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Interim analysis of serum placental growth factor values for use in pre-eclampsia screening. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2024; 63:701-702. [PMID: 38147437 DOI: 10.1002/uog.27570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 12/12/2023] [Accepted: 12/19/2023] [Indexed: 12/28/2023]
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PO-0828: Molecular Dynamics of Ebstein Barr Virus in Nasopharyngeal Carcinoma from a Non-Endemic area. Radiother Oncol 2020. [DOI: 10.1016/s0167-8140(21)00845-8] [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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Remote monitoring of blood pressure to reduce the risk of preeclampsia related complications with an innovative use of mobile technology. Pregnancy Hypertens 2016; 6:263-265. [PMID: 27939464 DOI: 10.1016/j.preghy.2016.04.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/18/2016] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Assess suitability of remote self-monitoring of blood pressure with an innovative use of technology in detecting raised blood pressure in pregnancy. STUDY DESIGN Assess ease of use and safety of the newly developed kit which included a Bluetooth enabled blood pressure machine and an android based mobile phone. The phone was modified to have only one application in it which showed the blood pressure readings with a traffic light system. The study was a proof of concept for wider use of the kit. We provided 50 women who were admitted with the kit. We assessed ease of use of the blood pressure machine and accuracy of readings including remote transfer to a computer. MAIN OUTCOME MEASURE Technological feasibility and acceptance by women. RESULTS The technology provides accurate data and visual cues including safe remote transfer instantaneously. 90% of the women agreed that the Kit was simple to use and 78% would prefer this model of testing at home. CONCLUSION In a relatively resource rich setting the machine can reduce the number of patient visits for women who are at risk for preeclampsia. In resource poor settings it helps to triage resources to women who need it the most. It also is a valuable tool for research. Studies of the Kit in both developed and developing world will be needed to show reduction in perinatal and maternal morbidity or mortality secondary to preeclampsia.
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Dilemmas in thromboprophylaxis in neurological conditions in pregnancy. MINERVA GINECOLOGICA 2015; 67:95-96. [PMID: 25660432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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A systematic review and meta-regression analysis of aggression during the first episode of psychosis. Acta Psychiatr Scand 2013; 128:413-21. [PMID: 23521361 DOI: 10.1111/acps.12113] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/06/2013] [Indexed: 01/13/2023]
Abstract
OBJECTIVE The First Episode of Psychosis (FEP) represents a period of heightened risk for aggression. However, it is not known whether this risk is significantly altered following contact with mental health services. METHOD Meta-analytic methods were used to estimate pooled prevalence of 'any' and 'serious' aggression during FEP, while meta-regression analyses were conducted to explore reasons for heterogeneity between studies. RESULTS Fifteen studies comprising 3, 294 FEP subjects were analysed. Pooled prevalence of 'any aggression' before service contact was 28% (95% CI: 22-34) and following contact 31% (95% CI: 20-42). Pooled prevalence of 'serious aggression' was 16% (95% CI: 11-20) before service contact and 13% (95% CI: 6-20) following contact. Four studies reporting repeated assessments within the same cohort revealed that aggression rates did not significantly differ post and pre service contact: Odds Ratios for any aggression: 1.18 (95% CI: 0.46-2.99) and serious aggression: 0.61 (95% CI: 0.31-1.21). CONCLUSION Rates of aggression are high during FEP, both before and following initial service contact, and seem not to alter following contact. This conclusion remains tentative due to considerable heterogeneity between studies and a lack of prospective cohort studies.
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Abstract
Measurements of the concentrations of 20 fission products in a sample of rain collected at Fayetteville, Arkansas, on 26 October 1964, yielded two "mass-yield" curves; one for fresh debris from the Chinese nuclear explosion, and another for older debris. The former curve resembled the mass-yield curve for neutron-induced fission of uranium-235.
