A frameshift mutation in NOD2 associated with susceptibility to Crohn's disease

Crohn's disease is a chronic inflammatory disorder of the gastrointestinal tract, which is thought to result from the effect of environmental factors in a genetically predisposed host. A gene location in the pericentromeric region of chromosome 16, IBD1, that contributes to susceptibility to Crohn's disease has been established through multiple linkage studies, but the specific gene(s) has not been identified. NOD2, a gene that encodes a protein with homology to plant disease resistance gene products is located in the peak region of linkage on chromosome 16 (ref. 7). Here we show, by using the transmission disequilibium test and case-control analysis, that a frameshift mutation caused by a cytosine insertion, 3020insC, which is expected to encode a truncated NOD2 protein, is associated with Crohn's disease. Wild-type NOD2 activates nuclear factor NF-kappaB, making it responsive to bacterial lipopolysaccharides; however, this induction was deficient in mutant NOD2. These results implicate NOD2 in susceptibility to Crohn's disease, and suggest a link between an innate immune response to bacterial components and development of disease.

Nod2, a Nod1/Apaf-1 family member that is restricted to monocytes and activates NF-kappaB

Apaf-1 and Nod1 are members of a protein family, each of which contains a caspase recruitment domain (CARD) linked to a nucleotide-binding domain, which regulate apoptosis and/or NF-kappaB activation. Nod2, a third member of the family, was identified. Nod2 is composed of two N-terminal CARDs, a nucleotide-binding domain, and multiple C-terminal leucine-rich repeats. Although Nod1 and Apaf-1 were broadly expressed in tissues, the expression of Nod2 was highly restricted to monocytes. Nod2 induced nuclear factor kappaB (NF-kappaB) activation, which required IKKgamma and was inhibited by dominant negative mutants of IkappaBalpha, IKKalpha, IKKbeta, and IKKgamma. Nod2 interacted with the serine-threonine kinase RICK via a homophilic CARD-CARD interaction. Furthermore, NF-kappaB activity induced by Nod2 correlated with its ability to interact with RICK and was specifically inhibited by a truncated mutant form of RICK containing its CARD. The identification of Nod2 defines a subfamily of Apaf-1-like proteins that function through RICK to activate a NF-kappaB signaling pathway.

Mutations in the nonstructural protein 5A gene and response to interferon in patients with chronic hepatitis C virus 1b infection

BACKGROUND

A region associated with sensitivity to interferon has been identified in the nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) genotype 1b. The region spans amino acid residues 2209 to 2248 (NS5A2209-2248) of HCV-J, a strain of HCV-1b whose complete genomic sequence has been identified. We examined whether the NS5A2209-2248 sequence present before therapy could be used as a predictor of the response to interferon therapy in patients with chronic HCV-1b infection.

METHODS

We retrospectively analyzed 84 patients with chronic HCV-1b infection who had received interferon alfa (total dose, 516 million to 880 million units) for six months. Pretreatment serum samples were analyzed. The amino acid sequence of NS5A2209-2248 was determined by direct sequencing of the HCV genome amplified by the polymerase chain reaction (PCR) and was compared with the established sequence for HCV-J.

RESULTS

A complete response, as evidenced by the absence of HCV RNA in serum on nested reverse-transcription PCR for six months after therapy, did not occur in any of the 30 patients whose NS5A2209-2248 sequences were identical to that of HCV-J (wild type). Five of 38 patients (13 percent) with 1 to 3 changes in NS5A2209-2248 (intermediate type) had complete responses, as did all 16 patients with 4 to 11 amino acid substitutions (mutant type), indicating that the mutant type was significantly associated with a complete response (P < 0.001). Although baseline serum HCV RNA levels, as measured by a branched-chain DNA assay, were lower in patients with the mutant type of NS5A2209-2248 than in those with the other types (P < 0.001), multivariate analyses revealed that the number of amino acid substitutions in NS5A2209-2248 was the only variable associated with an independent effect on the outcome of interferon therapy (odds ratio, 5.3; 95 percent confidence interval, 1.6 to 18; P = 0.007).

CONCLUSIONS

In patients with chronic HCV-1b infection, there is a substantial correlation between responses to interferon and mutations in the NS5A gene.

