Undifferentiated cells in the developing Drosophila eye influence facet assembly and require the Fat facets ubiquitin-specific protease

The Drosophila compound eye develops by a complex series of cell interactions where multiple positive and inhibitory cues guide cells in each facet into their positions and fates. The results of many genetic and molecular experiments have led to the view that facet assembly is directed by cells within developing ommatidial preclusters. Here fat facets mutants and the cloned fat facets gene were used to show that, in order to limit the number of photoreceptors in a facet to eight, undifferentiated cells surrounding assembling facets send an inhibitory signal to extraneous cells within the facet preclusters. Generation of the inhibitory signal requires the ubiquitin-specific protease encoded by the fat facets gene and is thus regulated by ubiquitin-dependent proteolysis.     

Retentive properties of a threaded split post with attachment sleeves cemented with various luting agents

This study determined the retention, in pounds, of Nos. 1 through 3 stainless steel attachment sleeves for the threaded split post system cemented with various cements. Post heads and matching sleeves were also sandblasted and compared with attachments not sandblasted. Four luting agents were selected, zinc oxyphosphate cement (ZOP), and three brands of composite resin cement (CRC). The experiment was divided into two parts; in part 1, samples were not treated, and in part 2, samples were sandblasted. Retentive values were recorded with a universal testing machine. A 2 x 3 x 4 factorial three-way analysis of variance was used to compute the effects sandblasting, sleeve and post type, and the luting agent. No statistical differences were recorded for sleeves not sandblasted, Nos. 1 and 2, regardless of the luting agent. The nonsandblasted No. 3 sleeve cemented with Panavia CRC had significantly greater retention than All-Bond CRC or ZOP. There were no statistical differences in retention of sandblasted sleeves for the No. 1 sleeve despite the type of luting agent. For sandblasted sleeves Nos. 2 and 3, ZOP and Panavia CRC recorded significantly greater retention than All-Bond CRC. However, there was no difference between sandblasting and not sandblasting for the No. 1 sleeve. Mean loads for Nos. 2 and 3 sleeves were substantially greater for sandblasted compared with attachments not sandblasted.     

The optx2 homeobox gene is expressed in early precursors of the eye and activates retina-specific genes

Vertebrate eye development begins at the gastrula stage, when a region known as the eye field acquires the capacity to generate retina and lens. Optx2, a homeobox gene of the sine oculis-Six family, is selectively expressed in this early eye field and later in the lens placode and optic vesicle. The distal and ventral portion of the optic vesicle are fated to become the retina and optic nerve, whereas the dorsal portion eventually loses its neural characteristics and activates the synthesis of melanin, forming the retinal pigment epithelium. Optx2 expression is turned off in the future pigment epithelium but remains expressed in the proliferating neuroblasts and differentiating cells of the neural retina. When an Optx2-expressing plasmid is transfected into embryonic or mature chicken pigment epithelial cells, these cells adopt a neuronal morphology and express markers characteristic of developing neural retina and photoreceptors. One explanation of these results is that Optx2 functions as a determinant of retinal precursors and that it has induced the transdifferentiation of pigment epithelium into retinal neurons and photoreceptors. We also have isolated optix, a Drosophila gene that is the closest insect homologue of Optx2 and Six3. Optix is expressed during early development of the fly head and eye primordia.     

Mechanical Behavior of CFRP Rod Anchors under Tensile Loading

This paper presents the results of an experimental and numerical study to examine the mechanical behavior of carbon fiber reinforced polymer rods gripped by a wedge anchor, comprised of an aluminum sleeve, four stainless steel wedges, and a stainless steel barrel. The carbon fiber reinforced polymer rod-anchor system was tested under monotonic and cyclic loading conditions. In the static load tests, the effect of presetting loads, usage history, and sleeve material were investigated. Presetting load levels of 50, 65, 80, and 100 kN were used, and tests were conducted with new and reused anchors. Aluminum and copper sleeves were considered. As the presetting load increased, the displacement (or slip) of the rod and sleeve decreased. No significant effect of reusing the anchor was found other than replacing the sleeve. Anchors with copper sleeves performed poorly at low presetting loads, in comparison to aluminum sleeves. Cyclic load tests were conducted on anchors using aluminum sleeves with a presetting load of 80 kN. The effects of cycling on the rod and sleeve displacement were minor for different mean stresses and stress ratios. A finite-element model, consisting of three contact surfaces, was applied to simulate the anchor components; the displacement of the rod compared well with experimental results.     

