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Smirnov S, Andryushkov V, Podivilov E, Sturman B, Breunig I. Soliton based χ (2) combs in high-Q optical microresonators. Opt Express 2021; 29:27434-27449. [PMID: 34615159 DOI: 10.1364/oe.432529] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023]
Abstract
Investigations of the frequency combs in χ(3) microresonators have passed a critical point when the soliton based regimes are well established and realized on different platforms. For χ(2) microresonators, where the first harmonic (FH) and second harmonic (SH) envelopes are coupled via the SH generation and optical parametric oscillation, the comb-soliton studies are just starting. Here we report on a vast accessible dual χ(2) soliton-comb family in high-Q microresonators with the SH and FH combs centered at the pump frequency ωp and its half ωp/2. Vicinity of the point of equal FH and SH group velocities λc, available via proper radial poling, is found to be the most advantageous for the generation of spectrally broad dual FH-SH combs. Our predictions as applied to lithium niobate resonators include the dependence of comb and dissipative soliton parameters on the pump power, the deviation λp - λc, the modal quality factors and frequency detunings, and the necessary parameters of radial poling of the resonator. These predictions form a solid basis for the realization of χ(2) frequency combs.
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2
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Smirnov S, Sturman B, Podivilov E, Breunig I. Walk-off controlled self-starting frequency combs in χ (2) optical microresonators. Opt Express 2020; 28:18006-18017. [PMID: 32680002 DOI: 10.1364/oe.395360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 05/22/2020] [Indexed: 06/11/2023]
Abstract
Investigations of frequency combs in χ(3) optical microresonators are burgeoning nowadays. Changeover to χ(2) resonators promises further advances and brings new challenges. Here, the comb generation entails not only coupled first and second harmonics (FHs and SHs) and two dispersion coefficients but also a substantial difference in the group velocities - the temporal walk-off. We predict walk-off controlled highly stable comb generation, which is drastically different from that known in the χ(3) case. This includes the general notion of antiperiodic states; formation of localized coherent antiperiodic steady states (solitons), where the FH and SH envelopes move with a common velocity without shape changes; characterization of a new vast family of antiperiodic solitons; and the dependence of comb spectra on the pump power and the group velocity difference.
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Karpov A, Anikin N, Cherepanov D, Mihailova A, Krasnova M, Smirnov S, Mihailov E, Chefu S, Ivkin D, Moiseeva O, Galagudza M. 3311A new rat model of chronic thromboembolic pulmonary hypertension induced by repeated intravenous administration of biodegradable alginate microspheres. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz745.0075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Introduction
Chronic thromboembolic pulmonary hypertension (CTEPH) is life-threatening complication of pulmonary embolism (PE) with insufficiently understood mechanisms. Several rodent CTEPH models based on i.v. administration of non-biodegradable microparticles have been validated for preclinical studies. Major limitation of these models is the lack of partial dissolution of emboli following their entrapment in the lung vasculature.
Purpose
The study was aimed at development and validation of rat CTEPH model based on recurrent embolization of (sub)segmental pulmonary artery branches with biodegradable microspheres.
Methods
Male Wistar rats were used for the experiments. Pulmonary vasculature was embolized either with sodium alginate microspheres (MS) or with autologous blood clots (AT). The animals were randomized into the following groups: i) controls: saline at a volume of 50 μL was injected 4 times with 8-day interval into the tail vein; the same regimen was used in two next groups; ii) AT; iii) MS4; iv) MS8: MS were administered 8 times with 4-day interval. Histological examination of the lungs was performed after 2 and 6 weeks after the last injection. 6 weeks after the last injection the following analyses were performed: treadmill test, transthoracic echocardiography (TTE), right ventricular catheterization with measurement of right ventricular systolic pressure (RVSP), determination of serum endothelin-1 level.
Results
The survival rate in the MS8 group was 50%. In the other groups, there were no animal deaths. Multiple emboli were found in the lumen of (sub)segmental pulmonary artery branches 2 weeks after the last injection in MS4 and MS8 groups. Increased diameter and thickening of the bronchial arterial wall were also registered. After 6 weeks, the index of hypertrophy of vessel wall in MS4 and MS8 groups was significantly higher than in controls (p=0.041 and p=0.006, respectively) (Fig. 1). No sign of vascular remodeling was identified in the branches of the pulmonary artery in the AT group. Exercise tolerance was significantly reduced in both MS4 and MS8 groups compared with the controls (p=0.025 and p=0.008, respectively). There were no significant differences in exercise tolerance between the AT and control groups. TTE data indicate a significant increase in the diameter of the pulmonary trunk and the right ventricular outflow tract in the MS8 group compared with controls and AT (p<0.05). Significant increase in RVSP as well as in endothelin-1 level versus controls was found only in the MS8 group.
