Biomedical subjects

H K Koerten

Publications and source records attributed to H K Koerten.

At least 19 recordsLinked to original sources

PubMed1992

Cellular reaction on the intraperitoneal injection of four types of polylactide particulates.

Four types of polylactide particulates, P-L-LA 100, 250, 550 KD and a P-DL-LA 400 KD were injected into the peritoneal cavity of mice. The inflammatory reaction showed an increase in cell number (mainly neutrophilic granulocytes) up to 48 h after which the cell numbers decreased below the control (phosphate-buffered saline). All four polylactide particulates aggregated and intermingled with inflammatory cells. The aggregates remained throughout the investigation period of 6 months. Quantitative measurements showed that standardization of the particle form and size is essential. From this study and other experiments in which calcium phosphates and asbestos were injected intraperitoneally, it is concluded that the inflammatory response observed in the peritoneal cavity is related to the type of material injected and probably to form and size of the individual particles, but not to molecular weight.

Animals↗

PubMed1992

Analysis of primary bone formation in porous alumina: a fluorescence and scanning electron microscopic study of marrow cell induced osteogenesis.

Porous alumina ceramics alone and combined with rat marrow cells were implanted subcutaneously in the back of syngeneic Fischer rats. Fluorochrome-labeling was performed post operatively and the ceramics were harvested 6 and 8 weeks after implantation. Undecalcified sections of the implants were observed under fluorescence microscopy and the de novo bone-ceramic interfacial areas were analyzed by a scanning electron microscope equipped with an electron probe microanalyzer. Alumina ceramics alone did not show any bone formation, while all marrow cell loaded ceramics showed new bone formation 6 and 8 weeks after implantation. Bone formation was first observed in the center of the pores and proceeded in a centrifugal direction, leading to contact with the ceramic. These results suggest that bone marrow cells have inherent osteogenic capacity and in the pore region of alumina ceramics progression of the osteogenesis causes the dissipation of intervening fibrous tissue between the de novo bone and alumina ceramic surface.

Aluminum Oxide↗

PubMed1991

Reactions of cells at implant surfaces.

The surface of implants is an important parameter in host-implant integration. Several strategies can be used to obtain integration, such as the application of grooves or pores at the implant surface. Most of these surface alterations, however, will lead to an increase of total implant surface area which might influence the inflammatory response to an implant. As far as integration with bone is concerned several biomaterials have been successful in mimicking this material, by having similar crystals at their surface (calcium phosphate ceramics) or by containing a certain amount of calcium and phosphorus. Polyactive, a poly(ethylene oxide)-poly(butylene terephthalate) segmented copolymer, also possesses favourable integration properties with bone, but initially lacks calcium and phosphorus. It is proposed that the application of hydrogels as biomaterial may add a new dimension to integration capacity.

Adsorption↗

PubMed1991

In vivo degradation of processed dermal sheep collagen evaluated with transmission electron microscopy.

The in vivo degradation of hexamethylenediisocyanate-tanned dermal sheep collagen was studied with transmission electron microscopy. Discs of hexamethylenediisocyanate-tanned dermal sheep collagen were subcutaneously implanted in rats. Both an intra- and an extracellular route of degradation could be distinguished. In addition to normal components of a typical foreign body reaction, remarkable phenomena, such as locally deviant neutrophil morphology, infiltration of basophil-like cells, indications of foreign body multinucleate giant cells formed from different cell types, aluminium silicate accumulations and calcium phosphate depositions, were observed. Foreign body multinucleate giant cells intracellularly degraded hexamethylenediisocyanate-tanned dermal sheep collagen after internalization. Both internalized and cellularly enveloped hexamethylenediisocyanate-tanned dermal sheep collagen degraded by the detachment of fibrils. Another extracellular route of degradation was characterized by calcium phosphate depositions in large bundles of hexamethylenediisocyanate-tanned dermal sheep collagen. From 6 wk, the hexamethylenediisocyanate-tanned dermal sheep collagen implant was replaced by rat connective tissue, which was subsequently also degraded. After 15 wk, the presence of basophil-like foreign body multinucleated giant cells containing aluminium/silicon-crystalline accumulations still persisted. These phenomena were related to the specific nature of the material used and suggest cytotoxicity. They emphasize the need for detailed evaluation at the ultrastructural level of newly developed biomaterials before they can be used for medical applications.

