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1.
J Dairy Sci ; 103(3): 2743-2755, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31882220

RESUMO

Our objectives were to test the efficacy of intravaginal (IVG) administration of PGF2α to induce corpus luteum (CL) regression, compare circulating progesterone (P4) profiles in cows receiving IVG versus intramuscular (IM) treatment with PGF2α, and evaluate reproductive outcomes. Lactating Holstein cows were synchronized using a Double-Ovsynch protocol [GnRH, 7 d later PGF2α, 3 d later GnRH, 7 d later GnRH, 7 d later PGF2α, 1 d later PGF2α, 32 h later GnRH, 16 to 20 h timed artificial insemination (TAI)] to receive TAI at 67 ± 3 d in milk. Seven days after the first GnRH treatment (time 0), cows with at least 1 visible CL ≥15 mm were blocked by parity and randomly assigned to a treatment that consisted of IM injection (IM-PGF; n = 201) or IVG instillation (IVG-PGF; n = 201) of PGF2α. Cows in IM-PGF received a single 25-mg dose of PGF2α (dinoprost tromethamine) intramuscularly. Cows in IVG-PGF received two 25-mg doses of PGF2α 12 h apart delivered through a catheter in the cranial portion of the vagina. Blood samples were collected at 0, 12, 48, and 72 h after treatment. Ovulation to the first GnRH of Double-Ovsynch was determined through transrectal ultrasonography. Only cows with P4 ≥1 ng/mL (functional CL) at time 0 (IM-PGF = 169; IVG-PGF = 179) were included in the analyses. Binary and quantitative data were analyzed by logistic regression and ANOVA with repeated measures, respectively. Results are presented as least squares means. Concentrations of P4 and the proportion of cows with a new CL at time 0 did not differ. Overall, the proportion of cows with CL regression using 1 ng of P4/mL (IM-PGF = 89.0%; IVG-PGF = 86.7%) or 0.5 ng of P4/mL (IM-PGF = 82.2%; IVG-PGF = 82.1%) as the cutoff did not differ. Concentrations of P4 were affected by treatment, time, and treatment × time interaction. Cows in IVG-PGF had greater mean P4 at 12 h than cows in IM-PGF. Mean P4 did not differ at 48 or 72 h after treatment. The proportion of cows with estrus recorded within 3 d of treatment (IM-PGF = 45.4%; IVG-PGF = 48.9%), ovulation risk after treatment (IM-PGF = 88.5%; IVG-PGF = 85.1%), and pregnancies per artificial insemination after TAI (IM-PGF = 51.5%; IVG-PGF = 57.8%) did not differ. We concluded that 2 IVG doses of 25 mg of PGF2α 12 h apart were as effective as a single 25-mg IM dose of PGF2α for inducing luteal regression in lactating dairy cattle.


Assuntos
Bovinos/fisiologia , Dinoprosta/análogos & derivados , Luteólise/efeitos dos fármacos , Ocitócicos/administração & dosagem , Reprodução , Administração Intravaginal , Animais , Dinoprosta/administração & dosagem , Estro/efeitos dos fármacos , Sincronização do Estro , Feminino , Hormônio Liberador de Gonadotropina/administração & dosagem , Injeções Intramusculares/veterinária , Inseminação Artificial/veterinária , Lactação , Ovulação/efeitos dos fármacos , Paridade , Gravidez , Progesterona/sangue , Distribuição Aleatória
2.
J Stroke Cerebrovasc Dis ; 29(11): 105314, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32951959