Figure 1. Histological changes in the branches of the pulmonary artery 6 weeks after the last injection of emboli.
Conclusion
Recurrent (×8) intravenous administration of MS in rats resulted in CTEPH development characterized by specific lung vasculature remodelling, reduced exercise tolerance, and persistent rise in RVSP. The model developed can be used for preclinical testing of promising drug candidates.
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Affiliation(s)
- A Karpov
- Federal Almazov Medical Research Centre, Saint Petersburg, Russian Federation
| | - N Anikin
- Saint Petersburg Pavlov State Medical University, Saint Petersburg, Russian Federation
| | - D Cherepanov
- Federal Almazov Medical Research Centre, Saint Petersburg, Russian Federation
| | - A Mihailova
- Saint Petersburg Pavlov State Medical University, Saint Petersburg, Russian Federation
| | - M Krasnova
- Saint Petersburg State Chemical Pharmaceutical University, Saint Petersburg, Russian Federation
| | - S Smirnov
- Saint Petersburg Pavlov State Medical University, Saint Petersburg, Russian Federation
| | - E Mihailov
- Saint Petersburg Pavlov State Medical University, Saint Petersburg, Russian Federation
| | - S Chefu
- Saint Petersburg Pavlov State Medical University, Saint Petersburg, Russian Federation
| | - D Ivkin
- Saint Petersburg State Chemical Pharmaceutical University, Saint Petersburg, Russian Federation
| | - O Moiseeva
- Federal Almazov Medical Research Centre, Saint Petersburg, Russian Federation
| | - M Galagudza
- Federal Almazov Medical Research Centre, Saint Petersburg, Russian Federation
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Mirzebasov M, Smirnov A, Smirnov S. [THE CELLULAR COMPOSITION OF THE EPITHELIUM OF THE VILLUS OF THE MUCOUS MEMBRANE OF THE DUODENUM OF RATS IN THE CONDITIONS OF EPICHLOROHYDRIN AND DRUG INFLUENCE]. Georgian Med News 2019:111-116. [PMID: 30829601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Purpose of the research is to study the nature of the disorders of the villi of the duodenal mucous membrane (MM) in conditions of long-acting ECH as well as to substantiate experimentally the effectiveness of the use of the extract of Echinacea purpurea (EP) and thiotriazoline for the purpose of these disorders correction. The withdrawal of the rats from the experiment was carried out on the 1st, 7th, 15th, 30th and 60th day after the completion of the administration of ECH, EP extract and thiotriazoline. Histological processing of duodenum fragments was performed according to the standard method. The cell composition of the villus epithelium of duodenal MM was evaluated using a laboratory microscope of the MC 100 (Micros, Austria) and the Microvisible software (version 1.11.10). The determination of the significance of differences was carried out according to the Mann-Whitney U criterion. Differences were considered significant at p<0.05. Prolonged action of ECH led to a decrease in the number of cells in one villus of duodenal MM. This decrease persisted after the end of the administration of this chemical. There was a decrease in the number of columnar epithelial cells, goblet exocrinocytes and argyrophil endocrinocytes. In rats that did not receive ECH, administration of an EP extract was accompanied by a short-term increase in the number of columnar epithelial cells in one villus of duodenal MM. The administration of thiotriazolin to rats that did not receive ECH caused a short-term increase in the number of cells in one villus of duodenal MM and the number of columnar epithelial cells in the one villus of duodenal MM. The use of EP extract on the background of inhalations of ECH reduced the degree of decrease in the number of cells in one villus of duodenal MM and the number of columnar epitheliocytes in one villus of duodenal MM, reduced the degree and duration of reduction in the number of goblet exocrinocytes in one villus of duodenal MM, reduced the duration of reduction in the number of argyrophil endocrinocytes in one villus of duodenal MM. The use of thiotriazolin during the administration of ECH led to a decrease in the degree and duration of a decrease in the number of cells in one villus of duodenal MM and the number of columnar epithelial cells in one villus of duodenal MM, and also prevented the occurrence of a decrease in the number of goblet exocrinocytes and argyrophil endocrinocytes in one villus of duodenal MM.
