The two major human metapneumovirus genetic lineages are highly related antigenically, and the fusion (F) protein is a major contributor to this antigenic relatedness

The growth properties and antigenic relatedness of the CAN98-75 (CAN75) and the CAN97-83 (CAN83) human metapneumovirus (HMPV) strains, which represent the two distinct HMPV genetic lineages and exhibit 5 and 63% amino acid divergence in the fusion (F) and attachment (G) proteins, respectively, were investigated in vitro and in rodents and nonhuman primates. Both strains replicated to high titers (> or =6.0 log(10)) in the upper respiratory tract of hamsters and to moderate titers (> or =3.6 log(10)) in the lower respiratory tract. The two lineages exhibited 48% antigenic relatedness based on reciprocal cross-neutralization assay with postinfection hamster sera, and infection with each strain provided a high level of resistance to reinfection with the homologous or heterologous strain. Hamsters immunized with a recombinant human parainfluenza virus type 1 expressing the fusion F protein of the CAN83 strain developed a serum antibody response that efficiently neutralized virus from both lineages and were protected from challenge with either HMPV strain. This result indicates that the HMPV F protein is a major antigenic determinant that mediates extensive cross-lineage neutralization and protection. Both HMPV strains replicated to low titers in the upper and lower respiratory tracts of rhesus macaques but induced high levels of HMPV-neutralizing antibodies in serum effective against both lineages. The level of HMPV replication in chimpanzees was moderately higher, and infected animals developed mild colds. HMPV replicated the most efficiently in the respiratory tracts of African green monkeys, and the infected animals developed a high level of HMPV serum-neutralizing antibodies (1:500 to 1:1,000) effective against both lineages. Reciprocal cross-neutralization assays in which postinfection sera from all three primate species were used indicated that CAN75 and CAN83 are 64 to 99% related antigenically. HMPV-infected chimpanzees and African green monkeys were highly protected from challenge with the heterologous HMPV strain. Taken together, the results from hamsters and nonhuman primates support the conclusion that the two HMPV genetic lineages are highly related antigenically and are not distinct antigenic subtypes or subgroups as defined by reciprocal cross-neutralization in vitro.     

Comparison of early and late responses to antigen of sensitized guinea pig parenchymal lung strips.

The peripheral lung parenchyma has been studied as a component of the asthmatic inflammatory response. During induced constriction, tissue resistance increases in different asthma models. Approximately 60% of the asthmatic patients show early and late responses. The late response is characterized by more severe airway obstruction. In the present study, we evaluated lung parenchymal strips mechanics in ovalbumin-sensitized guinea pigs, trying to reproduce both early and late inflammatory responses. Oscillatory mechanics of lung strips were performed in a control group (C), in an early response group (ER), and in two late response groups: 17 h (L1) and 72 h (L2) after the last ovalbumin challenge. Measurements of resistance and elastance were obtained before and after ovalbumin challenge in C and ER groups and before and after acetylcholine challenge in all groups. Using morphometry, we assessed the density of eosinophils and smooth muscle cells, as well as collagen and elastin content in lung strips. The baseline and postagonist values of resistance and elastance were increased in ER, L1, and L2 groups compared with C (P < or = 0.001). The morphometric analysis showed an increase in alveolar eosinophil density in ER and L2 groups compared with C (P < 0.05). There was a significant correlation between eosinophil density in parenchymal strips of C, L1, and L2 groups and values of resistance and elastance postacetylcholine (r = 0.71, P = 0.001 and r = 0.74, P < 0.001, respectively). The results show that the lung parenchyma is involved in the late response, and the constriction response in this phase is related to the eosinophilic inflammation.     

