The fidgetin family: Shaking things up among the microtubule-severing enzymes

The microtubule cytoskeleton is required for several crucial cellular processes, including chromosome segregation, cell polarity and orientation, and intracellular transport. These functions rely on microtubule stability and dynamics, which are regulated by microtubule-binding proteins (MTBPs). One such type of regulator is the microtubule-severing enzymes (MSEs), which are ATPases Associated with Diverse Cellular Activities (AAA+ ATPases). The most recently identified family are the fidgetins, which contain three members: fidgetin, fidgetin-like 1 (FL1), and fidgetin-like 2 (FL2). Of the three known MSE families, the fidgetins have the most diverse range of functions in the cell, spanning mitosis/meiosis, development, cell migration, DNA repair, and neuronal function. Furthermore, they offer intriguing novel therapeutic targets for cancer, cardiovascular disease, and wound healing. In the two decades since their first report, there has been great progress in our understanding of the fidgetins; however, there is still much left unknown about this unusual family. This review aims to consolidate the present body of knowledge of the fidgetin family of MSEs and to inspire deeper exploration into the fidgetins and the MSEs as a whole.

Fidgetin-like 2 depletion enhances cell migration by regulating GEF-H1, RhoA, and FAK

The microtubule (MT) cytoskeleton and its dynamics play an important role in cell migration. Depletion of the microtubule-severing enzyme Fidgetin-like 2 (FL2), a regulator of MT dynamics at the leading edge of migrating cells, leads to faster and more efficient cell migration. Here we examine how siRNA knockdown of FL2 increases cell motility. Förster resonance energy transfer biosensor studies shows that FL2 knockdown decreases activation of the p21 Rho GTPase, RhoA, and its activator GEF-H1. Immunofluorescence studies reveal that GEF-H1 is sequestered by the increased MT density resulting from FL2 depletion. Activation of the Rho GTPase, Rac1, however, does not change after FL2 knockdown. Furthermore, FL2 depletion leads to an increase in focal adhesion kinase activation at the leading edge, as shown by immunofluorescence studies, but no change in actin dynamics, as shown by fluorescence recovery after photobleaching. We believe these results expand our understanding of the role of MT dynamics in cell migration and offer new insights into RhoA and Rac1 regulation.

1678 A Rare Example of a Simple Bone Cyst of The Ascending Ramus in A Paediatric Patient

A simple bone cyst is described as an intra-osseous pseudocyst, devoid of an epithelial lining and either empty of filled with serous or sanguineous fluid. This case presents a rare example of a simple bone cyst of the ascending ramus of the mandible in a paediatric patient. Studies have shown that less than 5% of simple bone cysts of the jaw bones are located within the mandibular ramus, with the most common site being the premolar-molar region (75%). The 14-year-old female was referred by her orthodontist to the local Oral and Maxillofacial department, for an incidental finding on her pre-orthodontic OPT of a radiolucency in the left ascending ramus. Her medical history was clear, she was asymptomatic and had no sensory deficit. A CT scan demonstrated a 22mm multilocular radiolucency centred on the left ascending ramus, extending superiorly up to the base of the coronoid process and condylar neck. Inferiorly, the radiolucency abutted but did not involve the unerupted third molar. The scan highlighted thinning of the buccal and lingual cortices putting the patient at risk of pathological fracture. The inferior alveolar nerve canal passed through the lingual aspect of the radiolucency. The patient underwent exploration of the left mandible which revealed an empty bony cavity, with no cystic lining or contents. The definitive diagnosis of a simple bone cyst was established. She experienced satisfactory healing by her review appointment 4 weeks post-surgery. Combined radiographic and clinical assessment is important in the diagnosis of simple bone cysts.

1662 Closure of Oro-Antral Fistulae in Conjunction with Functional Endoscopic Sinus Surgery: A Retrospective Analysis + Systematic Review

Aim

The aim of this study was to evaluate the surgical closure of OAFs created following dental extractions in conjunction with FESS in adult patients within a hospital in South Wales, UK, during a 5-year period, from 1st January 2014 to 31st December 2018, with a systematic review of the literature to investigate success rates.

Method

A manual search in the hospital’s theatre system for surgery between 2014 and 2018 containing codes for FESS, OAC or OAF was completed. These were screened for joint cases, and the patient’s hospital numbers entered into a Microsoft Excel spreadsheet. A retrospective analysis of their clinical records was performed. Success was measured as total closure and relief of sinusitis after 1 month. The PRISMA format was used to complete the systematic review.

