Pore-blocking toxins inhibit voltage-dependent K(+) channels (Kv channels) by plugging the ion-conduction pathway. We have solved the crystal structure of paddle chimera, a Kv channel in complex with ...charybdotoxin (CTX), a pore-blocking toxin. The toxin binds to the extracellular pore entryway without producing discernable alteration of the selectivity filter structure and is oriented to project its Lys27 into the pore. The most extracellular K(+) binding site (S1) is devoid of K(+) electron-density when wild-type CTX is bound, but K(+) density is present to some extent in a Lys27Met mutant. In crystals with Cs(+) replacing K(+), S1 electron-density is present even in the presence of Lys27, a finding compatible with the differential effects of Cs(+) vs K(+) on CTX affinity for the channel. Together, these results show that CTX binds to a K(+) channel in a lock and key manner and interacts directly with conducting ions inside the selectivity filter. DOI:http://dx.doi.org/10.7554/eLife.00594.001.
DHHC (Asp-His-His-Cys) palmitoyltransferases are eukaryotic integral membrane enzymes that catalyze protein palmitoylation, which is important in a range of physiological processes, including small ...guanosine triphosphatase (GTPase) signaling, cell adhesion, and neuronal receptor scaffolding. We present crystal structures of two DHHC palmitoyltransferases and a covalent intermediate mimic. The active site resides at the membrane-cytosol interface, which allows the enzyme to catalyze thioester-exchange chemistry by using fatty acyl-coenzyme A and explains why membrane-proximal cysteines are candidates for palmitoylation. The acyl chain binds in a cavity formed by the transmembrane domain. We propose a mechanism for acyl chain-length selectivity in DHHC enzymes on the basis of cavity mutants with preferences for shorter and longer acyl chains.
Petroclival meningiomas are notoriously difficult lesions to manage surgically, given the critical neurovascular structures that are intimately associated with the tumors. In this paper, the authors' ...aim was to review their series of patients with petroclival meningiomas who underwent surgical treatment; emphasis was placed on evaluating modes of presentation, postoperative neurological outcome, complications, and recurrence rates.
Fifty patients underwent surgical treatment for petroclival meningiomas. The majority of the patients were women (72%). The authors retrospectively reviewed the patients' medical records, imaging studies, and pathology reports to analyze presentation, surgical approach, neurological outcomes, complications, and recurrence rates.
Headache was the most common presentation (58%). The most commonly used approach was the transpetrous approach (in 16 patients), followed by the orbitozygomatic approach (in 13). Gross-total resection was performed in 14 patients (28%), and in the remaining patients there was residual tumor (72%). Eighteen patients with tumor remnants were treated with Gamma Knife surgery. New postoperative cranial neuropathies were noted in 22 patients (44%). The most common cranial nerve (CN) deficit following surgery was CN III dysfunction (in 11 patients) and facial weakness (in 10). In 9 patients, the CN dysfunction was transient (41%), and 7 patients had permanent dysfunction (32%). Eight patients developed hydrocephalus and all required placement of a ventriculoperitoneal shunt. A CSF leak was noted in only 2 patients (4%), and wound dehiscence was noted in 1. The CSF leaks and the wound dehiscence occurred in patients who were undergoing reoperations. Adequate radiographic follow-up (minimum 6 months) was available for 31 patients (62%). The mean follow-up was 22.1 months. In 6 patients, tumor progression or recurrences were noted. The median time to recurrence was 84 months. At the time of discharge from the hospital, 92% of the patients had good outcomes (Glasgow Outcome Scale Scores 4 and 5). Three patients died of causes not directly related to the surgery.
Petroclival meningiomas still pose a formidable challenge to neurosurgeons. In their series, the authors used multiple skull base approaches and careful microneurosurgical technique to achieve a good functional outcome (Glasgow Outcome Scale Score 4 or 5) in 92% of patients, although the extent of gross-total resection was only 28%. The authors' primary surgical goal was to achieve maximal tumor resection while maintaining or improving neurological function. The authors favor the treatment of residual tumor or recurrent tumor with stereotactic radiosurgery.
