Dependence of lymphopenia-induced T cell proliferation on the abundance of peptide/ MHC epitopes and strength of their interaction with T cell receptors

Factors that affect naïve T cell proliferation in syngeneic lymphopenic hosts were investigated. 2C T cell receptor (TCR) transgenic T cells lacking both CD8 and CD4 survived but hardly proliferated. Proliferation of CD8+ 2C cells was proportional to the abundance of cognate peptide/MHC complexes and was severely inhibited by injection of anti-CD8 antibody. Weakly reactive self-peptides slightly enhanced CD8+ 2C cell proliferation whereas a potent agonist peptide promoted much more rapid proliferation, but inflammation-stimulating adjuvant had only a small effect on the rate of cell proliferation. The findings suggest that under uniform lymphopenic conditions, the widely different rates of proliferation of T cells expressing various TCR, or the same TCR in the presence or absence of CD8, reflect the strength of interaction between TCR and MHC associated with particular self-peptides.

Catalytic efficiency and vitality of HIV-1 proteases from African viral subtypes

The vast majority of HIV-1 infections in Africa are caused by the A and C viral subtypes rather than the B subtype prevalent in the United States and Western Europe. Genomic differences between subtypes give rise to sequence variations in the encoded proteins, including the HIV-1 protease. Because some amino acid polymorphisms occur at sites that have been associated with drug resistance in the B subtype, it is important to assess the effectiveness of protease inhibitors that have been developed against different subtypes. Here we report the enzymatic characterization of HIV-1 proteases with sequences found in drug-naïve Ugandan adults. The A protease used in these studies differs in seven positions (I13V/E35D/M36I/R41K/R57K/H69K/L89M) in relation to the consensus B subtype protease. Another protease containing a subset of these amino acid polymorphisms (M36I/R41K/H69K/L89M), which are found in subtype C and other HIV subtypes, also was studied. Both proteases were found to have similar catalytic constants, kcat, as the B subtype. The C subtype protease displayed lower Km values against two different substrates resulting in a higher (2.4-fold) catalytic efficiency than the B subtype protease. Indinavir, ritonavir, saquinavir, and nelfinavir inhibit the A and C subtype proteases with 2.5–7-fold and 2–4.5-fold weaker Kis than the B subtype. When all factors are taken into consideration it is found that the C subtype protease has the highest vitality (4–11 higher than the B subtype) whereas the A subtype protease exhibits values ranging between 1.5 and 5. These results point to a higher biochemical fitness of the A and C proteases in the presence of existing inhibitors.

CD8+ T cells control the TH phenotype of MBP-reactive CD4+ T cells in EAE mice

Trimolecular interactions between the T cell antigen receptor and MHC/peptide complexes, together with costimulatory molecules and cytokines, control the initial activation of naïve T cells and determine whether the helper precursor cell differentiates into either T helper (TH)1 or TH2 effector cells. We now present evidence that regulatory CD8+ T cells provide another level of control of TH phenotype during further evolution of immune responses. These regulatory CD8+ T cells are induced by antigen-triggered CD4+ TH1 cells during T cell vaccination and, in vitro, distinguish mature TH1 from TH2 cells in a T cell antigen receptor Vβ-specific and Qa-1-restricted manner. In vivo, protection from experimental autoimmune encephalomyelitis (EAE) induced by T cell vaccination depends on CD8+ T cells, and myelin basic protein-reactive TH1 Vβ8+ clones, but not TH2 Vβ8+ clones, used as vaccine T cells, protect animals from subsequent induction of EAE. Moreover, in vivo depletion of CD8+ T cells during the first episode of EAE results in skewing of the TH phenotype toward TH1 upon secondary myelin basic protein stimulation. These data provide evidence that CD8+ T cells control autoimmune responses, in part, by regulating the TH phenotype of self-reactive CD4+ T cells.

