Showing papers by "University of Freiburg published in 2002"
Pfizer1, University of Manchester2, University of Texas Health Science Center at San Antonio3, National Institutes of Health4, Harvard University5, Charité6, University of Freiburg7, European Organisation for Research and Treatment of Cancer8, Fred Hutchinson Cancer Research Center9, University of Paris10, Pasteur Institute11, University of Florida12, University of California, San Diego13, Wayne State University14, Radboud University Nijmegen15
TL;DR: In patients with invasive aspergillosis,Initial therapy with voriconazole led to better responses and improved survival and resulted in fewer severe side effects than the standard approach of initial therapy with amphotericin B.
Abstract: Background Voriconazole is a broad-spectrum triazole that is active against aspergillus species. We conducted a randomized trial to compare voriconazole with amphotericin B for primary therapy of invasive aspergillosis. Methods In this randomized, unblinded trial, patients received either intravenous voriconazole (two doses of 6 mg per kilogram of body weight on day 1, then 4 mg per kilogram twice daily for at least seven days) followed by 200 mg orally twice daily or intravenous amphotericin B deoxycholate (1 to 1.5 mg per kilogram per day). Other licensed antifungal treatments were allowed if the initial therapy failed or if the patient had an intolerance to the first drug used. A complete or partial response was considered to be a successful outcome. Results A total of 144 patients in the voriconazole group and 133 patients in the amphotericin B group with definite or probable aspergillosis received at least one dose of treatment. In most of the patients, the underlying condition was allogeneic hematop...
3,003 citations
TL;DR: The PSQI has a high test-retest reliability and a good validity for patients with primary insomnia and can be used as a marker for sleep disturbances in insomnia patients versus controls.
1,402 citations
TL;DR: This is the first report that polysaccharide degradation products of the extracellular matrix produced during inflammation might serve as an endogenous ligand for the TLR-4 complex on DCs.
Abstract: Low molecular weight fragmentation products of the polysaccharide of Hyaluronic acid (sHA) produced during inflammation have been shown to be potent activators of immunocompetent cells such as dendritic cells (DCs) and macrophages. Here we report that sHA induces maturation of DCs via the Toll-like receptor (TLR)-4, a receptor complex associated with innate immunity and host defense against bacterial infection. Bone marrow–derived DCs from C3H/HeJ and C57BL/10ScCr mice carrying mutant TLR-4 alleles were nonresponsive to sHA-induced phenotypic and functional maturation. Conversely, DCs from TLR-2–deficient mice were still susceptible to sHA. In accordance, addition of an anti–TLR-4 mAb to human monocyte–derived DCs blocked sHA-induced tumor necrosis factor α production. Western blot analysis revealed that sHA treatment resulted in distinct phosphorylation of p38/p42/44 MAP-kinases and nuclear translocation of nuclear factor (NF)-κB, all components of the TLR-4 signaling pathway. Blockade of this pathway by specific inhibitors completely abrogated the sHA-induced DC maturation. Finally, intravenous injection of sHA-induced DC emigration from the skin and their phenotypic and functional maturation in the spleen, again depending on the expression of TLR-4. In conclusion, this is the first report that polysaccharide degradation products of the extracellular matrix produced during inflammation might serve as an endogenous ligand for the TLR-4 complex on DCs.
1,363 citations
TL;DR: It is shown that auxin accumulates asymmetrically during differential growth in an efflux-dependent manner and that actin-dependent relocalization of PIN3 in response to gravity provides a mechanism for redirecting auxin flux to trigger asymmetric growth.
