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1.
Trop Anim Health Prod ; 52(5): 2667-2675, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32474755

RESUMO

This study investigated the effects of dietary supplementation with vitamin E (vit. E), selenium yeast (Se yeast), or both on egg incubation response, embryonic development, keet quality, and posthatch growth of helmeted guinea fowls. Two hundred and forty 24-week old helmeted guinea fowl hens (average weight 1.75 + 0.22 kg) and cocks (average weight 2.15 + 0.20 kg) were assigned into 24 pens; each pen housed 10 hens and 2 cocks. There were four dietary treatments consisting of a basal diet (control), basal diet supplemented with vit. E (30 IU/kg), Se yeast (0.3 mg/kg Se), or both. Six pens were assigned to each treatment. Egg incubation response were estimated using 504 settable eggs sampled from each treatment collected during 15 to 17 weeks in lay. A total of 72 fertile eggs sampled from each treatment were used for the estimation of embryonic development. Quality of day-old keets hatched was scored based on physical conditions, while posthatch growth was measured for 21 days. Guinea fowl breeders fed diet supplemented with both vit. E and Se yeast produced the highest (P < 0.05) number of fertile eggs, percentage fertility, number of hatchlings, hatchability of total eggs, and hatchability of fertile eggs. Supplementation with vit. E + Se yeast resulted in the heaviest (P < 0.05) embryo weight, relative embryo weight, least (P < 0.05) yolk sac weight, and relative yolk sac weight on 25 days of incubation. Hatchlings from breeders fed diet supplemented with Se yeast and vit. E + Se yeast showed normal swallowed yolk. Supplementation of maternal diet with vit. E, Se yeast, and vit. E + Se yeast resulted in improved (P < 0.05) feed conversion ratio of subsequent hatchlings during 1 to 7-day posthatch growth. It can be concluded that dietary supplementation of vit. E + Se yeast in guinea fowl breeders resulted in improved egg fertility, hatchability, heavier embryo weights, hatchlings of good quality, and improved posthatch growth during the first 7 days.

2.
J Therm Biol ; 87: 102468, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32001017

RESUMO

Preferred temperature (Tpref) has been measured in over 100 species of aquatic and 300 species of terrestrial ectotherms as a metric for assessing behavioural thermoregulation in variable environments and, as such, has been linked to ecological processes ranging from individual behaviour to population and community dynamics. Due to the asymmetric shape of performance curves, Tpref is typically lower than the optimal temperature (Topt, where physiological performance is at its peak), and the degree of this mismatch increases with variability in Tb. Intertidal ectotherms experience huge variability in Tb on a daily basis and therefore provide a good system to test whether the relationship between Tpref and variation in Tb holds in more extreme environments. A review of the literature, however, only revealed comparisons between Tpref and Topt for five intertidal species and measurements of Tpref for 23 species. An analysis of this limited literature for intertidal ectotherms showed a positive relationship between acclimation temperature and Tpref. There was, however, great variation in the methodologies employed to make these assessments. Factors contributing to behavioural thermoregulation in intertidal ectotherms including small body size; low mobility; interactions among individuals; endogenous clocks; metabolic effects; thermal sensitivity; sampling of the thermal environment and recent acclimation history were considered to varying degrees when measuring Tpref, confounding comparisons between species. The methodologies used to measure Tpref in intertidal ectotherms were reviewed in light of each of these factors, and methodologies proposed to standardize approaches. Given the theoretical predictions about the relationships between Tpref and variability in Tb, the spatial and temporal thermal variability experienced by intertidal ectotherms provides numerous opportunities to test these expectations if assessed in a standardized manner, and can potentially provide insights into the value of behavioural thermoregulation in the more thermally variable environments predicted to occur in the near future.

