The effect of urbanization on species composition and trophic guilds of bats (Mammalia, Chiroptera) in the Brazilian Savanna.

Urban environments present less environmental heterogeneity in relation to the natural ones, affecting the biodiversity of bats and the ecological processes in which they participate. In this way, we will identify how urbanization influences the structure of bat communities in the municipality of Goiânia, Goiás, Brazil. We compared species composition, guilds and bat richness in a gradient that crossed urban, semi-urban and natural areas in the municipality of Goiânia, contained in the Cerrado biome. We captured a total of 775 bats of 16 species distributed in three families. Urban areas had a higher species abundance, while semi-urban areas had a higher species richness. The three types of environments have different compositions, the urban one being more homogeneous, the fauna in these areas is composed of generalist species, which benefit from this process. The diversity present in semi-urban areas is a consequence of the intersection between urban and natural fauna, which is why urban expansion needs to occur in a planned manner to minimize the impacts of this process and ensure the maintenance of biodiversity.

Isolation and characterization of 10 microsatellite loci for Pallas' long-tongued bat Glossophaga soricina (Phyllostomidae).

Glossophaga soricina is a widespread Neotropical nectarivorous bat. We characterized 10 microsatellite loci isolated from a shotgun genomic library. We analyzed tissues from wing membrane of 67 individuals collected from two populations of Central Brazil (Brasília and Alto Paraíso). The number of alleles per locus ranged from 2 to 20, and the observed and expected heterozygosities ranged from 0.015 to 0.666 and from 0.016 to 0.915, respectively. The high combined probability of genetic identity (4.369 x 10(-8)) and probability of paternity exclusion (0.996) showed that these microsatellite loci would be useful for population genetic structure and parentage studies in natural populations of G. soricina.

Etiopathogenesis and prognostic implications of autoimmune hemolytic anemia association with chronic lymphocytic leukemia B.

Biological complexity of mechanisms of autoimmune hemolytic anemia (AHAI) in chronic lymphocytic leukemia B (CLL) and the relation cause / effect between these two diseases has been extensively researched, but currently is still far from being completely understood. It is known that the immune system has an important role in the pathogenesis of autoimmune diseases but also in the chronic lymphoproliferative malignancies. In this process of autoimmunity associated with immunodeficiency, the CLL neoplastic cells, the non-malignant B cells, T cells, and the cellular microenvironment cells are also involved. CLL pathological lymphocytes change peripheral immune tolerance acting as an antigen presenting cells and / or cells expressing inhibitory cytokines. The two subpopulations of T cells also have an important place: self-reactive T helper cells (TH) and regulatory T cells (Treg). The Fas / Fas ligand - cell death mechanism has a significant role both in maintaining cellular homeostasis, malignant hematopoietic cell expansion and the development of autoimmune disorders, including AIHA. The article reviews the etiopathogenesis of the autoimmune mechanism of AIHA in CLL, and its impact on the prognosis and long - term survival of patients with chronic lymphocytic leukemia B.

Prognosis Factors in Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia is still one of the most common hematologic malignancies. Finding a curative solution is the objective of numerous followed cases and clinical trials. Diagnosis is based on the interlocking of classic elements and newly identified prognostic factors but time to first treatment is still an open issue. CD38, ZAP 70, IgHV gene mutational status and cytogenetic changes are proven negatively influence the evolution of chronic lymphocytic leukemia. Whether through aggressive rapid evolution or by the difficulty of obtaining a complete remission or risk of early relapse, CLL is still important. Adapted to these prognostic factors, combined therapeutic regimens have proved to be effective in achieving a durable complete remission, new agents, with encouraging partial results, being studied. Requiring initial screening, for comparative purposes, a current and growing importance has minimal residual disease; its absence at the end of treatment represents a strong positive prognostic factor.

Importance of assessing cytogenetic and molecular risk factors in acute myeloid leukemia therapy.

