279 resultados para GERMINAL


Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this article we describe and evaluate the process of conducting online survey research about the legal recognition of same-sex relationships (key findings from which we have reported elsewhere, see Harding and Peel, 2006). Our aim in so doing is to contribute to the growing generic literature on internet-based research methods (Nosek et al., 2002; Rhodes et al., 2003; Stern, 2003; Strickland et al., 2003; Thomas et al., 2000) to the research methods literature within lesbian, gay, bisexual, trans and queer (LGBTQ) psychologies (Fish, 2000; Morris and Rothblum, 1999; Meezan and Martin, 2003; Mustanski, 2001) and also to extend the germinal literature focusing on internet research with non-heterosexual groups (Elford et al., 2004; Ellis et al., 2003; Ross et al., 2000). We begin by discussing the process of developing the online survey tool, before outlining the experience of the survey ‘going live’ and providing details of who completed the survey. We conclude by exploring some of the positives and pitfalls of this type of research methodology.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this article, the authors analyze participants' accounts of why they took part in a repeat-interview study exploring newly diagnosed patients' perceptions of diabetes service provision in Lothian, Scotland. The study involved three semistructured in-depth interviews with each patient (N = 40), which spanned a year. The authors provide a thematic discursive analysis of responses to the question, Can I ask you what made you decide to part in the study and why you've stayed involved over the past year? The main themes are (a) recruitment within health contexts ("the nurse said it would help"), (b) altruism ("if it can help somebody"), (c) qualitative research being seen as inherently innocuous ("nothing to lose"), and (d) therapeutic aspects of interviewing ("getting it off my chest"). The analysis contributes both to the qualitative literature about generic research participation and to a germinal literature exploring qualitative health research participation. © 2006 Sage Publications.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

