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81.
Ortiga-Carvalho TM Oliveira Kde J Morales MM Martins VP Pazos-Moura CC 《Experimental biology and medicine (Maywood, N.J.)》2003,228(9):1083-1088
Neuromedin B (NB), a bombesin-like peptide, highly concentrated in rat pituitary gland, has been shown to act as an autocrine/paracrine inhibitor of thyrotropin (TSH) release. Here it is shown that a single injection of thyrotropin-releasing hormone (TRH, 1.5 microg/animal, ip), the most important stimulator of thyrotropin secretion, induced approximately 35%-45% decrease in pituitary NB content in rats, as well as an important decrease in NB mRNA at 15 and 30 min (P < 0.05). Acute cold exposure, which induced higher serum TSH with a peak at 30 min, was associated with progressive decrease in pituitary NB, starting at 15 min although only reaching statistical significance after 2 hr (P < 0.05). Although not involved in the early peak, the decrease in NB may be contributing to maintenance of higher serum TSH in cold-exposed animals compared with those at room temperature. Fed rats, 2 hr after being subcutaneously injected with mouse recombinant leptin (8 microg /100 g body wt), showed a x2 increase in serum TSH and 38% reduction in pituitary NB (P < 0.05). In conclusion, TRH and leptin rapidly decreased pituitary NB and it is first proposed that the reduction of the inhibitory tonus of NB on TSH release will ultimately contribute to the amplification of TSH secretion elicited by TSH secretagogues. 相似文献
82.
83.
Lisboa PC Oliveira KJ Cabanelas A Ortiga-Carvalho TM Pazos-Moura CC 《American journal of physiology. Endocrinology and metabolism》2003,284(6):E1172-E1176
We investigated the effect of acute cold exposure, leptin, and the somatostatin analog octreotide (OCT) on thyroid type I (D1) and II (D2) deiodinase activities. Microsomal D1 and D2 activities were measured by the release of (125)I from (125)I-reverse triiodothyronine (rT(3)) under different assay conditions. Rats exposed to 4 degrees C (15, 30, 60, and 120 min) showed progressive reduction in thyroidal D1 and D2, reaching approximately 40% at 2 h (P < 0.05) despite increased circulating TSH (P < 0,05) associated with the higher thyroid D1 and D2 in hypothyroid rats. A single injection of leptin (8 microg/100 g body wt sc) induced increased thyroid and liver D1 (P < 0.05), but not thyroid D2, activities at 30 and 120 min, independently of the serum TSH rise shown only at 2 h. OCT (1 microg/kg body wt sc) increased D1 and D2 activity significantly 24 h after a single injection, with no changes in serum TSH. Therefore, leptin and somatostatin are potential physiological upregulators of thyroid deiodinases, and their low secretion during acute cold exposure may be a potential mechanism contributing to cold-induced reduction in thyroid deiodinase activity. 相似文献
84.
Methyl-CpG binding proteins identify novel sites of epigenetic inactivation in human cancer 总被引:18,自引:0,他引:18
Ballestar E Paz MF Valle L Wei S Fraga MF Espada J Cigudosa JC Huang TH Esteller M 《The EMBO journal》2003,22(23):6335-6345
85.
In the Drosophila leg, activation of Notch leads to the establishment of the joints that subdivide the appendage into segments. We find that mutations in bowl result in similar phenotypes to Notch, causing fusion and truncations of tarsal segments (tarsomeres) and, like its close relative Odd-skipped, Bowl is produced in response to Notch signalling at a subset of segment boundaries. However, despite the fact that bowl mutant clones result in fusion of tarsomeres, Bowl protein is only found at the t1/tibial and t5/pretarsal boundaries, not at tarsomere joints. One hypothesis to reconcile these data is that bowl has a role at an earlier stage in tarsal development. We therefore investigated the effects of bowl mutations on the expression of leg 'gap' genes that confer regional identity on the developing leg. Several of these genes have altered expression in bowl mutant cells. For example, bric-a-brac2 is normally expressed in the central part of the tarsus domain but expands into distal and proximal regions in bowl clones. Conversely, ectopic bowl leads to a reduction in bric-a-brac2, with a concomitant expansion of proximal (t1) and distal (t5) tarsomere fates. The bowl gene is therefore required for the elaboration of pattern in the tarsus and its effects suggest a progressive model for the determination of P/D identities. This mechanism might be important in the diversification of arthropod limbs, because it explains how segmented tarsomeres could have arisen from an ancestral limb with an unsegmented tarsus. 相似文献
86.
