Abstract LB-359: Plasma microRNAs as novel biomarkers for lung cancer

Objective: Lung cancer is the leading cause of cancer-related deaths in both men and women. Since there is no validated population-based screening procedure, most patients with lung cancer are diagnosed at advanced stages with an overall five-year survival rate of only 15%. Therefore, diagnosis of lung cancer at an early stage is important for improving the outcome of patients. MicroRNAs (miRNAs), a family of 19- to 25-nucleotide and noncoding small RNAs that primarily function as gene regulators at post-transcriptional level, are frequently dysregulated in cancer. Recent studies demonstrate that the miRNAs in blood are present in notably stabile form and are readily detectible by various sensitive methods. This new finding has raised a concept that circulating miRNAs could be novel non-invasive biomarkers for cancer detection. The objective of this study is to investigate the potential of circulating microRNAs for lung cancer detection.

Methods: First, we searched the miRNA microarray data of lung cancer from published literature, and selected 15 of miRNAs (miR-17, 21, 24, 106a, 125b, 128, 155, 182, 183, 197, 199b, 203, 205, 210 and 221) that were most frequently up-regulated in lung cancer tissues. Total RNA including miRNAs were isolated with mirVana PARIS kit (Ambion, TX), then polyadenylated and reverse-transcribed with a poly(T) adapter into cDNAs for real-time PCR using the miRNA-specific forward primer and the sequence complementary to the poly(T) adapter as the reverse primer. The levels of miRNAs were determined in 28 plasma samples from lung cancer patients and 16 of controls.

Results: We found that the levels of miR-155, miR-182 and miR-197 in plasma of lung cancer patients were significantly elevated compared with controls. MiR-155 yielded an AUC (the areas under the ROC curve) of 0.8739 (95% CI:0.7489 to 0.9989, P<0.001), miR-182 yielded an AUC of 0.8426 (95% CI:0.7239 to 0.9614, P<0.001) and miR-197 yielded an AUC of 0.8037 (95% CI:0.6705 to 0.9369, P<0.001) in discriminating lung cancer from controls.

Conclusions: MiR-155, miR-182 and miR-197 are significantly elevated in patient plasma with lung cancer and can be a potential non-invasive molecular biomarker for lung cancer screening and clinical follow-up.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-359.

Molecular detection of B-cell neoplasms by specific DNA methylation biomarkers

A novel, easy to perform PCR-based method employing specific DNA methylation biomarkers to detect B-cell neoplasms in a variety of B-cell lines and B lymphoblastic leukemia (B-ALL) patient specimens has been developed. This method detects as few as 5 B-ALL cells, or 1 B-ALL cell in 1,000,000 normal background blood cells using a single marker, DLC-1 gene CpG island (CGI) methylation. By adding two additional markers PCDHGA12 and RPIB9, over 80% of B-ALL cases were detected in patients' bone marrow and/or peripheral blood specimens. We have traced clinical B-ALL cases up to 10 years retrospectively and the DLC-1 methylation is correlated with patient clinical status. Thus, this epigenetic-based molecular method demonstrates its potential use in the diagnosis of B-cell neoplasia, in addition to traditional approach such as clinical features, morphology, immunophenotype, and genetic analysis.

