185 research outputs found
Fault Determination due to Sinkhole Array on Lar Valley, Northeast of Tehran (Iran)
The main objective of this paper is to present an approach to identify active faults in karstic enviroments. This is achieved by a releasing relationship between sinkholes or dolines formation, array and active faults mechanism. In this research , Lar valley on the Northeast of Tehran, Capital of Iran was selected as a case study. The sinkholes array in the valley shows that their formation and location is influenced by active faults. As a result of active faults mechanism, a number of young and old dolines have been formed on north and south of the study area. According to Aerial Photographs, Satellite images and geological logs corelation three major active faults were distingushed in the study area specially under Lar dam structure. Two of the faults are elongated to the north and the one extends to the south, seven sinkholes were formed on faults. Based on the available evidences, it is assumed that the formation and array of dolines in the study area has been formed and controlled by active faults. Conversely , it is deduced that faults activity may be determinated by sinkholes formation and array. This results may be applied for the similar cases of world's karstic belt
A Study on the Origin of Peroxisomes: Possibility of Actinobacteria Symbiosis
The origin of peroxisomes as having developed from the endoplasmic reticulum (ER) was proposed on the basis of the similarity between some peroxisomal proteins and ER proteins, and the localization of some peroxisomal proteins on the ER. To study the evolutionary distance between peroxisomes and ER and Prokaryotes, we carried out a phylogenetic analysis of CDC48 (cell division control 48) and its homologs, including ER-localized CDC48, CDC48 homologs in Prokaryotes and peroxisome-localized PEX1 and PEX6. A similarity search analysis of peroxisomal protein sequences to prokaryotic protein sequences using BLAST at several thresholds (E-values) was also done. We propose Actinobacteria symbiosis for the origin of peroxisomes based on the following evidence: (1) PEX1 and PEX6 are close in distance to CDC48 homologs in Actinobacteria, and these distances are closer than to ER-localized CDC48. (2) Actinobacteria proteins show the highest degree of similarity to peroxisomal proteins compared with other prokaryotes
Effects of nicorandil, a potassium channel opener, on idiopathic ventricular tachycardia
AbstractObjectives. We assessed the effects of the adenosine triphosphate (ATP)–sensitive potassium channel opener, nicorandil, on ATP- and verapamil-responsive ventricular tachycardias (VTs).Background. Adenosine- or ATP-sensitive VTs are thought to be due to a nonreentrant mechanism, presumably delayed afterdepolarization. We suggest that this potassium channel opener may suppress ATP- and verapamil-sensitive VTs.Methods. The subjects included 13 patients with idiopathic VTs, 7 of whom had sustained VT and 6 of whom had nonsustained VT. We evaluated the effects of ATP, nicorandil and verapamil on VTs.Results. Sustained VT: Verapamil had preventive effects on seven VTs. Four VTs were terminated by ATP, and of these, nicorandil terminated two and prevented exercise-induced VT in the two others. Three ATP-insensitive VTs, which were determined to be due to a reentry by an electrophysiologic study, were not terminated by nicorandil. Nonsustained VT: All six VTs were inhibited by ATP, and five of these were suppressed by nicorandil. Verapamil inhibited four of the five VTs. QT intervals and the corrected QT intervals were significantly shortened by nicorandil.Conclusions. Nicorandil suppresses ATP- and verapamil-responsive VTs. One of the mechanisms of suppression by nicorandil might be related to a reduction of calcium in the myocardium, because it reduces the action potential duration
Pituitary adenylate cyclase-activating polypeptide type 1 receptor signaling evokes long-lasting nociceptive behaviors through the activation of spinal astrocytes in mice
AbstractIntrathecal (i.t.) administration of pituitary adenylate cyclase-activating polypeptide (PACAP) induces long-lasting nociceptive behaviors for more than 60 min in mice, while the involvement of PACAP type1 receptor (PAC1-R) has not been clarified yet. The present study investigated signaling mechanisms of the PACAP-induced prolonged nociceptive behaviors. Single i.t. injection of a selective PAC1-R agonist, maxadilan (Max), mimicked nociceptive behaviors in a dose-dependent manner similar to PACAP. Pre- or post-treatment of a selective PAC1-R antagonist, max.d.4, significantly inhibited the nociceptive behaviors by PACAP or Max. Coadministration of a protein kinase A inhibitor, Rp-8-Br-cAMPS, a mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase inhibitor, PD98059 or a c-Jun N-terminal kinase (JNK) inhibitor, SP600125, significantly inhibited the nociceptive behaviors by Max. Immunohistochemistry and immunoblotting analysis revealed that spinal administration of Max-induced ERK phosphorylation and JNK phosphorylation, and also augmented an astrocyte marker, glial fibrillary acidic protein in mouse spinal cord. Furthermore, an astroglial toxin, l-α-aminoadipate, significantly attenuated the development of the nociceptive behaviors and ERK phosphorylation by Max. These results suggest that the activation of spinal PAC1-R induces long-lasting nociception through the interaction of neurons and astrocytes
