SEARCH · Search PubMed

Results for “In vitro model”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed1996

In vitro model to evaluate the relative efficacy of catheter-directed thrombolytic strategies.

RATIONALE AND OBJECTIVES: Catheter-directed thrombolytic therapy has become an accepted treatment for many vascular occlusions. However, the relative rates of lysis of the different methods of drug administration have not been quantified. We developed an in vitro model to simulate and quantify local lytic therapy of a thrombotic vascular occlusion and tested it by evaluating three catheter-directed lytic strategies. METHODS: Seven-centimeter-long segments of 125I-fibrinogen-labeled thrombus made from recently expired human blood from a blood bank were formed in plastic tubes and were placed in a flowing stream of saline. Using multisidehole catheters, the clots were "treated" with intrathrombic saline or urokinase administered by drip infusion or forced injection using identical total doses of drug and volumes of fluid. Using endhole catheters, saline or urokinase was drip infused into the leading edge of the thrombus using the same protocol. A collimated scintillation detector was used to quantify the amount of activity remaining in the thrombus during each experiment, and the resultant time-activity curves for the different trials were compared. RESULTS: Forced-injection administration of urokinase using a multisidehole catheter produced the fastest lysis, resulting in a half-life of 42 min. The other infusion methods were slower, with half-lives of 153 min for multisidehole urokinase drip infusion, 365 min for endhole urokinase drip infusion, and more than 1,000 min for multisidehole catheter forced injection of saline and multisidehole and endhole saline drip infusion. The differences among these groups were reproducible and statistically significant. CONCLUSION: Results suggest that a simple and inexpensive in vitro model simulating lysis of a vascular occlusion can produce reproducible quantitative data. The data demonstrate that forced injection of lytic agents with a multisidehole catheter enhances the rate of thrombolysis and that the enhancement is not primarily attributable to the mechanical effect of this mode of administration.

Catheterization, Peripheral↗

PubMed2001

Is cadmium chloride-induced inter-sertoli tight junction permeability barrier disruption a suitable in vitro model to study the events of junction disassembly during spermatogenesis in the rat testis?

The events of germ cell movement during spermatogenesis are composed of intermittent phases of junction disassembly and reassembly. Although primary Sertoli cells cultured in vitro can be used to study junction reassembly, an in vitro model to study the events of junction disassembly is still lacking. We have assessed whether the CdCl(2)-induced inter-Sertoli tight junction (TJ) permeability barrier disruption in vitro can fill this gap. When Sertoli cells (1.2 x 10(6) cells/cm(2)) were cultured on Matrigel-coated bicameral units to allow the assembly of inter-Sertoli TJs, it was manifested by a steady rise in transepithelial electrical resistance across the Sertoli cell epithelia. Exposure of these cells on day 1 (i.e. 24 h after their isolation) to CdCl(2) at 5-10 microM for 8 h could perturb the inter-Sertoli TJ assembly dose dependently without any apparent cytotoxicity. Likewise, when cells were exposed to CdCl(2) (0.1-5 microM) on day 4 for 8 h after inter-Sertoli TJs were already assembled, CdCl(2) also perturbed the maintenance of inter-Sertoli TJ permeability barrier dose dependently without signs of cell cytotoxicity. Although the perturbed inter-Sertoli TJs were not capable of resealing even after the removal of CdCl(2), the presence of testosterone (T) at 1 x 10(-9) M allowed resealing of the inter-Sertoli TJ barrier after CdCl(2) was removed, whereas the presence of 2 x 10(-7) M testosterone even protected Sertoli cells from CdCl(2)-induced damage. More important, the reassembly of inter-Sertoli TJs after CdCl(2)-induced TJ disruption was accompanied by changes in cellular gene expression of occludin and urokinase plasminogen activator, which mimicked their patterns during inter- Sertoli TJ assembly in vitro without CdCl(2) treatment. Based on these results, it is apparent that CdCl(2)-induced inter-Sertoli TJ disassembly is a potential in vitro model to study the events of junction disassembly.

Animals↗

PubMed1998

Videoimaging of prostatic stromal-cell contraction: an in vitro model for studying drug effects.

