Biomedical subjects

D E Lorke

Publications and source records attributed to D E Lorke.

At least 19 recordsLinked to original sources

PubMed2001

Proliferation and apoptosis in the epithelium of the developing human cornea and conjunctiva.

To determine the distribution of proliferating and apoptotic cells in the human cornea during prenatal and early postnatal development, we examined sections of the bulbar conjunctiva, the limbus as well as the central and peripheral cornea between 11 weeks of gestation and 6 months after birth. The objective was to localize dividing cells by proliferating cell nuclear antigen-like immunoreactivity (PCNA-LI) and apoptotic cells by terminal transferase-mediated nick-end labeling (TUNEL). Before the 17th gestational week, PCNA-LI was absent in all 4 regions examined, indicating negligible cell proliferation during early development. After 20 weeks, strong PCNA-labeling was observed in all regions examined suggestive of high proliferative activity not only in the limbus and the bulbar conjunctiva, but also in the central and peripheral cornea. This rise in proliferative activity was followed by a steady decline: after 28 weeks, anti-PCNA staining gradually disappeared in the central and peripheral cornea, so that, at 6 months after birth, it was confined to the limbus and the bulbar conjunctiva, resembling the picture described for the adult cornea. TUNEL-positive cells were virtually absent in all 4 regions examined before the 38th gestational week. Apoptotic cells only started to appear at 38 weeks; at this stage, they were confined to the bulbar conjunctival epithelium. At 6 months after birth, TUNEL-positive cells were observed in the bulbar conjunctival epithelium and the entire cornea; the limbus, however remained devoid of apoptotic cells throughout the entire prenatal and early postnatal period. The present study for the first time localizes proliferating and apoptotic cells in the epithelium of the developing human cornea. Three stages of development can be distinguished: Minimal proliferation (until 17th week), vigorous proliferation over the entire cornea including the limbus and the bulbar conjunctiva (until 28th week) and gradual decrease in proliferative activity (after 28th week) accompanied by the appearance of apoptotic cells.

Aging↗

PubMed2001

Expression of the Na-K-2Cl-cotransporter NKCC1 during mouse development.

Here we describe the expression pattern of the Na-K-2Cl-cotransporter NKKC1 during embryonal and early postnatal mouse development. During early stages hybridization signals were detected over single cells of the developing neuroepithelia, whereas the neuroepithelium of the basal telencephalon was labeled continuously. With ongoing differentiation a distinct pattern of hybridization became apparent, which switched from a neuronal to a more glial pattern in the adult. Outside the nervous system NKCC1 transcripts were present in many organs and were mostly confined to epithelia.

Animals↗

PubMed2001

In vitro and in vivo tracer characteristics of an established multidrug-resistant human colon cancer cell line.

UNLABELLED: 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) has been suggested as a tracer for the scintigraphic detection of multidrug resistance (MDR). The aim of this study was to compare MDR characteristics in vitro and in vivo by immunohistochemic and functional uptake assays in established tumor cell lines cultured and grown in severe combined immunodeficient (SCID) mice. METHODS: The presence of MDR was assessed in vitro in drug-resistant HT-29(mdr1) colon carcinoma cells and in nonresistant HT-29(par) cells by JSB-1 immunohistochemistry, uptake of the fluorescent dye Rhodamine 123, and quantitative measurement of 99mTc-MIBI accumulation. For in vivo imaging, SCID mice bearing subcutaneous xenografts of these cell lines were injected with 99mTc-MIBI and 18F-FDG for scintigraphic and PET examination. After imaging, tumors were analyzed by immunohistochemistry and electron microscopy. RESULTS: All HT-29(mdr1) cells cultured in vitro exhibited distinct JSB-1 immunoreactivity, although to a variable degree, whereas HT-29(par) cells were completely devoid of JSB-1 staining. Rhodamine 123 accumulated poorly in HT-29(mdr1) cells but strongly in HT-29(par) cells. Accumulation of 99mTc-MIBI was 0.05% +/- 0.01% of the activity of the external medium in HT-29(mdr1) cells, but about eight times higher in HT-29(par) cells (0.40% +/- 0.09%), a very low percentage compared with other tumor cell lines. No difference in 201TlCl accumulation was observed between both cell lines. In vivo, neither HT-29(par) nor HT-29(mdr1) tumors grown in SCID mice could be detected by 99mTc-MIBI scintigraphy. In FDG PET, both HT-29(mdr1) and HT-29(par) tumors were clearly visible. FDG uptake was, however, markedly higher in HT-29(par) than in HT-29(mdr1) tumors. Both tumor types were poorly vascularized, as shown histologically. JSB-1 immunoreactivity was absent in all HT-29(par) tumors examined, whereas the majority of HT-29(par) tumor cells were stained. Electron microscopy showed that HT-29(par) tumors contained significantly less mitochondria than hepatocytes of the SCID mouse liver, which displayed high 99mTc-MIBI uptake in our scintigraphy studies. CONCLUSION: Sufficient 99mTc-MIBI uptake is the major prerequisite for distinguishing successfully between drug-resistant and sensitive cells. Negative 99mTc-MIBI scintigrams are not necessarily associated with MDR expression. In some tumors, FDG may be an in vivo marker for MDR as suggested by PET.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Differential expression of the estrogen receptor-related receptor gamma in the mouse brain.

