PubMed Health⌕ Search

Biomedical subjects

R van Schilfgaarde

Publications and source records attributed to R van Schilfgaarde.

At least 55 records · Page 3Linked to original sources
PubMed1992

Long term success of aortoiliac operation for arteriosclerotic obstructive disease.

The current retrospective study was performed on 747 patients with aortoiliac obstructive disease who underwent reconstructive operation. Unlike many other centers, the University Hospital Leiden has, throughout the years, maintained the strategy of avoiding the implantation of a prosthesis in patients with limited and localized obstructive disease that could readily be treated with an endarterectomy. When a prosthesis was used, it was anastomosed to the femoral artery if a more proximal anastomosis was not feasible. In the present study, the long term outcome of the strategy is evaluated. Three groups of patients were studied--245 patients with moderate claudication, 331 patients with severe claudication and 162 patients with critical ischemia at presentation. Thromboendarterectomies were used in 229 patients (30.7 per cent) and prosthetic reconstructions in 518 patients (69.3 per cent), of which 339 (45.5 per cent) were aortoiliac reconstructions. The perioperative mortality rates were 1.6, 3.0 and 3.1 per cent for the three groups, respectively. Atherosclerotic heart disease was the most common cause of perioperative (30.0 per cent) and late (30.8 per cent) death. Late complications of surgical treatment also contributed significantly to the causes of late deaths (12.1 per cent). Because over-all survival rates in the current series compared favorably with those in other series, the influence of reconstructive operation on late survival was compensated for by a beneficial effect in patients without such complications. Secondary operations for late complications, such as false aneurysms and aortoiliac reobstruction or for progressive obstructive disease, were necessary in 21 per cent of all 727 survivors of the first operation. Actuarial curves with various endpoints--mortality, secondary operation, patency of aortoiliac segments, functional failure, amputation, presence of mild, moderate and severe claudication--were calculated according to the standard method of life table construction. In terms of technical success rates, the results of our surgical technique strategy compared favorably with those reported in other series, in which most patients were treated with aortobifemoral prostheses. The chances of functional failure increased with time, amounting to about 23 per cent at 15 years postoperatively for each group of patients. Comparison of technical and functional success rates showed a significant disparity, which was explained by the effects of collateral blood flow in instances of aortoiliac reobstruction and of progressing femoropopliteal obstructions in instances of open aortoiliac vessels.

Actuarial Analysis↗
PubMed1991

A versatile alginate droplet generator applicable for microencapsulation of pancreatic islets.

Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, smooth, and spherical in order to ensure that around the islets a strong alginate-polylysine-alginate capsule will be formed with optimal biocompatibility and diffusion of nutrients and hormones. However, the preparation of small capsules around islets is difficult. Our newly designed air jet droplet generator allows for variations in the length and diameter of the alginate nozzle and the air jacket and is in this way adaptable to a required bead size. Alginate droplets are converted into rigid beads in a 100 mM CaCl 2 solution. Their size depends upon the diameter of the jacket, the air flow rate, and the outer diameter of the nozzle, whereas the production rate depends upon the pressure on the alginate, and on the diameter and the length of the nozzle. When the air flow or the alginate flow surpasses a certain rate, the droplets are fragmented. This study describes the mutual relationship of these variables and defines their optimal range for reproducible production of smooth and spherical beads for microencapsulation of islets at an acceptable production rate.

Alginates↗
PubMed1991

Glucose tolerance and plasma insulin response to intravenous glucose infusion and test meal in rats with microencapsulated islet allografts.

Albino Oxford rats made diabetic with 75 mg/kg streptozotocin were intraperitoneally transplanted with 2500-2900 alginate-polylysine microencapsulated Lewis islets (n = 9, total islet tissue volume 8.0-11.0 microliters), or a similar volume of non-encapsulated Lewis islets (n = 5). All rats with microencapsulated islets became normoglycaemic, and remained normoglycaemic for 5-16 weeks. In rats with non-encapsulated islet grafts, only a temporary decrease in blood glucose was observed, and all were again severely hyperglycaemic at 1 week after implantation. At 5-6 weeks after transplantation, glucose tolerance in rats with microencapsulated islets was tested by intravenous glucose infusion (10 mg/min over 20 min) and test meal administration (n = 4). During glucose infusion, maximum glucose levels were 13.0 +/- 0.4 mmol/l in rats with microcapsules and 8.9 +/- 0.4 mmol/l in healthy control rats (p less than 0.01). Concomitant maximum plasma insulin levels were 215 +/- 17 pmol/l in rats with microcapsules and 715 +/- 85 pmol/l in controls (p less than 0.001). After the test meal, maximum blood glucose was 10.6 +/- 0.9 mmol/l in rats with microcapsules and 6.2 +/- 0.1 mmol/l in controls (p less than 0.001), with concomitant maximum plasma insulin levels of 247 +/- 11 pmol/l and 586 +/- 59 pmol/l, respectively (p less than 0.001). In conclusion, although the glucose tolerance is impaired and plasma insulin responses to intravenous glucose-load and test-meal are reduced, the alginate-polylysine membrane does provide adequate immunoisolation for the prolongation of allograft survival, resulting in prolonged normoglycaemia in streptozotocin diabetic rats.

