Mitochondria undergo fission and fusion to maintain homeostasis, and tumors exhibit the dysregulation of mitochondrial dynamics. We recently demonstrated that ectopic HRasG12V promotes mitochondrial ...fragmentation and tumor growth through Erk phosphorylation of the mitochondrial fission GTPase Dynamin-related protein 1 (Drp1). However, the role of Drp1 in the setting of endogenous oncogenic KRas remains unknown. Here, we show that Drp1 is required for KRas-driven anchorage-independent growth in fibroblasts and patient-derived pancreatic cancer cell lines, and it promotes glycolytic flux, in part through the regulation of hexokinase 2 (HK2). Furthermore, Drp1 deletion imparts a significant survival advantage in a model of KRas-driven pancreatic cancer, and tumors exhibit a strong selective pressure against complete Drp1 deletion. Rare tumors that arise in the absence of Drp1 have restored glycolysis but exhibit defective mitochondrial metabolism. This work demonstrates that Drp1 plays dual roles in KRas-driven tumor growth: supporting both glycolysis and mitochondrial function through independent mechanisms.
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•Drp1 is required for oncogenic KRas-driven transformation•Drp1 promotes KRas-driven glycolysis•Loss of Drp1 inhibits pancreatic tumorigenesis•Loss of Drp1 impairs mitochondrial metabolism in tumor cells
Nagdas et al. find that the mitochondrial fission GTPase Drp1 is required for KRas-driven transformation and pancreatic tumor growth. The inhibition of Drp1 in cells expressing oncogenic KRas leads to impaired glycolytic flux and the eventual loss of mitochondrial metabolic function.
Brain aging is associated with diminished circadian clock output and decreased expression of the core clock proteins, which regulate many aspects of cellular biochemistry and metabolism. The genes ...encoding clock proteins are expressed throughout the brain, though it is unknown whether these proteins modulate brain homeostasis. We observed that deletion of circadian clock transcriptional activators aryl hydrocarbon receptor nuclear translocator-like (Bmal1) alone, or circadian locomotor output cycles kaput (Clock) in combination with neuronal PAS domain protein 2 (Npas2), induced severe age-dependent astrogliosis in the cortex and hippocampus. Mice lacking the clock gene repressors period circadian clock 1 (Per1) and period circadian clock 2 (Per2) had no observed astrogliosis. Bmal1 deletion caused the degeneration of synaptic terminals and impaired cortical functional connectivity, as well as neuronal oxidative damage and impaired expression of several redox defense genes. Targeted deletion of Bmal1 in neurons and glia caused similar neuropathology, despite the retention of intact circadian behavioral and sleep-wake rhythms. Reduction of Bmal1 expression promoted neuronal death in primary cultures and in mice treated with a chemical inducer of oxidative injury and striatal neurodegeneration. Our findings indicate that BMAL1 in a complex with CLOCK or NPAS2 regulates cerebral redox homeostasis and connects impaired clock gene function to neurodegeneration.
Combination treatment with immune checkpoint inhibitors and antiangiogenic drugs has shown encouraging preliminary antitumor activity across various tumor types including advanced or metastatic renal ...cell carcinoma (aRCC). The open-label, parallel-cohort, dose-escalation, phase I CheckMate 016 study evaluated the efficacy and safety of nivolumab in combination with antiangiogenic tyrosine kinase inhibitors or ipilimumab. Long-term outcomes from this study for the combination of nivolumab plus sunitinib or pazopanib in aRCC are presented.
Patients with aRCC received nivolumab plus either sunitinib (50 mg/day, 4 weeks on/2 weeks off; N + S) or pazopanib (800 mg/day; N + P) until progression/unacceptable toxicity. The nivolumab starting dose was 2 mg/kg every 3 weeks, with planned escalation to 5 mg/kg every 3 weeks. Primary endpoints were safety and tolerability; antitumor activity was a secondary endpoint.
