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91.
Fourier transform infrared (FTIR) spectroscopy is a very flexible technique for characterization of protein secondary structure. Measurements can be carried out rapidly in a number of different environments based on only small quantities of proteins. For this technique to become more widely used for protein secondary structure characterization, however, further developments in methods to accurately quantify protein secondary structure are necessary. Here we propose a structural classification of proteins (SCOP) class specialized neural networks architecture combining an adaptive neuro-fuzzy inference system (ANFIS) with SCOP class specialized backpropagation neural networks for improved protein secondary structure prediction. Our study shows that proteins can be accurately classified into two main classes "all alpha proteins" and "all beta proteins" merely based on the amide I band maximum position of their FTIR spectra. ANFIS is employed to perform the classification task to demonstrate the potential of this architecture with moderately complex problems. Based on studies using a reference set of 17 proteins and an evaluation set of 4 proteins, improved predictions were achieved compared to a conventional neural network approach, where structure specialized neural networks are trained based on protein spectra of both "all alpha" and "all beta" proteins. The standard errors of prediction (SEPs) in % structure were improved by 4.05% for helix structure, by 5.91% for sheet structure, by 2.68% for turn structure, and by 2.15% for bend structure. For other structure, an increase of SEP by 2.43% was observed. Those results were confirmed by a "leave-one-out" run with the combined set of 21 FTIR spectra of proteins. 相似文献
92.
Nikos T Kouris Maria D Sifaki Dimitra D Kontogianni Ioannis Zaharos Eleni M Kalkandi Haris E Grassos Dimitris K Babalis 《Cardiovascular ultrasound》2003,1(1):1-6
Background
It has been suggested that an extensive contractile reserve identified recognised by means of dobutamine stress echocardiography may predict a better prognosis in patients with severe left ventricular dysfunction at rest. However, the clinical use of dobutamine stress echocardiography may be limited in patients with chronic heart failure by the substantial proportion of such patients treated with beta-blockers, since the inotropic response to adrenergic stimulation is known to be attenuated in patients receiving beta-adrenoceptor blockers. Enoximone is a positive inotropic agent that inhibits cyclic adenosine monophosphate-specific phosphosdiesterase. We therefore tested the hypothesis that enoximone may be an alternative to dobutamine in evaluating left ventricular contractile reserve in patients with systolic dysfunction on chronic beta-blocker therapy.Methods
We studied 26 patients (21 males and five females) with a mean age of 58 ± 10 years: 11 were not receiving beta-blockers (noBB group); 15 were receiving carvedilol at a mean dose of 34 mg/day (BB group). Dobutamine was infused at doses of 5 and 10 micrograms/kg/min, and enoximone at a dose of 1.5 mg/kg.Results
The ejection fraction in the noBB group increased by 9% with dobutamine and 8.73% with enoximone (p = 0.86); in the BB group, it increased by 6% with dobutamine and 8.94% with enoximone (p = 0.03). Regional peak systolic velocities were evaluated by means of tissue Doppler imaging in four basal and four medium level segments. In the noBB group, they increased more with dobutamine than with enoximone in three of the eight segments; no significant differences were found in the BB group. Dobutamine induced non-sustained ventricular tachycardia in three patients and supraventricular tachycardia in one, whereas enoximone did not induce any repetitive arrhythmias.Conclusions
Enoximone might be preferable to low-dose dobutamine for evaluating left ventricular contractile reserve in chronically beta-blocked heart failure patients as it is slightly more potent and has a better safety profile. 相似文献93.
94.
Hypothalamic neurons that produce the peptide transmitters hypocretins/orexins have attracted much recent attention. They provide direct and predominantly excitatory inputs to all major brain areas except the cerebellum, with the net effect of stimulating wakefulness and arousal. These inputs are essential for generating sustained wakefulness in mammals, and defects in hypocretin signalling result in narcolepsy. In addition, new roles for hypocretins/orexins are emerging in reward-seeking, learning, and memory. Recent studies also indicate that hypocretin/orexin neurons can alter their intrinsic electrical activity according to ambient fluctuations in the levels of nutrients and appetite-regulating hormones. These intriguing electrical responses are perhaps the strongest candidates to date for the elusive neural correlates of after-meal sleepiness and hunger-induced wakefulness. Hypocretin/orexin neurons may thus directly translate rises and falls in body energy levels into different states of consciousness. 相似文献
95.
When expressed either in polarized epithelial cells or in fibroblasts, two Na(+)/H(+) exchanger isoforms, NHE1 and NHE3, have different subcellular distributions. Using a quantitative cell surface biotinylation technique, we found PS120 cells target approximately 90% of mature NHE1 but only 14% of NHE3 to the cell surface, and this pattern occurs irrespective of NHE protein expression levels. In this study, we examined surface fractions of NHE3 C-terminal truncation mutants to identify domains involved in the targeting of NHE3. Removing the C-terminal 76 amino acids doubled surface fractions to 30% of total and doubled the V(max) from 1300 to 2432 microM H(+)/s. Removal of another 66 amino acids increased surface levels to 55% of total with an increase in the V(max) to 5794 microM H(+)/s. Surface fractions did not change with a further 105 amino acid truncation. We postulated that inhibition of the basal recycling of NHE3 could result in the surface accumulation of the NHE3 truncations. Accordingly, we found that, unlike wild-type NHE3, the truncations were shown to internalize poorly and were not affected by PI3 kinase inhibition. However, while the truncations demonstrated reduced basal recycling, they retained the same serum response as full-length NHE3, with a mobilization of approximately 10% of total NHE to the surface. We conclude that basal recycling of NHE3 is controlled by endocytic determinants contained within its C-terminal 142 amino acids and that serum-mediated exocytosis is independently regulated through a different part of the protein. 相似文献
96.
