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Biomedical subjects

B van der Lei

Publications and source records attributed to B van der Lei.

At least 19 recordsLinked to original sources
PubMed1996

The 3M precise microvascular anastomotic system for implanting PTFE microvenous prostheses into the rat femoral vein.

Successful implantations of PTFE microvenous prostheses with 3M precise anastomosis systems were presented. Twelve PTFE prostheses (Gore-Tex;I.D.1.0 mm) were implanted into rat femoral veins by means of 3M precise technique to evaluated the patency rate. In the control group, PTFE prostheses (n = 12) were implanted by means of end-to-end technique. In the experimental group, patency of the PTFE prostheses was evaluated at 3 (n = 6) and 6 (n = 6) weeks after implantation by means of macroscopic inspection and scanning electron microscopy. All prostheses except one were patent at the time of removal (patency rate 91.7 percent). All the microvenous prostheses were completely covered by an endothelial layer at 3 and 6 weeks after implantation, and no stenosis was observed at the anastomotic sites. In the control group, all prostheses except one were found to be occluded 3 weeks after implantation. These results demonstrate the value of the 3M precise technique when implanting PTFE microvenous prostheses.

Anastomosis, Surgical↗
PubMed1995

Biological performance of a degradable poly(lactic acid-epsilon-caprolactone) nerve guide: influence of tube dimensions.

One of the ways to reconstruct a nerve defect is to use a biodegradable nerve guide. The aim of this study was to establish a nerve guide constructed of an amorphous copolymer of lactic acid-caprolactone. A pilot study was set up to elucidate the effect of the tube dimensions on nerve regeneration. Four types of nerve guides, with internal diameters ranging from 1.12-1.23 mm and wall thicknesses ranging from 0.34-0.68, were tested for this purpose. We evaluated the biodegradation, foreign body reaction and nerve regeneration by light microscopy, after three different implantation times (1, 2, and 3 months). After 2 months, we observed that all types of nerve guides had changed from a transparent to an opaque and swollen state, and that they had lost their strength. The foreign body reaction was characterized by the presence of giant cells and fibroblasts surrounding the degrading nerve guide. From this pilot study, we conclude that nerve guide type 1, with an internal diameter of 1.23 mm and a wall thickness of 0.34 mm, can ensure nerve regeneration in the case of a 1-cm gap in the sciatic nerve of the rat. Nerve guides types 3 and 4, with relatively small lumens, show nerve compression due to a more pronounced swelling of the degrading tube.

Animals↗
PubMed1995

Influence of luminal pore size on the patency rate and endothelialization of polymeric microvenous prostheses.

In microvenous prosthetic surgery a continuous search for better patency rates is necessary to enable a clinical application. In this search for better patencies, modifications in the wall structure are being made. Directions found in the literature suggest that pore size plays an important role in achieving better patencies. Thus far, no study has been conducted to evaluate the influence of pore size on the patency rate of polyurethane microvenous prostheses. Since polyurethane is known to yield good patency rates, we conducted this study in which we compared different luminal pore sizes with regard to patency. Pore size varied from 0.6 to 20 microns in microvenous polyurethane-based prostheses (length 5-6 mm, internal diameter 1 mm). The results showed a favorable patency rate in the pore sizes larger than 5.0 microns (patency 75%) when compared to pore sizes smaller than 2.0 microns (patency 50%). This study demonstrates that microvenous polyurethane-based prostheses with a luminal pore size larger than 5.0 microns may yield better patency rates than prostheses with a luminal pore size smaller than 5.0 microns. Further studies are currently being performed to elucidate the very reasons for this effect.

Animals↗
PubMed1994

Fractures of the metacarpals. A retrospective analysis of incidence and aetiology and a review of the English-language literature.

In this study, we review the incidence and aetiology of 3858 metacarpal fractures in a series of 235,427 patients across the life-span. We found men aged 10-29 to have the highest incidence rates for metacarpal fracture (2.5 per cent). Accidental fall was the dominant cause of these fractures in the age group 9 years or less (38.7 per cent) and in the groups 50 years and older. Our data clearly show transport accidents and in particular bicycle accidents to be major determinants in all age groups. We conclude that recognition of the high frequency of metacarpal fractures among men aged 10-29 years should be given and public expenditure should be invested in the development and recommendation of proper safety gear.

