Randomized clinical trial of continuous sutures or non-penetrating clips for radiocephalic arteriovenous fistula.

BACKGROUND: Despite several modifications to the original design, patency rates of radiocephalic arteriovenous fistulas have changed little since the first report in 1966. The use of non-penetrating clips for vascular anastomosis on the outcome of such fistulas was studied. METHODS: Between January 2000 and August 2003, 107 primary radiocephalic fistulas were constructed in 98 patients. The vascular anastomoses were performed at random with either sutures (n = 56) or clips (n = 51). RESULTS: Although there were trends for better primary and primary assisted patency of clipped fistulas, the differences were not statistically significant. The 6-month primary patency rate was 61 per cent with sutures and 69 per cent with clips (P = 0.393). The mean(s.d.) primary patency was 315(306) and 285(285) days for clipped and sutured fistulas respectively. With regard to secondary patency, clipped fistulas were better (P = 0.009). The mean(s.d.) secondary patency was 435(376) and 344(316) days for clipped and sutured fistulas, respectively. There were no significant differences in flow characteristics, number of revisions or other morbidity. CONCLUSION: This randomized clinical trial provided further evidence that the use of vascular clips may improve the patency rate of radiocephalic arteriovenous fistulas for haemodialysis.

Treatment of short-necked infrarenal aortic aneurysms with fenestrated stent-grafts: short-term results.

INTRODUCTION: A proximal neck of 15 mm length is usually required to allow endovascular repair of abdominal aortic aneurysms (EVAR). Many patients have been refused EVAR due to a short neck. By customising fenestrated grafts to the patients' anatomy, we can offer an endovascular solution, especially for patients who are unsuitable for open repair. METHODS: Eighteen patients were selected for fenestrated stent-grafting if they presented with an abdominal aneurysm of at least 55 mm in diameter, a short neck (less than 15 mm), plus contra-indications for open repair (cardiopulmonary impairment or a hostile abdomen). The stent-graft used was a customised fenestrated model based on the Cook Zenith composite system. We used additional stents to ensure apposition of the fenestrations with the side branches. RESULTS: All endovascular procedures were successful. Out of the 46 targeted side branches (10 superior mesenteric arteries, 36 renal arteries), 45 were patent at the end of the procedure. One accessory renal artery became occluded by the stent-graft. There was one possible proximal type I endoleak, which later proved to be a type II endoleak. There was no mortality, but complications occurred in six patients: two cardiac complications, three urinary complications and one occlusion of a renal artery. At follow-up (mean 9.4 months, range 1-18), there were no additional renal complications and all the remaining targeted vessels stayed patent. DISCUSSION: By customizing fenestrated stent-grafts, it is possible to position the first covered stent completely inside the proximal neck, thus achieving a more stable position. The additional side-stents may also contribute to a better fixation. This technique may become a valuable alternative for patients who are at high risk from open surgery.

Non-suture methods of vascular anastomosis.

BACKGROUND: The main aim of performing a vascular anastomosis is to achieve maximal patency rates. An important factor to achieve that goal is to minimize damage to the vessel walls. Sutures inevitably induce vascular wall damage, which influences the healing of the anastomosis. Over time, several alternatives to sutures have become available. METHODS: A Medline literature search was performed to locate English, German and French language articles pertinent to non-suture methods of vascular anastomosis. Manual cross-referencing was also performed and many historical articles were included. RESULTS AND CONCLUSION: The non-suture techniques can be categorized into five groups based on the materials used: rings, clips, adhesives, stents and laser welding. With all these techniques a faster and less traumatic anastomosis can be made compared with sutures. However, each device is associated with technique-related complications. As a consequence, suturing continues to be the standard approach. The disadvantages of the non-suture techniques include: rigidity and a non-compliant anastomosis with rings; toxicity, leakage and aneurysm formation with adhesives; early occlusion with stents; cost, reduced strength in larger-sized vessels and demand for surgical skills with laser welding. Further refinement is needed before widespread adoption of these techniques can occur. Clips, however, may be particularly promising but long-term evaluation is required.