Prevention of leukostasis and vascular leakage in streptozotocin-induced diabetic retinopathy via intercellular adhesion molecule-1 inhibition

Diabetic retinopathy is a leading cause of adult vision loss and blindness. Much of the retinal damage that characterizes the disease results from retinal vascular leakage and nonperfusion. This study shows that diabetic retinal vascular leakage and nonperfusion are temporally and spatially associated with retinal leukocyte stasis (leukostasis) in the rat model of streptozotocin-induced diabetes. Retinal leukostasis increases within days of developing diabetes and correlates with the increased expression of retinal intercellular adhesion molecule-1 (ICAM-1). ICAM-1 blockade with a mAb prevents diabetic retinal leukostasis and vascular leakage by 48.5% and 85.6%, respectively. These data identify the causal role of leukocytes in the pathogenesis of diabetic retinopathy and establish the potential utility of ICAM-1 inhibition as a therapeutic strategy for the prevention of diabetic retinopathy.

An induced proximity model for NF-kappa B activation in the Nod1/RICK and RIP signaling pathways

Nod1 is an Apaf-1-like molecule composed of a caspase-recruitment domain (CARD), nucleotide-binding domain, and leucine-rich repeats that associates with the CARD-containing kinase RICK and activates nuclear factor kappaB (NF-kappaB). We show that self-association of Nod1 mediates proximity of RICK and the interaction of RICK with the gamma subunit of the IkappaB kinase (IKKgamma). Similarly, the RICK-related kinase RIP associated via its intermediate region with IKKgamma. A mutant form of IKKgamma deficient in binding to IKKalpha and IKKbeta inhibited NF-kappaB activation induced by RICK or RIP. Enforced oligomerization of RICK or RIP as well as of IKKgamma, IKKalpha, or IKKbeta was sufficient for induction of NF-kappaB activation. Thus, the proximity of RICK, RIP, and IKK complexes may play an important role for NF-kappaB activation during Nod1 oligomerization or trimerization of the tumor necrosis factor alpha receptor.

Human Nod1 confers responsiveness to bacterial lipopolysaccharides

The immune response to microbial pathogens is initiated by recognition of specific pathogen components by host cells both at the cell surface and in the cytosol. While the response triggered by pathogen products at the surface of immune cells is well characterized, that initiated in the cytosol is poorly understood. Nod1 is a member of a growing family of intracellular proteins with structural homology to apoptosis regulators Apaf-1/Ced-4 and a class of plant disease-resistant gene products. Here we show that bacterial lipopolysaccharides, but not other pathogen components tested, induced TLR4- and MyD88-independent NF-kappaB activation in human embryonic kidney 293T cells expressing trace amounts of Nod1. Nod2, another Nod family member, also conferred responsiveness to bacterial components but with a response pattern different from that observed with Nod1. As it was reported for plant disease-resistant R proteins, the leucine-rich repeats of Nod1 and Nod2 were required for lipopolysaccharide-induced NF-kappaB activation. A lipopolysaccharide binding activity could be specifically coimmunopurified with Nod1 from cytosolic extracts. These observations suggest that Nod1 and Nod2 are mammalian counterparts of plant disease-resistant gene products that may function as cytosolic receptors for pathogen components derived from invading bacteria.

Gene organization deduced from the complete sequence of liverwort Marchantia polymorpha mitochondrial DNA. A primitive form of plant mitochondrial genome

Analysis of the mitochondrial DNA of a liverwort Marchantia polymorpha by electron microscopy and restriction endonuclease mapping indicated that the liverwort mitochondrial genome was a single circular molecule of about 184,400 base-pairs. We have determined the complete sequence of the liverwort mitochondrial DNA and detected 94 possible genes in the sequence of 186,608 base-pairs. These included genes for three species of ribosomal RNA, 29 genes for 27 species of transfer RNA and 30 open reading frames (ORFs) for functionally known proteins (16 ribosomal proteins, 3 subunits of H(+)-ATPase, 3 subunits of cytochrome c oxidase, apocytochrome b protein and 7 subunits of NADH ubiquinone oxidoreductase). Three ORFs showed similarity to ORFs of unknown function in the mitochondrial genomes of other organisms. Furthermore, 29 ORFs were predicted as possible genes by using the index of G + C content in first, second and third letters of codons (42.0 +/- 10.9%, 37.0 +/- 13.2% and 26.4 +/- 9.4%, respectively) obtained from the codon usages of identified liverwort genes. To date, 32 introns belonging to either group I or group II intron have been found in the coding regions of 17 genes including ribosomal RNA genes (rrn18 and rrn26), a transfer RNA gene (trnS) and a pseudogene (psi nad7). RNA editing was apparently lacking in liverwort mitochondria since the nucleotide sequences of the liverwort mitochondrial DNA were well-conserved at the DNA level.

