HISTOLOGICAL, IMMUNOHISTOCHEMICAL, ТЕМ AND SEM INVESTIGATIONS IN THE VALVE-CUSP FREE BORDER OF GREAT VARICOSE SAPHENOUS VEIN

The authors studied venous valve cusps from surgically removed great saphenous vein with essential lower limb varicosis from 20 patients without data about previous thrombophlebitis. Venous valves without varicose alterations were used as controls. The histological, immunohistochemical, ТЕМ and SEM techniques were applied. In morphologically complete valve cusps from non-varicose great saphenous vein, a small marginal thickening was observed by routine histology. The cells visualised in these thickenings showed positive reaction against anti-vimentin but negative reaction against anti—smooth muscle actin antibody. In varicose vein valve cusps a marginal thickening with considerably larger diameter was histologically observed. In the fibrin-like material which was disposed around these thickenings, proliferation of fibroblasts as well as collagen fibres' depositions were seen. The SEM study showed partial "rollings" of the free cusp border. In the marginal thickening, the cells showed negative reaction not only to anti—smooth muscle actin but they also lost the reaction to anti-vimentin monoclonal antibody. The process mentioned above advanced, it occupied a new part at the valve cusp and so the cusp shortened. According to our hypothesis, this was one of the ways of initiating and advancing incompetence in primary varicosis

The marvel of percutaneous cardiovascular devices in the elderly

Thanks to minimally invasive procedures, frail and elderly patients can also benefit from innovative technologies. More than 14 million implanted pacemakers deliver impulses to the heart muscle to regulate the heart rate (treating bradycardias and blocks). The first human implantation of defibrillators was performed in early 2000. The defibrillator detects cardiac arrhythmias and corrects them by delivering electric shocks. The ongoing development of minimally invasive technologies has also broadened the scope of treatment for elderly patients with vascular stenosis and aneurysmal disease as well as other complex vascular pathologies. The nonsurgical cardiac valve replacement represents one of the most recent and exciting developments, demonstrating the feasibility of replacing a heart valve by way of placement through an intra-arterial or trans-ventricular sheath. Percutaneous devices are particularly well suited for the elderly as the surgical risks of minimally invasive surgery are considerably less as compared to open surgery, leading to a shorter hospital stay, a faster recovery, and improved quality of life

The Role of Bloom Index of Gelatin on the Interaction with Retinal Pigment Epithelial Cells

Biocompatible materials are of considerable interest in the development of cell/drug delivery carriers for therapeutic applications. This paper investigates the effects of the Bloom index of gelatin on its interaction with retinal pigment epithelial (RPE) cells. Following two days of culture of ARPE-19 cells with gelatin samples G75-100, G175, and G300, the in vitro biocompatibility was determined by cell proliferation and viability assays, and glutamate uptake measurements, as well as cytokine expression analyses. The mitochondrial dehydrogenase activity in the G300 groups was significantly lower than that of G75-100 and G175 groups. The Live/Dead assays also showed that the gelatin samples G300 induced mild cytotoxicity. In comparison with the treatment of gelatins with low Bloom index, the exposure to high Bloom strength gelatins markedly reduced the glutamate uptake capacity of ARPE-19 cells. One possible explanation for these observations is that the presence of gelatin samples G300 with high viscosity in the medium may affect the nutrient availability to cultured cells. The analyses of pro-inflammatory cytokine IL-6 expression at both mRNA and protein levels showed that the gelatins with low Bloom index caused less cellular inflammatory reaction and had more acceptable biocompatibility than their high Bloom strength counterparts. These findings suggest that the Bloom index gives influence on cellular responses to gelatin materials

Pivoting system fracture in a bileaflet mechanical valve: A case report

A leaflet escape occurred in a low profile bileaflet mechanical prosthesis manufactured by TRI-Technologies that had been implanted for 3 years in the mitral position of a 32 year old patient. The escaped leaflet had embolized and was subsequently located by an abdominal computerized axial tomography scan and ultrasound in the terminal portion of the aortic bifurcation. The embolized leaflet was removed 3 months after valve replacement surgery. In an attempt to determine the cause of the escape the retrieved embolized leaflet was investigated. Techniques employed included visual examination aided by stereo-microscopy, x-ray imaging and scanning electron microscopy. One of the ears had fractured and was missing from the leaflet. Chipping was observed at the leaflet ear position on both the inflow and outflow surfaces. Visual and SEM observations found fractographic river-lines that indicated an apparent origin at the inflow surface of the ear nearest to the straight ‘B-datum’ line or coaptation edge. The origin seemed to be in the radius between the leaflet ear and the leaflet body. SEM observation of the remaining intact ear showed wear marks on both the inflow and outflow sides of the leaflet ear that corresponded to the suspected origin of fracture. It is believed that the use of boron alloyed pyrolytic carbon material and the leaflet\u27s homogeneous monolithic structural design were factors that contributed to this adverse event

