Effect of superspeed sintering on translucency, opalescence, microstructure, and phase fraction of multilayered 4 mol% yttria-stabilized tetragonal zirconia polycrystal and 6 mol% yttria-stabilized partially stabilized zirconia ceramics

STATEMENT OF PROBLEM

The optical properties of recently developed multilayer zirconia have mainly been studied for the effects of conventional sintering and speed sintering but not as much for the effect of superspeed sintering. As superspeed sintering protocols typically require a higher sintering temperature and higher heating and cooling rates than speed- and conventional sintering protocols, the optical properties of superspeed sintered zirconia may be affected differently.

PURPOSE

The purpose of this in vitro study was to investigate the effect of superspeed sintering on the optical properties, microstructure, and phase fraction of multilayered 4 mol% yttria-stabilized (4Y-) and 6 mol% yttria-stabilized (6Y-) zirconia.

MATERIAL AND METHODS

Multilayered 4Y- and 6Y-zirconia were sectioned. After conventional and superspeed sintering, the translucency parameter (TP), and opalescence parameter (OP) were measured with a spectrophotometer (n=10). To obtain the grain sizes from the field emission scanning electron microscopy (FE-SEM) images for each layer (n=2), more than 500 (6Y-zirconia) and 800 grains (4Y-zirconia) were measured by linear intercept methods. The phase fractions were obtained through X-ray diffraction (XRD) analysis by using the Rietveld method (n=1). The results were analyzed by 3-way ANOVA and post hoc Tukey honest significant difference tests (TP and OP) and by 3-way ANOVA and post hoc Scheffé tests (grain size) (α=.05).

RESULTS

No layers exhibited a significant difference in TP after superspeed sintering, except the dentin layer (DL) and transition layer 2 (T2) of 4Y- and 6Y-zirconia, respectively. The TP increased (P<.05) in DL for superspeed sintered 4Y-zirconia and decreased (P<.05) in T2 for the superspeed sintered 6Y-zirconia. However, the difference in TP by superspeed sintering was lower than the perceptibility thresholds of 50:50%. The OP decreased (P<.05) in the DL and T2 of 4Y-zirconia after superspeed sintering. For 6Y-zirconia, the OP decreased (P<.05) in all layers except for the transition layer 1 (T1) after superspeed sintering. However, the difference in OP values was minimal, with only a 1.1 difference observed for Zolid Gen-X (4Y) and a range of 1.22 to 1.62 for Katana UTML (6Y) when using superspeed sintering. No significant change was found in the grain size after superspeed sintering of either zirconia. Regardless of the sintering speed, the average grain size of the 6Y-zirconia (conventional: 2.09 to 2.21 μm; superspeed: 2.11 to 2.20 μm) was larger than that of the 4Y-zirconia (conventional: 0.50 to 0.52 μm; superspeed: 0.52 to 0.54 μm). Owing to superspeed sintering, the metastable tetragonal (T') phase content increased while the tetragonal (T) phase decreased in 4Y-zirconia; in 6Y-zirconia, the cubic (C) phase content increased, while the T'-phase content decreased.

CONCLUSIONS

Superspeed sintering did not result in any clinically significant changes in the translucency and opalescence of 4Y- or 6Y-zirconia.

A33 EFFECTS OF THE NEXT GENERATION PROBIOTIC, AKKERMANSIA MUCINIPHILA, ON INTESTINAL INFLAMMATION AND BARRIER FUNCTION

Background

Inflammatory bowel disease (IBD), characterised by chronic intestinal inflammation, is hypothesised to arise from the interplay between susceptibility genes, the immune system, environmental factors, and gut microbiota. Akkermansia muciniphila is a symbiotic bacterium that accounts for 1-5% of the human fecal microbiota. This microbe has been hailed as a next-generation probiotic, principally with regard to its plethora of beneficial host interactions, including the ability to influence mucin secretion and strengthen the intestinal barrier.

Purpose

Though a clear-cut role and mechanism by which A. muciniphila influences inflammatory conditions is unknown, evidence indicates this microbe is depleted in IBD, suggesting it may have protective effects that are lost in these conditions. Here, we investigate the role and mechanism of A. muciniphila in intestinal inflammation and its influence on intestinal barrier function by utilizing barrier-disrupting models of colitis.

Method

Across several experimental models of intestinal inflammation including the chemically-induced dextran sulphate sodium (DSS) model, the parasitic-based model of Trichuris muris infection, and the spontaneous Muc2-/- model, A.muciniphila was administered by oral gavage. Disease activity index, macroscopic scoring and histological scoring were all performed to assess the severity of intestinal inflammation. Various pro- and anti-inflammatory cytokines were assessed within colonic tissue using commercially available ELISA kits.To investigate the effects that A. muciniphila has on barrier function in the context of colitis, reverse transcriptase qPCR was used to explore several factors, including several TJPs, AMPs, and mucins. To analyse the composition of the microbiota and changes in diversity with A. muciniphila supplementation, 16S rRNA sequencing of fecal samples was performed.

Result(s)

Though only minor benefits were derived from this microbe in germ-free mice, in specific pathogen-free (SPF) mice, administration of pasteurized A. muciniphila in a DSS recovery model ameliorated inflammation severity and promoted recovery compared to controls. When gavaged prior to DSS administration, both live and pasteurized A. muciniphila failed to diminish inflammatory markers indicating minimal preventative effects. T. muris-infected SPF mice treated with live A. muciniphila showed increased levels of Th2 and anti-inflammatory cytokines, decreased worm burden, and enhanced levels of the mucin, Muc5ac, compared with those receiving control broth or pasteurized bacteria. Further, both live and pasteurized A. muciniphila ameliorated the severity of inflammation in a mucin 2 deficient (Muc2^-/-) mouse model of spontaneous colitis, indicating that these protective effects are Muc2-independent.

Conclusion(s)

These observations provide us not only with an enhanced understanding of the role A. muciniphila plays in the pathogenesis of intestinal inflammatory conditions but also may fuel novel avenues of treatment for those with IBD.

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Disclosure of Interest

None Declared

Ultrasonic-assisted synthesis of ZnTe nanostructures and their structural, electrochemical and photoelectrical properties

Colloidal zinc telluride (ZnTe) nanostructures were successfully processed through a simple and facile ultrasonic (sonochemical) treatment for photoelectronic applications. The particle-like morphological features, phase and nature of valence state of various metal ions existing in ZnTe were examined using electron and X-ray photoelectron spectroscopic tools. Raman spectroscopic measurements revealed the dominance of exciton-phonon coupling and occurrence of TeO₂ traces in ZnTe through the corresponding vibrations. Optical bandgap of the ZnTe suspension was estimated to be around 2.15eV, authenticating the direct allowed transitions. The p-type electrical conductivity and charge carrier density of ZnTe were additionally estimated from the Bode, Nyquist and Mott-Schottky type impedance plots. The photoelectrical properties of ZnTe were investigated by fabricating p-ZnTe/n-Si heterostructures and studying their corresponding current-voltage characteristics under dark and white light illumination. The diodes revealed excellent rectifying behaviour with significant increase in reverse current under illumination. The stability of the devices were also affirmed through the time-dependent photoresponse characteristics, which actually suggested the improved and effective separation of photo generated electron hole pairs across the integrated heterojunctions. The obtained results also augment the potential of sonochemically processed ZnTe for application in photo detection and sensor related functions.

Time of Application of Sodium Ascorbate on Bonding to Bleached Dentin

This study examined the effects of different application times of sodium ascorbate (SA) on the bond strength of composite resin to bleached dentin. Specimens with an exposed dentin surface were divided into 3 groups according to the type of bleaching agent used: Group A, mixture of sodium perborate (SP) and distilled water (DW); Group B, mixture of SP and hydrogen peroxide (HP); control group, no bleaching. Each group was classified into 10 subgroups. Subgroups IB and DB underwent immediate bonding and delayed bonding, respectively. 10% SA was applied to 3, 5, 10, and 30 minutes and 1, 24, 48, and 72 hours, respectively. Microtensile bond strength (μTBS) was measured after restoration, and the data was analyzed by one-way ANOVA and Scheffé's test. Before restoration, the dentin surfaces were examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). SEM showed that most dentin surfaces were filled with crystals when SA was applied to more than 24 hours. EDS revealed peaks of calcium, carbon, oxygen, and sodium. The application of SA for 5 minutes to 48 hours or for 30 minutes to 24 hours is suggested when a mixture of SP and DW or HP is used, respectively.

