Formation of an intermediate compound with a B12H12 cluster: experimental and theoretical studies on magnesium borohydride Mg(BH4)2.

Experimental and theoretical studies on Mg(BH4)2 were carried out from the viewpoint of the formation of the intermediate compound MgB12H12 with B12H12 cluster. The full dehydriding and partial rehydriding reactions of Mg(BH4)2 occurred according to the following multistep reaction: Mg(BH4)2 -->1/6MgB12H12 + 5/6MgH2 + 13/6H2 <--> MgH2 + 2B + 3H2 <--> Mg + 2B + 4H2. The dehydriding reaction of Mg(BH4)2 starts at approximately 520 K, and 14.4 mass% of hydrogen is released upon heating to 800 K. Furthermore, 6.1 mass% of hydrogen can be rehydrided through the formation of MgB12H12. The mechanism for the formation of MgB12H12 under the present rehydriding condition is also discussed.

Clinicopathological correlation of polypoidal choroidal vasculopathy revealed by ultrastructural study.

AIMS: To describe the clinical and histopathological findings in a patient with polypoidal choroidal vasculopathy. METHODS: A 76 year old Japanese man had a discrete, orange-red lesion of 1 disc diameter in the macula, with the fluorescein and indocyanine green angiographic and optical coherence tomographic findings compatible with polypoidal choroidal vasculopathy. He underwent a surgical removal of the macular lesion, followed by light and electron microscopic examinations. RESULTS: The histopathological examination revealed that the specimen consisted of degenerated retinal pigment epithelium-Bruch's membrane-choriocapillaris complex and inner choroid. A tortuous, unusually dilated venule was present adjacent to an arteriole with marked sclerotic changes, appearing to form arteriovenous crossing. These vessels seemed to represent native inner choroidal vessels, and had haemorrhage per diapedesis. Blood cells and fibrin filled the lumina of the vessels and accumulated in the extravascular spaces, indicating vascular stasis. CONCLUSION: Hyperpermeability and haemorrhage due to stasis of a dilated venule and an arteriole involved by sclerosis at the site where they cross in the inner choroid might cause oedema and degeneration of the tissue. Voluminous accumulation of blood cells and fibrin might generate elevation of tissue pressure sufficient to displace the weakened lesion anteriorly. The result suggests that the polypoidal vessels in this case represent abnormality in the inner choroidal vasculature.

Optical coherence tomography of superior segmental optic hypoplasia.

AIM: To describe optical coherence tomography (OCT) images of superior segmental optic hypoplasia (SSOH). METHODS: Five patients (two men and three women, ages 10-45 years) presented with ophthalmoscopic features and visual field defects of SSOH. All affected eyes had good visual acuity and inferior altitudinal or inferonasal visual field loss. The mothers of three patients had type 1 diabetes mellitus. OCT (Humphrey Instrument, CA, USA) was used to evaluate tomographically the optic disc and peripapillary retina of both eyes of each patient. Control data on retinal nerve fibre layer (RNFL) thickness were obtained from 13 normal eyes, one eye each from 13 normal subjects. RESULTS: Seven of 10 eyes in patients had SSOH. Scans in the vertical meridian through the affected optic discs showed a superior defect of the optic disc associated with decreased RNFL thickness and, in some cases, an abnormal extension of a complex of retinal pigment epithelium and choroid over the edge of the lamina cribrosa. Circular scans around the seven optic discs revealed various decreases of peripapillary RNFL thickness in the superior quadrants. Vertical scans through the fovea also showed superior thinning of RNFL. Quantitative assessment of the peripapillary RNFL thickness revealed significantly decreased values in the superior quadrants compared to normal eyes. CONCLUSIONS: OCT provides a new tool for quantitative evaluation of optic nerve hypoplasia as exemplified in this study of SSOH. It can reveal minimal degrees of segmental hypoplasia previously undetected.

Photoreceptor cell differentiation in retinoblastoma demonstrated by a new immunohistochemical marker mucin-like glycoprotein associated with photoreceptor cells (MLGAPC).

