pH-induced conformational change of natural cyclic lipopeptide surfactin and the effect on protease activity.

The cyclic lipopeptide surfactin (SF) is one of the promising environmental friendly biosurfactants abundantly produced by microorganisms such as Bacillus subtilis. SF shows excellent surface properties at various pH, together with lower toxicity and higher biodegradability than commonly used petroleum-based surfactants. However, the effect of the dissociation degree of SF on self-assembly is still incompletely understood, even though two acidic amino acid residues (Asp and Glu) are known to influence eventual surface and biological functions. Here, we report changes in the secondary structure of SF induced by increased pH, and the effect on protease activity. We found that the ß-sheet and ß-turn formation of SF are significantly enhanced through increased dissociation of Asp and Glu as revealed by a titration experiment of SF solution to estimate apparent pK1 and pK2 values together with circular dichroism spectroscopy. We also studied the activity of the common detergent enzyme subtilisin in SF solution at above its pK2 (pH 7.6) to understand the role of the dissociation degree in the interaction with the protein. The mixing of SF having a unique cyclic topological feature with subtilisin suppressed the decrease in protease activity observed in the presence of synthetic surfactants such as sodium dodecyl sulfate and polyoxyethylene alkyl ether. Thus, SF has great potential for use in laundry detergent formulations, to improve the stability and reliability of detergent enzymes.

Management for pancreatolithiasis: a Japanese multicenter study.

OBJECTIVES: A Japanese multicenter study of pancreatolithiasis was performed to investigate its clinical features and determine treatment strategies for pancreatolithiasis. METHODS: A retrospective study was performed on 916 patients managed in 34 institutions for a period of more than 5 years. RESULTS: The treatment methods were extracorporeal shock wave lithotripsy (ESWL) in 479 patients, surgery in 133, and endoscopy alone in 68. Fragmentation of stones after ESWL was achieved in 92.4% of the patients. However, complete stone clearance was achieved in 49.4% of the patients after ESWL alone. The complete stone clearance rate was lower after ESWL than after endoscopy (87.9%). The incidence of early complications was significantly higher after surgery (13.3%) than after ESWL (6.1%). The frequencies of total stone recurrence after ESWL (22.5%) and endoscopy (12.0%) were significantly higher than that after surgery (1.5%). After ESWL (17.6%), abdominal pain recurred significantly more frequently than after surgery (2.2%). Stones and abdominal pain most often recurred within 3 years after ESWL and endoscopy. CONCLUSIONS: First-line treatment of pancreatic stones should be ESWL alone or with endoscopy because of its minimal invasiveness and low incidence of early complications. Surgery should be performed on patients in whom ESWL and endoscopy failed.

Gene cloning, overproduction, and characterization of thermolabile alkaline phosphatase from a psychrotrophic bacterium.

The gene encoding alkaline phosphatase from the psychrotrophic bacterium Shewanella sp. SIB1 was cloned, sequenced, and overexpressed in Escherichia coli. The recombinant protein was purified and its enzymatic properties were compared with those of E. coli alkaline phosphatase (APase), which shows an amino acid sequence identity of 37%. The optimum temperature of SIB1 APase was 50 degrees C, lower than that of E. coli APase by 30 degrees C. The specific activity of SIB1 APase at 50 degrees C was 3.1 fold higher than that of E. coli APase at 80 degrees C. SIB1 APase lost activity with a half-life of 3.9 min at 70 degrees C, whereas E. coli APase lost activity with a half-life of >6 h even at 80 degrees C. Thus SIB1 APase is well adapted to low temperatures. Comparison of the amino acid sequences of SIB1 and E. coli APases suggests that decreases in electrostatic interactions and number of disulfide bonds are responsible for the cold-adaptation of SIB1 APase.

Treatment of pancreatic stones with extracorporeal shock wave lithotripsy: results of a multicenter survey.

OBJECTIVES: A retrospective multicenter survey was performed to evaluate the efficacy of extracorporeal shock wave lithotripsy (ESWL) as a treatment of pancreatic stones. METHODS: A survey was sent to 11 institutions belonging to the Japanese Association of Extracorporeal Shock Wave Lithotripsy in Digestive Diseases, and data were collected on 555 patients who underwent ESWL for pancreatic stones between January 1990 and September 2002. The male:female ratio was 5.2:1, and the mean age was 52.5 years. The etiology was alcohol related in 425 patients (76.6%) and idiopathic in 111 patients (20.0%); 204 patients (36.8%) had a single stone and 470 patients (84.7%) were symptomatic. RESULTS: Mean frequency of the procedure was 5.0 times (range, 1-29). Fragmentation of stones was achieved in 513 patients (92.4%), and the complete stone clearance rate after ESWL alone or in combination with interventional endoscopy was 72.6%. Symptom relief was achieved in 428 (91.1%) of 470 patients. Thirty-five patients (6.3%) developed complications, including 30 patients (5.4%) who developed acute pancreatitis. Five hundred four (90.8%) patients were followed for a mean of 44.3 months, during which 122 (22.0%) suffered stone recurrence (mean time to recurrence, 25.1 months). Twenty-two (4.1%) of the 504 patients who were followed required surgery. Pancreatic exocrine function improved in 65 patients (38.0%), was unchanged in 49 patients (28.7%), and progressed in 57 patients (33.3%). Pancreatic endocrine function improved in 44 patients (24.3%), was unchanged in 85 patients (47.0%), and progressed in 52 patients (28.7%). CONCLUSION: ESWL is the treatment of choice for clearing pancreatic stones.

A giant retention cyst of the pancreas (cystic dilatation of dorsal pancreatic duct) associated with pancreas divisum.

We describe a rare case of pancreas divisum associated with a giant retention cyst (cystic dilatation of the dorsal pancreatic duct), presumably formed following obstruction of the minor papilla. The patient was treated by pancreatico(cysto)jejunostomy. A 50-year-old man was admitted with complaints of increasing upper abdominal distension and body weight loss. There was no previous history of pancreatitis, gallstones, drinking, or abdominal injury. An elastic-hard tumor-like resistance was palpable in the upper abdomen. Computed tomography and ultrasound (US) examinations revealed a giant cystic lesion expanding from the pancreas head to the tail. Endoscopic retrograde cholangiopancreatography findings showed a looping pancreatic duct which drained only the head and uncinate process of the pancreas to the main papilla. A US-guided puncture to the cystic lesion revealed that the lesion continued to the main pancreatic duct in the tail of pancreas. The lesion was connected to a small cystic lesion, which was located inside the minor papilla, and ended there. The amylase level in liquid aspirated from the cyst was 37 869 IU/l, and the result of cytological examination of the liquid showed class II. A pancreatico(cysto)jejunostomy was performed, with the diagnosis being pancreas divisum associated with a retention cyst following obstruction of the minor papilla. The histological findings of a specimen from the cyst wall revealed that the wall was a pancreatic duct covered with mildly inflammatory duct epithelium; there was no evidence of neoplasm. The patient is currently well, and a CT examination 2 years after the operation showed disappearance of the cyst and normal appearance of the whole pancreas.