To elucidate estrogen functions, the expression of the estrogen receptor-related receptor ERRgamma, a novel orphan nuclear receptor regulating transcription via estrogen responsive elements, has been localized by in situ hybridization in adult murine brain. ERRgamma transcripts were abundantly present in the isocortex, the olfactory system, cranial nerve nuclei and major parts of the coordination centers, e.g. reticular formation and major parts of the extrapyramidal motor systems. In addition, ERRgamma expression was detected in trigeminal ganglion neurons. ERRgamma distribution was clearly distinguished from that described for ERRalpha, for ERRbeta, and for estrogen receptors (ER) pointing at functional differences between ERRgamma and these receptors.

Animals↗

PubMed1999

Nitric oxide synthase expression and role during cardiomyogenesis.

OBJECTIVE: The aim of the present study was the investigation of the expression of NOS during cardiomyogenesis and its functional role. DESIGN: The qualitative and quantitative expression of NOS isoforms during different stages of cardiac development was evaluated using immunocytochemistry and dot blots, respectively. The functional relevance of NOS expression during cardiomyogenesis was investigated using the in vitro ES cell-differentiation model and selective pharmacological agents. RESULTS: On day 7.5 of embryonic development (E7.5) none of the NOS isoforms were expressed in the embryo, whereas the inducible (iNOS), as well as the endothelial (eNOS) isoforms were detected in the extraembryonic parts. In contrast, starting from E9.5 rat and murine embryos displayed prominent iNOS and eNOS expression. This was correlated with high expression of soluble guanylylcyclase (sGC) as well as high cyclic GMP (cGMP) content. During further development after E14.5 both, iNOS as well as eNOS, started to be downregulated and shortly prior to birth reduced staining for eNOS was found, whereas iNOS was hardly detectable. We further investigated whether NO plays a role for cardiomyogenesis, using in vitro ES cell-derived cardiomyocytes differentiating within embryoid bodies (EBs). The NOS expression pattern in these cells paralleled the one detected in vivo. We demonstrate that continuous incubation of EBs with the NOS inhibitors L-NMMA (2-10 mM) or L-NA (2-10 mM) for 4 to 9 days after plating resulted in a pronounced differentiation arrest of cardiomyocytes, whereas this effect could be reversed by coapplication of the NO-donor spermine-NONOate (10 microM). CONCLUSIONS: Both, iNOS and eNOS isoforms are prominently expressed during early stages of cardiomyogenesis. Around E14.5 NOS expression starts to decline. Moreover, the NO-generation is required for cardiomyogenesis since NOS inhibitors prevent the maturation of terminally differentiated cardiomyocytes using the ES cell system.

Animals↗

PubMed1999

Microvascular and tumor cell alterations during continuous hyperfractionated irradiation: an electron microscopic investigation on the rat R1H rhabdomyosarcoma.