Arm N + S enrolled 33 patients, 19 of whom were treatment-naïve; this arm advanced to the expansion phase. Median follow-up was 50.0 months. Patients experienced high frequencies of adverse events (AEs) including treatment-related AEs (100%), grade 3/4 treatment-related AEs (82%), and treatment-related AEs leading to discontinuation (39%). Investigator-assessed objective response rate (ORR) was 55% (18/33) and median progression-free survival (PFS) was 12.7 months. Median overall survival (OS) was not reached. Arm N + P enrolled 20 patients, all had ≥1 prior systemic therapy; this arm was closed due to dose-limiting toxicities and did not proceed to expansion. Median follow-up was 27.1 months. Patients treated with N + P experienced high frequencies of AEs including treatment-related AEs (100%), grade 3/4 treatment-related AEs (70%), and treatment-related AEs leading to discontinuation (25%). Investigator-assessed ORR was 45% (9/20) and median PFS was 7.2 months. Median OS was 27.9 months.
The addition of standard doses of sunitinib or pazopanib to nivolumab resulted in a high incidence of high-grade toxicities limiting future development of either combination regimen. While there was no adverse impact on response and the OS outcome was notable, the findings suggest that the success of combination regimens based on immune checkpoint inhibitors and antiangiogenic drugs may be dependent on careful selection of the antiangiogenic component and dose.
Clinicaltrials.gov identifier: NCT01472081 . Registered 16 November 2011.
Few treatment options are available for patients with advanced renal cell carcinoma who have received previous anti-PD-1-based or anti-PD-L1-based immunotherapy. Combining belzutifan, an HIF-2α ...inhibitor, with cabozantinib, a multitargeted tyrosine-kinase inhibitor of VEGFR, c-MET, and AXL, might provide more antitumoural effects than either agent alone. We aimed to investigate the antitumour activity and safety of belzutifan plus cabozantinib in patients with advanced clear cell renal cell carcinoma that was previously treated with immunotherapy.
This open-label, single-arm, phase 2 study was conducted at ten hospitals and cancer centres in the USA. Patients were enrolled into two cohorts. Patients in cohort 1 had treatment-naive disease (results will be reported separately). In cohort 2, eligible patients were aged 18 years or older with locally advanced or metastatic clear cell renal cell carcinoma, measurable disease according to Response Evaluation Criteria in Solid Tumours version 1.1, an Eastern Cooperative Oncology Group performance status score of 0 or 1, and had previously received immunotherapy and up to two systemic treatment regimens. Patients were given belzutifan 120 mg orally once daily and cabozantinib 60 mg orally once daily until disease progression, unacceptable toxicity, or patient withdrawal. The primary endpoint was confirmed objective response assessed by the investigator. Antitumour activity and safety were assessed in all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT03634540, and is ongoing.
Between Sept 27, 2018, and July 14, 2020, 117 patients were screened for eligibility, 52 (44%) of whom were enrolled in cohort 2 and received at least one dose of study treatment. Median age was 63·0 years (IQR 57·5–68·5), 38 (73%) of 52 patients were male, 14 (27%) were female, 48 (92%) were White, two (4%) were Black or African American, and two were Asian (4%). As of data cutoff (Feb 1, 2022), median follow-up was 24·6 months (IQR 22·1–32·2). 16 (30·8% 95% CI 18·7–45·1) of 52 patients had a confirmed objective response, including one (2%) who had a complete response and 15 (29%) who had partial responses. The most common grade 3–4 treatment-related adverse event was hypertension (14 27% of 52 patients). Serious treatment-related adverse events occurred in 15 (29%) patients. One death was considered treatment related by the investigator (respiratory failure).
Belzutifan plus cabozantinib has promising antitumour activity in patients with pretreated clear cell renal cell carcinoma and our findings provide rationale for further randomised trials with belzutifan in combination with a VEGFR tyrosine-kinase inhibitor.
Merck Sharp & Dohme (a subsidiary of Merck & Co) and the National Cancer Institute.