How the protease thrombin talks to cells

How does a protease act like a hormone to regulate cellular functions? The coagulation protease thrombin (EC 3.4.21.5) activates platelets and regulates the behavior of other cells by means of G protein-coupled protease-activated receptors (PARs). PAR1 is activated when thrombin binds to and cleaves its amino-terminal exodomain to unmask a new receptor amino terminus. This new amino terminus then serves as a tethered peptide ligand, binding intramolecularly to the body of the receptor to effect transmembrane signaling. The irreversibility of PAR1’s proteolytic activation mechanism stands in contrast to the reversible ligand binding that activates classical G protein-coupled receptors and compels special mechanisms for desensitization and resensitization. In endothelial cells and fibroblasts, activated PAR1 rapidly internalizes and then sorts to lysosomes rather than recycling to the plasma membrane as do classical G protein-coupled receptors. This trafficking behavior is critical for termination of thrombin signaling. An intracellular pool of thrombin receptors refreshes the cell surface with naïve receptors, thereby maintaining thrombin responsiveness. Thus cells have evolved a trafficking solution to the signaling problem presented by PARs. Four PARs have now been identified. PAR1, PAR3, and PAR4 can all be activated by thrombin. PAR2 is activated by trypsin and by trypsin-like proteases but not by thrombin. Recent studies with knockout mice, receptor-activating peptides, and blocking antibodies are beginning to define the role of these receptors in vivo.

Regulatory function of in vivo anergized CD4+ T cells

It has been suggested that anergic T cells may not be only inert cells but may rather play an active role, for example by regulating immune responses. We have previously reported the existence of “anergic” IL-10-producing CD4+ T cells generated in vivo by continuous antigenic stimulation. Using a gene transfer system where the antigen recognized by such T cells is expressed in skeletal muscle by two different DNA viral vectors, we show that these cells not only remain tolerant toward their cognate antigen but also can suppress the immune response of naïve T cells against the immunogenic adenoviral proteins. Furthermore, they can completely inhibit tissue destruction that takes place as a result of an immune response. The system presented here is unique in that the T cells have been anergized in vivo, their antigen specificity and functional status are known, and the amount, form, and timing of antigen expression can be manipulated. This model will therefore permit us to carefully dissect the mechanisms by which these anergic T cells regulate the priming and/or effector function of naïve T cells.

How αβ T cells deal with induced TCRα ablation

On deletion of the gene encoding the constant region of the T cell antigen receptor (TCR)α chain in mature T cells by induced Cre-mediated recombination, the cells lose most of their TCR from the cell surface within 7–10 days, but minute amounts of surface-bound TCRβ chains are retained for long periods of time. In a situation in which cellular influx from the thymus is blocked, TCR-deficient naïve T cells decay over time, the decay rates being faster for CD8+ cells (t1/2 ≈ 16 days) than for CD4+ cells (t1/2 ≈ 46 days). TCR+ naïve cells are either maintained (CD8+) or decay more slowly (CD4+; t1/2 ≈ 78 days.) Numbers of TCR-deficient memory T cells decline very slowly (CD8+ cells; t1/2 ≈ 52 days) or not at all (CD4+ cells), but at the population level, these cells fail to expand as their TCR+ counterparts do. Together with earlier data on T cell maintenance in environments lacking appropriate major histocompatibility complex antigens, these data argue against the possibility that spontaneous ligand-independent signaling by the αβTCR contributes significantly to T-cell homeostasis.

Dominant-negative action of the jimpy mutation in mice complemented with an autosomal transgene for myelin proteolipid protein.

Mutations in genes encoding membrane proteins have been associated with cell death of unknown cause from invertebrate development to human degenerative diseases. A point mutation in the gene for myelin proteolipid protein (PLP) underlies oligodendrocyte death and dysmyelination in jimpy mice, an accurate model for Pelizaeus-Merzbacher disease. To distinguish the loss of PLP function from other effects of the misfolded protein, we took advantage of the X chromosomal linkage of the gene and have complemented jimpy with a wild-type PLP transgene. In this artificial heterozygous situation, the jimpy mutation emerged as genetically dominant. At the cellular level oligodendrocytes showed little increase in survival although endogenous PLP gene and autosomal transgene were truly coexpressed. In surviving oligodendrocytes, wild-type PLP was functional and immunodetectable in myelin. Moreover, compacted myelin sheaths regained their normal periodicity. This strongly suggests that, despite the presence of functional wild-type PLP, misfolded jimpy PLP is by itself the primary cause of abnormal oligodendrocyte death.

