Cytochrome P-450 activities in human and rat brain microsomes.

The role of cytochrome P450 in the metabolism of dextromethorphan, amitriptyline, midazolam, S-mephenytoin, citalopram, fluoxetine and sertraline was investigated in rat and human brain microsomes. Depending on the parameters, the limit of quantification using gas chromatography-mass spectrometry methods was between 1.6 and 20 pmol per incubation, which generally contained 1500 microg protein. Amitriptyline was shown to be demethylated to nortriptyline by both rat and human microsomes. Inhibition studies using ketoconazole, furafylline, sulfaphenazole, omeprazole and quinidine suggested that CYP3A4 is the isoform responsible for this reaction whereas CYP1A2, CYP2C9, CYP2C19 and CYP2D6 do not seem to be involved. This result was confirmed by using a monoclonal antibody against CYP3A4. Dextromethorphan was metabolized to dextrorphan in rat brain microsomes and was inhibited by quinidine and by a polyclonal antibody against CYP2D6. Only the addition of exogenous reductase allowed the measurement of this activity in human brain microsomes. Metabolites of the other substrates could not be detected, possibly due to an insufficiently sensitive method. It is concluded that cytochrome P450 activity in the brain is very low, but that psychotropic drugs could undergo a local cerebral metabolism which could have pharmacological and/or toxicological consequences.

Research recommendations for selected IARC-classified agents.

OBJECTIVES: There are some common occupational agents and exposure circumstances where evidence of carcinogenicity is substantial but not yet conclusive for humans. The objectives are to identify research gaps and needs for twenty agents prioritized for review based on evidence of widespread human exposures and potential carcinogenicity in animals or humans. DATA SOURCES: A systematic review was conducted of new data published since the most recent pertinent IARC monograph meeting. DATA EXTRACTION: Reviewers were charged with identifying data gaps and general and specific approaches to address them, focusing on research that would be important in resolving classification uncertainties. An expert meeting brought reviewers together to discuss each agent and the identified data gaps and approaches. DATA SYNTHESIS: Several overarching issues were identified that pertained to multiple agents; these included the importance of recognizing that carcinogenic agents can act through multiple toxicity pathways and mechanisms, including epigenetic mechanisms, oxidative stress and immuno- and hormonal modulation. CONCLUSIONS: Studies in occupational populations provide important opportunities to understand the mechanisms through which exogenous agents cause cancer and intervene to prevent human exposure and/or prevent or detect cancer among those already exposed. Scientific developments are likely to increase the challenges and complexities of carcinogen testing and evaluation in the future, and epidemiologic studies will be particularly critical to inform carcinogen classification and risk assessment processes.[Authors]

“Estereótipos de género no brincar de crianças no Pré-escolar”

No presente estudo abordaremos o conceito de género como resultado de uma transformação social, cultural e política que foi tendo lugar nas relações entre meninos e meninas, marcadas ainda por uma profunda desigualdade a favor dos homens. Esta abordagem vem sendo divulgada em cabo verde, desde 1994, pelo instituto da condição feminina (ICF1), sendo actualmente designado instituto caboverdiano para igualdade e equidade de género (ICIEG2), cujas estratégias passa pelo reconhecimento da igualdade de género entre os sexos, tendo como horizonte a existência, em Cabo verde de uma comunidade igualitária e democrática em termos de oportunidades. (Constituição da republica (1999). É fácil perceber, mesmo tendo sido já definido por vários autores, que os papéis atribuídos a meninos e meninas, mulheres e homens, estão condicionados por um conjunto de factores socialmente adaptadas e constituídos pelos nossos antepassados. Na sociedade contemporânea deparamos com vários tipos de preconceitos ou crenças, que de una forma ou de outra contribuem e impedem mudanças comportamentais nos sexos, dos processos de socialização transmitidas de gerações em gerações e aceites por elas mesmas. Pois são hábitos que todos nós recebemos quotidianamente dos familiares e antepassados produzindo-os com naturalidade, isto porque os nossos próprios valores culturais e sociais desaconselham, ou mesmo proíbem os meninos de brincarem com bonecas ou meninas de jogarem a bola. Segundo o velho ditado que “pari fêmea” é “p" aba sirbi mundo” e que “pari matcho” é “pa ba sirbi rei” (Género, Mulher e política ICF, 2002). Nesta perspectiva a questão do sexo passa a ser incluída neste projecto, afinal, o tema esta ligada às noções de masculino e feminino, facilitando o processo de socialização da criança. Como depreendemos a natureza não é responsável pelas diferenças de comportamentos e de lugares que o homem e a mulher ocupam na sociedade e nas relações humanas.