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Evidence for a major meteorite impact on the Earth 34 million years ago: implication for eocene extinctions. Science 2010; 216:885-6. [PMID: 17819179 DOI: 10.1126/science.216.4548.885] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A deep-sea core from the Caribbean contains a layer of sediment highly enriched in meteoritic iridium. This layer underlies a layer of North American microtektites dated at 34.4 million years ago and coincides with the extinction of five major species of Radiolaria. It is suggested that a massive, chemically undifferentiated meteorite collided with the earth, producing the tektites and leading to extinctions 34 million years ago.
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A major meteorite impact on the Earth 65 million years ago: evidence from the cretaceous-tertiary boundary clay. Science 2010; 209:921-3. [PMID: 17810987 DOI: 10.1126/science.209.4459.921] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Evidence for a major meteorite impact on the earth 65 million years ago is shown by the presence of meteoritic debris in the "fish clay" from Denmark representing the Cretaceous-Tertiary boundary. Noble metals (iridium, osmium, gold, platinum, rhenium, ruthenium, palladium, nickel, and cobalt), which are sensitive indicators of meteorites and are normally depleted on the terrestrial surface by factors of 10(4) to 10(2) relative to cosmic abundances, are enriched in this boundary clay by factors of 5 to 100 over the expected abundances. With the exception of rhenium, all the enriched noble metals in the clay are present in cosmic proportions, indicating that the impacting celestial body had not undergone gross chemical differentiation. The major extinction of life on the earth at the end of the Cretaceous Period may be related to the meteorite impact.
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Abstract
The aim of the study was to evaluate secondary repair of the perineum following perineal trauma at childbirth. Patients who underwent secondary repair reported with symptoms of superficial dyspareunia, vulvo-vaginal pain, vaginal stenosis and broken or gaping wound. The study included 103 women over a 16-year period that underwent refashioning of the perineum at Northwick Park Hospital by the same surgeon. Among the cases, 81.6% were nulliparous and 18.4% were multiparous. Labour was induced in 30.1%, and 38% of the women required instrumental delivery. The length of the second stage of labour was 89 +/- 60 min for nulliparae and 50 +/- 48 min for multiparae. In 53.4% of the women, an episiotomy was performed. Catgut sutures were used in 69% of primary repairs. Predisposing factors for the need for secondary repair included nulliparity, forceps delivery, episiotomy, prolonged second stage of labour, surgeons' inexperience and the choice of suture material. Secondary repair is associated with a good result. A majority of women who required refashioning of the perineum for superficial dyspareunia presented late after the onset of the problem. In carefully selected women, such cases of superficial dyspareunia are easily treatable and surgery needs to be considered as an option.
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Abstract
BACKGROUND Heparin can significantly reduce pregnancy complications in women with certain thrombophilias, such as antiphospholipid syndrome. Recent reports suggest that heparin may act by mechanisms other than anticoagulation. However, the effect of heparin on trophoblast biology in the absence of thrombophilia has not been extensively investigated. Therefore, this study aimed to evaluate trophoblast invasion, using an established cell line and primary extravillous trophoblasts (EVTs), following exposure to heparin and fractionated heparin. METHODS An EVT cell line (SGHPL-4) was used to study invasion in the presence of hepatocyte growth factor (HGF) and varying concentrations of fractionated and unfractionated heparin. These experiments were repeated using first trimester primary EVTs. RESULTS Both forms of heparin significantly reduced HGF-induced invasion in the SGHPL-4 cell line. This suppression of invasion appeared to be dose-dependent for fractionated heparin. In primary EVT cells, fractionated heparin also demonstrated significant suppression of invasion. CONCLUSIONS Heparin has the potential to reduce trophoblast invasion in cell lines and first trimester EVT cells. This article highlights the need for further evaluation of these medications in vitro and in vivo, especially when used in the absence of thrombophilic disorders.
