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RISS 인기검색어
- 검색키워드
- 저자 : Ataúlfo Martínez-Torres (검색결과 3 건)
- 무료
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Functional and Structural Effects of Amyloid-beta Aggregate on Xenopus laevis Oocytes
Jorge Parodi,Ataúlfo Martínez-Torres,Lenin Ochoa-de la Paz,Ricardo Miledi 한국분자세포생물학회 2012 Molecules and cells Vol.34 No.4
Xenopus laevis oocytes exposed to amyloid- aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. The cells exhibited a series of “spontaneous” blips ranging in amplitude from 3.8 0.9 nA at the beginning of the recordings to 6.8 1.7 nA after 15 min of exposure to 1 M aggregate. These blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin B (7.8 1.2 nA) and gramicidin (6.3 1.1 nA). The amyloid aggregate-induced currents were abolished when extracellular Ca2+ was removed from the bathing solution, suggesting a central role for this cation in generating the spontaneous electric activity. The amyloid aggregate also affected the Ca2+-dependent Cl- currents of oocytes, as shown by increased amplitude of the transient-outward chloride current (Tout) and the serum-activated, oscillatory Cl- currents. Electron microcopy revealed that amyloid aggregate induced the dissociation of the follicular cells that surround the oocyte, thus leading to a failure in the electro-chemical communication between these cells. This was also evidenced by the suppression of the oscillatory Ca2+-dependent ATP-currents, which require proper coupling between oocytes and the follicular cell layer. These observations, made using the X. laevis oocytes as a versatile experimental model, may help to understand the effects of amyloid aggregate on cellular communication.
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Ion Currents Induced by ATP and Angiotensin II in Cultured Follicular Cells of Xenopus laevis
Marcelino Montiel-Herrera,Ana María Zaske,Jesús García-Colunga,Ataúlfo Martínez-Torres,Ricardo Miledi 한국분자세포생물학회 2011 Molecules and cells Vol.32 No.5
Xenopus laevis oocytes are commonly used to study the biophysical and pharmacological properties of foreign ion channels and receptors, but little is known about those endogenously expressed in their enveloping layer of follicular cells (FCs). Whole-cell recordings and the perforated patch-clamp technique in cultured FCs held at -60mV revealed that ATP (20-250 μM) generates inward currents of 465 ± 93 pA (mean ± standard error) in ∼60% of the FCs studied, whereas outward currents of 317 ± 100 pA were found in ∼5% of the cells. The net effect of ATP on the FCs was to activate both mono- and biphasic inward currents,with an associated increase in membrane chloride conductance. Two-microelectrode voltage-clamp recordings of nude oocytes held at -60 mV disclosed that ATP elicited biphasic inward currents, corresponding to the well-known Fin and Sin-like currents. ATP receptor antagonists like suramin, TNP-ATP, and RB2 did not inhibit any of these responses. On the other hand, when using wholecell recordings, 1 μM Ang II yielded smooth inward currents of 157 ± 45 pA in ∼16% of the FC held at -60 mV. The net Ang II response, mediated by the activation of the AT1receptor, was a chloride current inhibited by 10 nM ZD7155. This study will help to better understand the roles of ATP and Ang II receptors in the physiology of X. laevis oocytes.
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Luis Humberto Delgado-Rangel,Julia Hernández-Vargas,Marymar Becerra-González,Ataúlfo Martínez-Torres,Evgen Prokhorov,J. Betzabe González Campos 한국섬유공학회 2019 Fibers and polymers Vol.20 No.12
The combination of collagen (CG), chondroitin sulfate (CS), and hyaluronic acid (HA) with poly(vinyl alcohol)(PVA) was explored to produce 3D tri-component scaffolds with enhanced mechanical properties and potential use in tissueengineering. The CG/PVA/CS and CG/PVA/HA electrospun scaffolds were crosslinked with citric acid, a cytocompatiblecrosslinker, which induced improved mechanical properties in both dry and wet state, especially with large elongation atbreak in the wet state. Ultimate tensile stress under the dry and wet state are significantly higher than those previouslyreported about collagen based nanofibers. IR, DSC and dielectric analysis demonstrated homogenous blending without phaseseparation and strong interactions between components. All scaffolds had swelling pH-sensitive behavior, making thempromising materials for drug delivery systems. The nanofiber mats permitted adhesion and proliferation of human embryonickidney cells; this cell line formed clusters that adapted well to the mats’ surface, through which the cells extended theirprocesses.
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