Nitric oxide deficiency decreases C-repeat binding factor-dependent and -independent induction of cold acclimation.

Plant tolerance to freezing temperatures is governed by endogenous components and environmental factors. Exposure to low non-freezing temperatures is a key factor in the induction of freezing tolerance in the process called cold acclimation. The role of nitric oxide (NO) in cold acclimation was explored in Arabidopsis using triple nia1nia2noa1-2 mutants that are impaired in the nitrate-dependent and nitrate-independent pathways of NO production, and are thus NO deficient. Here, we demonstrate that cold-induced NO accumulation is required to promote the full cold acclimation response through C-repeat Binding Factor (CBF)-dependent gene expression, as well as the CBF-independent expression of other cold-responsive genes such as Oxidation-Related Zinc Finger 2 (ZF/OZF2). NO deficiency also altered abscisic acid perception and signaling and the cold-induced production of anthocyanins, which are additional factors involved in cold acclimation.

Influence on peri-implant bone loss of different fixed partial dentures retained on 2 implants.

STATEMENT OF PROBLEM: Marginal bone loss is key to determining the success of dental implants. However, how different factors, including the extension or span of implant-supported restorations and implant position, affect bone loss is unclear. PURPOSE: The purpose of this prospective clinical study was to analyze peri-implant bone loss 3 years after loading by evaluating the influence of implant position and prosthetic type and comparing splinted crowns and 3- or 4-unit fixed partial dentures (FPDs) to determine whether 2 dental implants can achieve comparable success when replacing 2, 3, or 4 missing teeth. MATERIAL AND METHODS: Sixty-two adjacent dental implants in 23 participants were investigated. The implants supported noncantilevered restorations: 2 splinted crowns or 3- or 4-unit FPDs. Bone loss was evaluated 3 years after loading from periapical radiographs using AutoCAD software. Nonparametric comparisons were made. The Wilcoxon test was applied to determine homogeneity of related samples. The Mann-Whitney test was applied to measure homogeneity of bone loss in 2 independent samples and the presence/absence of a pontic in the restoration (α=.05). RESULTS: Mean ±standard deviation peri-implant bone loss was 0.9 ±0.7 mm. The peri-implant bone loss of the restorations analyzed was similar to the average values of 1.1 ±0.8 mm for 3- and 4-unit FPDs and 0.8 ±0.6 mm for splinted crowns. The type of prosthodontic restoration and implant position did not show significant influences on bone loss (P>.05). CONCLUSIONS: Mean bone loss values were within an acceptable range. Statistically significant relationships were not found between the restoration types, suggesting that 3 or 4 missing teeth can be replaced by 2 implants. Further studies with longer follow-ups are needed to obtain clinically applicable conclusions.

Behavior of Human Osteoblast Cells Cultured on Titanium Discs in Relation to Surface Roughness and Presence of Melatonin.

The aim of this work was to observe the behavior of osteoblast cells cultured in vitro on titanium discs in relation to disc surface roughness and the addition of melatonin to the culture medium. MG63 osteoblast cells were cultivated on 120 Grade 5 Ti divided into three groups: Group E, treated with dual acid etch; Group EP, treated with dual acid etch and calcium phosphate; and Group M, machined. Surface roughness was examined under a laser scanning confocal microscope (CLSM) and scanning electron microscopy (SEM). The proliferation and morphology of cells were determined under fluorescence microscopy and SEM. Messenger ribonucleic acid (mRNA) of different genes related to osteoblastic differentiation was quantified by means of real-time quantitative polymerase chain reaction (RT-PCR) assay. The greatest surface roughness was found in Group EP (Ra 0.354 µm), followed by Group E (Ra 0.266 µm), and Group M (Ra 0.131 µm), with statistically significant differences between the groups (p < 0.001). In the presence of melatonin a trend to a higher cell proliferation was observed in all groups although significant differences were only found in Group M (p = 0.0079). Among the genes studied, a significant increase in phosphate-regulating neutral endopeptidase, X-linked (PHEX) expression was observed in cells cultured on EP discs. The addition of melatonin increased osteoblast cell proliferation and differentiation, and may favor the osseointegration of dental implants.

Vertical preparation for fixed prosthesis rehabilitation in the anterior sector.

This clinical report describes a biologically oriented preparation technique (BOPT) for teeth and an implant for the esthetic rehabilitation of the maxillary anterior sector. The technique was designed to create an anatomic crown with a prosthetic emergence profile that simulated the shape of the natural tooth.

An implant-supported overdenture design with a horizontal path of insertion.

