A new method for the study of essential fatty acid requirements in fish larvae

This study describes a methodology with potential application in the estimation of essential fatty acid (EFA) requirements of fish larvae. Senegalese sole (Solea senegalensis) larvae were fed, from 16 days after hatching (DAH), on Artemia enriched with different oils, inducing graded dietary concentrations of DHA: (1) soyabean oil, containing no measurable amounts of DHA (NDHA); (2) fish oil, inducing a medium DHA level (MDHA, 3 g DHA/100 g fatty acids); and (3) a mixture of Easy DHA Selco and Microfeed, resulting in high DHA content (HDHA, 8 g/100 g). At 28 DAH a metabolic trial was conducted where larvae were tube fed [1-(14) C]DHA, in order to determine its absorption, retention in the gut and body tissues, as well as its oxidation. At 23 DAH the HDHA treatment induced a significantly higher larval growth, while at 32 DAH significant differences were only found between the NDHA and HDHA treatments. The absorption of tube-fed [1-(14) C]DHA was extremely high (94-95%) and independent of feeding regime. However, in larvae fed NDHA Artemia, a significantly higher amount of label was retained in the gut compartment and a concurrently lower retention was measured in the body. A significantly higher proportion of the absorbed DHA label was oxidized in larvae fed HDHA, compared to NDHA. Based on these results, we suggest that increasing dietary supply of DHA above the larval requirement level results in its increased oxidation for energy purposes and we propose potential applications of the tube feeding methodology using radiolabelled EFA in conjunction with dose-response studies.'Fundacao para a Ciencia e a Tecnologia', Portugal [SFRH/BD/4902/2001]; FEDER, European Commission [PROMAR/SP5.P117/03

"Constructing Long and Dense Time-Series of Inequality Using the Theil Index"

Year-to-year economy-wide measures of income distribution, such as the Gini coefficient, are rarely available for long periods except in a few developed countries, and as a result few analyses of year-to-year changes in inequality exist. But wage and earnings data by industrial sectors are readily available for many countries over long time frames. This paper proposes the application of the between-group component of the Theil index to data on wages, earnings, and employment by industrial classification in order to measure the evolution of wage or earnings inequality through time. We provide formal criteria under which such a between-group Theil statistic can reasonably be assumed to give results that also track the (unobserved) evolution of inequality within industries. While the evolution of inequality in manufacturing earnings cannot be taken as per se indicating the larger movements of inequality in household incomes, including those outside the manufacturing sector, we argue on theoretical grounds that the two will rarely move in opposite directions. We conclude with an empirical application to the case of Brazil, an important developing country for which economy-wide Gini coefficients are scarce, but for which a between-industries Theil statistic may be computed on a monthly basis as far back as 1976.

Exploring The Relationship Between Learning Style And Critical Thinking In An Online Course

As online courses become more widespread in adult education programs, adult educators begin to explore teaching strategies that effectively facilitate student learning based on different learning styles. One teaching strategy commonly used in online courses to develop adult learners’ critical thinking skills is the discussion forum. Using online discussion forums in courses, often some students lack effective strategies for participating in discussion forums in courses. Therefore, this study explores the relationship between learning style and critical thinking in an online course that used discussion forums and concept maps as teaching strategies. Learning strategies used by students in the course were assessed using a Kolb-based learning style inventory. Students’ critical thinking skills were assessed by asking them to create concept maps of the reading materials and discussions in the course. Findings of this study show that there was no relationship between learning style and critical thinking; however, it suggests that individual factors (learner’s competency using concept map software, learner’s motivation about topics discussed, and individual learning style) and group factors (combination of learning styles in a group and group facilitation) influenced the ability of students to demonstrate successful critical thinking skills in the course. As online courses become more prevalent in adult education programs, adult educators explore teaching strategies that more effectively facilitate student learning based on different learning styles. A variety of teaching strategies for the online environment have been offered to practitioners in articles and books; however, few studies examine these teaching strategies based on student learning styles. One teaching strategy that is commonly used in online courses is the discussion forum. In an online discussion forum, a group of learners engages in a computer-mediated interchange of ideas through e-mail, chat, or bulletin board technology. As in a face-to-face discussion, each message is seen by all members of the group, but the lack of direct personal contact presents certain challenges. In my experience with discussion forums in courses, I have observed that some students lack effective strategies for participating in this activity. Therefore, as part of my Scholarship of Teaching and Learning (SoTL) research, I proposed to explore the relationship between learning style and critical thinking in an online course that uses discussion forums and concept maps as teaching strategies. My initial conjecture was that certain learning strategies would help learners be more successful in online discussion forums. To study this issue, I offered an Internet-based course using online discussion forums with the purpose of fostering learners’ critical thinking skills. The learning strategies used by students in the course were assessed using a Kolb-based learning style indicator. Students’ critical thinking skills were assessed by asking them to create concept maps of the reading materials and discussions in the course

Genome-Wide Host Gene Expression Analysis Before and After the Initiation of Highly Active Antiretroviral Therapy And Natural Control of HIV in Therapy Naïve HIV+ Non-Progressors

