RESUMO
BACKGROUND: Depressed fractures of the base of the middle phalanges are problematic because of frequent subluxations and centrally depressed fragments. There are two minimally invasive procedures available: 1) the less known intramedullary padding technique according to Hintringer and 2) the widely used distraction fixator of Suzuki. This article describes the technique and outcome of these two procedures. METHODOLOGY: The follow-up collective included 42 patients after treatment of a depressed fracture of the base of the middle phalanx. An intramedullary padding with percutaneous Kirschner wire retention was performed 28 times (group A) and treatment with a Suzuki fixator 14 times (group B). The study examined the hand function, the radiological results and the subjective pain level. RESULTS: According to the American Society for Surgery of the Hand (ASSH) classification 81% of the patients in group A achieved a good result but in group B the same result was achieved by only 50% of the patients. The median range of movement in the proximal interphalangeal joint was 82.5° after intramedullary padding and 47.5° after Suzuki fixator. In median, the impression was reduced from 2.35â¯mm to 0.5â¯mm in group A, but only from 1.6â¯mm to 1.15â¯mm in group B. Pain was a limiting factor in 2 out of 28 patients in group A and 1 out of 14 patients in group B. CONCLUSION: The intramedullary padding technique according to Hintringer enables good treatment of depressed fractures of the base of the middle phalanx of the finger. Repositioning of dorsal subluxations can be performed and centrally impressed fragments can be reduced better than by using the Suzuki dynamic fixator. In addition, the radiological course assessments can be assessed better than with the distraction fixator.
Assuntos
Traumatismos dos Dedos , Falanges dos Dedos da Mão , Fraturas Ósseas , Luxações Articulares , Fios Ortopédicos , Fixadores Externos , Traumatismos dos Dedos/cirurgia , Falanges dos Dedos da Mão/lesões , Dedos , Fraturas Ósseas/cirurgia , Humanos , Radiografia , Amplitude de Movimento Articular , Resultado do TratamentoRESUMO
PURPOSE: Automated spectral domain optical coherence tomography (SD-OCT) segmentation algorithms currently do not perform well in segmenting individual intraretinal layers in eyes with Stargardt disease (STGD). We compared selective B-scan segmentation strategies for generating mean retinal layer thickness and preserved area data from SD-OCT scans in patients with STGD1. METHODS: Forty-five eyes from 40 Stargardt patients were randomly selected from the ongoing Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) study. All eyes underwent SD-OCT using a standard macular volume consisting of 1024 × 49 equally spaced B-scans within a 20 × 20 degree field centered on the fovea. All 49 B-scans were segmented manually to quantify total retina, outer nuclear layer (ONL), photoreceptor inner segments, photoreceptor outer segments (OS), and retinal pigment epithelial layer (RPE). Mean thickness and total area were generated using all 49 B-scans (spaced 122 µm apart), 25 B-scans (every other B-scan, spaced 240 µm apart), 17 B-scans (every third scan, 353 µm apart), and 13 B-scans (every fourth scan, 462 µm apart), as well as by using an "adaptive" method where a subset (minimum 25 B-scans) of B-scans that the grader deemed as significantly different from adjacent B-scans were utilized. Mean absolute and percentage errors were calculated for macular thickness and area of different retinal layers for the different B-scan subset selection strategies relative to using all 49 B-scans, which was considered the reference or ground truth. RESULTS: Mean thickness and area measurements were significantly different for any regularly spaced reduction in B-scan density relative to the ground truth. When an adaptive approach was applied using a minimum of half the scans, the differences relative to ground truth were no longer significantly different. The mean percent differences for the area and thicknesses of the various layers ranged from 0.02 to 33.66 (p < 0.05 for all comparisons) and 0.44 to 7.24 (p > 0.05) respectively. CONCLUSION: Manual segmentation of a subset of B-scans using an adaptive strategy can yield thickness and area measurements of retinal sublayers comparable to the reference ground truth derived from using all B-scans in the volume. These results may have implications for increasing the efficiency of SD-OCT grading strategies in clinical trials for STGD and other related macular degenerative disorders.