Genetic structure of Oryza rufipogon Griff. in China

Oryza rufipogon Griff. (common wild rice; CWR) is the ancestor of Asian cultivated rice (Oryza sativa L.). Investigation of the genetic structure and diversity of CWR in China will provide information about the origin of cultivated rice and the grain quality and yield. In this study, we used 36 simple sequence repeat (SSR) markers to assay 889 accessions, which were highly representative of whole germplasm in China. The analysis revealed a hierarchical genetic structure within CWR. First, CWR has diverged into two ecotypic populations, a south subtropical population (SSP) and a middle subtropical population (MSP), probably owing to natural selection by the different climates. The distribution of specific alleles and haplotypes indicated that Chinese CWR had both indica-like and japonica-like variations; the SSP was an indica-like type, whereas the MSP was more japonica-like. The SSP and MSP further diverged into five (HN, GD-GX1, GX2, FJ and YN) and two (JX-HuN1 and HuN2) geographical populations, respectively. The genetic data suggest the isolation by distance, although water systems also appear to play an important role in the formation of homogenous populations, and occasionally landscape was also involved. The population GD-GX1, which grew widely in Guangdong and Guangxi provinces, was the largest geographical population in China. It had a high level of genetic diversity (GD) and the closest genetic relationship with other inferred populations. The population HN, with the smallest SSR molecular weights and the highest level of GD, may be the most ancestral population.

CpG islands: their potential as biomarkers for cancer

In general, DNA methylation acts in concert with other epigenetic processes, including histone modifications, chromatin remodeling and microRNAs, to shape the overall chromatin structure of the nucleus and potentially modify its functional state. Aberrant DNA methylation events can occur in a number of human diseases but we are only just beginning to appreciate the scope and magnitude of this process in human health. As one example, in contrast to normal cells, the cancer methylome is characterized by reciprocal hypermethylation of specific regulatory regions of genes along with an overall decrease in the quantity of 5-methylcytosine throughout the remainder of the genome. Currently, near genome-wide technologies are available and have been utilized to examine the extent of DNA methylation in discovery-based studies involving several physiological and disease states. Although early in the process, DNA methylation is being explored as a biomarker to be used in clinical practice for early detection of disease, tumor classification and for predicting disease outcome or recurrence. This perspective focuses on the current and future states of the use of DNA methylation biomarkers in disease diagnosis, prognosis and classification, with a particular emphasis on cancer.

Phylogeny of diplozoids in five genera of the subfamily Diplozoinae Palombi, 1949 as inferred from ITS-2 rDNA sequences

The phylogenetic relationship of 5 genera, i.e. Diplozoon Nordmann, 1832, Paradiplozoon Achmerov, 1974, Inustiatus Khotenovsky, 1978, Sindiplozoon Khotenovsky, 1981, and Eudiplozoon Khotenovsky, 1985 in the subfamily Diplozoinae Palombi, 1949 (Monogenea, Polyopisthocotylea) was inferred from rDNA ITS-2 region using neighbour-joining (NJ), maximum likelihood (ML) and Bayesian methods. The phylogenetic trees produced by using NJ, ML and Bayesian methods exhibit essentially the same topology. Surprisingly, freshwater species of Paradiplozoon from Europe clustered together with species of Diplozoon, but separated from Chinese Paradiplozoon species. The results of molecular phylogeny and lower level of divergence (4.1-15.7%) in ITS-2 rDNA among Paradiplozoon from Europe and Diplozoon and, on the other hand, high level of divergence (45.3-53.7%) among Paradiplozoon species from Europe and China might indicate the non-monophyletic origin of the genus Paradiplozoon. Also, the generic status of European Paradiplozoon needs to be revised. The species of Paradiplozoon in China is a basal group in Diplozoinae as revealed by NJ and Bayesian methods, and Sindiplozoon appears to be closely related to European Paradiplozoon and Diplozoon with their relationship to Eudiplozoon and Inustiatus being unresolved.

Discovery of 2-pyrimidyl-5-amidothiophenes as potent inhibitors for AKT: Synthesis and SAR studies

A series of 2-pyrimidyl-5-amidothiophenes has been synthesized and evaluated for AKT inhibition. SAR studies resulted in potent inhibitors of AKT with IC(50) values as low as single digit nanomolar as represented by compound 2aa. Compound 2aa showed cellular activity including antiproliferation and downstream target modulation. Selectivity profile is described. A co-crystal of 2aa with PKA is determined and discussed.

