WNK kinase, ion channels and arachidonic acid metabolites choreographically execute endothelium-dependent vasodilation.

The smooth muscle-walled blood vessels control blood pressure. The vessel lumen is lined by an endothelial cell (ECs) layer, interconnected to the surrounding smooth muscle cells (SMCs) by myoendothelial gap junctions. Gap junctions also maintain homo-cellular ECs-ECs and SMCs-SMCs connections. This gap junction network nearly equalises both cells' membrane potential and cytosolic ionic composition, whether in resting or stimulated conditions. When acetylcholine (ACh) activates ECs M3 receptors, a complex signalling cascade involving second messengers and ion channels is triggered to induce vasodilation.

Insights into the function and regulation of the calcium-activated chloride channel TMEM16A.

The TMEM16A channel, a member of the TMEM16 protein family comprising chloride (Cl-) channels and lipid scramblases, is activated by the free intracellular Ca2+ increments produced by inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release after GqPCRs or Ca2+ entry through cationic channels. It is a ubiquitous transmembrane protein that participates in multiple physiological functions essential to mammals' lives. TMEM16A structure contains two identical 10-segment monomers joined at their transmembrane segment 10. Each monomer harbours one independent hourglass-shaped pore gated by Ca2+ ligation to an orthosteric site adjacent to the pore and controlled by two gates. The orthosteric site is created by assembling negatively charged glutamate side chains near the pore´s cytosolic end. When empty, this site generates an electrostatic barrier that controls channel rectification. In addition, an isoleucine-triad forms a hydrophobic gate at the boundary of the cytosolic vestibule and the inner side of the neck. When the cytosolic Ca2+ rises, one or two Ca2+ ions bind to the orthosteric site in a voltage (V)-dependent manner, thus neutralising the electrostatic barrier and triggering an allosteric gating mechanism propagating via transmembrane segment 6 to the hydrophobic gate. These coordinated events lead to pore opening, allowing the Cl- flux to ensure the physiological response. The Ca2+-dependent function of TMEM16A is highly regulated. Anions with higher permeability than Cl- facilitate V dependence by increasing the Ca2+ sensitivity, intracellular protons can replace Ca2+ and induce channel opening, and phosphatidylinositol 4,5-bisphosphate bound to four cytosolic sites likely maintains Ca2+ sensitivity. Additional regulation is afforded by cytosolic proteins, most likely by phosphorylation and protein-protein interaction mechanisms.

Surgical treatment of pituitary neuroendocrine tumors with coexisting intracranial lesions: A case series and review of the literature.

Background: Pituitary neuroendocrine tumors (PitNETs) are a diverse group of benign neoplasms that account for a significant proportion of intracranial tumors (13%). The coexistence of PitNET with other intracranial lesions, such as meningiomas and intracranial aneurysms, has been constantly reported in the literature; yet, the pathophysiological mechanisms remain unknown, and the appropriate management is controversial. This study aims to describe the clinical characteristics, surgical treatment, and outcomes of patients with PitNET with coexisting intracranial lesions in a single healthcare center. Methods: A retrospective analysis was conducted on 12 patients who underwent surgical treatment for PitNET and another intracranial lesion at our single tertiary referral center over 15 years from January 2008 to May 2023. Results: Among these coexisting lesions, aneurysms were the most commonly found (41.67%), followed by meningiomas (33.33%). Surgical intervention for both lesions was performed in a single-stage procedure for most cases (75%), employing transcranial, endoscopic endonasal, and combined approaches. We found low preoperative Karnofsky Performance Scale scores in three patients, with significant differences in functional outcomes. Conclusion: These findings contribute to the limited knowledge about PitNET coexisting with other intracranial lesions and emphasize the importance of patient-tailored, multidisciplinary management in these unusual scenarios.

Visual outcomes in tuberculum sellae meningiomas comparing transcranial and endoscopic endonasal approaches.

