Epidemiology, characteristics, and prognostic factors of lymphoplasmacyte-rich meningioma: a systematic literature review.

BACKGROUNDS: Lymphoplasmacyte-rich meningioma(LPM) is a rare subtype of meningioma with a low degree of malignancy and an overall preferable prognosis. The purpose of this article is to increase the understanding of the disease, reduce misdiagnosis, and improve prognosis. METHODS: A search was conducted in the PubMed database for English articles published from 1993 to 2023. The keywords were "lymphoplasmacyte-rich (all fields) and meningioma (all fields) and English (lang)" and "lymphoplasmacyte-rich meningioma (title/abstract) and English (lang)".We further analyzed the clinical manifestations, imaging manifestations, pathological features, treatment strategies, and prognosis of LPM.The possible prognostic indicators were analyzed by the log-rank test and Pearson's chi-squared test. RESULTS: Fourteen reports with 95 LPM patients were included in this report, including 47 males and 48 females who were diagnosed between the ages of 9 and 79, with an average age of 45 years. The most common clinical manifestations are headache and limb movement disorders. In most cases, the tumor occurred on the convex portion of the brain. All tumors showed significant enhancement, with homogeneous enhancement being more common, and most patients showed peritumoral edema. Postoperative pathological EMA, LCA, and vimentin positivity were helpful for the final diagnosis of the patient. Log-rank tests showed a correlation between complete resection and better prognosis and recurrence. CONCLUSION: There is a lack of significant differences in the clinical symptoms and imaging manifestations of LPM compared to other diseases that need to be differentiated, and a clear diagnosis requires pathological examination. After standardized surgical treatment, the recurrence rate and mortality rate of LPM are both low. Complete surgical resection of tumors is associated with a better prognosis and lower recurrence rate.

Central nervous system clear cell meningioma: a systematic literature review.

Clear cell meningiomas are a rare histological subtype of World Health Organization (WHO) grade II meningioma. Despite its relatively low frequency, clear cell meningioma has attracted considerable attention because of its unique pathological characteristics, clinical behavior, and challenging management considerations. The purpose of our systematic review is to provide clinicians with a better understanding of this rare disease. PubMed was searched for articles in the English language published from 1988 to 2023 June. The keywords were as follows: "clear cell meningioma," "clear cell" and "meningioma." We analyzed clinical manifestations, radiological manifestations, pathological features, comprehensive treatment strategies, and prognosis to determine the factors influencing recurrence-free survival (RFS). Recurrence-free survival curves of related factors were calculated by the Kaplan‒Meier method. The log-rank test and Cox univariate analysis were adopted to assess the intergroup differences and seek significant factors influencing prognosis and recurrence. Fifty-seven papers met the eligibility criteria, including 207 cases of clear cell meningioma (CCM), which were confirmed by postoperative pathology. The fifty-seven articles involved 84 (40.6%) males and 123 (59.4%) females. The average age at diagnosis was 27.9 years (range, 14 months to 84 years). Among the symptoms observed, headache, neurologic deficit, and hearing loss were the most commonly reported clinical manifestations. Most tumors (47.8%) were located in the skull base region. Most tumors showed significant enhancement, and homogeneous enhancement was more common. A total of 152 (74.1%) patients underwent gross total resection (GTR), and 53 (25.9%) patients underwent subtotal resection (STR). During the follow-up, the tumor recurred in 80 (39.4%) patients. The log-rank test and the Cox univariate analysis revealed that tumor resection range (GTR vs. STR) and adjuvant treatment (YES vs. NO) were significant predictors of recurrence-free survival (RFS). Clear cell meningioma is a rare type of meningioma with challenging diagnosis and therapy. The prognosis of this disease is different from that of regular meningiomas. Recurrence remains a possibility even after total tumor resection. We found that the surgical resection range and adjuvant treatment affected the recurrence period. This finding provides significant guidance for the treatment of clear cell meningioma.

Leptomeningeal disease as a presenting feature of gestational trophoblastic neoplasia: A review and recommendations for management.

