Suprapapillary placement of plastic versus metal stents for malignant biliary hilar obstructions: a multicenter, randomized trial.

BACKGROUND AND AIMS: The efficacy of the suprapapillary placement of inside plastic stents (iPSs) for unresectable malignant hilar biliary obstructions (MHOs) is unknown compared with that of uncovered inside metal stents (iMSs). This randomized controlled trial was designed to evaluate the outcomes of endoscopic placement of these stents for unresectable MHOs. METHODS: This open-label, randomized study was conducted at 12 Japanese institutions. The enrolled patients with unresectable MHOs were allocated to iPS and iMS groups. The primary outcome was defined as the time to recurrent biliary obstruction in patients for whom the intervention was both technically and clinically successful. RESULTS: Among 87 enrollments, 38 patients in the iPS group and 46 patients in the iMS group were analyzed. Technical success rates were 100% (38 of 38) and 96.6% (44 of 46), respectively (P = 1.00). After transferring 1 unsuccessful iMS-group patient to the iPS group (since iPSs were deployed), the clinical success rates were 90.0% (35 of 39) for the iPS group and 88.9% (40 of 45) for the iMS group from a per-protocol analysis (P = 1.00). Among the patients with clinical success, the median times to recurrent biliary obstruction were 250 (95% confidence interval, 85-415) and 361 (95% confidence interval, 107-615) days (log-rank test, P = .34). No differences were detected in rates of adverse events. CONCLUSIONS: This Phase II randomized trial did not show any statistically significant difference in stent patency between suprapapillary plastic versus metal stents. Considering the potential advantages of plastic stents for malignant hilar obstruction, these findings suggest that suprapapillary plastic stents could be a viable alternative to metal stents for this condition.

Influence of spatially segregated IP3-producing pathways on spike generation and transmitter release in Purkinje cell axons.

It has been known for a long time that inositol-trisphosphate (IP3) receptors are present in the axon of certain types of mammalian neurons, but their functional role has remained unexplored. Here we show that localized photolysis of IP3 induces spatially constrained calcium rises in Purkinje cell axons. Confocal immunohistology reveals that the axon initial segment (AIS), as well as terminals onto deep cerebellar cells, express specific subtypes of Gα/q and phospholipase C (PLC) molecules, together with the upstream purinergic receptor P2Y1. By contrast, intermediate parts of the axon express another set of Gα/q and PLC molecules, indicating two spatially segregated signaling cascades linked to IP3 generation. This prompted a search for distinct actions of IP3 in different parts of Purkinje cell axons. In the AIS, we found that local applications of the specific P2Y1R agonist MRS2365 led to calcium elevation, and that IP3 photolysis led to inhibition of action potential firing. In synaptic terminals on deep cerebellar nuclei neurons, we found that photolysis of both IP3 and ATP led to GABA release. We propose that axonal IP3 receptors can inhibit action potential firing and increase neurotransmitter release, and that these effects are likely controlled by purinergic receptors. Altogether our results suggest a rich and diverse functional role of IP3 receptors in axons of mammalian neurons.

[Successful portal vein stent placement for chronic portal vein stenosis 5 years after pancreatoduodenectomy:a case report].

A 73-year-old man underwent pancreatoduodenectomy 5 years previously, and portal vein stenosis was observed immediately after surgery. A collateral vein with varices around the hepaticojejunostomy gradually developed. The patient experienced repeated episodes of melena that required transfusion. Enteroscopy confirmed varices around the hepaticojejunostomy, caused by portal vein stenosis, which was the source of intestinal bleeding. Varices were treated by placing an expandable metallic stent in the stenotic portal vein through a percutaneous transhepatic route. Although the portal vein stenosis was severe, the guidewire was successfully maneuvered into the superior mesenteric vein and stent placement was successful. Subsequently, the collateral vein disappeared and no further melena was observed.

Comparing the 14-mm uncovered and 10-mm covered metal stents in patients with distal biliary obstruction caused by unresectable pancreatic cancer: a multicenter retrospective study.

