Biomedical subjects

P Buma

Publications and source records attributed to P Buma.

At least 91 records · Page 5Linked to original sources

PubMed1995

Tissue reactions around a hydroxyapatite-coated hip prosthesis. Case report of a retrieved specimen.

Bone reactions were studied around a titanium, hydroxyapatite (HA)-coated Osteonics (Allendale, NJ) bipolar hip prosthesis, which was revised for severe midthigh pain 4 years after implantation. Inspection of the retrieved prosthesis using a dissecting microscope revealed scarce remnants of a coating-like material on the surface of the prosthesis; however, histology of this layer and histology of the bony side of the bone--HA interface failed to reveal any remnants of an HA coating. The interface was covered predominantly by trabecular bone, which closely followed the contour of the prosthesis, and was partly woven nonmineralized bone. At locations where mineralized bone faced the prosthesis, many small dark titanium wear particles were found. Similar particles were found in macrophages in the intertrabecular medullary space. Polyethylene wear particles were specifically located in macrophages in a soft tissue interface at more distal levels along the stem of the prosthesis. Although the observations presented in this case cannot be generalized, it clearly shows that the HA coating layer had completely disappeared after 4 years. More detailed retrieval studies and longer clinical follow-up studies are needed before a final evaluation of the behavior of HA coatings and long-term fixation of HA-coated prostheses can be made.

Adult↗

PubMed1995

Culture of chondrocytes in alginate and collagen carrier gels.

In this in vitro study, we compared the potential of collagen and alginate gels as carriers for chondrocyte transplantation and we studied the influence of demineralized bone matrix (DBM) on chondrocytes in the gels. Chondrocytes were assessed for cell viability, phenotype (histology), proliferation rate and sulfate incorporation. Collagen gels showed a significant increase in cell numbers, but the chondrocytes dedifferentiated into fibroblast-like cells from day 6 onwards. In alginate gels, initial cell loss was found, but the cells maintained their typical chondrocyte phenotype. Although the total quantity of proteoglycans initially synthesized per cell in collagen gel was significantly higher, expressed per cell, the quantity in alginate gel eventually surpassed collagen. No effects of culturing chondrocytes in combination with DBM could be demonstrated on cell proliferation and sulfate incorporation. The collagen and alginate gels have different advantages as carriers for chondrocyte transplantation. The high proliferation rate of chondrocytes in collagen gel may be an advantage, but the preservation of the chondrocyte phenotype and the gradually increasing proteoglycan synthesis in alginate gel is a promising method for creating a hyaline cartilage implant in vitro.

Alginates↗

PubMed1994

Optimization of cryopreservative procedures for human articular cartilage chondrocytes.

Procedures are being developed which use isolated articular cartilage (AC) chondrocytes to restore damaged articular surfaces. The availability of isolated human chondrocytes for transplantation may be increased by low-temperature storage (banking). At present, no single method of freezing chondrocytes has been proven to be optimal. In this project, two different freezing protocols, I and II, were compared. Protocol I used freezing rates of -1 degrees C/min down to a temperature of -40 degrees C. Protocol II used a freezing rate of -1 degree C/min down to -10 degrees C and faster rates thereafter. Cells were stored for 2 weeks at -196 degrees C. Survival and function of the cells after thawing were evaluated by histological examination and determination of 35S- and 3H-thymidine incorporation after 1 and 2 weeks of high-density monolayer culture. Cells frozen with protocol I showed better function and survival (99.75%) than cells frozen with protocol II (85%). Both groups showed slowing of metabolism and replication after freezing when compared with controls. We conclude that controlled freezing of adult human chondrocytes at rates of -1 degrees C/min improves survival. Banking of human AC chondrocytes may be feasible using protocol I, although some questions regarding the long-term behaviour of human AC chondrocytes after cryopreservation remain to be answered.

Aged↗

PubMed1994

A procedure for the visualization of bone with hydroxyl-apatite coated implants.