Background: Tuberculum sellae meningiomas (TSM) account for 3-10% of intracranial meningiomas. Visual loss is the presenting symptom in up to 80% of cases. Surgical management poses a great challenge due to tumor proximity to neurovascular structures such as the optic nerve and the internal carotid artery (ICA); hence, there is controversy regarding the optimal approach. The aim of this study is to determine differences in visual outcomes between transcranial (TCA) and endoscopic endonasal (EEA) approaches. Methods: A retrospective study including 29 patients with TSM surgically treated by TCA or EEA between 2011 and 2023 in a single referral center was conducted. Pre-and post-operative neuro-ophthalmologic evaluations, focusing on visual acuity and campimetry, were evaluated. Results: Sixteen (55.16%) patients were intervened through a TCA and the remaining 13 (44.84%) via an EEA. The lesions in each group were similar in terms of pre- operative volume (15.12 vs 12.9 cm3, p = 0.497) and neurovascular invasion (optic canal invasion 48.26 vs 41.37%, p = 0.664; ICA 44.81 vs 31.03%, p = 0.797). There were no significant differences in visual outcomes between both approaches; TCA presented an improvement of 5.18 points in visual fields (p = 0.140), whereas EEA had an improvement of 17.39 points in visual acuity (p = 0.114). Conclusion: EEA seems to offer greater improvement in visual acuity than TCA. However, the ideal approach should be individualized; taking into account the tumor's volume and invasiveness, as well as the patient's visual complaints.

Unilateral approach for bilateral clipping of posterior communicating artery aneurysms in a hybrid operating room: A technical note.

Bilateral posterior communicating (pComm) artery aneurysms represent only 2% of mirror intracranial aneurysms. Usually, these are surgically approached through bilateral craniotomies for clipping. We present the case of a 50-year-old female presenting with headache and horizontal diplopia. Neurological examination revealed a left oculomotor palsy, with no other neurological deficits. Imaging studies revealed bilateral aneurysmatic lesions in both internal carotid arteries (ICA). A conventional left pterional approach was planned in order to treat the symptomatic aneurysm, and, if deemed feasible, a contralateral clipping through the same approach. The procedure was performed in a hybrid operating room (HOR), performing an intraoperative digital subtraction angiography (DSA) and roadmapping assistance during dissection and clipping. Transoperatively, a post-fixed optic chiasm was identified, with a wide interoptic space, which allowed us to perform the contralateral clipping through a unilateral approach. This technique for clipping bilateral pComm aneurysms can be performed when the proper anatomical features are met.

Endoscopic Endonasal Approach in Craniopharyngiomas: Representative Cases and Technical Nuances for the Young Neurosurgeon.

Craniopharyngiomas (CPs) are Rathke's cleft-derived benign tumors originating most commonly in the dorsum sellae and representing 2% of intracranial neoplasms. CPs represent one of the more complex intracranial tumors due to their invasive nature, encasing neurovascular structures of the sellar and parasellar regions, making its resection a major challenge for the neurosurgeon with important postoperative morbidity. Nowadays, an endoscopic endonasal approach (EEA) provides an "easier" way for CPs resection allowing a direct route to the tumor with direct visualization of the surrounding structures, diminishing inadvertent injuries, and providing a better outcome for the patient. In this article, we include a comprehensive description of the EEA technique and nuances in CPs resection, including three illustrated clinical cases.

Phosphatidylinositol 4,5-Bisphosphate and Cholesterol Regulators of the Calcium-Activated Chloride Channels TMEM16A and TMEM16B.

Chloride fluxes through homo-dimeric calcium-activated channels TMEM16A and TMEM16B are critical to blood pressure, gastrointestinal motility, hormone, fluid and electrolyte secretion, pain sensation, sensory transduction, and neuronal and muscle excitability. Their gating depends on the voltage-dependent binding of two intracellular calcium ions to a high-affinity site formed by acidic residues from α-helices 6-8 in each monomer. Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a low-abundant lipid of the inner leaflet, supports TMEM16A function; it allows TMEM16A to evade the down-regulation induced by calcium, poly-L-lysine, or PI(4,5)P2 5-phosphatase. In stark contrast, adding or removing PI(4,5)P2 diminishes or increases TMEM16B function, respectively. PI(4,5)P2-binding sites on TMEM16A, and presumably on TMEM16B, are on the cytosolic side of α-helices 3-5, opposite the calcium-binding sites. This modular structure suggested that PI(4,5)P2 and calcium cooperate to maintain the conductive state in TMEM16A. Cholesterol, the second-largest constituent of the plasma membrane, also regulates TMEM16A though the mechanism, functional outcomes, binding site(s), and effects on TMEM16A and TMEM16B remain unknown.