Abstract: Long-standing models propose that plant growth responses to light or gravity are mediated by asymmetric distribution of the phytohormone auxin. Physiological studies implicated a specific transport system that relocates auxin laterally, thereby effecting differential growth; however, neither the molecular components of this system nor the cellular mechanism of auxin redistribution on light or gravity perception have been identified. Here, we show that auxin accumulates asymmetrically during differential growth in an efflux-dependent manner. Mutations in the Arabidopsis gene PIN3, a regulator of auxin efflux, alter differential growth. PIN3 is expressed in gravity-sensing tissues, with PIN3 protein accumulating predominantly at the lateral cell surface. PIN3 localizes to the plasma membrane and to vesicles that cycle in an actin-dependent manner. In the root columella, PIN3 is positioned symmetrically at the plasma membrane but rapidly relocalizes laterally on gravity stimulation. Our data indicate that PIN3 is a component of the lateral auxin transport system regulating tropic growth. In addition, actin-dependent relocalization of PIN3 in response to gravity provides a mechanism for redirecting auxin flux to trigger asymmetric growth.
1,321 citations
TL;DR: Almost one fourth of patients with apparently sporadic pheochromocytoma may be carriers of mutations; routine analysis for mutations of RET, VHL, SDHD, and SDHB is indicated to identify pheosene-associated syndromes that would otherwise be missed.
Abstract: Background The group of susceptibility genes for pheochromocytoma that included the proto-oncogene RET (associated with multiple endocrine neoplasia type 2 [MEN-2]) and the tumor-suppressor gene VHL (associated with von Hippel–Lindau disease) now also encompasses the newly identified genes for succinate dehydrogenase subunit D (SDHD) and succinate dehydrogenase subunit B (SDHB), which predispose carriers to pheochromocytomas and glomus tumors. We used molecular tools to classify a large cohort of patients with pheochromocytoma with respect to the presence or absence of mutations of one of these four genes and to investigate the relevance of genetic analyses to clinical practice. Methods Peripheral blood from unrelated, consenting registry patients with pheochromocytoma was tested for mutations of RET, VHL, SDHD, and SDHB. Clinical data at first presentation and follow-up were evaluated. Results Among 271 patients who presented with nonsyndromic pheochromocytoma and without a family history of the disease,...
1,228 citations
TL;DR: A new approach to the stabilization of numerical schemes in magnetohydrodynamic processes in which the divergence errors are transported to the domain boundaries with the maximal admissible speed and are damped at the same time is developed.
1,194 citations
TL;DR: In patients with severe, low-output heart failure, levosimendan improved haemodynamic performance more effectively than dobutamine and was accompanied by lower mortality in the levosIMendan group than in theDobutamine group for up to 180 days.
1,068 citations
TL;DR: It is proposed that the membranous web forms the viral replication complex in HCV-infected cells.
Abstract: Plus-strand RNA viruses characteristically replicate their genome in association with altered cellular membranes. In the present study, the capacity of hepatitis C virus (HCV) proteins to elicit intracellular membrane alterations was investigated by expressing, in tetracycline-regulated cell lines, a comprehensive panel of HCV proteins individually as well as in the context of the entire HCV polyprotein. As visualized by electron microscopy (EM), expression of the combined structural proteins core-E1-E2-p7, the NS3-4A complex, and protein NS4B induced distinct membrane alterations. By immunogold EM (IEM), the membrane-altering proteins were always found to localize to the respective altered membranes. NS4B, a protein of hitherto unknown function, induced a tight structure, designated membranous web, consisting of vesicles in a membranous matrix. Expression of the entire HCV polyprotein gave rise to membrane budding into rough endoplasmic reticulum vacuoles, to the membranous web, and to tightly associated vesicles often surrounding the membranous web. By IEM, all HCV proteins were found to be associated with the NS4B-induced membranous web, forming a membrane-associated multiprotein complex. A similar web-like structure in livers of HCV-infected chimpanzees was previously described (Pfeifer et al., Virchows Arch. B., 33:233-243, 1980). In view of this finding and the observation that all HCV proteins accumulate on the membranous web, we propose that the membranous web forms the viral replication complex in HCV-infected cells.
919 citations
TL;DR: The approach is based on role-based access control with additional support for specifying authorization constraints and can be used to improve productivity during the development of secure distributed systems and the quality of the resulting systems.