AIMS: For further understanding of specific differentiation in retinoblastoma, we studied the expression of newly detected mucin-like glycoprotein associated with photoreceptor cells (MLGAPC), which is specific for photoreceptor cells of retina and analogous to interphotoreceptor matrix proteoglycan-1 (IMPG1). METHODS AND RESULTS: Surgically enucleated retinoblastomas (n=21; undifferentiated type, n=15, differentiated type, n=6) were immunohistochemically studied with a polyclonal antibody against MLGAPC, and 17/21 cases (81%) showed positive staining of tumour cells. We classified various staining patterns and structures into four groups: type 1 showing a granular intracellular scattered staining pattern with round small cells; type 2 showing a reticular staining pattern between spindle-shaped tumour cells; type 3 showing radiating staining from the centre of Homer-Wright rosettes; type 4 showing ring-shaped, radiating and granular staining associated with Flexner-Wintersteiner rosettes. Eleven of 15 undifferentiated retinoblastomas (73%) showed type 1 or 2, and all the six differentiated cases showed type 3 or 4. Image analysis of immunostaining revealed an increase in MLGAPC-positive area from 0.48% in undifferentiated cases to 1.60% in differentiated cases, and a negative correlation was shown between mitotic frequency and MLGAPC-positive area. CONCLUSIONS: This study proved MLGAPC as a valuable marker of retinoblastoma, and that photoreceptor differentiation takes place even in 'undifferentiated' retinoblastoma.

Skeletal muscle regeneration associated with the stroma reaction during tumor invasion in the rat tongue.

This study was aimed to demonstrate the regeneration of skeletal muscle fibers in the stroma reaction during tumor invasion, using the rat model of tongue carcinoma. By oral administration of 4-nitroquinoline N-oxide, squamous cell carcinoma (SCC) appeared in the epithelium, and deeply invaded the muscular layer, inducing the stroma reaction around the tumor. Regenerating muscle fibers, characterized by the immature profiles of sparse myofibrils, centrally disposed multi-nuclei, and abundant mitochondria, were extended from the surrounding normal muscles into the stroma. By immunohistochemistry, some of them expressed BF-45, a marker for an early stage of myodifferentiation, similar to the regenerating muscle fibers in the bupivacaine hydrochloride-induced injury. They were closely associated with the stromal components such as ED-1-positive macrophages, alpha-smooth muscle actin-positive myofibroblasts, and factor VIII-related antigen-positive vascular endothelial cells, suggesting the roles of their interactions in muscle regeneration. Immature muscle fibers were usually devoid of acetylcholinesterase-positive endplates on them, but some were reinnervated by the terminal axons. The present results indicate that skeletal muscle regeneration is induced in association with the stroma reaction during SCC invasion in the tongue.

Initial stages of posterior vitreous detachment in healthy eyes of older persons evaluated by optical coherence tomography.

OBJECTIVE: To promote understanding of the development of posterior vitreous detachment (PVD) in healthy eyes using optical coherence tomography (OCT). METHODS: We studied 209 eyes of 209 healthy volunteers (165 men and 44 women; mean age, 52.3 years [range, 31-74 years]). In addition to biomicroscopy and ophthalmoscopy, OCT was performed to obtain high-resolution cross-sectional images of the vitreoretinal interface in the posterior fundus. RESULTS: The condition of the posterior vitreoretinal interface was classified as 1 of 5 stages, according to biomicroscopic findings and OCT images relative to discrete linear signals indicating a detached posterior vitreous face: stage 0, no PVD (61 eyes [29.2%]); stage 1, incomplete perifoveal PVD in up to 3 quadrants (100 eyes [47.8%]); stage 2, incomplete perifoveal PVD in all quadrants, with residual attachment to the fovea and optic disc (26 eyes [12.4%]); stage 3, incomplete PVD over the posterior pole, with residual attachment to the optic disc (4 eyes [1.9%]); or stage 4, complete PVD identified with biomicroscopy, but not with OCT because of instrument limitations (18 eyes [8.6%]). Stage 1, 2, and 3 incomplete PVD without subjective symptoms was not recognizable on contact lens biomicroscopy. There was a significant age-related progression in the condition of the vitreoretinal interface from stage 0 to stage 4. The superior quadrant was usually the initial site of incomplete PVD. CONCLUSIONS: Optical coherence tomography demonstrates that healthy human eyes have incomplete or partial PVD beginning as early as the fourth decade of life. Age-related PVD occurs initially as a focal detachment in the perifovea of 1 quadrant, with persistent attachment to the fovea and optic nerve head, with a predilection for the superior quadrant. It extends its range slowly for years and eventually results in complete PVD, associated with release of vitreopapillary adhesion.