The rehabilitation of the atrophic maxilla by means of implant-supported prostheses cannot always be achieved with fixed prostheses because of anatomic, esthetic, or economic issues, so for some patients the treatment of choice is a removable prosthesis. This article analyzes a new design for implant-supported overdentures with horizontal or faciolingual insertion. Its retention system is based on frictional forces or stepped interlocking horizontal surfaces and is appropriate for patients with skeletal Class II or III relationships with severe maxillary atrophies. The design facilitates implant-prosthetic hygiene and improved esthetics in patients with nonparallel implants by hiding abutment screws.

Periodontal and prosthetic outcomes on teeth prepared with biologically oriented preparation technique: a 4-year follow-up prospective clinical study.

PURPOSE: To evaluate the clinicaland biological behavior of full coverage restorations on teeth prepared without finish line during a 4-year follow-up. METHODS: This prospective study included 149 teeth treated using biologically oriented preparation technique (BOPT). The sample (149 teeth) was divided into two groups: Seventy four teeth restored with crowns, and 75 teeth supporting fixed partial dentures (FPD). Restorations were fabricated with zirconium oxide cores and ceramic coverings. Patients attended regular annual check-ups when probe depth, presence of inflammation with bleeding on probing, presence of plaque, gingival thickness, marginal stability, biological or mechanical complications, and the patient's level of satisfaction were registered over a 4-year follow-up. RESULTS: After the 4-year follow-up, 2.1% of teeth underwent increases in probing depth; 12% of the sample presented inflammation and bleeding on probing; 20% of the restored teeth presented plaque; gingival thickening increased a 32.5%; 98.6% of teeth presented marginal stability; the restoration survival rate was 96.6%, with 2% of biological complications and 1.4% of mechanical complications. General satisfaction score was 80.73. CONCLUSIONS: Restorations placed on teeth prepared using BOPT present good periodontal behavior, increase of gingival thickening, and marginal stability over a 4-year follow-up. High survival rates after 4 years show that the technique produces predictable outcomes. CLINICAL SIGNIFICANCE: The BOPT technique is a good treatment option in cases where replacement of an old restoration is required; presenting good periodontal behavior, gingival thickening, and marginal stability.

Influence of Transmucosal Area Morphology on Peri-Implant Bone Loss in Tissue-Level Implants.

PURPOSE: To analyze peri-implant bone loss around two types of tissue-level implants (convergent and divergent transmucosal morphology) placed in the same region of either the maxilla or mandible in a single surgical session. MATERIALS AND METHODS: This prospective study included 21 patients who each received two implants, one with a convergent transmucosal collar (n = 21) the other with a divergent collar (n = 21). Implants were placed in a single surgical session, by the same clinician, in the same clinical setting at the Prosthodontic and Occlusion Unit, University of Valencia (Spain). The implants (n = 42) were restored with splinted crowns screwed directly onto the prosthetic platforms. Bone loss analysis consisted of measurements taken from periapical radiographs 24 months after loading. Statistical analysis evaluated the homogeneity of the groups using Pearson's chisquare test; bone loss was compared with the Wilcoxon test. Statistical significance was set at 5% (α = .05), with a confidence interval of 95% and a power of 57%. RESULTS: Implants with convergent transmucosal morphology presented less mean peri-implant bone loss (0.29 ± 0.34 mm) than those with divergent transmucosal morphology (0.60 ± 0.63 mm), with a statistically significant difference between the two types of implants (P = .031). CONCLUSION: Less peri-implant bone loss occurs around supracrestal implants with convergent transmucosal morphology than divergent transmucosal morphology.

Influence of Implant-Prosthetic Connection on Peri-Implant Bone Loss: A Prospective Clinical Trial with 2-Year Follow-up.

PURPOSE: To analyze peri-implant bone loss around six different types of implant-prosthetic connections over a 2-year follow-up period. MATERIALS AND METHODS: A total of 120 implants were divided into six groups (n = 20), three with crestally and three with supracrestally placed implants, with different internal connections, placed in posterior sectors (molar and premolar), and bearing one-piece CAD/CAM restorations screwed directly to each implant's prosthetic platform. Bone height was measured from parallelized periapical radiographs taken at the moment of loading and 2 years later. RESULTS: The patient sample included 61 subjects, 36 men and 25 women. Significant differences were found in bone loss between groups, the implant with internal hex and convergent transmucosal collar showing the least bone loss (P < .001) in comparison with the other designs. Supracrestally placed implants underwent less bone loss than crestally placed implants (P = .025). CONCLUSION: Peri-implant bone loss is influenced by the level of implant placement in relation to the bone crest (crestal or supracrestal) and by the morphology of the prosthetic platform.

