No description available.

Eukaryotic translation initiation factor 5A (eIF-5A) is the only known cellular protein that contains the post-translationally derived amino acid, hypusine. Initially, eIF-5A was named as a translation initiation factor because of its capability to stimulate the formation of methionyl-puromycin, which mimics the first peptide bond formation during protein synthesis, under <em>in vitro</em> conditions. Subsequently, however, this proposed function of eIF-5A has been questioned because a similar effect on translation was not observed <em>in situ</em>. Moreover, eIF-5A appears not to be required for general protein synthesis. Rather, there is evidence that it facilitates the translation of specific subsets of mRNAs required for cell proliferation as well as apoptosis. <br /><br /> There are two isoforms of eIF-5A in the human genome which have designated eIF-5A1 and eIF-5A2. The objective of the present study was to gain an increased understanding of the roles of eIF-5A1 and eIF-5A2 during apoptosis and cell proliferation using human cell lines as a model system. Apoptosis was induced by treating the cells with Actinomycin D or sodium nitroprusside (SNP), which initiate programmed cell death by different mechanisms. It was observed for both normal and cancer cells that eIF-5A1 protein is up-regulated during apoptosis induced by Actinomycin D or SNP, whereas eIF-5A1 mRNA is constitutively expressed and does not change in abundance during this treatment. The up regulation of eIF-5A1 protein levels in the absence of a corresponding up-regulation in eIF-5A1 mRNA suggests that eIF-5A1 may be post-transcriptionally regulated. Moreover, eIF-5A1 protein up-regulation was stronger in normal cells than in cancer cells. By contrast, eIF-5A2 protein was below detection levels during apoptosis in both normal and cancer cells, although the corresponding transcript was detectable by semi-quantitative RT-PCR. This is attributable to inefficient translation of eIF-5A2 mRNA. <br /><br /> The effects of eIF-5A1 and eIF-5A2 on cell proliferation were examined by modulating the levels of serum in cultures of UACC-1598 cells, which are ovarian cancer cells that express high levels of both isoforms of eIF-5A. Serum starvation, which induces cell cycle arrest and ensuing apoptosis, followed by the re-addition of serum had no effect on the transcript levels of either eIF-5A1 or eIF-5A2. However, eIF-5A1 and eIF-5A2 proteins were both up-regulated within 24 hours of the initiation of serum starvation, and this coincided temporally with the onset of apoptosis as measured by TUNEL and a subsequent decline in viable cells. <br /><br /> The data indicate that eIF-5A1 and eIF-5A2 are both post-transcriptionally regulated and that they have functionally redundant roles in apoptosis.

No description available.

No description available.

No description available.

Introduction/purpose: Recovery from muscle damage involves a type of programmed cell death known as apoptosis. Damage Associated Molecular Patterns (DAMPs) are released after muscle damage and may cause premature apoptosis in monocytes infiltrating the damaged site. This may alter the time course of events towards recovery. Therefore, the purpose of this study was to investigate if downhill running causes a change in the susceptibility of monocytes to apoptosis. Methods: Participants (5 male, 6 female) completed a downhill running protocol consisting of 6-5 minute bouts at a speed of 6-9mph on a -15% grade treadmill. Venous blood samples were collected immediately pre-exercise (PRE), in addition to 4 -h, 24 -h and 48 -h post-exercise. Creatine kinase (CK) was measured to give an indication of muscle damage. Monocytes were analyzed by flow cytometry for expression of multicaspase and annexin v reagent was used to detect changes in the plasma membrane. A MILLIPLEX MAP human early apoptosis magnetic bead 7-plex kit (EMD Millipore, Billerica, MA) was used to assess the relative concentration of phosphorylated protein kinase B (Akt), Bcl-2 associated death promoter (BAD), B cell lymphoma-2 (Bcl-2), active caspase-8, active caspase-9, c jun N terminal kinase (JNK) and tumor protein p53 by Luminex multiplex assay. Results: CK peaked at 24- h. Monocytes showed greater expression of multicaspase at 24 –h and 48 -h than at PRE. Bcl-2, p53 and caspase-8 were all significantly greater at 24 –h than at PRE. Conclusion: Downhill running did alter the apoptotic response of monocytes and therefore may be important in the recovery process from muscle damage.