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Affiliation(s)
- M Mirzebasov
- State Establishment "Lugansk State Medical University", Ukraine
| | - A Smirnov
- State Establishment "Lugansk State Medical University", Ukraine
| | - S Smirnov
- State Establishment "Lugansk State Medical University", Ukraine
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Demchenko P, Gomon D, Anoshkin I, Smirnov S, Lioubtchenko D, Khodzitsky M. Study of influence of densification on control of conductivity and spectral characteristics of thin films of carbon nanotubes in terahertz frequency range. EPJ Web Conf 2018. [DOI: 10.1051/epjconf/201819506022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Shan YP, Tiwari PB, Krishnakumar P, Vlassiouk I, Li W, Wang X, Darici Y, Lindsay S, Wang HD, Smirnov S, He J. Surface modification of graphene nanopores for protein translocation. Nanotechnology 2013; 24:495102. [PMID: 24231385 PMCID: PMC3925770 DOI: 10.1088/0957-4484/24/49/495102] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Studies of DNA translocation through graphene nanopores have revealed their potential for DNA sequencing. Here we report a study of protein translocation through chemically modified graphene nanopores. A transmission electron microscope (TEM) was used to cut nanopores with diameters between 5 and 20 nm in multilayer graphene prepared by chemical vapor deposition (CVD). After oxygen plasma treatment, the dependence of the measured ionic current on salt concentration and pH was consistent with a small surface charge induced by the formation of carboxyl groups. While translocation of gold nanoparticles (10 nm) was readily detected through such treated pores of a larger diameter, translocation of the protein ferritin was not observed either for oxygen plasma treated pores, or for pores modified with mercaptohexadecanoic acid. Ferritin translocation events were reliably observed after the pores were modified with the phospholipid-PEG (DPPE-PEG750) amphiphile. The ion current signature of translocation events was complex, suggesting that a series of interactions between the protein and pores occurs during the process.
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Affiliation(s)
- Y. P. Shan
- Department of Physics, Florida International University, Miami, FL 33199, USA
| | - P. B. Tiwari
- Department of Physics, Florida International University, Miami, FL 33199, USA
| | - P. Krishnakumar
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA
| | - I. Vlassiouk
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - W.Z. Li
- Department of Physics, Florida International University, Miami, FL 33199, USA
| | - X.W. Wang
- Department of Physics, Florida International University, Miami, FL 33199, USA
| | - Y. Darici
- Department of Physics, Florida International University, Miami, FL 33199, USA
| | - S.M. Lindsay
- Department of Physics, Arizona State University, Tempe, AZ 85287, USA
- Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA
| | - H. D. Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R. China
| | - S. Smirnov
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA
- Corresponding Author: Sergei, Smirnov, ; He, Jin,
| | - J. He
- Department of Physics, Florida International University, Miami, FL 33199, USA
- Corresponding Author: Sergei, Smirnov, ; He, Jin,
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Benson N, Cucurull-Sanchez L, Demin O, Smirnov S, van der Graaf P. Reducing systems biology to practice in pharmaceutical company research; selected case studies. Adv Exp Med Biol 2012; 736:607-15. [PMID: 22161355 DOI: 10.1007/978-1-4419-7210-1_36] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Reviews of the productivity of the pharmaceutical industry have concluded that the current business model is unsustainable. Various remedies for this have been proposed, however, arguably these do not directly address the fundamental issue; namely, that it is the knowledge required to enable good decisions in the process of delivering a drug that is largely absent; in turn, this leads to a disconnect between our intuition of what the right drug target is and the reality of pharmacological intervention in a system such as a human disease state. As this system is highly complex, modelling will be required to elucidate emergent properties together with the data necessary to construct such models. Currently, however, both the models and data available are limited. The ultimate solution to the problem of pharmaceutical productivity may be the virtual human, however, it is likely to be many years, if at all, before this goal is realised. The current challenge is, therefore, whether systems modelling can contribute to improving productivity in the pharmaceutical industry in the interim and help to guide the optimal route to the virtual human. In this context, this chapter discusses the emergence of systems pharmacology in drug discovery from the interface of pharmacokinetic-pharmacodynamic modelling and systems biology. Examples of applications to the identification of optimal drug targets in given pathways, selecting drug modalities and defining biomarkers are discussed, together with future directions.
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Affiliation(s)
- N Benson
- Modelling and simulation, Department of Pharmacokinetics, Dynamics and Metabolism, Pfizer Worldwide Research, Pfizer Ltd., Sandwich CT13 9NJ, UK.
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Abstract
In this paper we have developed a model of antimicrobial effect of gramicidin S. This model has allowed us to predict the dependence of antimicrobial effect of the drug applied as oral melting tablets on dosage, time of resorption and minimal inhibitory concentration (MIC) of the drug characterizing its ability to kill different bacteria. The model has been employed to optimize dosing regime of gramicidin S containing drug Grammidin. Efficacy of the drug has been studied for the diverse gram-positive and gram-negative bacteria with different MIC. The number of bacteria located in the oral cavity and killed by one-pass administration of the drug (resolution of one tablet) has been calculated under condition of various dosing regimes. Based on the simulation results it has been found that (1) twofold prolongation of prescribed resorption time (from 30 to 60min) of the tablet comprising standard dosage of 3mg of gramicidin S results in 1.5-fold increase in efficacy, (2) 1.5-fold decrease in gramicidin S dosage (from 3 to 2mg per administration) under condition of holding prescribed resorption time (30min) does not lead to any considerable decrease in the efficacy of the drug.