Response of encapsulated rat pancreatic islets to hypoxia.

Hypoxia contributes to encapsulated pancreatic islet graft failure. To gain insight into the mechanisms that lead to hypoxia-induced graft failure, encapsulated islet function, vitality, and cell replication were assessed after 2 and 5 days of hypoxic (1% O2) and normoxic (20% O2) culture. The mRNA expression levels of Bcl-2, Bax, inducible nitric oxide synthase (iNOS), and monocyte chemoattractant protein 1 (MCP-1) were assessed, as well as the amount of nitrite and MCP-1 in the culture medium. Hypoxia was associated with loss of encapsulated islet function and vitality, but not with an increase in islet cell replication. Loss of vitality was due to necrosis, and only modestly due to apoptosis. Hypoxia was not associated with changes in the Bcl-2/Bax mRNA ratio, but it did increase the expression of iNOS and MCP-1 mRNA. The increased mRNA levels were, however, not associated with elevated concentrations of nitrite nor with elevated levels of MCP-1 protein. The increased iNOS mRNA levels imply a role for NO in the completion of cell death by hypoxia. The increased MCP-1 mRNA levels suggest that encapsulated islets in vivo contribute to their own graft failure by attracting cytokine-producing macrophages. The discrepancy between iNOS mRNA and nitrite is explained by the longer half-life of NO during hypoxia. MCP-1 protein levels are underestimated as a consequence of the lower number of vital cells in combination with a higher proteolytic activity due to necrosis. Thus, strategies to eliminate hypoxia may not only improve islet function and vitality, but may also reduce the attraction of macrophages by encapsulated islets.

[One hundred years of the Association of Surgeons in the Netherlands. VI. The training]. / Honderd jaar Nederlandse Vereniging voor Heelkunde. VI. De opleiding.

Over the last 25 years the organisation and content of the residency training program for general surgeons have been adapted to meet the needs of changing surgical practice. Recently more profound changes have been dictated by the Dutch Working Hours Act, which has strictly limited the working hours of resident physicians. With this the emphasis will be on improving theoretical and practical training methods. Because of the limiting working hours resident physicians will have a smaller role in patient care. These changes will require a huge effort from both the teaching surgeons and the resident physicians, as well as substantial financial investments from the government and healthcare providers.

Clinical experience with non-penetrating vascular clips in free-flap reconstructions.

To date, the gold standard for performing a microvascular anastomosis has been the penetrating suture with attached needle. During the last two decades, non-penetrating techniques have been introduced, including the Unilink system for end-to-end anastomoses, and the VCS clip-applier system for both end-to-end and end-to-side anastomoses. The aim of this study was to compare the results of different techniques used to create microvascular anastomoses in free-flap reconstructions. Between January 1995 and October 1999, we performed 474 microvascular anastomoses in 216 consecutive free-tissue transfers. The anastomosis techniques included manual sutures (42%), Unilink rings (34%) and VCS clips (24%). Seven combined sutured-clipped anastomoses were excluded from further analysis. The mean anastomotic time when rings were applied was significantly shorter than when using clips (P 0.0001) or sutures (P 0.0001). Venous anastomoses using clips took less time than those using sutures (P 0.05). There were 19 anastomotic failures, all of which lead to early flap failure. Ten flaps were salvaged by early reoperation; nine flaps were lost. Three more flaps were lost as a result of other causes, bringing the flap survival rate down to 94.4%. Early flap failure was caused by failure of the arterial anastomosis in eight cases; all of them were sutured (these represented 5% of all arterial anastomoses with sutures). None of the clipped arterial anastomoses failed. Early flap failure was caused by failure of the venous anastomosis in 11 patients. Three of these anastomoses were sutured (representing 6% of all venous anastomoses with sutures), seven were anastomosed with rings (representing 5% of all venous anastomoses with rings) and one was clipped (representing 2% of all venous anastomoses with clips). Both the VCS clip-applier system and the Unilink system are easy to handle and allow fast microvascular anastomoses without intraluminal penetration. The patency rate of clipped vessels is at least as good as the patency rates of vessels anastomosed using sutures or rings.