Assuntos
Algoritmos , Macula Lutea/patologia , Degeneração Macular/congênito , Epitélio Pigmentado da Retina/patologia , Tomografia de Coerência Óptica/métodos , Seguimentos , Humanos , Degeneração Macular/diagnóstico , Estudos Prospectivos , Reprodutibilidade dos Testes , Índice de Gravidade de Doença , Doença de StargardtRESUMO
BACKGROUND: Complications related to arthrodesis of the ankle or total ankle replacement require a critical assessment of the indication. Using denervation of the ankle, we have the possibility to delay the above-named surgical treatment for a number of years. The aim of this follow-up study was to review the results of ankle denervation after several years. METHODS: Within a follow-up examination, we were able to evaluate the results of 45 patients an average of 102 months following ankle denervation. RESULTS: A total of 82.2% of patients indicated an improvement of pain for an average of 60.9 months; 71.1% of patients reported that the operation was worthwhile. The AOFAS score improved from an average 37.9 (range 26-68) preoperatively to 55.6 (range 24-84) at follow-up. CONCLUSIONS: Ankle denervation can achieve good ankle pain reduction in the treatment of ankle arthrosis. Denervation should be considered a long-term treatment concept.
Assuntos
Articulação do Tornozelo/inervação , Artralgia/etiologia , Artralgia/prevenção & controle , Denervação/métodos , Osteoartrite/complicações , Osteoartrite/cirurgia , Adulto , Idoso , Articulação do Tornozelo/cirurgia , Artralgia/diagnóstico , Feminino , Seguimentos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Osteoartrite/diagnóstico , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: In this study 56 dorsal phalangeal fractures of the distal segment were classified regarding morphological criteria. MATERIAL AND METHODS: Clinical and radiological results after 4 months were analyzed. Fractures including subluxation of the distal interphalangeal joint occurred rarely (n=3) and were treated by surgery. Fractures without subluxation had either a triangle-shaped fragment (n=40) or a fragment similar to a hunter's hat (n=9). Furthermore, there were two fractures with a tiny bony avulsion and two fractures with more radial or ulnar-oriented fragments. The triangle and hunter's hat type fractures were treated either by splinting (n=20) or by open reduction and stabilization with screws and wires (n=29). RESULTS: Clinical outcome was similar in both groups. In 12 out of the 20 fractures treated by splinting a stepping of the joint surface had to be tolerated. Initially only 8 out of 20 fractures showed a stepping of the joint surface. The fractures treated by surgery showed a better radiological outcome. CONCLUSIONS: Initially 27 fractures showed a stepping in the joint line but after surgical treatment only 9 fractures still presented a stepping. The remaining four fractures were successfully treated by splinting.
Assuntos
Traumatismos dos Dedos/terapia , Falanges dos Dedos da Mão/lesões , Falanges dos Dedos da Mão/cirurgia , Fixação Interna de Fraturas/instrumentação , Fraturas Ósseas/terapia , Imobilização/instrumentação , Contenções , Adolescente , Adulto , Feminino , Traumatismos dos Dedos/diagnóstico por imagem , Falanges dos Dedos da Mão/diagnóstico por imagem , Fixação Interna de Fraturas/métodos , Consolidação da Fratura , Fraturas Ósseas/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia , Resultado do Tratamento , Adulto JovemRESUMO
Computer-assisted systems are used frequently in pelvis and spine surgery but are still rare in general trauma and hardly ever used in shoulder surgery. The major limitation is the use of rigid markers and the problem of obtaining navigable images in the complex shoulder region. The aim of this study was to evaluate the use of a new image-based guidance system in shoulder traumatology. The system was used to implant a tightrope system in Tossy III lesions of the AC joint (n=7) and compared to the conventional method (n=8). Outcome parameters were duration of surgery, number of trials for perfect positioning of the guide wire, C-arm shots used till K-wire position is accepted, duration of radiation and surgeon's comment on usability and benefit. The new system did not shorten the surgical procedure significantly (45 vs 49 min, p=0.6) but reduced the average overall radiation time from 152 to 90 s (p=0.3). The number of shots to implant the guide-wire could be reduced significantly from 8 to 5 (p=0.01). The number of trials to implant the guide wire was less in the image-guided group compared to the conventional group (1 vs 2, p=0.02). For the first time image-based guidance was used in shoulder traumatology. The system holds high potential to assist surgeons without disturbing the workflow in assuring guide wire positioning, reduce the number of dangerous mistrials and reduce the emission of radiation.
