Importance of two-dimensional gaze analyses in the assessment of reading performance in patients with retinitis pigmentosa.

The causes of reading difficulties in people with peripheral visual field loss are not fully understood. We conducted a two-dimensional gaze analysis on eye movements during reading in patients with retinitis pigmentosa to investigate the causes of reading difficulties in relation to the central visual field using a binocular eye mark recorder (EMR-9). Twenty-seven patients with retinitis pigmentosa whose central visual field narrowed to ≤ 20° using Goldmann kinetic perimetry (I/4 target) and this present study included eight healthy participants. The participants' visual acuities were corrected to better than +0.4 logMAR. Correlations and multivariate regression analyses were investigated between the number of letters read correctly, the I/4 central visual field, V/4 perifoveal and peripheral visual field, and visual acuity. Multivariate regression analysis revealed that all these parameters played almost equal roles in the number of letters read correctly. In the two-dimensional gaze analysis, the task performance time of patients during reading increased as the I/4 central visual field narrowed. The task performance time was more clearly correlated with the rotation saccade (r = 0.428, p <0.05) and the distance of the vertical direction (ΣY) of eye movements (r = 0.624, p < 0.01), but not with regressive saccade and the distance of the horizontal direction (ΣX). Visual acuity was correlated with the task performance time (-0.436, <0.05) but not with eye movement directionality. Reading difficulties in patients with retinitis pigmentosa result from impaired eye movement directionality. Understanding eye measurements for people with tunnel vision required a two-dimensional gaze analysis. The two-dimensional gaze analysis also showed that the involvement of the perifoveal and peripheral visual fields, visual acuity, and I/4 central visual field was important for reading in people with tunnel vision.

fMRI evidence of improved visual function in patients with progressive retinitis pigmentosa by eye-movement training.

To evaluate changes in the visual processing of patients with progressive retinitis pigmentosa (RP) who acquired improved reading capability by eye-movement training (EMT), we performed functional magnetic resonance imaging (fMRI) before and after EMT. Six patients with bilateral concentric contraction caused by pigmentary degeneration of the retina and 6 normal volunteers were recruited. Patients were given EMT for 5 min every day for 8-10 months. fMRI data were acquired on a 3.0-Tesla scanner while subjects were performing reading tasks. In separate experiments (before fMRI scanning), visual performances for readings were measured by the number of letters read correctly in 5 min. Before EMT, activation areas of the primary visual cortex of patients were 48.8% of those of the controls. The number of letters read correctly in 5 min was 36.6% of those by the normal volunteers. After EMT, the activation areas of patients were not changed or slightly decreased; however, reading performance increased in 5 of 6 patients, which was 46.6% of that of the normal volunteers (p< 0.05). After EMT, increased activity was observed in the frontal eye fields (FEFs) of all patients; however, increases in the activity of the parietal eye fields (PEFs) were observed only in patients who showed greater improvement in reading capability. The improvement in reading ability of the patients after EMT is regarded as an effect of the increased activity of FEF and PEF, which play important roles in attention and working memory as well as the regulation of eye movements.

The synthetic and biological studies of discorhabdins and related compounds.

Various analogues of the marine alkaloids, discorhabdins, have been synthesized. The strategy contains spirocyclization with phenyliodine(III) bis(trifluoroacetate) (PIFA), oxidative fragmentation of the ß-amino alcohols with the hypervalent iodine reagent C(6)F(5)I(OCOCF(3))(2), the detosylation and dehydrogenation reaction of the pyrroloiminoquinone unit in the presence of a catalytic amount of NaN(3) and the bridged ether synthesis with HBr-AcOH as the key reactions. All the synthesized compounds were evaluated by in vitro MTT assay for cytotoxic activity against the human colon cancer cell line HCT-116. Furthermore, the discorhabdin A oxa analogues were also evaluated against four kinds of tumor model cells, a human colon cancer cell line (WiDr), a human prostate cancer cell line (DU-145) and murine leukemia cell lines (P388 and L1210). For the identification of the target, discorhabdin A and the discorhabdin A oxa analogue were evaluated by an HCC panel assay. In the test, discorhabdins could have a novel mode of action with the tumor cells.

Synthesis of antitumor marine alkaloid discorhabdin A oxa analogues.

Discorhabdin A (1) exhibits a strong cytotoxic activity in vitro, but it is difficult to synthesize and handle due to the instability of its highly strained N,S-acetal structure. We then designed the analogues of discorhabdin A which also have strong cytotoxic activity and stability. The synthesis and examination of the biological activity of various types of stable discorhabdin A oxa analogues (2) were achieved.

The efficient direct synthesis of N,O-acetal compounds as key intermediates of discorhabdin A: oxidative fragmentation reaction of alpha-amino acids or beta-amino alcohols by using hypervalent iodine(III) reagents.

Hypervalent iodine(III) reagents are readily available, easy to handle, and have a low toxicity and similar reactivities to those of heavy metal reagents, and hence they are used for various oxidative reactions. The oxidative cleavage of alkynes or carbonyl compounds by using bis(trifluoroacetoxy)iodo(III) pentafluorobenzene (C(6)F(5)I(OCOCF(3))(2)) has been reported. Herein, the efficient direct synthesis of N,O-acetal compounds as key intermediates of discorhabdin A, by the oxidative fragmentation reaction of alpha-amino acids or beta-amino alcohols by using C(6)F(5)I(OCOCF(3))(2), is described.

The novel and efficient direct synthesis of N,O-acetal compounds using a hypervalent iodine(III) reagent: an improved synthetic method for a key intermediate of discorhabdins.

The use of hypervalent iodine(III) reagents allowed us to develop the novel and efficient direct synthesis of N,O-acetal compounds via the oxidative fragmentation reaction of alpha-amino acids or alpha-amino alcohols; furthermore, we succeeded in developing an improved synthesis of the key intermediate of discorhabdins.

Heat shock protein 90 as an endogenous protein enhancer of inducible nitric-oxide synthase.

Nitric oxide (NO) generated by inducible NO synthase (iNOS) plays crucial roles in inflammation and host defense. With an intrinsically bound calmodulin, iNOS is fully active once expressed in cells. Thus, regulation of NO production from iNOS was thought to primarily occur at the enzyme transcriptional level. Here we show that NO synthesis from iNOS can be profoundly modulated by heat shock protein 90 (hsp90) through protein-protein interaction. To study whether hsp90 affects iNOS function, recombinant murine iNOS was purified from an Escherichia coli expression system by affinity chromatography. Hsp90, at physiological concentrations (10-500 nm), dose-dependently increased iNOS activity. This was a specific effect because neither denatured hsp90 nor irrelevant bovine serum albumin affected iNOS function. Overexpression of hsp90 enhanced NO production in iNOS-transfected cells. On the contrary, hsp90 inhibition dramatically decreased NO formation from iNOS in macrophages. Co-immunoprecipitation studies showed that hsp90 and iNOS associated with each other in cells. Overexpression of iNOS resulted in NO-mediated cellular injury. Hsp90 inhibition markedly attenuated NO formation and prevented cellular injury. These results demonstrated that hsp90 is an allosteric enhancer of iNOS. iNOS is coupled with hsp90 in cells, and this coupling facilitates NO synthesis. In light of the critical role of hsp90 in iNOS-mediated cytotoxic action, modulating the interaction between hsp90 and iNOS may be a new approach to intervene inflammation and immune response.