A novel initialization method for nonnegative matrix factorization and its application in component recognition with three-dimensional fluorescence spectra

Nonnegative matrix factorization has been widely used in many areas and has been applied for component recognition with three dimensional fluorescence spectra recently. However, nonnegative matrix factorization is a nonconvex programming in the iteration process, thus the solution is dependent on the initial values and consequently not unique. Up to now, an effective global convergent algorithm is still absent. In this work, we propose an initialization scheme based on independent component analysis. Compared with other initialization schemes, the optimal solution of nonnegative matrix factorization based on independent component analysis is much better and it is demonstrated by typical experiments of component recognition with three-dimensional fluorescence spectra.

Identifying the related compounds using electrospray ionization tandem mass spectrometry: bromotyrosine alkaloids from marine sponge Psammaplysilla purpurea

We have investigated extracts of marine sponge Psammaplysilla purpurea during three collections from Mandapam (Tamil Nadu, India) and Okha (Gujarat, India) and indentified two new bromotyrosine alkaloids, purpurealidin I (7) and J (8) using electrospray ionization tandem mass spectrometry (ESI-MS/MS). This sponge has tremendous chemical diversity of bromotyrosine alkaloids. Here we have used the proteomics approach in identifying related bromotyrosine alkaloids based on the predicated mass fragmentation pattern. The focus is on the examination of detailed product ion spectra of six known compounds that allowed identification of new compounds based on its mass fragmentation pattern. The isotopic pattern of the peaks for protonated molecules indicated the number of bromine atoms present in the molecule. During MS/MS studies, the most prominent product ion peak is for the presence of side chain propane with either free NH(2) or NHMe or Nme(2). The cleavage at C-C bond between oxime-amide carbonyl and amide-phenoxy moiety also gave characteristic product ions. The ESI-MS spectra for all three collections show that the bromotyrosine metabolites vary during different season and also geographical location. Although, some common metabolites were observed during the three collections. Thus, ESI-MS/MS is a method of choice in identifying the related compounds.

The role of amino acids in spina bifida

Our objective was to measure amniotic fluid amino acid concentrations in pregnant women diagnosed as having fetuses with spina bifida in the second trimester of pregnancy. Fifteen pregnant women who had fetuses with spina bifida detected by ultrasonography (spina bifida group) in the second trimester and 19 women who had abnormal triple screenings indicating an increased risk for Down's syndrome but had healthy fetuses (control group) were enrolled in the study. Amniotic fluid was obtained by amniocentesis. The chromosomal analysis of the study and control groups was normal. Levels of free amino acids were measured in amniotic fluid samples using EZ: fast kits (EZ: fast GC/FID free (physiological) amino acid kit) by gas chromatography (Focus GC AI 3000 Thermo Finnigan analyzer). The mean levels of alanine, cystathionine, cysteine, phenylalanine, tryptophane, and tyrosine amino acids were found to be significantly higher in fetuses of the control group than in the spina bifida group (p<0.05). The detection of significantly higher amino acid concentrations in the amniotic fluid of healthy fetuses suggests loss of amino acids from the fetus through the spinal cord may contribute to the etiology of spina bifida.

Continuous-flow step gradient mass spectrometry based method for the determination of kinetic parameters of immobilized mushroom tyrosinase in equilibrating conditions: comparison with free enzyme

A mass spectrometry (MS)-based methodology for enzymatic assay in equilibrium conditions was designed and evaluated. This on-line assay involves the introduction of a continuous-flow step gradient (CFSG) of a substrate solution in the column containing immobilized enzyme and the simultaneous tracking of the product formation. We showed that the constant concentration of substrate in the entire bioreactor for an appropriate duration ensures the equilibration of the studied enzyme (mushroom tyrosinase). Under these conditions, it was demonstrated also that the kinetic and enzymatic parameters (Michaelis-Menten constant, K(M) , the maximal specific activity, SA(max)) are independent of the flow rate of the mobile phase. The feasibility of the mentioned approach for inhibitory tests was also investigated. The coupling of the mass spectrometer to the bio-reactor allows the selective monitoring of the enzymatic reaction products and increases their detection level. Very high sensitivity, 500 pmol/min/column, and selective monitoring of the products of the enzymatic reaction are allowed by MS detection. The methodology developed here constitutes a sensitive analytical tool to study enzymes requiring long equilibration times.

