Investigation on substrate specificity and catalytic activity of serine protease neuropsin.

Neuropsin is one of serine proteases mainly found at the hippocampus and the amygdala, where it contributes to the long-term potentiation and memory acquisition by rebuilding of synaptic connections. Despite of the importance of neuropsin, the substrate specificity and regulation mechanisms of neuropsin have been unclear. Thus, we investigated the substrate specificity and the catalytic activity of neuropsin by the protein-ligand docking and molecular dynamics (MD) simulations and succeeded to reproduce the trend of the experimental results. Our study revealed that the substrate specificity and the activity of neuropsin depended on multiple factors: the substrate charge, the substrate orientation, the hydrogen bond network within the catalytic triad and the substrate, and the formation of the oxyanion hole. The apo neuropsin was not reactive without proper alignment of catalytic triad. The substrate binding induced the reactive alignment of catalytic triad. Then the substrate-neuropsin interaction forms the oxyanion hole that stabilizes the transition state and reduces the free-energy barrier of the following scission reaction.

[A case of hepatic encephalopathy successfully treated by antegrade glycerin enema through percutaneous endoscopic cecostomy].

A 76-year-old man with liver cirrhosis, a chronic defecation disorder and a refractory hepatic encephalopathy was hospitalized for the hepatic encephalopathy. The encephalopathy quickly improved upon treatment, but a high level of serum ammonia persisted. We inserted a percutaneous endoscopic cecostomy at the cecum and an antegrade glycerin enema through it to treat the chronic defecation disorder, which was a deteriorative factor of the hepatic encephalopathy. After the aforementioned procedure, the chronic defecation disorder improved and the serum ammonia level dramatically decreased. The patient continued the antegrade glycerin enema at home, and serum ammonia values remained low in comparison to levels measured prior to the administration of treatment. The subject has not experienced a recurrence of hepatic encephalopathy.

[A case of secondary gastric wall abscess due to perforation from advanced colonic cancer successfully treated by endoscopic endoprostesis using endoscopic retrograde biliary drainage tube].

A 44 year-old man was admitted to our hospital because of severe left upper abdominal pain and high fever. Blood examinations revealed high levels of white blood cell count and CRP. An abdominal enhanced CT scan showed a low-density mass with an enhanced margin at the posterior side of the gastric body, and an irregular mass nearby at the transverse colon. We diagnosed a gastric wall abscess due to perforation from advanced colonic cancer and performed endoscopic drainage and endoprostesis by ERBD tube insertion into the abscess through the gastric wall. After the procedure, the clinical symptoms and laboratory data improved quickly, and we could continue further examinations and proceed safety with the treatment plan. To our knowledge, this is the first reported case of a gastric wall abscess due to penetration by gastrointestinal tract cancer which was treated with endoscopic endoprostesis.

Different effects of dexamethasone and the nitric oxide synthase inhibitor L-NAME on caerulein-induced rat acute pancreatitis, depending on the severity.

Effects of dexamethasone and N(G)-nitro-L-arginine methyl ester (L-NAME), the nitric oxide (NO) synthase inhibitor, on caerulein-induced acute pancreatitis were examined in rats. Acute pancreatitis was induced by caerulein (20 mug/kg, s.c.) given repeatedly 2 or 4 times every hour, and serum amylase levels, pancreas weight and myeloperoxidase (MPO) activity were measured 6 h after the first injection of caerulein. Dexamethasone (3 mg/kg) and L-NAME (30 mg/kg) were administered p.o. 30 min before the first injection of caerulein. Caerulein caused moderate or severe pancreatitis, depending on the times of injections, resulting in different degrees of increase in serum amylase levels and pancreas weight, and the marked elevation of MPO activity was observed only after injections of caerulein given 4 times per hour. Both dexamethasone and L-NAME suppressed the severity of pancreatits, yet the effect of L-NAME as compared with dexamethasone was more potent against mild pancreatitis but less potent against severe pancreatitis. These results suggest that caerulein-induced acute pancreatitis shows different responsiveness to L-NAME and dexamethasone, depending on the severity; the former is more effective against pancreatitis with less inflammation, while the latter is more effective against pancreatitis with severe inflammation. It is assumed that endogenous NO may be involved in oedema formation as the early event in the development of acute pancreatitis.

Initial experience with a new peroral electronic pancreatoscope with an accessory channel.