OBJECTIVES: Gestational Trophoblastic Neoplasia (GTN) is a rare group of malignant placental-related tumours requiring systemic anti-cancer treatment. Leptomeningeal disease (LMD) related to GTN is not well reported with no consensus in optimal treatment. We offer recommendations for management of these patients. METHODS: We discuss five patients with GTN who presented with features of LMD and were diagnosed with gadolinium-enhanced MRI brain, all of whom received low dose induction etoposide-cisplatin (EP) followed by either EP-etoposide, methotrexate (CNS) and actinomycin-D (EMA) or EMA(CNS)-cyclophosphamide and vincristine (CO). RESULTS: Four out of the five patients additionally received intrathecal methotrexate. Four patients had complete hCG response to first line multi-agent chemotherapy, one patient required second line paclitaxel, cisplatin alternating with paclitaxel, etoposide (TP/TE), where paclitaxel was substituted with nab-paclitaxel due to anaphylaxis, followed by hysterectomy. One of the four initial complete hCG responders relapsed in the lung requiring further systemic treatment with subsequent lobectomy. Patient reported outcomes indicate persistent neurological symptoms are mild and do not affect functionality and quality of life. CONCLUSION: With a follow-up range of 2-6 years, all five patients remain cured demonstrating excellent survival outcomes with the avoidance of whole-brain radiotherapy in all cases.

Primary intracranial lymphomas-incidence and survival: a population-based study.

Biopsy is recommended for patients with primary intracranial lymphoma to confirm the diagnosis, but the effect of tumor resection is still controversial. We conducted this retrospective study to better understand the epidemiology of primary intracranial lymphoma in the USA and explore the relationship between surgical resection and prognosis. Data regarding primary intracranial lymphoma, including incidence, were extracted from the SEER database. We analyzed the difference in incidence between different groups of people. We explored the effect of surgery on the survival of patients by the Kaplan-Meier method and evaluated the possible prognostic indicators by multivariate Cox proportional hazards models. The incidence significantly increased with age. The non-Hispanic Asian or Pacific Islander population exhibited the highest incidence, and the incidence was significantly higher in males than females. A total of 6428 cases were included in the cohort study, and most of the patients were diagnosed in the sixth to seventh decade of life. Sixty percent of tumors were supratentorial tumors. Surgery, especially total resection, significantly improved overall survival and cancer-specific survival. The survival of female patients, patients diagnosed before reaching 60 years of age, patients diagnosed after 2010, and patients with supratentorial lymphomas was better than that of their counterparts. The survival of patients with diffuse large B-cell lymphoma was worse than that of their counterparts. We conducted a comprehensive retrospective analysis of patients with primary intracranial lymphoma. We analyzed the difference in incidence between different groups of people. Surgery significantly improved overall and cancer-specific survival. The results of our research can help clinicians and patients better understand the epidemiology and management of primary intracranial lymphoma.

Targeting mitochondria in the regulation of neurodegenerative diseases: A comprehensive review.

Mitochondria are one of the essential cellular organelles. Apart from being considered as the powerhouse of the cell, mitochondria have been widely known to regulate redox reaction, inflammation, cell survival, cell death, metabolism, etc., and are implicated in the progression of numerous disease conditions including neurodegenerative diseases. Since brain is an energy-demanding organ, mitochondria and their functions are important for maintaining normal brain homeostasis. Alterations in mitochondrial gene expression, mutations, and epigenetic modification contribute to inflammation and neurodegeneration. Dysregulation of reactive oxygen species production by mitochondria and aggregation of proteins in neurons leads to alteration in mitochondria functions which further causes neuronal death and progression of neurodegeneration. Pharmacological studies have prioritized mitochondria as a possible drug target in the regulation of neurodegenerative diseases. Therefore, the present review article has been intended to provide a comprehensive understanding of mitochondrial role in the development and progression of neurodegenerative diseases mainly Alzheimer's, Parkinson's, multiple sclerosis, and amyotrophic lateral sclerosis followed by possible intervention and future treatment strategies to combat mitochondrial-mediated neurodegeneration.

