English for Strufents of Biological Departments

Структура пособия позволяет выбрать оптимальные способы организации работы для эффективного усвоения материала и аналитической обработки информации.Данное пособие предназначено для студентов I курса биологического факультета университета. В пособии представлены оригинальные тексты и упражнения к ним, способствующие закреплению лексического и грамматического материала

Determination of Safe and Effective Dosing Regimens for Nonsteroidal Anti-inflammatory Drugs in African and Asian Elephants.

Arthritis and foot disease are well documented conditions affecting captive elephants that are frequently treated with nonsteroidal anti-inflammatory drugs (NSAIDs). An important consideration regarding efficacy and safety of NSAIDs is the cyclooxygenase isoenzyme (COX-1 or 2) targets and pharmacokinetics of the specific drug. The purpose of this study was to determine the COX preference for each drug in Asian elephants, and to determine a dosing regimen for firocoxib based on pharmacokinetics at two doses (0.01 and 0.1 mg/kg) in Asian and African elephants. Single oral dosing of a commercially available tablet or paste determined a preferred dose. This dose underwent further evaluation via a single i.v. dose, and multiple consecutive doses of both formulations. Studies were performed by participating elephant facilities throughout North America. Samples were subjected to firocoxib analysis using HPLC. Pharmacokinetic data was subjected to non-compartmental analysis. Firocoxib was determined to prefer COX-2 whereas flunixin meglumin preferred COX-1 in vitro in Asian elephants (Elephas magnus). Serum levels of firocoxib were too low at doses of 0.01 mg/kg for pharmacokinetic analysis. Key pharmacokinetic parameters after single dosing of 0.1 mg/kg in African elephants were Cmax (31.3 +/- 6.6 ng/ml for tablets; 44 +/- 12.5 ng/ml for paste), AUC (1588+/-362 H*mg/ml for tablets; 814 H*mg/ml for paste) and elimination half-life (66 hours for tablets; 37 hours for paste). Key parameters for single dosing of 0.1 mg/kg orally in Asian elephan were Cmax (49 +/-3.27 ng/ml for tablets; 62 +/- 14.8 ng/ml for paste), AUC (1332+/-878 H*mg/ml for tablets; 1455+/-634 H*mg/ml for paste) and elimination half-life (34.3 +/-30.3 hours for tablets; 19.9 +/-12.8 hours for paste). After multiple administration, the time to steady-state was 5 days and after 8 days of dosing, the Cmax, (75.8+/-15.5 ng/ml for tablets; 95.5+/-29.3 ng/ml for paste) AUC (6341+/-3003 H*mg/ml for tablets; 5613+/-2262 H*mg/ml for paste) and half-life (84.4+/-32.2 hours for tablets; 62.9+/-2.25 hours for paste) were. All animals tolerated all doses with no apparent adverse events. Based on these data, firocoxib should be an effective, safe and convenient analgesic at 0.1 mg/kg every 24 hours when administered to Asian or African elephants

Hair Bundles of a Jawless Vertebrate Employ Tetrapod-Like Tuned Mechanical Amplification

In the hearing and balance organs of tetrapod vertebrates, mechanical signals are transduced by an elegant organelle called the hair bundle. Deflections of this structure apply forces to mechanically gated ion channels. Hair bundles are not passive receivers of stimuli, but are instead active participants in the process of sensory transduction. They expend chemical energy to exert mechanical work, and can harness this active process to amplify their mechanical response to stimuli. Furthermore, the active process is tuned, allowing a given hair bundle to preferentially amplify a particular frequency; this feature is valuable in the analysis of complex sounds. Hair bundles can also enter an unstable regime in which their active process drives spontaneous oscillations. Studying this epiphenomenon can reveal mechanisms underlying the amplifying abilities of hair bundles. Despite the importance of amplification in hearing, little is known regarding the evolution of the active process; it is unclear if the active process is exclusive to tetrapods. It would be instructive, for instance, to know whether the active process predates the array of auditory specializations seen throughout vertebrates. Here, we approach this problem by investigating the mechanical activity of the hair bundles from the inner ears of two jawless vertebrates, the sea lamprey Petromyzon marinus and the American brook lamprey Lampetra appendix. We observe spontaneous oscillations in both of these animals. In the latter species, we also show evidence that their oscillations stem from mechanisms similar to those driving the spontaneous oscillations of tetrapod vertebrates. Furthermore, we found that hair bundles exhibiting these movements can entrain to and mechanically amplify particular stimulus frequencies. Taken together, our findings from a group distantly related to the tetrapods suggest that the active process of hair bundles is trait ancestral to all vertebrate ears