Animals↗

PubMed1991

Polyethyleneimine as a contrast agent for ultrastructural localization and characterization of proteoglycans in the matrix of cartilage and bone.

We examined the presence of proteoglycans in the extracellular matrix of cartilage and bone in fetal mouse radii at the ultrastructural level, using the cationic dye polyethyleneimine (PEI). After staining with this dye, the proteoglycans appeared as granules in the uncalcified bone matrix and as extended winding structures in the cartilage matrix. PEI-positive material was removed after treatment of the tissue with chondroitinase ABC. Inhibition of the proteoglycan synthesis by beta-D-xyloside resulted in smaller PEI-positive windings in the cartilage matrix. These observations suggest that the winding, PEI-positive structures represent proteoglycan aggregates. No loss of PEI-positive material in the calcified cartilage matrix was seen, suggesting that proteoglycans do not need to be removed to make the matrix calcifiable.

Animals↗

PubMed1990

The biocompatibility of hydroxyapatite ceramic: a study of retrieved human middle ear implants.

The biocompatibility of 11 hydroxyapatite auditory canal-wall prostheses and 4 hydroxyapatite incus prostheses implanted for 4 to 40 months was evaluated by light microscopy, scanning electron microscopy, transmission electron microscopy, and Röntgen microanalysis. These 15 prostheses representing 4% of 375 prostheses, has been removed because of unresolved chronic middle ear infection, residual cholesteatoma, or poor fit. The findings confirmed earlier reports on the biocompatibility of hydroxyapatite in vitro, in animals, and in man. An electron-dense layer was found at the interface with bone and fibrous tissue, and a firm bond between the ceramic and bone at the hydroxyapatite ceramic/bone interface developed. Macropores became filled with bone and fibrous tissue, and the tissue in the individual pores was interconnected. Furthermore the incus prostheses were covered with an epithelium similar to that found in the human middle ear. Findings diverging from those made in other studies were the relatively large amount of exudate in the pores, an apparent increase of degradation during infection, and the accumulation of trace elements in one of the canal-wall prostheses. In all likelihood these three phenomena may be attributed to the unfavorable conditions to which these prostheses were exposed during implantation.

Biocompatible Materials↗

PubMed1990

Biocompatibility of a polyether urethane, polypropylene oxide, and a polyether polyester copolymer. A qualitative and quantitative study of three alloplastic tympanic membrane materials in the rat middle ear.

The biocompatibility of porous implants made of Estane 5714 F1 polyether urethane, polypropylene oxide, and a poly(ethylene oxide hydantoin) and poly(tetramethylene terephthalate) segmented polyether polyester copolymer (HPOE/PBT copolymer), which were selected as candidates for an alloplastic tympanic membrane, was assessed after implantation in rat middle ears for periods of up to 1 year. Implantation of the materials led to tissue reactions initially associated with the wound-healing process, whereas after 1 month not only the presence of macrophages and foreign-body giant cells surrounding the implant materials but also implant degradation were characteristic for a foreign-body reaction. Macrophages and foreign-body giant cells dominated the picture of the tissue surrounding polypropylene oxide. The altered morphology of these cells, the persistent infiltration of the implantation sites by exudate cells, and the premature death of five rats in the 1-year group suggest that polypropylene oxide degradation was accompanied by the release of toxic substances. Estane and copolymer degradation did not induce tissue responses reflecting implant toxicity, and tympanic membranes given these alloplasts showed a normal healing pattern. Inclusions in the cytoplasm of macrophages associated with degradation and phagocytosis of all of the polymers under study were found to contain iron, silicon, titanium, and aluminum. Growth of fibrous tissue and bone, the latter into Estane and HPOE/PBT copolymer implants, indicated appropriate implant fixation by tissue, although macrophages and foreign-body giant cells were present as well. Especially the fixation of copolymer by ingrowth of bone seems promising in terms of the amount of bone in the pores and the electron-dense bone/copolymer interface. The latter is indicative for bonding osteogenesis. The HPOE/PBT copolymer is a better candidate for alloplastic tympanic membrane than Estane, and the use of polypropylene oxide cannot be recommended.

