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Sabin ND, Cheung YT, Reddick WE, Bhojwani D, Liu W, Glass JO, Brinkman TM, Hwang SN, Srivastava D, Pui CH, Robison LL, Hudson MM, Krull KR. The Impact of Persistent Leukoencephalopathy on Brain White Matter Microstructure in Long-Term Survivors of Acute Lymphoblastic Leukemia Treated with Chemotherapy Only. AJNR Am J Neuroradiol 2018; 39:1919-1925. [PMID: 30213807 DOI: 10.3174/ajnr.a5791] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 07/19/2018] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Survivors of acute lymphoblastic leukemia are at risk for neurocognitive deficits and leukoencephalopathy. We performed a longitudinal assessment of leukoencephalopathy and its associations with long-term brain microstructural white matter integrity and neurocognitive outcomes in survivors of childhood acute lymphoblastic leukemia treated on a modern chemotherapy-only protocol. MATERIALS AND METHODS One hundred seventy-three survivors of acute lymphoblastic leukemia (49% female), treated on a chemotherapy-only protocol, underwent brain MR imaging during active therapy and repeat imaging and neurocognitive testing at follow-up (median, 13.5 years of age; interquartile range, 10.7-17.6 years; median time since diagnosis, 7.5 years; interquartile range, 6.3-9.1 years). Persistence of leukoencephalopathy was examined in relation to demographic and treatment data and to brain DTI in major fiber tracts and neurocognitive testing at follow-up. RESULTS Leukoencephalopathy was found in 52 of 173 long-term survivors (30.0%) and persisted in 41 of 52 (78.8%) who developed it during therapy. DTI parameters were associated with leukoencephalopathy in multiple brain regions, including the corona radiata (fractional anisotropy, P = .001; mean diffusivity, P < .001), superior longitudinal fasciculi (fractional anisotropy, P = .02; mean diffusivity, P < .001), and superior fronto-occipital fasciculi (fractional anisotropy, P = .006; mean diffusivity, P < .001). Mean diffusivity was associated with neurocognitive impairment including in the genu of the corpus callosum (P = .04), corona radiata (P = .02), and superior fronto-occipital fasciculi (P = .02). CONCLUSIONS Leukoencephalopathy during active therapy and neurocognitive impairment at long-term follow-up are associated with microstructural white matter integrity. DTI may be more sensitive than standard MR imaging for detection of clinically consequential white matter abnormalities in childhood acute lymphoblastic leukemia survivors treated with chemotherapy and in children undergoing treatment.
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Srivastava D, Favez O, Bonnaire N, Lucarelli F, Haeffelin M, Perraudin E, Gros V, Villenave E, Albinet A. Speciation of organic fractions does matter for aerosol source apportionment. Part 2: Intensive short-term campaign in the Paris area (France). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 634:267-278. [PMID: 29627550 DOI: 10.1016/j.scitotenv.2018.03.296] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 06/08/2023]
Abstract
The present study aimed at performing PM10 source apportionment, using positive matrix factorization (PMF), based on filter samples collected every 4h at a sub-urban station in the Paris region (France) during a PM pollution event in March 2015 (PM10>50μgm-3 for several consecutive days). The PMF model allowed to deconvolve 11 source factors. The use of specific primary and secondary organic molecular markers favoured the determination of common sources such as biomass burning and primary traffic emissions, as well as 2 specific biogenic SOA (marine+isoprene) and 3 anthropogenic SOA (nitro-PAHs+oxy-PAHs+phenolic compounds oxidation) factors. This study is probably the first one to report the use of methylnitrocatechol isomers as well as 1-nitropyrene to apportion secondary OA linked to biomass burning emissions and primary traffic emissions, respectively. Secondary organic carbon (SOC) fractions were found to account for 47% of the total OC. The use of organic molecular markers allowed the identification of 41% of the total SOC composed of anthropogenic SOA (namely, oxy-PAHs, nitro-PAHs and phenolic compounds oxidation, representing 15%, 9%, 11% of the total OC, respectively) and biogenic SOA (marine+isoprene) (6% in total). Results obtained also showed that 35% of the total SOC originated from anthropogenic sources and especially PAH SOA (oxy-PAHs+nitro-PAHs), accounting for 24% of the total SOC, highlighting its significant contribution in urban influenced environments. Anthropogenic SOA related to nitro-PAHs and phenolic compounds exhibited a clear diurnal pattern with high concentrations during the night indicating the prominent role of night-time chemistry but with different chemical processes involved.
