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.

Effect of the promoter presence in catalysts on the compositions of Fischer–Tropsch synthesis products

DenizUykun Mangaloğlu,Murat Baranak,Özlem Ataç,Hüsnü Atakül 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-

The effects of alkali promoters namely potassium, copper, and manganese, on the performance of the bi-functional iron–low acidity ZSM-5 catalysts in the Fischer–Tropsch (FT) synthesis were studied. ZSM-5 with very high silica alumina ratio (SAR) of 280 was used to take advantage of its shape selectivity and suppressing the effect of alkali migration on zeolite cation exchange sites. One bi-functional iron base catalyst (FeZ), three single promoted (KFeZ, CuFeZ, MnFeZ) and four multiple promoted (CuKFeZ, CuMnFeZ, KMnFeZ, CuKMnFeZ) catalysts were synthesized by the incipient to wetness impregnation method. They were characterized by XRD, BET, TPR, TEM and TPD analyses methods and tested for their FT synthesis activities. Promoters had considerable impacts on the compositions and the hydrocarbon distributions of the FT synthesis products. Addition of promoters resulted in an increase of up to 8.5–56% and 20–743% in the synthesis of gasoline and diesel range hydrocarbons, respectively. Consequently, the production of the total liquid fuel (gasoline + diesel) also increased from 48% (base catalyst) to 64–79% (promoted catalysts). The highest gasoline range hydrocarbon production was obtained from MnFeZ and CuKMnFeZ (≈70%) while CuKMnFeZ produced a FT product having the highest total liquid fuel (≈79%).

Efficacy of Trimetazidine Dihydrochloride for Relieving Chronic Tinnitus: A Randomized Double-Blind Study

Tolgar Lütfi Kumral,Güven Yıldırım,Güler Berkiten,Ziya Saltürk,Enes Ataç,Yavuz Atar,Yavuz Uyar 대한이비인후과학회 2016 Clinical and Experimental Otorhinolaryngology Vol.9 No.3

Objectives: To evaluate the efficacy of trimetazidine dihydrochloride as a treatment for chronic tinnitus. Methods: A total of 97 chronic tinnitus patients were evaluated in this randomized, prospective, double-blind, placebo-controlled trial. After assessing for eligibility, 82 patients were randomly assigned into placebo or trimetazidine groups according to the medication. The trimetazidine group received 20×3 mg/day per oral trimetazidine dihydrochloride and the placebo group received 20×3 mg/day per oral placebo for 3 months. Tinnitus handicap inventory (THI), visual analogue scale (VAS) questionnaires and audiometric results were used to determine the effectiveness of trimetazidine treatment. Results: The study group comprised 82 tinnitus subjects, 42 (51%) of whom received trimetazidine dihydrochloride and 40 (49%) who received placebo. There was no significant difference between placebo and trimetazidine groups in THI grade and VAS (both pre- and posttreatment scores) (P>0.05) and no significant improvement was observed in subjective loudness score in either group (P>0.05). Additionally there was no significant difference between groups in pre- and posttreatment pure tone hearing thresholds at all measured frequencies (P>0.05). Conclusion: Trimetazidine dihydrochloride therapy was ineffective for relieving chronic tinnitus.

Association of Adipokines, Insulin Resistance, Hypertension and Dyslipidemia in Patients with Psoriasis Vulgaris

( Melis Coban ),( Levent Tasli ),( Sebahat Turgut ),( Seyma Ozkan ),( Melek Tunc Ata1 ),( Fulya Akın ) 대한피부과학회 2016 Annals of Dermatology Vol.28 No.1

Background: Systemic inflammation in psoriasis causes insulin resistance and cardiovascular diseases. Adipokines are adipose-tissue-derived factors that are involved in metabolic processes. It is thought that these adipokines are associated with the development of psoriasis. Objective: The purpose of this study was to determine the changes in adipokine levels, insulin resistance, hypertension, and dyslipidemia over a 12-week period. Methods: The study comprised 35 psoriasis patients and 50 controls. Blood samples were obtained twice from the patients, one sample at the start and one at the end of a 12-week follow-up period. The following parameters were assessed in both groups: serum fasting glucose, fasting insulin, homeostasis model assessment-estimated insulin resistance (HOMA-IR) index, serum lipids, adiponectin, leptin, resistin, chemerin, omentin, vaspin, visfatin, retinol-binding protein 4, and high-sensitivity C-reactive protein (hs-CRP) levels; blood pressure; body mass index; and the psoriasis area severity index (PASI) scores. Results: The patients showed an improvement in the PASI score and a significant decrease in serum hs-CRP, omentin, and chemerin values. Moreover, at the start of the follow-up, the psoriasis patients had significantly lower levels of adiponectin and visfatin and significantly higher levels of vaspin and resistin than those of the control group. Visfatin levels correlated negatively with low-density lipoprotein (LDL) and cholesterol, while vaspin and omentin levels correlated positively with diastolic blood pressure. Decreased adiponectin levels correlated negatively with diastolic blood pressure and LDL. Conclusion: Plasma levels of adipokines might be useful for evaluating the disease activity of psoriasis and its comorbidities.

