PAK6-mediated phosphorylation of PPP2R2C regulates LRRK2-PP2A complex formation.

Mutations in leucine-rich repeat kinase 2 (LRRK2) are a common cause of inherited and sporadic Parkinson's disease (PD) and previous work suggests that dephosphorylation of LRRK2 at a cluster of heterologous phosphosites is associated to disease. We have previously reported subunits of the PP1 and PP2A classes of phosphatases as well as the PAK6 kinase as regulators of LRRK2 dephosphorylation. We therefore hypothesized that PAK6 may have a functional link with LRRK2's phosphatases. To investigate this, we used PhosTag gel electrophoresis with purified proteins and found that PAK6 phosphorylates the PP2A regulatory subunit PPP2R2C at position S381. While S381 phosphorylation did not affect PP2A holoenzyme formation, a S381A phosphodead PPP2R2C showed impaired binding to LRRK2. Also, PAK6 kinase activity changed PPP2R2C subcellular localization in a S381 phosphorylation-dependent manner. Finally, PAK6-mediated dephosphorylation of LRRK2 was unaffected by phosphorylation of PPP2R2C at S381, suggesting that the previously reported mechanism whereby PAK6-mediated phosphorylation of 14-3-3 proteins promotes 14-3-3-LRRK2 complex dissociation and consequent exposure of LRRK2 phosphosites for dephosphorylation is dominant. Taken together, we conclude that PAK6-mediated phosphorylation of PPP2R2C influences the recruitment of PPP2R2C to the LRRK2 complex and PPP2R2C subcellular localization, pointing to an additional mechanism in the fine-tuning of LRRK2 phosphorylation.

Clinical features and postoperative survival in patients with sporadic versus multiple endocrine neoplasia type 1-related pancreatic neuroendocrine tumors: An international cohort study.

BACKGROUND: The optimal surgical management of pancreatic neuroendocrine tumors in patients with multiple endocrine neoplasia type 1 is controversial. This study sought to compare clinicopathologic characteristics and outcomes of multiple endocrine neoplasia type 1-associated and sporadic pancreatic neuroendocrine tumors from a large multi-national database. METHODS: A multi-institutional, international database of patients with surgically resected pancreatic neuroendocrine tumors was analyzed. The cohort was divided into 2 groups: those with multiple endocrine neoplasia type 1 versus those with sporadic disease. Clinicopathologic comparisons were made. Overall and disease-free survival were analyzed. Propensity score matching was used to reduce bias. RESULTS: Of 651 patients included, 45 (6.9%) had multiple endocrine neoplasia type 1 and 606 sporadic pancreatic neuroendocrine tumors. Multiple endocrine neoplasia type 1-associated pancreatic neuroendocrine tumors were more common in younger patients and associated with multifocal disease at the time of surgery and higher T-stage. Lymph node involvement and the presence of metastasis were similar. Total pancreatectomy rate was 5-fold higher in the multiple endocrine neoplasia type 1 cohort. Median survival did not differ (disease-free survival 126 months multiple endocrine neoplasia type 1 vs 198 months sporadic, P > .5). After matching, survival remained similar (overall survival not reached in either cohort, disease-free survival 126 months multiple endocrine neoplasia type 1 vs 198 months sporadic, P > .5). Equivalence in overall survival and disease-free survival persisted even when patients who underwent subtotal and total pancreatectomy were excluded. CONCLUSION: Multiple endocrine neoplasia type 1-associated pancreatic neuroendocrine tumors are more common in younger patients and are associated with multifocality and higher T-stage. Survival for patients with multiple endocrine neoplasia type 1-associated pancreatic neuroendocrine tumors is comparable to those with sporadic pancreatic neuroendocrine tumors, even in the absence of radical pancreatectomy. Consideration should be given to parenchymal-sparing surgery to preserve pancreatic function.

A Phosphosite Mutant Approach on LRRK2 Links Phosphorylation and Dephosphorylation to Protective and Deleterious Markers, Respectively.