BACKGROUND: Stromal-cell contractility is known to play an important role in the development of bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH). An in vitro model of single-cell contraction was developed to investigate the effect of alpha1-adrenoceptor agonists and antagonists. METHODS: Human prostatic stromal cells were isolated from prostatectomy and cystoprostatectomy specimens. The cells were cultured in a selective medium supplemented with growth factors and steroid hormones. The culture flasks were coated with a viscous agent to allow cell contraction. Contractions were visualized by means of a cell-culture microscope fitted with a time-lapse video system. For quantitative analysis, the percentage of contracting cells was evaluated. RESULTS: Nineteen percent of the cells were found to contract without stimulation. Following incubation with doxazosin (10 nM, 100 nM, and 1 mM), there was a slight dose-dependent decrease in the number of spontaneously contracting cells, whereas adrenergic stimulation using 10 microM of phenylephrine led to a significant increase in the percentage of contracting cells (55%). Following incubation with 100 nM of doxazosin, the phenylephrine-induced effect was significantly reduced. CONCLUSIONS: This simple in vitro model of cell contraction in the prostate provides a useful means of investigating drug effects on prostatic stromal cells.

Adrenergic alpha-Agonists↗

PubMed1994

A new in vitro model of murine mesoderm migration: the role of fibronectin and laminin.

Examination of the factors involved in primary mesodermal migration in the mouse has been complicated by the lack of a suitable in vitro model. We have developed a new culture system using primitive streak stage embryos denuded of primitive endoderm, which allows easy observation and manipulation of the outgrowing cells. The cells migrating away from these explants were shown by immunocytochemistry to express vimentin and an epitope of the I antigen recognised by the antibody C6, both of which are present on the newly emerged mesoderm and not on the embryonic ectoderm in sections of embryos in utero. Conversely, cytokeratin, stage-specific embryonic antigen 1 (SSEA-1), E-cadherin and desmoplakin are expressed by the embryonic ectoderm but lost during mesoderm formation in vivo. They are absent or expressed very weakly by the migrated cells in vitro. In addition, only explants of the ectoplacental cone (EPC) and visceral endoderm alone, expressed a carbohydrate epitope (recognised by monoclonal antibody BOO6), characteristic of the EPC and primitive endoderm in utero, but absent from mesoderm. Thus we conclude that the cells which outgrow in this system are indeed mesodermal in phenotype. We have confirmed the work of others in demonstrating the presence of fibronectin (FN) and laminin (LN) in the migratory path of the mesoderm, at the ectoderm-visceral endoderm interface. We also report that the beta 1 integrin subunit of the FN and LN receptor is expressed by mesodermal cells at this interface. Using our in vitro model we have examined the role of the extracellular matrix (ECM) in mesodermal migration. Mesodermal cells migrate further and faster on substrates coated with FN or LN, and this increased migration is abolished by appropriate blocking antibodies. We conclude that the ECM, in particular FN and LN, plays an important role in the migration of primary mesodermal cells during gastrulation in the mouse embryo.

Animals↗

PubMed1995

Apoptotic death in an in vitro model of neuronal oxidative stress.

1. Oxidative stress is believed to be an important mediator of neuronal cell death but the precise mechanism by which this occurs is unknown. 2. We have developed an in vitro model of neuronal oxidative stress to study the pathways by which free radicals kill neurones. 3. We have shown that oxidative stress, cystine deprivation and glutathione depletion results in cell death with the morphological and biochemical features of apoptosis. 4. Neuronal apoptosis induced by oxidative stress can be inhibited by macromolecular synthesis inhibitors. 5. This in vitro model will be a valuable tool for defining the molecular targets of toxic free radicals in neurones and, in turn, in designing rational new therapies for free radical mediated diseases.

Apoptosis↗

PubMed1989

Epithelial bridging of the primary palate: II. In vitro model mimics in vivo behavior.

