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Tilburn J, Sarkar S, Widdick DA, Espeso EA, Orejas M, Mungroo J, Peñalva MA, Arst HN. The Aspergillus PacC zinc finger transcription factor mediates regulation of both acid- and alkaline-expressed genes by ambient pH. EMBO J 1995; 14:779-90. [PMID: 7882981 PMCID: PMC398143 DOI: 10.1002/j.1460-2075.1995.tb07056.x] [Citation(s) in RCA: 420] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The pH regulation of gene expression in Aspergillus nidulans is mediated by pacC, whose 678 residue-derived protein contains three putative Cys2His2 zinc fingers. Ten pacCc mutations mimicking growth at alkaline pH remove between 100 and 214 C-terminal residues, including a highly acidic region containing an acidic glutamine repeat. Nine pacC+/- mutations mimicking acidic growth conditions remove between 299 and 505 C-terminal residues. Deletion of the entire pacC coding region mimics acidity but leads additionally to poor growth and conidiation. A PacC fusion protein binds DNA with the core consensus GCCARG. At alkaline ambient pH, PacC activates transcription of alkaline-expressed genes (including pacC itself) and represses transcription of acid-expressed genes. pacCc mutations obviate the need for pH signal transduction.
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Sarkar S, Aziz Q, Woolf CJ, Hobson AR, Thompson DG. Contribution of central sensitisation to the development of non-cardiac chest pain. Lancet 2000; 356:1154-9. [PMID: 11030295 DOI: 10.1016/s0140-6736(00)02758-6] [Citation(s) in RCA: 267] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Non-cardiac chest pain mimics angina pectoris but generally originates from the oesophagus. Visceral hypersensitivity may contribute, but its neurophysiological basis is unclear. We investigated whether central sensitisation, an activity-dependent amplification of sensory transfer in the central nervous system, underlies visceral pain hypersensitivity and non-cardiac chest pain. METHODS We studied 19 healthy volunteers and seven patients with non-cardiac chest pain. Acid was infused into the lower oesophagus. Sensory responses to electrical stimulation were monitored within the acid-exposed lower oesophagus, the non-exposed upper oesophagus, and the cutaneous area of pain referral, before and after the infusion. FINDINGS In healthy volunteers, acid infusion into the lower oesophagus lowered the pain threshold in the upper oesophagus (mean decrease 18.2% [95% CI 10.4 to 26.0]; p=0.01) and on the chest wall (24.5% [10.2 to 38.7]; p=0.01). Patients with non-cardiac chest pain had a lower resting oesophageal pain threshold than healthy controls (45 [30 to 58] vs 64 [49 to 81] mA; p=0.04). In response to acid infusion, their pain threshold in the upper oesophagus fell further and for longer (mean fall in area under threshold/time curve 26.7 [11.0 to 42.3] vs 5.8 [2.8 to 8.8] units; p=0.04). INTERPRETATION The finding of secondary viscerovisceral and viscerosomatic pain hypersensitivity suggests that central sensitisation may contribute to visceral pain disorders. The prolonged visceral pain hypersensitivity in patients with non-cardiac chest pain suggests a central enhancement of sensory transfer. New therapeutic opportunities are therefore possible.
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Camarero S, Sarkar S, Ruiz-Dueñas FJ, Martínez MJ, Martínez AT. Description of a versatile peroxidase involved in the natural degradation of lignin that has both manganese peroxidase and lignin peroxidase substrate interaction sites. J Biol Chem 1999; 274:10324-30. [PMID: 10187820 DOI: 10.1074/jbc.274.15.10324] [Citation(s) in RCA: 227] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two major peroxidases are secreted by the fungus Pleurotus eryngii in lignocellulose cultures. One is similar to Phanerochaete chrysosporium manganese-dependent peroxidase. The second protein (PS1), although catalyzing the oxidation of Mn2+ to Mn3+ by H2O2, differs from the above enzymes by its manganese-independent activity enabling it to oxidize substituted phenols and synthetic dyes, as well as the lignin peroxidase (LiP) substrate veratryl alcohol. This is by a mechanism similar to that reported for LiP, as evidenced by p-dimethoxybenzene oxidation yielding benzoquinone. The apparent kinetic constants showed high activity on Mn2+, but methoxyhydroquinone was the natural substrate with the highest enzyme affinity (this and other phenolic substrates are not efficiently oxidized by the P. chrysosporium peroxidases). A three-dimensional model was built using crystal models from four fungal peroxidase as templates. The model suggests high structural affinity of this versatile peroxidase with LiP but shows a putative Mn2+ binding site near the internal heme propionate, involving Glu36, Glu40, and Asp181. A specific substrate interaction site for Mn2+ is supported by kinetic data showing noncompetitive inhibition with other peroxidase substrates. Moreover, residues reported as involved in LiP interaction with veratryl alcohol and other aromatic substrates are present in peroxidase PS1 such as His82 at the heme-channel opening, which is remarkably similar to that of P. chrysosporium LiP, and Trp170 at the protein surface. These residues could be involved in two different hypothetical long range electron transfer pathways from substrate (His82-Ala83-Asn84-His47-heme and Trp170-Leu171-heme) similar to those postulated for LiP.
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Day GL, Blot WJ, Shore RE, McLaughlin JK, Austin DF, Greenberg RS, Liff JM, Preston-Martin S, Sarkar S, Schoenberg JB. Second cancers following oral and pharyngeal cancers: role of tobacco and alcohol. J Natl Cancer Inst 1994; 86:131-7. [PMID: 8271296 DOI: 10.1093/jnci/86.2.131] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND The exceptionally high rate of second primary cancers among patients with oral and pharyngeal cancers is well recognized, yet there has been limited epidemiologic study of risk factors for second tumors. PURPOSE To evaluate the relation of smoking and alcohol consumption to the development of second cancers among this high-risk patient group, we conducted a nested case-control study. METHODS A total of 1090 patients enrolled in a 1984-1985 population-based, case-control study of oral cancer in four areas of the United States were followed through June 1989 for the occurrence of second primary cancers. Information on tobacco and alcohol consumption was obtained from the original interviews and was updated by follow-up interviews obtained for 80 case patients with second cancers and 189 sex-, study area-, and survival-matched cancer patients free of second cancers (control subjects). RESULTS Tobacco smoking and alcohol drinking each contributed to risk of second cancers, with the effects of smoking more pronounced than those of alcohol. The odds ratios (ORs) for smoking (adjusted for alcohol) rose with duration and intensity of smoking and were strongest for tumors of the aerodigestive tract (oral cavity, pharynx, esophagus, larynx, and lungs), with ORs reaching 4.7 (95% confidence interval [CI] = 1.4-16) among smokers of 40 or more cigarettes per day for 20 or more years. Current smokers as of the baseline survey experienced a fourfold increased risk of a second aerodigestive tract cancer relative to nonsmokers and former smokers. No reduction in risk was associated with cessation of smoking or drinking at or after the index diagnosis, although the short median interval (27 months) between tumor diagnoses limited observation of the effects due to recent cessation. Risk was significantly reduced, however, 5 years after smoking cessation. Among drinkers, second cancer risk was greatest for beer intake, with an OR for a second aerodigestive tract cancer of 3.8 (95% CI = 1.2-12) for 15 or more beers per week. CONCLUSIONS Oral and pharyngeal cancer patients with the highest intakes of tobacco and alcohol are the ones most prone to develop second primary cancers. IMPLICATIONS Avoidance of tobacco smoking and alcohol drinking is the most desirable way not only to prevent primary oral cancers, but also to reduce risk of second cancers of the aerodigestive system.