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Small C, Kemp H, Haywood K, Srivastava D. Current variation in the practice of measuring post-operative pain outcomes: time for a national consensus? Br J Anaesth 2018. [DOI: 10.1016/j.bja.2017.11.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Daniel LC, Wang M, Srivastava D, Schwartz L, Brinkman T, Edelstein K, Mulrooney D, Zhou E, Howell R, Gibson T, Leisenring W, Armstrong GT, Krull K. 0863 Sleep Behaviors And Patterns In Adult Survivors Of Childhood Cancers: A Report From The Childhood Cancer Survivor Study (CCSS). Sleep 2018. [DOI: 10.1093/sleep/zsy061.862] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Verma S, Rao B, Srivastava A, Srivastava D, Kaul R, Singh B. A facile synthesis of broad plasmon wavelength tunable silver nanoparticles in citrate aqueous solutions by laser ablation and light irradiation. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.05.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Singh H, Maurya RK, Kapoor P, Sharma P, Srivastava D. Subjective and objective evaluation of frontal smile esthetics in patients with facial asymmetry-a comparative cross-sectional study. Orthod Craniofac Res 2016; 20:8-20. [PMID: 27862935 DOI: 10.1111/ocr.12135] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2016] [Indexed: 11/27/2022]
Abstract
AIM AND OBJECTIVES To analyze the relationship between subjective and objective evaluations of pre-treatment posed smiles in patients with facial asymmetry and to assess the influence of dentofacial structures involved in asymmetry on the perception of smile attractiveness. SAMPLE Thirty-five patients (25 males and 10 females) between 18 and 25 years of age with facial asymmetry were selected. MATERIALS AND METHODS Pre-treatment clinical photographs of posed smiles were subjectively evaluated by a panel of 20 orthodontists, 20 oral surgeons, and 20 laypersons. A customized Smile Mesh program was used for objective evaluation of the same smiles. Direct comparison among three smile groups (unattractive, slightly attractive, and attractive) for different Smile Mesh measurements was carried out using two-way anova test. Additionally, linear regression was performed to evaluate whether these measurements could predict the attractiveness of captured smiles. RESULTS Patients with 'slightly attractive' smiles had a significantly greater distance between the incisal margin of the maxillary central incisor and the lower lip during smiling. The Smile Index was significantly greater in attractive smiles. However, based on the coefficients of linear regression, no objectively gathered measurement could predict smile attractiveness. CONCLUSIONS Attractiveness or unattractiveness of smiles in patients with facial asymmetry could not be predicted by any measurement of Smile Mesh. The presence of facial asymmetry did not significantly influence the perception of smile esthetics.
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Srivastava D, Azough F, Freer R, Combe E, Funahashi R, Kepaptsoglou DM, Ramasse QM, Molinari M, Yeandel SR, Baran JD, Parker SC. Crystal structure and thermoelectric properties of Sr-Mo substituted CaMnO 3: a combined experimental and computational study. JOURNAL OF MATERIALS CHEMISTRY. C 2015; 3:12245-12259. [PMID: 28496979 PMCID: PMC5361175 DOI: 10.1039/c5tc02318a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 10/30/2015] [Indexed: 06/07/2023]
Abstract
A combination of experimental and computational techniques has been employed to study doping effects in perovskite CaMnO3. High quality Sr-Mo co-substituted CaMnO3 ceramics were prepared by the conventional mixed oxide route. Crystallographic data from X-ray and electron diffraction showed an orthorhombic to tetragonal symmetry change on increasing the Sr content, suggesting that Sr widens the transition temperature in CaMnO3 preventing phase transformation-cracking on cooling after sintering, enabling the fabrication of high density ceramics. Atomically resolved imaging and analysis showed a random distribution of Sr in the A-site of the perovskite structure and revealed a boundary structure of 90° rotational twin boundaries across {101}orthorhombic; the latter are predominant phonon scattering sources to lower the thermal conductivity as suggested by molecular dynamics calculations. The effect of doping on the thermoelectric properties was evaluated. Increasing Sr substitution reduces the Seebeck coefficient but the power factor remains high due to improved densification by Sr substitution. Mo doping generates additional charge carriers due to the presence of Mn3+ in the Mn4+ matrix, reducing electrical resistivity. The major impact of Sr on thermoelectric behaviour is the reduction of the thermal conductivity as shown experimentally and by modelling. Strontium containing ceramics showed thermoelectric figure of merit (ZT) values higher than 0.1 at temperatures above 850 K. Ca0.7Sr0.3Mn0.96Mo0.04O3 ceramics exhibit enhanced properties with S1000K = -180 μV K-1, ρ1000K = 5 × 10-5 Ωm, k1000K = 1.8 W m-1 K-1 and ZT ≈ 0.11 at 1000 K.
