The influence of mandibular implant-retained overdentures in masticatory efficiency

doi: 10.1111/j.1741‐2358.2011.00539.x The influence of mandibular implant‐retained overdentures in masticatory efficiency Objective: To evaluate the masticatory efficiency of patients rehabilitated with conventional dentures (CDs) or implant‐retained mandibular overdentures. Background: Despite the evident benefits of implants on mastication as assessed by subjective patient‐based outcomes, the extent of implant overdenture treatment effect on food comminution is not well established. Materials and methods: A randomised clinical trial was carried out with 29 completely edentulous patients divided into two groups. The first group was rehabilitated with a mandibular overdenture retained by two splinted implants with bar‐clip system, while the second group was rehabilitated with a mandibular CD. Both groups also were rehabilitated with maxillary CDs. Masticatory efficiency and patient satisfaction were assessed 3 months after denture insertion. Masticatory efficiency was evaluated through the colorimetric method with the beads as the artificial test‐food. Comparisons for masticatory efficiency and patient satisfaction were performed using Student’s t‐test (α = 0.05). Results: No significant statistical difference was found for masticatory efficiency (p = 0.198). Patient overall satisfaction was significantly higher for the mandibular overdenture (p < 0.001). In addition, mandibular overdenture patients were significantly more satisfied with chewing experience (p < 0.05) and retention of the lower denture (p < 0.005). Conclusion: The results of this study suggest that mandibular overdenture significantly improves chewing experience, although limited effect on masticatory efficiency has been observed.     

Differential expression of the pr1A gene in Metarhizium anisopliae and Metarhizium acridum across different culture conditions and during pathogenesis

The entomopathogenic fungi of the genus Metarhizium have several subtilisin-like proteases that are involved in pathogenesis and these have been used to investigate genes that are differentially expressed in response to different growth conditions. The identification and characterization of these proteases can provide insight into how the fungus is capable of infecting a wide variety of insects and adapt to different substrates. In addition, the pr1A gene has been used for the genetic improvement of strains used in pest control. In this study we used quantitative RT-PCR to assess the relative expression levels of the pr1A gene in M. anisopliae and M. acridum during growth in different culture conditions and during infection of the sugar cane borer, Diatraea saccharalis Fabricius. We also carried out a pathogenicity test to assess the virulence of both species against D. saccharalis and correlated the results with the pattern of pr1A gene expression. This analysis revealed that, in both species, the pr1A gene was differentially expressed under the growth conditions studied and during the pathogenic process. M. anisopliae showed higher expression of pr1A in all conditions examined, when compared to M. acridum. Furthermore, M. anisopliae showed a greater potential to control D. saccharalis. Taken together, our results suggest that these species have developed different strategies to adapt to different growing conditions.     

Experimental evidence of habitat selection and territoriality in the Amazonian whip spider Heterophrynus longicornis (Arachnida, Amblypygi)

Animals that select and defend suitable habitats against conspecifics may be favored by maximizing prey encounter rate, gaining protection, or securing matings. However, the identification of habitat selection and territoriality may be hindered in observational studies in sedentary species with low-density populations, such as the whip spider Heterophrynus longicornis. To circumvent such difficulties, we adopted an experimental field approach to evaluate if H. longicornis selects and defends habitat in Central Amazon. To evaluate whether individuals perform habitat selection, we monitored the permanence of 29 experimentally released individuals in buttressed trees with a wide variation in diameter at breast height (DBH), with and without burrows at their bases. To evaluate whether individuals are territorial, we experimentally removed 21 individuals from their previously occupied trees and monitored the recolonization of these trees. If H. longicornis were territorial, we predicted that the recolonizers would be smaller than the removed individuals. We found 12 individuals in the trees where they were released on subsequent days, none of them in trees without burrows. The individual permanence was related to the presence of burrows, and not to DBH. There was recolonization by smaller males and females on ten trees from which the amblypygids were removed. In combination, the permanence of individuals in trees with burrows, the rapid recolonization of experimentally vacated trees by smaller individuals, and the preponderance of one individual per tree, suggest that both male and female H. longicornis perform habitat selection and also that after selecting a site, they defend it against conspecifics.     

