Focal demyelinative damage and neighboring white matter integrity: an optic neuritis study

Background:

Neuronal loss following damage is often greater than expected from the severity of injury to the nerve itself. The visual pathways, which comprise a well-defined system, and optic neuritis (ON), which is usually a discrete event, make a fine model to study this phenomenon.

Objective:

Understand the effect of focal optic nerve demyelination on neighboring white matter.

Methods:

Diffusion tensor imaging and probabilistic tractography were used to identify and characterize the optic tracts and radiations of 17 ON and matched controls. Data were correlated with retinal nerve fiber layer (RNFL) thickness.

Results:

Patients’ optic tracts exhibited reduced axial diffusivity, which correlated with RNFL thickness values. Patients’ optic radiations demonstrated intact axial diffusivity but reduced fractional anisotropy and elevated radial diffusivity, which could be explained by intra-bundle lesions. No correlations were found between diffusivity measurements in patients’ optic tracts and radiations; or between RNFL thickness and optic radiations’ diffusivity.

Conclusions:

Following ON, chronic axonal loss develops distally in the optic tracts, demonstrating Wallerian degeneration. Degeneration did not proceed to the optic radiations, opposing anterograde trans-neuronal changes. DTI in ON provides fine in-vivo human model for studying histological abnormalities in normal appearing white matter, localized in close proximity to damaged bundle.

Rehabilitation outcomes of stroke patients treated with multi-modal endovascular reperfusion therapy

AIM

The aim of this study was to investigate the influence of multi-modal endovascular reperfusion therapy (MMRT) on functional outcomes following rehabilitation.

METHODS

Data from 14 MMRT-treated patients were analyzed and compared to MMRT-ineligible, age and stroke severity-matched patients treated at the same Neurological and Rehabilitation departments. Neurological evaluation was assessed with the NIH stroke scale (NIHSS). Activity of daily living was measured using the FIMTM instrument. Functional outcome was measured using the modified Rankin scale (mRS).

RESULTS

The baseline characteristics of both groups were similar. NIHSS scores were lower in the MMRT group and they had slightly better functional and rehabilitation scores on admission to rehabilitation. At the end of rehabilitation, more MMRT-treated patients reached functional independence (mRS≤2; 50% vs. 7% respectively P=0.03). FIM scores were also higher in the MMRT group (mean score 93.3 vs. 87.7, respectively) but the difference did not reach significance. The delta in FIM and NIHSS scores obtained during rehabilitation did not significantly differ between the groups. MMRT remained a significant modifier of good outcome after regression analysis (OR 21.5 95% CI 1.1-410).

CONCLUSION

MMRT-treated patients have better chances of attaining independence after rehabilitation therapy. However, the additional improvements gained while in active rehabilitation were independent of reperfusion status.

Novel pulsatile cerebrospinal fluid model to assess pressure manometry and fluid sampling through spinal needles of different gauge: support for the use of a 22 G spinal needle with a tapered 27 G pencil-point tip

BACKGROUND

Parallel-walled spinal needles ≤ 22 G are routinely used for lumbar puncture, despite a reported ≥ 32% incidence of post-dural puncture headache. A tapered spinal needle (22 G shaft, 27 G tip) is in use in our institution. We hypothesized that despite the smaller dural puncture hole, this needle has similar cerebrospinal fluid (CSF) pressure equilibration times and CSF sampling times to a standard 22 G needle and assessed a range of spinal needles using an experimental pulsatile CSF reservoir.

METHODS

The pulsatile CSF reservoir had an oscillating pressure varying between 25 and 15 cm H(2)O at a cycle frequency of 80 s(-1). We tested seven parallel-walled spinal needles (18-27 G) and the tapered 22/27 G needle. CSF pressure was measured every 2 s by manometry. The time to collect 1 ml CSF samples was measured. Saline 0.9% and mannitol 20% were tested separately. One-way ANOVA with Bonferroni post-hoc test was used to compare 22G, 27G and 22/27G needles.

RESULTS

The mean [standard deviation (sd)] CSF pressure equilibration time (saline) was 40.7 (6.4), 108.7 (6.1), and 51.3 (4.6) s for the 22, 27, and 22/27 G needles (P< 0.0001 for comparisons between 27 G and other needles). The mean (sd) CSF sampling time (saline) was 40.3 (3.1), 225.3 (10.0), and 63.0 (5.2) s for the 22, 27, and 22/27 G needles (P< 0.0001 for comparisons between 27 G and other needles, and P= 0.019 between 22 and 22/27 G needles). Saline was different from mannitol for both measurements and all needles (P< 0.0001).

CONCLUSIONS

A 22/27 G tapered spinal needle has similar flow properties to the 22 G needle, despite a 27 G tip.

Sustained motion perception deficit following optic neuritis: Behavioral and cortical evidence

OBJECTIVE

To assess the recovery process in patients after an acute optic neuritis (ON) attack, comparing static and dynamic visual functions.

METHODS

In this prospective controlled study, 21 patients with unilateral, first-ever ON were followed over the course of 1 year. Standard visual tests, visual evoked potentials, and optical coherence tomography were assessed repeatedly. In addition, we developed a novel set of motion perceptual tasks to test dynamic visual deficits. fMRI examinations were performed to study the neuronal correlates for the behavioral findings.