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Bjarnason NH, Sarkar S, Duong T, Mitlak B, Delmas PD, Christiansen C. Six and twelve month changes in bone turnover are related to reduction in vertebral fracture risk during 3 years of raloxifene treatment in postmenopausal osteoporosis. Osteoporos Int 2001; 12:922-30. [PMID: 11808544 DOI: 10.1007/s001980170020] [Citation(s) in RCA: 187] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We studied the relationship between change in bone turnover and vertebral fracture risk during raloxifene therapy using 3-year data from the MORE trial, where 2622 of the 7705 randomized women had measurement of bone markers at baseline and after 6 and 12 months participation. Change in bone turnover was significantly related to future risk of vertebral fracture, also after adjusting for baseline vertebral fracture status and BMD. Thus, for a decrease of 9.3 pg/l in serum osteocalcin after 1 year's raloxifene therapy, the odds ratio (OR) for a new vertebral fracture during 3 years was 0.69 (0.54-0.88), p = 0.003. Similarly, for a decrease of 5.91 microg/l in serum bone alkaline phosphatase, OR was 0.75 (0.62-0.92), p = 0.005. The change in BMD over 12 and 24 months was not related to fracture risk in any of the analyses. The strongest predictor for vertebral fracture was prevalent vertebral fracture--even during therapy. The predictive value of baseline BMD was in the same order of magnitude as bone turnover change during raloxifene treatment. In conclusion, the change in bone turnover is related to fracture risk during raloxifene therapy. In contrast the change in BMD is not related to fracture risk. The strongest predictor for vertebral fracture is prevalent vertebral fracture.
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Sarkar S, Salacinski HJ, Hamilton G, Seifalian AM. The mechanical properties of infrainguinal vascular bypass grafts: their role in influencing patency. Eur J Vasc Endovasc Surg 2006; 31:627-36. [PMID: 16513376 DOI: 10.1016/j.ejvs.2006.01.006] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Accepted: 01/08/2006] [Indexed: 11/18/2022]
Abstract
When autologous vein is unavailable, prosthetic graft materials, particularly expanded polytetrafluoroethylene are used for peripheral arterial revascularisation. Poor long term patency of prosthetic materials is due to distal anastomotic intimal hyperplasia. Intimal hyperplasia is directly linked to shear stress abnormalities at the vessel wall. Compliance and calibre mismatch between native vessel and graft, as well as anastomotic line stress concentration contribute towards unnatural wall shear stress. High porosity reduces graft compliance by causing fibrovascular infiltration, whereas low porosity discourages the development of an endothelial lining and hence effective antithrombogenicity. Therefore, consideration of mechanical properties is necessary in graft development. Current research into synthetic vascular grafts concentrates on simulating the mechanical properties of native arteries and tissue engineering aims to construct a new biological arterial conduit.
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Review |
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186 |
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Yaffe K, Krueger K, Sarkar S, Grady D, Barrett-Connor E, Cox DA, Nickelsen T. Cognitive function in postmenopausal women treated with raloxifene. N Engl J Med 2001; 344:1207-13. [PMID: 11309635 DOI: 10.1056/nejm200104193441604] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND In postmenopausal women, estrogen may have a beneficial effect on cognition or reduce the risk of decline in cognitive function. Whether raloxifene, a selective estrogen-receptor modulator, might have similar actions is not known. METHODS As part of the Multiple Outcomes of Raloxifene Evaluation trial, we studied 7478 postmenopausal women with osteoporosis (mean age, 66 years), who were enrolled at 178 sites in 25 countries. The women were randomly assigned to receive raloxifene (60 mg or 120 mg) or placebo daily for three years. We compared the mean scores of the groups on six tests of cognitive function, which were administered at base line and at six months and one, two, and three years. Women were classified as having a decline in cognitive function if the change in their scores at three years was in the worst 10 percent. RESULTS The mean cognitive scores in the three groups of women were similar at base line. The scores improved slightly in all three groups during the three-year study period, with no significant differences among the groups. The risk of decline in the cognitive function, as measured by four of the six tests, did not differ significantly between the two raloxifene groups combined and the placebo group, but there was a trend toward less decline in the combined raloxifene group on the two tests of verbal memory (relative risk, 0.77) and attention, (relative risk, 0.87). Newly reported or worsening hot flashes did not negatively influence test scores or the effect of treatment on test performance. CONCLUSIONS Raloxifene treatment for three years does not affect overall cognitive scores in postmenopausal women with osteoporosis.