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Affiliation(s)
- S Smirnov
- Institute for Systems Biology SPb, Moscow, Russia
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9
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Drobyshev A, Reshetov I, Smirnov S, Shtripova N. P.333 Rehabilitation efficiency increase in patients with maxillar and mandibular defects. J Craniomaxillofac Surg 2006. [DOI: 10.1016/s1010-5182(06)60838-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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10
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Rogozin IB, Babenko VN, Fedorova ND, Jackson JD, Jacobs AR, Krylov DM, Makarova KS, Mazumder R, Mekhedov SL, Mirkin BG, Nikolskaya AN, Rao BS, Smirnov S, Sorokin AV, Sverdlov AV, Vasudevan S, Wolf YI, Yin JJ, Natale DA, Koonin EV. Evolution of eukaryotic gene repertoire and gene structure: discovering the unexpected dynamics of genome evolution. Cold Spring Harb Symp Quant Biol 2003; 68:293-301. [PMID: 15338629 DOI: 10.1101/sqb.2003.68.293] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Affiliation(s)
- I B Rogozin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
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Abstract
Estrogen (17beta-estradiol; 17betaE) and xenoestrogens, estrogenic compounds that are not steroid hormones, have non-genomic actions at plasma membrane receptors unrelated to the nuclear estrogen receptor. The open probability (P(o)) of large conductance Ca(2+)/voltage-sensitive k(+)(BK) channels is increased by 17betaE through the regulatory beta1 subunit. The pharmacological nature of the putative membrane binding site is unclear. We probed the site by determining whether tamoxifen ((Z)-1-(p-dimethylaminoethoxy-phenyl)-1,2-diphenyl-1-butene; Tx), a chemotherapeutic xenoestrogen, increased P(o) in clinically relevant concentrations (0.1-10 microm). In whole cell patch clamp recordings on canine colonic myocytes, which express the beta1 subunit, Tx activated charybdotoxin-sensitive K(+) current. In single channel experiments, Tx increased the NP(o) (P(o) x number channels; N) and decreased the unitary conductance (gamma) of BK channels. Tx increased NP(o) (EC(50) = 0.65 microm) in excised membrane patches independent of Ca(2+) changes. The Tx mechanism of action requires the beta1 subunit, as Tx increased the NP(o) of Slo alpha expressed in human embryonic kidney cells only in the presence of the beta1 subunit. Tx decreased gamma of the alpha subunit expressed alone, without effect on NP(o). Our data indicate that Tx increases BK channel activity in therapeutic concentrations and reveal novel pharmacological properties attributable to the alpha and beta1 subunits. These data shed light on BK channel structure and function, non-genomic mechanisms of regulation, and physiologically and therapeutically relevant effects of xenoestrogens.
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Affiliation(s)
- G M Dick
- Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, Nevada 89557, USA.
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12
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Abstract
A new multispectral imaging microscope with micrometer spatial resolution and millisecond temporal resolution has been developed. The imaging microscope is based on the use of an acousto-optic tunable filter (AOTF) for spectral tuning and a progressive scan camera capable of snapshot operation for recording. It can operate in two modes: images are recorded as a function of time or wavelength. When operated as a function of time, the microscope is configured so that as many images as possible are recorded, grabbed, and stored per one wavelength. Upon completion, the AOTF is scanned to a new wavelength, and a new set of images are recorded. Up to 33 images/ second (i.e., 30 ms/image) can be recorded in this mode. In the other configuration, the recording wavelength is rapidly scanned (by means of the AOTF) and only one image is rapidly recorded, grabbed, and stored for each wavelength. Because additional time is needed to scan the AOTF, the maximum number of images can be grabbed in this case is 16 frames/s. Preliminary applications of the imaging microscope include measurements of photoinduced changes of a single unit cell in temperature-sensitive cholesteric liquid crystals as a function of time and wavelength. The changes were found to be varied with time and wavelength. Interestingly, the photoinduced changes of unit cells in the liquid crystal are not the same but different from cell to cell. This imaging microscope is particularly useful for measurements of small-size samples that undergo rapid chemical or biochemical reactions, e.g., activities of a single biological cell.
