Search PubMed⌕ Search

Biomedical subjects

W L Jongebloed

Publications and source records attributed to W L Jongebloed.

At least 55 records · Page 3Linked to original sources
PubMed1989

Prosthetic microvenous grafting into the femoral vein of the rat; considerations concerning the anastomotic technique.

The sequential thrombotic events which occur after implantation of microvenous prostheses prepared from a polyurethane-based material (I.D. 1 mm, length 5 mm, n = 36) into the rat femoral vein by means of the conventional end-to-end suture technique were evaluated by direct inspection and by scanning electron microscopy during the first 24 postoperative hours. Thrombus formation started at the anastomotic sites on the exposed collagenous vessel wall tissue and increased with increasing postoperative time intervals, leading to complete occlusion of the prostheses after 30 minutes of implantation. As a result of these findings, 8 more microvenous prosthetic implantations were performed with the sleeve anastomotic technique and evaluated after 24 hours. Six of these prostheses were patent with only minimal exposure of collagenous tissue at the anastomotic sites and subsequently minimal thrombus accumulation. Two prostheses left in situ and evaluated after 3 weeks were then still patent and completely endothelialised. Based upon the present study, we recommend the sleeve anastomotic technique for implanting synthetic microvenous prostheses because this technique prevents extensive exposure of collagenous vessel wall tissue at the anastomoses, thus leading to less thrombus accumulation and subsequently to a higher patency rate.

Anastomosis, Surgical↗
PubMed1989

Dentine caries in vivo. Combined scanning electron microscopic and microradiographic investigation.

Dentine subjected to an in vivo demineralization challenge by plaque looses substantial amounts of mineral and is expected to change its ultrastructure. Results are presented of a combined microradiography and scanning electron microscopy (SEM) study on in vivo demineralized human dentine. The tissue was first demineralized in vivo under plaque for 3 weeks and subsequently analyzed by microradiography and SEM. In 6 participants dentine was positioned in a full prosthesis just under M2 in such a way that the outer surface of the tissue was 1.5 mm lower than the surface of the prosthesis; plaque accumulation takes place in the recessed area. A special technique allows SEM observations (at a given distance from the outer surface) on broken thin sections of demineralized dentine with a mineral content determined by microradiography. The results show that the ultrastructure of the dentine changes during severe demineralization. The main ultrastructural features are, however, still largely intact, even if half of the mineral originally present has been lost. In dentine with a mineral content of about 25 vol%, the dentinal tubules are enlarged by about 30%. In vivo demineralized dentine looses mineral in substantial amounts both from intertubular and from peritubular regions.

Adolescent↗
PubMed1989

Remineralization of bovine dentine in vitro. The influence of the F content in solution on mineral distribution.

In this paper remineralization of bovine dentine is reported. After demineralization of the dentine in an acidic gel system creating lesions of about 180 microns depth, the tissue was remineralized in a 1.5 mM Ca and 0.9 mM phosphate containing solution at pH 7 and 37 degrees C for 8 or 21 days. The F content in the remineralization solution was 0.02, 2, or 10 ppm as NaF. Samples were analyzed by means of microradiography and scanning electron microscopy. The results show that remineralization (without F added in solution) causes a decrease in mineral loss and in lesion depth. With 2 or 10 ppm in solution, however, a substantial mineral accumulation in the lesion, but particularly on the original dentine surface, was observed. During 3 weeks of remineralization, mineral accumulations of 67 and 70 vol% of mineral for 2 and 10 ppm F in solution, respectively, were found near the original outer surface, with the sound dentine mineral value being 48 vol%. The combined microradiography and scanning electron microscopy data show that the mineral accumulated is for a major part deposited on the dentine tissue and partly inside. The latter deposition occurred both inside the tubules as well as in the intertubular areas. Inside the tubules dense precipitates were observed. Because several differences exist between bovine and human dentine, an extrapolation to the human in vivo situation is speculative. The results indicate that the presence of fluoride in the parts per million range is important for dentine remineralization efficacy and that the outer surface area in dentine can be 'overremineralized'.

Animals↗
PubMed1988

A model to investigate xerostomia-related dental caries.

The aim of this study was to develop an in vivo model in which onset, progression, and prevention of xerostomia-related dental caries can be studied. The progress of the caries process was investigated on ground and polished human enamel blocks placed in the lower denture of 7 edentulous subjects suffering from xerostomia. During a period of 6 weeks the samples were analyzed at weekly intervals by means of scanning optical monitoring, scanning longitudinal microradiography, scanning electron microscopy, and hardness measurements. Although the indentation length increased significantly within 2 weeks, no demineralization could be yet observed with scanning optical monitoring, longitudinal microradiography, and electron microscopy in most samples. Starting from the 3rd week a progressive demineralization could be observed by all methods. The mineral loss (hydroxyapatite) in the 3rd week was 0.0126 kg.m-2 (median) which increased to 0.0761 kg.m-2 after 6 weeks. Scanning electron microscopy showed a destruction which resembled that of natural xerostomia-related dental caries. From this study it may be concluded that the in vivo model developed is suitable for studying onset, progression, and prevention of xerostomia-related dental caries.

Aged↗
PubMed1987

Artificially induced developmental defects in sheep enamel examined by scanning electron microscopy.

Upper incisor teeth from sheep infected with parasites or given 6 mg fluoride per kg bodyweight for 21 days during the period of tooth formation were examined with SEM and microradiography. It was found using both techniques that there had been a severe disturbance of the secretory ameloblasts leading to enamel hypoplasia. It is suggested that it is the severity rather than the cause of the insult to the ameloblasts which determines the degree of hypoplasia.

