Neuregulin1/ErbB4-induced migration in ST14A striatal progenitors: calcium-dependent mechanisms and modulation by NMDA receptor activation

<p>Abstract</p> <p>Background</p> <p>A number of studies have separately shown that the neuregulin1 (NRG1)/ErbB4 system and NMDA-type glutamate receptors (NMDARs) are involved in several aspects of neuronal migration. In addition, intracellular calcium fluctuations play central roles in neuronal motility. Stable expression of the tyrosine kinase receptor ErbB4 promotes migratory activity in the neural progenitor cell line ST14A upon NRG1 stimulation. In this work we analyzed the potential interactions between the NRG1/ErbB4 system and NMDARs in the ST14A migratory process as well as its calcium dependence.</p> <p>Results</p> <p>RT-PCR studies have shown that both native ST14A cells (non-expressing ErbB4), as well as ErbB4-transfected cells express low levels of a restricted number of NMDAR subunits: NR1, NR2C, NR2D and NR3B. The resulting NMDAR would form Ca²⁺channels characterized by low Mg²⁺-sensitivity and low Ca²⁺-permeability, generating small, long-lasting currents. Ca²⁺-imaging experiments showed slow [Ca²⁺]_iincreases in 45% of the cells following 8 μM NMDA stimulation. Basal migration of ErbB4-transfected ST14A cells was unaffected by 18 hrs NMDA incubation. However, over the same incubation time, NMDA was able to significantly enhance NRG1-induced migration. Pre-incubation with the intracellular calcium chelator BAPTA-AM reduced both NRG1- and NRG1/NMDA-stimulated migration, suggesting the involvement of Ca²⁺in these processes. NRG1 stimulation of ErbB4-transfected ST14A cells induced a sustained, long-lasting increase in [Ca²⁺]_i, in 99% of the cells. These intracellular Ca²⁺signals could be ascribed to both release from intracellular stores and influx from the extracellular medium trough a mechanism of store-operated calcium entry (SOCE). Short-time co-incubation of NMDA and NRG1 did not substantially modify the NRG1-induced intracellular calcium signals.</p> <p>Conclusions</p> <p>In summary, NRG1 stimulation of the ErbB4 receptor exerts a sustained [Ca²⁺]_iincrease in ST14A neural progenitors; NRG1-induced migration is Ca²⁺-dependent and can be positively modulated by activation of the NMDA receptor.</p

Mitral Valve Systolic Anterior Motion in Robotic Thoracic Surgery as the Cause of Unexplained Hemodynamic Shock: From a Case Report to Recommendations

Robotic major lung resection for lung cancer carries a risk for intraoperative hemodynamic instability. Systolic anterior motion (SAM) of the mitral valve is a rare and often misrecognized cause of intraoperative hemodynamic instability. If not promptly recognized, SAM leads to a complicated perioperative course. Here, we report for the first time a case of a patient with SAM with a severe degree of left ventricular outflow obstruction (LVOTO) undergoing robotic lung lobectomy and its challenging intraoperative management. A 70-year-old man undergoing robotic left upper lobectomy developed immediately after the induction of general anesthesia hemodynamic instability due to SAM-related LVOTO. The diagnosis was possible, thanks to the use of transesophageal echocardiography (TEE). The treatment strategies applied were preload optimization without fluid overload, ultra-short-acting beta-blockers, and vasopressors. Peripheral nerve blockades were preferred over epidural analgesia to avoid vasodilatation. The patient reported a good quality of recovery and no pain the day after surgery. The management of patients with higher risk of SAM and LVOTO development during robotic thoracic surgery requires a dedicated and skilled team together with high-impact treatment strategies driven by TEE. Since current guidelines do not recommend the use of TEE, even for patients with higher cardiac risk undergoing noncardiac surgery, the present case report may stimulate interest in future recommendations