Preservation of endothelial integrity and function in experimental vascular anastomosis with non-penetrating clips.

BACKGROUND: Vascular repair with sutures is associated with disruption of the endothelial lining and subsequent thrombus formation on the intraluminal lesions. This experimental study was designed to determine whether the use of non-penetrating clips improved endothelial preservation. METHODS: In ten female pigs, 25-mm arteriotomies were made in both carotid arteries. The arteriotomies were repaired with jugular vein patches. On the left side, the repair was done with 1.4-mm titanium clips, and on the right side with two running 6/0 polypropylene sutures. Next, the aorta was divided and subsequently repaired with 2-mm clips in five of these pigs, and with two running 5/0 polypropylene sutures in the remaining five pigs. Endothelial function was studied at the anastomotic site in the carotid arteries by determination of endothelium-dependent and -independent relaxatory responses. Morphometric examination of the carotid arteries and inspection of the aortic endothelium were performed by means of scanning electron microscopy. RESULTS: Maximal endothelium-dependent relaxation to adenosine 5'-diphosphate was less in sutured than in clipped carotid arteries (P < 0.05), while there was no difference in maximal endothelium-independent relaxation to sodium nitrite. This result in clipped carotid arteries was not accompanied by less intimal hyperplasia. Screening of the aortic anastomotic line showed better preservation of endothelial architecture after clip anastomosis. Mean cross-clamp time for carotid patch repair was significantly less when using clips than with sutures. CONCLUSION: The use of non-penetrating clips for vascular anastomoses preserved endothelial function and structural integrity better than running sutures, although the degree of intimal hyperplasia was similar.

Effects of brain death and hemodynamic status on function and immunologic activation of the potential donor liver in the rat.

OBJECTIVE: To assess the effect on the function and immunologic status of potential donor livers of the duration of brain death combined with the presence and absence of hemodynamic instability in the donor. SUMMARY BACKGROUND DATA: Brain death, regarded as a given condition in organ transplantation, could have significant effects on the donor organ quality. METHODS: Brain death was induced in Wistar rats. Short or long periods of brain death in the presence or absence of hemodynamic instability were applied. Sham-operated rats served as controls. Organ function was studied by monitoring standard serum parameters. The inflammatory status of the liver was assessed by determining the immediate early gene products, the expression of cell adhesion molecules, and the influx of leukocytes in the liver. RESULTS: Progressive organ dysfunction was most pronounced in hemodynamically unstable brain-dead donors. Irrespective of hemodynamic status, a progressive inflammatory activation could be observed in brain-dead rats compared with controls. CONCLUSIONS: Brain death causes progressive liver dysfunction, which is made worse by the coexistence of hemodynamic instability. Further, brain death activates the inflammatory status of the potential donor liver, irrespective of the presence of hypotension. The changes observed may predispose the graft to additional damage from ischemia and reperfusion in the transplant procedure.

Nonpenetrating vascular clips for small-caliber anastomosis.

In the search for better anastomosing techniques, an improved vascular stapler device (VCS clip applier system(R)) has been introduced. The system uses nonpenetrating clips to approximate everted vessel walls. The objective of this study was to determine the effects of nonpenetrating vascular clips on endothelial wound healing. Aortic end-to-end anastomoses were performed in male Wistar rats. A comparison was made between clipped (n = 12) and conventional hand-sewn (n = 6) anastomoses. Patency rates were verified at different time intervals (after 1, 4, and 8 weeks), after which the anastomotic sites were removed. Morphological evaluation was carried out using scanning electron microscopy. All rats survived the procedure. Closure with clips took less time than closure with conventional sutures, with decreasing aortic clamping times for the clipped procedures during the course of the experiments. Patency rates were 100% in both the "clipped" and "sutured" groups. Microscopic examination showed favorable endothelial healing at the clipped anastomotic sites, with less inflammatory reaction at 1 week, and a more complete endothelial regeneration at 4 and 8 weeks follow-up, as compared with the sutured anastomoses. The clip applier holds the promise of a useful device in anastomosing small-caliber vessels, since clip closure takes less time than suturing, while patency rates are identical, and morphological results are favorable. Training is mandatory to obtain technical skills and to achieve optimal results.

