Search PubMed⌕ Search

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.

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

At least 883 records · Page 49Linked to original sources
PubMed1997

In vitro model(s) for the percutaneous delivery of active tissue repair agents.

There is a need to evaluate the permeability of human ulcerated tissue and periulcer tissue in order to assess the possible treatment of such a localized pathological lesion with a topical therapy. In vitro percutaneous absorption studies were undertaken to evaluate an animal model that may mimic this clinical situation. Porcine skin from three anatomical sites, the ear, abdomen, and dorsum; ischaemic skin (porcine and guinea pig); porcine wounds; and human skin (including periulcer and ulcerated tissue) were investigated, utilizing both whole skin and dermal membranes. Dermal membranes were chosen as representative of ulcerated tissue, as there would be no epidermal barrier present, and the thickness of the dermal membrane was not expected to offer any diffusional resistance to topically applied active agents. A range of chemicals with differing physicochemical properties was investigated using a Franz type diffusion cell. For all tissues a permeability coefficient (kp with units of cm h-1) was measured, along with skin thickness and tissue partition coefficient measurements. Under these experimental conditions and for the range of compounds tested, the results suggest that porcine skin, whole skin, and dermal membranes should be considered as good representative in vitro models for the topical delivery of compounds to human skin and ulcerated tissue, respectively.

Administration, Cutaneous↗
PubMed2002

L-arginyl-3,4-spermidine is neuroprotective in several in vitro models of neurodegeneration and in vivo ischaemia without suppressing synaptic transmission.

1. Stroke is the third most common cause of death in the world, and there is a clear need to develop new therapeutics for the stroke victim. To address this need, we generated a combinatorial library of polyamine compounds based on sFTX-3.3 toxin from which L-Arginyl-3,4-Spermidine (L-Arg-3,4) emerged as a lead neuroprotective compound. In the present study, we have extended earlier results to examine the compound's neuroprotective actions in greater detail. 2. In an in vitro ischaemia model, L-Arg-3,4 significantly reduced CA1 cell death when administered prior to induction of 60 min of ischaemia as well as when administered immediately after ischaemia. Surprisingly, L-Arg-3,4 continued to prevent cell death significantly when administration was delayed for as long as 60 min after ischaemia. 3. L-Arg-3,4 significantly reduced cell death in excitotoxicity models mediated by glutamate, NMDA, AMPA, or kainate. Unlike glutamate receptor antagonists, 300 microM L-Arg-3,4 did not suppress synaptic transmission as measured by evoked responses in acute hippocampal slices. 4. L-Arg-3,4 provided significant protection, in vitro, in a superoxide mediated injury model and prevented an increase of superoxide production after AMPA or NMDA stimulation. It also decreased nitric oxide production after in vitro ischaemia and NMDA stimulation, but did so without inhibiting nitric oxide synthase directly. 5. Furthermore, L-Arg-3,4 was significantly neuroprotective in an in vivo model of global forebrain ischaemia, without any apparent neurological side-effects. 6. Taken together, these results demonstrate that L-Arg-3,4 is protective in several models of neurodegeneration and may have potential as a new therapeutic compound for the treatment of stroke, trauma, and other neurodegenerative diseases.

Animals↗
PubMed1980

The effects of some antirheumatic drugs on an in vitro model of human polymorphonuclear leucocyte chemokinesis.

1 A rapid, reproducible in vitro assay for studying the chemokinetic movement of human polymorphonuclear leucocytes (PMNs) is described. Two synthetic peptides, formyl methionyl-leucyl-phenylalanine (FMLP) and formyl methionyl-phenylalanine (FMP), were used as a standard chemokinesins. 2 Maximal chemokinetic movement was observed with peptide concentrations of 2.5 nM (FMLP) and 100 muM (FMP). EC50 values of 650.0 +/- 60.0 pM and 27.0 +/- 3.5 muM respectively are similar to those reported for chemotactic activity of the peptides in micropore filter assays. 3 The PMN chemokinetic response to FMLP was enhanced by histamine (100 nM) and vitamin C (2.5 muM). 4 Human serum albumin was shown to induce chemokinesis but to antagonize the response to FMLP in a dose-related fashion. Fibrinogen similarly antagonized the cell response to peptide. 5 Levamisole (250 nM to 2.5 muM) significantly potentiated the chemokinetic responses to FMLP and FMP in a dose-related manner. The chemokinetic response to FMLP was unaffected by D-penicillamine (250 muM to 10 mM) while alclofenac (500 muM to 1 mM), salicylic acid (250 muM to 10 mM) and indomethacin (100 muM to 1 mM) caused dose-related inhibition.

