1,721,151 research outputs found
Thyroid hormone analogues: An update
Full text linkThe development of thyroid hormone (TH) analogues was prompted by the attempt to exploit the effects of TH on lipid metabolism, avoiding cardiac thyrotoxicosis. Analysis of the relative distribution of the α and β subtypes of nuclear TH receptors (TRα and TRβ) showed that TRα and TRβ are responsible for cardiac and metabolic responses, respectively. Therefore, analogues with TRβ selectivity were developed, and four different compounds have been used in clinical trials: GC-1 (sobetirome), KB-2115 (eprotirome), MB07344/VK2809, and MGL-3196 (resmetirom). Each of these compounds was able to reduce low-density lipoprotein cholesterol, but a phase 3 trial with eprotirome was interrupted because of a significant increase in liver enzymes and the contemporary report of cartilage side effects in animals. As a consequence, the other projects were terminated as well. However, in recent years, TRβ agonists have raised new interest for the treatment of nonalcoholic fatty liver disease (NAFLD). After obtaining excellent results in experimental models, clinical trials have been started with MGL-3196 and VK2809, and the initial reports are encouraging. Sobetirome turned out to be effective also in experimental models of demyelinating disease. Aside TRβ agonists, TH analogues include some TH metabolites that are biologically active on their own, and their synthetic analogues. 3,5,3′-triiodothyroacetic acid has already found clinical use in the treatment of some cases of TH resistance due to TRβ mutations, and interesting results have recently been reported in patients with the Allan-Herndon-Dudley syndrome, a rare disease caused by mutations in the TH transporter MCT8. 3,5-diiodothyronine (T2) has been used with success in rat models of dyslipidemia and NAFLD, but the outcome of a clinical trial with a synthetic T2 analogue was disappointing. 3-iodothyronamine (T1AM) is the last entry in the group of active TH metabolites. Promising results have been obtained in animal models of neurological injury induced by β-amyloid or by convulsive agents, but no clinical data are available so far
New species of Trichogramma Westwood (Hymenoptera: Trichogrammatidae) associated with lepidopterous eggs in Brazil
No full textQuerino, R. B., Zucchi, R. A. (2003): New species of Trichogramma Westwood (Hymenoptera: Trichogrammatidae) associated with lepidopterous eggs in Brazil. Zootaxa 163: 1-10, DOI: 10.5281/zenodo.15679
FIGURE 1. Trichogrammatoidea annulata. A–B in Redescription of Trichogrammatoidea annulata De Santis (Hymenoptera: Trichogrammatidae)
No full textFIGURE 1. Trichogrammatoidea annulata. A–B. Antenna: A. Female, B. Male. C. Fore wing. D. Hind wing. E. Marginal vein of forewing. F–G. Male genital capsule: F. Ventral view, G. Dorsal view. H. Female genital capsule.Published as part of Querino, R. B. & Zucchi, R. A., 2004, Redescription of Trichogrammatoidea annulata De Santis (Hymenoptera: Trichogrammatidae), pp. 1-7 in Zootaxa 677 on page 4, DOI: 10.5281/zenodo.15855
Novel thyroid hormones
No full textThe field of thyroid hormone signaling has grown more complex in recent years. In particular, it has been suggested that some thyroid hormone derivatives, tentatively named "novel thyroid hormones" or "active thyroid hormone metabolites", may act as independent chemical messengers. They include 3,5-diiodothyronine (T2), 3-iodothyronamine (T1AM), and several iodothyroacetic acids, i.e., 3,5,3',5'-thyroacetic acid (TA4), 3,5,3'-thyroacetic acid (TA3), and 3-thyroacetic acid (TA1). We summarize the present knowledge on these compounds, namely their biosynthetic pathways, endogenous levels, molecular targets, and the functional effects elicited in experimental preparations or intact animals after exogenous administration. Their physiological and pathophysiological role is discussed, and potential therapeutic applications are outlined. The requirements needed to qualify these substances as chemical messengers must still be validated, although promising evidence has been collected. At present, the best candidate to the role of independent chemical messenger appears to be T1AM, and its most interesting effects concern metabolism and brain function. The responses elicited in experimental animals have suggested potential therapeutic applications. TA3 has an established role in thyroid hormone resistance syndromes, and is under investigation in Allen-Herndon-Dudley syndrome. Other potential targets are represented by obesity and dyslipidemia (for T2 and T1AM); dementia and degenerative brain disease (for T1AM and TA1); cancer (for T1AM and TA4). Another intriguing and unexplored question is the potential relevance of these metabolites in the clinical picture of hypothyroidism and in the response to replacement therapy