RESULTS

Four months after the acute phase, the affected eyes had returned to normal performance levels in the routine visual testing. However, motion perception remained impaired throughout the 12-month period. In agreement with the clinical findings, fMRI studies showed recovery in cortical activation during static object recognition, as opposed to sustained deficit in tasks that require motion perception.

CONCLUSIONS

Sustained motion perception deficit following ON may explain the continued visual complaints of patients long after recovery of visual acuity. Cortical activation patterns suggest that if plastic processes in higher visual regions contribute to the recovery of vision, this may be limited to static visual functions. Alternatively, cortical activation may reflect the visual percept (intact for visual acuity and impaired for motion perception), rather than demonstrating plastic processes. We suggest that motion perception should be included in the routine ophthalmologic tests following ON.

Prior use of statins and outcome in patients with intracerebral haemorrhage

BACKGROUND

Pre-treatment with cholesterol lowering drugs of the statin family may exert protective effects in patients with ischaemic stroke and subarachnoid haemorrhage but their effects are not clear in patients with intracerebral haemorrhage (ICH).

METHODS

We recruited patients admitted to our University Hospital with an acute ICH and analysed pre-admission demographic variables, pre-morbid therapy, clinical and radiological prognostic markers and outcome variables including 90-day modified Rankin score and NIH stroke scale score (NIHSS).

RESULTS

We recruited 399 patients with ICH of which 101 (25%) were using statins. Statin users more often had vascular risk factors, had significantly lower haematoma volumes (P = 0.04) and had lower mortality rates compared with non-users (45.6% vs. 56.1%; P = 0.11). However, statin treatment did not have a statistically significant impact on mortality or functional outcome on multiple logistic regression analysis.

CONCLUSIONS

Treatment with statins prior to ICH failed to show a significant impact on outcome in this analysis despite lower haematoma volumes.

Brain interleukin-1 mediates chronic stress-induced depression in mice via adrenocortical activation and hippocampal neurogenesis suppression

Several lines of evidence implicate the pro-inflammatory cytokine interleukin-1 (IL-1) in the etiology and pathophysiology of major depression. To explore the role of IL-1 in chronic stress-induced depression and some of its underlying biological mechanisms, we used the chronic mild stress (CMS) model of depression. Mice subjected to CMS for 5 weeks exhibited depressive-like symptoms, including decreased sucrose preference, reduced social exploration and adrenocortical activation, concomitantly with increased IL-1 beta levels in the hippocampus. In contrast, mice with deletion of the IL-1 receptor type I (IL-1rKO) or mice with transgenic, brain-restricted overexpression of IL-1 receptor antagonist did not display CMS-induced behavioral or neuroendocrine changes. Similarly, whereas in wild-type (WT) mice CMS significantly reduced hippocampal neurogenesis, measured by incorporation of bromodeoxyuridine (BrdU) and by doublecortin immunohistochemistry, no such decrease was observed IL-1rKO mice. The blunting of the adrenocortical activation in IL-1rKO mice may play a causal role in their resistance to depression, because removal of endogenous glucocorticoids by adrenalectomy also abolished the depressive-like effects of CMS, whereas chronic administration of corticosterone for 4 weeks produced depressive symptoms and reduced neurogenesis in both WT and IL-1rKO mice. The effects of CMS on both behavioral depression and neurogenesis could be mimicked by exogenous subcutaneous administration of IL-1 beta via osmotic minipumps for 4 weeks. These findings indicate that elevation in brain IL-1 levels, which characterizes many medical conditions, is both necessary and sufficient for producing the high incidence of depression found in these conditions. Thus, procedures aimed at reducing brain IL-1 levels may have potent antidepressive actions.

Transplantation of neural progenitors enhances production of endogenous cells in the impaired brain

Grafting of neural progenitors has been shown to reverse a wide variety of neurobehavioral defects. While their role of replacing injured cells and restoring damaged circuitries has been shown, it is widely accepted that this cannot be the only mechanism, as therapy can occur even when an insufficient number of transplanted cells are found. We hypothesized that one major mechanism by which transplanted neural progenitors exert their therapeutic effect is by enhancing endogenous cells production. Consequently, in an allographic model of transplantation, prenatally heroin-exposed genetically heterogeneous (HS) mice were made defective in their hippocampal neurobehavioral function by exposing their mothers to heroin (10 mg kg(-1) heroin on gestation days 9-18). Hippocampal damage was confirmed by deficient performance in the Morris maze (P<0.009), and decreased production of endogenous cells in the dentate gyrus by 39% was observed. On postnatal day 35, they received an HS-derived neural progenitors transplant followed by repeated bromodeoxyuridine injections. The transplant returned endogenous cells production to normal levels (P<0.006) and reversed the behavioral defects (P<0.03), despite the fact that only 0.0334% of the transplanted neural progenitors survived and that they differentiated mainly to astrocytes. An immunological study demonstrated the presence of macrophages and T cells as a possible explanation for the paucity of the transplanted cells. This study suggests one mechanism for the therapeutic action of neural progenitors, the enhancement of the production of endogenous cells, pointing to future clinical applications in this direction by use of neural progenitors or by analogous cell-inducing techniques.

Severe influenza infection in a chronic hepatitis C carrier: failure of protective serum HI antibodies after IM vaccination

BACKGROUND

Influenza is an important cause of morbidity and mortality in immunocompromised hosts. Recommendations exists for vaccination each year, yet disease can still occur.

OBJECTIVES

To describe the course of fulminant influenza infection in a patient with HCV.