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Affiliation(s)
- O Khait
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, USA
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Smirnov S, Johnson F, Marumoto R, de los Santos C. Structure of an 11-mer DNA duplex containing the carbocyclic nucleotide analog: 2'-deoxyaristeromycin. J Biomol Struct Dyn 2000; 17:981-91. [PMID: 10949165 DOI: 10.1080/07391102.2000.10506586] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
2'-deoxyaristeromycin (dAr) is a nucleoside analogue that is resistant to the action of DNA glycosylases. High-resolution NMR spectroscopy and molecular dynamics simulations were used to determine the three-dimensional structure of an 11-mer DNA containing a single dAr.T base pair at its center. Analysis of the spectra revealed the existence of a right-handed duplex in solution, stabilized by Watson-Crick hydrogen bonding and base-stacking interactions. The carbocyclic sugar adopted a C1'-exo conformation and sugars of the 3'-flanking base pair had puckers in the O4'-endo range. The dAr.T base pair was mildly propeller twisted, and the dAr analogue showed a positive roll with the 3'-flanking base. Our findings indicate that the observed resistance of dAr-containing oligodeoxynucleotides to the catalytic action of DNA glycosylases relates to its electronic properties rather than structure, and validate the use of dAr and related carbocyclic nucleoside analogues for biological and structure/function relationship studies.
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Affiliation(s)
- S Smirnov
- Department of Pharmacological Sciences, State University of New York at Stony Brook, 11794-8651, USA
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Smirnov S, Paalasmaa P, Uusisaari M, Voipio J, Kaila K. Pharmacological isolation of the synaptic and nonsynaptic components of the GABA-mediated biphasic response in rat CA1 hippocampal pyramidal cells. J Neurosci 1999; 19:9252-60. [PMID: 10531429 PMCID: PMC6782920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
High-frequency stimulation (HFS) applied to stratum radiatum of a rat hippocampal slice in the presence of ionotropic glutamate receptor antagonists evokes a biphasic GABA(A) receptor-dependent response in CA1 pyramidal neurons, with a brief hyperpolarizing IPSP (hIPSP) followed by a long-lasting depolarization. We show now that it is possible to pharmacologically separate the hIPSP and late depolarization from one another. In neurons intracellularly perfused for 1-2 hr with F(-) as the major anion and no ATP, the hIPSP (and the corresponding current, hIPSC) evoked by HFS was blocked, whereas neither the late depolarization nor its underlying current was attenuated. In contrast, internal perfusion with a high concentration (5 mM) of the impermeant lidocaine derivative QX-314 selectively abolished the depolarizing component of the biphasic response and also strongly reduced depolarizations evoked by extracellular microinjection of K(+). Bath application of quinine (0. 2-0.5 mM) or quinidine (0.1 mM) resulted in a pronounced inhibition of the HFS-induced extracellular K(+) concentration ([K(+)](o)) transient but not of the bicarbonate-dependent alkaline shift in extracellular pH. The attenuation of the [K(+)](o) transient was closely paralleled by a suppression of the HFS-evoked depolarization but not of the hIPSP. Quini(di)ne did not affect depolarizations induced by exogenous K(+) either. These data provide direct pharmacological evidence for the view that the HFS-induced biphasic response of the pyramidal neuron is composed of mechanistically distinct components: a direct GABA(A) receptor-mediated phase, which is followed by a slow, nonsynaptic [K(+)](o)-mediated depolarization. The bicarbonate-dependent, activity-induced [K(+)](o) transient can be blocked by quini(di)ne, whereas its depolarizing action in the pyramidal neuron is inhibited by internal QX-314. The presence of fundamentally distinct components in GABA(A) receptor-mediated actions evoked by HFS calls for further investigations of their functional role(s) in standard experimental maneuvers, such as those used in studies of synaptic plasticity and induction of gamma oscillations.
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Affiliation(s)
- S Smirnov
- Department of Biosciences, Division of Animal Physiology, University of Helsinki, Helsinki FIN-00014, Finland
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15
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Tran CD, Cui Y, Smirnov S. Simultaneous multispectral imaging in the visible and near-infrared region: applications in document authentication and determination of chemical inhomogeneity of copolymers. Anal Chem 1998; 70:4701-8. [PMID: 9844568 DOI: 10.1021/ac980647q] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new multispectral imaging spectrometer capable of simultaneously recording spectral images in the visible and near-infrared has been developed. In this instrument, an acoustooptic tunable filter is used to diffract an unpolarized incident light into two diffracted beams with orthogonal polarization; one of them is detected by a silicon camera for the visible region while the other beam is detected in the near-infrared region (from 1 to 1.7 microns) with a NIR camera. The imaging spectrometer is sensitive, inexpensive, and field deployable because it is based on the recently available InGaAs focal plane arrays camera, which is low cost and can be sensitively operated at room temperature. Preliminary applications of the imaging spectrometer include measurements of the visible and NIR absorption spectra of ink used to print U.S. currency. Such results may help to characterize samples as well as to control and to ensure the quality of the samples during the production processes. More important are the results obtained on ethylene/vinyl acetate copolymers. The NIR spectral images obtained clearly indicate that these copolymers exhibit a high degree of chemical inhomogeneity. Because of the possibility of inhomogeneity, it is very important that the homogeneity of polymers or copolymers be thoroughly understood before the NIR methods, especially those based on NIR spectrometers equipped with a single-element detector, are used for measurements.