An investigation was made into the nature and control of the annual reproductive cycle of the dace, Leuciscus leuciscus. It includes 1) a study of the natural reproductive cycle, 2) the use of Carp Pituitary Extract (CPE) to induce final maturation and ovulation in captive fish, 3) the effect of artificial light treatments on ovarian development and 4) the measurement of serum melatonin levels under different photoperiod regimes. Ovarian development was monitored by endocrinological data, notably serum cycles of 17-oestradiol (E2), testosterone (T), and calcium (as an index of vitellogenin), oocyte diameter, the gonadosomatic index and histological studies of the ovary. Under natural conditions, ovarian development can broadly be divided into 4 stages: 1) oogenesis which occurs immediately after spawning; 2) a primary growth phase (previtellogenic growth) prevalent between spawning and June; 3) a secondary growth phase (yolk vesicle plus vitellogenic growth) occurring between June and December and 4) final maturation and ovulation which occurs in mid-March. During the annual ovarian cycle, the sex steroids E2 and T showed two clear elevations. The first occurred initially in April followed by a rise in serum calcium levels. This subsequently initiated the appearance of yolk granules in the oocytes in June. The second rise occurred in September and levels were maintained until December, after which there was a decline in serum E2 levels. It is proposed that in the dace, high serum E2 levels between September and December were required to maintain vitellogenin production and therefore its uptake into the developing oocytes which occurred during this time, albeit at a slower rate than in the summer months. After December, prior to final maturation, whereas serum E2 and calcium levels declined, serum T levels remained elevated. In captivity, final maturation beyond the germinal vesicle migration stage failed to occur suggesting that the stimuli required for these events were absent. However ovulation could be induced by a single injection of CPE, which induced ovulation between 6 and 14 hours after treatment. Endocrine events associated with the artificial induction of spawning included a rise in serum levels of E2, T and the maturation inducing steroid 1720-dihydroxy progesterone. Photoperiodic manipulation demonstrated that whereas short or increasing daylengths were stimulatory to ovarian development, long days delayed development. Changes from long to short and constant short daylengths early in the reproductive cycle advanced maturation (up to 5 months), suggesting that the stimulus for ovarian development and maturation was a short day. However, experiments conducted later in the reproductive cycle demonstrated that only a simulated ambient photoperiod could induce final maturation. It is proposed therefore that under natural conditions the environmental stimulus for ovarian development and final maturation are short and increasing daylengths respectively. Further support that photoperiod is the dominant timing cue in this species was provided by the pattern of serum melatonin levels. Under different photoperiod treatments, serum melatonin, which is believed to be the chemical transducer of photoperiodic information (similar to other photoperiodic species) was elevated for the duration of the dark phase, indicating that the dace at least has the ability to `measure' changes in daylength.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study aimed to evaluate different concentrations of kisspeptin, as well as the interaction of kisspeptin and FSH/LH in vitro maturation and oocyte competence in cattle. In Experiment 1 was determined the minimum concentration of Kisspeptin (Kp) to be used, and in Experiment 2 was evaluated its interection with FSH and LH. The oocytes were collected in a commercial slaughterhouse and only Grade I oocytes were utilized. The oocytes were cultured in TCM-199 medium with bicarbonate plus 10% FBS, sodium pyruvate (22μg/mL), amikacin (83mg/mL), FSH (0.5μg/mL), with different concentrations of Kp, the treatments were: FSH + 0M Kp-10; FSH + 10-7M Kp-10, FSH + 10-6M Kp-10; FSH + 10-5M Kp-10. In Experiment 2, was used better concentration of Kp found in Experiment 1, the following treatments: no hormones; FSH; FSH + Kp-10; FSH + LH; FSH, LH + Kp-10; Kp-10. The oocyte competence was determined by nuclear maturation, mitochondrial distribution, MitoTracker® Orange CMTMRos fluorescence intensity and DCF. The evaluation of nuclear maturation was made after 24 hours incubation and the oocytes were stained with DAPI to determine the nuclear stage (Germinal Vesicle-GV, Metaphase I-MI and Metaphase II-MII).The mitochondrial distribution was classified as peripheral/semiperipheral and diffuse in clusters/granules, evaluated after stained with the MitoTracker® Orange CMTMRos, and was also identified the intensity of it. To determine the intensity of ROS oocytes were stained with DCF. The statistical analysis was performed by SAS GLIMMIX PROC. In Experiment 1 oocytes matured only with the FSH reached a smaller nuclear maturation when compared to those who were matured with Kisspeptin at different concentrations (FSH:13/33; FSH + 10-7M Kp-10: 28/35; FSH + 10-6M Kp-10:30/34; FSH + 10-5M Kp-10:28/32; P=0,0001). There was no statistical difference in mitochondrial distribution between treatments (P>0.05). The fluorescence intensity of MitoTracker did not differ among treatments (P>0.05). The DCF fluorescence intensity was lower when the concentration of Kp was increased in the medium (FSH:12177726,1; FSH + 10-7M Kp-10:10945982,83; FSH + 10-6M Kp-10:9820536,53; FSH + 10-5M Kp-10:9147016,38; P<0,0001). Based in the Experiment 1 results, the concentration of Kp was determined in 10-7M. In Experiment 2 the mitochondrial distribution was different between treatments, because oocytes matured only with Kp or FSH+LH, reached a oocyte competence greater than those maturated with FSH only or without hormone addition (no hormones:66,66%; FSH:66,66%; FSH + Kp-10:75,86%; FSH + LH:91,17%; FSH, LH + Kp-10:82,85%; Kp-10:91,17%; P<0,05). The no hormones resulted in a lower nuclear maturation than the other treatments (no hormones: 5/18; FSH:18/32; FSH + Kp-10:22/29; FSH + LH:26/33; FSH, LH + Kp-10:26/34; Kp-10:25/34; P=0,0094). The fluorescence intensity of probes MitoTracker and DCF was lower when Kp was added to the maturation medium (no hormones:1228363/540069; FSH:2307984/1395751; FSH + Kp-10:1941890/1114948; FSH + LH:2502145/1722376; FSH, LH + Kp-10:2286173/1467782; Kp-10:1859411/979325 P<0,0001). So this is the first study that shows that Kisspeptin stimulates oocyte maturation without the presence of gonadotropins in the maturation medium.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study emerged and founded itself with the aim to analyze the position taken by the family – and the implications in this subjective area – in attending children and adolescents in a Childhood Psychosocial Care Center (CAPSi). A secondary goal has come up as the comprehension surrounding the institutional representation made about the family and the service offered to children, adolescents and relatives. For such, the historical perspective on the relation between the State (laws and institutions) and the family was resumed, and the understanding of how it was reconciled by the medical knowledge and attended the ideological and political means. The social and ideological transformations of the 20th century culminated in the need of change required by the Psychiatric Reform and the achievement of patients on the right to return home and to their families. This new situation, permeated by the attempt of building an assistance model in Mental Health, presented a peculiarity–the close relationship between family and Mental Health services. The observations and conversations at CAPSi that were the investigation objects in this research, intended to learn on the quotidian of families and the possible treatment alternatives that would take into account the family circumstances. Conceiving the status of the families in Mental Health services is a germinal matter yet to be adjusted among the active knowledge in the post-Reform devices. The discussion about the family bonds, anchored in the theoretical perspective of Binding Psychoanalysis brought up elementary concepts such as psychic heritage, denial pact, unconscious alliances, the familiar psychic set, among other. The concept of family organizer helped to think of the family trajectories and stablishes a sort of identity for the family, as well as interferes in the establishment of its boundaries. The family path within the institution, as well as the status they establish facing the institutional approach, reflect the ghosts and the organizers shared by the group-family. It follows that the family is an important protagonist to be considered in the current therapeutic and political processes and, thus, is key to welcome the family bonds for the alliances act over the affective destinations, as well as try to remain sealed from the proposed changes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

