Car accident as a trigger for reverse takotsubo-like cardiomyopathy with paraganglioma: Case report and literature review.

Paraganglioma (PGL), which may cause acute Takotsubo-like cardiomyopathy (TLC), is a rare neuroendocrine neoplasm derived from various body sites. TLC has been associated with excessive catecholamine secretion and shares the same cardiac presentation with Takotsubo cardiomyopathy (TTC). We present the case of a 58-year-old male who arrived at the hospital after a car accident, reporting symptoms of chest tightness, shortness of breath, and abdominal pain after a car accident. The patient was found to have elevated troponin and severely depressed left ventricular function. Echocardiography depicted a normal contracting apex with the rest of the left ventricle being hypokinetic. Coronary computed tomography (CT) angiogram revealed mild coronary artery disease. Abdominal CT further revealed a mass on the left side of the epigastric aorta, confirmed by autopsy as a PGL.

Sonic hedgehog is a regulator of extracellular glutamate levels and epilepsy.

Sonic hedgehog (Shh), both as a mitogen and as a morphogen, plays an important role in cell proliferation and differentiation during early development. Here, we show that Shh inhibits glutamate transporter activities in neurons, rapidly enhances extracellular glutamate levels, and affects the development of epilepsy. Shh is quickly released in response to epileptic, but not physiological, stimuli. Inhibition of neuronal glutamate transporters by Shh depends on heterotrimeric G protein subunit Gαi and enhances extracellular glutamate levels. Inhibiting Shh signaling greatly reduces epileptiform activities in both cell cultures and hippocampal slices. Moreover, pharmacological or genetic inhibition of Shh signaling markedly suppresses epileptic phenotypes in kindling or pilocarpine models. Our results suggest that Shh contributes to the development of epilepsy and suppression of its signaling prevents the development of the disease. Thus, Shh can act as a modulator of neuronal activity, rapidly regulating glutamate levels and promoting epilepsy.

Imaging characteristics and treatment strategies for carotid artery occlusion caused by skull base fracture: Three case reports.

BACKGROUND: Traumatic internal carotid artery (ICA) occlusion is a rare complication of skull base fractures, characterized by high mortality and disability rates, and poor prognosis. Therefore, timely discovery and correct management are crucial for saving the lives of such patients and improving their prognosis. This article retrospectively analyzed the imaging and clinical data of three patients, to explore the imaging characteristics and treatment strategies for carotid artery occlusion, combined with severe skull base fractures. CASE SUMMARY: This case included three patients, all male, aged 21, 63, and 16 years. They underwent plain film skull computed tomography (CT) examination at the onset of their illnesses, which revealed fractures at the bases of their skulls. Ultimately, these cases were definitively diagnosed through CT angiography (CTA) examinations. The first patient did not receive surgical treatment, only anticoagulation therapy, and recovered smoothly with no residual limb dysfunction (Case 1). The other two patients both developed intracranial hypertension and underwent decompressive craniectomy. One of these patients had high intracranial pressure and significant brain swelling postoperatively, leading the family to choose to take him home (Case 2). The other patient also underwent decompressive craniectomy and recovered well postoperatively with only mild limb motor dysfunction (Case 3). We retrieved literature from PubMed on skull base fractures causing ICA occlusion to determine the imaging characteristics and treatment strategies for this type of disease. CONCLUSION: For patients with cranial trauma combined with skull base fractures, it is essential to complete a CTA examination as soon as possible, to screen for blunt cerebrovascular injury.

ECMO management for severe pulmonary embolism with concurrent cerebral hemorrhage: a case report.

Background: Acute pulmonary embolism (APE) is a common and potentially fatal cardiovascular disease that can lead to sudden cardiac arrest in severe cases. When conventional cardiopulmonary resuscitation measures fail to achieve the return of spontaneous circulation (ROSC) in patients with APE, venoarterial extracorporeal membrane oxygenation (ECMO) becomes a viable therapeutic option. As an advanced life support treatment, ECMO ensures the perfusion of critical organs, providing sufficient time for interventions necessary for ROSC. Case introduction: We report the case of a patient who experienced cardiac arrest due to pulmonary embolism. During the treatment, the patient received two sessions of external cardiopulmonary resuscitation (ECPR) as supportive care and experienced cerebral hemorrhage. Ultimately, the patient improved and was discharged following support from extracorporeal membrane oxygenation (ECMO), careful anticoagulation strategies, and intervention with balloon pulmonary angioplasty. Conclusion: ECMO can serve as an important life support technology for patients with severe APE. Through a cautious anticoagulation therapy, not only was the ECMO support successfully maintained but also was further deterioration of cerebral hemorrhage effectively prevented. For patients with concurrent main pulmonary artery embolism and bleeding, balloon pulmonary angioplasty may be an option.