Durch [Arg8]Vasotocin induzierte Translokation des Wasserkanals Aquaporin-2 im tubulären System der Hühnerniere

Das in magnozellulären Kerngebieten des Hypothalamus gebildete und in der Neurohypo-physe gespeicherte antidiuretische Hormon (ADH) bewirkt bei Säugetieren sowie Vögeln eine ausgeprägte renale Antidiurese. Dabei ist bei Säugern sowohl der rezeptive Mechanis-mus in den Hauptzellen der Sammelrohre (G-Protein gekoppelter, 7-transmembranaler V2-Rezeptor), die nachfolgende intrazelluläre Signaltransduktion (cAMP Bildung, Aktivie-rung der Proteinkinase A) sowie die finale Phosphorylierung vesikulär gespeicherter Was-serkanäle (= Aquaporin-2 = AQP-2) und deren Translokation in die luminale Zellmembran eingehend untersucht. Bei Vögeln hingegen konnten zwar die Hauptzellen der Sammel-rohre ebenfalls als wahrscheinlichste Zielstruktur für ADH identifiziert werden. Die mole-kulare Entität des Rezeptors sowie die nachgeschaltete Signaltransduktion hingegen blei-ben bis dato ungeklärt. Hinsichtlich der Bedeutung eines vogelspezifischen AQP-2 liegen erste Daten für die Wachtel, eingeschränkt auch für das Huhn vor. Primäres Ziel der vorliegenden Promotionsarbeit war daher der zelluläre Expressionsnach-weis für den Wasserkanal AQP-2 sowie dessen ADH-induzierte Translokation in die api-kale (bzw. auch laterale) Plasmamembran von Epithelzellen bestimmter Tubulussegmente der Hühnerniere mit Bezug zur Körperflüssigkeitshomöostase. Serielle Gewebsschnitte von in Paraffin eingebetteten Hühnernieren nach transkardialer Perfusionsfixation ermög-lichten zunächst aufgrund einer Hämatoxylin-Eosin Färbung die eindeutige Identifizierung der für die Vogelniere charakteristischen „säugerähnlichen“ sowie „reptilienähnlichen“ Glomerula sowie Epithelien aller tubulären Segmente, wie des proximalen Tubulus, der Henleschen Schleife, des distalen Tubulus sowie corticaler und medullärer Sammelrohre. Für den immunhistochemischen Nachweis des AQP-2 in der Hühnerniere kam ein gegen rattenspezifisches AQP-2 gerichtetes, polyclonales Antiserum in Form affinitätsgereinig-ter IgGs zum Einsatz. Durch indirekte Immunfluoreszenz konnte eine AQP-2 Expression selektiv in der Mehrzahl der Hauptzellen aus den Bereichen des Cortex renalis, corticaler sowie medullärer Sammelrohre, nicht jedoch anderen Zellen bzw. tubulären Komponenten der Hühnerniere aufgezeigt werden. Die Spezifität der Markierung konnte durch Kontroll-versuche (z.B. Absättigen der IgGs mit dem entsprechenden Antigen) untermauert werden. Interkalierende Schaltzellen der Sammelrohre aller drei Nierenbereiche waren durch das Fehlen des AQP-2 Wasserkanals, dafür jedoch ausgeprägte Expression der Carboanhydra-se II charakterisiert, ganz im Sinne ihrer Beteiligung an der Regulation des aviären Säure-Basen Haushaltes. Zur Untersuchung [1] der Translokation des Wasserkanals AQP-2 in die apikale und/oder laterale Plasmamembran der Hauptzellen, [2] einer möglichen Beteiligung von cAMP als second messenger für das vogelspezifische, antidiuretische Hormon [Arg8]Vasotocin = AVT, sowie [3] der Verteilung und Quantifizierung des Rezeptors für AVT in der Hüh-nerniere wurden für jeden dieser drei experimentellen Versuchsansätze drei Gruppen juve-niler Hühner herangezogen. Neben einer euhydrierten Kontrollgruppe (EUH) wurde einer zweiten Tiergruppe zur endogenen Stimulation des AVT-Systems für 40 Std. das Trink-wasser entzogen (DEH); einer dritten Versuchstiergruppe wurde akut für 30 min AVT (5 ng/min/kg KG) systemisch infundiert (AVT). Während die DEH-Hühner gegenüber der EUH-Kontrollgruppe bei extrazellulärer Hypovolämie und Hypernaträmie eine um den Faktor 3 stimulierte AVT Plasmakonzentration aufwiesen, war diese in der AVT-Gruppe bei unveränderten Werten des Extrazellularraumes um das 7-fache erhöht. Die homogene AQP-2 Expression vorrangig im Bereich des supranukleären bis subapika-len Zytosolbereichs der sammelrohrspezifischen Hauptzellen spiegelte die Situation des in Speichervesikeln vorliegenden, „ruhenden“ AQP-2 Wasserkanals bei Tieren der EUH-Gruppe wieder und stellte somit die unstimulierte Ausgangssituation des AQP-2 Translo-kationsprozesses dar. Der Entzug des Trinkwassers (DEH-Gruppe) resultierte in einer sig-nifikanten Zunahme der vesikelassoziierten AQP-2 Expression im gesamten Zytosol der Hauptzellen vor allem im Bereich des Cortex renalis und corticaler Markkegel, weniger der medullären Sammelrohre. Darüber hinaus kam es zu einer Translokation des Wasser-kanals vorrangig in die luminale, in geringem Maße auch die laterale Zellmembran der Epithelzellen. Die systemische AVT-Applikation hingegen resultierte in einer ausgepräg-ten Translokation von AQP-2 primär in die laterale sowie teilweise auch in