1,721,014 research outputs found
Recent advances in cellular and molecular aspects of mammalian retinal ischemia
Full text linkRetinal ischemia is a common clinical entity and, due
to relatively ineffective treatment, remains a common
cause of visual impairment and blindness. Generally,
ischemic syndromes are initially characterized by low
homeostatic responses which, with time, induce injury
to the tissue due to cell loss by apoptosis. In this respect,
retinal ischemia is a primary cause of neuronal
death. It can be considered as a sort of final common
pathway in retinal diseases and results in irreversible
morphological and functional changes. This review
summarizes the recent knowledge on the effects of
ischemia in retinal tissue and points out experimental
strategies/models performed to gain better comprehension
of retinal ischemia diseases. In particular, the
nature of the mechanisms leading to neuronal damage
(i.e., excess of glutamate release, oxidative stress and
inflammation) will be outlined as well as the potential
and most intriguing retinoprotective approaches and
the possible therapeutic use of naturally occurring
molecules such as neuropeptides. There is a general
agreement that a better understanding of the fundamental
pathophysiology of retinal ischemia will lead to better management and improved clinical outcome. In
this respect, to contrast this pathological state, specific
pharmacological strategies need to be developed
aimed at the many putative cascades generated during
ischemia
The neuropeptide systems and their potential role in the treatment of mammalian retinal ischemia: a developing story
Full text linkThe multiplicity of peptidergic receptors and of the transduction pathways they activate offers the possibility of
important advances in the development of specific drugs for clinical treatment of central nervous system disorders.
Among them, retinal ischemia is a common clinical entity and, due to relatively ineffective treatment, remains a common
cause of visual impairment and blindness. Ischemia is a primary cause of neuronal death, and it can be considered as a sort
of final common pathway in retinal diseases leading to irreversible morphological damage and vision loss. Neuropeptides
and their receptors are widely expressed in mammalian retinas, where they exert multifaceted functions both during
development and in the mature animal. In particular, in recent years somatostatin and pituitary adenylate cyclase
activating peptide have been reported to be highly protective against retinal cell death caused by ischemia, while data on
opioid peptides, angiotensin II, and other peptides have also been published. This review provides a rationale for
harnessing the peptidergic receptors as a potential target against retinal neuronal damages which occur during ischemic
retinopathies
An update on somatostatin receptor signalling in native systems and new insights on their pathophysiology
No full textThe peptide somatostatin (SRIF) has important physiological effects, mostly inhibitory, which have formed the basis for the clinical use of SRIF compounds. SRIF binding to its 5 guanine nucleotide-binding proteins-coupled receptors leads to the modulation of multiple transduction pathways. However, our current understanding of signaling exerted by receptors endogenously expressed in different cells/tissues reflects a rather complicated picture. On the other hand, the complexity of SRIF receptor signaling in pathologies, including pituitary and nervous system diseases, may be studied not only as alternative intervention points for the modulation of SRIF function but also to exploit new chemical space for drug-like molecules
Effects of somatostatin in animal models of retinal disease
No full textThe neuropeptide somatostatin (somatotropin release inhibiting factor, SRIF) has been widely investigated in the retina, where it is localized to sparse amacrine cells and, in some instances, in a subset of ganglion cells. All five different SRIF subtype receptors (designated sst1 through sst5) are expressed in the mammalian retina, and their variegated expression patterns, together with the variety of signaling mechanisms activated by the different ssts, suggest that the somatostatinergic system may exert multiple actions on retinal neurons and on retinal physiology. For instance, SRIF, mostly acting through sst2, functions as a positive factor in the retina by regulating retinal homeostasis and protecting neurons against damage. In particular, a considerable amount of experimental evidence has been gathered to show that sst2 activation may effectively limit the expression of pro-angiogenic signals, thereby counteracting the growth of new, aberrant vessels that is typically seen, for instance, in diabetic retinopathy. In addition, SRIF has been shown to protect retinal neurons from excitotoxic insults caused by excess of glutamate release. This condition is frequently associated with retinal ischemia, which is a common cause of severe retinal damage in different pathologies. Several studies have described potent protective actions of SRIF in the ischemic retina mediated by sst2 activation. Taken together, these data support the notion that therapeutic strategies based on the use and implementation of SRIF analogues may be clinically relevant in different retinal diseases such as ischemic and diabetic retinopathies. This chapter reviews the literature concerning the advances in the research of the roles played by the somatostatinergic system in animal models of retinal disease
Multiple signalling transduction mechanisms differentially coupled to somatostatin receptor subtypes: a current view
No full text
Physiology and pathology of somatostatin in the mammalian retina: a current view
Full text linkIn the retina, peptidergic signalling participates in multiple circuits of visual information processing. The neuropeptide somatostatin (SRIF) is localised to amacrine cells and, in some instances, in a subset of ganglion cells. The variegated expression patterns of SRIF receptors (sst(1)-sst(5)) and the variety of signalling mechanisms activated by retinal SRIF suggest that this peptide may exert multiple actions on retinal neurons and on retinal physiology, although our current understanding reflects a rather complicated picture. SRIF, mostly through sst(2), may act as a positive factor in the retina by regulating retinal homeostasis and protecting neurons against damage. In this respect, SRIF analogues seem to constitute a promising therapeutic arsenal to cure different retinal diseases, as for instance, ischemic and diabetic retinopathies. However, further investigations are needed not only to fully understand the functional role of the SRIF system in the retina but also to exploit new chemical space for drug-like molecules
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
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