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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is known that species belonging to the lowest metazoan phylum, the Porifera (sponges), do not develop tumors. Sponge cells share with tumor cells of higher animals at least one characteristic; they contain high levels of telomerase activity, suggesting that they possess a high proliferation capacity. This assumption, however, has not been substantiated experimentally. In addition, sponges show a specific bauplan, leading us to postulate that they undergo apoptosis to replace a given set of cells at a given time. In the present study, 17β-estradiol (βE2) was used as a defined agent to assess its effect on both the telomerase activity and the process of apoptosis in the marine sponge Geodia cydonium (Jameson). It was found that βE2 (100 to 500 ng ml−1) caused increased expression (i) of the heat-shock protein HSP70 (Mr=70 000), a cytoplasmic chaperone; and (ii) of the nuclear chaperone thioredoxin (TRX), a protein involved in the control of cancer cell growth. For this purpose the gene of G. cydonium encoding TRX was cloned, and the cDNA was applied for the determination of the expression. Verapamil, an inhibitor of both the mammalian multidrug resistance pump and the invertebrate multixenobiotic resistance pump, was used in co-incubation experiments with βE2 to increase the uptake of βE2. The experiments revealed that verapamil augmented the βE2 effect on the expression of the two chaperones, HSP70 and TRX. In addition, the tissue of G. cydonium underwent apoptosis, and the cells lost their telomerase activity. In parallel with the induction of the apoptotic process, the number of DNA strand breaks increased. It is concluded that βE2 displays its effect via the production of reactive oxygen species (ROS). At physiological concentrations ROS cause the expression of HSP70 and TRX, while at higher ROS levels, generated during the co-incubation period of βE2 with verapamil, the cells undergo apoptosis and lose telomerase activity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1211
    Keywords: Key words Sponges ; Geodia cydonium ; Ig-like domains ; Immune system ; Invertebrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  A cDNA encoding a receptor tyrosine kinase (RTK) was previously cloned and expressed from the marine sponge (Porifera) Geodia cydonium. In addition to the two intracellular regions characteristic for RTKs, two immunoglobulin (Ig)-like domains are found in the extracellular part of the sponge RTK. In the present study it is shown that no further Ig-like domain is present in the upstream region of the cDNA as well as of the gene hitherto known from the sponge RTK. Two different full-length cDNAs have been isolated and characterized in the present study, which possess two Ig-like domains, one transmembrane segment, and only a short intracellular part, without a TK domain. The two deduced polypeptides were preliminarily termed sponge adhesion molecules (SAM). The longer form of the SAM, GCSAML, encodes a deduced aa sequence, GCSAML, which comprises in the open reading frame 505 amino acids (aa) and has a calculated M r of 53911. The short form, GCSAMS, has 313 aa residues and an M r of 33987. The two Ig-like domains in GCSAML and GCSAMS are highly similar to the corresponding Ig-like domains in the RTKs from G. cydonium; the substitutions on both the aa and nt level are restricted to a few sites. Phylogenetic analyses revealed that the Ig-like domain 1 is similar to the human Ig lambda chain variable region, while the Ig-like domain 2 is related more closely to the human Ig heavy chain variable region. Transplantation experiments (autografting) were performed to demonstrate that the level of expression of the two new genes, GCSAML and GCSAMS, is upregulated during the self/self fusion process. Immunohistochemical analyses using antibodies raised against the two Ig-like domains demonstrate a strong expression in the fusion zone between graft and host. This finding has been supported by northern blotting experiments that revealed that especially GCSAML is strongly upregulated after autografting (up to 12-fold); the expression of GCSAMS reaches a value of 5-fold if compared with the controls. The results presented here demonstrate that the expression of the new molecules described, comprising two Ig-like domains, is upregulated during the process of autograft fusion.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Monatsschrift Kinderheilkunde 147 (1999), S. 947-950 
    ISSN: 1433-0474
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Alkoholkonsum unter Kindern und Jugendlichen ist relativ weit verbreitet, die Gefahren der Alkoholintoxikation werden dabei häufig unterschätzt [15]. Alkoholvergiftungen entstehen vorwiegend akzidentell in Unkenntnis der Wirkung des Alkohols, wobei Kinder und Jugendliche den Alkohol meist in Gruppen von Gleichaltrigen konsumieren. Der erste Alkoholkontakt der Kinder erfolgt häufig durch den sogenannten Probierkonsum im Kreis der Familie. Bei Kindern unter 6 Jahren kommen Alkoholvergiftungen in erster Linie aus Unachtsamkeit der Eltern oder durch Verwechslungen zustande. Kleinkinder unter 2 Jahren sind äußerst selten betroffen, dagegen konsumieren Kinder über 6 Jahre und Jugendliche für gewöhnlich bewußt Alkohol (besonders männliche Jugendliche) [2, 4, 17, 21, 23]. Durch Erörterung psychologischer Probleme und die Kenntnis der sozialen Verhältnisse können Risikopatienten erkannt werden, die einer Psychotherapie oder einer psychosozialen Betreuung bedürfen. Epidemiologie und psycho- soziale Faktoren