"Piecemeal" necrosis: renamed troxis necrosis

Piecemeal necrosis, currently called interface hepatitis, is a feature of viral hepatitis as well as autoimmune hepatitis and steatohepatitis. The mechanism of liver cell loss and piecemeal necrosis needs to be determined. We hypothesize that piecemeal necrosis in hepatitis is due to a piecemeal removal of hepatocyte cytoplasm by lymphocytic ingestion. To test this hypothesis, 61 consecutive liver biopsies were examined by light microscopy, by immunohistochemistry and by electron microscopy, and the lymphocytic-hepatocytic interaction was morphologically assessed. In cases of hepatitis C, hepatitis B, autoimmune hepatitis, primary biliary cirrhosis, and steatohepatitis, piecemeal necrosis was found. Using cytokeratin stains, it was apparent that the lymphocyte-hepatocyte interaction and piecemeal necrosis leads first to binding of the lymphocyte to hepatocyte plasma membrane and then blebbing or indentation of the hepatocyte by the lymphocyte, followed by endocytosis of liver cell cellular components and digestion in the lymphocyte lysosomes. This process is repeated while the cytoplasm and the nucleus of the hepatocyte disappear bite by bite, and only nubbins of residual hepatocytic cytoplasm remain, either attached to intact hepatocytes or surrounded and sequestered within scar tissue and lymphocytes. We conclude that piecemeal necrosis is a gradual disappearance of hepatocytes as a result of lymphocyte-hepatocyte binding and ligand internalization of liver surface molecules by the lymphocyte. This gradual process leads to a slow reduction of hepatocyte size and eventual disappearance at the interface between the lobule and portal tracts. To term this new kind of necrosis, we propose the name troxis necrosis, after the Greek noun meaning "nibbling."

The cell specific temporal expression of nitric oxide synthase isoforms during achilles tendon healing

OBJECTIVE AND DESIGN

We have previously shown that nitric oxide synthase (NOS) activity is upregulated following tendon injury, and that this activity is important to Achilles tendon healing. The aim of this study was to identify the cellular distribution of nitric oxide synthase isoforms during tendon healing.

MATERIAL OR SUBJECTS

Surgical division of the right Achilles tendon was performed in eighty-five male Sprague-Dawley rats. Healing Achilles tendons were harvested at 4, 7, 14 and 21 days following the surgery. The un-injured left Achilles tendons were used as controls. Using RNase protection assays, in situ hybridization and immunohistochemistry, mRNA and protein of NOS isoforms were evaluated.

RESULTS

Minimal NOS expression was found in un-injured tendon. A cell specific temporal pattern for the mRNA and protein for all three NOS isoforms was found following injury to the Achilles tendon. iNOS was maximal on day 4 in macrophages and fibroblasts. eNOS was maximal on day 4 in endothelial cells and fibroblasts. bNOS expression gradually increased up to day 21 and was found only in fibroblasts.

CONCLUSIONS

These results suggest that all three nitric oxide synthase isoforms are expressed by fibroblasts in a coordinated temporal sequence during tendon healing. The sequential pattern of NOS expression in healing fibroblasts suggests that each NOS isoform may play a different role in the healing process and provides opportunities to modify tendon healing in the clinical setting.

Antioxidant enzyme peroxiredoxin 5 is upregulated in degenerative human tendon

Peroxiredoxin 5 (PRDX5) is a novel thioredoxin peroxidase recently identified in a variety of human cells and tissues, which is considered to play an important role in oxidative stress protection mechanisms. However, little is known about its expression in tendon degeneration, a common and disabling condition that primarily affects older people, in which oxidative stress may be implicated. The present study demonstrated that normal human tendon expresses PRDX5 and its expression is significantly increased in degenerative tendon. In addition, we have localized PRDX5 to fibroblasts in normal tendon and to both fibroblasts and endothelial cells in degenerate tendon. The differential expression of PRDX5 in normal and degenerate tendon shows that a thioredoxin peroxidase with antioxidant properties is upregulated under pathophysiological conditions and suggests that oxidative stress may be involved in the pathogenesis of tendon degeneration. PRDX5 may play a protective role against oxidative stress during this pathophysiological process.