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Kulshrestha N, Srivastava D, Ghatak T, Yadav MS, Samanta S. An unusual case of recurrent urinary tract infection. Indian J Nephrol 2015; 25:392-3. [PMID: 26664226 PMCID: PMC4663788 DOI: 10.4103/0971-4065.161027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Srivastava D, Dhakad U, Das S, Wakhlu A, Kumar P, Nolkha N, Sharma A, Bhadu D, Sharma M. Bone Mineral density levels in patients of ankylosing spondylitis – An observational short study. INDIAN JOURNAL OF RHEUMATOLOGY 2014. [DOI: 10.1016/j.injr.2014.10.138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Srivastava D, Ghoshal U, Mittal RD, Ghoshal UC. Associations between IL-1RA polymorphisms and small intestinal bacterial overgrowth among patients with irritable bowel syndrome from India. Neurogastroenterol Motil 2014; 26:1408-16. [PMID: 25073651 DOI: 10.1111/nmo.12399] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 06/18/2014] [Indexed: 01/08/2023]
Abstract
BACKGROUND Low-grade inflammation (controlled by pro and anti-inflammatory molecules), induced by gut microbes in patients with small intestinal bacterial overgrowth (SIBO), may be associated with irritable bowel syndrome (IBS). Polymorphisms of IL-RA gene (anti-inflammatory) was evaluated in IBS and healthy subjects (HS); small intestinal mucosal IL-1α and β levels (pro-inflammatory) in relation to the presence of SIBO were evaluated in a subset of patients. METHODS Two hundred and twenty-one IBS patients and 273 age- and gender-matched HS were included. Exactly 209 of 221 patients (Rome III) and 273 HS were genotyped (PCR) for IL-1RA polymorphism. Mucosal IL-1α and β levels (pg/mg of biopsy) were estimated (ELISA) in 82/221 patients with and without SIBO (≥10(5) CFU/mL upper gut aspirate bacteria). KEY RESULTS Genotype 1/1 (IL-1RA over-producer) was less frequent among patients than controls (p = 0.007); genotypes 1/3 (p = 0.012, OR = 3.301, 95% CI = 1.31-8.35) and 2/3 (both under-producers; p = 0.009, OR = 7.703, 95% CI = 1.66-35.82) were commoner among IBS. Fifteen of 82 (18.3%) patients had SIBO. Levels of IL-1α and β were higher among patients with SIBO than without (IL-1α: 35.4 [20.1-66.8] vs 25.5 [4.2-65.3], p < 0.001; IL-1β: 206.8 [133.5-365.9] vs 93.1 [25.5-197.7], p < 0.001) and those with bloating than without (p = 0.012; p = 0.015). IL-1β was higher among patients with Bristol stool type 6 than those with type 1-2 (p = 0.002) and type 3-5 (p = 0.007). CONCLUSIONS & INFERENCES Polymorphisms 1/1 (IL-1RA over-producer) was infrequent and 1/3 and 2/3 (under-producers) frequent among IBS. Increased IL-1α and β levels were associated with SIBO. Increased IL-1β level was predominantly associated with bloating and loose stools (Bristol type 6).