Nitric Oxide Controls Constitutive Freezing Tolerance in Arabidopsis by Attenuating the Levels of Osmoprotectants, Stress-Related Hormones and Anthocyanins.

Plant tolerance to freezing temperatures is governed by endogenous constitutive components and environmental inducing factors. Nitric oxide (NO) is one of the endogenous components that participate in freezing tolerance regulation. A combined metabolomic and transcriptomic characterization of NO-deficient nia1,2noa1-2 mutant plants suggests that NO acts attenuating the production and accumulation of osmoprotective and regulatory metabolites, such as sugars and polyamines, stress-related hormones, such as ABA and jasmonates, and antioxidants, such as anthocyanins and flavonoids. Accordingly, NO-deficient plants are constitutively more freezing tolerant than wild type plants.

The gene doublesex of the fruit fly Anastrepha obliqua (Diptera, Tephritidae).

The gene doublesex of Anastrepha obliqua is composed of four instead of the usual six exons. It is transcribed in both sexes and its primary transcript undergoes sex-specific splicing, producing female Dsx(F) and male Dsx(M) proteins, which have in common the amino-terminal region but which differ at the carboxyl-terminal region.

Isolation and characterization of the Bactrocera oleae genes orthologous to the sex determining Sex-lethal and doublesex genes of Drosophila melanogaster.

Here we report the isolation and characterization of the olive fruit fly Bactrocera oleae genes orthologous to the Drosophila melanogaster sex-determining genes Sex-lethal (Sxl) and doublesex (dsx). Fragments of the Sxl and dsx orthologous were isolated with RT-PCR. Genomic and cDNA clones were then obtained by screening a genomic library and separate male and female cDNA adult libraries using the RT-PCR products as probes in both cases. B. oleae Sxl gene (BoSxl) expresses the same pattern of transcripts which encode for a single common polypeptide in both male and female flies. The gene shares a high degree of similarity in sequence and expression to its Ceratitis capitata orthologous and does not appear to play a key regulatory role in the sex-determining cascade. B. oleae dsx gene (Bodsx) expands in a chromosomal region of more than 50 kb, with 6 exons-5 introns, producing different sex-specific mRNAs, according to the Drosophila model. The cDNA sequences are almost identical to the gene orthologous of Bactrocera tryoni. Four repeat elements identical to the D. melanogaster TRA/TRA-2 binding sites have been found in the untranslated region of the female-specific exon 4, predicting a common regulatory splicing mechanism in all studied species of Diptera.

The gene Sex-lethal of the Sciaridae family (order Diptera, suborder Nematocera) and its phylogeny in dipteran insects.

This article reports the cloning and characterization of the gene homologous to Sex-lethal (Sxl) of Drosophila melanogaster from Sciara coprophila, Rhynchosciara americana, and Trichosia pubescens. This gene plays the key role in controlling sex determination and dosage compensation in D. melanogaster. The Sxl gene of the three species studied produces a single transcript encoding a single protein in both males and females. Comparison of the Sxl proteins of these Nematocera insects with those of the Brachycera showed their two RNA-binding domains (RBD) to be highly conserved, whereas significant variation was observed in both the N- and C-terminal domains. The great majority of nucleotide changes in the RBDs were synonymous, indicating that purifying selection is acting on them. In both sexes of the three Nematocera insects, the Sxl protein colocalized with transcription-active regions dependent on RNA polymerase II but not on RNA polymerase I. Together, these results indicate that Sxl does not appear to play a discriminatory role in the control of sex determination and dosage compensation in nematocerans. Thus, in the phylogenetic lineage that gave rise to the drosophilids, evolution coopted for the Sxl gene, modified it, and converted it into the key gene controlling sex determination and dosage compensation. At the same time, however, certain properties of the recruited ancestral Sxl gene were beneficial, and these are maintained in the evolved Sxl gene, allowing it to exert its sex-determining and dose compensation functions in Drosophila.

Post-fatigue fracture resistance of metal core crowns: press-on metal ceramic versus a conventional veneering system.