Since its discovery 25 years ago, the HIV virus has infected more than 34 million people in the world; the infection caused by this virus has led the world to its most terrible pandemic, and the greatest global health crises of our times. The host-virus interaction and natural history of the disease are influenced by the distinctive interface the virus has with each infected individual. The infection with HIV-1 is characterized by the destruction of CD4+ T-cells during the typical course of the infection, but HIV has the arsenal to infect practically all the major blood leukocytes. Taken from these observations, it is apparent that HIV has the innate ability to subvert and manipulate the host gene machinery at the transcriptomic level. The highly active anti-retroviral therapy (HAART) consists of a combination of powerful drugs, which serve as potent defence mechanism against the ways in which the HIV virus attacks the human bod y. Although these drugs are not able to rid the body of HIV virus, they can significantly delay the onset of AIDS and reduce the incidence of opportunistic infections, morbidity and mortality related to HIV infection. After the introduction of HAART treatment, it is observed that most patients with good adherence respond to HAART, which is defined by a decrease of plasma viral load to undetectable levels and an immune reconstitution with a significant increase of CD4+ T cell levels. Around 30% of the patients fail to achieve this response and continue to express high plasma viral load and low CD4+ T cell numbers. In contrast, some rare HIV+ patients maintain below detectable levels of plasma viremia without the treatment. These are termed long-term nonprogressors(LTNPs), less commonly called elite controllers. These rare individuals are infected with HIV, but have the natural ability to control the infection with the strength of their immune system. Many of th ese patients have been HIV positive for 30 years or more and! off the rapy for the entire duration of their infection, showing high CD4+T cells counts and no progression to the disease. In this context, it is important to mention that the genomic basis of this natural effective immunological control of viremia in LTNPs, as opposed to drug-mediated control of HIV, remains unknown. The development of high throughput microarray platforms and bioinformatic platforms to visualize and analyse the complex dataset has enabled considerable progress in the field of viral genomics, and also the visualization of host-virus interactions at the molecular level. In chapter III, we carried out a comparative genome-wide (encompassing all 25,000 human genes) pharmacogenomic study using whole primary peripheral blood mononuclear cells (PBMC) derived from 14 HIV+ patients at two time points: pre-HAART (TP-1 with detectable viremia) and post (TP2: below detectable level (BDL) of plasma HIV <40 copies of HIV RNA/mL plasma), to ascertain how genomically distinct viremic phase is from the phase in which virus is fully controlled with HAART. Another goal was to define the underlying pharmacogenomic basis of HIV control during HAART. In the second study shown in Chapter IV, we compared the two time points against the 9 LTNPs to unravel the genomic basis of natural control of viremia in therapy naïve LTNPs showing below detectable levels of viremia (<20 copies of HIV RNA/mL plasma) and high and stable CD4+T cell counts. Genomic RNA extracted from the PBMCs was used in genome-wide microarray analysis, using HT-12v3 Illumina chips. Quantile normalization was performed to normalize the data and inter-patient variability. Illumina®BeadStudio Data Analysis Software wa s used to obtain differentially expressed (DE) genes. Only the significant genes with p value <0.01 and FDR of <5% (for the comparison between TP1 and TP2) and FDR <1% (for the comparison between LTNP vers us TP1 and LTNP versus TP2) were considered appropriate for ! analysis . Pathway analysis was performed in MetaCoreTM from GeneGo, Inc to derive functional annotations. Functionally significant genes were validated by quantitative real time PCR. Between TP1 and TP2, 234 genes were differentially expressed. Within these genes, 212 were down-regulated and 22 upregulated. Between the comparison between LTNP vs TP1, 965 genes were differently expressed (706 genes were up-regulated and 259 genes were down-regulated), and when LTNP was compared to the TP2 group, we found 1181 DE genes (with 727 genes up-regulated and 454 genes downregulated). In the first part of this study, comparing the TP1 and TP2 only, we found that of the top 10 pathways, 8 belonged to the immune response system. This was the most significant pathway up-regulated in TP1 when compared to TP2. This comprised of genes that were involved in antiviral action of interferon (IFN) and their signalling function, antiviral response, dendritic cell maturation a nd migration, and cell metabolism. Map folder and enrichment analysis corroborated with our findings, thereby confirming an intrinsic role of the immune, inflammatory and interferon response family-related genes during HIV viremia in the absence of treatment. But a closer examination of this contrast also showed a mirror down-regulation of genes involved in innate and adaptive immunity, inflammation, apoptosis and antiviral functions. This directly implies a functional relevance of these pathways, through their modulation in TP1 and TP2 stages. Although these data are intuitive and expected, such analysis has never been performed before. The second part of this study, on comparisons between LTNP and TP1 and LTNP against TP2, we show the first evidence demonstrating that the natural control of HIV in LTNP is guided by the genes enriched in the immune response, cytoskeleton remodelling, apoptosis and T cell signalling pathways. Another striking ob servation was that, even though the LTNP and TP2 groups maintai ned BDL of plasma viremia (<40 copies), the LTNP group was genomically distinct from the TP2, which controlled viremia with HAART. This highlights the qualitative distinction and critical role of enriched pathways in natural control of viremia in the LTNPs. Seventeen genes encompassing all these pathways were validated by q-PCR, which showed consistent trends between microarray and q-RT PCR. One gene in particular, the thrombospondin (THBS1) (R2= 0.942) was identified as a biomarker in our study, discriminating between viremic patients and LTNPs at the genomic (R2= 0.942, p<2.654e.08) and proteomic levels (p<0.003761). The levels of expression of THBS1 showed excellent correlation with plasma viremia (R2=0.81557;p<.0.0003761), the first description of such an important protein. This is the most unique finding of this work, which has significance in HIV disease prognostics and diagnostics, in addition to predicting the strength of the ho st immune system, as evident from its down-regulation and low expression in the natural controllers. Overall, through these analyses, we have shown that, although there are common set of key genes associated with HIV at all stages, each stage also showed unique molecular signatures. This was demonstrated with the identification of molecular signatures for the control of virus with HAART therapy, as well as for the natural control of HIV in LTNPs. Especially for the LTNPs, the downregulation of the apoptosis was the most significant feature, which may have important implications in therapy, especially in the context of using apoptosis as a target for future therapies