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Gupta S, Misra R, Ghosh UK, Gupta V, Srivastava D. Comparison of foetomaternal circulation in normal pregnancies and pregnancy induced hypertension using color Doppler studies. INDIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY 2014; 58:284-289. [PMID: 25906613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The aim of present study was to assess fetomaternal blood flows in normal and abnormal pregnancies using color Doppler indices. Subjects were divided into two groups as: Group A of 25 subjects of normal pregnancy as controls and group B of 25 subjects of pregnancy induced hypertension. All the subjects were lying in the age-group of 25-35 years and having 28 to 34 weeks of gestation; the patients were evaluated by detailed history and were subjected to complete general examination. Blood pressure was taken on two occasions at least 6 hours apart. Systemic examination and obstetrical examination was done in all subjects. All cases were subjected to pathological tests- Haemogram, Test for proteins in urine. Ultrasound assessment of fetal growth was done by measuring BPD (Biparietal diameter), HC (Head circumference), FL (Femur length) and AC (Abdominal circumference): Average gestational age and effective fetal weight was then calculated by ultrasound machine. Color Doppler was used to assess the various Doppler indices indices: Pulsatility index (PI), Resistive index (RI) and Systolic diastolic ratio (S/D ratio) in bilateral uterine, umbilical and middle cerebral arteries and compared to the standard normograms. Percentage of subjects having abnormal Doppler indices were calculated. Assessment of percentage of SGA (small for gestational age) fetuses was done in all the three groups. Decline in mean values of all Doppler indices was found with advancing gestational age in normal pregnancy suggesting decreased vascular resistance and increased blood flow in fetomaternal circulation. In pregnancy induced hypertensives, the mean values of Doppler indices showed a decline as in normal pregnancy but showed an increase (more than 2 S.D. of the mean) for that gestational age in comparison to the control group suggesting increased impedance to blood flow in uteroplacental and fetomaternal circulation. Umbilical artery Doppler indices were found to be the most sensitive indicator of uteroplacental and fetoplacental insufficiency in pregnancy induced hypertensives (P = 0.001). Thus we concluded that color Doppler can detect changes in fetomaternal circulation which correlate strongly with the fetal growth and therefore associated with pregnancy outcome.
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Nolkha N, Srivastava D, Wakhlu A, Dhakad U. Neuropathic arthropathy and syringomyelia complicating a case of ankylosing spondylitis with peripheral arthritis. CASE REPORTS 2014; 2014:bcr-2014-205604. [DOI: 10.1136/bcr-2014-205604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Liu APY, Shing MMK, Yuen HL, Li CH, Ling SC, Luk CW, Ha SY, Li CK, Chan GCF, Tsui K, Gajjar A, Li C, Srivastava D, Broniscer A, Wetmore C, Kun LE, Merchant TE, Ellison DW, Orr B, Boop FA, Paul Klimo J, Ross JD, Robison LL, Armstrong GT, Walker D, Chu T, Shah A, Wilne S, Coleman M, Jaque FAM, Muthappan M, Law AJJ, Shing MMK, Chan GCF, Yuen HL, Lee RCH, Ling SC, Luk CW, Ha SY, Li CK, Mang OWS, Ngan RKC, Alston R, Estlin E, McCabe M, Birch J, Gattamaneni R, Kamaly-Asl I, Estlin E, Kamaly-Asl I, McCabe M, Birch J, Gattamaneni R, Alston R, Alston R, Estlin E, McCabe M, Gattamaneni R, Birch J, Kamaly-Asl I, Bendel A, Pond D, Woehrer A, Azizi AA, Heumesser R, Hackl M, Hainfellner JA, Dorfer C, Czech T, Chocholous M, Slavc I, Haberler C, Hami H, Ayoujil A, Habib F, Soulaymani A, Mokhtari A, Quyou A, Lim AHJ, Chan MY, Tan AM, Soh SY, Garba SM, Hami H, Zaki HM, Soulaymani A, Nouhou H, Quyou A, Owens-Pickle E, Smith A, Green AL, Schoettler M, Bandopadhayay P, Sauer N, Manley PE, Chi SN, Rodriguez-Galindo C, Kieran MW, Ribeiro K. EPIDEMIOLOGY. Neuro Oncol 2014. [DOI: 10.1093/neuonc/nou069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Srivastava D, Chakrabarti O. Mahogunin-mediated α-tubulin ubiquitination via noncanonical K6 linkage regulates microtubule stability and mitotic spindle orientation. Cell Death Dis 2014; 5:e1064. [PMID: 24556679 PMCID: PMC3944237 DOI: 10.1038/cddis.2014.1] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 12/19/2013] [Accepted: 12/19/2013] [Indexed: 12/26/2022]
Abstract
