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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A molecular analysis of opsin integration at the endoplasmic reticulum

Ismail, Nurzian January 2005 (has links)
A major step in the biosynthesis of many membrane proteins is their insertion into the membrane of the endoplasmic reticulum (ER). The insertion of a multi-spanning membrane protein is a complex process since several transmembrane (TM) domains have to be correctly integrated in order to enable its correct assembly. At present it is unclear how the integration of multiple TM domains is co-ordinated by the ER translocon. The aim of this study was to analyse the molecular environment of the TM domains of a model seven TM domain protein, opsin, so as to better understand the mechanism by which integration occurs. For this purpose, stable 'integration intermediates' of defined lengths representing distinct stages of opsin biosynthesis were generated by in vitro translation of truncated mRNA in the presence of semi-permeabilised cells. Cysteine-mediated, site-specific cross-linking and immunoprecipitation were employed to examine the environment of these integration intermediates. In addition, cysteine-specific modification reagents with different physical properties were used to investigate the environment of opsin TM3 during its insertion at the ER membrane. Opsin TM domains exhibit unique patterns of adduct formation with the ER translocon components, Sec61α and Sec61β. TM1 associates with the Sec61 complex at two distinct stages during nascent chain extension, and this behaviour is dependent on the presence of subsequent TM domains. The re-association of TM1 with the transloconmay well facilitate the co-ordinated integration of TMs 1-3 into the lipid bilayer. Opsin TM4 exits the Sec61 complex as soon as the subsequent TM domain is synthesised, while TM5, TM6 and TM7 remain associated with the ER translocon throughout protein synthesis, suggesting their concerted release upon chain termination. Evidence is provided that opsin is integrated via a single Sec61 heterotrimer, despite the fact that the ER translocon appears to consist of multiple copies of the Sec61 complex. On the basis of this work, a model is presented describing the complete integration of opsin at the ER membrane.
2

Avaliação in vitro do sêmen refrigerado e congelado de touros da raça 5/8 girolando / In vitro evaluation of chilled and frozen semen of 5/8 girolando bulls

CHAVES, Maiana Silva 27 May 2015 (has links)
Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-04-26T12:49:23Z No. of bitstreams: 1 Maiana Silva Chaves.pdf: 890339 bytes, checksum: 482b52d7baa7cd8512faba3b39aaca01 (MD5) / Made available in DSpace on 2017-04-26T12:49:23Z (GMT). No. of bitstreams: 1 Maiana Silva Chaves.pdf: 890339 bytes, checksum: 482b52d7baa7cd8512faba3b39aaca01 (MD5) Previous issue date: 2015-05-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The use of semen from 5/8 Girolando bulls is a way to turn aviable genetic material from a specialized breed in the harshest environments. In this sense, the objective of this study was to analyze in vitro the semen from this breed, concomitant to the comparison of semen changes the same sample subjected to cooling (24 and 48 hours) and freezing, the seminal analysis of bulls exposed to the same conditions and checking correlations between them and mainly obtain standard values for l in vitro seminal assays. Analyzes of total motility, progressive motility, curvilinear speed and beat cross frequency showed statistical difference between the cooling and freezing treatments, with the bull factor influencing the results of plasma membrane integrity, acrosome membrane potential and chromatin condensation. Among the variables, the integrity of the plasma membrane was the variable that presented the highest correlation with the other studied. The in vitro seminal analyzes of 5/8 Girolando bulls subjected to low temperatures will contribute to the knowledge of standard values for the analyzed variables. / A utilização do sêmen de touros 5/8 Girolando é uma maneira de disponibilizar material genético de uma raça especializada em ambientes mais hostis. Nesse sentido, o objetivo desse trabalho foi analisar in vitro o sêmen de reprodutores dessa raça, concomitante a comparação das alterações do sêmen da mesma partida submetido a refrigeração (24 e 48 horas) e congelação, às análises seminais de touros expostos às mesmas condições verificando correlações e principalmente, obtenção de valores padrões de análises seminais in vitro. Análises de motilidade total, motilidade progressiva, velocidade curvilínea e batimento flagelar cruzado mostraram diferença estatística entre os tratamentos de refrigeração e congelação, com o fator touro influenciando nos resultados de integridade de membrana plasmática, potencial de membrana acrossomal e condensação da cromatina. Dentre as variáveis, a integridade da membrana plasmática foi a variável de maior correlação com as demais estudadas. As análises seminais in vitro de touros 5/8 Girolando submetidos a baixas temperaturas contribuirá para o conhecimento dos valores padrões para as variáveis analisadas.
3