Intrinsic Innate Immune Responses Control Viral Growth and Protect against Neuronal Death in an Ex Vivo Model of West Nile Virus-Induced Central Nervous System Disease.

Recruitment of immune cells from the periphery is critical for controlling West Nile virus (WNV) growth in the central nervous system (CNS) and preventing subsequent WNV-induced CNS disease. Neuroinflammatory responses, including the release of proinflammatory cytokines and chemokines by CNS cells, influence the entry and function of peripheral immune cells that infiltrate the CNS. However, these same cytokines and chemokines contribute to tissue damage in other models of CNS injury. Rosiglitazone is a peroxisome proliferator-activated receptor gamma (PPARγ) agonist that inhibits neuroinflammation. We used rosiglitazone in WNV-infected ex vivo brain slice cultures (BSC) to investigate the role of neuroinflammation within the CNS in the absence of peripheral immune cells. Rosiglitazone treatment inhibited WNV-induced expression of proinflammatory chemokines and cytokines, interferon beta (IFN-ß), and IFN-stimulated genes (ISG) and also decreased WNV-induced activation of microglia. These decreased neuroinflammatory responses were associated with activation of astrocytes, robust viral growth, increased activation of caspase 3, and increased neuronal loss. Rosiglitazone had a similar effect on in vivo WNV infection, causing increased viral growth, tissue damage, and disease severity in infected mice, even though the number of infiltrating peripheral immune cells was higher in rosiglitazone-treated, WNV-infected mice than in untreated, infected controls. These results indicate that local neuroinflammatory responses are capable of controlling viral growth within the CNS and limiting neuronal loss and may function to keep the virus in check prior to the infiltration of peripheral immune cells, limiting both virus- and immune-mediated neuronal damage. IMPORTANCE West Nile virus is the most common cause of epidemic encephalitis in the United States and can result in debilitating CNS disease. There are no effective vaccines or treatments for WNV-induced CNS disease in humans. The peripheral immune response is critical for protection against WNV CNS infections. We now demonstrate that intrinsic immune responses also control viral growth and limit neuronal loss. These findings have important implications for developing new therapies for WNV-induced CNS disease.

Primary Malignant Brain Tumors following Systemic Malignancies: A Population-Based Analysis.

BACKGROUND: Several reports have described glioma following different cancers. We assessed the prevalence of primary malignant brain tumors afterward systemic malignancies in patients in the USA based on Surveillance, Epidemiology, and End Results (SEER) program data. METHODS: The detailed data of patients with primary malignant brain tumors following an initial malignant tumor outside the central nervous system were extracted from SEER. Descriptive statistics were used to analyze patient demographic and clinical characteristics. We also extracted standardized incidence ratios (SIRs) stratified by age, race, sex, history of radiation or chemotherapy, histology findings, and primary cancer site. RESULTS: We identified 5,212 patients diagnosed with primary malignant brain tumors following systemic malignancies. Most patients had prostate cancer, breast cancer, and skin melanoma as the primary cancer. The median duration between the first diagnosis of cancer and that of the subsequent malignant brain tumor was 53 months. Glioblastoma was the most common subsequent malignant brain tumor type. The prognosis after subsequent malignant brain tumor diagnosis was poor. The SIRs differed most by race, cancer site, and cancer type. Patients with acute lymphocytic leukemia had the highest risk of developing primary malignant brain tumors. CONCLUSION: Our study provides a comprehensive analysis of clinical data and the SIRs of patients with primary malignant brain tumors afterward other systemic malignancies. Genetic relationships might play a key role in subsequent malignant brain tumor origin. Our data provide directions for future studies exploring the hidden associations between systemic malignancies and primary malignant brain tumors.

Neural In Vitro Models for Studying Substances Acting on the Central Nervous System.