STUDY DESIGN

Case study in which correlation was made between immunoglobulin response to influenza vaccination to the disease and its unique clinical course caused by influenza virus.

RESULTS

Influenza A/Jerusalem 17/98 (H(1)N(1)) was isolated from the throat of a chronic hepatitis C carrier who, presented with shortness of breath, and subsequent massive bilateral pneumonia. The patient was previously immunized IM with inactive influenza vaccine. He developed protective levels of humoral antibodies (1:80 hemagglutination inhibition (HI) antibodies) against the three strains of the vaccine that evidently did not prevent respiratory infection. The development of massive bilateral pneumonia and continued presence of influenza virus in the respiratory tract may have been due to his underlying medical condition and possible lack of mucosal secretory IgA (SIgA) antibodies.

CONCLUSION

We have presented a case of prolonged influenza infection post vaccination. This case emphasizes the importance of an improved vaccine that would stimulate a better immunologic response, especially in immunocompromised patients.

Virus and host factors that mediate the clinical and behavioral signs of experimental herpetic encephalitis. A short auto-review

Experimental models that mimic the clinical syndrome of human viral encephalitis and represent HSV-1 neurotropism were utilized to investigate neuro-pharmacologic changes mediating clinical and behavioral manifestations of encephalitic infection of the central nervous system with HSV-1-induced rapid activation of the hypothalamic--pituitary--adrenocortical (HPA) axis and production of brain derived interleukin-1 (IL-1) and prostaglandin E2 (PG-E2), independently of viral replication. HSV-1 infection induced clinical signs of fever, motor hyperactivity and aggressive behavior. These manifestations were dependent on a permissive action of circulating glucocorticoids and not related to the degree of viral replication in the brain. Hyperthermia and HPA axis activation were also specifically dependent on HSV-1-induced brain IL-1 and PG-E2. The chronic neurological sequel or fatal outcome of HSV-1 encephalitis may be due to viral replication and brain tissue destruction, which are dependent on virus encoded virulence genes. In contrast, the clinical and behavioral signs in the acute phase are a result of activation of neurochemical systems, including cytokines, prostaglandinds and catecholamines. Circulating glucocorticoids play an essential role in mediating the physiologic actions of HSV-1-induced brain products and the clinical syndrome of encephalitis.

A novel permissive role for glucocorticoids in induction of febrile and behavioral signs of experimental herpes simplex virus encephalitis

Herpes simplex virus type 1 (HSV-1) encephalitis may present with fever and behavioral changes, to the extent of a psychotic state and psychomotor agitation. We developed a clinically relevant experimental model of HSV-1 encephalitis and investigated host brain responses associated with its clinical signs and whether these responses depend on the presence of circulating glucocorticoids. Intracerebral inoculation of HSV-1 in rats induced fever, motor hyperactivity and aggressive behavior. In adrenalectomized rats HSV-1 failed to induce these signs, although mortality rate was identical to sham-operated rats. Hypophysectomy or blocking glucocorticoid receptors also prevented HSV-1-induced fever. Dexamethasone replacement therapy to adrenalectomized rats restored the HSV-1-induced fever and behavioral abnormalities. HSV-1 inoculation produced hyperproduction of prostaglandin E(2) by brain slices. This effect was abolished in adrenalectomized rats and was restored by dexamethasone treatment. In intact rats HSV-1 induced brain interleukin-1beta (IL-1beta) gene expression. Adrenalectomy alone caused brain IL-1beta expression, which did not increase after HSV-1 infection. Similarly, HSV-1 induced IL-1beta expression in astrocyte cultures. Removal of cortisol from the culture medium caused basal IL-1beta mRNA expression which was not increased by infection. In conclusion, fever, motor hyperactivity and aggressive behavior during experimental HSV-1 encephalitis are dependent on brain responses, including prostaglandin E(2) and IL-1beta synthesis. Circulating glucocorticoids play an essential permissive role in the induction of these host brain responses.

Neural progenitors from human embryonic stem cells

The derivation of neural progenitor cells from human embryonic stem (ES) cells is of value both in the study of early human neurogenesis and in the creation of an unlimited source of donor cells for neural transplantation therapy. Here we report the generation of enriched and expandable preparations of proliferating neural progenitors from human ES cells. The neural progenitors could differentiate in vitro into the three neural lineages--astrocytes, oligodendrocytes, and mature neurons. When human neural progenitors were transplanted into the ventricles of newborn mouse brains, they incorporated in large numbers into the host brain parenchyma, demonstrated widespread distribution, and differentiated into progeny of the three neural lineages. The transplanted cells migrated along established brain migratory tracks in the host brain and differentiated in a region-specific manner, indicating that they could respond to local cues and participate in the processes of host brain development. Our observations set the stage for future developments that may allow the use of human ES cells for the treatment of neurological disorders.