Assuntos
Endoscopia/instrumentação , Procedimentos de Cirurgia Plástica/instrumentação , Lesões do Ombro , Articulação do Ombro/cirurgia , Cirurgia Assistida por Computador/instrumentação , Adulto , Idoso , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Articulação do Ombro/patologia , Resultado do TratamentoRESUMO
PURPOSE: To define unmet needs in ophthalmology which can realistically be addressed in the next years (2019-2025) and to describe potential avenues for research to address these challenges. METHODS: Outcomes of a consensus process within the European Vision Institute (EVI, Brussels) are outlined. Disease areas which are discussed comprise glaucoma, retinal dystrophies, diabetic retinopathy, dry eye disease, corneal diseases, cataract and refractive surgery. RESULTS: Unmet needs in the mentioned disease areas are discussed and realistically achievable research projects outlined. CONCLUSION: Considerable progress can be made in the field of ophthalmology and patient-relevant outcomes in the near future.
Assuntos
Catarata , Glaucoma , Oftalmologia , Consenso , Humanos , Visão OcularRESUMO
The use of patient-reported outcomes (PROs) - standardized assessments by the patient of the impact of illness or therapy - has been met with increasing interest over the last years. Evidence generated from PROs is used not only to support claims in the drug regulatory process but is also used in political decision making and activities by the pharmaceutical industry. PROs can reflect the benefits of a treatment very well because the patient's quality of life is a central variable, and its preservation or improvement is certainly the main objective of any therapeutic intervention. The routine use of PROs is still hampered by several methodological problems. However, there are a number of advantages, such as improved interaction between physicians and patients and shared decision making, that may result in increased compliance.
Assuntos
Oftalmopatias/psicologia , Oftalmopatias/terapia , Avaliação de Resultados em Cuidados de Saúde , Satisfação do Paciente , Qualidade de Vida/psicologia , Transtornos da Visão/psicologia , Transtornos da Visão/terapia , Atividades Cotidianas/psicologia , Medicina Baseada em Evidências , Alemanha , HumanosRESUMO
The framework programmes (FP) of the European Commission have substantially contributed to the funding of research within the European countries. The contribution of the funding provided by the EU relative to the funding available on the national level has steadily increased. European ophthalmology and vision research has benefited from this support provided by the EU. This review introduces the European funding policies and the European Research Area (ERA) and provides a list of all projects in ophthalmology and vision research that have been funded within FP1 to FP6. As an example for new instruments within FP6, Integrated Projects, the EVI-GENORET project is introduced. Finally an outlook for FP7 is provided.
Assuntos
Pesquisa Biomédica/economia , Ensaios Clínicos como Assunto/economia , União Europeia/economia , Financiamento Governamental/economia , Programas Governamentais/economia , Oftalmologia/economia , Europa (Continente)RESUMO
The European Vision Institute EEIG (EVI) creates a new legal entity based on Community law to facilitate and encourage cross-border co-operation in vision research. Its major objectives are to conduct and support research, training, health information dissemination and other programmes with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight and the special health problems and requirements of the blind and visually disabled. EVI aims to foster centres in the EU in capacity building for innovative projects, to increase the flexibility, attractiveness and competitiveness of research careers, especially for young researchers. In addition, EVI will serve to co-ordinate activities with patient organisations and to build a pan-European platform for clinical trials.
Assuntos
Academias e Institutos/organização & administração , Pesquisa Biomédica/organização & administração , União Europeia/economia , Financiamento Governamental/organização & administração , Programas Governamentais/organização & administração , Oftalmologia/organização & administração , Ensaios Clínicos como Assunto/tendências , Europa (Continente)RESUMO
The efficacy and safety of the therapeutic anti-VEGF concept has already been demonstrated for pegaptanib and ranibizumab. Bevacizumab acts as an antibody against all VEGF-A isoforms and has been developed for oncological indications with intravenous application. Initial reports on intravitreal administration in patients with neovascular age-related macular disease (AMD) have shown beneficial morphological and functional effects. In the meantime, bevacizumab has been used off-label in thousands of patients with AMD. However, data from prospective, controlled, randomized trials on both safety and efficacy are lacking. Herein recent experiences with bevacizumab are summarized and discussed. Furthermore, a web-based platform for online data registration and pooled analyses is presented.
