295 research outputs found
The oxidative damage to the human telomere: effects of 5-hydroxymethyl-2'-deoxyuridine on telomeric G-quadruplex structures
As part of the genome, human telomeric regions can be damaged by the chemically reactive molecules
responsible for oxidative DNA damage. Considering that G-quadruplex structures have been proven to
occur in human telomere regions, several studies have been devoted to investigating the effect of oxidation
products on the properties of these structures. However only investigations concerning the presence
in G-quadruplexes of the main oxidation products of deoxyguanosine and deoxyadenosine have
appeared in the literature. Here, we investigated the effects of 5-hydroxymethyl-2’-deoxyuridine
(5-hmdU), one of the main oxidation products of T, on the physical–chemical properties of the G-quadruplex
structures formed by two human telomeric sequences. Collected calorimetric, circular dichroism
and electrophoretic data suggest that, in contrast to most of the results on other damage, the replacement
of a T with a 5-hmdU results in only negligible effects on structural stability. Reported results and
other data from literature suggest a possible protecting effect of the loop residues on the other parts of
the G-quadruplexes
Strand directionality affects cation binding and movement within tetramolecular G-quadruplexes
Nuclear magnetic resonance study of G-quadruplex
structures formed by d(TG3T) and its modified
analogs containing a 50-50 or 30-30 inversion of
polarity sites, namely d(30TG50-50G2T30), d(30T50-
50G3T30) and d(50TG30-30G2T5’) demonstrates formation
of G-quadruplex structures with tetrameric
topology and distinct cation-binding preferences.
All oligonucleotides are able to form quadruplex
structures with two binding sites, although the
modified oligonucleotides also form, in variable
amounts, quadruplex structures with only one
bound cation. The inter-quartet cavities at the inversion
of polarity sites bind ammonium ions less
tightly than a naturally occurring 50-30 backbone.
Exchange of 15NH+
4 ions between G-quadruplex
and bulk solution is faster at the 30-end in comparison
to the 50-end. In addition to strand directionality,
cation movement is influenced by formation of an
all-syn G-quartet. Formation of such quartet has
been observed also for the parent d(TG3T) that
besides the canonical quadruplex with only all-anti
G-quartets, forms a tetramolecular parallel
quadruplex containing one all-syn G-quartet, never
observed before in unmodified quadruplex
structures
Connectivity alterations underlying the breakdown of pseudoneglect: New insights from healthy and pathological aging
A right-hemisphere dominance for visuospatial attention has been invoked as the most prominent neural feature of pseudoneglect (i.e., the leftward visuospatial bias exhibited in neurologically healthy individuals) but the neurophysiological underpinnings of such advantage are still controversial. Previous studies investigating visuospatial bias in multiple-objects visual enumeration reported that pseudoneglect is maintained in healthy elderly and amnesic mild cognitive impairment (aMCI), but not in Alzheimer's disease (AD). In this study, we aimed at investigating the neurophysiological correlates sustaining the rearrangements of the visuospatial bias along the progression from normal to pathological aging. To this aim, we recorded EEG activity during an enumeration task and analyzed intra-hemispheric fronto-parietal and inter-hemispheric effective connectivity adopting indexes from graph theory in patients with mild AD, patients with aMCI, and healthy elderly controls (HC). Results revealed that HC showed the leftward bias and stronger fronto-parietal effective connectivity in the right as compared to the left hemisphere. A breakdown of pseudoneglect in patients with AD was associated with both the loss of the fronto-parietal asymmetry and the reduction of inter-hemispheric parietal interactions. In aMCI, initial alterations of the attentional bias were associated with a reduction of parietal inter-hemispheric communication, but not with modulations of the right fronto-parietal connectivity advantage, which remained intact. These data provide support to the involvement of fronto-parietal and inter-parietal pathways in the leftward spatial bias, extending these notions to the complex neurophysiological alterations characterizing pathological aging
Improved performances of catalytic G-quadruplexes (G4-DNAzymes) via the chemical modifications of the DNA backbone to provide Gquadruplexes with double 3′-external G-quartets
Here we report on the design of a new catalytic G-quadruplex-DNA system (G4-DNAzyme) based on the modification
of the DNA scaffold to provide the DNA pre-catalyst with two identical 3′-ends, known to bemore catalytically
proficient than the 5′-ends. To this end, we introduced a 5′-5′ inversion of polarity site in the middle of
the G4-forming sequences AG4A andAG6A to obtain d(3′AGG5′-5′GGA3′) (orAG2-G2A) and d(3′AGGG5′-5′GGGA3′)
(or AG3-G3A) that fold into stable G4 whose tetramolecular nature was confirmed via nuclear magnetic resonance
(NMR) and circular dichroism(CD) investigations. Both AG2-G2AandAG3-G3A display two identical external
G-quartets (3′-ends) known to interact with the cofactor hemin with a high efficiency, making the resulting
complex competent to performhemoprotein-like catalysis (G4-DNAzyme). A systematic comparison of the performances
of modified and unmodified G4s lends credence to the relevance of the modification exploited here
(5′-5′ inversion of polarity site), which represents a new chemical opportunity to improve the overall activity
of catalytic G4s
Exploring the binding of d(GGGT)4 to the HIV-1 integrase: An approach to investigate G-quadruplex aptamer/target protein interactions.
