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91.
Marin RM Franchini KG 《American journal of physiology. Heart and circulatory physiology》2005,289(1):H131-H136
In isolated rat hearts perfused with HEPES and red blood cell-enriched buffers, we examined changes in left ventricular pressure induced by increases in heart rate or infusion of adenosine to investigate whether the negative force-frequency relation and the positive inotropic effect of adenosine are related to an inadequate oxygen supply provided by crystalloid perfusates. Hearts perfused with HEPES buffer at a constant flow demonstrated a negative force-frequency relation, whereas hearts perfused with red blood cell-enriched buffer exhibited a positive force-frequency relation. In contrast, HEPES buffer-perfused hearts showed a concentration-dependent increase in left ventricular systolic pressure [EC50 = 7.0 +/- 1.2 nM, maximal effect (Emax) = 104 +/- 2 and 84 +/- 2 mmHg at 0.1 microM and baseline, respectively] in response to adenosine, whereas hearts perfused with red blood cell-enriched buffer showed no change in left ventricular pressure. The positive inotropic effect of adenosine correlated with the simultaneous reduction in heart rate (r = 0.67, P < 0.01; EC50 = 3.8 +/- 1.4 nM, baseline 228 +/- 21 beats/min to a minimum of 183 +/- 22 beats/min at 0.1 microM) and was abolished in isolated hearts paced to suppress the adenosine-induced bradycardia. In conclusion, these results indicate that the negative force-frequency relation and the positive inotropic effect of adenosine in the isolated rat heart are related to myocardial hypoxia, rather than functional peculiarities of the rat heart. 相似文献
92.
Lucia Perez-Carbonell Francesc Balaguer Yuji Toiyama Cecilia Egoavil Estefania Rojas Carla Guarinos Montserrat Andreu Xavier Llor Antoni Castells Rodrigo Jover C. Richard Boland Ajay Goel 《PloS one》2014,9(8)
Background and Aim
Aberrant hypermethylation of cancer-related genes has emerged as a promising strategy for the development of diagnostic, prognostic and predictive biomarkers in human cancer, including colorectal cancer (CRC). The aim of this study was to perform a systematic and comprehensive analysis of a panel of CRC-specific genes as potential diagnostic, prognostic and predictive biomarkers in a large, population-based CRC cohort.Patients and Methods
Methylation status of the SEPT9, TWIST1, IGFBP3, GAS7, ALX4 and miR137 genes was studied by quantitative bisulfite pyrosequencing in a population-based cohort of 425 CRC patients.Results
Methylation levels of all genes analyzed were significantly higher in tumor tissues compared to normal mucosa (p<0.0001); however, cancer-associated hypermethylation was most frequently observed for miR137 (86.7%) and IGFBP3 (83%) in CRC patients. Methylation analysis using the combination of these two genes demonstrated greatest accuracy for the identification of colonic tumors (sensitivity 95.5%; specificity 90.5%). Low levels of IGFBP3 promoter methylation emerged as an independent risk factor for predicting poor disease free survival in stage II and III CRC patients (HR = 0.49, 95% CI: 0.28–0.85, p = 0.01). Our results also suggest that stage II & III CRC patients with high levels of IGFBP3 methylation do not benefit from adjuvant 5FU-based chemotherapy.Conclusion
By analyzing a large, population-based CRC cohort, we demonstrate the potential clinical significance of miR137 and IGFBP3 hypermethylation as promising diagnostic biomarkers in CRC. Our data also revealed that IGFBP3 hypermethylation may serve as an independent prognostic and predictive biomarker in stage II and III CRC patients. 相似文献93.
Lynch LF Lynch MI Ferreira RS Vasconcelos MS Melo N Ferreira S Malagueño E 《Memórias do Instituto Oswaldo Cruz》2011,106(5):625-628
Ocular toxoplasmosis can result in recurrent uveitis. Studies have shown that a correlation between active ocular toxoplasmosis and the presence of anti-Toxoplasma gondii secretory IgA (SIgA) in tears. This study compares anti-T. gondii SIgA levels in patients' tears during the acute and inactive phases of toxoplasmic uveitis. Twenty-nine positive tear specific SIgA for T. gondii patients with acute toxoplasmic uveitis were selected and were followed-up for at least two years, when the anti-T. gondii SIgA tears levels were determined. Specific SIgA for T. gondii was negative in 22 patients (75.86%) and positive in seven patients (24.13%) of whom six (85.7%) were followed over three years. Average SIgA levels during the acute phase are 1.54 and decrease significantly to 0.72 (p = 0.0001) during the inactive phase of disease. Because anti-T. gondii SIgA in the tear is negative in 75.86% of patients after the acute phase of infection, T. gondii SIgA levels may be used as a complementary diagnostic marker for active ocular toxoplasmosis. 相似文献
94.