The Leucine Rich Repeat Kinase 2 (LRRK2) gene is a major genetic determinant of Parkinson's disease (PD), encoding a homonymous multi-domain protein with two catalytic activities, GTPase and Kinase, involved in intracellular signaling and trafficking. LRRK2 is phosphorylated at multiple sites, including a cluster of autophosphorylation sites in the GTPase domain and a cluster of heterologous phosphorylation sites at residues 860 to 976. Phosphorylation at these latter sites is found to be modified in brains of PD patients, as well as for some disease mutant forms of LRRK2. The main aim of this study is to investigate the functional consequences of LRRK2 phosphorylation or dephosphorylation at LRRK2's heterologous phosphorylation sites. To this end, we generated LRRK2 phosphorylation site mutants and studied how these affected LRRK2 catalytic activity, neurite outgrowth and lysosomal physiology in cellular models. We show that phosphorylation of RAB8a and RAB10 substrates are reduced with phosphomimicking forms of LRRK2, while RAB29 induced activation of LRRK2 kinase activity is enhanced for phosphodead forms of LRRK2. Considering the hypothesis that PD pathology is associated to increased LRRK2 kinase activity, our results suggest that for its heterologous phosphorylation sites LRRK2 phosphorylation correlates to healthy phenotypes and LRRK2 dephosphorylation correlates to phenotypes associated to the PD pathological processes.

Allosteric Inhibition of Parkinson's-Linked LRRK2 by Constrained Peptides.

Leucine-Rich Repeat Kinase 2 (LRRK2) is a large, multidomain protein with dual kinase and GTPase function that is commonly mutated in both familial and idiopathic Parkinson's Disease (PD). While dimerization of LRRK2 is commonly detected in PD models, it remains unclear whether inhibition of dimerization can regulate catalytic activity and pathogenesis. Here, we show constrained peptides that are cell-penetrant, bind LRRK2, and inhibit LRRK2 activation by downregulating dimerization. We further show that inhibited dimerization decreases kinase activity and inhibits ROS production and PD-linked apoptosis in primary cortical neurons. While many ATP-competitive LRRK2 inhibitors induce toxicity and mislocalization of the protein in cells, these constrained peptides were found to not affect LRRK2 localization. The ability of these peptides to inhibit pathogenic LRRK2 kinase activity suggests that disruption of dimerization may serve as a new allosteric strategy to downregulate PD-related signaling pathways.

Operative treatment of athletic pubalgia in competitive athletes: a retrospective study.

BACKGROUND: Athletic pubalgia is an obscure sport injury, presenting mainly with groin pain during twisting movements. The present 15 year study reports outcomes, intraoperative findings and complications of the endoscopic surgical treatment in competitive athletes. METHODS: All competitive athletes, from 2004 to 2018, suffering from athletic pubalgia, treated with laparoscopic Total Extra-Peritoneal technique, at the Department of General, Laparoscopic, Oncologic and Robotic Surgery of the Athens Medical Center were included in this retrospective cohort. Postoperative pain, complications, return to previous training routine and patients' satisfaction were evaluated. RESULTS: A total of 130 patients (115; 88.5% males and 15; 11.5% females) with a mean age of 26.7±7.5 years were evaluated. Preoperatively, mean numeric scale pain was found to be 7.7±1.7. Three days postoperatively, the mean numeric pain scale was 3.4±1.5, showing 55.8% decrease. The mean time for return to sports activity was found to be 6.27±3.02 weeks. Regarding complications, six patients (4.6%) had slight numbness at the groin area during the first 6 postoperative months and one patient (0.8%) suffered from a postoperative hematoma. No recurrence was observed. At the final follow-up (mean 76.58±46.5 months), a total of 97 (74.7%) patients were very satisfied, 31 (23.8%) satisfied and two (1.5%) not satisfied with the outcome. CONCLUSIONS: Laparoscopic operative treatment in competitive athletes suffering from athletic pubalgia seems to offer rapid recovery, rapid return to sports, as well as very low complications rate and no recurrence.