CD4+ T cells play a crucial in the adaptive immune system. They function as the central hub to orchestrate the rest of immunity: CD4+ T cells are essential governing machinery in antibacterial and antiviral responses by facilitating B cell affinity maturation and coordinating the innate and adaptive immune systems to boost the overall immune outcome; on the contrary, hyperactivation of the inflammatory lineages of CD4+ T cells, as well as the impairments of suppressive CD4+ regulatory T cells, are the etiology of various autoimmunity and inflammatory diseases. The broad role of CD4+ T cells in both physiological and pathological contexts prompted me to explore the modulation of CD4+ T cells on the molecular level.

microRNAs (miRNAs) are small RNA molecules capable of regulating gene expression post-transcriptionally. miRNAs have been shown to exert substantial regulatory effects on CD4+ T cell activation, differentiation and helper function. Specifically, my lab has previously established the function of the miR-17-92 cluster in Th1 differentiation and anti-tumor responses. Here, I further analyzed the role of this miRNA cluster in Th17 differentiation, specifically, in the context of autoimmune diseases. Using both gain- and loss-of-function approaches, I demonstrated that miRNAs in miR-17-92, specifically, miR-17 and miR-19b in this cluster, is a crucial promoter of Th17 differentiation. Consequently, loss of miR-17-92 expression in T cells mitigated the progression of experimental autoimmune encephalomyelitis and T cell-induced colitis. In combination with my previous data, the molecular dissection of this cluster establishes that miR-19b and miR-17 play a comprehensive role in promoting multiple aspects of inflammatory T cell responses, which underscore them as potential targets for oligonucleotide-based therapy in treating autoimmune diseases.

To systematically study miRNA regulation in effector CD4+ T cells, I devised a large-scale miRNAome profiling to track in vivo miRNA changes in antigen-specific CD4+ T cells activated by Listeria challenge. From this screening, I identified that miR-23a expression tightly correlates with CD4+ effector expansion. Ectopic expression and genetic deletion strategies validated that miR-23a was required for antigen-stimulated effector CD4+ T cell survival in vitro and in vivo. I further determined that miR-23a targets Ppif, a gatekeeper of mitochondrial reactive oxygen species (ROS) release that protects CD4+ T cells from necrosis. Necrosis is a type of cell death that provokes inflammation, and it is prominently triggered by ROS release and its consequent oxidative stress. My finding that miR-23a curbs ROS-mediated necrosis highlights the essential role of this miRNA in maintaining immune homeostasis.

A key feature of miRNAs is their ability to modulate different biological aspects in different cell populations. Previously, my lab found that miR-23a potently suppresses CD8+ T cell cytotoxicity by restricting BLIMP1 expression. Since BLIMP1 has been found to inhibit T follicular helper (Tfh) differentiation by antagonizing the master transcription factor BCL6, I investigated whether miR-23a is also involved in Tfh differentiation. However, I found that miR-23a does not target BLIMP1 in CD4+ T cells and loss of miR-23a even fostered Tfh differentiation. This data indicate that miR-23a may target other pathways in CD4+ T cells regarding the Tfh differentiation pathway.

Although the lineage identity and regulatory networks for Tfh cells have been defined, the differentiation path of Tfh cells remains elusive. Two models have been proposed to explain the differentiation process of Tfh cells: in the parallel differentiation model, the Tfh lineage is segregated from other effector lineages at the early stage of antigen activation; alternatively, the sequential differentiation model suggests that naïve CD4+ T cells first differentiate into various effector lineages, then further program into Tfh cells. To address this question, I developed a novel in vitro co-culture system that employed antigen-specific CD4+ T cells, naïve B cells presenting cognate T cell antigen and BAFF-producing feeder cells to mimic germinal center. Using this system, I were able to robustly generate GC-like B cells. Notably, well-differentiated Th1 or Th2 effector cells also quickly acquired Tfh phenotype and function during in vitro co-culture, which suggested a sequential differentiation path for Tfh cells. To examine this path in vivo, under conditions of classical Th1- or Th2-type immunizations, I employed a TCRβ repertoire sequencing technique to track the clonotype origin of Tfh cells. Under both Th1- and Th2- immunization conditions, I observed profound repertoire overlaps between the Teff and Tfh populations, which strongly supports the proposed sequential differentiation model. Therefore, my studies establish a new platform to conveniently study Tfh-GC B cell interactions and provide insights into Tfh differentiation processes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The advent of next-generation sequencing, now nearing a decade in age, has enabled, among other capabilities, measurement of genome-wide sequence features at unprecedented scale and resolution.

