Activity of angiotensin peptides in clitoral cavernosum of alloxan induced diabetic rabbit

OBJECTIVES: To assess the role of peptides of the angiotensin (ANG) on the regulation of clitoral cavernosum tone and changes in ANG binding affinity in the rabbit with diabetes mellitus. MATERIAL AND METHODS: The isometric tension measurement and in vitro autoradiography were used in sham and diabetic clitoral cavernosum. RESULTS: In tension study, contractility in response to ANG I, ANG II, ANG III and ANG IV was enhanced in diabetic clitoral cavernosum strips (EC50 was 67.6 +/- 27.2, 4.3 +/- 0.4, 189.3 +/- 37.3, 443.2 +/- 0.4 nM for diabetic versus 155.2 +/- 76.1, 38.3 +/- 0.1, 528.0 +/- 75.2, 616.9 +/- 69.5 nM for sham, respectively). Contractile responses to ANG II was significantly inhibited by type 1 ANG II receptor (AT1) antagonist but not by type 2 ANG II receptor (AT2) antagonist in both groups. Percentages in contractions by ANG II (1 nM) in the presence of Dup 753 decreased significantly 36.2 +/- 4.6 to 6.3 +/- 2.4% in sham and 56.1 +/- 7.7 to 6.0 +/- 4.8% in diabetic group. The binding affinities were enhanced in diabetic clitoral cavernosum for ANG II (dissociation constant, 4.9 +/- 1.0 for sham versus 0.9 +/- 0.2 nM for diabetic) and for ANG I, ANG III, and ANG IV (inhibitory constant, 28.6 +/- 1.5, 398.7 +/- 157.2, and 3966.5 +/- 1524.1 nM for sham versus 20.6 +/- 5.7, 78.5 +/- 23.7, and 1098.7 +/- 195.5 nM, for diabetic, respectively, all p < 0.05). Sensitivities of AT1 and AT2 receptors to ANG II enhanced in diabetic than sham clitoral cavernosum tissue. CONCLUSIONS: This results suggest that the contractile responses to all four ANG peptides are enhanced in the diabetic clitoral cavernosum. Enhancement of contractility in diabetic clitoral cavernosum may be related to the increased affinity to ANG II receptors for ANG peptides.     

Effects of (1R,9S)-beta-hydrastine on l-DOPA-induced cytotoxicity in PC12 cells

(1R,9S)-beta-Hydrastine in lower concentrations of 10-50 microM inhibits dopamine biosynthesis in PC12 cells. In this study, the effects of (1R,9S)-beta-hydrastine on L-DOPA (L-3,4-dihydroxyphenylalanine)-induced cytotoxicity in PC12 cells were investigated. (1R,9S)-Hydrastine at concentrations up to 250 microM did not reduce cell viability. However, at concentrations higher than 500 microM it caused cytotoxicity in PC12 cells, as determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, TUNEL (terminal deoxynucleotidyltransferase dUTP nick-end labeling) method and flow cytometry. Exposure of PC12 cells to cytotoxic concentrations of (1R,9S)-beta-hydrastine (500 and 750 microM) in combination with L-DOPA (20, 50 and 100 microM) after 24 or 48 h resulted in a significant decrease in cell viability compared with the effects of (1R,9S)-beta-hydrastine or L-DOPA alone, and apoptotic cell death was observed. However, the decrease in cell viability induced by (1R,9S)-beta-hydrastine was not prevented by the antioxidant N-acetyl-L-cysteine, indicating that it is not mediated by membrane-based oxygen free radical damage. These data suggest that (1R,9S)-beta-hydrastine has a mild cytotoxic effect and at higher concentration ranges aggravates L-DOPA-induced cytotoxicity in PC12 cells.     

In vivo monitoring of amino acids by microdialysis sampling with on-line derivatization by naphthalene-2,3-dicarboxyaldehyde and rapid micellar electrokinetic capillary chromatography

An analytical method was developed to monitor amino acids collected by in vivo microdialysis. Microdialysate was continuously derivatized on-line by mixing 6 mM naphthalene-2,3-dicarboxyaldehyde (NDA) and 10 mM potassium cyanide with the dialysate stream in a fused silica capillary to form fluorescent products. Reaction time, determined by the flow rate and volume of reaction capillary, was 3 min. Derivatized amino acids were continuously delivered into a flow-gated interface and periodically injected onto a capillary electrophoresis unit equipped with a laser-induced fluorescence detection based on a commercial microscope. Separation was performed in the micellar electrokinetic chromatography mode using 30 mM sodium dodecyl sulfate in 15 mM phosphate buffer at pH 8.0 as the separation media. An electric field of 1.3 kV/cm was applied across a 10 cm long, 10 microm internal diameter separation capillary. These conditions allowed 17 amino acid derivatives to be resolved in less than 30 s. On-line injections could be performed at 30 s intervals for in vivo samples. Detection limits were from 10 to 30 nM for the amino acids. The method was applied to monitor the acute ethanol-induced amino acid level changes in freely moving rats. The results demonstrate the utility of the method to reveal dynamics of amino acid concentration in vivo.     

莫能菌素的毒性及其中毒的临床表现

莫能菌素是一类畜禽专用的抗生素,人类主要通过生产接触和误服导致中毒。主要损害肌肉组织,可出现肝、肾、心等多脏器的损害,严重者可因多脏器功能衰竭而死亡。目前尚无特效解毒药,治疗以清除毒物、对症与支持疗法为主。莫能菌素导致人类中毒案例的文献报告国外十分罕见,至今国内尚未见病例报道。现根据作者实践。结合国外文献做一综述。     

Robust generation of new hair cells in the mature mammalian inner ear by adenoviral expression of Hath1

Although hair cells regenerate spontaneously in birds and lower vertebrates following injury, there is yet no effective way to stimulate hair cell regeneration in mature mammalian inner ears. Here we report that a large number of hair cells are produced in the sensory epithelium of cultured adult rat utricular maculae, via adenovirus-mediated overexpression of Hath1, a human atonal homolog. The generation of new hair cells via Hath1 expression does not involve cell proliferation based on bromodeoxyuridine immunocytochemistry. Furthermore, using a similar approach, hair cells are regenerated following aminoglycoside injury in these cultures. These data show conclusively that mature mammalian inner ears have the competence to produce a large number of new hair cells. Local adenoviral gene therapy in the inner ear may be a potential approach to treatment of hearing and balance disorders.