Preferential solvation and optical properties of eumelanin building blocks in binary mixture of methanol and water.

Employing a sequential quantum mechanical/molecular mechanical approach for polar protic solvents, we study the absorption spectrum of eumelanin building blocks including monomers, dimers, and tetramers in pure water and methanol and three water-methanol binary mixtures having water molar fractions (Xw = 0.25, 0.50, and 0.75). The binary mixture of solvents is a common situation in experiments, but theoretical studies are limited to the use of continuum models. Here, we use explicit solvent molecules, and specific solute-solvent interaction is analyzed and seen to play an important role. Effects of the electronic polarization of solute by the environment were included using a reliable iterative scheme. The results illustrate that the monomers, dimers, and tetramers are preferably solvated by methanol, but the composition of the mixture in the vicinity of the solute molecules is different from the bulk composition with a preferential microsolvation (hydrogen bonds) in water for most species considered. It is observed that the short-range electrostatic polarization effects of the hydrogen bonds lead to a slight blue shift of the excitation energies when the concentration of water in the mixture is enhanced. For the same species, there is an enhancement of the higher-energy absorption intensity caused by long-range electrostatic interactions with the environment and that the behavior of the experimental spectrum, which is characterized by a nearly monotonic decay from the ultraviolet to the infrared, is qualitatively reproduced by the superposition of the absorption spectra of monomers, dimers, and tetramers in the liquid phase.

Molecular dynamic simulations, GIAO-NMR and TD-DFT spectroscopy analyze for zwitterionic isoleucine (ILE)N , 1 ≤ N ≤ 6, in water solution.

In this article, we investigate the effects of the isoleucine (ILE)N amino acid chain growth, N = 1.0.6, the ILE conformational effect as well as the solvent presence on the electrical and magnetic spectroscopic properties when these compounds are in aqueous solution. Computational molecular dynamics simulations were performed to include the solvent medium and generate uncorrelated configurations involving solute-solvent structures. The charge point model for solvent was used to obtain the results for quantum mechanical calculation, in special DFT calculations, for (ILE)N structures. Our results for the magnetic shielding constant obtained via GIAO-DFT-NMR calculations show that there is evidence of a magnetic behavior that characterizes the number of peptide bonds and, therefore, how the N isoleucine polypeptide chain is composed. TD-DFT results also show an absorption band shift to larger wavelengths indicating a dependence on N growth.

15N NMR Shifts of Eumelanin Building Blocks in Water: A Combined Quantum Mechanics/Statistical Mechanics Approach.

Theoretical results for the magnetic shielding of protonated and unprotonated nitrogens of eumelanin building blocks including monomers, dimers, and tetramers in gas phase and water are presented. The magnetic property in water was determined by carrying out Monte Carlo statistical mechanics sampling combined with quantum mechanics calculations based on the gauge-including atomic orbitals approach. The results show that the environment polarization can have a marked effect on nitrogen magnetic shieldings, especially for the unprotonated nitrogens. Large contrasts of the oligomerization effect on magnetic shielding show a clear distinction between eumelanin building blocks in solution, which could be detected in nuclear magnetic resonance experiments. Calculations for a π-stacked structure defined by the dimer of a tetrameric building block indicate that unprotonated N atoms are significantly deshielded upon π stacking, whereas protonated N atoms are slightly shielded. The results stress the interest of NMR experiments for a better understanding of the eumelanin complex structure.

Hydration effects on the electronic properties of eumelanin building blocks.

