Quantitative estimation of retinal nerve fiber layer height in glaucoma and the relationship with optic nerve head topography and visual field

Purpose: The authors estimated the retinal nerve fiber layer height (RNFLH) measurements in patients with glaucoma compared with those in age-matched healthy subjects as obtained by the laser scanning tomography and assessed the relationship between RNFLH measurements and optic and visual field status. Methods: Parameters of optic nerve head topography and RNFLH were evaluated in 125 eyes of 21 healthy subjects and 104 patients with glaucoma using the Heidelberg Retina Tomograph ([HRT] Heidelberg Engineering GmbH, Heidelberg, Germany) for the entire disc area and for the superior 70°(50°temporal and 20°nasal to the vertical midline) and inferior 70°sectors of the optic disc. The mean deviation of the visual field, as determined by the Humphrey program 24-2 (Humphrey Instruments, Inc., San Leonardo, CA, U.S.A) was calculated in the entire field and in the superior and inferior Bjerrum area. Result: Retinal nerve fiber layer height parameters (mean RNFLH and RNFL cross-sectional area) were decreased significantly in patients with glaucoma compared with healthy individuals. Retinal nerve fiber layer height parameters was correlated strongly with rim volume, rim area, and cup/disc area ratio. Of the various topography measures, retinal nerve fiber layer (RNFL) parameters and cup/disc area ratio showed the strongest correlation with visual field mean deviation in patients with glaucoma. Conclusion: Retinal nerve fiber layer height measures were reduced substantially in patients with glaucoma compared with age-matched healthy subjects. Retinal nerve fiber layer height was correlated strongly with topographic optic disc parameters and visual field changes in patients with glaucoma.

Inter-observer agreement in evaluating the anterior chamber angle by ultrasound biomicroscopy

Purpose. To determine the agreement between observers in estimating the configuration of the human anterior chamber angle (ACA) using ultrasound biomicroscopy (UBM). Methods. Two masked clinicians used UBM images to estimate, in 41 eyes, the configuration of the ACA, especially (1) the position of contact between the peripheral iris and the inside of the eye wall, (2) the angularity of the approach to the ACA, and (3) the curvature of the peripheral iris. Agreement between observers was evaluated by the kappa statistic. Results. Inter-observer agreement in assessing the iris insertion (kappa = 0.79), angular width (Kappa = 0.95), and the peripheral iris curvature (kappa = 0.84) was high. Conclusions. The agreement between observers in evaluating the anterior chamber angle configuration by UBM was excellent.

Increasing the size of a small peripheral iridotomy widens the anterior chamber angle:An ultrasound biomicroscopy study

Purpose: A peripheral iridotomy (PI) is the treatment of choice for pupillary block. In this study we investigated the effect of enlarging the size of a small PI on the anterior chamber angle in patients with angle closure using ultrasound biomicroscopy (UBM). Patients and Methods: Patients who had been treated with laser peripheral iridotomy for angle closure and were identified to have a small patent PI (<100 µm) with still appositionally closed anterior chamber angle were selected prospectively. The anterior chamber angle was assessed using UBM. The angle opening distance 500 µm from the scleral spur (AOD500) as well as the anterior and posterior chamber depth (ACD and PCD) 1000 µm from the scleral spur was measured. In addition, the ACD/PCD ratio was calculated. Afterwards, the PI was enlarged using an Nd: YAG laser and the UBM measurements were repeated as described above. Results: Six eyes of six patients were examined. After the enlargement of the PI the average AOD500 increased from 109 µm (±36) to 147 µm (±40) (p

Agreement between clinical and ultrasound biomicroscopy findings in different types of glaucoma

Purpose. To evaluate agreement between clinical examination (slit lamp examination and gonioscopy) and ultrasound biomicroscopy (UBM) in characterizing various features of the anterior chamber angle and adjacent structures. Methods. Twenty-eight patients (51 eyes) with open angle glaucoma (14), closed angle glaucoma (4), narrow angle and/or plateau iris (10), who had undergone UBM between March 94 and September 95 were studied. Evaluated parameters included angle width, iris configuration and presence of angle closure. The UBMs were reviewed in a masked fashion. Results. In 87.8% of cases there was agreement (within 10 degrees) between gonioscopic and UBM estimates of angle width. In all cases with greater than 10 degrees difference (12.2%) the angle size estimated by UBM was less than that estimated clinically. Iris configuration was graded identically in 51% of cases; the majority of disagreements (76.1%) occurred in cases graded as "regular" by gonioscopy and as "steep" by UBM. Angle closure was judged to be present more frequently by UBM. Conclusions. UBM and gonioscopy do not necessarily yield identical values for angle width, iris configuration, and presence of angle closure.