Anti-Inflammatory Agents↗
PubMed1994

Agar-entrapped bacteria as an in vitro model of biofilms and their susceptibility to antibiotics.

A simple in vitro system was developed as a model structure of biofilms and to evaluate their susceptibility to antibiotics. Viable Escherichia coli cells were entrapped in agar gel layers and incubated for 2 days in a minimal salt medium supplemented with glucose. After subsequent culture for 3 weeks under metal ion depletion, the biomass distribution inside the gel layer was highly heterogeneous. The cell concentration reached 10(11) cfu/g gel in the outer regions of the agar structure whereas the inner gel areas were less colonized (10(9) cfu/g gel). Immobilized cells displayed enhanced resistance to latamoxef as compared with free microorganisms. Moreover, a 3-week-old immobilized-cell membrane was less susceptible to the antibiotic than a younger (2 days old) one. The exposure for 11 h to 64 micrograms/cm3 latamoxef killed about 90% of the bacteria entrapped in the older agar layer, whereas the number of killed cells was 100-fold higher in the younger structure. Effective diffusivity measurements showed that the diffusion of latamoxef in the biofilm-like agar structures was moderately restricted as compared to that in water, and independent of the immobilized-cell content.

Agar↗
PubMed1999

[Introduction of the lipofuscin-fluorophor A2E into the lysosomal compartment of human retinal pigment epithelial cells by coupling to LDL particles. An in vitro model of retinal pigment epithelium cell aging].

PURPOSE: Lipofuscin accumulates with age and in association with various retinal diseases. To investigate cellular effects of lipofuscin components in an in vitro RPE cell model, specific loading of the lysosomal compartment is required. Herein a major lipofuscin fluorophor was complexed to LDL and the subsequent subcellular localization of the retinoid was examined. METHODS: The lipofuscin component N-retinylidene-N-retinylethanolamine (A2-E) was synthesized and coupled to LDL. Human RPE cell cultures were loaded with the A2-E/LDL complex over 4 weeks. Thereafter, RPE cells were harvested by trypsinization and disrupted by nitrogen cavitation. After ultra-centrifugation, the postnuclear supernatant was fractionated on a self-generating gradient and fractions were analyzed by measuring marker enzyme activities of various cellular compartments. RESULTS: A2-Eaccumulated almost exclusively in the lysosomal compartment, as indicated by the identical peaks of the marker enzyme ss-hexosaminidase and the relative fluorescence of A2-E. Only a small amount of A2-E appeared to associate with the cell membrane, as shown by a minor peak of A2-E corresponding to the distribution of phosphodiesterase activity. The lysosomal marker enzyme was not present in the cytosolic fraction. CONCLUSIONS: The feeding of A2-E/LDL complexes to cultured RPE-cells proved to be highly effective in specific loading of the lysosomal compartment, providing a suitable in vitro cell culture model for RPE aging and the investigation of A2-E-effects on lysosomal functions in RPE cells. Such a model may contribute to the understanding of the pathogenesis of degenerative diseases of the outer retina associated with excessive lipofuscin accumulation, including age-related macular degeneration, Stargardt's disease and Best's disease.

Cells, Cultured↗
PubMed1990

Sensitizing capacity of three methyl alkanesulphonates: a murine in vivo and in vitro model of allergic contact dermatitis.

A murine model for in vivo and in vitro studies of contact sensitization to methyl alkanesulphonate derivatives has been developed. Contact sensitivity was quantified in vivo by measuring the ear thickness increase, and the influence of the alkyl chain length (hexyl, dodecyl, hexadecyl) was investigated. Long chain methyl alkanesulphonates (dodecyl and hexadecyl) are strong sensitizers, while the shorter alkyl chain, methyl hexanesulphonate, is a weak sensitizer. In vitro lymphocyte blastogenesis was measured by the 3H-thymidine uptake and exhibited a stimulation index between 2 and 8. The results nicely parallelled the in vivo sensitization measurements, except for methyl dodecanesulphonate. This could be explained by the cytotoxic activity of this compound, the most toxic of the three methyl alkanesulphonates tested. Thus, murine sensitization to methyl alkanesulphonates provides a good model system for preliminary investigations of delayed type hypersensitivity mechanisms.

