La Psicologia de l'Art estudia les experiències estètiques i les preferències dels individus mentre miren l'art. L'objectiu d'aquesta investigació és analitzar l'apreciació de l'art contemporani en joves i gent gran al MFA de Boston. Es van dur a terme anàlisis quantitatives i qualitatives. L’estudi 1 va mostrar que els joves, més que la gent gran, van trobar que les cartel·les i les converses van contribuir a apreciar l'art contemporani, i més en el context del museu que en el del laboratori. L’estudi 2 va mostrar que el context del museu va contribuir a apreciar l’art, també, en els grups de discussió els joves comentaven que les cartel·les i les converses eren un punt de partida per entendre i apreciar l'art, per la gent gran no van ser tan útils. L'estudi 3 va mostrar que no només hi havia diferències entre la sala d’art contemporani i tradicional -la comprensió de l'art contemporani va ser major en la galeria d'art contemporani-, sinó també entre els grups d'edat -els joves van declarar que els agradava més l'art contemporani i la gent gran van gaudir més de l’experiència de visitar el museu-. Vam arribar a la conclusió que no només les diferències d'edat, sinó també les diferències relacionades amb l'educació i la freqüentació de les visites als museus contribueixen a l'apreciació de l'art. Aquesta investigació és important per demostrar com la gent aprecia i entén l'art contemporani. Per tant, aquests resultats tenen implicacions rellevants per dissenyar programes d’activitats en els museus que involucrin diferents grups de visitants. / La Psicología del Arte estudia las experiencias estéticas y las preferencias de los individuos mientras miran el arte. El objetivo de esta investigación es analizar la apreciación del arte contemporáneo de jóvenes y gente mayor en el MFA de Boston. Se llevaron a cabo análisis cuantitativos y cualitativos. El estudio 1 mostró que los jóvenes, más que la gente mayor, encontraron que las cartelas y conversaciones contribuyeron a apreciar el arte contemporáneo, y más en el contexto del museo que en el del laboratorio. El estudio 2 mostró que el contexto del museo contribuyó a la apreciación del arte. También, las discusiones en el grupo de jóvenes confirmaron que las cartelas y las conversaciones forman un punto de partida para entender y apreciar el arte, para la gente mayor no eran tan útiles. El estudio 3 mostró que no sólo existían diferencias entre la sala de arte contemporáneo y tradicional -la comprensión del arte contemporáneo fue mayor en la sala de arte contemporáneo-, sino también entre los grupos de edad -los jóvenes declararon que les gustaba más el arte contemporáneo y la gente mayor disfrutó más de la experiencia en el museo-. Llegamos a la conclusión de que no sólo las diferencias de edad, sino también las diferencias relacionadas con la educación y la frecuentación de visitas contribuyeron a la apreciación del arte. Esta investigación es importante para demostrar cómo la gente aprecia y entiende el arte contemporáneo. Por lo tanto, estos resultados tienen implicaciones relevantes para diseñar programas en los museos que involucren diferentes grupos. / Psychology of Art studies aesthetic experiences and individuals’ preferences while looking at art. The aim of this research is to analyze contemporary art appreciation in younger and older adults at the Museum of Fine Arts, Boston. Quantitative and qualitative analyses were conducted. Study 1 showed that younger more than older adults found that labels and conversations contributed to liking contemporary art, more in a museum setting rather than in a lab setting. Study 2 showed that the museum context contributed to appreciating the art. Also, group discussion of younger adults confirmed labels and conversations in the museum to be a starting point to understand and appreciate art; for older adults, these were not so helpful. Study 3 showed that not only were there differences between a contemporary and a traditional art gallery -participants understanding of contemporary art was greater in the contemporary art gallery-, but also between age groups -younger adults stated that they liked contemporary art more and older adults enjoyed their museum experience more. We conclude that not only age differences, but also differences related to education and museum visitation frequency contributed to art appreciation. This research is important to demonstrate how people appreciate contemporary art and how they understand it. Therefore, these findings have relevant implications for the design of museum programs about contemporary art to engage different groups of visitors.

