OCT findings in macular hole formation in eyes with complete vitreofoveal separation

The current study describes the morphologic macular features in two eyes that developed full-thickness macular holes in the setting of documented vitreofoveal separation. Using third-generation optical coherence tomography, complete vitreofoveal separation associated with the disruption of the inner foveal retina was documented in both cases. Five months after presentation, decreased vision and epiretinal membrane formation associated with development of a full-thickness macular hole were observed in the first patient. In the second patient, a full-thickness macular hole was demonstrated by optical coherence tomography 6 weeks after presentation. These findings suggest that full-thickness macular holes may develop in eyes with vitreofoveal separation. Evidence of the disturbance of the inner foveal architecture on optical coherence tomography indicates the potential role of factors other than anteroposterior or oblique vitreoretinal tractional forces in the genesis of some full-thickness macular holes.

Subcritical crack growth in porcelains, glass-ceramics, and glass-infiltrated alumina composite for dental restorations

The objective was to compare fracture toughness (K(Ic)), stress corrosion susceptibility coefficient (n), and stress intensity factor threshold for crack propagation (K(I0)) of two porcelains [VM7/Vita (V) and d.Sign/Ivoclar (D)], two glass-ceramics [Empress/Ivolcar (E1) and Empress2/Ivlocar (E2)] and a glass-infiltrated alumina composite [In-Ceram Alumina/Vita (IC)]. Disks were constructed according to each manufacturer`s processing method, and polished before induction of cracks by a Vickers indenter. Crack lengths were measured under optical microscopy at times between 0.1 and 100 h. Specimens were stored in artificial saliva at 37A degrees C during the whole experiment. K(Ic) and n were determined using indentation fracture method. K(I0) was determined by plotting log crack velocity versus log K(I). Microstructure characterization was carried out under SEM, EDS, X-ray diffraction and X-ray fluorescence. IC and E2 presented higher K(Ic) and K(I0) compared to E1, V, and D. IC presented the highest n value, followed by E2, D, E1, and V in a decreasing order. V and D presented similar K(Ic), but porcelain V showed higher K(I0) and lower n compared to D. Microstructure features (volume fraction, size, aspect ratio of crystalline phases and chemical composition of glassy matrix) determined K(Ic). The increase of K(Ic) value favored the increases of n and K(I0).

Fluoride effects on ectopic bone formation in young and old rats

This study evaluated the effect of fluoride oil bone fluoride levels and on ectopic bone formation in young and old rats. Eighty male Wistar rats were assigned to four groups (n = 20/g), which differed according to the fluoride concentration in their drinking water (0, 5, 15 and 50 mg/l). When half of the rats were 90 days old, demineralized bone matrix (DBM) was implanted. The other rats received DBM implants when they were 365 day`s old. The animals were killed 28 days after. Fluoride in the femur surface, whole femur and plasma was analyzed with an electrode, The implants were analyzed histomorphometrically. Data were tested for statistically, significant differences by ANOVA, Tukey`s test, t-test and linear regression (p < 0.05). Increases in plasma, femur surface and whole femur fluoride concentrations were observed cis water fluoride levels increased. There was also a trend for increase in plasina and femur fluoride concentrations cis age increased. Significant positive correlations were found between plasma and femur surface, plasina and femur and femur surface and femur fluoride, concentrations. The morphometric analyses indicated all increase in bone formation for younger rats that received 5 mg/l of fluoride in the drinking water. However, this was not statistically, significant. The younger rats that received 50 mg/l of fluoride showed impairment in bone formation. Bone formation was not significantly affected among the older rats. The results suggest that lower doses of fluoride in the drinking water, which slightly increase plasma fluoride levels, may have an anabolic effect oil bone formation in younger rats. Copyright 2008 Prous Science, S.A.U. or its licensors. All rights reserved.