die luminale Zellmembran. Die Beteiligung intrazellulärer Komponenten des Zytoskeletts sowie von SNARE-Proteinen, sowie die mögliche Funktion einer eher lateralen anstatt rein apikalen AQP-2 Translokation bei akut erhöhten AVT-Plasmakonzentrationen werden diskutiert. Ebenfalls immunhistologische Untersuchungen zu einer möglichen Funktion von cAMP in Rahmen des AVT-induzierten AQP-2 Transfers, durch den Einsatz eines cAMP spezifi-schen Antikörpers, haben keine eindeutigen, eher negative Ergebnisse erbracht. Dieses Ergebnis lässt sich durch zahlreiche Befunde in der Fachliteratur stützen. Die Verwendung des Radioliganden [3H]Vasopressin ermöglichte es, in einer angereicher-ten Plasmamembranfraktion der Hühnerniere mittels Sättigungskinetiken die Affinität (KD) sowie Dichte (Bmax) eines AVT-rezeptiven Systems zu bestimmen. Dabei konnte gezeigt werden, dass die endogene Stimulation des AVT-ergen Systems (DEH), vor allem aber die exogene Applikation des Nonapeptides (AVT) zu einer Down-Regulation des putativen Rezeptors bei unveränderter Bindungsaffinität führte. Kompetitive Verdrängungsstudien mit AVT-Strukturanaloga sowie Agonisten für bestimmte Subtypen des säugerspezifischen ADH-Rezeptors ergaben eindeutig die höchste Bindungsaffinität für AVT, bei marginaler Affinität für V2-Rezeptor spezifische Analoga. Es konnte nachgewiesen werden, dass der renal exprimierte AVT-Rezeptor des Huhnes unterschiedliche Charakteristika im Ver-gleich zu den V1a-, V1b- oder V2-Rezeptorsubtypen des Säugers aufweist. Die abschließen-de rezeptorautoradiographische Analyse konnte die funktionelle Expression des mit dem Radioliganden markierten Rezeptors im Bereich der „reptilienähnlichen“ Glomerula sowie des Sammelrohrbereichs nachweisen. Eine Aktivierung des vogelspezifischen ADH-Systems führte somit einerseits zu einer moderaten Down-Regulation des entsprechenden, zur Situation beim Säuger jedoch unter-schiedlichen Rezeptorsystems in der Niere des Huhnes; die Beteiligung von cAMP als klassischem second messenger des ADH bei Säugern konnte in den durchgeführten Stu-dien an der Hühnerniere nicht eindeutig geklärt werden. Interessanterweise bewirkte die durch extrazelluläre Dehydratation erhöhte Plasmakonzentration an AVT in erster Linie eine Translokation des Wasserkanals AQP-2 aus seiner vesikelassoziierten, zytosolischen Position primär in die luminale Plasmamembran, wohingegen systemisch verabreichtes AVT zu einer AQP-2 Translokation vornehmlich in die laterale Plasmamembran führte.In both mammalian and avian species, the antidiuretic hormone (ADH) - synthesized in magnocellular neurons of the hypothalamus and stored in the neurohypophysis - induces marked antidiuresis at the level of the kidneys. For mammals, the underlying hormone receptive mechanism in principal cells of nephronal collecting ducts (G-protein coupled, 7-transmembranal receptor), the intracellular signalling pathway involved (cAMP formation, protein kinase A activation) and the final steps of phosphorylation of vesicularly stored water channels = aquaporin-2 = AQP-2 with subsequent cellular translocation to the lumi-nal plasma membrane have been elucidated in detail. With regard to the avian kidney, also principal cells of the cortical and medullary collecting ducts could be identified as the most likely target structure for circulating ADH = [arg8]vasotocin = AVT to exert its action. The molecular entity of the receptor as well as the intracellular signalling pathway remain, however, rather unclear. First data became available recently concerning structure and regulated expression of the water channel AQP-2 in the kidney of the quail, and to a limi-ted extent the chicken. The primary goal of the thesis therefore has been to shed light on the cellular expression pattern of AQP-2 in the chicken kidney, with special emphasis being placed upon the AVT-induced AQP-2 translocation into the luminal and/or lateral plasma membranes of nephronal cells of certain tubular segments concerned with the efferent control of body fluid homeostasis. Serial tissue sections of paraffin-embedded, perfusion-fixed chicken kidneys, after staining with hematoxylin-eosin, enabled the clear identification of both “reptilian-type” and “mammalian-type” glomerula, as well as epithelia of all tubular seg-ments including proximal tubules, the loops of Henle, distal tubules and cortical/medullary collecting ducts. Affinity-purified IgGs of a polyclonal rabbit antiserum directed against rat-specific AQP-2 have been employed for the immunohistochemical detection of the water channel in the chicken kidney. Using indirect immunofluorescence, AQP-2 expression could selectively be demonstrated in the majority of