RESUMO

BACKGROUND AND PURPOSE: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is associated with stroke. The role of sex on stroke outcome has not been investigated. To objective of this paper is to describe the characteristics of a diverse cohort of acute stroke patients with COVID-19 disease and determine the role of sex on outcome. METHODS: This is a retrospective study of patients with acute stroke and SARS-CoV-2 infection admitted between March 15 to May 15, 2020 to one of the six participating comprehensive stroke centers. Baseline characteristics, stroke subtype, workup, treatment and outcome are presented as total number and percentage or median and interquartile range. Outcome at discharge was determined by the modified Rankin Scale Score (mRS). Variables and outcomes were compared for males and females using univariate and multivariate analysis. RESULTS: The study included 83 patients, 47% of which were Black, 28% Hispanics/Latinos, and 16% whites. Median age was 64 years. Approximately 89% had at least one preexisting vascular risk factor (VRF). The most common complications were respiratory failure (59%) and septic shock (34%). Compared with females, a higher proportion of males experienced severe SARS-CoV-2 symptoms requiring ICU hospitalization (73% vs. 49%; p = 0.04). When divided by stroke subtype, there were 77% ischemic, 19% intracerebral hemorrhage and 3% subarachnoid hemorrhage. The most common ischemic stroke etiologies were cryptogenic (39%) and cardioembolic (27%). Compared with females, males had higher mortality (38% vs. 13%; p = 0.02) and were less likely to be discharged home (12% vs. 33%; p = 0.04). After adjustment for age, race/ethnicity, and number of VRFs, mRS was higher in males than in females (OR = 1.47, 95% CI = 1.03-2.09). CONCLUSION: In this cohort of SARS-CoV-2 stroke patients, most had clinical evidence of coronavirus infection on admission and preexisting VRFs. Severe in-hospital complications and worse outcomes after ischemic strokes were higher in males, than females.


Assuntos
Isquemia Encefálica/epidemiologia , Infecções por Coronavirus/epidemiologia , Disparidades nos Níveis de Saúde , Hemorragias Intracranianas/epidemiologia , Pneumonia Viral/epidemiologia , Acidente Vascular Cerebral/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/terapia , COVID-19 , Chicago/epidemiologia , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/terapia , Feminino , Humanos , Hemorragias Intracranianas/diagnóstico , Hemorragias Intracranianas/terapia , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/diagnóstico , Pneumonia Viral/terapia , Prognóstico , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Fatores Sexuais , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/terapia , Fatores de Tempo
3.
Doc Ophthalmol ; 130(2): 131-9, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25516428

RESUMO

PURPOSE: We investigate how type 2 diabetes (T2DM) and diabetic retinopathy (DR) affect color vision (CV) and mfERG implicit time (IT), whether CV and IT are correlated, and whether CV and IT abnormality classifications agree. METHODS: Adams desaturated D-15 color test, mfERG, and fundus photographs were examined in 37 controls, 22 T2DM patients without DR (NoRet group), and 25 T2DM patients with DR (Ret group). Color confusion score (CCS) was calculated. ITs were averaged within the central 7 hexagons (central IT; ≤4.5°) and outside this area (peripheral IT; ≥4.5°). DR was within (DRIN) or outside (DROUT) of the central 7 hexagons. Group differences, percentages of abnormalities, correlations, and agreement were determined. RESULTS: CCS was greater in the NoRet (P = 0.002) and Ret (P < 0.0001) groups than in control group. CCS was abnormal in 3, 41, and 48 % of eyes in the control, NoRet, and Ret groups, respectively. Ret group CV abnormalities were more frequent in DRIN than in DROUT subgroups (71 vs. 18 %, respectively; P < 0.0001). CCS and IT were correlated only in the Ret group, in both retinal zones (P ≤ 0.028). Only in the Ret group did CCS and peripheral IT abnormality classifications agree (72 %; P < 0.05). CONCLUSION: CV is affected in patients with T2DM, even without DR. Central DR increases the likelihood of a CV deficit compared with non-central DR. mfERG IT averaged across central or peripheral retinal locations is less frequently abnormal than CV in the absence of DR, and these two measures are correlated only when DR is present.