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Structure of mesh phases in a cationic surfactant system with strongly bound counterions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:3606-14. [PMID: 17319705 DOI: 10.1021/la0631466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We report the observation of an intermediate mesh phase with rhombohedral symmetry, corresponding to the space group Rm, in a mixed surfactant system formed by the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the organic salt 3-sodium-2-hydroxy naphthoate (SHN). It occurs between a random mesh phase (L(alpha)(D)) and a lamellar phase (L(alpha)) at low temperatures; at higher temperatures, the (L(alpha)(D)) phase transforms continuously into the (L(alpha)) phase with an increasing surfactant concentration (phi(s)). To separate the effects of salt and phi(s) on the phase behavior, the ternary system consisting of cetyltrimethylammonium 3-hydroxy-naphthalene-2-carboxylate (CTAHN), sodium bromide (NaBr), and water was studied. The intermediate mesh phase is found in this system at high NaBr concentrations. The micellar aggregates, both in the intermediate and random mesh phases, are found to be made up of a two-dimensional network of rod-like segments, with three rods meeting at each node. The average mesh size increases with phi(s), and the transition from the random mesh phase to the intermediate phase is found to occur when it is approximately 1.5 times the lamellar periodicity. The intermediate mesh phase is absent in the equimolar dodecyltrimethylammonium bromide (DTAB)-SHN system, indicating the role of the surfactant chain length in the formation of this phase. This system exhibits a random mesh phase over a very wide range of water content, with the average mesh size decreasing upon an increasing phi(s), contrary to the trend seen in the CTAB-SHN system.
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Intussusception: a rare cause of abdominal pain in pregnancy. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2006; 28:723-5. [PMID: 16958024 DOI: 10.1002/uog.3810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
A 34-year-old woman presented at 19 weeks in her third pregnancy with abdominal pain and hyperemesis. This was her third admission during the pregnancy for similar complaints. A few days after admission an exacerbation in her pain was noted, in particular on eating or lying down, and a firm and mobile epigastric mass could be palpated separate from her uterus. The differential diagnosis was a hernia or a degenerating pedunculated fibroid. Sonography revealed a mass separate from the uterus with an appearance consistent with intussusception. Magnetic resonance imaging confirmed the diagnosis. A limited right hemicolectomy was performed. The final diagnosis was adenocarcinoma of the colon. It is difficult to diagnose intussusception during pregnancy. The presenting symptoms of nausea, vomiting, abdominal pain and constipation are common in pregnancy and the displacement of the bowel by the gravid uterus hampers examination. Intussusception is very rare in adults and generally it is associated with tumors. Preoperative diagnosis is difficult but possible with accurate imaging.
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Anti-proliferative effects of sorafenib in clear cell renal cell carcinoma (CCRCC) cell lines: Relationship to von Hippel Lindau protein (pVHL) expression and hypoxia. J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.4601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
4601 Background: Sorafenib, a multikinase inhibitor targeting raf kinase and several receptor tyrosine kinases including VEGFR-2 and PDGFR, has demonstrated clinical activity in the treatment of metastatic CCRCC. To further characterize the molecular basis of response to this agent, we tested the functional role of pVHL and hypoxia in the anti-tumor activity of sorafenib in a panel of CCRCC cell lines. Methods: CCRCC cell lines CAKI-1 (wild-type pVHL), CAKI-2 (mutant VHL) and the isogenic pair, 786–0-neo (vector control) and 786–0-VHL (pVHL expressing) cells were treated with sorafenib (2.5 - 20 μM) for 24 - 96 hours at 37°C in a atmosphere of either normoxia (21% oxygen) or hypoxia (1% oxygen), 5% carbon dioxide and remainder nitrogen. Gene expression analysis of control and sorafenib treated CCRCC cell lines was carried out using a custom cancer cDNA array containing probes to 9240 cDNA clones corresponding to 4900 Unigenes or unclustered ESTs relevant to cancer or kidney development. Results: Anti-proliferative effects of sorafenib were both concentration and time of treatment