Animal models have been greatly contributing to our understanding of physiology, mechanisms of diseases, and toxicity. Yet, their limitations due to, e.g., interspecies variation are reflected in the high number of drug attrition rates, especially in central nervous system (CNS) diseases. Therefore, human-based neural in vitro models for studying safety and efficacy of substances acting on the CNS are needed. Human iPSC-derived cells offer such a platform with the unique advantage of reproducing the "human context" in vitro by preserving the genetic and molecular phenotype of their donors. Guiding the differentiation of hiPSC into cells of the nervous system and combining them in a 2D or 3D format allows to obtain complex models suitable for investigating neurotoxicity or brain-related diseases with patient-derived cells. This chapter will give an overview over stem cell-based human 2D neuronal and mixed neuronal/astrocyte models, in vitro cultures of microglia, as well as CNS disease models and considers new developments in the field, more specifically the use of brain organoids and 3D bioprinted in vitro models for safety and efficacy evaluation.

Activation of carbonic anhydrases from human brain by amino alcohol oxime ethers: towards human carbonic anhydrase VII selective activators.

The synthesis and carbonic anhydrase (CA; EC 4.2.1.1) activating effects of a series of oxime ether-based amino alcohols towards four human (h) CA isoforms expressed in human brain, hCA I, II, IV and VII, are described. Most investigated amino alcohol derivatives induced a consistent activation of the tested CAs, with KAs spanning from a low micromolar to a medium nanomolar range. Specifically, hCA II and VII, putative main CA targets when central nervous system (CNS) diseases are concerned, were most efficiently activated by these oxime ether derivatives. Furthermore, a multitude of selective hCA VII activators were identified. As hCA VII is one of the key isoforms involved in brain metabolism and other brain functions, the identified potent and selective hCA VII activators may be considered of interest for investigations of various therapeutic applications or as lead compounds in search of even more potent and selective CA activators.

Human iPSC-Based Modeling of Central Nerve System Disorders for Drug Discovery.

A high-throughput drug screen identifies potentially promising therapeutics for clinical trials. However, limitations that persist in current disease modeling with limited physiological relevancy of human patients skew drug responses, hamper translation of clinical efficacy, and contribute to high clinical attritions. The emergence of induced pluripotent stem cell (iPSC) technology revolutionizes the paradigm of drug discovery. In particular, iPSC-based three-dimensional (3D) tissue engineering that appears as a promising vehicle of in vitro disease modeling provides more sophisticated tissue architectures and micro-environmental cues than a traditional two-dimensional (2D) culture. Here we discuss 3D based organoids/spheroids that construct the advanced modeling with evolved structural complexity, which propels drug discovery by exhibiting more human specific and diverse pathologies that are not perceived in 2D or animal models. We will then focus on various central nerve system (CNS) disease modeling using human iPSCs, leading to uncovering disease pathogenesis that guides the development of therapeutic strategies. Finally, we will address new opportunities of iPSC-assisted drug discovery with multi-disciplinary approaches from bioengineering to Omics technology. Despite technological challenges, iPSC-derived cytoarchitectures through interactions of diverse cell types mimic patients' CNS and serve as a platform for therapeutic development and personalized precision medicine.

Neuroinflammatory Disease as an Isolated Manifestation of Hemophagocytic Lymphohistiocytosis.

Isolated neuroinflammatory disease has been described in case reports of familial hemophagocytic lymphohistiocytosis (FHL), but the clinical spectrum of disease manifestations, response to therapy and prognosis remain poorly defined. We combined an international survey with a literature search to identify FHL patients with (i) initial presentation with isolated neurological symptoms; (ii) absence of cytopenia and splenomegaly at presentation; and (iii) systemic HLH features no earlier than 3 months after neurological presentation. Thirty-eight (20 unreported) patients were identified with initial diagnoses including acute demyelinating encephalopathy, leukoencephalopathy, CNS vasculitis, multiple sclerosis, and encephalitis. Median age at presentation was 6.5 years, most commonly with ataxia/gait disturbance (75%) and seizures (53%). Diffuse multifocal white matter changes (79%) and cerebellar involvement (61%) were common MRI findings. CSF cell count and protein were increased in 22/29 and 15/29 patients, respectively. Fourteen patients progressed to systemic inflammatory disease fulfilling HLH-2004 criteria at a mean of 36.9 months after initial neurological presentation. Mutations were detected in PRF1 in 23 patients (61%), RAB27A in 10 (26%), UNC13D in 3 (8%), LYST in 1 (3%), and STXBP2 in 1 (3%) with a mean interval to diagnosis of 28.3 months. Among 19 patients who underwent HSCT, 11 neurologically improved, 4 were stable, one relapsed, and 3 died. Among 14 non-transplanted patients, only 3 improved or had stable disease, one relapsed, and 10 died. Isolated CNS-HLH is a rare and often overlooked cause of inflammatory brain disease. HLH-directed therapy followed by HSCT seems to improve survival and outcome.