Previously, Forbes et al. [J Craniofac Genet Dev. Biol, 9:271-284, 1989] and Millicovsky et al. [Am J Anat 164:29-44, 1982], demonstrated that some of the epithelial cells of the primary palate formed extensive projections, bridging the medial and lateral nasal prominences. These connections are thought to aide in the fusion process by facilitating union of the prominences, a process known as secondary fusion [Millicovsky et al., 1982]. In order to study the epithelial cell and its behavior more closely an in vitro model was established [Gibson et al.: J Craniofac Genet Dev Biol, 1989], where epithelial cells in culture were shown to produce many of the morphologic characteristics observed in vivo. In the present study, an in vitro model is discussed which reproduces the epithelial projections observed in vivo. Epithelial cells, previously characterized, were obtained from the primary palate of 13-day-old rat embryos and sub-cultured as explants. Comparisons were made with the epithelial bridging observed in vivo of two species of animals. The results indicated sub-cultured epithelium as isolated cells, at either low or high density, rarely formed bridges. Primary cultures of epithelial explants also infrequently formed projections. However, sub-cultures of epithelial explants, plated as small clusters of cells with intervening spaces between cell groups, demonstrated extensive epithelial bridging. Epithelial projections did not form from cells that were directly attached to the plastic culture dish; only superficial, elevated cells formed projections. Significantly, the connections that occurred between explants did not attach to the plastic substratum. Instead, they appeared as line connections suspended by the medium. With time, the number of projections increased and epithelial cells could be seen along the projections forming an epithelial bridge. This study established a model of epithelial bridging in vitro for analysis of a process which has been shown to be an integral part of primary palate fusion.

Amniotic Fluid↗

PubMed1994

An in vitro model for the effects of androgen on neurons employing androgen receptor-transfected PC12 cells.

Androgen alters neurite outgrowth, synaptic organization, and cell survival in various portions of the brain and spinal cord. However, examination of the specific effects of androgen on neurons in vivo has been difficult. Previously, an in vitro model for the effects of estrogen on neurons was developed and characterized, using an estrogen receptor (ER)-transfected PC12 rat pheochromocytoma cell line. This model demonstrated estrogenic regulation of neurite outgrowth, spine formation, and gap junction formation. Similarly, an in vitro model for the effects of androgen on neurons is now described. Wild-type cells (PC12-WT) were stably transfected with an expression vector coding for the full-length cDNA for the human androgen receptor (AR). Resultant clones were isolated, screened for incorporation of vector and expression of AR mRNA and protein, and analyzed for morphologic responses to androgen. PC12-WT, NE09 (ER-negative, AR-negative), SER8 (ER-positive, AR-negative), and AR8 (ER-negative, AR-positive) cells were exposed to 10 ng/ml nerve growth factor (NGF), along with 0-10(-7) M dihydrotestosterone (DHT) for 2 days. AR8 cells demonstrated an androgen dose-dependent increase in mean neurite length, branch order, and neurite field area, whereas neurite branch segment length and soma area were not affected by androgen. PC12-WT, NE09, and SER8 cells exhibited no alterations in cell morphology with DHT exposure. Because of the synergistic effects of DHT and NGF, the regulation of NGF receptor mRNA by DHT was evaluated; however, no significant induction of either trkA or p75 mRNA expression by androgen was documented. The results suggest that in AR-positive PC12 cells, androgen acts additively with NGF to increase neurite outgrowth; but androgen effects are mediated specifically through branching and arborization. These responses are similar to developmental studies of androgen effects in vivo. Thus, androgen appears to induce an inherent neural morphologic program in AR-containing cells, which increases the receptive field of these cells, increasing the likelihood for interneural communication, although not promoting communication itself. These cell lines will provide a unique in vitro system for studying mechanisms of androgen-neuron interactions.

Androgens↗

PubMed2000

In vitro models of human blastocyst implantation.

This paper reviews different in vitro models used for the study of blastocyst implantation in animals and the human. Furthermore, results from human blastocyst-endometrial interactions in vitro, investigated by scanning electron microscopy (SEM), light microscopy (LM) and transmission electron microscopy (TEM), are presented. SEM demonstrates the preference of human blastocysts to adhere to pinopode-presenting areas on endometrial cell cultures. LM and TEM show that the first morphological sign of cell contact, defined as junction formation, is present at the apical-to-lateral border of endometrial epithelial cells, whereas trophoblast attachment to apical endometrial epithelial plasma membranes was not observed. More advanced stages illustrate that the human blastocyst penetrates the epithelial lining by the intrusive penetration mechanism.

Animals↗

PubMed1991

Oncogene-mediated transformation. An in vitro model for colon carcinogenesis.