A procedure for the histological visualization of the interface between implants coated with hydroxyl-apatite (HA) and bone, and the reaction of bones to the implants, has been developed. Thick sections of bones with HA-coated stainless-steel implants, were investigated with the implant still in situ with routine and (confocal) fluorescence microscopy. The prosthesis-HA-bone interface, bone cells, necrotic and vascularised bone, bone-ingrowth and bone remodelling could be visualised. After removal of the implant from the sections alternative sections were further processed for routine light microscopy, microradiography and detailed fluorescence studies. It appeared that the HA coating was still intact and the integrity of the HA-bone bond was very well preserved. The HA coating layer had the same appearance as after the first inspection with surface microscopy. However, more details were visible. Prosthesis-related and time-related changes in the appearance of the HA layer were detected. The advantage of the procedure is that observations can be made of bone reactions with the prosthesis still in situ, without previous embedding in plastics, and laborous sectioning and/or grinding procedures. Thereafter, sections can be processed for different histological techniques, e.g. immunocytochemistry, routine histology, microradiography, fluorescence microscopy, apparently without imparing the HA coating layer.

Animals↗

PubMed1994

The in-vivo effects of an intramedullary implant evoking a constant radial stress to bone. An animal study in the tibia of the goat.

Initial stability is essential for successful bone ingrowth into non-cemented prostheses. An entire new concept to increase the initial stability directly after implantation of intramedullary stems was developed (the tension rod prosthesis). The concept is based on a tension rod made out of memory metal that pulls a proximal stem of a prosthesis towards a distal anchor with a constant force. The stress generated along the long axis of the bone produces a radial stress around the prosthesis in the proximal femur. The main goal of this design is to increase the primary stability of the prosthesis during the ingrowth phase and to prevent stress shielding and bone resorption, as realized by the radial force applied to the proximal endosteum of the bone. To assess the efficacy of this concept and to collect data for the anchor design, an implant was developed for implantation into the tibia of the goat. Analyses of push-out strength and bone reactions were performed postoperatively. After 48 weeks the push-out strength of this implant was increased and the histological evaluation showed almost complete osseousintegration. Histomorphometrical analysis showed pronounced, permanent periosteal reactions, located around the anchor of the implant, which generates the radial stress. These first results showed that the bone can withstand the radial stress provoked by the anchor of the tension rod. It is concluded that the concept of a tension rod prosthesis is viable.

Animals↗

PubMed1994

Innervation of the patella. An immunohistochemical study in mice.

In the mouse, arthritis was induced by a single sub-patellar intraarticular injection of bacterial collagenase. This procedure induces also patellar malalignment. A rich innervation of thin varicose calcitonin gene-related peptide (CGRP) and substance P (SP) immunoreactive fibers was found in the joint capsule, in the periosteum of the patella, in the synovial tissues at the lateral border of the patella, in the femoral groove, and in the subchondral bone of the patella and femur. Moreover, fibers were found in plica tissues between the quadriceps and patellar tendon, and the femoral groove. After the collagenase treatment, the general innervation pattern was comparable to that of the controls, but CGRP and SP innervation was no longer detectable with the antibodies in the plica tissues, and was to a lesser extent detectable in the fat pad of the patella, in the lateral borders of the patella and in the proliferated synovial tissues. Signs of degenerated axonal profiles were observed in these locations with a polyclonal antibody to the growth-associated protein GAP-43/B-50. At all the other peripheral locations, such as the muscles, the GAP-43/B-50 distribution was normal.

Animals↗

PubMed1994

Morsellized allografts for fixation of the hip prosthesis femoral component. A mechanical and histological study in the goat.

To simulate femoral intramedullary bone stock loss in revision surgery of failed total hip arthroplasties, a method was developed using impacted trabecular bone grafts. In 14 goats a cemented total hip arthroplasty was performed, fixating the stem within a circumferential construction of bone allografts. After 6 or 12 weeks, 4 goats were used for mechanical tests and 3 for histology. The stability of the stems was determined in a loading experiment with roentgen-stereophotogrammetric analysis; loads of up to 1.44 times body weight were used. One aseptic loosening was seen with gross movements. In the other cases the most important movements were axial rotations (max. 0.24 degrees under 800 N) and axial translations (max. 0.16 mm under 800 N). After unloading some elastic recovery occurred. There were no differences between the 6 and 12-week groups. Histologically, revascularization and remodeling of the grafts were evident. Bone apposition and bone resorption of the grafts resulted in a mixture of graft and new bone. There was more new bone formation in the 12-week group, but the process was not yet completed. The use of impacted trabecular bone grafts in cases of severe intramedullary bone stock loss seems to be a promising revision technique.

Animals↗

PubMed1993

Chondrocyte behavior in fibrin glue in vitro.