Nitric oxide in skeletal muscle: inhibition of nitric oxide synthase inhibits walking speed in rats

Nitric oxide (NO*) is a multifunctional messenger molecule generated by a family of enzymes called the nitric oxide synthases (NOSs). Although NOSs have been identified in skeletal muscle, specifically brain NOS (bNOS) and endothelial NOS (eNOS), their role has not been well clarified. The goals of this investigation were to (1) characterize the immunoreactivity, Ca(2+) dependence, and activity of NOS in human and rat skeletal muscle and (2) using a rat model, investigate the effect of chronic blockade of NOS on skeletal muscle structure and function. Our results showed that both human and rodent skeletal muscle had NOS activity. This NOS activity was similar to that of the endothelial and brain NOS isoforms in that it was calcium-dependent. However, Western blot analysis consistently showed that a polyclonal antibody raised against a peptide sequence of human inducible NOS (iNOS) reacted with a protein with a molecular weight (95 kDa) that was different from that of other NOS isoforms. RT-PCR analysis identified the mRNA expression of not only eNOS and bNOS but also iNOS in human and rat muscle. Inhibition of nitric oxide synthase in rats with N(omega)-nitro-L-arginine methyl ester (L-NAME) resulted in a progressive, severe reduction in walking speed (30-fold reduction in walking velocity at day 22, P < 0.001), muscle fiber cross-sectional area (40% reduction at day 22, P < 0.001), and muscle mass (40% reduction in dry weight at day 22, P < 0.01). Rats fed the same regimen of the enantiomer of L-NAME (d-NAME) had normal motor function, muscle fiber morphology, and muscle mass. Taken together, these results imply that there may be a novel nitric oxide synthase in muscle and that NO. generated from muscle may be important in muscle function.

Reduction in corneal haze and apoptosis by amniotic membrane matrix in excimer laser photoablation in rabbits

PURPOSE

To determine whether preserved human amniotic membrane can reduce corneal haze and keratocyte apoptosis induced by excimer laser photoablation in rabbit corneas.

METHODS

Excimer photoablation was performed bilaterally in 30 rabbits with a 6.0 mm ablation zone and 120 microm depth using the VISX Star laser with the phototherapeutic keratectomy (PTK) mode. One eye was randomly covered by preserved human amniotic membrane secured with 4 interrupted 10-0 nylon sutures, and the other eye served as the control. The amniotic membranes were removed at 1 week, and corneal haze was graded with slitlamp biomicroscopy by 3 masked corneal specialists biweekly for the ensuing 12 weeks until the rabbits were killed. Another 18 rabbits were divided into 4 subgroups and received PTK alone, PTK with membrane, PTK with sham sutures, or PTK with tarsorrhaphy. All eyes were studied histologically, and 3 eyes in each group were studied by in situ terminal deoxynucleotidyl transferase deoxy-UTP-nick end labeling assay at 1, 3, and 7 days and 12 weeks, respectively.

RESULTS

A consistent grading of differences in corneal haze scoring between the control corneas and the amniotic-membrane-covered corneas was noted among the 3 masked observers. Organized reticular post-PTK corneal haze peaked at 7 weeks in both groups, and the corneal haze score in the amniotic-membrane-covered group was significantly less than in the control group from 7 to 12 weeks (all P < .001). Compared to the control corneas, the amniotic-membrane-covered corneas had less inflammatory response at 1 and 3 days, less keratocyte apoptosis in the ablated anterior corneal stroma at 1, 3, and 7 days (P < .001), and less stromal fibroblast cellularity and epithelial hyperplasia at 12 weeks.

CONCLUSIONS

Amniotic membrane matrix introduced at an early stage of the corneal wound healing process effectively reduced corneal haze induced by excimer laser photoablation in rabbits. Studies linking suppression of apoptosis in the acute wound-healing process with reduction of subsequent corneal scarring may have useful clinical applications.