Call number: LD2668 .T4 1986 M37 / Master of Science / Human Nutrition

The study of foraging behaviour in plant-pollinator mutualisms has benefitted from the use of artificial flowers to manipulate floral display traits and the delivery of floral rewards. The two most common floral rewards are pollen and nectar; some pollinators, such as bees, are obliged to collect both for survival and reproduction. While flexible designs for artificial flowers providing nectar rewards abound, useful designs for artificial flowers that dispense pollen are few. This disparity mirrors a heavy emphasis on nectar collection in the study of pollinator foraging behaviour. In this study we describe a novel, easily constructed and modifiable artificial flower that dispenses flexible amounts of pollen via an ‘anther’ composed of a chenille stem. Using controlled lab assays, we show that more pulverized honeybee pollen is collected by bumblebee (Bombus impatiens) workers at chenille stem feeders than at dish-type feeders. We suggest that the paucity of studies examining pollinator cognition in the context of pollen rewards might be partly remedied if researchers had access to inexpensive and easily adjustable pollen-offering surrogate flowers.

CHIKV is the prototype of Alphaviruses and it causes an acute febrile illness with rash, severely painful arthralgias, and sometimes arthritis. While CHIKV has first been identified in the 1950s in Africa, recent outbreaks of CHIKV in the islands of the Indian Ocean and particular in Italia have re-drawn attention to CHIKV. In the past CHIKV disease was considered self-limiting and non-fatal. However, a number of deaths on Reunion (Anonym, 2006) during the outbreak, which was affected directly or indirectly by CHIKV, have changed this view. To defeat CHIKV outbreaks diagnostic tools and anti CHIKV therapies are urgently needed. In this thesis, we generated tools to investigate CHIKV at the molecular level by serological tests. CHIKV was isolated from a German woman who was infected during her holidays on the Mauritius Island. To characterize this viral isolate the complete viral genome was amplified by PCR and molecular cloned. In order to analyse antibody responses of infected individuals some of the structural and non-structural genes were subcloned in bacterial expression vectors. The NSP2, proteinase, capsid, E1 and E2 were subsequently expressed in E.coli using purified successfully. In this thesis, the structural proteins were used to develop a screening test for anti-CHIKV antibodies in patient derived serum samples. These tests were evaluated with pre-characterized anti-CHIKV sera (30 samples) obtained from the BNI Hamburg and 100 serum samples from German blood donors used as negative controls. Immunoblotting analysis revealed that up to 77% of precharacterised positive sera could recognize the recombinant proteins and there were no detectable reactivity of CHIKV-negative German donor sera. The recombinant proteins were also recognized by 71.4% of positive sera in the newly established ELISA. In order to go further in analyses of the results, an in house IFA was performed. Positive sera (21 samples) were used. The results showed that all of them reacted positive, but this assay was less sensitive than the IFA from BNI. In comparison with the IFA result from BNI Hamburg, the results were not congruent in all test performed. This could be due to various drawbacks of the tests. A cross reaction in Alphaviruses and the different strains are mentioned as well as the denatured forms of the structural proteins. Besides the main structural proteins (E1, E2 and C), other proteins such as non-structural proteins, uncleaved precursor proteins could participate in the different outcomes of serological assays. In order to go further in the CHIKV diagnoses, the CHIKV recombinant proteins were applied to screen the anti-CHIKV antibodies in the Vietnamese population, who are considered to live in the high risk regions. In serological tests, 158 sera of Vietnamese donors were incubated with the recombinant proteins or the fixed CHIKV infected cells. The results showed that 24% of Vietnamese donor sera recognized the recombinant proteins in immunoblot assay, while 36% scored positive in the ELISA assay. In IFA, the sera considered positive were 11.4%. While some discrepancies in serological tests were found, these results showed that the ratio of CHIKV-positive sera seem to be equal to the other regions in the world, which are affected by CHIKV. It is suggested that CHIKV infection in Vietnam has been repeatedly misdiagnosed. This study cohort consisted only of samples originating from Hanoi area of Northern Vietnam, thus, future studies should expand to include samples from other Vietnam areas. To do this the various subtypes of the virus in the different regions should be isolated and the sequences of these viruses should be well characterized.