PURPOSE: Conventionally fractionated y-irradiation results in severe damage of tumor capillaries associated with decreasing oxygen partial pressure within the tumor. The present study was undertaken to assess whether vasculo-connective changes are less pronounced after continuous hyperfractionated irradiation, implying better tumor oxygenation and improved radiosensitivity. MATERIALS AND METHODS: Twenty rats with an isotransplanted R1H rhabdomyosarcoma were irradiated for 12 days with 2 daily fractions of 2.5 Gy (delta t = 6 h). After 0, 15, 30, 45, and 60 Gy, tumor tissue of 4 rats each was analyzed histologically and electron-microscopically. RESULTS: Untreated rhabdomyosarcomas were composed of spindle-shaped tumor cells with numerous mitoses. There were many apoptotic nuclei and a large central necrosis. Tumor capillaries showed a continuous lining of flattened endothelial cells with broad overlapping cell contacts overlying a delicate continuous basal lamina. During irradiation, mean tumor volume declined from 1.9 cm3 to 1.2 cm3. The number of atypical mitoses and apoptoses increased and numerous giant tumor cells appeared. The proportion occupied by necrotic tumor tissue rose from 30% to 60%. After 15 Gy (3 days), a marked vasodilatation was apparent accompanied by an interstitial edema. Occasionally, endothelial cells were rounded up and showed indented nuclei, with the underlying basal lamina disintegrated. These changes progressed with increasing radiation doses. After 30 Gy (6 days), leukocytes started to adhere to the endothelial wall. Electron-dense fine fibrillar and basal lamina-like deposits appeared in the perivascular space. Endothelial cell edema was only observed after 60 Gy (12 days). Cell contact areas were shortened, however, the endothelial lining was not interrupted. No signs of radiation fibrosis were observed. CONCLUSION: Continuous hyperfractionated irradiation induces relatively discrete alterations of the vasculo-connective tumor tissue as compared to conventional irradiation. This may be an advantage with respect to tumor blood flow, oxygenation, and thus, radiosensitivity.

Animals↗

PubMed1999

Histology and ultrastructure of liver and kidney following blood exchange with ultrapurified, polymerised bovine hemoglobin in comparison with hydroxyethyl starch.

Because of their oxygen binding capacity, cell-free hemoglobin solutions are promising blood substitutes. However, their clinical use has so far been limited by toxic side effects on liver and kidney until ultrapurification and chemical modifications have been established in the production process of hemoglobin-based oxygen carriers. The present study has been designed to examine structural changes of liver and kidney by light and electron microscopy after complete isovolemic blood exchange with a new ultrapurified bovine hemoglobin solution (UPBH-2) in eight beagle dogs. The results have been compared with a sham-operated control and eight animals having undergone blood exchange with hydroxyethyl starch (HES), a clinically used colloidal volume substitute. In the kidney, no changes were observed after blood exchange with UPBH-2 as compared with the sham control. These findings indicate sufficient tissue oxygenation and lack of renal toxicity. In contrast, histological signs of severe proximal tubular damage, eg, wide lumina, cytoplasmic protrusions, brush-border defects, and tubular necroses, were seen after blood exchange with HES. These changes are consistent with hypoxic tissue damage. In the liver, a slight increase in the number of single cell necroses was observed after UPBH-2 treatment as well as after blood exchange with HES. At the ultrastructural level, partial loss of microvilli and cytoplasmic protrusions of hepatocytes as well as swelling of endothelial cells were present in both groups, but slightly more pronounced in the UPBH-2 group. In all UPBH-2-treated animals, a marked diminution of glycogen-granula in hepatocytes was observed indicating an influence of UPBH-2 upon glycogen metabolism. Whereas the alterations of hepatocytes after nearly complete blood exchange with HES can be interpreted as a consequence of tissue hypoxia, the ultrastructural changes after UPBH-2 treatment cannot be attributed to hypoxic conditions, because improved tissue oxygenation has been demonstrated during treatment with UPBH-2. Hepatocyte damage was very discrete and comparable with the alterations observed after HES treatment. Hence, major hepatotoxicity can be excluded. The absence of significant adverse effects on the ultrastructural integrity of the kidney indicates that UPBH-2, owing to ultrapurification and polymerization, is an oxygen-carrying hemoglobin without acute renal toxicity.

Animals↗

PubMed1999

[Cutaneous asthenia (Ehlers-Danlos syndrome) in a domestic rabbit].

Cutaneous asthenia is a connective tissue disease primarily of dogs and cats, resembling Ehlers-Danlos syndrome in man. This is a description of the disorder in a rabbit. The one-year-old female animal was presented because of two large gaping wounds of the skin. Clinical examination revealed a hyperextensible, thin, and fragile skin. The degree of skin extensibility was evaluated by means of a skin extensibility index (SEI: 19.2%) and compared with those of 4 healthy rabbits (SEI: 8.3%-14.3%). Clinical diagnosis was confirmed by histopathological examination of a skin biopsy revealing reduced packing density of collagen fibers. In addition a decreased number of hair follicles was observed. No conclusion could be drawn regarding the etiology, but existing literature strongly suggests a genetic cause (mostly autosomal dominant inheritance) in humans as well as in animals.