Acute effects of purified and UV-inactivated Herpes simplex virus type 1 on the hypothalamo-pituitary-adrenocortical axis

Herpes simplex virus type 1 (HSV-1) is a common cause of viral encephalitis, manifested by neuroendocrine and behavioral changes. We have previously demonstrated that HSV-1 induces marked hypothalamo-pituitary-adrenocortical (HPA) axis activation. In this study we characterized the acute effects of HSV-1 on the HPA axis occurring before viral replication and appearance of clinical signs of encephalitis. Since in previous studies we used crude virus preparations which may contain immune factors produced by the infected cells, we tested here the effects of purified HSV-1 virions. HSV-1 was propagated on Vero cells and virions were purified by centrifugation in sucrose gradients. Inactivation of viral infectivity was achieved by UV-irradiation, which caused a million-fold decrease in virus titer, as determined by plaque assay. Intracerebroventricular (ICV) inoculation of crude or purified virions induced a dose dependent increase in serum corticosterone and corticotropin (ACTH). This effect was maximal within 3.5 h postinfection and lasted for 72 h. ICV inoculation of UV-inactivated purified virions caused a marked increase in serum corticosterone and ACTH at 3.5 h, but in contrast to the effect of the active virus, the hormone levels gradually decreased at 24 h, and returned to basal levels at 72 h postinfection. HSV-1-induced HPA axis activation at 3.5 h was completely abolished by pretreatment with interleukin-1 receptor antagonist, injected ICV. Adrenalectomized rats failed to respond to ICV inoculation of purified HSV-1 by increase in ACTH. In contrast, these rats responded to ICV injection of LPS.

IN CONCLUSION

(1) HSV-1 can acutely activate the HPA axis before and independently of any viral replication; (2) HSV-1-induced HPA axis activation depends on a permissive action of circulating glucocorticoids and on host derived brain interleukin-1.

Expression of endothelial nitric oxide synthase in the ischemic penumbra: relationship to expression of neuronal nitric oxide synthase and vascular endothelial growth factor

Expressional patterns of the endothelial and neuronal forms of nitric oxide synthase (NOS) in cerebral ischemia were studied utilizing a permanent middle cerebral artery occlusion (PMCAO) model. Motor performance and infarct volumes were determined in the rats. Immunohistochemical staining for eNOS, nNOS and neurofilament were performed at 1, 2, 3, 5, 7 and 14 days after PMCAO. Vascular endothelial growth factor (VEGF) expression was determined by in-situ hybridization. PMCAO caused a reproducible cortical infarct with motor deficits in the rats. Double immunohistochemical stainings indicated that eNOS and nNOS were induced in ischemic neurons. Most stained neurons were positive for both NOS forms but some reacted with only one NOS antibody. nNOS expression peaked at 24-48 h after PMCAO, stained mainly the cytoplasm of core neurons, and disappeared after the 3rd day. eNOS expression increased until the 7th day, stained mainly the cytoplasm and membrane of penumbral cells and disappeared by the 14th day after PMCAO. VEGF expression was significantly induced in the penumbral zone in a similar distribution to eNOS. The anatomical and temporal pattern of VEGF and eNOS induction in the brain after permanent ischemia suggest that these mediators may play a role in protecting penumbral tissue from additional ischemic damage.

Headache characteristics in patients after migrainous stroke

Six patients who fulfilled strictly defined criteria for migrainous cerebral infarction and in whom other causes of stroke were ruled out were observed. All had a long-standing history of migraine with aura. In most, stroke was mild with good recovery and no recurrence. Headache frequency and severity decreased after the stroke. It is hypothesized that the improvement in migraine may be due to reduced nociceptive transmission as result of loss in vasoreactivity of the affected cerebral blood vessel.

Prognostic factors in artificially ventilated stroke patients

OBJECTIVES

To evaluate the reasons for implementing artificial ventilation (AV) in patients with acute ischemic stroke (AIS), determine their outcome and characterize prognostic variables in these patients.

METHODS

Consecutive patients presenting with AIS were evaluated. All patients who received AV were treated in a neurological semi-intensive care setting.

RESULTS

Of the 173 patients included in the study, 27 (16%) needed AV, 16 (9%) received AV and five of these patients (31%) survived. The mean NIH stroke scale score prior to AV was 14.5+/-5.6 (vs. 9.1+/-6.2 in non-intubated patients, P=0.001). Six patients were ventilated because of neurological deterioration. Most of these patients had large hemispheric infarctions with evident herniation and midline shift on CT scans. The only one who survived the acute hospitalization did not recover and died within 3 months. In the other 10 patients, AV was instituted during cardiopulmonary decompensation (CPD). These patients generally fared better; four of them survived and were discharged after a lengthier hospital stay when compared to non-intubated patients. Variables associated with survival among intubated patients were a lower neurological disability score on admission and on day 7 after the stroke, and intubation during CPD.

CONCLUSIONS

Implementing AV in semi-intensive care settings does not seem to improve survival in AIS patients with neurological deterioration. Stroke patients who need AV during CPD and those that have less severe neurological deficits may have better chances for survival.

Bilateral focal motor status epilepticus with retained consciousness after stroke

Bilateral motor seizures with retained consciousness are rare and often mistaken for pseudoseizures. In the few reported cases, the seizures were brief and the underlying lesion usually was a tumor. Here the authors describe a patient with bilateral focal motor status epilepticus with retained consciousness after a stroke. A seizure should be considered as the possible cause of continuous bilateral limb movements with retained consciousness.

From neural stem cells to myelinating oligodendrocytes

The potential to generate oligodendrocytes progenitors (OP) from neural stem cells (NSCs) exists throughout the developing CNS. Yet, in the embryonic spinal cord, the oligodendrocyte phenotype is induced by sonic hedgehog in a restricted anterior region. In addition, neuregulins are emerging as potent regulators of early and late OP development. The ability to isolate and grow NSCs as well as glial-restricted progenitors has revealed that FGF2 and thyroid hormone favor an oligodendrocyte fate. Analysis of genetically modified mice showed that PDGF controls the migration and production of oligodendrocytes in vivo. Interplay between mitogens, thyroid hormone, and neurotransmitters may maintain the undifferentiated stage or result in OP growth arrest. Notch signaling by axons inhibits oligodendrocyte differentiation until neuronal signals--linked to electrical activity-trigger initiation of myelination. To repair myelin in adult CNS, multipotential neural precursors, rather than slowly cycling OP, appear the cells of choice to rapidly generate myelin-forming cells.