Results

13 patients (mean age 51 ± 12.44, 7:6 male to female) met the inclusion criteria. The most common cause was extraction of the maxillary first molar. A 100% success rate was achieved, with no patients requiring revision surgery. The systematic review highlighted an average success rate of 98.7%. A protocol for the management of OACs was designed in both English and Welsh and distributed to Primary Care Dentists within South Wales.

Conclusions

OAF closure with FESS can be considered as a highly effective approach, leaving patients symptom free. It is important that protocols are in place for dentists suspecting an OAC in order to expedite patient management.

Using methylcholanthrene-induced fibrosarcomas to study tumor immunology

Mouse models of cancer are essential in furthering our understanding both of the mechanisms that drive tumor development and the immune response that develops in parallel, and also in providing a platform for testing novel anti-cancer therapies. The majority of solid tumor models available rely on the injection of existing cancer cell lines into naïve hosts which, while providing quick and reproducible model systems, typically lack the development of a tumor microenvironment that recapitulates those seen in human cancers. Administration of the carcinogen 3-methylcholanthrene (MCA), allows tumors to develop in situ, forming a tumor microenvironment with an established stroma and vasculature. This article provides a detailed set of protocols for the administration of MCA into mice and the subsequent monitoring of tumors. Protocols are also provided for some of the routinely used downstream applications that can be used for MCA tumors.

Evaluation of novel highly specific antibodies to cancer testis antigen Centrin-1 for radioimmunoimaging and radioimmunotherapy of pancreatic cancer

Background

Pancreatic ductal adenocarcinoma (PDAC) accounts for >90% of pancreatic malignancies, and has median survival of <6 months. There is an urgent need for diagnostic and therapeutic options for PDAC. Centrin1 (CETN1) is a novel member of Cancer/Testis Antigens, with a 25‐fold increase of CETN1 gene expression in PDX from PDAC patients. The absence of selective anti‐CETN1 antibodies is hampering CETN1 use for diagnosis and therapy. Here we report the generation of highly specific for CETN1 antibodies and their evaluation for radioimmunoimaging and radioimmunotherapy (RIT) of experimental PDAC.

Methods

The antibodies to CETN1 were generated via mice immunization with immunogenic peptide distinguishing CETN1 from CETN2. Patient tumor microarrays were used to evaluate the binding of the immune serum to PDAC versus normal pancreas. The antibodies were tested for their preferential binding to CETN1 over CETN2 by ELISA. Mice bearing PDAC MiaPaCa2 xenografts were imaged with microSPECT/CT and treated with ²¹³Bi‐ and ¹⁷⁷Lu‐labeled antibodies to CETN1.

Results

Immune serum bind to 50% PDAC cases on patient tumor microarrays with no specific binding to normal pancreas. Antibodies demonstrated preferential binding to CETN1 versus CETN2. Antibody 69‐11 localized to PDAC xenografts in mice in vivo and ex vivo. RIT of PDAC xenografts with ²¹³Bi‐labeled antibodies was effective, safe, and CETN1‐specific.

Conclusions

The results demonstrate the ability of these novel antibodies to detect CETN1 both in vitro and in vivo; as well, the RIT treatment of experimental PDAC when radiolabeled with ²¹³Bi is highly efficient and safe. Further evaluation of these novel reagents for diagnosis and treatment of PDAC is warranted.

A potential case of remission of Parkinson's disease

We present the case of a 78-year-old male who, 16 years ago, was diagnosed with Parkinson's disease (PD) by a neurologist. He initially presented with left-hand tremor, stooped posture, shuffling gait, and frequent falls, which eventually progressed to bilateral motor symptoms after 3 years. Since 2012, his symptoms and signs have almost completely remitted, and he has been off all pharmacotherapy for that time. The accuracy of the initial PD diagnosis is supported by an appropriate clinical presentation, history of positive response to Sinemet, and an abnormal SPECT DaT scan; thus this case suggests the possibility of remission of symptoms in some patients. We propose that the patient's long history of meditation practice may have been one contributing factor of this improvement as meditation has been shown to release dopamine in the striatum.

Pain sensitization in people with knee osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

Emerging evidence suggests that pain sensitization plays an important role in pain associated with knee osteoarthritis (OA). This systematic review and meta-analysis examined the evidence for pain sensitization in people with knee OA and the relationship between pain sensitization and symptom severity.

METHODS

A search of electronic databases and reference lists was carried out. All full text observational studies published between 2000 and 2014 with the aim of investigating pain sensitization in humans with knee OA using quantitative sensory testing (QST) measures of hyperalgesia and central hyperexcitability were eligible for inclusion. Meta-analysis of data was carried out using a random effects model, which included results comparing knee OA participants to controls, and results comparing high symptom severity to low symptom severity.