Animals↗

PubMed1997

[Rotator cuff rupture. Vascular supply and collagen fiber processes as pathogenetic factors].

Light and polarization microscopic appraisal of the pathways of fibers and blood vessels in the region of the rotator cuff shows branches of the suprascapular artery. These initially radiate into the insertion tendon parallel to the muscle fibers. They do not continue there, i.e. the vessel branches have blind endings, or they branch and anastomose with each other. Outliers of the transverse branch of the anterior circumflex artery of the humerus come from lateral (from the direction of the deltoid muscle). They pass from the bony insertion of the supraspinatus tendon into the tendon plate, but only run together with the fibers for a short distance. Consequently, a zone low in vessels or free of vessels can be constantly demonstrated under a magnifying glass in the course of the supraspinatus and to a small extent also of the infraspinatus in the fetus or neonate as well as in the adult in the region of the zone of interweaving of the tendinous muscle outlier with the capsule at length magnification. In the genesis of rotator cuff rupture, the presence of hypovascularity must be considered to be a predisposing factor which is present from birth onwards. It affects the clinical course during the process of aging as the point of least resistance in consequence of arteriosclerosis, collagen degeneration physiological wear and tear friction at the lower surface of the acromion and inflammatory swellings of the subacromial bursa.

Aged↗

PubMed1996

[Detection of the tendon of the musculus plantaris longus--diagnostic imaging and anatomic correlate].

Using ultrasound as well as magnetic resonance imaging (MRI) and computed tomography (CT), the plantaris tendon can be identified between the top of the calcaneus and the upper third of the lower leg in cross sections. Due to the surrounding fat tissue, the best proof of plantaris tendon existence and diameter can be obtained on sections at the level of syndesmosis and ankle joint. This allows to avoid unnecessary incisions during plastic and reconstructive surgery using this tendon as an autologeous transplant. For the experienced examiner ultrasound seems to be the easiest way to show plantaris tendon existence; in case of doubt, MRI or CT will give further information.

Ankle Injuries↗

PubMed1996

Alpha4-1 subunit mRNA of the nicotinic acetylcholine receptor in the rat olfactory bulb: cellular expression in adult, pre- and postnatal stages.

In addition to their role in signal transduction, nicotinic acetylcholine receptors have been shown in vi-tro to be involved in neuronal growth cone regulation during development. This idea is supported by recent histochemical findings showing that iso- and archicortical nicotinic alpha4-1 receptor mRNA expression precedes cholinergic fiber ingrowth. To test whether this also holds true for rhinencephalic parts of the telencephalon, we have studied the olfactory bulb by digoxigenin-mediated in situ hybridization, using an alpha4-1 isoform-specific riboprobe and an alkaline-phosphatase-based detection system. Development is characterized by early intense alpha4-1 mRNA expression (embryonic day 14), reaching a peak around postnatal day 2 when all olfactory bulb layers are invested with numerous alpha4-1 transcript-bearing neurons. Subsequently, the density of labeled neurons decreases to reach adult levels (postnatal day 120), where strongly labeled neurons remain in the mitral cell layer, outer external plexiform layer, and glomerular layer. The unifying pattern of iso-, archicortical, and rhinencephalic alpha4-1 mRNA expression is its early onset, i.e. preceding cholinergic innervation. This points to a possible role of nicotinic receptors regarding neuronal migration in all three regions.

Animals↗

PubMed1996

[Acute effects of complete blood exchange with ultra-purified hemoglobin solution or hydroxyethyl starch on liver and kidney in the animal model].