Habitually exercising older men do not demonstrate age-associated vascular endothelial oxidative stress

We tested the hypothesis that older men who perform habitual aerobic exercise do not demonstrate age-associated vascular endothelial oxidative stress compared with their sedentary peers. Older exercising men (n=13, 62±2 years) had higher (P<0.05) physical activity (79±7 vs. 30±6 MET hours per week) and maximal exercise oxygen consumption (42±1 vs. 29±1 mL kg(-1) per minute) vs. sedentary men (n=28, 63±1 years). Brachial artery flow-mediated dilation (FMD), a measure of vascular endothelial function, was greater (P<0.05) in the exercising vs. sedentary older men (6.3±0.5 vs. 4.9±0.4%Δ) and not different than young controls (n=20, 25±1 years, 7.1±0.5%Δ). In vascular endothelial cells sampled from the brachial artery, nitrotyrosine, a marker of oxidative stress, was 51% lower in the exercising vs. sedentary older men (0.38±0.06 vs. 0.77±0.10 AU). This was associated with lower endothelial expression of the oxidant enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (p47(phox) subunit, 0.33±0.05 vs. 0.61±0.09 AU) and the redox-sensitive transcription factor nuclear factor kappa B (NFκB) (p65 subunit, 0.36±0.05 vs. 0.72±0.09 AU). Expression of the antioxidant enzyme manganese superoxide dismutase (SOD) (0.57±0.13 vs. 0.30±0.04 AU) and activity of endothelium-bound extracellular SOD were greater (6.4±0.5 vs. 5.0±0.6 U mL(-1) per minute) in the exercising men (both P<0.05), but differences no longer were significant after correcting for adiposity and circulating metabolic factors. Overall, values for the young controls differed with those for the sedentary, but not the exercising older men. Older men who exercise regularly do not demonstrate vascular endothelial oxidative stress, and this may be a key molecular mechanism underlying their reduced risk of cardiovascular diseases.

Proteomic characterisation of hydrothermal redox damage

BACKGROUND

Peptide and protein damage contributes to the loss of quality and value in protein-based food and textile products as well as to the degeneration of biological tissues such as hair and skin. The effects of elevated temperature on such substrates at the molecular level are, however, relatively unknown. This paper examines the response of peptides and proteins to hydrothermal damage using mass spectrometry and reports the location of molecular markers of hydrothermal damage within wool proteins.

RESULTS

The hydrothermal exposure of model peptides containing the oxidatively sensitive residues tryptophan and tyrosine revealed the formation of a number of products such as hydroxytryptophan and dihydrophenylalanine. A variety of degradation products were also observed in intermediate filament proteins, including products arising from deamidation and from oxidation of histidine, tyrosine and tryptophan residues.

CONCLUSION

The products observed to form during hydrothermal exposure indicated the involvement of reactive oxygen species. Molecular markers were identified within a proteinaceous system to allow the evaluation of damage type or severity. These findings have important implications for the thermal processing of foods and textiles.

Simultaneous identification of tyrosine phosphorylation and sulfation sites utilizing tyrosine-specific bromination

Tyrosine phosphorylation and sulfation play many key roles in the cell. Isobaric phosphotyrosine and sulfotyrosine residues in peptides were determined by mass spectrometry using phosphatase or sulfatase to remove the phosphate or the sulfate group. Unique Br signature was introduced to the resulting tyrosine residues by incubation with 32% HBr at -20 °C for 20 min. MS/MS analysis of the brominated peptide enabled unambiguous determination of the phosphotyrosine and the sulfotyrosine sites. When phosphotyrosine and sulfotyrosine as well as free tyrosine were present in the same peptide, they could be determined simultaneously using either phosphatase or sulfatase following acetylation of the free tyrosine.

A digital microfluidic method for dried blood spot analysis

Blood samples stored as dried blood spots (DBSs) are emerging as a useful sampling and storage vehicle for a wide range of applications. Unfortunately, the surging popularity of DBS samples has not yet been accompanied by an improvement in automated techniques for extraction and analysis. As a first step towards overcoming this challenge, we have developed a prototype microfluidic system for quantification of amino acids in dried blood spots, in which analytes are extracted, mixed with internal standards, derivatized, and reconstituted for analysis by (off-line and in-line) tandem mass spectrometry. The new method is fast, robust, precise, and most importantly, compatible with automation. We propose that the new method can potentially contribute to a new generation of analytical techniques for quantifying analytes in DBS samples for a wide range of applications.

