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Biomedical subjects

J Roos

Publications and source records attributed to J Roos.

At least 19 recordsLinked to original sources
PubMed2006

Should human chondrocytes fly? The impact of electromagnetic irradiation on chondrocyte viability and implications for their use in tissue engineering.

A significant logistic factor as to the successful clinical application of the autologous tissue engineering concept is efficient transportation: the donor cells need to be delivered to tissue processing facilities which in most cases requires air transportation. This study was designed to evaluate how human chondrocytes react to X-ray exposure. Primary cell cultures were established, cultured, incubated and exposed to different doses and time periods of radiation. Subsequently, quantitative cell proliferation assays were done and qualitative evaluation of cellular protein production were performed. Our results show that after irradiation of chondrocytes with different doses, no significant differences in terms of cellular viability occurred compared with the control group. These results were obtained when chondrocytes were exposed to luggage transillumination doses as well as exposure to clinically used radiation doses. Any damage affecting cell growth or quality was not observed in our study. However, information about damage of cellular DNA remains incomplete.

Apoptosis↗
PubMed2005

[Osteofluorosis caused by excess use of toothpaste].

BACKGROUND: Osteofluorosis is caused by chronic fluoride intoxication. Fluoride is used in toothpaste for the prevention of dental caries, and dental fluorosis has often been reported among children and attributed to ingestion of fluoride toothpaste. We report a case of chronic fluoride intoxication caused by excess use of toothpaste in an adult. CASE: A 45-year-old woman consulted a rheumatologist for painful swelling of the fingers, phalangeal rather than articular. She also had brown staining on her teeth. Radiography of the hands showed periosteal apposition on the phalanges. Further work-up ruled out tumoral or thyroid causes. Laboratory tests showed elevated fluoride levels in the blood (50.9 micromol/L, normal<1.5 micromol/L) and in the urine (721 micromol/L, normal<46 micromol/L). On questioning, we found only one cause for chronic fluoride intoxication: excess and unusual use of toothpaste. The patient brushed her teeth 18 times a day and swallowed the toothpaste, because she liked the taste. She consumed a tube of toothpaste every 2 days, thereby swallowing 68.5 mg of fluoride every day. Suspecting fluorosis from toothpaste, we asked the patient to use a toothpaste without fluoride. Sixteen weeks later, the pain had ceased, and laboratory tests showed massively reduced but still elevated fluoride levels in the blood (6.9 micromol/L) and urine (92.7 micromol/L). CONCLUSION: In this rare case of fluoride intoxication, misuse of a normally innocuous product caused osteofluorosis.

Bone Diseases↗
PubMed2004

Direct observation of the oxygen isotope effect on the in-plane magnetic field penetration depth in optimally doped YBa2Cu3O7-delta.

We report the first direct observation of the oxygen-isotope ((16)O/(18)O) effect on the in-plane penetration depth lambda(ab) in a nearly optimally doped YBa(2)Cu(3)O(7-delta) film using the novel low-energy muon-spin rotation technique. Spin-polarized low-energy muons are implanted in the film at a known depth z beneath the surface and process in the local magnetic field B(z). This feature allows us to measure directly the profile B(z) of the magnetic field inside the superconducting film in the Meissner state and to make a straightforward determination of lambda(ab). A substantial isotope shift Delta lambda(ab)/lambda(ab)=2.8(1.0)% at 4 K is observed, implying that the in-plane effective supercarrier mass m*(ab) is oxygen-isotope dependent with Delta m*(ab)/m*(ab)=5.5(2.0)%. These results are in good agreement with magnetization measurements on powder samples.

Journal Article↗
PubMed2004

[Application of multislice spiral CT (MSCT) in multiple injured patients and its effect on diagnostic and therapeutic algorithms].

The initial diagnostic work-up of trauma victims with multiple injuries is currently a combination of conventional radiography (CR), ultrasound (US), and computed tomography (CT). This article reviews the diagnostic quality of the different imaging modalities regarding detection and classification of injuries. CT performs better than US in detecting traumatic lesions of abdominal parenchymal organs. Furthermore, CT is better than CR in detecting therapeutically relevant chest and bone injuries. MSCT may replace CR and US under the condition that it is faster than or at least as fast as the conventional approach to diagnose life threatening injuries. This can be achieved only by changing the work-flow for the entire trauma team including radiologist. Furthermore, certain prerequisites must be fulfilled including integration of a MSCT scanner into the emergency room. An optimized whole body CT protocol for the assessment of trauma victims using MSCT as well as a two-step algorithm for reporting the imaging findings depending on their clinical significance is presented.