3.
Radiat Prot Dosimetry ; 174(3): 322-336, 2017 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-27881792

RESUMO

A group of Aboriginal people was camped at Wallatinna in South Australia, ~170 km downwind from Emu Field, where an atomic test (the Totem 1 test) was carried out at 07.00 on 15 October 1953 local time (21.30 on 14 October 1953 GMT (Greenwich Mean Time)). They left the camp ~24 hours later. These people stated that a phenomenon that has become known as a 'black mist' rolled through their camp site ~5 hours after detonation and that some of them subsequently became sick, displaying skin reddening and nausea. They feared that the sickness was a result of exposure to high levels of radiation. The purpose of this paper is to determine if these people could have received ionising radiation doses high enough to cause the symptoms displayed. The methodology used for the dose estimates is described in the paper. The exposure modes considered were external exposure due to the passage of a contaminated plume over the camp site, inhalation of material from this plume, external exposure from material deposited on the ground as the plume passed, and consumption of contaminated food and water. The contaminants considered in the airborne cloud and the ground plume were fission products and unburnt plutonium from the nuclear detonation, and neutron activation products caused by vaporisation of the tower used to position the weapon. The source was approximated by a line source. An upper estimate of the effective doses received is ~4 mSv, which is well below the level at which acute radiation effects are observed. This estimate is consistent with earlier assessments, which did not consider inhalation of the contribution from neutron activation products.


Assuntos
Armas Nucleares , Grupo com Ancestrais Oceânicos , Doses de Radiação , Exposição à Radiação , Humanos , Plutônio , Radiação Ionizante , Austrália do Sul
4.
J Microsc ; 244(1): 1-20, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21812778

RESUMO

Mycelial morphology is a critically important process property in industrial fermentations of filamentous microorganisms, as particular phenotypes are associated with maximum productivity. The morphological form that develops in a given process results from the combination of various environmental factors, together with the genotype of the organism itself. The design of systems capable of rapidly and accurately characterising morphology within a given process represents a significant challenge to biotechnologists, as the complex phenotypes that are manifested are often not easily quantified. Over the last two decades, the proliferation of high-power personal computers and high-resolution digital cameras has enabled scientists to apply digital image analysis to this challenge. Although several fully automated systems have been designed for this purpose, manual analysis of images is still commonplace, together with qualitative, subjective descriptions of morphologies. This review describes the complex morphologies that can develop in fermentations of filamentous microbes and the application of microscopy and image analysis techniques to the quantification of such structures.


Assuntos
Fungos/citologia , Processamento de Imagem Assistida por Computador/métodos , Microbiologia Industrial/métodos , Microscopia/métodos , Automação/métodos , Fermentação
5.
Eye (Lond) ; 22(10): 1263-6, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18292789

RESUMO

PURPOSE: To discuss the evolution and current status of 25-, 23-, and 20-gauge vitrectomy instrumentation. METHODS: Literature review. RESULTS: There are multiple small case series describing the surgical techniques, clinical outcomes, and complications associated with 25- and 23-gauge vitrectomy. These studies suggest that small-gauge vitrectomy may shorten operating time, improve patient comfort, and speed visual recovery. However, increased complication rates involving hypotony and endophthalmitis have been reported. There are no level 1 evidence-based studies comparing the efficacy and safety of 25-, 23-, and 20-gauge vitrectomy. CONCLUSION: 25- and 23-gauge vitrectomy techniques may shorten operating time, improve patient comfort, and speed visual recovery. However, larger and better designed evidence-based studies are required to better understand relative values of 25-, 23-, and 20-gauge vitrectomy.


Assuntos
Vitrectomia/instrumentação , Corpo Vítreo/cirurgia , Endoftalmite/etiologia , Desenho de Equipamento , Humanos , Vitrectomia/efeitos adversos , Vitrectomia/tendências
8.
Graefes Arch Clin Exp Ophthalmol ; 244(8): 996-1002, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16365737