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. This paper deals with the expression of the biomarker hsp70 in the liver and kidney of the freshwater fish Oreochromis niloticus following exposure to the herbicide oxyfluorfen (Goal). Fishes were exposed to three concentrations, the 96-h LC50 (3 mg/L), the 96-h ½LC50 (1.5 mg/L), and the 96-h ¼LC50 (0.75 mg/L) of oxyfluorfen for 6, 15, and 24 days, respectively, and samples were taken at three different time periods for each concentration. The livers responded to the herbicide by an induction of the expression of both the constitutive (hsp75; Mr 75 kDa) and the inducible (hsp73; Mr 73 kDa) hsp70 proteins. In kidney, the herbicide induced a time-dependent increase in the expression of the constitutive hsp70 (hsp75) as well, but the inducible hsp70 (hsp73) required much longer incubation periods to reach maximal levels (15 and 24 days). Our results suggest that expression of hsp70 in fish is a sensitive indicator of cellular responses to herbicide exposure in the aquatic environment.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The marine sponge Suberites domuncula was used as a bioindicator to study the effects of cadmium on the occurrence of DNA strand breakage and on the induction of the expression of the stress biomarkers, heat shock protein 70 (HSP70) and glucose-regulated protein 78 (GRP78) homolog. The cDNA encoding GRP78 homolog from S. domuncula was isolated and characterized. The GRP78 cDNA has a length of 2.1 kb and displays characteristic features of the HSP70 family; it encodes an aa sequence of Mr 72,000. Exposure of S. domuncula to 1 mg/L of cadmium chloride for 24 h caused a strong (16.6-fold) increase in cadmium content to 7.7 μg/g wet weight of sponge tissue; after an incubation period of 6 days, the accumulation was 20.4-fold. The increase in cadmium content was paralleled by a transient decrease in zinc content at days 1 and 3. Exposure of S. domuncula to cadmium chloride also resulted in a marked increase in the number of DNA single strand breaks, as assessed by a recently developed fast and sensitive microplate assay. The maximum increase in DNA damage was observed after an incubation of 12 h in the presence of 1 mg/L of cadmium chloride; after longer incubation, the number of damaged sites decreased, most likely due to DNA repair. Quantitative analysis of the expression of HSP70 (Mr 73 kDa) revealed that onset of maximal levels of HSP70 depends on the concentration of cadmium chloride in the ambient seawater. Maximal induction (8.9-fold increase compared to control) of HSP70 following exposure to 1 mg/L of cadmium chloride was found after 12 h, while longer incubation periods (3–6 days) were needed to reach maximum levels of HSP70 in the presence of lower concentrations of cadmium chloride (0.1 mg/L and 0.01 mg/L). Northern blot analysis revealed that the level of the 2.0 kb sponge GRP78 homolog mRNA transiently increased under cadmium stress; the maximum increase in the presence of 0.1 mg/L of cadmium chloride was observed at day 3. Our results suggest that sponges are useful indicator organisms to assess the genotoxic risks of cadmium pollution in marine environments.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 86 (1999), S. 457-467 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Notes: MyoD/myogenin genes and neural key genes (e.g., achaete scute-C, neurogenin), are switched on which control entire sets of subordinate effector genes. In multiplying cells "cell heredity" based on an epigenetic cellular memory enables transmission of the cell type determining program from parental to daughter cells. This memory can be based on autocatalytic self-activation of cell type specific selector genes and on the enduring action of gene groups such as the Polycomb and thrithorax complexes that code for proteins which bind to DNA sequences called cellular memory modules. These modules confer permanent accessibility (potentiation) or inaccessibility (silencing) upon many different gene loci on the chromosomes.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1437-1588
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Mobility and migration pose increasing risks for the health of travellers. Prevention of such health risks, especially of infectious diseases in general and sexually transmitted infections in particular, is seen as a priority task in Germany. Since the eighties the federal agency for health education (BzgA) conceptualized and prioritized health education on travel-associated health risks and STDs. Prerequisites for successful STD prevention are:〈@Normal.lf〉█*To focus on individual independence and self-determination,〈@Normal.lf〉█*To integrate the messages into a positive valued context (health) to diminish avoidance and denial, █*To implement the messages with adequate tonality, functional information or original presentation,〈@Normal.lf〉█*Adequacy for the target groups, █*To attract a high degree of attention, but to avoid distancing (no emphasis on prostitution, sex etc.), █*To offer personal references, █*To work with positive and encouraging messages, not with fear and threats. The evaluation of the education effects shows that nowadays especially travellers with increased STD risks also show better preventive behaviors. So far condom use increased from year to year, but now this seems to level off. Therefore it is important to continue and – if possible – to intensify prevention measures for travellers. Cooperative strategies with the travel industry will become more important. At the same time the quality of travel-associated health education and information has to be improved. Mobilität und Migration: zur Notwendigkeit der Prävention von Infektionskrankheiten