OBJECTIVE: The present animal study investigates the influence of an acute and almost complete isovolaemic haemodilution with a new ultrapurified polymerized bovine haemoglobin (UPBH) on hepatic and renal function and histology in comparison to hydroxyethylstarch (HES). METHODS: Eighteen anaesthetized dogs underwent progressive isovolaemic haemodilution with either HES (group 1) or UPBH (group 2) to haematocrit target levels of 15, 10 and < 5%. Haemodynamics, arterial and mixed-venous blood gases and blood chemistry were determined at each measurepoint. With a haematocrit value < 5%, biopsies were taken from the liver and kidneys and prepared for light and electron microscopic analysis. One dog without haemodilution figured as control animal. Statistical analysis was performed using ANOVA, with p < 0.05 considered significant. RESULTS: In group 1, the cardiac output was increased in parallel to a decreasing vascular resistance, while in group 2 haemodynamic parameters remained unchanged. In group 1, avDO2 and final DO2 and VO2 were decreased. In contrast, avDO2 and oxygen extraction ratio were increased, while VO2 remained stable under decreasing DO2 in group 2. In both groups, coagulation values and blood chemistry showed dilution dependent changes. Colloid osmotic pressure and plasma viscosity were increased in both groups but COP was higher in group 1 compared to group 2. A lower urine output in comparison to group 1 and a maximal concentration of 0.27 g/dl of free haemoglobin in urine were seen in group 2. Liver biopsies showed no severe histological changes in both groups. Renal histology revealed severe alterations of proximal tubules after haemodilution with HES. In contrast, no histological indications for acute toxic or ischaemic lesions in the kidneys were seen after UPBH treatment. CONCLUSION: The high degree of purification and polymerization of bovine haemoglobin associated with adequate tissue oxygenation by increased oxygen extraction resulted in normal histological and functional findings after acute and almost complete blood exchange with UPBH. In contrast, HES-treated animals showed severe histological changes of renal tubuli caused by isovolaemic anaemia.

Animals↗

PubMed1995

Cellular expression of alpha 4 subunit mRNA of the nicotinic acetylcholine receptor in the developing rat telencephalon.

By contrast to adult brain, little is known on the development of nicotinic acetylcholine receptor (nAChR) expression. Using a digoxigenin-labeled riboprobe for in situ hybridization, alpha 4 nAChR subunit mRNA expression was studied in embryonic and postnatal rat neocortex and hippocampus where it was transiently increased in neuronal subpopulations and preceded cholinergic fiber ingrowth. alpha 4 expression was increased in neocortical layer VIb between E20 and P2 and, about birth, in dentate gyrus granule cells subsequently decreasing to adult levels. nAChR mRNA expression is increased at the developing neuromuscular endplate preceding cholinergic innervation which triggers changes in non-alpha nAChR isoform expression. It has to be elucidated whether similar changes may occur in the telencephalon.

Animals↗

PubMed1994

Altered postnatal development of the visual cortex in trisomy 19 mice.

The development of the visual cortex was studied in 30 Trisomy 19 (Ts19) mice aged 1-16 days postpartum and their euploid littermates. Morphogenesis of the Ts19 visual cortex, though delayed in development, followed the regular sequence observed in control littermates. Early morphogenetic events, such as obliteration of the ventricular lumen, disappearance of the ventricular zone, formation of a visible apical dendrite, as well as disappearance of both migrating neurons and the columnar organization of bipolar preneurons were delayed by 1 day; maturation steps occurring later such as appearance and disappearance of perikaryal basophilia were delayed by 2 days. Myelination of the white matter was similarly retarded by 2 days. The fronto-occipital length of the cerebral hemispheres and the thickness of the visual cortex were decreased by about 20%, consistent with a hypoplasia of the Ts19 neocortex. Unlike in the cerebral cortex of human Ts21, morphometric analysis of the visual cortex of Ts19 mice did not give any indication of a selective deficit in a particular neuron population; the increased cell density and the reduced nuclear volume observed during early postnatal development are attributable to a maturational delay. The relevance of these results with respect to the mechanisms underlying neuropathological alterations in human Ts21 is discussed.

Animals↗

PubMed1994

Developmental characteristics of trisomy 19 mice.

Trisomy 19 (Ts19), the only murine trisomy compatible with survival beyond birth, allows systematic studies on the effect of an additional chromosome upon postnatal development. In this review, developmental consequences of murine Ts19 are presented. In Ts19 mice, viability is limited to a few weeks postpartum. Body weight is markedly reduced. The occurrence of malformations of the cardiovascular, skeletal and central nervous systems depends on the parental genetic background. In all organ systems examined, development is delayed by 1-2 days. Ts19 hematopoietic cells exhibit the same survival rate in lethally irradiated hosts as controls. In the CNS, morphological and morphometric studies fail to detect cytoarchitectonic abnormalities: the orderly pattern of development is not disturbed in the visual cortex, cerebellum, locus coeruleus (LC), optic nerve and retina; but neurogenesis, gliogenesis, myelination and invasion of blood vessels are each delayed by 1-2 days. In addition, size and cell number of different brain regions are reduced to a variable degree: the telencephalon and the cerebellar vermis are markedly hypoplastic, whereas the LC, the optic nerve and the retina are hardly reduced in size. Choline acetyltransferase activity is selectively reduced in the Ts19 telencephalon, whereas the activity of the marker enzyme of the GABAergic system is decreased in all brain regions examined. In behavioral tests, visual capacities and orientation ability of Ts19 mice develop with a 2-day delay, while motor coordination is more severely retarded; there is no response to auditory stimulation. Fetal Ts19 ovaries show excessive oocyte degeneration. Development of the testes is only disturbed postnatally: differentiation of gonocytes to A spermatogonia and formation of B spermatogonia are severely disrupted, resulting in a striking reduction in germ cell number and a predominance of Sertoli cells. Histopathological changes exhibit marked intra- and interindividual variations. In addition, growth and lumen formation are impaired in the seminiferous tubules. The proliferative capacity of cultured Ts19 cells is not altered. The activities of glutamate oxaloacetate transaminase-1 and phosphoglycerate mutase-1 are increased by 50%, compatible with a gene dosage effect of these two enzymes. Ganglioside composition is altered in the Ts19 liver, but not in the brain, spleen and heart. Two-dimensional protein patterns show both chromosome-specific and chromosome-nonspecific changes, their frequency being far lower than expected from the number of proteins coded on chromosome 19. Possible pathogenetic mechanisms are discussed.