principal cells of collecting ducts within the cortex renalis, and both cortical and medullary cone regions. Other cells and tubular structures of the chicken kidney, however, could not be immunolabeled positively. Specificity of label-ing was supported by preincubation of the antibody with the respective antigen. Intercala-ting cells of the collecting ducts within all three segments of the kidney investigated could be characterized by the lack of AQP-2 but marked carboanhydrase II expression. In order to elucidate [1] the translocation process for AQP-2 into the luminal and/or lateral plasma membrane of principal cells, [2] the putative contribution of cAMP as a second messenger for avian-specific AVT, as well as [3] the distribution and quantification of receptors for AVT in the chicken kidney, three groups of juvenile chicken were formed for each of these projects. Besides a euhydrated control group (EUH), drinking water was withdrawn for 40 hrs for a second group of animals, rendering them dehydrated (DEH) with an endogenously activated ADH-system. AVT was acutely applied to a third group of chicken by intravenous infusion (5 ng/min/kg BW) for 30 min (AVT). DEH animals pro-ved to have a 4-fold elevated plasma AVT concentration when compared to the EUH group, under conditions of extracellular hypovolemia and hypernatremia, whereas the AVT group revealed an even 8-fold elevation of plasma AVT at unaltered status of the extracel-lular fluid compartment. The homogeneous AQP-2 expression preferentially in the supranuclear to subapical zone of the principal cells reflected the situation of AQP-2 water channels being stored in cytosolic vesicles, “waiting” to be called upon stage; this status represents the non-stimu-lated starting condition before ADH-induced AQP-2 translocation. The withdrawal of drin-king water (DEH group) resulted in a significant increase in vesicle-associated AQP-2 expression throughout the cytosol of principal cells localized in the cortex renalis, the cor-tical cones and to a lesser degree the medullary cones. Furthermore, in a major portion of collecting duct epithelial cells, the water channel proteins have been translocated to and into the lumi-nal plasma membrane, with some cells also demonstrating immunolabeling for AQP-2 at the level of the lateral membranes. Systemic AVT infusion on the other hand caused pronounced translocation of water channel proteins into the lateral, partially also luminal plasma membrane sites. The contribution of intracellular cytoskeleton components and SNARE proteins, as well as the putative functionality of lateral rather than luminal AQP-2 membrane insertion under conditions of hyperosmolality and/or elevated plasma AVT con-centration is discussed. Additional immunohistochemical experiments trying to reveal the contribution of cAMP as a classical second messenger within the issue of AVT-induced AQP-2 translocation did not yield unequivocal results or even negative ones, thus supporting data collected over the years speaking against a role of cAMP as an important, AVT-induced messenger molecule in the avian kidney. The application of the radioligand [3H]vasopressin allowed the determination of both the affinity (KD) and density (Bmax) of the AVT receptive system in the chicken kidney, em-ploying an enriched plasma membrane fraction. It could be demonstrated, that the endoge-nous stimulation of the AVT system (DEH group), and even more so the systemic admini-stration of AVT (AVT group) induced a down-regulation of the putative AVT receptor at unaltered binding affinity. Competitive displacement studies with AVT analogues and lig-ands for various ADH receptor subtypes showed highest affinity for AVT to displace [3H]AVP, with only marginal affinity for V2 receptor agonist dDAVP. The renally expressed AVT receptor appears to possess binding characteristics different from classical mammalian V1a-, V1b- and V2-receptors. Receptor autoradiographical analysis led to the specific labelling of “reptilian-type” glomerula and cortical cone collecting tubules. Activation of the avian-specific ADH (= AVT) system thus resulted in a moderate down-regulation the yet unknown renal AVT receptive system. The contribution of cAMP as a classical second messenger of ADH in mammals could not be clarified in the thesis presen-ted. Extracellular dehydration with elevated plasma AVT levels caused a marked transloca-tion of AQP-2 water channel proteins from its cytosolic, vesicle-associated location prima-rily into the luminal plasma membrane, whereas systemically administered AVT at unalte-red status of the extracellular fluid compartment led to AQP-2 translocation into the lateral plasma membranes