To test fibrin glue as a vehicle in chondrocyte transplantation, chondrocytes, isolated from articular cartilage of young rabbits, were mixed with Tissucol, a highly concentrated fibrin glue, and cultured for 7 days. Histology, autoradiography (35-S) and electron microscopy were used to study chondrocyte behavior and phenotypic expression. Chondrocytes multiplied, retained their morphology, and produced matrix in fibrin glue as long as the cells were surrounded by the glue. Glue disintegration started after 3 days and was accelerated by higher cell concentrations.

Animals↗

PubMed1993

Cemented fixation with bone grafts.

Loosening of the acetabular cup in cemented total hip arthroplasty is always accompanied by a loss of bone stock. Acetabular lesions can be reconstructed in several ways. Preoperative planning must be through, and specifically if graft procedures are considered, infection must be ruled out. The treatment of choice is a standardized cemented acetabular revision procedure with tight impaction of morsellized cancellous grafts. The clinical success of the technique is supported by the results of an animal experiment.

Acetabulum↗

PubMed1992

Ultrastructure of the periaqueductal grey matter of the rat: an electron microscopical and horseradish peroxidase study.

The neurons of the mesencephalic periaqueductal grey substance (PAG) in the rat are small and medium sized. The cells are frequently located in small clusters, without interdigitating glial elements and may be connected by direct membrane appositions or by gap junctions. The inner zone of the PAG is cell poor. In many cases, the cytoplasm of the cells is filled with extensive rough endoplasmic reticulum, free ribosomes, Golgi apparatus, and large lysosome-like granules. The nuclei show large indentations. The cells have a high nucleus-cytoplasm ratio. The neuropil is very extensive and particularly rich in large numbers of small unmyelinated axons, dendrites, axonal varicosities, and synaptic connections. Myelinated fibres are relatively scarce. The orientation of the fibres was studied in transverse and horizontal sections, in combination with HRP track tracing experiments. It appeared that throughout the PAG most of the fibres were orientated longitudinally. Quantitation showed that most fibres were present in the inner zones of the PAG. Moreover, the diameter of the fibres adjacent to the aqueduct was smaller than that of the fibres in the peripheral parts of the PAG. The thin unmyelinated fibres made extensive synaptic connections within the PAG. Many synaptic varicosities were found in the neuropil of the PAG. There were four types of synaptic varicosities, characterized by different populations of clear and dense-core secretory granules and by the different morphology of the synaptic specializations. In general, the different types of varicosity were homogeneously distributed in the different parts of the PAG. Electron dense secretory granules, when present, were located at some distance from the synaptic junction. Serial sections revealed varicosities which contained only dense-core secretory granules, without synaptic specializations. The dendrites of PAG neurons generally lacked synaptic spines. Many dendrites, particularly those of neurons located in the peripheral parts of the PAG, were directed toward the aqueduct. The present study shows that the PAG is a very complex brain area. The crisscrossing of axons and dendrites with synaptic connections at considerable distances from the cell bodies render it very difficult to unravel the relationships between the possible sources and destinations of ongoing information. This structure complicates the search for relationships between the functional organization and the cytoarchitectural borders in the PAG area.

Animals↗

PubMed1992

Calcitonin gene-related peptide, substance P and GAP-43/B-50 immunoreactivity in the normal and arthrotic knee joint of the mouse.

The aim of this study was to describe the normal distribution of calcitonin gene-related peptide (CGRP) and substance P (SP) containing fibres in the knee joint of the mouse and to obtain insight into the changes in innervation associated with degenerative processes in the joint. Arthrosis was induced by a single subpatellar intra-articular injection of bacterial collagenase. After decalcification in EDTA solutions, the CGRP and SP fibres were visualized by peroxidase-antiperoxidase pre-embedding immunocytochemistry for light microscopy. Control experiments on the mouse brain as a reference for the effect of EDTA on the immunostaining showed that the decalcification procedure with EDTA had not impaired the immunostaining. A rich innervation of thin varicose CGRP and SP immunoreactive fibres was found in most peri- and intra-articular tissue components. The periosteum, synovial tissues, the joint capsule and the intra-articular fat tissues were richly innervated. Less intense innervations were also found in the subchondral bone plates of the tibio-femoral joint and of the patella. Fibres were also found in the soft tissues between the patellar tendon and the femoral groove. No differences could be found between the location of CGRP and SP fibres with respect to the localization in the joint, but generally more CGRP fibres were found. The collagenase-induced osteoarthrosis was characterized by sclerosis of the subchondral bone, patellar dislocation, osteophyte formation, synovial proliferation and by severe cartilage abrasion, particularly on the medial side of the femoro-tibial joint. The overall distribution of CGRP and SP fibres was the same as in the control joints. However, major differences were found in all studied joints at specific locations around the cruciate ligaments, in the synovium around the patella, in the soft tissues lateral of the patella and in plica tissue between the patella and femoral groove. The CGRP and SP innervation was no longer detectable by immunolabelling with the antibodies. With a polyclonal antibody to the growth associated protein GAP-43/B-50, signs of degenerated axonal profiles were observed in these locations. At other peripheral locations, such as the muscles, the GAP-43/B-50 distribution was normal. In conclusion, the present study provides detailed information on the localization of CGRP and SP fibres, which may be involved in pain perception. Knowledge of the changes that occur during arthrosis may give more insight into the clinical symptoms.