This thesis studies the effects on the unemployment rate and average income due to the payroll tax cuts for young workers in Sweden. The method that has been used is a difference-in-difference approach with two different control groups. The unemployment rate for Swedish individuals at age 15-24 has been matched towards individuals at the same age in Finland and Denmark. The data behind the estimations is picked from the database of Eurostat. The results indicate an increase in the unemployment rate, contrary to the expectations from the theoretical framework in the subject. One possible explanation for a lack of increase in employment due to a targeted tax cut is shifting, meaning that the lowered cost for firms is shifted onto the employees’ wages. However, no significant results on the wage effect were found, so no such conclusion can be made. The explanation could lay in modeling problems, a growing labor force or the supply of labor (which may choose other alternatives than employment). By the results of this report, the main conclusion is that the payroll tax reductions did not reduce the high unemployment rate among young individuals in Sweden.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Current Landsat 7 processing is based on a single-string, multifunction approach. A follow-on system has been designed that repartitions functions across multiple hardware platforms to provide increased flexibility and support for additional missions. Downlink bit stream acquisition has been moved to lower cost systems functioning as “capture appliances” with high-speed network interconnections to Level 0 processing on generic compute servers. This decouples serial data stream acquisition from the processing system to allow the addition or replacement of compute servers, without the reintegration of specialized high-speed capture hardware. Moreover, it also allows the easy integration of new systems and missions without extensive system redesign or additional software.

Résumé : L’IL-7 et l’IL-15 sont des cytokines impliquées dans l’homéostasie des lymphocytes T CD8 naïfs et mémoires respectivement. Lors d’une réponse immunitaire, certaines cytokines pro-inflammatoires, comme l’IL-6 et l’IL-21, sont produites par les cellules du système immunitaire inné. Nous avons observé que certaines cytokines de ces deux groupes (homéostasie et pro-inflammatoires), peuvent avoir un effet synergique sur la fonction des lymphocytes T CD8. Spécifiquement, l’incubation des lymphocytes T CD8 naïfs avec l’IL-6 ou l’IL-21, en présence d’IL-7 ou d’IL-15 cause une forte prolifération qui est indépendante de l’antigène. De plus, la combinaison d’IL-15 avec l’IL-6 ou l’IL-21 entraîne une prolifération préférentielle des lymphocytes T mémoires, tandis que la combinaison avec l’IL-7 entraîne une prolifération des lymphocytes T naïfs. La stimulation des lymphocytes T CD8 avec l’IL-6 ou l’IL-21, en présence d’IL-7 ou d’IL-15, entraîne une augmentation de la phosphorylation en tyrosine de STAT5 ainsi qu’une augmentation de liaison à l’ADN. Nous avons étudié l’effet d’une pré-stimulation des cellules T CD8 naïves par les cytokines synergiques sur leur réponse subséquente à un antigène. Nous avons observé qu’une pré-stimulation avec l’IL-6 ou l’IL-21, en présence d’IL-7 ou d’IL-15, même pour une courte durée de 24 heures, augmente leur sensibilité aux antigènes, entraînant une robuste prolifération et une forte augmentation de cytotoxité spécifique à l’antigène gp33. Nous avons observé que les cytokines pro-inflammatoires en combinaison avec l’IL-7 induisent une augmentation accrue de la prolifération chez les lymphocytes T CD8 exprimant un TCR transgénique de forte affinité (P14), ainsi que les cellules exprimant un TCR de faible affinité (H-Y). De plus, la combinaison synergique de cytokines entraîne une forte expression du récepteur de l’IL-2R[gamma] (CD132), ainsi qu’une augmentation de la production d’IL-2 après stimulation antigénique. Une forte augmentation de l’expression de CD8 et de CD45, ainsi qu’une diminution drastique de l’expression de CD5 peut expliquer l’augmentation de l’avidité fonctionnelle du TCR suite à une stimulation avec les combinaisons de cytokines synergiques. La stimulation des lymphocytes T CD8 avec les combinaisons de cytokines, induit une augmentation de la phosphorylation de LAT ainsi qu‘AKT. Cependant, la stimulation subséquente du CD3 n’entraîne pas d’augmentation de la phosphorylation de LAT ainsi qu’AKT chez les lymphocytes T CD8 pré-stimulés avec les combinaisons de cytokines. Nous avons aussi observé que les lymphocytes T CD8 stimulés avec les combinaisons de cytokines augmentent l’expression de CD62L, ce qui peut favoriser leur migration vers les ganglions lymphatiques. En