Purification and ligand binding of a soluble class I major histocompatibility complex molecule consisting of the first three domains of H-2Kd fused to beta 2-microglobulin expressed in the baculovirus-insect cell system.

A recombinant baculovirus encoding a single-chain murine major histocompatibility complex class I molecule in which the first three domains of H-2Kd are fused to beta 2-microglobulin (beta 2-m) via a 15-amino acid linker has been isolated and used to infect lepidopteran cells. A soluble, 391-amino acid single-chain H-2Kd (SC-Kd) molecule of 48 kDa was synthesized and glycosylated in insect cells and could be purified in the absence of detergents by affinity chromatography using the anti-H-2Kd monoclonal antibody SF1.1.1.1. We tested the ability of SC-Kd to bind antigenic peptides using a direct binding assay based on photoaffinity labeling. The photoreactive derivative was prepared from the H-2Kd-restricted Plasmodium berghei circumsporozoite protein (P.b. CS) peptide 253-260 (YIPSAEKI), a probe that we had previously shown to be unable to bind to the H-2Kd heavy chain in infected cells in the absence of co-expressed beta 2-microglobulin. SC-Kd expressed in insect cells did not require additional mouse beta 2-m to bind the photoprobe, indicating that the covalently attached beta 2-m could substitute for the free molecule. Similarly, binding of the P.b. CS photoaffinity probe to the purified SC-Kd molecule was unaffected by the addition of exogenous beta 2-m. This is in contrast to H-2KdQ10, a soluble H-2Kd molecule in which beta 2-m is noncovalently bound to the soluble heavy chain, whose ability to bind the photoaffinity probe is greatly enhanced in the presence of an excess of exogenous beta 2-m. The binding of the probe to SC-Kd was allele-specific, since labeling was selectively inhibited only by antigenic peptides known to be presented by the H-2Kd molecule.

Doctors without borders: The returns to an occupational license for Soviet immigrant physicians in Israel

Re-licensing requirements for professionals that move across borders arewidespread. In this paper, we measure the returns to an occupationallicense using novel data on Soviet trained physicians that immigrated toIsrael. An immigrant re-training assignment rule used by the IsraelMinistry of Health provides an exogenous source of variation inre-licensing outcomes. Instrumental variables and quantile treatmenteffects estimates of the returns to an occupational license indicate excesswages due to occupational entry restrictions and negative selectioninto licensing status. We develop a model of optimal license acquisitionwhich suggests that the wages of high-skilled immigrant physicians in thenonphysician sector outweigh the lower direct costs that these immigrantsface in acquiring a medical license. Licensing thus leads to lower averagequality of service. However, the positive earnings effect of entry restrictionsfar outweighs the lower practitioner quality earnings effect that licensinginduces.

Oxidative and glycogenolytic cCapacities within the developing chick heart.