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Clinical Trial |
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Aartsen MG, Abbasi R, Abdou Y, Ackermann M, Adams J, Aguilar JA, Ahlers M, Altmann D, Auffenberg J, Bai X, Baker M, Barwick SW, Baum V, Bay R, Beatty JJ, Bechet S, Becker Tjus J, Becker KH, Benabderrahmane ML, BenZvi S, Berghaus P, Berley D, Bernardini E, Bernhard A, Bertrand D, Besson DZ, Binder G, Bindig D, Bissok M, Blaufuss E, Blumenthal J, Boersma DJ, Bohaichuk S, Bohm C, Bose D, Böser S, Botner O, Brayeur L, Bretz HP, Brown AM, Bruijn R, Brunner J, Carson M, Casey J, Casier M, Chirkin D, Christov A, Christy B, Clark K, Clevermann F, Coenders S, Cohen S, Cowen DF, Cruz Silva AH, Danninger M, Daughhetee J, Davis JC, Day M, De Clercq C, De Ridder S, Desiati P, de Vries KD, de With M, DeYoung T, Díaz-Vélez JC, Dunkman M, Eagan R, Eberhardt B, Eichmann B, Eisch J, Ellsworth RW, Euler S, Evenson PA, Fadiran O, Fazely AR, Fedynitch A, Feintzeig J, Feusels T, Filimonov K, Finley C, Fischer-Wasels T, Flis S, Franckowiak A, Frantzen K, Fuchs T, Gaisser TK, Gallagher J, Gerhardt L, Gladstone L, Glüsenkamp T, Goldschmidt A, Golup G, Gonzalez JG, Goodman JA, Góra D, Grandmont DT, Grant D, Groß A, Ha C, Haj Ismail A, et alAartsen MG, Abbasi R, Abdou Y, Ackermann M, Adams J, Aguilar JA, Ahlers M, Altmann D, Auffenberg J, Bai X, Baker M, Barwick SW, Baum V, Bay R, Beatty JJ, Bechet S, Becker Tjus J, Becker KH, Benabderrahmane ML, BenZvi S, Berghaus P, Berley D, Bernardini E, Bernhard A, Bertrand D, Besson DZ, Binder G, Bindig D, Bissok M, Blaufuss E, Blumenthal J, Boersma DJ, Bohaichuk S, Bohm C, Bose D, Böser S, Botner O, Brayeur L, Bretz HP, Brown AM, Bruijn R, Brunner J, Carson M, Casey J, Casier M, Chirkin D, Christov A, Christy B, Clark K, Clevermann F, Coenders S, Cohen S, Cowen DF, Cruz Silva AH, Danninger M, Daughhetee J, Davis JC, Day M, De Clercq C, De Ridder S, Desiati P, de Vries KD, de With M, DeYoung T, Díaz-Vélez JC, Dunkman M, Eagan R, Eberhardt B, Eichmann B, Eisch J, Ellsworth RW, Euler S, Evenson PA, Fadiran O, Fazely AR, Fedynitch A, Feintzeig J, Feusels T, Filimonov K, Finley C, Fischer-Wasels T, Flis S, Franckowiak A, Frantzen K, Fuchs T, Gaisser TK, Gallagher J, Gerhardt L, Gladstone L, Glüsenkamp T, Goldschmidt A, Golup G, Gonzalez JG, Goodman JA, Góra D, Grandmont DT, Grant D, Groß A, Ha C, Haj Ismail A, Hallen P, Hallgren A, Halzen F, Hanson K, Heereman D, Heinen D, Helbing K, Hellauer R, Hickford S, Hill GC, Hoffman KD, Hoffmann R, Homeier A, Hoshina K, Huelsnitz W, Hulth PO, Hultqvist K, Hussain S, Ishihara A, Jacobi E, Jacobsen J, Jagielski K, Japaridze GS, Jero K, Jlelati O, Kaminsky B, Kappes A, Karg T, Karle A, Kelley JL, Kiryluk J, Kläs J, Klein SR, Köhne JH, Kohnen G, Kolanoski H, Köpke L, Kopper C, Kopper S, Koskinen DJ, Kowalski M, Krasberg M, Krings K, Kroll G, Kunnen J, Kurahashi N, Kuwabara T, Labare M, Landsman H, Larson MJ, Lesiak-Bzdak M, Leuermann M, Leute J, Lünemann J, Madsen J, Maggi G, Maruyama R, Mase K, Matis HS, McNally F, Meagher K, Merck M, Meures T, Miarecki S, Middell E, Milke N, Miller J, Mohrmann L, Montaruli T, Morse R, Nahnhauer R, Naumann U, Niederhausen H, Nowicki SC, Nygren DR, Obertacke A, Odrowski S, Olivas A, O'Murchadha A, Paul L, Pepper JA, Pérez de los Heros C, Pfendner C, Pieloth D, Pinat E, Posselt J, Price PB, Przybylski GT, Rädel L, Rameez M, Rawlins K, Redl P, Reimann R, Resconi E, Rhode W, Ribordy M, Richman M, Riedel B, Rodrigues JP, Rott C, Ruhe T, Ruzybayev B, Ryckbosch D, Saba SM, Salameh T, Sander HG, Santander M, Sarkar S, Schatto K, Scheriau F, Schmidt T, Schmitz M, Schoenen S, Schöneberg S, Schönwald A, Schukraft A, Schulte L, Schulz O, Seckel D, Sestayo Y, Seunarine S, Shanidze R, Sheremata C, Smith MWE, Soldin D, Spiczak GM, Spiering C, Stamatikos M, Stanev T, Stasik A, Stezelberger T, Stokstad RG, Stößl A, Strahler EA, Ström R, Sullivan GW, Taavola H, Taboada I, Tamburro A, Tepe A, Ter-Antonyan S, Tešić G, Tilav S, Toale PA, Toscano S, Unger E, Usner M, van Eijndhoven N, Van Overloop A, van Santen J, Vehring M, Voge M, Vraeghe M, Walck C, Waldenmaier T, Wallraff M, Weaver C, Wellons M, Wendt C, Westerhoff S, Whitehorn N, Wiebe K, Wiebusch CH, Williams DR, Wissing H, Wolf M, Wood TR, Woschnagg K, Xu DL, Xu XW, Yanez JP, Yodh G, Yoshida S, Zarzhitsky P, Ziemann J, Zierke S, Zoll M. Evidence for high-energy extraterrestrial neutrinos at the IceCube detector. Science 2013; 342:1242856. [PMID: 24264993 DOI: 10.1126/science.1242856] [Show More Authors] [Citation(s) in RCA: 181] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report on results of an all-sky search for high-energy neutrino events interacting within the IceCube neutrino detector conducted between May 2010 and May 2012. The search follows up on the previous detection of two PeV neutrino events, with improved sensitivity and extended energy coverage down to about 30 TeV. Twenty-six additional events were observed, substantially more than expected from atmospheric backgrounds. Combined, both searches reject a purely atmospheric origin for the 28 events at the 4σ level. These 28 events, which include the highest energy neutrinos ever observed, have flavors, directions, and energies inconsistent with those expected from the atmospheric muon and neutrino backgrounds. These properties are, however, consistent with generic predictions for an additional component of extraterrestrial origin.