Animals↗

PubMed1991

Ultrastructural localization of adrenocorticotrophic hormone and the phosphoprotein B-50/growth-associated protein 43 in freeze-substituted, Lowicryl HM20-embedded mesencephalic central gray substance of the rat.

Previous studies have shown that the endogenous phosphorylation of the neuron-specific protein B-50 in isolated synaptic plasma membranes is inhibited by adrenocorticotrophic hormone(1-24). The aim of this study is to examine if there is a specific neuroanatomical interaction of adrenocorticotrophic hormone and B-50 in the mesencephalic central gray substance of the rat. With light microscopy, high B-50 immunoreactivity was detected throughout the mesencephalic central gray substance, overlapping with those areas where adrenocorticotrophic hormone-immunoreactive fibres were present. To study the ultrastructural localization of B-50 and adrenocorticotrophic hormone, we employed a method of immunogold labelling on ultrathin sections of freeze-substituted and Lowicryl HM20-embedded fixed brain tissue. This offered optimal morphological preservation together with high retention of antigenicity. At the electron microscopic level, adrenocorticotrophic hormone immunoreactivity was detected in dense-core secretory granules present in non-junctional regions of axoinal varicosities. This suggests a non-synaptic release of adrenocorticotrophic hormone from the axons. Using double immunolabelling techniques we showed that in adrenocorticotrophic hormone-innervated areas of the mesencephalic central gray substance B-50 immunoreactivity was present at plasma membranes of all unmyelinated axons and axonal varicosities and virtually absent in dendrites. The result on B-50 localization agrees well with previous studies in the hippocampus [Van Lookeren Campagne et al. 1990 J. Neurocytol. 19, 948-961] and in the pyramidal tract [Gorgels et al. 1989 J. Neurosci. 9, 3861-3869] of the rat and suggests that in the mature rat central nervous system, B-50 expression in axons is a general phenomenon. For the adrenocorticotrophic hormone-innervated areas, we discuss the proposal that non-synaptically released adrenocorticotrophic hormone modulates B-50 phosphorylation in axons and axon terminals.

Acrylic Resins↗

PubMed1989

Characterization of luteinizing hormone-releasing hormone fibres in the mesencephalic central grey substance of the rat.

With the peroxidase-antiperoxidase (PAP) preembedding immunocytochemical method the luteinizing hormone-releasing hormone (LHRH) containing fibres in the mesencephalic central grey substance (MCG) of male and female rats were studied light and electron microscopically. Thin unmyelinated LHRH immunoreactive fibres were found in the MCG up to the ponto-mesencephalic junction in a ventral sub- and intraependymal position. Especially in the middle part of the MCG, LHRH reactive fibres were found in two or three rostrocaudally orientated ventromedial thickenings of the ependymal lining. Ultrastructurally, LHRH varicosities contained immunopositive secretory granules with a diameter of approximately 110 nm. Because the LHRH varicosities were not observed to make any synaptic contact with dendrites of MCG cells, it seems very likely that LHRH influences MCG neurons in a nonsynaptic way. No apparent differences were found between male and female rats.

Animals↗

PubMed1988

Ultrastructural characterization of exocytotic release sites in different layers of the median eminence of the rat.