Animals↗

PubMed1990

Evidence of grass-pollen allergenic activity in the smaller micronic atmospheric aerosol fraction.

In June 1988, during the grass-pollen season in Leiden, The Netherlands, outdoor airborne particulate matter was collected and separated into fractions according to aerodynamic sizes (greater than or equal to 10 microns, 4.9-10 microns, 2.7-4.9 microns, 1.3-2.7 microns, 0.6-1.3 microns, less than or equal to 0.6 microns), with a cascade impactor mounted on top of a high volume sampler. The different fractions were tested for the presence of grass-pollen allergenic activity using a RAST-inhibition assay: specific IgE-antibody-containing patient serum was applied on the particle-loaded impaction strips, and the serum was recovered by descending elution for further analysis in the RAST. Simultaneously, continuous measurements were made of the airborne grass-pollen concentration using a volumetric pollen trap. Sampling observations lasting 7-9 hr during a period with relatively high airborne grass-pollen concentrations showed reliably detectable amounts of grass-pollen allergen, not only in the first impaction stage where intact pollen were collected, but also in the lower stages collecting the smaller, paucimicronic and submicron atmospheric aerosol fraction. It is evident that this result has serious implications for the understanding of the bronchial symptoms frequently seen in hay fever patients on days with high pollen concentrations in the air.

Air↗

PubMed1990

Asbestos body formation and iron accumulation in mouse peritoneal granulomas after the introduction of crocidolite asbestos fibers.

This report describes the cell biology of the development of asbestos bodies after a single intraperitoneal injection of a suspension of crocidolite asbestos fibers into the mouse peritoneal cavity. The majority of the infected fibers were found in aggregates of peritoneal macrophages, exudate cells, and fibrous tissue. These aggregates developed into granulomas containing not only numerous asbestos fibers, but also cells of various types, including macrophages, multinucleated giant cells, fibroblasts, plasma cells, granulocytes, and mast cells. Cytoplasmic ferritin was abundantly present in macrophages and giant cells. In addition, iron-rich inclusion bodies were detected. The results of this study show that asbestos body formation can occur outside the pleural cavity. Asbestos body formation occurred in the granulomas after periods of 1 month and longer. On the basis of morphologic criteria, various types of asbestos body were distinguished. X-ray microanalysis showed that variations in the density of the coat could attributed to the presence of chemical elements in various concentrations. Evidence is presented that asbestos body formation is an extracellular phenomenon.

Animals↗

PubMed1990

The formation of asbestos bodies by mouse peritoneal macrophages. An in vitro study.

For studies on the mechanism of asbestos body formation, Union Internationale Contre Cancer (UICC) crocidolite asbestos fibers were added to a culture of mouse peritoneal macrophages. Small asbestos fibers were totally ingested by the macrophages, but fibers too long to be taken up completely remained as a consequence extracellular. These long asbestos fibers became the basis for asbestos body formation. The basic mechanism underlying asbestos body formation was found to be the exocytotic activity of macrophages. The number of iron-rich inclusion bodies was dependent on the availability of iron in the culture media, and the same holds for the amount of iron in the asbestos body coat. This means that asbestos body formation is a phenomenon that occurs accidentally when macrophages come into contact with long fibers in an iron-rich environment. A time-dependent increase in the number, average size, and rate of segmentation of the asbestos bodies was observed. The present report is the first to describe asbestos body formation in vitro.

Acid Phosphatase↗

PubMed1989

An activating and cytotoxic effect of asbestos on polymorphonuclear leukocytes.