BACKGROUND: A peroral electronic pancreatoscope was previously developed to improve visualization of the pancreatic duct, but this instrument had no accessory channel. METHODS: A new peroral electronic pancreatoscope (2.6-mm external diameter) with an accessory channel (0.5 mm) was developed. Peroral pancreatoscopy or cholangioscopy was performed with this new instrument in 11 patients with various pancreatobiliary diseases. The clinical utility of the new peroral electronic pancreatoscope was assessed, and visualization with this new instrument was compared with that of the prototype. RESULTS: The resolution of the two instrument systems was nearly equal, with that provided by the new peroral electronic pancreatoscope being slightly better. The new peroral electronic pancreatoscope was inserted successfully into the pancreatic or bile duct in 9 of the 11 patients (82%). Observation of a predetermined target and juice collection with direct visualization was successful in 8 of the 9 patients (89%). CONCLUSIONS: The new peroral electronic pancreatoscope with an accessory channel was useful for clinical diagnosis of various pancreatobiliary diseases. Visualization is excellent. Pancreatic juice and other samples can be collected under direct visualization.

Prophylactic effect of restraint stress on cerulein-induced pancreatitis in rats: role of endogenous glucocorticoids.

Stress is reportedly known to affect the severity of acute pancreatitis, yet the effect has not been without controversy. We investigated the influence of restraint stress on cerulein-induced pancreatitis, especially in relation to endogenous glucocorticoids. In the present study, restraint stress significantly reduced the increase in serum amylase levels but not pancreas weight induced by cerulein, the effect being totally antagonized by pretreatment with mifepristone, a glucocorticoid receptor antagonist. The changes induced by cerulein were prevented by dexamethasone in a dose-dependent manner. Histologically, restraint stress suppressed the intralobular edema, similar to a low dose of dexamethasone, while the latter at a high dose prevented not only the intralobular but also the interlobular edema. These results suggest that restraint stress exerts a beneficial influence on the cerulein-induced pancreatitis, mainly mediated by endogenous glucocorticoids, and it is assumed that short-term steroid therapy has a potential of clinical application for treatment of pancreatitis.

A case of pseudotumorous pancreatitis that presented unique pancreatoscopic findings with the peroral electronic pancreatoscope.

A 49-year-old man was admitted to Hospital of Kyoto Prefectural University of Medicine complaining of epigastralgia and jaundice. There was a tumor (approximately 30 mm) in the pancreatic head on ultrasound, computed tomography and magnetic resonance imaging. Endoscopic retrograde cholangiopancreatography revealed a stenosis of the main pancreatic duct in the head of the pancreas. Pancreatoscopy with the peroral electronic pancreatoscope (PEPS) was performed to differentiate between pseudotumorous pancreatitis (PTP) and pancreatic carcinoma. The PEPS showed non-erosive erythematous mucosa around the stenosis and this unique finding was different from that of pancreatic carcinoma. Pylorus-preserving pancreatoduodenectomy was performed under the possible diagnosis of carcinoma. As a result, the diagnosis of PTP was confirmed histopathologically. At present, the diagnosis of PTP is difficult because of similar findings with carcinoma in various imaging procedures. However, we consider that detailed observation and accurate morphologic assessment of the main pancreatic duct with the PEPS has the possibility of differentiating PTP from pancreatic carcinoma.

Electronic pancreatoscopy for the diagnosis of pancreatic diseases.

OBJECTIVES: Diagnostic pancreatoscopy was performed in 56 patients using the newly developed peroral electronic pancreatoscope (PEPS). The diagnostic value of the PEPS for pancreatic diseases was evaluated. METHODS: The PEPS (external diameter = 2.1 mm, bidirectional tip deflection) was developed with a minute 50,000-pixel interline charge-coupled device. Pancreatoscopy was performed by means of an endoscopic retrograde approach without sphincterotomy. The cases examined were normal (three), chronic pancreatitis (32), pancreatic cancer (eight), and intraductal papillary mucinous tumors (13). RESULTS: Of the 56 cases, 42 (75%) were adequately seen. In normal cases, fine capillary vessels were clearly visualized on the smooth whitish-pink mucosa. Findings in chronic pancreatitis included protein plugs, calcified stones, rough whitish mucosa, scar formation, edema, erythema, and indistinct capillary appearance. All the stenoses of chronic pancreatitis could be differentiated from those of pancreatic cancer with the PEPS. In the pancreatic cancer cases, all patients had stenoses or duct cutoffs; most cases had friable mucosa with erythema and erosive changes, and a single patient had a compressed pancreatic duct wall covered with normal epithelium. In the cases of intraductal papillary mucinous tumors, papillary tumors were visualized with extreme clarity. In the case of adenocarcinoma, the PEPS revealed oval-shaped tumors with spotty redness or villous tumors with dilation of capillary vessels. Moderate acute pancreatitis was recognized after pancreatoscopy in one of the 56 cases (1.8%). CONCLUSIONS: Electronic pancreatoscopy with the PEPS is feasible in most patients and technically safe, and improves diagnostic yield over conventional pancreatoscopy.