Viral Factors Important for Efficient Replication of Influenza A Viruses in Cells of the Central Nervous System.

Central nervous system (CNS) disease is one of the most common extrarespiratory tract complications of influenza A virus infections. Remarkably, zoonotic H5N1 virus infections are more frequently associated with CNS disease than seasonal or pandemic influenza viruses. Little is known about the interaction between influenza A viruses and cells of the CNS; therefore, it is currently unknown which viral factors are important for efficient replication. Here, we determined the replication kinetics of a seasonal, pandemic, zoonotic, and lab-adapted influenza A virus in human neuron-like (SK-N-SH) and astrocyte-like (U87-MG) cells and primary mouse cortex neurons. In general, highly pathogenic avian influenza (HPAI) H5N1 virus replicated most efficiently in all cells, which was associated with efficient attachment and infection. Seasonal H3N2 and to a lesser extent pandemic H1N1 virus replicated in a trypsin-dependent manner in SK-N-SH but not in U87-MG cells. In the absence of trypsin, only HPAI H5N1 and WSN viruses replicated. Removal of the multibasic cleavage site (MBCS) from HPAI H5N1 virus attenuated, but did not abrogate, replication. Taken together, our results showed that the MBCS and, to a lesser extent, the ability to attach are important determinants for efficient replication of HPAI H5N1 virus in cells of the CNS. This suggests that both an alternative hemagglutinin (HA) cleavage mechanism and preference for α-2,3-linked sialic acids allowing efficient attachment contribute to the ability of influenza A viruses to replicate efficiently in cells of the CNS. This study further improves our knowledge on potential viral factors important for the neurotropic potential of influenza A viruses.IMPORTANCE Central nervous system (CNS) disease is one of the most common extrarespiratory tract complications of influenza A virus infections, and the frequency and severity differ between seasonal, pandemic, and zoonotic influenza viruses. However, little is known about the interaction of these viruses with cells of the CNS. Differences among seasonal, pandemic, and zoonotic influenza viruses in replication efficacy in CNS cells, in vitro, suggest that the presence of an alternative HA cleavage mechanism and ability to attach are important viral factors. Identifying these viral factors and detailed knowledge of the interaction between influenza virus and CNS cells are important to prevent and treat this potentially lethal CNS disease.

Contribution of P2X4 Receptors to CNS Function and Pathophysiology.

The release and extracellular action of ATP are a widespread mechanism for cell-to-cell communication in living organisms through activation of P2X and P2Y receptors expressed at the cell surface of most tissues, including the nervous system. Among ionototropic receptors, P2X4 receptors have emerged in the last decade as a potential target for CNS disorders such as epilepsy, ischemia, chronic pain, anxiety, multiple sclerosis and neurodegenerative diseases. However, the role of P2X4 receptor in each pathology ranges from beneficial to detrimental, although the mechanisms are still mostly unknown. P2X4 is expressed at low levels in CNS cells including neurons and glial cells. In normal conditions, P2X4 activation contributes to synaptic transmission and synaptic plasticity. Importantly, one of the genes present in the transcriptional program of myeloid cell activation is P2X4. Microglial P2X4 upregulation, the P2X4+ state of microglia, seems to be common in most acute and chronic neurodegenerative diseases associated with inflammation. In this review, we summarize knowledge about the role of P2X4 receptors in the CNS physiology and discuss potential pitfalls and open questions about the therapeutic potential of blocking or potentiation of P2X4 for different pathologies.