Pancreatic grade 3 neuroendocrine tumors behave similarly to neuroendocrine carcinomas following resection: a multi-center, international appraisal of the WHO 2010 and WHO 2017 staging schema for pancreatic neuroendocrine lesions.

BACKGROUND: In 2017, the WHO updated their 2010 classification of pancreatic neuroendocrine tumors, introducing a well-differentiated, highly proliferative grade 3 tumor, distinct from neuroendocrine carcinomas. The aim of this study was to investigate the clinical significance of this update in a large cohort of resected tumors. METHODS: Using a multicenter, international dataset of patients with pancreatic neuroendocrine lesions, patients were classified both according to the WHO 2010 and 2017 schema. Multivariable survival analyses were performed, and the models were evaluated for discrimination ability and goodness of fit. RESULTS: Excluding patients with a known germline MEN1 mutation and incomplete data, 544 patients were analyzed. The performance of the WHO 2010 and 2017 models was similar, however surgically resected grade 3 tumors behaved very similarly to neuroendocrine carcinomas. CONCLUSION: The addition of a grade 3 NET classification may be of limited utility in surgically resected patients, as these lesions have similar postoperative survival compared to carcinomas. While the addition may allow for a more granular evaluation of novel treatment strategies, surgical intervention for high grade tumors should be considered judiciously.

Robot-Assisted Removal of a Broken Scalpel Blade following Discectomy.

The risk of a broken scalpel blade during discectomy is considered extremely rare, while no guidelines exist regarding this complication. We report a case of a robotic broken blade removal following lumbar discectomy. A 52-year-old female was subjected to L4-L5 discectomy. During the annulus resection, the scalpel blade broke and was retained within the disc space. The broken blade migrated towards the abdominal cavity and viscera. Emergency CT angiography scan revealed that the main vessels were intact, while the broken surgical knife was located anterior to the lumbar spine at the L4/L5 level, to the left of the aorta and superiorly of the left common iliac artery. At that point, robot-assisted laparoscopy was performed. The broken instrument was located and carefully removed. It seems more proper that such foreign bodies should be removed, while robotic surgery may play a significant role in cases that the foreign body is near major vessels.

Laparoscopic total extraperitoneal inguinal hernia repair: Retrospective study on prosthetic materials, postoperative management, and quality of life.

Laparoscopic inguinal hernia repair is one of the most frequently performed operations. However, the search for the most appropriate prosthetic materials continues to occupy the surgical community. The purpose of this study was to evaluate the postoperative short- and mid-term effects (like duration of stay, number and type of complications, and inguinal pain) of laparoscopic inguinal hernia repair using the total extraperitoneal (TEP) approach. The evaluation encompassed different types of mesh and fixation devices, as well as medications prescribed during hospitalization.This retrospective study was conducted at the General, Laparoendoscopic, Bariatric, and Robotic Surgical Clinic of the Athens Medical Center. Clinical data from 524 patients were evaluated. The answers from an appropriately designed questionnaire completed from each individual were used to obtain information about their postoperative course. The statistical analysis was implemented in SPSS v 23.Analysis revealed that pain sensation on discharge decreased with increasing age (P < .05). No clear relationship was found between surgical clips and pain (P = .292), as well as mesh absorbability and chronic pain (P = .539). The major postoperative complications were annoyance and discomfort (15.9%). The recurrence rate was 1.7%.Postoperative complications following the TEP approach were mostly found to be minor; chronic pain, as an aspect of impaired quality of life, was not experienced in the majority (89.08%). The properties of prosthetic materials used and the type of medications prescribed were not found to exert a significant role in satisfactory postoperative outcomes.

Biochemical and kinetic properties of the complex Roco G-protein cycle.