Igreja de N.Sra. da Candelária

A planta baixa é feita em forma de cruz latina com duas sacristias laterais acrescidas à planta original. A fachada em estilo pombalino é formada por sobreposição das ordens sendo duas no corpo da igreja e três nas torres. Os arremates destas são bulbosos e azulejados. A cúpula ocupa visualmente o espaço do triângulo frontão posicionado entre as torres que com as laterais formam sete tramos. Todo o frontispício, fachadas laterais e posterior são revestidos em granito. As portas de bronze são de autoria do escultor Teixeira Lopes executadas na cidade do Porto, Portugal, em 1901. Internamente apresenta influência italiana no revestimento em mármore contrariando a grande maioria das igrejas que são revestidas de madeira entalhada, à maneira portuguesa. O estuque de gesso nas abóbadas é trabalho de Bartolomeu Meira. As pinturas murais da cúpula, do teto da capela-mor e da nave são de autoria de Zeferino da Costa, Bernardelli, Oscar Pereira da Silva, Castagneto, Pinto Bandeira e outros, no século XIX e XX. Adentrar neste magnífico templo é ter a sensação da espiritualidade expressa em arte de maneira diferenciada inclusive daqueles templos barrocos coloniais. Exemplar ímpar da arte portuguesa influenciada diretamente na grandiosidade romana foi salva da destruição para a construção da avenida Presidente Vargas em 1940. Ganhou assim uma privilegiada perspectiva no frontispício com a praça Pio X e na parte posterior, sua silhueta elegante com a grande cúpula foi cenário de fundo do carnaval carioca durante décadas no século XX.

Igreja de N.Sra. do Carmo e Capela Real

A planta baixa é feita em forma de cruz latina com duas sacristias laterais acrescidas à planta original. A fachada em estilo pombalino é formada por sobreposição das ordens sendo duas no corpo da igreja e três nas torres. Os arremates destas são bulbosos e azulejados. A cúpula ocupa visualmente o espaço do triângulo frontão posicionado entre as torres que com as laterais formam sete tramos. Todo o frontispício, fachadas laterais e posterior são revestidos em granito. As portas de bronze são de autoria do escultor Teixeira Lopes executadas na cidade do Porto, Portugal, em 1901. Internamente apresenta influência italiana no revestimento em mármore contrariando a grande maioria das igrejas que são revestidas de madeira entalhada, à maneira portuguesa. O estuque de gesso nas abóbadas é trabalho de Bartolomeu Meira. As pinturas murais da cúpula, do teto da capela-mor e da nave são de autoria de Zeferino da Costa, Bernardelli, Oscar Pereira da Silva, Castagneto, Pinto Bandeira e outros, no século XIX e XX. Adentrar neste magnífico templo é ter a sensação da espiritualidade expressa em arte de maneira diferenciada inclusive daqueles templos barrocos coloniais. Exemplar ímpar da arte portuguesa influenciada diretamente na grandiosidade romana foi salva da destruição para a construção da avenida Presidente Vargas em 1940. Ganhou assim uma privilegiada perspectiva no frontispício com a praça Pio X e na parte posterior, sua silhueta elegante com a grande cúpula foi cenário de fundo do carnaval carioca durante décadas no século XX.