Perioperative predictors for complications in patients with Xanthogranulomatous Pyelonephritis treated with nephrectomy.

INTRODUCTION: Xanthogranulomatous pyelonephritis is an inflammatory disease characterized by chronic obstruction and infection. This pathology is a life-threatening condition when surgical treatment is carried out. We decided to retrospectively evaluate whether there were perioperative factors that predict complications in patients who undergo nephrectomy. METHODS: We reviewed all nephrectomies done in the period of 2013-2018, in a tertiary referral Hospital with the histopathological diagnosis of Xanthogranulomatous Pyelonephritis. RESULTS: The presence of renal abscess at admission was observed as a risk factor associated with perioperative complications (p = 0.002), presence of abscess was observed in 47.4% of subjects without complications compared to 89.3% of the perioperative complication group. Higher rates of blood transfusion requirement were observed in the perioperative complication group, 89.3% compared to 68.4% (p = 0.029), furthermore, perioperative bleeding was slightly greater in the complication group compared to its counterpart, 700 mL, and 600 mL, respectively (p = 0.01). CONCLUSIONS: Anemia and the presence of abscess were important perioperative factors that predict perioperative complications.

Intra-aneurysmatic thrombectomy in a distal anterior cerebral artery aneurysm.

Thrombectomy procedures following intra-aneurysmatic lesions are extremely rare, and few cases have been reported. This article describes a microsurgical intra-aneurysmatic thrombectomy (MIaT) for a distal anterior cerebral artery (DACA) aneurysm. We present the case of a 48-year-old female that was admitted to the emergency room, showing neurologic deterioration with focal deficits. A computed tomography angiography (CTA) scan revealed an aneurysm located in the distal segment of the left anterior cerebral artery. During the surgical procedure, after clipping, a wellformed clot was visualized through the aneurysm's wall obstructing the left DACA flow. We proceeded to open the aneurysm's dome to remove the thrombus and clip the aneurysm neck, re-establishing the flow of the left DACA. Intra-aneurysmatic thrombosis can occur as a complication during clipping, obstructing the distal flow of vital arteries and causing fatal results in the patient's postoperative status. MIaT is a good technique for restoring the flow of the affected vessel and allows a secure aneurysm clipping after thrombus removal.

Magnetic resonance imaging finding of coexistence of bilateral paraclinoid aneurysms in a patient with a nonfunctioning macroadenoma, simultaneous resection, and clipping: illustrative case.

BACKGROUND: Unruptured incidental intracranial aneurysm can coexist with pituitary adenoma, however, the occurrence is extremely rare. Timely diagnosis of asymptomatic intracranial aneurysms with pituitary adenoma may lead to planning a tailored surgical strategy to deal with both pathologies simultaneously. A case of a patient who underwent transcranial resection of a pituitary adenoma with clipping of two mirror aneurysms is reported. OBSERVATIONS: A 55-year-old female presented with deterioration of visual acuity that progressed over 1 year, as well as presence of right eyelid ptosis. Magnetic resonance imaging of the head showed the presence of an intrasellar pituitary macroadenoma. Bilateral paraclinoid aneurysms were documented to be in contact with the pituitary tumor. The patient underwent surgery with simultaneous aneurysm clipping and tumor resection through a standard pterional approach with intradural clinoidectomy. The aneurysms were successfully clipped after the tumoral debulking. After clipping, the pseudocapsule was fully resected. LESSONS: Various treatment options are available. Although endovascular securing of the aneurysms prior to the tumor resection would be ideal, in cases in which this resource is not readily available at all times, the surgeon must be prepared to solve pathologies with an elevated level of complexity.

Gating and anion selectivity are reciprocally regulated in TMEM16A (ANO1).