The purpose of this guideline is to update the 2010 American Academy of Neurology (AAN) brain death/death by neurologic criteria (BD/DNC) guideline for adults and the 2011 American Academy of ...Pediatrics, Child Neurology Society, and Society of Critical Care Medicine guideline for infants and children and to clarify the BD/DNC determination process by integrating guidance for adults and children into a single guideline. Updates in this guideline include guidance related to conducting the BD/DNC evaluation in the context of extracorporeal membrane oxygenation, targeted temperature management, and primary infratentorial injury.
A panel of experts from multiple medical societies developed BD/DNC recommendations. Because of the lack of high-quality evidence on the subject, a novel, evidence-informed formal consensus process was used. This process relied on the panel experts' review and detailed knowledge of the literature surrounding BD/DNC to guide the development of preliminary recommendations. Recommendations were formulated and voted on, using a modified Delphi process, according to the 2017 AAN Clinical Practice Guideline Process Manual.
Eighty-five recommendations were developed on the following: (1) general principles for the BD/DNC evaluation, (2) qualifications to perform BD/DNC evaluations, (3) prerequisites for BD/DNC determination, (4) components of the BD/DNC neurologic examination, (5) apnea testing as part of the BD/DNC evaluation, (6) ancillary testing as part of the BD/DNC evaluation, and (7) special considerations for BD/DNC determination.
ABSTRACT
BACKGROUND
The Congress of Neurological Surgeons reviews its guidelines according to the Institute of Medicine's recommended best practice of reviewing guidelines every 5 yrs. The authors ...performed a planned 5-yr review of the medical literature used to develop the “Pediatric hydrocephalus: systematic literature review and evidence-based guidelines” and determined the need for an update to the original guideline based on new available evidence.
OBJECTIVE
To perform an update to include the current medical literature for the “Pediatric hydrocephalus: systematic literature review and evidence-based guidelines”, originally published in 2014.
METHODS
The Guidelines Task Force used the search terms and strategies consistent with the original guidelines to search PubMed and Cochrane Central for relevant literature published between March 2012 and November 2019. The same inclusion/exclusion criteria were also used to screen abstracts and to perform the full-text review. Full text articles were then reviewed and when appropriate, included as evidence and recommendations were added or changed accordingly.
RESULTS
A total of 41 studies yielded by the updated search met inclusion criteria and were included in this update.
CONCLUSION
New literature resulting from the update yielded a new recommendation in Part 2, which states that neuro-endoscopic lavage is a feasible and safe option for the removal of intraventricular clots and may lower the rate of shunt placement (Level III). Additionally a recommendation in part 7 of the guideline now states that antibiotic-impregnated shunt tubing reduces the risk of shunt infection compared with conventional silicone hardware and should be used for children who require placement of a shunt (Level I). <https://www.cns.org/guidelines/browse-guidelines-detail/pediatric-hydrocephalus-guideline>
Chiari 1 and Hydrocephalus - A Review Sharma, Himanshu; Treiber, Jeffrey; Bauer, David
Neurology India,
11/2021, Volume:
69, Issue:
8
Journal Article
Peer reviewed
Open access
Chari 1 malformation, a radiologic finding of caudal cerebellar tonsillar displacement, has a clinical course that can range from benign to complications involving life-threatening hydrocephalus. ...While the pathophysiologic processes underlying this variation in outcome remain a matter of scientific debate, the clinical realities and decision-making conundrums that these patients pose require a coherent approach to this entity. In this review, we seek to highlight the various processes underlying the development of hydrocephalus in patients with Chiari 1 malformations. Hydrocephalus may occur as a cause, consequence, or in parallel with the development of Chiari 1 malformation, and understanding the etiology of such hydrocephalus is critical to the treatment of Chiari 1 malformations with associated hydrocephalus. We further discuss the literature pertaining to the management of these patients and unify the current scientific thinking on Chiari 1 malformations with the extant data on operative management of Chiari 1 to develop a structured and pragmatic approach to the diagnosis and management of patients with Chiari 1-associated hydrocephalus.