Infiltrative keratitis with contact lens wear--a review

BACKGROUND: "Infiltrates" of white blood cells aggregating in the superficial cornea are common with corneal inflammation. The etiologies of such inflammation vary widely and include an association with contact lens wear. METHODS: This paper reviews the literature regarding corneal infiltrative keratitis with contact lens wear. Basic mechanisms in the development of corneal infiltrates as well as etiologies are presented. Associations and causes, clinical presentation, differential diagnosis, course, and treatment for corneal infiltrates in contact lens wearers are reviewed. CONCLUSIONS: Corneal infiltrates associated with contact lens wear may stem from a variety of causes including factors related to the lens material, design, condition; the lens wearing schedule; environmental factors such as external environment; and lens care patterns, procedures, and products. Individuals who wear contact lenses are also subject to the many non-contact lens-related stimuli to corneal infiltration. Accurate diagnosis and appropriate management of corneal infiltrates with contact lens wear is important, especially due to the possibility of infectious etiology.     

Correction factors for water-proofing sleeves in kilovoltage x-ray beams

This paper investigates the effect of the waterproofing sleeve on the calibration of kilovoltage photon beams (50-300 kV). The sleeve effect correction factor, ps has been calculated using the Monte Carlo method as the ratios of the air kerma in an air cavity of a cylindrical chamber without the waterproofing sleeve to that with a sleeve. Three sleeve materials have been studied, PMMA, nylon and polystyrene. The calculations were carried out using the EGS4 (Electron Gamma Shower version 4) code system with the application of a correlated-sampling variance-reduction technique. The results show that the sleeve correction factor for 1-mm thick nylon and polystyrene sleeves, ps varies from 0.992 to 1.000 and from 0.981 to 1.000, respectively, for the same beam quality range. The ps factor varies with sleeve thickness, beam quality and phantom depth. No significant dependence of the ps factor on field size and source-surface distance has been found. Measurements for PMMA, nylon and polystyrene sleeves of various thicknesses have also been carried out and show excellent agreement with Monte Carlo calculations.     

Effect of contact lens wear on the conjunctival mucous system

Biopsy specimens from the upper tarsal conjunctiva of 20 contact lens wearers with a clinically evident increase in mucus and ten non-lens wearing subjects were examined by light microscopy and scanning and transmission electron microscopy to determine the effect of contact lens wear on the mucous cell system(s). Three types of crypts associated with mucous secretion were found in all specimens: those with intracellular openings (type I, 0.1 to 0.2 mum) associated with non-goblet mucous secretory cells; those with small intercellular openings (type II, 1 to 2 mum) usually associated with goblet cells, and those with intraepithelial and intrastromal crypts with large intercellular openings (type III, 10 to 60 mum) lined with goblet and non-goblet mucous secretory cells. Contact lens wearers had increased numbers of non-goblet cells with mucous secretory vesicles lining the surface of the conjunctiva and the epithelial infoldings of type III crypts than did the normal subjects. We conclude that increased mucous secretion in contact lens wearers is associated with an increased number of cells and number of secretory vesicles involved in the non-goblet cell mucous system.     