Optimization of the structure-switching aptamer-based fluorescence polarization assay for the sensitive tyrosinamide sensing

In this paper, a structure-switching aptamer assay based on a fluorescence polarization (FP) signal transduction approach and dedicated to the L-tyrosinamide sensing was described and optimized. A fluorescently labelled complementary strand (CS) of the aptamer central region was used as a probe. The effects of critical parameters such as buffer composition and pH, temperature, aptamer:CS stoichiometry, nature of the dye (Fluorescein (F) or Texas Red (TR)) and length of the CS (15-, 12-, 9- and 6-mer) on the assay analytical performances were evaluated. Under optimized experimental conditions (10 mM Tris-HCl, 5 mM MgCl(2) and 25 mM NaCl, pH 7.5 temperature of 22°C and stoichiometry 1:1), the results showed that, for a 12-mer CS, the F dye moderately increased the method sensitivity in comparison to the TR label. The F labelled 9-mer CS, however, did not allow the hybrid formation with the functional nucleic acid, thus emphasizing the importance of the nature of the fluorophore. In contrast, the same 9-mer CS labelled with the TR dye was able to effectively associate with the aptamer and was easily displaced upon target binding as demonstrated by a significant improvement of the sensitivity and a detection limit of 250 nM, comparable to those reported with direct aptasensing methods. The present study demonstrates that not only the CS length but also the nature of the dye played a preponderant role in the performance of the structure-switching aptamer assay, highlighting the importance of interdependently controlling these two factors for an optimal FP-based sensing platform.

[Oxidative stress in soleus and extensor digitorum longus (EDL) muscles of spontaneously hypertensive rats]

Systemic diseases affect skeletal muscle, and inflammation and oxidative stress are some of the involved mechanisms. There is scarce information about the effects of essential hypertension on skeletal muscle. The soleus and extensor digitorum longus (EDL) muscles of spontaneously hypertensive rats (SHR) were studied compared to control Wistar Kyoto (WKY) rats. The levels of nitrite and nitrate in micromol/mg-protein; endothelial (eNOS), neuronal (nNOS), and inducible (iNOS) nitric oxide synthases, nitrotyrosine and tumour necrosis factor alpha (TNF-alpha) in ng/mg-protein were determined. Compared with controls, the SHR showed increased levels of nitrotyrosine (soleus 24.4 +/- 5.0 vs. 3.3 +/- 0.3, p<0.001; EDL 20.2 +/- 4.3 vs. 4.5 +/- 0.4, p<0.0037), iNOS (soleus 26.6 +/- 3.7 vs. 8.3 +/- 0.9; EDL 21.3 +/- 3.7 vs. 11.0 +/- 0.8, both p<0.0001) and TNF-alpha (soleus 2.2 +/- 0.5 vs. 0.6 +/- 0.1, p<0.05; EDL 1.9 +/- 0.2 vs. 0.6 +/- 0.1, p<0.02). A decrease of eNOS was found in soleus muscle (20.6 +/- 1.4 vs. 30.3 +/- 1.2, p<0.00001); of nNOS (soleus 16.8 +/- 1.4 vs. 20.7 +/- 1.8, p< 0.05; EDL 13.6 +/- 1.3 vs. 21.9 +/- 1.8, p<.005) and nitrite in EDL (5.8 +/- 0.3 vs. 7.1 +/- 0.5, p<0.026).There was a positive correlation between TNF-alpha vs. nitrotyrosine in soleus (r=0.798; p<0.031) and a tendency in EDL (r=0.739; p=0.059); iNOS vs. nitrotyrosine (soleus: r=0.908; p<0.0001; EDL: r=0.707; p<0.01), a tendency between TNF-alpha and iNOS (EDL: r=0.736; p<0.059); and a negative correlation between eNOS vs. nitrotyrosine in soleus muscle (r=-0.816; p<0.0012). In conclusion, in skeletal muscles of SHR an inflammatory process was found evidenced by the increase in TNF-alpha, nitrotyrosine and iNOS. The decreased levels of constitutive synthases, together with the higher level of iNOS, are indicative of endothelial dysfunction.