Assuntos
Defeitos da Visão Cromática/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Retinopatia Diabética/fisiopatologia , Adulto , Idoso , Testes de Percepção de Cores , Técnicas de Diagnóstico Oftalmológico , Eletrorretinografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Retina/fisiopatologia
4.
Cell Mol Bioeng ; 11(6): 495-508, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30581495

RESUMO

INTRODUCTION: Ventilator-Induced lung injury (VILI) is a form of acute lung injury that is initiated or exacerbated by mechanical ventilation. The aging lung is also more susceptible to injury. Harmful mechanical stretch of the alveolar epithelium is a recognized mechanism of VILI, yet little is known about how mechanical stretch affects aged epithelial cells. Disruption to Endoplasmic Reticulum (ER) homeostasis results in a condition known as ER stress that leads to disruption of cellular homeostasis, apoptosis, and inflammation. ER stress is increased with aging and other pathological stimuli. We hypothesized that age and mechanical stretch increase alveolar epithelial cells' proinflammatory responses that are mediated by ER stress. Furthermore, we believed that inhibition of this upstream mechanism with 4PBA, an ER stress reducer, alleviates subsequent inflammation and monocyte recruitment. METHODS: Type II alveolar epithelial cells (ATII) were harvested from C57Bl6/J mice 2 months (young) and 20 months (old) of age. The cells were cyclically stretched at 15% change in surface area for up to 24 hours. Prior to stretch, groups were administered 4PBA or vehicle as a control. RESULTS: Mechanical stretch and age upregulated ER stress and proinflammatory MCP-1/CCL2 and MIP-1ß/CCL4 chemokine expression in ATIIs. Age-matched and mismatched monocyte recruitment by ATII conditioned media was also quantified. CONCLUSIONS: Age increases susceptibility to stretch-induced ER stress and downstream inflammatory gene expression in a primary ATII epithelial cell model. Administration of 4PBA attenuated the increased ER stress and proinflammatory responses from stretch and/or age and significantly reduced monocyte migration to ATII conditioned media.

5.
Med Klin Intensivmed Notfmed ; 111(6): 508-13, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26507497

RESUMO

OBJECTIVE: To detect connections between parameters of ventilation and outcomes of cardiac intensive care patients. DESIGN AND SETTING: Noninterventional study. Between 05/11 and 05/12 all patients with acute heart failure and post cardiopulmonary resuscitation were registered. Lung protective ventilation was defined as peak inspiratory pressure (PIP) < 30 mmHg and tidal volume (Vt) < = 6 ml/kg. RESULTS: In total, 129 patients were included in the study, 68.2 % male, age 67.9 ± 13.4 years, weight 71.4 ± 37.2 kg, predictive body weight 66.9 ± 8.8 kg, mortality 47.3 %. Lung protective ventilated patients at day 1: 17.3 % with a significant difference between surviving and nonsurviving patients (24.1 % vs. 9.6 %; p < 0.05). Logistic regression models showed a strong connection between PIP and survival (odds ratio 1.13; p < 0.05). Vt showed no significant influence on survival. CONCLUSION: Our data recommends a strict observance of a low PIP for cardiac intensive care patients, whereas Vt seems to be of secondary importance.


Assuntos
Cuidados Críticos , Respiração Artificial , Síndrome do Desconforto Respiratório , Volume de Ventilação Pulmonar , Idoso , Feminino , Humanos , Pulmão , Masculino , Pessoa de Meia-Idade , Respiração com Pressão Positiva
6.
Clin Infect Dis ; 40(7): e59-62, 2005 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-15824976

RESUMO

Our experience with West Nile virus infection revealed that 54% of 28 patients had a focal neurological deficit at presentation. A meningitis or encephalitis syndrome was absent in 47% of patients with focal deficits. Details of the variety of deficits, the time to development of deficits, and the associated radiological and laboratory findings are also discussed in the present report.


Assuntos
Doenças do Sistema Nervoso/fisiopatologia , Doenças do Sistema Nervoso/virologia , Febre do Nilo Ocidental/complicações , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
7.
Clin Neurophysiol ; 116(10): 2441-53, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16002333

