Modeling of grid cell activity demonstrates in vivo entorhinal 'look-ahead' properties.

Recent in vivo data show ensemble activity in medial entorhinal neurons that demonstrates 'look-ahead' activity, decoding spatially to reward locations ahead of a rat deliberating at a choice point while performing a cued, appetitive T-Maze task. To model this experiment's look-ahead results, we adapted previous work that produced a model where scans along equally probable directions activated place cells, associated reward cells, grid cells, and persistent spiking cells along those trajectories. Such look-ahead activity may be a function of animals performing scans to reduce ambiguity while making decisions. In our updated model, look-ahead scans at the choice point can activate goal-associated reward and place cells, which indicate the direction the virtual rat should turn at the choice point. Hebbian associations between stimulus and reward cell layers are learned during training trials, and the reward and place layers are then used during testing to retrieve goal-associated cells based on cue presentation. This system creates representations of location and associated reward information based on only two inputs of heading and speed information which activate grid cell and place cell layers. We present spatial and temporal decoding of grid cell ensembles as rats are tested with perfect and imperfect stimuli. Here, the virtual rat reliably learns goal locations through training sessions and performs both biased and unbiased look-ahead scans at the choice point. Spatial and temporal decoding of simulated medial entorhinal activity indicates that ensembles are representing forward reward locations when the animal deliberates at the choice point, emulating in vivo results.

Two-site phacotrabeculectomy versus bimanual microincision cataract surgery combined with trabeculectomy.

PURPOSE: To compare the results of two-site phacotrabeculectomy with microincision cataract surgery (MICS) and trabeculectomy. METHODS: Fifty-eight eyes with coexisting cataract and glaucoma were randomly assigned to have a trabeculectomy in a superior quadrant combined with phacoemulsification and intraocular lens (IOL) implantation through temporal clear corneal incision (two-site phacotrabeculectomy group), or a trabeculectomy in a superior quadrant combined with MICS followed by IOL implantation from the trabeculectomy incision (MICS + trabeculectomy group). The main outcome measures were preoperative and postoperative intraocular pressure (IOP), number of glaucoma medications, best-corrected visual acuity (BCVA), and complications. Follow-up was period was 12 months. RESULTS: Twenty-eight two-site phacotrabeculectomies and 30 MICS + trabeculectomies were performed. Mean age of the subjects was 67.4 years. Mean preoperative IOP was 24.6+/-5.7 mmHg in the two-site phacotrabeculectomy group and 23.7+/-5.5 mmHg in the MICS + trabeculectomy group (p=0.52). At 12 months postoperatively mean IOP was 14.5+/-3.0 and 14.3+/-3.4 mmHg in two-site phacotrabeculectomy and MICS + trabeculectomy groups, respectively (p=0.8). Preoperative and postoperative glaucoma medication numbers were similar and mean number of glaucoma medications decreased in both groups after the surgery (p<0.05). BCVA improved in both groups. Twenty-six of 28 eyes (92%) in the two-site + trabeculectomy group and 27 of 30 (90%) in the MICS + trabeculectomy group had clinically apparent filtering blebs at 12 months (p=0.71). Postoperative complications were comparable. CONCLUSIONS: MICS + trabeculectomy provided 1 year IOP control comparable to that with two-site phacotrabeculectomy with similar amount of complications and similar final BCVA.

Clustering of invasive Aspergillus ustus eye infections in a tertiary care hospital: a molecular epidemiologic study of an uncommon species.