Temporal expression of nitric oxide synthase isoforms in healing Achilles tendon

We investigated the temporal expressions of the three nitric oxide synthase (NOS) isoforms by semi-quantitative polymerase chain reaction (PCR) assays and by immunoblot analysis, following Achilles tendon transection in rats. Four days after injury, there were increases in the steady-state levels of mRNA for all three NOS isoforms, with peaks for the inducible isoform (iNOS) (23-fold increase) at day 4, the endothelial isoform (eNOS) (24-fold increase) at day 7 and the neuronal isoform (bNOS) (seven-fold increase) at day 21. The temporal expression of NOS isoforms at a protein level was consistent with the results at the mRNA level. We have previously shown a five-fold increase in the NOS activity, as detected by 3H-arginine to 3H-citrulline conversion, at day 7 postinjury. These findings indicate that all three NOS isoforms are expressed during tendon healing with differential expression patterns during the various phases of tendon healing. These findings may prove clinically relevant with respect to strategies for regulating tendon healing.

Identification and characterization of TUP1-regulated genes in Candida albicans

TUP1 encodes a transcriptional repressor that negatively controls filamentous growth in Candida albicans. Using subtractive hybridization, we identified six genes, termed repressed by TUP1 (RBT), whose expression is regulated by TUP1. One of the genes (HWP1) has previously been characterized, and a seventh TUP1-repressed gene (WAP1) was recovered due to its high similarity to RBT5. These genes all encode secreted or cell surface proteins, and four out of the seven (HWP1, RBT1, RBT5, and WAP1) encode putatively GPI-modified cell wall proteins. The remaining three, RBT2, RBT4, and RBT7, encode, respectively, an apparent ferric reductase, a plant pathogenesis-related protein (PR-1), and a putative secreted RNase T2. The expression of RBT1, RBT4, RBT5, HWP1, and WAP1 was induced in wild-type cells during the switch from the yeast form to filamentous growth, indicating the importance of TUP1 in regulating this process and implicating the RBTs in hyphal-specific functions. We produced knockout strains in C. albicans for RBT1, RBT2, RBT4, RBT5, and WAP1 and detected no phenotypes on several laboratory media. However, two animal models for C. albicans infection, a rabbit cornea model and a mouse systemic infection model, revealed that rbt1Delta and rbt4Delta strains had significantly reduced virulence. TUP1 appears, therefore, to regulate many genes in C. albicans, a significant fraction of which are induced during filamentous growth, and some of which participate in pathogenesis.

Pain After Epithelial Removal by Ethanol-assisted Mechanical Versus Transepithelial Excimer Laser Debridement

PURPOSE

To compare subjective pain responses between two techniques of epithelial removal prior to photorefractive keratectomy (PRK) treatment: ethanol-soaked pledget with mechanical debridement of the epithelium versus excimer laser transepithelial ablation.

METHODS

Nine patients underwent bilateral PRK. Each had the epithelium in one eye debrided by placing a pledget soaked in 20% ethanol on the cornea for 2 minutes followed by gentle scraping with a blade. The epithelium in the other eye was removed by transepithelial phototherapeutic keratectomy (PTK) treatment. For each eye, PRK was initiated immediately after removal of the epithelium. On postoperative day one, each patient was asked to rate the level of pain suffered over the last 24 hours on a scale of 0 (minimal) to 10 (maximal). Data were analyzed in a masked fashion.

RESULTS

Postoperative day one average pain level in the ethanol-assisted mechanically debrided eyes was 3.0 +/- 2.5 and in the transepithelial PTK eyes was 6.8 +/- 1.8. The difference was statistically significant by Student's t-test (P < .01). All epithelial defects healed within 3 days with no clinically significant difference in healing time between the two techniques.