Acute myeloid leukemia (AML) is a heterogeneous disease in clinical presentation, outcome and therapeutic response. Cytogenetic and molecular characteristics are important prognostic indicators allowing the identification of distinct subtypes of AML, prognostic stratification and risk-adapted treatment. We present our experience during 5 years, in which we treated 245 patients with AML, of which we could genetically characterize 48 cases (26 females, 22 males) with a median age of 52 years. Cytogenetic analysis was performed by GTG banding on cultures of marrow cells treated with colcemid. Molecular analysis used RT-PCR performed on ABI 9700 platform in order to identify the following fusion genes: E2A-PBX1, TEL-AML1, AML1-ETO, PML-RARα, MLL-AF4, CBFC-MYH11, BCR-ABL, SIL-TAL, and MLL-AF9as well as mutations in Flt3, NPM1, WT1 genes. Fourteen patients were older than 60 years. In 12 we performed cytogenetic analysis showing 5 cases with complex karyotype, 2 normal karyotypes, 1 case of del(21), del (9), 11q- and t(3;15) respectively as well as 2 unevaluable karyotypes. These anomalies were associated with a high incidence of secondary AMLs (10/14) and with a low remission (CR) rate (5/14). Out of the 35 patients younger than 60 years, 25 were evaluated by cytogenetics showing a high incidence of favorable cytogenetic changes: 6 anomalies of chromosome 16 (5 inv (16) and 1 t (16; 16)), 3 t (15; 17), 3 cases of t (8; 21) of which 2 with additional abnormalities, 7 normal karyotypes and 1 case of 7q-, -y,-3 and respectively -8 associated with +18. In 25 cases molecular analysis was performed showing alterations in 21 patients: 6 cases with AML/ETO, 3 PML/RAR, 7 Flt3 mutations (2 associated with NPM1 mutation) as well as 1 case of isolated mutation of NPM1 and respectively WT1. CR rate was of 28/35. All cases with t (15; 17) and PML/RAR as well all cases with t (8; 21) and/or AML/ETO achieved CR. Out of the 7 cases with Flt3 mutations only 4 achieved CR including the 2 cases with associated NPM1 mutations. In our experience, genetic characteristics correlate with other prognostic markers such as age and secondary leukemia; "favorable" genetic anomalies were associated with a high CR rate; association of t (8; 21) with additional abnormalities did not influence CR rate.

Bat community species richness and composition in a restinga protected area in Southeastern Brazil.

In Brazil, restingas are under severe human-induced impacts resulting in habitat degradation and loss and remain one of the less frequently studied ecosystems. The main objectives of the present study are to describe the bat community in a restinga in Paulo Cesar Vinha State Park, Guarapari municipality, state of Espírito Santo, southeastern Brazil. Fieldwork was conducted twice a month from August 2004 to September 2005. A total sampling effort of 40,300 m(2)/h, represents the largest sampling effort for sampling bats in restingas to date. Bats were sampled in five different vegetational types in the area. Captured bats were processed recording information on species, sex, age, forearm length and weight. Shannon Diversity and Jaccard indexes were used to analyse diversity and similarity among habitats in the Park. A total of 554 captures belonging to 14 species and two families were obtained. Noctilio leporinus was recorded through direct observation and an ultra-sound detector also registered the presence of individuals from the family Molossidae, without being possible to distinguish it at specific level. Frugivores were the most representative guild. Richness was higher in Clusia shrubs (11 species) and Caraís lagoon (10 species). Shannon diversity index was estimated at H' = 1.43 for the overall sample, with Caraís lagoon representing the most diverse habitat (H' = 1.60). The greater similarity (J = 0.714) was observed for the two areas under high human influence.

Bat community species richness and composition in a restinga protected area in Southeastern Brazil / Estrutura de comunidade de morcegos numa área protegida de restinga no Sudeste do Brasil

In Brazil, restingas are under severe human-induced impacts resulting in habitat degradation and loss and remain one of the less frequently studied ecosystems. The main objectives of the present study are to describe the bat community in a restinga in Paulo Cesar Vinha State Park, Guarapari municipality, state of Espírito Santo, southeastern Brazil. Fieldwork was conducted twice a month from August 2004 to September 2005. A total sampling effort of 40,300 m²/h, represents the largest sampling effort for sampling bats in restingas to date. Bats were sampled in five different vegetational types in the area. Captured bats were processed recording information on species, sex, age, forearm length and weight. Shannon Diversity and Jaccard indexes were used to analyse diversity and similarity among habitats in the Park. A total of 554 captures belonging to 14 species and two families were obtained. Noctilio leporinus was recorded through direct observation and an ultra-sound detector also registered the presence of individuals from the family Molossidae, without being possible to distinguish it at specific level. Frugivores were the most representative guild. Richness was higher in Clusia shrubs (11 species) and Caraís lagoon (10 species). Shannon diversity index was estimated at H' = 1.43 for the overall sample, with Caraís lagoon representing the most diverse habitat (H' = 1.60). The greater similarity (J = 0.714) was observed for the two areas under high human influence.