Chrysotile asbestos induces extensive enzyme release from polymorphonuclear leukocytes (PMNs). The release of the cytoplasmic enzyme lactate dehydrogenase implies membrane damage and cytotoxicity. In the presence of extracellular Ca2+ asbestos exerts an activating effect, evident from the release of granule-associated enzymes by exocytosis. Both the cytotoxic and activating effect of asbestos may contribute to asbestos-induced tissue damage.

Animals↗

PubMed1989

The involvement of ionic interactions during asbestos-induced enzyme release from polymorphonuclear leukocytes.

Chrysotile asbestos permeabilizes the plasma membrane of rabbit polymorphonuclear leukocytes (PMNs) which is evident from the release of the cytoplasmic enzyme lactate dehydrogenase (LDH) from the cell. When Ca2+ is present in the medium exocytosis is observed, evident from the release of the granule associated enzyme lysozyme which is not liberated in the absence of Ca2+. Asbestos-induced enzyme release is inhibited by polyanions or by removal of positive charges on asbestos, and resembles enzyme release induced by synthetic polycations. Pretreatment of PMNs with neuraminidase does not affect the ability of asbestos to induce enzyme release from these cells. Asbestos induces release of glucose from glucose-loaded liposomes, and this effect can be inhibited by the polyanion poly-D-glutamic acid. The results are compatible with the view that positive charges play a decisive role in the interaction between PMNs and asbestos, and that the primary target of asbestos could be the lipid bilayer of the membrane. The interaction results in a permeabilized plasma membrane. When Ca2+ is present in the medium it moves into the cell and causes exocytosis of the granule enzyme lysozyme. Inhibition of cytotoxicity by polyanion may cause a diminished Ca2+-influx and hence inhibition of lysozyme release.

Animals↗

PubMed1989

Scanning electron microscopy comparing exclamation mark hairs in alopecia areata with normal hair fibres, mechanically broken by traction.

A scanning electron microscope was used to compare the distal ends of exclamation mark hairs from alopecia areata patients with the fracture surface of normal hair fibres, mechanically broken by traction. The exclamation mark hairs shows minimal damage to the cuticular cell pattern of the hair shaft. Where the cuticle was absent, cortex and medulla showed low-density features fanning out into a fringe-like structure at the distal ends. The fracture surfaces of normal hair fibres, mechanically broken by traction showed a markedly abnormal cuticular scale pattern, whereas the features of cortical and medullary tissue were normal. These morphological differences between the fracture surface of exclamation mark hairs and normal hair fibres, mechanically broken by traction, may enhance our understanding of the pathogenesis of alopecia areata.

Adult↗

PubMed1987

Image analysis and X-ray microanalysis in cytochemistry.

When cytochemical reaction products are homogeneously distributed within an organelle, point analyses suffice for the quantitative approach. However, quantitative analysis becomes tedious, when the elements in the reaction product are inhomogeneously distributed. Problems arise when elements from two reaction products have to be related to each other, or to endogenous cytological products (ferritin, haemosiderin, calcium, electron dense markers), either topographically or in concentration. When analyzing inhomogeneous/heteromorphical reaction product-containing organelles special attention has to be paid to measure and relate both volume and concentration. In this paper a relative simple structure (eosinophil granules) is chosen to demonstrate that the acquisition of the requested morphometrical plus chemical information and their integration is possible. The following points will be covered to acquire the morphometrical and chemical information: a). How to estimate the total cell cross-sectioned area. b). How to estimate the total cross-sectioned area of all reaction product-containing particles inside that cell. The ratio of these two areas will provide the requested information about the particle volume fraction. By using the X-ray detector in addition: c). How to acquire the chemical information at the requested resolution, within a reasonable total acquisition time d). How to integrate the morphometrical and chemical data per organelle, by matrix analysis in a reduced scan area. e). How to acquire quantitative chemical information, by the use of cross-sectioned standards. f). How to make this acquisition method independent from changes in the instrumental conditions during the acquisition.

Animals↗

PubMed1986

The biological performance of calcium phosphate ceramics in an infected implantation site. III: Biological performance of beta-whitlockite in the noninfected and infected rat middle ear.