Roco proteins have come into focus after mutations in the gene coding for the human Roco protein Leucine-rich repeat kinase 2 (LRRK2) were discovered to be one of the most common genetic causes of late onset Parkinson's disease. Roco proteins are characterized by a Roc domain responsible for GTP binding and hydrolysis, followed by a COR dimerization device. The regulation and function of this RocCOR domain tandem is still not completely understood. To fully biochemically characterize Roco proteins, we performed a systematic survey of the kinetic properties of several Roco protein family members, including LRRK2. Together, our results show that Roco proteins have a unique G-protein cycle. Our results confirm that Roco proteins have a low nucleotide affinity in the micromolar range and thus do not strictly depend on G-nucleotide exchange factors. Measurement of multiple and single turnover reactions shows that neither Pi nor GDP release are rate-limiting, while this is the case for the GAP-mediated GTPase reaction of some small G-proteins like Ras and for most other high affinity Ras-like proteins, respectively. The KM values of the reactions are in the range of the physiological GTP concentration, suggesting that LRRK2 functioning might be regulated by the cellular GTP level.

The role of (auto)-phosphorylation in the complex activation mechanism of LRRK2.

Mutations in human leucine-rich-repeat kinase 2 (LRRK2) have been found to be the most frequent cause of late-onset Parkinson's Disease (PD). LRRK2 is a large protein with two enzymatic domains, a GTPase and a kinase domain. A cluster of (auto)-phosphorylation sites within the N-terminus of LRRK2 have been shown to be crucial for the localization of LRRK2 and is important for PD pathogenesis. In addition, phosphorylation of sites within the G-domain of the protein affect GTPase activity. Here we discuss the role of these (auto)-phosphorylation sites of LRRK2 and their regulation by phosphatases and upstream kinases.

A homologue of the Parkinson's disease-associated protein LRRK2 undergoes a monomer-dimer transition during GTP turnover.

Mutations in LRRK2 are a common cause of genetic Parkinson's disease (PD). LRRK2 is a multi-domain Roco protein, harbouring kinase and GTPase activity. In analogy with a bacterial homologue, LRRK2 was proposed to act as a GTPase activated by dimerization (GAD), while recent reports suggest LRRK2 to exist under a monomeric and dimeric form in vivo. It is however unknown how LRRK2 oligomerization is regulated. Here, we show that oligomerization of a homologous bacterial Roco protein depends on the nucleotide load. The protein is mainly dimeric in the nucleotide-free and GDP-bound states, while it forms monomers upon GTP binding, leading to a monomer-dimer cycle during GTP hydrolysis. An analogue of a PD-associated mutation stabilizes the dimer and decreases the GTPase activity. This work thus provides insights into the conformational cycle of Roco proteins and suggests a link between oligomerization and disease-associated mutations in LRRK2.

Laparoscopic Finney pyloroplasty in the emergency setting: first case report in the literature and technical challenges.

Pyloroplasty is currently reserved for emergencies (perforation, bleeding), but may occasionally be performed to treat benign gastric outlet obstruction (GOO). Historically, two techniques are available: the Mikulicz pyloroplasty, by which the pylorus is incised longitudinally and sutured vertically, and the Finney pyloroplasty, by which a U-shaped inverted incision is made in the second part of duodenum (D1-D2), followed by a side-to-side gastroduodenostomy. We report our experience in this single case of laparoscopic Finney pyloroplasty (LFP) performed in the emergency setting for a woman with a perforated duodenal ulcer and severe loss of tissue in D1-D2. Due to the presence of severely inflamed perforation edges and the risk of duodenal narrowing with subsequent GOO, Finney technique was favored over direct ulcer repair. The patient achieved a full postoperative recovery free of complications, with a dynamic oral contrast study demonstrating good gastric evacuation. Review of the current literature revealed no similar cases, as LFP has only been performed in the canine model. Although LFP requires a specific surgical skill-set, we believe it can be effective and feasible in cases of duodenal perforation with significant loss of mural substance.

Successful Outflow Reconstruction to Salvage Traumatic Hepatic Vein-Caval Avulsion of a Normothermic Machine Ex-Situ Perfused Liver Graft: Case Report and Management of Organ Pool Challenges.