Accommodation of angular incompatibilities between interfacial facets during precipitate growth

Precipitate growth in a duplex stainless steel and a titanium aluminide alloy has been studied using transmission electron microscopy. Particles with similar crystallography and acicular form arise in both cases, and are bounded by two principal facets. One facet, designated C, is based on a commensurate singular interface structure, and the coherency strains are accommodated by interfacial defects. The other facet, designated I, is based on a singular configuration that is incommensurate in one dimension. The orientation relationship (OR) between the particle and the matrix for the singular C structure is Kurdjumov-Sachs (K-S), whereas that for the I facet is Pitsch. The angular incompatibility between these two types of facets must be accommodated to minimize the displacement field as particles grow. The present observations suggest that this is accomplished through the generation of crystal dislocations at facet junctions and their subsequent climb along the facets. The total density of defects needed to accommodate the angular discrepancy is fixed, but the partitioning of these dislocations between C and I facets is not. The actual partitioning determines the observed OR for a particle, and is determined by the kinetics of climb, which is likely to be different in the two facets. In the stainless steel, the observations are consistent with climb occurring in both the C and I facets, but faster in the I facet, leading to a distribution of observed ORs that is skewed away from Pitsch toward K-S. In the titanium aluminide alloy, no climb into the C facets was found, so a unique OR close to K-S arises. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.     

Accommodation of angular incompatibilities between interfacial facets during precipitate growth

Precipitate growth in a duplex stainless steel and a titanium aluminide alloy has been studied using transmission electron microscopy. Particles with similar crystallography and acicular form arise in both cases, and are bounded by two principal facets. One facet, designated C, is based on a commensurate singular interface structure, and the coherency strains are accommodated by interfacial defects. The other facet, designated I, is based on a singular configuration that is incommensurate in one dimension. The orientation relationship (OR) between the particle and the matrix for the singular C structure is Kurdjumov-Sachs (K-S), whereas that for the I facet is Pitsch. The angular incompatibility between these two types of facets must be accommodated to minimize the displacement field as particles grow. The present observations suggest that this is accomplished through the generation of crystal dislocations at facet junctions and their subsequent climb along the facets. The total density of defects needed to accommodate the angular discrepancy is fixed, but the partitioning of these dislocations between C and I facets is not. The actual partitioning determines the observed OR for a particle, and is determined by the kinetics of climb, which is likely to be different in the two facets. In the stainless steel, the observations are consistent with climb occurring in both the C and I facets, but faster in the I facet, leading to a distribution of observed ORs that is skewed away from Pitsch toward K-S. In the titanium aluminide alloy, no climb into the C facets was found, so a unique OR close to K-S arises. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS Alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.     

Accommodation of angular incompatibilities between interfacial facets during precipitate growth

Precipitate growth in a duplex stainless steel and a titanium aluminide alloy has been studied using transmission electron microscopy. Particles with similar crystallography and acicular form arise in both cases, and are bounded by two principal facets. One facet, designated C, is based on a commensurate singular interface structure, and the coherency strains are accommodated by interfacial defects. The other facet, designated I, is based on a singular configuration that is incommensurate in one dimension. The orientation relationship (OR) between the particle and the matrix for the singular C structure is Kurdjumov-Sachs (K-S), whereas that for the I facet is Pitsch. The angular incompatibility between these two types of facets must be accommodated to minimize the displacement field as particles grow. The present observations suggest that this is accomplished through the generation of crystal dislocations at facet junctions and their subsequent climb along the facets. The total density of defects needed to accommodate the angular discrepancy is fixed, but the partitioning of these dislocations between C and I facets is not. The actual partitioning determines the observed OR for a particle, and is determined by the kinetics of climb, which is likely to be different in the two facets. In the stainless steel, the observations are consistent with climb occurring in both the C and I facets, but faster in the I facet, leading to a distribution of observed ORs that is skewed away from Pitsch toward K-S. In the titanium aluminide alloy, no climb into the C facets was found, so a unique OR close to K-S arises. This article is based on a presentation made in the “Hume-Rothery Symposium on Structure and Diffusional Growth Mechanisms of Irrational Interphase Boundaries,” which occurred during the TMS Winter meeting, March 15–17, 2004, in Charlotte, NC, under the auspices of the TMS alloy Phases Committee and the co-sponsorship of the TMS-ASM Phase Transformations Committee.     