Polysialylated neural cell adhesion molecule-positive CNS precursors generate both oligodendrocytes and Schwann cells to remyelinate the CNS after transplantation

Transplantation offers a means of identifying the differentiation and myelination potential of early neural precursors, features relevant to myelin regeneration in demyelinating diseases. In the postnatal rat brain, precursor cells expressing the polysialylated (PSA) form of the neural cell adhesion molecule NCAM have been shown to generate mostly oligodendrocytes and astrocytes in vitro (Ben-Hur et al., 1998). Immunoselected PSA-NCAM+ newborn rat CNS precursors were expanded as clusters with FGF2 and grafted into a focal demyelinating lesion in adult rat spinal cord. We show that these neural precursors can completely remyelinate such CNS lesions. While PSA-NCAM+ precursor clusters contain rare P75+ putative neural crest precursors, they do not generate Schwann cells in vitro even in the presence of glial growth factor. Yet they generate oligodendrocytes, astrocytes, and Schwann cells in vivo when confronted with demyelinated axons in a glia-free area. We confirmed the transplant origin of these Schwann cells using Y chromosome in situ hybridization and immunostaining for the peripheral myelin protein P0 of tissue from female rats that had been grafted with male cell clusters. The number and distribution of Schwann cells within remyelinated tissue, and the absence of P0 mRNAs in donor cells, indicated that Schwann cells were generated by expansion and differentiation of transplanted PSA-NCAM+ neural precursors and were not derived from contaminating Schwann cells. Thus, transplantation into demyelinated CNS tissue reveals an unexpected differentiation potential of a neural precursor, resulting in remyelination of CNS axons by PNS and CNS myelin-forming cells.

The role of brain cytokines in mediating the behavioral and neuroendocrine effects of intracerebral mycoplasma fermentans

Intracerebral administration of Mycoplasma fermentans (MF), a small microorganism that has been found in the brain of some AIDS patients, induces behavioral and neuroendocrine alterations in rats. To examine the role of tumor necrosis factor-alpha (TNFalpha) and interleukin-1 (IL-1) in mediating these effects we measured MF-induced expression of TNFalpha and IL-1beta mRNA in various brain regions, and the effects of TNFalpha synthesis blockers and IL-1 receptor antagonist (IL-1ra) on MF-induced sickness behavior and adrenocortical activation. Intracerebroventricular (i.c.v.) administration of heat-inactivated MF induced the expression of both TNFalpha and IL-1beta mRNA in the cortex, dorsal hippocampus, amygdala, and hypothalamus. Pre-treatment of rats with either TNFalpha synthesis blockers, pentoxifylline or rolipram, or with IL-1ra did not attenuate MF-induced anorexia, body weight loss, and suppression of social behavior. However, simultaneous administration of both pentoxifylline and IL-1ra markedly attenuated MF-induced anorexia and body weight loss, but had no effect on the suppression of social behavior. Pre-treatment with pentoxifylline, but not with IL-1ra, significantly attenuated MF-induced corticosterone (CS) secretion. Together, these findings indicate that both TNFalpha and IL-1 participate, in a complementary manner, in mediating some of the behavioral effects of MF, whereas only TNFalpha, but not IL-1, is involved in mediating MF-induced adrenocortical activation. We suggest that cytokines within the brain are involved in mediating at least some of the neurobehavioral and neuroendocrine abnormalities that may be produced by MF in AIDS patients.

Growth and fate of PSA-NCAM+ precursors of the postnatal brain

Oligodendrocyte-type 2 astrocyte (O-2A) lineage cells are derived from multipotential stem cells of the developing CNS. Precursors of O-2A progenitors express the polysialylated (PSA) form of the neural cell adhesion molecule (NCAM) and are detected in neonatal rat brain glial cultures. It is unclear how such PSA-NCAM+ "pre-progenitors" are related to neural stem cells and whether they still have the potential to differentiate along several neural lineages. Here we isolated PSA-NCAM+ pre-progenitor cells from glial cultures by immunopanning and found that most of these cells expressed nestin and PDGF-receptor-alpha but not O-2A antigens. PSA-NCAM+ cells synthesized transcripts for fibroblast growth factor (FGF) receptors 1, 2, and 3 and responded to FGF2 by survival and proliferation, growing into large clusters resembling neural spheres. FGF2-induced proliferation of PSA-NCAM+ pre-progenitors was significantly enhanced by thyroid hormone (T3), which on its own did not increase cell survival or mitosis. After adhesion and withdrawal of the mitogen, spheres generated mostly oligodendrocytes and astrocytes but very rarely neurons. PSA-NCAM immunopanned cells grown in epidermal growth factor (EGF) also adopted a mostly glial fate after differentiation. In contrast, PSA-NCAM-negative cells and striatal neonatal stem cells, grown in EGF or FGF2, generated the three CNS cell types. Like neural stem cells, PSA-negative cells generated more oligodendrocytes and fewer neurons when expanded in FGF2 and T3. Thus emergence of PSA-NCAM at the surface of neonatal brain precursors coincides with their restriction to a glial fate. T3 modulates these events by enhancing PSA-NCAM+ pre-progenitor growth in FGF2 and favoring an oligodendrocyte fate.

