (i) a strain-dependent variation in neural spread exists that may influence the ability of the virus to cause acute neurological disease and (ii) the amount of infectious virus present within an infected brain does not necessarily determine or reflect the clinical status of the animal. Of the clinical isolates examined, the strains recovered from brain tissue of humans after fatal episodes of encephalitis were found to be no more neurovirulent in mice than the strains isolated from nonneural sites. However, although syncytial variants were found to be highly attenuated by the peripheral route, as a group these strains proved to be among the most virulent when inoculated directly into the central nervous system.

Recurrent herpes simplex encephalitis: recovery of virus after Ara-A treatment

A 54-year-old man developed clinical findings consistent with herpes simplex virus (HSV) encephalitis. These signs included an abrupt onset of focal central nervous system disease, cerebrospinal fluid pleocytosis, localized electroencephalographic abnormalities, and a computerized tomographic scan showing right temporal lobe involvement. Treatment with adenine arabinoside (Ara-A) resulted in improvement. Two months later he again became confused, and a left hemiparesis developed. Although biopsy revealed extensive necrosis and inflammatory response, HSV antigens and herpesvirus particles were not detected. Culture of biopsy tissue yielded HSV type 1 only after 18 days. A second course of Ara-A was administered but the patient failed to improve and died four months later. Extensive inflammatory necrosis of both temporal lobes involving gray and white matter was found. Cultures were negative for HSV. The recovery of virus from our patient during the second encephalitic episode should raise concerns regarding the efficacy of Ara-A treatment and the role of the virus in recurrent disease. In addition, the importance of maintaining biopsy tissue in culture for prolonged periods is emphasized.

Herpetic proctitis and meningitis: recovery of two strains of herpes simplex virus type 1 from cerebrospinal fluid

A patient with simultaneous proctitis and meningitis due to herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) was extensively investigated. In both disease locations the infection was clinically evident and culture-proven. Analysis by sodium dodecylsulfate-polyacrylamide gel electrophoresis of rectal isolates revealed both HSV-1 and HSV-2. The cerebrospinal fluid harbored two apparently different strains of HSV-1, one of which was shown by restriction endonuclease analysis to be identical with the rectal isolate of HSV-1.

Detection of tissue culture-adapted Theiler's virus RNA in spinal cord white matter cells throughout infection

The appearance of histological lesions and the localization of viral RNA in the central nervous system of mice infected with tissue culture-adapted Theiler's murine encephalomyelitis virus (WW strain) (TMEV-WW) was studied. Viral RNA was detected by autoradiography after in situ hybridization, using a (3)H-labeled DNA probe complementary to virion RNA, which was applied to deparaffinized sections of central nervous system tissues from infected mice. Subjacent histological sections of tissues were used to assess the location and extent of lesions. Lesions were first observed at 20 days post-inoculation and appeared to enlarge throughout infection. They consisted of infiltrates of mononuclear cells and lymphocytes in spinal cord white matter and leptomeninges; at 78 days post-inoculation severe necrotizing and demyelinative myelitis and gliosis were observed. In contrast to the pathogenesis of brain-derived TMEV-WW-infected mice, no lesions were found in the central nervous system gray matter of mice infected with tissue culture-adapted TMEV-WW at any time post-infection. Tissue culture-adapted viral RNA was found in the cells of spinal cord white matter throughout infection; only one neuron in close proximity to the injection site was found to contain viral RNA shortly after infection. At early times after infection, spinal cord white matter cells containing viral RNA were found before development of inflammatory lesions; at later days post-inoculation, positive cells were found within, at the periphery of, or at a distance from lesions. The number of infected cells and the amount of viral RNA per cell appeared to remain constant from 20 to 78 days post-inoculation despite the increasing intensity of the inflammatory response. The nearly exclusive spinal cord white matter tropism of tissue culture-adapted TMEV-WW appeared to directly correlate with the disease-inducing potential of this virus.

