Amândio Rocha-Sousa

Inotropic and lusitropic effects of ghrelin and their modulation by the endocardial endothelium, NO, prostaglandins, GHS-R1a and KCa channels.

Contractile effects of ghrelin (10(-9) to 10(-6) M) were tested in rat papillary muscles of normal (n = 50) and hypertrophic (n = 16) right ventricles (RV). RV hypertrophy was induced by pulmonary hypertension using monocrotaline. In normal muscles, ghrelin was added either alone (n = 9) or after pre-treatment with indomethacin (cycloxygenase inhibitor, 10(-5) M; n = 10), L-nitro-L-arginin (NO synthase inhibitor, 10(-4) M; n = 9), D-Lys(3)-GHRP-6 (GHS-R1a antagonist; 10(-4) M; n = 8) or apamin+charybdotoxin (KCa channels blockers; 10(-6) M, n =7 ), as well as after damaging the endocardial endothelium (n = 7). In hypertrophic muscles, ghrelin was added either alone (n = 9) or after pre-treatment with apamin+charybdotoxin (10(-6 M, n=7). Ghrelin concentration-dependently decreased active tension (AT) and maximal velocity of tension rise (negative inotropic effect), as well as, maximal velocity of tension decay (negative lusitropic effect) and time to AT (onset of relaxation). These effects were maximal at 10(-6) M, similar in normal and hypertrophic muscles and were significantly altered only by apamin+charybdotoxin, indomethacin and L-nitro-L-arginin. Apamin+charybdotoxin attenuated the negative inotropic effect, while indomethacin and L-nitro-L-arginin, respectively, blunted and exacerbated the premature onset of relaxation. In conclusion, ghrelin induces negative inotropic and lusitropic effects and an earlier onset of relaxation in normal and hypertrophic myocardium, which are independent of GHS-R1a, since they were not affected by D-Lys(3)-GHRP-6. The negative inotropic effect is partly mediated by KCa channels, while the earlier onset of relaxation is modulated by prostaglandins and NO.

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.

Spectral-domain optical coherence tomography of the choroid during valsalva maneuver.

PURPOSE To evaluate the influence of Valsalva maneuver on the morphology and thickness of the choroid at the macular area. DESIGN Prospective interventional case series. METHODS Institutional setting. Nine healthy volunteers performed macular spectral-domain optical coherence tomography using enhanced-depth imaging at rest and during a Valsalva maneuver. Horizontal and vertical B-scans centered on the fovea were acquired. Subfoveal and average choroidal thickness in the central 3 mm were compared in the resting position and during the Valsalva maneuver using manual and semiautomatic measuring tools. Changes in choroidal thickness were evaluated. RESULTS There was no statistically significant difference in choroidal thickness at rest or during Valsalva maneuver in any of the compared groups. The subfoveal thickness difference was -4.1 μm on horizontal scans (P = .28) and 1.4 μm on vertical scans (P = .75). The mean choroidal thickness difference in the central 3000 μm was 8.5 μm on horizontal scans (P = .73) and -5.3 μm on vertical scans (P = .41). CONCLUSIONS Valsalva maneuver does not change choroidal thickness at the posterior pole. The increase in ocular pressure caused by this maneuver cannot be explained by an increase in choroidal thickness in this portion of the uveal tract.

Choroidal and macular thickness changes induced by cataract surgery

Background The aim of this study was to evaluate the effect of uneventful phacoemulsification on the morphology and thickness of the macula, the submacular choroid, and the peripapillary choroid. Methods In 14 eyes from 14 patients, retinal macular thickness, choroidal submacular thickness, and choroidal peripapillary thickness were measured preoperatively and at one week and one month after phacoemulsification using enhanced depth imaging spectral domain optical coherence tomography. Changes in thickness of the different ocular tissues were evaluated. Results There was a statistically significant increase in mean retinal macular thickness at one month. In horizontal scans, the mean increase was +8.67±6.75 μm (P<0.001), and in vertical scans, the mean increase was +8.80±7.07 μm (P=0.001). However, there were no significant changes in choroidal morphology in the submacular and peripapillary areas one month after surgery. In vertical scans, there was a nonsignificant increase in choroidal thickness (+4.21±20.2 μm; P=0.47) whilst in horizontal scans a nonsignificant decrease was recorded (−9.11±39.59 μm; P=0.41). In peripapillary scans, a nonsignificant increase in mean choroidal thickness was registered (+3.25±11.80 μm; P=0.36). Conclusion Uncomplicated phacoemulsification induces nonpathologic increases in retinal macular thickness probably due to the inflammatory insult of the surgery; however these changes are not accompanied by significant changes in choroidal thickness. In the posterior segment, the morphologic response to the inflammatory insult of phacoemulsification is mainly observed at the retinal level, and seems to be independent of choroidal thickness changes.