Evaluation of molecular events in human colon polyps and tumors has revealed constitutive elevated expression of c-myc, activation of both ras and src proto-oncogenes, and allelic deletion events involving inactivation of putative regulatory genes, including p53. To evaluate the contribution of each of these events to colon carcinogenesis, it is desirable to establish epithelial cell lines representing different stages of neoplastic progression. Such in vitro models can be used to establish a primary role for different genes implicated in neoplastic transformation, identifying events involved in multistep carcinogenesis and delineating the factors modulating cellular transformation. We present herein a summary of such an in vitro model for colon carcinogenesis using the introduction of relevant genetic elements into normal mucosa to identify the molecular steps and accompanying cellular events underlying neoplastic progression in the colon.

Animals↗

PubMed2005

Endothelial cell protection and complement inhibition in xenotransplantation: a novel in vitro model using whole blood.

BACKGROUND: Studying the interactions between xenoreactive antibodies, complement and coagulation factors with the endothelium in hyperacute and acute vascular rejection usually necessitates the use of in vivo models. Conventional in vitro or ex vivo systems require either serum, plasma or anti-coagulated whole blood, making analysis of coagulation-mediated effects difficult. Here a novel in vitro microcarrier-based system for the study of endothelial cell (EC) activation and damage, using non-anticoagulated whole blood is described. Once established, the model was used to study the effect of the characterized complement- and coagulation inhibitor dextran sulfate (DXS, MW 5000) for its EC protective properties in a xenotransplantation setting. METHODS: Porcine aortic endothelial cells (PAEC), grown to confluence on microcarrier beads, were incubated with non-anticoagulated whole human blood until coagulation occurred or for a maximum of 90 min. PAEC-beads were either pre- or co-incubated with DXS. Phosphate buffered saline (PBS) experiments served as controls. Fluid phase and surface activation markers for complement and coagulation were analyzed as well as binding of DXS to PAEC-beads. RESULTS: Co- as well as pre-incubation of DXS, followed by washing of the beads, significantly prolonged time to coagulation from 39 +/- 12 min (PBS control) to 74 +/- 23 and 77 +/- 20 min, respectively (P < 0.005 vs. PBS). DXS treatment attenuated surface deposition of C1q, C4b/c, C3b/c and C5b-9 without affecting IgG or IgM deposition. Endothelial integrity, expressed by positivity for von Willebrand Factor, was maintained longer with DXS treatment. Compared with PBS controls, both pre- and co-incubation with DXS significantly prolonged activated partial thromboplastin time (>300 s, P < 0.05) and reduced production of thrombin-antithrombin complexes and fibrinopeptide A. Whilst DXS co-incubation completely blocked classical pathway complement activity (CH50 test) DXS pre-incubation or PBS control experiments showed no inhibition. DXS bound to PAEC-beads as visualized using fluorescein-labeled DXS. CONCLUSIONS: This novel in vitro microcarrier model can be used to study EC damage and the complex interactions with whole blood as well as screen ''endothelial protective'' substances in a xenotransplantation setting. DXS provides EC protection in this in vitro setting, attenuating damage of ECs as seen in hyperacute xenograft rejection.

Animals↗

PubMed2003

On the accuracy of some in vitro models for mechanical studies of maxillary removable partial dentures.

OBJECTIVES: Comparative in vitro/in vivo studies show wide differences in functional strain magnitudes and patterns of functional strain distribution in prosthetic devices. The aim of this study was to evaluate the accuracy of three in vitro models for biomechanical studies of prosthetic devices. METHODS: Strain gages were attached to the test RPDs of six subjects. In vitro maxillary models with simple (model A), intermediate (model B) and advanced (model C) features for the anatomical simulation of supporting structures were manufactured for each subject. The dentures were subjected to two separate series of standardized functional and laboratorial loading tests. The principal maximum strain value (epsilon (1)) obtained for each gage and experiment was used to calculate the intra-experiment variance and inter-experiment variance for the in vivo and in vitro experiments. The integrated strain gage difference value between the in vitro and in vivo data (Sigma(diff)) was calculated for every loading test and compared to the in vivo inter-experiment variance with ANOVA and Scheffés test. RESULTS: The bite forces recorded were similar for each subject and loading position and between the two loading sessions. The inter- and intra-experiment variance was found to be higher for in vivo loadings than for in vitro. Results showed that the (Sigma(diff)) values for model B and model C were significantly different from the in vivo strain inter-experiment variance (p<0.05). SIGNIFICANCE: This study showed that the anatomical simulation of in vitro models is insufficient to allow for accurate mechanical analyses of maxillary RPDs and that only simple verifications of the strain levels in prosthetic appliances can be attained in vitro.