Structural characterisation and in vitro behaviour of apatite coatings and powders.

Etok , S E 17 November 2009 (has links)
Hydroxyapatite (HAP) coatings are used in orthopaedic surgery for bone regeneration. Current methods of phase quantification of HAP coatings suffer from drawbacks. A novel methodology of quantitative phase analysis of HAP coatings has been devised and validated. This method, based on whole pattern fitting with a fundamental parameters approach, incorporates amorphous calcium phosphate (ACP) and apatite phases into structural refinements. A comparison of the structural and chemical properties of plasma sprayed (PS) and novel electrodeposited (ED) HAP coatings has been conducted. ED coatings contained less ACP and more preferred orientation than the PS coatings, although the stoichiometry was similar. In vitro investigations of PS and ED coatings in simulated body fluid and foetal calf serum revealed that both are bioactive. A carbonated apatite layer produced on the ED coatings was -0.7μm thick with a stoichiometry and chemical constituents similar to that of natural bone apatite. PS coatings produced a nanocrystalline carbonated apatite layer (-4μm). For the first time it has been possible to model crystalline HAP and nanocrystalline apatite as independent phases and obtain accurate lattice parameters for each. A positive linear correlation has been made between microstrain and the solubility of HAP and carbonated apatites. Dissolution studies have shown that the behaviour of HAP and carbonated apatite is dominated by crystallite size at low undersaturation and by crystallite size and microstrain at high undersaturation for crystallites between -30OA- 1000A. Metastable equilibrium occurred for crystallites <_400A at low undersaturation. Carbonate content did not affect the solubility or dissolution behaviour. A novel technology for coating polymeric tape with HAP for potential use in anterior cruciate ligament reconstruction has been devised. Mechanical tests have demonstrated that no adverse properties are induced by the coating technology. Cell culture studies have shown that the HAP layer is capable of enhanced attachment, proliferation and differentiation of osteoblast cells compared to uncoated tape.
4

Structural characterisation and in vitro behaviour of apatite coatings and powders

Etok, Susan Essien January 2005 (has links)
Hydroxyapatite (HAP) coatings are used in orthopaedic surgery for bone regeneration. Current methods of phase quantification of HAP coatings suffer from drawbacks. A novel methodology of quantitative phase analysis of HAP coatings has been devised and validated. This method, based on whole pattern fitting with a fundamental parameters approach, incorporates amorphous calcium phosphate (ACP) and apatite phases into structural refinements. A comparison of the structural and chemical properties of plasma sprayed (PS) and novel electrodeposited (ED) HAP coatings has been conducted. ED coatings contained less ACP and more preferred orientation than the PS coatings, although the stoichiometry was similar. In vitro investigations of PS and ED coatings in simulated body fluid and foetal calf serum revealed that both are bioactive. A carbonated apatite layer produced on the ED coatings was -0.7μm thick with a stoichiometry and chemical constituents similar to that of natural bone apatite. PS coatings produced a nanocrystalline carbonated apatite layer (-4μm). For the first time it has been possible to model crystalline HAP and nanocrystalline apatite as independent phases and obtain accurate lattice parameters for each. A positive linear correlation has been made between microstrain and the solubility of HAP and carbonated apatites. Dissolution studies have shown that the behaviour of HAP and carbonated apatite is dominated by crystallite size at low undersaturation and by crystallite size and microstrain at high undersaturation for crystallites between -30OA- 1000A. Metastable equilibrium occurred for crystallites <_400A at low undersaturation. Carbonate content did not affect the solubility or dissolution behaviour. A novel technology for coating polymeric tape with HAP for potential use in anterior cruciate ligament reconstruction has been devised. Mechanical tests have demonstrated that no adverse properties are induced by the coating technology. Cell culture studies have shown that the HAP layer is capable of enhanced attachment, proliferation and differentiation of osteoblast cells compared to uncoated tape.
5