Abdominal Injuries↗
PubMed2003

[Initial examination for school attendance in Mannheim: language development at initial school entry level].

INTRODUCTION: In autumn 2001 the initial examination for school attendance in Mannheim has been fundamentally reorganised. The individual examination elements had been widely standardized, the results can be evaluated by regions and a diagnosis for the early detection of legasthenia has been developed. METHODS: The testing involved repeating sentences, numbers and artificial words. This has been developed by the Pedagogical University Heidelberg. In pre-examinations in Heidelberg the results relate significantly to the subsequent results in reading and writing. PROBANDS: A total of 2,744 children (46.1% girls, 53.9% boys) aged of 5 to 7 years was seen. 71.5% of the children were German nationality. Most non-German nationalities were Turkish (15.4%) and Italian (3.6%) children. Besides the nationality the mother tongue has been also recorded. More than 96% of the children had been attending a kindergarten. For judgement of the social strata the frequency of social welfare receivers has been recorded. RESULTS: The testing results are significantly influenced by the native language and the social strata of the children. The results of children with German as native language are above those of non-Germans. Within the migrant children there are significant differences between the several nationalities. Children from a lower social strata achieved lower results. A positive effect to the language development is attributed to the attendance of a kindergarten. CONCLUSION: These results are the basis for language- and general health supporting projects in Mannheim. For the examination for school attendance in the current year the diagnostic for language development has been extended by some more aspects.

Child↗
PubMed2002

Temperature and field dependence of the anisotropy of MgB2.

The anisotropy gamma of the superconducting state of high quality single crystals of MgB2 was determined, using torque magnetometry with two different methods. The anisotropy of the upper critical field was found to be temperature dependent, decreasing from gamma approximately 6 at 15 K to 2.8 at 35 K. Reversible torque data near T(c) reveal a field dependent anisotropy, increasing nearly linearly from gamma approximately equal to 2 in zero field to 3.7 in 10 kOe. The unusual temperature dependence is a true bulk property and can be explained by nonlocal effects of anisotropic pairing and/or the k--> dependence of the effective mass tensor.

Journal Article↗
PubMed2001

Maxillary implants loaded at 3 months after insertion: results with Astra Tech implants after up to 5 years.

BACKGROUND: To date, clinical studies have mainly focused on early loading of mandibular implants. Recently, there has also been considerable interest in early loading of maxillary implants. PURPOSE: The purpose of this article is to report the outcome of maxillary implants loaded after a 3-month healing period and followed up to 5 years. MATERIALS AND METHODS: Seventeen patients (11 males and 6 females) received 44 Astra Tech implants (Mölndal, Sweden) for treatment of single-tooth (13 cases) and partial edentulism (9 cases). The patients were followed up to 5 years after implant placement: 50% of the implants were followed for 3 years and 16% have been followed throughout the observation period. Preoperatively, bone height and width were assessed on radiographs. Marginal bone loss was recorded on intraoral radiographs annually. RESULTS: No implant was lost during the observation period. The average marginal bone loss was 0.5 +/- 0.7 mm after 1 year, 0.6 +/- 0.7 mm after 3 years, and 0.9 +/- 1.6 mm after 5 years. There were no soft-tissue or prosthetic failures recorded during the observation period. CONCLUSION: Early loading of Astra Tech implants was highly successful in maxillary partial and single-tooth cases followed up to 5 years in function.

Adult↗
PubMed2001

Expression of TCL1 in hematologic disorders.

