Organic matrix of pancreatic stones associated with nutritional pancreatitis

In recent studies performed on pancreatic stones from patients with alcoholic pancreatitis, a novel secretory protein was identified: the pancreatic stone protein (PSP Mr 14,000). This protein suppresses CaCO3 precipitation, and could therefore stabilize normally supersaturated pancreatic juice. Crystallographic analysis of stones from patients with nutritional pancreatitis (NP), as well as alcoholic pancreatitis (AP), revealed that the main constituent was calcite (CaCO3). In the present study, we investigated the organic matrix of NP stones. In the 14 cases studied, the organic matrix was rendered soluble after mineral dissolution with EDTA + citrate. Analysis of the isolated matrix revealed the presence of one major protein (Mr 14,000), and of a minor protein (Mr 30,000), which is in fact an aggregate form of the 14,000 Mr protein. Using PSP antibodies, complete immunological identity was found between PSP, the immunoreactive form of PSP present in nonactivated pancreatic juice, and the protein matrix of NP stones. Moreover, protein matrix of NP stones also inhibited the nucleation of CaCO3 crystal, and decreased their growth rate in vitro. The presence of PSP in all AP and NP stones suggests that it plays a key role in stone formation during the course of chronic pancreatitis. These results also suggest the existence of some pathophysiological links between these two apparently different etiological forms of calcifying pancreatitis.     

Air-stable droplet interface bilayers on oil-infused surfaces

Droplet interface bilayers are versatile model membranes useful for synthetic biology and biosensing; however, to date they have always been confined to fluid reservoirs. Here, we demonstrate that when two or more water droplets collide on an oil-infused substrate, they exhibit noncoalescence due to the formation of a thin oil film that gets squeezed between the droplets from the bottom up. We show that when phospholipids are included in the water droplets, a stable droplet interface bilayer forms between the noncoalescing water droplets. As with traditional oil-submerged droplet interface bilayers, we were able to characterize ion channel transport by incorporating peptides into each droplet. Our findings reveal that droplet interface bilayers can function in ambient environments, which could potentially enable biosensing of airborne matter.Inspired by the pitcher plant (1), it was recently found that nano/microstructured hydrophobic substrates can be impregnated with lubricating fluids to create slippery surfaces for droplets (2–5). In contrast to dry, superomniphobic surfaces (6), lubricant-infused surfaces demonstrate stable liquid repellency at extreme pressures and temperatures (5, 7), are self-healing to mechanical damage (5), and their wettability and optical properties can be tuned (7, 8). A wide variety of applications are being explored for lubricant-infused surfaces, such as enhancing condensation heat transfer (9, 10), self-cleaning (11), fog harvesting (12), and omniphobic textiles (13), or minimizing ice nucleation (14, 15), ice adhesion (16, 17), and biofouling (18). Though previous studies have characterized the dynamics and possible wetting states of isolated droplets on lubricant-infused surfaces (5, 19–22), the interactive behavior of multiple droplets has not been reported.For the more traditional scenario of water droplets