Effect of immersion into solutions at various pH on the color stability of composite resins with different shades

Objectives

This study examined the color changes of a resin composite with different shades upon exposure to water with different pH.

Materials and Methods

Nanohybrid resin composites (Filtek Z350XT, 3M ESPE) with four different shades (A2, A3, B1, and B2) were immersed in water with three different pH (pH 3, 6, and 9) for 14 day. The CIE L*a*b* color coordinates of the specimens were evaluated before and after immersion in the solutions. The color difference (ΔE*) and the translucency parameter (TP) were calculated using the color coordinates.

Results

ΔE* ranged from 0.33 to 1.58, and the values were affected significantly by the pH. The specimens immersed in a pH 6 solution showed the highest ΔE* values (0.87 - 1.58). The specimens with a B1 shade showed the lowest ΔE* change compared to the other shades. TP ranged from 7.01 to 9.46 depending on the pH and resin shade. The TP difference between before and after immersion in the pH solutions was less than 1.0.

Conclusions

The resulting change of color of the tested specimens did not appear to be clinically problematic because the color difference was < 1.6 in the acidic, neutral, and alkaline solutions regardless of the resin shade, i.e., the color change was imperceptible.

Effect of dentin pretreatment and curing mode on the microtensile bond strength of self-adhesive resin cements

PURPOSE

The aim was to evaluate the effect of curing mode and different dentin surface pretreatment on microtensile bond strength (µTBS) of self-adhesive resin cements.

MATERIALS AND METHODS

Thirty-six extracted human permanent molars were sectioned horizontally exposing flat dentin surface. The teeth were divided into 12 groups (3 teeth/group) according to the dentin surface pretreatment methods (control, 18% EDTA, 10% Polyacrylic acid) and curing mode (self-curing vs. light-curing) of cement. After pretreatment, composite resin blocks were cemented with the following: (a) G-CEM LinkAce; (b) RelyX U200, followed by either self-curing or light-curing. After storage, the teeth were sectioned and µTBS test was performed using a microtensile testing machine. The data was statistically analyzed using one-way ANOVA, Student T-test and Scheffe's post-hoc test at P<.05 level.

RESULTS

For G-CEM LinkAce cement groups, polyacrylic acid pretreatment showed the highest µTBS in the self-cured group. In the light-cured group, no significant improvements were observed according to the dentin surface pretreatment. There were no significant differences between curing modes. Both dentin surface pretreatment methods helped to increase the µTBS of RelyX U200 resin cement significantly and degree of pretreatment effect was similar. No significant differences were found regarding curing modes except control groups. In the comparisons of two self-adhesive resin cements, all groups within the same pretreatment and curing mode were significantly different excluding self-cured control groups.

CONCLUSION

Selecting RelyX U200 used in this study and application of dentin surface pretreatment with EDTA and polyacrylic acid might be recommended to enhance the bond strength of cement to dentin.

Effect of resin thickness on the microhardness and optical properties of bulk-fill resin composites

OBJECTIVES

This study evaluated the effects of the resin thickness on the microhardness and optical properties of bulk-fill resin composites.

METHODS

Four bulk-fill (Venus Bulk Fill, Heraeus Kulzer; SDR, Dentsply Caulk; Tetric N-Ceram Bulk Fill, Ivoclar vivadent; SonicFill, Kerr) and two regular resin composites (Charisma flow, Heraeus Kulzer; Tetric N-Ceram, Ivoclar vivadent) were used. Sixty acrylic cylindrical molds were prepared for each thickness (2, 3 and 4 mm). The molds were divided into six groups for resin composites. The microhardness was measured on the top and bottom surfaces, and the colors were measured using Commission Internationale d'Eclairage (CIE) L (*) a (*) b (*) system. Color differences according to the thickness and translucency parameters and the correlations between the microhardness and translucency parameter were analyzed. The microhardness and color differences were analyzed by ANOVA and Scheffe's post hoc test, and a student t-test, respectively. The level of significance was set to α = 0.05.

RESULTS

The microhardness decreased with increasing resin thickness. The bulk-fill resin composites showed a bottom/top hardness ratio of almost 80% or more in 4 mm thick specimens. The highest translucency parameter was observed in Venus Bulk Fill. All resin composites used in this study except for Venus Bulk Fill showed linear correlations between the microhardness and translucency parameter according to the thickness.

CONCLUSIONS

Within the limitations of this study, the bulk-fill resin composites used in this study can be placed and cured properly in the 4 mm bulk.

Effect of additional etching and ethanol-wet bonding on the dentin bond strength of one-step self-etch adhesives

Objectives

This study examined the effects of additional acid etching on the dentin bond strength of one-step self-etch adhesives with different compositions and pH. The effect of ethanol wetting on etched dentin bond strength of self-etch adhesives was also evaluated.

Materials and Methods

Forty-two human permanent molars were classified into 21 groups according to the adhesive types (Clearfil SE Bond [SE, control]; G-aenial Bond [GB]; Xeno V [XV]; Beauti Bond [BB]; Adper Easy Bond [AE]; Single Bond Universal [SU]; All Bond Universal [AU]), and the dentin conditioning methods. Composite resins were placed on the dentin surfaces, and the teeth were sectioned. The microtensile bond strength was measured, and the failure mode of the fractured specimens was examined. The data were analyzed statistically using two-way ANOVA and Duncan's post hoc test.

Results

In GB, XV and SE (pH ≤ 2), the bond strength was decreased significantly when the dentin was etched (p < 0.05). In BB, AE and SU (pH 2.4 - 2.7), additional etching did not affect the bond strength (p > 0.05). In AU (pH = 3.2), additional etching increased the bond strength significantly (p < 0.05). When adhesives were applied to the acid etched dentin with ethanol-wet bonding, the bond strength was significantly higher than that of the no ethanol-wet bonding groups, and the incidence of cohesive failure was increased.

Conclusions

The effect of additional acid etching on the dentin bond strength was influenced by the pH of one-step self-etch adhesives. Ethanol wetting on etched dentin could create a stronger bonding performance of one-step self-etch adhesives for acid etched dentin.

The effect of resin thickness on polymerization characteristics of silorane-based composite resin

Objectives

This study examined the influence of the resin thickness on the polymerization of silorane- and methacrylate-based composites.

Materials and Methods

One silorane-based (Filtek P90, 3M ESPE) and two methacrylate-based (Filtek Z250 and Z350, 3M ESPE) composite resins were used. The number of photons were detected using a photodiode detector at the different thicknesses (thickness, 1, 2 and 3 mm) specimens. The microhardness of the top and bottom surfaces was measured (n = 15) using a Vickers hardness with 200 gf load and 15 sec dwell time conditions. The degree of conversion (DC) of the specimens was determined using Fourier transform infrared spectroscopy (FTIR). Scratched powder of each top and bottom surface of the specimen dissolved in ethanol for transmission FTIR spectroscopy. The refractive index was measured using a Abbe-type refractometer. To measure the polymerization shrinkage, a linometer was used. The results were analyzed using two-way ANOVA and Tukey's test at p < 0.05 level.

Results

The silorane-based resin composite showed the lowest filler content and light attenuation among the specimens. P90 showed the highest values in the DC and the lowest microhardness at all depth. In the polymerization shrinkage, P90 showed a significantly lower shrinkage than the rest two resin products (p < 0.05). P90 showed a significantly lower refractive index than the remaining two resin products (p < 0.05).

Conclusions

DC, microhardness, polymerization rate and refractive index linearly decreased as specimen thickness linearly increased. P90 showed much less polymerization shrinkage compared to other specimens. P90, even though achieved the highest DC, showed the lowest microhardness and refractive index.

