An Unexpected Cause of Syncope.

Syncope is a common chief complaint among patients presenting to the emergency department, the etiology of which can often be discerned with a thorough history and physical examination. Inversely, liposarcomas are rare tumors that frequently pose a diagnostic challenge as the clinical presentation is highly nonspecific and varies greatly depending on the anatomic location and size of the tumor. Here we present a case of retroperitoneal liposarcomas (RLS) presenting to the emergency department (ED) with a sole complaint of syncope, resulting in a diagnostic dilemma. This clinical scenario highlights the significance of thorough physical examination regardless of the presenting chief complaint, as unexpected physical examination findings prompted an extended work-up and thus facilitated the diagnosis, providing the opportunity for early intervention and resection of the tumor.

Non-aromatic Anticonvulsant (Divalproex Sodium)-Induced Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS) Syndrome.

A wide array of commonly prescribed antiepileptic medications, antibiotics, antivirals, anti-parasitic, and antihyperuricemic can cause Drug Reaction Eosinophilia and Systemic Syndrome (DRESS)- a drug induced hypersensitivity reaction characterized by cutaneous manifestation, fever, eosinophilia, thrombocytopenia and one or more visceral organ involvement. The rare occurrence in clinical settings and wide variety of clinical presentations make DRESS a diagnostically challenging case. A vast majority of DRESS cases are attributed to the most commonly prescribed anticonvulsant medications - phenytoin and carbamazepines. Even though non-aromatic divalproex sodium/valproic acid (VPA) can cause life-threatening fatal hypersensitivity reactions on rare occasions, a handful cases of valproate-induced DRESS have been reported. We hereby report a case of a 57-year-old cognitively impaired person with polypharmacy who presented with worsening diffuse skin rash, fever, dysphagia, eosinophilia, thrombocytopenia, and mixed type of hepatic injury. The patient was eventually diagnosed with DRESS due to divalproex sodium- an anticonvulsant medication. The objective of our report is to identify and recognize the rare yet proper causative agent that induces DRESS and potential mitigation of significant systemic consequences by its subsequent withdrawal.

Partial Fanconi Syndrome Induced by Ifosfamide.

Several commonly used chemotherapeutic agents, antibiotics, antivirals, and antiepileptic medications can cause partial or full Fanconi syndrome, disorders which can generally be described as transport defects in the proximal renal tubule, associated with non-anion gap metabolic acidosis. Fanconi syndrome is underreported and therefore often missed in the clinical setting. Herein, we present a case report that details the course of a 64-year-old female with a history of stage IV undifferentiated pleomorphic sarcoma who after her sixth chemotherapeutic cycle (adriamycin, ifosfamide, and mesna) developed severe hypokalemia, hypophosphatemia, and proteinuria without glycosuria, eventually diagnosed with partial Fanconi syndrome. The aim of this report is to highlight the importance of routine serum and urine monitoring in patients undergoing therapy with potentially nephrotoxic agents to avoid potentially fatal renal nephrotoxicity, including partial and full Fanconi syndrome.

Single-molecule tracking of small GTPase Rac1 uncovers spatial regulation of membrane translocation and mechanism for polarized signaling.

Polarized Rac1 signaling is a hallmark of many cellular functions, including cell adhesion, motility, and cell division. The two steps of Rac1 activation are its translocation to the plasma membrane and the exchange of nucleotide from GDP to GTP. It is, however, unclear whether these two processes are regulated independent of each other and what their respective roles are in polarization of Rac1 signaling. We designed a single-particle tracking (SPT) method to quantitatively analyze the kinetics of Rac1 membrane translocation in living cells. We found that the rate of Rac1 translocation was significantly elevated in protrusions during cell spreading on collagen. Furthermore, combining FRET sensor imaging with SPT measurements in the same cell, the recruitment of Rac1 was found to be polarized to an extent similar to that of the nucleotide exchange process. Statistical analysis of single-molecule trajectories and optogenetic manipulation of membrane lipids revealed that Rac1 membrane translocation precedes nucleotide exchange, and is governed primarily by interactions with phospholipids, particularly PI(3,4,5)P3, instead of protein factors. Overall, the study highlights the significance of membrane translocation in spatial Rac1 signaling, which is in addition to the traditional view focusing primarily on GEF distribution and exchange reaction.

Japanese encephalitis virus-infected macrophages induce neuronal death.

Inflammation in the central nervous system (CNS) in Japanese encephalitis (JE) is shown to be the result of microglial activation that leads to the release of various proinflammatory mediators. Peripheral macrophages have been reported to infiltrate into the CNS in JE, though their contribution to the inflammatory process is yet to be elucidated. In this study, using an in vitro macrophage model, we have shown that upon JE virus infection, these cells secrete various soluble factors which may significantly add to the existing inflammatory milieu and lead to apoptotic or necrotic death of neurons. However, it is difficult to quantify the extent of involvement of either the microglia or infiltrating macrophages in the inflammatory processes.

