Although human face recognition performance shows high selectivity, even for unfamiliar faces, the neuronal circuitry underlying this high performance is poorly understood. Two extreme alternatives can be considered: either a "labeled-line" principle, in which subtle changes in face images lead to activation of differently tuned neuronal populations, or a coarse coding principle, where the high face selectivity is coded by the relative activation of broadly tuned neurons. In this study, we set to parametrically examine the shape and selectivity profile of face-related visual areas. To that end, we applied the functional magnetic resonance (fMR)-adaptation paradigm. Unfamiliar face stimuli were morphed into sets ranging from identical faces, through subtle morphing, to completely different exemplars. The fusiform face area (FFA) revealed high face sensitivity, so that even facial images perceived as belonging to the same individual (<35%) were sufficient to produce full recovery from adaptation. Interestingly, the psychophysical detectability of facial differences paralleled the release from fMR-adaptation. These results support the labeled-line model where high sensitivity to face changes is paralleled by narrow tuning of neuronal populations selective to each face image, and they suggest that fMR-adaptation is closely related to behavior. The results bear strong implications to the nature of face-related neuronal responses. 相似文献
1,10-phenanthroline (phen), flufenamic acid, and indomethacin are inhibitors of aldo-keto reductases 1C1 (AKR1C1), but only phen decreased the benzo[a]pyrene (BaP)-induced cytochrome P450 1a1 (Cyp1a1) protein level. Therefore the decrease in the BaP-induced Cyp1a1 protein level was not due to inhibition of Akr1c1, but to phen itself. Phen decreased the BaP-induced Cyp1a1 promoter activity and protein expression, and in contrast, it increased Cyp1a1 mRNA, resulting from an increase in mRNA stability. Phen is also known as a transition metal ion-chelator. Along with the phen study, we also found that Zn2+, Fe2+ and Cu2+ increased Cyp1a1 mRNA and protein stability. Our results show that phen stabilized the mRNA of Cyp1a1, although it decreased cell viability. In addition, Zn2+ and Fe2+ highly neutralized phen's suppression of Cyp1a1 protein expression, but they only slightly neutralized phen's promotion of mRNA stability and suppression of cell viability, and had no effect on phen's suppression of promoter activity. Phen's effect on Cyp1a1 expression was reversible, which indicates that phen is non-covalently linked to its target. This report elucidates a new role for phen of stabilizing Cyp1a1 mRNA, and provides information for further studies on mRNA stabilization. 相似文献
Chrysin is a flavonoid that exists in nature and is the major component of some traditional medicinal herbs. We investigated the hepatoprotective and antihyperlipidaemic potential of chrysin against d-galactosamine (a single intraperitoneal injection 400 mg/kg BW) induced hepatotoxicity in male albino Wistar rats. d-GalN rats exhibited an increased hepato and nephro toxicity marker activities aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and gamma glutamyl transpeptidase and total bilirubin level while urea, uric acid and creatinine and lipid profile. It also negatively affected the serum total protein, albumin and A/G ratio. Rats treated with chrysin at different concentrations (25, 50 and 100 mg/kg BW) caused a significant improvement in serum protein level, decreased hepato and nephro toxicity markers. It also decreased the levels of very low density lipoprotein cholesterol and low density lipoprotein cholesterol while high density lipoprotein cholesterol significantly increased. It also decreased the levels of total cholesterol, phospholipids, triglycerides, free fatty acids in the plasma and tissues of liver and kidney. The effect of chrysin (25 mg/kg) is comparable with silymarin, a known hepatoprotective drug. Chrysin thus exhibits hepatoprotective and antihyperlipidaemic activity. 相似文献
We tested functional activation for faces in patient D.F., who following acquired brain damage has a profound deficit in object recognition based on form (visual form agnosia) and also prosopagnosia that is undocumented to date. Functional imaging demonstrated that like our control observers, D.F. shows significantly more activation when passively viewing face compared to scene images in an area that is consistent with the fusiform face area (FFA) (p < 0.01). Control observers also show occipital face area (OFA) activation; however, whereas D.F.'s lesions appear to overlap the OFA bilaterally. We asked, given that D.F. shows FFA activation for faces, to what extent is she able to recognize faces? D.F. demonstrated a severe impairment in higher level face processing--she could not recognize face identity, gender or emotional expression. In contrast, she performed relatively normally on many face categorization tasks. D.F. can differentiate faces from non-faces given sufficient texture information and processing time, and she can do this is independent of color and illumination information. D.F. can use configural information for categorizing faces when they are presented in an upright but not a sideways orientation and given that she also cannot discriminate half-faces she may rely on a spatially symmetric feature arrangement. Faces appear to be a unique category, which she can classify even when she has no advance knowledge that she will be shown face images. Together, these imaging and behavioral data support the importance of the integrity of a complex network of regions for face identification, including more than just the FFA--in particular the OFA, a region believed to be associated with low-level processing. 相似文献