TRPC5 channel is the mediator of neurotrophin-3 in regulating dendritic growth via CaMKIIα in rat hippocampal neurons.

Neurotrophin-3 (NT-3) plays numerous important roles in the CNS and the elevation of intracellular Ca(2+) ([Ca(2+)](i)) is critical for these functions of NT-3. However, the mechanism by which NT-3 induces [Ca(2+)](i) elevation remains largely unknown. Here, we found that transient receptor potential canonical (TRPC) 5 protein and TrkC, the NT-3 receptor, exhibited a similar temporal expression in rat hippocampus and cellular colocalization in hippocampal neurons. Stimulation of the neurons by NT-3 induced a nonselective cation conductance and PLCγ-dependent [Ca(2+)](i) elevation, which were both blocked when TRPC5, but not TRPC6 channels, were inhibited. Moreover, the Ca(2+) influx through TRPC5 induced by NT-3 inhibited the neuronal dendritic growth through activation of calmodulin-dependent kinase (CaMK) IIα. In contrast, the Ca(2+) influx through TRPC6 induced by NT-4 promoted the dendritic growth. Thus, TRPC5 acts as a novel and specific mediator for NT-3 to regulate dendrite development through CaMKIIα.

Critical role of TRPC6 channels in the formation of excitatory synapses.

The transient receptor potential canonical (TRPC) channels are Ca2+-permeable, nonselective cation channels with different biological functions, but their roles in brain are largely unknown. Here we report that TRPC6 was localized to excitatory synapses and promoted their formation via a CaMKIV-CREB-dependent pathway. TRPC6 transgenic mice showed enhancement in spine formation, and spatial learning and memory in Morris water maze. These results reveal a previously unknown role of TRPC6 in synaptic and behavioral plasticity.

WITHDRAWN: Adenoviral gene delivery can convert adult human fibroblasts to neurons.

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The Kv2.1 channels mediate neuronal apoptosis induced by excitotoxicity.

Chronic loss of intracellular K(+) can induce neuronal apoptosis in pathological conditions. However, the mechanism by which the K(+) channels are regulated in this process remains largely unknown. Here, we report that the increased membrane expression of Kv2.1 proteins in cortical neurons deprived of serum, a condition known to induce K(+) loss, promotes neuronal apoptosis. The increase in I(K) current density and apoptosis in the neurons deprived of serum were inhibited by a dominant negative form of Kv2.1 and MK801, an antagonist to NMDA receptors. The membrane level of Kv2.1 and its interaction with SNAP25 were increased, whereas the Kv2.1 phosphorylation was inhibited in the neurons deprived of serum. Botulinum neurotoxin, an agent known to prevent formation of soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex, suppressed the increase in I(K) current density. Together, these results suggest that NMDA receptor-dependent Kv2.1 membrane translocation is regulated by a soluble N-ethylmaleimide-sensitive factor attachment protein receptor-dependent vesicular trafficking mechanism and is responsible for neuronal cell death induced by chronic loss of K(+).

Blockade of TRPC6 channels induced G2/M phase arrest and suppressed growth in human gastric cancer cells.

Channels formed by the canonical transient receptor potential (TRPC) subfamily of proteins are Ca(2+)-permeable, nonselective cation channels with various functions. Through a phospholipase C (PLC)-dependent mechanism TRPC6, a member of TRPC subfamily, can be activated by receptor tyrosine kinases (RTK) or G protein-coupled receptors (GPCR), which are implicated in cell proliferation and human malignancies. Here, we report that TRPC6 has a critical role in human gastric cancer development. Expression of TRPC6 was greatly upregulated in human gastric cancer epithelial cells compared with that in normal gastric epithelial cells. Treatment of AGS or MKN45 cells, human gastric cancer cell lines, with SKF96365, an agent known to inhibit TRPC channels, arrested cell cycle in G2/M phase and suppressed cell growth. Importantly, expressing a dominant negative mutant of TRPC6 (DNC6) in these cells also arrested cell cycle in G2/M phase and inhibited cell growth. The Ca(2+) elevation in the MKN45 cells evoked by histamine was inhibited by SKF96365 and DNC6. Moreover, inhibition of TRPC6 suppressed the formation of gastric tumors in nude mice. These results suggest that Ca(2+) elevation regulated by TRPC6 channels is essential for G2/M phase transition and for the development of gastric cancers.