Inhibition of nitric oxide synthase uncoupling by sepiapterin improves left ventricular function in streptozotocin-induced diabetic mice

1. Uncoupling of nitric oxide synthase (NOS) has been implicated in the pathogenesis of left ventricular (LV) dysfunction in diabetes mellitus. In the present study, we investigated the role of NOS uncoupling in oxidative/nitrosative stress and LV dysfunction in the diabetic mouse heart. 2. Diabetes was induced in wild-type (WT), endothelial (e) NOS knockout (eNOS(-/-)), inducible (i) NOS knockout (iNOS(-/-)) and neuronal (n) NOS knockout (nNOS(-/-)) mice by streptozotocin (STZ) treatment. 3. In the diabetic heart, iNOS, but not eNOS or nNOS, expression was increased. Levels of malondialdehyde (MDA), 4-hydroxy-noneal (HNE) and nitrotyrosine (NT), as markers of oxidative/nitrosative stress, were increased in the diabetic mouse heart, but the increase in oxidative/nitrosative stress was significantly repressed in the iNOS(-/-) diabetic mouse heart. Levels of nitrite and nitrate (NO(x)), as an index of nitric oxide, bioavailability were significantly decreased in the iNOS(-/-) diabetic mouse heart. 4. Oral administration of sepiapterin (10 mg/kg per day), a precursor of tetrahydrobiopterin (BH(4)), significantly increased BH(4) and the BH(4)/BH(2) ratio in diabetic mouse heart. Similarly, sepiapterin inhibited the formation of HNE, MDA and NT in diabetic hearts from all three genotypes, but the increase in NO(x) following sepiapterin treatment was significantly attenuated in the iNOS(-/-) diabetic mouse heart. Percentage fractional shortening (FS), evaluated by echocardiography, decreased significantly in all genotypes of diabetic mice. Sepiapterin significantly increased percentage FS in diabetic mice, except in iNOS(-/-) mice. 5. These results suggest that sepiapterin inhibits uncoupling of NOS and improves LV function presumably by increasing iNOS-derived nitric oxide in the diabetic heart.

Brominated tyrosine and polyelectrolyte multilayer analysis by laser desorption vacuum ultraviolet postionization and secondary ion mass spectrometry

The small molecular analyte 3,5-dibromotyrosine (Br(2)Y) and chitosan-alginate polyelectrolyte multilayers (PEM) with and without adsorbed Br(2)Y were analyzed by laser desorption postionization-mass spectrometry (LDPI-MS). LDPI-MS using a 7.87 eV laser and tunable 8-12.5 eV synchrotron vacuum ultraviolet (VUV) radiation found that desorption of clusters from Br(2)Y films allowed detection by ≤8 eV single photon ionization. Thermal desorption and electronic structure calculations determined the ionization energy of Br(2)Y to be ~8.3 ± 0.1 eV and further indicated that the lower ionization energies of clusters permitted their detection at ≤8 eV photon energies. However, single photon ionization could only detect Br(2)Y adsorbed within PEMs when using either higher photon energies or matrix addition to the sample. All samples were also analyzed by 25 keV Bi(3)(+) secondary ion mass spectrometry (SIMS), with the negative ion spectra showing strong parent ion signal which complemented that observed by LDPI-MS. However, the negative ion SIMS appeared strongly dependent on the high electron affinity of this specific analyte and the analyte's condensed phase environment.

[Study of tyrosine online fluorescence spectrum under high pressure]

The effect of pressure on fluorescence of tyrosine (Tyr) and Tyr in different concentration of Cu2+ was investigated. The results showed that Tyr fluorescence intensity was enhanced with increasing pressure in the absence of Cu2+, with the fluorescence intensity increasing by about 9% when the pressure reached 60 MPa. Furthermore, Tyr fluorescence quenched by Cu2+ and the quenching became stronger when the concentration of Cu2+ was higher. The effect of pressure on the fluorescence of Tyr was different under various Cu2+ concentrations. When Cu2+ concentration was lower, the fluorescence intensity increased relatively weakly (under 60 MPa and [Copper ion]/[Tyr] = 1, fluorescence intensity increased by 14.4%) and vice versa, the fluorescence intensity increased relatively strongly (under 60 MPa and [Copper ion]/[Tyr] = 40, fluorescence intensity increased by 38.4%).