RESUMO

BACKGROUND: The generation of an atraumatic posterior vitreous detachment (PVD), a common goal in vitreoretinal surgery, is a challenge, particularly in children and young trauma patients. Plasmin has been proposed as an adjunct to vitrectomy to enzymatically generate a PVD. Low doses of streptokinase-activated plasmin were tested in human pilot studies. This dose-escalation study assesses the safety range of intravitreal human streptokinase-plasmin in rabbits. METHODS: Plasminogen was isolated from human plasma by affinity chromatography, followed by activation with streptokinase (1:1), to generate the streptokinase-plasmin complex. Enzyme doses from 0.1-7 activity units (AU, in 0.1 ml) were injected into the mid-vitreous of 35 eyes; six control eyes were injected with balanced salt solution (BSS, 0.1 ml). Thirty minutes after injection, a two-port vitrectomy was performed. Fundus and slit lamp examinations were performed on days 1 and 7. On days 2 and 7, bright flash electroretinography was performed and compared with preoperative recordings. Some animals receiving higher doses of streptokinase-plasmin (1-7 AU) were followed clinically and with electroretinography for up to 9 months. RESULTS: A mild-to-moderate inflammatory response was seen in both control and plasmin-treated eyes on day 1, but had disappeared completely by day 7 in most eyes. In the 7 AU group, inflammation was stronger and more protracted. Two of three eyes from this group developed wrinkling of the medullary rays; one of them showed discoloration and traction at the medullary rays in the late follow-up. Electroretinograms (ERGs) of vitrectomized control eyes showed the following changes from preoperative values: 48 h, a-wave -11.10% [no significant (n.s.)], b-wave -14.62% (P=0.046); 7 days, a-wave +9.18% (n.s.), b wave +11.69% (n.s.). For the enzyme-treated eyes: 48 h: a-wave -20.43% (P<0.001), b-wave -9.57% (p<0.001); 7 days: a wave -14.21% (P<0.001), b-wave +2.48% (P<0.001). There was no evidence of dose-dependent ERG changes in enzyme-treated eyes at doses up to 5 AU. Groups of up to 3 AU were investigated by light and transmission electron microscopy, without evidence of toxicity. CONCLUSION: Streptokinase-plasmin doses up to 3 AU were found to be safe when injected into rabbit eyes followed by vitrectomy.


Assuntos
Plasminogênio/administração & dosagem , Estreptoquinase/administração & dosagem , Vitrectomia/métodos , Descolamento do Vítreo/cirurgia , Animais , Cromatografia de Afinidade , Terapia Combinada , Combinação de Medicamentos , Eletrorretinografia , Humanos , Injeções , Estimulação Luminosa , Plasminogênio/efeitos adversos , Plasminogênio/isolamento & purificação , Coelhos , Retina/efeitos dos fármacos , Retina/fisiologia , Estreptoquinase/efeitos adversos , Vitrectomia/efeitos adversos , Corpo Vítreo/efeitos dos fármacos
10.
Br J Ophthalmol ; 88(8): 1055-9, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15258024

RESUMO

AIMS: To study the effectiveness of indocyanine green mediated photothrombosis in the management of predominantly classic subfoveal choroidal neovascularisation associated with age related macular degeneration. METHODS: Prospective, non-comparative, interventional case series of nine patients with predominantly classic subfoveal choroidal neovascularisation secondary to age related macular degeneration who declined photocoagulation or verteporfin photodynamic therapy. Patients were submitted to one or more treatments with an intravenous injection of a small volume of high concentration indocyanine green solution followed by low irradiance, large spot 810 nm continuous laser application via a transpupillary approach. Main outcome measures were change in best corrected visual acuity and macular exudative manifestations. RESULTS: After 12 months of follow up, the final best corrected visual acuity was the same (plus or minus two ETDRS lines) in five eyes (55%), improved more than two ETDRS lines in three eyes (33%), and worsened by more than two lines in the remaining eye. The improved vision was probably related to partial or complete restoration of the macular architecture as a result of fluid resolution, whereas the worsened vision was primarily the result of treatment failure in achieving substantial choroidal neovascular occlusion. There were no complications related to the procedure. CONCLUSION: Indocyanine green mediated photothrombosis may be an effective alternative treatment for predominantly classic subfoveal choroidal neovascularisation caused by age related macular degeneration.


Assuntos
Neovascularização de Coroide/cirurgia , Verde de Indocianina/uso terapêutico , Fotocoagulação , Degeneração Macular/complicações , Fármacos Fotossensibilizantes/uso terapêutico , Idoso , Idoso de 80 Anos ou mais , Neovascularização de Coroide/tratamento farmacológico , Neovascularização de Coroide/etiologia , Terapia Combinada/métodos , Feminino , Angiofluoresceinografia , Humanos , Degeneração Macular/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Resultado do Tratamento , Acuidade Visual/fisiologia
11.
Mar Environ Res ; 58(1): 83-93, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15046947