Accidental Falls↗
PubMed1994

Phalangeal fractures of the hand. An analysis of gender and age-related incidence and aetiology.

The incidence and aetiology of 6,857 phalangeal fractures of the hand have been reviewed in a series of 235,427 patients, looking for an age-specific vulnerability to fracture. We found sports to be the main cause of fracture in the 10-29 years age groups and accidental falls to be the leading cause in those aged 70 years or older. We made a new observation that the highest incidence occurs in the male 40-69 age group and machinery was the dominant cause of fracture in this group. Recognition of the frequency of industrial trauma is needed, and public expenditure should be invested in its prevention and treatment.

Accidental Falls↗
PubMed1993

Patency and healing of microvascular prostheses: a review of 10 years of experimental work in Groningen.

From 1982 onwards, in Groningen, The Netherlands, we have worked on the experimental evaluation and development of microvascular prostheses in rats and rabbits. In this review article a systematic overview of this experimental work is presented and the results are discussed with regard to the literature to come to a current state of the art on (experimental) microvascular grafting with prosthetic conduits.

Anastomosis, Surgical↗
PubMed1993

Autologous vein supported with a biodegradable prosthesis for arterial grafting.

To evaluate the potential of a supporting, compliant, biodegradable prosthesis to function as a temporary protective scaffold for autologous vein grafts in the arterial circulation, we implanted vein grafts into the carotid arteries of rabbits, either with (composite grafts) or without (control grafts) such a supporting prosthesis, and evaluated them up to 6 weeks. The control vein grafts showed edema and severe medial disruption with infiltration of polymorphonuclear cells on day 1. Over the study, irregular fibrocyte formation resulted in the formation of a fibrotic vein wall. In contrast, the composite vein grafts showed preservation of smooth muscle cell layers and elastic laminae with a minor inflammatory response. Regular proliferation of fibroblasts, which in some areas were circularly oriented, was observed. We conclude that a supporting, compliant, biodegradable prosthesis can function as a protective scaffold for vein grafts in the arterial circulation, thus reducing damage to the vein graft wall and allowing gradual arterialization.

Animals↗
PubMed1993

Degradation of a supporting prosthesis can optimize arterialization of autologous veins.

In a previous study, we implanted autologous vein grafts in the carotid artery of rabbits supported by a compliant, biodegradable prosthesis to prevent vein wall damage due to the higher arterial pressure. We showed that such a supporting prosthesis indeed reduces damage to these vein grafts and allows for more regular and gradual arterialization than that afforded by unsupported vein grafts. To evaluate the influence of the rate of biodegradation of such a supporting prosthesis on the process of arterialization of autologous vein grafts, we implanted vein grafts supported with prostheses, which degrade within 3 weeks (group I), 6 weeks (group II), or 3 months (group III), into the carotid artery of rabbits, and then evaluated them up to 6 weeks after implantation. At 6 weeks, the group I vein grafts showed a thinner vein wall than did the adjacent artery during dilatation. In group II, the vein wall thickness and luminal diameter had completely adjusted to that of the adjacent carotid artery. The group III vein grafts showed a significantly thinner vein wall in the absence of dilatation. All supported vein grafts showed regular longitudinally oriented and, in some areas, circularly oriented cell layers, together with thin elastic laminae, which were most pronounced in group II. We conclude that a supporting, compliant prosthesis can stimulate, regulate, and optimize the arterialization of autologous vein grafts in rabbits. If the rate of degradation is carefully chosen, the radius and wall thickness of the vein graft can completely adjust to that of the adjacent artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Healing of microvenous PTFE prostheses implanted into the rat femoral vein.

44 PTFE prostheses (Gore-Tex; ID 1 mm) were implanted into rats' femoral veins by means of the sleeve anastomotic technique and were evaluated at regular intervals from 1 h up till 24 weeks after implantation by means of light and electron microscopy to study in detail their healing process. All prostheses, except one at 1 week and one at 24 weeks after implantation, were patent at the time of removal. Upon implantation, the luminal surface of the prostheses became covered with a thin clot layer. From 1 week onwards, endothelial cells originating from the anastomotic sides grew in across the anastomoses. In addition, small capillary-like orifices were present at the anastomotic sites, from which endothelial cells also seemed to originate. At 2 weeks, in several areas in the mid-region of the prostheses, the fronts of regenerating endothelial cells had reached each other, and about 80% of the luminal surface was covered by endothelium and at 3 weeks, the prostheses were completely covered by an endothelial layer. These results demonstrate that PTFE microvenous prostheses heal exclusively by means of rapid ingrowth of endothelial cells originating from both sides at the anastomoses.