Immunochemical features of a case of progressive rubella panencephalitis

Progressive rubella panencephalitis (PRP), a slowly progressive and fatal central nervous system (CNS) disorder due to rubella virus, is characterized by high cerebrospinal fluid (CSF) levels of immunoglobulins, oligoclonal bands and high CSF:serum rubella antibody titre ratios. Sera, CSF and neutral extracts of brain, spleen, lymph node and kidney obtained at autopsy from a case were analysed for immunoglobulin isotype and content by enzyme linked immunosorbent assays. Comparable titres of rubella specific IgA and IgG were found in sera and CSF, but accounted for a disproportionate amount of the isotype specific immunoglobulins of CSF (0.19%, 14.0%) as compared to serum (0.02%, 0.69%). The percentage of isotype specific immunoglobulins were not increased in extracts of most visceral tissues compared to serum, however, rubella specific IgA and IgG were disproportionately increased in extracts from most regions of brain sampled (1-60-fold and 8-27-fold respectively). No rubella specific IgM could be conclusively demonstrated in any specimen. Immunoprecipitation studies showed that the IgG reacted with the major glycoproteins (gp62, gp47-56 complex) and non-glycosylated polypeptide (p38) of radiolabelled rubella virions and infected cell lysates. These studies support the conclusion that a major portion of the rubella specific antibody is produced within the CNS of patients with PRP.

Detection of Theiler's virus RNA in mouse central nervous system by in situ hybridization

The location and distribution of viral RNA were examined in the central nervous system tissues of weanling mice acutely infected with the GDVII strain of Theiler's murine encephalomyelitis virus. Viral RNA was detected by autoradiography following in situ hybridization of a 3H-labeled DNA synthesized in vitro complementary to purified viral RNA. Viral RNA was detected in pyramidal neurons of the hippocampus, cerebral cortex, brainstem nuclei, thalamus, basal ganglia, and spinal cord. Autoradiographic grains could be detected in the axonal and dendritic processes of many infected neurons. No viral RNA was detected in any cell of the cerebellum or white matter. In addition to demonstrating the location of viral RNA in infected central nervous system tissues, and hence the sites of viral replication during this acute polioencephalomyelitis, they indicate that necrosis of hippocampal neurons is due to lytic infection, rather than to hypoxia.

Theiler's virus persists in glial cells during demyelinating disease

Theiler's murine encephalomyelitis virus (T-MuEV) is the agent of a persistent, demyelinating infection of the central nervous system of mice, T-MuEV RNA was detected in histological sections of brain and spinal cord of experimentally infected animals by in situ hybridization. Both neurons and glial cells contained viral RNA during the early acute phase of the disease, The amount of viral RNA in neurons, however, was considerably higher than in glial cells. During the late demyelinating phase of the disease, viral RNA was found in low amounts only in glial cells of the white matter of spinal cord. At that stage, no viral RNA was found in neurons. These results demonstrate that T-MuEV persists in glial cells of the white matter. A reconstruction of the pathogenesis of this persistent infection is proposed, based on the different levels of virus replication in neurons and glial cells.

Use of monoclonal antibody directed against herpes simplex virus glycoproteins to protect mice against acute virus-induced neurological disease

Monoclonal antibodies HCl and HD1, directed against herpes simplex virus type 1 (HSV-1) glycoproteins gC and gD, respectively, were evaluated for their ability to passively immunize mice against acute virus-induced neurological disease after footpad inoculation with HSV-1 or herpes simplex virus type 2 (HSV-2). Control virus-infected mice receiving a single intraperitoneal injection of normal serum died within 7 to 10 days after the spread of virus from footpad to spinal cord and brain. However, a single intraperitoneal injection of either HCl or HD1 antibody protected mice from neurological illness and death when administered to HSV-1 (strain HTZ)-infected mice at either 2 h before virus challenge or at 24 h after virus inoculation. To determine the in vivo specificity of the antibodies, passive transfer studies were performed with mice infected with the MP strain of HSV-1, a mutant of HSV-1 (mP) which is defective in the production of glycoprotein gC. Whereas HD1 antibody decreased the incidence of neurological illness in MP- and mP-infected mice, HCl antibody, which protected mP-infected animals, failed to protect mice infected with the MP strain. When HD1 antibody was administered to HSV-2 (strain G)-infected mice at either 2 h before virus challenge or at 6 h (but not 24 h) after virus inoculation, 100% of the infected animals receiving HD1 antibody survived. In contrast, 100% of HSV-2 (strain G)-infected animals passively immunized with HCl antibody developed neurological illness and died. These results provide in vivo evidence that the HSV-induced glycoprotein gC expresses type-specific antigenic determinants, whereas glycoprotein gD expresses type-common determinants.

Scrapie-associated particles in postsynaptic processes. Further ultrastructural studies

Both tubular and spherical densities have been described in postsynaptic processes of mice with clinical scrapie. To determine whether the tubular appearances resulted from tubular structures or from overlap of spherical particles, electron microscopic examination was performed by tilting the specimen through large angles. In every instance where such could be analyzed, the tubular appearances resulted from overlapping of tightly aggregated spherical particles.