Aged↗

PubMed1988

An in vitro model of 1-methyl-4-phenyl-pyridinium (MPP+) toxicity: incubation of rabbit caudate nucleus slices with MPP+ followed by biochemical and functional analysis.

1. Slices of rabbit caudate nucleus were preincubated for up to 24 h in vitro in the presence of the neurotoxic compound 1-methyl-4-phenyl-pyridinium (MPP+). Subsequently the levels of endogenous monoamines in the slices were determined by h.p.l.c. with electrochemical detection. MPP+, in concentrations higher than 32 nM significantly diminished the dopamine levels within the slices in a concentration- and time-dependent manner; at 32 microM the depletion was more than 95%. The concentration of the major metabolite of dopamine, dihydroxyphenyl acetic acid (DOPAC) was decreased at concentrations of MPP+ that did not alter dopamine levels. Thus, MPP+ increased the dopamine/DOPAC ratio. 2. In contrast, both 5-hydroxytryptamine (5-HT) levels and 5-HT/5-hydroxyindolacetic acid (5-HIAA) ratios were increased at nanomolar concentrations of MPP+. 5-HT was significantly reduced only at 32 microM. 3. The dopamine uptake inhibitor nomifensine reduced the depletory effect of MPP+ on dopamine and DOPAC content. 4. Following 24 h pretreatment with MPP+, the uptake of [3H]-dopamine into rabbit caudate nucleus slices was either enhanced (at 0.32 microM, 1 microM and 3.2 microM MPP+) or reduced (at 32 microM MPP+). 5. Preincubation of slices with 10 microM MPP+ for only 1 h increased their 3H-labelling (in contrast to 24 h pretreatment) whereas after 9 h no net increase was detectable. After 1 and 9 h MPP+ pretreatment, much less deaminated metabolites of [3H]-dopamine were found in the incubation medium of MPP+ treated slices than in the medium of control slices. These findings suggest that MPP+ strongly inhibits the enzyme monoamine oxidase (MAO) within dopaminergic (and 5-hydroxytryptaminergic) terminals before destroying them. 6. To validate the proposed in vitro model functionally, the electrically evoked release of [3H]-acetylcholine ([3H]-ACh) was investigated in MPP+ treated slices and controls. MPP+ reduced both the facilitatory effect of the D2-receptor antagonist domperidone and the inhibitory effect of the catecholamine uptake inhibitor nomifensine on [3H]-ACh release; effects compatible with a diminished inhibitory dopaminergic input on cholinergic neurones. 7. These findings also show that the terminal region of dopaminergic neurones, the caudate nucleus, is a site for MPP+ toxicity. The present in vitro model may be useful for investigating the effects of MPP+ and its interaction with other drugs under defined conditions.

1-Methyl-4-phenylpyridinium↗

PubMed2002

An in vitro model of neurotrauma in organotypic spinal cord cultures from adult mice.

Cellular degeneration after spinal cord injury (SCI) involves numerous pathways. It is essential to use appropriate experimental models in order to understand the complex processes, which evolve after the initial trauma. The purpose of this study was to develop and assess an in vitro model of neurotrauma using organotypic slice culture of adult mice spinal cord. This model will facilitate the investigation of primary and secondary mechanisms of cell death that occurs after SCI. We modified previously described methods for generating organotypic cultures of murine spinal cord. The viability of organotypic cultures was assessed by observing the outgrowth of neurites and by using a mitochondria dependent dye for live cells (tetrazolium dye; MTT). The morphological integrity of cultures was examined histologically by hematoxylin and eosin (H&E) staining for general morphology and with luxol fast blue (LFB) for myelin. Neuronal and glial (GFAP; CNPase) markers were used to identify neurons, astrocytes and oligodendroglia, respectively. Primary injury was achieved by using a weight drop (0.2 g) model of injury. Cell death after primary injury was attenuated by pre-treatment with two known neuroprotective agents: the AMPA/KA blocker CNQX and methylprednisolone. The nuclear markers Propidium iodide and Sytox-green, as well as the TUNEL (in situ terminal deoxytransferase-mediated dUTP nick end labeling) technique, were used as a quantitative indicators of cell death at 24, 48 and 72 h post-injury using a confocal microscope and image analysis software. This novel in vitro model of SCI is easy to reproduce, will facilitate the examination of post-trauma cell death mechanisms and the neuroprotective effects of pharmacological agents and aid in the study of transgenic murine models.