RESUMO

OBJECTIVE: To study the presence of electrophysiological indicators of remaining cortical functions in patients with persistent vegetative state (PVS) and minimally conscious state (MCS). Previous electrophysiological and PET data indicated that some PVS patients have partially intact cortical processing functions. However, it remains unclear whether the reported patients were representative for PVS population or just some exceptional cases. METHODS: Event-related brain responses to stimuli of different complexity levels, recorded in 98 patients with extremely severe diffuse brain injuries, 50 of which in PVS. Four main indicators of cortical functions were: (i) N1-P2 complex as an index of simple, undifferentiated cortical processing; (ii) mismatch negativity as an index of pre-attentive, probably unconscious, cortical orientation; (iii) P3 wave as an index of deep cortical analysis of physical stimuli, and (iv) brain responses to semantic stimuli. RESULTS: Cortical responses were found in all PVS patients with a background EEG activity > 4 Hz. All responses investigated, including those to semantic stimuli that indicated comprehension of meaning, occurred significantly above chance, though less frequently than in patients with severe brain injuries who were conscious. CONCLUSIONS: Cortical responses were lacking in most patients with severe EEG slowing (< 4 Hz). Follow-up data revealed that the presence of a mismatch negativity, a short disease duration, and the traumatic etiology were related to a better outcome. SIGNIFICANCE: The data show that in a subpopulation of PVS patients with preserved thalamocortical feedback connections, remaining cortical information processing is a consistent finding and may even involve semantic levels of processing.


Assuntos
Transtornos da Consciência/fisiopatologia , Processos Mentais/fisiologia , Estado Vegetativo Persistente/fisiopatologia , Córtex Auditivo/fisiologia , Lesões Encefálicas/fisiopatologia , Córtex Cerebral/fisiopatologia , Eletroencefalografia , Eletroculografia , Potenciais Evocados/fisiologia , Fixação Ocular/fisiologia , Seguimentos , Humanos
8.
Invest Ophthalmol Vis Sci ; 38(11): 2278-89, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9344351

RESUMO

PURPOSE: To describe the types of color vision defects present in the acute phase of the disease and 6 months into recovery in the 438 participants of the Optic Neuritis Treatment Trial. METHODS: Patients meeting strict eligibility criteria were seen within 8 days of the onset of symptoms and then at regular follow-up visits. At the first and 6-month visits (and subsequent annual visits), spatial vision (acuity, contrast sensitivity), visual fields, and color vision were measured. Farnsworth-Munsell 100-hue tests were scored by a variant of the method of quadrant analysis described by Smith et al (Am J Ophthalmol. 1985; 100:176-182). RESULTS: Most persons show mixed red-green (RG) and blue-yellow (BY) color defects (one type predominating, accompanied by a lesser defect of the other type). BY defects tend to be slightly more common in the acute phase of the disease, with slightly more RG defects at 6 months. Persons may shift defect type over time. Defect type was not related to any of the spatial vision measures at either test time or to treatment group; however, severity of color defect was related to both spatial vision measures and treatment group. CONCLUSIONS: Contrary to common clinical wisdom, optic neuritis is not characterized by selective RG defects. Color defect type cannot be used for differential diagnosis of optic neuritis.


Assuntos
Defeitos da Visão Cromática/diagnóstico , Neurite Óptica/complicações , Neurite Óptica/terapia , Percepção Espacial , Doença Aguda , Adolescente , Adulto , Percepção de Cores/fisiologia , Testes de Percepção de Cores , Defeitos da Visão Cromática/complicações , Defeitos da Visão Cromática/fisiopatologia , Sensibilidades de Contraste/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neurite Óptica/fisiopatologia , Acuidade Visual/fisiologia , Campos Visuais/fisiologia
9.
Invest Ophthalmol Vis Sci ; 40(11): 2638-51, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10509661

RESUMO

PURPOSE: To identify local retinal abnormalities in diabetic patients with and without retinopathy, by using the multifocal electroretinogram (M-ERG). METHODS: Electroretinograms were recorded at 103 discrete retinal locations in each eye of eight persons with nonproliferative diabetic retinopathy (NPDR) and eight diabetic persons without retinopathy, using VERIS (EDI, San Mateo, CA). The amplitude and implicit time of each local (first-order) retinal response were derived and compared with normal values obtained from 16 age-matched, nondiabetic subjects. Maps of local response amplitude and implicit time were compared with fundus photographs taken at the time of testing. RESULTS: In eyes with NPDR, the implicit times of responses from retinal sites manifesting clinical pathologic fundus lesions (e.g., microaneurysms and focal edema), were markedly delayed (e.g., up to 7 msec from normal). Responses from adjacent retinal sites that were more normal in clinical appearance were also delayed, but to a lesser extent (e.g., 2-5 msec). Smaller, yet significant local response delays were also found in eyes without retinopathy. By contrast, local response amplitudes bore no consistent relationship to fundus abnormalities in eyes with retinopathy, and amplitudes were typically normal in eyes without retinopathy. CONCLUSIONS: The M-ERG reveals local retinal dysfunction in diabetic eyes even before retinopathy. The magnitude of delay of local ERG implicit time reflects the degree of local clinical abnormality in eyes with retinopathy. Local response delays found in some eyes without retinopathy suggest that the M-ERG detects subclinical local retinal dysfunction in diabetes. Analysis of M-ERG implicit time, independent of amplitude, improves the sensitivity of detection of local retinal dysfunction in diabetes.