Genetic diversity of Puccinia kuehnii,the causal agent of orange rust of sugarcane,from Brazil

The use of resistant genotypes is the preferred method to control orange rust of sugarcane (Saccharum spp) caused by Puccinia kuehnii. This approach has been adopted in Brazil but outbreaks of the disease on previously resistant varieties showed that the efficacy of this method is limited and requires a better understanding of pathogen diversity. Nevertheless, adequate molecular markers for examining pathogen diversity at population level are not available, which limits the success of orange rust control by genetic resistance. Therefore, two independent investigations were conducted to examine genetic diversity of P. kuehnii from São Paulo state, the most important sugarcane growing state of Brazil. First, simple-sequence repeat (SSR) markers were developed in the present work and genotypic diversity of orange rust isolates from different locations investigated. Second, phenotypic diversity was examined by the single-pustule inoculation technique on P. kuehnii isolates retrieved from three susceptible commercial sugarcane cultivars. A total of 96 SSR markers were generated and tested for this species. Subsequently, 29 isolates of P. kuehnii were fingerprinted with nine SSR markers to estimate the genotypic diversity by neighbour-joining and 3D principal coordinates. The 29 isolates of the pathogen clustered into four main groups, which were identified by three SSR markers (NPRL_PK_108a, NPRL_PK_162_spka and NPRL_PK_221_spka). Phenotypic data at 21 days after the single-pustule inoculation showed that P. kuehnii from highly susceptible commercial cultivars harboured a small proportion of variants capable of causing disease on resistant cultivars. A differential reaction was demonstrated for the most virulent variant in a repeated experiment confirming the existence of races within P. kuehnii in Brazil.     

Biodegradation of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis> diethylaniline in a contaminated aquifer: laboratory- and field-scale evidences

The effectiveness of biosparging to mitigate N,N diethylaniline in aquifer was evaluated by measuring the time course of decrease in concentration of the aforementioned compound in aerobic microcosm experiments. The first-order kinetic constant for N,N diethylaniline aerobic biodegradation was estimated from microcosm data (0.037 ± 0.004 d⁻¹), and the value was consistent with the best-fitting value in the transport and reaction model of the aquifer (0.020 d⁻¹). Furthermore, the biodegradability of the compound was evaluated under anaerobic condition in microcosm experiments, which was supported by field modelling. There was no significant degradation in the anaerobic microcosm experiments, confirming the recalcitrance of N,N diethyl aniline under the aforementioned aquifer condition.     

Low prevalence of hepatitis C virus infection in Amerindians from Western Venezuela

Previous studies have not found hepatitis C virus (HCV) infection in Amerindians from Western Venezuela. A survey of 254 Bari and Yukpa natives aged 10-60 years (mean +/- SD age = 35 +/- 5.4 years) from four communities, two Bari and two Yukpa, in this area were studied to assess the prevalence of antibodies to HCV (anti-HCV) and HCV RNA among these indigenous populations. Serum samples were examined initially for anti-HCV by a four generation enzyme-linked immunosorbent assay (ELISA). Reactive samples were then tested using a third generation recombinant immunoblot assay (RIBA-3). Viral RNA was investigated in all immunoblot-reactive samples by a nested polymerase chain reaction (PCR) method. Six (2.3%) of 254 natives were positive by ELISA, one (2.2%) of these reactive samples were positive by RIBA, and four (1.5%) were indeterminate. Only two (0.8%) were positive by PCR, corresponding to 1 (2.1%) of 47 inhabitants of a Yukpa community and to 1 (2.2%) of 45 subjects of a Bari community. Iatrogenic is thought to play a role in acquisition of the infection. The findings indicate a HCV focus of low endemicity and are compatible with a low degree of exposures of the natives to the virus. Studies are necessary to assess the risk factors for infection in these Amerindians.     