Mahogunin ring finger-1 (MGRN1) is a cytosolic ubiquitin ligase whose disruption or interaction with some isoforms of cytosolically exposed prion protein leads to spongiform neurodegeneration and also lack of which results in reduced embryonic viability due to mispatterning of the left–right (LR) axis during development. Here we demonstrate an interaction between the cytoskeletal protein α-tubulin and MGRN1. In cultured cell systems, loss of the ubiquitin E3 ligase activity of MGRN1 results in spindle misorientation and decreased α-tubulin polymerization, an effect also seen in primary cells. α-Tubulin was post-translationally modified by MGRN1 via noncanonical K6-linked polyubiquitination. This was significant because expression of catalytically inactive MGRN1 and/or ubiquitin mutant capable of only monoubiquitination resulted in similar mitotic spindle misorientation. The modulatory effect of MGRN1 was specific for α-tubulin and similar changes could not be detected in β- or γ-tubulin. However, catalytic inactivation of MGRN1 did not abrogate monoubiquitination of α-tubulin, thus unraveling a unique dual mode of ubiquitination by an unknown E3 ligase and MGRN1. MGRN1-mediated α-tubulin modification, and hence its stability, may highlight a key event in the LR patterning during embryogenesis.
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Kulkarni R, Mani Krishna K, Neogy S, Srivastava D, Ramadasan E, Dey G, Saibaba N, Jha S, Shriwastaw R, Anantharaman S. Determination of correlation parameters for evaluation of mechanical properties by Small Punch Test and Automated Ball Indentation Test for Zr–2.5% Nb pressure tube material. NUCLEAR ENGINEERING AND DESIGN 2013. [DOI: 10.1016/j.nucengdes.2013.10.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Srivastava D, Gupta A, Srivastava B. Distraction osteogenesis in cleft lip and palate. Int J Oral Maxillofac Surg 2013. [DOI: 10.1016/j.ijom.2013.07.586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gupta A, Srivastava D. Changing trends in maxillofacial trauma in Delhi and National Capital Region-multicentric retrospective study of 450 cases. Int J Oral Maxillofac Surg 2013. [DOI: 10.1016/j.ijom.2013.07.184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fox DA, Srivastava D, Poblenz A, He L. Lead-induced Alterations in Gene Expression and Activity of Retinal cGMP PDE Results in Calcium Overload and Rod-selective Apoptosis. Toxicol In Vitro 2012; 12:597-8. [PMID: 20654449 DOI: 10.1016/s0887-2333(98)00044-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Agarwal A, Pandey R, Das V, Pandey A, Agarwal S, Jain V, Srivastava D. O017 IMPROVING EFFICACY OF MISOPROSTOL FOR INDUCTION OF SECOND TRIMESTER ABORTIONS. Int J Gynaecol Obstet 2012. [DOI: 10.1016/s0020-7292(12)60447-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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AlRais F, Feldstein VA, Srivastava D, Gosnell K, Moon-Grady AJ. Monochorionic twins discordant for congenital heart disease: a referral center's experience and possible pathophysiologic mechanisms. Prenat Diagn 2011; 31:978-84. [DOI: 10.1002/pd.2819] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 06/01/2011] [Accepted: 06/01/2011] [Indexed: 11/10/2022]
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Brenner D, Robertson D, Carty R, Srivastava D, Garrison B. Combining Molecular Dynamics and Monte Carlo Simulations to Model Chemical Vapor Deposition: Application to Diamond. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-278-255] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractGas-surface reactions of the type that contribute to growth during the chemical vapor deposition (CVD) of diamond films are generally completed in picoseconds, well within timescales accessible by molecular dynamics (MD) simulations. For low-pressure deposition, however, the time between collisions for a surface site can be microseconds, which makes direct modeling of CVD crystal growth impossible using standard MD methods. To effectively bridge this discrepancy in timescales, the gas-surface reactions can be modeled using MD trajectories, and then this data can be used to define probabilities in a Monte Carlo algorithm where each step represents a gas-surface collision. We illustrate this approach using the reaction of atomic hydrogen with a diamond (111) surface as an example, where we use abstraction and sticking probabilities generated using classical trajectories in a simple Monte Carlo algorithm to determine the number of open sites as a function of temperature. We also include models for the thermal desorption of hydrogen that predict that growth temperatures are not restricted by the thermal loss of chemisorbed hydrogen.