Genetic and historic evidence for climate-driven population fragmentation in a top cetacean predator: the harbour porpoises in European water

Recent climate change has triggered profound reorganization in northeast Atlantic ecosystems, with substantial impact on the distribution of marine assemblages from plankton to fishes. However, assessing the repercussions on apex marine predators remains a challenging issue, especially for pelagic species. In this study, we use Bayesian coalescent modelling of microsatellite variation to track the population demographic history of one of the smallest temperate cetaceans, the harbour porpoise (Phocoena phocoena) in European waters. Combining genetic inferences with palaeo-oceanographic and historical records provides strong evidence that populations of harbour porpoises have responded markedly to the recent climate-driven reorganization in the eastern North Atlantic food web. This response includes the isolation of porpoises in Iberian waters from those further north only approximately 300 years ago with a predominant northward migration, contemporaneous with the warming trend underway since the ‘Little Ice Age’ period and with the ongoing retreat of cold-water fishes from the Bay of Biscay. The extinction or exodus of harbour porpoises from the Mediterranean Sea (leaving an isolated relict population in the Black Sea) has lacked a coherent explanation. The present results suggest that the fragmentation of harbour distribution range in the Mediterranean Sea was triggered during the warm ‘Mid-Holocene Optimum’ period (approx. 5000 years ago), by the end of the post-glacial nutrient-rich ‘Sapropel’ conditions that prevailed before that time.     

Three-dimensional mechanical properties of porcine coronary arteries: a validated two-layer model

The normal coronary artery consists of two mechanically distinct layers: intima-media and adventitia. The objective of this study is to establish a two-layer three-dimensional (3-D) stress-strain relation of porcine coronary arteries. Experimental measurements were made by a series of biaxial tests (inflation and axial extension) of intact coronary arteries and, subsequently, their corresponding intima-media or adventitia layer. The Fung-type exponential strain energy function was used to describe the 3-D strain-stress relation for each layer and the intact wall. A genetic algorithm was used to determine the material constants in the Fung-type constitutive equation by curve fitting the experimental data. Because one layer must be sacrificed before the other layer can be tested, the material property of the missing layer was computed from the material constants of the intact vessel and the tested layer. A total of 20 porcine hearts were used: one group of 10 hearts for the left anterior descending artery and another group of 10 hearts for the right coronary artery. Each group was further divided into two subgroups of five specimens tested for the intact wall and the intima-media layer and for the intact wall and the adventitia layer. Our results show statistically significant differences in the material properties of the two layers. The mathematical model was validated by experimental stress-strain data for individual layers. The validated 3-D constitutive model will serve as a foundation for formulation of layer-specific boundary value problems in coronary physiology and cardiology.     

Enhanced macrophage activity in granulomatous lesions of immune mice challenged with Mycobacterium tuberculosis

In this study, we evaluated the cellular influx and cytokine environment in the lungs of mice made immune by prior vaccination with Mycobacterium bovis bacillus Calmette-Guérin compared with control mice after infection with Mycobacterium tuberculosis to characterize composition of protective lesions in the lungs. Immune mice controlled the growth of the M. tuberculosis challenge more efficiently than control mice. In immune animals, granulomatous lesions were smaller and had a more lymphocytic core, less foamy cells, less parenchymal inflammation, and slower progression of lung pathology than in lungs of control mice. During the chronic stage of the infection, the bacterial load in the lungs of immune mice remained at a level 10 times lower than control mice, and this was associated with reduced numbers of CD4P(+P) and CD8P(+P) T cells, and the lower expression of protective (IL-12, IFN-gamma), inflammatory (TNF-alpha), immunoregulatory (GM-CSF), and immunosuppressive (IL-10) cytokines. The immune mice had higher numbers of CD11b- CD11c(high) DEC-205(low) alveolar macrophages, but lower numbers of CD11b+ CD11c(high) DEC-205(high) dendritic cells, with the latter expressing significantly lower levels of the antiapoptotic marker TNFR-associated factor-1. Moreover, during the early stage of chronic infection, lung dendritic cells from immune mice expressed higher levels of MHC class II and CD40 molecules than similar cells from control mice. These results indicate that while a chronic disease state is the eventual outcome in both control and immune mice infected with M. tuberculosis by aerosol exposure, immune mice develop a protective granulomatous lesion by increasing macrophage numbers and reduced expression of protective and inflammatory cytokines.     

Light-induced rhythmic changes in thermotolerance in stationary-phase cells of Candida utilis.

In synchronized light-dark cycles, stationary-phase cultures of the budding yeast Candida utilis were able to survive heat treatment at 50 degees C with an apparent circadian-like rhythm related to the onset of light. However, in continuous darkness this pattern did not run freely and was markedly dampened. We discuss these findings in terms of the potential circadian control of heat tolerance, which has been described in the fission yeast Schizosaccharomyces pombe. Our results suggest that the resistance pattern observed in C. utilis is most likely an adaptive response to the light-induced generation of reactive oxygen species rather than the occurrence of a truly endogenous circadian rhythm.     

