Effect of Copper Nanoparticles on the Flexural Strength of Heat Polymerized Acrylic Resin.

The aim of this study was to investigate the flexural strength of heat cure acrylic resin reinforced with varying concentration copper nanoparticles. The study followed ISO 20795-1-2013 guidelines for estimating the flexural strength. Hundred samples of heat cure acrylic resin of dimension were fabricated. The study had five groups and each group had 20 samples. The samples were grouped as per the concentration of copper (Cu) nanoparticles in acrylic. Three-point bending flexural strength was evaluated with universal testing machine. The load was directed at the midpoint of the sample at a cross-sectional speed of 5 mm/min. The fractured load was recorded and flexural strength was estimated. The data were statistically analyzed with analysis of variance and the post hoc test. The results displayed improved flexural strength in lower Cu concentrations. The increase in flexural strength was observed in 1% (78.38 MPa), 2% (73.08 MPa), and 3% (73.08 MPa) of Cu nanoparticles and it decreased beyond 3% increase in Cu nanoparticles. The tests were statistically insignificant (P <.05). The results concluded that the optimal concentration of Cu nanoparticles to be reinforced with heat cure PMMA is 1 gm. The flexural strength decreased with an increase in concentration of Cu nanoparticles.

Comparison of Masticatory Efficiency and Patient Satisfaction of Injection-Molded Conventional Complete Dentures and Biofunctional Prosthetic System Dentures: A Parallel Randomized Clinical Trial.

Introduction Complete loss of natural teeth severely compromises the masticatory efficiency of geriatric patients and directly affects their general health. Biofunctional prosthetic system (BPS) has been developed as an alternate method of denture fabrication to match the higher expectations of patients. Studies comparing BPS dentures with injection-molded conventional complete dentures (IM-CCD) are lacking. Our study aimed to compare the masticatory efficiency and patient satisfaction of BPS dentures with IM-CCD. Methods This trial was designed as a randomized, prospective, single-center, double-blinded study with two parallel arms (BPS group and IM-CCD group) having an equal allocation (1:1). Completely edentulous patients aged 45-80 who visited our outpatient department between January and August 2018 were screened and enrolled according to our inclusion and exclusion criteria. Random sequence generation was done using an online randomization program. Allocation concealment was done using sequentially labeled opaque envelopes. The participants and the outcome assessors were blinded. A single operator performed all the clinical procedures in both groups under the guidance of the instructor. The age and gender of the patients were recorded for demographic data at baseline. Primary outcomes were assessed six weeks after denture insertion. The number of denture adjustments required during the first six weeks after denture delivery was recorded as the secondary outcome. Masticatory efficiency was evaluated by the volumetric single-sieve method. An abbreviated version of the Oral Health Impact Profile questionnaire for edentulous patients (OHIP-EDENT) was used for patient satisfaction scores. The total OHIP-EDENT score was calculated by adding all the responses to the 19 questions (ranging from 0 to 38). Individual domain scores were calculated by adding the response to all the questions in that domain. All the data obtained were tested for normality using the Kolmogorov-Smirnov test. Data were analyzed using either unpaired Student's T-test or Mann-Whitney U test for normal and non-normal data, respectively. The gender characteristics of the sample were compared using Chi-Square test. Results Two patients in the IM-CCD group and one patient in the BPS group were lost to follow-up. Hence only the secondary outcome data were analyzed for these patients. Primary outcome data of patients who were lost to follow-up were excluded from the analysis. No significant differences (p>0.05) were found between the two groups for age and gender characteristics of the samples. Masticatory efficiency for both peanut and carrot was found to be significantly higher (p<0.05) in the BPS group than in the IM-CCD group. No significant differences (p>0.05) in the mean scores were observed between the two groups for total OHIP-EDENT scores or the individual domain scores. No significant differences (p>0.05) were observed between the groups for the number of denture adjustments done. Conclusion Within the limitations of the trial, it can be concluded that the BPS dentures significantly improved the masticatory efficiency for both hard (carrots) and soft (peanuts) foods compared to the IM-CCD. However, there was no difference between the masticatory-related complaints domain scores between the two dentures. No significant differences were found between BPS dentures and IM-CCD with respect to overall patient satisfaction scores or post-insertion denture adjustments.