Beim Zigarettenrauchen als der häufigsten Form des Tabakkonsums stellt das respiratorische Epithel des oberen und unteren Aerodigestivtraktes das primäre Kontaktorgan der zyto- und genotoxischen Inhaltsstoffe dar. Nikotin, das Hauptalkaloid des Tabaks, ruft nicht nur eine starke Abhängigkeit hervor, sondern kann in Anbetracht früherer Studien auch zum Tabak assoziierten Krebsrisiko beitragen. Neben tumorproliferativen Effekten wie etwa der Angioneogenese, der Zellproliferation oder einer Apoptoseinhibition ist die Rolle der tumorinitiierenden Wirkung von Nikotin durch eine direkte Schädigung der DNA noch unzureichend untersucht. Ziele dieser experimentellen Arbeit waren deshalb, Nikotin induzierte DNA-Schäden an frisch isolierten sowie rekultivierten humanen Lymphozyten mit Hilfe des alkalischen Einzelzell-Mikrogelelektrophorese (Comet) Assays darzustellen, den Nachweis dieser Schäden durch Koinkubation mit dem Reparaturenzyminhibitor Aphidicolin (APC) zu sensitivieren sowie oxidativ geschädigte Basen durch die Formamidopyrimidin-Glykosylase (Fpg) aufzuzeigen. Durch Koinkubation mit Epibatidin, einem Subtyp spezifischen und kompetitiven Agonisten am nikotinergen Acetylcholinrezeptor (nAChR), wurde die Rolle der rezeptorvermittelten Mechanismen Nikotin induzierter DNA-Schäden an Lymphozyten und nasalen Mukosazellen untersucht. Auch der Frage, ob Rauchen zu einer erhöhten basalen Schädigung an nasalen Mukosazellen führe, wurde nachgegangen. Nach der Zellisolierung der humanen nasalen Schleimhautzellen und peripheren Lymphozyten erfolgte zum Ausschluss zytotoxischer Effekte jeweils vor und nach der einstündigen Fremdstoffinkubation mit Nikotin (1 µM bis 1000 µM), APC (2,5 µg/ml), Epibatidin (1 µM bis 100 µM) und MMS (100 µM) die Bestimmung der Zellvitalität mit dem Trypanblau-Ausschlusstest. Durch Inkubation mit Fpg nach der Lyse zellulärer Membranen erfolgte die Augmentation oxidativ geschädigter Basen. Potentielle DNA-Schäden in Form von Einzelstrangbrüchen und alkalilabilen Stellen der DNA wurden mit dem Comet Assay erfasst. An frisch isolierten Lymphozyten konnte nach ein-stündiger Inkubation mit Nikotin ab 100 µM ein signifikanter DNA-Schaden festgestellt werden. Mit dem Einsatz von Fpg kam es ab 10 µM Nikotin zu einem signifikanten Anstieg der DNA-Fragmentierung. An rekultivierten Lymphozyten konnte nach Kryokonservierung bei einstündiger Inkubation mit Nikotin bereits ab 1 µM eine signifikante DNA-Schädigung nachgewiesen werden, die sich ebenfalls bei Koinkubation mit APC ab 1 µM darstellte. Durch Koinkubation von Nikotin (1000 µM) mit Epibatidin in aufsteigender Konzentration konnte an frisch isolierten Lymphozyten nur in einer Konzentration (10 µM) die Nikotin induzierte DNA-Fragmentierung gesenkt werden. Hierbei zeigte Epibatidin selbst einen DNA-Schaden in niedriger Konzentration (1 µM und 10 µM). An nasalen Mukosazellen konnte der Nikotin induzierte DNA-Schaden durch die Koinkubation mit Epibatidin nicht gesenkt werden. Auch an nasaler Mukosa rief Epibatidin ab 1 µM einen signifikanten DNA-Schaden hervor. Bezüglich einer Einflussgröße durch das Rauchen auf die Ergebnisse im Comet Assay konnte kein Unterschied der basalen als auch der durch Nikotin induzierten DNA-Fragmentierung zwischen der Gruppe der Raucher und Nichtraucher festgestellt werden. Nikotin verursachte bereits bei einer einstündigen Expositionsdauer DNA-Schäden an humanen Lymphozyten und nasalen Mukosazellen. Der Nachweis oxidativ geschädigter Basen an Lymphozyten zeigt auf eine Generierung von reaktiven Sauerstoffspezies (ROS) durch Nikotin hin. Die Aktivierung des homomeren α7 nAChR durch Nikotin soll hierbei eine wichtige Rolle als Auslöser der intrazellulären