Biotic Immigration Events (BIMEs) record the large-scale dispersal of taxa from one biogeographic area to another and have significantly impacted biodiversity throughout geologic time. BIMEs ...associated with biodiversity increases have been linked to ecologic and evolutionary processes including niche partitioning, species packing, and higher speciation rates. Yet substantial biodiversity decline has also been documented following BIMEs due to elevated extinction and/or reduced speciation rates. In this review, we develop a conceptual model for biodiversity accumulation that links BIMEs and geographic isolation with local (α) diversity, regional (β) diversity, and global (γ) diversity metrics. Within the model, BIME intervals are characterized by colonization of existing species within new geographic regions and a lack of successful speciation events. Thus, there is no change in γ-diversity, and α-diversity increases at the cost of β-diversity. An interval of regional isolation follows in which lineage splitting results in successful speciation events and diversity increases across all three metrics. Alternation of these two regimes can result in substantial biodiversity accumulation.
We tested this conceptual model using a series of case studies from the paleontological record. We primarily focus on two intervals during the Middle through Late Ordovician Period (470–458Ma): the globally pervasive BIMEs during the Great Ordovician Biodiversification Event (GOBE) and a regional BIME, the Richmondian Invasion. We further test the conceptual model by examining the Great Devonian Interchange, Neogene mollusk migrations and diversification, and the Great American Biotic Interchange. Paleontological data accord well with model predictions.
Constraining the mechanisms of biodiversity accumulation provides context for conservation biology. Because α-, β-, and γ-diversity are semi-independent, different techniques should be considered for sustaining various diversity partitions. Maintaining natural migration routes and population sizes among isolated regions are vital to preserving both extant biodiversity and biogeographic pathways requisite for future diversity generation.
•Biotic immigration events (BIMEs) are common in the geologic record.•Alternating dispersal and vicariance regimes can generate substantial diversity.•BIME intervals increase diversity within basins, but not at higher scales.•Speciation occurs primarily during intervals of regional isolation.•BIMEs of the geologic past provide an analog for modern invasive species.
Vagal nerve stimulation is a safe and well-tolerated treatment for drug-resistant epilepsy. Complications and failure of the device can result from lead fracture, device malfunction, disconnection, ...or battery displacement and can result in a variety of symptoms. We present an interesting case of stimulator malfunction with increased impedance change seen only with a change in head position.
The patient is a 25-year-old male with a vagal nerve stimulator (VNs) placed for medically refractory epilepsy who presented with neck pain and an electrical pulling sensation in his neck whenever he turned his head to the right.
Initial interrogation of the VNs showed normal impedance. Subsequent interrogation with the patient's head turned found increased impedance only when the head was turned to the right. The patient had successful removal and replacement of the device with resolution of his preoperative complaints. Partial lead fracture was seen at explant.
VNs malfunction can present in atypical ways. Positional maneuvers may help with its timely diagnosis.
•Vagal nerve stimulator malfunction can present atypically.•Vagal nerve stimulator malfunction can manifest as shock sensation on head turning.•Impedances on a vagal nerve stimulator can vary correspondingly by position.
Vagal nerve stimulators (VNs) have been in use in the United States since the 1990s as a palliative treatment option for drug-resistant epilepsy. Over time, the electrode coils wrapped around the ...vagus nerve become encapsulated by extensive scar tissue, making complete electrode removal challenging. We present a case series of lead revision surgeries with a unique way to remove the scar tissue around the vagus nerve, demonstrating a technique for complete electrode removal.
This was a case series of 9 consecutive patients who underwent complete removal of an existing VNs electrode using needle tip monopolar electrocautery.
Complete removal of the entire VNs electrode array was achieved in all patients with no permanent complications seen at postoperative follow-up at 3 months.
Complete VNs electrode array removal can be safely achieved by using needle tip monopolar electrocautery.
•Lead coils around the VN tend to be covered by extensive scaring, making complete removal challenging.•Monopolar cautery with ultra-sharp tip at low setting can safely be used to remove the scar tissue around the lead coils.•EC has the potential to damage peripheral nerve during the dissection process on a microscopic level.
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