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排序方式: 共有1319条查询结果,搜索用时 421 毫秒
911.
Markiewicz W Jaroszewski JJ Barszczewska B Sienkiewicz W 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2003,41(2):73-81
The aim of the present study was to determine: (i) the presence of dopamine-beta-hydroxylase (DbetaH)- and neuropeptide Y (NPY)-immunoreactive (IR) nerve fibres in the wall of the porcine ovarian artery, (ii) the influence of NPY and norepinephrine (NE) on the contractile activity of the pig ovarian arteries, and (iii) the pharmacological analysis of the interaction between NPY and NE in the isolated porcine ovarian arteries collected from immature pigs and from animals in different days of the estrous cycle. Ovarian arteries for immunohistochemistry and isolated arteries for pharmacological studies were excised from immature pigs and mature animals on days 1-5, 8-13 and 17-20 of the estrous cycle. The study showed that both DbetaH- and NPY-IR nerve fibres were present in the pig ovarian arteries in all periods examined, and, that in some fibres DbetaH and NPY were co-localized. Both NE (10(-6) M) and NPY (10(-7) M) increased blood pressure of examined preparations, however, NE caused stronger changes in the vessel wall tension (P<0.001), than did NPY. NE significantly increased (P<0.001) blood pressure of all isolated arteries, however, this response was stronger in vessels from days 1-5 of the cycle, when compared to days 8-13 (P<0.01), 17-20 and immature pigs (P<0.001). NPY increased significantly blood pressure in isolated arteries from days 8-13 and 17-20 of the cycle (P<0.001), while in preparations taken from immature pigs and animals on days 1-5 of the estrous cycle this response was somewhat weaker (P<0.01). A higher elevation (P<0.001) of blood pressure after NPY administration was observed in isolated arteries from days 17-20 of the cycle, when compared to vessels from days 1-5 and 8-13 and those from immature pigs. Moreover, NE significantly intensified (P<0.001) an increase in the blood pressure in isolated arteries pre-treated with NPY in all periods examined. NPY insignificantly (P>0.05) potentiated increase of blood pressure in NE pre-treated vessels of immature pigs and in isolated arteries from days 17-20 of the cycle and significantly (P<0.05) in vessels from days 1-5 and 8-13 of the estrous cycle. Our results indicate that DbetaH- and NPY-IR nerve fibres are present in the pig ovarian arteries. NE and NPY administered alone increased blood pressure in the pig isolated ovarian artery and simultaneous administration of both substances caused each other potentiation of vasocontractile effect, however, the strength of observed changes was dependent on the stage of the estrous cycle. 相似文献
912.
Optical absorption and fluorescence parameters of chlorophyll a and the phytol-free chlorophyllide a, as well as of their Mg-depleted derivatives, were compared in a series of organic solvents. In contrast to prevailing opinion,
the spectral properties of chlorophyll are not indifferent to the removal of phytol. The electronic absorption spectra of
chlorophyll a and chlorophyllide a differ and display a different dependence on the nature of the solvent, which cannot be explained solely by the location
of a charged carboxylic group in the proximity of the π– electron system. In fact, measurements in media of varying basicity
show that deprotonation of the free carboxylic group in chlorophyllide, i.e., the presence of a negative point charge near
the macrocycle, has no effect on pigment absorption spectra. Analysis of the solvent effect on the QY energies in terms of solvent polarity reveals that the phytyl moiety perturbs the spectral features of chlorophyll, mainly
due to its interactions with the pigment solvation shell. The phytyl residue might also be thus partly involved in controlling
the central metal ligation in chlorophylls. This influence of phytol on the spectral features of chlorophyll should be taken
into account when comparing the spectra in solution with various spectral forms of chlorophyll in vivo.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
913.
Grochowalska R Machnicka B Wysocki R Lachowicz TM 《Cellular & molecular biology letters》2003,8(2):261-268
A series of 30 Saccharomyces cerevisiae aci(+) mutants (characterized as acidifying Ogur's glucose medium containing bromocresol purple) were isolated after EMS mutagenesis. All the mutants excreted acid metabolites to the medium after 24 or 48 hours of incubation. The character of the aci(+) mutations was defined using classical genetic techniques. Three of the aci(+) mutants were studied by molecular genetics techniques. 相似文献
914.
