Exit of Plasmodium Sporozoites from Oocysts Is an Active Process That Involves the Circumsporozoite Protein

Plasmodium sporozoites develop within oocysts residing in the mosquito midgut. Mature sporozoites exit the oocysts, enter the hemolymph, and invade the salivary glands. The circumsporozoite (CS) protein is the major surface protein of salivary gland and oocyst sporozoites. It is also found on the oocyst plasma membrane and on the inner surface of the oocyst capsule. CS protein contains a conserved motif of positively charged amino acids: region II-plus, which has been implicated in the initial stages of sporozoite invasion of hepatocytes. We investigated the function of region II-plus by generating mutant parasites in which the region had been substituted with alanines. Mutant parasites produced normal numbers of sporozoites in the oocysts, but the sporozoites were unable to exit the oocysts. In in vitro as well, there was a profound delay, upon trypsin treatment, in the release of mutant sporozoites from oocysts. We conclude that the exit of sporozoites from oocysts is an active process that involves the region II-plus of CS protein. In addition, the mutant sporozoites were not infective to young rats. These findings provide a new target for developing reagents that interfere with the transmission of malaria

Obstetric training: competence and care in birth assistance

Esta tese consiste em uma análise da formação em obstetrícia durante a graduação em medicina, baseada em pesquisa etnográfica realizada em duas escolas conceituadas. Objetivou-se estudar o modo como se articulam a competência técnica e científica e o cuidado ou relação com a paciente no ensino teórico e prático da assistência ao parto. As técnicas utilizadas na coleta de dados foram: observação participante, entrevistas semi-estruturadas e, de modo complementar, a análise de livros-texto e protocolos assistenciais. O trabalho abrangeu uma caracterização das propostas curriculares e um exame da experiência dos alunos quanto ao ensino teórico e prático, incluindo sua supervisão nas diversas atividades assistenciais. Ênfase maior recai sobre o desenvolvimento de conhecimentos científicos na formação. Mesmo no internato ênfase é colocada na aprendizagem da construção e encenação de narrativas clínicas, privilegiando-se a transmissão oral do conhecimento e a memória em relação ao registro escrito e à consulta ao prontuário das pacientes. Pautado em parte por assim chamadas concepções \"clássicas\", que sustentam uma visão patológica da fisiologia do parto, o exercício da prática envolve condutas que têm sido questionadas a partir das evidencias científicas ou até abandonadas em outros contextos As decisões acerca das condutas ou tratamentos adotados não são compartilhadas com as mulheres atendidas que frequentemente não são consultadas ou sequer informadas à respeito. Por vezes juízos de valor também influenciam o julgamento clínico e a tomada de decisões médicas. Há poucos parâmetros para avaliar as atitudes dos alunos em sua interação com as pacientes. Nos serviços em que há maior interação entre alunos e pacientes, a supervisão é menor. Existem acordos informais entre os assistentes na divisão de plantões que se contrapõe aos organogramas formais dos serviços obstétricos vinculados as Faculdades de medicina pesquisadas. Esses acordos subordinam os objetivos institucionais da boa formação e assistência em obstetrícia aos interesses individuais e coletivos dos profissionais obstetras responsáveis pela supervisão do ensino. Componente do currículo oculto, esses acordos servem de modelo para outros envolvendo residentes e/ou alunos. Ao longo da formação dos estudantes de medicina, as interações entre os sujeitos em relação no exercício do ato médico contribuem de diversas maneiras para desqualificar a prática médica da obstetrícia como técnica moral-dependente.This thesis consists of an analysis of obstetric training during medical school. It is based on ethnographic research undertaken at two acknowledged medical schools. The objective was to study how technical and scientific competence and care, that is, the relationship with the patient, are articulated in theoretical and practical training of birth assistance. The techniques employed in fieldwork were: participant observation, semi-structured interviews and, in a complementary form, the analysis of textbooks and assistance protocols. A characterization of the curriculum offered by the schools and an examination of students experience with respect to learning the theory and practice of obstetrics, including the supervision of the various activities involving obstetric assistance are discussed. Description and analysis of the scission between the development of technical and scientific competence in the educational process was undertaken. The implications of this scission for training in the practice of medicine as a moral dependent technique are discussed. Great emphasis is placed on the development of scientific knowledge during training. Even in the clinical years, emphasis is placed on learning to construct clinical narratives, placing priority on memory and the oral transmission of knowledge rather than written registration and consultation of patiente\'s charts. Learning and training is based in part on so-called \"classical\" concepts, which sustain a pathological approach to birthing. In training, this approach involves norms of conduct that have been questioned by scientific evidence and that have even been abandoned in other contexts. Obstetrical decisions involving conduct and training are not taken in conjunction with the women receiving assistance who frequently are not even consulted or informed of these decisions. Sometimes prejudices influence medical judgment and decision-making. There are few parameters to evaluate student attitudes in their interaction with patients. In the work stations where students interact more with patients there is less supervision. Informal arrangements between assistants with respect to rounds conflict with the formal schedules of the obstetric services associated to the medical schools where research was undertaken. These arrangements subordinate the institutional objectives of good medical practice and assistance to the individual and collective interests of the obstetricians responsible for supervising training. These arrangements are a component of the hidden curriculum and serve as a model for other arrangements involving residents and/or students. Throughout the obstetric training of medical students, interactions between the subjects involved in the medical act contribute in several ways to disqualify the medical practice of obstetrics as a morally-dependent technique

