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61.
Serotonin (5-hydroxytryptamine; 5-HT) elicits external carotid vasoconstriction in vagosympathectomized dogs via 5-HT1B/1D receptors and a mechanism unrelated to the 5-HT1, 5-HT2, 5-HT3 and 5-HT4 types. In order to further explore the nature of this novel mechanism, the canine external carotid effects of 2-(2-aminoethyl)-quinoline (D-1997), a novel 5-HT1 receptor agonist, were analyzed and compared with those of 5-HT and sumatriptan. Intracarotid (i.c.) infusions of 5-HT, D-1997 and sumatriptan to vagosympathectomized dogs dose-dependently decreased external carotid conductance, the rank order of agonist potency being 5-HT > sumatriptan > D-1997. The effects to D-1997 were resistant to intravenous (i.v.) pretreatment with 5-HT2 and 5-HT3/5-HT4 receptor antagonists. Remarkably, the effects induced by lower (10-100 microg/min), but not higher (300-1000 microg/min), doses of D-1997 were blocked by high doses of methiothepin (1 and 3 mg/kg, i.v.), as previously shown with 5-HT. In addition, GR-127935 (1-10 microg/kg, i.v.), partially and dose-dependently antagonized D-1997-induced responses. However, the effects of D-1997 remained unaltered after blockade of alpha- and beta-adrenoceptors, muscarinic, nicotinic, histamine and dopamine receptors, or inhibition of 5-HT-uptake or cyclo-oxygenase, depletion of biogenic amines or blockade of Ca2+ channels. These results may support our previous contention that lower doses of 5-HT elicit external carotid vasoconstriction in vagosympathectomized dogs by activation of 5-HT1B/1D receptors, whilst higher doses of 5-HT stimulate a novel vasoconstrictor mechanism. 相似文献
62.
The specific recognition by Escherichia coli RNA polymerase of single-stranded oligodeoxyribonucleotides (oligos) with the sequence of the -10 promoter region on the nontemplate strand has been studied. Binding was monitored by observing the increase in fluorescence of 2-aminopurine residues incorporated in the oligos. The effects of salt on the rates of formation and dissociation of RNA polymerase.oligo complexes are relatively small, from which we conclude that electrostatic interactions contribute minimally to the favorable binding free energy. From the convex temperature dependence of ln Ka (Ka is the equilibrium association constant), we infer that a large apparent negative heat capacity, of 1-2 kcal M-1 K-1, accompanies complex formation, which is interpreted as due to a conformational change in RNA polymerase. Contrary to expectation, the forward rate constant for binding of oligos is more than 10-fold smaller than that for open complex formation at strong promoters. This suggests that in comparison to an oligo, promoter DNA may be better able to accelerate this required conformational change in the RNA polymerase. Oligo binding was shown to compete with the interaction between RNA polymerase and promoters, indicating that the two bind to overlapping sites on the RNA polymerase 相似文献
63.
For ultrasonographic B-scan images collected by means of a handheld transducer moving in the elevational direction, frame spacings are computed with a speckle-decorrelation algorithm, without additional positioning hardware. Fully developed speckle volumes are automatically segmented and spacing computed from the decorrelation curves. Position accuracy is within 10% for phantoms and 15% for breast studies. The algorithm provides image-based registration, which allows accurate three-dimensional volume rendering. 相似文献
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There has been little empirical study of risk factors for the development of late-life late-onset drinking problems. In the current prospective study, we compare two groups of older adults who, at a baseline assessment, were nonproblem drinkers: individuals who developed drinking problems over the course of the next 7 years (n = 77) and those who did not (n = 197). Late-onset problem drinkers reported mild to moderate drinking problems and spontaneous remission rates were high. Compared with stable nonproblem drinkers, late-onset problem drinkers at baseline were more likely to report incipient problems, heavier alcohol consumption, greater friend approval of drinking, more reliance on avoidance coping strategies, were more likely to smoke, and were less likely to have acute medical conditions that could potentially be complicated by alcohol consumption. Contrary to expectation, life stressors did not predict drinking problem onset. However, compared with stable nonproblem drinkers, late-onset problem drinkers were more likely to have a history of responding to stressors and negative affect with increased alcohol consumption. 相似文献
66.