The biological performance of macroporous beta-whitlockite implanted in the rat middle ear was evaluated. The material was studied in the non-infected middle ear and in middle ears infected by Staphylococcus aureus. beta-whitlockite was quickly covered by a normal mucosa. One week post-operatively the macropores were filled with exudate, fibrous tissue, and a small quantity of bone. Six months after the operation the greater part of the macropore area was filled with bone (74%); fibrous tissue accounted for 20%, and exudate for 5%. In histological sections, the macropore area of beta-whitlockite had increased by 68% after six months, indicating biodegradation. Macrophages and multinucleated cells were present in the vicinity of the implant and played a role in this biodegradation. Besides cytoplasmic vacuoles containing calcium phosphate, the cells showed smaller granules containing trace elements originally present in the implant material, such as silicon, titanium, aluminum, iron, and magnesium.

Animals↗

PubMed1986

Morphological studies on cellular detachment induced by antibody reactions directed against membrane associated antigens. An ultrastructural study.

The skin explant model was used to determine the effect of antibody reactions against membrane associated antigens on normal human keratinocytes. Addition of specific allo-antibodies against HLA class I antigens induced characteristic changes in the cells on the outermost region of the explant-outgrowth. A disorganization of the filopodia of these cells occurred and the edges of the cellular border were lifted from the substratum. These signs of detachment were also found when pemphigus serum was added. In both experimental conditions the detachment of the cells was complement independent. After removing the antiserum a recovery took place, but the cells once lifted from the substratum remained recognizable as a ridge of cells. No changes were observed when the explants were incubated with antibodies against HLA class II antigens. Incubation with specific antibodies against HLA class I antigens not present on the explant had also no effect. We propose that antibody reactions against various membrane associated antigens can induce within a few hours characteristic changes of the cellular margins.

Animals↗

PubMed1986

Quantitative DNA measurements in an instrument combining scanning electron microscopy and light microscopy.

An instrument for combined scanning electron microscopy (SEM) and light microscopy (LM) to which a photometer unit is attached is described. A special stage in the vacuum chamber of a scanning electron microscope incorporates light microscope optics (objective and condenser) designed for transmission and epi-illumination fluorescence LM. An optical bridge connects these optics to a light microscope, without objective and condenser. The possibility of performing quantitative DNA measurements in this combined microscope (the LM/SEM) was tested using preparations of either chicken erythrocytes, human lymphocytes, or mouse liver cells. The cells were fixed, brought on a cover-glass, quantitatively stained for DNA, dehydrated, and critical point dried (CPD). After mounting the cells were coated with gold. The specimens were brought into the vacuum chamber of the combined microscope and individual cells were studied with SEM and LM. Simultaneously DNA measurements were performed by means of the photometer unit attached to the microscope. It is shown in this study that DNA measurements of cells in the combined microscope give similar results when compared to DNA measurements of embedded cells performed with a conventional fluorescence microscope. Furthermore, it is shown that although the gold layer covering the LM/SEM specimens weakens the fluorescence signal, it does not interfere with the DNA measurements.

Animals↗

PubMed1986

The endocytosis of asbestos by mouse peritoneal macrophages and its long-term effect on iron accumulation and labyrinth formation.

The effect of a single intraperitoneal injection of crocidolite asbestos fibres on the peritoneal cell population were studied. Attention was paid to the changes in the proportions taken by the various types of cell in this population after peritoneal stimulation as well as the handling of asbestos fibres by the peritoneal cells and the formation of asbestos bodies. Intraperitoneal administration of crocidolite led to an influx of inflammatory cells into the peritoneal cavity. The asbestos fibres were phagocytosed and gradually cleared from the peritoneal cavity. Long before this clearance was completed, the peritoneal cell population had returned to the steady state. The stimulated peritoneal macrophages showed increasing concentrations of iron in both lysosomes and the cytoplasm. At later time points, residual bodies containing iron and asbestos fibres were seen frequently in macrophages, but asbestos bodies were not found. As a reaction to the administration of crocidolite asbestos, macrophages from the peritoneal cavity develop tubular systems (labyrinths) that increase in number and size.

Animals↗