Igreja de N. Sr.ª da Lapa dos Mercadores

Dentre as igrejas construídas na densa malha urbana da antiga capital, esta se destaca por possuir um adro fechado – galilé -, local defronte do qual havia em 1740 um oratório para N.Sra. da Lapa dos Mascates. A beleza desta igreja se deve a diversos fatores: a exata colocação da torre única neoclássica ao final da rua que a emoldura; a luz intensa que jorra sobre a ornamentação tornando-a mais ampla; a combinação dos elementos arquitetônicos em um pequeno espaço com os arcos plenos formando a galilé, acima, janelas coloniais e relevos na frontaria com pedra de lioz; triângulo frontão clássico; volutas barrocas com perfis de santos – Adriano, Bernardo nos nichos e Félix , João da Mata acima - e coruchéus à maneira de Gian Lorenzo Bernini (1598- 1680), colocados em 1869 por Antônio de Pádua. Internamente mais surpresas: o espaço elíptico amplia a graciosa cúpula que eleva o olhar até o pequeno lanternim. A profundidade da capela-mor cria um contraponto direcional até o retábulo com duplo coroamento enfatizado pela seqüência de fontes de luzes advindas das alturas dos lanternins e tribunas.

Igreja de N. Sra.do Bonsucesso

De exterior severo, lembra a fachada da igreja conventual de Santo Antônio com a torre sineira com arcos plenos e óculo no triângulo frontão retilíneo, duas janelas e portada setecentista em pedra de lioz. O corpo da igreja é destacado por cunhais de cantaria. O interior da nave retangular profunda é decorado com quatro altares incrustados nas paredes em estilo rococó tardio de 1818. A capela-mór é bem iluminada por uma cúpula com lanternim em madeira sobre o presbitério. O altar-mor se destaca ao fundo dos dois amplos arcos com colunas lisas arrematadas por capitéis jônicos. Na ampla sacristia há pinturas em bandeiras que saíam em procissões e execuções capitais bem como o crucifixo que acompanhou Tiradentes para o seu enforcamento em 1792. Na sacristia se encontram pinturas como Aparição de N.Sra. de 1639, N.Sra. da Conceição de 1664 entre outras além das Bandeiras da Misericórdia.

Igreja da Ordem Terceira dos Mínimos de São Francisco de Paula

A rica fachada em cantaria apresenta frontão curvilíneo e torres com coroamento bulboso ainda com traços barrocos persistindo o acúmulo formal do eclétismo com elementos tanto europeus como coloniais. As imensas pilastras externas são duplas nas laterais e torres e a modenatura se adensa no corpo da igreja que exibe um pórtico clássico ladeado de portas com arcos plenos e acima no coro, janelas com vergas coloniais.. Internamente a pompa toma conta do ambiente sacro. A grandiosidade da nave única retangular é conseguida pela profundidade e verticalidade das dez colunas neoclássicas de ordem coríntia, dispostas par a par, tão colossais quanto aquelas da capela-mor que serviu de inspiração e por onde se iniciou a ornamentação. Os festões e guirlandas no meio do fuste das colunas da capela-mor são acréscimos posteriores a 1855. A ornamentação do arco-cruzeiro é mais contida e apresenta-se como elemento construtivo. A decoração interior mesmo sendo realizada no século XIX tem a grandiosidade barroca. Assim como a construção teve vários construtores também a talha contou com vários artífices que ornamentaram a nave. Foram eles: os entalhadores Pádua e Castro (1855-1865), Cláudio Manoel dos Reis e pelos escultores Chaves Pinheiro que executou as esculturas dos doze apóstolos em madeira e Almeida Reis modelou os baixos-relevos referentes a vida do santo protetor na nave. A ornamentação da capela-mor é atribuída também ao mestre Valentim, auxiliado pelo mestre carpinteiro Florêncio Machado. Esta foi sua última obra iniciada em 1801, terminada em 1813 e reformulada por Pádua Castro em 1855. Nesta ocasião se abriu o zimbório e ampliou-se as colunas do altar-mor, aumentando o trono na nova tribuna. Uma visita à pinacoteca da ordem terceira é surpreendente pois alí se encontram obras dos pintores Manuel da Cunha, José de Oliveira Rosa, Rafael Mendes Carvalho, Claude-Joseph Barandier, Auguste Petit, Vitor Meireles Carlos Oswald entre outros.