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Research Support, U.S. Gov't, Non-P.H.S. |
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181 |
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Sarkar S, Sreter FA, Gergely J. Light chains of myosins from white, red, and cardiac muscles. Proc Natl Acad Sci U S A 1971; 68:946-50. [PMID: 4252540 PMCID: PMC389087 DOI: 10.1073/pnas.68.5.946] [Citation(s) in RCA: 169] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Purified preparations of rabbit skeletal white, red, and cardiac muscle myosin (WM, RM, and CM) were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Significant differences in both the molecular weights and number of light chains in these myosins were found. WM has three distinct light-chain components (LC(1W), LC(2W), LC(3W)) having molecular weights of 25,500, 17,400, and 15,100, respectively. No component with a molecular weight around 15,000 is present in RM or CM. RM and CM contain components of identical molecular weights close to 25,000 and 17,000 (LC(1CR) and LC(2CR)) which, however, clearly differ in molecular weight from the corresponding subunits in WM. RM has an additional component (LC(1R)) having a slightly higher molecular weight than LC(1W) and LC(1CR). Thus differences and similarities in many biochemical properties between WM, RM, and CM, which have been described earlier, are also reflected in the light-chain components. The present results support the hypothesis that different sets of genes are active in producing components of myosin that make up different isozymic forms characteristic of each muscle type.
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research-article |
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Orejas M, Espeso EA, Tilburn J, Sarkar S, Arst HN, Peñalva MA. Activation of the Aspergillus PacC transcription factor in response to alkaline ambient pH requires proteolysis of the carboxy-terminal moiety. Genes Dev 1995; 9:1622-32. [PMID: 7628696 DOI: 10.1101/gad.9.13.1622] [Citation(s) in RCA: 161] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Extremes of pH are an occupational hazard for many microorganisms. In addition to efficient pH homeostasis, survival effectively requires a regulatory system tailoring the syntheses of molecules functioning beyond the cell boundaries (permeases, secreted enzymes, and exported metabolites) to the pH of the growth environment. Our previous work established that the zinc finger PacC transcription factor mediates such pH regulation in the fungus Aspergillus nidulans in response to a signal provided by the products of the six pal genes at alkaline ambient pH. In the presence of this signal, PacC becomes functional, activating transcription of genes expressed at alkaline pH and preventing transcription of genes expressed at acidic pH. Here we detect two forms of PacC in extracts, both forming specific retardation complexes with a PacC-binding site. Under acidic growth conditions or in acidity-mimicking pal mutants (defective in ambient pH signal transduction), the full-length form of PacC predominates. Under alkaline growth conditions or in alkalinity-mimicking pacCc mutants (independent of the ambient pH signal), a proteolysed version containing the amino-terminal approximately 40% of the protein predominates. This specifically cleaved shorter version is clearly functional, both as an activator for alkaline-expressed genes and as a repressor for acid-expressed genes, but the full-length form of PacC must be inactive. Thus, PacC proteolysis is an essential and pH-sensitive step in the regulation of gene expression by ambient pH. Carboxy-terminal truncations, resulting in a gain-of-function (pacCc) phenotype, bypass the requirement for the pal signal transduction pathway for conversion of the full-length to the proteolyzed functional form.
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Comparative Study |
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Aartsen MG, Ackermann M, Adams J, Aguilar JA, Ahlers M, Ahrens M, Altmann D, Anderson T, Arguelles C, Arlen TC, Auffenberg J, Bai X, Barwick SW, Baum V, Beatty JJ, Becker Tjus J, Becker KH, BenZvi S, Berghaus P, Berley D, Bernardini E, Bernhard A, Besson DZ, Binder G, Bindig D, Bissok M, Blaufuss E, Blumenthal J, Boersma DJ, Bohm C, Bose D, Böser S, Botner O, Brayeur L, Bretz HP, Brown AM, Casey J, Casier M, Chirkin D, Christov A, Christy B, Clark K, Classen L, Clevermann F, Coenders S, Cowen DF, Cruz Silva AH, Danninger M, Daughhetee J, Davis JC, Day M, de André JPAM, De Clercq C, De Ridder S, Desiati P, de Vries KD, de With M, DeYoung T, Díaz-Vélez JC, Dunkman M, Eagan R, Eberhardt B, Eichmann B, Eisch J, Euler S, Evenson PA, Fadiran O, Fazely AR, Fedynitch A, Feintzeig J, Felde J, Feusels T, Filimonov K, Finley C, Fischer-Wasels T, Flis S, Franckowiak A, Frantzen K, Fuchs T, Gaisser TK, Gallagher J, Gerhardt L, Gier D, Gladstone L, Glüsenkamp T, Goldschmidt A, Golup G, Gonzalez JG, Goodman JA, Góra D, Grandmont DT, Grant D, Gretskov P, Groh JC, Groß A, Ha C, Haack C, Haj Ismail A, Hallen P, Hallgren A, et alAartsen MG, Ackermann M, Adams J, Aguilar JA, Ahlers M, Ahrens M, Altmann D, Anderson T, Arguelles C, Arlen TC, Auffenberg J, Bai X, Barwick SW, Baum V, Beatty JJ, Becker Tjus J, Becker KH, BenZvi S, Berghaus P, Berley D, Bernardini E, Bernhard