Emilie Saby Jesper Buchhave Poulsen Just Justesen Merike Kelve Maria Jesus Uriz 《Biochimie》2009,91(11-12):1531-1534
Sponges [porifera], the most ancient metazoans, contain modules related to the vertebrate immune system, including the 2′,5′-oligoadenylate synthetase (OAS). The components of the antiviral 2′,5′-oligoadenylate (2–5A) system (OAS, 2′-Phosphodiesterase (2′-PDE) and RNAse L) of vertebrates have not all been identified in sponges. Here, we demonstrate for the first time that in addition to the OAS activity, sponges possess a 2′-PDE activity, which highlights the probable existence of a premature 2–5A system. Indeed, Suberites domuncula and Crella elegans exhibited this 2–5A degrading activity. Upon this finding, two out of three elements forming the 2–5A system have been found in sponges, only a endoribonuclease, RNAse L or similar, has to be found. We suspect the existence of a complex immune system in sponges, besides the self/non-self recognition system and the use of phagocytosis and secondary metabolites against pathogens. 相似文献
87.
The relationship between autolytic degradation of ß(13),(14)-D-glucanand acid pH-induced extension of isolated Zea mays cell wallshas been investigated using a constant-load extension technique.Acidic buffer (4.5) was able to induce an additional extension(Ea) on cell walls already extended at pH 6.8 buffer under a20 g-mass load, indicating that the additional extension (Ea)was the parameter that better represented the effect of thedifferent treatments on the mechanical properties of maize coleoptilecell walls. The additional extension in response to acidic pHwas higher when cell walls had been previously autolysed for24 h at pH 5.5. Furthermore, the acid-pH effect was dependenton the presence during the constant load extension of some thermo-labilefactors, suggesting the participation of expansins. Acid pHincreased Ea of native cell walls through an increase in theplastic extension (Ep) in agreement with a one step mechanismleading directly to irreversible (plastic) wall extension assuggested by Cosgrove (1977). The autolytic degradation of ß(13),(14)-D-glucan was also able to modify the mechanicalproperties of maize coleoptile cell walls increasing its elasticextension (Ee) in response to pH 4.5 buffer but that modificationonly leads to an increase in wall extension when expansins areactive, suggesting a cooperation between ß-glucanturnover and expansin action. (Received August 5, 1998; Accepted March 16, 1999) 相似文献
88.
The ability to flexibly produce facial expressions and vocalizations has a strong impact on the way humans communicate, as it promotes more explicit and versatile forms of communication. Whereas facial expressions and vocalizations are unarguably closely linked in primates, the extent to which these expressions can be produced independently in nonhuman primates is unknown. The present work, thus, examined if chimpanzees produce the same types of facial expressions with and without accompanying vocalizations, as do humans. Forty-six chimpanzees (Pan troglodytes) were video-recorded during spontaneous play with conspecifics at the Chimfunshi Wildlife Orphanage. ChimpFACS was applied, a standardized coding system to measure chimpanzee facial movements, based on FACS developed for humans. Data showed that the chimpanzees produced the same 14 configurations of open-mouth faces when laugh sounds were present and when they were absent. Chimpanzees, thus, produce these facial expressions flexibly without being morphologically constrained by the accompanying vocalizations. Furthermore, the data indicated that the facial expression plus vocalization and the facial expression alone were used differently in social play, i.e., when in physical contact with the playmates and when matching the playmates’ open-mouth faces. These findings provide empirical evidence that chimpanzees produce distinctive facial expressions independently from a vocalization, and that their multimodal use affects communicative meaning, important traits for a more explicit and versatile way of communication. As it is still uncertain how human laugh faces evolved, the ChimpFACS data were also used to empirically examine the evolutionary relation between open-mouth faces with laugh sounds of chimpanzees and laugh faces of humans. The ChimpFACS results revealed that laugh faces of humans must have gradually emerged from laughing open-mouth faces of ancestral apes. This work examines the main evolutionary changes of laugh faces since the last common ancestor of chimpanzees and humans. 相似文献
89.
90.