Failure of Helicobacter pylori eradication and age are independent risk factors for recurrent neoplasia after endoscopic resection of early gastric cancer in 283 patients

BACKGROUND

Whether the incidence of metachronous gastric dysplasia and cancer could be decreased by eradication of Helicobacter pylori after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC).

AIM

To compare the incidence of metachronous gastric lesion in the eradicated group and the persistent group. Second end point is to evaluate the risk factors for metachronous gastric lesions after ESD for EGC.

METHODS

In a single centre, between May 2007 and May 2010, the patients who had evidence of H. pylori infection at the time of ESD for EGC were included, and the follow-up data were analysed retrospectively.

RESULTS

We enrolled 283 patients who have shown H. pylori infection at the time of ESD for EGC. Successful eradication was achieved for 214 patients (75.6%) (Eradicated group), and 69 patients (24.4%) showed persistent H. pylori infection (Persistent group). Metachronous gastric lesions developed in 13 (18.8%) in the persistent group and 18 (8.4%) in the eradicated group (P = 0.016). In the ≥60-year-old group, the cumulative incidence of metachronous gastric cancer showed a significant increase (P = 0.012). Cumulative hazard ratio of subsequent gastric metachronous lesions differed between the eradication group and the persistent infection group (OR = 2.322, 95% CI = 1.136-4.744, P = 0.021), and ≥60 age at the time of endoscopic resection (OR = 2.803, 95% CI = 1.207-6.509, P = 0.016).

CONCLUSIONS

Both persistent H. pylori infection and old age (≥60) are independent risk factors for the increased incidence of metachronous gastric cancer.

The effect of additional etching and curing mechanism of composite resin on the dentin bond strength

PURPOSE

The aim of this study was to evaluate the effects of additional acid etching and curing mechanism (light-curing or self-curing) of a composite resin on the dentin bond strength and compatibility of one-step self-etching adhesives.

MATERIALS AND METHODS

Sixteen human permanent molars were randomly divided into eight groups according to the adhesives used (All-Bond Universal: ABU, Clearfil S3 Bond: CS3), additional acid etching (additional acid etching performed: EO, no additional acid etching performed: EX), and composite resins (Filtek Z-250: Z250, Clearfil FII New Bond: CFNB). Group 1: ABU-EO-Z250, Group 2: ABU-EO-CFNB, Group 3: ABU-EX-Z250, Group 4: ABU-EX-CFNB, Group 5: CS3-EO-Z250, Group 6: CS3-EO-CFNB, Group 7: CS3-EX-Z250, Group 8: CS3-EX-CFNB. After bonding procedures, composite resins were built up on dentin surfaces. After 24-hour water storage, the teeth were sectioned to make 10 specimens for each group. The microtensile bond strength test was performed using a microtensile testing machine. The failure mode of the fractured specimens was examined by means of an optical microscope at ×20 magnification. The data was analyzed using a one-way ANOVA and Scheffe's post-hoc test (α=.05).

RESULTS

Additional etching groups showed significantly higher values than the no additional etching group when using All-Bond Universal. The light-cured composite resin groups showed significantly higher values than the self-cured composite resin groups in the Clearfil S3 Bond.

CONCLUSION

The additional acid etching is beneficial for the dentin bond strength when using low acidic one-step self-etch adhesives, and low acidic one-step self-etch adhesives are compatible with self-cured composite resin. The acidity of the one-step self-etch adhesives is an influencing factor in terms of the dentin bonding strength and incompatibility with a self-cured composite resin.

Effect of temperature on the mass and color stability of additional photoinitiatorcontaining composite resins

The purpose of this study was to evaluate how the temperature affects the stability of polymerized additional photoinitiator-containing composite resins. Five resin products were light-cured using a quartz-tungsten-halogen, and single and dual emission peaks lightemitting diodes. The degree of conversion (DC) and water sorption, solubility, and color change of the specimens were evaluated after immersion in the solutions of different temperatures (4, 37, and 60ºC) for 14 days. On the top surface, the light-curing units had no significant influence on DC of the tested specimens. On the bottom surface, the influence was inconsistent. As the solution temperature increased, water sorption also consistently increased in all specimens, whereas solubility changed inconsistently. Water sorption and solubility had a high linear correlation only at low temperature solution. Color change of the specimens was similar, mostly slight, and statistically inconsistent regardless of solution temperature. The restored composite resins are needed to avoid contact with hot solutions for durable dental restoration.

Effect of solution temperature on the mechanical properties of dual-cure resin cements

PURPOSE

This study was to evaluate the effect of the solution temperature on the mechanical properties of dualcure resin cements.

MATERIALS AND METHODS

For the study, five dual-cure resin cements were chosen and light cured. To evaluate the effect of temperature on the specimens, the light-cured specimens were immersed in deionized water at three different temperatures (4, 37 and 60℃) for 7 days. The control specimens were aged in a 37℃ dry and dark chamber for 24 hours. The mechanical properties of the light-cured specimens were evaluated using the Vickers hardness test, three-point bending test, and compression test, respectively. Both flexural and compressive properties were evaluated using a universal testing machine. The data were analyzed using a two way ANOVA with Tukey test to perform multiple comparisons (α=0.05).

RESULTS

After immersion, the specimens showed significantly different microhardness, flexural, and compressive properties compared to the control case regardless of solution temperatures. Depending on the resin brand, the microhardness difference between the top and bottom surfaces ranged approximately 3.3-12.2%. Among the specimens, BisCem and Calibra showed the highest and lowest decrease of flexural strength, respectively. Also, Calibra and Multilink Automix showed the highest and lowest decrease of compressive strength, respectively compared to the control case.

CONCLUSION

The examined dual-cure resin cements had compatible flexural and compressive properties with most methacrylate-based composite resins and the underlying dentin regardless of solution temperature. However, the effect of the solution temperature on the mechanical properties was not consistent and depended more on the resin brand.

Diffusion tensor imaging-demonstrated differences between hemiplegic and diplegic cerebral palsy with symmetric periventricular leukomalacia

BACKGROUND AND PURPOSE

Patients with cerebral palsy have variable clinical presentations such as hemiplegic, diplegic, or quadriplegic patterns though they have PVL on conventional MR images. The authors investigated whether DTT can differentiate between hemiplegic and diplegic CP in patients presenting with symmetric PVL on conventional MR images.

MATERIALS AND METHODS

One hundred thirteen consecutive pediatric patients with definite hemiplegic (59 patients; 30 boys, 29 girls; mean age, 34.19 months; range, 24-52 months) or diplegic (54 patients; 27 boys, 27 girls; mean age, 31.07 months; range, 24-48 months) symptoms and bilateral symmetric PVL on conventional brain MR imaging were recruited. The states of CSTs were examined by using DTT, and the asymmetries of right and left CSTs in the hemiplegic and diplegic groups were compared by using asymmetric anisotropy indexes and asymmetric mean diffusivity indexes.

RESULTS

All patients in the hemiplegic group with asymmetric results exhibited disrupted integrities of more affected CSTs and sparing of less affected CSTs. However, diplegic patients revealed symmetric disrupted findings of the right and left CSTs at the upper periventricular level. Asymmetric anisotropy index and asymmetric mean diffusivity index values were significantly higher in the hemiplegic group than in the diplegic group (P < .05), and these results of DTT significantly corresponded with their typical clinical manifestation.

CONCLUSIONS

DTT may be very useful for the detailed estimation of the CST state in patients with bilateral symmetric PVL.