The aim of this study was to investigate whether apamin-sensitive K(+)channels play a role in the NO induced relaxation of the human pregnant myometrium. Concentration-response curves for sodium nitroprusside (SNP) (10(-9)-10(-4)M) were constructed in the absence and presence of 10(-8)M apamin and 10(-7)M charybdotoxin (CTX). Preincubation with apamin resulted in a significant attenuation of the relaxation caused by SNP, while pre-treatment with CTX insignificantly decreased the SNP induced relaxation. Our findings suggest that apamin-sensitive K(+)channels exist in the human pregnant myometrium and play a role in modulation of the myometrium response to NO donors 相似文献
915.
Białek-Bylka GE Jazurek B Dedic R Hala J Skrzypczak A 《Cellular & molecular biology letters》2003,8(3):689-697
The (1(1)B(u)+) energy of synthetic 15-cis beta-carotene exhibits a linear dependence on (n(2)-1)/(n(2)+2) in non-polar and polar solvents; in this it is similar to (that of) all-trans beta-carotene. The point of intersection is at (n(2)-1)/(n(2)+2) = 0.3 for both isomers. The microenvironment of 15-cis beta-carotene in the Photosystem II reaction center was established as having a mean refractive index 1.473. Persistent spectral hole burning with a very broad (approximately 30 nm) hole observed around 500 nm (corresponding to an extremely short excited lifetime tau approximately 9 fs) indicates that 15-cis beta-carotene has/displays very efficient photoprotective quenching. 相似文献
916.
Kontaxakis VP Havaki-Kontaxaki BJ Christodoulou NG Paplos KG Christodoulou GN 《Annals of general hospital psychiatry》2003,2(1):10
BACKGROUND: The neuroleptic malignant syndrome is a rare but serious condition mainly associated with antipsychotic medication. There are controversies as to whether "classical" forms of neuroleptic malignant syndrome can occur in patients given atypical antipsychotics. The serotonin syndrome is caused by drug-induced excess of intrasynaptic 5-hydroxytryptamine. The possible relationship between neuroleptic malignant syndrome and serotonin syndrome is at present in the focus of scientific interest. METHODS: This retrospective phenomenological study aims to examine the seventeen reported olanzapine - induced neuroleptic malignant syndrome cases under the light of possible overlap between neuroleptic malignant syndrome and serotonin syndrome clinical features. RESULTS: The serotonin syndrome clinical features most often reported in cases initially diagnosed as neuroleptic malignant syndrome are: fever (82%), mental status changes (82%) and diaphoresis (47%). Three out of the ten classical serotonin syndrome clinical features were concurrently observed in eleven (65%) patients and four clinical features were observed in seven (41%) patients. CONCLUSION: The results of this study show that the clinical symptoms of olanzapine-induced neuroleptic malignant syndrome and serotonin syndrome are overlapping suggesting similarities in underlying pathophysiological mechanisms. 相似文献
917.
Gorski A Dabrowska K Switala-Jeleń K Nowaczyk M Weber-Dabrowska B Boratynski J Wietrzyk J Opolski A 《Medical immunology (London, England)》2003,2(1):2
BACKGROUND: While the ability of bacteriophages to kill bacteria is well known and has been used in some centers to combat antibiotics - resistant infections, our knowledge about phage interactions with mammalian cells is very limited and phages have been believed to have no intrinsic tropism for those cells. PRESENTATION OF THE HYPOTHESIS: At least some phages (e.g., T4 coliphage) express Lys-Arg-Gly (KGD) sequence which binds beta3 integrins (primarily alphaIIbbeta3). Therefore, phages could bind beta3+ cells (platelets, monocytes, some lymphocytes and some neoplastic cells) and downregulate activities of those cells by inhibiting integrin functions. TESTING THE HYPOTHESIS: Binding of KGD+ phages to beta3 integrin+ cells may be detected using standard techniques involving phage - mediated bacterial lysis and plaque formation. Furthermore, the binding may be visualized by electron microscopy and fluorescence using labelled phages. Binding specificity can be confirmed with the aid of specific blocking peptides and monoclonal antibodies. In vivo effects of phage - cell interactions may be assessed by examining the possible biological effects of beta3 blockade (e.g., anti-metastatic activity). IMPLICATION OF THE HYPOTHESIS: If, indeed, phages can modify functions of beta3+ cells (platelets, monocytes, lymphocytes, cancer cells) they could be important biological response modifiers regulating migration and activities of those cells. Such novel understanding of their role could open novel perspectives in their potential use in treatment of cardiovascular and autoimmune disease, graft rejection and cancer. 相似文献
918.