Expression of NOD2 in Paneth cells: a possible link to Crohn's ileitis

BACKGROUND AND AIMS

Genetic variation in NOD2 has been associated with susceptibility to Crohn's disease (CD) and specifically with ileal involvement. The reason for the unique association of NOD2 mutations with ileal disease is unclear. To identify a possible link, we tested expression of NOD2 in intestinal tissue of CD patients and controls.

PATIENTS AND METHODS

Fifty five specimens of ileum or colon from 21 CD patients, seven ulcerative colitis (UC) patients, and five controls with pathology other than CD or UC were stained for NOD2 using an immunoperoxidase method.

RESULTS

Using a monoclonal antibody against NOD2 developed in our laboratory, we detected uniform expression of NOD2 in terminal ileum Paneth cells from controls and patients as well as in metaplastic Paneth cells in the colon. Mechanical purification showed enriched expression of NOD2 mRNA in ileal crypts. In Paneth cells, NOD2 was located in the cytosol in close proximity to the granules that contain antimicrobial peptides. We detected minimal NOD2 in the villous epithelium of the ileum or in the colonic epithelium from both CD patients and controls.

CONCLUSIONS

These results suggest a role for NOD2 in the regulation of Paneth cell mediated responses against intestinal bacteria and a plausible mechanism to explain the selective association of NOD2 mutations with ileal disease. The impaired capacity of CD associated mutations to sense luminal bacteria may result in increased susceptibility to certain gut microbes.

Impact of sarcopenia on survival in patients undergoing living donor liver transplantation

Skeletal muscle depletion, referred to as sarcopenia, predicts morbidity and mortality in patients undergoing digestive surgery. However, the impact on liver transplantation is unclear. The present study investigated the impact of sarcopenia on patients undergoing living donor liver transplantation (LDLT). Sarcopenia was assessed by a body composition analyzer in 124 adult patients undergoing LDLT between February 2008 and April 2012. The correlation of sarcopenia with other patient factors and the impact of sarcopenia on survival after LDLT were analyzed. The median ratio of preoperative skeletal muscle mass was 92% (range, 67-130%) of the standard mass. Preoperative skeletal muscle mass was significantly correlated with the branched-chain amino acids to tyrosine ratio (r = -0.254, p = 0.005) and body cell mass (r = 0.636, p < 0.001). The overall survival rate in patients with low skeletal muscle mass was significantly lower than in patients with normal/high skeletal muscle mass (p < 0.001). Perioperative nutritional therapy significantly increased overall survival in patients with low skeletal muscle mass (p = 0.009). Multivariate analysis showed that low skeletal muscle mass was an independent risk factor for death after transplantation. In conclusion, sarcopenia was closely involved with posttransplant mortality in patients undergoing LDLT. Perioperative nutritional therapy significantly improved overall survival in patients with sarcopenia.

Vascular endothelial growth factor (VEGF)-induced retinal vascular permeability is mediated by intercellular adhesion molecule-1 (ICAM-1)

Two prominent vascular endothelial growth factor (VEGF)-induced retinal effects are vascular permeability and capillary nonperfusion. The mechanisms by which these effects occur are not completely known. Using a rat model, we show that intravitreous injections of VEGF precipitate an extensive retinal leukocyte stasis (leukostasis) that coincides with enhanced vascular permeability and capillary nonperfusion. The leukostasis is accompanied by the up-regulation of intercellular adhesion molecule-1 expression in the retina. The inhibition of intercellular adhesion molecule-1 bioactivity with a neutralizing antibody prevents the permeability and leukostasis increases by 79% and 54%, respectively. These data are the first to demonstrate that a nonendothelial cell type contributes to VEGF-induced vascular permeability. Additionally, they identify a potential mechanism for VEGF-induced retinal capillary nonperfusion.