BACKGROUND: Endoscopic biliary drainage using metal stent (MSs) is an established palliative treatment for patients with unresectable malignant distal biliary obstruction (MDBO). However, a major drawback of MS is recurrent biliary obstruction (RBO). Uncovered MSs with a diameter of 14 mm (UMS-14) were developed to overcome this. We aimed to compare the clinical outcomes of UMS-14 with those of conventional covered MSs having a diameter of 10 mm (CMS-10). METHODS: Consecutive patients with MDBO caused by unresectable pancreatic cancer, who underwent UMS-14 or CMS-10 placement at two tertiary-care centers, were retrospectively examined according to the Tokyo Criteria 2014. RESULTS: Two hundred and thirty-eight patients who underwent UMS-14 (the UMS-14 group, n = 80) or CMS-10 (the CMS-10 group, n = 158) over a 62-month period were included. The technical and clinical success rates were similar between the two groups. RBO occurred in 20 (25%) and 59 (37%) patients of the UMS-14 and CMS-10 groups, respectively (p = 0.06). Median time till RBO was significantly longer in the UMS-14 group than in the CMS-10 group (not reached vs. 290 days, p = 0.04). Multivariate analysis revealed that CMS-10 placement was an independent risk factor for RBO (hazard ratio: 1.66, 95% confidence interval: 1.00-2.76). The incidence of early complications, including pancreatitis, and the overall survival (UMS-14 vs. CMS-10: 169 vs. 167 days, p = 0.83) were comparable between the two groups. CONCLUSIONS: UMS-14 stents were safe and effective for treating patients with MDBO secondary to unresectable pancreatic cancer. The insertion of UMS-14 is recommended, because it is less likely to get occluded as compared to CMS-10.

Can regular follow-up imaging contribute to the determination of appropriate timing of surgery in patients with undiagnosed mucinous cystic neoplasm? A multicenter retrospective study.

OBJECTIVE: Guidelines suggest that patients with undiagnosed pancreatic cystic lesions should be monitored despite a lack of evidence supporting surveillance for undiagnosed mucinous cystic neoplasms (MCNs). We aimed to investigate the pre- and post-operative clinical course of patients with MCN and the utility of follow-up for patients who were not diagnosed with MCN at initial examination. PATIENTS AND METHODS: This multicenter retrospective study enrolled 28 patients with resected pathology-proven MCN; 12 and 16 patients underwent surgery within and after 6 months from the initial examination (Groups A and B, respectively). Outcome measures included changes in imaging findings until surgery in Group B, pathological findings between both groups and differences in pathological findings between patients with and without regular follow-up imaging in Group B. RESULTS: In Group B, the median cyst size was 30 and 48 mm at the initial examination and immediately before surgery, respectively. The incidence of mural cysts, thickened walls and mural nodules were 25, 19 and 0%, respectively, at the initial examination and 69, 56 and 31%, respectively, immediately before surgery. There were no significant differences in the invasive carcinoma rates between Groups A and B (13 vs. 17%). Regular follow-up imaging was offered to Group B. Among these, invasive carcinoma was found in one patient exhibiting no recurrence. One patient without follow-up imaging had invasive carcinoma recurrence post-operatively. CONCLUSIONS: MCNs increased in size, and typical imaging findings appeared over time. For undiagnosed MCN, regular follow-up examination contributed to the determination of the appropriate surgical timing.

[A case of poorly differentiated pancreatic adenocarcinoma with spontaneous regression wherein retrospective rim enhancement findings were important for diagnosis].

A 66-year-old man with epigastric pain was admitted to our hospital for further evaluation of a pancreatic mass, as indicated on transabdominal ultrasonography performed by his family doctor. Using various imaging modalities, the 22-mm tumor was diagnosed as a cystic tumor with hemorrhagic necrosis. The tumor diameter reduced to 11mm over the course of 1 month. However, the tumor margin was irregular than that at the initial diagnosis, and circumferential rim enhancement was observed in equilibrium phase computed tomography images. Therefore, we diagnosed the patient with pancreatic ductal adenocarcinoma with a necrotic component. Distal pancreatectomy with splenectomy was performed, and the subsequent histological diagnosis was poorly differentiated adenocarcinoma. This case had an interesting course as described by the diagnostic images.