Cutting edge: Complement (C3d)-linked antigens break B cell anergy

C3dg adducts of Ag can coligate complement receptor type 2 (CR2; CD21) and the B cell Ag receptor. This interaction significantly amplifies BCR-mediated signals in Ag-naive wild-type mice, lowering the threshold for B cell activation and the generation of humoral immune responses as much as 1000-fold. In this study we demonstrate that CR2-mediated complementation of BCR signals can also overcome B cell anergy. Unlike Ag alone, BCR/CR2 costimulation (Ars-CCG/C3dg complexes) of anergic Ars/A1 B cells led to Ca(2+) mobilization in vitro and the production of autoantibodies in vivo. Interestingly, the in vivo immune response of anergic cells occurs without the formation of germinal centers. These results suggest that the Ag unresponsiveness of anergic B cells can be overcome by cross-reactive (self-mimicking) Ags that have been complement-opsonized. This mechanism may place individuals exposed to complement-fixing bacteria at risk for autoimmunity.     

Characterization of heme as activator of Toll-like receptor 4

Heme is an ancient and ubiquitous molecule present in organisms of all kingdoms, composed of an atom of iron linked to four ligand groups of porphyrin. A high amount of free heme, a potential amplifier of the inflammatory response, is a characteristic feature of diseases with increased hemolysis or extensive cell damage. Here we demonstrate that heme, but not its analogs/precursors, induced tumor necrosis factor-alpha (TNF-alpha) secretion by macrophages dependently on MyD88, TLR4, and CD14. The activation of TLR4 by heme is exquisitely strict, requiring its coordinated iron and the vinyl groups of the porphyrin ring. Signaling of heme through TLR4 depended on an interaction distinct from the one established between TLR4 and lipopolysaccharide (LPS) since anti-TLR4/MD2 antibody or a lipid A antagonist inhibited LPS-induced TNF-alpha secretion but not heme activity. Conversely, protoporphyrin IX antagonized heme without affecting LPS-induced activation. Moreover, heme induced TNF-alpha and keratinocyte chemokine but was ineffective to induce interleukin-6, interleukin-12, and interferon-inducible protein-10 secretion or co-stimulatory molecule expression. These findings support the concept that the broad ligand specificity of TLR4 and the different activation profiles might in part reside in its ability to recognize different ligands in different binding sites. Finally, heme induced oxidative burst, neutrophil recruitment, and heme oxygenase-1 expression independently of TLR4. Thus, our results presented here reveal a previous unrecognized role of heme as an extracellular signaling molecule that affects the innate immune response through a receptor-mediated mechanism.     

Biotransformation of β-hydroxyphenyl selenides, diphenyldiselenide and benzeneseleninic acid by whole cells of Aspergillus terreus

Aspergillus terreus CCT 3320 and A. terreus URM 3571 catalysed the biotransformations of organic β-hydroxyphenyl selenides through oxidation and methylation reactions. The kinetic resolution of (RS)-1-(phenylseleno)-2-propanol (1) via enantioselective oxidation produced (+)-(S)-1 in high enantiomeric excess (>99%) and in a yield of 50% as determined by product isolation. Oxidation of the R-enantiomer of 1, followed by elimination of the propyl moiety and subsequent methylation of the presumed intermediate, led to the formation of methylphenyl-selenide, which was isolated in a yield of 40%. Whole cells of A. terreus also biocatalysed transformations of diphenyldiselenide, benzeneseleninic acid, (RS)-1-(phenylseleno)-2-pentanol and (RS)-1-(phenylseleno)-3-methyl-2-butanol, but not of (RS)-1-(phenylseleno)-2-phenyl-methanol. This is the first report of the biomethylation of organoselenium compounds by whole cells of A. terreus.