dependent; the IC50 of sorafenib (inhibitory concentration for 50% cell kill) ranged from 7.5-10 μM and required continuous treatment for at least 48-72 hours for maximal cell kill. In contrast to CAKI-2 and 786–0-neo cells harboring mutant VHL, both CAKI-1 and 786–0-VHL cells expressing wild type VHL were ∼2-fold more resistant to the anti-proliferative effects of sorfaenib when treated under hypoxic conditions. No difference in resistance was observed under normoxic conditions. In contrast to 786–0-neo cells, there were ∼40 genes overexpressed (>5-fold) under hypoxia in control 786–0-VHL cells, that were predominantly related to anti-apoptosis (e.g. bcl2-associated athanogene) or angiogenesis (e.g. PDGF beta). Bcl2-associated athanogene and PDGF beta were down regulated >2-fold in hypoxia with sorafenib treatment. Conclusions: CCRCC with wild type VHL under hypoxic conditions can promote overexpression of anti-apoptotic and angiogenesis genes that attenuate the anti-proliferative effects of sorafenib. pVHL and hypoxia related genes may be important biomarkers for assessing the clinical efficacy of sorafenib in CCRCC. [Table: see text]
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Effect of first-trimester serum from pregnant women with high-resistance uterine artery Doppler resistance on extravillous trophoblast invasion. Hum Reprod 2006; 21:1295-8. [PMID: 16431899 DOI: 10.1093/humrep/dei482] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Abnormal uterine artery Doppler indices are associated with pregnancy complications such as pre-eclampsia and intrauterine growth restriction. Poor trophoblast invasion may be a consequence of, or be associated with, abnormal Doppler indices. OBJECTIVE To evaluate in vitro trophoblast function following exposure to first-trimester serum from pregnancies with high uterine artery Doppler resistance indices. METHODS Doppler ultrasound examination of the maternal uterine arteries was performed on women at 10-14 weeks' gestation. Serum was collected from women with bilateral uterine artery notches with resistance indices above the 95th centile and from patients with normal uterine artery indices. The effect of serum on trophoblast invasion was determined using an established in vitro model from the extravillous trophoblast-derived cell line SGHPL-4. RESULTS Trophoblastic invasion was significantly reduced when treated with serum from women with high-resistance compared with normal-resistance uterine artery Doppler indices (P < 0.05). CONCLUSION Maternal serum in the first trimester of pregnancy from patients with high-resistance uterine artery Doppler indices appears to inhibit trophoblast invasion. This experimental model allows further investigation of factors responsible and the evaluation of therapeutic strategies.
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Neonatal outcome of antenatally diagnosed congenital cystic adenomatoid malformations. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2005; 26:150-3. [PMID: 16038013 DOI: 10.1002/uog.1920] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
OBJECTIVE To investigate the natural history and outcome of antenatally diagnosed congenital cystic adenomatoid malformation (CCAM) of the lung. METHODS This was a retrospective study of all cases of fetal CCAM of the lung diagnosed antenatally. All cases were referred to a tertiary center for further management. A computer search identified all referred cases, and the records of these patients were examined to determine the pregnancy outcome. RESULTS In a 4-year period, 34 cases of fetal CCAM were referred for further management. At presentation, all the cases were noted to be unilateral CCAMs and the majority (79%) were microcystic in nature. The CCAMs were complicated by varying degrees of mediastinal shift (79%) and hydrops fetalis (18%). During the course of the pregnancy, the lung lesion was seen to reduce in size or resolve spontaneously in 76% of cases without any prenatal intervention (including resolution of hydrops in three cases). The overall survival rate into infancy was 88%. One pregnancy was terminated for persisting hydrops fetalis and another resulted in infant death from complications of neonatal cardiac surgery for an associated aortic coarctation. CONCLUSION The outcome of antenatally detected CCAM is much better than previously reported even when complicated by hydrops fetalis at presentation. The latter seems to be related to the high spontaneous regression rate of this tumor. Despite the antenatal resolution of CCAMs on ultrasound, postnatal follow-up is recommended in view of the long-term complications of this malformation.