Isolation and characterization of galectins in the mammalian retina.

PURPOSE: Previous studies have suggested that galectins may be involved in retinal adhesion and photoreceptor cell survival. To elucidate the underlying mechanisms, the authors isolated retinal galectins, determined their types and distributions, and investigated the validity of the hypothesis, using rat models. METHODS: An antibody was prepared against a bovine retinal lectin that was isolated by use of a lactose-agarose column. cDNA of the lectin was isolated by screening of a bovine retinal cDNA library, using the antibody, and then was sequenced. The cDNAs of rat retinal galectins were also isolated by means of polymerase chain reaction and used to produce an antibody against recombinant galectin-3. Using the described antibodies, the authors examined the distributions of galectins in bovine and rat retinas, morphologic changes of rat retinas induced by the antibodies, and distributional changes of galectins in constant-light-exposed rat retinas. RESULTS: The cDNAs of bovine galectin-1, rat galectin-1, and rat galectin-3 were isolated. Galectin-1 was found in various regions, including the retinal pigment epithelium, outer limiting membrane, and outer plexiform layer in bovine and rat retinas. Galectin-3 was increasingly detected in the cytoplasm of Müller cells after constant light exposure after an increase in its transcript. Retinal detachment and vacuolation of the outer plexiform layer were induced in rat eyes by intravitreous injection of the anti-galectin-1 antibody. CONCLUSIONS: Galectin-1 may be involved in adhesion of the photoreceptor and outer plexiform layers by interacting with glycoconjugates with beta-galactoside residues in the interphotoreceptor matrix and synaptic cleft matrix. Galectin-3 may increase in Müller cells of a degenerative rat retina, probably through endogenous anti-apoptosis.

Mechanism of growth-inhibitory effect of cisplatin on human pancreatic cancer cells and status of p53 gene.

Pancreatic cancer is a devastating malignant tumor in humans and the development of new modalities of treatment is needed. We studied the mechanism of the growth-inhibitory effect of cisplatin (CDDP) on human pancreatic cancer cells in connection with the status of the p53 gene and expression of the bcl-2 family. COLO-357 cells with wild-type p53 gene and T3M4, Panc-1 and AsPC-1 cells with mutant-p53 gene were used. Growth of these cells was inhibited by CDDP in a dose-dependent manner in both serum-deprived and serum-supplemented conditions. CDDP induced apoptosis of COLO-357 and T3M4 cells in the serum-supplemented condition, whereas necrosis of these cells was induced by CDDP at high concentrations in the serum-deprived condition. Although expression of bax mRNA and its protein product were enhanced, while bcl-2 protein was decreased by CDDP in COLO-357 cells, expression of mRNA of the bcl-2 family and protein product were not influenced by CDDP in T3M4 cells. Increased expression of bax and reduced expression of bcl-2 are involved in the growth-inhibitory effect of CDDP on pancreatic cancer cells with wild-type p53 gene.

Postsurgical evaluation of idiopathic vitreomacular traction syndrome by optical coherence tomography.

PURPOSE: To report a case of idiopathic vitreomacular traction syndrome with preoperative and postoperative evaluation by optical coherence tomography. DESIGN: Interventional case report. METHODS: A 62-year-old woman presented with blurred vision in the left eye because of idiopathic vitreomacular traction syndrome, and she underwent a pars plana vitrectomy. Optical coherence tomography was performed before and after surgery. RESULTS: Preoperative optical coherence tomography, right eye, revealed residual adhesion of incomplete posterior vitreous detachment and edematous, thickened outer retina in the macula. A successful vitrectomy relieved vitreoretinal traction with nearly complete resolution of cystoid macular edema within 1 month after surgery, followed in subsequent months by gradual foveal depression resembling a lamellar macular hole. Resolution of subretinal serous fluid was delayed with complete disappearance, some 12 months after surgery, which correlated with a gradual improvement in visual acuity. CONCLUSION: Optical coherence tomography provides a sensitive anatomical evaluation of vitreomacular traction syndrome. Reorganization of retinal tissue after surgical intervention for vitreoretinal traction may be slower than is apparent from conventional examinations.