Effect of recombinant human bone morphogenetic protein-2 on bone formation in the acute distraction osteogenesis of rat mandibles

Background Distraction osteogenesis (DO) is a method of producing new bone directly from the osteotomy site by gradual traction of the divided bone fragments. Aim The purpose of the present study was to evaluate histomorphometrically whether acute DO would constitute a viable alternative to the conventional continuous distraction treatment and also to verify the capacity of a recombinant human BMP (rhBMP-2) associated with monoolein gel to stimulate bone formation in the acute distraction process. Materials and methods Forty-eight Wistar rats were assigned to three groups: Group 1, treated at a conventional continuous distraction rate (0.5 mm/day), Group 2, treated with acute distraction of 2.5 mm at the time of the surgical procedure, and Group 3, subjected to acute distraction associated with rhBMP-2. The animals from each experimental group were killed at the end of the second or fourth post-operative weeks and the volume fraction of newly formed bone trabeculae was estimated in histological images by a differential point-counting method. Results The results showed that after 2 and 4 weeks, bone volumes in the rhBMP-2 group were significantly higher than in the other groups (P < 0.05), but no significant difference was observed in the volume fraction of newly formed bone between the continuous and acute DO groups. Conclusion In conclusion, the study indicates that rhBMP-2 can enhance the bone formation at acute DO, which may potentially reduce the treatment period and complications related to the distraction procedure. To cite this article:Issa JPM, do Nascimento C, Lamano T, Iyomasa MM, Sebald W, de Albuquerque Jr RF. Effect of recombinant human bone morphogenetic protein-2 on bone formation in the acute distraction osteogenesis of rat mandibles.Clin. Oral Impl. Res. 20, 2009; 1286-1292.doi: 10.1111/j.1600-0501.2009.01799.x.

Solid state F-19 NMR determination of new structure formation in FEP following radiolysis at 300 and 363 K

The radiation chemistry of FEP copolymer with a mole fraction TFE of 0.90 has been studied using Co-60 gamma -radiation at temperatures of 300 and 363 K. New structure formation in the copolymers was analysed by solid state F-19 NMR. New chain scission products were the principal new structures found. The G-value for the formation of new -CF3 groups was 2.2 and 2.1 for the radiolysis of FEP at 300 and 363 K, respectively, and the G-value for the loss of original -CF3 groups was G(-CF3) = 1.0 and 0.9 at these two temperatures, respectively. There was a nett loss of -CF- groups on irradiation, with G(-CF) of 1.3 and 0.9 at 300 and 363 K, respectively. (C) 2001 Elsevier Science Ltd. All rights reserved.

Kinase-dependent and kinase-independent functions of EphA4 receptors in major axon tract formation in vivo

The EphA4 receptor tyrosine kinase regulates the formation of the corticospinal tract (CST), a pathway controlling voluntary movements, and of the anterior commissure (AC), connecting the neocortical temporal robes. To study EphA4 kinase signaling in these processes, we generated mice expressing mutant EphA4 receptors either lacking kinase activity or with severely downregulated kinase activity. We demonstrate that EphA4 is required for CST formation as a receptor for which it requires an active kinase domain. In contrast, the formation of the AC is rescued by kinase-dead EphA4, suggesting that in this structure EphA4 acts as a ligand for which its kinase activity is not required. Unexpectedly, the cytoplasmic sterile-alpha motif (SAM) domain is not required for EphA4 functions. Our findings establish both kinase-dependent and kinase-independent functions of EphA4 in the formation of major axon tracts.

Shoot control of hypernodulation and aberrant root formation in the har1-1 mutant of Lotus japonicus

The har1-1 mutant of Lotus japonicus B-129-S9 Gifu is characterized by two phenotypes: greater than normal nodulation (hypernodulation) and significantly inhibited root growth in the presence of its microsymbiont Mesorhizobium loti strain NZP2235. We demonstrate that the two traits co-segregate, suggesting a single genetic alteration involving developmental pleiotropy. A cross between the mutant and genotype Funakura (with wild-type root and nodule morphology) demonstrated Mendelian recessive segregation of both phenotypes (root and nodule) in 216 F2 individuals. Using DNA-amplification fingerprinting polymorphisms in Gifu har1-1 and Funakura, the mutant locus was positioned between two markers at about 7 and 13 cM distance. Reciprocal hypocotyl grafting of shoots and roots showed that the hypernodulation and reduced root phenotypes are both predominantly controlled by the shoot.