Cardiac morphogenesis and function are known to depend on both aerobic and anaerobic energy-producing pathways. However, the relative contribution of mitochondrial oxidation and glycogenolysis, as well as the determining factors of oxygen demand in the distinct chambers of the embryonic heart, remains to be investigated. Spontaneously beating hearts isolated from stage 11, 20, and 24HH chick embryos were maintained in vitro under controlled metabolic conditions. O(2) uptake and glycogenolytic rate were determined in atrium, ventricle, and conotruncus in the absence or presence of glucose. Oxidative capacity ranged from 0.2 to 0.5 nmol O(2)/(h.microg protein), did not depend on exogenous glucose, and was the highest in atria at stage 20HH. However, the highest reserves of oxidative capacity, assessed by mitochondrial uncoupling, were found at the youngest stage and in conotruncus, representing 75 to 130% of the control values. At stage 24HH, glycogenolysis in glucose-free medium was 0.22, 0.17, and 0.04 nmol glucose U(h.microg protein) in atrium, ventricle, and conotruncus, respectively. Mechanical loading of the ventricle increased its oxidative capacity by 62% without altering glycogenolysis or lactate production. Blockade of glycolysis by iodoacetate suppressed lactate production but modified neither O(2) nor glycogen consumption in substrate-free medium. These findings indicate that atrium is the cardiac chamber that best utilizes its oxidative and glycogenolytic capacities and that ventricular wall stretch represents an early and major determinant of the O(2) uptake. Moreover, the fact that O(2) and glycogen consumptions were not affected by inhibition of glyceraldehyde-3-phosphate dehydrogenase provides indirect evidence for an active glycerol-phosphate shuttle in the embryonic cardiomyocytes.

Risk sharing with the monarch: Excusable defaults and contingent debt in the age of Philip II, 1556-1598

Contingent sovereign debt can create important welfare gains. Nonetheless,there is almost no issuance today. Using hand-collected archival data, we examine thefirst known case of large-scale use of state-contingent sovereign debt in history. Philip IIof Spain entered into hundreds of contracts whose value and due date depended onverifiable, exogenous events such as the arrival of silver fleets. We show that this allowedfor effective risk-sharing between the king and his bankers. The data also stronglysuggest that the defaults that occurred were excusable they were simply contingenciesover which Crown and bankers had not contracted previously.

The distribution of talent across contests

Do the contests with the largest prizes attract the most able contestants? Towhat extent do contestants avoid competition? In this paper, we show, theoreticallyand empirically, that the distribution of abilities plays a crucial role in determiningcontest choice. Sorting exists only when the proportion of high-ability contestantsis sufficiently small. As this proportion increases, contestants shy away from competitionand sorting decreases, such that, reverse sorting becomes a possibility. Wetest our theoretical predictions using a large panel data set containing contest choiceover three decades. We use exogenous variation in the participation of highly-ablecompetitors to provide empirical evidence for the relationship among prizes, competition,and sorting.

Austerity and anarchy: Budget cuts and social unrest in Europe, 1919-2008

Does fiscal consolidation lead to social unrest? Using cross-country evidencefor the period 1919 to 2008, we examine the extent to which societies becomeunstable after budget cuts. The results show a clear correlation between fiscalretrenchment and instability. Expenditure cuts are particularly potent infueling protests; tax rises have only small and insignificant effects. We test ifthe relationship simply reflects economic downturns, using a recently-developedIMF dataset on exogenous expenditure shocks, and conclude that this is not thecase. While autocracies and democracies show broadly similar responses to budgetcuts, countries with more constraints on the executive are less likely to seeunrest after austerity measures. Growing media penetration does not strengthenthe effect of cut-backs on the level of unrest. We also find that austerity episodesthat result in unrest lead to quick reversals of fiscal policy.

Endogenous credit cycles

I develop an overlapping-generations framework in which changes in lending standards generateendogenous cycles. In my economy, entrepreneurs who are privately informed about thequality of their projects need to borrow funds. Intermediaries screen entrepreneurs both throughthe amount of investment undertaken and through the level of entrepreneurial net worth.I show that endogenous regime switches in financial contracts from pooling to separatingand vice-versa may generate fluctuations even in the absence of exogenous shocks. Whenthe economy is in the pooling (separating) regime, lending standards seem lax ( tight ) andinvestment is high (low). Differently from the existing literature, my model does not requireentrepreneurial net worth to be counter cyclycal or inconsequential for determining aggregateinvestment.