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Affiliation(s)
- C D Tran
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, USA
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16
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Kaila K, Lamsa K, Smirnov S, Taira T, Voipio J. Long-lasting GABA-mediated depolarization evoked by high-frequency stimulation in pyramidal neurons of rat hippocampal slice is attributable to a network-driven, bicarbonate-dependent K+ transient. J Neurosci 1997; 17:7662-72. [PMID: 9315888 PMCID: PMC6793904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Biphasic GABAA-mediated postsynaptic responses can be readily evoked in CA1 pyramidal neurons of rat hippocampal slices by high-frequency stimulus (HFS) trains in the presence of ionotropic glutamate receptor antagonists. In the present experiments with sharp microelectrodes, whole-cell techniques, and K+-selective microelectrodes, an HFS train (40 pulses at 100 Hz) applied in stratum radiatum close to the recording site evoked a brief hyperpolarizing IPSP (hIPSP), which turned into a prolonged (2-3 sec) depolarization (GABA-mediated depolarizing postsynaptic potential; GDPSP). The I-V relationships of the postsynaptic currents (hIPSC and GDPSC) had distinct characteristics: the hIPSC and the early GDPSC showed outward rectification, whereas the late GDPSC was reduced with positive voltage steps to zero or beyond (inward rectification), but often no clear reversal was seen. That two distinct currents contribute to the generation of the GDPSP was also evident from the finding that a second HFS train at peak or late GDPSP induced a prompt GABAA-mediated hyperpolarization. The GDPSP/C was dependent on the availability of bicarbonate, but not on interstitial or intrapyramidal carbonic anhydrase activity. The HFS train evoked a rapid GABAA-mediated bicarbonate-dependent increase in the extracellular K+ concentration ([K+]o), and the GDPSP followed the K+ transient in a sub-Nernstian manner. The spatial and pharmacological characteristics of the [K+]o shift indicated that it is generated by a local network of GABAergic interneurons. The brief ascending phase of the GDPSP is linked to a K+-dependent accumulation of intracellular Cl-. Thereafter, a nonsynaptic mechanism, a direct depolarizing effect of the [K+]o shift, is responsible for the most conspicuous characteristics of the GDPSP: its large amplitude and prolonged duration.
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Affiliation(s)
- K Kaila
- Department of Biosciences, Division of Animal Physiology, University of Helsinki, FIN-00014 Helsinki, Finland
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Smirnov S, Shulaev V, Tumer NE. Expression of Pokeweed Antiviral Protein in Transgenic Plants Induces Virus Resistance in Grafted Wild-Type Plants Independently of Salicylic Acid Accumulation and Pathogenesis-Related Protein Synthesis. Plant Physiol 1997; 114:1113-1121. [PMID: 12223762 PMCID: PMC158401 DOI: 10.1104/pp.114.3.1113] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Pokeweed antiviral protein (PAP), a 29-kD protein isolated from Phytolacca americana, inhibits translation by catalytically removing a specific adenine residue from the large rRNA of the 60S subunit of eukaryotic ribosomes. Transgenic tobacco (Nicotiana tabacum) plants expressing PAP or a variant (PAP-v) were shown to be resistant to a broad spectrum of plant viruses. Expression of PAP-v in transgenic plants induces synthesis of pathogenesis-related proteins and a very weak (<2-fold) increase in salicylic acid levels. Using reciprocal grafting experiments, we demonstrate here that transgenic tobacco rootstocks expressing PAP-v induce resistance to tobacco mosaic virus infection in both N. tabacum NN and nn scions. Increased resistance to potato virus X was also observed in N. tabacum nn scions grafted on transgenic rootstocks. PAP expression was not detected in the wild-type scions or rootstocks that showed virus resistance, nor was there any increase in salicylic acid levels or pathogenesis-related protein synthesis. Grafting experiments with transgenic plants expressing an inactive PAP mutant demonstrated that an intact active site of PAP is necessary for induction of virus resistance in wild-type scions. These results indicate that enzymatic activity of PAP is responsible for generating a signal that renders wild-type scions resistant to virus infection in the absence of increased salicylic acid levels and pathogenesis-related protein synthesis.