A, Besson DZ, Binder G, Bindig D, Bissok M, Blaufuss E, Blumenthal J, Boersma DJ, Bohm C, Bose D, Böser S, Botner O, Brayeur L, Bretz HP, Brown AM, Casey J, Casier M, Chirkin D, Christov A, Christy B, Clark K, Classen L, Clevermann F, Coenders S, Cowen DF, Cruz Silva AH, Danninger M, Daughhetee J, Davis JC, Day M, de André JPAM, De Clercq C, De Ridder S, Desiati P, de Vries KD, de With M, DeYoung T, Díaz-Vélez JC, Dunkman M, Eagan R, Eberhardt B, Eichmann B, Eisch J, Euler S, Evenson PA, Fadiran O, Fazely AR, Fedynitch A, Feintzeig J, Felde J, Feusels T, Filimonov K, Finley C, Fischer-Wasels T, Flis S, Franckowiak A, Frantzen K, Fuchs T, Gaisser TK, Gallagher J, Gerhardt L, Gier D, Gladstone L, Glüsenkamp T, Goldschmidt A, Golup G, Gonzalez JG, Goodman JA, Góra D, Grandmont DT, Grant D, Gretskov P, Groh JC, Groß A, Ha C, Haack C, Haj Ismail A, Hallen P, Hallgren A, Halzen F, Hanson K, Hebecker D, Heereman D, Heinen D, Helbing K, Hellauer R, Hellwig D, Hickford S, Hill GC, Hoffman KD, Hoffmann R, Homeier A, Hoshina K, Huang F, Huelsnitz W, Hulth PO, Hultqvist K, Hussain S, Ishihara A, Jacobi E, Jacobsen J, Jagielski K, Japaridze GS, Jero K, Jlelati O, Jurkovic M, Kaminsky B, Kappes A, Karg T, Karle A, Kauer M, Kelley JL, Kheirandish A, Kiryluk J, Kläs J, Klein SR, Köhne JH, Kohnen G, Kolanoski H, Koob A, Köpke L, Kopper C, Kopper S, Koskinen DJ, Kowalski M, Kriesten A, Krings K, Kroll G, Kunnen J, Kurahashi N, Kuwabara T, Labare M, Larsen DT, Larson MJ, Lesiak-Bzdak M, Leuermann M, Leute J, Lünemann J, Macías O, Madsen J, Maggi G, Maruyama R, Mase K, Matis HS, McNally F, Meagher K, Meli A, Meures T, Miarecki S, Middell E, Middlemas E, Milke N, Miller J, Mohrmann L, Montaruli T, Morse R, Nahnhauer R, Naumann U, Niederhausen H, Nowicki SC, Nygren DR, Obertacke A, Odrowski S, Olivas A, Omairat A, O'Murchadha A, Palczewski T, Paul L, Penek O, Pepper JA, Pérez de Los Heros C, Pfendner C, Pieloth D, Pinat E, Posselt J, Price PB, Przybylski GT, Pütz J, Quinnan M, Rädel L, Rameez M, Rawlins K, Redl P, Rees I, Reimann R, Resconi E, Rhode W, Richman M, Riedel B, Robertson S, Rodrigues JP, Rongen M, Rott C, Ruhe T, Ruzybayev B, Ryckbosch D, Saba SM, Sander HG, Santander M, Sarkar S, Schatto K, Scheriau F, Schmidt T, Schmitz M, Schoenen S, Schöneberg S, Schönwald A, Schukraft A, Schulte L, Schulz O, Seckel D, Sestayo Y, Seunarine S, Shanidze R, Sheremata C, Smith MWE, Soldin D, Spiczak GM, Spiering C, Stamatikos M, Stanev T, Stanisha NA, Stasik A, Stezelberger T, Stokstad RG, Stößl A, Strahler EA, Ström R, Strotjohann NL, Sullivan GW, Taavola H, Taboada I, Tamburro A, Tepe A, Ter-Antonyan S, Terliuk A, Tešić G, Tilav S, Toale PA, Tobin MN, Tosi D, Tselengidou M, Unger E, Usner M, Vallecorsa S, van Eijndhoven N, Vandenbroucke J, van Santen J, Vehring M, Voge M, Vraeghe M, Walck C, Wallraff M, Weaver C, Wellons M, Wendt C, Westerhoff S, Whelan BJ, Whitehorn N, Wichary C, Wiebe K, Wiebusch CH, Williams DR, Wissing H, Wolf M, Wood TR, Woschnagg K, Xu DL, Xu XW, Yanez JP, Yodh G, Yoshida S, Zarzhitsky P, Ziemann J, Zierke S, Zoll M. Observation of high-energy astrophysical neutrinos in three years of IceCube data. PHYSICAL REVIEW LETTERS 2014; 113:101101. [PMID: 25238345 DOI: 10.1103/physrevlett.113.101101] [Show More Authors] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Indexed: 06/03/2023]
Abstract
A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV-PeV range at the level of 10(-8) GeV cm-2 s-1 sr-1 per flavor and reject a purely atmospheric explanation for the combined three-year data at 5.7σ. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year data set, with a live time of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000-TeV event is the highest-energy neutrino interaction ever observed.
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Sarkar S, Hopper AK. tRNA nuclear export in saccharomyces cerevisiae: in situ hybridization analysis. Mol Biol Cell 1998; 9:3041-55. [PMID: 9802895 PMCID: PMC25586 DOI: 10.1091/mbc.9.11.3041] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
To understand the factors specifically affecting tRNA nuclear export, we adapted in situ hybridization procedures to locate endogenous levels of individual tRNA families in wild-type and mutant yeast cells. Our studies of tRNAs encoded by genes lacking introns show that nucleoporin Nup116p affects both poly(A) RNA and tRNA export, whereas Nup159p affects only poly(A) RNA export. Los1p is similar to exportin-t, which facilitates vertebrate tRNA export. A los1 deletion mutation affects tRNA but not poly(A) RNA export. The data support the notion that Los1p and exportin-t are functional homologues. Because LOS1 is nonessential, tRNA export in vertebrate and yeast cells likely involves factors in addition to exportin-t. Mutation of RNA1, which encodes RanGAP, causes nuclear accumulation of tRNAs and poly(A) RNA. Many yeast mutants, including those with the rna1-1 mutation, affect both pre-tRNA splicing and RNA export. Our studies of the location of intron-containing pre-tRNAs in the rna1-1 mutant rule out the possibility that this results from tRNA export occurring before splicing. Our results also argue against inappropriate subnuclear compartmentalization causing defects in pre-tRNA splicing. Rather, the data support "feedback" of nucleus/cytosol exchange to the pre-tRNA splicing machinery.