No Brasil, as restingas sofrem severos impactos humanos que resultam em perda e degradação de habitat. Além disso, constituem um dos ecossistemas menos estudados. Os principais objetivos deste estudo foram descrever uma parcela da quirópterofauna do Parque Estadual Paulo Cesar Vinha, município de Guarapari, Estado do Espírito Santo, e descrever a estrutura de comunidade de morcegos nessa área de restinga, no Sudeste do Brasil. O trabalho de campo foi realizado duas vezes por mês, de agosto de 2004 a setembro de 2005. O esforço de amostragem total foi de 40.300 m²/h, que representa o maior esforço de captura para morcegos em restingas até o momento. Os morcegos foram capturados em diferentes tipos de vegetação e tiveram as informações de espécie, sexo, idade, comprimento do antebraço e peso anotadas. Os índices de diversidade de Shannon e Jaccard foram utilizados para analisar a diversidade e a similaridade entre os habitats. Foram obtidas 554 capturas representando 14 espécies e duas famílias. Noctilio leporinus foi registrado através de observação direta. Com o uso de um detector de ultrassons, registrou-se a presença de indivíduos da família Molossidae, não sendo possível a identificação da espécie. A riqueza foi maior no ambiente de Clusia (11 espécies) e na lagoa de Caraís (10 espécies). O índice de diversidade de Shannon foi estimado em H' = 1,43 na área total amostrada, com a lagoa de Caraís, representando o habitat mais diverso (H' = 1,60). A maior similaridade (J = 0,714) foi observada entre as duas áreas sob maior influência antrópica. Um aumento no número de pesquisas em áreas de restinga é importante para garantir melhores medidas de conservação para esse ecossistema.

[Heart assist systems with integrated microsensors (HIM 2)]. / Herzunterstützungssystem mit Integrierter Mikrosensorik (HIM 2).

The use of intracardiac pump systems is leading to more physiological support for coronary surgery patients. But the currently available micro blood pump with an integrated micro pressure sensor and an outer diameter of 6.5 mm is not suitable for a transfemoral placement of the device. Therefore a significantly smaller pump with an outer diameter of 4 mm (12F) is been developed and tested. To transfer the sensor technology in this, for the first time the MID (moulded interconnected device) technology is applied in a medical device. In a first step MID is used to integrate a smaller pressure sensor on the existing blood pump. The result should help to find a new packaging and connecting solution for integration of the miniaturized sensor on the 4 mm pump.

The effect of Simvastatin upon serum pseudocholinesterase and plasmatic factor VII.

UNLABELLED: The statins have a moderate lowering effect upon triglycerides, one hypothesis suggesting an inhibitory effect upon liver VLDL synthesis. Because VLDL synthesis is related to other hepatic protein synthesis we studied the effect of Simvastatin upon serum cholinesterase activity and factor VII activity, which are also synthetized at hepatic level. METHODS: 39 patients with ischaemic heart disease, proved by coronarography and moderate hypercholesterolaemia received for two months 20 mg Simvastatin (Zocor). The value of total Co, LDLCo, HDLCo, triglycerides, serum cholinesterase activity and factor VII activity were determined before and after treatment, by standard methods. RESULTS: Triglycerides were, together with total Co, significantly lowered during the two months treatment with Simvastatin, but the values of serum cholinesterase and factor VII activity were not significantly modified. This suggests that moderate doses of Simvastatin do not depress liver protein synthesis. CONCLUSION: Simvastatin does not lower the triglycerides level through depression of liver protein syntesis, other mechanisms being probably involved.

Recruitment times, proliferation, and apoptosis rates during the CD8(+) T-cell response to lymphocytic choriomeningitis virus.