OBJECTIVE: TCL1, MTCP1 and TCL1b are three members of a new family of oncogenes that are expressed in T cell leukemias of ataxia telangiectasia patients (T-PLL, T-CLL). TCL1 is located at 14q32.1 and activated by juxtaposition to the alpha/delta-locus at 14q11 or beta-locus at 7q35 of the T cell receptor during the reciprocal translocations t(14;14)(q11;q32), t(7;14)(q35;q32), or inversion inv(14)(q11;q32). TCL1 encodes a predominantly cytoplasmic protein of 114 aa (14 kD) of unknown function. Recent studies suggest that TCL1 promotes cell survival rather than stimulating cell proliferation, as previously proposed. METHODS: In an attempt to clarify the contexts in which TCL1 is expressed, we investigated TCL1 expression in 114 lymphoma and leukemia patients by Northern blot, RT-PCR and immunohistochemistry. RESULTS: TCL1 expression is restricted to lymphoid cells, and is found in neoplastic (T and B cell neoplasms, and Hodgkin's disease) and nonneoplastic proliferations (reactive lesions). Out of 114 cases, 18 neoplasms of myeloid and 4 cases of epithelial origin were TCL1-negative. In lesions of the lymphoid system, both low- and high-grade lymphomas were found to express TCL1. CONCLUSIONS: We propose that TCL1 expression especially in high-grade B cell non-Hodgkin's lymphomas might interfere with B cell differentiation and promote the transition from low- to high-grade lymphoma.

Blotting, Northern↗
PubMed2000

Charge degree of freedom and the single-spin fluid model in YBa2Cu4O8

We present a 17O nuclear magnetic resonance study in the stoichiometric superconductor YBa2Cu4O8. A double irradiation method enables us to show that, below around 200 K, the spin-lattice relaxation rate of plane oxygen is not only driven by magnetic fluctuations, but also significantly by quadrupolar fluctuations, i. e., low-frequency charge fluctuations. In the superconducting state, on lowering the temperature, the quadrupolar relaxation diminishes faster than the magnetic one. These findings show that, with the opening of the spin pseudogap, a charge degree of freedom of mainly oxygen character is present in the electronic low-energy excitation spectrum.

Journal Article↗
PubMed2000

Separation of quadrupolar and magnetic contributions to spin-lattice relaxation in the case of a single isotope

We present a NMR pulse double-irradiation method which allows one to separate magnetic from quadrupolar contributions in the spin-lattice relaxation. The pulse sequence fully saturates one transition while another is observed. In the presence of a ||Deltam || = 2 quadrupolar contribution, the intensity of the observed line is altered compared to a standard spin-echo experiment. We calculated analytically this intensity change for spins I = 1, 32, 52, thus providing a quantitative analysis of the experimental results. Since the pulse sequence we used takes care of the absorbed radiofrequency power, no problems due to heating arise. The method is especially suited when only one NMR sensitive isotope is available. Different cross-checks were performed to prove the reliability of the results obtained. The applicability of this method is demonstrated by a study of the plane oxygen (17)O (I = 52) in the high-temperature superconductor YBa(2)Cu(4)O(8): the (17)O spin-lattice relaxation rate consists of magnetic as well as quadrupolar contributions. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Drosophila Futsch/22C10 is a MAP1B-like protein required for dendritic and axonal development.

Here we report the description of the Drosophila gene futsch, which encodes a protein recognized by the monoclonal antibody 22C10 that has been widely used to visualize neuronal morphology and axonal projections. The Futsch protein is 5327 amino acids in length. It localizes to the microtubule compartment of the cell and associates with microtubules in vitro. The N- and C-terminal domains of Futsch are homologous to the vertebrate MAP1B microtubule-associated protein. The central domain of the Futsch protein is highly repetitive and shows sequence similarity to neurofilament proteins of which no Drosophila homologs have been reported. Loss-of-function analyses demonstrate that during embryogenesis Futsch is necessary for dendritic and axonal growth. Gain-of-function analyses demonstrate a functional interaction of Futsch with other MAPs. In addition, we show that during development, futsch expression is negatively regulated in nonneuronal tissues.

Aging↗
PubMed2000

Drosophila Futsch regulates synaptic microtubule organization and is necessary for synaptic growth.