RAGs and Regulation of Autoantibodies

Autoreactive antibodies are etiologic agents in a number of autoimmune diseases. Like all other antibodies these antibodies are produced in developing B cells by V(D)J recombination in the bone marrow. Three mechanisms regulate autoreactive B cells: deletion, receptor editing, and anergy. Here we review the prevalence of autoantibodies in the initial antibody repertoire, their regulation by receptor editing, and the role of the recombinase proteins (RAG l and RAG2) in this process

Collective fluorescence and decoherence of a few nearly identical quantum dots

We study the collective interaction of excitons in closely spaced artificial molecules and arrays of nearly identical quantum dots with the electromagnetic modes. We discuss how collective fluorescence builds up in the presence of a small mismatch of the transition energy. We show that a superradiant state of a single exciton in a molecule of two dots with realistic energy mismatch undergoes a two-rate decay. We analyze also the stability of subdecoherent states for non-identical systems.Comment: 7 pages, 5 figure

Obstetric training: competence and care in birth assistance

Esta tese consiste em uma análise da formação em obstetrícia durante a graduação em medicina, baseada em pesquisa etnográfica realizada em duas escolas conceituadas. Objetivou-se estudar o modo como se articulam a competência técnica e científica e o cuidado ou relação com a paciente no ensino teórico e prático da assistência ao parto. As técnicas utilizadas na coleta de dados foram: observação participante, entrevistas semi-estruturadas e, de modo complementar, a análise de livros-texto e protocolos assistenciais. O trabalho abrangeu uma caracterização das propostas curriculares e um exame da experiência dos alunos quanto ao ensino teórico e prático, incluindo sua supervisão nas diversas atividades assistenciais. Ênfase maior recai sobre o desenvolvimento de conhecimentos científicos na formação. Mesmo no internato ênfase é colocada na aprendizagem da construção e encenação de narrativas clínicas, privilegiando-se a transmissão oral do conhecimento e a memória em relação ao registro escrito e à consulta ao prontuário das pacientes. Pautado em parte por assim chamadas concepções \"clássicas\", que sustentam uma visão patológica da fisiologia do parto, o exercício da prática envolve condutas que têm sido questionadas a partir das evidencias científicas ou até abandonadas em outros contextos As decisões acerca das condutas ou tratamentos adotados não são compartilhadas com as mulheres atendidas que frequentemente não são consultadas ou sequer informadas à respeito. Por vezes juízos de valor também influenciam o julgamento clínico e a tomada de decisões médicas. Há poucos parâmetros para avaliar as atitudes dos alunos em sua interação com as pacientes. Nos serviços em que há maior interação entre alunos e pacientes, a supervisão é menor. Existem acordos informais entre os assistentes na divisão de plantões que se contrapõe aos organogramas formais dos serviços obstétricos vinculados as Faculdades de medicina pesquisadas. Esses acordos subordinam os objetivos institucionais da boa formação e assistência em obstetrícia aos interesses individuais e coletivos dos profissionais obstetras responsáveis pela supervisão do ensino. Componente do currículo oculto, esses acordos servem de modelo para outros envolvendo residentes e/ou alunos. Ao longo da formação dos estudantes de medicina, as interações entre os sujeitos em relação no exercício do ato médico contribuem de diversas maneiras para desqualificar a prática médica da obstetrícia como técnica moral-dependente.This thesis consists of an analysis of obstetric training during medical school. It is based on ethnographic research undertaken at two acknowledged medical schools. The objective was to study how technical and scientific competence and care, that is, the relationship with the patient, are articulated in theoretical and practical training of birth assistance. The techniques employed in fieldwork were: participant observation, semi-structured interviews and, in a complementary form, the analysis of textbooks and assistance protocols. A characterization of the curriculum offered by the schools and an examination of students experience with respect to learning the theory and practice of obstetrics, including the supervision of the various activities involving obstetric assistance are discussed. Description and analysis of the scission between the development of technical and scientific competence in the educational process was undertaken. The implications of this scission for training in the practice of medicine as a moral dependent technique are discussed. Great emphasis is placed on the development of scientific knowledge during training. Even in the clinical years, emphasis is placed on learning to construct clinical narratives, placing priority on memory and the oral transmission of knowledge rather than written registration and consultation of patiente\'s charts. Learning and training is based in part on so-called \"classical\" concepts, which sustain a pathological approach to birthing. In training, this approach involves norms of conduct that have been questioned by scientific evidence and that have even been abandoned in other contexts. Obstetrical decisions involving conduct and training are not taken in conjunction with the women receiving assistance who frequently are not even consulted or informed of these decisions. Sometimes prejudices influence medical judgment and decision-making. There are few parameters to evaluate student attitudes in their interaction with patients. In the work stations where students interact more with patients there is less supervision. Informal arrangements between assistants with respect to rounds conflict with the formal schedules of the obstetric services associated to the medical schools where research was undertaken. These arrangements subordinate the institutional objectives of good medical practice and assistance to the individual and collective interests of the obstetricians responsible for supervising training. These arrangements are a component of the hidden curriculum and serve as a model for other arrangements involving residents and/or students. Throughout the obstetric training of medical students, interactions between the subjects involved in the medical act contribute in several ways to disqualify the medical practice of obstetrics as a morally-dependent technique