Assuntos
Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Retinopatia Diabética/diagnóstico , Retina/fisiopatologia , Adulto , Retinopatia Diabética/classificação , Retinopatia Diabética/fisiopatologia , Eletrorretinografia , Feminino , Fundo de Olho , Humanos , Masculino , Pessoa de Meia-Idade , Retina/patologia , Sensibilidade e Especificidade
10.
Invest Ophthalmol Vis Sci ; 38(1): 207-18, 1997 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9008645

RESUMO

PURPOSE: To design and evaluate a new vision test that combines low contrast and reduced illumination to stress the visual system and be sensitive to subtle alterations in function. METHODS: A simple new clinical test, the Smith-Kettlewell Institute Low Luminance (SKILL) Card, is designed to measure spatial vision under conditions of reduced contrast and luminance using normal office lighting. The SKILL Card consists of two near acuity charts mounted back to back. One side has a chart with black letters on a dark gray background designed to simulate reduced contrast and luminance conditions. The other side has a high-contrast, black-on-white letter chart. The SKILL score is the acuity loss (number of letters) between the light and dark sides. RESULTS: Age norms for a large normal population have been established and show that test scores increase with age, particularly after age 50. Repeatability is as good as that of standard Snellen acuity. The SKILL score is affected minimally by blur, but it is affected by large variations in light level. SKILL scores are sensitive to the presence of visual disease such as "recovered" optic neuritis. CONCLUSIONS: The SKILL card allows quick, reliable measurement of the effect of reduced luminance and contrast on acuity SKILL scores are not correlated with other vision measures in patients with optic neuritis, which shows that the SKILL card measures a different dimension of vision function than existing clinical tests.


Assuntos
Sensibilidades de Contraste/fisiologia , Luz , Testes Visuais/instrumentação , Acuidade Visual/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Desenho de Equipamento , Glaucoma/fisiopatologia , Humanos , Pessoa de Meia-Idade , Hipertensão Ocular/fisiopatologia , Neurite Óptica/fisiopatologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
11.
Invest Ophthalmol Vis Sci ; 35(3): 1243-6, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8125735

RESUMO

PURPOSE: To investigate variations in diabetic short-wavelength sensitivity with acute, induced changes in blood glucose level. METHODS: Increment threshold measures were obtained for short-wavelength-sensitive and middle/long-wavelength-sensitive cone pathways after an induced, acute change in blood glucose level in diabetic observers. RESULTS: Diabetic observers showed an increase in short-wavelength sensitivity, but no change in middle/long-wavelength sensitivity, with a rapid drop in blood glucose level. CONCLUSIONS: Experimentally induced changes in diabetic blood glucose levels can directly affect diabetic short-wavelength sensitivity.


Assuntos
Glicemia/metabolismo , Percepção de Cores/fisiologia , Retinopatia Diabética/fisiopatologia , Luz , Limiar Sensorial/fisiologia , Adolescente , Adulto , Idoso , Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Feminino , Humanos , Hiperglicemia/fisiopatologia , Masculino , Pessoa de Meia-Idade
12.
Invest Ophthalmol Vis Sci ; 38(5): 800-10, 1997 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9112974