Local and cardiorenal effects of periodontitis in nitric oxide-deficient hypertensive rats

OBJECTIVE

in this study we have assessed the renal and cardiac consequences of ligature-induced periodontitis in both normotensive and nitric oxide (NO)-deficient (L-NAME-treated) hypertensive rats.

MATERIALS AND METHODS

oral L-NAME (or water) treatment was started two weeks prior to induction of periodontitis. Rats were sacrificed 3, 7 or 14 days after ligature placement, and alveolar bone loss was evaluated radiographically. Thiobarbituric reactive species (TBARS; a lipid peroxidation index), protein nitrotyrosine (NT; a marker of protein nitration) and myeloperoxidase activity (MPO; a neutrophil marker) were determined in the heart and kidney.

RESULTS

in NO-deficient hypertensive rats, periodontitis-induced alveolar bone loss was significantly diminished. In addition, periodontitis-induced cardiac NT elevation was completely prevented by L-NAME treatment. On the other hand L-NAME treatment enhanced MPO production in both heart and kidneys of rats with periodontitis. No changes due to periodontitis were observed in cardiac or renal TBARS content.

CONCLUSIONS

in addition to mediating alveolar bone loss, NO contributes to systemic effects of periodontitis in the heart and kidney.

Plant cell-wall cross-links by REDOR NMR spectroscopy

We present a new method that integrates selective biosynthetic labeling and solid-state NMR detection to identify in situ important protein cross-links in plant cell walls. We have labeled soybean cells by growth in media containing l-[ring-d(4)]tyrosine and l-[ring-4-(13)C]tyrosine, compared whole-cell and cell-wall (13)C CPMAS spectra, and examined intact cell walls using (13)C{(2)H} rotational echo double-resonance (REDOR) solid-state NMR. The proximity of (13)C and (2)H labels shows that 25% of the tyrosines in soybean cell walls are part of isodityrosine cross-links between protein chains. We also used (15)N{(13)C} REDOR of intact cell walls labeled by l-[ε-(15)N,6-(13)C]lysine and depleted in natural-abundance (15)N to establish that the side chains of lysine are not significantly involved in covalent cross-links to proteins or sugars.

Identifying peroxidases and their oxidants in the early pathology of cystic fibrosis

We aimed to determine whether myeloperoxidase (MPO) is the main peroxidase present in the airways of children with cystic fibrosis (CF) and to assess which oxidants it produces and whether they are associated with clinical features of CF. Children with CF (n=54) and without CF (n=16) underwent bronchoscopy and bronchoalveolar lavage (BAL) for assessment of pulmonary infection and inflammation. BAL fluid was analyzed for MPO, halogenated tyrosines as markers of hypohalous acids, thiocyanate, and protein carbonyls. MPO was the only peroxidase detected in BAL samples from children with CF and its concentration was markedly higher than in controls. Levels of 3-chlorotyrosine and 3-bromotyrosine in proteins were higher in the CF group. They correlated with neutrophils and MPO. The concentration of thiocyanate in BAL samples was below 1μM. Protein carbonyl levels correlated with MPO and halogenated tyrosines in patients with CF. Levels of MPO and halogenated tyrosines were higher in children with infections, especially Pseudomonas aeruginosa, and in the presence of respiratory symptoms. They also correlated with the Kanga clinical score. Our findings suggest that MPO produces hypobromous acid as well as hypochlorous acid in the airways of children with CF and that these oxidants are involved in the early pathogenesis of CF.