CONCLUSION

In preparation for PRK, ethanol-assisted mechanical debridement of the epithelium caused significantly less postoperative pain than epithelial removal using the excimer laser.

Recurrent fungal keratitis and endophthalmitis

PURPOSE

To report a case of recurrent fungal sclerokeratitis and endophthalmitis with a very successful outcome due to aggressive combined surgical and medical therapy. To discuss the management of this potentially devastating infection.

METHODS

A 65-year-old man presented with 6 months of left eye redness and irritation after injury from organic matter propelled from an airboat. Initially, he had been treated with foreign body removal, antibiotics, and steroids. He was diagnosed with reactive sclerokeratitis at presentation and was treated with steroids. However, when he did not improve, cultures were obtained and Acremonium species filamentous fungi was identified. Despite treatment with appropriate topical and systemic antifungals, his fungal sclerokeratitis progressed to endophthalmitis. Two therapeutic penetrating keratoplasties (PKs) with iridectomy and intraocular amphotericin B were necessary to eradicate the fungal infection.

RESULTS

Visual acuity was restored to 20/25-3 with correction 9 months after initial presentation. There was no recurrence of fungal infection after the second therapeutic PK.

CONCLUSION

The possible reasons for recurrence of fungal infection are discussed. The role of timely and aggressive medical and surgical intervention for fungal sclerokeratitis and endophthalmitis in restoring excellent vision is emphasized.

Genotype dependent and cigarette specific effects on endothelial nitric oxide synthase gene expression and enzyme activity

We explored the interactive effects of endothelial nitric oxide synthase (eNOS) genotypes and cigarette smoking on protein levels and enzyme activity in 33 postpartum placentas. Whilst the eNOS protein levels were lower in the rare allele (0.48+/-0.11, n=9 vs. 1. 05+/-0.10, n=24, P<0.01), the eNOS enzyme activity was about 7-fold higher in the rare allele (4556.2+/-255.4 vs. 621.8+/-180.5 cpm/mg/min, P<0.01). Smokers had lower eNOS protein levels (1.07+/-0. 09 vs. 0.50+/-0.19, P<0.05) in both alleles. It reduced the eNOS activities only in the rare allele (non-smokers: 6143.8+/-251.2, n=5, smokers: 2968.5+/-259.4, n=4, 52% reduction, P<0.01). We conclude that associations between eNOS polymorphism and protein levels and enzyme activities are modifiable by smoking, the effects of smoking are dependent on the eNOS genotypes.

Differences in virulence between two Candida albicans strains in experimental keratitis

PURPOSE

To study the differences in disease caused by two wild-type strains of Candida albicans in a model of contact lens-facilitated keratitis in rabbits.

METHODS

Two strains, SC5314 and VE175, were examined. Standardized inocula were placed on the debrided corneal surface of one eye in Dutch belted rabbits and covered with a contact lens. A temporary tarsorrhaphy was opened after 24 hours with removal of the contact lens. Six days later, corneas were photographed and animals killed. Corneas were bisected with one half for quantitative isolate recovery and the other for stromal penetration by hyphae.

RESULTS

Strain SC5314 was significantly more virulent. The mean hyphal penetration into the cornea was 24.4% +/- 8.5% of the corneal thickness, and in three of six corneas hyphae penetrated through the entire cornea. In contrast, for VE175, the mean hyphal penetration was 2.6% +/- 1.2%. The difference between these two strains was statistically significant (P = 0.0297). Hyphae did not penetrate into the deep layers of the cornea in any of the six rabbits infected with VE175. The grading of clinical disease was consistent with histology, in that strain SC5314 caused more severe infection than VE175 and the difference was statistically significant (P = 0.0048). There was no difference in isolate recovery.

CONCLUSIONS

Wild-type strains of C. albicans can differ significantly in virulence as measured by depth of fungal invasion into corneas and clinical evaluation of infection. Further characterization of the intrinsic genetic differences between such strains may help identify factors responsible for fungal virulence.

