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Int. j. odontostomatol. (Print) ; 13(3): 310-315, set. 2019. graf
Artigo em Espanhol | LILACS-Express | ID: biblio-1012428


RESUMEN: La odontodisplasia regional (OR) es una alteración en el desarrollo, no hereditario y que afecta tanto la dentición temporal como la dentición definitiva. Involucra a los tejidos mesodérmicos y ectodérmicos de los dientes lo que es condescendiente con hallazgos clínicos, radiográficos e histológicos. Su etiología aun es desconocida y se presenta mayoritariamente en mujeres. Clínicamente puede afectar al maxilar, a la mandíbula o ambas arcadas pero generalmente solo se ve comprometida una ellas, principalmente el más afectado es el hueso maxilar. Radiográficamente se observa una pobre diferencia entre los tejidos del esmalte y la dentina, siendo tejidos menos radiopacos que su contraparte sana generando un aspecto descrito como "diente fantasma". Histológicamente se observan zonas hipocalcificadas del esmalte con un orden de prismas irregulares mientras que la dentina se observa con un número reducido de túbulos dentinarios y de consistencia más fibrosa en su zona coronal. El tratamiento de la OR es controversial ya que su incidencia es baja y la literatura al respecto no es clara. El objetivo de este manuscrito, fue reportar un caso de OR y revisar la literatura relacionada. Presentamos un caso de OR en una paciente de 12 años que presenta ausencia de los dientes 2.4, 2.5 y 2.6; restos radiculares y agenesia de los dientes 3.5 y 4.5. Se describirán sus aspectos clínicos, radiográficos e histológicos. Se realizó una búsqueda sistemática en las siguientes bases de datos: Clínical key, Science Direct, PubMed y SciELO.

ABSTRACT: Regional odontodysplasia (RO) is a variation in the development; it is not hereditary and it affects both deciduous and permanent dentition. It involves the mesodermal and ectodermal tissues of dental pieces, and coincides with clinical, radiographic and histological findings. Its etiology is still unknown and it reportedly occurs mostly in women. Clinically it can affect the maxilla, mandible or both arches but generally only one is compromised, mainly the maxilla which is affected the most. Radiographically there is limited difference between enamel and dentin tissue, which is less radiopaque than their healthy counterpart, generating an aspect described as "phantom tooth". Histologically hypocalcified areas of the enamel are observed with an irregular order of prisms while the dentine is observed with a reduced number of dentinal tubules and more fibrous consistency in the coronal area. RO treatment is controversial since its incidence is low and the literature on these events is not clear. The aim of this manuscript was to report a case of RO and review related literature. We present a case of RO in a 12-year-old patient who presents absence of parts and 2.6; radicular remains and agenesis of parts 3.5 and 4.5. Its clinical, radiographic and histological aspects are described. A systematic search was carried out in the following databases: Clinical key, Science Direct, PubMed and SciELO.

Biotechnol Prog ; : e2893, 2019 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-31425642


Whole cell biocatalysis is an ideal tool for biotransformations that demand enzyme regeneration or robustness to fluctuating pH, osmolarity and bio-contaminant load in feedstocks. The methylotrophic yeast Komagataella phaffii (K. phaffii) is an attractive alternative to Escherichia coli (E. coli) for whole cell biocatalysis due to its genetic tractability and capacity to grow to up to 60% wet cell weight by volume. We sought to exploit high cell density K. phaffii to intensify whole-cell chiral amino-alcohol (CAA) biosynthesis. We engineered two novel K. phaffii GS115 strains: one by inserting a Chromobacterium violaceum ω-transaminase CV2025 transgene, for strain PpTAmCV708, and a second strain, PpTAm-TK16, by also inserting the same CV2025 transgene plus a second transgene for a native transketolase. At high cell density, both strains tolerated high substrate concentrations. When fed three low cost substrates, 200 mM glycolaldehyde, 200 mM hydroxypyruvate and 150 mM methylbenzylamine, PpTAm-TK16 whole cells achieved 0.29 g L-1  h-1 space-time yield of the acetophenone by-product, a 49-fold increase of the highest levels reported for E. coli whole cells harbouring the equivalent pathway. When fed only the low-cost substrate, 150 mM methylbenzylamine, strain PpTAmCV708 achieved a 105-fold increase of reported E. coli whole cell biocatalysis performance, with a space-time yield of 0.62 g L-1  h-1 of the CAA, 2-amino-1,3,4-butanetriol (ABT). The rapid growth and high biomass characteristics of K. phaffii were successfully exploited for production of ABT by whole-cell biocatalysis at higher levels than the previously achieved with E. coli in the presence of the same substrates. This article is protected by copyright. All rights reserved.

Biotechnol Prog ; 34(1): 99-106, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29086489


Transketolase is a proven biocatalytic tool for asymmetric carbon-carbon bond formation, both as a purified enzyme and within bacterial whole-cell biocatalysts. The performance of Pichia pastoris as a host for transketolase whole-cell biocatalysis was investigated using a transketolase-overexpressing strain to catalyze formation of l-erythrulose from ß-hydroxypyruvic acid and glycolaldehyde substrates. Pichia pastoris transketolase coding sequence from the locus PAS_chr1-4_0150 was subcloned downstream of the methanol-inducible AOX1 promoter in a plasmid for transformation of strain GS115, generating strain TK150. Whole and disrupted TK150 cells from shake flasks achieved 62% and 65% conversion, respectively, under optimal pH and methanol induction conditions. In a 300 µL reaction, TK150 samples from a 1L fed-batch fermentation achieved a maximum l-erythrulose space time yield (STY) of 46.58 g L-1 h-1 , specific activity of 155 U gCDW-1, product yield on substrate (Yp/s ) of 0.52 mol mol-1 and product yield on catalyst (Yp/x ) of 2.23g gCDW-1. We have successfully exploited the rapid growth and high biomass characteristics of Pichia pastoris in whole cell biocatalysis. At high cell density, the engineered TK150 Pichia pastoris strain tolerated high concentrations of substrate and product to achieve high STY of the chiral sugar l-erythrulose. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 34:99-106, 2018.