Critical role of lipid rafts in virus entry and activation of phosphoinositide 3' kinase/Akt signaling during early stages of Japanese encephalitis virus infection in neural stem/progenitor cells.

Japanese encephalitis virus (JEV), the leading cause of acute encephalitis in South-East Asia is a neurotropic virus infecting various CNS cell types. Most Flaviviruses including JEV get internalised into cells by receptor-mediated endocytosis, which involve clathrin and membrane cholesterol. The cholesterol-enriched membrane microdomains referred to as lipid rafts act as portals for virus entry in a number of enveloped viruses, including Flavivirus. However, the precise role played by membrane lipid rafts in JEV internalisation into neural stem cells is still unknown. We have established neural stem/progenitor cells and C17.2 cell line as models of productive JEV infection. Increase in membrane fluidity and clustering of viral envelope proteins in lipid rafts was observed in early time points of infection. Localisation of non-structural proteins to rafts at later infection stages was also observed. Co-localisation of JEV glycoprotein with Cholera toxin B confirmed that JEV internalisation occurs in a lipid-raft dependent manner. Though JEV entry is raft dependent, however, there is requirement of functional clathrin during endocytosis inside the cells. Besides virus entry, the lipid rafts act as signalling platforms for Src tyrosine kinases and result in activation of phosphoinositìde 3'-kinase/Akt signalling during early JEV infection. Disruption of lipid raft formation by cholesterol depletion using Methyl ß-cyclodextrin, reduced JEV RNA levels and production of infectious virus particles as well as impaired phosphoinositìde 3'-kinase/Akt signalling during initial infection. Overall, our results implicate the importance of host membrane lipid rafts in JEV entry and life cycle, besides maintaining survival of neural stem/progenitor cells during early infection.

Japanese encephalitis virus induce immuno-competency in neural stem/progenitor cells.

BACKGROUND: The low immunogenicity of neural stem/progenitor cells (NSPCs) coupled with negligible expression of MHC antigens has popularized their use in transplantation medicine. However, in an inflammatory environment, the NSPCs express costimulatory molecules and MHC antigens, and also exhibit certain immunomodulatory functions. Since NSPCs are the cellular targets in a number of virus infections both during postnatal and adult stages, we wanted to investigate the immunological properties of these stem cells in response to viral pathogen. METHODOLOGY/PRINCIPAL FINDINGS: We utilized both in vivo mouse model and in vitro neurosphere model of Japanese encephalitis virus (JEV) infection for the study. The NSPCs residing in the subventricular zone of the infected brains showed prominent expression of MHC-I and costimulatory molecules CD40, CD80, and CD86. Using Flow cytometry and fluorescence microscopy, we observed increased surface expression of co-stimulatory molecule and MHC class I antigen in NSPCs upon progressive JEV infection in vitro. Moreover, significant production of pro-inflammatory cyto/chemokines was detected in JEV infected NSPCs by Cytokine Bead Array analysis. Interestingly, NSPCs were capable of providing functional costimulation to allogenic T cells and JEV infection resulted in increased proliferation of allogenic T cells, as detected by Mixed Lymphocyte reaction and CFSE experiments. We also report IL-2 production by NSPCs upon JEV infection, which possibly provides mitogenic signals to T cells and trigger their proliferation. CONCLUSION/SIGNIFICANCE: The in vivo and in vitro findings clearly indicate the development of immunogenicity in NSPCs following progressive JEV infection, in our case, JEV infection. Following a neurotropic virus infection, NSPCs possibly behave as immunogenic cells and contribute to both the innate and adaptive immune axes. The newly discovered immunological properties of NSPCs may have implications in assigning a new role of these cells as non-professional antigen presenting cells in the central nervous system.

Tobacco carcinogen induces microglial activation and subsequent neuronal damage.

4-Methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) is a tobacco-specific procarcinogen. We have investigated whether NNK causes inflammatory upheaval in the brain by activation of resident microglia and astrocyte and result in bystander neuronal damage. We have carried out the work in both in vitro and in vivo models. We have found that treatment with NNK causes significant activation of mouse microglial (BV2) cell line as evident by increase in reactive oxygen species and nitric oxide level. Western blot analysis has showed increase in proinflammatory signaling proteins, proinflammatory effector proteins, and other stress-related proteins. Interestingly, increased levels of proinflammatory cytokines like interleukin (IL)-6, tumor necrosis factor-alpha, monocyte chemoattractant protein 1 (MCP1), and IL-12p70 are also detected. Work from our in vivo studies has demonstrated similar increase in proinflammatory signaling and effector molecules along with the proinflammatory cytokine levels, following NNK treatment. Immunohistochemical staining of the brain sections of NNK-treated mice reveals massive microglial and astrocyte activation along with distinct foci of neuronal damage. Both in vitro and in vivo results provide strong indication that NNK causes significant upheaval of the inflammatory condition of brain and inflicts subsequent neuronal damage.