When to carry eccentric products? Optimal retail assortment under consumer returns

To understand whether retailers should consider consumer returns when merchandising, we study howthe optimal assortment of a price-taking retailer is influenced by its return policy. The retailer selects itsassortment from an exogenous set of horizontally differentiated products. Consumers make purchase andkeep/return decisions in nested multinomial logit fashion. Our main finding is that the optimal assortmenthas a counterintuitive structure for relatively strict return policies: It is optimal to offer a mix of the mostpopular and most eccentric products when the refund amount is sufficiently low, which can be viewed asa form of risk sharing between the retailer and consumers. In contrast, if the refund is sufficiently high, orwhen returns are disallowed, optimal assortment is composed of only the most popular products (a commonfinding in the literature). We provide preliminary empirical evidence for one of the key drivers of our results:more eccentric products have higher probability of return conditional on purchase. In light of our analyticalfindings and managerial insights, we conclude that retailers should take their return policies into accountwhen merchandising.

Analysis of CD4+ and CD8+ T cells by defined MHC-peptide complexes

MHC class II-peptide multimers are important tools for the detection, enumeration and isolation of antigen-specific CD4+ Τ cells. However, their erratic and often poor performance impeded their broad application and thus in-depth analysis of key aspects of antigen-specific CD4+ Τ cell responses. In the first part of this thesis we demonstrate that a major cause for poor MHC class II tetramer staining performance is incomplete peptide loading on MHC molecules. We observed that peptide binding affinity for "empty" MHC class II molecules poorly correlates with peptide loading efficacy. Addition of a His-tag or desthiobiotin (DTB) at the peptide N-terminus allowed us to isolate "immunopure" MHC class II-peptide monomers by affinity chromatography; this significantly, often dramatically, improved tetramer staining of antigen-specific CD4+ Τ cells. Insertion of a photosensitive amino acid between the tag and the peptide, permitted removal of the tag from "immunopure" MHC class II-peptide complex by UV irradiation, and hence elimination of its potential interference with TCR and/or MHC binding. Moreover, to improve loading of self and tumor antigen- derived peptides onto "empty" MHC II molecules, we first loaded these with a photocleavable variant of the influenza A hemagglutinin peptide HA306-318 and subsequently exchanged it with a poorly loading peptide (e.g. NY-ESO-1119-143) upon photolysis of the conditional ligand. Finally, we established a novel type of MHC class II multimers built on reversible chelate formation between 2xHis-tagged MHC molecules and a fluorescent nitrilotriacetic acid (NTA)-containing scaffold. Staining of antigen-specific CD4+ Τ cells with "NTAmers" is fully reversible and allows gentle cell sorting. In the second part of the thesis we investigated the role of the CD8α transmembrane domain (TMD) for CD8 coreceptor function. The sequence of the CD8α TMD, but not the CD8β TMD, is highly conserved and homodimerizes efficiently. We replaced the CD8α TMD with the one of the interleukin-2 receptor a chain (CD8αTac) and thus ablated CD8α TMD interactions. We observed that ΤΙ Τ cell hybridomas expressing CD8αTacβ exhibited severely impaired intracellular calcium flux, IL-2 responses and Kd/PbCS(ABA) P255A tetramer binding. By means of fluorescence resonance energy transfer experiments (FRET) we established that CD8αTacβ associated with TCR:CD3 considerably less efficiently than CD8αβ, both in the presence and the absence of Kd/PbCS(ABA) complexes. Moreover, we observed that CD8αTacβ partitioned substantially less in lipid rafts, and related to this, associated less efficiently with p56Lck (Lck), a Src kinase that plays key roles in TCR proximal signaling. Our results support the view that the CD8α TMD promotes the formation of CD8αβP-CD8αβ dimers on cell surfaces. Because these contain two CD8β chains and that CD8β, unlike CD8α, mediates association of CD8 with TCR:CD3 as