Oral Rehabilitation of a Patient with Papillon Lefèvre Syndrome Using Fixed Full-Arch Hybrid Prostheses Supported by Four Axially Loaded Implants: A Case Report with Four-Year Follow-up.

This report details the successful prosthetic rehabilitation of a 25-year-old male patient with Papillon Lefèvre Syndrome (PLS) using an implant-supported hybrid prosthesis. Six implants were placed in the maxilla, and four were placed in the mandibular arch. All implants were inserted axially (non-tilted) and were planned to be loaded after a healing period of 6 months. One implant failed due to graft loss during the healing phase, which was removed and the remaining implants were restored with a hybrid prosthesis after 6 months, using the delayed loading protocol. The patient was followed-up for four years and all the remaining implants successfully integrated and remained fully functional during this period. The prosthesis significantly improved the functional, aesthetic, and psychological well-being of the patient. This case report is the first of its kind to use only four axially placed implants for rehabilitation of a PLS patient with a successful four-year follow-up.

Effect of Laser Etching and Spark Erosion on Retention and Resistance of Partial Veneer Crown Copings Luted with Adhesive Resin Cement.

PURPOSE: There has been less focus on methods to improve the clinical performance of partial veneer crowns. In this study, we wanted to explore the potential of two new surface treatment modalities (laser etching and spark erosion) for improving the longevity of partial veneer crowns. MATERIAL AND METHODS: Conventional partial veneer crown preparation was done on 90 extracted premolars by a single operator. All the samples used in the study were divided into three groups. Group A were samples to be treated by sandblasting alone, Group B were samples to be treated by sandblasting followed by laser etching, and Group C were samples to be treated by sandblasting followed by spark erosion. Each group consisted of two Sub Groups: Sub Group I-Retention test group, Sub Group: II-Resistance test group. The prepared teeth were randomly allotted to the three groups and subgroups using lot method. Partial veneer crown copings were fabricated for testing retention and resistance. Castings in each subgroup were luted with resin cement to their respective tooth preparations. Retention and resistance testing of samples were done with the use of an Instron Universal testing machine. RESULTS: The two surface treatments, laser etching and spark erosion (Groups B and C) of metal copings significantly improved the retention and resistance compared to sandblasted surfaces alone (P ≤ 0.05). Retention and resistance of copings which were sandblasted and spark eroded (Group C) were found to be highest among the three groups (P ≤ 0.05). CONCLUSION: Within the limitation of this study, it can be concluded that the combination of spark erosion and sandblasting significantly improves the retention and resistance values of partial veneer crown. This study helps to provide better knowledge about the surface treatment required for success of partial veneer crowns.

Engineered selective plant male sterility through pollen-specific expression of the EcoRI restriction endonuclease.

Unintended gene flow from transgenic plants via pollen, seed and vegetative propagation is a regulatory concern because of potential admixture in food and crop systems, as well as hybridization and introgression to wild and weedy relatives. Bioconfinement of transgenic pollen would help address some of these concerns and enable transgenic plant production for several crops where gene flow is an issue. Here, we demonstrate the expression of the restriction endonuclease EcoRI under the control of the tomato pollen-specific LAT52 promoter is an effective method for generating selective male sterility in Nicotiana tabacum (tobacco). Of nine transgenic events recovered, four events had very high bioconfinement with tightly controlled EcoRI expression in pollen and negligible-to-no expression other plant tissues. Transgenic plants had normal morphology wherein vegetative growth and reproductivity were similar to nontransgenic controls. In glasshouse experiments, transgenic lines were hand-crossed to both male-sterile and emasculated nontransgenic tobacco varieties. Progeny analysis of 16 000-40 000 seeds per transgenic line demonstrated five lines approached (>99.7%) or attained 100% bioconfinement for one or more generations. Bioconfinement was again demonstrated at or near 100% under field conditions where four transgenic lines were grown in close proximity to male-sterile tobacco, and 900-2100 seeds per male-sterile line were analysed for transgenes. Based upon these results, we conclude EcoRI-driven selective male sterility holds practical potential as a safe and reliable transgene bioconfinement strategy. Given the mechanism of male sterility, this method could be applicable to any plant species.