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Affiliation(s)
- S. Smirnov
- Center for Agricultural Molecular Biology and Department of Plant Pathology, Rutgers University, P.O. Box 231, New Brunswick, New Jersey 08903-0231
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Smirnov S, Sidorov V, Pinkhassik E, HavlicČek J, Stibor I. Complexes of p-t-Butylcalix[4]arene Derivatives with Neutral Molecules: Structures and Stabilities. Supramol Chem 1997. [DOI: 10.1080/10610279708034936] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Amin S, Laryea A, Cosman M, Liu T, Xu R, Dwarakanath S, Mao B, Smirnov S, Harvey RG, Hecht SS, Geacintov NE. Direct Synthesis and Characterization of Site-Specific Deoxyguanosyl and Deoxyadenosyl Adducts Derived from the Binding of Pah Diol Epoxides to Oligonucleotides. Polycycl Aromat Compd 1996. [DOI: 10.1080/10406639608034690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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20
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Pasternack M, Smirnov S, Kaila K. Proton modulation of functionally distinct GABAA receptors in acutely isolated pyramidal neurons of rat hippocampus. Neuropharmacology 1996; 35:1279-88. [PMID: 9014143 DOI: 10.1016/s0028-3908(96)00075-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have studied the effect of extracellular pH (pHo) on the GABAA receptor-mediated chloride conductance in acutely isolated pyramidal neurons from area CA1 of the rat hippocampus under whole-cell voltage clamp in bicarbonate-free solutions. The conductance evoked by saturating or near-saturating concentrations (200-1000 microM) of GABA showed a marked sensitivity to variations of pHo around 7.4. A decrease in pHo between 8.4 and 6.4 increased the GABAA receptor-mediated chloride conductance by about two-fold per pH unit. In contrast, when evoked by a low agonist concentration (1-10 microM) the conductance showed an equally marked decrease upon a decrease in pHo. The half-time for desensitization of the conductance induced by 500 microM GABA was around 900 ms at pHo 6.4 and 7.4, but decreased to 650 ms at pHo 8.4. A fall in pHo decreased the amount of desensitization of the conductance evoked by a 5 s application of 5 microM, but not of 500 microM, GABA. The concentration-response relationship of the GABA-induced conductance showed a local plateau between 50 and 100 microM of GABA, which was particularly evident at high pHo. Assuming two receptor populations with a high and a low affinity for GABA, the effect of H+ on the GABAA receptors could be explained as an increase in the EC50 of the high affinity receptor, and an apparently non-competitive potentiation of both the high and the low affinity receptors. The GABAA receptor-mediated conductance was markedly inhibited by 20-50 microM Zn2+. In addition, Zn2+ reverted the down-modulation by H+ observed at low GABA concentrations to up-modulation. Diazepam (1-10 microM) had only a marginal effect on the GABA-gated conductance. Taken together, the results suggest the coexistence in individual hippocampal neurons of two distinct GABAA receptor populations having differential sensitivities to H+. In the light of the inhibitory action of Zn2+ and the virtual absence of an effect of diazepam it is probable that a significant fraction of the GABAA receptors lack the gamma 2 subunit. The observation that an elevated pH has a strong suppressing effect on the conductance evoked by high concentrations of GABA may at least partly explain why an extracellular alkalosis leads to neuronal hyperexcitability.
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Affiliation(s)
- M Pasternack
- Department of Biosciences, University of Helsinki, Finland.
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21
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Bargholtz C, Fransson K, Batenkov O, Majorov M, Smirnov S, Veshikov A. Gamma ray emission in the 252Cf spontaneous fission process. Phys Rev Lett 1995; 74:3081. [PMID: 10058098 DOI: 10.1103/physrevlett.74.3081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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22
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Laryea A, Cosman M, Lin JM, Liu T, Agarwal R, Smirnov S, Amin S, Harvey RG, Dipple A, Geacintov NE. Direct synthesis and characterization of site-specific adenosyl adducts derived from the binding of a 3,4-dihydroxy-1,2-epoxybenzo[c]phenanthrene stereoisomer to an 11-mer oligodeoxyribonucleotide. Chem Res Toxicol 1995; 8:444-54. [PMID: 7578932 DOI: 10.1021/tx00045a017] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Site-specifically modified oligonucleotides were obtained in milligram quantities by reacting racemic 3t,4r-dihydroxy-1,2t-epoxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene (B[c]PhDE-2, or anti-B[c]PhDE) with the single deoxyadenosine (dA) residue in the oligodeoxynucleotide d(CTCTCACTTCC). Enzyme digestion of the covalently modified oligonucleotides with the exonuclease spleen phosphodiesterase yielded covalently linked B[ca]PhDE-N6-deoxyadenosyl monophosphate (dAMP) adducts. Comparisons of the reverse phase HPLC retention times and CD spectra of these B[c]PhDE-3'-dAMP mononucleotide adducts, with those of standards derived from the reaction of the enantiomers (+)- and (-)-anti-B[c]PhDE with 3'-dAMP, show that two major oligonucleotide adducts (I and II) were obtained upon reacting racemic anti-B[c]PhDE with d(CTCTCACTTCC). In oligonucleotide adduct I, the lesion is a (+)-trans-anti-B[c]PhDE-N6-dA residue, and in oligonucleotide adduct II it is a (-)-trans-anti-B[c]PhDE-N6-dA residue. These assignments were further confirmed using a standard 32P postlabeling assay of B[c]PhDE-3'-dAMP mononucleotide adducts obtained from the digestion of oligonucleotides I and II by spleen phosphodiesterase. The melting points (Tm) of duplexes of modified oligonucleotides I and II and their natural complementary strands are not affected significantly by the presence of the covalently bound benzo[c]phenanthrenyl residues. Opposite stereoselective resistance to enzyme digestion by the exonucleases snake venom phosphodiesterase and spleen phosphodiesterase is exhibited by the stereoisomeric (+)-trans- and (-)-trans-anti-B[c]PhDE-modified oligonucleotide adducts I and II; these results are consistent with the intercalative insertion of the benzo[c]phenanthrenyl residues on the 5'-side of the modified dA residue in adduct I, and its insertion on the 3'-side of the dA residue in adduct II, as observed in the duplexes by high resolution NMR techniques [Cosman et al. (1993) Biochemistry 32, 12488-12497, and Cosman et all, Biochemistry, in press.