Multiple shoot formation in lentil (Lens culinaris) seeds

A protocol based on seed culture was developed for efficient in vitro propagation of lentil (Lens culinaris Medik). Benzyladenine (BA), thidiazuron (TDZ), and kinetin all induced multiple shoot formation. In terms of the number of long shoots (>2.0 cm) produced per seed, BA and TDZ at optimum concentrations (0.2-0.4 and 0.1 mg/litre, respectively) had similar efficiency, whereas kinetin produced less shoots. Murashige and Skoog (MS) salt composition was better than that of Gamborge (B5) for shoot induction. Increasing calcium (Ca) concentration was necessary to overcome shoot-tip necrosis. For shoot elongation, fresh medium of the same composition of shoot induction medium could be used for stumps from medium with low BA (

Instabilities and drop formation in cylindrical liquid jets in reduced gravity

The effects of convective and absolute instabilities on the formation of drops formed from cylindrical liquid jets of glycerol/water issuing into still air were investigated. Medium-duration reduced gravity tests were conducted aboard NASA's KC-135 and compared to similar tests performed under normal gravity conditions to aid in understanding the drop formation process. In reduced gravity, the Rayleigh-Chandrasekhar Equation was found to accurately predict the transition between a region of absolute and convective instability as defined by a critical Weber number. Observations of the physics of the jet, its breakup, and subsequent drop dynamics under both gravity conditions and the effects of the two instabilities on these processes are presented. All the normal gravity liquid jets investigated, in regions of convective or absolute instability, were subject to significant stretching effects, which affected the subsequent drop and associated geometry and dynamics. These effects were not displayed in reduced gravity and, therefore, the liquid jets would form drops which took longer to form (reduction in drop frequency), larger in size, and more spherical (surface tension effects). Most observed changes, in regions of either absolute or convective instabilities, were due to a reduction in the buoyancy force and an increased importance of the surface tension force acting on the liquid contained in the jet or formed drop. Reduced gravity environments allow better investigations to be performed into the physics of liquid jets, subsequently formed drops, and the effects of instabilities on these systems. In reduced gravity, drops form up to three times more slowly and as a consequence are up to three times larger in volume in the theoretical absolute instability region than in the theoretical convective instability region. This difference was not seen in the corresponding normal gravity tests due to the masking effects of gravity. A drop is shown to be able to form and detach in a region of absolute instability, and spanning the critical Weber number (from a region of convective to absolute instability) resulted in a marked change in dynamics and geometry of the liquid jet and detaching drops. (C) 2002 American Institute of Physics.

Immunohistochemical localization of fibromodulin in the periodontium during cementogenesis and root formation in the rat molar

Background: Cementum is essential for periodontal regeneration, as it provides anchorage between the root surface and the periodontal ligament. A variety of macromolecules present in the extracellular matrix of the periodontium, including proteoglycans, are likely to play a regulatory role in cementogenesis. Recently, the small leucine-rich proteoglycan, fibromodulin, has been isolated from bovine periodontal ligament and localized in bovine cementum, as well as in human periodontal ligament. Objective: The aim of this study was to examine the distribution of fibromodulin during cementogenesis and root formation. Methods: A standard indirect immunoperoxidase technique was employed, using an antifibromodulin polyclonal antibody on sections of molar teeth from rats aged 3, 5 and 8 weeks. Results: Immunoreactivity to fibromodulin was evident in the periodontal ligament in all sections. An intense positive stain was observed in the extracellular matrix where the periodontal ligament fibers insert into the alveolar bone and where the Sharpey's fibers insert into the cementum. There was no staining evident in the mineralized cellular and acellular cementum. The intensity of immunoreactivity to the antifibromodulin antibody increased proportionally with increasing tissue maturation. Conclusion: The results from this study suggest that fibromodulin is a significant component of the extracellular matrix in the periodontal ligament during development, and may play a regulatory role in the mineralization process or maintaining homeostasis at the hard-soft tissue interface during cementogenesis.

Crack detection in hollow section structures through coupled response measurements

Detection of a circumferential crack in a hollow section beam is investigated using coupled response measurements. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. This matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. The suitability of the mode coupling methodology is first demonstrated analytically. Laboratory test results are then presented for circular hollow section beams with artificially generated cracks of varying severity. It is shown that this method has the potential as a damage detection tool for mechanical structures. (C) 2002 Elsevier Science Ltd. All rights reserved.