Physiological and transcriptional responses of Baccharis halimifolia to the explosive "composition B" (RDX/TNT) in amended soil.

Unexploded explosives that include royal demolition explosive (RDX) and trinitrotoluene (TNT) cause environmental concerns for surrounding ecosystems. Baccharis halimifolia is a plant species in the sunflower family that grows naturally near munitions sites on contaminated soils, indicating that it might have tolerance to explosives. B. halimifolia plants were grown on 100, 300, and 750 mg kg(-1) of soil amended with composition B (Comp B) explosive, a mixture of royal demolition explosive and trinitrotoluene. These concentrations are environmentally relevant to such munitions sites. The purpose of the experiment was to mimic contaminated sites to assess the plant's physiological response and uptake of explosives and to identify upregulated genes in response to explosives in order to better understand how this species copes with explosives. Stomatal conductance was not significantly reduced in any treatments. However, net photosynthesis, absorbed photons, and chlorophyll were significantly reduced in all treatments relative to the control plants. The dark-adapted parameter of photosynthesis was reduced only in the 750 mg kg(-1) Comp B treatment. Thus, we observed partial physiological tolerance to Comp B in B. halimifolia plants. We identified and cloned 11 B. halimifolia gene candidates that were orthologous to explosive-responsive genes previously identified in Arabidopsis and poplar. Nine of those genes showed more than 90% similarity to Conyza canadensis (horseweed), which is the closest relative with significant available genomics resources. The expression patterns of these genes were studied using quantitative real-time PCR. Three genes were transcriptionally upregulated in Comp B treatments, and the Cytb6f gene was found to be highly active in all the tested concentrations of Comp B. These three newly identified candidate genes of this explosives-tolerant plant species can be potentially exploited for uses in phytoremediation by overexpressing these genes in transgenic plants and, similarly, by using promoters or variants of promoters from these genes fused to reporter genes in transgenic plants for making phytosensors to report the localized presence of explosives in contaminated soils.

Stable transformation of ferns using spores as targets: Pteris vittata and Ceratopteris thalictroides.

Ferns (Pteridophyta) are very important members of the plant kingdom that lag behind other taxa with regards to our understanding of their genetics, genomics, and molecular biology. We report here, to our knowledge, the first instance of stable transformation of fern with recovery of transgenic sporophytes. Spores of the arsenic hyperaccumulating fern Pteris vittata and tetraploid 'C-fern Express' (Ceratopteris thalictroides) were stably transformed by Agrobacterium tumefaciens with constructs containing the P. vittata actin promoter driving a GUSPlus reporter gene. Reporter gene expression assays were performed on multiple tissues and growth stages of gametophytes and sporophytes. Southern-blot analysis confirmed stable transgene integration in recovered sporophytes and also confirmed that no plasmid from A. tumefaciens was present in the sporophyte tissues. We recovered seven independent transformants of P. vittata and four independent C. thalictroides transgenics. Inheritance analyses using ß-glucuronidase (GUS) histochemical staining revealed that the GUS transgene was stably expressed in second generation C. thalictroides sporophytic tissues. In an independent experiment, the gusA gene that was driven by the 2× Cauliflower mosaic virus 35S promoter was bombarded into P. vittata spores using biolistics, in which putatively stable transgenic gametophytes were recovered. Transformation procedures required no tissue culture or selectable marker genes. However, we did attempt to use hygromycin selection, which was ineffective for recovering transgenic ferns. This simple stable transformation method should help facilitate functional genomics studies in ferns.

Root suberin forms an extracellular barrier that affects water relations and mineral nutrition in Arabidopsis.

