RESUMO
The catalytic cavity of the Alicyclobacillus acidocaldarius squalene-hopene cyclase is predominantly lined by aromatic amino acids. In mutant cyclases, the four tyrosine residues in the catalytic cavity were replaced by different amino acids. The mutants showed significant differences in catalytic behavior compared to the wild-type and to each other. Mutants Y609L, Y609C and Y609S produced the bicyclic main product gamma-polypodatetraene, while Y495L and Y612L showed a wild-type product pattern and produced hopene as the main product. Altered product patterns were also found with Y420 mutations.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/metabolismo , Sequência Conservada/genética , Transferases Intramoleculares/metabolismo , Mutagênese Sítio-Dirigida , Triterpenos/metabolismo , Tirosina/metabolismo , Bacillus/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Compostos Bicíclicos Heterocíclicos com Pontes/química , Domínio Catalítico/genética , Cromatografia Gasosa-Espectrometria de Massas , Transferases Intramoleculares/química , Transferases Intramoleculares/genética , Cinética , Especificidade por Substrato/genética , Triterpenos/química , Tirosina/genéticaRESUMO
The catalytic cavity of Alicyclobacillus acidocaldarius squalene-hopene cyclase is mainly lined by aromatic amino acids. In recombinant cyclases, three out of four tyrosine residues (Y) have been mutated to phenylalanine residues (F). The mutant cyclases Y495F and Y612F had less activity than the wild-type cyclase, but a wild-type product pattern. Mutant Y609F had wild-type activity but a drastically altered product pattern with hopene and significant amounts of bicyclic alpha-polypodatetraene and different tetracyclic triterpenes (dammaradienes and eupha-7,24-diene). The experiments demonstrated that Y495 and Y612 may be involved in the initiation of the cyclization reaction and Y609 in the stabilization and/or positioning of the intermediate carbocations.
Assuntos
Bacillus/enzimologia , Transferases Intramoleculares/química , Transferases Intramoleculares/fisiologia , Relação Estrutura-Atividade , TirosinaRESUMO
Using monoclonal antibody (mAb) M-Kid 2 to the alpha 3 beta 1 heterodimer, we have evaluated immunohistochemically the in vivo expression of the Vla-3 integrin in normal and transformed non-lymphoid human tissues. In normal tissues the alpha 3 beta 1 complex displays a polarized distribution at the baso-lateral aspect of most keratinizing and glandular epithelia. In addition the integrin is detected in perineurium, basal lamina of smooth muscular fibers, vascular media, podocytes and Bowman's capsule, myoepithelial cells of the parotid and breast, and in pulmonary alveoli. Neoplastic transformation is associated with qualitative and quantitative changes in expression of this integrin. The loss of polarized distribution often occurs in various malignancies. Furthermore, a significant decrease in expression occurs in 13% of the colon-rectum carcinomas, 75% of the ductal invasive, and 40% of the lobular invasive breast carcinomas. Among the lung malignancies tested, the small cell lung carcinomas (SCLC) were found to be consistently unreactive with mAb M-Kid 2. Analysis of Vla-3 expression in established tumor cell lines demonstrated that the integrin is almost invariably expressed by the plastic adherent cell subpopulations.
Assuntos
Neoplasias/metabolismo , Receptores de Antígeno muito Tardio/metabolismo , Anticorpos Monoclonais , Humanos , Neoplasias/patologia , Valores de Referência , Distribuição Tecidual , Células Tumorais Cultivadas/metabolismoRESUMO
The fundamental data requirements for the authorization of plant protection products and the inclusion of active ingredients in Annex I of Council Directive 91/414/EEC (Council Directive of 15 July 1991 referring to placing plant protection products on the market (91/414/EEC). Official Journal of European Communities L 230, 19 August 1991) are described in the Annexes II and III of this Directive. Definite instructions with regard to preconditions for implementation and methodology (guidelines) concerning investigations with terrestrial plants are deficient. In addition to that, the uniform principles for the registration of plant protection products in the Member States described in Annex VI of the directive do not include any criteria concerning the risk assessment for non-target plants. However, plant protection products often show effects on non-target plants which need to be assessed as a requirement for the authorisation of the product. Hence, the German Federal Environmental Agency has developed a tiered approach to assess the effects of plant protection products on non-terrestrial plants. The risk is assessed using the effect-concentration evaluated in ecotoxicological tests and the environmental concentration predicted by validated exposure models. To protect non-target plants in terrestrial ecosystems assessment factors need to be considered. In the future, the risk for terrestrial plants needs to be addressed, also with regard to the revision of the Annexes of Directive 91/414/EEC.
Assuntos
Ecossistema , Praguicidas/normas , Plantas , Agricultura , Exposição Ambiental , Valores de Referência , Medição de Risco , Testes de ToxicidadeRESUMO
This report describes the surgical and orthodontic management of a patient with a palatally impacted permanent maxillary canine. Following surgical exposure, orthodontic traction was applied to reposition the canine with resultant proper functioning, excellent esthetics, and good periodontal health.
Assuntos
Técnicas de Movimentação Dentária/métodos , Dente Impactado/cirurgia , Adolescente , Dente Canino , Feminino , Humanos , Dente não Erupcionado/cirurgiaRESUMO
Using a 0.028 stainless steel wire, an appliance was fabricated to fit from the distal aspects of the laterals to the mesial side of the maxillary molars where it floats freely. Interarch Class II elastics with the potential of 16 ounces of force were used from the hooks to the lower first molar. The appliance was worn approximately 6 weeks to distalize the maxillary molar.
Assuntos
Má Oclusão Classe II de Angle/terapia , Dente Molar , Aparelhos Ortodônticos , Técnicas de Movimentação Dentária/instrumentação , Criança , Aparelhos de Tração Extrabucal , Feminino , Humanos , Maxila , Desenho de Aparelho Ortodôntico , Fios Ortodônticos , Planejamento de Assistência ao Paciente , Técnicas de Movimentação Dentária/métodosAssuntos
Coroas , Dente Molar , Aço Inoxidável/uso terapêutico , Dente Decíduo , Anestésicos , Cárie Dentária/cirurgia , Preparo da Cavidade Dentária , Cimentos Dentários/uso terapêutico , Instrumentos Odontológicos , Humanos , Dente Molar/anatomia & histologia , Pulpectomia , Pulpotomia , Dente Decíduo/anatomia & histologiaRESUMO
Standard of practice does not always equal standard of care. When faced with a problematic situation, the dentist will either treat from experience, or else depend on what has been suggested by others. In some cases, anecdotal information may not be applicable. Recommended clinical procedures have not always been supported by adequate research. Although midline correction has been expressed as a certainty, it does not always occur. Patience on the part of the practitioner will allow the child to be observed periodically, and at the same time allow the dentition to develop naturally. Orthodontic treatment can always be used, once the permanent canines erupt.