Animals↗
PubMed1991

Computerised vascular data management: a flexible modular registry suitable for the evaluation of long-term results in patients subjected to multiple interventions.

We have designed a computerised vascular registry (CVR) combining storage of complete patient histories in minute detail, including reoperations and long-term follow-up, with clinical applicability. The basic concept of this registry is the storage of data in a structure of cycles (one cycle per treatment episode), modules (clusters of logistically correlated data) and data-chapters (clusters of clinically correlated data). The registry was designed to minimally interfere with routine clinical practice, for instance by collecting the data step-by-step at the wards and out-patient clinics, quite similar to traditional record keeping. The CVR enables production of inventories of all stored data. More importantly, and in addition to other registries, the structure of our registry adequately enables analyses of data of patients with multiple interventions and patients with long-term follow-up. A microcomputer was used for the input of data, which were stored in a structure enabling effortless transportation of the data to a mainframe computer. Standard software programs were used. Simple inventories and analyses were performed on a microcomputer, and a mainframe computer was used for more complex analyses. The performance and applicability of the newly designed CVR was thoroughly tested in comprehensive retrospective studies. On the basis of these experiences several adjustments were carried out after which the CVR was introduced into clinical practice.

Computer Systems↗
PubMed1991

The efficacy of intraperitoneal pancreatic islet isografts in the reversal of diabetes in rats.

The peritoneal cavity is of renewed interest for pancreatic islet transplantation, since it is the preferable site for transplantation of immunoisolated islets. In this study we investigated the minimum islet graft volume needed to restore normoglycemia after free intraperitoneal isogenic transplantation in streptozotocin diabetic rats. Furthermore, graft function was tested by measuring glucose and insulin response to an intravenous glucose load and spontaneously ingested carbohydrate-rich meal. Three graft volumes were used: 8.0-10.0 (group A); 4.0-5.0 (group B); and 2.0-2.3 microliters (group C); 1 microliter contained about 300 islets. All 10 rats in group A and 7 out of 9 rats in group B became normoglycemic for at least 6 months posttransplant, with blood glucose levels not significantly different from normal control animals. Only 3 out of 9 animals in group C became normoglycemic and never for longer than 3 months. The insulin responses to IVGTT in group A and group B were proportional to the grafted islet volume and always significantly lower than those of normal control rats. The insulin response to the test meal showed a similar tendency, which was found to be associated with the absence of preabsorptive insulin secretion. Maximum postprandial blood glucose levels in group A and group B were 0.8 and 1.5 mM higher than in normal control rats. We conclude that intraperitoneal transplantation of at least 4.0-5.0-microliters islet tissue is needed to reverse blood glucose in streptozotocin diabetic rats, and that glucose and insulin levels on IVGTT and test meal in rats with islet grafts of 8.0-10.0 microliters are not completely normalized. It is suggested that the impaired glucose tolerance is due to an insufficient beta-cell mass and a lack of parasympathetic innervation of the transplanted islet tissue.

Animals↗
PubMed1991

Effect of alginate-polylysine-alginate microencapsulation on in vitro insulin release from rat pancreatic islets.

We investigated the effect of alginate-polylysine-alginate microencapsulation on glucose-induced insulin secretion by rat islets. Applying the encapsulation method originally described by Lim, we found severely reduced in vitro insulin release (expressed as picomoles of insulin.10 islets-1.45 min-1 when incubated in 16.5 mM glucose), because the insulin release with encapsulated islets was 1.42 +/- 0.49 compared to 13.58 +/- 0.80 with free control islets. This could not be explained by inadequate permeability of the capsule, because insulin release was also severely reduced (2.12 +/- 0.61) when islets were subjected to the procedure but without the membrane-forming polylysine step. Therefore, islets were tested after having been subjected separately to each of the steps of the procedure. Insulin release was not affected by either alginate or CaCl2 but was severely reduced after prolonged suspension in saline or treatment with citrate. When saline and citrate were replaced by Ca2(+)-free Krebs-Ringer bicarbonate buffer (KRBB) and 1 mM EGTA, respectively, insulin release improved significantly both with complete and with incomplete (no polylysine step) encapsulation. This outcome was verified in a set of experiments run in parallel with islets derived from the same isolation procedure. Insulin release was 1.20 +/- 0.23 from islets encapsulated with the method of Lim and 10.73 +/- 1.04 from free control islets. With the modified procedure, insulin release was 9.17 +/- 0.52 vs. 9.61 +/- 1.27 for complete versus incomplete encapsulation, respectively. We conclude that Ca2(+)-free KRBB instead of saline and EGTA instead of citrate should be used to obtain an adequate insulin response from encapsulated islets and that the capsule membrane as such has no influence on glucose and insulin diffusion.