Role of Extracellular Vesicles in Substance Abuse and HIV-Related Neurological Pathologies.

Extracellular vesicles (EVs) are a broad, heterogeneous class of membranous lipid-bilayer vesicles that facilitate intercellular communication throughout the body. As important carriers of various types of cargo, including proteins, lipids, DNA fragments, and a variety of small noncoding RNAs, including miRNAs, mRNAs, and siRNAs, EVs may play an important role in the development of addiction and other neurological pathologies, particularly those related to HIV. In this review, we summarize the findings of EV studies in the context of methamphetamine (METH), cocaine, nicotine, opioid, and alcohol use disorders, highlighting important EV cargoes that may contribute to addiction. Additionally, as HIV and substance abuse are often comorbid, we discuss the potential role of EVs in the intersection of substance abuse and HIV. Taken together, the studies presented in this comprehensive review shed light on the potential role of EVs in the exacerbation of substance use and HIV. As a subject of growing interest, EVs may continue to provide information about mechanisms and pathogenesis in substance use disorders and CNS pathologies, perhaps allowing for exploration into potential therapeutic options.

Synthesis, CYP 450 evaluation, and docking simulation of novel 4-aminopyridine and coumarin derivatives.

Four series of novel compounds based on 4-aminopyridine, glatiramer acetate, pyrone, and coumarin backbones were sufficiently synthesized and identified by spectroscopic methods. CYP enzyme inhibition assays of five predominate human P450 isozymes indicate that all compounds, except for 4-hydrazide pyridine 1c, seem to be less toxic than 4-aminopyridine. Further investigation of the compounds using molecular docking experiments revealed different, the same, or stronger binding modes for most of the synthesized compounds, with both polar and hydrophobic interactions with the 1WDA and 1J95 receptors compared to benzoyl l-arginine amide and 4-aminopyridine, respectively. These results introduce the synthesized compounds as K+ channel blockers that could be considered for in vivo CNS disease studies.

The roles of extracellular vesicle microRNAs in the central nervous system.

MicroRNAs (miRNAs) are small, highly conserved non-coding RNA molecules that post-transcriptionally regulate protein expression and most biological processes. Mature miRNAs are recruited to the RNA-induced silencing complex (RISC) and target mRNAs via complementary base-pairing, thus resulting in translational inhibition and/or transcript degradation. Here, we present evidence implicating miRNAs within extracellular vesicles (EVs), including microvesicles and exosomes, as mediators of central nervous system (CNS) development, homeostasis, and injury. EVs are extracellular vesicles that are secreted by all cells and represent a novel method of intercellular communication. In glial cells, the transfer of miRNAs via EVs can alter the function of recipient cells and significantly impacts cellular mechanisms involved in both injury and repair. This review discusses the value of information to be gained by studying miRNAs within EVs in the context of CNS diseases and their potential use in the development of novel disease biomarkers and therapeutic strategies.

Resolving neuroinflammation, the therapeutic potential of the anti-malaria drug family of artemisinin.

Artemisinin (Qinghaosu) and its semi-synthetic derivatives have been demonstrated to alleviate neuroinflammatory response in the central nerve system (CNS). In this review, we summarized that artemisinins are capable to treat neuroinflammtion-related CNS diseases in both direct (via regulating inflammatory process in the CNS, exerting anti-oxidative stress and neuroprotective effect, and preventing Aß accumulation) and indirect (via maintaining BBB integrity, suppressing systemic inflammation and alleviating intestinal inflammtion) manner. However, the precise mechanism of their anti-neuroinflammatory effects and potential neurotoxicity, which hindered further progress in these aspects, remains unclear. We suggest that further understanding of the PK/PD properties and structure-action relationship of atemisinin and its derivatives will facilitate the development of new therapeutics with better curative effects and safety.