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Guzzella L, Roscioli C, Viganò L, Saha M, Sarkar SK, Bhattacharya A. Evaluation of the concentration of HCH, DDT, HCB, PCB and PAH in the sediments along the lower stretch of Hugli estuary, West Bengal, northeast India. ENVIRONMENT INTERNATIONAL 2005; 31:523-534. [PMID: 15788193 DOI: 10.1016/j.envint.2004.10.014] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Accepted: 10/15/2004] [Indexed: 05/24/2023]
Abstract
Detailed analyses of persistent organic pollutants (POPs) such as hexachlorocyclohexane (HCH) isomers (HCHs), dichlorodiphenyltrichloro ethane (DDT) and its metabolites (DDTs), hexachlorobenzene (HCB) and congeners of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the coastal estuarine environment of West Bengal, northeast India allowed the evaluation of the contamination status, distribution and possible pollution sources. HCH, DDT, HCB, PCB and PAH were identified compounds in all the samples, whereas the concentrations of chlorinated pesticides (trans-eptachlorepoxide, dieldrin, endrin, metaoxychlor and mirex) were below the detection limits and were not of great concern. The pesticides did demonstrate markedly different distributions reflecting different agricultural and domestic usage in the region. The range of concentrations of HCH, HCB, DDT and PCBs in the sediments were 0.11-0.40, <0.05-0.98, 0.18-1.93 and 0.18-2.33 ng/g dry wt, respectively. Overall elevated levels of HCB, DDT and PCB were recorded at Babughat, a very closely located site of the metropolitan megacity Calcutta. Fluoranthene (flu) and pyrene (py), the dominant 4-ring PAHs, also showed an abrupt elevated concentrations at Babughat with values of 214 and 144 ng/g dry wt, respectively. Among the isomers and metabolites of HCH, DDT and PCB, alpha-HCH, pp'-DDT and PCB (101), PCB (118), PCB(153) and PCB (138) were found to be dominant. High ratios of metabolites of DDT to SigmaDDTs reveal recent use of DDT in this coastal environment. Fluoranthene, pyrene, 1,2-benzo(a)anthracene and chrysene formed the dominant congeners out of 19 identified PAHs. The sources of contamination are closely related to human activities such as domestic and industrial discharge, automobile exhausts, street runoff, slum sewage, agricultural chemicals and soil erosion due to deforestation as well as atmospheric transport. This study is compared to other coastal and estuarine environments in India and abroad. The baseline data can be used for regular ecological monitoring, considering the industrial and agricultural growth around this important estuarine ecosystem.
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Sarkar S, Ma WT, Sandri GH. On fluctuation analysis: a new, simple and efficient method for computing the expected number of mutants. Genetica 1992; 85:173-9. [PMID: 1624139 DOI: 10.1007/bf00120324] [Citation(s) in RCA: 137] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fluctuation analysis, which is often used to demonstrate random mutagenesis in cell lines (and to estimate mutation rates), is based on the properties of a probability distribution known as the Luria-Delbrück distribution (and its generalizations). The two main new results reported in this paper are (i) a simple, completely general, and computationally efficient procedure for calculating probability distributions arising from fluctuation analysis and (ii) the formula for this procedure when cells in a colony have only grown for a finite number of generations after initial seeding. It is also shown that the procedure reduces to one that was developed earlier when an infinite number of generations is assumed. The derivation of the generating function of the distribution is also clarified. The results obtained should also be useful to experimentalists when only a relatively short time elapses between seeding and harvesting cultures for fluctuation analysis.
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Sarkar S, Jun S, Rellick S, Quintana DD, Cavendish JZ, Simpkins JW. Expression of microRNA-34a in Alzheimer's disease brain targets genes linked to synaptic plasticity, energy metabolism, and resting state network activity. Brain Res 2016; 1646:139-151. [PMID: 27235866 DOI: 10.1016/j.brainres.2016.05.026] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/06/2016] [Accepted: 05/13/2016] [Indexed: 01/07/2023]
Abstract
Polygenetic risk factors and reduced expression of many genes in late-onset Alzheimer's disease (AD) impedes identification of a target(s) for disease-modifying therapies. We identified a single microRNA, miR-34a that is over expressed in specific brain regions of AD patients as well as in the 3xTg-AD mouse model. Specifically, increased miR-34a expression in the temporal cortex region compared to age matched healthy control correlates with severity of AD pathology. miR-34a over expression in patient's tissue and forced expression in primary neuronal culture correlates with concurrent repression of its target genes involved in synaptic plasticity, oxidative phosphorylation and glycolysis. The repression of oxidative phosphorylation and glycolysis related proteins correlates with reduced ATP production and glycolytic capacity, respectively. We also found that miR-34a overexpressed neurons secrete miR-34a containing exosomes that are taken up by neighboring neurons. Furthermore, miR-34a targets dozens of genes whose expressions are known to be correlated with synchronous activity in resting state functional networks. Our analysis of human genomic sequences from the tentative promoter of miR-34a gene shows the presence of NFκB, STAT1, c-Fos, CREB and p53 response elements. Together, our results raise the possibilities that pathophysiology-induced activation of specific transcription factor may lead to increased expression of miR-34a gene and miR-34a mediated concurrent repression of its target genes in neural networks may result in dysfunction of synaptic plasticity, energy metabolism, and resting state network activity. Thus, our results provide insights into polygenetic AD mechanisms and disclose miR-34a as a potential therapeutic target for AD.
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Sabhachandani P, Motwani V, Cohen N, Sarkar S, Torchilin V, Konry T. Generation and functional assessment of 3D multicellular spheroids in droplet based microfluidics platform. LAB ON A CHIP 2016; 16:497-505. [PMID: 26686985 PMCID: PMC4834071 DOI: 10.1039/c5lc01139f] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Here we describe a robust, microfluidic technique to generate and analyze 3D tumor spheroids, which resembles tumor microenvironment and can be used as a more effective preclinical drug testing and screening model. Monodisperse cell-laden alginate droplets were generated in polydimethylsiloxane (PDMS) microfluidic devices that combine T-junction droplet generation and external gelation for spheroid formation. The proposed approach has the capability to incorporate multiple cell types. For the purposes of our study, we generated spheroids with breast cancer cell lines (MCF-7 drug sensitive and resistant) and co-culture spheroids of MCF-7 together with a fibroblast cell line (HS-5). The device has the capability to house 1000 spheroids on chip for drug screening and other functional analysis. Cellular viability of spheroids in the array part of the device was maintained for two weeks by continuous perfusion of complete media into the device. The functional performance of our 3D tumor models and a dose dependent response of standard chemotherapeutic drug, doxorubicin (Dox) and standard drug combination Dox and paclitaxel (PCT) was analyzed on our chip-based platform. Altogether, our work provides a simple and novel, in vitro platform to generate, image and analyze uniform, 3D monodisperse alginate hydrogel tumors for various omic studies and therapeutic efficiency screening, an important translational step before in vivo studies.
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Abstract
Organicism (materialistic holism) has provided the philosophical underpinnings for embryology since the time of Kant. It had influenced the founders of developmental mechanics, and the importance of organicism to embryology was explicitly recognized by such figures as O. Hertwig, H. Spemann, R. Harrison, A. M. Dalq, J. Needham, and C. H. Waddington. Many of the principles of organicism remain in contemporary developmental biology, but they are rarely defined as such. A combination of genetic reductionism and the adoption of holism by unscientific communities has led to the devaluation of organicism as a fruitful heuristic for research. This essay attempts to define organicism, provide a brief history of its importance to experimental embryology, outline some sociologically based reasons for its decline, and document its value in contemporary developmental biology. Based on principles or organicism, developmental biology should become a science of emerging complexity. However, this does mean that some of us will have to learn calculus.