Therapeutic effect of a novel anilidoquinoline derivative, 2-(2-methyl-quinoline-4ylamino)-N-(2-chlorophenyl)-acetamide, in Japanese encephalitis: correlation with in vitro neuroprotection.

2-(2-Methyl-quinoline-4ylamino)-N-(2-chlorophenyl)-acetamide, a novel anilidoquinoline derivative, was synthesised and evaluated for its therapeutic efficacy in treating Japanese encephalitis. The compound showed significant antiviral and antiapoptotic effects in vitro. Significant decreases in viral load (P<0.01) combined with an increase in survival was observed in Japanese encephalitis virus-infected mice treated with 2-(2-methyl-quinoline-4ylamino)-N-(2-chlorophenyl)-acetamide.

Japanese encephalitis virus infects neural progenitor cells and decreases their proliferation.

Japanese encephalitis virus (JEV), a common cause of encephalitis in humans, especially in children, leads to substantial neuronal injury. The survivors of JEV infection have severe cognitive impairment, motor and behavioral disorders. We hypothesize that depletion of neural progenitor cells (NPCs) by the virus culminates in neurological sequelae in survivors of Japanese encephalitis (JE). We utilized both in vivo model of JEV infection and in vitro neurosphere cultures to study progressive JEV infection. Cellular infection and cell death was determined by flow cytometry. BrdU administration in animals and in neurospheres was used to determine the proliferative ability of NPCs. JEV leads to massive loss of actively proliferating NPC population from the subventricular zone (SVZ). The ability of JEV infected subventricular zone cells to form neurospheres is severely compromised. This can be attributed to JEV infection in NPCs, which however do not result in robust death of the resilient NPC cells. Instead, JEV suppresses the cycling ability of these cells, preventing their proliferation. JEV primarily targets at a critical postnatal age and severely diminishes the NPC pool in SVZ, thus impairing the process of recovery after the insult. This arrested growth and proliferation of NPCs might have an effect on the neurological consequences in JE survivors.

Tumor necrosis factor receptor-associated death domain mediated neuronal death contributes to the glial activation and subsequent neuroinflammation in Japanese encephalitis.

While a number of studies have documented the importance of microglia in central nervous system (CNS) response to injury, infection and in disease state, little is known regarding how the neuronal death initiates the cascades of secondary neuroinflammation. We have exploited an experimental model of Japanese encephalitis to better understand how neuronal death following viral infection initiates microglial activation following Japanese encephalitis virus infection. We have earlier shown that the altered expression of tumor necrosis factor receptor-1 (TNFR-1) and TNFR associated death domain (TRADD) following Japanese encephalitis virus infection regulates the downstream apoptotic cascades. Here we have reported that silencing TRADD expression with small-interfering RNA reduced neuronal apoptosis and subsequent microglial and astroglial activation and release of various pro-inflammatory mediators. Our findings suggest that the engagement of TNFR-1 and TRADD following Japanese encephalitis virus infection plays a crucial role in glial activation also and influences the outcome of viral pathogenesis.

Tumor necrosis factor receptor-1-induced neuronal death by TRADD contributes to the pathogenesis of Japanese encephalitis.

While a number of studies have documented the neurotropism of Japanese encephalitis virus (JEV), little is known regarding the molecular mechanism of neuronal death following viral infection. The tumor necrosis factor receptor (TNFR)-associated death domain (TRADD) has been suggested to be the crucial signal adaptor that mediates all intracellular responses from TNFR-1. Using mouse (Neuro2a) and human (SK-N-SH) neuroblastoma cell lines, we have shown that the altered expression of TNFR-1 and TRADD following JEV infection regulates the downstream apoptotic cascades. Activation of TRADD led to mitochondria-mediated neuronal apoptosis. As TRADD-knockout animals or deficient cell lines are unavailable, it has been difficult to definitively address the physiological role of TRADD in diseases pathology following JEV infection. We circumvented this problem by silencing TRADD expression with small-interfering RNA (siRNA) and have found that TRADD is required for TNFR-1-initiated neuronal apoptosis following in vitro infection with JEV. Interestingly, siRNA against TRADD also decreased the viral load in Neuro2a cells. Furthermore, siRNA against TRADD increased the survival of JEV-infected mice by altering the expression of pro apoptotic versus antiapoptotic molecules. These studies show that the engagement of TNFR-1 and TRADD following JEV infection plays a crucial role in neuronal apoptosis.