The effects of extracellular sodium chloride on the activity and expression of Na,K-ATPase in primary cultures of dogfish (Scyliorhinus canicula) rectal gland epithelial cells

Dogfish, Scyliorhinus canicula, rectal gland epithelial cells were successfully cultured using two different techniques: 1) a perfusion based technique and 2) a modified Valentich's technique. The morphology of the primary rectal gland epithelial cell cultures was investigated using light, fluorescence and electron microscopy. These studies demonstrated that the cell cultures express most of the structural features of native shark rectal gland cells, including numerous mitochondria, complex tight junctions and extensive membrane folding. The cultured cells using the perfusion technique adopted an extremely flattened morphology when grown on collagen. These cells whether grown in suspension or on collagen, displayed a striking level of vacuole formation, these vacuoles were not associated with transport epithelia. The rectal gland cell cultures were then used to investigate the effect increasing extracellular sodium chloride concentration has on rectal gland cells Na, K-ATPase activity. Increasing sodium chloride concentration in the growth medium by 50% (240 mM to 360 mM) resulted in a transient 3-4 fold increase in Na, K-ATPase activity in cell homogenates approximately 12 hours after the medium change. The response was dependent upon both sodium and chloride ions and was also inhibited by the loop diuretic bumetanide (0.1 mM within 30 minutes), indicating that entry of the ions into the cell is via the Na, K, C1 cotransporter. Incubation of cells in normal medium in the presence of the sodium ionophore monensin also resulted in a dose dependant sustained increase in Na, K-ATPase activity following a 12 hour incubation. The increase in Na, K-ATPase activity associated with increased extracellular sodium chloride concentration was only seen in cells grown on collagen and not in cells grown in suspension. Increases in activity are sensitive to the protein synthesis inhibitor cycloheximide (10 mug/ml), but not the transcriptional inhibitor actinomycin D suggesting that up-regulation of the Na, K-ATPase occurs at the level of translational regulation. Unfortunately this result could not be confirmed using Northern analysis due to unforeseen difficulties in extracting sufficient RNA from the cell cultures. Addition of bumetanide (0.1 mM) to cells grown in normal medium caused a rapid but reversible down-regulation (by 70%) of basal Na, K-ATPase activity within 30 minutes. The anti-microtubular agent colchicine (0.1 mug/ml) inhibited the bumetanide induced down-regulation of Na, K-ATPase and also the recovery of activity following bumetanide removal. The rectal gland cell cultures were used to investigate potential hormonal regulators of the shark rectal gland. The effect of the putative regulators of sodium chloride secretion scyliorhinin II and sCNP on intracellular concentrations of cAMP and cGMP was investigated. The cell cultures were shown be hormonally active as they responded with an increase in intracelllular cAMP concentration to forskolin, PGE1 and PGE2. When scyliorhinin II (10 muM) and IBMX (1 mM) was perfused through the isolated rectal gland a 2 fold increase in cAMP concentration was found in the perfusate after 8 minutes, however no increase was seen in cAMP levels when cell cultures were treated with scyliorhinin II. Shark CNP increased cGMP concentrations in the perfusates of the perfused rectal gland by up to four fold after seven minutes but there was no consistent effect on cGMP concentrations in the cultured cell monolayer. In conclusion it is believed that sCNP and scyliorhinin II mediate their actions on the regulation of sodium chloride secretion by the rectal gland at the vascular level, controlling the extent of perfusion of the gland. This study showed that high salt levels in the medium of shark rectal gland cell monolayers increased the measurable Na, K-ATPase activity and that this response was dependent on protein synthesis but not transcription. It also showed that the response is inhibited by the loop diuretic bumetanide, indicating that entry of the ions into the cell is via the Na, K, Cl cotransporter and that the increase in Na, K-ATPase activity is presumably due to an increase in intracellular sodium concentration. The hormones sCNP and scyliorhinin II appear to mediate their actions on the regulation of sodium chloride secretion by the rectal gland at the vascular level controlling the extent of perfusion of the gland. In conclusion although sodium chloride transport in the dogfish rectal gland requires much more investigation, this study has hopefully proved that dogfish epithelial cell cultures provide a good model for further investigations involving the regulation of activity and expression of the sodium pump