Transrenal Deployment of a Modular Stent Graft to Repair AAAs with Short Necks: Experiments in Dogs

Severely angulated (> 60°) or short (< 15mm) proximal necks remain significant anatomical limitations for endovascular stent-graft repairs for abdominal aortic aneurysms. Ensuring proper proximal fixation of the stent-graft to the host artery without the short-or long-term risks of endoleak or migration represents a particular technical challenge for these anatomical circumstances. An innovative balloon expandable stent combined with a weft-knitted prosthesis was specifically designed for these situations by modelling the stent to the neck anatomy without overdistension or potential barotrauma allowing better incorporation of the device. The Latecba stent-graft consists of a 2 parts modular design. The first one, Module A, is deployed at the transrenal level and consists of a Palmaz type stent whose first half is bare and second half is sutured to a crimped weft-knitted polyester graft whose distal end holds a constriction. The second Module B is a non-crimped weft-knitted graft attached to 2 stainless steel stents. The first stent is entirely contained in the proximal textile tube, allowing fixation to module A. The second stent, which is left uncovered over the distal third, ensures proper fixation of the stent-graft distally. Following the creation of a prosthetic aneurysm in the infrarenal aorta in 32 dogs, 29 received the Latecba stent-graft for scheduled durations of 10 days, 1 month, 3 months and 6 months. Proper deployment of the stent-grafts was achieved without difficulty. All 29 animals survived and the devices were all patent at sacrifice. No device defects or migrations were observed and the stent-grafts proved to be efficient in this setting to exclude the aneurysm. Analyses of the explanted devices (gross observations, RX, CT scan, IVUS, angioscopy) confirmed the stability of this modular stent-graft. Further on-going clinical investigations are warranted to validate this concept before this stent-graft becomes commercially available without any restriction

A Floating Thrombus Anchored at the Proximal Anastomosis of a Woven Thoracic Graft Mimicking a Genuine Aortic Dissection

An aortoesophageal fistula following surgery for a ruptured 6.6-cm thoracic aneurysm in a 69-yearold female was repaired using a 34-mm woven prosthetic graft. A follow-up computed tomography (CT) scan at 10 days postoperatively revealed a dissection-like picture in the region of the graft, which was treated conservatively. The patient eventually died from sepsis and multiorgan failure. At autopsy, the graft was retrieved in situ and studied by detailed gross, microscopy, and scanning electron microscopy (SEM) examination. Gross observation confirmed that the dissection resulted from the rolling of the internal capsule downstream. A massive thrombus anchored at the proximal anastomosis and held by a narrow head was also noted. The thrombus demonstrated reorganization in the area of the anastomosis, with a false lumen in its distal half. The reminder of the thrombus consisted of layered fibrin. After gross examination, the fabric graft was found to be flawless. Additional detailed studies were also done using microscopy, SEM, and gross examination

Osteochondral defects : present situation and tissue engineering approaches

Articular cartilage is often damaged due to trauma or degenerative diseases, resulting in severe pain and disability. Most clinical approaches have been shown to have limited capacity to treat cartilage lesions. Tissue engineering (TE) has been proposed as an alternative strategy to repair cartilage. Cartilage defects often penetrate to the subchondral bone, or full-thickness defects are also produced in some therapeutic procedures. Therefore, in TE strategies one should also consider the need for a simultaneous regeneration of both cartilage and subchondral bone in situations where osteochondral defects are present, or to provide an enhanced support for the cartilage hybrid construct. In this review, different concepts related to TE in osteochondral regeneration will be discussed. The focus is on the need to produce new biphasic scaffolds that will provide differentiated and adequate conditions for guiding the growth of the two tissues, satisfying their different biological and functional requirements

Surface pretreatments for medical application of adhesion

Medical implants and prostheses (artificial hips, tendono- and ligament plasties) usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m). This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body