Retinopathy associated with Machado--Joseph disease (spinocerebellar ataxia 3) with CAG trinucleotide repeat expansion.

PURPOSE: To report characteristic atrophic maculopathy in a patient with Machado--Joseph disease (spinocerebellar ataxia 3) caused by trinucleotide repeat expansion of the relevant gene. METHODS: Case report. RESULTS: A 64-year-old Japanese man had suffered from slurred speech and gait disturbance since 57 years of age. Cerebellar ataxia, extensor plantar response, and other neurological signs were compatible with features of Machado--Joseph disease. Magnetic resonance imaging showed atrophies of cerebellum and cerebral cortex. Family history suggested an autosomal dominant inheritance of the disease. The patient presented with gaze-evoked nystagmus and limitations of eye movement in all directions. Ophthalmoscopy and fluorescein angiogram revealed symmetric changes in the posterior fundi, which consisted of patchy atrophies at the level of the retinal pigment epithelium. Scotopic electroretinogram showed no abnormalities with normal oscillatory potentials. Polymerase chain reaction analysis of the Machado--Joseph disease gene identified a heterozygous trinucleotide (CAG) repeat expansion. CONCLUSION: This case illustrates a rare association of atrophic maculopathy and external ophthalmoplegia in Machado--Joseph disease, contrasted with the common occurrence of retinal degeneration in spinocerebellar ataxia 7. Dystrophic changes in the retinal pigment epithelium have rarely been described but may be one of the characteristic complications of Machado--Joseph disease.

Cytochrome P450 1B1 gene mutations in Japanese patients with primary congenital glaucoma(1).

PURPOSE: To report a novel missense mutation and DNA polymorphism of the CYP1B1gene in Japanese patients with primary congenital glaucoma. METHODS: A series of 11 unrelated patients with primary congenital glaucoma was examined. Patients were followed in the Kagoshima University Hospital between 1979 and 1998. DNA was extracted from leukocytes of the patients, their families, and unrelated healthy individuals. Amplicons spanning the coding regions of the CYP1B1 gene were examined by direct sequencing and enzyme-restriction detection. RESULTS: In the 11 unrelated patients, besides the previously reported insertional mutation (1620 ins G), a novel missense mutation was identified at codons 444 to replace arginine with glutamine (R444Q) in one patient. The novel missense mutation cosegregated in the relevant family as an autosomal recessive pattern and was not found in other patients or control individuals. In addition, five polymorphic sites were found at codons 48, 119, 330, 432, and 449. These polymorphic alleles did not cosegregate with the disease, and they were found in healthy individuals as well. CONCLUSIONS: Approximately 20% of Japanese patients with primary congenital glaucoma may be affected by mutations in the CYP1B1 gene. Further studies are justified to explore whether a relationship exists between the phenotypic expressivity of the disease and the type of mutation.

Genetic association of manganese superoxide dismutase with exudative age-related macular degeneration.