Heat transfer and pressure drop characteristics of nanofluids in a plate heat exchanger

In this paper, the heat transfer characteristics and pressure drop of the ZnO and Al2O3 nanofluids in a plate heat exchanger were studied. The experimental conditions were 100-500 Reynolds number and the respective volumetric flow rates. The working temperature of the heat exchanger was within 20-40 degrees C. The measured thermophysical properties, such as thermal conductivity and kinematic viscosity, were applied to the calculation of the convective heat transfer coefficient of the plate heat exchanger employing the ZnO and Al2O3 nanofluids made through a two-step method. According to the Reynolds number, the overall heat transfer coefficient for 6 vol% Al2O3 increased to 30% because at the given viscosity and density of the nanofluids, they did not have the same flow rates. At a given volumetric flow rate, however, the performance did not improve. After the nanofluids were placed in the plate heat exchanger, the experimental results pertaining to nanofluid efficiency seemed inauspicious.

Novel drug delivery systems for glaucoma

Reduction of intraocular pressure (IOP) by pharmaceutical or surgical means has long been the standard treatment for glaucoma. A number of excellent drugs are available that are effective in reducing IOP. These drugs are typically applied as eye drops. However, patient adherence can be poor, thus reducing the clinical efficacy of the drugs. Several novel delivery systems designed to address the issue of adherence and to ensure consistent reduction of IOP are currently under development. These delivery systems include contact lenses-releasing glaucoma medications, injectables such as biodegradable micro- and nanoparticles, and surgically implanted systems. These new technologies are aimed at increasing clinical efficacy by offering multiple delivery options and are capable of managing IOP for several months. There is also a desire to have complementary neuroprotective approaches for those who continue to show progression, despite IOP reduction. Many potential neuroprotective agents are not suitable for traditional oral or drop formulations. Their potential is dependent on developing suitable delivery systems that can provide the drugs in a sustained, local manner to the retina and optic nerve. Drug delivery systems have the potential to improve patient adherence, reduce side effects, increase efficacy, and ultimately, preserve sight for glaucoma patients. In this review, we discuss benefits and limitations of the current systems of delivery and application, as well as those on the horizon.

Genetic and Biochemical Characterization of Nectria haematococca Strains with Adhesive and Adhesion-Reduced Macroconidia

A previous study reported the isolation of two mutants (LE1 and LE2) of the plant pathogenic fungus Nectria haematococca (anamorph, Fusarium solani f. sp. cucurbitae) with macroconidia with reduced ability to adhere (Att) to zucchini fruits and polystyrene. The adhesion-reduced-phenotype in LE1 and LE2 macroconidia is temperature sensitive and dependent on the concentration of nutrients. Classical genetic analysis of progeny derived from LE1 identified a mutation in a genetic locus, named Att1. The 90-kDa glycoprotein and macroconidial tip mucilage which were previously associated with the development of adhesion competence in Att macroconidia are specifically associated with macroconidia; neither is produced on microconidia, which are relatively nonadherent. However, macroconidia of both Att and Att strains produce the 90-kDa glycoprotein and the macroconidial tip mucilage.

Orientational relationships and atomic arrangements of GaN nanorods grown on Al2O3 (0001) substrates by using hydride vapor phase epitaxy

Scanning electron microscopy (SEM) images and transmission electron microscopy (TEM) images showed that the one-dimensional GaN nanorods were formed on Al2O3 (0001) substrates by using hydride vapor phase epitaxy without a catalyst. Selected area electron diffraction (SAED) pattern and high-resolution TEM (HRTEM) results showed that GaN nanorods grown on Al2O3 (0001) substrates had crystalline wurzite structures and (0001) preferential orientation. The morphologies of GaN nanorods were affected by the flow rates of the source materials. The orientational relationships between the GaN nanorods and the Al2O3 substrates were (0001)GaN perpendicular (0001) Al2O3 and [0110]GaN perpendicular [1120] Al2O3. Cross-sectional and plan-view atomic arrangements of the fully relaxed interfacial region are described on the basis of the TEM, the SAED pattern, and the HRTEM results.

Retinogeniculate EPSPs recorded intracellularly in the ferret lateral geniculate nucleus in vitro: Role of NMDA receptors

We used an in vitro preparation of the ferret lateral geniculate nucleus (LGN) to examine the role of the NMDA class of excitatory amino acid (EAA) receptors in retinogeniculate transmission. Intracellular recordings revealed that blockade of NMDA receptors both shortened the time course and reduced the amplitude of fast and slow components of excitatory postsynaptic potentials (EPSPs) evoked by optic tract stimulation. The amplitude and width of the EPSPs mediated by NMDA receptors increased as membrane potential was depolarized towards spike threshold. Individual LGN cells were influenced to varying extents by blockade of NMDA receptors; NMDA and non-NMDA receptor blockade together attenuated severely the entire retinogeniculate EPSP. The dependence of all components of retinogeniculate EPSPs (and action potentials) on NMDA receptor activation supports the hypothesis that the NMDA receptor participates in fast (<10 ms) synaptic events underlying conventional retinogeniculate transmission. The voltage dependence of the NMDA receptor-gated conductance suggests strongly that the transmission of retinal information through the LGN is subject to modulation by extraretinal inputs that affect the membrane potential of LGN neurons.

Morphology of deltoid origin and end tendons--a generic model

This study provides a model of the complex deltoid origin and end tendons, as a basis for further anatomical, biomechanical and clinical research. Although the deltoid is used in transpositions with upper limb paralysis, its detailed morphology and segmentation has not been object of much study. Morphologically, the deltoid faces two distinct challenges. It closely envelops a ball joint, and it reduces its width over a short distance from a very wide origin along clavicle, acromion and spina scapula, to an insertion as narrow as the humerus. These challenges necessitate specific morphological tendon adaptations. A qualitative model for these tendons is developed by the stepwise transformation of a unipennate muscle model into a functional deltoid muscle. Each step is the solution to one of the mentioned morphological challenges. The final model is of an end tendon consisting of a continuous succession of bipennate end tendon blades centrally interspaced by unipennate tendon parts. The origin tendon consists of lamellae that interdigitate with the end tendon blades, creating a natural segmentation. The model is illustrated by qualitative dissection results. In addition, in view of a proliferation of terms found in the literature to describe deltoid tendons, tendon concepts are reviewed and the systematic use of the unique and simple terminology of 'origin and end tendons' is proposed.

Kernohan's notch phenomenon demonstrated by diffusion tensor imaging and transcranial magnetic stimulation

Kernohan's notch phenomenon is the ipsilateral hemiplegia caused by compression of the contralateral cerebral peduncle against the tentorial edge by a supratentorial mass. Diffusion tensor imaging (DTI) and transcranial magnetic stimulation (TMS) could be useful for exploring the state of the corticospinal tract (CST). This report attempts to demonstrate Kernohan's notch phenomenon in a patient with subdural haematoma by using DTI and TMS. One patient and six normal control subjects were recruited. The patient showed severe right hemiplegia even though the subdural haematoma was located in the right hemisphere. Brain CT at the time of onset showed right transtentorial herniation, and T2 weighted images at 6 weeks after onset showed a leucomalacic lesion on the left cerebral peduncle. DTI and TMS were performed at 6 weeks after onset. The fractional anisotrophy value of the left midbrain and medulla of the patient was found to be decreased in comparison with that of the control subjects. On fibre tractography for the CST, an interruption was observed in the left midbrain and medulla. The motor evoked potential obtained from the right hand muscle showed delayed latency, low amplitude and a higher excitatory threshold, thus indicating that the CST of the left hemisphere had been damaged. It seems that the CST had been damaged at the left midbrain, although subdural haematoma and transtentorial herniation had occurred in the right hemisphere in this patient. This report demonstrates Kernohan's notch phenomenon in this patient using DTI and TMS.

Evaluation of polymerization in fluoride-containing composite resins

Fluoride-containing restorative materials are frequently utilized to delay or inhibit caries. The quality of the fluoride-containing composite resins was evaluated by testing their microhardness, polymerization shrinkage, thermal expansion coefficient, and surface morphology. Some of them were evaluated in conjunction with the thermocycling process. The microhardness values of the thermocycled specimens were similar to those of the specimens immersed only in distilled water. Among the specimens, Surefil showed the highest (68.6 +/- 1.2 Hv) value. A linear correlation was found between microhardness and the filler content (vol%) of the specimens regardless of their states. Polymerization shrinkage rapidly increased during the light curing, and then it reached a plateau. The shrinkage values increased as the specimens became thicker. In a temperature range of 30 approximately 80 degrees C, the coefficients of thermal expansion of the control specimens ranged between 43 x 10(-6)/ degrees C and 77 x 10(-6)/ degrees C. An inverse correlations were observed between the filler content (vol%) and the coefficient of thermal expansion and between microhardness and the coefficient of thermal expansion of the control specimens. Tetric Ceram showed a perforated or "Swiss-cheese" morphology after thermocycling. It was unique and occurred only in this product.