Inhibition of inducible nitric oxide synthase prevents graft injury after transplantation of livers from rats after cardiac death

This study investigated the roles of inducible nitric oxide synthase (iNOS) in the failure of rat liver grafts from cardiac death donors (GCDD). Livers were explanted after 30-minute aorta clamping and implanted after 4-hour storage in University of Wisconsin solution. The iNOS expression increased slightly in grafts from non-cardiac death donors (GNCDD) but markedly in GCDD. Serum nitrite and nitrate and hepatic 3-nitrotyrosine adducts, indicators of NO and peroxynitrite production, respectively, were substantially higher after transplantation of GCDD than GNCDD. Production of reactive nitrogen species (RNS) was largely blocked by 1400W (N-[1-naphthyl]ethylenediamine dihydrochloride; 5 μM), a specific iNOS inhibitor. Alanine aminotransferase release, bilirubin, necrosis, and apoptosis were 6.4-fold, 6.5-fold, 2.3-fold, and 2.7-fold higher, respectively, after transplantation of GCDD than GNCDD. The inhibitor 1400W effectively blocked these alterations and also increased survival of GCDD to 80% from 33%. Increased RNS production and failure of GCDD were associated with activation of c-Jun-N-terminal kinase (JNK), an effect that was blocked by inhibition of iNOS. Inhibition of JNK also improved the outcome after transplantation of GCDD. Together, the data indicate that iNOS increases substantially in GCDD, leading to RNS overproduction, JNK activation, and more severe graft injury. Inhibitors of iNOS are suggested as effective therapies to improve the outcome after transplantation of GCDD.

Optical determination of L-tyrosine based on eggshell membrane immobilized tyrosinase

An optical biosensor based on the eggshell membrane immobilized tyrosinase is described for the detection of L-tyrosine (L-Tyr). The detection scheme was based on the measurement of absorption value of color adduct resulting from the reaction of 3-methyl-2-benzothiazolinone hydrazone and dopa-quinone produced from the enzymatic oxidation of L-Tyr. The prepared biosensor demonstrated optimum activity at pH 7, optimum temperature range of 20-40 degrees C and a linear response for the L-Tyr concentration in range of 5-200 microM. It also showed good operation stability for repeated measurements (over 300 times) and storage stability after it had been kept at 4 degrees C for 3 months.

Determination of L-tyrosine by beta-cyclodextrin sensitized fluorescence quenching method

A novel beta-cyclodextrin (beta-CD) sensitized fluorescence quenching method for the determination of l-tyrosine (l-Tyr) with Mo(VI)-phenyl-fluorone (PF) as a fluorescence probe has been developed. The fluorescence intensity of Mo(VI)-PF-beta-CD was diminished as the l-tyrosine was added, the fluorescence quenching value DeltaF=F(beta-CD-Mo-PF)-F(beta-CD-Mo-PF-l-Tyr) was enhanced in beta-CD and there was a linear relationship between the DeltaF and the concentration of l-Tyr. Under the optimal conditions, the linear range of calibration curve for the determination of l-tyrosine was 0.3-20.0microgmL(-1); the detection limit was 0.094microgmL(-1). NaOH (10%, w/v) is the best reagent of hydrolysis in sample preparation. The sensitized mechanism of beta-cyclodextrin was discussed. The method has been applied to the determination of l-tyrosine in spirulina and food samples with satisfactory results.

[Identification of active components in Styela clava by HPLC-eSI-Tof/MS and the study on their HPLC specific chromatograms]

A new method based on high performance liquid chromatography-electrospray ionization time of flight-mass spectrometry (HPLC-ESI-TOF/MS) was developed for the rapid identification of active compounds in Styela clava and the development of its specific chromatograms. Samples were extracted by ultrasonic-assisted extraction, and the extraction conditions were optimized. The developed HPLC-ESI-TOF/MS method was used to identify the components in Styela clava extract, and a specific chromatogram based on HPLC analysis was established. Ten compounds in Styela clava extract have been primary identified by HPLC-ESI-TOF/MS on-line detection combined with literature review. The result of similarity evaluation for specific chromatograms indicated that the quality of different Styela clava samples was not entirely consistent. This method has the advantages of simple operation, rapid measurement and it is a powerful tool for identification of active components in Styela clava and its quality control.

[Effects of different severities of hypoxia-ischemia on brain injury in neonatal rats]

OBJECTIVE

To compare the features of brain injury in neonatal rats with different severities of hypoxia-ischemia (HI), and explore the role of microglial activation and cytokines.

METHODS

One hundred and twenty 7-day-old rats were randomized to three groups: sham control, mild HI, and severe HI. The rats in the HI groups were subjected to right carotid artery occlusion and 8% oxygen hypoxia exposure (40 minutes, 34.5 Celsius degree in the mild HI group; 65 minutes, 35.5 Celsius degree in the severe HI group). MRI, microtubule associated protein (MAP2) and TUNEL staining were used to confirm the severity of brain injury. Changes in expression of activated microglia (ED1) and signs of cytokine involvement or oxidative stress (TNF-alpha, nitrotyrosine) were assessed immunohistochemically.