[Insect-resistant transgenic poplar expressing AaIT gene]

Insect-specific scorpion neurotoxin AaIT gene inserted into a binary vector was transferred into a hybrid poplar clone N-106(P. deltoides x P. simonii) growing in the Southern of China. We obtained sixty-two regenerated plants by Agrobacterium tumefaciens transferring system. PCR and PCR-Southern analysis showed that AaIT gene was incorporated into the genome of some recovered poplar plants. One of the transformed plants named A5 was significantly resistant to feeding by first instar larvae of Lymantria dispar, compared with the untransformed control plant. It caused a decrease in leaf consumption by larvae, a lower larval weight gain and a higher larval motality rate of Lymantria dispar. ELISA analysis proved that AaIT gene was expressed in this transfomed poplar plant.

Nitric oxide modulates fracture healing

The role of the messenger molecule nitric oxide has not been evaluated in fracture healing. NO is synthesized by three kinds of nitric oxide synthase (NOS): inducible NOS (iNOS), endothelial (eNOS), and neuronal (bNOS). We evaluated the role of these enzymes in a rat femur fracture-healing model. There was no messenger RNA (mRNA) expression, immunoreactivity, or enzymatic activity for NOS in unfractured femoral cortex. After fracture, however, mRNA, protein, and enzymatic activity for iNOS were identified in the healing rat femoral fracture callus, with maximum activity on day 15. The mRNA expression for eNOS and bNOS was induced slightly later than for iNOS, consistent with a temporal increase in calcium-dependent NOS activity that gradually increased up to day 30. mRNA expression for the three NOS isoforms also was found in six of six human fracture callus samples. To study the effect of suppression of NO synthesis on fracture healing, an experimental group of rats was fed an NOS inhibitor, L-nitroso-arginine methyl ester (L-NAME), and the control group was fed its inactive enantiomer, D-nitroso-arginine methyl ester (D-NAME). An 18% (p < or = 0.01) decrease in cross-sectional area and a 45% (p < or = 0.05) decrease in failure load were observed in the NOS-inhibited group on day 24 after fracture. Furthermore, the effect of NO supplementation to fracture healing was studied by delivering NO to the fracture site using carboxybutyl chitosan NONOate locally. On day 17 after fracture, there was a 30% (p < or = 0.05) increase in cross-sectional area in the NO-donor group compared with the NOS inhibition group. These results show for the first time that NO is expressed during fracture healing in rats and in humans, that suppression of NOS impairs fracture healing, and that supplementation of NO can reverse the inhibition of healing produced by NOS inhibitors.

Staphylococcus aureus stimulates inducible nitric oxide synthase in articular cartilage

OBJECTIVE

To determine if Staphylococcus aureus stimulates the L-arginine-nitric oxide (NO) synthase pathway in articular cartilage.

METHODS

A heat-killed and sonicated (denatured) S. aureus preparation was added to cultures of bovine articular cartilage. NO production was measured as accumulated nitrite in the culture medium and by the NO synthase-dependent conversion of 3H-L-arginine to 3H-L-citrulline in cartilage homogenates. Inducible NO synthase (iNOS) messenger RNA (mRNA) expression was analyzed by Northern blot. Proteoglycan synthesis was measured by 35SO4 incorporation into glycosaminoglycan.

RESULTS

Nitrite accumulation and 3H-L-citrulline formation in cartilage were elevated by denatured S. aureus (compared with unstimulated control cartilage) and inhibited by the NO synthase inhibitor N(G)-monomethyl-L-arginine. Northern blot analysis revealed increased iNOS mRNA expression in bovine chondrocytes in response to denatured S. aureus stimulation. Denatured S. aureus suppressed the accumulation of 35SO4-labeled macromolecules representing newly synthesized proteoglycans in bovine articular cartilage. The suppressed proteoglycan synthesis was due to the presence of NO.