Abstract: We present a modeling language for the model-driven development of secure, distributed systems based on the Unified Modeling Language (UML). Our approach is based on role-based access control with additional support for specifying authorization constraints. We show how UMLcan be used to specify information related to access control in the overall design of an application and how this information can be used to automatically generate complete access control infrastructures. Our approach can be used to improve productivity during the development of secure distributed systems and the quality of the resulting systems.
862 citations
TL;DR: A novel member of the PIN family of putative auxin efflux carriers, Arabidopsis PIN4, is characterized that is localized in developing and mature root meristems and proposed a role for AtPIN4 in generating a sink for auxin below the quiescent center of the root meristsem that is essential for Auxin distribution and patterning.
814 citations
TL;DR: The GAM framework based on backfitting with linear smoothers presents some diculties when it comes to model selection and the availability of user friendly GAM software in Splus.
TL;DR: It is demonstrated that sdf-1 mRNA is expressed in locations where PGCs are found and toward which they migrate in wild-type as well as in mutant embryos in which PGC migration is abnormal, strongly suggesting that this molecule provides a key directional cue for the P GCs.
TL;DR: Dendrimers are characterized by a combination of high end-group functionality and a compact, precisely defined molecular structure that can be used in biomedical applications, for example, for the amplification or multiplication of effects on a molecular level, or to create extremely high local concentrations of drugs, molecular labels, or probe moieties.
Abstract: Dendrimers are characterized by a combination of high end-group functionality and a compact, precisely defined molecular structure. These characteristics can be used in biomedical applications, for example, for the amplification or multiplication of effects on a molecular level, or to create extremely high local concentrations of drugs, molecular labels, or probe moieties. A brief summary of the current state of the art in the field is given, and focuses on the application of dendrimers both in diagnostics as well as in therapy. In diagnostics, dendrimers that bear GdIII complexes are used as contrast agents in magnetic resonance imaging. DNA dendrimers have potential for routine use in high-throughput functional genomic analysis, as well as for DNA biosensors. Dendrimers are also being investigated for therapeutics, for example, as carriers for controlled drug delivery, in gene transfection, as well as in boron neutron-capture therapy. Furthermore, the antimicrobial activity of dendrimers has been studied.
TL;DR: A role for Reelin is revealed in controlling synaptic plasticity in the adult brain and the impairment of apoE receptor-dependent neuromodulation may contribute to cognitive impairment and synaptic loss in Alzheimer disease.
TL;DR: For the first time, hydrogel scaffolds with a designed external shape and a well-defined internal pore structure were prepared by this RP process and the versatile application potential of new hydrogels was demonstrated in cell culture.
TL;DR: The propensity of Au(-)(N) clusters to favor planar structures is correlated with strong hybridization of the atomic 5d and 6s orbitals due to relativistic effects.
Abstract: Electronic structure and bonding in anionic coinage metal clusters are investigated via density-functional calculations, focusing on an extensive set of isomers of ${\mathrm{Cu}}_{7}^{\ensuremath{-}}$, ${\mathrm{Ag}}_{7}^{\ensuremath{-}}$, and ${\mathrm{Au}}_{7}^{\ensuremath{-}}$. While the ground states of ${\mathrm{Cu}}_{7}^{\ensuremath{-}}$ and ${\mathrm{Ag}}_{7}^{\ensuremath{-}}$ are three dimensional (3D), that of ${\mathrm{Au}}_{7}^{\ensuremath{-}}$ is planar, separated from the optimal 3D isomer by 0.5 eV. The simulated thermally weighted photoabsorption spectrum of ${\mathrm{Au}}_{7}^{\ensuremath{-}}$ is dominated by planar structures, and it agrees well with the measured one. The propensity of ${\mathrm{Au}}_{N}^{\ensuremath{-}}$ clusters to favor planar structures (with $N$ as large as 13) is correlated with strong hybridization of the atomic $5d$ and $6s$ orbitals due to relativistic effects.
TL;DR: The use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA).