PURPOSE: To elucidate whether any polymorphic genes for xenobiotic-metabolizing and antioxidant enzymes are associated with the development of exudative age-related macular degeneration. METHODS: A hospital-based case-control study was performed on a consecutive series of 102 Japanese patients with the exudative form of age-related macular degeneration who were recruited between 1993 and 1998 in the Kagoshima University Hospital. Controls were 200 systemically healthy individuals who had no senescent ocular disorders and were over 50 years of age. There was no evidence of age-related macular degeneration in the 200 controls. Genomic DNA from peripheral bloods was examined using polymerase chain reaction and defined for the genetic polymorphisms of cytochrome P-450 1A1, glutathione S-transferases, microsomal epoxide hydrolase, and manganese superoxide dismutase. RESULTS: We found a significant association of manganese superoxide dismutase gene polymorphism, valine/alanine polymorphism at the targeting sequence of the enzyme, with age-related macular degeneration. The patients had an increased frequency of alanine allele and alanine/alanine genotype (odds ratio = 10.14, 95% confidence interval = 4.84 to 2.13; P =.0005 after Bonferroni correction). We also observed a weak association of microsomal epoxide hydrolase exon-3 polymorphism with age-related macular degeneration (odds ratio = 2.20, 95% confidence interval = 4. 02 to 1.20; P =.020 after Bonferroni correction). Cytochrome P-450 1A1, glutathione S-transferases, and microsomal epoxide hydrolase exon-4 were polymorphic, but their genotype frequency distributions did not show a statistically significant difference between the patients and controls. CONCLUSIONS: The results suggest that manganese superoxide dismutase gene polymorphism is associated with exudative age-related macular degeneration. Microsomal epoxide hydrolase is another enzyme that may be associated with the disease. The exudative form of age-related macular degeneration may have genetic risk factors against oxidative stress and/or effects of xenobiotics. Further association studies in other polymorphic genes for xenobiotic-metabolizing enzymes are needed to elucidate the environmental-genetic interaction in the underlying cause of age-related macular degeneration.

Choroideremia associated with subretinal neovascular membrane.

PURPOSE: To report two Japanese patients with choroideremia, one male and one heterozygous female, who developed subretinal neovascular membrane and/or subretinal fibrosis in the intermediate stage of the disease, and, in addition, to describe marked clinical manifestation in a heterozygous carrier female. METHOD: Two patients were examined by slip-lamp biomicroscopy, ophthalmoscopy and other ophthalmoloscopic examinations. RESULTS: Two cases showed moderately advanced ophthalmoscopic and functional abnormalitities compatible with choroideremia, and in addition, subretinal lesion in the fovea and/or midperiphery. CONCLUSION: The intermediate stage of choroideremia may occasionally be complicated with choroidal neovascular membrane in the fovea, the midperiphery, or both, which resolves spontaneously and results in subretinal fibrous scarring. The occurrence of this complication in the fovea leads to episodic central visual loss, while midperipheral lesion may remain unrecognized.

A novel PAX6 gene mutation (P118R) in a family with congenital nystagmus associated with a variant form of aniridia.

BACKGROUND: A variety of PAX6 gene mutations were identified in patients with aniridia and/or allied ocular dysgenesis such as keratopathy, Peters' anomaly, foveal hypoplasia, and nystagmus. To scrutinize the etiology of a four-generation Japanese family with autosomal dominant nystagmus associated with anterior and posterior segment anomalies, the PAX6 gene was examined. PATIENTS AND METHODS: A Japanese family showed a variant aniridia phenotype in four successive generations. Affected individuals had congenital nystagmus, microcornea with shortened axial length, superficial peripheral corneal opacification with pannus formation, dislocated pupil, and foveal hypoplasia. Analysis of the PAX6 gene mutation was performed in affected and unaffected individuals. RESULTS: A novel missense mutation in the PAX6 gene was found in all affected individuals examined, but neither in unaffected individuals nor in unrelated healthy individuals. This mutation predicted a proline to arginine change at codon 118 (P118R) in the paired domain of PAX6 protein. CONCLUSION: The reported family illustrates that mutations in the PAX6 gene, in particular missense mutations, may manifest atypical clinical expression or forme fruste of aniridia.

Isolation and characterization of mucinlike glycoprotein associated with photoreceptor cells.