Genetic variants in GPR126 are associated with adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is the most common pediatric skeletal disease. We previously reported a locus on chromosome 10q24.31 associated with AIS susceptibility in Japanese using a genome-wide association study (GWAS) consisting of 1,033 cases and 1,473 controls. To identify additional AIS-associated loci, we expanded the study by adding X-chromosome SNPs in the GWAS and increasing the size of the replication cohorts. Through a stepwise association study including 1,819 cases and 25,939 controls, we identified a new susceptibility locus on chromosome 6q24.1 in Japanese (P = 2.25 × 10(-10); odds ratio (OR) = 1.28). The most significantly associated SNP, rs6570507, was in GPR126 (encoding G protein-coupled receptor 126). Its association was replicated in Han Chinese and European-ancestry populations (combined P = 1.27 × 10(-14); OR = 1.27). GPR126 was highly expressed in cartilage, and the knockdown of gpr126 in zebrafish caused delayed ossification of the developing spine. Our results should provide insights into the etiology and pathogenesis of AIS.

Radical operations for carcinoma of the gallbladder: present status in Japan

Based on the histological findings of 1,686 resected cases of gallbladder carcinoma and operative results collected from 172 major hospitals in Japan, the present status of radical operation was assessed with respect to the relationship between the depth of carcinoma invasion and the operative results. The depth of carcinoma invasion was classified into 5 groups, i.e., limited to the mucosal layer (m) in 11.9%, advanced to the proper muscle layer (pm) in 9.8%, extending to the subserosal layer (ss) in 29.6%, serosal involvement (se) in 21.8%, and carcinoma invading the adjacent organs (si) in 26.9%. Tumor extension, such as lymph node metastasis, invasion of lymphatic and venous vessels, and perineural infiltration, were observed more frequently in patients with ss, se, and si than in those with m and pm. The cumulative 5-year survival rates were 82.6% and 72.5% in patients with m and pm, which were significantly higher than 37.0%, 14.7%, and 7.5% in those with ss, se, and si, respectively. The choice of operative procedures should depend on the depth of carcinoma invasion. Cholecystectomy alone is done only in patients with tumor limited to the mucosa, and more radical procedures such as extended cholecystectomy should be performed in those with carcinoma invasion beyond the mucosa. Pancreatoduodenectomy is indicated in those with lymph node metastasis posterior to the head of the pancreas and with invasion to the duodenum. When the tumor directly invades the liver, major hepatic resection is recommended.(ABSTRACT TRUNCATED AT 250 WORDS)

Interactions in the error-prone postreplication repair proteins hREV1, hREV3, and hREV7

Most mutations after DNA damage in yeast Saccharomyces cerevisiae are induced by error-prone translesion DNA synthesis employing scRev1 and DNA polymerase zeta that consists of scRev3 and scRev7 proteins. Recently, the human REV1 (hREV1) and REV3 (hREV3) genes were identified, and their products were revealed to be involved in UV-induced mutagenesis, as observed for their yeast counterparts. Human REV7 (hREV7) was also cloned, and its product was found to interact with hREV3, but the biological function of hREV7 remained unknown. We report here the analyses of precise interactions in the human REV proteins. The interaction between hREV1 and hREV7 was identified by the yeast two-hybrid library screening using a bait of hREV7, which was confirmed by in vitro and in vivo binding assays. The homodimerization of hREV7 was also detected in the two-hybrid analysis. In addition, the precise domains for interaction between hREV7 and hREV1 or hREV3 and for hREV7 homodimerization were determined. Although hREV7 interacts with both hREV1 and hREV3, a stable complex formation of the three proteins was undetectable in vitro. These findings suggest the possibility that hREV7 might play an important role in regulating the enzymatic activities of hREV1 and hREV3 for mutagenesis in response to DNA damage.

Poly(vinyl alcohol) hydrogels as soft contact lens material

A new type of soft contact lens was developed from the poly(vinyl alcohol) (PVA) hydrogel prepared by a low temperature crystallization technique using a water-dimethyl sulfoxide mixed solvent. The PVA contact lens materials had a water content of 78% and a tensile strength of 50 kg/cm2, five times as strong as that of commercial poly(2-hydroxyethyl methacrylate) soft contact lens. The amount of proteins adsorbed to the PVA soft hydrogel material was half to one thirtieth of that of conventional soft contact lenses. Histological and scanning electron microscopic observation of rabbit eyes which had worn the PVA soft contact lens for 12 weeks showed no difference in corneal epithelium and cell arrangement in the corneal epithelium from the non-wearing eyes.