Theoretical results for the electronic properties of eumelanin building blocks in the gas phase and water are presented. The building blocks presently investigated include the monomeric species DHI (5,6-dihydroxyindole) or hydroquinone (HQ), DHICA (5,6-dihydroxyindole-2-carboxylic acid), indolequinone (IQ), quinone methide (MQ), two covalently bonded dimers [HM ≡ HQ + MQ and IM ≡ IQ + MQ], and two tetramers [HMIM ≡ HQ + IM, IMIM ≡ IM + IM]. The electronic properties in water were determined by carrying out sequential Monte Carlo/time dependent density functional theory calculations. The results illustrate the role played by hydrogen bonding and electrostatic interactions in the electronic properties of eumelanin building blocks in a polar environment. In water, the dipole moments of monomeric species are significantly increased ([54-79]%) relative to their gas phase values. Recently, it has been proposed that the observed enhancement of the higher-energy absorption intensity in eumelanin can be explained by excitonic coupling among eumelanin protomolecules [C.-T. Chen et al., Nat. Commun. 5, 3859 (2014)]. Here, we are providing evidence that for DHICA, IQ, and HMIM, the electronic absorption toward the higher-energy end of the spectrum ([180-220] nm) is enhanced by long-range Coulombic interactions with the water environment. It was verified that by superposing the absorption spectra of different eumelanin building blocks corresponding to the monomers, dimers, and tetramers in liquid water, the behaviour of the experimental spectrum, which is characterised by a nearly monotonic decay from the ultraviolet to the infrared, is qualitatively reproduced. This result is in keeping with a "chemical disorder model," where the broadband absorption of eumelanin pigments is determined by the superposition of the spectra associated with the monomeric and oligomeric building blocks.

[Study of retinopathy of prematurity in a university hospital]. / Estudo da retinopatia da prematuridade em um hospital universitário.

PURPOSE: To evaluate the prevalence of retinopathy of prematurity (ROP) in newborns, classify the cases, describe the risk factors for disease and treatment. METHODS: A retrospective observational cross-sectional study including newborns with gestational age ≤ 32 weeks and/or weight ≤ 1,500 g admitted to the neonatal intensive care unit of the Hospital de Clínicas, Universidade Federal de Uberlândia (HC-UFU) during the period of July 2005 to June 2007. RESULTS: We analyzed 148 patients. In 66 (44.6%) ROP was detected; 82 (55.4%) showed no disease. The statistically significant risk factors were: birth weight (p=0.0001), gestational age (p=0.0001), mechanical ventilation (p=0.0001), blood transfusion (p=0.0001), and postconceptional age (PCA) (p=0.0001). Of the 66 premature infants with ROP, 77% were treated medically (follow-up with indirect ophthalmoscopy) and 23% required surgical treatment or photocoagulation. CONCLUSION: Based on the data above, the prevalence observed in this study was high. The development of ROP was inversely proportional to the weight and gestational age at birth.

Estudo da retinopatia da prematuridade em um hospital universitário / Study of retinopathy of prematurity in a university hospital

OBJETIVO: Avaliar a prevalência, sua classificação, descrição dos fatores de risco e tratamento da retinopatia da prematuridade (ROP) nos recém-nascidos. MÉTODOS: Estudo observacional transversal retrospectivo incluindo os recém-nascidos com idade gestacional <32 semanas e/ou peso <1.500 g internados na UTI neonatal do Hospital de Clínicas da Universidade Federal de Uberlândia (HC-UFU) durante o período de julho de 2005 a junho de 2007. RESULTADOS: Foram analisados 148 pacientes. Em 66 (44,6 por cento) detectou-se a ROP; 82 (55,4 por cento) não apresentaram a doença. Os fatores de risco estatisticamente significantes foram: peso ao nascimento (p=0,0001), idade gestacional (p=0,0001), ventilação mecânica (p=0,0001), transfusão sanguínea (p=0,0001), persistência do canal arterial (PCA) (p=0,0001). Dos 66 prematuros com ROP, 77 por cento foram tratados clinicamente (acompanhamento com oftalmoscopia indireta) e 23 por cento necessitaram de tratamento cirúrgico ou fotocoagulação a laser. CONCLUSÃO: Com base nos dados acima, a prevalência encontrada nesse estudo foi elevada. O desenvolvimento da ROP foi inversamente proporcional ao peso e à idade gestacional ao nascimento.