Cas9-Primed Adaptive Immunity During the CRISPR-Cas Response

Prokaryotes have developed numerous defense strategies to combat the constant threat of viruses (bacteriophages) that endanger them. Clustered, regularly interspaced short palindromic repeats (CRISPR) loci provide archaea and bacteria with adaptive immune systems that allow them to counteract these rapidly evolving genetic parasites. These diverse systems all generally contain two components: a set of CRISPR-associated (cas) genes and a series of repetitive DNA elements intercalated with variable sequences known as spacers. Following viral infection, these sequences are acquired from the viral genome and integrated in the CRISPR array as new spacers. Spacers are then transcribed into CRISPR RNAs (crRNAs) that direct the Cas nucleases to destroy the invader following sequence-specific recognition of either DNA or RNA. Thus, spacers function as a form of immunologic memory that can be called upon again and again to defend the cell from reinfection. In type II CRISPR-Cas systems, spacer sequences direct the Cas9 nuclease to target infecting bacteriophages and cleave their double-stranded (ds)DNA genomes. Whether and how pre-exiting anti-viral spacers in type II systems affect memory generation and the acquisition of new spacers is unknown. Here, in my thesis work, I demonstrate that previously acquired spacers promote additional spacer capture from the vicinity of the Cas9 cut site at an enhanced rate. I go on to show that Cas9-mediated dsDNA break (DSB) formation is required for spacer-mediated spacer acquisition and that the rate of spacer acquisition is correlated with the efficiency of Cas9 cleavage. As a result of this mechanism, cells with preexisting viral immunity can utilize their spacerderived crRNAs to direct the acquisition of additional spacers in a new phase of immune response known as primed spacer acquisition or priming. A consequence of priming is that immune cells can acquire additional spacers as Cas9 destroys the infecting virus. I go on to show that spacers acquired during Cas9- mediated priming endow potent benefits to bacterial communities faced with virulent bacteriophages. In particular, priming suppresses the emergence of CRISPR escaper and related viruses that emerge during Cas9 targeting. I show that this anti-viral immunity is achieved in three ways. Firstly, priming expands the hosts immune repertoire, thereby improving the existing anti-phage immunity. In addition, I show that primed spacer acquisition allows the host to contain the propagation escapers that have mutations in their target sequence that abrogate Cas9 targeting. Finally, by preemptively immunizing the host with additional spacers during the initial Cas9 targeting response, priming allows the host to anticipate secondary infections by escaper and related viruses. This “prophylactic” immunity is a unique feature in CRISPR systems that allows type II systems to overcome future threats from viruses that would have overcome the defense provided by the initial anti-viral spacer. CRISPR-Cas immune systems allow their host to rapidly adapt to the viruses that challenge them. Collectively, my thesis work has revealed a new phases of the type II-A CRISPR-Cas9 immune response that is fundamental to how these systems defend their hosts against bacteriophages