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Abstract
OBJECTIVE To define the outcome in cases of cystic hygroma diagnosed from a routine obstetric population. METHOD This was a retrospective study of 42 cases of fetal cystic hygroma detected at 11 to 23 weeks' gestation in a routine obstetric population of 25 352 pregnancies. Fetal cystic hygroma was categorized according to position, severity, presence of cardiac defects and Hydrops fetalis. RESULTS There were 20 (47.6%) cases with aneuploidy (9 trisomies and 11 Turner's syndrome). Major congenital cardiac defects were identified in 12 (28.6%) cases. Regression of the hygroma was noted in 2/20 (10%) of the aneuploid pregnancies and 3/17 (17.6%) of the euploid pregnancies. The majority (90.0%) of the aneuploid fetuses were female. In contrast, 70.58% of the fetuses in the euploid group were male and all the surviving normal babies were also male (n = 3). CONCLUSION The findings of this study would support invasive prenatal diagnosis for an ultrasound finding of fetal cystic hygroma. Even in euploid pregnancies with cystic hygroma, there is a high mortality with associated abnormalities. The data also suggest a guarded pregnancy prognosis for the finding of fetal cystic hygroma, and that it is improved with spontaneous resolution, especially in male fetuses of normal karyotype.
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Soliton propagation in an erbium-doped fiber with and without a continuous wave background. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2003; 68:066615. [PMID: 14754344 DOI: 10.1103/physreve.68.066615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2003] [Indexed: 05/24/2023]
Abstract
Considering ultrashort pulse propagation in a nonlinear resonant fiber governed by Hirota-Maxwell Bloch equations, the soliton interaction in an erbium-doped fiber system associated with higher-order dispersion, self-steepening, and self-induced transparency effects is studied for the case when the fiber is driven with and without a constant pumping source. Using auto-Bäcklund-transformation, one- and two-soliton solutions are generated. The significance of the results is discussed in detail.
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Migraine with aura is not linked to the FHM gene CACNA1A or the chromosomal region, 19p13. Neurology 2002; 59:1099-101. [PMID: 12370474 DOI: 10.1212/wnl.59.7.1099] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Two microsatellite markers, tightly linked to CACNA1A, were genotyped in migraine with aura (MA) families to determine if this gene, which underlies the 19p13 linked forms of familial hemiplegic migraine, is also linked to MA. Two-point parametric lod and nonparametric linkage scores did not support linkage. Transmission disequilibrium testing provided no evidence for linkage of MA to CACNA1A. In a large dataset of 64 Canadian MA families, the authors did not find evidence to support an MA susceptibility gene in the region of 19p13.
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Immobilization of papain on cold-plasma functionalized polyethylene and glass surfaces. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 2002; 12:1027-49. [PMID: 11787520 DOI: 10.1163/156856201753252543] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Polyethylene and glass surfaces were functionalized under dichlorosilane-RF-cold-plasma environments and were employed as substrates for further in situ derivatization reactions and immobilization of papain. Surface functionality changes of RF-plasma-exposed surfaces were monitored under 40 kHz continuous discharge environments. The nature and morphology of derivatized substrates and the substrates bearing the immobilized enzyme were analyzed using survey and high resolution ESCA, ATR-FTIR, and fluorescence of chemical derivatization techniques. Spacer molecules intercalated between the substrates and the enzyme significantly increased the enzyme activity (comparable with the that of the free enzyme). Computer-aided conformational modeling of the substrate-spacer systems corroborated with experimental data indicated that an optimal distance might exist between the enzyme and the substrate. The activity of free and immobilized papain was monitored using benzoyl arginine ethyl ester assay. The pH data were recorded every 0.3 s over 25 min. The Michaelis-Menten kinetic constants were evaluated for immobilized enzymes. It was shown, that the immobilized papain retains most of its activity after several washing/assay cycles.