Photodetection of basal cell carcinoma using methyl 5-aminolaevulinate-induced protoporphyrin IX based on fluorescence image analysis

BACKGROUND

The preferential accumulation of 5-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) in neoplastic cells supports its potential use in the photodetection of porphyrin fluorescence in tumour cells. Hence, epithelial tumours, including basal cell carcinoma (BCC), might be visualized using the fluorescence of selectively accumulated ALA-induced PpIX.

AIM

In this study, we evaluated the clinical efficacy of PpIX fluorescence images using fluorescence image analysis (FIA) to define the lateral border between the tumour and tumour-free areas of facial BCC.

METHODS

FIA was used to define the lateral border between the tumour and tumour-free areas on red fluorescence images induced by the topical application of methyl 5-aminolaevulinate (MAL) ointment. According to the FIA results, 50 tissue samples, obtained from 10 patients with BCC, were divided into three categories: tumour area (n = 10), suspected tumour area (n = 20) and suspected tumour-free area (n = 20). These tissue samples were evaluated by histopathological examination. The FIA tool marked out the PpIX fluorescence image for defining the lateral border between the BCC tumour and tumour-free areas.

RESULTS

The rate of tumour detection from BCC lesions using PpIX fluorescence with the FIA tool showed a sensitivity of 94.1% and specificity of 82.6%.

CONCLUSION

These results suggest that MAL-induced PpIX fluorescence imaging using FIA is quite sensitive and specific for detecting tumour and occult tumour in facial BCC lesions. This method of presurgical in vivo imaging is therefore proposed as a useful tool for defining the lateral border between BCC tumour and tumour-free areas.

Effect of low-level laser treatment after installation of dental titanium implant-immunohistochemical study of RANKL, RANK, OPG: An experimental study in rats

BACKGROUND AND OBJECTIVES

This experiment using an animal experimental model was conducted in order to investigate the effect of low-level laser therapy (LLLT) on the healing of the dental titanium implant.

STUDY DESIGN/MATERIALS AND METHODS

The experimental group received LLLT for a week and the control group did not. Each group consisted of 10 rats. Two rats from the groups were euthenized on the days 1, 3, 7, 14, and 21 of the experiment. The expression of receptor activator of nuclear factor kB ligand (RANKL), osteoprotegerin (OPG), and receptor activator of nuclear factor kB (RANK) were investigated.

RESULTS

The expression of RANKL was observed from the initial stage of the installation of the implant for both the experimental and control groups. However, the degree of expression was higher in the experimental group. The degree of expression of OPG increased remarkably in the experimental group, while in the control group the degree of expression increased only slightly. In the experimental group, the expression of RANK was observed from the first day, but in the control group, it was weakly observed after day 3. The overall expression within the bone was slight on day 7 in the control group, while an active expression was observed in the experimental group. Bone density after installation of dental titanium implant during osseointegration in the experimental group was higher than the control group. The surface and structure of the titanium implant was not damaged by low-level laser (LLL).

CONCLUSIONS

From the above results, the expression of OPG, RANKL, and RANK during the osseointegration of the dental titanium implant was observed within bone tissue. The application of the LLL influenced the expression of OPG, RANKL, and RANK, and resulted in the expansion of metabolic bone activity and increased the activity of bone tissue cells.

Mineral loss from bovine enamel by a 30% hydrogen peroxide solution

This study investigated the effect of a 30% hydrogen peroxide bleaching agent on bovine enamel in terms of mineral loss. Contents of mineral elements both in the teeth and bleaching agent were evaluated to estimate the effect of hydrogen peroxide on teeth. Finely polished non-carious bovine incisors (n = 5) were immersed in a 30% hydrogen peroxide solution for 120 h. The amounts of concentrated elements in the bleaching agent (5 mL) were measured using inductively coupled plasma-atomic emission spectrometer and ion chromatograph. The contents of mineral elements in the teeth were measured using an electron probe microanalyzer. The Ca/P ratio in the bleaching agent was approximately 1.99. The amount of Zn in the bleaching agent was below the detection limit. The total content of mineral elements of the unbleached enamel (90.75 +/- 1.58) was slightly greater than that of the bleached enamel (87.44 +/- 0.77). The Ca/P ratio of the bleached enamel was 2.06. The amount of Ca loss from the bleached enamels after 120 h was similar to the amount of Ca loss from teeth exposed to a soft drink or juice for a few minutes. Therefore, mineral loss caused by the bleaching process may not be a threatening factor to teeth.

Intraocular pressure measurement in mice: a comparison between Goldmann and rebound tonometry

PURPOSE

The development of mouse models of glaucoma requires methods to accurately measure the intraocular pressure (IOP) in this species. The aim of this study was to compare the accuracy of IOP measurements in mice between modified Goldmann and rebound tonometers.

METHODS

IOP was measured either with a modified Goldmann or a rebound tonometer while simultaneously measuring the IOP using invasive manometry in enucleated eyes and in vivo. The level of IOP was controlled hydrostatically. The agreement and correlation between the IOP determined by invasive manometry and by either noninvasive method was evaluated. In addition, the IOP was determined by both noninvasive methods in a cohort of mice with laser-induced ocular hypertension (OHT), and the agreement and correlation between the two tonometry methods were evaluated.

RESULTS

Measured IOP by either noninvasive tonometer correlated well with those recorded simultaneously by invasive manometry (r=0.98 for rebound and r=0.94 for Goldmann). In mice with OHT, the IOP correlation between rebound and modified Goldmann was moderate (r=0.71); the IOP measured by modified Goldmann tonometry was consistently higher than that by rebound by approximately 5 mmHg. However, the relative per cent increases in IOP were similar between the two methods.

CONCLUSION

Both noninvasive methods of IOP measurements in mice are suitable to detect changes in IOP although rebound tonometry correlated better with the invasive manometry readings. The results suggest that the relative, rather than absolute, IOP offers a more reliable means of correlating findings from studies using different tonometers.

Longitudinal fMRI study for locomotor recovery in patients with stroke

The authors investigated bihemispheric motor network reorganization supporting locomotor recovery after stroke over time. They determined longitudinal changes in locomotor function and fMRI in 10 stroke patients at the subacute stage and the chronic stage. The results suggest that the bihemispheric reorganization mechanism underlying locomotor recovery evolved from the ipsilateral (contralesional) primary sensorimotor cortex (SM1) activation at the subacute stage to the contralateral (ipsilesional) SM1 activation at the chronic stage.

Neural Progenitor Cell Transplants into the Developing and Mature Central Nervous System

When developing cell transplant strategies to repair the diseased or injured central nervous system (CNS), it is essential to consider host-graft interactions and how they may influence the outcome of the transplants. Recent studies have demonstrated that transplanted neural progenitor cells (NPCs) can differentiate and integrate morphologically into developing mammalian retinas. Is the ability to differentiate and to undergo structural integration into the CNS unique to specific progenitor cells, or is this plasticity a function of host environment, or both? To address these issues we have used the developing retina of the Brazilian opossum and have compared the structural integration of brain and retinal progenitor cells transplanted into the eyes at different developmental stages. The Brazilian opossum, Monodelphis domestica, is a small pouchless marsupial native to South America. This animal's lack of a pouch and fetal-like nature at birth circumvents the need for in utero surgical procedures, and thus provides an ideal environment in which to study the interactions between developing host tissues and transplanted NPCs. To test whether NPCs affect visual function we transplanted adult hippocampal progenitor cells (AHPCs) into normal, healthy adult rat eyes and performed noninvasive functional recordings. Monitoring of the retina and optic nerve over time by electroretinography and pupillometry revealed no severe perturbation in visual function in the transplant recipient eyes. Taken together, our findings suggest that the age of the host environment can strongly influence NPC differentiation and that transplantation of neural progenitor cells may be a useful strategy aimed at treating neurodegeneration and pathology of the CNS.

