Maxillary Obturator Prosthesis Made with Polyetherketoneketone Using Optical Impression and CAD/CAM System.

This report describes the case of a 68-year-old man who visited our department complaining of poor denture retention and difficulty masticating due to damage to the retainer of a maxillary obturator. The patient had never been satisfied with the fit of this prosthesis, which had been placed two years earlier. The obturator and the mucosal surface of the denture base were incompatible, which had caused the retainer to detach. The maxillary defect was categorized as H3S0D0T0 according to the HS classification. The diagnosis was a masticatory disorder due to a damaged retainer and an incompatible denture base. Optical impressions and occlusal records were taken and a maxillary obturator fabricated using a CAD/CAM system. Dental CAD software was used to design and complete the tooth arrangement. The CAM system was used to mill a polyetherketoneketone disc based on the obtained data and composite resin used to face the teeth and gingiva. The maxillary obturator was placed after only three visits, spanning from impression taking to denture completion. The use of digital data allowed the time to denture completion to be shortened in addition to the number of hospital visits to be reduced. Compared to conventional impression taking, optical impressions also prevent discomfort, decreasing stress for the patient.

Maxillofacial prosthetic treatment factors affecting oral health-related quality of life after surgery for patients with oral cancer.

STATEMENT OF PROBLEM: After oral cancer surgery, tissue defects can cause deformity and limited mobility, complicating many essential functions. For patients with mandibular, tongue, and oral floor defects, evidence regarding the effects of maxillofacial prosthetics on their oral health-related quality of life (OHRQoL) is lacking. Therefore, maxillofacial prosthetic reconstruction has been implemented with no clear treatment goals. PURPOSE: The purpose of this clinical study was to identify factors affecting the improvement of OHRQoL by using maxillofacial prosthetic treatment after surgery to repair maxillary, mandibular, tongue, and oral floor defects. MATERIAL AND METHODS: All individuals who agreed to maxillofacial prosthetics after surgery for oral cancer were enrolled. Oral function and OHRQoL were evaluated before maxillofacial prosthesis placement and 1 month after final adjustments. The oral functions evaluated included masticatory function, swallowing function, and articulatory function. The Oral Health Impact Profile (OHIP-J54) was used to evaluate OHRQoL. Factors affecting changes in the OHIP-J54 score for participants' background and oral functions before and after treatment were analyzed through logistic regression analysis (stepwise method). RESULTS: Participants included 34 men and 16 women with an average age of 72.4 ±8.7 years. "Psychological discomfort" was correlated with the patient's sex and masticatory function. "Physical disability" was related to articulatory function. "Handicap" was related to the swallowing function. "Additional Japanese questions" were related to the patient's sex. CONCLUSIONS: Participants' sex and their oral functions, including masticatory, swallowing, and articulatory functions, were associated with improved OHRQoL because of maxillofacial prosthetics after surgery for oral cancer.

Requirement of phosphatidylglycerol for maintenance of photosynthetic machinery.

Phosphatidylglycerol (PG) is a ubiquitous component of thylakoid membranes. Experiments with the pgsA mutant of the cyanobacterium Synechocystis sp. PCC6803 defective in biosynthesis of PG have demonstrated an indispensable role of PG in photosynthesis. In the present study, we have investigated the light susceptibility of the pgsA mutant with regard to the maintenance of the photosynthetic machinery. Growth of the mutant cells without PG increased the light susceptibility of the cells and resulted in severe photoinhibition of photosynthesis upon a high-light treatment, whereas the growth in the presence of PG was protected against photoinhibition. Photoinhibition induced by PG deprivation was mainly caused by an impairment of the restoration process. The primary target of the light-induced damage in thylakoid membranes, the D1 protein of photosystem (PS) II was, however, synthesized and degraded with similar rates irrespective of whether the mutant cells were incubated with PG or not. Intriguingly, it was found that instead of the synthesis of the D1 protein, the dimerization of the PSII core monomers was impaired in the PG-deprived mutant cells. Addition of PG to photoinhibited cells restored the dimerization capacity of PSII core monomers. These results suggest that PG plays an important role in the maintenance of the photosynthetic machinery through the dimerization and reactivation of the PSII core complex.