Assuntos
Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/efeitos adversos , Neovascularização de Coroide/tratamento farmacológico , Degeneração Macular/tratamento farmacológico , Inibidores da Angiogênese/administração & dosagem , Inibidores da Angiogênese/efeitos adversos , Anticorpos Monoclonais Humanizados , Bevacizumab , Neovascularização de Coroide/etiologia , Ensaios Clínicos como Assunto , Aprovação de Drogas , Rotulagem de Medicamentos , Medicina Baseada em Evidências , Humanos , Injeções Intralesionais , Degeneração Macular/complicações , Padrões de Prática Médica , Resultado do Tratamento , Corpo VítreoRESUMO
Pseudoxanthoma elasticum (PXE) is an inherited disorder that is associated with accumulation of mineralized and fragmented elastic fibers in the skin, vessel walls, and Bruch's membrane. Clinically, patients exhibit characteristic lesions of the skin (soft, ivory-colored papules in a reticular pattern that predominantly affect the neck), the posterior segment of the eye (peau d'orange, angioid streaks, choroidal neovascularizations), and the cardiovascular system (peripheral arterial occlusive disease, coronary occlusion, gastrointestinal bleeding). There is no causal therapy. Recent studies suggest that PXE is inherited almost exclusively as an autosomal recessive trait. Its prevalence has been estimated to be 1:25,000-100,000. The ABCC6 gene on chromosome 16p13.1 is associated with the disease. Mutations within the ABCC6 gene cause reduced or absent transmembraneous transport that leads to accumulation of substrate and calcification of elastic fibers. Although based on clinical features the diagnosis appears readily possible, variability in phenotypic expressions and the low prevalence may be responsible that the disease is underdiagnosed. This review covers current knowledge of PXE and presents therapeutic approaches.
Assuntos
Neovascularização de Coroide/diagnóstico , Neovascularização de Coroide/terapia , Pseudoxantoma Elástico/diagnóstico , Pseudoxantoma Elástico/terapia , Neovascularização de Coroide/epidemiologia , Neovascularização de Coroide/etiologia , Humanos , Guias de Prática Clínica como Assunto , Padrões de Prática Médica , Pseudoxantoma Elástico/complicações , Pseudoxantoma Elástico/epidemiologiaAssuntos
Arteriopatias Oclusivas/diagnóstico , Hipertensão/diagnóstico , Pescoço , Pseudoxantoma Elástico/diagnóstico , Encaminhamento e Consulta , Envelhecimento da Pele , Estrias Angioides/diagnóstico , Estrias Angioides/genética , Arteriopatias Oclusivas/genética , Comportamento Cooperativo , Distrofias Hereditárias da Córnea/diagnóstico , Distrofias Hereditárias da Córnea/genética , Humanos , Hipertensão/genética , Comunicação Interdisciplinar , Masculino , Pessoa de Meia-Idade , Pseudoxantoma Elástico/genética , Envelhecimento da Pele/genéticaRESUMO
BACKGROUND: Wrist fusion is still a common treatment for patients with advanced stage arthritis. Since patients are often intimidated by the functional limitations, we intended to evaluate the influence of the lack of wrist motion in different positions on the dynamic grip function and the grip strength of the hand. METHODS: We simulated wrist fusion in 20° extension and 20° flexion and evaluated the following grip types: fist closure, 2 different power grips, pinch grip and precision grip. A TUB sensor glove was used, which allowed us to dynamically record the range of motion (ROM) of the finger joints as well as grip strength. Nineteen healthy subjects participated and all types of grips were performed using a standardised protocol with and without simulated wrist fusion. RESULTS: Lack of wrist motion in 20° extension had no relevant effect on the fingers' ROM, grip speed or strength. Simulated fusion in 20° flexion also had no influence on ROM or grip speed, rejecting our hypothesis that a tenodesis effect of the extensors in flexion would decrease ROM in the finger joints and grip speed. However, we were able to show a significant decrease of grip strength in flexion compared with extension or healthy wrists. The decrease averaged between 23 and 42% of healthy values, depending on the grip type. There was no change in strength distribution among the fingers. CONCLUSION: We didn't find any impact of lack of wrist motion on finger movement during forceful hand grip at normal speed. However, a significant loss of grip strength in flexed position of the wrist joint should be considered in patients with an indication for bilateral wrist fusion.