A Phenomenological Study of College Faculty Experiences Derived from Teaching in a Computer-Mediated Environment When There is an Absence of Physical Presence

This phenomenological study investigated the meaning of the online teaching experiences of college faculty when there was an absence of physical presence. Findings suggest that teaching online is work intensive because of the length of engagement before and during instruction and the depth of engagement during the delivery of a course; however, it is also rewarding when the instructor experiences satisfaction throughout the process of design and delivery of instruction

Myxobacteria-derived outer membrane vesicles as a drug delivery system to treat bacterial infections

Bacterial infections represent a serious risk to public health globally. The World Health Organization (WHO) estimated that infections of the lower respiratory tract were the fourth leading cause of death worldwide in 2019, killing 2.6 million people. One of the main causes of such numbers is the development of antibiotic resistance by bacteria, a process facilitated by the misuse of antibiotic compounds in humans and in animals. The employment of nanomedicine can be explored for the development of new nanocarriers that can be used for the treatment of those infections, such as extracellular vesicles (EVs) and, more specifically, outer membrane vesicles (OMVs) derived from myxobacteria, which are natural producers of antibacterial compounds. In this thesis, OMVs were isolated from the strains Cystobacter velatus Cbv34 and Cystobacter ferrugineus Cbfe23 and were characterized. The OMVs’ effects on mammalian cells were promising, eliciting no negative impact in biocompatibility, and not significantly stimulating the release of pro-inflammatory cytokines. The OMVs were also successfully internalized by mammalian cells, thus able to decrease the proliferation rate of intracellular Staphylococcus aureus. Moreover, the myxobacterial OMVs were able to detach biofilm from surfaces and prevent their growth in a model subjected to fluid flow. The findings of this study demonstrate the substantial potential of the use of myxobacterial OMVs for the treatment of bacterial infections.Bakterielle Infektionen sind eine globale Bedrohung der öffentlichen Gesundheit. Mit 2,6 Mio. Toten im Jahr 2019 hat die Weltgesundheitsorganisation Infektionen der unteren Atemwege mit als die vierthäufigste Todesursache eingeschätzt. Eine der Hauptursachen ist die von Bakterien entwickelte Antibiotikaresistenz, ein Prozess, der durch den Fehlgebrauch von Antibiotika bei Menschen und Tier vorangetrieben wird. Mit Hilfe der Nanomedizin können neue Trägersysteme entwickelt und für die Behandlung von Infektionen verwendet werden. Solche Partikel sind beispielsweise extrazelluläre Vesikel (EVs) oder genauer äußere Membranvesikel (OMVs) von Myxobakterien, welche als natürliche Produzenten antibiotischer Substanzen gelten. In dieser Arbeit wurden OMVs von den Stämmen Cystobacter velatus Cbv34 und Cystobacter ferrugineus Cbfe23 isoliert und charakterisiert. Die Wirkung von OMVs auf tierische Zellen war vielversprechend, da sie keinen negativen Einfluss auf die Biokompatibilität und keine signifikante Ausschüttung von proinflammatorischen Zytokinen bewirkt haben. Zudem wurden OMV erfolgreich von tierischen Zellen aufgenommen und waren daher fähig, die Proliferation von Staphylococcus aureus zu bremsen. Außerdem waren myxobakterielle OMV in einem Durchflussmodell in der Lage, Biofilm von Oberflächen zu lösen und deren Wachstum zu unterbinden. Die Erkenntnisse dieser Studie unterstreichen das Potential der Verwendung von myxobateriellen OMVs zur Behandlung bakterieller Infektionen

Transthyretin familial amyloid polyneuropathy impact on health-related quality of life

info:eu-repo/semantics/publishedVersio

Carbon formation on steam reforming catalysts

Imperial Users onl