MG Maher E Sapi B Turner A Gumbs PL Perrotta D Carter BM Kacinski BG Haffty 《Canadian Metallurgical Quarterly》1998,4(8):1851-1856
The macrophage colony-stimulating factor receptor (CSF-1R), the product of the c-fms proto-oncogene, regulates normal proliferation and differentiation of macrophages and trophoblasts. Recent research found abnormal expression of CSF-1R in human carcinomas of the breast, endometrium, and ovary. Furthermore, activation of CSF-1R by its ligand has been shown to regulate invasiveness and anchorage-independent growth in breast carcinoma cells. To study the significance of CSF-1R expression in breast cancer, we designed a case-controlled immunohistochemical study. We chose 80 patients from a database of 1200 early stage I or II breast cancer patients treated with conservative surgery and radiation therapy. Expression of CSF-1R in the tumors of 40 patients who experienced an ipsilateral breast tumor recurrence (IBTR) as a primary site of relapse were compared with 40 patients who had not experienced an IBTR. The index and control patients were matched by age, clinical stage, nodal status, and follow-up. Paraffin-embedded sections were immunostained with antibodies directed toward CSF-1R. For the CSF-1R antibody, a total of 28 index cases (70%) demonstrated strong staining, whereas only 16 control cases (40%) demonstrated high immunoreactivity (P = 0.007). The CSF-1R antibody showed a positive correlation for local relapse, but no correlation was found between CSF-1R expression and distant metastasis. In summary, our findings provide evidence for the poor prognostic role of CSF-1R in IBTR. 相似文献
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68.
JM Cho AJ LaPorta JR Clark MJ Schofield SL Hammond PL Mallory 《Canadian Metallurgical Quarterly》1994,8(12):1380-3; discussion 1383-4
The clinical observation that a laparoscopic cholecystectomy is a minimally invasive operation has not been demonstrated on a biochemical basis. Interleukin-6, a known endogenous pyrogen and hepatocyte-stimulating protein, correlates with the significance of surgical trauma. Utilizing the IL-6 immunoassay, we studied this biochemical parameter of trauma to compare its response in laparoscopic vs open cholecystectomy. Sixteen patients who underwent only laparoscopic cholecystectomy showed peak IL-6 concentrations of 51 pg/ml (22-86) vs a peak IL-6 concentration of 124 pg/ml (56-225) for open cholecystectomy. Six additional patients who underwent an ERCP followed by laparoscopic cholecystectomy showed a dramatic rise in peak IL-6 concentration to 315 pg/ml (15-634). These results biochemically confirm the true minimal invasiveness of laparoscopic cholecystectomy. The findings in the ERCP-followed-by-laparoscopic-cholecystectomy group support the theory that two invasive procedures in close proximity may prime the cytokine system in its response to surgical trauma. 相似文献
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70.
There are known 3 likely mechanisms of virus conveyance into the central nervous system (CNS). These include hematogenic penetration, spread along the peripheral nerves, and the olfactory pathway which begins from the infected olfactory neuroepithelial cells. The possibility of viral spread into CNS via the olfactory pathway was shown for the representatives of togaviruses, herpesviruses, coronaviruses, rhabdoviruses, and for some others. This study suggests that the olfactory pathway of viral conveyance into CNS may be blocked by specific mucosal antibodies in the nasal mucosa. The recombinant TK- variant of WR vaccinia strain with inserted genes coding structural and nonstructural proteins of TBE virus is accumulated in the branches of the respiratory tract only while the parenteral vaccinia strain is detected in the brain regions, spleen, respiratory tract, and in blood. The protective activity of recombinant strain and inactivated TBE vaccine after mice immunization by escarification or intranasally, or subcutaneously was comparatively studied. The findings indicate that intranasal immunization by recombinant strain is the most protective against intraperitoneal challenge by TBE virus. The mucosal and humoral immune response that was induced by intranasal immunization seems to provide the highest levels of protection, which was experimentally observed. 相似文献