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Affiliation(s)
- A Laryea
- Chemistry Department, New York University, New York 10003, USA
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23
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Mao B, Xu J, Li B, Margulis LA, Smirnov S, Ya NQ, Courtney SH, Geacintov NE. Synthesis and characterization of covalent adducts derived from the binding of benzo[a]pyrene diol expoxide to a -GGG- sequence in a deoxyoligonucleotide. Carcinogenesis 1995; 16:357-65. [PMID: 7859369 DOI: 10.1093/carcin/16.2.357] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Direct synthesis and purification procedures are described for the preparation of adducts derived from the covalent binding of 7R,8S-dihydroxy-9S,10R-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene [(+)-anti-BPDE or (+)-BPDE 2] to each of the three guanine residues (trans-N2-dG lesions) in the oligodeoxyribonucleotide d(CTATG1G2G3TATC). The positions of the modified Gs are defined by Maxam-Gilbert sequencing techniques. Six different oligonucleotides with one or two precisely positioned (+)-anti-BPDE residues are identified. The absorbance, circular dichroism and fluorescence characteristics are changed upon formation of duplexes with the complementary strands d(GATACCCATAG). In the doubly-modified oligonucleotides, a broad, excimer-like long wavelength fluorescence emission band is observed with a maximum near 455 nm only if the two (+)-anti-BPDE-modified Gs are adjacent to one another. The covalently attached (+)-anti-BPDE residues decrease the thermodynamic stabilities of the duplexes; their melting points are markedly dependent on the position of the lesions, being highest with the (+)-anti-BPDE residue at G1 (Tm = 40 degrees C, only 2 degrees C lower than in the case of the unmodified oligonucleotide) and lowest when it is situated at G3 (Tm = 29 degrees C). The implications of these and other physical characteristics are discussed. The facile synthesis of these or similar site-specific and stereochemically defined (+)-trans-anti-BPDE-N2-dG lesions in runs of contiguous guanines in oligodeoxyribonucleotides of specified base sequence should be useful for the design of site-directed mutagenesis studies in vitro and in vivo.
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MESH Headings
- 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/chemistry
- 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/isolation & purification
- 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide/metabolism
- Base Sequence
- Binding Sites
- Chemical Phenomena
- Chemistry, Physical
- Chromatography, High Pressure Liquid
- DNA/isolation & purification
- DNA/metabolism
- DNA Adducts/chemistry
- DNA Adducts/isolation & purification
- DNA Adducts/metabolism
- Electrophoresis
- Molecular Sequence Data
- Oligonucleotides/isolation & purification
- Oligonucleotides/metabolism
- Spectrometry, Fluorescence
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Affiliation(s)
- B Mao
- Chemistry Department, New York University, NY 10003
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Abstract
Recent work suggests that activity-induced alkaline transients within the interstitial space of nervous tissue are largely due to net fluxes of acid-base equivalents across postsynaptic receptor-gated ion channels. In view of the marked pH sensitivity of certain receptor channels, it has been frequently postulated that synaptically-evoked H+ shifts might play a neuromodulatory role. We provide here the first evidence to support the above hypothesis in showing that extracellularly recorded glutamatergic responses in area CA1 of rat hippocampal slices are potentiated upon inhibition of fast extracellular H+ buffering by a poorly-permeant carbonic anhydrase inhibitor, benzolamide (10 microM). Experiments with glutamate receptor antagonists and Mg(2+)-free solutions suggest that the action of benzolamide is mediated by the H+ sensitivity of N-methyl-D-aspartate (NMDA) receptor channels. In further agreement with an intrinsic neuromodulatory role for H+ in excitatory transmission, addition of the H+ buffer HEPES (20 mM) produced a selective attenuation of pharmacologically-isolated NMDA receptor-mediated responses.
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Affiliation(s)
- T Taira
- Department of Zoology, University of Helsinki, Finland
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