Meningitis, the inflammation of the protective membrane surrounding the brain and spinal cord (known as meninges), is a condition associated with high mortality rates and permanent neurological ...sequelae in a significant proportion of survivors. The opportunistic pathogen
(SPN/pneumococcus) is the leading cause of bacterial meningitis in adults and older children. Following infection of the lower respiratory tract and subsequent bloodstream invasion, SPN breaches the blood-brain barrier endothelium for invasion of the central nervous system. Transcytosis, a mode of passage through the endothelial cells has been identified as the predominant route of pneumococcal blood-brain barrier trafficking. Herein, we review the interactions enabling SPN invasion into the brain endothelial cells, events involved in the tug-of-war between pneumococcal virulence factors and host intracellular defense machineries and pneumococcal strategies for evasion of host defenses and successful transendothelial trafficking.
Homeotic selector (HOX) transcription factors (TFs) regulate gene expression that determines the identity of Drosophila segments along the anterior-posterior (A-P) axis. The current challenge with ...HOX proteins is understanding how they achieve their functional specificity while sharing a highly conserved homeodomain (HD) that recognize the same DNA binding sites. One mechanism proposed to regulate HOX activity is differential post-translational modification (PTM). As a first step in investigating this hypothesis, the sites of PTM on a Sex combs reduced protein fused to a triple tag (SCRTT) extracted from developing embryos were identified by Tandem Mass Spectrometry (MS/MS). The PTMs identified include phosphorylation at S185, S201, T315, S316, T317 and T324, acetylation at K218, S223, S227, K309, K434 and K439, formylation at K218, K309, K325, K341, K369, K434 and K439, methylation at S19, S166, K168 and T364, carboxylation at D108, K298, W307, K309, E323, K325 and K369, and hydroxylation at P22, Y87, P107, D108, D111, P269, P306, R310, N321, K325, Y334, R366, P392 and Y398. Of the 44 modifications, 18 map to functionally important regions of SCR. Besides a highly conserved DNA-binding HD, HOX proteins also have functionally important, evolutionarily conserved small motifs, which may be Short Linear Motifs (SLiMs). SLiMs are proposed to be preferential sites of phosphorylation. Although 6 of 7 phosphosites map to regions of predicted SLiMs, we find no support for the hypothesis that the individual S, T and Y residues of predicted SLiMs are phosphorylated more frequently than S, T and Y residues outside of predicted SLiMs.
Background:Right ventricular (RV) volumetric and functional assessments are both crucial for the management of patients with hypoplastic left heart syndrome (HLHS). 3-dimensional echocardiography ...(3DE) for volume measurements and 2D speckle-tracking echocardiography (2D-STE) for strain analysis are performed separately. 3D-STE is capable of evaluating those parameters simultaneously and providing principal strain (PS), unifying the concepts of myofiber orientation and contraction into a single, maximal contractile direction. However, the application of 3D-STE to HLHS has not been studied and so became the aim of our study.Methods and Results:64 HLHS patients after Fontan palliation underwent 3D-STE analysis measuring RV end-diastolic volume index (EDVi), ejection fraction (EF), global PS (GPS), global circumferential strain (GCS), and global longitudinal strain (GLS). Volume measurements were compared between 3D-STE and 3DE, and strains were compared between 3D- and 2D-STE. EDVi and EF showed strong correlations between 3D-STE and 3DE (r=0.93 and 0.87, respectively). GCS and GLS showed moderate correlations between 3D- and 2D-STE (r=0.65 and 0.61, respectively). GPS showed highest magnitude and excellent correlation with EF (r=−0.95).Conclusions:Simultaneous volumetric and functional assessment by 3D-STE was a useful method in this HLHS cohort. PS is a promising parameter for evaluating the RV function of HLHS, which could be useful during longitudinal follow-up.
ABSTRACT
The Agency for Healthcare Research and Quality patient safety indicators (PSI) were developed as a metric of hospital complication rates. PSI‐14 measures postoperative wound dehiscence and ...specifically how often a surgical wound in the abdominal or pelvic area fails to heal after abdominopelvic surgery. Wound dehiscence is estimated to occur in 0.5–3.4% of abdominopelvic surgeries, and carries a mortality of up to 40%. Postoperative wound dehiscence has been adopted as a surrogate safety outcome measure as it impacts morbidity, length of stay, healthcare costs and readmission rates. Postoperative wound dehiscence cases from the Nationwide Inpatient Sample demonstrate 9.6% excess mortality, 9.4 days of excess hospitalization and $40,323 in excess hospital charges relative to matched controls. The purpose of the current study was to investigate the associations between PSI‐14 and measurable medical and surgical comorbidities using the Explorys technology platform to query electronic health record data from a large hospital system serving a diverse patient population in the Washington, DC and Baltimore, MD metropolitan areas. The study population included 25,636 eligible patients who had undergone abdominopelvic surgery between January 1, 2008 and December 31, 2012. Of these cases, 786 (2.97%) had postoperative wound dehiscence. Patient‐associated comorbidities were strongly associated with PSI‐14, suggesting that this indicator may not solely be an indicator of hospital safety. There was a strong association between PSI‐14 and opioid use after surgery and this finding merits further investigation.