In this dissertation, I describe work to understand the genetic underpinnings of non-Hodgkin’s lymphoma through exploration of the epigenetics of its cell of origin, initial characterization and interpretation of driver mutations, and finally, a larger-scale, population-level study that incorporates mutation interpretation with clinical outcome.

In the first research chapter, I describe genomic characteristics of lymphomas through the lens of their cells of origin. Just as many other cancers, such as breast cancer or lung cancer, are categorized based on their cell of origin, lymphoma subtypes can be examined through the context of their normal B Cells of origin, Naïve, Germinal Center, and post-Germinal Center. By applying integrative analysis of the epigenetics of normal B Cells of origin through chromatin-immunoprecipitation sequencing, we find that differences in normal B Cell subtypes are reflected in the mutational landscapes of the cancers that arise from them, namely Mantle Cell, Burkitt, and Diffuse Large B-Cell Lymphoma.

In the next research chapter, I describe our first endeavor into understanding the genetic heterogeneity of Diffuse Large B Cell Lymphoma, the most common form of non-Hodgkin’s lymphoma, which affects 100,000 patients in the world. Through whole-genome sequencing of 1 case as well as whole-exome sequencing of 94 cases, we characterize the most recurrent genetic features of DLBCL and lay the groundwork for a larger study.

In the last research chapter, I describe work to characterize and interpret the whole exomes of 1001 cases of DLBCL in the largest single-cancer study to date. This highly-powered study enabled sub-gene, gene-level, and gene-network level understanding of driver mutations within DLBCL. Moreover, matched genomic and clinical data enabled the connection of these driver mutations to clinical features such as treatment response or overall survival. As sequencing costs continue to drop, whole-exome sequencing will become a routine clinical assay, and another diagnostic dimension in addition to existing methods such as histology. However, to unlock the full utility of sequencing data, we must be able to interpret it. This study undertakes a first step in developing the understanding necessary to uncover the genomic signals of DLBCL hidden within its exomes. However, beyond the scope of this one disease, the experimental and analytical methods can be readily applied to other cancer sequencing studies.