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Chatterjee M, Silva Filho EV, Sarkar SK, Sella SM, Bhattacharya A, Satpathy KK, Prasad MVR, Chakraborty S, Bhattacharya BD. Distribution and possible source of trace elements in the sediment cores of a tropical macrotidal estuary and their ecotoxicological significance. ENVIRONMENT INTERNATIONAL 2007; 33:346-56. [PMID: 17196656 DOI: 10.1016/j.envint.2006.11.013] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Revised: 11/07/2006] [Accepted: 11/13/2006] [Indexed: 05/13/2023]
Abstract
The paper presents the first document regarding concentration, distribution and possible sources of selected trace elements (Cu, Fe, Mn, Zn, Cr, Co, Ni, Pb, Al, B and Ba) in core sediments (<63 micro particle size) from the lower stretch of Hugli (Ganges) estuary, northeast coast of Bay of Bengal by ICP-AES and EDXRF to evaluate geochemical processes influencing their distribution and possible environmental consequences. The levels of elements showed a wide range of variations in different core depths, in upper and lower intertidal zones as well as among three sampling stations. The most interesting feature of the study is the downward increase of concentrations of majority of the elements reaching overall maximum values at a depth of 20-28 cm in upper littoral zone of the site located in the extreme downstream stretch of the estuary. Values of organic carbon showed very strong positive correlations with most of the elements as revealed by correlation matrix (r) values. The interelemental relationship revealed the identical behavior of element during its transport in the estuarine environment. The overall variation in concentration can be attributed to differential discharge of untreated effluents originating from industrial, agricultural, and aquacultural sources as well as from domestic sewage along with the fishing and boating activities. The resulting compositional dataset was tested by principal component analyses and cluster analyses. Pollution load index (PLI) and index of Geoaccumulation (Igeo) revealed overall low values but the enrichment factors (EFs) for Pb were typically high for all the stations. The mean concentrations of Zn and to some extent Cu exceeded the Effects Range-Low (ER-L) values in the majority of the cases indicating that there may be some ecotoxicological risk to organisms living in sediments. The concentration of the trace elements reported in this work is useful as baselines for comparison in future sediment quality studies.
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Sarkar S, Donn SM. Management of neonatal abstinence syndrome in neonatal intensive care units: a national survey. J Perinatol 2006; 26:15-7. [PMID: 16355103 DOI: 10.1038/sj.jp.7211427] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
AIMS To determine the monitoring and treatment of neonatal abstinence syndrome (NAS) in neonatal intensive care units (NICUs) following opiate or polydrug exposure in utero. METHODS A pretested questionnaire was distributed via email to the chiefs of the neonatology divisions with accredited Fellowship programs in Neonatal-Perinatal Medicine in the United States. RESULTS Of the 102 individuals contacted, 75 participated in the survey. In all, 41 of the respondents (54.5%) have a written policy regarding the management of neonatal NAS. The method of Finnegan is the most commonly used abstinence scoring system (49 of 75, 65%), while only three respondents use the Lipsitz tool. Opioids (tincture of opium, or morphine sulfate solution) are used most commonly for management of both opioid (63% of respondents) and polydrug (52% of respondents) withdrawal, followed by phenobarbital (32 % of respondents) for polydrug withdrawal and methadone (20% of respondents) for opioid withdrawal. In all, 53 respondents (70%) use phenobarbital, and 19 (25%) use intravenous morphine to control opioid withdrawal seizures, while 61 (81%) use phenobarbital in cases of polydrug withdrawal seizures. Only 53 respondents (70%) always use an abstinence scoring system to determine when to start, titrate, or terminate pharmacologic treatment of neonatal NAS. CONCLUSION The management of neonatal psychomotor behavior consistent with withdrawal varies widely, with inconsistent policies to determine its presence or treatment. Only about half of NICUs have written guidelines for the management of NAS, which may preclude effective auditing of this practice. Educational interventions may be necessary to ensure changes in clinical practice.
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Burgoyne RD, Cambray-Deakin MA, Lewis SA, Sarkar S, Cowan NJ. Differential distribution of beta-tubulin isotypes in cerebellum. EMBO J 1988; 7:2311-9. [PMID: 2461292 PMCID: PMC457095 DOI: 10.1002/j.1460-2075.1988.tb03074.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We describe the structure and expression of a mammalian beta-tubulin isotype (M beta 6) that is weakly expressed in testis but is abundant in developing brain, with transcripts declining to lower levels in the adult brain. The expression of M beta 6 was undetectable in any other mouse tissue examined. A serum specific for this isotype was prepared using a cloned fusion protein as immunogen. M beta 6 is one of five known beta-tubulin isotypes expressed in brain, and using the anti-M beta 6 serum along with sera, anti-M beta 2, anti-M beta 3/4 and anti-M beta 5, previously characterized, we have examined the pattern of expression of beta-tubulin isotypes in rat cerebellum. The isotypes each have characteristic cell-type specific patterns of localization in cerebellum. M beta 2, M beta 3/4 and M beta 5 are present in both neuronal and non-neuronal cells, but in contrast M beta 6 was only detectable in neurons in tissue sections and in dissociated cerebellar cell culture. The majority of sequence differences among the beta-tubulin isotypes lie at the carboxy terminus, the region of beta-tubulin involved in MAP binding. In the case of M beta 2 and M beta 6, the patterns of expression are similar or identical to the patterns of expression of MAP3 and MAP1A respectively. These results suggest that beta-tubulin isotypes may contribute to the determination of the specific association of MAPs with microtubules of diverse function. However, the strict subcellular segregation of other MAPs in brain may be determined by other factors.
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Sarkar S, Hobson AR, Furlong PL, Woolf CJ, Thompson DG, Aziz Q. Central neural mechanisms mediating human visceral hypersensitivity. Am J Physiol Gastrointest Liver Physiol 2001; 281:G1196-202. [PMID: 11668028 DOI: 10.1152/ajpgi.2001.281.5.g1196] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although visceral hypersensitivity is thought to be important in generating symptoms in functional gastrointestinal disorders, the neural mechanisms involved are poorly understood. We recently showed that central sensitization (hyperexcitability of spinal cord sensory neurones) may play an important role. In this study, we demonstrate that after a 30-min infusion of 0.15 M HCl acid into the healthy human distal esophagus, we see a reduction in the pain threshold to electrical stimulation of the non-acid-exposed proximal esophagus (9.6 +/- 2.4 mA) and a concurrent reduction in the latency of the N1 and P2 components of the esophageal evoked potentials (EEP) from this region (10.4 +/- 2.3 and 15.8 +/- 5.3 ms, respectively). This reduced EEP latency indicates a central increase in afferent pathway velocity and therefore suggests that hyperexcitability within the central visceral pain pathway contributes to the hypersensitivity within the proximal, non-acid-exposed esophagus (secondary hyperalgesia/allodynia). These findings provide the first electrophysiological evidence that central sensitization contributes to human visceral hypersensitivity.