J. H. Medina C. Peña M. Piva C. Wolfman M. L. de Stein C. Wasowski C. Da Cunha I. Izquierdo A. C. Paladini 《Molecular neurobiology》1992,6(4):377-386
Great progress has been made in the last 5 yr in demonstrating the presence of benzodiazepines (BDZs) in mammalian tissues,
in beginning studies on the origin of these natural compounds, and in elucidating their possible biological roles. Many unanswered
questions remain regarding the sources and biosynthetic pathways responsible for the presence of BDZs in brain and their different
physiological and/or biochemical actions. This essay will focus on recent findings supporting that: (1) BDZs are of natural
origin; (2) mammalian brain contains BDZs in concentrations ranging between 5.10−10–10−8
M; (3) dietary source of BDZs might be a plausible explanation for their occurrence in animal tissues, including man; (4) the
formation of BDZ-like molecules in brain is a possibility, experimentally supported; (5) BDZ-like molecules including diazepam
andN-desmethyldiazepam are elevated in hepatic encephalopathy; and (6) natural BDZs in the brain are involved in the modulation
of memory processes. Future studies using the full range of biochemical, physiological, behavioral, and molecular biological
techniques available to the neuroscientist will hopefully continue to yield exciting and new information concerning the biological
roles that BDZs might play in the normal and pathological functioning of the brain. 相似文献
95.
Caufriez A Moreno-Reyes R Leproult R Vertongen F Van Cauter E Copinschi G 《American journal of physiology. Endocrinology and metabolism》2002,282(5):E1147-E1153
To investigate the adaptation of plasma cortisol profiles to an abrupt phase advance of the rest-activity cycle, eight normal young subjects were submitted in a sleep laboratory to an 8-h advance shift of their sleep-wake and dark-light cycles. The shift was achieved by advancing bedtimes from 2300-0700 to 1500-2300. Blood samples were obtained at 20-min intervals for 68 consecutive hours. The shift resulted within 6-9 h in a 3- to 4-h advance of timings of the nadir of the cortisol profile and of the end of the quiescent period but had no immediate effect on the timing of cortisol acrophase. The quiescent period of cortisol secretion was shortened and fragmented. Thus a major advance shift achieved without enforcing sleep deprivation results in a rapid partial adaptation of the temporal profiles of cortisol but also in a marked disruption of the cortisol quiescent period. Sleep onset was consistently followed by a decrease in cortisol concentrations. Conversely, both sleep-wake and dark-light transitions were consistently associated with cortisol secretory pulses. 相似文献
96.
In many plant species with multiovulate ovaries, a considerable reduction in the number of ovules takes place. However, the
underlying physiological causes are not clear. In Prunus spp., although flowers present two ovules, usually only one seed is produced. We have followed the development and degeneration
of the two ovules in apricot (Prunus armeniaca L.) and examined the extent to which carbohydrates within the ovule might be involved in determining the fate of the ovule.
While the primary ovule grows in the days following anthesis, growth of the secondary ovule is arrested. Starch distribution
along the different ovular tissues exhibits several changes that are different in the two ovules. Primary ovule growth is
inversely related to starch content and this growth takes place independently of pollination since it occurs in the same way
in pollinated and unpollinated flowers. In the secondary ovule, starch disappears simultaneously from all ovular structures
and callose is layered at the chalazal end of the nucellus. The size of the secondary ovule does not change significantly
from anthesis to degeneration, and callose starts to accumulate 5 days after anthesis. Likewise, this process occurs independently
of pollination. These results are discussed in terms of the implications of the starch content of ovules in fertilization
success and ovule fate.
Received: 26 August 1997 / Revision accepted: 17 December 1997 相似文献
97.