Assuntos
Força da Mão , Procedimentos Ortopédicos , Articulação do Punho/cirurgia , Articulações dos Dedos , Humanos , Amplitude de Movimento Articular , PunhoRESUMO
BACKGROUND AND PURPOSE: Mild traumatic brain injury results in a heterogeneous constellation of deficits and symptoms that persist in a subset of patients. This prospective longitudinal study identifies early diffusion tensor imaging biomarkers of mild traumatic brain injury that significantly relate to outcomes at 1 year following injury. MATERIALS AND METHODS: DTI was performed on 39 subjects with mild traumatic brain injury within 16 days of injury and 40 controls; 26 subjects with mild traumatic brain injury returned for follow-up at 1 year. We identified subject-specific regions of abnormally high and low fractional anisotropy and calculated mean fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity across all white matter voxels brain-wide and each of several white matter regions. Assessment of cognitive performance and symptom burden was performed at 1 year. RESULTS: Significant associations of brain-wide DTI measures and outcomes included the following: mean radial diffusivity and mean diffusivity with memory; and mean fractional anisotropy, radial diffusivity, and mean diffusivity with health-related quality of life. Significant differences in outcomes were found between subjects with and without abnormally high fractional anisotropy for the following white matter regions and outcome measures: left frontal lobe and left temporal lobe with attention at 1 year, left and right cerebelli with somatic postconcussion symptoms at 1 year, and right thalamus with emotional postconcussion symptoms at 1 year. CONCLUSIONS: Individualized assessment of DTI abnormalities significantly relates to long-term outcomes in mild traumatic brain injury. Abnormally high fractional anisotropy is significantly associated with better outcomes and might represent an imaging correlate of postinjury compensatory processes.
RESUMO
BACKGROUND: Evidence-based medicine requires careful appraisal of published data derived from experimental and clinical studies. Based on classification of biomedical research reports, evidence levels can be determined and recommendations for therapeutic decisions can be made. METHODS: A classification system for clinical studies was developed. It was evaluated in classifying the reports published in Der Ophthalmologe during 2003-2004 (study design: descriptive cross-sectional study, case series). RESULTS: In the 2-year interval, 70 longitudinal and 95 cross-sectional studies were published. The vast majority of the longitudinal studies were interventional cohort studies. Not considering case reports, 73% of the original articles were longitudinal prospective studies, 1% were retrospective (case-control) studies, and 26% were cross-sectional studies. CONCLUSIONS: The study design of all published articles could be classified using the classification system. This classification system proves to be applicable in the context of clinical studies in ophthalmology and may be helpful in the process of critical appraisal of the literature and synthesis of clinical evidence and an evidence-based recommendation.
Assuntos
Pesquisa Biomédica/classificação , Pesquisa Biomédica/estatística & dados numéricos , Ensaios Clínicos como Assunto/normas , Medicina Baseada em Evidências/normas , Oftalmologia/normas , Publicações Periódicas como Assunto/classificação , Publicações Periódicas como Assunto/estatística & dados numéricos , Bibliometria , Ensaios Clínicos como Assunto/estatística & dados numéricos , Medicina Baseada em Evidências/estatística & dados numéricos , Alemanha , Oftalmologia/estatística & dados numéricos , Publicações Periódicas como Assunto/normas , Padrões de ReferênciaRESUMO
The discovery of the complement factor H (CFH) polymorphism in age-related macular degeneration (AMD) strongly suggests a causative role of the complement system in the pathogenesis of this disease. The complement system is part of the innate immune system and is closely associated with the cellular response and the adaptive immune system. This article provides an overview of the complement system and, taking the new data into account, of possible immunopathogenetic processes in AMD.
Assuntos
Lâmina Basilar da Corioide/imunologia , Degeneração Macular/imunologia , Modelos Imunológicos , Epitélio Pigmentado Ocular/imunologia , Fator H do Complemento/imunologia , HumanosRESUMO
Age-related macular degeneration is a complex genetic disorder. Recent data suggest that the additive genetic risk for late-stage disease is more than two-thirds. Comprehensive genetic studies (candidate gene approaches, linkage and association studies) have been performed in recent years to identity the genetic risk factors at the molecular lavel. Very recently, a significant risk allele, Y402H, has been discovered in the complement factor H (CFH) gene. The relative risk of developing AMD has been estimated between 2.4-4.6 for heterozygotes and 3.3-7.4 for homozygotes. This polymorphism accounts for approximately 20-50% of the overall risk of developing AMD. In this review the results from molecular genetic studies in AMD are summarized, with a special emphasis on the recent data obtained for the CFH gene.