Half-lives of plasma membrane Na+/H+ exchangers NHE1-3: plasma membrane NHE2 has a rapid rate of degradation 总被引:2,自引:0,他引:2
Cavet Megan E.; Akhter Shafinaz; Murtazina Rakhilya; Sanchez de Medina Fermin; Tse Chung-Ming; Donowitz Mark 《American journal of physiology. Cell physiology》2001,281(6):C2039
The Na+/H+ exchangers NHE2 and NHE3 areinvolved in epithelial Na+ and HCO absorption. To increase insights into the functions of NHE2 vs. NHE3,we compared their cellular processing with each other and with thehousekeeping isoform NHE1. Using biotinylated exchanger, we determinedthat the half-life of plasma membrane NHE2 was short (3 h) comparedwith that of NHE1 (24 h) and NHE3 (14 h) in both PS120 fibroblasts andCaco-2 cells. NHE2 transport and plasma membrane levels were reduced by3 h of Brefeldin A treatment, whereas NHE1 was unaffected. NHE2was degraded by the lysosomes but not proteosomes, as demonstrated byincreasing levels of endocytosed NHE2 protein after inhibition of thelysosomes, but not with proteosome inhibition. Unlike that of NHE3,basal NHE2 transport activity was not affected by phosphatidylinositol 3-kinase inhibition and did not appear to be localized in the juxtanuclear recycling endosome. Therefore, for NHE2, protein degradation and/or protein synthesis probably play important roles inits basal and regulated states. These results suggest fundamental differences in the cellular processing and trafficking of NHE2 andNHE3. These differences may underlie the specialized roles that theseexchangers play in epithelial cells. 相似文献
97.
Asmat Maria Wishal Ramzan Muhammad Haris Ramzan Faiqah 《International journal of peptide research and therapeutics》2020,26(3):1259-1267
International Journal of Peptide Research and Therapeutics - Neurokinin B (NKB) is an important endogenous neuropeptide and belongs to largest neuropeptide family tachykinin. NKB is thought to... 相似文献
98.
Mohammad Nazim Uddin Patrice Dunoyer Gregory Schott Salina Akhter Chunlin Shi William J. Lucas Olivier Voinnet Jae-Yean Kim 《Nucleic acids research》2014,42(12):7971-7980
RNA silencing is an evolutionarily conserved mechanism triggered by double-stranded RNA that is processed into 21- to 24-nt small interfering (si)RNA or micro (mi)RNA by RNaseIII-like enzymes called Dicers. Gene regulations by RNA silencing have fundamental implications in a large number of biological processes that include antiviral defense, maintenance of genome integrity and the orchestration of cell fates. Although most generic or core components of the various plant small RNA pathways have been likely identified over the past 15 years, factors involved in RNAi regulation through post-translational modifications are just starting to emerge, mostly through forward genetic studies. A genetic screen designed to identify factors required for RNAi in Arabidopsis identified the serine/threonine protein kinase, TOUSLED (TSL). Mutations in TSL affect exogenous and virus-derived siRNA activity in a manner dependent upon its kinase activity. By contrast, despite their pleiotropic developmental phenotype, tsl mutants show no defect in biogenesis or activity of miRNA or endogenous trans-acting siRNA. These data suggest a possible role for TSL phosphorylation in the specific regulation of exogenous and antiviral RNA silencing in Arabidopsis and identify TSL as an intrinsic regulator of RNA interference. 相似文献
99.
Md. Habban Akhter Sarwar Beg Mohammed Tarique Arshi Malik Sarah Afaq Hani Choudhry Salman Hosawi 《Biochimica et Biophysica Acta (BBA)/General Subjects》2021,1865(2):129777
BackgroundIn past few decades, the research on engineered nanocarriers (NCs) has gained significant attention in cancer therapy due to selective delivery of drug molecules on the diseased cells thereby preventing unwanted uptake into healthy cells to cause toxicity.Scope of reviewThe applicability of enhanced permeability and retention (EPR) effect for the delivery of nanomedicines in cancer therapy has gained limited success due to poor accessibility of the drugs to the target cells where non-specific payload delivery to the off target region lack substantial reward over the conventional therapeutic systems.Major conclusionsIn spite of the fact, nanomedicines fabricated from the biocompatible nanocarriers have reduced targeting potential for meaningful clinical benefits. However, over expression of receptors on the tumor cells provides opportunity to design functional nanomedicine to bind substantially and deliver therapeutics to the cells or tissues of interest by alleviating the bio-toxicity and unwanted effects. This critique will give insight into the over expressed receptor in various tumor and targeting potential of functional nanomedicine as new therapeutic avenues for effective treatment.General significanceThis review shortly shed light on EPR-based drug targeting using nanomedicinal strategies, their limitation, and advances in therapeutic targeting to the tumor cells. 相似文献
100.
Mohammed A. A. Alqumber Naseem Akhter Shafiul Haque Aditya K. Panda Raju K. Mandal 《PloS one》2014,9(4)