Animals↗

PubMed1997

Development and initial application of an in vitro model of apoptosis in rodent cholangiocytes.

Although histological data suggest that cholangiocytes die by apoptosis in human liver diseases, no information exists on the mechanisms of cholangiocyte apoptosis. Thus our aims were to establish an in vitro model of cholangiocyte apoptosis and to test the hypothesis that changes in intracellular ions would cause apoptosis in cholangiocytes by a protease-sensitive pathway. A large number of proapoptotic agents were ineffective in inducing apoptosis in rat or human cholangiocytes in culture; in contrast, beauvericin, a K+ ionophore, caused apoptosis in both cell lines, despite their expression of Bcl-2. Although beauvericin decreased intracellular K+ and increased intracellular Ca2+, abolishing the K+ gradient did not prevent beauvericin-induced apoptosis; in contrast, omission of extracellular Ca2+ inhibited apoptosis by 42%. The interleukin-1 beta-converting enzyme (ICE) family protease inhibitor, Z-Val-Ala-Asp chloromethylketone, inhibited apoptosis in a concentration-dependent manner. By Northern blot analysis, cholangiocytes expressed the mRNA for three members of the ICE protease family: ICE, ICE/ CED-3 homologue-1 (ICH-1), and cysteine protease P-32 (CPP-32). Cleavage of a substrate for CPP-32-like protease activity, but not a substrate for ICE and ICH-1, increased after beauvericin treatment. In summary, we have established an in vitro model of apoptosis in cholangiocytes. Our data suggest that beauvericin-induced apoptosis occurs by a Ca(2+)-dependent CPP-32 protease-sensitive pathway despite cholangiocyte expression of Bcl-2.

Animals↗

PubMed1984

Rapid desensitization and uncoupling of human beta-adrenergic receptors in an in vitro model of lactic acidosis.

Adrenergic responsiveness in many tissues may be impaired in the presence of lactic acidosis. The purpose of this study was to examine how human neutrophil beta 2-adrenergic receptors may be altered in an in vitro model of lactic acidosis. Receptor coupling was assessed by constructing curves for the competition of isoproterenol with [125I]iodocyanopindolol for beta-adrenergic receptors. Receptors were exposed to control (2 mM lactate, pH 7.4), lactic acidosis (16 mM lactate, pH 7.1), lactate excess (16 mM lactate, pH 7.4), and low pH (2 mM lactate, pH 7.1) conditions. Prior exposure of beta-adrenergic receptors on whole cells to lactic acidosis resulted in a 61% reduction in isoproterenol-stimulated cAMP accumulation (P less than 0.005). This desensitization was not accompanied by down-regulation. After exposure to lactic acidosis, beta-adrenergic receptors were uncoupled sufficiently that a high affinity state could not be detected. Both lactate excess and low pH were necessary to fully express the desensitization and uncoupling defects. The uncoupling was rapid (40 min) and occurred in cell-free membrane preparations. Thus, in an in vitro model of lactic acidosis, rapid desensitization and uncoupling occur which do not appear to require protein synthesis.

Acidosis↗

PubMedDate not supplied

[An in vitro model for producing femoral fractures and for the study of primary stability of cerclage].

