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R van Schilfgaarde

Publications and source records attributed to R van Schilfgaarde.

At least 37 records · Page 2Linked to original sources
PubMed1995

Different roles of class I and class II Clostridium histolyticum collagenase in rat pancreatic islet isolation.

Crude Clostridium histolyticum collagenase was purified by gel filtration and fractionated by anion exchange chromatography into class I with high collagen digestion activity (CDA) and low FALGPA (2-furanacryloyl-L-leucylglycyl-L-prolyl-L-alanine) hydrolysis activity (FHA), class II with low CDA and high FHA, and a fraction called class I/II with intermediate activities. The roles of these collagenase classes in rat pancreatic islet isolation were investigated. Dissociations were carried out with 360 mg of pancreatic tissue in 10 ml of buffer containing 10% (wt/vol) albumin to suppress endogenous proteolytic activity, 100 U of C. histolyticum neutral protease, and one or two purified collagenase(s). For purified nonfractionated (PNF) collagenase, 2.6 mg of enzyme containing 2.4 U CDA and 38.0 U FHA was used, and for the separate classes, comparable amounts of activity were added. PNF collagenase dissociated the tissue completely in 32 min and yielded 5.0 +/- 0.4 microliters islet tissue/g pancreas. Class I collagenase alone dissociated pancreatic tissue extremely slowly and incompletely; only a few islets were released (0.7 +/- 0.2 microliters/g pancreas). Class II collagenase alone dissociated the tissue adequately in 50 min, and a high islet yield of 5.7 +/- 0.6 microliters/g was obtained. With class I/II, a similar dissociation time (47 min) and islet yield (5.5 +/- 0.3 microliters/g) were obtained. Combining class I and class II collagenase resulted in a more rapid dissociation (32 min) and a higher islet yield (7.1 +/- 0.8 microliters/g) than that obtained with PNF collagenase (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1994

Rat islet isograft function. Effect of graft volume and transplantation site.

Islet isograft function was analyzed after transplantation of 4 well-defined endocrine volumes (12.5%, 25%, 50%, and 100% of the endocrine volume in the normal adult rat pancreas) to 3 different sites (kidney, liver, and spleen). Graft function was tested in unanesthetized, unstressed rats by the responses to glucose infusion and to a meal. All animals with grafts > or = 25% of the endocrine volume of the rat pancreas returned to normoglycemia after transplantation. The minimal graft volume for restoring normoglycemia is probably between 12.5% and 25%, since also a small number of grafts of 12.5% were successful. At 1 month, basal glucose and insulin levels were similar to those of controls in rats with grafts to the spleen, but higher in rats with grafts to the kidney or liver. Irrespective of the transplantation site, recipients had higher glucose and lower insulin levels than controls in response to glucose infusion. In response to a meal, however, only the first-phase insulin response was reduced, but the total insulin output during the entire test was similar to that of controls. Graft performance was found to be graft-size dependent. Results of tests performed at 2 months showed a tendency of increasing responsiveness compared with the results of tests at 1 month.

Animals↗
PubMed1994

The capsular overgrowth on microencapsulated pancreatic islet grafts in streptozotocin and autoimmune diabetic rats.

This study investigates whether capsular overgrowth on alginate-polylysine microencapsulated islets is influenced by (1) the presence of islet tissue, (2) MHC incompatibility between donor and recipient, or (3) the presence of autoimmune diabetes. Encapsulated Albino Oxford (AO, n = 6, isografts) and Lewis (n = 6, allografts) rat islets, and encapsulated human islets (n = 5, xenografts) were implanted intraperitoneally into streptozotocin-diabetic AO rats. Also, encapsulated AO islets were implanted into autoimmune diabetic Bio Breeding/Organon (BB/O) rats (n = 5, allografts). Five isografts, five allografts, and three xenografts in AO recipients and five allografts in BB/O recipients resulted in normoglycemia. Two weeks after implantation, islets containing capsules were retrieved by peritoneal lavage, after which all animals that had become normoglycemic after transplantation returned to a state of hyperglycemia. Recovery rates of the capsules of these successful grafts, expressed as percentages of the initially implanted graft volume, varied from 72% +/- 7% to 80% +/- 9%. The associated pericapsular infiltrates (PCI) were similar in all groups and varied from 3.2% +/- 1.4% to 8.3% +/- 2.6%. Similar recovery rates and PCI were also found with empty capsules. However, the recovery rates of recipients with graft failures were lower and showed more PCI. Immunohistological staining of PCI showed no differences in the types of cells in the PCI on capsules with or without islets. We conclude that this early PCI is a capsule-induced foreign body reaction that is not influenced by MHC incompatibility or by the presence of autoimmune diabetes, and it should be avoided by improving the biocompatibility of the capsules.