Ultrasound biomicroscopy in deep sclerectomy

Purpose: To evaluate by ultrasound biomicroscopy (UBM) the anatomical characteristics and the intraocular pressure (IOP) lowering mechanisms of deep sclerectomy after long-term follow-up. Methods: In all, 22 eyes of 21 consecutive patients who had deep sclerectomy were examined by UBM. Several UBM variables were prospectively evaluated, including the presence and maximum length and height of the intrascleral space, the minimum thickness of residual trabeculo-Descemet membrane (TDM), the presence and type of subconjunctival filtering bleb, and the presence of other possible drainage sites, for example suprachoroidal. Surgical success was considered to be achieved when the IOP was

Ultrasound biomicroscopy in infantile glaucoma

Background: Glaucoma in infants has many causes. Evaluation of the anatomy of the anterior segment of eyes with infantile glaucoma may help to determine the pathogenesis of an infant's disease and influence therapeutic decisions. Methods: Eleven eyes of six infants with glaucoma were evaluated with ultrasound biomicroscopy (UBM) to evaluate the anatomic characteristics and relationships of the anterior segment structures. Results: The anterior chamber angle, iris, lens, ciliary body, and posterior chamber angle could be imaged in detail. Elongated and anteriorly placed ciliary processes were noted in all eight eyes with trabeculodysgenesis. There were no apparent anomalies in the trabecular meshwork, or anterior chamber. In three eyes with dense corneal opacities, ultrasound biomicroscopy showed severe anterior segment disorganization and thin central corneas with posterior corneal excavation. Conclusions: Ultrasound biomicroscopy is a useful non-invasive method for evaluating infants with glaucoma in cases with corneal opacities. This information can help in surgical planning for glaucoma management.

Intraobserver and interobserver agreement in evaluating the anterior chamber angle configuration by ultrasound biomicroscopy

Purpose: To determine the intra- and interobserver agreement in assessing the configuration of the human anterior chamber angle using ultrasound biomicroscopy (UBM). Methods: Two masked clinicians used ubm images to estimate, in 41 eyes, (a) the position of contact between the peripheral iris and the inside of the eye wall, (b) the angular size of the anterior chamber angle (ACA), and (c) the curvature of the peripheral iris. Both observers, masked to the previous results, examined the same images in a second session. Agreement was evaluated using the unweighted ? statistic. Results: Intraobserver agreement in assessing the iris insertion, angular width, and the iris curvature was high (range of ? values, 0.83-0.92). Interobserver agreement in evaluating the level of iris insertion (? = 0.79), the angular width (? = 0.95), and the iris curvature (? = 0.84) was also high. Conclusion: The agreement within the same observer and between observers in evaluating the ACA configuration by UBM was excellent.

Quantitative detection of DNA by autocatalytic enlargement of hybridized gold nanoprobes

Quantitative detection of specific viral DNA has become a pressing issue for the earlier clinical diagnosis of viral infectious diseases. Therefore, in this paper, we report a simple, sensitive, and inexpensive quantitative approach for DNA detection based on the autocatalytic Au deposition of gold nanoprobes via the surface reduction of AuCl4- to Au0 on their surface in the presence of ascorbic acid (AA) and cetyltrimethylammonium bromide (CTAB). On this basis, signal enhancements in the absorbance intensity and kinetic behavior of gold enlargement in the aqueous phase have been well investigated and explained for the selection of analytical parameters. To achieve high sensitivity, magnetic particles conjugated with capture probes (PMPs) were employed for the collection of gold nanoprobes. After denaturated by ion a pH 11 solution, the amplified signals of gold nanoprobes, which is proportional to the concentration of the target DNA, could easily be confirmed by a UV-vis scanning spectrophotometer. Limit of detection could be obtained as low as 1.0 fM by this simple method.

Molecular dynamics simulation model for the quantitative assessment of tool wear during single point diamond turning of cubic silicon carbide

Silicon carbide (SiC) is a material of great technological interest for engineering applications concerning hostile environments where silicon-based components cannot work (beyond 623 K). Single point diamond turning (SPDT) has remained a superior and viable method to harness process efficiency and freeform shapes on this harder material. However, it is extremely difficult to machine this ceramic consistently in the ductile regime due to sudden and rapid tool wear. It thus becomes non trivial to develop an accurate understanding of tool wear mechanism during SPDT of SiC in order to identify measures to suppress wear to minimize operational cost.