Vitreous and retinal amino acid concentrations in experimental central retinal artery occlusion in the primate

PURPOSE

Vitreous and retinal amino-acid concentrations were evaluated in a primate model of central retinal artery occlusion (CRAO) to study the role of glutamate excitotoxicity in acute retinal ischaemia.

METHODS

Unilateral, acute CRAO was produced by temporary clamping of the central retinal artery for 190 min in four elderly rhesus monkeys. Fundus photography, fluorescein angiography, and electroretinogram were performed before and during CRAO, and after unclamping the artery. Vitreous samples were obtained before and after CRAO in both eyes, and analysed for 13 amino-acid concentrations using high-pressure liquid chromatography. The animals were killed 350 min after retinal reperfusion, and the retinal tissue was submitted for amino-acid analysis.

RESULTS

In all four eyes, the macula showed the 'cherry red spot'. The CRAO was confirmed by fluorescein angiography and decreased b-wave on electroretinogram. Retinal histology confirmed ischaemic changes in the inner retina. Changes in all 13 vitreous amino-acid concentrations after CRAO (including glutamate) were not significantly different between study and control eyes (P = 0.09 to 0.82). All retinal amino-acid concentrations (including glutamate) were not significantly different between two eyes (P = 0.07-0.93).

CONCLUSIONS

In the primate model of acute inner retinal ischaemia induced by transient CRAO, we were unable to detect significantly elevated concentrations of vitreous and retinal glutamate. Our primate model has the advantage of closely modelling the CRAO in humans. Further basic and clinical studies are needed to elucidate the role of glutamate excitotoxicity in retinal ischaemia.

The effect of 30% hydrogen peroxide on the color of compomers

The interaction between bleaching agents and recently introduced compomers has several issues that need to be explored, including morphology and mechanical properties. To investigate the effect of 30% hydrogen peroxide, a bleaching agent, on the color of compomers, three compomers (Compoglass F, Elan, and F2000) were polymerized, bleached up to 120 h, and then measured to determine the reflectance of the specimen during the bleaching process. Color differences were evaluated from the reflectance and color values that were represented by CIE L*a*b* values. Compomers stored in distilled water were used as a source of reference. Teeth were also used for comparison. Color differences for both the tested teeth and compomers and different periods of bleaching and soaking in distilled water showed statistically significant difference (p < 0.0001). Among the tested compomers, Compoglass F demonstrated the highest color difference. In addition, the color differences were maximal during the first 24 h. After 24 h, the color difference increased nearly linearly. Compomers stored in both a bleaching agent and distilled water did not exhibit much color difference between them. However, the color difference between teeth and compomers was considerable.

Cysteine metabolism in periportal and perivenous hepatocytes: perivenous cells have greater capacity for glutathione production and taurine synthesis but not for cysteine catabolism

Hepatocyte preparations highly enriched in cells from either the periportal or the perivenous zone of the liver acinus were prepared using a digitonin/collagenase perfusion method. Five enzymes of cysteine metabolism were assayed in both periportal and perivenous preparations. The ratios of periportal to perivenous activity were 0.76, 0.60, 0.81, 1.62, and 1.01 for cysteine dioxygenase, cysteinesulfinate decarboxylase, gamma-glutamylcysteine synthetase, cystathionase, and asparate (cysteinesulfinate) aminotransferase, respectively. Only cysteinesulfinate decarboxylase activity was significantly different between periportal and perivenous cells. In incubations with 2 mmol/L [(35)S]cysteine, total cysteine catabolism ([(35)S]taurine plus [(35)S]sulfate) between periportal and perivenous cells was not different, which is consistent with the observation of similar cysteine dioxygenase activity across the hepatic acinus. Consistent with the lower cysteinesulfinate decarboxylase activity in periportal cells, 16% of the total catabolism of [(35)S]cysteine in periportal cells resulted in taurine synthesis compared to 28% in perivenous cells. A lower rate of [(35)S]glutathione synthesis was observed in periportal cells compared to perivenous cells, but gamma-glutamylcysteine synthetase activity was not significantly different between perivenous and periportal cells. Cysteinesulfnate decarboxylase can be added to the list of enzymes whose activities are markedly enriched in perivenous cells.

Effect of bleaching agents on the fluoride release and microhardness of dental materials

The use of bleaching agents has become a popular procedure for whitening teeth. Recently introduced polyacid-modified composite resins (compomers) have several favorable features, such as improved physical properties and fluoride release. Because these two materials have many possibilities to interact in the oral cavity during dental treatment, it is necessary to understand such interaction. To evaluate the effect of a bleaching agent on dental restoratives, three compomers were photopolymerized and then bleached for 1, 2, 3 and 5 days with the use of 30% hydrogen peroxide. Fluoride release, surface microhardness, and surface modifications were evaluated. It was found that the cumulative fluoride release was found to be linearly correlated to the tested periods of bleaching in all compomers. Among the tested compomers, F2000 showed the highest cumulative fluoride release. Bleached compomers became soft because of surface degradation, so the surface microhardness decreased. F2000 showed an apparent crack formation that was not observed in other compomers. The nearly linear correlation between the filler content and microhardness was found in the control samples. However, the same correlation was not observed after the compomers were stored in a bleaching agent or distilled water.

Effects of hydrogen peroxide on the light reflectance and morphology of bovine enamel

The purpose of this study was to examine the effects of a bleaching agent (30% hydrogen peroxide) on the surface of bovine enamel using a scanning electron microscope and a UV-VIS-NIR spectrophotometer. Five non-carious bovine incisors were bleached for 0, 1, 2 and 3 days using 30% hydrogen peroxide. The light reflectance spectrum was measured using a spectrophotometer with diffuse reflectance mode. Colour values and colour differences in the teeth were evaluated from the reflectance measurements with the CIE L*a*b* colour coordinate system. Surface alterations in the bleached and unbleached teeth were studied using a scanning electron microscope. The change of reflectance in the teeth was related to the change of colour. Most reflectance change occurred within a 1-day bleaching, and this result was confirmed by a CIE L*a*b* colour coordinate system. The colour differences in the bleached teeth were significant enough to be perceived by the observer's eye. The comparison of bleached to unbleached bovine enamel revealed that the bleached surface showed non-uniform slight morphological alterations, and it developed varying degrees of surface porosity. This study indicates that the bleached bovine teeth showed apparent colour differences as well as slight morphological alterations after bleaching.

Post-transcriptional regulation of cysteine dioxygenase in rat liver

Changes in hepatic cysteine dioxygenase (CDO) activity in response to diet play a dominant role in regulation of cysteine catabolism and taurine synthesis. We have conducted several studies of the molecular regulation of CDO activity in rat liver and rat hepatocytes. Compared to levels observed in liver of rats fed a basal 10% casein diet, up to 180-fold higher levels of CDO activity and protein were observed in liver of rats fed diets that contained additional protein, complete amino acid mixture, methionine, or cystine. Neither CDO activity nor CDO protein was induced by excess non-sulfur amino acids alone. Excess sulfur amino acids or protein did not significantly increase the concentration of hepatic CDO mRNA. Preliminary studies indicate that the polysome profile for association of CDO mRNA with polysomes is not altered by an increase in dietary protein level, suggesting that regulation may be posttranslational and possibly involve a decrease in the rate of CDO degradation. In primary cultures of rat hepatocytes, CDO mRNA, protein, and activity all virtually disappeared by 12 to 24 h of culture in standard medium whereas CDO protein, but not CDO mRNA, accumulated markedly between 12 and 24 h in hepatocytes cultured in medium with excess methionine or cyst(e)ine. These observations are also consistent with a limited role of transcriptional or translational regulation of CDO in response to diet.