Alginates↗
PubMed1994

Role of vagal dysfunction in motility and transit disorders of jejunal Roux limb after Roux-en-Y gastrojejunostomy.

After a Roux-en-Y gastrojejunostomy patients frequently complain about abdominal pain, fullness, nausea and vomiting, ie, the Roux-en-Y syndrome. Stasis in the Roux limb due to disordered motility is known to be a cause of these complaints. The aim of the present study was to determine whether vagal denervation contributes to the development of motility disturbances and stasis in the Roux limb. Forty-seven patients with a Roux-en-Y gastrojejunostomy after partial gastrectomy were studied. A truncal vagotomy had been performed in 26 of these 47 patients. Transit through the Roux limb was evaluated by radionuclide studies, motility in the Roux limb was studied by manometry, and vagal function was tested by measuring the pancreatic polypeptide response to an insulin-induced hypoglycemia (PP test). On the basis of the PP test patients were classified as having (1) normal, (2) moderately impaired, and (3) severely impaired vagal function. The PP test showed that two of the 26 patients subjected to vagotomy had a moderately impaired vagal function, the other 24 all had a severely impaired vagal function. In the patients not subjected to a vagotomy, vagal function was disturbed in 11 of the 21 patients. Motility disturbances were not observed more frequently in patients with either moderately or severely impaired vagal function than in patients with normal vagal function. Stasis in the Roux limb was seen even more frequently in patients with a normal vagal function than in patients with a severely impaired vagal function.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Roux-en-Y↗
PubMed1994

Aortoiliac and aortofemoral reconstruction of obstructive disease.

This retrospective study evaluates our strategy to limit prosthetic reconstructions for aortoiliac obstructive disease to the diseased segments in 518 patients. There were 363 (70%) reconstructions without femoral anastomotic sites (FEM-0), 107 (21%) reconstructions with one femoral anastomotic site (FEM-1), and 48 (9%) aortobifemoral reconstructions (FEM-2). The ischemic symptoms and the extent of obstructions were significantly more severe in the FEM-1 and FEM-2 groups than in the FEM-0 group. Early operative results were comparable in all three groups. The difference in outcome became apparent when the long-term results were considered. Long-term follow-up continued for up to 20 years after the operation. Primary and secondary patency rates were significantly higher in the FEM-0 group (9% and 4% recurrent obstructions per 5 years, respectively) than in the FEM-1 and FEM-2 groups (both 14% and 10%, respectively), which was explained by patient selection. Late additional surgery was performed after aortoiliac procedures in most cases for recurrent aortoiliac obstruction and after aortofemoral procedures in most cases for false aneurysms. The risk of late additional operations during long-term follow-up were significantly lower in the FEM-0 group than in the FEM-1 and FEM-2 groups. These results support our strategy to tailor prosthetic reconstructive surgery to the individual status of the aortoiliac arteries.

Aorta, Abdominal↗
PubMed1993

Manometric and scintigraphic studies of the relation between motility disturbances in the Roux limb and the Roux-en-Y syndrome.

