1,721,007 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Cellular and molecular mechanisms underlying erythropoietic response to chronic stress
Get PDFStres je sastavni deo svakodnevnog života. Psihološki stresori pokreću kompleksan odgovor organizma na stres koji utiče na različite fiziološke procese uključujući hematopoezu. Poznato je da se u bazalnim uslovima proces eritrocitopoeze odvija prevashodno u kostnoj srži, dok se u stanjima povećanih potreba organizma za eritrocitopoezom ovaj proces, nazvan stres eritrocitopoeza (SE), aktivira i u slezini. Prema najnovijim saznanjima, neadekvatna regulacija SE može rezultirati prekomernom ekspanzijom i malignom transformacijom nezrelih ćelija crvene krvne loze. Do sada je proces SE ispitivan prevashodno na mišjim modelima anemije dok su literaturni podaci o efektima hroničnog psihološkog stresa na proces eritrocitopoeze veoma oskudni. Cilj ove studije je bio: 1) da se ispita uticaj hroničnog psihološkog stresa na proces eritrocitopoeze u kostnoj srži i slezini, i 2) da se istraže ćelijski i molekularni mehanizmi regulacije ispitivanog procesa. U tu svrhu su korišćeni odrasli mužjaci miševa visokorodnih sojeva CBA i C57/BL6, kao i MIF knockout miševi koji su bili podvrgnuti restraint stresu 7 ili 14 dana uzastopno, u trajanju od 2 sata dnevno. Za detekciju progenitorskih ćelija eritrocitne loze primenjen je metod kultivacije hematopoetskih ćelija na podlozi od metilceluloze obogaćene odgovarajućim citokinima. Metodama protočne citofluorometrije i imunohistohemije izvršena je detekcija i kvantifikacija eritroblasta u ispitivanim uzorcima kostne srži i slezine. Ekspresija ciljnih proteina je analizirana primenom Western blot-a i imunohistohemije dok je relativna ekspresija ispitivanih gena određena metodom Real-Тime PCR. Naši rezultati su pokazali da hronični psihološki stres redukuje koncentraciju gvožđa i hemoglobina u krvi, i da dovodi do stimulacije eritrocitopoeze u kostnoj srži i slezini miša. Inhibicija sinteze azot monoksida u potpunosti je sprečila stimulišući efekat hroničnog stresa na progenitorske ćelije crvene krvne loze u kostnoj srži, ukazujući prvi put da ovaj signalni molekul ima značajnu ulogu u ekspanziji eritroidnih progenitora tokom hroničnog psihološkog stresa. Pored povećanog broja
progenitorskih ćelija, u slezini hronično stresiranih životinja smo detektovali i znatno veći procenat eritroblasta što ukazuje da hronični psihološki stres ima izraženiji efekat na ekstramedularnu eritrocitopoezu...Stress has become an important aspect of daily life. Exposure to a psychological stressor initiates an integrated response that affects different physiological processes including hematopoiesis. The majority of steady-state erythropoiesis occurs in the bone marrow. However, recent studies have shown that the adult spleen serves as the main site of red blood cell production under different stress conditions, collectively referred to as stress erythropoiesis (SE). Furthermore, emerging evidence suggests that inappropriate activation of SE may predispose to leukemic transformation. Much of what we know about SE comes from the analysis of murine models of anemia, but the erythropoietic effects of chronic psychological stress remain largely unknown. The aim of the current study was to examine the influence of chronic psychological stress on erythropoiesis in adult bone marrow and spleen, as well as to investigate cellular and molecular mechanisms underlying the observed effects. For this purpose, adult male CBA and C57BL/6 mice were subjected to 2 hrs. daily restraint stress for 7 or 14 consecutive days. In addition, we used macrophage migration inhibitory factor (MIF)-knockout mice on a C57BL/6 background to examine whether MIF is involved in the control of stress-induced erythropoiesis. The number of erythroid progenitors was determined using colony assays, whereas CD71/Ter119 profiles of bone marrow and splenic cells were analyzed by flow cytometry. The expression of target proteins were assessed by Western blot and immunohistochemistry, while gene expression analysis was performed using real-time PCR. Our results showed that chronic exposure to restraint stress decreased the concentration of iron and hemoglobin in the blood, and resulted in markedly increased number of erythroid progenitors in murine bone marrow and spleen. Blockade of nitric oxide synthesis completely abolished the stimulatory effect of chronic restraint stress on erytrhoid progenitors in the bone marrow, suggesting a role of nitric oxide in stress-induced erythroid cell growth. Although repeated restraint stress initiated an erythroid
stress response in both bone marrow and spleen, the effects on growth and maturation of erythroid cells were more prominent in the spleen, showing that chronic psychological stress stimulates mainly extramedullary erythropoiesis..