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Ray D, Aswal VK, Srivastava D. Concentration effect on tuning of block copolymer-mediated synthesis of gold nanoparticles. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2010; 10:6356-6362. [PMID: 21137730 DOI: 10.1166/jnn.2010.2627] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Synthesis of gold nanoparticles has been examined using triblock copolymer Pluronic P85 (EO26PO39EO26) at different concentrations as a function of hydrogen tetrachloroaureate (III) hydrate (HAuCl4 x 3H2O) in aqueous solution. The concentration of P85 block copolymer was varied from 0.5 to 2 wt% at fixed temperature (30 degrees C) in presence of HAuCl4 x 3H2O in the range of 0.002 to 0.2 wt% for each P85 concentration. The surface plasmon resonance in the time-dependent UV-visible spectra reveals that increase in the block copolymer concentration increases the yield of the gold nanoparticles but decreases their stability. Both small-angle neutron scattering (SANS) and dynamic light scattering (DLS) show that the number density of block copolymer micelles increase almost linearly with the concentration, which is related to result in higher numbers of nucleation centers and therefore increase in the yield of gold nanoparticles. The fact that increase in the number density of nanoparticles also increases the chances of aggregation and this tends to decrease the stability at higher block copolymer concentration. Transmission electron microscopy (TEM) images confirm the larger sizes of the nanoparticles formed in these systems at higher concentrations.
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Mohamed SA, Nigam V, Jensen B, Sier H, Simpson P, Srivastava D, Sievers HH. Micrornas in bicuspid aortic valve: a comparison between stenosis and insufficiency aortic valve. Thorac Cardiovasc Surg 2010. [DOI: 10.1055/s-0029-1246793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Armstrong GT, Pan Z, Ness K, Srivastava D, Robison LL. Temporal trends in cause-specific late mortality among five-year survivors of childhood cancer. J Clin Oncol 2009. [DOI: 10.1200/jco.2009.27.15_suppl.10004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
10004 Background: Five-year survival rates for childhood cancer have increased over the past 4 decades, increasing the number of long-term survivors. Among 5-yr survivors, the impact of changes in therapy on cause-specific late mortality has not been thoroughly assessed. Methods: Late mortality was evaluated over 3 eras (1974–81, 1982–90, 1991–2000) in 26,643 5-year survivors diagnosed <21 years of age from the SEER population-based registry. Cause-specific mortality was categorized as death from recurrence/progression of primary disease, external causes, and non-recurrence/non-external causes (Non-Recur/Ext) (i.e., deaths from health conditions including sequelae of cancer therapy). Results: All-cause and Recurrence mortality was significantly lower in more recent eras ( Table ). No significant improvement in late mortality attributable to Non-Recur/Ext causes was seen. Additionally, all-cause mortality was significantly lower in more recent eras for 5-year survivors of ALL, AML, Hodgkin, NHL, and CNS tumors, but not neuroblastoma and Ewing's Sarcoma where an increase in cumulative incidence of late mortality was seen in more recent eras. Significant improvement in late mortality from Recurrence by era was seen in most diagnostic groups. Conclusions: All-cause late mortality has improved with more recent eras, attributable to reduced rates of mortality from progression of primary disease (i.e., durable remission). Importantly, however, efforts to reduce the toxicity of more recent therapies have not produced detectable reduction in mortality attributable to other health conditions including sequelae of cancer therapy (non-Recur/Ext causes of death), which would include death from second malignancy, cardiac and pulmonary conditions. Worsening late mortality for 5-year survivors of neuroblastoma and Ewing's sarcoma may be due to improved use of salvage therapies that delay, but do not ultimately prevent death. [Table: see text] No significant financial relationships to disclose.
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Srivastava D, Srivastava B, Tripathi T. Surgical correction of mandibular malformations by distraction osteogenesis. Int J Oral Maxillofac Surg 2007. [DOI: 10.1016/j.ijom.2007.08.159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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