Guidance with real-time CT fluoroscopy: early clinical experience

A recently developed real-time computed tomography (CT) fluoroscopy system, which provides effective real-time reconstruction and display of CT images, was used to monitor nonvascular interventional procedures performed in 57 patients. Biopsy of thoracic lesions (n = 38), biopsy or drainage of pelvic lesions (n = 6), drainage or aspiration of intracranial hematomas (n = 9), and other procedures (n = 4) were performed. CT fluoroscopy successfully depicted the entire procedure in all patients. In thoracic lesions, a mean 1.3 passes was necessary to gain access to the lesion. Sufficient cytologic samples were obtained in 32 of 33 pulmonary lesions with a mean diameter of 26 mm.

Intracranial aneurysms: detection with three-dimensional CT angiography with volume rendering--comparison with conventional angiographic and surgical findings

PURPOSE

To assess the diagnostic accuracy of three-dimensional (3D) computed tomographic (CT) angiography for intracranial aneurysms.

MATERIALS AND METHODS

The 3D CT angiograms obtained in 49 patients with or without intracranial aneurysms were evaluated by four blinded observers. Results were compared with findings at conventional angiography or surgery. A volume-rendering method was used, and 13 images obtained in different directions were reviewed in each study. The diameter of aneurysms was divided into four sizes: large, greater than 13 mm; medium, 5-12 mm; small, 3-4 mm; and very small, less than 3 mm. Results were also evaluated by means of receiver operating characteristic analysis.

RESULTS

At conventional angiography, 47 aneurysms, including 14 less than 3 mm, were depicted in 35 patients. The mean sensitivity of CT angiography for very small aneurysms was 64%; small, 83%; medium, 95%; and large, 100%. Some very small aneurysms that were not depicted at conventional angiography were depicted at CT angiography, and one was proved at surgery.

CONCLUSION

CT angiography has good sensitivity for depiction of intracranial aneurysms 3 mm or larger and relatively good sensitivity for aneurysms less than 3 mm. CT angiography may be a noninvasive technique for detection of asymptomatic unruptured or ruptured aneurysms.

Significance of des-gamma-carboxy prothrombin in selection criteria for living donor liver transplantation for hepatocellular carcinoma

Des-gamma-carboxy prothrombin (DCP) levels reportedly correlate with histological features of hepatocellular carcinoma (HCC). We examined serum DCP as a predictor of HCC recurrence in 144 patients who underwent living donor liver transplantation. Receiver operating characteristics (ROC) analysis revealed superiority of DCP and AFP over preoperative tumor size or number for predicting recurrence. Multivariate analysis revealed tumor size >5 cm, > or =11 nodules, and DCP >400 mAU/mL as significant independent risk factors for recurrence. Incidence of microvascular invasion (62% vs. 27%, p = 0.0003) and poor differentiation (38% vs. 16%, p = 0.0087) were significantly higher for patients with DCP >400 mAU/mL than for patients with DCP < or =400 mAU/mL. In ROC analysis for patients with < or =10 nodules all < or =5 cm to predict recurrence, area under the curve was much higher for DCP than for AFP (0.84 vs. 0.69). Kyoto criteria were thus defined as < or =10 nodules all < or =5 cm, and DCP < or =400 mAU/mL. The 5-year recurrence rate for 28 patients beyond-Milan but within-Kyoto criteria was as excellent as that for 78 patients within-Milan criteria (3% vs. 7%). The preoperative DCP level offers additional information regarding histological features, and thus can greatly improve patient selection criteria when used with tumor bulk information.

PDGFR alpha expression during mouse embryogenesis: immunolocalization analyzed by whole-mount immunohistostaining using the monoclonal anti-mouse PDGFR alpha antibody APA5