Rate of visual field loss and long-term visual outcome in primary open-angle glaucoma

PURPOSE

To evaluate long-term visual field outcome in primary open-angle glaucoma.

METHODS

In this retrospective cohort study, 40 eyes of 40 patients with primary open-angle glaucoma with elevated intraocular pressure and a minimum of 8-year longitudinal series of visual fields were plotted with Goldmann perimeter. Eyes with any other ocular disease except cataract were excluded. Manual grid templates were used to quantify the visual fields. Linear regression was performed to estimate the rate of visual field decline. Pertinent clinical factors were evaluated for statistical association with the rate of decline. Long-term clinical outcome including visual acuity, rate of legal blindness, and rate of medical and surgical interventions was also measured.

RESULTS

In the 40 eyes studied, with a mean follow-up of 14 years, the visual field score decreased at the rate of -1.5% per year. Overall, 68% showed significant decrease, and the rate of decrease among these eyes was -2.1% per year. Five eyes became legally blind from glaucoma; the cumulative rate of blindness from glaucoma was 19% at 22 years. Higher intraocular pressure and greater number of antiglaucoma medications on initial presentation were associated with faster and slower deterioration of visual field (compared with the average), respectively.

CONCLUSIONS

With standard glaucoma therapy, the rate of visual field loss in primary open-angle glaucoma is slow. Lower intraocular pressure and more antiglaucoma medications are associated with slower visual field decline. Legal blindness from glaucoma is 19% over a follow-up of 22 years.

Cysteine regulates expression of cysteine dioxygenase and gamma-glutamylcysteine synthetase in cultured rat hepatocytes

Rat hepatocytes cultured for 3 days in basal medium expressed low levels of cysteine dioxygenase (CDO) and high levels of gamma-glutamylcysteine synthetase (GCS). When the medium was supplemented with 2 mmol/l methionine or cysteine, CDO activity and CDO protein increased by >10-fold and CDO mRNA increased by 1.5- or 3.2-fold. In contrast, GCS activity decreased to 51 or 29% of basal, GCS heavy subunit (GCS-HS) protein decreased to 89 or 58% of basal, and GCS mRNA decreased to 79 or 37% of basal for methionine or cysteine supplementation, respectively. Supplementation with cysteine consistently yielded responses of greater magnitude than did supplementation with an equimolar amount of methionine. Addition of propargylglycine to inhibit cystathionine gamma-lyase activity and, hence, cysteine formation from methionine prevented the effects of methionine, but not those of cysteine, on CDO and GCS expression. Addition of buthionine sulfoximine to inhibit GCS, and thus block glutathione synthesis from cysteine, did not alter the ability of methionine or cysteine to increase CDO. GSH concentration was not correlated with changes in either CDO or GCS-HS expression. The effectiveness of cysteine was equivalent to or greater than that of its precursors (S-adenosylmethionine, cystathionine, homocysteine) or metabolites (taurine, sulfate). Taken together, these results suggest that cysteine itself is an important cellular signal for upregulation of CDO and downregulation of GCS.

Cysteine dioxygenase and gamma-glutamylcysteine synthetase activities in primary cultured hepatocytes respond to sulfur amino acid supplementation in a reciprocal manner

Hepatocytes were cultured for 3 days as spheroids (aggregates) or as monolayers in basal medium and in sulfur amino acid-supplemented media. Cultured hepatocytes had low levels of cysteine dioxygenase (CDO) activity and normal levels of gamma-glutamylcysteine synthetase (GCS) and cysteine-sulfinate decarboxylase (CSDC) activities compared to freshly isolated cells. CDO activity increased and GCS activity decreased in a dose-response manner in cells cultured in either methionine- or cysteine-supplemented media. CSDC activity was not significantly affected by methionine supplementation. Changes in CDO and GCS were associated with changes in cysteine catabolism to taurine plus sulfate and in synthesis of glutathione, respectively. These responses are similar to those observed in liver of intact rats fed diets supplemented with sulfur amino acids. A near-maximal response of CDO or GCS activity was observed when the medium contained 1.O mmol/L of methionine plus cyst(e)ine. Changes in CDO and GCS activities did not appear to be mediated by changes in the intracellular glutathione concentration. Cultured hepatocytes offer a useful model for further studies of cysteine metabolism and its regulation in response to sulfur amino acid availability.

Long-term results of eyes with penetrating keratoplasty and glaucoma drainage tube implant

PURPOSE

To present long-term results of eyes with penetrating keratoplasty (PK) and glaucoma tube implant.

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

We retrospectively reviewed medical records of all patients who underwent both PK and glaucoma tube implant (Baerveldt or Ahmed) at the University of Iowa between July of 1988 and December of 1997 (55 eyes).

METHODS

Success of the tube implant or PK was evaluated using Kaplan-Meier survival analysis. Association of relevant clinical factors with glaucoma or corneal graft outcome was evaluated using log-rank test or Cox proportional hazard regression analysis. The factors evaluated were glaucoma and cornea diagnoses; prior, simultaneous, and subsequent surgeries; type of tube implant; relative timing of surgeries; and postsurgical complications.

MAIN OUTCOME MEASURES

Glaucoma outcome was assessed by postoperative intraocular pressure (IOP), number of medications, and need for further glaucoma surgery. Corneal outcome was assessed by graft rejection, failure, and Snellen visual acuity. Surgical procedures before and during the study period, and their complications were evaluated.

RESULTS

The mean preoperative intraocular pressure was 29.8 mmHg with an average of 2.9 medications. At last postoperative follow-up, the mean IOP decreased to 14.3 mmHg with 0.7 medication. The tube implant successfully controlled glaucoma in 45 eyes (82%) at 3 years. More severe postsurgical complications were associated with greater glaucoma failure. Graft rejection occurred in 17 eyes, and 7 of these progressed to failure. Nonimmunologic graft failure occurred in an additional 17 eyes (31%). The remaining 31 eyes (56%) had a clear graft. The corneal grafts remained clear in 70% and 55% of eyes at 2 and 3 years, respectively. Corneal graft failure was associated with glaucoma and cornea diagnoses groups, type of tube implant, and relative timing of the two surgeries. Complications occurred in 23 eyes (42%), and 10 of these were serious.

CONCLUSIONS

A drainage tube implant can successfully control glaucoma in a majority (82%) of keratoplasty eyes at 3 years. However, the success of corneal grafts is low (55%) at 3 years. Postsurgical complications are not uncommon and are associated with poor glaucoma outcome. Other clinical factors are associated with poor graft outcome.

Non-secretion of mutant proteins of the glaucoma gene myocilin in cultured trabecular meshwork cells and in aqueous humor

Until recently, very little was known about the molecular mechanisms responsible for the development of glaucoma, a leading cause of blindness worldwide. Mutations in the glaucoma gene myocilin (MYOC, GLC1A) are associated with elevated intraocular pressure and the development of autosomal dominant juvenile glaucoma and a subset of adult-onset glaucoma. MYOC is expressed in the trabecular meshwork (TM), a tissue responsible for drainage of aqueous humor from the eye, and the tissue involved in elevated intraocular pressure associated with glaucoma. To better understand the role of MYOC in glaucoma pathogenesis, we examined the expression of normal and mutant myocilin in cultured ocular (TM) and non-ocular cells as well as in the aqueous humor of patients with and without MYOC glaucoma. Normal myocilin was secreted from cultured cells, but very little to no myocilin was secreted from cells expressing five different mutant forms of MYOC. In addition, no mutant myocilin was detected in the aqueous humor of patients harboring a nonsense MYOC mutation (Q368X). Co-transfection of cultured cells with normal and mutant myocilin led to suppression of normal myocilin secretion. These studies suggest that MYOC glaucoma is due either to insufficient levels of secreted myocilin or to compromised TM cell function caused by congestion of the TM secretory pathway.

Correlation of automated visual field parameters and peripapillary nerve fiber layer thickness as measured by scanning laser polarimetry

PURPOSE

To correlate Humphrey visual field mean sensitivity and peripapillary nerve fiber layer thickness as measured by scanning laser polarimetry.