[A case of jejunal neuroendocrine carcinoma complicated with dermatomyositis].

A 65-year-old woman who had been diagnosed with dermatomyositis presented to the hospital with a small bowel mass. She had tested positive for fecal occult blood test and anemia at a medical checkup;therefore, computerized tomography (CT) was performed at the previous hospital and it had revealed thickening of the intestinal wall. Abdominal contrast-enhanced CT, single-balloon assisted enteroscopy, and biopsy led to a diagnosis of poorly differentiated jejunal adenocarcinoma. The patient underwent laparoscopic segmental resection of the jejunum with dissection of mesenteric lymph nodes. A histological examination revealed that the tumor was neuroendocrine carcinoma (NEC), large-cell type of the jejunum, pT3, pN0, sM0, and pStage IIA. Immunohistochemically, the NEC component was positive for chromogranin A and negative for neural cell adhesion molecule and synaptophysin. The MIB-1 index was 60%. Four courses of postoperative chemotherapy using cisplatin and etoposide were administered. The patient is currently doing well without any recurrence or metastasis. To the best of the author's knowledge, this is the first report of dermatomyositis associated with primary jejunal NEC.

Axonal GABAA receptors depolarize presynaptic terminals and facilitate transmitter release in cerebellar Purkinje cells.

KEY POINTS: GABAA receptors have been described in the axonal compartment of neurons; contrary to dendritic GABAA receptors, axonal GABAA receptors usually induce depolarizing responses. In this study we describe the presence of functional axonal GABAA receptors in cerebellar Purkinje cells by using a combination of direct patch-clamp recordings from the axon terminals and laser GABA photolysis. In Purkinje cells, axonal GABAA receptors are depolarizing and induce an increase in neurotransmitter release that results in a change of short-term synaptic plasticity. These results contribute to our understanding of the cellular mechanisms of action of axonal GABAA receptors and highlight the importance of the presynaptic compartment in neuronal computation. ABSTRACT: In neurons of the adult brain, somatodendritic GABAA receptors (GABAA Rs) mediate fast synaptic inhibition and play a crucial role in synaptic integration. GABAA Rs are not only present in the somatodendritic compartment, but also in the axonal compartment where they modulate action potential (AP) propagation and transmitter release. Although presynaptic GABAA Rs have been reported in various brain regions, their mechanisms of action and physiological roles remain obscure, particularly at GABAergic boutons. Here, using a combination of direct whole-bouton or perforated patch-clamp recordings and local GABA photolysis in single axonal varicosities of cerebellar Purkinje cells, we investigate the subcellular localization and functional role of axonal GABAA Rs both in primary cultures and acute slices. Our results indicate that presynaptic terminals of PCs carry GABAA Rs that behave as auto-receptors; their activation leads to a depolarization of the terminal membrane after an AP due to the relatively high cytoplasmic Cl- concentration in the axon, but they do not modulate the AP itself. Paired recordings from different terminals of the same axon show that the GABAA R-mediated local depolarizations propagate substantially to neighbouring varicosities. Finally, the depolarization mediated by presynaptic GABAA R activation augmented Ca2+ influx and transmitter release, resulting in a marked effect on short-term plasticity. Altogether, our results reveal a mechanism by which presynaptic GABAA Rs influence neuronal computation.

Ca(2+) current facilitation determines short-term facilitation at inhibitory synapses between cerebellar Purkinje cells.