Nathan W Brunner Roham T Zamanian Fumiaki Ikeno Yoshiaki Mitsutake Andrew J Connolly Eric Shuffle Ke Yuan Mark Orcholski Jennifer Lyons Vinicio A de Jesus Perez 《Comparative medicine》2015,65(3):217-224
Pulmonary arterial hypertension (PAH) is a devastating disorder characterized by progressive elevation of the pulmonary pressures that, in the absence of therapy, results in chronic right-heart failure and premature death. The vascular pathology of PAH is characterized by progressive loss of small (diameter, less than 50 μm) peripheral pulmonary arteries along with abnormal medial thickening, neointimal formation, and intraluminal narrowing of the remaining pulmonary arteries. Vascular pathology correlates with disease severity, given that hemodynamic effects and disease outcomes are worse in patients with advanced compared with lower-grade lesions. Novel imaging tools are urgently needed that demonstrate the extent of vascular remodeling in PAH patients during diagnosis and treatment monitoring. Optical coherence tomography (OCT) is a catheter-based intravascular imaging technique used to obtain high-resolution 2D and 3D cross-sectional images of coronary arteries, thus revealing the extent of vascular wall pathology due to diseases such as atherosclerosis and in-stent restenosis; its utility as a diagnostic tool in the assessment of the pulmonary circulation is unknown. Here we show that OCT provides high-definition images that capture the morphology of pulmonary arterial walls in explanted human lungs and during pulmonary arterial catheterization of an adult pig. We conclude that OCT may facilitate the evaluation of patients with PAH by disclosing the degree of wall remodeling present in pulmonary vessels. Future studies are warranted to determine whether this information complements the hemodynamic and functional assessments routinely performed in PAH patients, facilitates treatment selection, and improves estimates of prognosis and outcome.Abbreviations: OCT, optical coherence tomography; PAC, pulmonary artery catheter; PAH, pulmonary arterial hypertensionPulmonary arterial hypertension (PAH) is a devastating disorder characterized by progressive elevation of pulmonary pressures that, when untreated, can lead to chronic right heart failure and death.14 The vascular pathology of PAH is characterized by neointimal formation, medial thickening, intravascular thrombi and, in severe cases, intravascular clusters of disorganized endothelial cells that give rise to tortuous endovascular channels.8 Most of the early vascular lesions are found in small (diameter, less than 50 μm) pulmonary arteries. However, as the disease advances, pulmonary arteries (diameter, 50 μm or larger) proximal to these lesions also display evidence of luminal narrowing and medial thickening.7,8,15 Most patients with PAH are younger than those with chronic systemic vascular disorders (that is, coronary artery disease, peripheral vascular disease, systemic hypertension), whose vascular pathology involves mostly large to medium-sized arteries. However, both patient populations demonstrate various pathologic features, including vascular smooth-cell accumulation, neointimal formation, inflammation, luminal narrowing, and alterations in the composition of the extracellular matrix.6,17The only definite way to diagnose PAH is through right heart catheterization to directly measure the pressure in the pulmonary circulation. Although pulmonary angiography during right heart catheterization cannot be used to diagnose PAH, it provides supportive evidence of PAH by demonstrating significant peripheral small vessel loss and luminal narrowing in the remaining central vessels. Angiography can help clinicians visualize pulmonary vessels in real time, but this diagnostic technique has important limitations. The use of ionized contrast can cause allergic reactions and may trigger acute renal failure due to contrast-induced nephropathy.26 In addition, pulmonary angiography provides information regarding gross vessel appearance and small vessel perfusion but not about the state of vascular wall remodeling or the extent of luminal narrowing associated with PAH at any stage.5,16 Therefore, imaging techniques are urgently needed that complement the hemodynamic information obtained via right heart catheterization with a safe and reproducible method to assess vascular wall pathology, thereby allowing clinicians to correlate the clinical evolution of PAH with the progression of vascular pathology.The last decade has seen tremendous progress in the development of intravascular imaging modalities that can identify patients at risk for developing complications related to systemic vascular disease and therefore prevent disease-related morbidity and mortality.4 One such modality is optical coherence tomography (OCT), an imaging technique that uses a thin (diameter, 1.0 mm) wire and near-infrared light to capture micrometer-resolution, 3D images from within optical scattering media (for example, biologic tissue).1 Superior to other intravascular imaging techniques, OCT is frequently used in patients with coronary artery disease, where it provides high-resolution images of the coronary arterial wall that correlate highly with pathology seen in explanted vessels.10,11,21 To date, several small studies have demonstrated the application of OCT to the evaluation of vascular remodeling in both idiopathic PAH and chronic thromboembolic PAH.7,21 However, despite OCT''s obvious advantages in the characterization of vascular remodeling in discrete segments of the pulmonary circulation, whether OCT provides anatomic information across the length of the pulmonary artery has not been tested.Here, we report the capacity of OCT to obtain both longitudinal and cross-sectional images that provide accurate anatomic information on healthy pulmonary arteries in explanted human lungs and during the pulmonary arterial catheterization of a live adult pig (Sus scrofa domesticus). 相似文献