Numerous essential physiological processes depend on the TMEM16A-mediated Ca2+-activated chloride fluxes. Extensive structure-function studies have helped to elucidate the Ca2+ gating mechanism of TMEM16A, revealing a Ca2+-sensing element close to the anion pore that alters conduction. However, substrate selection and the substrate-gating relationship in TMEM16A remain less explored. Here, we study the gating-permeant anion relationship on mouse TMEM16A expressed in HEK 293 cells using electrophysiological recordings coupled with site-directed mutagenesis. We show that the apparent Ca2+ sensitivity of TMEM16A increased with highly permeant anions and SCN- mole fractions, likely by stabilizing bound Ca2+. Conversely, mutations at crucial gating elements, including the Ca2+-binding site 1, the transmembrane helix 6 (TM6), and the hydrophobic gate, impaired the anion permeability and selectivity of TMEM16A. Finally, we found that, unlike anion-selective wild-type channels, the voltage dependence of unselective TMEM16A mutant channels was less sensitive to SCN-. Therefore, our work identifies structural determinants of selectivity at the Ca2+ site, TM6, and hydrophobic gate and reveals a reciprocal regulation of gating and selectivity. We suggest that this regulation is essential to set ionic selectivity and the Ca2+ and voltage sensitivities in TMEM16A.

Function and Regulation of the Calcium-Activated Chloride Channel Anoctamin 1 (TMEM16A).

Various human tissues express the calcium-activated chloride channel Anoctamin 1 (ANO1), also known as TMEM16A. ANO1 allows the passive chloride flux that controls different physiological functions ranging from muscle contraction, fluid and hormone secretion, gastrointestinal motility, and electrical excitability. Overexpression of ANO1 is associated with pathological conditions such as hypertension and cancer. The molecular cloning of ANO1 has led to a surge in structural, functional, and physiological studies of the channel in several tissues. ANO1 is a homodimer channel harboring two pores - one in each monomer - that work independently. Each pore is activated by voltage-dependent binding of two intracellular calcium ions to a high-affinity-binding site. In addition, the binding of phosphatidylinositol 4,5-bisphosphate to sites scattered throughout the cytosolic side of the protein aids the calcium activation process. Furthermore, many pharmacological studies have established ANO1 as a target of promising compounds that could treat several illnesses. This chapter describes our current understanding of the physiological roles of ANO1 and its regulation under physiological conditions as well as new pharmacological compounds with potential therapeutic applications.

Oleic acid blocks the calcium-activated chloride channel TMEM16A/ANO1.

The calcium-activated chloride channel TMEM16A (ANO1) supports the passive movement of chloride ions across membranes and controls critical cell functions. Here we study the block of wild-type and mutant TMEM16A channels expressed in HEK293 cells by oleic acid, a monounsaturated omega-9 fatty acid beneficial for cardiovascular health. We found that oleic acid irreversibly blocks TMEM16A in a dose- and voltage-dependent manner at low intracellular Ca2+. We tested whether oleic acid interacted with the TMEM16A pore, varying the permeant anion concentration and mutating pore residues. Lowering the permeating anion concentration in the intracellular side did nothing but the blockade was intensified by increasing the anion concentration in the extracellular side. However, the blockade of the pore mutants E633A and I641A was voltage-independent, and the I641A IC50, a mutant with the inner hydrophobic gate in disarray, increased 16-fold. Furthermore, the uncharged methyl-oleate blocked 20-24% of the wild-type and I641A channels regardless of voltage. Our findings suggest that oleic acid inhibits TMEM16A by an allosteric mechanism after the electric field drives oleic acid's charged moiety inside the pore. Block of TMEM16A might be why oleic acid has a beneficial impact on the cardiovascular system.

Combined Endoscopic Transsphenoidal and Tubular Retractor-Assisted Transventricular Approach for Giant Pituitary Adenomas.

