Biomedical subjects

A Rocha-Sousa

Publications and source records attributed to A Rocha-Sousa.

5 recordsLinked to original sources

PubMed2006

Ghrelin as a novel locally produced relaxing peptide of the iris sphincter and dilator muscles.

Ghrelin is a recently described acylated peptide, which works as a somatosecretagogue and has described effects on the smooth, skeletal and cardiac muscle. We examined the production and effects of ghrelin on relaxation of the iris muscles. Contractile effects of 1-5 human ghrelin (frGhr, 10(-9)-6 x 10(-5)M) and 1-5 human des-octanoyl-ghrelin (d-frGhr; 10(-9)-6 x 10(-5)M) were tested on iris rabbit sphincter (n=11 frGhr; n=7 d-frGhr), dilator (n=6 frGhr; n=6 d-frGhr) and rat sphincter (n=6 frGhr; n=8 d-frGhr) precontracted muscles. On rabbit sphincter the effect of frGhr was also tested in presence of: i) L-NA (10(-5)M; n=7); ii) indomethacin (10(-5)M; n=7); iii) DLys(3)GHRP6 (10(-4)M; n=6); and iv) apamin+carybdotoxin (10(-6)M; n=6). Furthermore, on rabbit dilator the effect of frGhr was tested in presence of DLys(3)GHRP6 (10(-4)M; n=7). Finally, ghrelin mRNA production was assessed by "in situ" hybridization in Wistar rat eyes (n=8). In all muscles, frGhr promoted a concentration-dependent relaxation, maximal at 6 x 10(-5)M, 1.5-3 min after its addition, decreasing tension by 34.1+/-12.1%, 25.8+/-4.8% and 52.1+/-10.3% in the rabbit sphincter, dilator and rat sphincter, respectively. In the rabbit sphincter the relaxing effects of frGhr were: (i) enhanced in presence of DLys(3)GHRP6 (118.1+/-21.1%); (ii) blunted by indomethacin; and (iii) not altered by apamin+carybdotoxin (36.4+/-14.4%) or L-NA (52.4+/-11.4%). Relaxing effects of d-frGhr in rabbit (43.3+/-5.2%) and rat (77.1+/-15.3%) sphincter muscles were similar to those of frGhr. In rabbit dilator muscle, d-frGhr did not significantly alter active tension and the relaxing effect of frGhr was blunted by GHSR-1a blockage. Ghrelin mRNA was identified in iris posterior epithelium. In conclusion, ghrelin is a novel, locally produced, relaxing agent of iris dilator and sphincter muscles, an effect that is mediated by GHSR-1a in the former, but not in the latter. Furthermore, in the sphincter it seems to be mediated by prostaglandins, but not by NO or K(Ca) channels.

Animals↗

PubMed2003

Modern sports eye injuries.

AIMS: To determine the severity and long term sequelae of eye injuries caused by modern sports that could be responsible for significant ocular trauma in the future. METHODS: Prospective observational study of 24 (25 eyes) athletes with sports related ocular injuries from health clubs, war games, adventure, radical and new types of soccer, presenting to an eye emergency department between 1992 and 2002 (10 years). RESULTS: Modern sports were responsible for 8.3% of the 288 total sports eye injuries reported. Squash (29.2%) was the most common cause, followed by paintball (20.8%) and motocross (16.6%). The most common diagnosis during the follow up period was retinal breaks (20%). 18 (75%) patients sustained a severe injury. The final visual acuity remained <20/100 in two paintball players. CONCLUSIONS: Ocular injuries resulting from modern sports are often severe. Adequate instruction of the participants in the games, proper use of eye protectors, and a routine complete ophthalmological examination after an eye trauma should be mandatory.

Adolescent↗

PubMed2001

[Mechanisms underlying endothelin-1 effects on myocardial function].