completely submerged in a reservoir of immiscible fluid, the physics of droplet–droplet interactions are well known. Water droplets submerged in crude oil can exhibit stable noncoalescence; this is because the crude oil contains surface-active components, such as resins and asphaltenes, which congregate at the droplet interfaces (23). When amphiphilic phospholipids are introduced into an oil reservoir containing water droplets, droplet interface bilayers (DIBs) can form between adjacent water droplets (24, 25). Recently, DIBs have emerged as an ideal model membrane system due to attractive features such as durability (26, 27), tunable size and curvature (28–30), deformability (31), facile electrical characterization of ion channels (32–35), the option to introduce asymmetry into the system (36), and droplet interchangeability (26, 32). In the absence of any stabilizing agents, water droplets colliding in an immiscible fluid will exhibit coalescence when their interaction time exceeds the time required to drain the film of fluid trapped between the droplets (37, 38). Droplet collision is typically controlled by applying a constant force (i.e., gravity) (39, 40), constant approach velocity (41, 42), or constant flow rate (43, 44). For experimental studies in pure oil baths, the time required for colliding water droplets to exhibit film rupture and coalesce typically ranges from 10⁻³ to 10² s, depending on parameters such as oil viscosity, droplet size, and the flow field (40, 42–44).Here, we show that water droplets in an ambient environment exhibit noncoalescence when colliding on an oil-infused surface, even in the absence of any surfactants. This phenomenon is due to the oil meniscus that surrounds each water droplet; when the oil menisci of neighboring droplets overlap, the menisci spontaneously merge together to minimize their surface energies and an oil film is squeezed upward to form a barrier between the colliding droplets. Though droplet coalescence will eventually occur due to film drainage, the time required for film rupture is several hours for moderate-viscosity [∼100 centistokes (cSt)] oils and is 1–3 orders of magnitude longer compared with droplets submerged in an oil bath (40, 42–44). These findings should refine the understanding of using oil-infused substrates for processes involving droplet–droplet interactions, such as condensation (9, 10) and fog harvesting (12).When incorporating amphiphilic phospholipids into the water droplets, we demonstrate that the thinning oil membrane between noncoalescing droplets gets replaced by a stable lipid bilayer, somewhat analogous to the formation of a black lipid membrane in an aperture painted with oil (45). To our knowledge, this is the first report of producing droplet interface bilayers in an ambient environment. We show that air-stable DIBs still allow for the robust electrical characterization of ion channels inserted in the lipid bilayer. Previously, it has been demonstrated that black lipid membranes or DIBs can be used for biosensing (46–50), light sensing (26), microscale biobatteries (26), electrical circuits (51, 52), and engineering tissue-like material (53). However, these suspended lipid bilayers have always been confined to fluid reservoirs (25, 45). We suggest that our air-stable DIBs will allow for an unprecedented degree of control regarding the fabrication, manipulation, transportation, and utilization of functional droplet networks.     