Metodverifiering av reagens med förhöjt tröskelvärde för biotininterferens för biomarkörerna NT-proBNP, prokalcitonin och prostataspecifikt antigen på Roche Cobas® e801.

Hoberg, Emilia January 2020 (has links)
Biotin är ett vitamin som finns naturligt i livsmedel och det dagliga intaget nås via födan. Höga doser biotintillskott samt höga doser biotin i läkemedel, kan leda till biotininterferens i kliniska immunokemiska analyser. Roche Diagnostics® vill införa nya reagens med högre tröskel för biotininterferens för att minska risken för biotininterferens vid analys av patientplasma. Därför var syftet med studien att metodverifiera fyra nya reagens från Roche Diagnostics® som används vid diagnostisering och behandling av hjärtsvikt, sepsis, och prostatacancer. De fyra reagensen, Elecsys® proBNP II, Elecsys® BRAHMS PCT, Elecsys® total PSA samt Elecsys® free PSA metodverifierades för att användas på Cobas® e801. Studiematerialet bestod av 20 patientprover av litiumheparinplasma per reagens (totalt 80 patientprover). Resultatet av verifieringen av Elecsys® proBNP II visade en korrelation till det befintliga reagenset på r = 0,9998 och Bland-Altman analys visade en spridning av resultaten på &lt; 10 %; inomserieprecisionsstudien gav CV 1,56 %. Elecsys® BRAHMS PCT hade en korrelation på r = 0,9997 och Bland-Altman analysen visade en spridning på &gt; 10 %; inomserieprecisionsstudien gav CV 1,70 %. För Elecsys® total PSA och free PSA fanns korrelationen till det befintliga reagenset på r = 1 respektive 0,9997 och Bland- Altman analysen visade en spridning på &lt; 10 % hos båda reagensen. Inomserieprecisionsstudien gav CV 0,44 % respektive CV 2,67 %. Resultaten för samtliga reagens uppvisar god korrelation till det befintliga reagenset och en hög mätnoggrannhet vilket talar för att de fyra nya reagensen kan tas i bruk. / Biotin is naturally found in foods, and we obtain this vitamin through our daily diet. Biotin supplements as well as high doses of biotin in drugs can lead to biotin interference in clinical immunochemical analyzes. Therefore, the purpose of this study was to methodically verify four new reagents from Roche Diagnostics® with a higher threshold for biotin interference, used in the diagnosis and treatment of heart faliure, sepsis and prostate cancer. The four reagents, Elecsys® proBNP II, Elecsys® BRAHMS PCT, Elecsys® total PSA and Elecsys® free PSA were method-verified for use on Cobas® e801. The study material consisted of 20 patient samples of lithium heparin plasma per reagent. In total 80 samples were analyzed.The result of the verification of Elecsys® proBNP II showed a correlation to the existing reagent of r = 0.9998 and Bland-Altman analysis showed a distribution of the results of &lt;10 %. The withinseries precision study yielded CV 1.56 %. Elecsys® BRAHMS PCT had a correlation of r = 0.9997 and the Bland-Altman analysis showed a distribution of &gt; 10 %. The withinseries precision study gave CV 1.70 %. For Elecsys® total PSA and free PSA, the correlation to the existing reagent was r = 1 and 0.9997, respectively, and the Bland-Altman analysis showed a distribution of &lt;10 % in both reagents. The withinseries precision study yielded CV 0.44 % and CV 2.67 % respectively.The results for all reagents show a good correlation to the existing reagent and a high accuracy of measurement, which indicates that the four new reagents can be used.
6