Though central to our understanding of how roots perform their vital function of scavenging water and solutes from the soil, no direct genetic evidence currently exists to support the foundational model that suberin acts to form a chemical barrier limiting the extracellular, or apoplastic, transport of water and solutes in plant roots. Using the newly characterized enhanced suberin1 (esb1) mutant, we established a connection in Arabidopsis thaliana between suberin in the root and both water movement through the plant and solute accumulation in the shoot. Esb1 mutants, characterized by increased root suberin, were found to have reduced day time transpiration rates and increased water-use efficiency during their vegetative growth period. Furthermore, these changes in suberin and water transport were associated with decreases in the accumulation of Ca, Mn, and Zn and increases in the accumulation of Na, S, K, As, Se, and Mo in the shoot. Here, we present direct genetic evidence establishing that suberin in the roots plays a critical role in controlling both water and mineral ion uptake and transport to the leaves. The changes observed in the elemental accumulation in leaves are also interpreted as evidence that a significant component of the radial root transport of Ca, Mn, and Zn occurs in the apoplast.

The leaf ionome as a multivariable system to detect a plant's physiological status.

The contention that quantitative profiles of biomolecules contain information about the physiological state of the organism has motivated a variety of high-throughput molecular profiling experiments. However, unbiased discovery and validation of biomolecular signatures from these experiments remains a challenge. Here we show that the Arabidopsis thaliana (Arabidopsis) leaf ionome, or elemental composition, contains such signatures, and we establish statistical models that connect these multivariable signatures to defined physiological responses, such as iron (Fe) and phosphorus (P) homeostasis. Iron is essential for plant growth and development, but potentially toxic at elevated levels. Because of this, shoot Fe concentrations are tightly regulated and show little variation over a range of Fe concentrations in the environment, making them a poor probe of a plant's Fe status. By evaluating the shoot ionome in plants grown under different Fe nutritional conditions, we have established a multivariable ionomic signature for the Fe response status of Arabidopsis. This signature has been validated against known Fe-response proteins and allows the high-throughput detection of the Fe status of plants with a false negative/positive rate of 18%/16%. A "metascreen" of previously collected ionomic data from 880 Arabidopsis mutants and natural accessions for this Fe response signature successfully identified the known Fe mutants frd1 and frd3. A similar approach has also been taken to identify and use a shoot ionomic signature associated with P homeostasis. This study establishes that multivariable ionomic signatures of physiological states associated with mineral nutrient homeostasis do exist in Arabidopsis and are in principle robust enough to detect specific physiological responses to environmental or genetic perturbations.

Variation in molybdenum content across broadly distributed populations of Arabidopsis thaliana is controlled by a mitochondrial molybdenum transporter (MOT1).

Molybdenum (Mo) is an essential micronutrient for plants, serving as a cofactor for enzymes involved in nitrate assimilation, sulfite detoxification, abscisic acid biosynthesis, and purine degradation. Here we show that natural variation in shoot Mo content across 92 Arabidopsis thaliana accessions is controlled by variation in a mitochondrially localized transporter (Molybdenum Transporter 1 - MOT1) that belongs to the sulfate transporter superfamily. A deletion in the MOT1 promoter is strongly associated with low shoot Mo, occurring in seven of the accessions with the lowest shoot content of Mo. Consistent with the low Mo phenotype, MOT1 expression in low Mo accessions is reduced. Reciprocal grafting experiments demonstrate that the roots of Ler-0 are responsible for the low Mo accumulation in shoot, and GUS localization demonstrates that MOT1 is expressed strongly in the roots. MOT1 contains an N-terminal mitochondrial targeting sequence and expression of MOT1 tagged with GFP in protoplasts and transgenic plants, establishing the mitochondrial localization of this protein. Furthermore, expression of MOT1 specifically enhances Mo accumulation in yeast by 5-fold, consistent with MOT1 functioning as a molybdate transporter. This work provides the first molecular insight into the processes that regulate Mo accumulation in plants and shows that novel loci can be detected by association mapping.

Transcriptional activation and localization of expression of Brassica juncea putative metal transport protein BjMTP1.