We investigated the cells that express platelet-derived growth factor receptor alpha (PDGFR alpha) during mouse embryogenesis. PDGFR alpha expression has been identified by in situ hybridization or immunohistochemistry using polyclonal antibodies on tissue sectins. Because no immunostaining study using whole-mount specimens has been published to date, we established a new monoclonal antibody (MAb), APA5, for this purpose. Our results differed in that APA5 stained only the paraxial mesoderm, whereas other investigators concluded that most if not all mesodermal cells expressed PDGFR alpha. Moreover, we did not find PDGFR alpha expression in embryonic erythrocytes, which have been previously suggested to express PDGFR alpha. On the basis of our present results, we wish to revise the proposed PDGFR alpha expression as follows. At the pregastrulation stage, PDGFR alpha is expressed only in primitive endoderm, particularly that in the ectoplacental cone. On gastrulation, it is expressed at high levels in the paraxial mesoderm. This expression continues after its differentiation into the somite. Along with the differentiation and migration of the sclerotome, PDGFR alpha + cells begin to become distributed throughout the embryonal mesenchyme. During organogenesis, particularly intense staining is detected in regions of epithelial and mesenchymal interaction, such as the tooth bud and bronchi. In addition to mesodermal derivatives, the developing lens, apical ectodermal ridge, glial precursor, cardiac valves, and choroid plexus express PDGFR alpha. Our results with whole-mount immunostaining show that PDGFR alpha is abundantly expressed and may play important roles during embryogenesis.

A new feature of angiotensin-converting enzyme in the brain: hydrolysis of substance P

Highly purified rat brain angiotensin-converting enzyme hydrolyzes substance P which contains a C-terminal amino acid with an amidated carboxyl group. The hydrolysis of substance P verified by amino-group fluorometry and by high-performance liquid chromatography is inhibited by captopril, but not by phosphoramidon. The presence of sodium chloride is essential for the hydrolysis. The analyses of cleavage products indicate that the enzyme hydrolyzes substance P between Phe7-Phe8 and Phe8-Gly9 by an endopeptidase action, followed by successive release of dipeptides by a dipeptidyl carboxypeptidase action.

A Functional SNP in BNC2 Is Associated with Adolescent Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) is the most common spinal deformity. We previously conducted a genome-wide association study (GWAS) and detected two loci associated with AIS. To identify additional loci, we extended our GWAS by increasing the number of cohorts (2,109 affected subjects and 11,140 control subjects in total) and conducting a whole-genome imputation. Through the extended GWAS and replication studies using independent Japanese and Chinese populations, we identified a susceptibility locus on chromosome 9p22.2 (p = 2.46 × 10(-13); odds ratio = 1.21). The most significantly associated SNPs were in intron 3 of BNC2, which encodes a zinc finger transcription factor, basonuclin-2. Expression quantitative trait loci data suggested that the associated SNPs have the potential to regulate the BNC2 transcriptional activity and that the susceptibility alleles increase BNC2 expression. We identified a functional SNP, rs10738445 in BNC2, whose susceptibility allele showed both higher binding to a transcription factor, YY1 (yin and yang 1), and higher BNC2 enhancer activity than the non-susceptibility allele. BNC2 overexpression produced body curvature in developing zebrafish in a gene-dosage-dependent manner. Our results suggest that increased BNC2 expression is implicated in the etiology of AIS.

Effect of particle size of polymeric nanospheres on intravitreal kinetics

In this study, we injected nanospheres containing a fluorescein derivative into the vitreous cavity of pigmented rabbit eyes and evaluated their intraocular kinetics as drug carriers in vivo. Polystyrene nanospheres (2 microm, 200 nm and 50 nm in diameter) containing a fluorescein derivative were used in this study. A suspension of each particle was prepared by diluting with distilled water at a concentration of 10 microg/ml equivalent to sodium fluorescein. The suspension of nanospheres was injected once into the vitreous cavity of unilateral eyes of pigmented rabbits. A sodium fluorescein solution of the same concentration was injected once into the vitreous cavity of the other eye as the control. The intraocular kinetics of nanospheres was evaluated by measuring vitreous fluorescence using a scanning fluorophotometer. To investigate elimination pathways of nanospheres in detail, serial cross-sections of the eyes were examined with a fluorescence microscope. The fluorescence derived from nanospheres was observed in the vitreous cavity for over 1 month (2 microm: t(1/2) = 5.4 +/- 0.8 days, 200 nm: t(1/2) = 8.6 +/- 0.7 days, 50 nm: t(1/2) = 10.1 +/- 1.8 days), whereas that in the control eyes completely disappeared within 3 days (t(1/2) = 7.8 +/- 0.7 h). The elimination half-life from the vitreous cavity correlated well with the particle diameter (r = -0.997, p = 0.007). Histological studies using a fluorescence microscope revealed that nanospheres with a diameter of 2 microm were seen in the vitreous cavity and trabecular meshwork, while nanospheres with a diameter of smaller than 200 nm were also observed in the retina as well as these tissues. Our findings indicated that nanospheres may be beneficial as a drug carrier to the retina, vitreous and trabecular meshwork.

