1,720,960 research outputs found
Structural and ultrastructural comparison of photophores of two species of deep-sea fishes: Argyropelecus hemigymnus and Maurolicus muelleri
No full textThe structure of the photophores (luminous organs) of two species of deep-sea fishes from the
Strait of Messina, Argyropelecus hemigymnus and Maurolicus muelleri, was examined. Although
significant structural differences were identified between species, especially in photophore organization
and distribution, ultrastructural comparisons indicated a marked similarity between them.
The photocytes exhibited numerous secretory granules, of different electron density, embedded in
an extremely developed rough endoplasmic reticulum. Numerous mitochondria were observed
among the secretory granules. The lens appeared to be composed of tightly contiguous polyhedral
cells. The reflector was made up of cells rich in guanine crystals embedded in an amorphous
matrix and appeared to be surrounded by a layer of connective tissue full of melanocytes.
Ventrally, every photophore was delimited by a thick cellular layer called the ‘gelatinous layer’
with dioptric properties. The results confirm that even though A. hemigymnus and M. muelleri
differ widely phylogenetically, they exhibit adaptive convergence, involving similar morphology
and physiology in these luminous structures
Glycoconjugate histochemistry of bovine Brunner glands
No full textThe principal aims of this study have been
to elucidate the nature of glycoconjugates produced
by the two distinct parts of bovine Brunner glands, peripheral
and central areas of lobules, and to investigate
the presence of sialyl acid residues. Bovine duodenal tissues,
embedded in paraffin wax, were investigated by
means of both conventional histochemical methods (PAS,
AB, HID) and biotinylated lectins (Con A, DBA, SBA,
GS-I-B4, PNA, sWGA, GS-II, UEA-I, LPA, LFA). Conventional
histochemical methods allowed us to accurately
define two different areas: a central and a peripheral
area. The central area, composed of secretory tubular
tracts and the excretory duct, contained neutral glycoconjugates.
The peripheral area was formed by both terminal
alveolar and tubular secretory tracts and contained both
neutral and acidic glycoconjugates, the latter partly
carboxylated and partly sulfated. Lectin histochemistry
confirmed differences highlighted by conventional histochemical
methods and allowed us to characterise glycoprotein
profiles of the preterminal and terminal tracts.
The preterminal tracts and the excretory duct contained
glycoconjugates with terminal D-Gal ]3(1-3)GalNAc,
a-D-Gal, a/[3-D-GalNAc, a/[3-D-GlcNAc, and internal
[3(1-4) D-GlcNAc and a-Man residues. The terminal
tracts were characterised by terminal a-L fucose,
[3-D-GalNac, a/[3D-GlcNAc, a-D-Gal, a-D-GalNAc, and
sialic acid residues. Internal [3(1-4) D-GlcNAc and
a-Man residues were also identified. Finally, secretion of
bovine Brunner glands is characterised by both O-linked
and N-linked glycoproteins: cells located in the preterminal
tracts and in the excretory duct produce mainly
O-linked glycoproteins while cells located in the terminal
tracts produce N-linked glycoproteins
Density and pattern of dopamine D2-like receptors in the cerebellar cortex of aged rats.
No full textThe pharmacological properties and the anatomical localization of dopamine (DA) D2-like receptors were studied in the cerebellum of 3 months, 12 months, and 24 months male Wistar rats using combined radioligand binding and autoradiographic techniques with [3H]-spiroperidol as a ligand. The binding was consistent with the labelling of the DA D3 receptor subtype. The affinity for DA D2-like receptors was similar in the cerebellar cortex of the three animal groups investigated, whereas the density of binding sites (Bmax value) assessed using conventional radioligand binding techniques was reduced as a function of aging. Light microscope autoradiography revealed the localization of binding sites primarily in the molecular layer and to a lesser amount in Purkinje neurons layer. A loss of binding sites was noticeable with aging in the grey matter of the cerebellar cortex. It affected primarily the molecular layer. Analysis of radioligand binding data and light microscope autoradiography suggests that age-related changes of DA D2-like receptors depend in part by structural alterations of cerebellar cortex and in part by modifications in receptor expression
Natural sesquiterpenes as potential modulator of intracellular pathways in CCA proliferation
No full textMany natural compounds are able to control apoptotic signaling pathways particularly by modulating the NFkB and STAT3 cascades. The natural sesquiterpenes β-caryophyllene (CRY) and beta-caryophyllene oxide (CRYO) exhibited in vitro chemosensitizing properties in different human cancer cell lines, among which liver cancer cells. Cholangiocarcinoma (CCA), that originates at the level of the intrahepatic or extrahepatic bile ducts,is one the most aggressive type of cancer for its chemotherapy resistance and invasiveness. Increasing efforts are directed to identify new cellular targets for cancer cell survival and metastatization and some alternative approaches. In this context, ourprevious studies highlighted that a combined treatment of low-dose doxorubicin (DOXO) and a nontoxic concentration of CRY(10 μg/mL) and CRYO (10 μg/mL) increased the effectiveness of the anticancer drug. Present study was aimed at identifyingthe possible interference of the combined treatment of low-dose DOXO and CRY or CRYO on the STAT3 activation pathway inCCA cells. To this end, cholangiocytes were exposed to the test substances for 24h and 72h, before to evaluate the apoptosis,through the Annexin V staining, and the nuclear translocation of STAT3, through immunofluorescence. We found that DOXO in association with CRY, but not with CRYO, suppresses the STAT3 activation in CCA cells with a time-dependent effect.Accordingly, an increased apoptosis was found in cholangiocytes treated with DOXO + CRY, compared to DOXO alone. Our results show for the first time that the combination DOXO and CRY is able to modulate the STAT3 pathway and could be considered ablocker of the same signaling cascade
Localisation of dopamine D3 receptor in the rat cerebellar cortex: a light microscope autoradiographic study.
No full textThe pharmacological properties and the anatomical localisation of dopamine D3 receptor were assessed in the rat cerebellar cortex using radioligand binding techniques associated with light microscope autoradiography and 7-[3H]hydroxy-N,N-di-n-propyl-2-aminotetralin (7-[3H]OH-DPAT) as a ligand. 7-[3H]OH-DPAT was specifically bound to sections of rat cerebellar cortex with a dissociation constant (Kd) of 0.5 nM and a maximum density of binding sites (Bmax) of 97 +/- 4 fmol/mg tissue. The rank order of potency of competitors of 7-[3H]OH-DPAT binding and the observation that guanosine triphosphate did not affect radioligand binding suggest the labelling of a dopamine D3 receptor. 7-[3H]OH-DPAT binding sites are located mainly in the molecular layer and in lesser amounts in the Purkinje neuron layer, primarily within the cell body of Purkinje neurons. No specific accumulation of silver grains was observed in the granule neuron layer or in the white matter of the cerebellar cortex. The localisation of a putative dopamine D3 receptor within Purkinje neurons suggests that this site may have functional relevance in the cerebellar cortex
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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