After a Roux-en-Y gastrojejunostomy, patients frequently complain of abdominal pain, fullness, nausea, and vomiting. This so-called Roux-en-Y syndrome is caused by slow gastric emptying, Roux-limb stasis, or both. The pathogenesis of these transit disorders is unknown. The aim of the present study was to investigate whether slow gastric emptying and Roux-limb stasis can be attributed to motility disturbances in the Roux limb. Thirty-seven patients with a Roux-en-Y gastrojejunostomy after partial gastrectomy were studied, 26 of whom had the Roux-en-Y syndrome and 11 who did not. Gastrojejunal transit was evaluated by radionuclide studies, and motility in the Roux limb was studied by manometry. Thirteen patients had slow gastric emptying, and 14 had stasis in the Roux limb. Slow gastric emptying, Roux-limb stasis, or a combination of both was found in 20 of 26 symptomatic patients and in only 4 of 11 asymptomatic patients (p < 0.05). The basic motor patterns, the interdigestive motor cycle, and the fed state were present in most patients. However, motility disturbances were present in 34 of the 37 patients. Motility disturbances were observed significantly more frequently in patients with symptoms than in those without, and also in patients with Roux-limb stasis than in those without, but no relation was found between motility disorders and slow gastric emptying. Aberrant propagation of the migrating motor complex and the absence of the fed state were the only motility disorders that were not observed in patients with normal Roux-limb transit. Of the various recorded motility disturbances, these two probably represent the more serious motility disturbances. The results of our study indicate that Roux-limb stasis is caused by motility disorders in the Roux limb. They also indicate that Roux-limb stasis is not responsible for slow gastric emptying, since there is no correlation between motility disorders in the Roux limb and slow gastric emptying.

Abdominal Pain↗
PubMed1993

Fish oil increases the release of tumour necrosis factor and interleukin-6, and has no effect on the incidence of multiple organ failure in rats with peritonitis.

OBJECTIVE: To find out if fish oil given intraperitoneally would cause a reduction in the release of tumour necrosis factor and interleukin-6 in abdominal exudate and blood (experiment A), and if it reduces the incidence of organ failure in rats with peritonitis (experiment B). DESIGN: Laboratory experiment. SETTING: University animal laboratory. MATERIAL: Thirty-six selectively decontaminated rats in each experiment. INTERVENTIONS: All rats were pretreated with 2 ml fish oil, lecithin, or saline, intraperitoneally for one or six weeks before intraperitoneal injection of zymosan. Experiment A: Samples of abdominal exudate and plasma were taken regularly for 24 hours after the zymosan had been given. Experiment B: Clinical, biochemical, and histological variables were measured over a 12-day period after the zymosan had been given. MAIN OUTCOME MEASURES: Experiment A: Concentrations of tumour necrosis factor and interleukin-6 in abdominal exudate and plasma. Experiment B: Incidence of multiple organ failure. RESULTS: Experiment A: Concentrations of tumour necrosis factor and interleukin-6 in abdominal exudate and plasma were significantly higher in rats pretreated with fish oil, compared with control rats. This effect was more pronounced after six weeks of pretreatment. Experiment B: There were no significant differences between the groups for any variable. CONCLUSION: Fish oil given intraperitoneally increased rather than reduced local and systemic release of tumour necrosis factor and interleukin-6, and did not reduce the incidence of organ failure in rats with sterile peritonitis.

Animals↗
PubMed1992

Significance of the peri-insular extracellular matrix for islet isolation from the pancreas of rat, dog, pig, and man.

The presence and distribution in the peri-insular region of extracellular matrix, and in particular basement membrane, was investigated in a comparative study comprising pancreata of rat, dog, pig, and man. Basement membrane markers, collagen type-IV and laminin, were determined immunohistochemically. Additional information pertaining to the structural relationships between endocrine and exocrine pancreas, in particular cell-to-cell and cell-to-matrix contacts, was obtained by electron microscopy. In pig, very little peri-insular capsule is present, and the structural integration of the porcine islet in the exocrine pancreas almost exclusively depends on cell-to-cell adhesion. In the canine pancreas, the islets are almost completely encapsulated with very little direct exocrine-to-endocrine cell-to-cell contact. In rat and man, the situation is intermediate with a tendency towards predominance of cell-to-matrix adhesion. The intra-insular adhesion mechanisms depend largely on cell-to-cell adhesion in all four species. The ultrastructural results suggest that collagenase preparations employed in islet isolation procedures should be of high purity as to preserve the protease-sensitive intra-islet cell-to-cell adhesion. Under these conditions, however, the endocrine-to-exocrine cell-to-cell contacts will be conserved also, resulting in an exocrine-tissue contamination of the islets of Langerhans. Consequently, additional steps for the effective removal of exocrine tissue and the purification of islets are required.