In this paper, molecular dynamics (MD) simulation has been deployed with a realistic analytical bond order potential (ABOP) formalism based potential energy function to understand tool wear mechanism during single point diamond turning of SiC. The most significant result was obtained using the radial distribution function which suggests graphitization of diamond tool during the machining process. This phenomenon occurs due to the abrasive processes between these two ultra hard materials. The abrasive action results in locally high temperature which compounds with the massive cutting forces leading to sp3–sp2 order–disorder transition of diamond tool. This represents the root cause of tool wear during SPDT operation of cubic SiC. Further testing led to the development of a novel method for quantitative assessment of the progression of diamond tool wear from MD simulations.

Review and quantitative meta-analysis of diet suggests the Eurasian otter (Lutra lutra) is likely to be a poor bioindicator

The Eurasian otter (Lutra lutra L.) is a top predator in aquatic systems and plays an important role in ecosystem functioning. However, it has undergone dramatic declines throughout Europe as a result of environmental degradation. We examine the putative role of the otter as a bioindicator in Ireland which remains a stronghold for the species and affords a unique opportunity to examine variation in its ecological niche. We describe diet, using spraint contents, along rivers during 2010 and conduct a review and quantitative meta-analysis of the results of a further 21 studies. We aimed to assess variation in otter diet in relation to river productivity, a proxy for natural nutrification and anthropogenic eutrophication, and availability of salmonid prey (Salmo trutta and Salmo salar), to test the hypothesis that otter diet is related to environmental quality. Otter diet did not vary with levels of productivity or availability of salmonids whilst Compositional Analysis suggested there was no selection of salmonid over non-salmonid fish. There was a distinct niche separation between riverine and lacustrine systems, the latter being dominated by Atlantic eel (Anguilla anguilla). Otters are opportunistic and may take insects, freshwater mussels, birds, mammals and even fruit. Otters living along coasts have a greatest niche breath than those in freshwater systems which encompasses a wide variety of intertidal prey though pelagic fish are rarely taken. It is concluded that the ability of the otter to feed on a wide diversity of prey taxa and the strong influence of habitat type, renders it a poor bioindicator of environmental water quality. It seems likely that the plasticity of the habitat and dietary niche of otters, and the extent of suitable habitat, may have sustained populations in Ireland despite intensification of agriculture during the 20th century.

Toward Quantitative Electrochemical Measurements on the Nanoscale by Scanning Probe Microscopy: Environmental and Current Spreading Effects

The application of electric bias across tip–surface junctions in scanning probe microscopy can readily induce surface and bulk electrochemical processes that can be further detected though changes in surface topography, Faradaic or conductive currents, or electromechanical strain responses. However, the basic factors controlling tip-induced electrochemical processes, including the relationship between applied tip bias and the thermodynamics of local processes, remains largely unexplored. Using the model Li-ion reduction reaction on the surface in Li-ion conducting glass ceramic, we explore the factors controlling Li-metal formation and find surprisingly strong effects of atmosphere and back electrode composition on the process. We find that reaction processes are highly dependent on the nature of the counter electrode and environmental conditions. Using a nondepleting Li counter electrode, Li particles could grow significantly larger and faster than a depleting counter electrode. Significant Li ion depletion leads to the inability for further Li reduction. Time studies suggest that Li diffusion replenishes the vacant sites after 12 h. These studies suggest the feasibility of SPM-based quantitative electrochemical studies under proper environmental controls, extending the concepts of ultramicroelectrodes to the single-digit nanometer scale.

Plasma IL-6 levels correlate with clinical and ultrasound measures of arthritis in patients with systemic lupus erythematosus

ObjectiveThe objective of this paper is to elucidate the role of specific cytokines in lupus (SLE) arthritis.MethodsFifty SLE and 40 RA patients had an ultrasound (US) scan of their hand as per standardized protocols. US scores were expressed per joint and as a total 'US activity' score, (sum of power Doppler (PD) and grey-scale synovial hypertrophy scores in all joints) and a total erosion score. SLE disease activity was assessed (BILAG and SELENA-SLEDAI). Plasma levels of IL-6, TNF-alpha and BLyS were measured using sandwich ELISA kits (Quantikine kits, R & D).ResultsOn the basis of the US results SLE patients were divided into three groups: erosive arthritis (n?=?20), non-erosive arthritis (n?=?18) and those with a normal US scan (n?=?12). Across the SLE groups plasma IL-6 levels correlated with CRP (p?