Donor organ shortage continues to limit the availability of liver transplantation, a successful and established therapy of end-stage liver diseases. Strategies to mitigate graft shortage include the utilization of marginal livers and recently ex-situ normothermic machine perfusion devices. A 59-year-old woman with cirrhosis due to primary sclerosing cholangitis was offered an ex-situ machine perfused graft with unnoticed severe injury of the suprahepatic vasculature due to road traffic accident. Following a complex avulsion, repair and reconstruction of all donor hepatic veins as well as the suprahepatic inferior vena cava, the patient underwent a face-to-face piggy-back orthotopic liver transplantation and was discharged on the 11th postoperative day after an uncomplicated recovery. This report illustrates the operative technique to utilize an otherwise unusable organ, in the current environment of donor shortage and declining graft quality. Normothermic machine perfusion can definitely play a role in increasing the graft pool, without compromising the quality of livers who had vascular or other damage before being ex-situ perfused. Furthermore, it emphasizes the importance of promptly and thoroughly communicating organ injuries, as well as considering all reconstructive options within the level of expertise at the recipient center.

Long-term survival with repeated resections of recurrent hepatocellular carcinoma in a non-cirrhotic liver: case report and brief review of the literature.

A healthy and asymptomatic 55-year-old woman underwent a complete (R0) non-anatomical resection of an incidentally detected solitary hepatocellular carcinoma (HCC) in a non-cirrhotic liver. Six years following the initial R0 non-anatomical resection, intrahepatic recurrence was diagnosed and the patient underwent a second R0 non-anatomical resection. At 12.5 years following the initial resection, a further intrahepatic recurrence was diagnosed, which was once again completely resected by left lateral hepatectomy. This represents one of the longest reported periods between initial resection and HCC recurrence, following repeated R0 resections in the absence of cirrhosis. The appropriate surveillance period and genetic testing protocol for such cases remains to be established.

Primary small bowel melanomas: fact or myth?

Small bowel melanoma (SBM) is a rare entity, which often evades diagnosis and therefore presents late. Its origin, whether arising primarily or metastatically from an unidentified or regressed primary cutaneous melanoma, remains debatable. In this report, we present a rare case of primary SBM and review the current literature. A 60-year-old man presented with melena and microcytic anemia. A series of investigations including abdominal ultrasonography (US), esophago-gastro-duodenoscopy (EGD) and colonoscopy were normal. Abdominal computed tomography revealed no specific pathology. Subsequent capsule endoscopy identified a jejunal mass, which was confirmed on laparotomy, was resected, and histologically diagnosed as melanoma. Extensive postoperative clinical examination revealed no cutaneous lesions. This report discusses gastrointestinal (GI) malignant melanoma, and examines the evidence both for and against the existence of true primary vs. metastatic disease. Furthermore, this case highlights the capabilities of capsule endoscopy in identifying an extremely rare GI tumor, which evaded other diagnostic modalities. Finally, the origins and pathophysiology of this rare cancer are evaluated, with the aim of promoting early diagnosis and treatment, and therefore improving current poor outcomes.

Identification of protein phosphatase 2A as an interacting protein of leucine-rich repeat kinase 2.

Mutations in the gene coding for the multi-domain protein leucine-rich repeat kinase 2 (LRRK2) are the leading cause of genetically inherited Parkinson's disease (PD). Two of the common found mutations are the R1441C and G2019S. In this study we identified protein phosphatase 2A (PP2A) as an interacting partner of LRRK2. We were able to demonstrate that the Ras of complex protein (ROC) domain is sufficient to interact with the three subunits of PP2A in human neuroblastoma SH-SY5Y cells and in HeLa cells. The alpha subunit of PP2A is interacting with LRRK2 in the perinuclear region of HeLa cells. Silencing the catalytic subunit of PP2A by shRNA aggravated cellular degeneration induced by the pathogenic R1441C-LRRK2 mutant expressed in neuroblastoma SH-SY5Y cells. A similar enhancement of apoptotic nuclei was observed by downregulation of the catalytic subunit of PP2A in cultured cortical cells derived from neurons overexpressing the pathogenic mutant G2019S-LRRK2. Conversely, pharmacological activation of PP2A by sodium selenate showed a partial neuroprotection from R1441C-LRRK2-induced cellular degeneration. All these data suggest that PP2A is a new interacting partner of LRRK2 and reveal the importance of PP2A as a potential therapeutic target in PD.