Thus, this dissertation leverages next-generation sequencing analysis to understand the genetic underpinnings of lymphoma, both by examining its normal cells of origin as well as through a large-scale study to sensitively identify recurrently mutated genes and their relationship to clinical outcome.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Translocations in myeloma are thought to occur solely in mature B cells in the germinal center through class switch recombination (CSR). We used a targeted captured technique followed by massively parallel sequencing to determine the exact breakpoints in both the immunoglobulin heavy chain (IGH) locus and the partner chromosome in 61 presentation multiple myeloma samples. The majority of samples (62%) have a breakpoint within the switch regions upstream of the IGH constant genes and are generated through CSR in a mature B cell. However, the proportion of CSR translocations is not consistent between cytogenetic subgroups. We find that 100% of t(4;14) are CSR-mediated; however, 21% of t(11;14) and 25% of t(14;20) are generated through DH-JH recombination activation gene-mediated mechanisms, indicating they occur earlier in B-cell development at the pro-B-cell stage in the bone marrow. These 2 groups also generate translocations through receptor revision, as determined by the breakpoints and mutation status of the segments used in 10% and 50% of t(11;14) and t(14;20) samples, respectively. The study indicates that in a significant number of cases the translocation-based etiological events underlying myeloma may arise at the pro-B-cell hematological progenitor cell level, much earlier in B-cell development than was previously thought.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The pathogenesis of diffuse large B-cell lymphoma (DLBCL) remains partially unknown. The analysis of the B-cell receptor of the malignant cells could contribute to a better understanding of the DLBCL biology. We studied the molecular features of the immunoglobulin heavy chain (IGH) rearrangements in 165 patients diagnosed with DLBCL not otherwise specified. Clonal IGH rearrangements were amplified according to the BIOMED-2 protocol and PCR products were sequenced directly. We also analyzed the criteria for stereotyped patterns in all complete IGHV-IGHD-IGHJ (V-D-J) sequences. Complete V-D-J rearrangements were identified in 130 of 165 patients. Most cases (89%) were highly mutated, but 12 sequences were truly unmutated or minimally mutated. Three genes, IGHV4-34, IGHV3-23, and IGHV4-39, accounted for one third of the whole cohort, including an overrepresentation of IGHV4-34 (15.5% overall). Interestingly, all IGHV4-34 rearrangements and all unmutated sequences belonged to the nongerminal center B-cell-like (non-GCB) subtype. Overall, we found three cases following the current criteria for stereotyped heavy chain VH CDR3 sequences, two of them belonging to subsets previously described in CLL. IGHV gene repertoire is remarkably biased, implying an antigen-driven origin in DLBCL. The particular features in the sequence of the immunoglobulins suggest the existence of particular subgroups within the non-GCB subtype.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BACKGROUND AND OBJECTIVES: Analysis of IgH rearrangements in B-cell malignancies has provided clinical researchers with a wide range of information during the last few years. However, only a few studies have contributed to the characterization of these features in multiple myeloma (MM), and they have been focused on the analysis of the expressed IgH allele only. Comparison between the expressed and the non-functional IgH alleles allows further characterizion of the selection processes to which pre-myeloma cells are submitted. DESIGN AND METHODS: We analyzed a cohort of 84 untreated MM patients in order to characterize their functional VDJH and non-functional DJH rearrangements. The pattern of mutations and gene segment usage for both types of rearrangements was analyzed by polymerase chain reaction and sequencing. RESULTS: VH3 and VH1 family members were over- and under-represented, respectively. VH3-30 and VH3-15 segments were the most frequently used, whereas VH4-34 was found only in non-functional or heavily mutated VDJH rearrangements. DH2 and DH3 family members were over-represented in both VDJH and DJH repertoires, while the DH1 family was under-represented only in the productive VDJH rearrangements. Finally, DH3-22 and DH2-21 gene segments were found to be over-represented in the functional repertoire while segments commonly used by less mature B-cell malignancies, such as DH6-19 or DH3-3, were under-represented. INTERPRETATION AND CONCLUSIONS: Data reported here help to identify the clonogenic MM cell as a post-germinal center B cell that has undergone selection processes during the germinal center reaction.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tese de Doutoramento, Ciências Agrárias (Reprodução Animal), 26 de Junho de 2013, Universidade dos Açores.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Estudos baseados nas características testiculares estão altamente relacionados com a eficiência reprodutiva de varias espécies. Assim, o projeto desenvolvido teve como objetivo identificar as células do epitélio seminífero, caracterizar histologicamente suas associações, que formam os estádios, e determinar a frequência destes. Os fragmentos de testículos, com 30, 45, 60, 75, 90, 105, 120, 150 dias foram coletados no Centro de Multiplicação da Universidade Federal Rural do Semi-Árido (UFERSA), Mossoró/ RN. Passando pelos processos de fixação, lavagens em soluções de concentrações crescentes de álcoois (70-100%), desidratação em xilol, inclusão em Histosec®, preparação das lâminas histológicas, colorações em Hematoxilina e Eosina (HE) e suas fotomicrografias para a caracterização dos núcleos celulares do epitélio germinativo e a definição dos oitos estágios do ciclo do epitélio seminífero (CES) baseados no Método da Morfologia Tubular. Das faixas etárias analisadas todos os animais de 90-150 dias de idade apresentaram todos os estádios do CES. Os estádios I e III foram os que apresentaram maior e menor freqüência, respectivamente. Os animais caracterizados como pré-púberes (30 dias), púberes (45-90 dias de idade) e pós-púberes (105150 dias de idade) apresentaram os estádios I, VIII e IV com uma maior freqüência, respectivamente.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Biologia Celular, Pós-Graduação em Biologia Molecular, 2016.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

T follicular helper (Tfh) cells support differentiation of B cells to plasma cells and high affinity antibody production in germinal centers (GC) and Tfh differentiation requires the function of B cell lymphoma 6 (Bcl6). We have now discovered that early growth response gene (Egr) 2 and 3 directly regulate the expression of Bcl6 in Tfh cells which is required for their function in regulation of GC formation. In the absence of Egr2 and 3, the expression of Bcl6 in Tfh cells is defective leading to impaired differentiation of Tfh cells resulting in a failure to form GCs following virus infection and defects in production of anti-viral antibodies. Enforced expression of Bcl6 in Egr2/3 deficient CD4 T cells partially restored Tfh differentiation and GC formation in response to virus infection. Our findings demonstrate a novel function of Egr2/3 which is important for Tfh cell development and Tfh cell mediated B cell immune responses.