Cardiac, Skeletal, and Smooth Muscle Regulation by Ghrelin

Ghrelin, mainly secreted from gastric mucosa, is the endogenous ligand for the growth hormone secretagogue receptor and induces a potent release of growth hormone. Ghrelin is widely expressed in different tissues and therefore has both endocrine and paracrine/autocrine effects. In this chapter, we summarize: (1) structure and distribution of ghrelin and its receptors; (2) myocardial effects of ghrelin, describing its acute and chronic actions on cardiac function; (3) ghrelin effects on smooth muscle, namely vascular smooth muscle, intraocular and gastrointestinal smooth muscle; and (4) skeletal actions of ghrelin. Ghrelin has a potent vasodilator effect, thereby reducing cardiac afterload and increasing cardiac output. In models of heart failure and myocardial ischemia, ghrelin administration has beneficial effects. At smooth muscle, ghrelin modulates vascular tone, increases gut transit, and relaxes iris muscles. In the skeletal muscle, ghrelin regulates resting membrane potential. In conclusion, there are increasing evidences that ghrelin is a peptide with paracrine actions that can modulate cardiac, smooth, and skeletal muscle functions.

Analyses of aqueous humour ghrelin levels of eyes with and without glaucoma

Ghrelin is an acylated, 28-amino-acid peptide isolated from human and rat gastric oxyntic mucosa,1 with actions mediated by the GHSR-1a receptor. The ability of ghrelin to activate GHSR-1a is dependent on the presence of an octanoyl-(acyl)-chain in serine-3.2 As almost 90% of circulating ghrelin lacks this chain3 and this desacylated form (des-acyl-ghrelin) has biological effects, this means that these effects are not mediated by GHSR-1a. The presence of ghrelin in the rat posterior epithelium of the iris and non-pigmented ciliary epithelium was recently demonstrated.4 It relaxes both the iris sphincter and dilator muscles, through a GHSR-1a-dependent mechanism in the dilator, but GHSR-1a-independent in the sphincter.4 In ocular tissues, obestatin, a peptide derived from the ghrelin gene,5 promotes the proliferation of human retinal pigmentary epithelium cells6 and potentiates cholinergic contraction.7 The aim of our study was to determine the AqH levels of ghrelin and des-acyl-ghrelin in patients with and without glaucoma that underwent cataract surgery. This prospective study included consecutive patients with (n = 9) and without (n = 15) open-angle glaucoma who were …

Possible role for fundus autofluorescence as a predictive factor for visual acuity recovery after epiretinal membrane surgery.

Purpose: To study the potential association between fundus autofluorescence, spectral-domain optical coherence tomography, and visual acuity in patients undergoing surgery because of epiretinal membranes. Methods: Prospective, interventional case series including 26 patients submitted to vitrectomy because of symptomatic epiretinal membranes. Preoperative evaluation consisted of a complete ophthalmologic examination, autofluorescence, and spectral-domain optical coherence tomography. Studied variables included foveal autofluorescence (fov.AF), photoreceptor inner segment/outer segment (IS/OS) junction line integrity, external limiting membrane integrity, central foveal thickness, and foveal morphology. All examinations were repeated at the first, third, and sixth postoperative months. The main outcome measures were logarithm of minimal angle resolution visual acuity, fov.AF integrity, and IS/OS integrity. Results: All cases showing a continuous IS/OS line had an intact fov.AF, whereas patients with IS/OS disruption could have either an increased area of foveal hypoautofluorescence or an intact fov.AF, with the latter being associated with IS/OS integrity recovery in follow-up spectral-domain optical coherence tomography imaging. The only preoperative variables presenting a significant correlation with final visual acuity were baseline visual acuity (P = 0.047) and fov.AF grade (P = 0.023). Conclusion: Recovery of IS/OS line integrity after surgery, in patients with preoperative IS/OS disruption and normal fov.AF, can be explained by the presence of a functional retinal pigment epithelium–photoreceptor complex, supporting normal photoreceptor activity. Autofluorescence imaging provides a functional component to the study of epiretinal membranes, complementing the structural information obtained with optical coherence tomography.

Evaluation of visual acuity, macular status, and subfoveal choroidal thickness changes after cataract surgery in eyes with diabetic retinopathy.