Treatment modalities for advanced ALK-rearranged non-small-cell lung cancer.

The ALK gene plays a key role in the pathogenesis of non-small-cell lung cancer (NSCLC). Patients with NSCLC harboring an ALK-rearrangement represent the second oncogene addiction to be identified in this disease. Crizotinib was the first ALK inhibitor showing pronounced clinical activity, and is now a reference treatment for ALK-positive NSCLC disease. However, despite initial impressive responses to crizotinib, acquired resistance almost invariably develops within 12 months. The pressing need for effective second-line agents has prompted the rapid development of next-generation ALK inhibitors. These agents, notably ceritinib and alectinib as the most developed, have a higher potency against ALK than crizotinib, along with activity against tumors harboring crizotinib-resistant mutations and potentially improved CNS penetration.

Clostridium septicum Pneumocephalus.

BACKGROUND: Spontaneous pneumocephalus in the nontraumatic setting is distinctly unusual. Pneumocephalus from central nervous system infection with Clostridium septicum has been rarely reported, and more commonly reflects a later stage of abscess formation. We present an unusual case of invasive C. septicum infection without an associated diagnosed malignancy presenting with rapidly progressive CNS pathology and resultant early pneumocephalus. METHODS: Medical records, radiologic imaging, and microbiological specimens of a case were reviewed. RESULTS: A 66-year-old male presented with a history of two witnessed generalized tonic-clonic seizures on awakening. He was found unresponsive at the scene by paramedics and subsequently intubated. There was no reported antecedent symptomatology, such as headache, fever, chills, focal weakness, and speech or gait disturbances. Medical history was remarkable only for diet-controlled hypertension. Computed tomography (CT) head imaging revealed an abnormal right parietal hypodensity. The patient was evaluated per the acute stroke protocol but was not deemed a candidate for intervention or thrombolytic therapy given the uncertainty of his clinical presentation; intravenous antibiotics were administered for possible sepsis. Follow-up CT imaging of the head performed 8 h later revealed right parieto-temporal pneumocephalus with extensive cerebral edema and effacement of basilar cisterns. Neurosurgical intervention was not deemed appropriate given the catastrophic nature of his injury and the patient subsequently expired 14 h after presentation. Blood cultures grew gram-positive rods in three of four bottles identified as C. septicum. CONCLUSIONS: Clostridium septicum is an uncommon and often fatal cause of nontraumatic pneumocephalus. This underscores the need for a high index of clinical suspicion in cases with unexplained pneumocephalus, as early diagnosis remains the key to survival. In survivors of C. septicum infection, subsequent colonoscopy should be considered to exclude undiagnosed or occult gastrointestinal malignancy.

Th17-biased RORγt transgenic mice become susceptible to a viral model for multiple sclerosis.

In a viral model for multiple sclerosis (MS), Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), both immune-mediated tissue damage (immunopathology) and virus persistence have been shown to cause pathology. T helper (Th) 17 cells are a Th cell subset, whose differentiation requires the transcription factor retinoic acid-related orphan receptor (ROR) γt, secrete pro-inflammatory cytokines, including IL-17, and can antagonize Th1 cells. Although Th17 cells have been shown to play a pathogenic role in immune-mediated diseases or a protective role in bacterial and fungal infections, their role in viral infections is unclear. Using newly established Th17-biased RORγt Tg mice, we tested whether Th17 cells could play a pathogenic or protective role in TMEV-IDD by contributing to immunopathology and/or by modulating anti-viral Th1 immune responses. While TMEV-infected wild-type littermate C57BL/6 mice are resistant to TMEV-IDD, RORγt Tg mice developed inflammatory demyelinating lesions with virus persistence in the spinal cord. TMEV-infected RORγt Tg mice had higher levels of IL-17, lower levels of interferon-γ, and fewer CD8(+) T cells, without alteration in overall levels of anti-viral lymphoproliferative and antibody responses, compared with TMEV-infected wild-type mice. This suggests that a Th17-biased "gain-of-function" mutation could increase susceptibility to virus-mediated demyelinating diseases.