688 research outputs found
Thyroid thermogenesis in adult rat hepatocytes in primary monolayer culture: direct action of thyroid hormone in vitro.
We have studied the effect of 3,5,3'-triiodothyronine (T3) on the respiration of adult rat hepatocytes in primary monolayer culture prepared from hypothyroid rat liver. After addition of T3 to the culture medium at a concentration of 2 x 10(-7) M, oxygen consumption of the cultured cells increased detectably at 24 h and was maximal at 72--96 h, relative to control cultures (38.0 +/- 1.8 vs. 25.0 +/- 1.5 microliter/h.mg protein). The thyroid-responsive enzymes, Na+ + K+-activated adenosine triphosphatase (NaK-ATPase) and alpha-glycerophosphate dehydrogenase (GPD), each exhibited increased activity in response to T3, in parallel with the change in oxygen consumption, whereas the activity of Mg-dependent ATPase was unaffected. These responses to T3 were dose dependent over similar concentration ranges, the half-maximal response for each occurring at ca 8 x 10(-10) M. In thyroid-treated cells, the observed increase in respiration was almost completely (90%) inhibited after addition of ouabain (10(-3) M) to the culture medium. It was found also that a 4-h exposure of the cultured hepatocytes to T3 was sufficient to elicit a significant thermogenic response, measured at a time (48 h later) when T3 was no longer present in the medium. The response to T3 occurred in fully defined culture medium and was independent of the presence or absence of hypothyroid rat serum, corticosterone, or insulin, and cellular ATP was unaffected by T3 in concentrations up to 2 x 10(-7) M. The findings document that adult rat hepatocytes in primary monolayer culture respond directly to thyroid hormone; the increases in respiration and NaK-ATPase activity elicited by T3 were cotemporal and apparently coordinate
Excited-state Forces within a First-principles Green's Function Formalism
We present a new first-principles formalism for calculating forces for
optically excited electronic states using the interacting Green's function
approach with the GW-Bethe Salpeter Equation method. This advance allows for
efficient computation of gradients of the excited-state Born-Oppenheimer
energy, allowing for the study of relaxation, molecular dynamics, and
photoluminescence of excited states. The approach is tested on photoexcited
carbon dioxide and ammonia molecules, and the calculations accurately describe
the excitation energies and photoinduced structural deformations.Comment: 2 figures and 2 table
A First-Principles Study of the Electronic Reconstructions of LaAlO3/SrTiO3 Heterointerfaces and Their Variants
We present a first-principles study of the electronic structures and
properties of ideal (atomically sharp) LaAlO3/SrTiO3 (001) heterointerfaces and
their variants such as a new class of quantum well systems. We demonstrate the
insulating-to-metallic transition as a function of the LaAlO3 film thickness in
these systems. After the phase transition, we find that conduction electrons
are bound to the n-type interface while holes diffuse away from the p-type
interface, and we explain this asymmetry in terms of a large hopping matrix
element that is unique to the n-type interface. We build a tight-binding model
based on these hopping matrix elements to illustrate how the conduction
electron gas is bound to the n-type interface. Based on the `polar catastrophe'
mechanism, we propose a new class of quantum wells at which we can manually
control the spatial extent of the conduction electron gas. In addition, we
develop a continuous model to unify the LaAlO3/SrTiO3 interfaces and quantum
wells and predict the thickness dependence of sheet carrier densities of these
systems. Finally, we study the external field effect on both LaAlO3/SrTiO3
interfaces and quantum well systems. Our systematic study of the electronic
reconstruction of LaAlO3/SrTiO3 interfaces may serve as a guide to engineering
transition metal oxide heterointerfaces.Comment: 50 pages, 18 figures and 4 table
V-06.02: Laparoscopic radical cystoprostatic adenectomy
Introduction: We hereby present a new
laparoscopic prostate-preserving cystectomy
technique that aims at reducing sexual dysfunction
and urinary incontinence in comparison
with the conventional technique of
laparoscopic radical cystoprostatectom
Assessment of oral acetazolamide on postoperative pain after laparoscopic cholecystectomy
Background and aim: Carbon dioxide (Co2) is used during laparoscopy for producing pneumoperttoneum. Combination of this gas with irrigation fluid in the abdomen produces carbonic acid which creates two kinds of abdominal and referred pain to right shoulder. In the present research we have studied the effect of oral acetazolamide in reducing postoperative pain after laparoscopic cholecystectomy. Methods: This clinical trial was performed in 88 patients with cholelithiasis without any complication that were candidate for laparoscopic cholecystectomy. The patients devided randomly and equally in two groups. The experimental group received Acetazolamide (250mg orally 24 hours before surgery every 8 hours) and control group received placebo. Abdominal and shoulder pain measured using Mc Gill pain score by a person who was blind for both groups. Pain measurement was performed in four different times before and after the surgery discharge from recovery and 24 hours after surgery. Data were analyzed by using SPSS software. Results: We observed that mean pain scores was significantly higher in acetazolamide group compared to the placebo group 24 hours after the operation (P0.05). Conclusion: Although acetazolamide can reduce abdominal pain referred to right shoulder by reducing acidity in peritoneal irrigation fluid but this drug can increase abdominal pain in the site of surgery with damaged tissues by producing tissue acidosis (as a side effect of drug)