conclusion, la production de cytokines pro-inflammatoires (IL-6, IL-15, IL-21) par les cellules du système immunitaire inné lors d’une infection ou d’une inflammation, ainsi que la présence constitutive d’IL-7, peuvent stimuler la prolifération et l’activation des lymphocytes T CD8 de façon non spécifique à l’antigène. Cette stimulation entraîne une augmentation de l’avidité fonctionnelle de leur TCR causant ainsi une forte prolifération ainsi que l’acquisition de fonctions effectrices spécifiques. Cette liaison entre le système immunitaire inné et adaptatif, médiée par les cytokines pro-inflammatoires et les cytokines homéostatiques joue un rôle très important dans l’élimination des pathogènes ainsi que dans le développement de maladies auto-immunitaires. / Abstract : Homeostasis of naive and memory CD8[superscript +] T lymphocytes is dependent on two cytokines IL-7 and IL-15, respectively. During an immune response to an infection, cells of the innate immune system produce several pro-inflammatory cytokines. We have observed that these two groups of cytokines, namely proinflammatory and homeostatic, can have a synergistic effect on CD8 T lymphocytes. Specifically, incubation of naive CD8 T cells with IL-6 or IL-21 in the presence of IL-7 or IL-15 induced strong proliferation in an antigen independent manner. While the combination of IL-6 or IL-21 with IL-15 induced strong proliferation of memory CD8 T cells, naïve CD8 T cells responded better to the combination with IL-7. These stimulatory cytokine combinations elicited strong STAT5 phosphorylation and it’s binding to DNA in CD8 T cells. We investigated the effect of priming CD8 T cells with the synergistic combination of IL-6 or IL-21 and IL-7 on their subsequent response to antigen. We observed that cytokine priming for only 24 hours enhanced their sensitivity to antigen, resulting in strong proliferation, effectors functions and cytotoxicity. These effects were observed with CD8 T cells expressing transgenic TCR with strong (P14) or weak (H-Y) affinity towards cognate peptide antigens. Priming CD8 T cells with the synergistic combination of cytokines increased the expression of IL-2 receptor gamma (CD132) and augmented the production of IL-2 when stimulated with antigen. These cells also expressed elevated levels of CD8 and CD45, as well as down modulate CD5, and these events may underlie the increased TCR avidity. Stimulation of CD8 T cells with the synergistic combination of cytokines induced phosphorylation of LAT and AKT. However, subsequent TCR stimulation did not further increase these phosphorylation events. We have observed that C D8 T cells primed with the synergistic combinations of cytokines up regulated CD62L, which could promote their migration through lymph nodes. In conclusion, inflammatory cytokines such as (IL-6, IL-15, IL-21) secreted by cells of the innate immune system during an infection or non-infectious inflammation, and basal levels of the homeostatic cytokine IL-7 can act in synergy with inflammatory cytokines to activate CD8 T lymphocytes in an antigen independent manner. This stimulation also results in an increase in the functional avidity of their TCR, as indicated by strong antigen responsiveness with increased proliferation and display of effectors functions. This connection between the innate and adaptive system mediated by inflammatory cytokines may play an important role in pathogen clearance and possibly in the development of autoimmune diseases.

Thesis (MTh (Practical Theology and Missiology))--University of Stellenbosch, 2009. / AFRIKAANSE OPSOMMING: “First, the church isn’t ours; it’s God’s. And second, it isn’t ours; it’s us” (McLaren 2000:7). Wat ook al van die Kerk gesê word, hoe ons as Kerk funksioneer en leef – dit moet altyd gedoen word met hierdie woorde van McLaren in gedagte. Die gesindheid waarmee ons na mekaar kyk en met mekaar verskil is juis dit wat vertel van ons volwassenheid in Christus. “Die kriterium waarmee julle oordeel, sal ook vir julle self gebruik word” (Matteus 7:2)1. Gelowiges vanuit verskillende kerklike agtergronde, met verskillende dogmatiese tradisies en oortuigings, aanbid en dien die Here saam in 'n geloofsgemeenskap sonder enige teologiese spanning. Terwyl daar ruimte gebied word vir verskeie denkrigtings en elkeen se eie pad met God gebied word, gaan dit vir elke gelowige om 'n verhouding met God deur Jesus Christus en die leiding van die Heilige Gees. Verder gaan dit oor verhoudings tussen medegelowiges en 'n missionale praksis2 in die gemeenskap. Volgens Barna verlaat miljoene gelowiges die denominasies en tradisionele gemeentes (2005:11) omdat hulle gefrustreerd geraak het met die beheer binne die onbuigbare mensgemaakte strukture, sisteme en