We present evidence that Futsch, a novel protein with MAP1B homology, controls synaptic growth at the Drosophila neuromuscularjunction through the regulation of the synaptic microtubule cytoskeleton. Futsch colocalizes with microtubules and identifies cytoskeletal loops that traverse the lateral margin of select synaptic boutons. An apparent rearrangement of microtubule loop architecture occurs during bouton division, and a genetic analysis indicates that Futsch is necessary for this process. futsch mutations disrupt synaptic microtubule organization, reduce bouton number, and increase bouton size. These deficits can be partially rescued by neuronal overexpression of a futsch MAP1B homology domain. Finally, genetic manipulations that increase nerve-terminal branching correlate with increased synaptic microtubule loop formation, and both processes require normal Futsch function. These data suggest a common microtubule-based growth mechanism at the synapse and growth cone.

Animals↗
PubMed1999

The endocytic machinery in nerve terminals surrounds sites of exocytosis.

In most models of endocytosis, the endocytic machinery is recruited from the cytoplasm by cytoplasmic tails of the plasma membrane proteins that are to be internalized. This does not appear to be true at synapses where the endocytic machinery required for synaptic vesicle recycling is localized to membrane-associated 'hot spots' [1] [2]. In Drosophila neuromuscular junctions, the multi-domain protein Dap160 is also localized to hot spots [3] and has some characteristics expected of an anchoring protein. Anchoring the endocytic machinery to the plasma membrane might help contribute to the remarkable speed of synaptic vesicle recycling [4]. Here, we report that the endocytic machinery surrounds sites that are believed to be sites of exocytosis. We propose that the radial distribution of the synaptic vesicle recycling machinery already present on the plasma membrane in unstimulated nerve terminals is a fundamental unit of pre-synaptic organization and allows the nerve terminal to extract maximum recycling efficiency out of conventional endocytic machinery.

Animals↗
PubMed1999

Syndapin I, a synaptic dynamin-binding protein that associates with the neural Wiskott-Aldrich syndrome protein.

The GTPase dynamin has been clearly implicated in clathrin-mediated endocytosis of synaptic vesicle membranes at the presynaptic nerve terminal. Here we describe a novel 52-kDa protein in rat brain that binds the proline-rich C terminus of dynamin. Syndapin I (synaptic, dynamin-associated protein I) is highly enriched in brain where it exists in a high molecular weight complex. Syndapin I can be involved in multiple protein-protein interactions via a src homology 3 (SH3) domain at the C terminus and two predicted coiled-coil stretches. Coprecipitation studies and blot overlay analyses revealed that syndapin I binds the brain-specific proteins dynamin I, synaptojanin, and synapsin I via an SH3 domain-specific interaction. Coimmunoprecipitation of dynamin I with antibodies recognizing syndapin I and colocalization of syndapin I with dynamin I at vesicular structures in primary neurons indicate that syndapin I associates with dynamin I in vivo and may play a role in synaptic vesicle endocytosis. Furthermore, syndapin I associates with the neural Wiskott-Aldrich syndrome protein, an actin-depolymerizing protein that regulates cytoskeletal rearrangement. These characteristics of syndapin I suggest a molecular link between cytoskeletal dynamics and synaptic vesicle recycling in the nerve terminal.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Neuroendocrine synaptic vesicles are formed in vitro by both clathrin-dependent and clathrin-independent pathways.

In the neuroendocrine cell line, PC12, synaptic vesicles can be generated from endosomes by a sorting and vesiculation process that requires the heterotetrameric adaptor protein AP3 and a small molecular weight GTPase of the ADP ribosylation factor (ARF) family. We have now discovered a second pathway that sorts the synaptic vesicle-associated membrane protein (VAMP) into similarly sized vesicles. For this pathway the plasma membrane is the precursor rather than endosomes. Both pathways require cytosol and ATP and are inhibited by GTPgammaS. The second pathway, however, uses AP2 instead of AP3 and is brefeldin A insensitive. The AP2-dependent pathway is inhibited by depletion of clathrin or by inhibitors of clathrin binding, whereas the AP3 pathway is not. The VAMP-containing, plasma membrane-derived vesicles can be readily separated on sucrose gradients from transferrin (Tf)-containing vesicles generated by incubating Tf-labeled plasma membrane preparations at 37 degreesC. Dynamin- interacting proteins are required for the AP2-mediated vesiculation from the plasma membrane, but not from endosomes. Thus, VAMP is sorted into small vesicles by AP3 and ARF1 at endosomes and by AP2 and clathrin at the plasma membrane.

ADP-Ribosylation Factor 1↗