Meningeal carcinomatosis. Case report and review of the literature

Cadaver knee joints were mounted so that life-like forces of weight-bearing were simulated. The patello-femoral contact areas were defined under load throughout the range of movement by the dye method. During movement from extension to 90 degrees of flexion a band of contact sweeps across the patella from inferior to superior pole, but the odd facet makes no contact. At about 135 degrees of flexion separate medial and lateral contact areas form, the medial one limited to the odd facet. From extension to 90 degrees of flexion the patella holds the quadriceps tendon away from the femur, but in further degrees of flexion an extensive "tendo-femoral" contact area forms. Between 90 degrees and 135 degrees of flexion the patella rotates and the ridge between the medial and odd facets engages the femoral condyle. The odd facet is shown to be a habitual non-contact area and the ridge to be subject to high load, observations which correlate with cartilage lesions described in Part 2 of the paper.     

高温焙砂装入装置的设计

叙述了高温焙砂装入装置的结构形式、工作原理以及驱动装置的特点,介绍了这种装入装置的设计及特点.     

Validity of job facet importance: A multinational multicriteria study.

Compared the importance of various job aspects, or facets, in predicting different criteria. Questionnaire measures were obtained from 2,376 salesmen and 6,331 repairmen of an international firm in 5 countries. Employees' ratings of facet importance were compared to facet importance defined empirically (i.e., by the correlation of facet satisfaction with various criteria). The importance of job facets, while similar among the 5 countries, varied with the criterion used. Higher order job facets were most important for predicting overall satisfaction and intent to stay with the company but were least important for predicting work tension. In multiple correlations with facet satisfactions, adding employees' nationality improved predictions only of performance ratings; adding employees' occupation improved predictions only of intent to stay. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new tool to measure pressure under burn garments

This article introduces a new tool to measure the pressure that is under pressure garments. The Iscan (Tekscan, Inc.) system uses a patented ultra-thin (0.007 inch) sensor with multiple sensing locations that sample continuously at 100 times per second. It is noninvasive, convenient, and quick. The study had two parts. First, we established the validity and reliability of the device. Next, garment/scar interface pressures were measured on new garments with use of the Iscan system. Four garment types were studied, with 10 measurements made in each group: Isotoner gloves (Smith & Nephew Roylan, Inc.); custom-fit pressure gloves; Tubigrip forearm sleeves (Seton Health Care Group); and custom-fit pressure forearm sleeves. Mean garment/scar interface pressures were 18 +/- 2 mm Hg for the Isotoner glove, 34 +/- 5 mm Hg for the custom-fit pressure glove, 20 +/- 7 mm Hg for the Tubigrip sleeve, and 35 +/- 6 mm Hg for the custom-fit sleeve. We concluded that the Iscan system can be used to measure pressure under pressure garments accurately and reliably, and that custom-fit hand and forearm garments provide more pressure than Isotoner gloves or Tubigrip sleeves.     

Structure, development and function of cytoskeletal elements in non-neuronal cells of the human eye