The significance of platelet-leukocyte interactions for the development of thromboembolic complications in patients with Philadelphia-negative myeloproliferative neoplasms
Get PDFUVOD: Tromboza često komplikuje klinički tok Filadelfija negativnih
mijeloproliferativnih neoplazmi (Ph-MPN) i predstavlja glavni uzrok morbiditeta i
mortaliteta u ovim bolestima. Patofiziologija tromboze u Ph-MPN je složena i još uvek
nije potpuno razjašnjena. Iako su poremećaji broja i funkcije trombocita dugo smatrani
glavnim uzročnicima trombofilnog stanja u Ph-MPN, sada se sve veća pažnja posvećuje
ispitivanju dinamičkih interakcija između aktiviranih trombocita, leukocita i endotela.
Značaj određivanja broja leukocitno-trombocitnih(Le-Tr) agregata, kao pokazatelja
intravaskularne aktivacije leukocita i trombocita, za procenu rizika od pojave
trombotičnih komplikacija kod bolesnika sa Ph-MPN do sada je ispitivan samo u
retrospektivnim studijama.
CILJ ove prospektivne studije je bio da ispita prediktivnu vrednost cirkulišućih
neutrofilno-trombocitnih (Neu-Tr) i monocitno-trombocitnih (Mo-Tr) agregata i
solubilnih E-, L- i P- selektina za nastanak tromboembolijskih (TE) događaja kod
bolesnika sa Ph-MPN.
MATERIJAL I METODE: U studiju je uključeno 95 konsekutivnih bolesnika sa de
novo Ph-MPN: 39 sa policitemijom verom (PV), 27 sa esencijalnom trombocitemijom
(ET) i 29 sa primarnom mijelofibrozom (PMF), kod kojih je dijagnoza bolesti
postavljena prema kriterijumima Svetske zdravstvene organizacije. Kontrolnu grupu su
činila 33 zdrava volontera. Sve analize su rađene nakon dijagnoze, a pre početka
antiagregatorne ili citoreduktivne terapije. Prisustvo Le-Tr agregata je ispitivano u
uzorcima periferne krvi metodom multiparametarske protočne citometrije (BD
FACSCalibur 4FC). Nivo Le-Tr agregata je izražavan kao procenat CD42b+CD61+
neutrofila, odnosno monocita. Koncentracija solubilnih selektina u plazmi je određivana
enzimskim imunoesejem. Sve arterijske i venske tromboze, izuzev mikrocirkulatornih
poremećaja, su evidentirane tokom perioda praćenja od 3.25 godina nakon dijagnoze.
REZULTATI: Tokom perioda praćenja TE komplikacije je dobilo 12.6% bolesnika sa
Ph-MPN (arterijske 9.4%, venske 3.2%), sa prosečnim vremenom do događaja od 39
meseci. Incidenca trombotičnih događaja u celoj grupi bolesnika sa Ph-MPN tokom
perioda praćenja je iznosila 4.36 na 100 bolesničkih godina...BACKGROUND: Thrombosis often complicates the clinical course of Philadelphia
negative myeloproliferative neoplasms (Ph-MPN) and is a major cause of morbidity and
mortality in these diseases. The pathophysiology of thrombosis in patients (pts) with Ph-
MPN is complex and still not fully understood.Inappropriate activation of leukocytes,
platelets and endothelial cells, with their mutual interaction represents an important
mechanism of thrombosis tendency in thesediseases. The importance of determining the
number of leukocyte-platelet (Le-Plt) aggregates as indicators of intravascular
activation of leukocytes and platelets, for assessing the risk of thrombotic complications
in pts with Ph-MPN has so far tested only in retrospective studies.
The AIM of our prospectivestudy was to investigate the predictive value of circulating
neutrophyle-platelet(Neu-Plt) and monocyte-platelet(Mo-Plt)aggregates as well as
soluble selectins for occurence of thromboembolic (TE) events in pts with Ph-MPN.
METHODS: The study included 95 consecutive pts withde novoPh-MPN (39
polycythemia vera, 27 essential thrombocythemia, and 29 primary
myelofibrosis),diagnosed according to WHO criteria. Control group consisted of 33
healthy volonters. All analysis were performed after diagnosis, and before the start of
antiplatelet or cytoreductive therapy. Flow cytometric analysis of Le-Plt aggregateswas
performed on whole blood samples anticoagulated with EDTA/CTAD. Le-plt
aggregates were estimated as a fraction (%) of CD42b+CD61+ neutrophyles and
monocytes. The plasma levels of E-, L-, and P-selectins were determinedby enzyme
immunoassay. All arterial and venous thrombotic events, except microcirculatory
disturbances, were recorded during mean follow-up period of about 3.25 years after
diagnosis.
RESULTS: During the follow-up TE complications occurred in 12.6% Ph-MPN pts
(arterial in 9.4%, venous in 3.2%), with mean time to TE event of 39 months..
