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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%).

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.

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.

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.

A ratiometric fluorimetry is proposed for the determination of peroxynitrite (ONOO-) and the evaluation of its scavenger based on synchronous fluorescence spectroscopy. L-tyrosine, an intrinsic fluorescent aminoacid, reacts with peroxynitrite and carbon dioxide, yielding a highly fluorescent dimer of tyrosine in pH 8.5 PBS buffer solution. By synchronous fluorescence scanning, both monomer and dimer emission bands of L-tyrosine appeared at 364 and 406 nm, respectively. The ratio of F406/ F364 is quantitatively related to the concentration of peroxynitrite, where F406 represents the intensity of synchronous emission band of dimer and F364 represents that of monomer. The method has been showing merit of being insensitive to the changes in experimental parameters and offers a higher sensitivity and a broader responding linear range of the analyte concentration, compared to fluorimetric method, giving a LOD of 1.84 X 10(-8) mol x L(-1) and a linear range of 1.60 X 10(-7) mol x L(-1)-6.00 X 10(-6) mol x L(-1) for ONOO-, respectively, with a deviation of 2.4% for 1.00 X 10(-6) mol x L(-1) ONOO- (n = 8). A IC50 of 0.065 microg x mL(-1) for mitoxantrone, an antioxidant and anticancer drug, was also obtained. This method has proved to be simple and speedy. It would be easily used in the determination of ONOO- and its scavenger.

A new method using alternating penalty trilinear decomposition algorithm coupled with excitation-emission matrix fluorometry has been developed for simultaneous resolution and determination of tyrosine, phenylalanine and tryptophan. Their correlation coefficients were 0.9987, 0.9995 and 0.9993 respectively. The contents of tyrosine, phenylalanine and tryptophan in Hibiscus syriacus L. leaves were also be determined by this method after being extracted by ultrasonic. The coefficients of variation and the recoveries of the three amino acids were 0.84%, 0.36%, 1.59% and 101.0%-92.7%, 106.5%-93.0%, 103.0%-95.0% respectively. All these show that this is a simple, fast and cridible method.

A new fluorescence method by artificial neural network for the simultaneous determination of tryptophan and tyrosine was developed. The determination was carried out in the KH2PO4-K2HPO4 buffer solution (pH = 7.15) and at the EX (excitation) wavelength of 224 nm. In the range of 290-400 nm, the fluorescence intensities at fourteen wavelengths were taken as characteristic parameters of the artificial neural network, and the samples were arranged by the method of equality design. The mean recoveries of tryptophan and tyrosine were 100.9% and 101.6% respectively. The RSDs of the results were 4.18% and 4.17%. The method has been applied to the determination of tryptophan and tyrosine in compound amino acid injection, and the relative errors were 4.0% and 2.6%, respectively. The results were better than those of other networks in training speed and accuracy. In conclusion, the new network spectrofluorimetry is a good choice for multicomponent resolving analysis.

A new selective and sensitive spectrofluorimetric method for the determination of Tyrosine in beer and grape wine has been developed. This method is based on the quenching of fluorescence of Tyrosine by Molybrum(VI). The exitation and emission wavelengths were found to be 278 and 305 nm, respectively. There was a linear relationship in the range of 0.01-14.4 micrograms.mL-1 for Tyrosine. This method is simple and rapid, and has been applied to the determination of Tyrosine in beer and grape wine with satisfactory results.

The nitroxyl of nitrotyrosine can be substituted quantitatively by iodide when the nitroxyl is reduced to amino and then diazotized to diazonium. The iodide can be determined by catalytic spectrophotometric method with iodide-nitrous acid-arsenious acid system. Thus, a new catalytic spectrophotometric method combining the substitution of nitroxyl by iodide for the determination of nitrotyrosine has been established. The limit of detection is 0.002 mumol.L-1 and the linear range is 0.005-0.25 mumol.L-1. The method has been used for the determination of nitrotyrosine in the products of the reaction of tyrosine with peroxynitrite and the results are satisfactory.