Aspergillus infections are being increasingly recognized as an important cause of morbidity and blindness. We report here the first cluster of Aspergillus ustus endophthalmitis cases which occurred in a large tertiary care hospital during the period October 2003 to June 2004. In three of the cases, the patients required enucleation following cataract surgery, while the fourth involved a fatal infection in a pediatric patient hospitalized for osteopetrosis. Patient charts from the four cases were reviewed retrospectively and indicated that postoperative signs of fungal endophthalmitis developed in the patients 1-11 weeks after surgery. The molecular characterization of the isolates and their epidemiological relatedness were evaluated by Random Amplification of Polymorphic DNA (RAPD). A source investigation of this mini outbreak was performed by environmental sampling, but no isolates of A. ustus were recovered from these studies. All A. ustus strains isolated from three patients with fungal endophthalmitis had the same RAPD pattern suggesting a common source. The strain from the pediatric patient differed from the ophthalmic isolates in five electrophoretic loci. The latter was included solely as an outbreak, unrelated control to evaluate the discriminatory power of the molecular typing method employed in the analysis of the ophthalmic strains. These cases illustrate the potential for uncommon species like A. ustus to cause high morbidity and mortality in some clinical settings. Aspergillus ustus endophthalmitis is a serious and devastating complication of ocular surgery. It is unknown whether ongoing hospital construction may have contributed to this cluster of cases. Random amplification of polymorphic DNA may give valuable clues about the clonality of A. ustus strains.

Adherence of Candida albicans to denture base acrylics and silicone-based resilient liner materials with different surface finishes.

This study evaluated the surface roughness and Candida albicans adherence on denture base acrylic resins and silicone-based resilient liners with different surface finishes. Four commercial denture base acrylic resins (three heat polymerized and one room temperature polymerized) and five silicone-based liner materials (two heat polymerized and three room temperature polymerized) (10 x 10 x 2 mm) were tested in this study. The materials were processed against glass or plaster or finished with a tungsten carbide bur. Surface roughness measurements were made using a profilometer with an optical scanner probe. All specimens were ultrasonically cleaned in water for 15 s, autoclave sterilized, and contaminated with C. albicans solution for adherence assay evaluation. The materials processed against the glass surface showed significantly lower surface roughness values (0.11 +/- 0.1-1.66 +/- 1.1 microm) than those of the materials processed against the dental plaster (2.61 +/- 0.2-6.12 +/- 2.8 microm) or roughening with a bur (1.48 +/- 0.2-7.05 +/- 1.2 microm; p < 0.05, one- or two-way analysis of variance). Also, the materials processed against the glass surface showed lower C. albicans adhesion (mean ranks 120.36) than those of the materials processed against the dental plaster (mean ranks 139.77) or roughening with a bur (mean ranks 143.06), but the differences were not statistically significant (p > 0.05, Kruskal-Wallis and Mann-Whitney). In all types of surface finishes, C. albicans adhesion on denture base acrylics was significantly less (mean ranks 90.18-90.40) than those of silicone liners (mean ranks 119.38-205.18; p < 0.01, Kruskal-Wallis).

A probable outbreak of toxoplasmosis among boarding school students in Turkey.

In total, 171 students from a boarding school in Izmir, Turkey, with mild and non-specific symptoms of toxoplasmosis, were screened during September-October 2002. All 171 students were seropositive for Toxoplasma gondii IgG and IgM. Of 43 students tested, 40 (93%) had low IgG avidity. None showed evidence of ophthalmic involvement. The data suggest that T. gondii may spread rapidly in close living conditions, possibly following exposure to cat litter. This is the largest recent outbreak of toxoplamosis described in the medical literature.

Scedosporium apiospermum keratitis treated with itraconazole.

Mycotic keratitis usually occurs in conjunction with trauma to the cornea. Scedosporium apiospermum, a dematiaceous fungus linked to the teleomorph Pseudallescheria boydii is not a common agent of mycotic keratitis. A 22-year old male patient with mycotic keratitis due to S. apiospermum is presented. In in vitro susceptibility testing, the isolate showed resistance against amphotericin B (minimum inhibitory concentration [MIC] 16 microg ml(-1)) but was susceptible to itraconazole (ITC) and fluconazole with MICs of 0.125 microg ml(-1) and 4 microg ml(-1), respectively. The patient was cured clinically after ITC treatment and surgical intervention. Azoles may be superior for eliminating S. apiospermum from infected ocular sites.

Craniofacial anomalies, ocular findings, pigmented nevi, camptodactyly, and skeletal changes: a possible new autosomal recessive disorder.

A 20-year-old male is described with craniofacial anomalies, ocular findings, pigmented nevi, camptodactyly and skeletal changes. On the basis of the clinical and radiological differences with syndromes previously described we classify the present case as a new faciothoracoskeletal syndrome. Parental consanguinity supports autosomal recessive inheritance.