Alkanesulfonates↗
PubMed2002

Development of an in vitro model to study oxidative DNA damage in human coronary smooth muscle cells.

Oxidative damage in the vascular system has been linked to the development of atherosclerosis. The aim of the present study was to establish a cell culture model for the investigation of in vitro induced oxidative DNA injury, its modulation and repair kinetics. Primary cultures of human coronary artery smooth muscle cells were used as target cells. The cells were exposed to hydrogen peroxide (H2O2). DNA damage was quantified by the alkaline single-cell gel electrophoresis assay (comet assay). This method allows quantification of DNA single and double strand breaks and of alkali-labile sites in individual cells. In the present study H2O2 concentration-responses and dependence of damage on exposure time and temperature were evaluated and the repair kinetics were studied. The results show that this cell culture model can be employed to study oxidative DNA injury in the cells of the human cardiovascular system, a promoter of cardiovascular disease. Further it offers the possibility to investigate pharmacological modulators of such oxidative effects. Such modulators are antioxidants like vitamin C and E, steroid hormones, phytoestrogens, or synthetic agents. Today, pigs, rabbits or rats are used to test systemic and local administration of the named modulating substances, the latter by use of special catheters or stents placed inside the arteries. These experiments require treatment observation over a number of weeks and killing of the animals at the end of the experiment. By using the proposed cell culture model such animal experiments could be partly avoided.

Cell Survival↗
PubMed1980

In vivo and in vitro models of demyelinating diseases. III. JHM virus infection of rats.

Suckling rats of three inbred and three outbred strains were inoculated intraperitoneally (P) or intracerebrally (IC) with the JHM strain of mouse hepatitis virus (JHMV) and were monitored for evidence of neurologic diseases. Consequences of varying age at inoculation, route of injection, and virus dose were ascertained. No disease was evident after IP injection but IC inoculation with at least 10(4) plaque-forming units at 2 days of age resulted in either a rapidly fatal encephalitis or a chronic, progressive, fatal neurologic disease in most rats, regardless of strain. Inoculation at 5 or 10 days of age predominantly caused the chronic neurologic disease, characterized by demyelinating lesions in the brain, spinal cord, or optic nerve, which sometimes were evident as late as several months postinoculation. Demyelination in the optic nerve proved to be concurrent with demyelinating lesions elsewhere in the CNS. Occasionally, clinical remissions were observed in rats in which posterior paralysis developed, suggesting that remyelination in the rat can occur. Demonstration of virus replication, by infectivity, in rats exhibiting neurologic disease and in rats without clinical symptoms was substantiated by electron microscopic observations of virus development and assembly in oligodendroglia of the optic nerve and spinal cord. In view of the protracted course of the disease in some rats, presence of demyelinating lesions confirmed by light and electron microscopy, and remissions of clinical symptoms, the JHMV-infected rat seems to be an appropriate animal model to study virus-mediated progressive demyelinating disease.

Animals↗
PubMed2001

Adherence and invasion studies of Candida albicans strains, using in vitro models of esophageal candidiasis.

The adherence of clinical and commensal isolates and reference collection strains of Candida albicans to a human esophageal cell monolayer (HET1-A) and reconstituted human esophageal tissue was compared. Isolates from patients with a severe form of esophageal candidiasis or candidemia adhered to HET1-A cells to a significantly greater extent than did isolates from patients with mild esophageal candidiasis or commensal and reference collection strains. In addition, C. albicans strain SSK21, which lacks the ssk1 response regulator gene of a 2-component signal transduction pathway, adhered less readily to the HET1-A cells than did parental cells or a gene-reconstituted strain. In a reconstituted esophageal tissue model, all clinical strains but not commensal or reference collection strains penetrated the epithelium, albeit at different rates. Hyphal formation following yeast cell adherence to the esophageal tissue was a requirement for invasion. Scanning electron microscopy was also used to confirm the colonization of the esophageal tissues by various strains. These studies indicate that both the HET1-A and the reconstituted esophageal tissue models can be used as in vitro targets to evaluate the adherence phenotype and invasiveness of C. albicans strains.