Abstract: The far-infrared dielectric function of a wide range of organic molecules is dominated by vibrations involving a substantial fraction of the atoms forming the molecule and motion associated with intermolecular hydrogen bond vibrations. Due to their collective nature such modes are highly sensitive to the intra- and intermolecular structure and thus provide a unique fingerprint of the conformational state of the molecule and effects of its environment. We demonstrate the use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared (0.5-4.0 THz) dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA). We observe numerous distinct spectral features with large differences between the molecules in both frequency-dependent absorption coefficient and index of refraction. Assisted by results from density-functional calculations we interpret the origin of the observed resonances as vibrations of hydrogen bonds between the molecules.
TL;DR: An interneuron network model based on experimentally determined properties was able to generate oscillatory activity with higher coherence over a broad range of frequencies (20–110 Hz), and high coherence and flexibility in frequency control emerge from the combination of synaptic properties, network structure, and electrical coupling.
Abstract: Networks of GABAergic interneurons are of critical importance for the generation of gamma frequency oscillations in the brain. To examine the underlying synaptic mechanisms, we made paired recordings from “basket cells” (BCs) in different subfields of hippocampal slices, using transgenic mice that express enhanced green fluorescent protein (EGFP) under the control of the parvalbumin promoter. Unitary inhibitory postsynaptic currents (IPSCs) showed large amplitude and fast time course with mean amplitude-weighted decay time constants of 2.5, 1.2, and 1.8 ms in the dentate gyrus, and the cornu ammonis area 3 (CA3) and 1 (CA1), respectively (33–34°C). The decay of unitary IPSCs at BC–BC synapses was significantly faster than that at BC–principal cell synapses, indicating target cell-specific differences in IPSC kinetics. In addition, electrical coupling was found in a subset of BC–BC pairs. To examine whether an interneuron network with fast inhibitory synapses can act as a gamma frequency oscillator, we developed an interneuron network model based on experimentally determined properties. In comparison to previous interneuron network models, our model was able to generate oscillatory activity with higher coherence over a broad range of frequencies (20–110 Hz). In this model, high coherence and flexibility in frequency control emerge from the combination of synaptic properties, network structure, and electrical coupling.
TL;DR: In this paper, the full-length 14-kb transcript of DNAH5 was characterized in individuals with primary ciliary dyskinesia (PCD) with randomization of LR asymmetry.
Abstract: Primary ciliary dyskinesia (PCD, MIM 242650) is characterized by recurrent infections of the respiratory tract due to reduced mucociliary clearance and by sperm immobility. Half of the affected offspring have situs inversus (reversed organs), which results from randomization of left-right (LR) asymmetry. We previously localized to chromosome 5p a PCD locus containing DNAH5, which encodes a protein highly similar to the Chlamydomonas gamma-dynein heavy chain. Here we characterize the full-length 14-kb transcript of DNAH5. Sequence analysis in individuals with PCD with randomization of LR asymmetry identified mutations resulting in non-functional DNAH5 proteins.
TL;DR: The emergence of partially demethylated epigenotypes and re-establishment of normal p15 protein expression following the initial decitabine courses implicate pharmacologic demethylation as a possible mechanism resulting in hematologic response in MDS.
TL;DR: The results suggest that each connected L4 spiny neurone produces a weak but reliable EPSP in the pyramidal cell, implying that transmission of signals to layer 2/3 is likely to have a high threshold requiring simultaneous activation of many L4 neurons, and postsynaptic glutamate receptors act as a gate for the lateral spread of excitation in layer 1/3.