Overweight: A Protective Factor against Comorbidity in the Elderly

The aim of this study was to investigate the relationship between body mass index (BMI) categories and comorbidity in 9067 patients (age range 18‒94 years) who underwent upper digestive endoscopy in Northern Sardinia, Italy. The majority of participants (62.2%) had a BMI under 25 kg/m2, overweight was detected in 30.4%, and obesity (BMI ≥ 30 kg/m2) in 7.4% of patients. The most frequent illness recorded was hypertension followed by cardiovascular and liver disease. The multivariate analysis, after adjusting for sex, residence, marital status, smoking habits, occupation and hospitalization detected an association between comorbidity and aging that was statistically significant and progressive. Among patients younger than 60 years (n = 5612) the comorbidity risk was higher for BMI ranging 27.5‒29.9 kg/m2 compared with BMI 25.0‒27.4 kg/m2 (RR = 1.38; 95% CI 1.27‒1.50 vs. RR = 0.86; 95% CI 0.81‒0.90). In patients older than 60 years (n= 3455) the risk was lower for a BMI in the range 27.5–29.9 kg/m2 compared with a BMI in the range 25.0–27.4 kg/m2 (RR = 1.11; 95% CI 1.05‒1.18 vs. RR = 1.28; 95% CI 1.21‒1.35). These results suggest that being moderately overweight is a marker of a healthy aging process and might protect, at least in part, against comorbidity. However, further research is needed to better understand this unexpected finding

Hampered long-term depression and thin spine loss in the nucleus accumbens of ethanol-dependent rats

Alcoholism involves long-term cognitive deficits, including memory impairment, resulting in substantial cost to society. Neuronal refinement and stabilization are hypothesized to confer resilience to poor decision making and addictive-like behaviors, such as excessive ethanol drinking and dependence. Accordingly, structural abnormalities are likely to contribute to synaptic dysfunctions that occur from suddenly ceasing the use of alcohol after chronic ingestion. Here we show that ethanol-dependent rats display a loss of dendritic spines in medium spiny neurons of the nucleus accumbens (Nacc) shell, accompanied by a reduction of tyrosine hydroxylase immunostaining and postsynaptic density 95-positive elements. Further analysis indicates that &#8220;long thin&#8221; but not &#8220;mushroom&#8221; spines are selectively affected. In addition, patch-clamp experiments from Nacc slices reveal that long-term depression (LTD) formation is hampered, with parallel changes in field potential recordings and reductions in NMDA-mediated synaptic currents. These changes are restricted to the withdrawal phase of ethanol dependence, suggesting their relevance in the genesis of signs and/or symptoms affecting ethanol withdrawal and thus the whole addictive cycle. Overall, these results highlight the key role of dynamic alterations in dendritic spines and their presynaptic afferents in the evolution of alcohol dependence. Furthermore, they suggest that the selective loss of long thin spines together with a reduced NMDA receptor function may affect learning. Disruption of this LTD could contribute to the rigid emotional and motivational state observed in alcohol dependence

Hampered long-term depression and thin spine loss in the nucleus accumbens of ethanol-dependent rats

Alcoholism involves long-term cognitive deficits, including memory impairment, resulting in substantial cost to society. Neuronal refinement and stabilization are hypothesized to confer resilience to poor decision making and addictive-like behaviors, such as excessive ethanol drinking and dependence. Accordingly, structural abnormalities are likely to contribute to synaptic dysfunctions that occur from suddenly ceasing the use of alcohol after chronic ingestion. Here we show that ethanol-dependent rats display a loss of dendritic spines in medium spiny neurons of the nucleus accumbens (Nacc) shell, accompanied by a reduction of tyrosine hydroxylase immunostaining and postsynaptic density 95-positive elements. Further analysis indicates that "long thin" but not "mushroom" spines are selectively affected. In addition, patch-clamp experiments from Nacc slices reveal that long-term depression (LTD) formation is hampered, with parallel changes in field potential recordings and reductions in NMDA-mediated synaptic currents. These changes are restricted to the withdrawal phase of ethanol dependence, suggesting their relevance in the genesis of signs and/or symptoms affecting ethanol withdrawal and thus the whole addictive cycle. Overall, these results highlight the key role of dynamic alterations in dendritic spines and their presynaptic afferents in the evolution of alcohol dependence. Furthermore, they suggest that the selective loss of long thin spines together with a reduced NMDA receptor function may affect learning. Disruption of this LTD could contribute to the rigid emotional and motivational state observed in alcohol dependence

Torsade de pointes: an unknown complication of hypertensive encephalopathy

Non ha abstract. E' una lettera all'Editore