RESUMO

The gastropod limpet, Cellana grata, is common on moderately exposed to exposed Hong Kong rocky shores. On the basis of the existing literature on trace metal contamination in Hong Kong, four sites were identified, representative of highly polluted (Aberdeen and Lei Yue Mun) and clean (Cape d'Aguilar and Clear Water Bay) conditions. Limpets from the two polluted sites showed similar, but significantly higher body concentrations of copper than limpets from the two clean sites, which were also similar. Non-invasive measurements of cardiac activity of limpets from the four sites showed between site differences in baseline heart rates under standard seawater, irrespective of pollution level. When acutely exposed to water borne copper (2 h, 0.5+/-0.06 SD ppm), however, limpets from clean sites showed a significantly higher increase in inter-beating time (bradycardia) than those from polluted sites. These results highlight the potential use of cardiac activity to assess the exposure of natural populations of limpets to trace metal pollution.


Assuntos
Cobre/toxicidade , Monitoramento Ambiental , Frequência Cardíaca/efeitos dos fármacos , Caramujos/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Hong Kong
12.
Artigo em Inglês | MEDLINE | ID: mdl-12679876

RESUMO

The degu (Octodon degus) is a diurnal rodent, native to Chile. Basic features of vision and visual organization in this species were examined in a series of anatomical, electrophysiological and behavioral experiments. The lens of the degu eye selectively absorbs short-wavelength light and shows a progressive increase in optical density as a function of age. Electroretinograms recorded using a flicker-photometric procedure reveal three spectral mechanisms: a rod with peak sensitivity of about 500 nm and two types of cone having respective spectral peaks of about 362 nm and 507 nm. Opsin antibody labeling was used to determine the retinal distributions of the three receptor types. A total of about one-third of the approximately 9 million photoreceptors of the degu retina are cones with the two types (507 nm/362 nm) represented in a ratio of about 13:1. The contributions to vision of all three receptor types were examined in a series of behavioral experiments. A consistent feature of both the electrophysiological and behavioral results is that relatively high levels of light adaptation are required to effect the full transition from rod-based to cone-based vision. In behavioral tests degus were shown to be able to make color discriminations between ultraviolet and visible lights.


Assuntos
Adaptação Ocular/fisiologia , Visão Ocular/fisiologia , Envelhecimento , Animais , Sensibilidades de Contraste/fisiologia , Discriminação Psicológica , Eletrorretinografia/métodos , Potenciais Evocados Visuais , Feminino , Cristalino/fisiologia , Masculino , Estimulação Luminosa , Psicofísica/métodos , Células Fotorreceptoras Retinianas Cones/anatomia & histologia , Células Fotorreceptoras Retinianas Cones/metabolismo , Células Fotorreceptoras Retinianas Bastonetes/anatomia & histologia , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Opsinas de Bastonetes/metabolismo , Roedores , Limiar Sensorial/fisiologia , Espectrofotometria Ultravioleta , Raios Ultravioleta
13.
Ophthalmology ; 108(12): 2273-8, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11733270