The Kv4.2 mediates excitatory activity-dependent regulation of neuronal excitability in rat cortical neurons.

Neuronal excitability can cooperate with synaptic transmission to control the information storage. This regulation of neuronal plasticity can be affected by alterations in neuronal inputs and accomplished by modulation of voltage-dependent ion channels. In this study, we report that enhanced excitatory input negatively regulated neuronal excitability. Enhanced excitatory input by glutamate, electric field stimulation or high K+ increased transient outward K+ current, whereas did not affect the delayed rectifier K+ current in rat cultured cortical neurons. Both the voltage-dependent K+ channel 4.2 and 4.3 subunits contributed to the increase. The increase in the K+ current density by Kv4.2 was ascribed to its cytoplasmic membrane translocation, which was mediated by NMDA type of glutamate receptor. Furthermore, enhanced excitatory input inhibited neuronal excitability. Taken together, our results suggest that excitatory neurotransmission affects neuronal excitability via the regulation of the K+ channel membrane translocation.

Neuronal transcription factors induce conversion of human glioma cells to neurons and inhibit tumorigenesis.

Recent findings have demonstrated that the overexpression of lineage-specific transcription factors induces cell fate changes among diverse cell types. For example, neurons can be generated from mouse and human fibroblasts. It is well known that neurons are terminally differentiated cells that do not divide. Therefore, we consider how to induce glioma cells to become neurons by introducing transcription factors. Here, we describe the efficient generation of induced neuronal (iN) cells from glioma cells by the infection with three transcription factors: Ascl1, Brn2 and Ngn2 (ABN). iN cells expressed multiple neuronal markers and fired action potentials, similar to the properties of authentic neurons. Importantly, the proliferation of glioma cells following ABN overexpression was dramatically inhibited in both in vitro and in vivo experiments. In addition, iN cells that originated from human glioma cells did not continue to grow when they were sorted and cultured in vitro. The strategies by which glioma cells are induced to become neurons may be used to clinically study methods for inhibiting tumor growth.

Inhibition of TRPC6 degradation suppresses ischemic brain damage in rats.

Brain injury after focal cerebral ischemia, the most common cause of stroke, develops from a series of pathological processes, including excitotoxicity, inflammation, and apoptosis. While NMDA receptors have been implicated in excitotoxicity, attempts to prevent ischemic brain damage by blocking NMDA receptors have been disappointing. Disruption of neuroprotective pathways may be another avenue responsible for ischemic damage, and thus preservation of neuronal survival may be important for prevention of ischemic brain injury. Here, we report that suppression of proteolytic degradation of transient receptor potential canonical 6 (TRPC6) prevented ischemic neuronal cell death in a rat model of stroke. The TRPC6 protein level in neurons was greatly reduced in ischemia via NMDA receptor-dependent calpain proteolysis of the N-terminal domain of TRPC6 at Lys¹6. This downregulation was specific for TRPC6 and preceded neuronal death. In a rat model of ischemia, activating TRPC6 prevented neuronal death, while blocking TRPC6 increased sensitivity to ischemia. A fusion peptide derived from the calpain cleavage site in TRPC6 inhibited degradation of TRPC6, reduced infarct size, and improved behavioral performance measures via the cAMP response element-binding protein (CREB) signaling pathway. Thus, TRPC6 proteolysis contributed to ischemic neuronal cell death, and suppression of its degradation preserved neuronal survival and prevented ischemic brain damage.

Essential role of TRPC6 channels in G2/M phase transition and development of human glioma.