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Sarkar S, Azad AK, Hopper AK. Nuclear tRNA aminoacylation and its role in nuclear export of endogenous tRNAs in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 1999; 96:14366-71. [PMID: 10588711 PMCID: PMC24442 DOI: 10.1073/pnas.96.25.14366] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nuclear tRNA aminoacylation was proposed to provide a proofreading step in Xenopus oocytes, ensuring nuclear export of functional tRNAs [Lund, E. & Dahlberg, J. E. (1998) Science 282, 2082-2085]. Herein, it is documented that tRNA aminoacylation also occurs in yeast nuclei and is important for tRNA export. We propose that tRNA aminoacylation functions in one of at least two parallel paths of tRNA export in yeast. Alteration of one aminoacyl-tRNA synthetase affects export of only cognate tRNA, whereas alterations of two other aminoacyl-tRNA synthetases affect export of both cognate and noncognate tRNAs. Saturation of tRNA export pathway is a possible explanation of this phenomenon.
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Sarkar S, Yadav P, Trivedi R, Bansal AK, Bhatnagar D. Cadmium-induced lipid peroxidation and the status of the antioxidant system in rat tissues. J Trace Elem Med Biol 1995; 9:144-9. [PMID: 8605602 DOI: 10.1016/s0946-672x(11)80038-6] [Citation(s) in RCA: 119] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cadmium may induce oxidative damage in different tissues by enhancing peroxidation of membrane lipids and altering the antioxidant system of the cells. The peroxidative damage to the cell membrane may cause injury to cellular components due to the interaction of metal ions with the cell organelles. The treatment with Cd (0.4 mg/kg body wt, ip) significantly increased lipid peroxidation (LPO) in heart within 3 h of the Cd injection, while the increase in kidney and liver followed 6 to 12 h after Cd intoxication. The antioxidant enzymes and other antioxidants provide protection to the cells against oxidative damage. The superoxide dismutase (SOD) activity increased in heart, kidney and liver within 24 h of Cd intoxication. The CAT activity increased significantly in heart 9 h after Cd injection; however, no significant change in CAT activity was observed in kidney and liver tissues. The GSH content and the activity of GR decreased in heart, kidney and liver 72 h after Cd administration, which has been suggested to be the cause for increased LPO in the tissues. The hexose monophosphate (HMP) shunt enzymes generate NADPH required for the activity of GR which may affect the GSH content in the tissues. The generalised decrease in glucose 6-phosphate dehydrogenase (G6PDH) and 6 phospho gluconate dehydrogenase (6PGDH) at 9 h followed by an increase in these enzymes in tissues 72 h after Cd intoxication suggest that the production of NADPH by the HMP shunt is required to reduce the oxidative damage. The results show that Cd induced LPO in the tissues and the condition was partially counteracted by the antioxidant system.
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Sarkar S, Pranava M, Marita R. Demonstration of the hypoglycemic action of Momordica charantia in a validated animal model of diabetes. Pharmacol Res 1996; 33:1-4. [PMID: 8817639 DOI: 10.1006/phrs.1996.0001] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In an effort to establish and document the hypoglycaemic activity of Momordica charantia in validated models of diabetes, the alcoholic extract of the pulp was studied. In the normal glucose primed rat model, M. charantia fruit extract, 500 mg kg-1, depressed the plasma glucose levels by 10-15% at 1 h. Under similar conditions, tolbutamide (100 mg kg-1) caused approximately 40% reductions in plasma glucose both at 1 and 2 h. At 500 mg kg-1, the efficacy of M. charantia was 25-30% of tolbutamide. The reduction in plasma glucose in normal glucose primed rat was not accompanied by increased insulin secretion. There was no evidence of tachyphylaxis to the effect of M. charantia extract on repeated dosing. In streptozotocin diabetes rats, it improved the oral glucose tolerance causing significant (P < 0.002) reduction in plasma glucose of 26% at 3.5 h while metformin caused 40-50% reduction at 1, 2 and 3.5 h. M. charantia extract (500 mg kg-1) caused a 4-5-fold increase in the rate of glycogen synthesis from U-14C-glucose in the liver of normally fed rats. These data suggest that the mechanism of action of M. charantia could be partly attributed to increased glucose utilization in the liver rather than an insulin secretion effect. This is the first report on the effect of M. charantia in characterized and validated animal model systems known to respond to oral hypoglycaemic drugs.
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Sarkar S, Wilson M. Lethal photosensitization of bacteria in subgingival plaque from patients with chronic periodontitis. J Periodontal Res 1993; 28:204-10. [PMID: 8388448 DOI: 10.1111/j.1600-0765.1993.tb01070.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Subgingival plaque samples from patients with chronic periodontitis were exposed to light from a 7.3 mW Helium/Neon laser for 30 s in the presence and absence of 50 micrograms/ml toluidine blue O as a photosensitizer. Viable counts of various groups and species of bacteria were carried out before and after irradiation. The median numbers of viable bacteria initially present in the 30-microliters aliquots irradiated were 1.13 x 10(5) cfu (aerobes), 4.08 x 10(5) cfu (anaerobes), 4.92 x 10(3) cfu (black-pigmented anaerobes), 4.75 x 10(2) cfu (Porphyromonas gingivalis), 6.15 x 10(3) cfu (Fusobacterium nucleatum) and 1.7 x 10(4) cfu (streptococci). The dye/laser combination achieved significant reductions in the viability of these organisms, the median reductions in the viable counts being 91.1% for aerobes, 96.6% for anaerobes, 100% for black-pigmented anaerobes, P. gingivalis and F. nucleatum and 94.2% for streptococci. Overall, the viability of bacteria in the 20 plaque samples was not significantly decreased by the dye alone. However, in a small minority of samples there were indications of light-independent, dye-induced toxicity. Low-power lasers, in conjunction with appropriate photosensitizers, may be a useful adjunct to mechanical debridement in the treatment of inflammatory periodontal diseases if a similar effectiveness against subgingival plaque bacteria can be achieved in vivo.
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