The cytoskeleton, of which the main components in the human eye are actin microfilaments, intermediate filaments and microtubules with their associated proteins, is essential for the normal growth, maturation, differentiation, integrity and function of its cells. These components interact with intra- and extracellular environment and each other, and their profile frequently changes during development, according to physiologic demands, and in various diseases. The ocular cytoskeleton is unique in many ways. A special pair of cytokeratins, CK 3 and 12, has apparently evolved only for the purposes of the corneal epithelium. However, other cytokeratins such as CK 4, 5, 14, and 19 are also important for the normal ocular surface epithelia, and other types may be acquired in keratinizing diseases. The intraocular tissues, which have a relatively simple cytoskeleton consisting mainly of vimentin and simple epithelial CK 8 and 18, differ in many details from extraocular ones. The iris and lens epithelium characteristically lack cytokeratins in adults, and the intraocular muscles all have a cytoskeletal profile of their own. The dilator of the iris contains vimentin, desmin and cytokeratins, being an example of triple intermediate filament expression, but the ciliary muscle lacks cytokeratin and the sphincter of the iris is devoid even of vimentin. Conversion from extraocular-type cytoskeletal profile occurs during fetal life. It seems that posttranslational modification of cytokeratins in the eye may also differ from that of extraocular tissues. So far, it has not been possible to reconcile the cytoskeletal profile of intraocular tissues with their specific functional demands, but many theories have been put forward. Systematic search for cytoskeletal elements has also revealed novel cell populations in the human eye. These include transitional cells of the cornea that may represent stem cells on migration, myofibroblasts of the scleral spur and juxtacanalicular tissue that may modulate aqueous outflow, and subepithelial matrix cells of the ciliary body and myofibroblasts of the choroid that may both participate in accommodation. In contrast to the structure and development of the ocular cytoskeleton, changes that take place in ocular disease have not been analysed systematically. Nevertheless, potentially meaningful changes have already been observed in corneal dystrophies (Meesmann's dystrophy, posterior polymorphous dystrophy and iridocorneal endothelial syndrome), degenerations (pterygium) and inflammatory diseases (Pseudomonas keratitis), in opacification of the lens (anterior subcapsular and secondary cataract), in diseases characterized by proliferation of the retinal pigment epithelium (macular degeneration and proliferative vitreoretinopathy), and in intraocular tumours (uveal melanoma). In particular, upregulation of alpha-smooth muscle actin seems to be a relatively general response typical of spreading and migrating corneal stromal and lens epithelial cells, trabecular cells and retinal pigment epithelial cells.     

Observations of Facet Formation in Near-<Emphasis Type="Italic">α</Emphasis> Titanium and Comments on the Role of Hydrogen

Faceted features are frequently observed on the fracture surfaces of titanium alloys that have failed by static loading, continuous cycling, dwell fatigue loading, and stress corrosion cracking (SCC). Although the facets formed under different loading conditions seem qualitatively similar, there are significant differences in the spatial and crystallographic orientations of the facets as well as subtle differences in facet surface topography. The current study compares and contrasts facets for various loading conditions (cyclic, creep, SCC, and dwell) in the Ti-8Al-1Mo-1V alloy with the primary motivation being to understand the mechanisms of crack initiation and faceted growth during dwell fatigue. The spatial and crystallographic orientations of the facets were determined using quantitative tilt fractography and electron backscatter diffraction, whereas facet topography was examined using ultra-high-resolution scanning electron microscopy. Collectively, the experimental observations suggest that hydrogen may play an important role in facet formation and accelerating small crack growth rates during dwell fatigue loading.     

Effect of hepatic venous outflow obstruction on pores and fenestration in sinusoidal endothelium

The ultrastructure of pores and fenestrations in hepatic sinusoidal endothelial cells was examined following partial surgical occlusion of the suprahepatic portion of the inferior vena cava. Within 12 h after partial obstruction of hepatic venous outflow, endothelial pores (less than 0-1 mum in diameter) and sieve plates in the distal halves of sinusoids were greatly reduced in number or were totally absent, and they were replaced by large fenestration (less than 1-0 mum in diameter). These results suggest that pores forming sieve plates may fuse to form large fenestrations. The findings also indicate that sinusoidal hypertension and hypoxia associated with obstruction of hepatic venous outflow alter the distribution of pores and fenestrations in sinusoidal endothelium     

Phage typing combined with pulsed-field gel electrophoresis and random amplified polymorphic DNA increases discrimination in the epidemiological analysis of Salmonella enteritidis strains