Retinal nerve fiber layer defect as an early manifestation of diabetic retinopathy

PURPOSE

An incidence of and risk factors for retinal nerve fiber layer defect were investigated in patients with type II diabetes mellitus and compared with that of age-matched control subjects.

METHODS

The authors photographed the retinal nerve fiber layer of the right eye in each of 137 patients with diabetes and 144 healthy control subjects. The level of diabetic retinopathy ranged from levels 1 (no microaneurysm) to 4 (eyes with localized intra-retinal microvascular abnormalities or venous beading). Risk factors for the nerve fiber layer defect analyzed were age of patients, visual acuity, axial length, optic disc size, glycosylated hemoglobin, systolic blood pressure, and level of diabetic retinopathy.

RESULTS

Defects of the retinal nerve fiber layer were found in 6/30 (20%) eyes with level 1 retinopathy, 8/14 (57%) eyes with level 2 retinopathy, 24/47 (51%) eyes with level 3 retinopathy, and 36/46 (78%) eyes with level 4 retinopathy. These defect incidences were significantly higher than that of the control group, which had 5/144 (3.5%) defects (P < or = 0.001). Risk factors for this nerve defect were level of diabetic retinopathy (P = 0.002), high systolic blood pressure (P = 0.0232), and patient's age (P = 0.0478). Not correlated with the incidence of the retinal nerve fiber layer defect were visual acuity, disc size, axial length, and glycosylated hemoglobin level at the time of examination.

CONCLUSION

These findings suggest that the retinal nerve fiber layer defect is common in patients with early diabetic retinopathy. Risk factors for this defect were higher level of diabetic retinopathy, systemic hypertension, and advanced age.

Cloning and molecular analysis of the Arabidopsis gene Terminal Flower 1

The Arabidopsis gene Terminal Flower 1 (TFL1) controls inflorescence meristem identity. A terminal flower (tfl1) mutant, which develops a terminal flower at the apex of the inflorescence, was induced by transformation with T-DNA. Using a plant DNA fragment flanking the integrated T-DNA as a probe, a clone was selected from a wild-type genomic library. Comparative sequence analysis of this clone with an EST clone (129D7T7) suggested the existence of a gene encoding a protein similar to that encoded by the cen gene which controls inflorescence meristem identity in Antirrhinum. Nucleotide sequences of the region homologous to this putative TFL1 gene were compared between five chemically induced tfl1 mutants and their parental wild-type ecotypes. Every mutant was found to have a nucleotide substitution which could be responsible for the tfl1 phenotype. This result confirmed that the cloned gene is TFL1 itself. In our tfl1 mutant, no nucleotide substitution was found in the transcribed region of the gene, and the T-DNA-insertion site was located at 458 bp downstream of the putative polyadenylation signal, suggesting that an element important for expression of the TFL1 gene exists in this area.

Pathogenetic potential of leukocytes in diabetic retinopathy

Recently, increasing interest has been directed toward the role of leukocytes in microvascular disorders including diabetic retinopathy because of their large cell volume, high cytoplasmic rigidity, natural tendency to stick to the vascular endothelium, and capacity to generate toxic superoxide radicals and proteolytic enzymes. Leukocytes in diabetes are reported to be less deformable and more activated, and may be involved in capillary non-perfusion, endothelial cell damage, and vascular leakage in the retinal microcirculation. In fact, histological studies show many capillary occlusions by leukocytes and capillary dropout or degeneration associated with leukocytes in the diabetic retina. Serial acridine orange leukocyte fluorography and fluorescein angiography studies also identify trapped leukocytes directly associated with areas of downstream non-perfusion in the diabetic retinal microcirculation. More recent studies suggest that adhesion molecules may mediate retinal leukocyte stasis (leukostasis) in diabetes and a reduction in the leukostasis by anti-adhesion antibodies can suppress retinal vascular leakage. In addition, some agents inhibiting leukostasis are reported to improve retinal abnormalities induced by diabetes. Thus, leukostasis in the retinal microcirculation can be a new promising target in the treatment of diabetic retinopathy.