Assuntos
Hidrocarboneto de Aril Hidroxilases/genética , Degeneração Macular/sangue , Degeneração Macular/epidemiologia , Medição de Risco/métodos , Fator H do Complemento/genética , Análise Mutacional de DNA/métodos , França/epidemiologia , Predisposição Genética para Doença/epidemiologia , Testes Genéticos/métodos , Humanos , Incidência , Degeneração Macular/genética , Polimorfismo Genético , Fatores de RiscoRESUMO
In an open prospective study, 54 patients in an interdisciplinary, operative, anesthesiologic intensive care unit were treated with intravenous ciprofloxacin for life-threatening infections. Secondary nosocomial pneumonias were the predominant infection in most patients. A total of 88 causative pathogens were isolated from 50 patients. The most commonly isolated organism was Pseudomonas aeruginosa; Serratia marcescens, Staphylococcus aureus, and Enterobacter sp. were also isolated. Pathogens could not be detected in four patients (three patients with pneumonia, one patient with urinary tract infection). Ciprofloxacin was administered intravenously, either 400 mg every 12 hours or, after a loading dose of 600 mg every 12 hours on Day 1, 400 mg every 12 hours on successive treatment days. A total of 44 patients were treated parenterally, four orally. An additional six patients received ciprofloxacin in both dosage forms as sequential therapy. Serum ciprofloxacin levels were determined by high-performance liquid chromatography in 17 patients. The serum concentrations and the elimination half-life were in accordance with values already published for parenteral doses of 200 and 500 mg ciprofloxacin. Ciprofloxacin clearance was linear even at the high dose (600 mg every 12 hours loading dose) and no cumulative effect was observed. Clinical outcome was very good. Cure was achieved in 21 patients, and clinical improvement occurred in 23 (favorable clinical response rate, 82 percent). Two patients did not respond to therapy, and eight patients were not evaluable. Adverse effects occurred in 12 patients: transient elevation of liver enzymes (seven patients), temporary increase in serum creatinine levels (two), convulsions (two), and exanthem (one). The treatment of severe infections in intensive care patients with higher doses of parenteral ciprofloxacin appears to be considerably more effective than therapy with the doses of intravenous ciprofloxacin recommended to date. Therefore, these preliminary results are the subject of an ongoing double-blind study.
Assuntos
Ciprofloxacina/administração & dosagem , Infecção Hospitalar/tratamento farmacológico , Bactérias/isolamento & purificação , Ciprofloxacina/efeitos adversos , Ciprofloxacina/farmacocinética , Avaliação de Medicamentos , Tolerância a Medicamentos , Humanos , Infusões IntravenosasRESUMO
We have prepared four different 1,4-benzodiazepines, labeled at C-7 with the 1.6-hr positron emitter Br-75 or the 57-hr gamma emitter Br-77, as potential radio-pharmaceuticals for the mapping of cerebral benzodiazepine receptor areas. The triazene method was used and optimized. Yields at the no-carrier-added level were 20%. 7-[75Br]-5-(2-fluorophenyl)-1-methyl-1,3-dihydro-2H-1,4-benzodiazepine-2-one (Br-75 BFB) was isolated with a minimum specific activity of 20,000 Ci/mmole. Biodistribution in mice shows that BFB is taken up rapidly by the brain and is retained there at useful concentrations for significant periods of time. The maximum uptake is observed at 0.25 min. Brain-to-blood concentration ratios are larger than 2 during the interval (0.25 to 10 min) investigated.
Assuntos
Benzodiazepinas , Encéfalo/diagnóstico por imagem , Bromo , Radioisótopos , Tomografia Computadorizada de Emissão/métodos , Animais , Benzodiazepinas/biossíntese , Benzodiazepinas/metabolismo , Encéfalo/metabolismo , Fenômenos Químicos , Química , Marcação por Isótopo , Camundongos , Receptores de Droga/metabolismo , Relação Estrutura-Atividade , Distribuição Tecidual , TriazenosRESUMO
PURPOSE: To study the dynamics and interactions of the signals originating in the long- (L-) and middle (M)-wavelength-sensitive cone pathways in patients with retinitis pigmentosa (RP). METHODS: Twenty-six patients with RP and 29 normal subjects participated in the study. Electroretinographic (ERG) responses were measured to stimuli that modulated exclusively the L- or the M-cones or the two simultaneously (both in-phase and in counter-phase) with varying ratios of L- to M-cone contrasts. S-cones were not modulated. RESULTS: The data of the normal subjects and of the patients can be described by a model in which the amplitudes and the phases of the signals originating in the L- and M-cones are vector summed. In the RP patients, there was a general reduction in ERG sensitivity. The L-cone-driven ERG response was significantly delayed, whereas the M-cone-driven ERG response was phase advanced. CONCLUSIONS: Large dynamic differences between L- and M-cone-driven ERGs can be detected in RP. As a result, the interaction between the L- and M-cone systems, when modulated simultaneously at 30 Hz, is subtractive in RP patients and additive in normal subjects. Our data show that the use of only a standard white flicker ERG might lead to a misinterpretation of the mechanisms involved in retinal disorders, because the phases of different cone-driven responses are not considered.