Jaqueline Inês Alves de Andrade Eduardo Akifumi Ono Glauber Cruz de Menezes Elenice Martins Brasil Rodrigo Roubach Elisabeth Criscuolo Urbinati Marcos Tavares-Dias Jaydione Luiz Marcon Elizabeth Gusmo Affonso 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2007,146(4):576
This study evaluated the influence of diets supplemented with 500, 800, 1200 mg kg− 1 of vitamin C (ascorbic acid or AA) and vitamin E (α-tocopherol or α-T) on the physiological responses of pirarucu fed for 2 months. Weight and mortality were not affected by dietary vitamin type or their concentrations. Significant increase (p < 0.05) on the red blood cells count was obtained on treatments with 800 and 1200 mg AA kg− 1 and on the hemoglobin concentration on treatment with 500 mg α-T kg− 1 relatively to control. Mean corpuscular volume presented a significant decrease (p < 0.05) on treatment with 800 and 1200 mg AA kg−1 when compared to control. Mean corpuscular hemoglobin concentration was significantly high (p < 0.05) on treatment with 500 mg α-T kg− 1. Only in vitamin C treatments, we noticed a significant increase (p < 0.05) in the number of leucocytes relative to control. All fish in the vitamin-supplemented treatments, except 500 mg AA kg− 1, had high total protein values compared to control. Fish treated with 800 or 1200 mg α-T kg− 1 also showed increases in plasma glucose concentrations. Our results suggest that 800 and 1200 mg AA kg− 1 are probably the most suitable concentrations for pirarucu diets, although high vitamin E diets are not necessary for quantitative leucocyte increases for this species. 相似文献
98.
Del Rio R Muñoz C Arias P Court FA Moya EA Iturriaga R 《American journal of physiology. Lung cellular and molecular physiology》2011,301(5):L702-L711
Chronic intermittent hypoxia (CIH), a characteristic of sleep obstructive apnea, enhances carotid body (CB) chemosensory responses to hypoxia, but its consequences on CB vascular area and VEGF expression are unknown. Accordingly, we studied the effect of CIH on CB volume, glomus cell numbers, blood vessel diameter and number, and VEGF immunoreactivity (VEGF-ir) in male Sprague-Dawley rats exposed to 5% O(2), 12 times/h for 8 h or sham condition for 21 days. We found that CIH did not modify the CB volume or the number of glomus cells but increased VEGF-ir and enlarged the vascular area by increasing the size of the blood vessels, whereas the number of the vessels was unchanged. Because oxidative stress plays an essential role in the CIH-induced carotid chemosensory potentiation, we tested whether antioxidant treatment with ascorbic acid may impede the vascular enlargement and the VEGF upregulation. Ascorbic acid, which prevents the CB chemosensory potentiation, failed to impede the vascular enlargement and the increased VEGF-ir. Thus present results suggest that the CB vascular enlargement induced by CIH is a direct effect of intermittent hypoxia and not secondary to the oxidative stress. Accordingly, the subsequent capillary changes may be secondary to the mechanisms involved in the neural chemosensory plasticity induced by intermittent hypoxia. 相似文献
99.
100.
Recently the squid pens, a rich source of beta-chitin containing low contents of inorganic compounds, have become available in considerable amounts as a refuse of the fishery industries in Brazil. Thus, the aim of this work is to use squid pens from Loligo sanpaulensis and Loligo plei, species found in the Brazilian coast, as the raw material for the extraction of beta-chitin. The squid pens were submitted to the usual sequence of treatments used for chitin extraction - demineralization and deproteinization - but due to its low content of inorganic compounds a two-step alkaline treatment was enough to produce beta-chitin with low contents of ash (< or = 0.7%). Indeed, the low contents of ash and metals, such as Ca (< or = 10.4 ppm), Mg (< or = 2.5 ppm), Mn (< or = 3.1 ppm) and Fe (< or = 1.8 ppm), are lower than those reported in most of the papers found in the literature. Also, the beta-chitin extracted by employing only the alkaline treatment was more acetylated than the other samples prepared in this work. Regardless of the treatment employed for the extraction of the beta-chitin from the squid pens, its infrared spectra and X-ray diffraction pattern presented only minor differences, however they were clearly distinguished from commercial alpha-chitin. 相似文献