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Immobilization of alpha-chymotrypsin on oxygen-RF-plasma functionalized PET and PP surfaces. JOURNAL OF BIOMATERIALS SCIENCE. POLYMER EDITION 1998; 9:389-404. [PMID: 9586786 DOI: 10.1080/09205063.1998.9753063] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In this contribution the immobilization of alpha-chymotrypsin on plasma activated PET and PP surfaces is investigated. The 'anchoring' C=O groups on polymer surfaces were created under RF-O2-plasma environments. The identity and relative concentrations of plasma-created functionalities were evaluated using survey and high resolution X-ray photoelectron spectroscopy, and differential attenuated total reflectance-FTIR spectroscopy. Surface morphology changes of plasma-exposed substrates were analyzed by atomic force microscopy. Enzyme assays were performed from both virgin and plasma modified samples which underwent the immobilization procedure. It was demonstrated that cold-plasma technique is suitable for generating functional, synthetic polymeric surfaces which can initiate enzyme coupling reactions. It also has been shown that the activity of the immobilized enzyme is lower in comparison to the free enzyme. Reduced conformational mobility resulting from multiple-point coupling process might be responsible for this behavior.
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The Tunguska Explosion of 1908: Discovery of Meteoritic Debris near the Explosion Site and at the South Pole. Science 1983; 220:1158-61. [PMID: 17818499 DOI: 10.1126/science.220.4602.1158] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Submillimeter-sized metallic spheres extracted from soil in the Tunguska region of central Siberia contain noble metals in cosmic proportions. The trace element composition and geographical distribution of these spheres suggest that they are from the 30 June 1908 Tunguska explosion and not meteoritic ablation products falling continuously on the earth. Debris from this explosion was also discovered in a South Pole ice core; this discovery indicates that the Tunguska object exploded in the atmosphere with subsequent stratospheric injection and transport of the debris. The celestial body that exploded over Tunguska weighed more than 7 million tons, was more than 0.16 kilometer in diameter, and may well have been a stony meteorite. This discovery offers a new precision time marker in polar ice strata for the year 1909. The steady-state influx of cosmic matter at the South Pole is estimated to be 1.8 x 10(-8) grams per square centimeter per year, which corresponds to a global influx of 4 x l0(5) tons per year.
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Relationship between an iridium anomaly and the North American microtektite layer in core RC9-58 from the Caribbean Sea. ACTA ACUST UNITED AC 1982. [DOI: 10.1029/jb087is01p0a425] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
An unusual carbon-rich material found in the Abee meteorite is highly enriched in volatile elements, by factors of 10(4) relative to the case for nonvolatile elements. Volatile-rich material of this type might form in the solar nebula toward the end of accretion, when small amounts of residual dust acquire all the uncondensed volatile elements. The mercury enrichment factor of 8500 could explain the paradox of the excess abundance of this element in meteorites.
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Abstract
Although micrometeorites of cometary origin are thought to be the dominant component of interplanetary dust, it has never been possible to positively identify such micrometer-sized particles. Two such particles have been identified as definitely micrometeorites since their abundances of volatile and nonvolatile trace elements closely match those of primitive solar system material.
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Abstract
Silicate spherules produced by atmospheric melting of meteoric bodies are probably the most common form of extraterrestrial material on the earth. It has never been possible to positively identify such particles although it has been known for more than a century that silicate spherules of suspected extraterrestrial origin are present in deep-sea sediments. One such spherule has been identified as definitely extraterrestrial since its abundances of nonvolatile trace elements closely match those of primitive solar system material.
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The simultaneous determination of 20 trace elements in terrestrial, lunar and meteoritic material by radiochemical neutron activation analysis. Anal Chim Acta 1974. [DOI: 10.1016/s0003-2670(01)82944-5] [Citation(s) in RCA: 82] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Several Apollo 16 breccias, including one containing goethite, are strikingly enriched in volatile elements such as bromine, cadmium, germanium, antimony, thallium, and zinc. Similar but smaller enrichments are found in all highland soils. It appears that volcanic processes took place in the lunar highlands, involving the release of volatiles including water. The lunar thallium/uranium ratio is 2 x 10-(4) of the cosmic ratio, which suggests that the moon's original water content could not have exceeded the equivalent of a layer 22 meters deep. The cataclastic anorthosites at the Apollo 16 site may represent deep ejecta from the Nectaris basin.