PURPOSE: To evaluate the prevalence of retinopathy of prematurity (ROP) in newborns, classify the cases, describe the risk factors for disease and treatment. METHODS: A retrospective observational cross-sectional study including newborns with gestational age < 32 weeks and/or weight < 1,500 g admitted to the neonatal intensive care unit of the Hospital de Clínicas, Universidade Federal de Uberlândia (HC-UFU) during the period of July 2005 to June 2007. RESULTS: We analyzed 148 patients. In 66 (44.6 percent) ROP was detected; 82 (55.4 percent) showed no disease. The statistically significant risk factors were: birth weight (p=0.0001), gestational age (p=0.0001), mechanical ventilation (p=0.0001), blood transfusion (p=0.0001), and postconceptional age (PCA) (p=0.0001). Of the 66 premature infants with ROP, 77 percent were treated medically (follow-up with indirect ophthalmoscopy) and 23 percent required surgical treatment or photocoagulation. CONCLUSION: Based on the data above, the prevalence observed in this study was high. The development of ROP was inversely proportional to the weight and gestational age at birth.

Silicone oil tamponade in 23-gauge transconjunctival sutureless vitrectomy.

PURPOSE: To describe 20 consecutive patients treated with 23-gauge transconjunctival sutureless vitrectomy and silicone oil tamponade for retinal detachments (RD) of different etiologies. METHODS: Prospective case series. Twenty patients with complex retinal detachment were submitted to a primary 23-gauge transconjunctival pars plana vitrectomy: rhegmatogenous retinal detachment with proliferative vitreoretinopathy (RRD + PVR) in 7 cases, diabetic tractional retinal detachment (DTRD) in 5 cases, giant retinal tear (GRT) in 2 cases, RRD with multiple tears in 2 cases, GRT + uveitis in 1 case, RRD + uveitis in 1 case, DTRD + RRD in 1 case, and RRD + PVR with intraocular foreign body (IOFB) in 1 case. Length of postoperative follow up ranged from 3 to 14 months. RESULTS: Final visual acuity ranged from 20/25 to hand motion. Postoperatively, none of the 20 eyes had hypotony or leakage of silicone oil through the sclerotomies. Seventeen out of 20 (85%) had improved vision. CONCLUSION: Silicone oil tamponade was demonstrated to be a feasible option in conjunction with 23-g transconjunctival sutureless vitrectomy to treat complex retinal detachment.

[Acute post-traumatic optic nerve avulsion: case report]. / Características da fase aguda da avulsão do nervo óptico pós-trauma: relato de caso.

Optic nerve avulsion is a rare, but devastating complication. In this condition, the optic nerve is forcibly disinserted from the retina, choroid, and vitreous, and the lamina cribrosa is retracted from the scleral rim. If the media are clear, the avulsion is easily diagnosed. The appearance of the fundus is striking, with a hole or cavity where the optic disc has retracted into its dural sheath. The complementary examinations are not very accurate for the diagnosis of this pathology and with some residual vision, opaque media, that occur in partial avulsion, the diagnosis may be mistaken or delayed. In this article we report a case of complete optic nerve avulsion examined at the Retina and Vitreous Department of the "Hospital das Clínicas" of the Federal University of Uberlândia - MG - Brazil.

Características da fase aguda da avulsão do nervo óptico pós-trauma: relato de caso / Acute post-traumatic optic nerve avulsion: case report

A avulsão do nervo óptico representa uma entidade rara, levando a resultados devastadores na maioria dos casos e com prognóstico reservado. A presença de meios translúcidos possibilita, na maioria das vezes, diagnósticos acurados, mostrando a fundoscopia tipicamente uma cavidade localizada no local da retração do disco óptico para sua bainha dural. Embora exames complementares raramente sejam necessários para o diagnóstico desta afecção, quadros clínicos associados a graus variados de turvação de meios dióptricos e algum grau residual da visão, como nas roturas parciais, podem levar à dificuldade do diagnóstico e mesmo retardar o processo terapêutico. Neste artigo, relatamos a fase aguda de um caso típico de avulsão completa do nervo óptico, examinado no Serviço de Retina e Vítreo do Hospital de Clínicas da Universidade Federal de Uberlândia - MG.