Igreja N. Sra. da Santa Cruz dos Militares

O desenho do frontispício apresenta monumentalidade pela proporção dos cinco tramos no primeiro pavimento e três no segundo encimado por um triângulo frontão com uma cruz sobre o acrotério na parte central. A horizontalidade advém das duas volutas laterais sobre o entalhamento das portas que dão acesso aos corredores. O corpo da igreja tem uma porta central ladeada por nichos e o pórtico com colunas em pedra com capitéis jônicos são de mármore. Unindo a sacada e janelas do coro há quatro nichos para os santos evangelistas. Mestre Valentim que lá trabalhou entre 1805 a 1811, esculpiu dois deles em cedro: São Mateus e São João, recolhidos atualmente no Museu Histórico e Nacional. As quatro esculturas em mármore de Carrara nos atuais nichos são do escultor acadêmico Jean-Louis Despré, vindas da Itália em 1926. Internamente a surpresa está na alvura da ornamentação, com o mínimo de policromia e mesmo douramento, permitindo que a rica talha rococó se revele aos pouco a partir da capela-mor, obra de mestre Valentim. Na entrada, o arco ornamentado que sustenta o coro é surpreendente pelas guirlandas e buquês de flores que se adensam até quase a altura dos olhos emoldurando toda a nave com relevos simbólicos cristãos e maçônicos, típicos do Iluminismo.

Everything in di Dark Muss Come to Light: A Postcolonial Investigation of the Practice of Extra Lessons at the Secondary Level in Jamaica's Education System

Despite the vast research examining the evolution of Caribbean education systems, little is chronologically tied to the postcolonial theoretical perspectives of specific island-state systems, such as the Jamaican education system and its relationship with the underground shadow education system. This dissertation study sought to address the gaps in the literature by critically positioning postcolonial theories in education to examine the macro- and micro-level impacts of extra lessons on secondary education in Jamaica. The following postcolonial theoretical (PCT) tenets in education were contextualized from a review of the literature: (a) PCT in education uses colonial discourse analysis to critically deconstruct and decolonize imperialistic and colonial representations of knowledge throughout history; (b) PCT in education uses an anti-colonial discursive framework to re-position indigenous knowledge in schools, colleges, and universities to challenge hegemonic knowledge; (c) PCT in education involves the "unlearning" of dominant, normative ideologies, the use of self-reflexivity, and deconstruction; and (d) PCT in education calls for critical pedagogical approaches that reject the banking concept of education and introduces inclusive pedagogy to facilitate "the passage from naïve to critical transitivity" (Freire, 1973, p. 32). Specifically, using a transformative mixed-methods design, grounded and informed by a postcolonial theoretical lens, I quantitatively uncovered and then qualitatively highlighted how if at all extra lessons can improve educational outcomes for students at the secondary level in Jamaica. Accordingly, the quantitative data was used to test the hypotheses that the practice of extra lessons in schools is related to student academic achievement and the practice of critical-inclusive pedagogy in extra lessons is related to academic achievement. The two-level hierarchical linear model analysis revealed that hours spent in extra lessons, average household monthly income, and critical-inclusive pedagogical tents were the best predictors for academic achievement. Alternatively, the holistic multi-case study explored how extra-lessons produces increased academic achievement. The data revealed new ways of knowledge construction and critical pedagogical approaches to galvanize systemic change in secondary education. Furthermore, the data showed that extra lessons can improve educational outcomes for students at the secondary level if the conditions for learning are met. This study sets the stage for new forms of knowledge construction and implications for policy change.

Intercultural Communication Between Forensic and Clinical Psychologists

While working in clinical and forensic psychology settings, a communication difficulty between the two professions became apparent. Forensic psychologists often appeared cold and callous from the clinical psychologist’s perspective, while clinical psychologists often appeared naïve or too client centered from the forensic psychologist’s perspective. I wondered if viewing each subfield of psychology as a culture could facilitate better communication through intercultural communication. Guided by Intercultural Communication in Contexts (Martin & Nakayama, 2010) in approaching intercultural communication between the two professions, I explored factors contributing to each profession’s cultural identities. Once this was established, I attempted to explore the different ways each culture could communicate more effectively. By recognizing and utilizing the strengths from each profession and understanding the possible pitfalls of one’s own, we may become competent in intercultural communication