Candida albicans↗
PubMed2004

T cells support osteoclastogenesis in an in vitro model derived from human multiple myeloma bone disease: the role of the OPG/TRAIL interaction.

The development of multiple myeloma (MM) bone disease is mediated by increased number and activity of osteoclasts (OCs). Using an in vitro osteoclastogenesis model consisting of unstimulated and unfractionated peripheral blood mononuclear cells (PBMCs) from patients with MM, we showed that T cells support the formation of OCs with longer survival. Different from T-cell-depleted MM PBMC cultures, exogenous macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor-kappaB ligand (RANKL) were necessary for the formation of OCs; however, they did not exhibit longer survival. We found up-regulated production of RANKL, osteoprotegerin (OPG), and TNF-related apoptosis-inducing ligand (TRAIL) by fresh MM T cells. Despite high OPG levels, the persistence of osteoclastogenesis can be related to the formation of the OPG/TRAIL complex demonstrated by immunoprecipitation experiments and the addition of anti-TRAIL antibody which decreases OC formation. OCs overexpressed TRAIL decoy receptor DcR2 in the presence of MM T cells and death receptor DR4 in T-cell-depleted cultures. In addition, increased Bcl-2/Bax (B-cell lymphoma-2/Bcl2-associated protein X) ratio, following Bcl-2 up-regulation, was detected in OCs generated in the presence of T cells. Our results highlight that MM T cells support OC formation and survival, possibly involving OPG/TRAIL interaction and unbalanced OC expression of TRAIL death and decoy receptors.

Aged↗
PubMed1998

Expression of matrix Gla protein (MGP) in an in vitro model of vascular calcification.

To investigate the role of matrix Gla protein (MGP), which can bind mineral ions through gamma-carboxylated glutamic acid residues, in vascular calcification, we examined the expression of MGP in an in vitro calcification model by using bovine vascular smooth muscle cells (BVSMC). The expression of MGP mRNA was decreased during BVSMC calcification and its levels were inversely correlated with the quantities of BVSMC calcification. MGP mRNA expression was restored to the level of uncalcified control by inhibiting BVSMC calcification with bisphosphonates. These data suggest that the expression of MGP gene is modulated in the development of vascular calcification.

Alendronate↗
PubMed2004

In vitro models to test orthopedic biomaterials in view of their clinical application in osteoporotic bone.

The development of in vitro cell cultures, in association with in vivo experimentation, greatly improved the characterization of biomaterials for orthopedic devices before their clinical use. In recent years an increasing interest has arisen in the use of both pathological osteoblast cultures and animal models to perform in vitro and in vivo tests on biomaterial behavior. A growing number of prostheses, in fact, are implanted in osteoporotic patients, due to the increasing age of the population. Moreover, the presence of osteoporosis may affect bone-biomaterial osteointegration in these patients. The present paper is a literature review and, after a short description of in vitro studies for characterization of osteoblasts derived from osteoporotic bone, the results of in vitro studies on biomaterial biocompatibility and osteointegration rate in the presence of osteoporotic bone derived osteoblast cultures are reported. Pathological cell culture models are able to demonstrate the different behavior of osteoblasts in response to biomaterials, when comparing normal and pathological conditions.

Animals↗
PubMed2004

An in vitro model for the detection of reduced platelet sensitivity to acetylsalicylic acid.