Fibrinolysis was initially defined using rapid thrombelastography (rTEG). The cutoffs for the pathologic extremes of the fibrinolytic system, hyperfibrinolysis and shutdown, were both defined based ...on association with mortality. We propose to redefine these phenotypes for both TEG and for rotational thrombelastometry, the other commonly used viscoelastic assay.
Rotational thrombelastometry, rTEG, and clinical data were prospectively collected on trauma patients admitted to an urban Level I trauma center from 2010 to 2016. Hyperfibrinolysis was defined as the Youden index from EXTEM-clot lysis index 60 minutes after clotting time (CLI60) and rTEG-fibrinolysis 30 minutes after achieving MA (LY30) for predicting massive transfusion (>10 red blood cell units, or death per 6 hours after injury) as a surrogate for severe bleeding. Patients identified as having hyperfibrinolysis were then removed from the data set, and the cutoff for fibrinolysis shutdown was derived as the optimal cutoff for predicting mortality in the remaining patients.
Overall, 216 patients (median age, 36 years (interquartile range, 27-49 years), 82% men, 58% blunt injury) were included. Of these, 16% required massive transfusion, and 12.5% died. Rapid thrombelastography phenotypes were redefined as hyperfibrinolysis: rTEG-LY30 greater than7.7%, physiologic rTEG-LY30 0.6% to7.6%, and shutdown rTEG-LY30 less than 0.6%. EXTEM-CLI60 fibrinolysis phenotypes were hyperfibrinolysis CLI60 less than 82%, physiologic (CLI60, 82-97.9%), and shutdown (CLI60 > 98%). Weighted kappa statistics revealed moderate agreement between rotational thrombelastometry- and rTEG-defined fibrinolysis (k = 0.51; 95% confidence interval, 0.39-0.63), with disagreement mostly in the shutdown and physiologic categories.
We confirmed the U-shaped distribution of death related to fibrinolysis system abnormalities. Both rTEG LY30 and EXTEM CLI60 can identify the spectrum of fibrinolytic phenotypes, have moderate agreement, and can be used to guide hemostatic resuscitation.
Diagnostic study, level III.
Moyamoya disease, an uncommon chronic intra-cerebral arteriopathy asymmetrically affecting the proximal vasculature, is rarely associated with clinical features pertaining to movement disorders.
A ...5-year-and-9-month-old boy developed repetitive episodic involuntary winking of the right eye along with ipsilateral shoulder shrugging movements in an absolutely conscious state, associated with paroxysmal shouts and loud laughs and punctuated with abusive verbal expressions (coprolalia). These episodic features, over the course of the next 1.5 years, got progressively accentuated by situations which evoked stress. In addition, there was progressive regression of verbal and cognitive milestones, emotional lability and aspects of attention deficit hyperkinetic disorder. The child was evaluated by a neurologist with magnetic resonance imaging of the brain, which showed characteristic ischaemic areas involving the basal ganglia and fronto-parietal cortical areas along the middle cerebral artery territory, predominantly on the left side. Subsequent cerebral angiography revealed extensive stenosis of bilateral (predominantly left-sided) internal cerebral arteries and middle cerebral arteries with evidence of diffuse leptomeningeal collaterals. The electroencephalography was reported to be normal. He was eventually diagnosed to be suffering from Moyamoya disease with associated Tourette's syndrome. Subsequently, the child underwent left-sided superficial temporal artery to middle cerebral artery anastomosis along with encephalo-duro-arterio-myo-synangiosis. Significant clinico-radiological improvement was noted after 3 months. The clinical deficiencies had dramatically resolved. There was evidence of excellent development of both direct and indirect surgical collaterals along the left middle cerebral artery territory. He could go back to school.
Ours is probably the first case reporting an association of paediatric Moyamoya disease with Tourette's syndrome, which significantly resolved after cerebral revascularisation surgery.
PDF