The release of neuronal secretory products by exocytosis in different layers of the median eminence of the rat was investigated ultrastructurally after perfusion with Ringer solution containing tannic acid. Exocytotic images were observed in all layers studied. Neurohaemal release sites were found in the pars externa of the palisade layer, where they occurred not only against the basal lamina of the pericapillary space, but also opposite, adjacent to neuronal and glial elements. In the lateral portion of the pars externa of the palisade layer most release sites were separated from the pericapillary space or the pial surface by ependymal or glial processes. In the pars interna of the palisade layer, and in the reticular, fibre and subependymal layers, release was observed in different types of axonal processes without morphological synaptic specializations. We suggest that products released in the pars externa of the palisade layer are destined to reach the capillaries of the primary portal plexus. Although the non-vascular release sites may serve a similar hormonal function, they may alternatively represent the morphological correlate of axo-axonal contacts or of paracrine, non-synaptic release sites.

Animals↗

PubMed1987

Ultrastructural demonstration of oxytocin and vasopressin release sites in the neural lobe and median eminence of the rat by tannic acid and immunogold methods.

We have investigated the localization of oxytocin (OXT) and vasopressin (AVP) release sites in the neural lobe and median eminence (ME) of the rat. Ultrastructural and post-embedding immunocytochemical studies with protein A-gold as a marker were used for the identification of OXT and AVP neurosecretory granules (NSG). Release of the contents of these OXT and AVP NSG by exocytosis has been clearly demonstrated with the tannic acid-Ringer incubation method in axon terminals of the neural lobe and in varicose fibres with OXT and AVP NSG in the internal zone of the ME. As these fibers lack synaptic specializations, and are not located in the direct vicinity of capillaries of the primary portal plexus, these observations suggest that OXT and AVP are released in a paracrine way in the ME of the rat.

Animals↗

PubMed1987

Ultrastructural localization of exocytotic release sites in immunocytochemically characterized cell types. A combination of two methods.

Preembedding visualization of exocytosis by tannic acid treatment and postembedding immunocytochemical identification of cell types were combined to demonstrate the release of secretory products by exocytosis of characterized cell types. Treatment with tannic acid was carried out by perfusion with Ringer containing tannic acid, followed by fixation, dehydration and embedding. For electron microscopical immunocytochemistry protein A-gold was used as marker. In this study, exocytotic release was demonstrated for prolactin by cells in the pars distalis, and for oxytocin by axon terminals in the pars nervosa of the pituitary gland of the rat.

Animals↗

PubMed1986

Role of cAMP in electrical and secretory activity of the neuroendocrine caudo-dorsal cells of Lymnaea stagnalis.

The peptidergic neuroendocrine caudo-dorsal cells (CDC) in the cerebral ganglia of the freshwater snail Lymnaea stagnalis L. produce an ovulation-stimulating neurohormone (CDCH). Release occurs by exocytosis in a calcium-dependent way from axon terminals in the periphery of the intercerebral commissure, particularly during a period of electrical activity (the 'discharge'). An important factor in electrical and, hence, secretory activity of the CDC appears to be cyclic adenosine 3', 5'-monophosphate (cAMP). Incubation of cerebral ganglia in snail Ringer with the cAMP-analogue 8-(4-chlorophenylthio)-cAMP (cpt-cAMP) or with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) leads to activation of the CDC: electrophysiological, quantitative electron microscopic and bioassay studies show that incubation results in the onset of intense electrical activity, a marked reduction in the number of secretory granules in the axon terminals, an enormous increase in the number of exocytosis phenomena and a strong stimulation of CDCH-release. It is assumed that treatment with IBMX or with cpt-cAMP mimics a rise in the cytoplasmic level of cAMP when the CDC become activated by a physiological stimulus. This rise most likely effectuates a permeability change of the axolemma for ions involved in the discharge. As a consequence of the depolarization of the axolemma during the discharge, calcium ions would enter the axon terminal and induce exocytotic release of CDCH.

1-Methyl-3-isobutylxanthine↗

PubMed1986

Ultrastructural demonstration of secretion by exocytosis in rat pinealocytes with the use of the tannic acid method.

In the rat pineal gland the mechanism of release of secretory material was studied ultrastructurally after incubating tissues in Ringer solution containing tannic acid. The results indicate that pinealocytes release the contents of secretory vesicles into the extracellular space via exocytosis, a phenomenon that has not been visualized previously in this cell type. This finding may reflect release of polypeptides by the pineal gland.

Animals↗