BACKGROUND: Surgical resection remains the standard treatment for most giant pituitary adenomas (GPAs). The selected surgical approach for these complex lesions depends mainly on their extension. Single approaches may be limited in some cases presenting with invasion into multiple compartments, thereby limiting extent of resection. METHODS: We report a series of patients with GPA operated on through a combined approach involving an endoscopic endonasal transsphenoidal approach and a tubular retractor-assisted transventricular approach, describing the technique, its indications, limitations, and outcomes. Baseline and postoperative clinical, functional, and morphologic variables were documented up until each patient's last follow-up visit. RESULTS: Five patients harboring tumors extending into the third and lateral ventricles were included. Mean extent of resection was 94.6%. Mean follow-up was 39.4 months. One patient presented with a growth hormone-secreting GPA, who achieved remission after repeat resection during follow-up. There were no intraoperative complications, and 1 patient required reoperation for cerebrospinal fluid leak repair. One patient received adjuvant radiotherapy, and 3 patients remained stable requiring no additional treatment. All patients maintained an adequate postoperative functional status. CONCLUSIONS: The combined approach herein described may be a safe and effective option for some patients with GPAs extending into the third and lateral ventricles. An adequate patient selection is mandatory to exploit the benefits of each individual approach.

Electro-steric opening of the CLC-2 chloride channel gate.

The widely expressed two-pore homodimeric inward rectifier CLC-2 chloride channel regulates transepithelial chloride transport, extracellular chloride homeostasis, and neuronal excitability. Each pore is independently gated at hyperpolarized voltages by a conserved pore glutamate. Presumably, exiting chloride ions push glutamate outwardly while external protonation stabilizes it. To understand the mechanism of mouse CLC-2 opening we used homology modelling-guided structure-function analysis. Structural modelling suggests that glutamate E213 interacts with tyrosine Y561 to close a pore. Accordingly, Y561A and E213D mutants are activated at less hyperpolarized voltages, re-opened at depolarized voltages, and fast and common gating components are reduced. The double mutant cycle analysis showed that E213 and Y561 are energetically coupled to alter CLC-2 gating. In agreement, the anomalous mole fraction behaviour of the voltage dependence, measured by the voltage to induce half-open probability, was strongly altered in these mutants. Finally, cytosolic acidification or high extracellular chloride concentration, conditions that have little or no effect on WT CLC-2, induced reopening of Y561 mutants at positive voltages presumably by the inward opening of E213. We concluded that the CLC-2 gate is formed by Y561-E213 and that outward permeant anions open the gate by electrostatic and steric interactions.

Update of the Mexican College of Rheumatology Guidelines for the Pharmacological Treatment of Rheumatoid Arthritis, 2018. / Actualización de las guías del tratamiento farmacológico de la artritis reumatoide del Colegio Mexicano de Reumatología 2018.

Therapeutic advances in rheumatoid arthritis require periodic review of treatment guidelines. OBJECTIVE: To update the Mexican College of Rheumatology guidelines on the pharmacological treatment of rheumatoid arthritis. METHOD: Board certified rheumatologists from different health institutions and regions of the country participated. Work teams were formed that reviewed the previous guidelines, elaborated new questions, reviewed the literature, and scored the evidence that was presented and discussed in plenary session. The conclusions were presented to infectologists, gynaecologists and patients. Recommendations were based on levels of evidence according to GRADE methodology. RESULTS: Updated recommendations on the use of available medications for rheumatoid arthritis treatment in Mexico up to 2017 are presented. The importance of adequate and sustained control of the disease is emphasized and relevant safety aspects are described. Bioethical conflicts are included, and government action is invited to strengthen correct treatment of the disease. CONCLUSIONS: The updated recommendations of the Mexican College of Rheumatology on the pharmacological treatment of rheumatoid arthritis incorporate the best available information to be used in the Mexican health care system.

Analysis of Intraoperative Seizures During Bipolar Brain Mapping in Eloquent Areas: Intraoperative Seizures in brain mapping.