Cytokine production in the brain following closed head injury: dexanabinol (HU-211) is a novel TNF-alpha inhibitor and an effective neuroprotectant

Traumatic brain injury triggers a cascade of events resulting in delayed edema, necrosis and impaired function. Harmful mediators are accumulating in the brain after injury and recently, the role of cytokines in the pathophysiology of brain injury has been suggested. We have developed an experimental model for closed head injury (CHI), in which edema, blood-brain-barrier disruption, motor and memory dysfunctions have been demonstrated. In this study, spatial and temporal induction of IL-1, IL-6 and TNF-alpha gene mRNA transcription and of TNF-alpha and IL-6 activity in rat brain after CHI are shown. Dexanabinol, HU-211, is a synthetic cannabinoid devoid of cannabimimetic effects; it exhibits pharmacological properties of N-methyl-D-aspartate (NMDA)-receptor antagonist and is an effective cerebroprotectant. We report here that HU-211 is a novel inhibitor of TNF-alpha production at a post-transcriptional stage. HU-211, pentoxyfilline and TNF-binding protein improved the outcome of CHI. We suggest that TNF-alpha is a primary mediator of neurotoxicity after CHI, as inhibition of TNF-alpha is associated with better clinical recovery. TNF-alpha modulating agents, if given within the early time window post-injury, may improve the final neurological outcome in victims of brain trauma.

Mononeuritis multiplex: a rare complication of acute hepatitis A

A 28-year-old man suffered from acute severe hepatitis A virus infection, documented by serologic diagnosis. During the clinical and enzymatic recovery phase, mononeuritis multiplex that involved the left ulnar and right lateral cutaneous nerves developed. It presented by sensorimotor disturbances in left arm and right thigh. Mononeuritis multiplex has been frequently described in patients with chronic hepatitis B, either isolated or associated with periarteritis nodosa. However, it has not been reported in association with hepatitis A infection.

Rescue of HSV-1 neurovirulence is associated with induction of brain interleukin-1 expression, prostaglandin synthesis and neuroendocrine responses

Several HSV-1 neurovirulence genes have been mapped but the mechanisms by which they affect host-virus interactions are not known. We have previously mapped HSV-1 neurovirulence to the UL53 gene region of the viral DNA by transfer of this gene from the neurovirulent R-19 strain to the non-neurovirulent R-15 strain in the generation of the p-71 recombinant, in which neurovirulence was rescued. In the present study we inoculated these strains into the paraventricular nucleus (PVN) of the hypothalamus of rats. We examined: (1) Clinical course of encephalitis. (2) Hypothalamic-pituitary-adrenocortical (HPA) axis function. (3) Brain cytokine gene mRNA expression and prostaglandin E2 (PGE2) production. (4) The relation of these parameters to viral replication and to cellular inflammation. In R-15 infected rats no signs of disease were observed. There was a temporary inflammatory reaction and IL-1 beta transcription in the PVN area. The function of the HPA axis was similar to control rats. Only slight increase in brain PGE2 production was found. In R-19 and p-71 infected rats, overt clinical signs of encephalitis and cellular inflammation in the PVN area were observed within 3 days post-infection (p.i). All rats died between 4-7 days p.i. These strains induced IL-1 beta transcription in the hypothalamus as well as in extra-hypothalamic brain regions in which no cellular inflammation was found. Basal serum ACTH and' CS were markedly elevated and hypothalamic CRF-41 content was significantly reduced as compared to R-15 infected rats. Both strains markedly increased brain PGE2 production. HSV-1 brain titers at 3 days p.i. were 100-fold lower than the inoculum titer although clinical signs of encephalitis were prominent. The results suggest that rescue of HSV-1 neurovirulence by the UL53 gene region of the viral genome is associated with enhancement of viral-induced brain IL-1 beta gene expression, increased brain PGE2 synthesis and hypersecretion of HPA axis hormones. Viral-induced brain derived cytokines and prostaglandins may contribute to the clinical syndrome of acute herpetic encephalitis in particular at early stages of the disease when virus load in the brain is low and cellular infiltrates are not widespread.

The clinical significance of a single abnormal immunoglobulin band in cerebrospinal fluid electrophoresis

The finding of oligoclonal immunoglobulin (Ig) bands in the cerebrospinal fluid (CSF) is considered a cornerstone in the diagnosis of multiple sclerosis, but can be observed in other diseases as well. In a small subset of patients only a single Ig band, confined to the CSF, is identified. We evaluated the possible diagnostic significance of such a finding. Agarose gels of 6000 CSF samples were re-examined. In 1013 samples (16.8%) there were oligoclonal bands, and in 33 additional samples (0.55%) a single band was found (without a correlating band in the serum). Full data was available for 20 single band patients. Seven patients had clinical definite multiple sclerosis. Of these, 6 had a typically prominent affective disorder and 5 had a relatively malignant course of disease. Seven additional patients had other white matter diseases of the central nervous system (CNS). The remaining patients had inflammatory diseases of peripheral nerves or CNS gray matter and non-inflammatory brain diseases. The frequency of demyelinating diseases of the CNS in patients with a single abnormal Ig band in the CSF was significantly less than in a control group of patients with oligoclonal bands. In conclusion, the finding of a single Ig band confined to the CSF may hint for a disease other than multiple sclerosis, and mark an aggressive course with affective disorder in those who do have multiple sclerosis.