Abnormalities, Multiple↗

PubMed1993

[Changes in the femoral nerve and medial articular nerve after medial arthrotomy and replacement of the anterior cruciate ligament].

The effect of combined medial arthrotomy (Payr's approach) and replacement of the anterior cruciate ligament upon the femoral nerve and the medial articular nerve has been studied. Resection and prosthetic replacement of the anterior cruciate ligament was performed on the right hindlimb of twelve Merino sheep. Three unoperated animals served as controls. Eight to 48 weeks after the operation, myelinated axons of the femoral nerve and the medial articular nerve were examined using morphological and morphometric methods. Compared with the un-operated control side, only discrete morphological alterations were detectable, such as an increase in non-circular axons. In contrast, considerable morphometric changes were observed: A decrease in large axons and an increase in small axons were found in the femoral nerve of the operated side resulting in a significant reduction in axon diameter (p < or = 0.05). This decrease in axon diameter was associated with a significant increase in the number of axons. Both changes persisted throughout the period examined (48 weeks). Similar changes, i.e. increase in small axons, decrease in large axons and reduction in mean axon diameter were also observed in the medial articular nerve. The results show that medial arthrotomy with prosthetic replacement of the anterior cruciate ligament results in irreversible changes of the femoral nerve and the medial articular nerve. These findings indicate that the medial articular nerve is injured during medial arthrotomy. Mechanisms are discussed which may explain the alterations observed in the femoral nerve a long distance (30 to 35 cm) away from the operation site.

Animals↗

PubMed1993

[Isolated fracture of Volkmann's triangle--a unique injury].

25 rare isolated fractures of the dorsal tibial margin out of 2500 ankle-lesions have been analysed. The mechanism consists of extensive plantar flexion followed by axial impact of the astragalus against the posterolateral part of the mortise. The tense condition of the syndesmotic apparatus forces it to pull off the dorsal insertion wedge on the distal tibia with an articular component of different size. Small and undislocated fragments are prevalent. Torn anterior tibiofibular ligament and parts of the interosseous membrane are typical concomitants of this lesion. Neither fibular nor medial structures of the ankle joint have been harmed. Orthotopic bony union of the tibial margin and ligament healing is safe within three weeks of non-weight-bearing immobilisation followed by the same period of walking cast. Large dislocated fragments require operation. Most patients have excellent or good results as our follow-up study confirms.

Adolescent↗

PubMed1993

[Effect of synthetic hydroxyapatite ceramics on long-term cultures of isolated chondrocytes].

This study deals with the influence of hydroxyapatite-ceramic on long-term cultures of rabbit articular chondrocytes. By additioni of granules of this material into the culture wells improval of cell proliferation by factor 12 over a period of twelve weeks is found. More important is the maintaining of the status of differentiation of the chondrocytes, documented by immunoidentification of the expressed collagen I production over collagen II as marker for chondrocytes. In controls without addition of hydroxyapatite-ceramic there is a dynamic increase of collagen I production over the culture period and morphological alteration of the cell shape leading to fibroblast-like cells. As this dedifferentiation is the main problem concerning chondrocytes long-term cultures, the addition of HAC into the culture medium is a simple and effective method enhancing the productivity of the culture system. Moreover this experimental design with chondrocytes as cells familiar with mineralized matrix gives an important proof of the excellent cytocompatibility of the hydroxyapatite-ceramic used in this study.

Animals↗