RESULTS

In the mild HI group, MRI scans demonstrated increased T2 values in the ipsilateral subcortical white matter and a slight loss of T2 values in the cortex, corresponding to a medium loss of MAP2 in the ipsilateral cortex. There was an increase in the number of TUNEL positive cells compared to the control group within the subcortical white matter. In the severe HI group, the T2 value increased in the majority of the hemisphere, corresponding to a severe loss of staining for MAP2 in the ispilateral hemisphere. The number of TUNEL positive cells significantly increased in the ipsilateral cortex and white matter. In the mild HI group, ED1, TNF-alpha and nitrotyrosine expression increased only in the acute stage and was only observed in subcortical white matter. In contrast, after severe HI, the increase in ED1, TNF-alpha and nitrotyrosine expression was observed in the whole ipsilateral hemisphere and prolonged for weeks.

CONCLUSIONS

Following a mild HI a relatively selective white matter injury compares to the pannecrosis in the cortex and white matter following a severe HI. Microglial activation and over-expression of cytokines might contribute to the development of hypoxic-ischemic brain damage.

Resveratrol suppresses oxidative stress and inflammatory response in diethylnitrosamine-initiated rat hepatocarcinogenesis

Hepatocellular carcinoma (HCC), one of the most frequent and deadliest cancers, has been increasing considerably in the United States. In the absence of a proven effective therapy for HCC, novel chemopreventive strategies are urgently needed to lower the current morbidity and mortality of HCC. Recently, we have reported that resveratrol, a compound present in grapes and red wine, significantly prevents diethylnitrosamine (DENA)-induced liver tumorigenesis in rats, although the mechanism of action is not completely understood. In the present study, we have examined the underlying mechanisms of resveratrol chemoprevention of hepatocarcinogenesis by investigating the effects of resveratrol on oxidative damage and inflammatory markers during DENA-initiated rat liver carcinogenesis. There was a significant increase in hepatic lipid peroxidation and protein oxidation in carcinogen control animals compared with their normal counterparts at the end of the study (20 weeks). Elevated expressions of inducible nitric oxide synthase and 3-nitrotyrosine were noticed in the livers of the same animals. Dietary resveratrol (50-300 mg/kg) administered throughout the study reversed all the aforementioned markers in a dose-responsive fashion in rats challenged with DENA. Resveratrol also elevated the protein and mRNA expression of hepatic nuclear factor E2-related factor 2 (Nrf2). Results of the present investigation provide evidence that attenuation of oxidative stress and suppression of inflammatory response mediated by Nrf2 could be implicated, at least in part, in the chemopreventive effects of this dietary agent against chemically induced hepatic tumorigenesis in rats. The outcome of this study may benefit the development of resveratrol in the prevention and intervention of human HCC.

Attenuation of diabetes-induced renal dysfunction by multiple exposures to low-dose radiation is associated with the suppression of systemic and renal inflammation

Renal protection against diabetes-induced pathogenic injuries by multiple exposures to low-dose radiation (LDR) was investigated to develop a novel approach to the prevention of renal disease for diabetic subjects. C57BL/6J mice were given multiple low-dose streptozotocin (STZ; 6 x 60 [corrected] mg/kg) to produce a type 1 diabetes. Two weeks after diabetes onset, some of diabetic mice and age-matched nondiabetic mice were exposed whole body to 25 mGy X-rays every other day for 2, 4, 8, 12, and 16 wk. Diabetes caused a significant renal dysfunction, shown by time-dependent increase in urinary microalbumin (Malb) and decrease in urinary creatinine (Cre), and pathological changes, shown by significant increases in renal structural changes and PAS-positive staining. However, diabetes-induced renal dysfunction and pathological changes were significantly, albeit partially, attenuated by multiple exposures to LDR. Furthermore, LDR protection against diabetes-induced renal dysfunction and pathological changes was associated with a significant suppression of diabetes-increased systemic and renal inflammation, shown by significant increases in serum and renal TNFalpha, ICAM-1, IL-18, MCP-1, and PAI-1 contents. To further explore the mechanism by which LDR prevents diabetes-induced renal pathological changes, renal oxidative damage was examined by Western blotting and immunohistochemical staining for 3-nitrotyrosine and 4-hydroxynonenal. Significant increase in oxidative damage was observed in diabetic mice, but not diabetic mice, with LDR. Renal fibrosis, examined by Western blotting of connective tissue growth factor and Masson's trichrome staining, was also evident in the kidneys of diabetic mice but not diabetic mice with LDR. These results suggest that multiple exposures to LDR significantly suppress diabetes-induced systemic and renal inflammatory response and renal oxidative damage, resulting in a prevention of the renal dysfunction and fibrosis.