The pgp1 mutant locus of Arabidopsis encodes a phosphatidylglycerolphosphate synthase with impaired activity.

Phosphatidylglycerol is a ubiquitous phospholipid that is also present in the photosynthetic membranes of plants. Multiple independent lines of evidence suggest that this lipid plays a critical role for the proper function of photosynthetic membranes and cold acclimation. In eukaryotes, different subcellular compartments are competent for the biosynthesis of phosphatidylglycerol. Details on the plant-specific pathways in different organelles are scarce. Here, we describe a phosphatidylglycerol biosynthesis-deficient mutant of Arabidopsis, pgp1. The overall content of phosphatidylglycerol is reduced by 30%. This mutant carries a point mutation in the CDP-alcohol phosphotransferase motif of the phosphatidylglycerolphosphate synthase (EC 2.7.8.5) isoform encoded by a gene on chromosome 2. The mutant shows an 80% reduction in plastidic phosphatidylglycerolphosphate synthase activity consistent with the plastidic location of this particular isoform. Mutant plants are pale green, and their photosynthesis is impaired. This mutant provides a promising new tool to elucidate the biosynthesis and function of plastidic phosphatidylglycerol in seed plants.

Phosphatidylglycerol requirement for the function of electron acceptor plastoquinone Q(B) in the photosystem II reaction center.

Phosphatidylglycerol (PG), a ubiquitous constituent of thylakoid membranes of chloroplasts and cyanobacteria, is demonstrated to be essential for the functionality of plastoquinone electron acceptor Q(B) in the photosystem II reaction center of oxygenic photosynthesis. Growth of the pgsA mutant cells of Synechocystis sp. PCC6803 that are defective in phosphatidylglycerolphosphate synthase and are incapable of synthesizing PG, in a medium without PG, resulted in a 90% decrease in PG content and a 50% loss of photosynthetic oxygen-evolving activity as reported [Hagio, M., Gombos, Z., Várkonyi, Z., Masamoto, K., Sato, N., Tsuzuki, M., and Wada, H. (2000) Plant Physiol. 124, 795-804]. We have studied each step of the electron transport in photosystem II of the pgsA mutant to clarify the functional site of PG. Accumulation of Q(A)(-) was indicated by the fast rise of chlorophyll fluorescence yield under continuous and flash illumination. Oxidation of Q(A)(-) by Q(B) plastoquinone was shown to become slow, and Q(A)(-) reoxidation required a few seconds when measured by double flash fluorescence measurements. Thermoluminescence measurements further indicated the accumulation of the S(2)Q(A)(-) state but not of the S(2)Q(B)(-) state following the PG deprivation. These results suggest that the function of Q(B) plastoquinone was inactivated by the PG deprivation. We assume that PG is an indispensable component of the photosystem II reaction center complex to maintain the structural integrity of the Q(B)-binding site. These findings provide the first clear identification of a specific functional site of PG in the photosynthetic reaction center.

Phosphatidylglycerol is essential for the development of thylakoid membranes in Arabidopsis thaliana.

Phosphatidylglycerol is a ubiquitous phospholipid in the biological membranes of many organisms. In plants, phosphatidylglycerol is mainly present in thylakoid membranes and has been suggested to play specific roles in photosynthesis. Here, we have isolated two T-DNA tagged lines of Arabidopsis thaliana that have a T-DNA insertion in the PGP1 gene encoding a phosphatidylglycerolphosphate synthase involved in the biosynthesis of phosphatidylglycerol. In homozygous plants of the T-DNA tagged lines, the PGP1 gene was completely disrupted. The growth of these knockout mutants was dependent on the presence of sucrose in the growth medium, and these plants had pale yellow-green leaves. The leaves of the mutants had remarkably large intercellular spaces due to the reduction in the number of mesophyll cells. The development of chloroplasts in the leaf cells was severely arrested in the mutants. Mesophyll cells with chloroplast particles are only found around vascular structures, whereas epidermal cells are enlarged but largely conserved. The content of phosphatidylglycerol in the mutants was reduced to 12% of that of the wild type. These results demonstrate that PGP1 plays a major role in the biosynthesis of phosphatidylglycerol in chloroplasts, and that phosphatidylglycerol is essential for the development of thylakoid membranes in A. thaliana.