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.

Development of Collagen/Poly(vinyl alcohol)/Chondroitin Sulfate and Collagen/Poly(vinyl alcohol)/HA Electrospun Scaffolds for Tissue Engineering

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.

Hb Murcia (β118(G19)His>Gln): A New Hemoglobin Variant Found in a Spanish Woman

Fernández Beatriz González,Campuzano José Bartolomé Nieto,Rocamora Dolores García,Nieto Jorge M,Fernández Fernando Ataúlfo González,Villegas Ana,Cuesta Celina Benavente,Ropero Paloma 대한진단검사의학회 2021 Annals of Laboratory Medicine Vol.41 No.5

Interfacial stress assessment at the cracked zones in CFRP retrofitted RC beams

Ata Hojatkashani,Mohammad Zaman Kabir 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.6

In this work, an experimental examination was carried out to study interfacial stresses developed at the junction zones between carbon fiber reinforced plastic (CFRP) fabrics (~1 mm thickness) and tensile concrete portion in CFRP retrofitted RC beams. In this respect, initially six similar RC beams of 150 × 150 × 1000 mm dimensions were prepared. Three of which were strengthened with CFRP fabrics at the tensile side of the beams. Furthermore, a notch was cut at the center of the bottom surface for all of the studied beams. The notch was 15 mm deep and ran across the full width of tension side of the beams. The mentioned interfacial stresses could be calculated from strains measured using strain gauges mounted on the interface zone of the tensile concrete and the CFRP sheet. Based on the results obtained,it is shown that interfacial stresses developed between CFRP fabrics and RC beam had a noticeable effect on debonding failure mode of the latter. The load carrying capacity of CFRP strengthened RC specimens increased ~75% compared to that of the control RC beams. This was attributed to the enhancement of flexural mode of the former. Finally, finite element analysis was also utilized to verify the measured experimental results.

Hybrid fuzzy model to predict strength and optimum compositions of natural Alumina-Silica-based geopolymers

Ata Allah Nadiri,Somayeh Asadi,Hamed Babaizadeh,Keivan Naderi 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.1

This study introduces the supervised committee fuzzy model as a hybrid fuzzy model to predict compressive strength (CS) of geopolymers prepared from alumina-silica products. For this purpose, more than 50 experimental data that evaluated the effect of Al2O3/SiO2, Na2O/Al2O3, Na2O/H2O and Na/[Na+K] on (CS) of geopolymers were collected from the literature. Then, three different Fuzzy Logic (FL) models (Sugeno fuzzy logic (SFL), Mamdani fuzzy logic (MFL), and Larsen fuzzy logic (LFL)) were adopted to overcome the inherent uncertainty of geochemical parameters and to predict CS. After validating the model, it was found that the SFL model is superior to MFL and LFL models, but each of the FL models has advantages to predict CS. Therefore, to achieve the optimal performance, the supervised committee fuzzy logic (SCFL) model was developed as a hybrid method to combine the benefits of individual FL models. The SCFL employs an artificial neural network (ANN) model to re-predict the CS of three FL model predictions. The results also show significant fitting improvement in comparison with individual FL models.

Microbial Flora of Normal and Abnormal Cervical Mucous Discharge Associated with Reproductive Performance of Cows and Heifers in Estrus

Ata, Ayhan,Turutoglu, Hulya,Kale, Mehmet,Gulay, Mehmet Sukru,Pehlivanoglu, Faruk Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.8

The aim of the present study was to describe whether abnormal cervical mucus discharge (A-CMD) or pathogens in cervical mucus discharge (CMD) have effects on reproductive performance of cows and heifers in estrus. Animals having clear discharges (68 cows, 38 heifers) with normal viscosity and without bad odor were grouped as normal cervical mucous discharge (N-CMD) group. The other animals (84 cows, 32 heifers) were grouped as A-CMD group. Microorganisms isolated from samples were divided into three groups as uterine pathogens (UP), potential uterine pathogens (PUP) or opportunistic uterine pathogens (OUP). Presence of PUP was associated with A-CMD for both cows (p<0.01) and heifers (p<0.02). First service conception rates (FS-CR) were lower in cows positive for PUP (p<0.01). Moreover, presence of PUP and OUP affected FS-CR in heifers (p<0.01). Although A-CMD significantly affected FS-CR in cows (p<0.04), it did not affect FS-CR in heifers. Differences in average open day for cows (p<0.02) and first service age for heifers (p<0.01) were significant between N-CMD and A-CMD groups, respectively. The current study suggested that CMD should be evaluated more carefully when there are infertility problems. In addition to the known microorganism that causes sterility and infertility in the UP group, pathogens in the PUP group should be considered for their potential to cause infertility.