well as with lipid rafts and hence with Lck, we propose that the CD8αTMD plays an important and hitherto unrecognized role for CD8 coreceptor function, namely by promoting CD8αβ dimer formation. We discuss what implications this might have on TCR oligomerization and TCR signaling. - Les multimères de complexes MHC classe II-peptide sont des outils importants pour la détection, le dénombrement et l'isolation des cellules Τ CD4+ spécifiques pour un antigène d'intérêt. Cependant, leur performance erratique et souvent inadéquate a empêché leur utilisation généralisée, limitant ainsi l'analyse des aspects clés des réponses des lymphocytes Τ CD4+. Dans la première partie de cette thèse, nous montrons que la cause principale de la faible efficacité des multimères de complexes MHC classe II-peptide est le chargement incomplet des molécules MHC par des peptides. Nous montrons également que l'affinité du peptide pour la molécule MHC classe II "vide" n'est pas nécessairement liée au degré du chargement. Grâce à l'introduction d'une étiquette d'histidines (His-tag) ou d'une molécule de desthiobiotine à l'extrémité N-terminale du peptide, des monomères MHC classe II- peptide dits "immunopures" ont pu être isolés par chromatographic d'affinité. Ceci a permis d'améliorer significativement et souvent de façon spectaculaire, le marquage des cellules Τ CD4+ spécifiques pour un antigène d'intérêt. L'insertion d'un acide aminé photosensible entre l'étiquette et le peptide a permis la suppression de l'étiquette du complexe MHC classe- Il peptide "immunopure" par irradiation aux UV, éliminant ainsi de potentielles interférences de liaison au TCR et/ou au MHC. De plus, afin d'améliorer le chargement des molécules MHC classe II "vides" avec des peptides dérivés d'auto-antigènes ou d'antigènes tumoraux, nous avons tout d'abord chargé les molécules MHC "vides" avec un analogue peptidique photoclivable issu du peptide HA306-318 de l'hémagglutinine de la grippe de type A, puis, sous condition de photolyse, nous l'avons échangé avec de peptides à chargement faible (p.ex. NY-ESO-1119-143). Finalement, nous avons construit un nouveau type de multimère réversible, appelé "NTAmère", basé sur la formation chélatante reversible entre les molécules MHC-peptide étiquettés par 2xHis et un support fluorescent contenant des acides nitrilotriacetiques (NTA). Le marquage des cellules Τ CD4+ spécifiques pour un antigène d'intérêt avec les "NTAmères" est pleinement réversible et permet également un tri cellulaire plus doux. Dans la deuxième partie de cette thèse nous avons étudié le rôle du domaine transmembranaire (TMD) du CD8α pour la fonction coréceptrice du CD8. La séquence du TMD du CD8α, mais pas celle du TMD du CD8β, est hautement conservée et permet une homodimérisation efficace. Nous avons remplacé le TMD du CD8α avec celui de la chaîne α du récepteur à l'IL-2 (CD8αTac), éliminant ainsi les interactions du TMD du CD8α. Nous avons montré que les cellules des hybridomes Τ T1 exprimant le CD8αTacβ présentaient une atteinte sévère du flux du calcium intracellulaire, des réponses d'IL-2 et de la liaison des tétramères Kd/PbCS(ABA) P255A. Grâce aux expériences de transfert d'énergie entre molécules fluorescentes (FRET), nous avons montré que l'association du CD8αTacβ avec le TCR:CD3 est considérablement moins efficace qu'avec le CD8αβ, et ceci aussi bien en présence qu'en absence de complexes Kd/PbCS(ABA). De plus, nous avons observé que le CD8αTacβ se distribuait beaucoup moins bien dans les radeaux lipidiques, engendrant ainsi, une association moins efficace avec p56Lck (Lck), une kinase de la famille Src qui joue un rôle clé dans la signalisation proximale du TCR. Nos résultats soutiennent l'hypothèse que le TMD du CD8αβ favorise la formation des dimères de CD8αβ à la surface des cellules. Parce que ces derniers contiennent deux chaînes CD8β et que CD8β, contrairement à CD8α, favorise l'association du CD8 au TCR:CD3 aussi bien qu'aux radeaux lipidiques et par conséquent à Lck, nous proposons que le TMD du CD8α joue un rôle important, jusqu'alors inconnu, pour la fonction coreceptrice du CD8, en encourageant la formation des dimères CD8αβ. Nous discutons des implications possibles sur l'oligomerisation du TCR et la signalisation du TCR.