PURPOSE: Although previous lectin-histochemical studies have shown that O-linked glycoproteins are distributed in cone pedicles and rod spherules, as well as in photoreceptors, including associated interphotoreceptor matrices (IPM), attention has been directed only to those in the IPM. In this study, cloning of the O-linked glycoproteins not only in the IPM but also in the region including the cone pedicles and rod spherules was attempted. METHODS: The cDNA for the core protein of the O-linked glycoprotein in the bovine retina was isolated by screening a bovine retinal cDNA library using a polyclonal antibody against the jacalin (a lectin specific for O-linked sugar residues)-binding glycoproteins (JBGPs) in the whole bovine retina. The expression of the JPGP core protein in the retina was examined by means of in situ hybridization histochemistry and immunohistochemistry. RESULTS: The cDNA was isolated and found to encode an entire core protein [predicted molecular mass (Mr): 101 kDa; rich in Ser and Thr; mucin-like] for the JBGPs with Mr of 120 and 135 kDa. The mRNA was expressed in both cone and rod photoreceptor cells. This protein was distributed in the cone pedicles and rod spherules as well as the photoreceptor layer. CONCLUSIONS: Mucinlike glycoproteins with Mr of 120 and 135 kDa may be synthesized in the cone and rod photoreceptor cells, respectively, and distributed not only in the photoreceptor layer (probably including the IPM) but also in the cone pedicles and rod spherules.

Clinical and genetic features of choroideremia

Background: Choroideremia is an X-linked hereditary eye disease that causes progressive degeneration of the choroid and retina and frequently leads to legal blindness in later life. Recent molecular genetic studies have revealed mutations involving the Rab escort protein (REP-1) gene localized at Xq 21.Clinical Features: The clinical picture and rate of progression may vary among affected individuals in different families and within the same family. Usually, hemizygous males develop night blindness in their teenage years, followed by progressive peripheral visual field constriction and visual disability in late age. Heterozygous female carriers are mostly asymptomatic, but their fundi show characteristic pigment changes in the midperiphery closely resembling the fine mottling observed in the initial stage of the disease in males.Molecular Genetics: Assessment of the REP-1 gene in European and Japanese choroideremia patients has revealed a wide variety of mutations, including gross deletions and point mutations such as nonsense, frameshift, and splice-site mutations. All these mutations are thought to fail in intact REP-1 protein synthesis.Conclusions: The recent molecular studies may open a new chapter in the research on choroideremia as well as diagnosis and genetic counseling.

Introduction to genetics in ophthalmology, value of family studies

This paper reviews the author's personal experience with genetic eye diseases and discusses the significance of family studies in providing key information for the advancement of molecular research. Choroideremia: This disease has long been known as an X-linked progressive tapetoretinal degeneration, but it was first described in Japan in 1974 after finding asymptomatic fundus changes in heterozygous female carriers that are compatible with X chromosomal inactivation. Mutations in the disease-causing gene (REP-1) provide a clue to the diagnosis and pathophysiology of the disease.Leber's Hereditary Optic Neuropathy: The clinical expression is so variable among affected individuals and families that mild optic nerve disease of insidious onset should be differentiated from autosomal dominant optic atrophy. Molecular assessment of mitochondrial DNA leads to a definite diagnosis of the disease, but mitochondrial DNA mutations do not fully account for the clinical manifestation and phenotypic variability of the disease.Norrie Disease: This rare X-linked vitreoretinal dysplasia, characterized by congenital bilateral blindness, was documented in Japan some twenty years ago and the disease has been identified in four unrelated Japanese families. The disease, once diagnosed on the basis of elaborate clinical and familial studies, can now be defined by molecular assessment of the Norrie disease gene.Congenital Nystagmus: A four-generation family was described which presented with autosomal dominantly inherited congenital nystagmus, peripheral corneal opacity, and foveal hypoplasia without any iris tissue malformation. The diagnosis of this family was established by detection of a missense mutation in the paired domain of the PAX 6 gene, hence conforming to a forme fruste of congenital aniridia.Sorsby's Fundus Dystrophy: Two Japanese families with Sorsby's fundus dystrophy showed late-onset retinal dystrophy characterized by submacular hemorrhage and atrophy. Our patients presented with visual loss as late as 50 years of age or older due to macula-confined degenerative changes that were similar in all respects to exudative age-related macular degeneration and showed a novel mutation in the tissue inhibitor of the metalloproteinases-3 gene.Age-Related Macular Degeneration (ARMD): We have studied whether there is any association of candidate polymorphic genes involving xenobiotic or antioxidant metabolism with susceptibility to ARMD. Preliminary results suggest that the genetic polymorphism of microsomal epoxide hydrolase is related to potential risk of ARMD.