Ghrelin is an important factor involved in most of the metabolic and hormonal signals which adapt the reproductive functions in conditions of altered energy balance. Moreover, the coordinated role of leptin and ghrelin appears in fact to have a specific role in the regulation of puberty. Systemic action of ghrelin on the reproductive axis involves the control of the hypothalamic-pituitary-gondal axis. In addition, it has been shown that ghrelin may directly act at a gonadal level in both females and males. Available data also demonstrate that sex steroid hormones and gonadotropins may in turn regulate the gonadal effect of ghrelin, as documented by studies performed in females with the polycystic ovary syndrome and in hypogonadal men. Notably, recent studies also confirm a potentially important role for ghrelin in fetal and neonatal energy balance, and specifically in allowing fetal adaptation to an adverse intrauterine environment. 相似文献
Inotropic agents are administered to improve cardiac output and peripheral perfusion in patients with systolic dysfunction and low cardiac output. However, there is evidence of increased mortality and adverse effects associated with current inotropic agents. These adverse outcomes may be ascribed to patient selection, increased myocardial energy expenditure and oxygen consumption, or to specific mechanisms of action. Both sympathomimetic amines and type III phosphodiesterase inhibitors act through an increase in intracellular cyclic adenosine monophoshate and free calcium concentrations, mechanisms that increase oxygen consumption and favor arrhythmias. Concomitant peripheral vasodilation with some agents (phosphodiesterase inhibitors and levosimendan) may also lower coronary perfusion pressure and favor myocardial damage. New agents with different mechanisms of action might have a better benefit to risk ratio and allow an improvement in tissue and end-organ perfusion with less untoward effects. We have summarized the characteristics of the main inotropic agents for heart failure treatment, the data from randomized controlled trials, and future perspectives for this class of drugs. 相似文献
Purpose: To study the role of Optical coherence tomography (OCT) Angiography (OCTA) in detecting retinal vascular and macular abnormalities as compared to Fundus Fluorescein Angiography (FFA) in subjects with Asteroid hyalosis (AH).
Methods: In a prospective study, patients with AH underwent OCTA and FFA. AH graded as Grade 1 in 8 (optic disc, second order vessels visible), Grade 2 in 4 (optic disc, first-order vessels visible), Grade 3 in 11 (hazy view of optic disc) and Grade 4 (no view of fundus) in 2 eyes.
Results: A total of 20 patients (25 eyes) with AH were included. In comparison to FFA, OCTA was able to similarly detect Diabetic Retinopathy changes such as Neovascularization, microaneurysms, capillary dropout, and foveal avascular zone extent in vascular occlusion in all grades of AH.
Conclusion: OCTA, a noninvasive imaging tool, could detect various retinal vascular and macular abnormalities in patients with all grades of AH in comparison to FFA. 相似文献
We determined whether habitual cigarette smoking alters insulin-stimulated glucose transport and GLUT4 protein expression in skeletal muscle. Vastus lateralis muscle was obtained from 10 habitual cigarette smokers and 10 control subjects using an open muscle biopsy procedure. Basal 3-O-methylglucose transport was twofold higher (P > 0·01) in muscle from habitual smokers (0·05 ± 0·08 vs. 1·04 ± 0·19 μmol ml?1 h?1; controls vs. smokers respectively). Insulin (600 pmol l?1) increased glucose transport 2·6-fold (P > 0·05) in muscle from control subjects, whereas no significant increase was noted in habitual smokers. Skeletal muscle GLUT4 protein expression was similar between the groups. FFA levels were elevated in the smokers (264 ± 49 vs. 748 ± 138 μmol l?1 for control subjects vs. smokers; P < 0·05), and serum triglyceride levels were increased in the smokers (0·9 ± 0·2 vs. 2·3 ± 0·6 mmol l?1 for control subjects vs. smokers; P < 0·05). Skeletal muscle carnitine palmitil (acyl) transferase activity was similar between the groups, indicating that FFA transport into the mitochondria was unaltered by cigarette smoking. In conclusion, cigarette smoking appears to have a profound effect on glucose transport in skeletal muscle. Basal glucose transport is markedly elevated, whereas insulin-stimulated glucose transport is impaired. These changes cannot be explained by altered protein expression of GLUT4, but may be related to increased serum FFA and triglyceride levels. These findings highlight the importance of identifying habitual cigarette smokers in studies aimed at assessing factors that lead to alterations in lipid and glucose homeostasis in people with non-insulin-dependent diabetes mellitus (NIDDM). 相似文献