The specific CD8(+) T-cell response during acute lymphocytic choriomeningitis virus (LCMV) infection of mice is characterized by a rapid proliferation phase, followed by a rapid death phase and long-term memory. In BALB/c mice the immunodominant and subdominant CD8(+) responses are directed against the NP118 and GP283 epitopes. These responses differ mainly in the magnitude of the epitope-specific CD8(+) T-cell expansion. Using mathematical models together with a nonlinear parameter estimation procedure, we estimate the parameters describing the rates of change during the three phases and thereby establish the differences between the responses to the two epitopes. We find that CD8(+) cell proliferation begins 1 to 2 days after infection and occurs at an average rate of 3 day(-1), reaching the maximum population size between days 5 and 6 after immunization. The 10-fold difference in expansion to the NP118 and GP283 epitopes can be accounted for in our model by a 3.5-fold difference in the antigen concentration of these epitopes at which T-cell stimulation is half-maximal. As a consequence of this 3.5-fold difference in the epitope concentration needed for T-cell stimulation, the rates of activation and proliferation of T cells specific for the two epitopes differ during the response and in combination can account for the large difference in the magnitude of the response. After the peak, during the death phase, the population declines at a rate of 0.5 day(-1), i.e., cells have an average life time of 2 days. The model accounts for a memory cell population of 5% of the peak population size by a reversal to memory of 1 to 2% of the activated cells per day during the death phase.

Whole-genome analysis: annotations and updates.

The most important advances in the field of genome annotation over the past two years involve the use of cDNA sequences, protein structures and gene expression data to predict genes. These types of information not only improve gene identification, but they also give insights into variation in gene structure and function.

Improved inference of mutation rates: I. An integral representation for the Luria-Delbrück distribution.

The estimation of mutation rates is ordinarily performed using results based on the Luria-Delbrück distribution. There are certain difficulties associated with the use of this distribution in practice, some of which we address in this paper (others in the companion paper, Oprea and Kepler, Theor. Popul. Biol., 2001). The distribution is difficult to compute exactly, especially for large values of the random variable. To overcome this problem, we derive an integral representation of the Luria-Delbrück distribution that can be computed easily for large culture sizes. In addition, we introduce the usual assumption of very small probability of having a large proportion of mutants only after the generating function has been computed. Thus, we obtain information on the moments for the more general case. We examine the asymptotic behavior of this system. We find a scaling or "standardization" technique that reduces the family of distributions parameterized by three parameters (mutation rate, initial cell number, and final cell number) to a single distribution with no parameters, valid so long as the product of the mutation rate and the final culture is sufficiently large. We provide a pair of techniques for computing confidence intervals for the mutation rate. In the second paper of this series, we use the distribution derived here to find approximate distributions for the case where the cell cycle time is not well-described as an exponential random variable as is implicitly assumed by Luria-Delbrück distribution.

Improved inference of mutation rates: II. Generalization of the Luria-Delbrück distribution for realistic cell-cycle time distributions.

In the first paper of this series (Kepler and Oprea, Theor. Popul. Biol. 2001) we found a continuum approximation of the Luria-Delbrück distribution in terms of a scaled variable related to the proportion of mutants in the culture. Here we show that the Luria-Delbrück distribution is inaccurate when realistic division processes are being considered due to the non-Markovian character of the cell cycle. We derive the expectation of the proportion of mutants in the culture for arbitrary cell-cycle time distributions. We then introduce a two-parameter generalization of the continuum Luria-Delbrück distribution for two of the more commonly used cell-cycle time distributions: gamma and shifted exponential. We obtain the generalized distribution by defining a map from the actual parameters to "effective" parameters. The effective mutation rate is obtained analytically, while the effective population size is obtained by fitting simulation data. Our simulations show that the second parameter depend mostly on the coefficient of variation of the cell-cycle time distribution.

The targeting of somatic hypermutation closely resembles that of meiotic mutation.