KEY POINTS: Short-term facilitation takes place at GABAergic synapses between cerebellar Purkinje cells (PCs). By directly patch clamp recording from a PC axon terminal, we studied the mechanism of short-term facilitation. We show that the Ca(2+) currents elicited by high-frequency action potentials were augmented in a [Ca(2+) ]i -dependent manner. The facilitation of synaptic transmission showed 4-5th power dependence on the Ca(2+) current facilitation, and was abolished when the Ca(2+) current amplitude was adjusted to be identical. Short-term facilitation of Ca(2+) currents predominantly mediates short-term facilitation at synapses between PCs. ABSTRACT: Short-term synaptic facilitation is critical for information processing of neuronal circuits. Several Ca(2+) -dependent positive regulations of transmitter release have been suggested as candidate mechanisms underlying facilitation. However, the small sizes of presynaptic terminals have hindered the biophysical study of short-term facilitation. In the present study, by directly recording from the axon terminal of a rat cerebellar Purkinje cell (PC) in culture, we demonstrate a crucial role of [Ca(2+) ]i -dependent facilitation of Ca(2+) currents in short-term facilitation at inhibitory PC-PC synapses. Voltage clamp recording was performed from a PC axon terminal visualized by enhanced green fluorescent protein, and the Ca(2+) currents elicited by the voltage command consisting of action potential waveforms were recorded. The amplitude of presynaptic Ca(2+) current was augmented upon high-frequency paired-pulse stimulation in a [Ca(2+) ]i -dependent manner, leading to paired-pulse facilitation of Ca(2+) currents. Paired recordings from a presynaptic PC axon terminal and a postsynaptic PC soma demonstrated that the paired-pulse facilitation of inhibitory synaptic transmission between PCs showed 4-5th power dependence on that of Ca(2+) currents, and was completely abolished when the Ca(2+) current amplitude was adjusted to be identical. Thus, short-term facilitation of Ca(2+) currents predominantly mediates short-term synaptic facilitation at synapses between PCs.

Long-term potentiation of inhibitory synaptic transmission onto cerebellar Purkinje neurons contributes to adaptation of vestibulo-ocular reflex.

Synaptic plasticity in the cerebellum is thought to contribute to motor learning. In particular, long-term depression (LTD) at parallel fiber (PF) to Purkinje neuron (PN) excitatory synapses has attracted much attention of neuroscientists as a primary cellular mechanism for motor learning. In contrast, roles of plasticity at cerebellar inhibitory synapses in vivo remain unknown. Here, we have investigated the roles of long-lasting enhancement of transmission at GABAergic synapses on a PN that is known as rebound potentiation (RP). Previous studies demonstrated that binding of GABAA receptor with GABAA receptor-associated protein (GABARAP) is required for RP, and that a peptide that blocks this binding suppresses RP induction. To address the functional roles of RP, we generated transgenic mice that express this peptide fused to a fluorescent protein selectively in PNs using the PN-specific L7 promoter. These mice failed to show RP, although they showed no changes in the basal amplitude or frequency of miniature IPSCs. The transgenic mice also showed no abnormality in gross cerebellar morphology, LTD, or other excitatory synaptic properties, or intrinsic excitability of PNs. Next, we attempted to evaluate their motor control and learning ability by examining reflex eye movements. The basal dynamic properties of the vestibulo-ocular reflex and optokinetic response, and adaptation of the latter, were normal in the transgenic mice. In contrast, the transgenic mice showed defects in the adaptation of vestibulo-ocular reflex, a model paradigm of cerebellum-dependent motor learning. These results together suggest that RP contributes to a certain type of motor learning.

Opposite regulation of inhibitory synaptic plasticity by α and ß subunits of Ca(2+)/calmodulin-dependent protein kinase II.