CONCLUSION

These findings support the hypothesis that a component of S. aureus can stimulate iNOS in articular cartilage, and that NO generated from this enzyme down-regulates cartilage matrix proteoglycan synthesis.

On the role of kerato-epithelin in the pathogenesis of 5q31-linked corneal dystrophies

PURPOSE

Recently, the authors identified a gene, BIGH3, in which different mutations cause a group of hereditary corneal dystrophies: lattice type I and IIIA (CDLI and CDLIIIA), granular Groenouw type I (CDGGI), Avellino (CDA), and Reis-Bücklers' (CDRB). All these disorders are characterized by the progressive accumulation of corneal deposits with different structural organization. Experiments were conducted to determine the role of kerato-epithelin (KE), the product of BIGH3, in the pathogenesis of the diseases.

METHODS

KE-15 and KE-2, two rabbit antisera raised against peptides from the 69-364 and 426 - 682 amino acid regions of KE respectively, were used for immunohistology of the corneas obtained after keratoplasty in six CDLI patients, three CDGGI patients, and one CDA patient.

RESULTS

The nonamyloid deposits observed in CDGGI stained intensively with KE-15 and KE-2, whereas the amyloid deposits in all analyzed CDLI corneas reacted to KE-2 but not to KE-15. In the CDA cornea, where amyloid and nonamyloid inclusions were present, positive staining with both antisera was observed.

CONCLUSIONS

Pathologic amyloid and nonamyloid deposits observed in CDLI, CDGGI-, and CDA-affected corneas are caused by KE accumulation. Different staining patterns of amyloid and nonamyloid deposits observed with antibodies against the amino and carboxyl termini of KE suggest that two mechanisms of KE misfolding are implicated in the pathogenesis of 5q31-linked corneal dystrophies.

Contact lens-induced infection--a new model of Candida albicans keratitis

PURPOSE

A model of experimental keratomycosis was established that mimics human disease in which the only fungi present are those that are actively growing within the cornea.

METHODS

Dutch-belted rabbits received a subconjunctival injection of triamcinolone acetonide to one eye. One day later the epithelium was removed from the central cornea and a standardized inoculum of Candida albicans blastoconidia was placed on the corneal surface and covered with a contact lens. The lids were closed with a lateral tarsorrhaphy. After 24 hours, the lid sutures and contact lens were removed. Five days later the animals were killed, and their corneas were subjected to separate isolate recovery and histology studies. A group of similarly infected rabbits without corticosteroid injection served as controls.

RESULTS

Both groups developed invasive corneal disease. Although isolate recovery was not significantly different from corticosteroid-treated rabbits compared with controls, fungal biomass was increased. Hyphal invasion was limited to the anterior cornea in control eyes, but penetrated deep stroma in most of the corticosteroid-treated rabbits.

CONCLUSIONS

Invasive corneal disease can be established with a surface inoculum. Corticosteroid administration increased corneal penetration of hyphae. Quantitative isolate recovery is not a reliable measure of the fungal load within the cornea.

Mutation hot spots in 5q31-linked corneal dystrophies

Mutations in the BIGH3 gene on chromosome 5q31 cause four distinct autosomal dominant diseases of the human cornea: granular (Groenouw type I), Reis-Bücklers, lattice type I, and Avellino corneal dystrophies. All four diseases are characterized by both progressive accumulation of corneal deposits and eventual loss of vision. We have identified a specific recurrent missense mutation for each type of dystrophy, in 10 independently ascertained families. Genotype analysis with microsatellite markers surrounding the BIGH3 locus was performed in these 10 families and in 5 families reported previously. The affected haplotype could be determined in 10 of the 15 families and was different in each family. These data indicate that R555W, R124C, and R124H mutations occurred independently in several ethnic groups and that these mutations do not reflect a putative founder effect. Furthermore, this study confirms the specific importance of the R124 and R555 amino acids in the pathogenesis of autosomal dominant corneal dystrophies linked to 5q.