Effects of HSV-1, a neurotropic virus, on the hypothalamic-pituitary-adrenocortical axis in rats

It is well established that the hypothalamic-pituitary-adrenocortical (HPA) axis is activated during systemic viral diseases. In this study we examined the effects of a neurotropic virus, herpes simplex virus type 1 (HSV-1), on the HPA axis in male rats. Following corneal inoculation with HSV-1, the virus invaded the nervous system and replicated in the brainstem without clinical signs of disease. During this asymptomatic brainstem infection with HSV-1, significant changes were found in the function of the HPA axis: On days 3, 7 and 14 post-infection (p.i.) basal ACTH and corticosterone (CS) levels were markedly elevated, and photic stressful stimulation failed to further increase the levels of these hormones. In addition, the elevated basal serum levels of ACTH and CS could not be suppressed by pretreatment with dexamethasone. The content of CRF-41 in the paraventricular nucleus of the hypothalamus and in the median eminence measured at 6 days p.i. was similar to that of vehicle inoculated rats. By 4 weeks p.i. the basal levels of ACTH and CS returned to normal and these animals responded to photic stimulation and dexamethasone similar to vehicle inoculated rats. Systemic (intraperitoneal) inoculation of HSV-1 did not induce any changes in the HPA axis responses. We therefore suggest that asymptomatic acute infection of the brainstem with HSV-1 may affect brain regions involved in the regulation of the HPA axis, and that those effects are mediated centrally and not by a systemic mechanism.

Familial Sneddon's syndrome

We report the familial occurrence and apparent autosomal dominant inheritance of Sneddon's syndrome with variable clinical expression. The proband, a 40-year-old woman, presented with livedo reticularis and progressive neurological deterioration following a stroke. The diagnosis was confirmed by cerebral angiogram and skin biopsy, both showing the characteristic findings. Two of the patient's sisters were reported to have been similarly affected in the past. Her mother, two additional siblings and five of her seven children exhibited various vasospastic skin phenomena. Familial aggregation of this disorder may be common and a genetic basis may be involved in its pathogenesis.

Valproate encephalopathy and hypocarnitinaemia in diabetic patients

Two patients with epilepsy and diabetes mellitus developed encephalopathy while on valproate monotherapy. Low plasma carnitine levels were found. Discontinuation of valproate was followed by clinical recovery and normalization of carnitine levels. Both valproate treatment and diabetes mellitus may contribute to secondary carnitine deficiency, with resultant encephalopathy. Thus, diabetic patients may be at increased risk of developing valproate encephalopathy associated with hypocarnitinaemia.

[Thiamin deficiency is common in Israel]

Diseases due to vitamin B1 (thiamin) deficiency are considered to be uncommon in Israel. We present 13 patients admitted during the course of a year who were found to have thiamin deficiency. 5 had classic syndromes such as beri-beri, Wernicke's encephalopathy and cerebellar degeneration. In another 8 the thiamin deficiency was found during workup for less specific neurological abnormalities. Only a minority were alcoholics. Mainly at risk for developing nutritional deficiency were the solitary elderly of low socio-economic status with poor nutrition. Other reasons for thiamin deficiency were drug abuse and hyperemesis gravidarum. Thiamin levels should be determined not only in alcoholics and those with classic B1 deficiency syndromes, but in the routine workup of patients with sensory-motor neuropathy, dementia, gait disorders, cerebellar syndromes and confusional states. It is advised to give vitamins prophylactically to asymptomatic high risk patients.

Characterization of RNA transcripts from herpes simplex virus-1 DNA fragment BamHI-B

Herpes simplex virus type 1 (HSV-1) DNA fragment BamHI-B (0.738-0.809 map units) was recently reported to be associated with the phenotype of intraperitoneal pathogenicity and to encode a latency-associated RNA transcript. Part of this fragment resides within the internal repeat sequence of the long (L) region of the viral genome. In this study, RNA transcripts from BamHI-B were characterized. In addition to immediate-early mRNAs IE-1 and IE-2, eight novel RNA species were found. Three transcripts were mapped in the repeat regions of this fragment and five transcripts in the unique L region of BamHI-B. In addition, transcription activity from these regions was compared in several HSV-1 strains. These included the intraperitoneal virulent F and KOS strains, the avirulent strain HFEM, as well as the HFEM/F intratypic virulent recombinant R-MIC1. Several differences were noted and their possible relevance to virulence is discussed.

Comparative analysis of the transcripts mapped in the BamHI DNA fragment B of avirulent HSV-1 HFEM, virulent HSV-1 F, and their intratypic recombinant viruses