Signaltransduktion der Radikalbildung spielen. Epibatidin als ein starker Agonist am α7 Rezeptor führte bereits in geringen Konzentrationen zu einer signifikanten DNA-Fragmentierung. Bei fehlender Reparatur dieser DNA-Schäden und einer ausbleibenden Elimination der geschädigten Zelle können diese Mutationen akkumulieren und zur Tabak assoziierten Krebsentstehung beitragen. Eine Substitutionstherapie mit Nikotin zur Raucherentwöhnung muss bei solchen Ergebnissen äußerst kritisch betrachtet werden. / Respiratory epithelia of the upper and lower aero digestive tract are in first contact with cyto- and genotoxic components of tobacco smoke. Nicotine, being the main alkaloid of tobacco, is responsible for addiction to tobacco and contributes to tobacco carcinogenesis, too. While mechanisms of tumor proliferation caused by nicotine, such as stimulation of angiogenesis and cell proliferation or inhibition of apoptosis, are well accepted, the role of direct DNA damage by nicotine as a potentially tumor initiating factor is in focus of the present study. This experimental study demonstrates DNA damage in freshly isolated and cryo-preserved human lymphocytes after exposure to nicotine with the alkaline single-cell microgel electrophoresis (comet) assay. Co-incubations with aphidicolin (APC), an inhibitor of repair enzymes, and formamidopyrimidine-glycosylase (Fpg), an enzyme to detect oxidative damaged bases, were performed. Epibatidine as a subtype-specific and competitive agonist of the nicotinic acetylcholine receptor (nAChR) correspondent to nicotine was implemented to evaluate the role of receptor associated mechanisms of DNA damage. Furthermore, the influence of the smoking-status on the DNA damage of nasal mucosa cells was evaluated. Cytotoxic effects were investigated before and after one hour of exposure to nicotine (1 µM to 1000 µM), APC (2,5 µg/ml), epibatidine (1 µM to 100 µM) and methyl methane sulfonate as control (100 µM) in the trypan blue exclusion test. After lysis of cellular membranes, oxidative damaged bases of DNA were detected by incubation with Fpg. DNA damage like single strand brakes and alkali labile sites of DNA were investigated with the aid of the comet assay. Freshly isolated lymphocytes showed at 100 µM nicotine a significant DNA damage. Applying Fpg, a significant increase in DNA fragmentation could already be detected at 10 µM nicotine. Cryopreserved lymphocytes showed a significant DNA damage at 1 µM nicotine both with and without the co-incubation of APC. The co-incubation of 1000 µM nicotine with epibatidine showed in a single concentration (10 µM) a reduction of nicotine induced DNA damage in lymphocytes. Epibatidine itself caused DNA damage at lower concentrations (1 µM and 10 µM) in lymphocytes. In nasal mucosa cells epibatidine did not reduce the nicotine induced DNA damage but caused itself DNA damage at 1 µM. The smoking-status of the participants had no influence on basal and nicotine induced DNA fragmentation. Nicotine induced DNA damage to cells of human blood and nasal mucosa just after one hour of exposure. The evidence of oxidative damaged bases of DNA in lymphocytes shows the development of reactive oxygen species (ROS) by nicotine. The activation of the homomeric α7 nAChR by nicotine seems to be relevant to the intracellular transduction for generating ROS. Epibatidine, as a strong agonist on the α7 nAChR, caused significant DNA fragmentation in low concentrations, already. By insufficient repair of the DNA damage and inhibited elimination of damaged cells, mutations can accumulate and contribute to tobacco carcinogenesis. Hence, nicotine in a replacement therapy should be considered very critically.