Cellular and molecular mechanisms underlying erythropoietic response to chronic stress
No full textStres je sastavni deo svakodnevnog života. Psihološki stresori pokreću kompleksan odgovor organizma na stres koji utiče na različite fiziološke procese uključujući hematopoezu. Poznato je da se u bazalnim uslovima proces eritrocitopoeze odvija prevashodno u kostnoj srži, dok se u stanjima povećanih potreba organizma za eritrocitopoezom ovaj proces, nazvan stres eritrocitopoeza (SE), aktivira i u slezini. Prema najnovijim saznanjima, neadekvatna regulacija SE može rezultirati prekomernom ekspanzijom i malignom transformacijom nezrelih ćelija crvene krvne loze. Do sada je proces SE ispitivan prevashodno na mišjim modelima anemije dok su literaturni podaci o efektima hroničnog psihološkog stresa na proces eritrocitopoeze veoma oskudni. Cilj ove studije je bio: 1) da se ispita uticaj hroničnog psihološkog stresa na proces eritrocitopoeze u kostnoj srži i slezini, i 2) da se istraže ćelijski i molekularni mehanizmi regulacije ispitivanog procesa. U tu svrhu su korišćeni odrasli mužjaci miševa visokorodnih sojeva CBA i C57/BL6, kao i MIF knockout miševi koji su bili podvrgnuti restraint stresu 7 ili 14 dana uzastopno, u trajanju od 2 sata dnevno. Za detekciju progenitorskih ćelija eritrocitne loze primenjen je metod kultivacije hematopoetskih ćelija na podlozi od metilceluloze obogaćene odgovarajućim citokinima. Metodama protočne citofluorometrije i imunohistohemije izvršena je detekcija i kvantifikacija eritroblasta u ispitivanim uzorcima kostne srži i slezine. Ekspresija ciljnih proteina je analizirana primenom Western blot-a i imunohistohemije dok je relativna ekspresija ispitivanih gena određena metodom Real-Тime PCR. Naši rezultati su pokazali da hronični psihološki stres redukuje koncentraciju gvožđa i hemoglobina u krvi, i da dovodi do stimulacije eritrocitopoeze u kostnoj srži i slezini miša. Inhibicija sinteze azot monoksida u potpunosti je sprečila stimulišući efekat hroničnog stresa na progenitorske ćelije crvene krvne loze u kostnoj srži, ukazujući prvi put da ovaj signalni molekul ima značajnu ulogu u ekspanziji eritroidnih progenitora tokom hroničnog psihološkog stresa. Pored povećanog broja
progenitorskih ćelija, u slezini hronično stresiranih životinja smo detektovali i znatno veći procenat eritroblasta što ukazuje da hronični psihološki stres ima izraženiji efekat na ekstramedularnu eritrocitopoezu...Stress has become an important aspect of daily life. Exposure to a psychological stressor initiates an integrated response that affects different physiological processes including hematopoiesis. The majority of steady-state erythropoiesis occurs in the bone marrow. However, recent studies have shown that the adult spleen serves as the main site of red blood cell production under different stress conditions, collectively referred to as stress erythropoiesis (SE). Furthermore, emerging evidence suggests that inappropriate activation of SE may predispose to leukemic transformation. Much of what we know about SE comes from the analysis of murine models of anemia, but the erythropoietic effects of chronic psychological stress remain largely unknown. The aim of the current study was to examine the influence of chronic psychological stress on erythropoiesis in adult bone marrow and spleen, as well as to investigate cellular and molecular mechanisms underlying the observed effects. For this purpose, adult male CBA and C57BL/6 mice were subjected to 2 hrs. daily restraint stress for 7 or 14 consecutive days. In addition, we used macrophage migration inhibitory factor (MIF)-knockout mice on a C57BL/6 background to examine whether MIF is involved in the control of stress-induced erythropoiesis. The number of erythroid progenitors was determined using colony assays, whereas CD71/Ter119 profiles of bone marrow and splenic cells were analyzed by flow cytometry. The expression of target proteins were assessed by Western blot and immunohistochemistry, while gene expression analysis was performed using real-time PCR. Our results showed that chronic exposure to restraint stress decreased the concentration of iron and hemoglobin in the blood, and resulted in markedly increased number of erythroid progenitors in murine bone marrow and spleen. Blockade of nitric oxide synthesis completely abolished the stimulatory effect of chronic restraint stress on erytrhoid progenitors in the bone marrow, suggesting a role of nitric oxide in stress-induced erythroid cell growth. Although repeated restraint stress initiated an erythroid
stress response in both bone marrow and spleen, the effects on growth and maturation of erythroid cells were more prominent in the spleen, showing that chronic psychological stress stimulates mainly extramedullary erythropoiesis..