[Gastrointestinal surgery and gastroenterology. II. Transplantation of pancreas]. / Gastro-intestinale chirurgie en gastro-enterologie. II. Pancreastransplantatie.

In patients with type I diabetes mellitus, adequate blood glucose control prevents the development or aggravation of late complications. Apart from administration of insulin, transplantation of insulin-producing tissue is also a possibility. Transplantation of Langerhans islets which contain the insulin-producing beta cells is still in its initial phase. Transplantation of the entire pancreas received a boost in the mid-eighties when it became possible to drain the secretion of the exocrine part of the pancreas to the bladder using the duodenum. Other important steps forward were prevention and treatment of rejection and improvement of the preservation fluid. Because pancreas transplantation makes lifelong immunosuppression necessary, it is performed mainly in patients subjected to kidney transplantation because of terminal renal failure. The one-year survival of the patients after simultaneous pancreas and kidney transplantation increased to over 90%, that of the grafted pancreas to 82% and that of the grafted kidney to 86-90%. The one-year survival after transplantation of the pancreas alone increased to 62%. A successful pancreas transplantation leads to independence from insulin treatment and to normal glucose and HbA1c values. Pancreas transplantation also reduces diabetes nephropathy and progression of coronary sclerosis.

Evaluation of two outcome prediction models on an independent database.

OBJECTIVE: To evaluate the performance of the New Simplified Acute Physiology Score (SAPS II) and the admission Mortality Probability Model (MPM0) in a large independent database, using formal statistical assessment. DESIGN: Analysis of the database of a multicenter, multinational, prospective cohort study, EURICUS-I. SETTING: Eighty nine intensive care units (ICUs) from 13 European areas. PATIENTS: Data of 16,060 patients consecutively admitted to the participating ICUs were collected during a period of 4 months. Following the original SAPS II and MPM0 criteria, the analysis excluded: patients <18 ys of age; readmissions; patients admitted with acute myocardial infarction; burns; and patients in the postoperative period after coronary artery bypass surgery. All patients with a length of stay <8 hrs were excluded from the study to keep comparability between both systems. A total of 10,027 patients were analyzed. INTERVENTIONS: Collection of the first 24 hrs' admission data necessary for the calculation of SAPS II and MPM0 and basic demographic statistics. Vital status at discharge from the hospital was registered. MEASUREMENTS AND MAIN RESULTS: Despite having a good discriminative capability, as measured by the area under the receiver operating characteristic (ROC) curves (SAPS II: ROC = 0.822 +/- 0.005 SEM; MPM0: ROC = 0.785 +/- 0.006 SEM), both models presented poor calibration, with significant differences between observed and predicted mortality (Hosmer-Lemeshow goodness-of-fit tests H and C, p < .0001). Both SAPS II (predicted risk >40%) and MPM0 (predicted risk >30%) overestimated the risk of death. The evaluation of the uniformity of fit of SAPS II and MPM0 demonstrated large variations across the various subgroups of patients. CONCLUSIONS: The original SAPS II and MPM0 models did not accurately predict mortality on an independent large international multicenter ICU patient database. Results of studies utilizing general outcome prediction models without previous validation in the target population should be interpreted with prudence.

Changing patterns in graduate surgical education in The Netherlands.

An overview is presented of the organization, outline, and contents of graduate surgical training programs in The Netherlands. Adaptations of these programs to changes in demands in surgical practice and health care delivery systems are discussed. Special emphasis is given to the relation of surgery and the surgical specialties, additional training, theoretic training, and manpower planning. The principal questions regarding the optimal way to respond to changing concepts in the field of surgery are presented and discussed in the context of the situation in The Netherlands, but they seem to be similar in the surgical communities of many countries.

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.

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)

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.

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.

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.

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.

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.

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.