BACKGROUND: The aim of this in vitro study was to compare the mechanical failure behavior and to analyze fracture characteristics of metal ceramic crowns with two veneering systems - press-on metal (PoM) ceramic versus a conventional veneering system - subjected to static compressive loading. MATERIAL AND METHODS: Forty-six crowns were constructed and divided into two groups according to porcelain veneer manufacture. Group A: 23 metal copings with porcelain IPS-InLine veneering (conventional metal ceramic). Group B: 23 metal copings with IPS-InLine PoM veneering porcelain. After 120,000 fatigue cycles, the crowns were axially loaded to the moment of fracture with a universal testing machine. The fractured specimens were examined under optical stereomicroscopy and scanning electron microscope. RESULTS: Fracture resistance values showed statistically significant differences (Student's t-test) regarding the type of ceramic veneering technique (p=0.001): Group A (conventional metal ceramics) obtained a mean fracture resistance of 1933.17 N, and Group B 1325.74N (Press-on metal ceramics). The most common type of fracture was adhesive failure (with metal exposure) (p=0.000). Veneer porcelain fractured on the occlusal surface following a radial pattern. CONCLUSIONS: Metal ceramic crowns made of IPS InLine or IPS InLine PoM ceramics with different laboratory techniques all achieved above-average values for clinical survival in the oral environment according to ISO 6872. Crowns made with IPS InLine by conventional technique resisted fracture an average of 45% more than IPS InLine PoM fabricated with the press-on technique. Key words:Mechanical failure, conventional feldspathic, pressable ceramic, chewing simulator, thermocycling, compressive testing, fracture types, scanning electron microscope.

Assessment of the capacity of a pyrophosphate-based mouth rinse to inhibit the formation of supragingival dental calculus. A randomized double-blind placebo-controlled clinical trial

Background: This study aimed to analyze the efficacy of an anti-calculus mouth rinse and its possible adverse effects on the mucosa and teeth. Material and Methods: This randomized double-blind placebo-controlled clinical trial included 40 patients with treated and managed periodontal disease, all with a history of rapid calculus formation. Patients used a pyrophos-phate-based test mouth rinse (B) or a placebo (A). A range of parameters were measured for: saliva (saliva flow, pH and chemical composition); calculus (Volpe-Manhold [V-M] index, weight, and volume); adverse effects on mucosa and teeth; and the patients’ subjective perceptive of mouth rinse efficacy. Results: the test mouth rinse B produced reductions in urea, uric acid, and phosphorous, calcium, saliva flow, and increases in pH. V-M index and calculus weight decreased after using the test mouth rinse. Calculus volume decreased with both mouth rinses. No changes to the mucosa or teeth were observed. Patients perceived that the test mouth rinse was more effective

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Survival rates of a lithium disilicate-based core ceramic for three-unit esthetic fixed partial dentures: a 10-year prospective study.

PURPOSE: The aim of this prospective study was to evaluate the clinical efficacy and long-term survival rate of three-unit fixed partial dentures (FPDs) made from lithium disilicate-based core ceramic. MATERIALS AND METHODS: Twenty-one three-unit FPDs were placed in 19 patients to replace single lost teeth in the esthetic area, following a study protocol that took clinical, esthetic, and radiologic aspects into consideration. Each case was reviewed at 1 week following placement, at 6 months, and then annually for 10 years. Statistical analysis was performed using Kaplan-Meier survival analysis. RESULTS: Out of the 19 patients, 14.3% presented reversible postoperative sensitivity. Recession was observed in 24% of dental posts, and 7.1% presented marginal discoloration. Treatment did not increase either Bleeding or Plaque Index scores at prepared teeth; secondary caries did not appear either. The restorations' survival rate at the 10-year follow-up was 71.4%; six FPDs had fractured and one debonded. CONCLUSIONS: Fracture failure rate was 28.6% after 10 years; a high percentage corresponded to connector fractures and occurred during the first 5 years. Lithium disilicate glass-ceramic FPDs present a higher risk of fracture than standard therapies (metal-ceramic) or other more recently developed ceramic materials. The prognosis for survival improves for Class I occlusion and nonparafunctional patients.

Common evolutionary origin and birth-and-death process in the replication-independent histone H1 isoforms from vertebrate and invertebrate genomes.

The H1 histone multigene family shows the greatest diversity of isoforms among the five histone gene families, including replication-dependent (RD) and replication-independent (RI) genes, according to their expression patterns along the cell cycle and their genomic organization. Although the molecular characterization of the RI isoforms has been well documented in vertebrates, similar information is lacking in invertebrates. In this work we provide evidence for a polyadenylation signature in the Mytilus "orphon" H1 genes similar to the polyadenylation characteristic of RI H1 genes. These mussel genes, together with the sea urchin H1delta genes, are part of a lineage of invertebrate "orphon" H1 genes that share several control elements with vertebrate RI H1 genes. These control elements include the UCE element, H1-box and H4-box. We provide evidence for a functional evolution of vertebrate and invertebrate RI H1 genes, which exhibit a clustering pattern by type instead of by species, with a marked difference from the somatic variants. In addition, these genes display an extensive silent divergence at the nucleotide level which is always significantly larger than the nonsilent. It thus appears that RI and RD H1 isoforms display similar long-term evolutionary patterns, best described by the birth-and-death model of evolution. Notably, this observation is in contrast with the theoretical belief that clustered RD H1 genes evolve in a concerted manner. The split of the RI group from the main RD group must therefore have occurred before the divergence between vertebrates and invertebrates about 815 million years ago. This was the result of the transposition of H1 genes to solitary locations in the genome.