Abstract: Whole-cell voltage recordings were obtained from 64 synaptically coupled excitatory layer 4 (L4) spiny neurones and L2/3 pyramidal cells in acute slices of the somatosensory cortex ('barrel' cortex) of 17- to 23-days-old rats. Single action potentials (APs) in the L4 spiny neurone evoked single unitary EPSPs in the L2/3 pyramidal cell with a peak amplitude of 0.7 +/- 0.6 mV. The average latency was 2.1 +/- 0.6 ms, the rise time was 0.8 +/- 0.3 ms and the decay time constant was 12.7 +/- 3.5 ms. The percentage of failures of an AP in a L4 spiny neurone to evoke a unitary EPSP in the L2/3 pyramidal cell was 4.9 +/- 8.8 % and the coefficient of variation (c.v.) of the unitary EPSP amplitude was 0.27 +/- 0.13. Both c.v. and percentage of failures decreased with increased average EPSP amplitude. Postsynaptic glutamate receptors (GluRs) in L2/3 pyramidal cells were of the N-methyl-D-aspartate (NMDA) receptor (NMDAR) and the non-NMDAR type. At -60 mV in the presence of extracellular Mg2+ (1 mM), 29 +/- 15 % of the EPSP voltage-time integral was blocked by NMDAR antagonists. In 0 Mg2+, the NMDAR/AMPAR ratio of the EPSC was 0.50 +/- 0.29, about half the value obtained for L4 spiny neurone connections. Burst stimulation of L4 spiny neurones showed that EPSPs in L2/3 pyramidal cells depressed over a wide range of frequencies (1-100 s(-1) ). However, at higher frequencies (30 s(-1)) EPSP summation overcame synaptic depression so that the summed EPSP was larger than the first EPSP amplitude in the train. The number of putative synaptic contacts established by the axonal collaterals of the L4 projection neurone with the target neurone in layer 2/3 varied between 4 and 5, with an average of 4.5 +/- 0.5 (n = 13 pairs). Synapses were established on basal dendrites of the pyramidal cell. Their mean geometric distance from the pyramidal cell soma was 67 +/- 34 microm (range, 16-196 microm). The results suggest that each connected L4 spiny neurone produces a weak but reliable EPSP in the pyramidal cell. Therefore transmission of signals to layer 2/3 is likely to have a high threshold requiring simultaneous activation of many L4 neurons, implying that L4 spiny neurone to L2/3 pyramidal cell synapses act as a gate for the lateral spread of excitation in layer 2/3.
TL;DR: The beta-barrels are suitable objects for channel engineering, because the structures are simple and because many of these proteins can be produced into inclusion bodies and recovered therefrom in the exact native conformation.
TL;DR: In general, Mx GTPases appear to detect viral infection by sensing nucleocapsid‐like structures and are trapped and sorted to locations where they become unavailable for the generation of new virus particles.
Abstract: Mx proteins are interferon-induced GTPases that belong to the dynamin superfamily of large GTPases. Similarities include a high molecular weight, a propensity to self-assemble, a relatively low affinity for GTP, and a high intrinsic rate of GTP hydrolysis. A unique property of Mx GTPases is their antiviral activity against a wide range of RNA viruses, including bunya- and orthomyxoviruses. The human MxA GTPase accumulates in the cytoplasm of interferon-treated cells, partly associating with the endoplasmic reticulum. In the case of bunyaviruses, MxA interferes with transport of the viral nucleocapsid protein (N) to the Golgi compartment, the site of virus assembly. In the case of Thogoto virus (an orthomyxovirus), MxA prevents the incoming viral nucleocapsids from being transported into the nucleus, the site of viral transcription and replication. In both cases, the GTP-binding and carboxy-terminal effector functions of MxA are required for target recognition. In general, Mx GTPases appear to detect viral infection by sensing nucleocapsid-like structures. As a consequence, these viral components are trapped and sorted to locations where they become unavailable for the generation of new virus particles.
TL;DR: It is shown that Runx3‐deficient mice develop severe limb ataxia due to disruption of monosynaptic connectivity between intra spinal afferents and motoneurons, and the underlying cause is a loss of DRG proprioceptive neurons.