Evaluation of congenital hypothyroidism screening program in urban and rural health centers in Chaharamahal and Bakhtiari
زمینه و هدف: تشخیص و درمان زودرس کم کاری تیروئید در پیشگیری از عقب ماندگی ذهنی ضروری است. این مطالعه به منظور ارزیابی برنامه غربالگری کم کاری تیروئید نوزادی در استان چهارمحال وبختیاری انجام شده است. روش بررسی: مطالعه حاضر از نوع توصیفی- مقطعی در سال 1388 بر روی 100 نوزاد متولد شده انجام شد. داده ها با کمک چک لیست محقق ساخته مبتنی بر دستورالعمل کشوری در خصوص غربالگری تیروئید جمع آوری و در نرم افزارSPSS تحلیل شد. یافته ها: 23 کارکنان از علایم کم کاری تیروئیدی مادرزادی آگاهی خوب و 73 آگاهی متوسط داشتند و تقریباً 79 فعالیت های نمونه گیری در مراکز خیلی خوب انجام می شد. نتیجه گیری: با توجه به یافته های حاصل در 80 مراکز وضعیت خیلی خوب بود. آموزش و نظارت مستمر بر کارکنان ، ارسال دستورالعمل و کتابچه به مراکزی که در این زمینه دچار کمبود هستند، توصیه می گردد
Growth and interfacial properties of epitaxial oxides on semiconductors: ab initio insights
Crystalline metal oxides display a large number of physical functionalities such as ferroelectricity, magnetism, superconductivity, and Mott transitions. High quality heterostructures involving metal oxides and workhorse semiconductors such as silicon have the potential to open new directions in electronic device design that harness these degrees of freedom for computation or information storage. This review describes how first-principles theoretical modeling has informed current understanding of the growth mechanisms and resulting interfacial structures of crystalline, coherent, and epitaxial metal oxide thin films on semiconductors. Two overarching themes in this general area are addressed. First, the initial steps of oxide growth involve careful preparation of the semiconductor surface to guard against amorphous oxide formation and to create an ordered template for epitaxy. The methods by which this is achieved are reviewed, and possibilities for improving present processes to enable the epitaxial growth of a wider set of oxides are discussed. Second, once a heterointerface is created, the precise interfacial chemical composition and atomic structure is difficult to determine unambiguously from experiment or theory alone. The current understanding of the structure and properties of complex oxide/semiconductor heterostructures is reviewed, and the main challenges to prediction—namely, (i) are these heterostructures in thermodynamic equilibrium or kinetically trapped, and (ii) how do the interfaces modify or couple to the degrees of freedom in the oxide?—are explored in detail for two metal oxide thin films on silicon. Finally, an outlook of where theoretical efforts in this field may be headed in the near future is provided.National Science Foundation (U.S.). Materials Research Science and Engineering Centers (Program) (Grant DMR-1119826)National Science Foundation (U.S.). (Yale University. Biomedical High Performance Computing Center. Grant CNS 08-21132
Structure-based stabilization of insulin as a therapeutic protein assembly via enhanced aromatic-aromatic interactions
Key contributions to protein structure and stability are provided by weakly polar interactions, which arise from asymmetric electronic distributions within amino acids and peptide bonds. Of particular interest are aromatic side chains whose directional π-systems commonly stabilize protein interiors and interfaces. Here, we consider aromatic-aromatic interactions within a model protein assembly: the dimer interface of insulin. Semi-classical simulations of aromatic-aromatic interactions at this interface suggested that substitution of residue TyrB26 by Trp would preserve native structure while enhancing dimerization (and hence hexamer stability). The crystal structure of a [TrpB26]insulin analog (determined as a T3Rf3 zinc hexamer at a resolution of 2.25 Å) was observed to be essentially identical to that of WT insulin. Remarkably and yet in general accordance with theoretical expectations, spectroscopic studies demonstrated a 150-fold increase in the in vitro lifetime of the variant hexamer, a critical pharmacokinetic parameter influencing design of long-acting formulations. Functional studies in diabetic rats indeed revealed prolonged action following subcutaneous injection. The potency of the TrpB26-modified analog was equal to or greater than an unmodified control. Thus, exploiting a general quantum-chemical feature of protein structure and stability, our results exemplify a mechanism-based approach to the optimization of a therapeutic protein assembly
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