Ameloblasts↗
PubMed1986

A SEM-correlation of the anatomy of the vitreous body: making visible the invisible.

The naked human vitreous (sclera, iris and cornea removed) suspended in water does not reveal inner structures. After ink injection into the vitreous, the presence of different compartments and the existence of cisterns becomes evident. A concept of the internal system of cisterns is given on the basis of stereoscopic-lightmicroscopic images. An attempt is made to correlate images of the complete vitreous body, obtained with a stereo-lightmicroscope, with images of segments of cisternal walls produced with a scanning electron-microscope (SEM). A comparison is made between SEM-images of the vitreous bodies of human and rabbit eyes.

Animals↗
PubMed1986

A SEM-study of a keratoconus and an artificially aged human cornea.

The substructure of both the epithelial and endothelial surfaces of a keratoconus and an artificially aged cornea was compared with that of a healthy cornea by investigating them with a scanning electron microscope. From the depressions around the protruding centre of the epithelial surface of the keratoconus cornea, and from the whole epithelial surface of the artificially aged cornea, cells detached themselves, assuming a more or less rounded shape. The endothelial surface of both the keratoconus and the aged cornea showed areas of cells with an almost completely disintegrated cell membrane, exposing the cell contents. On the endothelial surface of the keratoconus cells were found with a missing cell-nucleus and a perforated cell membrane, due to a 'Kammerwasser Einbruch' effect.

Aging↗
PubMed1986

Degradation of polypropylene in the human eye: a SEM-study.

A polypropylene surgical suture, which had served as fixation suture for an IOL for a period of 6.5 years, was removed from the eye of a Dutch patient because it had broken at one end and thus formed a potential risk for a corneal touch syndrome. After careful rinsing in 50% ethanol, to remove adhering debris, it was prepared for SEM. A virgin piece of polypropylene material from a surgical package underwent the same preparative procedure. The fixation suture showed cracks perpendicular to the longitudinal axis of the suture; part of the surface layer was nearly detached or completely missing; while the diameter of the suture was decreased towards both ends by over 50% in comparison with the original diameter. The exposed subsurface layer showed a fibrillar structure. The degradation phenomena are considered to be caused by the enzymatic action of tissue-fluids. Virgin material did not show any of the phenomena observed on the fixation suture under consideration.

Eye↗
PubMed1986

Membrane formation and endothelial cell growth on an intra-ocular lens in the human eye, a SEM study.

In this study we have demonstrated the formation of an acellular and a cellular membrane on the surface of an explanted intra-ocular lens by scanning electron microscopy. The acellular membrane is considered to be the result of a physiological process, whereas the cellular membrane is looked upon as a pathological endothelial membrane formed as the result of intermittent touch between the implant and the endothelium.

Aged↗
PubMed1986

Mechanical and biochemical effects of man-made fibres and metals in the human eye, a SEM-study.

Prolene, perlon, supramid and titanium, either used as sutures, 'Strampelli' sutures or artificial lens loops, were compared after remaining in the human eye for at least one year. For comparison, non-implanted samples of each of the materials were used as blanks. Prolene and Perlon in particular showed severe biodegradation after a given period; Supramid showed much less degradation of its surface. Titanium showed a rather rough outer surface (even in the non-implanted samples), particularly as bends in the lens loop, which facilitated the adherence of cells, fibres and microorganisms.

Azepines↗
PubMed1986

Some considerations on experimental lens implant in the rabbit eye, a SEM-study.

Intraocular implantation of an iris-bridge or lobster-claw lens was performed on a rabbit eye. The incisions were closed with stainless steel-vanadium sutures. Two months after implantation loosening at one side of the connection between lens and iris was noted, which resulted in long-term intermittent touch of the corneal endothelium. The reaction of the endothelium to the corneal sutures and the contact area of artificial lens and corneal endothelium were studied by SEM.

Animals↗
PubMed1986

A keratoprosthesis successfully implanted in the cornea of a rabbit, a SEM-study.

By means of a new fixation technique keratoprostheses were fixed in the cornea of 'Hollander' rabbits. The fixation is based on the use of corneo-sclerally orientated stainless steel-vanadium traction threads in corneal stroma and scleral tissue. Keratoprostheses placed according to this fixation technique have a follow-up of a maximum of two years. The liquid sealing capacity, the cell behaviour on the surface of the prosthesis and the anchoring of the stainless steel vanadium wire have been investigated in detail with the scanning electronmicroscope (SEM).

Animals↗
PubMed1986

Scanning electron microscopy study of experimental intraocular lens implantation in the rabbit eye.

Extracapsular surgery was performed on a rabbit eye for implantation of a lobster-claw or iris-bridge type intraocular lens (IOL). The incision was closed with stainless steel-vanadium sutures of 50 micron diameter. Two months after implantation, one pincer of the lens became detached from the iris, causing an intermittent IOL-endothelial touch of four months duration. It resulted in endothelial disruption with localized breaks in Descemet's membrane. Six months after implantation, the IOL and the entire anterior segment were removed and processed for scanning electron microscopy. The lobster-claw lens had been covered partly with a membrane, composed of different types of cells with many microvilli, particularly in the vicinity of the loophole of the intact iris bridge. The sutures were almost completely covered with somewhat irregular endothelial cells and an intact Descemet's membrane. At isolated spots where the covering was incomplete, elongated cells with many microvilli bordered the open areas. At the site of breaks, Descemet's membrane was denuded and in the process of being repopulated with cells. At places of minor disruption, elongated and triangular-shaped endothelial cells, often having many microvilli and interconnections with philopodia-like extensions, were about to cover the "wounded" area.

Animals↗