Adult↗
PubMed1992

Insulin secretion by rat islet isografts of a defined endocrine volume after transplantation to three different sites.

We have analysed the graft function of rat islet isografts of identical and well-defined endocrine volumes after transplantation to three different sites (kidney, liver and spleen). Graft endocrine mass was determined by measuring the total islet volume prior to transplantation and was chosen to be similar to the endocrine volume in the normal adult rat pancreas. Graft function was tested in unanaesthetized, unstressed rats by the responses to glucose infusion and to a meal. All transplanted animals returned to normoglycaemia within one week after transplantation. At one month, basal glucose and insulin levels were similar to controls in rats with grafts to the spleen, but higher in rats with grafts to the kidney or liver. Irrespective of the transplantation site, recipients had higher glucose and lower insulin levels than controls in response to glucose infusion, but in response to a meal these differences from normal were less obvious. Finally, recipients showed both an acute insulin response to glucose infusion as well as a pre-absorptive insulin release after food ingestion, irrespective of the transplantation site. Our findings indicate that the insulin response to glucose infusion and to a meal is quantitatively reduced, but qualitatively intact after transplantation to the kidney, liver or spleen.

Animals↗
PubMed1992

An analysis of the role of collagenase and protease in the enzymatic dissociation of the rat pancreas for islet isolation.

Crude Clostridium histolyticum collagenase is widely used for the enzymatic degradation of pancreatic extracellular matrix in order to isolate the islets of Langerhans. The variable enzymatic composition of crude collagenases is a critical issue which contributes to the poor reproducibility of islet isolation procedures. In this study, the separate contributions of collagenase and protease to the islet isolation process were analysed by testing various combinations of purified collagenase and purified protease in rat pancreas dissociations under conditions which eliminated all other proteolytic activity. Under these conditions, complete tissue dissociation by purified collagenase required 99 +/- 10 min, whereas increasing amounts of protease progressively reduced this time to a minimum of 36 +/- 1 min. Histochemical analysis of the dissociation process showed that protease enhanced the degradation of all four major components of the extracellular matrix: collagen was degraded more completely, while proteoglycans, glycoproteins and elastin were degraded at a higher rate. Pancreas dissociation under the present, strictly controlled conditions resulted in a high yield of viable islets: 4.2-5.0 microliters islet tissue volume (3,300-3,800 islets) were isolated per g pancreas in the presence of a high or low protease concentration, respectively. Prolonged dissociation in the presence of protease resulted in a dramatic decrease in islet yield which correlated with the observation that the enzyme accelerated islet disintegration. It is concluded that the collagenase-induced dissociation of the extracellular matrix is facilitated by protease. Our study shows that high yields of viable islets can be obtained under controlled enzymatic conditions, provided that the exposure of islets to protease is limited.

Animals↗
PubMed1992

Peri-insular presence of collagenase during islet isolation procedures.

Reportedly, higher islet yields are obtained by ductal collagenase administration and subsequent digestion of the pancreas than by the chopped tissue collagenase digestion technique. However, the exact mechanism of islet isolation is not known. This study aims to understand the underlying mechanism of a favorable effect of ductal collagenase administration. To this end, we investigated if the higher yields can be explained by a different distribution of the collagenase enzymes in the pancreatic tissue after ductal application as compared to during chopped tissue digestion. India ink was used to mimic and visualize the distribution of collagenase in histological sections of pancreases of several species. Ink particles were seen around and even within the islets both after ductal application and during chopped tissue collagenase digestion. Thus, collagenase enzymes are not restricted to the exocrine tissue compartment with either technique. In view of this observation, we compared the efficacy of both techniques in islet isolation procedures in paired experiments in rats. Both techniques gave similar islet yields to those reportedly obtained with the ductal collagenase method. However, with either technique, the islet yield was only approximately 50% of the endocrine volume of the pancreas, indicating that a substantial loss of islet tissue had occurred. We conclude that, irrespective of the route of collagenase administration, collagenase enzymes are present in the peri-insular space during islet isolation procedures. This is pertinent in view of the finding that both methods have similar islet yields in rats and that collagenase digestion, as such, is associated with loss of islet tissue.