tradisies. Die bedanking van 'n paar honderd gelowiges vanuit die hoofstroom denominasies, net in George alleen, waaronder daar 'n hele aantal voltydse werkers, kerkraadslede en aktiewe lidmate is, maak dit nodig dat die tradisionele manier van kerkwees heroorweeg word. Die Kerk 24/7-beweging wat ontstaan het rondom predikante met Pinkster en Gereformeerde agtergronde, bied 'n geloofsgemeenskap vir dié wat saam met Barna se miljoene, die denominasies verlaat het. Die Beweging besef dat dit deel is van 'n postmoderne omgewing waarin die Kerk besig is om te verander. Hierdie beweging is deel van die Ontluikende Kerk as fenomeen en nie as 'n organisasie wat deur sekere “emergants” of enige iemand anders gelei word nie. Hierdie studie beskryf die Ontluikende Kerk soos veral deur die oë van Barna, Gibbs & Bolger, en McLaren gesien. Dit omskryf ook die ondervindinge en betrokkenheid van veral drie predikante, Breedt, Badenhorst en Potgieter wat saam met ander gelowiges op soek is na God se wil vir die Kerk in 'n postmoderne omgewing. Gedurende die bestaan van drie en 'n half jaar het nog agt ander predikante en voltydse werkers vanuit die Charismatiese, Pinkster en Gereformeerde agtergronde betrokke geraak en is deel van die vorming van die huidige bedieningspraktyk van die Kerk 24/7-beweging. Die antwoorde van die respondente werp meer lig op die redes waarom die betrokke gelowiges hul denominasies en gemeentes verlaat het om hulle saam met ander wat dieselfde oortuigings deel, te “fellowship” en die Here dan so te dien. Hierdie kwalitatiewe studie is die navorser se bydrae om die siening en belewenis van die postmoderne Christen se kerklike ervarings binne sy leefwêreld te beskryf. Die ontstaan van die Kerk 24/7-beweging is volgens die navorser 'n antwoord op die behoefte van talle gelowiges om die Here buite die tradisionele kerkstrukture en sisteme te dien. / ABSTRACT: “First, the church isn’t ours; it’s God’s. And second, it isn’t ours; it’s us” (McLaren 2000:7). Whatever is said about the Church, how we function as the Body of Christ and how we approach the future, must always be done with McLaren’s quote in mind. The attitude with which we differ from each other, will always point to our maturity in Christ. “For in the way you judge, you will be judged; and by your standard of measure, it will be measured to you” (Matthew 7:2). Believers from different spiritual backgrounds and convictions fellowship together in a faith community without any theological tension. While the focus is on a relationship with God through the Holy Spirit, each person is allowed to minister as he or she feels led by the Holy Spirit. What is very important, is the relationship amongst fellow believers and a missional praxis within the community. According to Barna, millions of believers leave the denominations and traditional congregations because of the control within the human-made systems and structures. In George alone a few hundred believers, of which quite a number were full-time workers, left the mainstream denominations in the past four years. This definitely calls for a reconsidering of the traditional way of doing church. The Church 24/7 movement, which was started by pastors from Pentecostal and Reformed backgrounds, offers a faith community to those who left their congregations just as Barna’s millions. The Movement realizes that it finds itself in a postmodern environment where the church is constantly changing. The Church 24/7 movement forms part of the Emerging Church as phenomenon and is not an organization led by the emergants like Brian McLaren or any other leader. This study describes the Emerging Church as chiefly seen through the eyes of Barna, Gibbs & Bolger and McLaren. It also emphasizes the experiences and involvement of Breedt, Badenhorst and Potgieter who started the Movement together with fellow believers. During the past three and a half years, eight other Ministers and full-time workers from the Charismatic, Pentecostal and Reformed backgrounds became part of the exciting development of this ministry which day by day unfolds through the Holy Spirit’s inspiration. The answers given by the respondents help us to understand why believers left their traditional congregations to spontaneously get involved with this new way of thinking about God’s Church. This qualitative study is the contribution of the researcher to describe the experience and perception the postmodern Christian have of church life within this world. According to the researcher the rise of the Church 24/7 movement is an answer to the believers who long to serve God without the traditional church structures and systems.

Thesis (MSc)--Stellenbosch University, 2013. / Please refer to full text to view abstract.