Alginates↗
PubMed1990

[Renal artery reconstruction for renovascular hypertension].

Between 1959 and 1983, 172 patients were treated for hypertension by reconstruction of a renal artery. Reconstruction was preferably performed with autologous material. In a selected group of 29 patients with lesions in the distal renal artery or the hilar branches, an extracorporeal reconstruction with autotransplantation was performed. After a mean follow-up of 8.4 years the hypertension was cured or improved in 82% of the patients. In patients with an arteriosclerotic renal artery stenosis this result was favourably influenced by a short duration of hypertension before the operation. Their life expectancy after the operation was clearly favourably influenced by a beneficial blood pressure response even if arteriosclerotic lesions of coronary arteries, extracranial vessels and/or peripheral vessels were present before the renovascular operation. In selected patients, renal artery reconstruction for treatment of hypertension yields excellent short-term and long-term results, not only with regard to the blood pressure response but also with respect to the patients' life expectancy.

Adult↗
PubMed1990

The efficacy of density gradients for islet purification: a comparison of seven density gradients.

Seven different density gradient-forming materials were compared as to their efficacy for rat islet purification. Continuous density gradients were used in order to determine the bouyant densities of the different pancreatic tissue components. Hand-picked islets served as a control. A significant separation of large numbers of islets from the exocrine tissue band was only seen in the albumin, dextran-40, and metrizamide gradients. Pure islet preparations could not be obtained with any of the gradients studied as none of the gradients completely separated lymph nodes, vessels, and ducts from the islets. Gradients containing sucrose resulted in low islet yields. The islet yields obtained with the other gradients were in the same range as those obtained by hand-picking. Metrizamide gave significantly higher yields than the widely used Ficoll. Judged both in terms of numbers of islets and their in vitro function, the best results were obtained with metrizamide and dextran-40.

Albumins↗
PubMed1990

Factors influencing the isolation process of islets of Langerhans.

Determination of collagenase and proteolytic activities and slabgel electrophoresis of collagenase preparations obtained from different suppliers reveals a highly variable content of collagenase, proteolytic activities and other components. The electrophoresis pattern can help to select collagenase preparations with a low content of impurities suitable for islet isolation. During islet isolation the exocrine tissue releases large amounts of proteolytic activities into the digestion medium, which decreases islet yield. Addition of 10% albumin to the digestion medium strongly suppresses the release of proteolytic activity and increases the number of islets obtained. Addition of both albumin and trypsin inhibitors further increases not only the number of islets, but also the total volume of islet tissue obtained. The islet isolation process is not critically dependent on the pH in the range 6.2 to 8.0 and only marginally dependent on the calcium concentration.

Animals↗
PubMed1989

Expanded polytetrafluoroethylene patch for the repair of large abdominal wall defects.

Expanded polytetrafluoroethylene (ePTFE) was used to repair 11 large abdominal wall defects in ten patients. Three patches were fixed to the adjacent abdominal aponeurosis with a single row of sutures; seven patches were implanted with a 1-2 cm overlap of patch and aponeurosis and a double row of sutures. Recurrent buttonhole hernias were found in two patients, in both of whom a single row of sutures had been used. This reherniation was due to insufficient anchorage of the patch to the fascia. It is concluded that ePTFE is a useful material to repair large abdominal wall defects provided the patch is fixed to the aponeurosis with an overlap and a double row of sutures to prevent buttonhole hernias.

Abdominal Muscles↗
PubMed1989

Long-term results of renal artery reconstruction with autogenous artery in patients with renovascular hypertension.