BACKGROUND: Patients with glioblastoma multiforme, the most aggressive form of glioma, have a median survival of approximately 12 months. Calcium (Ca(2+)) signaling plays an important role in cell proliferation, and some members of the Ca(2+)-permeable transient receptor potential canonical (TRPC) family of channel proteins have demonstrated a role in the proliferation of many types of cancer cells. In this study, we investigated the role of TRPC6 in cell cycle progression and in the development of human glioma. METHODS: TRPC6 protein and mRNA expression were assessed in glioma (n = 33) and normal (n = 17) brain tissues from patients and in human glioma cell lines U251, U87, and T98G. Activation of TRPC6 channels was tested by platelet-derived growth factor-induced Ca(2+) imaging. The effect of inhibiting TRPC6 activity or expression using the dominant-negative mutant TRPC6 (DNC6) or RNA interference, respectively, was tested on cell growth, cell cycle progression, radiosensitization of glioma cells, and development of xenografted human gliomas in a mouse model. The green fluorescent protein (GFP) and wild-type TRPC6 (WTC6) were used as controls. Survival of mice bearing xenografted tumors in the GFP, DNC6, and WTC6 groups (n = 13, 15, and 13, respectively) was compared using Kaplan-Meier analysis. All statistical tests were two-sided. RESULTS: Functional TRPC6 was overexpressed in human glioma cells. Inhibition of TRPC6 activity or expression attenuated the increase in intracellular Ca(2+) by platelet-derived growth factor, suppressed cell growth and clonogenic ability, induced cell cycle arrest at the G2/M phase, and enhanced the antiproliferative effect of ionizing radiation. Cyclin-dependent kinase 1 activation and cell division cycle 25 homolog C expression regulated the cell cycle arrest. Inhibition of TRPC6 activity also reduced tumor volume in a subcutaneous mouse model of xenografted human tumors (P = .014 vs GFP; P < .001 vs WTC6) and increased mean survival in mice in an intracranial model (P < .001 vs GFP or WTC6). CONCLUSIONS: In this preclinical model, TRPC6 channels were essential for glioma development via regulation of G2/M phase transition. This study suggests that TRPC6 might be a new target for therapeutic intervention of human glioma.

Critical role of TRPC6 channels in VEGF-mediated angiogenesis.

Intracellular Ca(2+) signaling plays critical roles in VEGF-mediated angiogenesis. Transient receptor potential canonical (TRPC) channel 6, a Ca(2+)-permeable non-selective cation channel, can be activated by VEGF. Here, we report that TRPC6 is important for VEGF-mediated angiogenesis. Inhibition of TRPC6 in human umbilical vein endothelial cells (HUVECs) by pharmacological or genetic approaches arrested HUVECs at G2/M phase and suppressed VEGF-induced HUVEC proliferation and tube formation. Furthermore, inhibition of TRPCs abolished VEGF-, but not FGF-induced angiogenesis in the chick embryo chorioallantoic membrane. These results suggest that TRPC6 plays an important role in VEGF-mediated angiogenesis.

[Interaction of 5-HT2 and 5-HT3 receptor subtype in 5-HT-induced nociceptive responses in peripheral primary sensory nerve ending].

AIM: To study the correlation between 5-HT-induced pain response and the contribution by individual 5-HTR subtypes including 5-HT1R, 5-HT2R and 5-HT3R at the level of peripheral primary afferent. METHODS: The experiments were done on acutely isolated trigeminal ganglion (TG) neurons using whole-cell patch clamp technique and the nociceptive effect was observed on behavior experiments by intraplantar injection of test drugs. RESULTS: The majority of cells examined responded to 5-HT in a manner of concentration dependence (10(-6) - 10(-3) mol/) (61.4%, 54/88) and with a fast activating and rapid desensitizing inward current (I(5-HT)), which was thought to be mediated by the activation of 5-HT3R, since it could be blocked by 5-HT3R antagonist ICS 205930 and mimicked by 5-HT3R agonist 2-methyl-5-HT. It was found that I(5-HT) was potentiated by 5-HT2R agonist alpha-methyl-5-HT markedly, while 5-HT1R agonist R-(+)-UH 301 did not. In behavioral experiment performed on conscious rats, intraplantar injection of 5-HT(10(-5), 10(-4) and 10(-3) mol/L) induced an increment of cumulative lifting time first 20 min in a manner of concentration dependence. By dissociating 5-HTR subtypes using their corresponding antagonists (ICS and CYP) the potency order of hindpaw lifting time was identified as follows: 5-HT > 5-HT + ICS > 5-HT + CYP. CONCLUSION: The results suggest that in 5-HT-induced nociceptive response at the primary sensory level 5-HT3R may play a role of initiation, but 5-HT2R mediates maintaining and modulatory effect in the processes of nociceptive information convey.