Beata?Modzelewska Anna?KostrzewskaEmail author Marek?Sipowicz Tomasz?Kleszczewski Satish?Batra 《Reproductive biology and endocrinology : RB&E》2003,1(1):8
There is now considerable evidence for the involvement of K+ channels in nitric oxide (NO) induced relaxation of smooth muscles including the myometrium. In order to assess whether apamin-sensitive
K+ channels play a role in NO – induced relaxation of the human uterus, we have studied the effect of specific blockers of these
channels on the relaxation of myometrium from non-pregnant women. In vitro isometric contractions were recorded in uterine
tissues from non-pregnant premenopausal women who had undergone hysterectomy. Apamin (10 nM) and scyllatoxin (10 nM) did not
alter spontaneous myometrial contractions. However, 15-min pretreatment of the myometrium strips with apamin completely inhibited
relaxation caused by diethylamine-nitric oxide (DEA/NO). The pretreatment with scyllatoxin significantly reduced (about 2.6
times) maximum relaxation of the strips induced by DEA/NO (p < 0.05). These results strongly suggest that, beside Ca2+ and voltage dependent charybdotoxin-sensitive (CTX-sensitive) K+ channels, apamin-sensitive K+ channels are also present in the human non-pregnant myometrium. These channels offer an additional target in the development
of new tocolytic agents. 相似文献
919.
Shuto D Kasai S Kimura T Liu P Hidaka K Hamada T Shibakawa S Hayashi Y Hattori C Szabo B Ishiura S Kiso Y 《Bioorganic & medicinal chemistry letters》2003,13(24):4273-4276
A novel class of substrate-based β-secretase (BACE1) inhibitors containing a hydroxymethylcarbonyl (HMC) isostere was designed and synthesized. Phenylnorstatine [(2R,3S)-3-amino-2-hydroxy-4-phenylbutyric acid; Pns] was an effective transition-state mimic at the P1 position. Structure–activity relationships (SARs) of the P3–P3′ positions of BACE1 inhibitors were studied. 相似文献
920.
Ressmeyer AR Mayo JC Zelosko V Sáinz RM Tan DX Poeggeler B Antolín I Zsizsik BK Reiter RJ Hardeland R 《Redox report : communications in free radical research》2003,8(4):205-213
In numerous experimental systems, the neurohormone melatonin has been shown to protect against oxidative stress, an effect which appears to be the result of a combination of different actions. In this study, we have investigated the possible contribution to radical scavenging by substituted kynuramines formed from melatonin via pyrrole ring cleavage. N1-Acetyl-5-methoxykynuramine (AMK), a metabolite deriving from melatonin by mechanisms involving free radicals, exhibits potent antioxidant properties exceeding those of its direct precursor N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and its analog N1-acetylkynuramine (AK). Scavenging of hydroxyl radicals was demonstrated by competition with ABTS in a Fenton reaction system at pH 5 and by competition with DMSO in a hemin-catalyzed H2O2 system at pH 8. Under catalysis by hemin, oxidation of AMK was accompanied by the emission of chemiluminescence. AMK was a potent reductant of ABTS cation radicals, but, in the absence of catalysts, a poor scavenger of superoxide anions. In accordance with the latter observation, AMK was fairly stable in a pH 8 H2O2 system devoid of hemin. Contrary to AFMK, AMK was easily oxidized in a reaction mixture generating carbonate radicals. In an oxidative protein destruction assay based on peroxyl radical formation, AMK proved to be highly protective. No prooxidant properties of AMK were detected in a sensitive biological test system based on light emission by the bioluminescent dinoflagellate Lingulodinium polyedrum. AMK may contribute to the antioxidant properties of the indolic precursor melatonin. 相似文献