Biochemistry of Theiler's murine encephalomyelitis virus isolated from acutely infected mouse brain: identification of a previously unreported polypeptide

The WW strain of Theiler's murine encephalomyelitis virus (WW-TMEV) was purified from homogenates of acutely infected mouse brain. Infectious WW-TMEV was found to have an estimated sedimentation coefficient of 156 (s20,w) and a density of 1.35 g/cm3 in CsCl. Electron microscopy revealed a homogeneous population of 26-nm nonenveloped particles. Iodination of sodium dodecyl sulfate (SDS)-disrupted virions revealed four major capsid proteins with molecular weights of 58,000, 37,000, 34,000, and 27,000. A 6,000-dalton polypeptide was observed after long exposures of autoradiograms. The 37,000-, 24,000-, 27,000-, and 6,000-dalton polypeptides corresponded to picornaviral VP1, VP2, VP3, and VP4 capsid polypeptides, respectively. Comparison of autoradiograms of virions radiolabeled before and after SDS disruption indicated that the 58,000-dalton protein, VP2, and VP3 preferentially bound 125I under the labeling conditions used. Direct evidence was obtained that VP2 and VP3 were derived from the 58,000-dalton polypeptide by isolation of the 58,000-dalton polypeptide from polyacrylamide gels run under nonreducing conditions and subjecting it to reelectrophoresis under reducing conditions. The effect of trypsin on purified virions and their polypeptides was also investigated. Trypsin-sensitive sites were found in the 58,000-dalton protein, VP1, and VP2. Our results indicate that, in addition to the four typical picornaviral capsid polypeptides, there is a 58,000-dalton polypeptide present in WW-TMEV, which is sensitive to trypsin and can be reduced into two of the capsid proteins, VP2 and VP3.

Progressive retinal degeneration in scrapie-infected hamsters: a light and electron microscopic analysis

Scrapie is considered a prototype of the spongiform encephalopathies. This group of diseases is characterized by a prolonged incubation period, without symptoms, followed by an insidious onset of clinical disease leading to death. Attention has mainly been focused on central nervous system pathology, and reports of pathology in the retina have been limited. In this study, hamsters were inoculated intracerebrally with the scrapie agent and serially sacrificed to determine agent titers and pathologic changes in the eyes over time. Scrapie infectivity rises progressively in the eye to maximal levels between 6 and 8 weeks after inoculation, then it reaches a plateau. Ocular abnormalities are first visible 8 weeks after infection. The process begins with a gradual loss of rod outer segments, after which progressive loss of rod inner segments and photoreceptor nuclei occurs. By 10 weeks, only a vestige of the outer nuclear layer remains. Ultrastructurally, this destruction is attended by the presence of macrophages, although the importance of this finding is unknown. Later, Müller cells increase their pericellular investment of remaining photoreceptor cell nuclei. The limitation of the lesion to the outer retinal layers suggests this tissue site may be important in the investigation of basic pathogenetic mechanisms in the spongiform encephalopathies.

Type-common and type-specific monoclonal antibody to herpes simplex virus type 1

Hybridoma cells produced by fusing mouse myeloma cells with spleen cells from mice primed with herpes simplex virus (HSV) type 1 yielded five clones producing neutralizing antibody against homologous virus. Two clones, HCl and HC2, produced antibody capable of precipitating glycoprotein C and its precursor, whereas three clones, HD1, HD2, and HD3, produced antibody capable of precipitating glycoprotein D and its precursor. Antibody produced by the HC1 and HC2 clones neutralized HSV type 1 but not HSV type 2 or HSV type 1 strain MP, which is known to lack glycoprotein C. Antibody produced by the HD1 and HD2 clones neutralized both HSV type 1 and HSV type 2, whereas antibody produced by the HD3 clone neutralized HSV type 1 but not HSV type 2. The two clones which produced antibody to glycoprotein C and the two clones which produced type-common antibody to glycoprotein D were independently derived and not clonally related inasmuch as the antibody in each pair belonged to a different subclass of immunoglobulin.

Delayed stroke following carotid occlusion

A 60-year-old patient suffered a lethal hemispheric infarction 3 days after angiographically documented occlusion of the ipsilateral cervical internal carotid artery and while receiving anticoagulant therapy. Pathologic evidence is consistent with embolism from the distal "tail" of a propagated carotid thrombus as the mechanism of his stroke.