RESUMO

PURPOSE: To determine whether specific chromatic pathways are selectively affected by short-term variations in blood glucose levels in observers with and without diabetes. METHODS: Ten subjects with diabetes, all with type 1 diabetes and no retinopathy, and eight age-similar normal subjects were tested. Cortical visually evoked potentials (VEPs) in response to stimuli designed to selectively activate the short-wavelength-sensitive (S) or long- and middle-wavelength-sensitive (LM) chromatic (isoluminant) pathways or the achromatic pathway were recorded over a period of several hours. Capillary blood glucose also was measured repeatedly over the same period. The relation between VEP latency and blood glucose was determined. RESULTS: The S-pathway VEP latency was correlated significantly with blood glucose in a slight majority (6/10) of persons with diabetes; S-pathway latency was longer at higher blood glucose levels. This association between S-pathway latency and blood glucose was not dependent on the pattern of blood glucose variation over time (i.e., significant correlations between blood glucose and latency were observed in persons for whom blood glucose increased, decreased, or rose and then fell over time). No dependence on blood glucose was observed for LM- or achromatic-pathway VEP latency in subjects with diabetes. CONCLUSIONS: Acute variations in blood glucose of subjects with diabetes over hours selectively affect the function of the short-wavelength-sensitive chromatic pathway. The findings are discussed within the context of known mechanisms by which elevated glucose affects cellular metabolism with a time course consistent with the transient nature of the effect observed.


Assuntos
Glicemia/fisiologia , Diabetes Mellitus Tipo 1/fisiopatologia , Potenciais Evocados Visuais/fisiologia , Células Fotorreceptoras Retinianas Cones/fisiopatologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Vias Visuais/fisiopatologia
13.
Vision Res ; 24(1): 77-85, 1984.
Artigo em Inglês | MEDLINE | ID: mdl-6695510

RESUMO

Behavioral measures of spatial summation in 4- and 11-week old human infants were obtained using the forced-choice preferential looking technique. Infants exhibit complete spatial summation over large areas (4 weeks: 8.9 degrees; 11 weeks: 5.5 degrees), much larger than those of adults tested in the same apparatus (2.6 degrees). Thus, infants' summation areas are larger than adults' by factors of 12 at 4 weeks and 4 at 11 weeks. It is argued that at most, one-half of this difference between the infant and adult data may be due to optical factors (e.g. defocus and small eye size). The remainder probably reflects differences in the neural organization of the immature and mature visual systems.


Assuntos
Adaptação à Escuridão , Percepção Espacial/fisiologia , Adulto , Humanos , Lactente , Retina/fisiologia , Limiar Sensorial
14.
Vision Res ; 40(24): 3447-53, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11058741

RESUMO

The effect of acute blood glucose elevations on human outer retinal function was examined. Electrooculograms were recorded as the background light cycled on/off with a 2-min period, eliciting rapid changes in the corneo-retinal standing potential known as the fast-oscillation of the electrooculogram. Recordings were made while subjects fasted and after they consumed 100 g of D-glucose. In all subjects, blood glucose levels strongly affected fast oscillation amplitude, which reflects photoreceptor-driven changes in RPE cell chloride concentration. The sensitivity of RPE metabolism to glucose fluctuations may relate to changes in the blood-retinal barrier that are known to occur in diabetes (e.g. macular edema).


Assuntos
Glicemia/metabolismo , Barreira Hematorretiniana/fisiologia , Epitélio Pigmentado Ocular/fisiologia , Retina/fisiologia , Adulto , Eletroculografia/efeitos dos fármacos , Jejum/fisiologia , Glucose/farmacologia , Humanos , Transporte de Íons , Iluminação , Epitélio Pigmentado Ocular/metabolismo
15.
Br J Ophthalmol ; 88(4): 543-50, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15031174