In adult rabbits, mid-diaphyseal segments of the radius or ulna were excised to produce defects greater than the critical size for spontaneous bone repair. The defects were enveloped in sleeves composed of nonbiodegradable expanded polyfluoroethylene (ePTFE), pore size 30, 60, 90 microns, and compared with sleeves of three biodegradable materials. Bone morphogenetic protein and associated noncollagenous bone matrix protein (BMP/NCP) or recombinant human morphogenetic protein (rhBMP-2) were implanted inside the sleeves. Albumin was implanted for a control system. Without intracompartmental BMP, only about 10%-15% of the defect was repaired by bone growth extending from the bone ends into the sleeves composed of ePTFE, pore size 30 microns. With sleeves with pore size 60 or 90 microns and intracompartmental BMP/NCP, 54%-96% regeneration occurred within 8 weeks after the operation. Sleeves of biodegradable nonimmunogenic materials such as polyorthoester (POE) and polylactic-polyglycollic acids (PLA/PGA) permitted 86%-98% restoration of bone continuity, but only when BMP was present in the lumen. With puncture holes (0.5 mm in diameter), implants of BMP/NCP in the 30-micron PTFE sleeve produced transmembrane external callus formation and bone regeneration to 147%. Sleeves composed of aorta first calcified, then induced complete intracompartmental bone regeneration. Atelocollagen sleeves incited a low-grade inflammatory cell reaction and did not promote complete regeneration. Under conditions presently undisclosed segments of the ulna bridged with ePTFE, were incompletely paired, even with intracompartmental BMP/NCP. Puncture holes of 0.5 mm admitted ingrowth of capillaries and introduced local conditions favorable for the response to BMP/NCP. BMP/NCP may promote proliferation of nutrient vessels and differentiation of bone marrow stroma cells between the open bone ends. For further investigation, the hypothesis to be examined is that the optimum response to BMP/NCP and rhBMP-2 would emerge in compartments containing first a high concentration gradient and second proliferating perivascular cells.     

Ocular characteristics associated with rigid gas-permeable lens adherence

PURPOSE: Rigid gas-permeable (RGP) lens adherence after overnight lens wear is clearly a patient-dependent phenomenon. However, no previous study has attempted to determine whether specific ocular characteristics are associated with an increased frequency of lens adherence. METHOD: In this study, clinically applicable tests were used to measure a range of ocular characteristics, including central and peripheral corneal curvature, tear film status, eyelid characteristics, central corneal thickness, and ocular rigidity in a group of 22 young adult subjects for whom reliable estimates for frequency of overnight RGP lens adherence had been obtained from earlier studies. RESULTS: Linear discriminant analysis revealed that a higher frequency of lens adherence was associated with lower ocular rigidity, thinner central corneas, greater eyelid tension, and lower amounts of corneal astigmatism. CONCLUSIONS: These findings suggest a clinical approach for identifying patients who may develop clinically significant lens adherence during RGP extended wear, and also provide support for the "thin film adherence" theory of RGP lens adherence.     

Role of ligaments and facets in lumbar spinal stability

STUDY DESIGN: The issue of segmental stability using finite element analysis was studied. Effect of ligament and facet (total and partial) removal and their geometry on segment response were studied from the viewpoint of stability. OBJECTIVES: To predict factors that may be linked to the cause of rotational instabilities, spondylolisthesis, retrospondylolisthesis, and stenosis. SUMMARY OF BACKGROUND DATA: The study provides a comprehensive study on the role of facets and ligaments and their geometry in preserving segmental stability. No previous biomechanical study has explored these issues in detail. METHODS: Three-dimensional nonlinear finite element analysis was performed on L3-L4 motion segments, with and without posterior elements (ligaments and facets), subjected to sagittal moments. Effects of ligament and facet (partial and total) removal and their orientations on segment response are examined from the viewpoint of stability. RESULTS: Ligaments play an important role in resisting flexion rotation and posterior shear whereas facets are mainly responsible for preventing large extension rotation and anterior displacement. Facet loads and stresses are high under large extension and anterior shear loading. Unlike total facetectomy, selective removal of facets does not compromise segmental stability. Facet loads are dependent on spatial orientation. CONCLUSIONS: Rotational instability in flexion or posterior displacement (retrospondylolisthesis) is unlikely without prior damage of ligaments, whereas instability in extension rotation or forward displacement (spondylolisthesis) is unlikely before facet degeneration or removal. The facet stress and displacement distribution predicts that facet osteoarthritis or hypertrophy leading to spinal stenosis is most likely under flexion-anterior shear loading. Selective facetectomy may restore spinal canal size without compromising the stability of the segment. A facet that is more sagittally oriented may be linked to the cause of spondylolisthesis, whereas a less transversely oriented facet joint may be linked to rotational instabilities in extension.