Ćelijski i molekularni mehanizmi regulacije eritrocitopoeze u uslovima hroničnog stresa
Get PDFStress has become an important aspect of daily life. Exposure to a psychological stressor initiates an integrated response that affects different physiological processes including hematopoiesis. The majority of steady-state erythropoiesis occurs in the bone marrow. However, recent studies have shown that the adult spleen serves as the main site of red blood cell production under different stress conditions, collectively referred to as stress erythropoiesis (SE). Furthermore, emerging evidence suggests that inappropriate activation of SE may predispose to leukemic transformation. Much of what we know about SE comes from the analysis of murine models of anemia, but the erythropoietic effects of chronic psychological stress remain largely unknown. The aim of the current study was to examine the influence of chronic psychological stress on erythropoiesis in adult bone marrow and spleen, as well as to investigate cellular and molecular mechanisms underlying the observed effects. For this purpose, adult male CBA and C57BL/6 mice were subjected to 2 hrs. daily restraint stress for 7 or 14 consecutive days. In addition, we used macrophage migration inhibitory factor (MIF)-knockout mice on a C57BL/6 background to examine whether MIF is involved in the control of stress-induced erythropoiesis. The number of erythroid progenitors was determined using colony assays, whereas CD71/Ter119 profiles of bone marrow and splenic cells were analyzed by flow cytometry. The expression of target proteins were assessed by Western blot and immunohistochemistry, while gene expression analysis was performed using real-time PCR. Our results showed that chronic exposure to restraint stress decreased the concentration of iron and hemoglobin in the blood, and resulted in markedly increased number of erythroid progenitors in murine bone marrow and spleen. Blockade of nitric oxide synthesis completely abolished the stimulatory effect of chronic restraint stress on erytrhoid progenitors in the bone marrow, suggesting a role of nitric oxide in stress-induced erythroid cell growth. Although repeated restraint stress initiated an erythroid stress response in both bone marrow and spleen, the effects on growth and maturation of erythroid cells were more prominent in the spleen, showing that chronic psychological stress stimulates mainly extramedullary erythropoiesis...Stres je sastavni deo svakodnevnog života. Psihološki stresori pokreću kompleksan odgovor organizma na stres koji utiče na različite fiziološke procese uključujući hematopoezu. Poznato je da se u bazalnim uslovima proces eritrocitopoeze odvija prevashodno u kostnoj srži, dok se u stanjima povećanih potreba organizma za eritrocitopoezom ovaj proces, nazvan stres eritrocitopoeza (SE), aktivira i u slezini. Prema najnovijim saznanjima, neadekvatna regulacija SE može rezultirati prekomernom ekspanzijom i malignom transformacijom nezrelih ćelija crvene krvne loze. Do sada je proces SE ispitivan prevashodno na mišjim modelima anemije dok su literaturni podaci o efektima hroničnog psihološkog stresa na proces eritrocitopoeze veoma oskudni. Cilj ove studije je bio: 1) da se ispita uticaj hroničnog psihološkog stresa na proces eritrocitopoeze u kostnoj srži i slezini, i 2) da se istraže ćelijski i molekularni mehanizmi regulacije ispitivanog procesa. U tu svrhu su korišćeni odrasli mužjaci miševa visokorodnih sojeva CBA i C57/BL6, kao i MIF knockout miševi koji su bili podvrgnuti restraint stresu 7 ili 14 dana uzastopno, u trajanju od 2 sata dnevno. Za detekciju progenitorskih ćelija eritrocitne loze primenjen je metod kultivacije hematopoetskih ćelija na podlozi od metilceluloze obogaćene odgovarajućim citokinima. Metodama protočne citofluorometrije i imunohistohemije izvršena je detekcija i kvantifikacija eritroblasta u ispitivanim uzorcima kostne srži i slezine. Ekspresija ciljnih proteina je analizirana primenom Western blot-a i imunohistohemije dok je relativna ekspresija ispitivanih gena određena metodom Real-Тime PCR. Naši rezultati su pokazali da hronični psihološki stres redukuje koncentraciju gvožđa i hemoglobina u krvi, i da dovodi do stimulacije eritrocitopoeze u kostnoj srži i slezini miša. Inhibicija sinteze azot monoksida u potpunosti je sprečila stimulišući efekat hroničnog stresa na progenitorske ćelije crvene krvne loze u kostnoj srži, ukazujući prvi put da ovaj signalni molekul ima značajnu ulogu u ekspanziji eritroidnih progenitora tokom hroničnog psihološkog stresa. Pored povećanog broja progenitorskih ćelija, u slezini hronično stresiranih životinja smo detektovali i znatno veći procenat eritroblasta što ukazuje da hronični psihološki stres ima izraženiji efekat na ekstramedularnu eritrocitopoezu..
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