Purpose: Progression of diabetic macular edema has been reported as a common cause of poor visual acuity recovery after cataract surgery in patients with diabetes. Despite being responsible for the blood supply to the outer retina, the role of the choroidal layer in the pathogenesis of diabetic retinopathy (DR) is not yet understood. Our objective is to characterize macular and subfoveal choroidal thickness changes after cataract surgery in eyes with DR. Methods: Thirty-five eyes with clinically significant cataract of patients with DR were divided into three groups based on clinical and optical coherence tomography findings: patients with DR without macular edema, patients with DR and macular thickening detected on optical coherence tomography, and finally patients with clinically significant macular edema. All cases were submitted to ophthalmologic examination and spectral domain optical coherence tomography 1 week before cataract surgery and repeated 1 month after surgery. Patients with preoperative clinically significant macular edema were treated with intravitreal bevacizumab at the time of surgery. Results: All groups showed a significant increase in visual acuity 1 month after surgery (P < 0.001). Mean foveal thickness increased significantly in all groups, including controls (P = 0.013), except in patients who were simultaneously treated with intravitreal bevacizumab (P = 0.933). An increase of maximum macular thickness of at least 11% was found in 25.7% of the DR eyes, but no such increase occurred in the control eyes. No significant change was verified for subfoveal choroidal thickness in any of the studied groups. Conclusion: Surgical inflammation associated with cataract surgery caused a significant increase of macular thickness in control and DR eyes that were not treated with intravitreous bevacizumab. Such macular changes were not accompanied by subfoveal choroidal thickness changes in any of the study groups, suggesting that the changes in macular thickness associated with the surgery are not related to changes in choroidal thickness and that there is no relation between inner blood–retinal barrier status and diabetic choroidal angiopathy.

The obestatin/ghrelin system as a novel regulatory mechanism of iris muscle contraction.

Purpose: To evaluate obestatin and ghrelin effects on iris muscle contraction. Materials and Methods: Obestatin (10−5 M) or ghrelin (10−5 M) were tested on two consecutive carbachol-or epinephrine-elicited contractions of iris rabbit sphincter or dilator muscles. Ghrelin and obestatin effects on iris muscles basal tension were also tested, and their effects on iris sphincter EFS-elicited contraction were evaluated. Results: Compared with the first, tension of the second carbachol-induced contraction of the iris sphincter decreased 11.5 ± 5.5% in the vehicle group, increased 19.0 ± 10.2% in presence of obestatin, and remained unchanged by ghrelin. Epinephrine-induced contractions were not affected by obestatin or ghrelin. EFS-elicited contractions were decreased 9.3 ± 3.2% by ghrelin. Basal tension of the iris sphincter decreased 21.7 ± 3.7% in presence of ghrelin (10−5 M), while that of the dilator decreased 14.1 ± 5.0% in presence of obestatin (10−5 M). Conclusion: This study suggests that obestatin potentiates the cholinergic contraction of the iris sphincter and relaxes the iris dilator muscles.

Identification of the ghrelin-GHSR 1 system and its influence in the modulation of induced ocular hypertension in rabbit and rat eyes.

Recent studies evidenced a decrease in ghrelins aqueous humor levels in patients with glaucoma. The goal of our investigation was to study the effect of the ghrelin-GHSR-1a system in the modulation of intraocular pressure in acute ocular hypertension models and its expression and distribution in ocular tissues. Two animal models of acute ocular hypertension were used to study the effect of the ghrelin-GHSR-1a system in the modulation of intraocular pressure: the rabbit and the rat. Ocular hypertension was induced by an intravitreal injection of 20% NaCl. Ghrelin or des-acyl ghrelin were delivered subconjunctivally and the intraocular pressure was assessed by a rebound tonometer that was calibrated for each species. In addition, we have studied the influence of nitric oxide and prostaglandins on ghrelins effect in the rabbit animal model. Finally, we determined by immunofluorescence the expression of ghrelin and GHSR-1 in the rats ocular tissue. Ghrelin decreased the intraocular pressure in both animal models (maximum decrease: 43.8±12.0% in the rabbit and 29.0±7.46% in the rat). In the rabbit, this effect was blunted in the presence of l-NAME and ketorolac. Des-acyl ghrelin only decreased the intraocular pressure in the rat (maximum decrease: 34.9±8.15%). Ghrelin expression was detected in the ciliary processes and GHSR-1 expression was detected in the trabecular meshwork and ciliary body. The ghrelin-GHSR-1 system is expressed in the anterior segment of the eye. Ghrelin and des-acyl ghrelin are responsible for a hypotensive effect in acute ocular hypertension animal models.