    Notes: Zusammenfassung Mobilität und Migration stellen regional und global ein wachsendes Risiko für die Gesundheit reisender Menschen dar. Die Prävention solcher gesundheitlichen Gefahren erhält gerade in Deutschland einen immer höheren Stellenwert. Von besonderer Bedeutung sind die weltweit zunehmenden Infektionskrankheiten, unter denen die sexuell übertragbaren Infektionen einen hohen Anteil haben. Seit den 80er Jahren hat die Bundeszentrale für gesundheitliche Aufklärung (BZgA) die Aufklärung über reisebedingte Gesundheitsrisiken und insbesondere über sexuell übertragene Infektionen konzeptualisiert und zu einem Arbeitsschwerpunkt gemacht. Grundvoraussetzungen für erfolgreiche STD-Prävention sind: █*Fokussierung der Eigenverantwortung und Selbstbestimmung des Individuums, █*Einbettung in positiv bewertete Themenzusammenhänge (Gesundheit) zur Verminderung von Abwehr und Verleugnung, █*eine adäquate „Tonalität” der Umsetzung mit sachlicher Information oder auch origineller Darstellungsweise. Die STD-Prävention soll also zielgruppenadäquat sein, hohe Aufmerksamkeit erreichen, aber nicht zur Distanzierung führen (keine Hervorhebung von Prostitution, Sex etc.); Differenzierung für persönliche Bezüge bieten und nicht mit Angst und Drohungen, sondern positiven und ermutigenden Botschaften arbeiten. Die Evaluation der Auklärungseffekte zeigt, daß heute gerade Reisende mit erhöhtem STD-Risiko auch in erhöhtem Maße präventives Verhalten zeigen. Der bisherige jährliche Anstieg der Kondomnutzung scheint jedoch derzeit in eine Stagnation überzugehen. Die Fortsetzung und womöglich Intensivierung der Schwerpunktsetzung der Prävention bei Reisen ist deswegen wichtig. Kooperationsstrategien mit der Reiseindustrie haben dabei einen wachsenden Stellenwert. Komplementär muß die Qualität reisebezogener Gesundheitsberatung besser gesichert und gefördert werden.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 136 (1999), S. 171-192 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Continuous and discrete Fourier transforms (CFT and DFT, respectively) are used to derive a formal solution for the Fourier transforms of stresses and strains that develop in elastically homogeneous but arbitrarily eigenstrained linear-elastic bodies. The solution is then specialized to the case of a dilatorically eigenstrained cylindrical region in an infinite matrix, both of which are made of the same cubic material with the same orientation of principal axes. In the continuous case all integrations necessary for the inverse Fourier transformation can be carried out explicitly provided the material is “slightly” cubic. This results in an approximate but analytical expression for the stresses and strains in physical space. Moreover, the stress-strain fields inside of the inclusion prove to be of the Eshelby type, i.e., they are homogeneous and isotropic. The range of validity of the analytical solution is assessed numerically by means of discrete Fourier transforms (DFT). It is demonstrated that even for strongly cubic materials the stresses and strains are quite well represented by the aforementioned approximate solution. Moreover, the total elastic energy of two eigenstrained cylindrical inclusions in slightly cubic material with the same orientation of their principal axes is calculated analytically by means of CFT. The minimum of the energy is determined as a function of the relative position of the two inclusions with respect to the crystal axes and it is used to explain the formation of textures in cubic materials.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0878
    Keywords: Key words Metabotropic glutamate/GABA-like receptor ; Evolution ; Geodia cydonium (Porifera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To date, no conclusive evidence has been presented for the existence of neuronal-like elements in Porifera (sponges). In the present study, isolated cells from the marine sponge Geodia cydonium are shown to react to the excitatory amino acid glutamate with an increase in the concentration of intracellular calcium[Ca2+]i. This effect can also be observed when the compounds L-quisqualic acid (L-QA) or L-(+)-2-amino-4-phosphonobutyric acid (L-AP-4) are used. The effect of L-QA and L-AP-4, both agonists for metabotropic glutamate receptors (mGluRs), can be abolished by the antagonist of group I mGluRs, (RS)-α-methyl-4-carboxyphenylglycine. These data suggest that sponge cells contain an mGluR-like protein. A cDNA encoding rat mGluR subtype 1 has been used to identify the complete nucleotide sequence of G. cydonium cDNA coding for a 528-amino-acid-long protein (59 kDa) that displays marked overall similarity to mGluRs and to γ-amino-butyric acid B receptors. The deduced sponge polypeptide, termed putative mGlu/GABA-like receptor, displays the highest similarity to the two families of metabotropic receptors within the transmembrane segment. The N-terminal part of the sponge sequence shows similarity to mGluR4 and mGluR5. These findings suggest that the earliest evolutionary metazoan phylum, the Porifera, possesses a sophisticated intercellular communication and signaling system, as seen in the neuronal network of higher Metazoa.
    Type of Medium: Electronic Resource
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