We have compared the microsequence specificity of mutations introduced during somatic hypermutation (SH) and those introduced meiotically during neutral evolution. We have minimized the effects of selection by studying nonproductive (hence unselected) Ig V region genes for somatic mutations and processed pseudogenes for meiotic mutations. We find that the two sets of patterns are very similar: the mutabilities of nucleotide triplets are positively correlated between the somatic and meiotic sets. The major differences that do exist fall into three distinct categories: 1) The mutability is sharply higher at CG dinucleotides under meiotic but not somatic mutation. 2) The complementary triplets AGC and GCT are much more mutable under somatic than under meiotic mutation. 3) Triplets of the form WAN (W = T or A) are uniformly more mutable under somatic than under meiotic mutation. Nevertheless, the relative mutabilities both within this set and within the SAN (S = G or C) triplets are highly correlated with those under meiotic mutation. We also find that the somatic triplet specificity is strongly symmetric under strand exchange for A/T triplets as well as for G/C triplets in spite of the strong predominance of A over T mutations. Thus, we suggest that somatic mutation has at least two distinct components: one that specifically targets AGC/GCT triplets and another that acts as true catalysis of meiotic mutation.

Dynamics of one-pass germinal center models: implications for affinity maturation.

During an immune response, the affinity of antibodies that react with the antigen that triggered the response increases with time, a phenomenon known as affinity maturation. The molecular basis of affinity maturation has been partially elucidated. It involves the somatic mutation of immunoglobulin V-region genes within antigen-stimulated germinal center B cells and the subsequent selection of high affinity variants. This mutation and selection process is extremely efficient and produces large numbers of high affinity variants. Studies of the architecture of germinal centers suggested that B cells divide in the dark zone of the germinal center, then migrate to the light zone, where they undergo selection based on their interaction with antigen-loaded follicular dendritic cells, after which they exit the germinal center through the mantle zone. Kepler and Perelson questioned this architecturally driven view of the germinal center reaction. They, as well as others, argued that the large number of point mutations observed in germinal center B cell V-region genes, frequently 5 to 10 and sometimes higher, would most likely render cells incapable of binding the antigen, if no selection step was interposed between rounds of mutations. To clarify this issue, we address the question of whether a mechanism in which mutants are generated and then selected in one pass, with no post-selection amplification, can account for the observed efficiency of affinity maturation. We analyse a set of one-pass models of the germinal center reaction, with decaying antigen, and mutation occurring at transcription or at replication. We show that under all the scenarios, the proportion of high affinity cells in the output of a germinal center varies logarithmically with their selection probability. For biologically realistic parameters, the efficiency of this process is in clear disagreement with the experimental data. Furthermore, we discuss a set of, possibly counterintuitive, more general features of one-pass selection models that follow from our analysis. We believe that these results may also provide useful intuitions in other cases where a population is subjected to selection mediated by a selective force that decays over time.

Genetic plasticity of V genes under somatic hypermutation: statistical analyses using a new resampling-based methodology.

Evidence for somatic hypermutation of immunoglobulin genes has been observed in all of the species in which immunoglobulins have been found. Previous studies have suggested that codon usage in immunoglobulin variable (V) region genes is such that the sequence-specificity of somatic hypermutation results in greater mutability in complementarity-determining regions of the gene than in the framework regions. We have developed a new resampling-based methodology to explore genetic plasticity in individual V genes and in V gene families in a statistically meaningful way. We determine what factors contribute to this mutability difference and characterize the strength of selection for this effect. We find that although the codon usage in immunoglobulin V genes renders them distinct among translationally equivalent sequences with random codon usage, they are nevertheless not optimal in this regard. We find that the mutability patterns in a number of species are similar to those we find for human sequences. Interestingly, sheep sequences show extremely strong mutability differences, consistent with the role of somatic hypermutation in the diversification of primary antibody repertoire in these animals. Human TCR V(beta) sequences resemble immunoglobulin in mutability pattern, suggesting one of several alternatives, that hypermutation is functionally operating in TCR, that it was once operating in TCR or in the common precursor of TCR and immunoglobulin, or that the hypermutation mechanism has evolved to exploit the codon usage in immunoglobulin (and fortuitously, TCR) rather than vice-versa. Our findings provide support to the hypothesis that somatic hypermutation appeared very early in the phylogeny of immune systems, that it is, to a large extent, shared between species, and that it makes an essential contribution to the generation of the antibody repertoire.