Induction of several forms of synaptic plasticity, a cellular basis for learning and memory, depends on the activation of Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII). CaMKII acts as a holoenzyme consisting of α and ß subunits (α- and ßCaMKII). However, it remains elusive how the subunit composition of a CaMKII holoenzyme affects its activation and hence synaptic plasticity. We addressed this issue by focusing on long-term potentiation (LTP) at inhibitory synapses on cerebellar Purkinje neurons (PNs) (called rebound potentiation, RP). The contribution of each subunit to RP was examined by selective knock-down or overexpression of that subunit. Electrophysiological recording from a rat cultured PN demonstrated that ßCaMKII is essential for RP induction, whereas αCaMKII suppresses it. Thus, RP was negatively regulated due to the greater relative abundance of αCaMKII compared to ßCaMKII, suggesting a critical role of CaMKII subunit composition in RP. The higher affinity of ßCaMKII to Ca(2+)/CaM compared with αCaMKII was responsible for the predominant role in RP induction. Live-cell imaging of CaMKII activity based on the Förster resonance energy transfer (FRET) technique revealed that ßCaMKII enrichment enhances the total CaMKII activation upon a transient conditioning depolarization. Taken together, these findings clarified that α- and ßCaMKII oppositely regulate CaMKII activation, controlling the induction of inhibitory synaptic plasticity in a PN, which might contribute to the adaptive information processing of the cerebellar cortex.

Plexiform schwannoma of the rectum.

Plexiform schwannoma is a benign peripheral nerve sheath tumor composed exclusively of Schwann cells arranged in a plexiform pattern. Most plexiform schwannomas are skin tumors and visceral localization is very rare. To our knowledge, there are six cases localized in visceral organs. We describe herein the first known case of plexiform schwannoma of the rectum resected by endoscopic submucosal dissection (ESD). A 77-year-old woman presented with a short history of anal pain. Sigmoidoscopy demonstrated a submucosal tumor, 20 mm in diameter, of the rectum below the peritoneal reflection (Rb). We resected the tumorby ESD. The tumor consisted of multiple white nodules in the submucosal layer. Microscopic examination revealed that the tumor was composed mainly of Antoni A tissue, compatible with conventional schwannoma. Immunohistochemically, the tumor was positive for S-100, and negative for α-smooth muscle actin, c-kit and CD-34. No evidence of recurrence has been found in 2 years of follow up.

Investigating morphological changes in a simple mucinous cyst during the follow-up period: a case report.

A 64-year-old man was referred to our department after a small pancreatic cystic lesion was discovered on computed tomography performed to assess choledocholithiasis. Multiple standard imaging modalities, including endoscopic ultrasound (EUS), failed to reveal pancreatic masses, wall thickening, or mural nodules. Consequently, a benign pancreatic cystic lesion was suspected, and the patient underwent biannual imaging studies including rotating magnetic resonance imaging and EUS. Six years after the initial detection of the pancreatic cyst, wall thickening was observed, leading to a shortened observation period of once every 3 months. After 6.5 years, hypoechoic area surrounding the cyst, which could be interpreted as thickening of the cyst wall was observed, prompting distal pancreatectomy due to the suspicion of malignant disease. The histopathological examination revealed a unilocular mucinous cyst with a single layer of cuboidal cells and low-grade dysplasia. A fibrous proliferation of the polycystic stroma and no ovarian-type stroma was observed. Malignant cells were absent from the cystic epithelium and stroma. The final histopathological diagnosis was a simple mucinous cyst of the pancreatic tail.

Safety and efficacy of atezolizumab plus bevacizumab combination therapy in patients with unresectable hepatocellular carcinoma undergoing dialysis: a case series.

Three patients aged 79, 75, and 81 years with unresectable hepatocellular carcinoma (HCC) and undergoing maintenance hemodialysis were treated with a combination of atezolizumab and bevacizumab. The patients, respectively, received their 22nd, 2nd, and 4th treatment cycles, and one achieved long-term stable disease. No serious adverse events, including immune-related adverse events, were observed in any patient. Remarkable progress has been made in chemotherapy for cancer; however, the efficacy and safety of chemotherapy in patients undergoing hemodialysis have not been adequately elucidated. This report provides novel insights into the feasibility and outcomes of atezolizumab and bevacizumab combination therapy in patients with HCC undergoing hemodialysis, highlighting its potential as a viable treatment option with manageable side effects.