Optic nerve avulsion is a rare, but devastating complication. In this condition, the optic nerve is forcibly disinserted from the retina, choroid, and vitreous, and the lamina cribrosa is retracted from the scleral rim. If the media are clear, the avulsion is easily diagnosed. The appearance of the fundus is striking, with a hole or cavity where the optic disc has retracted into its dural sheath. The complementary examinations are not very accurate for the diagnosis of this pathology and with some residual vision, opaque media, that occur in partial avulsion, the diagnosis may be mistaken or delayed. In this article we report a case of complete optic nerve avulsion examined at the Retina and Vitreous Department of the "Hospital das Clínicas" of the Federal University of Uberlândia - MG - Brazil.

Vitrectomia farmacológica e descolamento do vítreo posterior / Pharmacological vitreolysis and posterior vitreous detachment

O vítreo exerce papel crucial na patogênese de vários distúrbios vitreoretinianos. As alterações moleculares e estruturais fisiológicas do gel vítreo evoluem para a liquefação e culminam com o descolamento do córtex vítreo posterior (DVP). A ocorrência do descolamento do vítreo posterior influencia positivamente o prognóstico de pacientes diabéticos, com maculopatias e vasculopatias. Abordaremos o conceito da vitrectomia farmacológica que se refere ao uso de agentes que alteram a organização molecular do vítreo, num esforço de reduzir ou eliminar seu papel na gênese de doenças vítreo-retinianas, sendo o seu objetivo final, o descolamento total do vítreo posterior. Vários agentes têm sido estudados durante a última década, porém, existem várias limitações na aplicabilidade clínica destes compostos. Nesse artigo de revisão, iremos abordar os diferentes agentes e os seus mecanismos de ação sobre a matriz extracelular e a interface vítreo-retiniana.

Photodynamic therapy-treated choroidal neovascular membrane secondary to toxoplasmic retinochoroiditis.

PURPOSE: To report the result of photodynamic therapy with Visudyne (PDT) on a child with choroidal neovascular membrane (CNV) secondary to toxoplasmic retinochoroiditis. METHODS: An 11-year-old child with a unilateral lowering of visual acuity secondary to an extrafoveal choroidal neovascular membrane was submitted to PDT. RESULTS: One week after PDT, the patient's vision had improved from 10/160 to 20/70, with marked improvement in the angiographic findings. The CNV evolved with decreasing of leakage until 45 days after operation, when it regressed to a chorioretinal scar formation, with final vision of 20/25. CONCLUSION: PDT promoted an early recovery of visual acuity in an eye with choroidal neovascularization secondary to toxoplasmic retinochoroiditis.

Facoemulsificaçäo: resultados e complicaçöes nos primeiros 100 olhos / Phacoemulsification: outcomes and complications in the first 100 eyes

Analizar o resultado visual e as complicaçöes dos 100 primeiros olhos submetidos á facoemulsificaçäo, realizados no Hospital do Servidor Público Estadual Säo Paulo (HSPE), por cirurgiöes iniciantes nesta técnica. Pacientes e Método: As 100 primeiras cirurgias de facoemulsificaçäo realizadas por 05 cirurgiöes, em pacientes do ambulatório de Catarata do HSPE, foram analisadas. A técnica utilizada foi incisäo tunelizada, capsulorrexis curvilínea contínua anterior, facoemulsificaçäo do núcleo, usando um aparelho de bomba peristáltica, e implante de lente intra-ocular, sob anestasia com bloqueio peribulbar. Resultados: As complicaçöes ocorreram em 15,2 por cento dos olhos, sendo rotura de cápsula posterior sem perda vítrea em 8,7 por cento, perda vítrea em 5,4 por cento e luxaçäo de núcleo no vítreo em 1 olho. Em 96,7 por cento dos olhos foram implantados LIO de c