A new first-derivative fluorescent method by partial least squares (PLS) for the simultaneous determination of tryptophan, tyrosine and Phenylalanine was developed. The determination was carried out in KH2PO4-K2HPO4 buffer solution (pH = 7.4) and at the EX (excite) wavelength of 216.6 nm. The method has been applied to the determination of tryptophan, tyrosine and phenylalanine in compound amino acid injection, and the relative errors are within +/- 7.2%.

A new method of second order derivative fluorimetry for the simultaneous determination of tryptophan and tyrosine is described. The measurement of emission spectra is carried out with excitation at 221 nm in a KH2PO4-NaOH buffer solution (pH = 7.4). The second-derivative peak is at 318 nm and 283 nm for tryptophan and tyrosine respectively. The two amino acids can be determined directly from corresponding second order derivative signals. Linear regression equation of the calibration graph is c = 0.000 7H-0.004, with a correlation coefficient of linear regression of 0.9964 for tryptophan and c = 0.001 2H-0.0040, with a correlation coefficient of linear regressin of 0.9971 for tyrosine. The linear ranges of determination of tryptophan and tyrosine are from 0.004 to 0.200 microgram.mL-1 and from 0.002 to 0.025 microgram.mL-1, respectively. Effects of pH, temperature and foreign ions on the determination of tryptophan and tyrosine have been examined. Recovery is from 92.0% to 104% for tryptophan and 98.7% to 102.0% for tyrosine, and relative standard deviation of 3.5% and 2.8%, respectively.

Substantial differences were found in the spectral properties of surgical samples from 20 women patients with histologically normal and cancerous breast tissue. The most striking changes in the spectra were observed in the symmetric and asymmetric stretching bands of phosphodiester groups, which shifted to short wavenumber about 3 cm-1 in nu s PO2-, and to long wavenumber about 2 cm-1 in nu s PO2-. The ratio of A1,173/A1,163 increased and that of A1,025/A1,082 decreased, the intensity of symmetric and asymmetric stretching bands of CH3 decreased and those of CH2 increased in all of breast cancer tissues. Our findings indicated that in breast cancer tissue, the degree of hydrogen-bonding of oxygen atoms in the backbone of nucleic acid increased; the content of glycogen decreased; the degree of hydrogen-bonding of OH groups in serine, tyrosine, and threonine residues of cell proteins decreased; and also there were changes in the packing and the conformational structure of the methylene chains of membrane lipids.

Seventeen amino acids in Trigonella foenumgraecum seeds are analyzed by means of HITACHI Model 835-50 High Speed Amino Acid Analyzer. Seven of them are essential amino acid for human body. The results provide references for evaluating the usefulness of T. foenumgraecum seeds in medicine and food.

A new method for the simultaneous determination of tyrosine and tryptophan by polarization spectrofluorimetry has been developed. The interference of phenylalanine and light scattering of solvent were eliminated by using vertically crossed polarizers. The overlapping of fluorescence spectra of the two amino acids was solved with filters. The linear ranges of determination were 0.02-12.0 mg.L-1(tyrosine) and 0.01-2.50 mg.L-1(tryptophan). The mean recoveries of tyrosine and tryptophan in samples were 95.4% and 101.7% (in amino acid injection). 99.2% and 100.0% (in wild jujube kernel), 95.3% and 97.2% (in shrimp shell) respectively. The proposed method has been used to determine tyrosine and tryptophan in amino acid injection, extracts of wild jujube kernel and shrimp shells with satisfactory results.

The ovaries taken from the immature female rats primed with PMSG-hCG were digested with collagenase-DNAase solution to obtain the luteal cell suspensions. Luteal cells were then incubated with different doses of hCG, cAMP or progesterone for 1.5 hours. The contents of tyrosine in luteal cell suspensions were determined by thin layer chromatogram using dual-wavelength chromatogram scanner. It was found that the content of tyrosine in rat luteal cell suspensions was 1.41 + 0.24 nmol/L/10(6) cells after one hour incubation. hCG, cAMP and progesterone all could significantly increase the content of tyrosine in the suspensions, suggesting the release of "endogenous tyrosine". The increase of tyrosine was not due to increased transformation of phenylalanine, the precursor of tyrosine, and increased protein synthesis, because both phenylalanine and cycloheximide failed to influence such increase.