OBJECTIVES: Awake Craniotomy (AC) is a very well described technique that is performed to make an adequate tumor resection preserving the functionality of the patient. Intraoperative Seizures (IS) are reported as a failure of such procedure. We analyze the incidence and risk factor during AC. METHODS: We made a review of the database of the National Institute of Neurology and Neurosurgery between January 2017 and May 2019 for intrinsic tumors located in eloquent areas of the brain. An analysis of ISconcerning the clinical history, clinical presentation, imaging techniques, histological findings and surgical technique was made. The factors associated with Mapping Failure (MF) were also evaluated. RESULTS: 45 patients were included of whom 7 patients (15.6%) developed IS after cortical-subcortical stimulation, 5 presented partial motor seizures (11.1%) and 2 experimented generalized secondary seizures (4.5%). Of the patients that had a MF, one patient (14%) was due to generalized tonic-clonic seizures which couldn't be managed by cold saline irrigation and administration of anti-seizures drugs and was then converted to a general anesthetic technique. We observed that the patients that had a bigger tumoral volume (112.2 cm3 85.3, P = 0,07) had a bigger positive relation in presenting IS, having a peak sensibility and specificity above 70 cc (ROC). CONCLUSIONS: In our analysis IS are more common in patients with high presurgical tumor volume. Even though the majority of the patients that presented IS didn't develop MF, it is important to acknowledge that the multidisciplinary group in the operating room must be prepared to detect these complications, treat them promptly and avoid MF.

Regulation of the Ca2+-activated chloride channel Anoctamin-1 (TMEM16A) by Ca2+-induced interaction with FKBP12 and calcineurin.

Chloride fluxes through the calcium-gated chloride channel Anoctamin-1 (TMEM16A) control blood pressure, secretion of saliva, mucin, insulin, and melatonin, gastrointestinal motility, sperm capacitation and motility, and pain sensation. Calcium activates a myriad of regulatory proteins but how these proteins affect TMEM16A activity is unresolved. Here we show by co-immunoprecipitation that increasing intracellular calcium with ionomycin or by activating sphingosine-1-phosphate receptors, induces coupling of calcium/calmodulin-dependent phosphatase calcineurin and prolyl isomerase FK506-binding protein 12 (FKBP12) to TMEM16A in HEK-293 cells. Application of drugs that target either calcineurin (cyclosporine A) or FKBP12 (tacrolimus known as FK506 and sirolimus known as rapamycin) caused a decrease in TMEM16A activity. In addition, FK506 and BAPTA-AM prevented co-immunoprecipitation between FKBP12 and TMEM16A. FK506 rendered the channel insensitive to cyclosporine A without altering its apparent calcium sensitivity whereas zero intracellular calcium blocked the effect of FK506. Rapamycin decreased TMEM16A activity in cells pre-treated with cyclosporine A or FK506. These results suggest the formation of a TMEM16A-FKBP12-calcineurin complex that regulates channel function. We conclude that upon a cytosolic calcium increase the TMEM16A-FKPB12-calcineurin trimers are assembled. Such hetero-oligomerization enhances TMEM16A channel activity but is not mandatory for activation by calcium.

Voltage-Dependent Protonation of the Calcium Pocket Enable Activation of the Calcium-Activated Chloride Channel Anoctamin-1 (TMEM16A).

Anoctamin-1 (ANO1 or TMEM16A) is a homo-dimeric Ca2+-activated Cl- channel responsible for essential physiological processes. Each monomer harbours a pore and a Ca2+-binding pocket; the voltage-dependent binding of two intracellular Ca2+ ions to the pocket gates the pore. However, in the absence of intracellular Ca2+ voltage activates TMEM16A by an unknown mechanism. Here we show voltage-activated anion currents that are outwardly rectifying, time-independent with fast or absent tail currents that are inhibited by tannic and anthracene-9-carboxylic acids. Since intracellular protons compete with Ca2+ for binding sites in the pocket, we hypothesized that voltage-dependent titration of these sites would induce gating. Indeed intracellular acidification enabled activation of TMEM16A by voltage-dependent protonation, which enhanced the open probability of the channel. Mutating Glu/Asp residues in the Ca2+-binding pocket to glutamine (to resemble a permanent protonated Glu) yielded channels that were easier to activate at physiological pH. Notably, the response of these mutants to intracellular acidification was diminished and became voltage-independent. Thus, voltage-dependent protonation of glutamate/aspartate residues (Glu/Asp) located in the Ca2+-binding pocket underlines TMEM16A activation in the absence of intracellular Ca2+.