Pancreas divisum is a probable cause of acute pancreatitis: a report of 137 cases

The incidence of pancreas divisum (PD) was evaluated in a retrospective series of 1,825 successful consecutive ERCPs. One hundred thirty-seven pancreas divisums (7.5%) were found in 80 males and 57 females at a mean age of 49.2 years. The ventral ducts were visualized in 82.5% and the dorsal ducts in 74.1% of attempted cannulations of the minor papilla. Pancreas divisum was significantly more frequent in patients presenting with acute idiopathic pancreatitis (50.0%) or acute biliary pancreatitis (23.7%) than in controls or in the general population. This difference was not found in acute pancreatitis due to other etiologies. Acute pancreatitis associated with PD is generally recurrent, is not severe, but may be complicated by necrotic pseudocysts. The frequency of PD was also significantly increased in patients with gallbladder stones but not with common bile duct stones. In other pathological groups--chronic pancreatitis and pancreatic cancer--the frequency of pancreas divisum was not statistically different from that observed in controls and/or in the general population. We conclude that on a statistical basis, PD is a probable cause of acute pancreatitis, especially in its idiopathic recurrent variety, and that its frequency is increased in patients with gallbladder stones.     

A multicenter inquiry into the etiology of pancreatic diseases.

A multicenter study on the etiology and diet of patients with pancreatic diseases has been realized with the collaboration of 36 centers in 19 countries having widely different climatic and racial conditions. 2,478 cases were studied: acute pancreatitis (AP), 222 males, 208 females; calcified chronic pancreatitis (CCP), 801 males, 134 females; non-calcified chronic pancreatitis (NCCP), 525 males, 155 females; pancreatic cancer (PK), 69 males, 14 females; controls, 281 males, 62 females. The analysis of mutual information and the factorial analysis of correspondences have been used. With regard to chronic pancreatitis, the 19 countries could be classified into 4 classes presenting relative similarities. (A) Southern Europe: The diet is rich in carbohydrates, protein and lipids, alcohol intake is primarily in the form of wine and the pathology is dominated by CCP. There are much fewer women than men with chronic pancreatitis. (B) Northern Europe, to which may be added Argentina and Chile, is characterized by a protein- and lipid-rich diet, a beer-based alcohol consumption and a distinct prevalence of AP and NCCP. The prevalence of males with chronic pancreatitis is less marked than in southern Europe. (C) Japan has a lipid-poor diet and a low frequency of CCP and NCCP. (D) A fourth group is mostly composed of tropical countries with mixed races. It may be divided into 2 subclasses: (a) India is the most characteristic country of the first type with low fat, low protein diet, no alcoholism, high frequency of CCP (at an early age); (b) Brasil and South Africa are representative of the second subclass with very high alcohol intake in the form of spirits and a high frequency of CCP.     

Immunolocalization of collagen types, laminin and fibronectin in the normal human pancreas

In order to define the connective matrix organization of the normal human pancreas collagen types I, III, pro-III and IV, laminin and fibronectin were labeled using specific, antihuman antibodies. Visualization was by indirect immunofluorescence. Collagen types I, III and pro-III were present within lobules: around acini, ducts and small vessels. Their immunofluorescence reaction was particularly obvious in septa and it also outlined interlobular vessels and ducts. The type III and pro-III fractions possessed a characteristic, branched appearance in many situations, when compared to the more linear type I reaction. Collagen type IV, laminin and fibronectin were closely applied to acini, ducts and vessels, but in contrast to the other collagen types were absent from septa.     

A comparison of alcoholic pancreatitis in rat and man

Acute ethanol intoxication was studied in 38 Wistar rats, 18 on a balanced diet and 20 on a high fat diet, fed by gavage on 47% ethanol in a dosage of from 3 to 12 g/kg body weight daily for periods ranging from three to 16 days. No macroscopic changes in pancreas or liver were found in any of these animals. Histological changes (venous congestion of the pancreas, the liver, and the kidneys) were found in rats given 4 g or more per kilogram. The only difference between the findings in rats given a balanced diet and those given a high fat diet was the development of fatty livers in the latter group.

Chronic ethanol intoxication was studied in 45 Wistar rats, on a balanced diet, which were given 20% ethanol freely for 20 to 30 months. More than half the animals developed pancreatic lesions very similar to those of human chronic pancreatitis. The pathological changes, in foci surrounded by normal pancreatic tissue, were a reduction in acini, duct multiplication (probably by neogenesis), protein plugs, sometimes calcified in the ducts and sclerosis. Samples of pancreatic juice from four animals exposed to ethanol contained significantly higher protein concentrations than samples taken from two control animals. Protein precipitates appeared spontaneously in the pancreatic juice of the animals exposed to ethanol, but not in that of the controls. These findings are very similar to those in alcoholic pancreatitis in man, which has thus been reproduced for the first time in experimental animals. Beta-cell adenomata of the islets of Langerhans were observed in four of the rats exposed to ethanol.

     

Action of intragastric ethanol on the pancreatic secretion of conscious rats.

A surgical procedure has been disigned which permits injection in the stomach and the duodenum by separate catheters, collection of the pancreatic juice during the experiments, recirculation of the pancreatic juice into the duodenum between experiments, and a normal circulation of bile in rats. Experiments were performed in conscious rats given either 20% ethanol or water. In rats submitted to daily ethanol consumption for 13 months, the intragastric injection of 2 g/kg 20% ethanol considerably increased the pancreatic secretion of protein and, to a lesser extent, of water. In control non-alcoholic rats, a short period of increased secretion is followed by a major inhibition of pancreatic secretion, this reverse reaction to ethanol of pancreatic secretion according to whether or not rats are adapted to regular ethanol consumption is similar to what has been previously observed in dog. In chronic alcoholic rats, the release of secretin is probably not very different from controls.