Somatic mutation leads to efficient affinity maturation when centrocytes recycle back to centroblasts.

Although most mutations are deleterious, an interplay between somatic mutation and selection within germinal centers (GC) results in rapid generation of high affinity memory B cells. How high affinity B cells with large numbers of mutations are generated and preserved within GC containing at their peak only a few thousand cells has been puzzling. We have developed a model of somatic mutation and B cell expansion within a GC that resolves this puzzle. We show that the frequent recycling of Ag-selected centrocytes back into centroblasts can lead to efficient affinity maturation. Memory cells are generated in large numbers even when most of the selected centrocytes recycle back into centroblasts. Our model suggests that a germinal center reaction in which the output of cells is low up to the point of GC dissociation, followed by the release of centrocytes into the periphery, is advantageous for generating high affinity memory.

Exploring the mechanisms of primary antibody responses to T cell-dependent antigens.

We have developed a model of the early events that occur during a primary antibody response to a T cell-dependent antigen. Within secondary lymphoid organs, B cell proliferation in response to antigen injection gives rise to two kinds of transient structures: foci that develop in the T cell area, and germinal centers, that develop in the secondary follicles of the B cell area. Foci give rise to plasma cells that are responsible for the majority of early circulating antibody, whereas germinal centers are sites of somatic mutation and memory cell formation. Here we model the cell-cell interactions and cell population kinetics involved in the generation of antibody-forming cell foci, and compare our model with experimental data. We focus on fundamental issues involving the control of B cell proliferation and differentiation, using simple kinetic models that depend on direct cell-cell interactions and on the action of cytokines. We show that with realistic parameter assumptions our model can account for both the rapid cellular expansion and the differentiation of B cells into antibody-secreting cells. By summing the expected antibody production of all the plasmablasts and plasma cells that are generated during the focus response we can account for much of the antibody observed in the serum of mice during a primary response. Lastly, we compare the predictions of our model for two different scenarios for the control of B cell proliferation. In one model, we assume that B cells, once activated, proliferate under the control of cytokines without direct interaction with activated T cells. In the other model, we assume that after dividing B cells return to rest and require a contact-dependent signal from an activated T cell to divide again. The first model gives rise to large foci and antibody levels similar to that observed in experiment, whereas the latter model gives rise to four-fold smaller foci and to circulating antibody levels that are one order of magnitude lower than typical experimental values. This result suggests that B cells may be able to divide without further contact with T cells once a cognate interaction has occurred.

Capacity of a model immune network.

The capacity of a model immune network in terms of the number of different antigens that can be vaccinated against without any memory lost is computed and tested by numerical simulations. We also investigate memory loss and failure to vaccinate due to overcrowding the network with too many antigens. The computations are done for two different strategies for proliferation, one implying all the antigen specific clones and the second one being more thrifty.

Exercise tests in labile hypertensive patients.

From a collectivity of 17,256 subjects below the age of 30 years, 80 subjects with labile hypertension (LH) were selected. The LH subjects were subjected to exercise test and the response of arterial blood pressure (BP) was followed up. The data obtained were compared with similar determinations carried out in a group of normotensive subjects. The mean value of systolic blood pressure (SBP) on exercise in the normal subjects was 171.0 +/- 2.9 mmHg and that of diastolic blood pressure (DBP) was 77.5 + 1.5 mmHg. The LH subjects presented, on exercise increases of both SBP and DBP in 35 cases (43.7%), increase of only SBP in 10 cases (12.5%) and "normal" type response in 35 cases (43.7%). In these subjects the mean value of SBP, on exercise, was 191.0 +/- 2.6 mmHg (p less than 0.001 as compared with the normal) and that of DBP was 90.0 +/- 1.9 mmHg (p less than 0.001 as compared with the normal). The above data proved that the LH subjects represented a group distinct from the normal subjects. The LH subjects presented a bimodal percent distribution of SBP and DBP on exercise, suggesting the existence of two subgroups one with "normal" type BP response the other with "hypertensive" type response. The BP response to exercise represents a simple test for the detection of abnormal BP increases. The authors consider as fully justified a longitudinal study of LH subjects. The exercise test might have a predictive value in detecting the early signs of essential hypertension.