Progressive myelopathy due to extramedullary hematopoiesis: case report and review of the literature

Extramedullary hematopoiesis (EMH) in the spinal epidural space is a rare but treatable cause of progressive paraparesis in patients with a variety of hematological and systemic disorders. We report a case of extensive thoracic epidural EMH causing progressive spastic paraparesis in a patient with agnogenic myeloid metaplasia. The literature describes 11 additional cases of myelopathy due to epidural EMH. All patients had EMH in the midthoracic region with elevated cerebrospinal fluid protein and abnormal spine roentgenograms or myelograms. Treatment with decompressive laminectomy, radiation therapy, or both, resulted in marked or complete recovery in 7 of 10 patients. Patients who develop paraparesis and who have a disorder associated with EMH should be evaluated rapidly for this treatable condition.

Host defenses in herpes simplex infections of the nervous system: effect of antibody on disease and viral spread

BALB/c mice passively immunized with antibody to herpes simplex virus type 1 and challenged in the footpad with 10(5.7) plaque-forming units of herpes simplex virus type 1 were shown to be protected from neurological disease and death compared with control mice treated with normal serum or antibody to Sindbis virus. One hundred percent of untreated mice had virus recoverable from dorsal root ganglia by 48 h after infection. Whereas amputation of the infected limb at 48 h had no effect, antibody administration (resulting in titers of 1:8 and 1:16) was found to prevent acute neurological disease if administered no later than 48 h after infection. Antibody also restricted the extent of latent infection in the lumbosacral ganglia. The data provide strong evidence that antibody is effective in preventing spread of virus both in the peripheral nervous system and in central nervous system (spinal cord) tissue.

Morphology of central nervous system disease in immunosuppressed mice after peripheral herpes simplex virus inoculation. Trigeminal root entry zone

Inoculation of mice and rabbits on the cornea with herpes simplex type 1 virus has been shown to cause an ascending infection of the trigeminal nerve, ganglion, and descending tract within the brainstem (2, 3, 7). A discrete, destructive, and primarily demyelinative lesion is seen on the central nervous system side of the trigeminal root entry zone 5 to 8 days after infection (8, 15, 16). This study, utilizing Swiss mice, demonstrated that immunosuppression with cyclophosphamide prior to infection with herpes simplex type virus causes a marked reduction of the mononuclear infiltrate within the central nervous system and a significant decrease in myelin destruction when compared with the infected, nonimmunosuppressed control animals. The content of virus in the brainstem was similar in both groups by day 8 as were the neutralizing antibody titers to herpes simplex type 1 virus. These results suggest that the cellular response plays a definitive role in the destruction of central nervous system tissue after peripheral infection with herpes simplex type 1 virus.

Partial purification and evidence for multiple molecular forms of the scrapie agent

A procedure for the partial purification of the scrapie agent from mouse spleen was developed based on its sedimentation profile. Differential centrifugation and detergent treatment with sodium deoxycholate yielded a fraction designated "P5" which was enriched for scrapie infectivity approximately 20-fold with respect to cellular protein. The P5 fraction was devoid of cellular membranes but heavily contaminated with ribosomes as judged by electron microscopy. On centrifugation of the fraction P5 to near equilibrium in a sucrose gradient scrapie infectivity was distributed over a range of densities from 1.08 to 1.30 g/cm3. Parallel rate-zonal analysis showed that the infectivity was distributed over a range of particle sizes with s20.w values from approximately 40 S to greater than 500 S. Incubation of P5 at 37 or 80 degrees C, under conditions that disrupt ribosomes, dramatically altered the rate-zonal gradient profile of the agent. Under these conditions, the agent sedimented as particles with s20.w greater than 500 S. The apparent heterogeneity of the scrapie agent with respect to both size and density and its ability to shift from one form to another suggest that the agent may contain hydrophobic domains on its surface.

Experimental scrapie in mice: ultrastructural observations

Scrapie, kuru, and Creutzfeldt-Jakob disease are characterized by a similar spongiform pathology, prolonged incubation periods, and an agent with unique physical, chemical, and biological properties. Swiss mice were inoculated with the scrapie agent and sacrificed three to five months later for light and electron microscopy. At three months, small vacuoles were seen within the neuropil of the cerebral cortex and basal ganglia. By the fifth month these vacuoles had increased in number and size and were accompanied by moderate astrocytic proliferation. The brainstem, cerebellum, and spinal cord showed variable changes of much less intensity. Many dilated postsynaptic processes contained osmiophilic particles in random or crystalline arrays. The particles, measuring approximately 23 nm in diameter, appeared consistently in postsynaptic processes of brain from scrapie-infected mice, were lacking in controls, and were a size consistent with sedimentation and filtration data for the scrapie agent. Whether these particles represent the scrapie agent must await further studies.