Κάθε χρόνο τα άτομα που υποφέρουν από κάποιας μορφής νεφρική νόσο αυξάνονται παρά τις εξελίξεις στον τομέα της ιατρικής. Έχει παρατηρηθεί ότι η νεφρική νόσος, στις περισσότερες περιπτώσεις μπορεί να εξελιχθεί σε νεφρική ανεπάρκεια, είτε με πιο αργούς είτε με πιο γρήγορους ρυθμούς. Η νεφρική ανεπάρκεια αντιμετωπίζεται είτε με αιμοκάθαρση είτε με μεταμόσχευση. Το ανοσοποιητικό σύστημα διαδραματίζει σημαντικό ρόλο τόσο στην αντιμετώπιση όσο και στη πρόοδο των διάφορων μορφών νεφρικής νόσου. Ωστόσο, οι διάφοροι λεμφοκυτταρικοί τύποι, και ιδιαίτερα αυτοί της φυσικής ανοσίας, δεν έχουν μελετηθεί ιδιαίτερα και πολλές φορές από τις λίγες μελέτες που υπάρχουν προκύπτουν αντικρουόμενα αποτελέσματα. Η μελέτη μας επικεντρώθηκε στα Τ, στα ΝΚ και στα ΝΚ-Τ λεμφοκύτταρα. Επιλέξαμε να ερευνήσουμε αρχικά και τελικά στάδια νεφρικής νόσου. Έτσι οι ασθενείς κατηγοριοποιούνται σε τρεις ομάδες: ασθενείς με σπειραμαρονεφρίτιδα (αρχικό στάδιο), ασθενείς που υποβάλλονται σε αιμοκάθαρση και μεταμοσχευμένοι ασθενείς (τελικά στάδια). Σε κάθε πείραμα γίνεται σύγκριση με μια ομάδα ελέγχου (control, που αποτελείται από υγιή άτομα). Στην περίπτωση της σπειραματονεφρίδας παρατηρήθηκαν φυσιολογικά ποσοστά των λεμφοκυτταρικών τύπων και της έκφρασης του NKG2D υποδοχέα. Παρατηρήθηκε, όμως, αυξημένη έκφραση του TNF-α. Στην περίπτωση της αιμοκάθαρσης αν και παρατηρήθηκε μειωμένο ποσοστό ΝΚ και Τ κυττάρων, βρέθηκε ότι παρουσιάζουν αυξημένη κυτταροτοξικότητα και λειτουργικότητα. Αυτό φαίνεται και από την αύξηση στην έκφραση του CD107α και από την αύξηση στη συγκέντρωση του TNF-α. Όσον αφορά τα ΝΚ-Τ κύτταρα, αν και το ποσοστό τους είναι φυσιολογικό, εμφανίζουν αυξημένη έκφραση του υποδοχέα NKG2D. Τέλος, όσον αφορά την ομάδα των μεταμοσχευμένων ασθενών, δεν παρατηρήθηκε μεταβολή στο ποσοστό των Τ και των ΝΚ-Τ κυττάρων. Όταν όμως οι ασθενείς κατηγοριοποιούνται με βάση την φαρμακευτική αγωγή, το ποσοστό των ΝΚ-Τ κυττάρων είναι αυξημένο σε ασθενείς που τους χορηγείται κυκλοσπορίνη. Επίσης, η έκφραση του υποδοχέα NKG2D είναι φυσιολογική και στις δύο κατηγορίες λεμφοκυττάρων. Από την άλλη, αν και το ποσοστό των ΝΚ κυττάρων μειώνεται, αυτά εμφανίζουν φυσιολογική λειτουργικότητα και κυτταροτοξικότητα, όπως φαίνεται από τη φυσιολογική έκφραση του NKG2D υποδοχέα, της πρωτεΐνης CD107α και του TNF-α. / Every year, people who suffer from some form of kidney disease are increasing despite advances in medicine. It has been observed that the kidney disease, in most cases might progress to renal failure, either slower or faster. The renal failure is treated either by hemodialysis or renal transplantation. The immune system plays an important role in the treatment and in the progression of various forms of renal disease. However, the various types of lymphocytes, and especially those of innate immunity have not been widely studied and often the few studies that exist result in conflicting results. Our study focused on T, NK and NK-T lymphocytes. We chose to investigate initial and final stages of renal disease. Patients were categorized into three groups: patients with glomerulonephritis (initial stage), patients on dialysis and transplanted patients (final stages). In each experiment patients were compared with a control group consisting of healthy individuals. In the case of glomerulonephritis, we observed normal percentages of the lymphocyte population examined and normal expression of the NKG2D receptor, as well as increased expression of TNF-α. In the case of hemodialysis, NK and T cell percentages were reduced, while NK cells exhibited enhanced cytotoxicity and functionality. This was shown by the increase in the expression of CD107α and by the increase in the concentration of TNF-α. Regarding the NK-T cells, although their percentage was normal, they showed increased expression of NKG2D receptor. Finally, concerning the group of transplanted patients, no change was observed in the percentage of T and NK-T cells. However, when patients were categorized based on the medication, the percentage of NK-T cells was increased in patients receiving cyclosporine. In addition, the expression of NKG2D receptor was normal on T and NK-T cells. On the other hand, although the percentage of NK cells was reduced, those cells exhibited normal functionality and cytotoxicity, as shown by the normal expression of NKG2D receptor, CD107α protein and TNF-α.