RESUMO

PURPOSE: To determine visual outcomes and the incidence of retinal detachment in eyes presenting with posterior vitreous separation and dense fundus-obscuring vitreous hemorrhage. DESIGN: Retrospective consecutive noncomparative interventional case series. PARTICIPANTS: Thirty-six eyes (15 right eyes and 21 left eyes) of 34 patients (18 female and 16 male) ranging in age from 42 to 94 years. Mean follow-up was 14 months. METHODS: A comparison of the best-corrected initial visual acuities versus final visual acuities after spontaneous resolution of vitreous hemorrhage or surgical intervention. The number of eyes that were found to have retinal tears or that had a rhegmatogenous retinal detachment develop was documented. Logarithm of the minimum angle of resolution-converted visual acuities was used for comparison. Categorical data were analyzed by Fisher's exact test, and population means were compared by Student's t test. MAIN OUTCOME MEASURES: Final mean visual acuities, number of eyes with at least one retinal tear, location of retinal tears, number of eyes that had retinal detachment develop, and the number of eyes repaired with scleral buckling surgery and/or pars plana vitrectomy. RESULTS: Twenty-four of 36 eyes (67%) were found to have at least one retinal break (range, 0-4 breaks), with 88% of breaks located in the superior retina. Eleven eyes (31%) had more than one retinal break. Fourteen of 36 eyes (39%) had a rhegmatogenous retinal detachment develop that was repaired with pars plana vitrectomy and scleral buckling. An additional 14 eyes (39%) underwent vitrectomy for nonclearing vitreous hemorrhage. The incidence of retinal detachment in eyes with a history of retinal detachment in the contralateral eye was 75% (P = 0.04). Seven of 14 eyes (50%) with retinal detachment had coexisting proliferative vitreoretinopathy. Most retinal breaks and detachments occurred in emmetropic or myopic eyes. For all 36 eyes the mean preoperative visual acuity was 20/1233, and the mean final visual acuity was 20/62 (P < 0.0001). Eyes that had a macula-off retinal detachment develop had worse final visual outcomes (20/264; P = 0.01), as did eyes that had proliferative vitreoretinopathy develop (20/129; P = 0.04). CONCLUSIONS: Acute, spontaneous, nontraumatic posterior vitreous separation with dense fundus-obscuring vitreous hemorrhage is associated with a high incidence of retinal tears and detachment. Close follow-up with clinical examination and ultrasonography is necessary, because many of these eyes may eventually require surgical intervention. Aggressive management with early vitrectomy should be considered when there is a history of retinal detachment in the contralateral eye.


Assuntos
Descolamento Retiniano/etiologia , Perfurações Retinianas/etiologia , Acuidade Visual , Descolamento do Vítreo/complicações , Hemorragia Vítrea/complicações , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Fundo de Olho , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Descolamento Retiniano/cirurgia , Perfurações Retinianas/cirurgia , Estudos Retrospectivos , Recurvamento da Esclera , Resultado do Tratamento , Vitrectomia , Vitreorretinopatia Proliferativa/etiologia , Descolamento do Vítreo/cirurgia , Hemorragia Vítrea/cirurgia
14.
J Comput Biol ; 8(5): 523-47, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11694181

RESUMO

Finding optimal three-dimensional molecular configurations based on a limited amount of experimental and/or theoretical data requires efficient nonlinear optimization algorithms. Optimization methods must be able to find atomic configurations that are close to the absolute, or global, minimum error and also satisfy known physical constraints such as minimum separation distances between atoms (based on van der Waals interactions). The most difficult obstacles in these types of problems are that 1) using a limited amount of input data leads to many possible local optima and 2) introducing physical constraints, such as minimum separation distances, helps to limit the search space but often makes convergence to a global minimum more difficult. We introduce a constrained global optimization algorithm that is robust and efficient in yielding near-optimal three-dimensional configurations that are guaranteed to satisfy known separation constraints. The algorithm uses an atom-based approach that reduces the dimensionality and allows for tractable enforcement of constraints while maintaining good global convergence properties. We evaluate the new optimization algorithm using synthetic data from the yeast phenylalanine tRNA and several proteins, all with known crystal structure taken from the Protein Data Bank. We compare the results to commonly applied optimization methods, such as distance geometry, simulated annealing, continuation, and smoothing. We show that compared to other optimization approaches, our algorithm is able combine sparse input data with physical constraints in an efficient manner to yield structures with lower root mean squared deviation.


Assuntos
Algoritmos , Modelos Moleculares , Proteínas/química , Estrutura Molecular , RNA de Transferência de Fenilalanina/química
15.
Ophthalmology ; 108(10): 1902-5; discussion 1905-6, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11581070