Animals↗
PubMed1992

Design of a polyurethane membrane for the encapsulation of islets of Langerhans.

A semipermeable membrane for the encapsulation of the islets of Langerhans, consisting of a microporous polymer network, has been developed. The polyurethane network was formed by cross-linking a mixture of linoleic acid and a linear poly(etherurethane) with dicumyl peroxide. Cross-linking the polyurethane impedes the formation of hard domains. Miocroporosity was introduced by adding salt crystals of different sizes before cross-linking and leaching it out afterwards. To optimize the permeability and immunoprotectivity, membranes were prepared with three different porosities. Membranes of this material were filled with islets of Langerhans and implanted in the peritoneal cavity of rats. Short-term in vivo experiments in rats show that membranes with pores in the range 0.3-0.7 micron and a wall thickness of about 8 microns were permeable for insulin and glucose and protected the islets of Langerhans against the cells of the immunological system.

Animals↗
PubMed1992

Long-term results of prosthetic and non-prosthetic reconstruction for obstructive aorto-iliac disease.

In this retrospective study the results of 518 prosthetic aorto-iliac reconstructions (PRS) and of 229 thrombo-endarterectomies (TEA) were evaluated, with inclusion of follow-up results up to 20 years after surgery. Patients in the PRS group had presented with more severe ischaemic symptoms and more extensive arterio-sclerotic obstructions than the patients in the TEA group. Results in the TEA group were further analysed according to the extension of arterio-sclerotic disease: there were 93 patients with obstructions limited to the aorta or common iliac arteries and 136 patients with more extensive lesions. Patients with limited obstructions were younger, proportionally more often female, had fewer risk factors, and presented with less severe ischaemic symptoms than patients with more extensive obstructions. Operative mortality and early technical and functional results were similar in the PRS and TEA group, but long-term survival and patency rates were significantly better, and the need for late, additional operations was less in the TEA group. Late functional success rates were similar in both groups. The differences in outcome were explained by patient selection. Within the TEA group significantly superior results regarding survival, patency, need for late, additional surgery, and functional success were observed in the subset of patients with obstructions limited to the aorta or common iliac arteries. Considering these results and the risks inherent in a prosthetic reconstruction, such as prosthetic infection and the chance for false aneurysms, we advocate the use of an aorto-iliac TEA in properly selected patients.

Aorta, Abdominal↗
PubMed1992

Comparison of top and bottom loading of a dextran gradient for rat pancreatic islet purification.

Rat pancreatic islet yields obtained with dextran gradient purification were compared after suspending the digest into either the top or the bottom layer of the gradient. A 5-layer discontinuous gradient was used, which consisted of 16 ml 31% dextran as bottom layer, overlayered with 25%, 23%, 20% and 11% dextran (4 ml each). When the digest of 1 rat pancreas was suspended into the top layer of the gradient, the total number of islets obtained from the 11-20, 20-23 and 23-25% interfaces was 862 +/- 38, 240 +/- 39 and 54 +/- 5, respectively. From this gradient, also 1409 +/- 81 islets were retrieved from the bottom layer (i.e., exocrine pellet). In contrast, when the pancreas digest was suspended into the bottom layer of the gradient, 1964 +/- 63, 435 +/- 42, and 177 +/- 34 islets were obtained from the successive interfaces, and only 50 +/- 20 islets from the exocrine pellet. The total islet volume obtained from the two uppermost interfaces was 3.46 +/- 0.31 microliters after top-loading, and 4.93 +/- 0.16 microliters after bottom-loading (n = 7, p < 0.01). When the islets retrieved from one bottom loaded gradient were transplanted into either 1 (n = 6) or 2 (n = 9) diabetic recipients, glucose levels normalized in all instances. We therefore conclude that a bottom-loaded dextran gradient separates islets from exocrine tissue effectively, resulting in significantly higher islet yields than obtained with a top-loaded dextran gradient.

Animals↗