Ως θέμα της πραγματεύεται την Εργαστηριακή διερεύνηση των φυσικών και μηχανικών ιδιοτήτων των μαλακών βράχων και των αμμωδών εδαφών με εξέταση χαρακτηριστικών παραδειγμάτων αργιλομαργαϊκής σύστασης πετρωμάτων καθώς και τις τεχνικογεωλογικές συνθήκες κατά τη διάνοιξη της οδικής σήραγγας του Πλατάνου. Πραγματοποιήθηκε δειγματοληψία από το μέτωπο εκσκαφής της σήραγγας του Πλατάνου και χρησιμοποιήσαμε 3 δείγματα για τις εργαστηριακές δοκιμές. / -

MicroRNAs (miRNAs) are a diverse and evolutionarily conserved class of non-coding RNAs that play a multitude of roles in many branches of eukaryotic biology. The regulation of miRNAs is dynamically controlled both spatially and temporally, and the expression of miRNAs can be modulated at the level of transcription or at points downstream of the miRNA maturation process. A relevant example of post-transcriptional miRNA regulation is the blockade of let-7 precursor miRNAs by Lin28 in embryonic stem cells. This pathway, which is initiated by the small RNA-binding protein Lin28, recruits the terminal uridyl transferase (TUTase) Zcchc11 to add a non-templated oligouridine tail to the miRNAs 3' end, and signals it for degradation by the cytoplasmic exonuclease Dis3l2. The Lin28/let-7 axis is essential for development and metabolic homeostasis, and is reactivated in a subset of human cancers. This thesis describes the biochemical mechanism underlying Lin28-mediated degradation of let-7, as well as a novel role for Zcchc11 and the related TUTase Zcchc6 in targeting mature developmental miRNAs in a Lin28-independent manner.

NADPH-cytochrome P450 reductase (CPR) is a flavoprotein containing both FAD and FMN and functions as the electron donor protein for several oxygenase enzymes found on the endoplasmic reticulum of eukaryotic cells, including cytochrome P450s involved in drug metabolism and cholesterol biosynthesis. As many as three enzymes in the cholesterol biosynthetic pathway have been demonstrated, or proposed, to use CPR as a redox partner: squalene monooxygenase, which converts squalene to 2,3-oxidosqualene; lanosterol demethylase, a cytochrome P450 (CYP51); and 7-dehydrocholesterol reductase, the final step in cholesterol synthesis. In yeast CPR can be replaced by the NADH-cytochrome b5 pathway, but this has not been demonstrated in animals or plants. My studies with hepatic cytochrome P450 reductase-null mice have revealed a second microsomal reductase for squalene monooxygenase that was not previously detected. Studies carried out with hepatocytes from CPR-null mice demonstrate that this second reductase is active in whole cells and leads to the accumulation of 24-dihydrolanosterol, indicating that lanosterol demethylation, catalyzed by CYP51, is blocked. These results demonstrate that this second reductase plays a significant role in supporting squalene monooxygenase but not cytochrome P450-mediated reactions. 7-Dehydrocholesterol reductase (E.C. 1.3.1.21) catalyzes the reduction of the 7-8 double bond of 7-dehydrocholesterol to yield cholesterol. It has been suggested that cytochrome-P450 reductase is required for this reaction. My studies show that 7-dehydrocholesterol reductase is enzymatically active in CPR-null microsomes, with activity equal to or greater than that found in preparations from wild-type mice. Mammalian cytochrome b5, which can accept electrons from either cytochrome P450 reductase or NADH-cytochrome b5 reductase, is known to be involved in augmenting some P450-dependent monooxygenase reactions. Cytochrome P450 2E1 has been found to exhibit reasonable rates of turnover via an NADHcytochrome b5 pathway in reconstituted enzyme systems and in heterologous hosts. Using microsomes from hepatic CPR-null mice, I have determined that NADH-dependent CYP2E1 activity in the absence of NADPH-dependent activity constituted approximately 10% of CYP2E1 activity observed in microsomal preparations with NADPH from wild-type mice. However, little or no CYP2E1 activity could be detected in primary hepatocytes isolated from CPR-null mice.