ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

With the cloning of complementary DNAs encoding the receptors for the most physiologically important pancreatic secretagogues, the past year has provided resources key in understanding the proximal steps in stimulus-secretion coupling in the acinar cell. In addition, new acinar cell agonists have been identified, the importance of neural regulation of acinar cell function has been appreciated, the regulatory roles of serine-threonine and tyrosine protein phosphorylation have been expanded, and the description of numerous small guanine nucleotide—binding proteins in various compartments of the acinar cell has begun. In addition to these biochemical and physiologic advances, sensitive methodologies to define the spatial and temporal events that occur in the cell have been established. These findings should contribute to better understanding the molecular basis of signal transduction and integration of responses in polarized secretory epithelia.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Electrophysiological studies have determined the fundamental mechanisms underlying fluid and electrolyte transport by the pancreatic duct cell. Stimulated fluid and bicarbonate secretion by these cells involves activation of an apical membrane chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR). The intracellular protons that accumulate during this process are extruded basolaterally, possibly by proton pumps inserted into the plasma membrane. Although secretion is clearly regulated by secretin and the cyclic AMP pathway, it is apparent that other agents (acetylcholine, bombesin, and substance P), acting through calcium and other pathways, can also regulate the process. With the exception of CFTR, however, the sites of regulation have not been completely established. As a target of both protein kinase A and protein kinase C, CFTR is one potential site for regulation by different signaling pathways. Furthermore, CFTR may have intracellular functions, raising the possibility that its activation affects additional duct cell processes.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Recent experimental studies in animals and humans provide strong evidence that cholecystokinin acts via cholinergic pathways to mediate pancreatic secretion of enzymes and bicarbonate. These findings revolutionize our current concept of the mechanism of action of cholecystokinin on pancreatic exocrine secretion. In addition, it also appears that depending on the stimulants, the release of cholecystokinin from cholecystokinin cells in the upper intestinal mucosa may be modulated by cholinergic input. Studies in rats examined the role of intraluminal proteases and bile acid in the release of cholecystokinin. Physiologic concentrations of bile acid inhibit cholecystokinin release by maintaining luminal trypsin activities, whereas higher concentrations of bile acid inhibit cholecystokinin secretion independent of luminal protease activities. This further illuminates the mechanism responsible for feedback regulation of pancreatic secretion. Human studies support that both somatostatin and the adrenergic pathway modulate interdigestive pancreatic enzyme secretion, indicating complex neural and hormonal mediation of basal pancreatic secretion. A number of new peptides have been reported to modulate pancreatic secretion and growth, and their mechanisms of action were examined and discussed. This suggests that the exocrine pancreas is under complex neurohormonal control.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Investigators employ animal models of pancreatitis for two principal reasons: to answer questions regarding the pathophysiology and cellular biology of the disease and to test novel treatment modalities. The past year has seen progress in both fields. Factors that determine vascular blood flow and coagulation have been the focus of much attention. Premature protease activation, generation of oxygen radicals, and ethanol toxicity have been investigated to characterize further their roles in triggering pathophysiologic events. New models that mimic a gallstone-induced or autoimmune pathogenesis of pancreatitis have emerged or gained ground. The mechanisms involved in pancreatic regeneration remain a subject of ongoing controversy.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Ascariasis is an important cause of acute pancreatitis in endemic areas, as are drugs such as dideoxyinosine and pentamidine in patients with HIV infection. Pancreatic exocrine function is substantially depressed early in acute pancreatitis but generally returns to normal. To estimate prognosis, new predictors and predictor systems continue to be developed, although no single predictor or system appears clearly superior. Recent studies evaluating somatostatin or its analogues in the treatment or prevention of acute pancreatitis have yielded disappointing results. Early endoscopic retrograde cholangiopancreatography reduces the frequency of biliary sepsis in gallstone pancreatitis but does not affect the course of pancreatitis, whereas endoscopic stenting of the minor papilla reduces the likelihood of recurrence of acute pancreatitis in patients with pancreas divisum.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Patients with severe abdominal pain secondary to chronic pancreatitis may have minimal or no radiographic abnormalities (as shown by ultrasound, computed tomography, or endoscopic retrograde cholangiopancreatography), yet have abnormal exocrine function and histologic lesions. Pancreatic interstitial pressure may be increased without main duct dilation. Diffuse small duct disease may be responsible for abdominal pain. Endoscopic procedures for benign pancreatic disease remain experimental therapies and may cause permanent damage to the pancreas. No double-blind, placebo-controlled studies are available to demonstrate that these procedures relieve abdominal pain in chronic pancreatitis patients. Octreotide administered perioperatively prevents complications caused by pancreatic surgery. The standard aggressive interventional approach to the management of pancreatic pseudocysts may have to be reassessed because recent evidence suggests that conservative, expectant management may be the treatment of choice for many patients. This review focuses on recent observations concerning the pathogenesis, pathophysiology, diagnosis, and management of patients with chronic pancreatitis related to alcohol and cystic fibrosis, or idiopathic in nature.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Attempts to treat acute pancreatitis with protease inhibitors and secretion inhibitors have been unsuccessful. Endoscopic therapy for acute pancreatitis is beneficial because it reduces the incidence of biliary sepsis. Pancreas divisum may be treated successfully by endoscopic placement of a dorsal duct stent. Asymptomatic pseudocysts can be safely observed rather than drained even if they persist for more than 6 weeks. Extended pancreatic resections may improve the survival rate for patients with locally invasive cancer. Pylorus-preserving resection may be less appropriate than the standard Whipple's resection for pancreatic head carcinomas. Endoscopic ultrasonography may be useful in localizing islet cell tumors. Combined pancreas and kidney transplantation is associated with a better outcome than is isolated pancreas allotransplantation in diabetic patients.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Progress is being made in understanding the pathogenesis of pancreatic cancer at the molecular level. It has been demonstrated that growth factor receptors can accelerate the growth of tumors in culture, but clinical trials with various antagonists have failed to improve the therapy for this disease. Studies have been presented this year showing better outcomes from surgical approaches if diagnosis is made earlier. Early diagnosis by standard means such as computed tomography scanning remain elusive. Many serum markers for pancreatic carcinoma have been identified; however, although useful for following the course of the disease, these markers remain nonspecific unless serum levels are exceptionally elevated. Endoscopic biliary stenting has great potential in obviating laparotomy in patients in need of palliation but is limited by the high occlusion rate of the stents.

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID

ISSN:0267-1379    

出版商:OVID    

年代:1993

数据来源: OVID