RESULTS

Fifteen studies were identified following screening and quality appraisal. For the meta-analysis, pressure pain threshold (PPT) and heat pain threshold (HPT) means and standard deviations were pooled using random effects models. The point estimate was large for differences in PPTs between knee OA participants and controls [-0.85; confidence interval (CI): -1.1 to -0.6], and moderate for PPT differences between knee OA participants with high symptom severity vs those with low symptom severity (0.51; CI: -0.73 to -0.30). A small point estimate was found for differences in HPTs between knee OA participants and controls (-0.42; CI: -0.87 to 0.02).

CONCLUSION

Evidence from this systematic review and meta-analysis suggests that pain sensitization is present in people with knee OA and may be associated with knee OA symptom severity.

Highly prevalent colorectal cancer-infiltrating LAP⁺ Foxp3⁻ T cells exhibit more potent immunosuppressive activity than Foxp3⁺ regulatory T cells

Although elevated CD4⁺Foxp3⁺ regulatory T cell (Treg) frequencies within tumors are well documented, the functional and phenotypic characteristics of CD4⁺Foxp3⁺ and CD4⁺Foxp3⁻ T cell subsets from matched blood, healthy colon, and colorectal cancer require in-depth investigation. Flow cytometry revealed that the majority of intratumoral CD4⁺Foxp3⁺ T cells (Tregs) were Helios⁺ and expressed higher levels of cytotoxic T-lymphocyte antigen 4 (CTLA-4) and CD39 than Tregs from colon and blood. Moreover, ∼30% of intratumoral CD4⁺Foxp3⁻ T cells expressed markers associated with regulatory functions, including latency-associated peptide (LAP), lymphocyte activation gene-3 (LAG-3), and CD25. This unique population of cells produced interleukin-10 (IL-10) and transforming growth factor-β (TGF-β), and was ∼50-fold more suppressive than Foxp3⁺ Tregs. Thus, intratumoral Tregs are diverse, posing multiple obstacles to immunotherapeutic intervention in colorectal malignancies.

Paracetamol overdose as a result of dental pain requiring medical treatment – two case reports

Two cases of unintentional paracetamol overdose are presented. Over a one month period these patients presented to an Accident and Emergency (A&E) department with symptoms of paracetamol toxicity, following the ingestion of large quantities of analgesia for the self treatment of dental pain. In one case the patient had no access to a dentist. Both patients required admission under the care of the medical on-call team and required anti-toxicity treatment to prevent permanent liver injury. Subsequent referrals were made to the oral and maxillofacial surgery team who provided emergency dental treatment and advice on further dental care. This paper highlights the significant signs and symptoms of paracetamol overdose about which dental practitioners should be aware. It also describes the management principles required to prevent potentially life threatening liver damage. Discussion is also made of the potential impact on patients struggling to cope with pulpal pain without access to a general dental practitioner.

Credible investigation of air accidents

Within the United Kingdom the Air Accidents Investigation Branch (AAIB) has been used as a model for the other transport modes accident investigation bodies. Government Ministers considered that the AAIB's approach had established the trust of the public and the aviation industry in its ability to conduct independent and objective investigations. The paper will examine the factors that are involved in establishing this trust. They include: the investigation framework; the actual and perceived independence of the accident investigating body; the aviation industry's safety culture; the qualities of the investigators and the quality of their liaison with bereaved families those directly affected by the accidents they investigate.

Issues in life support and human factors in crew rescue from the ISS

The design and development of crew emergency response systems, particularly to provide an unplanned emergency return to Earth, requires an understanding of crew performance challenges in space. The combined effects of psychological and physiological adaptation during long-duration missions will have a significant effect on crew performance in the unpredictable and potentially life-threatening conditions of an emergency return to Earth. It is therefore important that the systems to be developed for emergency egress address these challenges through an integrated program to produce optimum productivity and safety in times of utmost stress. Fundamental to the success of the CRV is the Environmental Control and Life Support System (ECLSS), which provides the necessary conditions for the crew to survive their return mission in a shirtsleeve environment. This article will discuss the many issues in the design of an ECLSS system for CRV and place it in the context of the human performance challenges of the mission.

Human factors and life support issues in crew rescue from the International Space Station (ISS)

The design and development of crew emergency response systems, particularly to provide an unplanned emergency return to earth, requires an understanding of crew performance challenges in space. The combined effects of psychological and physiological adaptation during long duration missions will have a significant effect on crew performance in the unpredictable and potentially life threatening conditions of an emergency return to earth. It is therefore important that the systems to be developed for emergency egress address these challenges through an integrated program to produce optimum productivity and safety in times of utmost stress. Fundamental to the success of the CRV is the Environmental Control and Life Support System (ECLSS), which provides the necessary conditions for the crew to survive their return mission in a shirt-sleeve environment. This paper will discuss the many issues in the design of an ECLSS system for CRV and place it in the context of the human performance challenges of the mission.