A discovery of 'aspirin resistance' has prompted the search for fast and reliable methods for the monitoring of antiplatelet efficacy of acetylsalicylic acid (ASA). Our aims were: (1) to evaluate the in vitro model-based method for detecting a reduced platelets' sensitivity to ASA using a point-of-care platelet function analyser PFA-100; and (2) to propose a simple method of data analysis that might be successfully employed to discriminate between 'good' and 'poor' responders to aspirin. Whole blood platelets from healthy volunteers were incubated in vitro with 30 microg/ml ASA (the in vitro method under evaluation) or analysed following a 10-day intake of an average 150 mg ASA (Aspirin Protect) daily (the reference ex vivo method). According to polynomial regression analysis of the bimodally distributed data, the donors with lower ('ASA poor responders') or higher platelet sensitivity to ASA ('ASA good responders') were discriminated at 58.6% of platelet function inhibition. Despite the similar proportions of 'ASA poor responders' (44 versus 41% using the ex vivo and in vitro tests, respectively), 30% of discordant classifications point to a rather unsatisfactory convergence between both methods. Due to a considerable discordance between the in vitro and ex vivo tests of ASA efficacy performed with the use of the PFA-100 system, the former cannot be reliably and interchangeably used for the monitoring of aspirin therapy and the selection of an effective therapeutic ASA dose. A novel approach to data analysis of the distribution of platelet inhibition rates facilitates an evaluation of cut-off points required to discriminate between 'poor responders' and 'good responders' to aspirin.

Adult↗
PubMed1986

An in vitro model of erythroid egress in bone marrow.

An in vitro system has been developed that mimics the passage of erythrocytes from the bone marrow to the circulation. Bone marrow egress and its proper regulation are vital physiologic processes. However, because of the inaccessibility of the marrow, it is difficult to evaluate the various factors important in controlling these processes or even to define the precise mechanism by which egress occurs. The in vitro system has been designed to evaluate the importance of different physical parameters in regulating egress. It consists of a thin silicon wafer (thickness approximately equal to 1.0 micron) cemented over the tip of a large (15.0 micron ID) micropipette. The wafer contains a single circular pore. Cells were observed under the microscope as they passed through the pore under controlled pressures. The rate and duration of passage were obtained from videorecordings of the experiment. The measured passage times agreed well with the predictions of a simple analytical model of a cell passing through a thin aperture. The experimental results confirm the conclusion reached from the analysis that the pressures needed to drive a cell through the pore are well within the physiologic range, and the time needed to complete egress is typically less than 1.0 seconds. These results support the hypothesis that erythrocyte egress may be driven by a hydrostatic pressure difference across the pore.

Bone Marrow↗
PubMed1999

A three-dimensional in-vitro model for the study of peritoneal tumour metastasis.

Peritoneal metastasis is a frequent complication of gastrointestinal malignancy. We have developed a three-dimensional model of the human peritoneum that simulates the metastatic process in vitro. Peritoneal fibroblasts were incorporated into collagen lattices, allowed to contract, then overlaid with mesothelial cells. Scanning and transmission electron microscopy showed the model to have similar physical properties to human peritoneum. Mesothelial expression of the beta1 integrin family, the basement membrane proteins fibronectin, laminin, collagen types III and IV, and the cell adhesion molecules ICAM-1, VCAM-1 and PECAM were assessed and showed similar results to in vivo tissue. Gastrointestinal tumour cells seeded onto the model exhibited mesothelial adhesion, cell spreading and vesicle formation, and invasion of the mesothelial monolayer on scanning electron microscopy. Two distinct patterns of tumour cell growth were observed using light microscopy: a superficial spreading layer, and discrete invasive deposits. Invasion was accompanied by disruption of the mesothelial monolayer, degradation and re-orientation of the matrix, and rudimentary tumour cell differentiation. We believe the use of this in vitro peritoneal model will facilitate the study of the molecular mechanisms involved in the metastatic process.

Humans↗
PubMed1987

Relationships of five Doppler measures with flow in an in vitro model and clinical findings in newborn infants.

This report compares six Doppler ultrasound measures of blood flow: Pourcelot's pulsatility index, Gosling's pulsatility index, area under the curve, systolic amplitude, diastolic amplitude, and mean amplitude. Recordings from an in vitro arterial model and from the anterior cerebral arteries in 33 newborn infants with asphyxia, intraventricular hemorrhage, or normal state were analyzed. In the model, all measures had excellent correlation with flow. Neonates were correctly classified according to diagnosis by the Doppler measures as follows: Pourcelot's pulsatility index (100%), Gosling's pulsatility index (97%), diastolic amplitude (94%), mean amplitude (76%), area under the curve (70%), and systolic amplitude (58%). The best accuracy was obtained with the pulsatility indices.

Asphyxia Neonatorum↗