New Insights into SNR Evolution Revealed by the Discovery of Recombining Plasmas
We report the discovery of recombining plasmas in three supernova remnants
(SNRs) with the Suzaku X-ray astronomy satellite. During SNR's evolution, the
expanding supernova ejecta and the ambient matter are compressed and heated by
the reverse and forward shocks to form an X-ray emitting hot plasma. Since
ionization proceeds slowly compared to shock heating, most young or middle-aged
SNRs have ionizing (underionized) plasmas. Owing to high sensitivity of Suzaku,
however, we have detected radiative recombination continua (RRCs) from the SNRs
IC 443, W49B, and G359.1-0.5. The presence of the strong RRC is the definitive
evidence that the plasma is recombining (overionized). As a possible origin of
the overionization, an interaction between the ejecta and dense circumstellar
matter is proposed; the highly ionized gas was made at the initial phase of the
SNR evolution in dense regions, and subsequent rapid adiabatic expansion caused
sudden cooling of the electrons. The analysis on the full X-ray band spectrum
of IC 443, which is newly presented in this paper, provides a consistent
picture with this scenario. We also comment on the implications from the fact
that all the SNRs having recombining plasmas are correlated with the
mixed-morphology class.Comment: Published by Advances in Space Researc
Testing the External Shock Model of Gamma-Ray Bursts using the Late-Time Simultaneous Optical and X-ray Afterglows
We study the ``normal'' decay phase of the X-ray afterglows of gamma-ray
bursts (GRBs), which follows the shallow decay phase, using the events
simultaneously observed in the R-band. The classical external shock model -- in
which neither the delayed energy injection nor time-dependency of shock
micro-physics is considered -- shows that the decay indices of the X-ray and
R-band light curves, and , obey a certain
relation, and that in particular, should be
larger than -1/4 unless the ambient density increases with the distance from
the central engine. For our selected 14 samples, we have found that 4 events
violate the limit at more than the 3 level, so that a fraction of
events are outliers of the classical external shock model at the ``normal''
decay phase.Comment: Accepted for publication in ApJL. 12 page, 2 figures, 2 table
Relationship between serum concentrations of saturated fatty acids and unsaturated fatty acids and the homeostasis model insulin resistance index in Japanese patients with type 2 diabetes mellitus
Background : Consumption of polyunsaturated fatty acids (PUFA) improves the lipid metabolism of diabetics, leading to prevents of arteriosclerosis. Exact relationship between saturated fatty acids (SFA) or PUFA and the insulin resistance of diabetics are unknown.
Subjects and Methods : We investigated the relationship between the serum concentrations of saturated and unsaturated fatty acids and the homeostasis model insulin resistance index (HOMA-R) in Japanese patients with type 2 diabetes mellitus.
Results : The SFA, i.e., lauric acid, myristic acid, palmitic acid, and stearic acid ; the monounsaturated fatty acids (MUFA), i.e., palmitoleic acid, oleic acid, and erucic acid ; and the PUFA, i.e., eicosadienoic acid, dihomo-γ-linolenic acid, docosatetraenoic acid, and docosapentaenoic acid were positively correlated with HOMA-R. However, no correlations were found between HOMA-R and SFA, i.e., arachidic acid, behenic acid, and lignoceric acid ; the MUFA, i.e., eicosenoic acid and nervonic acid ; and the PUFA, i.e., linoleic acid, γ-linolenic acid, linolenic acid, 5-8-11 eicosatrienoic acid, arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid.
Conclusions : Some PUFA as well as SFA were positively correlated with HOMA-R. These results indicate that the intake of diet fatty acid must be well balanced in diabetic patients and it is not always true to refrain from taking SFA and increase the unsaturated fatty acids in their diets
The Satb1 Protein Directs Hematopoietic Stem Cell Differentiation toward Lymphoid Lineages
SummaryHow hematopoietic stem cells (HSCs) produce particular lineages is insufficiently understood. We searched for key factors that direct HSC to lymphopoiesis. Comparing gene expression profiles for HSCs and early lymphoid progenitors revealed that Satb1, a global chromatin regulator, was markedly induced with lymphoid lineage specification. HSCs from Satb1-deficient mice were defective in lymphopoietic activity in culture and failed to reconstitute T lymphopoiesis in wild-type recipients. Furthermore, Satb1 transduction of HSCs and embryonic stem cells robustly promoted their differentiation toward lymphocytes. Whereas genes that encode Ikaros, E2A, and Notch1 were unaffected, many genes involved in lineage decisions were regulated by Satb1. Satb1 expression was reduced in aged HSCs with compromised lymphopoietic potential, but forced Satb1 expression partly restored that potential. Thus, Satb1 governs the initiating process central to the replenishing of lymphoid lineages. Such activity in lymphoid cell generation may be of clinical importance and useful to overcome immunosenescence
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