RESUMO

AIMS: To study the effects of two commonly used pre-amplifier filtering bandwidths on normal multifocal electroretinogram (mfERG) responses and their comparative abilities to detect retinal disease. METHODS: 103 standard mfERGs were recorded simultaneously in two channels with different pre-amplifier settings (10-100 Hz and 10-300 Hz) from one eye of each of 20 normal subjects, 17 diabetics with non-proliferative diabetic retinopathy (NPDR), and 12 diabetics without retinopathy. Signal to noise ratios (SNR) of the normal subjects' first order mfERGs were compared between channels. All subjects' amplitudes and implicit times were derived using a "template stretching" method. For comparison, implicit time was also measured using a "template sliding" method. mfERG amplitudes and implicit times were compared between the channels and among subject groups. RESULTS: Normal mean amplitudes and implicit times were similar for the two channels. However, normal 10-100 Hz recordings had significantly higher SNR and lower intersubject variability than 10-300 Hz recordings. In NPDR, the 10-100 Hz channel identified significantly more implicit time and amplitude abnormalities. In the diabetics without retinopathy, 10-100 Hz filtering identified significantly more implicit time abnormalities than 10-300 Hz filtering. For both filter settings, diabetic implicit times were more often abnormal than amplitudes. The 10-100 Hz channel was superior for both implicit time measurements. CONCLUSION: Standard mfERGs recorded from normal eyes and filtered 10-100 Hz contain less noise, higher SNR, and less intersubject variability than those filtered at 10-300 Hz. This underlies the finding that the 10-100 Hz filter setting identifies more retinal dysfunction than the 10-300 Hz setting.


Assuntos
Retinopatia Diabética/diagnóstico , Eletrorretinografia/métodos , Adulto , Idoso , Estudos de Casos e Controles , Diabetes Mellitus/fisiopatologia , Eletrônica Médica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade
16.
Vision Res ; 30(7): 973-83, 1990.
Artigo em Inglês | MEDLINE | ID: mdl-2392841

RESUMO

Rod saturation on flashed and steady red backgrounds was investigated in normals and three achromats, two of whom were found to have some residual cone function. LWS cones selectively reduce the background level at which rod saturation occurs and elevate rod thresholds at flashed background levels well below saturation. Both of these LWS cone actions are also present in eyes with greatly reduced LWS cone function. In normal eyes LWS cones also elevate rod thresholds on steady backgrounds. We thus conclude that LWS cones influence rods through different mechanisms under transient (flashed) and steady-state background stimulation and that the increase in rod visual sensitivity observed during prolonged presentation of a background is due to a time-dependent reduction of LWS cone influence on rods. Finally, the finding that rod-cone interactions of the same magnitude found in normals can be seen in individuals where the cones' ability to mediate vision is severely reduced suggests the rod saturation paradigm as a sensitive technique for revealing residual LWS cone function.


Assuntos
Defeitos da Visão Cromática/fisiopatologia , Células Fotorreceptoras/fisiopatologia , Adaptação Ocular/fisiologia , Feminino , Humanos , Luz , Masculino , Limiar Sensorial/fisiologia , Espectrofotometria
17.
Vision Res ; 34(20): 2657-71, 1994 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-7975303

RESUMO

Visual evoked potentials (VEPs) were measured for sinusoidal gratings with spatio-chromatic modulation defined in a three-dimensional color space. The spatio-chromatic modulation of the gratings can be decomposed into contributions from an achromatic luminance varying component, an isoluminant component which modulates only the activities of L cones and M cones, and an isoluminant component corresponding to modulation of only S-cone activity. The emphasis of this report is the nature of VEPs resulting from isoluminant spatio-chromatic modulation. The VEP response was characterized along a number of spatial, temporal, and chromatic stimulus dimensions: contrast, spatial frequency, chromaticity in the isoluminant plane, chrominance/luminance ratio, orientation, and temporal frequency. Isoluminant VEPs resulting from stimuli modulating L and M cones are compared with those from S-cone modulation. When appropriate spatiotemporal conditions are employed, both types produce robust VEPs; however, the S-pathway VEPs show considerably longer latencies than do those from LM-pathway activation. The VEP results are compared to psychophysical and single unit electrophysiological observations. VEP latencies exhibit the lowpass character of psychophysical chromatic contrast sensitivity functions but VEP amplitudes show bandpass tuning along both the S and LM axes. An oblique effect, i.e. shorter latencies for horizontal and vertical gratings than for diagonal, is observed in the isoluminant VEP. S-pathway VEPs are used to demonstrate an electophysiological correlate of transient tritanopia. Normative amplitude and latency data for VEPs from selectivity stimulated chromatic mechanisms provide a baseline for clinical electrodiagnostic applications.