Abstract: The RUNX transcription factors are important regulators of linage-specific gene expression in major developmental pathways. Recently, we demonstrated that Runx3 is highly expressed in developing cranial and dorsal root ganglia (DRGs). Here we report that within the DRGs, Runx3 is specifically expressed in a subset of neurons, the tyrosine kinase receptor C (TrkC) proprioceptive neurons. We show that Runx3-deficient mice develop severe limb ataxia due to disruption of monosynaptic connectivity between intra spinal afferents and motoneurons. We demonstrate that the underlying cause of the defect is a loss of DRG proprioceptive neurons, reflected by a decreased number of TrkC-, parvalbumin- and β-galactosidase-positive cells. Thus, Runx3 is a neurogenic TrkC neuron-specific transcription factor. In its absence, TrkC neurons in the DRG do not survive long enough to extend their axons toward target cells, resulting in lack of connectivity and ataxia. The data provide new genetic insights into the neurogenesis of DRGs and may help elucidate the molecular mechanisms underlying somatosensory-related ataxia in humans.
TL;DR: In this article, a coherent set of principles for integrating instructional explanations into learning via self-explanations was developed, implemented, and tested, and the results showed that the instructional explanations had a positive effect on learning, at least under certain conditions.
TL;DR: It is concluded that OH fulfils basic criteria for a wall-loosening factor acting in auxin-mediated elongation growth of plant species with widely differing cell-wall polysaccharide compositions.
Abstract: Hydroxyl radicals (OH) are capable of unspecifically cleaving cell-wall polysaccharides in a site-specific reaction. I investigated the hypothesis that cell-wall loosening underlying the elongation growth of plant organs is controlled by apoplastically produced OH attacking load-bearing cell-wall matrix polymers. Isolated cell walls (operationally, frozen/thawed, abraded segments from coleoptiles or hypocotyls, respectively) from maize, cucumber, soybean, sunflower or Scots pine seedlings were pre-loaded with catalytic Cu or Fe ions and then incubated in a mixture of ascorbate + H 2 O 2 for generating OH in the walls. This treatment induced irreversible wall extension (creep) in walls stretched in an extensiometer. The reaction could be promoted by acid pH and inhibited by several OH scavengers. Generation of OH by the same reaction in living coleoptile or hypocotyl segments caused elongation growth. Auxin-induced elongation growth of maize coleoptiles could be inhibited by OH scavengers. Auxin promoted the production of superoxide radicals (O 2 - ), an OH precursor, in the growth-controlling outer epidermis of maize coleoptiles. It is concluded that OH fulfils basic criteria for a wall-loosening factor acting in auxin-mediated elongation growth of plant species with widely differing cell-wall polysaccharide compositions.
TL;DR: The incidence of soccer injuries can be reduced by preventive interventions, especially in low skill level youth teams, and coaches and players need better education regarding injury prevention strategies and should include such interventions as part of their regular training.
Abstract: Background:Risk factors for soccer injuries and possibilities for prevention have been discussed by several authors, but only a few have investigated the effectiveness of preventive interventions.Purpose:The aim of the present study was to evaluate the effects of a prevention program on the incidence of soccer injuries in male youth amateur players.Study Design:Prospective controlled intervention study.Methods:Seven soccer teams took part in a prevention program that focused on education and supervision of coaches and players, while seven other teams were instructed to train and play soccer as usual. Over 1 year all injuries were documented weekly by physicians. Complete weekly injury reports were available for 194 players.Results:The incidence of injury per 1000 hours of training and playing soccer was 6.7 in the intervention group and 8.5 in the control group, which equates to 21% fewer injuries in the intervention group. The greatest effects were observed for mild injuries, overuse injuries, and injuri...
TL;DR: A hypothesis is developed that trans-lycopene or a trans-allycopene derivative acts as an inductor in a kind of feedback mechanism stimulating endogenous carotenogenic genes in rice endosperm.