BACKGROUND: Metal hyperaccumulators, including various Thlaspi species, constitutively express the putative metal transporter MTP1 to high levels in shoots. Here we present data on the transcriptional regulation and localization of expression of the homologous gene BjMTP1 in Brassica juncea. Though B. juncea lacks the ability to hyperaccumulate metals, its relatively high biomass, rapid growth and relatedness to true metal hyperaccumulating plants makes it a promising starting point for the development of plants for phytoremediation. Our goal in this study is to determine the transcriptional regulation of MTP1 in order to start to better understanding the physiological role of MTP1 in B. juncea. RESULTS: Steady-state mRNA levels of BjMTP1 were found to be enhanced 8.8, 5.9, and 1.6-fold in five-day-old B. juncea seedlings after exposure to Ni2+, Cd2+ or Zn2+, respectively. This was also reflected in enhanced GUS activity in B. juncea seedlings transformed with BjMTP1 promoter::GUSPlus after exposure to these metals over a similar range of toxicities from mild to severe. However, no increase in GUS activity was observed after exposure of seedlings to cold or heat stress, NaCl or hydrogen peroxide. GUS expression in Ni2+ treated seedlings was localized in roots, particularly in the root-shoot transition zone. In four- week- old transgenic plants BjMTP1 promoter activity also primarily increased in roots in response to Ni2+ or Cd2+ in plants transformed with either GUS or mRFP1 as reporter genes, and expression was localized to the secondary xylem parenchyma. In leaves, BjMTP1 promoter activity in response to Ni2+ or Cd2+ spiked after 24 h then decreased. In shoots GUS expression was prominently present in the vasculature of leaves, and floral parts. CONCLUSION: Our studies establish that a 983 bp DNA fragment upstream of the BjMTP1 translational start site is sufficient for the specific activation by Ni2+ and Cd2+ of BjMTP1 expression primarily in roots. Activation of expression by both metals in roots is primarily localized to the xylem parenchyma cells. This study is the first to identify specific Ni2+ and Cd2+ transcriptional regulation and tissue localization of BjMTP1.

Natural variants of AtHKT1 enhance Na+ accumulation in two wild populations of Arabidopsis.

Plants are sessile and therefore have developed mechanisms to adapt to their environment, including the soil mineral nutrient composition. Ionomics is a developing functional genomic strategy designed to rapidly identify the genes and gene networks involved in regulating how plants acquire and accumulate these mineral nutrients from the soil. Here, we report on the coupling of high-throughput elemental profiling of shoot tissue from various Arabidopsis accessions with DNA microarray-based bulk segregant analysis and reverse genetics, for the rapid identification of genes from wild populations of Arabidopsis that are involved in regulating how plants acquire and accumulate Na(+) from the soil. Elemental profiling of shoot tissue from 12 different Arabidopsis accessions revealed that two coastal populations of Arabidopsis collected from Tossa del Mar, Spain, and Tsu, Japan (Ts-1 and Tsu-1, respectively), accumulate higher shoot levels of Na(+) than do Col-0 and other accessions. We identify AtHKT1, known to encode a Na(+) transporter, as being the causal locus driving elevated shoot Na(+) in both Ts-1 and Tsu-1. Furthermore, we establish that a deletion in a tandem repeat sequence approximately 5 kb upstream of AtHKT1 is responsible for the reduced root expression of AtHKT1 observed in these accessions. Reciprocal grafting experiments establish that this loss of AtHKT1 expression in roots is responsible for elevated shoot Na(+). Interestingly, and in contrast to the hkt1-1 null mutant, under NaCl stress conditions, this novel AtHKT1 allele not only does not confer NaCl sensitivity but also cosegregates with elevated NaCl tolerance. We also present all our elemental profiling data in a new open access ionomics database, the Purdue Ionomics Information Management System (PiiMS; http://www.purdue.edu/dp/ionomics). Using DNA microarray-based genotyping has allowed us to rapidly identify AtHKT1 as the casual locus driving the natural variation in shoot Na(+) accumulation we observed in Ts-1 and Tsu-1. Such an approach overcomes the limitations imposed by a lack of established genetic markers in most Arabidopsis accessions and opens up a vast and tractable source of natural variation for the identification of gene function not only in ionomics but also in many other biological processes.