Assuntos
Percepção de Cores/fisiologia , Potenciais Evocados Visuais , Reconhecimento Visual de Modelos/fisiologia , Adaptação Ocular , Sensibilidades de Contraste/fisiologia , Humanos , Psicofísica , Células Fotorreceptoras Retinianas Cones/fisiologia , Rotação , Fatores de Tempo
18.
Vision Res ; 24(12): 1753-63, 1984.
Artigo em Inglês | MEDLINE | ID: mdl-6533998

RESUMO

A fixation-and-flash technique has been developed to provide control over the retinal eccentricities of stimuli presented to infant subjects, to within a few degrees of visual angle. The technique is a variant of forced-choice preferential looking (FPL). An adult observer triggers presentation of the test stimulus when she judges that the infant is fixating a centrally located fixation target. The stimuli are short in relation to the infant's refixation latency. Auxiliary experiments confirmed that on most trials the stimuli fell within +/- 4 degrees of the designated eccentricity. Test fields of two sizes, 3.1 and 17 degrees, were presented to 1-month-old infants at one of four retinal locations, 9, 18, 27 and 36 degrees eccentric. The infants' data show a perfect area-intensity tradeoff at all four locations. Adult control subjects showed summation over areas of only 1-2 degrees. The results are discussed in relation to other evidence of coarse spatial processing in human infants and other immature mammalian systems.


Assuntos
Limiar Sensorial/fisiologia , Percepção Visual/fisiologia , Adulto , Adaptação à Escuridão , Feminino , Fixação Ocular , Humanos , Lactente , Masculino , Estimulação Luminosa , Retina/fisiologia
19.
Vision Res ; 25(6): 821-31, 1985.
Artigo em Inglês | MEDLINE | ID: mdl-4024480

RESUMO

The capacity of 1- and 2-month-old infants to make a tritan discrimination between a 4 degree, 416 nm test field and a 547 nm surround was tested by means of the forced-choice preferential looking technique. Most of the 2-month-olds and the other 1-month-olds made the tritan discrimination and must therefore have functional SWS cones. Most of the youngest 1-month-olds failed to make the tritan discrimination and therefore either do not encode or do not preserve the information ordinarily encoded by SWS cones. The implications of these data and the prior data of Hamer et al. [Vision Res. 22, 575-587 (1982)] are discussed in relation to color theory.


Assuntos
Percepção de Cores/fisiologia , Adulto , Fatores Etários , Desenvolvimento Infantil , Discriminação Psicológica , Humanos , Lactente , Recém-Nascido , Limiar Sensorial , Espectrofotometria
20.
J Cataract Refract Surg ; 20(4): 455-8, 1994 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7932138

RESUMO

Intraocular pressure (IOP) increase soon after neodymium:YAG (Nd:YAG) treatments in the anterior segment has been reported. To evaluate this complication in a large sample of patients, we conducted a retrospective study of all Nd:YAG treatments during three years. Three hundred forty capsulotomies and 212 iridotomies were performed with the Q-switched Nd:YAG laser. An IOP elevation of 10 mm Hg or more within two hours of laser surgery was seen in 15 eyes (4.4%) that had a capsulotomy but in 45 eyes (21.2%) that had an iridotomy. In 13 of the 15 eyes in which the IOP increased after capsulotomy, additional risk factors (glaucoma, high myopia, aphakia) were found. Our results indicate that posterior capsulotomy with the Nd:YAG laser in otherwise healthy, pseudophakic eyes is usually not accompanied by immediate IOP elevation. Elevation can be predicted by risk factors and therefore anticipated in a small group of vulnerable patients.


Assuntos
Câmara Anterior/fisiologia , Pressão Intraocular , Iris/cirurgia , Terapia a Laser , Cápsula do Cristalino/cirurgia , Idoso , Catarata/etiologia , Extração de Catarata/efeitos adversos , Feminino , Humanos , Terapia a Laser/efeitos adversos , Lentes Intraoculares , Masculino , Hipertensão Ocular/etiologia , Estudos Retrospectivos , Fatores de Risco
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