METHODS

The authors studied 54 eyes of 34 patients who visited a university-based glaucoma clinic and had undergone scanning laser polarimetry and Humphrey perimetry within 6 months. The study population included normal patients and those with glaucoma, ocular hypertension, and glaucoma suspect. The authors correlated visual field sensitivity with peripapillary nerve fiber thickness, and visual field mean deviation with the average deviation from the normal nerve fiber layer thickness. They also correlated the visual field mean deviation with all available GDx Nerve Fiber Analyzer parameters.

RESULTS

The visual field mean sensitivity and deviation showed a bilinear correlation to peripapillary nerve fiber layer thickness. The visual field mean sensitivity changed little when the nerve fiber layer thickness was greater than 70 microm. The nerve fiber layer thickness below this level was associated with a rapid decrease in the visual field sensitivity. Similarly, the visual field mean deviation was close to 0 dB when the nerve fiber layer was within -10 microm of the normal value; below this thickness, the mean deviation became substantially more negative. There was a large individual variability around the bilinear fit. Of the scanning laser polarimetry parameters, a calculated index, referred to as the number, had the highest correlation with the Humphrey mean deviation.

CONCLUSION

The bilinear correlation and its variability between the scanning laser polarimetry and visual field parameters make it difficult to predict the result of one from the other. In general, the correlation between the two is better when there is a significant visual field defect than when the visual field is close to normal.

Apparent central nervous system depression in infants after the use of topical brimonidine

PURPOSE

To report two cases in which topical brimonidine resulted in apparent central nervous system depression and unresponsiveness in an infant.

METHODS

Review of two patients. An 11-day-old infant became lethargic and apneic after a single drop of brimonidine. These symptoms were reproduced after a second administration of brimonidine. A 5-month-old infant became lethargic and poorly responsive after receiving 1 drop of brimonidine in each eye.

RESULTS

The first patient required admission to the hospital for medical stabilization. He recovered without sequelae. The second patient recovered spontaneously approximately 2.5 hours after administration of brimonidine.

CONCLUSIONS

Topical brimonidine may be associated with central nervous system depression in infants. The use of brimonidine is not recommended in these patients until further data are available.

Orbital melanoma presenting as orbital cellulitis: a clinicopathologic report

Most choroidal melanomas are diagnosed when the tumor is still relatively small and confined to the globe. Rarely, these tumors can escape detection and extend through the sclera. They can reach a large size and create significant orbital inflammation. The authors describe a 71-year-old man with orbital cellulitis secondary to a necrotic choroidal melanoma that invaded the orbit. This tumor had minimal intraocular involvement with a large extrascleral component. On histopathologic analysis, the lesion was best classified as a spindle B melanoma with epithelioid areas (mixed melanoma). The patient was treated with an enucleation and postoperative radiation. This report demonstrates that malignancies in the orbit can present as acute infections. Early suspicion, diagnosis, and treatment of these lesions offer the best chance for survival.

Test-retest variability of blue-on-yellow perimetry is greater than white-on-white perimetry in normal subjects

PURPOSE

To compare long-term fluctuation of blue-on-yellow automated perimetry with white-on-white automated perimetry in normal subjects.

METHODS

White-on-white and blue-on-yellow automated perimetry were performed on a Humphrey Visual Field Analyzer and an Octopus perimeter, both modified for blue-on-yellow perimetry. The study sample consisted of 31 eyes of 31 normal subjects for the Humphrey perimeter and 33 eyes of 33 normal subjects for the Octopus perimeter. After one practice session, each subject completed four testing sessions over a period of 2 to 8 weeks, each separated by at least 1 day. Each testing session consisted of both white-on-white and blue-on-yellow perimetry performed on one eye; the order of the tests was alternated for successive sessions. Long-term fluctuation (expressed as statistical variance) was calculated for each test location. Intersubject variability (expressed as statistical variance) across all subjects was determined for each test location.

RESULTS

On the Humphrey perimeter, the long term fluctuation for blue-on-yellow perimetry (4.07 +/- 3.07 dB2) was significantly greater than that for white-on-white perimetry (1.97 +/- 0.99 dB2; P < .001). Long-term fluctuation increased as a function of eccentricity for both blue-on-yellow and white-on-white perimetry. Short-term fluctuation was significantly greater for blue-on-yellow (0.46 +/- 0.25 dB) than that for white-on-white perimetry (0.29 +/- 0.19 dB; P < .02). Finally, the intersubject variability was significantly greater in blue-on-yellow (13.2 +/- 2.8 dB2) than it was in white-on-white perimetry (4.25 +/- 1.13 dB2; P < .001). Similar results were found with the Octopus perimeter.

CONCLUSIONS

Long-term fluctuation and short-term fluctuation of blue-on-yellow perimetry are greater than those of white-on-white perimetry in normal subjects. The increased long-term fluctuation requires appropriate statistical approaches when evaluating serial change of blue-on-yellow perimetry.

Temporal corneal phacoemulsification in patients with filtered glaucoma

OBJECTIVE

To evaluate the effect of temporal clear corneal phacoemulsification on intraocular pressure (IOP) in eyes that underwent prior trabeculectomy.

DESIGN

Retrospective case-control study.

PATIENTS

Forty consecutive patients who underwent temporal clear corneal phacoemulsification subsequent to trabeculectomy (trabeculectomy-phacoemulsification group) were identified, and 40 control patients who underwent trabeculectomy alone (trabeculectomy group) were matched to the case patients for length of follow-up, age, IOP, number of antiglaucoma medications, number of 5-fluorouracil injections, race, sex, and diagnosis.

MAIN OUTCOME MEASURES

Intraocular pressure before vs 1 year after phacoemulsification in the trabeculectomy-phacoemulsification group compared with IOP in the trabeculectomy group and survival analysis of IOP control after trabeculectomy in the 2 groups.

RESULTS

In the trabeculectomy-phacoemulsification group, IOP 1 year after phacoemulsification was not significantly different from the prephacoemulsification IOP value (P = .65). Kaplan-Meier survival analysis showed that the rates of IOP control 3, 6, and 9 years after trabeculectomy in the trabeculectomy-phacoemulsification group were 80%, 66%, and 44%, respectively; in the trabeculectomy group, these were 79%, 69%, and 55%, respectively. These survival curves were not statistically different (P = .55).

CONCLUSION

Cataract surgery by temporal clear corneal phacoemulsification in eyes with filtering blebs after trabeculectomy does not adversely affect long-term IOP control.

Temporal corneal phacoemulsification in filtered glaucoma patients

PURPOSE

To evaluate the effect of temporal clear corneal phacoemulsification on intraocular pressure (IOP) in eyes that had prior trabeculectomy.

DESIGN

Retrospective case-control study.

PATIENTS

Forty consecutive patients (cases; TRAB-PHACO group) who underwent temporal corneal phacoemulsification subsequent to trabeculectomy were identified. Forty patients (controls; TRAB group) who had trabeculectomy alone were matched to the cases for length of follow-up, age, IOP, number of anti-glaucoma medications, number of 5-fluorouracil (5-FU) injections, race, sex and diagnosis.

MAIN OUTCOME MEASURES

Comparison of IOP before and one year after phacoemulsification in the TRAB-PHACO group, and comparison with the TRAB group. Survival analysis of IOP control after trabeculectomy in the TRAB-PHACO and TRAB groups.

RESULTS

In the TRAB-PHACO group, IOP one year after phacoemulsification was not significantly different from the pre-phacoemulsification IOP value (p = 0.65). Kaplan-Meier survival analysis showed that the rates of IOP control at 3, 6 and 9 years after trabeculectomy in the TRAB-PHACO group were 80%, 66% and 44%; in the TRAB group these were 79%, 69% and 55%. These survival curves were not statistically different (p = 0.55).

CONCLUSIONS

Cataract surgery by temporal clear corneal phacoemulsification in eyes with filtering blebs after trabeculectomy does not adversely affect long term IOP control.