The aptamer d(GGGT)4 (T30923 or T30695) forms a 5'-5' dimer of two stacked parallel G-quadruplexes,
each characterized by three G-tetrads and three single-thymidine reversed-chain loops. This aptamer has
been reported to exhibit anti-HIV activity by targeting the HIV integrase, a viral enzyme responsible for
the integration of viral DNA into the host-cell genome. However, information concerning the aptamer/
target interaction is still rather limited. In this communication we report microscale thermophoresis
investigations on the interaction between the HIV-1 integrase and d(GGGT)4 aptamer analogues containing
abasic sites singly replacing thymidines in the original sequence. This approach has allowed the
identification of which part of the aptamer G-quadruplex structure is mainly involved in the interaction
with the protei
Psychologists in italian hospital settings: an exploratory analysis of hospital physicians: representations and demands of psychological Intervention
Aunque la Organización Mundial de la Salud
ha evidenciado la importancia de adoptar modelos
integrados de asistencia basados en el enfoque
bio-psico-social, en los servicios de salud, como
los hospitales, existe todavía mucha resistencia
para su implementación. Se presenta un estudio
exploratorio cualitativo dirigido a comprender las
representaciones y las demandas de los médicos
hospitalarios con respecto a la intervención psicológica
en los contextos hospitalarios italianos.
Conforme a este objetivo se desarrolló un guión de
entrevista semi-estructurada y se entrevistaron 15
médicos italianos divididos por género, edad y especialidad
médica. Fueron investigados las representaciones
de la enfermedad, el acercamiento a
los pacientes y los modelos de intervención, la experiencia
de colaboración con psicólogos, las representaciones
de dónde, cuándo y cómo los psicólogos
podrían ser útiles en el contexto hos pitalario,
las visiones generales del hospital y de su
futuro, los puntos de fuerza y de debilidad de su
trabajo, las estrategias utilizadas para superar las
dificultades diarias y las estrategias propuestas
pa ra mejorar el sistema hospitalario. El análisis de
contenido de las entrevistas ha revelado que la intervención
psicológica está representada predominantemente
como una intervención a nivel individual
dirigida a contener el distrés emocional en
relación con la enfermedad. Además se ha evidenciado
la falta de consideración de la competencia
psicológica como útil para promocionar el
funcionamiento organizativo de los servicios hospitalarios.
Estos resultados pueden apoyar la investigación
futura en esta área y son utilizados pa -
ra discutir las oportunidades de un diálogo constructivo
entre ciencias médica y psicológica en los
contextos hospitalarios.ABSTRACT: During the years, the World Health Organiza -
tion has been emphasising the importance of
promoting integrated models of care consistent
with a bio-psycho-social approach to health-illness.
Nonetheless, healthcare services still show much
resistance to the implementation of such models
and the use of multidisciplinary teams. As a con -
sequence, and despite the efforts made over the
years by psychologists, the role and specificity of
psychological competence in healthcare settings continues to remain unclear. This is particularly
true as regards hospital settings. Based on these
considerations, this article presents an exploratory
qualitative study aimed at understanding hospital
physicians’ representations of, and demands for,
psychological intervention in Italian hospital set -
tings. The main argument on which the study was
based is that the integration of psychological
competence into hospital settings very much
depends on other professionals’ representation of
the psychological profession, as well as on the
emotional symbolization of their work context and
professional practice. A key role is played by
physicians, whose representations of the psychol -
ogical intervention in hospital settings have been
under studied at the international level, and almost
not studied with regard to the Italian context. The
purpose of this study was to respond to this gap in
the literature. In this regard, a semi-structured
interview script was developed and used to inter -
view 15 Italian hospital physicians varying in
gender, age, and medical speciality. Participants
were selected by convenience and interviews were
carried out individually in the hospital settings.