Renal artery reconstruction for the treatment of renovascular hypertension is preferably performed with an autologous graft when a graft is required. Although satisfactory results with vein grafts have been reported, stenosis and dilatation are not infrequent complications which have been observed only occasionally in arterial grafts. We have analysed our long-term results obtained with autogenous arterial grafts for renal artery reconstruction to determine the functional and anatomical results with regard to these complications. The data from 57 survivors operated on from 1959 through 1983 were analysed. All patients were hypertensive and the average systolic and diastolic blood pressure was 173/109 mmHg (mean number of 2.2 drugs). The renal artery stenosis was caused by arteriosclerosis and fibrodysplasia in 24 and 33 patients, respectively. In situ repair was performed in 30 patients (arterial bypass: 17 patients; splenorenal bypass: 13 patients). Extracorporeal repair of fibrodysplastic branch lesions was performed in 27 patients using branched hypogastric artery grafts (mean number of 2.4 branch anastomoses per kidney). Results were evaluated in the short (mean 8.3 months) and long term (mean 7.5 years) and the blood pressure response classified as either beneficial (cured/improved) or failed. Anatomical results were evaluated by angiography in the short-term in 87% of the patients and the long-term in 70%. A beneficial blood pressure response was obtained in 77% and 86% of patients in the short and long-term, respectively. The average blood pressure level after an interval of several years (long term) was 144/87 mmHg (mean number of 0.9 antihypertensive drugs). After in situ reconstruction, 2 and 1 anatomical failures were observed in the short and long-term, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial Occlusive Diseases↗
PubMed1989

False aneurysms after prosthetic reconstructions for aortoiliac obstructive disease.

Several aspects of false aneurysm development after prosthetic resconstruction for aortoiliac obstructive disease were studied. For this purpose the long-term results (up to 20 years of follow-up) of 518 patients with implanted arterial prostheses in the aortoiliofemoral tract were retrospectively evaluated. Completeness of follow-up data was 83.2% 15 years after operation. A total of 101 false aneurysms (21 aortic, 53 iliac, and 27 femoral) were detected in 69 patients and verified by operation. The incidence per patient was 69 of 518 patients (13.3%). The incidences per anastomosis were: aortic, 21 of 438 anastomoses (4.8%); iliac, 53 of 835 anastomoses (6.3%); and femoral, 27 of 198 anastomoses (13.6%). Almost one half (47.5%) of all the false aneurysms were asymptomatic and were detected by angiography or ultrasonography. Chances for late survivors to develop a false aneurysm during follow-up were calculated by the life-table method. The chance to be free of a false aneurysm at any site was 77.2% 15 years after operation. These chances were 92.3%, 84.5%, and 76.2% for aortic, iliac, and femoral anastomoses, respectively. Analyses of subgroups showed that the development of a false aneurysm was significantly correlated with the presence of hypertension, multilevel disease, the type of suture material, and the type of anastomosis. These results indicate unexpectedly high chances for the development of false aneurysms in long-term survivors after aortoiliac or aortofemoral prosthetic reconstructions. We advocate the use of a life-long follow-up schedule with periodic angiography and ultrasonography for these patients.

Anastomosis, Surgical↗
PubMed1989

Crossover study on effects of duct obliteration, celiac denervation, and autotransplantation on glucose- and meal-stimulated insulin, glucagon, and pancreatic polypeptide levels.

In segmental-pancreas transplantation the body and tail of the pancreas are used. In an experimental study in dogs, the effects of sequentially conducted removal of the right pancreatic lobe (pancreatic head), duct obliteration, celiac denervation, and autotransplantation were studied according to a crossover design. Two groups of dogs were studied. In both groups the right lobe of the pancreas was removed at primary operation, and the duct of the transected left lobe (body and tail) was injected with fibrin sealant. The left lobe was completely freed from surrounding tissue (celiac denervation) in group 1 (n = 9), and the innervation of the left lobe was left intact in group 2 (n = 8). At 12 wk, two dogs in group 1 and four dogs in group 2 underwent successful autotransplantation of the left lobe. Pancreatic hormone secretion was stimulated by intravenous glucose injection and test-meal administration before primary operation and at 11 and 18 wk thereafter. The combination of removal of the right lobe and duct obliteration led to a decrease in glucose tolerance at both stimulation tests and a decrease in peripheral insulin release after intravenous glucose injection. At test-meal administration, no change in insulin and glucagon levels was demonstrated. If celiac denervation was added, similar results were obtained based on the understanding that the peripheral insulin release after the test meal was significantly elevated. Meal-stimulated pancreatic polypeptide response was abolished in both groups. Removal of the right lobe leads to parasympathic denervation of the left lobe, and celiac denervation mainly interferes with alpha-adrenergic innervation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Procurement of the liver and the whole pancreas from a single cadaver donor.

Safely harvesting the liver as well as the whole pancreas from a single donor is not yet common practice in transplantation surgery, since these organs have a partially common blood supply. Two harvesting procedures are described followed by successful transplantation of five solid organs from each donor, including liver and whole pancreas. Important details of the preferred surgical technique are the division of the hepatic artery just distal to the splenic artery and keeping the aortic patch, including superior mesenteric artery and coeliac trunk with the pancreas graft. Using this technique the liver and the whole pancreas could be transplanted without extra vascular anastomoses, while vascular grafts were not necessary. The risk of thrombosis during pancreas and liver transplantation is minimized in this way, while the primary function of each of the five harvested organs was excellent.

Cadaver↗