HSV-1 HFEM, whose genome harbors a deletion of 4.1 kbp (0.762 to 0.789 map units (mu] is avirulent for mice and tree shrews by the intraperitoneal (i.p.) application route. Insertion of the BamHI DNA fragment B (0.738 to 0.809 mu) and/or the MluI DNA fragment (0.7615 to 0.796 mu) molecularly cloned from virulent HSV-1 F, restored the i.p. pathogenicity to strain HFEM and led to the isolation of virulent intratypic recombinants. In order to determine the RNA transcripts mapped in the BamHI DNA fragment B of the HSV-1 HFEM, HSV-1 F, and their intratypic recombinants R15, R19, R26, and R-Ml-C1, a comparative analysis was performed using Northern blot hybridizations. Two novel RNA transcripts of 3.5 and 1.5 kb were detected which hybridize to the left terminus (0.738 to 0.746 mu) of the BamHI DNA fragment B. The 1.5 kb RNA transcript was missing in the avirulent HSV-1 HFEM. Hybridization with the BssHII DNA fragment F (0.760 to 0.762 mu) led to detection of a 3.5 kb RNA transcript by HSV-1 HFEM which was missing in all other viruses tested. In contrast a 1.5 kb RNA transcript was detectable in all other virus strains with the exception of HSV-1 HFEM. The 3.5 kb transcript hybridized to the right-hand flank of the deleted region in the genome of HSV-1 HFEM (Asp718/SalI DNA fragment; 0.786 to 0.79 mu). The detection of the novel 1.5 kb RNA, which is missing in HSV-1 HFEM, and the appearance of the newly transcribed 3.5 kb RNA in HSV-1 HFEM only, indicates a new open reading frame in this particular region as a consequence of the fusion of the DNA sequences at both ends of the deletion in the genome of HSV-1 HFEM.

HSV-1 DNA sequence determining intraperitoneal pathogenicity in mice is required for transcription of viral immediate-early genes in macrophages

The relationship between intraperitoneal (ip) pathogenicity in vivo of herpes simplex virus type 1 (HSV-1) and infection of macrophages (m phi) in vitro was studied. The apathogenic HSV-1 strain HFEM disappeared from the peritoneum of infected mice following ip inoculation, while the pathogenic F strain persisted in the peritoneum and penetrated the mouse nervous system, and eventually the mice died, showing severe neurological signs. When peritoneal m phi were infected in vitro, a direct correlation with pathogenicity in vivo was found with several HSV-1 strains and recombinants. HSV-1 strains (F, KOS, R-M1C1) which were pathogenic for mice by the ip route, induced cytopathic effect (CPE) in m phi in vitro. Strain F transcribed viral immediate-early genes and synthesized viral DNA in m phi that were treated with L-cell conditioned medium (as a source of colony-stimulating factor) prior to infection. Apathogenic HSV-1 strains (HFEM, R-15, R-19) did not cause CPE in m phi. The HFEM strain was already blocked in the transcription of viral alpha genes in the infected m phi, but replicated well in control BSC-1 cells. An intratypic recombinant (R-M1C1), produced by cotransfection of HFEM DNA with a cloned Mlul-Mlul DNA fragment (coordinates 0.7615-0.796) from HSV-1 strain F, that was shown [Becker et al. (1986). Virology 149, 255-259] to have regained partial ip virulence for mice, now transcribed alpha genes, synthesized viral DNA, and induced CPE in m phi. It appears that the viral DNA fragment responsible for ip virulence is involved in tissue-specific recognition of virus by infected m phi, a function necessary for transcription of viral alpha genes.

HSV-1 virulence for mice by the intracerebral route is encoded by the BamHI-L DNA fragment containing the cell fusion gene

The phenotype of pathogenicity by direct intracerebral inoculation of herpes simplex virus type 1 (HSV-1) was mapped in the viral genome. This phenotype could be rescued by cotransfection of unit length HSV-1 DNA of an avirulent strain with the BamHI fragment L (0.70-0.738 map units) cloned from a virulent strain. The virulence function was localized in the 2.0 Kb NruI-BamHI fragment in the right-hand side of BamHI-L, the same region that encodes a virus cell-fusion gene (3). Transduction of virulence was linked with the phenotype of a larger plaque size. It is concluded that a neurovirulence function resides in the BamHI-L fragment of the HSV-1 genome, closely linked to the viral gene for cell fusion.

Replacement of the deletion in the genome (0.762-0.789 mu) of avirulent HSV-1 HFEM using cloned MluI DNA fragment (0.7615-0.796 mu) of virulent HSV-1 F leads to generation of virulent intratypic recombinant

The HFEM strain of HSV-1 is apathogenic for the tree shrew by the intraperitoneal (i.p.) route because of a deletion in the genome coordinates 0.762-0.789. Insertion of the MluI DNA fragment (coordinates 0.7615-0.789) cloned from HSV-1 strain F, which is pathogenic for the tree shrew, restored the i.p. pathogenicity to strain HFEM. The recombinant designated R-M1-C1 was highly pathogenic for the tree shrew, but slightly virulent for inbred mouse strain A. It thus appears that the viral DNA sequence involved in the i.p. pathogenicity of HSV-1 is located within the genome coordinates 0.761-0.796. This sequence is recognized differently by the cellular elements involved in HSV-1 infection in the tree shrew and the mouse.

A sequence in HpaI-P fragment of herpes simplex virus-1 DNA determines intraperitoneal virulence in mice

The virulence of herpes simplex virus-1 (HSV-1) strains by the intraperitoneal (ip) route of injection in mice depends on the presence of an intact sequence in the HpaI DNA fragment P within coordinates 0.762 to 0.787. Deletion of the HpaI-P region (e.g., strain HFEM) abrogates the ability of the virus to infect mice by the ip route without affecting pathogenicity by the intracerebral (ic) route. A recombinant virus (M1C1) derived from DNA of the HSV-1 HFEM strain and the MLUIDNA fragment (coordinates 0.761 to 0.796) spanning the HpaI-P sequence of the pathogenic strain F regained pathogenicity for mice by the ip route.