Expression of Inflammatory and Regenerative Genes in a Model of Liver Ischemia/Reperfusion and Partial Hepatectomy.

PURPOSE/AIM: Hepatic ischemia/reperfusion (I/R) describes the paradox of additional tissue injury caused by reperfusion. The aim of this survey was to investigate the mRNA expression of genes exerting their inflammatory and regenerative reaction in a porcine model of I/R and extended hepatectomy. MATERIAL AND METHODS: Twelve pigs were used, weighing 30-35 kg in average, which were allocated in two groups: the I/R group with eight pigs and the sham-operated (control) one with four pigs. The I/R group underwent portacaval anastomosis and Pringle maneuver followed by extended hepatectomy. The hepatoduodenal ligament was occluded for 150 min and the liver remnant was reperfused for 24 hours. Blood samples were steadily received throughout the surgical procedure, where hepatic biopsies were taken for pathological evaluation. Animals were sacrificed in 24 hours after the onset of reperfusion. RESULTS: Between the two groups, statistically significant differences were noticed in serum values of AST, ALT, ALP, and total bilirubin in the early and late phase of reperfusion. The mRNA expression of iNOS, IL-1b, and TGF-a did not increase significantly in the I/R group. Conversely, the mRNA modification of IL-6, STAT-3, and E-selectin demonstrated significantly increased expression in I/R animals. CONCLUSIONS: In the present survey, a new I/R swine model was proposed and specific parameters were analyzed, revealing differences between the study groups.

Synchronous Hepatic Epithelioid Hemangioendothelioma and Hepatocellular Carcinoma: First Case Report in the Literature and Challenges.

We would like to report the first case in English literature, to the best of our knowledge, of a synchronous hepatic epithelioid hemangioendothelioma (HEHE) and hepatocellular carcinoma (HCC), as well as to address the current trends and challenges in the management of HEHE.An otherwise well 58-year-old man was referred to his local hepatology service with elevated serum γ-GT levels. Imaging revealed bilobar liver lesions consistent with HEHE, a discrete left lobe lesion suspected as HCC, and multiple pulmonary nodules. Biopsies confirmed HEHE with pulmonary metastases. After multidisciplinary team discussions, the patient was admitted under our team and underwent an uneventful laparoscopic left lateral hepatectomy for suspected HCC, which was confirmed histologically.As part of a watch-and-wait approach to metastatic HEHE, in the first follow-up (3 months postoperatively) the patient was clinically fine and the surveillance CT scan did not show recurrent disease.By presenting this case, we aim to raise awareness that this rare entity can coexist with others, potentially complicating their management.

Microelectromechanical systems and nanotechnology: a platform for the next stent technological era.

Nanotechnology is the design and development of materials, structures, and devices with at least 1 dimension between the 1- and 100-nm-size scale. Manipulating matter at the atomic scale offers unique opportunities in material design particularly in biological interfaces. In this short review, we explore the disruptive technological opportunities that nanotechnology and microelectromechanical systems may offer in possible future stent designs along with safety issues that may surface with the use of nanoparticles in medical devices.

Parathyroid autotransplantation in extensive head and neck resections: case series report.

Permanent or temporary hypoparathyroidism may be a debilitating result of radical cervical surgery, as noted most commonly following thyroid or parathyroid surgery. However, it can also be the outcome of any surgical procedure involving bilateral extensive manipulation of the anterior neck triangle, especially in order to ensure oncologically adequate surgical margins. We report our experience of three patients that underwent parathyroid immediate autotransplanation following extensive surgical manipulations of the neck region for oncological reasons. PTH levels were restored to normal by the fourth postoperative week, allowing us to wean the patients off calcium and vitamin D3 supplementation, which was attributed to full autograft function. Parathyroid autotransplantation, immediate or delayed, is a simple and safe technique which should be considered by the surgeon whenever there is a high risk for postoperative hypoparathyroidism following radical operations of the neck for oncological reasons.