FIGURE 3. Trichogramma annulata. A–G in Redescription of Trichogrammatoidea annulata De Santis (Hymenoptera: Trichogrammatidae)
No full textFIGURE 3. Trichogramma annulata. A–G. Genital capsule Male: A. dorsal view; B. Dorsal view with apodemes; C. Detail apical of dorsal view; D. Ventral view; E. Apical detail (ventral view); F. Ventral view (intervolselar process minute); G. Detail apical (ventral view). H–I. Genital capsule female: H. Ventral view. I. Apical detail (ventral view).Published as part of Querino, R. B. & Zucchi, R. A., 2004, Redescription of Trichogrammatoidea annulata De Santis (Hymenoptera: Trichogrammatidae), pp. 1-7 in Zootaxa 677 on page 6, DOI: 10.5281/zenodo.15855
Vitamin D status and cardiovascular outcome
No full textIntroduction: Vitamin D is classically involved in maintaining bone and mineral health, but it has been shown to exert many extraskeletal functions, including pleiotropic effects on cardiovascular system. Materials and method: This review aims to summarize evidences in literature about vitamin D and cardiovascular outcome. Results and conclusions: Calcitriol or 1,25(OH)2D, the active hormone, binds to the specific nuclear receptor VDR, which is expressed in rat and human heart and vasculature and has effects on myocardiocytes, smooth cells, and endothelial cells. 25-Hydroxy-vitamin D (25OHD) represents the biomarker of vitamin D levels and reflects vitamin D status. There is consistent evidence that low serum 25OHD levels are associated with increased risk of cardiovascular diseases, including hypertension, coronary artery disease, ischemic heart disease, heart failure, stroke, and type 2 diabetes. Randomized-controlled trials and Mendelian randomization studies so far have not succeeded in proving a benefit of vitamin D supplementation. However, the latter investigations are affected by some methodological limitations, and therefore, it is still unclear if vitamin D deficiency has a causative role in cardiovascular diseases or is rather a marker of poor health in chronic disease
The TRbeta-selective agonist, GC-1, stimulates mitochondrial oxidative processes to a lesser extent than triiodothyronine
No full textJ Endocrinol. 2010 Jun;205(3):279-89. Epub 2010 Apr 1.
The TRbeta-selective agonist, GC-1, stimulates mitochondrial oxidative processes to a lesser extent than triiodothyronine.
Venditti P, Chiellini G, Di Stefano L, Napolitano G, Zucchi R, Columbano A, Scanlan TS, Di Meo S.
SourceDipartimento delle Scienze Biologiche, Sezione di Fisiologia, Università di Napoli Federico II, Via Mezzocannone 8, I-80134 Napoli, Italy. [email protected]
Abstract
Specific tissue responses to thyroid hormone are mediated by the hormone binding to two subtypes of nuclear receptors, TRalpha and TRbeta. We investigated the relationship between TRbeta activation and liver oxidative metabolism in hypothyroid rats treated with equimolar doses of triiodothyronine (T(3)) and GC-1, a TRbeta agonist. T(3) treatment produces increases in O(2) consumption and H(2)O(2) production higher than those elicited by GC-1. The greater effects of T(3) on oxidative processes are linked to the higher hormonal stimulation of the content of respiratory chain components including autoxidizable electron carriers as demonstrated by the measurement of activities of respiratory complexes and H(2)O(2) generation in the presence of respiratory inhibitors. It is conceivable that these differential effects are dependent on the inability of GC-1 to stimulate TRalpha receptors that are likely involved in the expression of some components of the respiratory chain. The greater increases in reactive oxygen species production and susceptibility to oxidants exhibited by mitochondria from T(3)-treated rats are consistent with their higher lipid and protein oxidative damage and lower resistance to Ca(2)(+) load. The T(3) and GC-1 effects on the expression levels of nuclear respiratory factor-1 and -2 and peroxisome proliferator-activated receptor-gamma coactivator-1alpha suggest the involvement of respiratory factors in the agonist-linked changes in mitochondrial respiratory capacities and H(2)O(2) production.
PMID:20360308[PubMed - indexed for MEDLINE
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
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