Biological activity of Bifidobacterium longum in response to environmental pH

The influence of environmental pH on biological activity of Bifidobacterium longum CRL 849 grown in MRS-raffinose was evaluated. At pH 6.0, 5.5 and 5.0, raffinose was completely consumed by this microorganism, showing different consumption rates at each pH value (between 3.03 and 0.76 mmol l⁻¹ h⁻¹). At pH 4.5, the growth was lowest. The removal of raffinose was due to the α-galactosidase (α-gal) activity of this bifidobacteria, which was highest at pH 6.0–5.5 (1,280–1,223 mU ml⁻¹). The production of β-glucosidase (β-glu) showed a similar pattern to α-gal activity with major values. The yield of organic acids produced during raffinose consumption was also highest at pH 6.0–5.5. The results of this study will allow the selection of the optimum growth conditions of B. longum CRL 849, with elevated levels of α-gal to be used in the reduction of nondigestible α-oligosaccharide in soy products and β-glu activities involved in isoflavone conversion to bioactive forms when used as starter culture.     

Influence of Th1/Th2 Cytokines and Nitric Oxide in Murine Systemic Infection Induced by Sporothrix schenckii

In an attempt to elucidate the effects of Sporothrix schenckii infection on the immune response, our laboratory has developed a murine model of disseminated sporotrichosis. Helper T cells can be further subdivided into Th1 and Th2 phenotypes. The differentiation of two subsets of T lymphocytes is driven by IL-12 and IL-4 cytokines, respectively. Th1 cells produce IFN-γ that activate macrophages and promote cell-mediated immunity. In addition, we found low levels of iNOS and NO production in the initial (1st and 2nd weeks) and final (9th and 10th weeks) periods of the infection, in contrast with the period of week 4 to 7 of elevated values. The determination of IFN-γ and IL-12 are in agreement with NO/iNOS detection, showing the presence of cellular immune response throughout the infectious process. However, the production of IL-4 shows an increase in levels after the 5th and 6th weeks suggesting a participation of Th2 response in this period as well. Regarding these results, the study demonstrated that in experimental sporotrichosis infection the cellular immune response participated throughout the period analyzed as a nitric oxide dependent mechanism. In contrast, the presence of Th2 response began in the 5th week, suggesting the participation of humoral immune response in advanced stages of sporotrichosis.     

Fourier transform infrared spectroscopy provides a fingerprint for the tetramer and for the aggregates of transthyretin

Transthyretin (TTR) is an amyloidogenic protein whose aggregation is responsible for several familial amyloid diseases. Here, we use FTIR to describe the secondary structural changes that take place when wt TTR undergoes heat- or high-pressure-induced denaturation, as well as fibril formation. Upon thermal denaturation, TTR loses part of its intramolecular beta-sheet structure followed by an increase in nonnative, probably antiparallel beta-sheet contacts (bands at 1,616 and 1,686 cm(-1)) and in the light scattering, suggesting its aggregation. Pressure-induced denaturation studies show that even at very elevated pressures (12 kbar), TTR loses only part of its beta-sheet structure, suggesting that pressure leads to a partially unfolded species. On comparing the FTIR spectrum of the TTR amyloid fibril produced at atmospheric pressure upon acidification (pH 4.4) with the one presented by the native tetramer, we find that the content of beta-sheets does not change much upon fibrillization; however, the alignment of beta-sheets is altered, resulting in the formation of distinct beta-sheet contacts (band at 1,625 cm(-1)). The random-coil content also decreases in going from tetramers to fibrils. This means that, although part of the tertiary- and secondary-structure content of the TTR monomers has to be lost before fibril formation, as previously suggested, there must be a subsequent reorganization of part of the random-coil structure into a well-organized structure compatible with the amyloid fibril, as well as a readjustment of the alignment of the beta-sheets. Interestingly, the infrared spectrum of the protein recovered from a cycle of compression-decompression at pD 5, 37 degrees C, is quite similar to that of fibrils produced at atmospheric pressure (pH 4.4), which suggests that high hydrostatic pressure converts the tetramers of TTR into an amyloidogenic conformation.