Representations of disease; approach to patients
and models of intervention; experiences of collab -
oration with psychologists; representations of
where, when and how psychologists could be use -
ful in the hospital context; overall visions of one’s
hospital and its future; strengths and weaknesses of
one’s own work; strategies used to overcome
every day difficulties and strategies advocated to
improve the hospital were focus of analysis. The
interviews, administered by two researchers, were
audio-recorded and transcribed. Then a content
analysis was developed by three analysts that cod -
ed the units of the text (sequences) according to the
ca tegories and subcategories identified. The cate -
gories were: (a) perspective on medical inter vention;
(b) problems and weak nesses; (c) strengths;
(d) current and future strategies; (e) psychosocial
component of disease, and (f) relation ship between
Medicine and Psychology. Transcripts were ana -
lyzed independently by the analysts, and the interrater
agreement was 83%. Results revealed a
widespread view that psychol ogical science is of
limited relevance in the hospital context. The
difficulty in perceiving psychologists as a medical
resource appeared to be largely related to phys -
icians’ endorsement of a bio-medical ap proach, as well as to their lack of opportunities for formal
and/or informal collaboration with psy chologists.
Psychologists were thought of primarily as diag -
nosticians or therapists, and psychological interven
tion was mainly characterized as an individuallevel
intervention whose main objective is to
support the patient and manage his / her emotional
response to the disease (and the response of his /
her family). Despite physicians felt the hospital
system plagued by problems, especially at the
structural and functional levels, they did not
envisage psychological competence as useful for
fostering hospital organisational functioning. On
the contrary, they advocated a top-down change in
the hospital system, delegating responsibility for
change to hospital management or policy makers.
As a consequence, an urgent demand for Psychol -
ogy remains unexpressed. Although based on a
small sample, the present study provides useful
insights which may prompt further research in this
area. Furthermore, it provides information about
the demand for psychological intervention in the
hospital context which can be used to develop
strategies to promote multidisciplinary care and
integrated mind-body interventions. Results sug gest
the necessity to rethink professional roles and to
promote a constructive dialogue between medical
and psychological science in Italian hospital set -
tings.info:eu-repo/semantics/publishedVersio
Monomolecular G-quadruplex structures with inversion of polarity sites: new topologies and potentiality
In this paper, we report investigations, based on circular
dichroism, nuclear magnetic resonance spectroscopy
and electrophoresis methods, on three
oligonucleotide sequences, each containing one 3-
3 and two 5-5 inversion of polarity sites, and four
G-runs with a variable number of residues, namely
two, three and four (mTG2T, mTG3T andmTG4T with
sequence 3-TGnT-5-5-TGnT-3-3-TGnT-5-5-TGnT-3
in which n = 2, 3 and 4, respectively), in comparison
with their canonical counterparts (TGnT)4 (n
= 2, 3 and 4). Oligonucleotides mTG3T and mTG4 T
have been proven to form very stable unprecedented
monomolecular parallel G-quadruplex structures,
characterized by three side loops containing
the inversion of polarity sites. Both G-quadruplexes
have shown an all-syn G-tetrad, while the other
guanosines adopt anti glycosidic conformations. All
oligonucleotides investigated have shown a noteworthy
antiproliferative activity against lung cancer cell
line Calu 6 and colorectal cancer cell line HCT-116
p53−/−. Interestingly, mTG3T andmTG4T have proven
to be mostly resistant to nucleases in a fetal bovine
serum assay. The whole of the data suggest the involvement
of specific pathways and targets for the
biological activity
Exploring New Potential Anticancer Activities of the G-Quadruplexes Formed by [(GTG2T(G3T)3] and Its Derivatives with an Abasic Site Replacing Single Thymidine