RESUMO

PURPOSE: This is a pilot study to assess the use of autologous plasmin enzyme (APE) as an adjunct to vitreous surgery in eyes with advanced diabetic retinopathy. DESIGN: Prospective noncomparative interventional case series. PARTICIPANTS: Seven patients with advanced diabetic retinopathy selected at random from our practice population. METHODS: Seven eyes were treated with APE as an adjunct to standard vitreous surgery. Six eyes had macular tractional retinal detachments, and one eye had refractory macular edema. Three fellow eyes had standard vitreous surgery performed for macular tractional retinal detachments without APE. All 10 eyes had macular edema and background diabetic retinopathy. MAIN OUTCOME MEASURES: The main outcome measures included induction of a posterior vitreous detachment, retinal reattachment, improvement in visual acuity, and resolution of macular edema. RESULTS: All seven APE-treated eyes achieved spontaneous or easy removal of the posterior hyaloid including one eye that had vitreoschisis over areas of detached retina. All eyes treated with APE had resolution of intraretinal edema. Retinas of all eyes treated with APE were reattached. The three fellow eyes were treated by vitreous surgery without APE. Two of the three fellow eyes had reattached retinas, but none had resolution of intraretinal edema without further focal photocoagulation treatment. Mean visual acuity improvement was 0.7 logarithm of the minimum angle of resolution (LogMAR) units in APE-treated eyes and 0.1 LogMAR units in eyes without APE. The average follow-up period was 14 months. CONCLUSIONS: This pilot study suggests that APE may be beneficial in the surgical management of diabetic retinopathy.


Assuntos
Retinopatia Diabética/tratamento farmacológico , Retinopatia Diabética/cirurgia , Fibrinolisina/uso terapêutico , Fibrinolíticos/uso terapêutico , Vitreorretinopatia Proliferativa/tratamento farmacológico , Vitreorretinopatia Proliferativa/cirurgia , Adulto , Idoso , Quimioterapia Adjuvante , Feminino , Humanos , Fotocoagulação , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Estudos Prospectivos , Resultado do Tratamento , Acuidade Visual , Vitrectomia , Corpo Vítreo/efeitos dos fármacos
16.
Ophthalmology ; 108(9): 1647-53, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11535465

RESUMO

PURPOSE: To describe the results of retinal tears and rhegmatogenous retinal detachments (RD) in adults with retinopathy of prematurity (ROP). DESIGN: Noncomparitive interventional case series. METHODS: Retrospective cohort of 216 eyes of 108 patients, 15 years or older, followed for up to 23 years (median, 6.2 years). RESULTS: One eye was initially seen with an RD, and during follow-up 30 eyes had an RD develop. An additional surgical procedure was required in 7 of the 31 eyes (23%) with an RD. Four eyes were initially seen with retinal tears, and during follow-up 19 eyes had a retinal tear develop. Seven of the 23 eyes (30%) with a retinal tear had initial repair fail. Eyes with minimal cicatricial changes from ROP were still at high risk for tears and detachments developing. Eighty percent of eyes with retinal tears and 60% of eyes with an RD that started with vision >20/60 maintained that level of vision at the final examination. CONCLUSION: In patients with a history of premature birth, features of fundus examinations do not correlate with the occurrence of a retinal tear or RD. Repair of a tear or detachment in such a patient is more likely to require multiple procedures but can still be associated with good visual results. Physicians should consider widespread relief of vitreoretinal traction for a tear or detachment in any patient with a history of premature birth.


Assuntos
Descolamento Retiniano/etiologia , Perfurações Retinianas/etiologia , Retinopatia da Prematuridade/complicações , Acuidade Visual , Adolescente , Adulto , Peso ao Nascer , Criança , Pré-Escolar , Feminino , Seguimentos , Idade Gestacional , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Descolamento Retiniano/cirurgia , Perfurações Retinianas/cirurgia , Estudos Retrospectivos , Fatores de Risco , Recurvamento da Esclera , Resultado do Tratamento , Vitrectomia
17.
Arch Biochem Biophys ; 392(2): 295-302, 2001 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-11488605

RESUMO

When hydrogen peroxide (H2O2) was provided as the only substrate for horseradish peroxidase C (HRP-C) the catalase-like emission of oxygen gas was observed. The reaction was favored at neutral compared to acidic pH. Addition of the superoxide radical scavengers tetranitromethane (TNM) or superoxide dismutase (SOD) increased activity. TNM's effect was concentration dependent but SOD's was not, indicating that only some of the superoxide generated was released into solution. Manganous ions (Mn2+) react with superoxide radicals to regenerate H2O2 but not oxygen; when added to the reaction medium oxygen production was reduced but not abolished. The effect was essentially concentration independent, suggesting that most oxygen was produced enzymatically and not by chemical disproportionation of superoxide. The catalase-like activities of some site-directed mutants of HRP-C suggest that active site residues histidine 42 and arginine 38 are influential in determining this activity. A clear correlation also existed between catalase activity and the enzymes' resistance to inactivation by H2O2. Computer simulation of a reaction scheme that included catalase-like activity agreed well with experimental data.