Association of F18-fluoro-ethyl-tyrosin uptake and 5-aminolevulinic acid-induced fluorescence in gliomas

PURPOSE

Malignant gliomas are highly infiltrative tumours with a fatal prognosis. F18-fluoroethyl-tyrosine (FET)-positron emission tomography (PET) often reveals a broader extension of these tumours compared with contrast-enhanced magnetic resonance imaging (MRI). Complete resection of the contrast-enhancing lesion is aspired. Fluorescence-guided resection using 5-aminolevulinic acid (5-ALA) improved the extent of resection. In this study, we investigated whether the FET uptake correlates with the extent of resection using 5-ALA-induced fluorescence.

METHODS

Thirteen patients who underwent preoperative and postoperative MRI, FET-PET and fluorescence-guided neuronavigated resection were included in this study. The areas in which intraoperative fluorescence terminated the resection were marked. After fusion of PET and MRI, the standardized uptake value (SUV) of FET related to normal brain (SUV(R)) was measured in regions of interest corresponding to resected and remaining tissue, respectively. Receiver-operating characteristic (ROC) curve analysis determined the optimal threshold of the relative SUV anticipating 5-ALA-induced fluorescence.

RESULTS

During resection a vivid fluorescence was present in all patients. Histology revealed glioblastomas in 11 cases, an anaplastic astrocytoma in one case and a low-grade astrocytoma in one case. The median FET SUV(R) was higher in areas corresponding to the fluorescent tumour compared with the non-fluorescent normal brain (2.321 vs 1.142, p < 0.0001, t-test). A SUV(R) greater than 1.374 predicted the fluorescence with a sensitivity of 0.87 [95% confidence interval (CI): 0.74-0.94] and a specificity of 0.94 (CI: 0.84-0.99). The area under the ROC curve was 0.9656 (CI: 0.9364-0.9948).

CONCLUSIONS

FET uptake predicts the 5-ALA-induced fluorescence in glioma patients. Thus, FET-PET provides useful information for planning glioma resection.

[Establishment and application of double-antibody sandwich ELISA for determination of 3-nitrotyrosine]

AIM

To prepare the working standards of 3-nitrotyrosine (3-NT) and establish a two-antibody-sandwich ELISA for determining the concentration of peroxynitrite in the tissue.

METHODS

Nitrated bovine serum albumin was prepared by additions of an alkaline stock solution of peroxynitrite which was synthesized by a quenched-flow reactor. The monoclone anti-3-NT antibody from mouse was used as coating antibody and the polyclone anti-3-NT antibody from as labeling antibody to prepare the standard work curve by orthogonal design. The concentrations of 3-NT in cardiac tissue from rats subjected to myocardial ischemia and reperfusion (MI/R) were analyzed.

RESULTS

A two-antibody-sandwich ELISA method for measuring 3-NT content in biological fluids and homogenates was successfully established. The detecting limit was 0.1 ng x ml(-1) and the linear range of standard work curve was 0.15 - 7.50 ng x ml(-1) (r2 = 0.995). The 3-NT concentration in cardiac tissue from rats subjected to MI/R (1022.42 +/- 97.35 ng x mg pro(-1)) was significantly higher than that in the sham group (246.58 +/- 56.52 ng x mg pro(-1), P < 0.01).

CONCLUSION

A two-antibody-sandwich ELISA was established for determining the 3-NT concentration in the tissue and conveniently, quickly, accurately quantitative analysis of the content of 3-NT. The assay provides a new method for quantitative analysis of the peroxyinitrite in the future.