Solving non-linear stochastic models by parameterizing expectations: An application to asset pricing with production

A new algorithm called the parameterized expectations approach(PEA) for solving dynamic stochastic models under rational expectationsis developed and its advantages and disadvantages are discussed. Thisalgorithm can, in principle, approximate the true equilibrium arbitrarilywell. Also, this algorithm works from the Euler equations, so that theequilibrium does not have to be cast in the form of a planner's problem.Monte--Carlo integration and the absence of grids on the state variables,cause the computation costs not to go up exponentially when the numberof state variables or the exogenous shocks in the economy increase. \\As an application we analyze an asset pricing model with endogenousproduction. We analyze its implications for time dependence of volatilityof stock returns and the term structure of interest rates. We argue thatthis model can generate hump--shaped term structures.

Revisão e análise cladística de Serdia Stål (Heteroptera, Pentatomidae, Pentatomini)

Treze espécies são hoje incluídas no gênero: S. apicicornis, Stål, 1860; S. beckerae Thomas & Rolston, 1985; S. calligera Stål, 1860; S. concolor Ruckes, 1958; S. costalis Ruckes, 1958; S. delphis Thomas & Rolston, 1985; S. inspersipes Stål, 1860; S. lobata Thomas & Rolston, 1985; S. rotundicornis Becker, 1967 e S. ruckesi Thomas & Rolston, 1985. Cinco novas espécies são descritas: S. indistincta sp. nov (Irai, Rio Grande do Sul), S. bicolor sp. nov (Ponta Grossa, Paraná), S. maculata sp. nov (Itatiaia, Rio de Janeiro), S. máxima sp. nov (Imbituba, Santa Catarina) e S. robusta sp. nov (Itatiaia, Rio de Janeiro) do Brasil. A análise cladística foi realizada usando 40 caracteres e 21 táxons. O gênero Tibilis Stål, 1860; Neotibilis Grazia & Barcellos, 1994 e Similliserdia Fortes & Grazia, 1998 foram usados como grupo-externo. A monofilia de Serdia foi sustentada por 3 sinapomorfias: ápice do escutelo com margens enegrecidas, machos com a parede da taça genital espessada com processos em aba, fêmeas com o espessamento da íntima vaginal situado na metade posterior das gonapófises 9 e projetando-se ventralmente. O subgênero Brasiliicola Kirkaldy, 1909 é considerado sinônimo junior de Serdia. São fornecidas ilustrações, mapas de distribuição geográfica e chave para as espécies.

Shared knowledge

Agents use their knowledge on the history of the economy in orderto choose what is the optimal action to take at any given moment of time,but each individual observes history with some noise. This paper showsthat the amount of information available on the past evolution of theeconomy is an endogenous variable, and that this leads to overconcentrationof the investment, which can be interpreted as underinvestment in research.It presents a model in which agents have to invest at each period in one of$K$ sectors, each of them paying an exogenous return that follows a welldefined stochastic path. At any moment of time each agent receives an unbiasednoisy signal on the payoff of each sector. The signals differ across agents,but all of them have the same variance, which depends on the aggregate investmentin that particular sector (so that if almost everybody invests in it theperceptions of everybody will be very accurate, but if almost nobody doesthe perceptions of everybody will be very noisy). The degree of hetereogeneityacross agents is then an endogenous variable, evolving across time determining,and being determined by, the amount of information disclosed.As long as both the level of social interaction and the underlying precisionof the observations are relatively large agents behave in a very preciseway. This behavior is unmodified for a huge range of informational parameters,and it is characterized by an excessive concentration of the investment ina few sectors. Additionally the model shows that generalized improvements in thequality of the information that each agent gets may lead to a worse outcomefor all the agents due to the overconcentration of the investment that thisproduces.