Abstract: To obtain a functioning provitamin A (beta-carotene) biosynthetic pathway in rice endosperm, we introduced in a single, combined transformation effort the cDNA coding for phytoene synthase (psy) and lycopene beta-cyclase (beta-lcy) both from Narcissus pseudonarcissus and both under the control of the endosperm-specific glutelin promoter together with a bacterial phytoene desaturase (crtI, from Erwinia uredovora under constitutive 35S promoter control). This combination covers the requirements for beta-carotene synthesis and, as hoped, yellow beta-carotene-bearing rice endosperm was obtained in the T(0)-generation. Additional experiments revealed that the presence of beta-lcy was not necessary, because psy and crtI alone were able to drive beta-carotene synthesis as well as the formation of further downstream xanthophylls. Plausible explanations for this finding are that these downstream enzymes are constitutively expressed in rice endosperm or are induced by the transformation, e.g., by enzymatically formed products. Results using N. pseudonarcissus as a model system led to the development of a hypothesis, our present working model, that trans-lycopene or a trans-lycopene derivative acts as an inductor in a kind of feedback mechanism stimulating endogenous carotenogenic genes. Various institutional arrangements for disseminating Golden Rice to research institutes in developing countries also are discussed.
TL;DR: It is demonstrated that the distributed-order time fractional diffusion equation describes the subdiffusion random process that is subordinated to the Wiener process and whose diffusion exponent decreases in time (retarding sub Diffusion).
Abstract: We propose diffusionlike equations with time and space fractional derivatives of the distributed order for the kinetic description of anomalous diffusion and relaxation phenomena, whose diffusion exponent varies with time and which, correspondingly, cannot be viewed as self-affine random processes possessing a unique Hurst exponent. We prove the positivity of the solutions of the proposed equations and establish their relation to the continuous-time random walk theory. We show that the distributed-order time fractional diffusion equation describes the subdiffusion random process that is subordinated to the Wiener process and whose diffusion exponent decreases in time (retarding subdiffusion). This process may lead to superslow diffusion, with the mean square displacement growing logarithmically in time. We also demonstrate that the distributed-order space fractional diffusion equation describes superdiffusion phenomena with the diffusion exponent increasing in time (accelerating superdiffusion).
TL;DR: Investigating the expression of typical osteoblast‐related genes by human bone marrow stromal cells provides evidence that mRNA levels of BMP‐2, BSP, and OP, quantified using real‐time RT‐PCR, can be used as markers to monitor the extent of BMSC osteogenic differentiation in vitro.
Abstract: We developed and used real-time RT-PCR assays to investigate how the expression of typical osteoblast-related genes by human bone marrow stromal cells (BMSC) is regulated by (i) the culture time in medium inducing osteogenic differentiation and (ii) the previous expansion in medium enhancing cell osteogenic commitment. BMSC from six healthy donors were expanded in medium without (CTR) or with fibroblast growth factor-2 and dexamethasone (FGF/Dex; these factors are known to increase BMSC osteogenic commitment) and further cultivated for up to 20 days with ascorbic acid, beta-glycerophosphate and dexamethasone (these factors are typically used to induce BMSC osteogenic differentiation). Despite a high variability in the gene expression levels among different individuals, we identified the following statistically significant patterns. The mRNA levels of bone morphogenetic protein-2 (BMP-2), bone sialo protein-II (BSP), osteopontin (OP) and to a lower extent cbfa-1 increased with culture time in osteogenic medium (OM), both in CTR- and FGF/Dex-expanded BMSC, unlike levels of alkaline phosphatase, collagen type I, osteocalcin, and osteonectin. After 20 days culture in OM, BMP-2, BSP, and OP were more expressed in FGF/Dex than in CTR-expanded BMSC (mRNA levels were, respectively, 9.5-, 14.9-, and 5.8-fold higher), unlike all the other investigated genes. Analysis of single-colony-derived strains of BMSC further revealed that after 20 days culture in OM, only a subset of FGF/Dex-expanded clones expressed higher mRNA levels of BMP-2, BSP, and OP than CTR-expanded clones. In conclusion, we provide evidence that mRNA levels of BMP-2, BSP, and OP, quantified using real-time RT-PCR, can be used as markers to monitor the extent of BMSC osteogenic differentiation in vitro; using those markers, we further demonstrated that only a few subpopulations of BMSC display enhanced osteogenic differentiation following FGF/Dex expansion.