In this paper, we report our investigations on five T30175 analogues, prepared by replacing sequence thymidines with abasic sites (S) one at a time, in comparison to their natural counterpart in order to evaluate their antiproliferative potential and the involvement of the residues not belonging to the central core of stacked guanosines in biological activity. The collected NMR (Nuclear Magnetic Resonance), CD (Circular Dichroism), and PAGE (Polyacrylamide Gel Electrophoresis) data strongly suggest that all of them adopt G-quadruplex (G4) structures strictly similar to that of the parent aptamer with the ability to fold into a dimeric structure composed of two identical G-quadruplexes, each characterized by parallel strands, three all-anti-G-tetrads and four one-thymidine loops (one bulge and three propeller loops). Furthermore, their antiproliferative (MTT assay) and anti-motility (wound healing assay) properties against lung and colorectal cancer cells were tested. Although all of the oligodeoxynucleotides (ODNs) investigated here exhibited anti-proliferative activity, the unmodified T30175 aptamer showed the greatest effect on cell growth, suggesting that both its characteristic folding in dimeric form and its presence in the sequence of all thymidines are crucial elements for antiproliferative activity. This straightforward approach is suitable for understanding the critical requirements of the G-quadruplex structures that affect antiproliferative potential and suggests its application as a starting point to facilitate the reasonable development of G-quadruplexes with improved anticancer properties
Structural and Biological Features of G-Quadruplex Aptamers as Promising Inhibitors of the STAT3 Signaling Pathway
: In this paper, we investigate the structural and biological features of G-quadruplex (G4) aptamers as promising antiproliferative compounds affecting the STAT3 signalling pathway. Targeting the STAT3 protein through high-affinity ligands to reduce its levels or activity in cancer has noteworthy therapeutic potential. T40214 (STAT) [(G3C)4] is a G4 aptamer that can influence STAT3 biological outcomes in an efficient manner in several cancer cells. To explore the effects of an extra cytidine in second position and/or of single site-specific replacements of loop residues in generating aptamers that can affect the STAT3 biochemical pathway, a series of STAT and STATB [GCG2(CG3)3C] analogues containing a thymidine residue instead of cytidines was prepared. NMR, CD, UV, and PAGE data suggested that all derivatives adopt dimeric G4 structures like that of unmodified T40214 endowed with higher thermal stability, keeping the resistance in biological environments substantially unchanged, as shown by the nuclease stability assay. The antiproliferative activity of these ODNs was tested on both human prostate (DU145) and breast (MDA-MB-231) cancer cells. All derivatives showed similar antiproliferative activities on both cell lines, revealing a marked inhibition of proliferation, particularly at 72 h at 30 µM. Transcriptomic analysis aimed to evaluate STAT's and STATB's influence on the expression of many genes in MDA-MB-231 cells, suggested their potential involvement in STAT3 pathway modulation, and thus their interference in different biological processes. These data provide new tools to affect an interesting biochemical pathway and to develop novel anticancer and anti-inflammatory drugs
Platelet abnormalities and platelet-to-lymphocyte ratios in canine immunosuppressant-responsive and non-responsive enteropathy: A retrospective study in 41 dogs
Few studies have examined platelet alterations in dogs with chronic enteropathy. Our aim was to investigate platelet count (PLT), mean platelet volume (MPV), and platelet-to-lymphocyte ratio (PLR) in dogs diagnosed with immunosuppressant-responsive enteropathy (IRE). In this retrospective study of 41 dogs, data regarding signalment, canine chronic enteropathy clinical activity index (CCECAI), endoscopic and histopathological scores, PLT, MPV, PLR, total serum protein concentrations, albumin, and iron were collected. Clinical response and relapse were assessed with the evaluation of CCECAI over time. One month after starting therapy, dogs with >25% CCECAI reduction were considered responders. During a three-month CCECAI evaluation as part of a twelve-month follow-up, a CCECAI >3 together with a ≥2 unit increase in responder dogs was considered a relapse. PLT and PLR displayed significant negative correlation with MPV. MPV was positively correlated with total protein and albumin levels and negatively correlated with CCECAI. Three dogs were classified as non-responders, and 14 relapsed within 12 months. No differences were observed in PLT, MPV, or PLR between responding/non-responding and relapsing/non-relapsing groups. PLT, MPV, and PLR correlated with total protein, albumin, and CCECAI, confirming PLT as a potential marker, and suggesting MPV as a new marker of clinical efficacy against canine IRE
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