Verifiering av metod för analys av etylenglykol i plasma på Roche Cobas® c502

Lindgren, Rebecca January 2021 (has links)
Etylenglykol (etan-1,2-diol) är en dihydroxyalkohol som är en komponent i kylarvätska och andra frost- och kylskyddsmedel. Förtäring av etylenglykol leder till allvarliga skador och i värsta fall död utan behandling. I Sverige år 2020 fanns det endast ett tiotal laboratorier som erbjöd analys av etylenglykol dygnet runt. Detta leder till att prover ofta behöver skickas till större laboratorier med taxi vilket i sin tur leder till en försenad diagnosticering av patienten. Syftet med examensarbetet var att verifiera en enzymatisk kolorimetrisk metod för analys av etylenglykol i plasma på instrumentet Roche Cobas® 8000 modul c502. Reagenset som verifierades var DiscretPak™ Ethylene Glycol Reagents från företaget Catachem. Verifieringen gjordes med avseende på total precision (repeterbarhet), inomserieprecision och linjäritet. Resultaten jämfördes med analys på gaskromatograf. Provmaterialet bestod av patientprover av litiumheparinplasma,  patientprover av serum och kontrollprover från Equalis. Resultatet som erhölls vid verifieringen visade på linjär korrelation mellan den enzymatiska metoden och GC-analys. En negativ bias observerades dock i jämförelse med analys på gaskromatograf. Utvärdering av repeterbarhet gav CV 4,6% vid 9,0 mmol/L och 3,66% vid 40,0 mmol/L. Inomserieprecisionstudie gav CV 14,7% vid 1 mmol/L, 5,2% vid 4 mmol/L och 1,4% vid 17 mmol/L. Precisionen är viktigast vid de lägre koncentrationerna. Insättning av behandling med antidot är aktuellt vid 4 mmol/L. Utvärdering av linjäritet visade på ett starkt linjärt samband hos analysen vid koncentrationer &lt;50 mmol/L. Vid koncentrationer &gt;50 mmol/L fanns ett linjärt samband men en minskad överensstämmelse mellan den beräknade och den uppmätta koncentrationen observerades. Metodverifieringen ansågs vara godkänd för kliniskt bruk och analysen kommer att införas i analyssortimentet hos Klinisk Kemi i Växjö. / Ethylene glycol is an alcohol that is a common component in antifreeze. Ingestion of ethylene glycol will, without treatment, lead to severe organ damage and in worst-case death. In 2020 there was only a few laboratories in Sweden that offered analysis of ethylene glycol all hours of the day and week. This means that samples often need to be transported to laboratories at larger hospitals which leads delayed diagnosis of the patient. The purpose of this study was to verify an enzymatic method for analysis of ethylene glycol in plasma on the instrument Roche Cobas® 8000 module c502. The reagent that was used was DiscretPak™ Ethylene Glycol Reagents from Catachem. The study included evaluation of total precision, within-run precision, linearity, and a comparison with analysis with gas chromatography (GC). The sample material consisted of patient samples of plasma, patient samples of serum and quality controls from Equalis. The result of the study showed linear correlation between the enzymatic method and analysis with GC. A negative bias was observed in comparison to analysis with GC. The coefficient of variation (CV) for total precision was 4,7% at 9,0 mmol/L and 3,7% at 40,0 mmol/L. The CV for within-run was 14,7% at 1 mmol/L, 5,2% at 4 mmol/L and 1,4% at 17 mmol/L. The precision of the method is most important at lower concentrations. The evaluation of linearity showed linear correlation at concentrations &lt;50 mmol/L with. A linear correlation was observed at concentrations &gt;50 mmol/L, although the agreement with the calculated concentrations decreased. The method verification was successful as the results were deemed acceptable for clinical use.

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