Life Sciences Program Tasks and Bibliography for FY 1997

This document includes information on all peer reviewed projects funded by the Office of Life and Microgravity Sciences and Applications, Life Sciences Division during fiscal year 1997. This document will be published annually and made available to scientists in the space life sciences field both as a hard copy and as an interactive internet web page

Glycoproteomic research using mass spectrometry

The development of problem-specific mass spectrometric (MS) glycoproteomic strategies has allowed the discovery of previously unknown protein glycosylation in both eukaryotic and prokaryotic organisms. The research in this thesis focuses on the identification and structural characterisation of novel glycan structures in ADAMTS13 and Clostridium difficile. ADAMTS13 is a large multi-domain protein which regulates thrombogenesis by cleavage of the adhesive blood glycoprotein, VWF, so generating smaller less thrombogenic fragments. Glycoproteomic strategies were employed to investigate a secretion-enhancing mutant by comparing the O-glycome of wild type (WT) with synonymous substitution, P118P, and a non-synonymous control, P118F. Identical post-translational modifications (PTMs) but several novel PTMs were discovered in ADAMTS13 including TSR1 O-glycosylation, C-mannosylation of W387 and DiSialyl Core-1 O-glycosylation of S1170. Clostridium difficile is one of the main organisms responsible for morbidity in hospitalised patients, and is the etiological agent of antibiotic-associated diarrhoea and pseudomembranous colitis. The C.difficile cell wall is surrounded by an S-layer composed of two proteins, high molecular weight (HMW) and low molecular weight (LMW) SLPs. 12 slpA gene cassettes have been recently described and cassette-11 carries an insert containing 19 ORFs. Combining different biochemical and ES- and MALDI-MS approaches, including the ETD technique, with genetic experiments, it was demonstrated that LMW SLP in strain Ox247 is glycosylated with a surprisingly large linear pentose-branched oligosaccharide of more than forty sugar residues, and a collaborative NMR study suggests a Phospho- and Acetyl- substituted non-reducing terminal rhamnose. Analysing different C.difficile hypervirulent strains, novel flagellar sulphonated peptidylamido-glycan structures not previously observed in sugar or amino acid chemistry were identified. High resolution mass measurement and negative-ion nanospray MS/MS of cone-voltage-induced fragment ions were crucial in allowing the discovery of a unique terminal Taurine (aminoethyl-sulphonic acid) peptidylamidoglycan unit which could provide a novel strategy to escape the immune system, by the C.difficile becoming more virulent.Open Acces

OSU theses and dissertations : 1966-1970

A departmental and author index of Masters' Theses and Doctoral Dissertations accepted by the Graduate School