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Moon: Possible Nature of the Body That Produced the Imbrian Basin, from the Composition of Apollo 14 Samples. Science 1972; 175:55-9. [PMID: 17833980 DOI: 10.1126/science.175.4017.55] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Soils from the Apollo 14 site contain nearly three times as much meteoritic material as soils from the Apollo 11, Apollo 12, and Luna 16 sites. Part of this material consists of the ubiquitous micrometeorite component, of primitive (carbonaceous-chondrite-like) composition. The remainder, seen most conspicuously in coarse glass and norite fragments, has a decidedly fractionated composition, with volatile elements less than one-tenth as abundant as siderophiles. This material seems to be debris of the Cyprus-sized planetesimal that produced the Imbrian basin. Compositionally this planetesimal has no exact counterpart among known meteorite classes, though group IVA irons come close. It also resembles the initial composition of the earth as postulated by the two-component model. Apparently the Imbrian planetesimal was an Earth satellite swept up by the moon during tidal recession or capture, or an asteroid deflected by Mars into terrestrial space.
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Abstract
The glassy coating of lunar rock 12017 is enriched in 15 trace elements relative to the crystalline interior. It apparently consists chiefly of shock-melted rock, somewhat richer in rare earth elements and alkali metals than rock 12017 itself. The glass has been contaminated by about 0.5 percent carbonaceous-chondrite-like material or, alternatively, by a mixture of 0.06 to 0.3 percent fractionated meteoritic material and approximately 10 to 15 percent local soil. The glazing seems to represent molten material splashed from a nearby meteorite impact and not in situ melting by a sudden increase in solar luminosity.
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Abstract
Four core and soil samples from Apollo 12 are enriched in a number of trace elements of meteoritic origin to virtually the same degree as Apollo 11 soil. An average meteoritic influx rate of about 4 x 10(-9) gram per square centimeter per year thus seems to be valid for the entire moon. A sample from a light gray, coarse-grained layer in the core resembles lunar basalts in composition, but is enriched by factors of 10(4) to 10(5) in bismuth and cadmium.
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Trace Elements and Radioactivity in Lunar Rocks: Implications for Meteorite Infall, Solar-Wind Flux, and Formation Conditions of Moon. Science 1970; 167:490-3. [PMID: 17781465 DOI: 10.1126/science.167.3918.490] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Lunar soil and type C breccias are enriched 3-to 100-fold in Ir, Au, Zn, Cd, Ag, Br, Bi, and Tl, relative to type A, B rocks. Smaller enrichments were found for Co, Cu, Ga, Pd, Rb, and Cs. The solar wind at present intensity can account for only 3 percent of this enrichment; an upper limit to the average proton flux during the last 4.5 x 109 years thus is 8 x 10(9) cm(-2) yr(-1). The remaining enrichment seems to be due to a 1.5 to 2 percent admixture of carbonaceous-chondritelike material, corresponding to an average influx rate of meteoritic and cometary matter of 2.9 x 10(-9) g cm(-2) yr(-1) at Tranquility Base. This is about one-quarter the terrestrial rate. Type A, B rocks are depleted 10-to 100-fold in Ag, Au, Zn, Cd, In, Tl, and Bi, relative to terrestrial basalts. This suggests loss by high-temperature volatilization, before or after accretion of the moon. Positron activities due mainly to (22)Na and (26)Al range from 90 to 220 beta(+) min(-1) kg(-1) in five small rocks or fragments (9 to 29 g). The higher activities presumably indicate surface locations. Th and U contents generally agree with those found by the preliminary examination team.
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14.8 MeV Neutron Activation Cross Sections for 181Ta(n, α) 178m,gLu and 178Hf(n,p) 178m,gLu. RADIOCHIM ACTA 1966. [DOI: 10.1524/ract.1966.6.1.26] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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