Late tamponade with mechanical circulatory support

BACKGROUND

Circulatory support with mechanical devices often leads to bleeding and tamponade.

METHODS

We report a series of three patients that required mechanical circulatory support for postcardiotomy ventricular dysfunction.

RESULTS

Late tamponade occurred in each patient with different clinical presentations. Early postoperative bleeding occurred in 2 patients. There was no active bleeding in any of the 3 patients. Transesophageal echocardiography was not helpful in making the diagnosis.

CONCLUSION

Late tamponade, which may be the result of hematoma with earlier bleeding, can present as dyspnea, hypoxia, or forms of hemodynamic collapse. Exploratory media sternotomy is required to definitively make the diagnosis and to evacuate the hematoma.

Influence of ascending versus descending balloon counterpulsation on bypass graft blood flow

BACKGROUND

Mechanical circulatory assistance is frequently needed in postcardiotomy patients to support the failing heart. A balloon catheter called SupraCor (ABIOMED Cardiovascular, Inc, Danvers, MA) has been developed and is similar to the existing intraaortic balloon pump with the exception of placement in the ascending versus the descending thoracic aorta. This investigation compared the effects of SupraCor versus standard intraaortic balloon pump on internal mammary artery and venous conduit bypass graft blood flow.

METHODS

Porcine total heart bypass was used to anastomose a jugular vein from the ascending aorta to a subsequently ligated left anterior descending coronary artery. The left internal mammary artery was then anastomosed to the jugular vein so each conduit perfused the same coronary vascular bed. An additional right heart bypass preparation allowed precise control of cardiac output and blood pressure, which were maintained constant throughout mechanical circulatory assistance. Electromagnetic flow probes measured flow through each bypass graft and the other conduit was atraumatically occluded.

RESULTS

The SupraCor caused a significant increase in both internal mammary artery (+70% from 35 +/- mL/min to 56 +/- 9 mL/min; p = 0.04) and venous bypass graft blood flow (+49% from 66 +/- 12 mL/min to 95 +/- 15 mL/min; p = 0.02) when compared with controls. The intraaortic balloon pump failed to alter internal mammary artery or venous bypass graft flow.

CONCLUSIONS

The results demonstrate that counterpulsation with an ascending aortic balloon significantly increases coronary bypass graft flow in both internal mammary artery and venous conduits. In contrast, counterpulsation with a descending aortic balloon did not alter coronary bypass graft flow.

The prohibitin family of mitochondrial proteins regulate replicative lifespan

Cellular senescence is determined by multiple factors, including the genetic regulation of metabolism and responses to endogenous and exogenous stresses [1-4]. Recent studies implicate a limited number of gene products in elongating lifespan in yeast and Caenorhabditis elegans [2-4]; these include the C, elegans gene cik-1, a central regulator of metabolism [5], and yeast RAS2, which controls the response to ultraviolet irradiation and other stresses [3]. Another gene postulated to effect senescence is PHB1, the yeast homologue of prohibitin [3], a rodent gene initially identified as a potential regulator of growth arrest and tumour suppressor [6-8]. Highly conserved prohibitin homologues have been identified in mammals [9], Drosophila [10], C. elegans [9], plants [11] and yeast. A second mammalian gene, encoding BAP37, a protein with sequence similarity to prohibitin, is thought to be involved in lymphocyte function [9]. Here, we show that the nuclear-encoded mammalian prohibitin and BAP37 proteins are present in mitochondria, are co-expressed, and interact physically with each other. Deletion of the Saccharomyces cerevisiae homologues, PHB1 and PHB2, results in a decreased replicative lifespan and a defect in mitochondrial membrane potential. Our observations highlight the relationship between the metabolic efficiency of cells and the ageing process, and provide evidence for its evolutionary conservation.

Cancrum oris-like lesions

Cancrum oris is predominantly seen in children in underdeveloped countries where widespread malnutrition, dehydration and epidemic infections are present. In the western world, it is sometimes found in immunosuppressed adults with predisposing conditions such as leukaemia and infection associated with malnutrition. Early diagnosis and an intensive therapeutic approach are the key to a favourable prognosis of noma-like necro-ulcerative lesions. The prognosis is significantly improved if the predisposing condition can be removed. Two cases are presented and the treatment is discussed.