Assuntos
Catalase/química , Peroxidase do Rábano Silvestre/metabolismo , Oxigênio/metabolismo , Arginina/química , Catalase/metabolismo , Catálise , Simulação por Computador , Escherichia coli/metabolismo , Depuradores de Radicais Livres/metabolismo , Histidina/química , Peróxido de Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Íons , Cinética , Manganês/metabolismo , Modelos Químicos , Mutagênese Sítio-Dirigida , Superóxido Dismutase/metabolismo , Tetranitrometano/metabolismo , Fatores de Tempo
18.
J Exp Biol ; 204(Pt 14): 2439-46, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11511659

RESUMO

Rats (Rattus norvegicus) have two classes of cone, one containing an ultraviolet (UV)-sensitive photopigment and the other housing a pigment maximally sensitive in the middle (M) wavelengths of the visible spectrum. The manner in which signals from these two cone types contribute to rat vision was investigated through recordings of a gross electrical potential (the electroretinogram, ERG) and behavioral discrimination tests. Spectral sensitivity functions obtained from both types of measurement indicate clear contributions from each of the cone classes, but there is a marked enhancement of the relative sensitivity to UV light in the behavioral index; for instance, under some photopic test conditions, rats are approximately equally sensitive to middle-wavelength and UV lights. In adaptation tests, thresholds for UV and M lights were found to be differentially elevated in the presence of chromatic adapting backgrounds, thus providing the possibility that signals from the two cones could be used by the rat visual system to support color discriminations. Evidence of dichromatic color vision in the rat was subsequently obtained from tests of wavelength discrimination.


Assuntos
Luz , Células Fotorreceptoras Retinianas Cones/fisiologia , Raios Ultravioleta , Visão Ocular/fisiologia , Adaptação Ocular/fisiologia , Animais , Comportamento Animal , Percepção de Cores/fisiologia , Discriminação Psicológica , Eletrorretinografia , Ratos , Ratos Long-Evans , Limiar Sensorial
19.
Phys Rev Lett ; 86(21): 4934-7, 2001 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-11384385

RESUMO

The spectrum of the luminescence emitted at the collapse of single laser-induced bubbles in water is measured for different maximum bubble radii. Bubbles as large as 2 mm show a molecular OH(*) band at 310 nm in the spectrum, which otherwise can be fitted approximately with a blackbody curve at a temperature of 7800 K. This finding provides a connection between the light emission of single bubbles and multibubble sonoluminescence, since in the latter case the same molecular band is observed. Surface instabilities are observed in the larger bubbles, and may be connected with the OH(*) emission.

20.
Retina ; 21(3): 226-9, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11421011

RESUMO

PURPOSE: To describe acquired ocular toxoplasmosis in deer hunters. METHODS AND RESULTS: The authors describe five young men presenting with flu-like symptoms followed by visual loss due to a unilateral, focal necrotizing retinitis. All five men gave a history of ingesting undercooked or uncooked venison. All five had elevated toxoplasma serology, and all five improved clinically with an antitoxoplasma regimen. CONCLUSION: In previously healthy young men, flu-like symptoms associated with visual loss and retinitis should prompt questioning about hunting and raw game meat ingestion, especially when toxoplasmosis is suspected.


Assuntos
Cervos/parasitologia , Parasitologia de Alimentos , Carne/parasitologia , Síndrome de Necrose Retiniana Aguda/parasitologia , Toxoplasmose Ocular/etiologia , Adolescente , Adulto , Animais , Anticorpos Antiprotozoários/análise , Antiprotozoários/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Síndrome de Necrose Retiniana Aguda/diagnóstico , Síndrome de Necrose Retiniana Aguda/tratamento farmacológico , Toxoplasma/imunologia , Toxoplasmose Ocular/diagnóstico , Toxoplasmose Ocular/tratamento farmacológico , Transtornos da Visão/diagnóstico , Transtornos da Visão/tratamento farmacológico , Transtornos da Visão/parasitologia , Acuidade Visual
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