PURPOSE: Intraoperative femoral fracture is a well recognized intraoperative complication of cementless total hip arthroplasty (THA). This study was designed to establish an in-vitro model for initiation of fractures of the femur in cementless THA and to assess the effect of fracture fixation by cerclage wiring using steel wire (Protasul). METHODS: Ten human femur specimens were studied. Longitudinal cracks were created by pressing a well fixed conical stem deeper into the femur in a material testing machine. RESULTS: The force necessary to propagate a longitudinal crack in the femur was 1915 N to 9288 N (median 6531 N). This forces are according to 3 to 15 times (median 11 times) body weight. There was no difference of force between left and right femurs from the same individual (U-test). The femoral cortex fractured in 5 cases ventrally, in 6 cases medially and in 1 case laterally. After monofile cerclage wire application the force required to press prosthesis 5 mm deeper into the medullary canal was 0.3 to 2.7 times body weight. After monofile cerclage wire application pressing in the prosthesis 30 mm needed 1.8 to 8.1 times body weight. CONCLUSIONS: During insertion of a conical stem the orthopaedic surgeon should look for fractures of the medial cortex of the femur which is the most frequent location for fractures. This in-vitro model provides a reproductable method for the initiation and propagation of longitudinal femoral fractures in press-fit noncemented THA system and to assess the effect of fracture fixation in the form of cerclage wiring.

Adult↗

PubMed2003

Characterisation of some cytotoxic endpoints using rat liver and HepG2 spheroids as in vitro models and their application in hepatotoxicity studies. I. Glucose metabolism and enzyme release as cytotoxic markers.

Cytotoxicity endpoints, spontaneous glucose secretion/consumption and LDH and gamma-GT release, were characterised in rat liver and HepG2 spheroids as in vitro models for toxicology studies. Preprepared rat liver spheroids and HepG2 spheroids cultured in a six-well plate format were exposed to varying concentrations of galactosamine, propranolol, diclofenac, and paracetamol. All four model toxins significantly affected glucose secretion, which agreed well with LDH and/or gamma-GT release in rat liver spheroids. These toxins also significantly increased LDH and/or gamma-GT release in HepG2 spheroids. Whereas glucose consumption in HepG2 spheroids did not show conclusive results, LDH activities in both types of spheroids were similar and their levels were relatively high. Accordingly, the level of LDH leakage in both types of spheroids was much higher than gamma-GT after exposure to the toxins. In contrast, gamma-GT activity in HepG2 spheroids was sixfold higher than that in rat liver spheroids. This study revealed that galactosamine interfered with the gamma-GT assay and paracetamol interfered with the LDH assay. It demonstrated, for the first time, that glucose secretion by liver spheroids can be used as a functional indicator of cytotoxicity. Test compounds may interfere with enzymatic assays as indicated by LDH and gamma-GT release in this study. Combining functional parameters together with two or more indicators of enzyme releases can provide a reliable cytotoxicity evaluation. Liver and HepG2 spheroids as in vitro models showed good predictions in chemical-induced hepatic cytotoxicity.

Acetaminophen↗

PubMed2005

Transcriptional profiling and assessment of cell lines as in vitro models for mantle cell lymphoma.

Mantle cell lymphoma (MCL) is an aggressive malignancy and new treatment modalities must be established to increase patient survival time. In the search for new therapeutic targets, reliable and well-characterised in vitro models are essential. In this study, we have characterised three MCL cell lines (SP53, Granta 519 and NCEB1) in comparison with primary tumours from MCL, follicular lymphomas (FL), a FL cell line (RL), a Burkitt lymphoma cell line (RAJI) and five different B cell populations from healthy individuals. Expression profiling was used to determine the relative expression of >12000 transcripts in these samples, and flow cytometry analysis was performed to establish a phenotypic signature for each of the cell lines. In addition, the cell lines were sequenced, and the frequency of somatic mutations and immunoglobulin (Ig) variable heavy chain (VH) usage were determined. We show by hierarchical clustering that the cell lines retain a genetic signature similar to primary MCL, which readily separated the MCL samples from the other lymphoma cell lines and the FL tumours. Furthermore, the MCL cell lines showed differences in the frequency of VH somatic mutations (0-2.1%). The increased number of mutations in NCEB1, compared to the other MCL cell lines, was in agreement with a decreased expression of CD31, CD44, CXCR5, CCR7 and CCR6. Taken together, our data show that the cell lines are clearly derived from MCL tumours and expressed similar genetic and phenotypic signatures compared to primary tumours, which confirmed their usefulness as in vitro models.

B-Lymphocytes↗