Differential acetylation of histones H3 and H4 in paternal and maternal germline chromosomes during development of sciarid flies.

A classic example of chromosome elimination and genomic imprinting is found in sciarid flies (Diptera. Sciaridae), where whole chromosomes of exclusively paternal origin are discarded from the genome at different developmental stages. Two types of chromosome elimination event occur in the germline. In embryos of both sexes, the extrusion of a single paternal X chromosome occurs in early germ nuclei and in male meiotic cells the whole paternal complement is discarded. In sciarids, early germ nuclei remain undivided for a long time and exhibit a high degree of chromatin compaction, so that chromosomes are cytologically individualized. We investigated chromatin differences between parental chromosomes in Sciara ocellaris and S. coprophila by analyzing histone acetylation modifications in early germ nuclei. We examined germ nuclei from early embryonic stages to premeiotic larval stages, male meiotic cell and early somatic nuclei following fertilization. In early germ cells, only half of the regular chromosome complement is highly acetylated for histones H4 and H3. The chromosomes that are highly acetylated are paternally derived. An exception is the paternal X chromosome that is eliminated from germ nuclei. At later stages preceding the initiation of mitotic gonial divisions, all chromosomes of the germline complement show similar high levels of histone H4/H3 acetylation. In male meiosis, maternal chromosomes are highly acetylated for histones H4 and H3, whereas the entire paternal chromosome set undergoing elimination appears under-acetylated. The results suggest that histone acetylation contributes towards specifying the imprinted behavior of germline chromosomes in sciarids.

Selección de la ceramica a utilizar en tratamientos mediante frentes laminados de porcelana / Choice of ceramic for use in treatments with porcelain laminate veneers

El tratamiento mediante Frentes Laminados de Porcelana (FLP) se utiliza desde hace más de dos décadas para el tratamiento de problemas estéticos y/o funcionales, particularmente en el grupo anterior de las arcadas dentarias (1,2,3). La actual oferta en el mercado de cerámicas dentales aptas para este tipo de tratamiento, pero muy distintas en cuanto a composición, características ópticas y sistema de elaboración, hace complicada la selección del material más adecuado a cada paciente en particular. Proponemos un sistema sencillo de elección de la cerámica teniendo en cuenta las dos variables que más influirán en el resultado estético final: de un lado las características propias del diente (sustrato en el que nos apoyamos), y de otro las características propias del material cerámico en cuanto a resistencia y propiedades ópticas

Porcelain laminate veneers (PLVs) have been used for over two decades to treat esthetic and/or functional problems, particularly in the anterior sector (1-3). A range of dental ceramic materials are presently available on the market for these treatments, though with very different characteristics in terms of the composition, optic properties and manufacturing processes involved. As a result, selection of the material best suited for the management of each individual patient may prove complicated. The present study proposes a simple system for selecting the most appropriate ceramic material, based on the two variables that most influence the esthetic outcome: the intrinsic characteristics of the substrate tooth, and the characteristics of the ceramic material in terms of resistance and optic properties

Full maxillary rehabilitation with an all-ceramic system

With the appearance of all-ceramic systems, providing a choice of framework porcelains and allowing the samematerial to be used for the veneer, it is now possible to select the ideal structure in terms of both function andesthetics. Silicate ceramics allow porcelain laminate veneers and crowns to be used in the anterior region, providingexcellent esthetics; while for the posterior area, where function takes precedence, oxide ceramics, specificallyzirconium oxide, are preferred. The IPS e.max ceramic system, heir apparent to the IPS Empress 2 system,combines the advantages of zirconium oxide ceramics (IPS e.max Zircad) with the excellent esthetic qualities ofsilicate ceramics (IPS e.max Press).This paper presents a clinical case requiring complete maxillary rehabilitation for esthetic purposes. An overviewof some of the porcelains used in this system, analyzed from both the clinical and laboratory perspective is provided.The esthetic advantages of a single ceramic veneer, the need to select appropriate ceramics for anterior andposterior regions, and cementation and surface treatments are discussed (AU)

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