INTRODUCTION: Endothelin-1 (ET-1) has potent vasoconstrictor, growth promoting and positive inotropic properties. Its effects on the intrinsic properties of the myocardium were recently described. The present study investigated the mechanisms underlying those effects. METHODS: The myocardial effects of 1 and 10 nM of ET-1 were evaluated in isolated rabbit papillary muscles (n = 9) and human atrial trabecula from CABG patients (Krebs-Ringer; 1.8 mM CaCl2; 35 degrees C). In papillary muscles the effects of 1 nM ET-1 were also studied in the presence of: (i) a selective ETA receptor antagonist, BQ-123 (0.1 microM; n = 9); (ii) a selective ETB receptor antagonist, BQ-788 (0.1 microM; n = 6); and (iii) an Na+/H+ exchanger inhibitor, methyl-isobutyl-amiloride (MIA; 1 microM; n = 6). Only significant results (mean +/- SE, p < 0.05) are given, expressed as delta % baseline. RESULTS: In AT by papillary muscles, 1 nM of ET-1 increased 64 +/- 16%, dT/dtmin 39 +/- 13% and decreased PT by 11 +/- 2%. The analysis of atrial strip contractions yielded similar results. In papillary muscles the effects of ET-1 were not affected by BQ-788, yet they were abolished by BQ-123, and reduced by 44% by MIA. CONCLUSIONS: The action of ET-1 on myocardial function is similar in human and non-human myocardium. The myocardial effects observed in the present study are mediated by the binding to ETA receptors, and partially dependent on Na+/H+ exchanger activation.

Animals↗

PubMed2000

[The effects of endothelin-1 on myocardial function].

INTRODUCTION: Endothelin-1 (ET-1) has potent vasoconstrictor, growth promoting and positive inotropic properties, with increased plasma levels in heart failure (HF). With regard to the cardiac effects of ET-1, most studies have not been able to differentiate its effects on the intrinsic properties of the myocardium from the secondary effects resulting from load changes and coronary vasoconstriction. This study investigated the myocardial effects of ET-1. METHODS: The study was performed on isolated rabbit papillary muscles (n = 9), before and after the addition of ET-1 (10 nM) to the superfusing solution (Krebs-Ringer; 1.25 nM Ca2+; 35 degrees C). One isotonic, one isometric and two afterloaded-isotonic twitches were recorded and analyzed. Only significant results (mean +/- SE, p < 0.05) are given, expressed as delta % baseline. RESULTS: ET-1 induced an increase of AT (147 +/- 33%), dT/dtmax (154 +/- 39%) and dT/dtmin (145 +/- 38%), while the duration of the twitch did not vary significantly. In addition, after ET-1, RT at the end of the isometric twitch decreased by 19 +/- 3%, when compared with the control and to its value at the beginning of the twitch. CONCLUSIONS: This study showed that, in addition to the well-known positive inotropic effect, ET-1 improves diastolic function by accelerating relaxation rate (dT/dtmin) and decreasing RT. These results may have important implications in the pathophysiology of HF.

Animals↗

PubMedDate not supplied

Identification of XLRS1 gene mutation (608C > T) in a Portuguese family with juvenile retinoschisis.

PURPOSE: To characterize electroretinogram (ERG) and molecular genetic findings in a family with XLRS1 mutation. The authors present two cases of a Portuguese family with juvenile retinoschisis with a mutation in exon 6. METHODS: Two brothers and their parents, grandmother, and uncle underwent a full ophthalmic examination. The two brothers with ophthalmic disease were evaluated with color fundus photography, fluorescein angiography, optical coherence tomography (OCT), molecular genetic study (Group VI of Retinoschisis Consortium), pattern visual evoked potential (PVEP), and full field ERG. RESULTS: Both patients presented funduscopic manifestations of vitre o retinal degeneration. They presented peripheral schisis and retinal detachment. However, foveal schisis had never been observed at funduscopy. A negative ERG was recorded in both. Six months after that, the younger brother showed a typical foveal schisis at fundus examination. A retinoschisis gene (XLRS1) mutation with transition of cytosine by thymine at position 608 (608C > T) had been identified in both. CONCLUSIONS: Negative ERG is the most secure clinical marker to establish the diagnosis of juvenile retinoschisis. XLRS1 gene 608C > T mutation was described for the first time in a Portuguese family.

Child↗