Animals↗
PubMed1993

Correction osteotomies of phalanges and metacarpals for rotational and angular malunion: a long-term follow-up and a review of the literature.

Correction osteotomies of nine phalanges and six metacarpals for rotational and angular malunion were performed in 15 patients ranging from 20 to 75 years of age and followed a mean period of 4.5 years, ranging from 1 to 11 years. Full correction of the preoperative deformity was achieved in 13 of the 15 patients (87%), bony union in 100%, and no loss of preoperative range of motion was observed, except in one patient who underwent additional arthrodesis. A high satisfaction rate was seen among 13 of the 15 patients. These results underline that osteotomies of phalanges and metacarpals for angular and rotational malunion can have significant functional benefits for the well-being of patients.

Adult↗
PubMed1993

Prosthetic microvenous grafting in the rat femoral vein.

Male Wistar rats were used to evaluate microvenous prosthetic grafting techniques and microvenous prostheses in the femoral vein. With the end-to-end technique to implant microvenous prostheses, there was extensive exposure of vessel wall collagen especially at the suture sites. Thrombus formation then led to complete occlusion in all but one of the 32 prostheses 60 min after implantation. However, with the sleeve anastomotic technique there was only minimal exposure of collagen and minimal thrombus accumulation. Fifty-nine of the 64 microvenous prostheses implanted with the sleeve technique were patent after 1 day, 1, 3, 6, and 12 weeks (patency rate 92%). All patent microvenous prostheses were completely covered by an endothelial layer after 3 weeks. It was concluded that the rat is an appropriate experimental laboratory animal for evaluating new grafting techniques with microvenous prostheses and that the sleeve anastomotic technique gives the highest patency rates with microvenous prostheses.

Anastomosis, Surgical↗
PubMed1993

Expanded polytetrafluoroethylene patch versus polypropylene mesh for the repair of contaminated defects of the abdominal wall.

Contaminated defects of the abdominal wall continue to be a significant problem for patients and surgeons. The lack of sufficient tissue may require the insertion of a prosthetic material. Polypropylene (PP) mesh is still the most widely used material for this purpose, although the propensity to induce extensive visceral adhesions and erosion of the skin or intestine is a well-known drawback. Expanded polytetrafluoroethylene (PTFE) patch has better mechanical properties and has a low potential for infection. Therefore, we used expanded PTFE patch to repair contaminated abdominal wall defects in three patients. In one patient, the postoperative course was uneventful. In the other two patients, the patch had to be removed for ongoing wound sepsis and because the patch disintegrated. In an experimental study, contaminated abdominal wall defects created in Wistar rats were repaired with expanded PTFE patch (PTFE group, n = 21) or PP (PP group, n = 21). Wound infection occurred in 16 rats in the PTFE group and in 14 rats in the PP group. Two rats in each group died. Two rats in the PTFE group died as a result of peritonitis, one rat in the PP group died as a result of ileus and one as a result of peritonitis. Incisional hernia was found to be significantly more frequent in the PTFE group (n = 13) than in the PP group (n = 3). Fistula formation was only found in three rats in the PP group. Adhesion formation was more pronounced in rats in the PP group. It is concluded that the expanded PTFE is unsuitable for the reconstruction of contaminated abdominal wall defects and that PP mesh is more suitable, although this material has a high risk of complications.

Abdominal Muscles↗
PubMed1992

The use of the saddle prosthesis for reconstruction of the hip joint after tumor resection of the pelvis.

Reconstruction of the hip joint by a saddle prosthesis after excision of a malignant pelvic tumor is a relatively new method, which thus far has been mainly used for revision of infected hip arthroplasties. One patient with a metastatic cystosarcoma phyllodes and one patient with a chondrosarcoma of the pelvis were treated by local resection and reconstruction with a saddle prosthesis. Although the patient with the metastatic cystosarcoma phyllodes died 9 months after surgery due to metastatic disease, both patients had early recovery, with no difference in leg length and obtained early painless complete weight bearing with satisfactory functional result. These two case reports clearly illustrate the usefulness of the saddle prostheses in limb saving surgery for malignant tumors of the pelvis.

Adult↗