ABSTRACT
The periodontal ligament (PDL) is a porous and fibrous soft tissue situated around the tooth, which plays a key role in the transmission of loads from the tooth to the alveolar bone of the mandible. Although several studies have tried to characterize its mechanical properties, the behaviour of this tissue is not clear yet. In this study, a new simulation methodology based on a material model which considers the contribution of porous and fibrous structure with different material model formulations depending on the effort direction is proposed. The defined material model was characterized by a non-linear approximation of the porous fibrous matrix to experimental results obtained from samples of similar species and was validated by rigorous test simulations under tensile and compressive loads. The global PDL response was also validated using the parameters of the characterization in a finite element model of full human canine tooth obtained by micro-tomography. The results suggest that the porous contribution has high influence during compression because the bulk modulus of the material depends on the ability of interstitial fluid to drain. On the other hand, the collagen fibres running along the load direction are the main responsible of the ligament stiffness during tensile efforts. Thus, a material model with distinct responses depending of the load direction is proposed. Furthermore, the results suggest the importance of considering 3D finite element models based of the real morphology of human PDL for representing the irregular stress distribution caused by the coupling of complex material models and irregular morphologies.
Subject(s)
Periodontal Ligament/diagnostic imaging , Biomechanical Phenomena/physiology , Computer Simulation , Elasticity , Finite Element Analysis , Humans , Models, Biological , Periodontal Ligament/physiology , Porosity , Stress, Mechanical , X-Ray MicrotomographyABSTRACT
Tannase is an enzyme that catalyses the hydrolysis of ester bonds present in tannins. Most of the scientific reports about this biocatalysis focus on aspects related to tannase production and its recovery; on the other hand, reports assessing the molecular aspects of the tannase gene or protein are scarce. In the present study, a tannase gene fragment from several Aspergillus strains isolated from the Mexican semidesert was sequenced and compared with tannase amino acid sequences reported in NCBI database using bioinformatics tools. The genetic relationship among the different tannase sequences was also determined. A conserved region of 7 amino acids was found with the conserved motif GXSXG common to esterases, in which the active-site serine residue is located. In addition, in Aspergillus niger strains GH1 and PSH, we found an extra codon in the tannase sequences encoding glycine. The tannase gene belonging to semidesert fungal strains followed a neutral evolution path with the formation of 10 haplotypes, of which A. niger GH1 and PSH haplotypes are the oldest.
Subject(s)
Aspergillus niger/enzymology , Carboxylic Ester Hydrolases/genetics , Fungal Proteins/genetics , Amino Acid Sequence , Base Sequence , Carboxylic Ester Hydrolases/chemistry , Conserved Sequence , Fungal Proteins/chemistry , Genes, Fungal , Haplotypes , Molecular Sequence Data , Molecular Typing , Mycological Typing Techniques , Phylogeny , Polymorphism, Genetic , Sequence Analysis, DNAABSTRACT
BACKGROUND: Oxidative stress is a central factor in the pathogenesis of Parkinson's disease (PD). Heme oxygenase-1 (HO-1) is an antioxidant protein expressed in response to oxidative challenge, and its expression levels are inversely correlated with glycogen synthase kinase-3beta (GSK3beta) activity. Underexpression of HO-1 in concert with an upregulation of GSK3beta would result in a less effective antioxidant response and might increase the risk of PD. METHODS: We examined two functional polymorphism in the promoter regions of HO-1 (-413, rs2071746) and GSK3beta (-157, rs6438552) in a group of 251 Spanish patients with PD and 234 controls. RESULTS: Subjects carrying both the HO-1 (-413, rs2071746) TT genotype and the GSK3beta (-157, rs6438552) TT genotype had a four times higher risk of developing PD than subjects without these genotypes (adjusted by age and sex OR = 4.12; 95% CI = 1.45-11.71; Bonferroni corrected P = 0.024). CONCLUSIONS: Considering synergistic effects between polymorphisms in oxidative stress-related genes may help in determining the risk profile for PD.
Subject(s)
Genetic Predisposition to Disease/genetics , Glycogen Synthase Kinase 3/genetics , Heme Oxygenase-1/genetics , Oxidative Stress/genetics , Parkinson Disease/enzymology , Parkinson Disease/genetics , Adult , Aged , Aged, 80 and over , Cohort Studies , Female , Gene Frequency/genetics , Genotype , Glycogen Synthase Kinase 3 beta , Humans , Male , Middle Aged , Polymorphism, Genetic/genetics , Promoter Regions, Genetic/genetics , Risk AssessmentABSTRACT
BACKGROUND: The authors describe a Heller's technique alteration used for treatment of early Chagasic megaesphagus (ECM): esophagocardiomyotomy with divulsion plus esophagocardiopexy. PATIENTS AND METHODS: Between June 1988 and March 1996, fifty patients were operated on at Surgery Department of FAMEMA. All had chagasic megaesophagus degrees I, II and III. RESULTS: The results were excellent in 86% (43/50) and good in 14% (7/50), for 6 months to 7.6 years of follow up. The radiological and endoscopic studies showed neither esophagic stasis nor food residues and esophagitis. CONCLUSION: The authors concluded that esophagocardiomyotomy with divulsion plus esophagocardiogastropexy is efficient in ECM degrees I, II e III and emphasize both technical facility and security.
Subject(s)
Chagas Disease/complications , Esophageal Achalasia/surgery , Adult , Aged , Cardia/surgery , Esophageal Achalasia/etiology , Female , Follow-Up Studies , Fundoplication/methods , Humans , Male , Middle AgedABSTRACT
Objetivo. Os autores descrevem uma variante da técnica proposta por Heller para o tratamento cirúrgico do megaesofago: esofagocardiomiotomia com divulsao associada a esofagofundogastropexia. Casuística e Método. No período de junho de 1988 a março de 1996, foram operados, na Disciplina de Cirurgia do Aparelho Digestivo do Departamento de Cirurgia da Faculdade de Medicina de Marília, SP, 50 pacientes portadores de megaesôfago chagásico graus I, II e III. Resultados. Num seguimento de seis meses a 7,6 anos, os resultados sao classificados como ótimo, 86 por cento, e bom, 14 por cento. O estudo radiológico contrastado mostra melhora do clareamento esofágico e a endoscopia, ausência de restos alimentares e esofagite. Conclusao. Os autores concluem que esofagocardiomiotomia com divulsao associada a esofagofundogastropexia é eficaz no tratamento cirúrgico do megaesôfago chagásico graus I, II e III, e enfatizam a facilidade técnica e a segurança do procedimento.
Subject(s)
Humans , Female , Aged , Middle Aged , Adult , Chagas Disease/complications , Esophageal Achalasia/surgery , Cardia/surgery , Esophageal Achalasia/etiology , Follow-Up Studies , Fundoplication/methods , Treatment OutcomeABSTRACT
A retrospective study was carried out upon 393 patients diagnosed from the 1 January 1970 through 1 December 1978 for carcinoma of the colon and rectum, 90 per cent of whom had a complete follow-up study during a five year period or until death. A classification system by stage, which has given us good results since there are no crossovers in the survival evolution of the different subgroups, is described. The system shows great uniformity since a linear equation with a slope of 15.76 per cent and a linear correlation coefficient (r) = -0.999 relates almost perfectly the decrease in survival time as the stages advance.
