Estudio de la frecuencia de parpadeo y evaluación de la película lagrimal en superficie ocular de cobayos / Eye blinking frequency studies and tear film evaluation in guinea pig's ocular surface

OBJETVOS: La Queratopatía Climática Esferoidea (QCE) es una enfermedad degenerativa de la córnea humana caracterizada por la agregación de proteínas bajo el epitelio y una progresiva opacidad corneal, causada por condiciones ambientales desfavorables. Si bien esta patología fue descripta por primera vez hace más de cien años, en la actualidad no existe un modelo experimental de QCE que permita avanzar en el conocimiento de la etiopatogenia de la misma para plantear posibles tratamientos. En el intento por desarrollar este modelo en cobayos y debido a la escasa bibliografía disponible que describa la anatomía, fisiología y superficie ocular de estos animales, realizamos diferentes tests fisiológicos de superficie ocular en cobayos y lo compararemos con el humano. MÉTODOS: Para estos estudios se utilizaron 15 cobayos. Se realizaron videograbaciones de los mismos en un ambiente de tranquilidad y bajo ciertos estímulos para estudiar la dinámica de parpadeo y sueño. Con el fin de analizar la producción y la estabilidad del film lagrimal, se realizaron test de Schirmer, medición de la altura del menisco lagrimal inferior por OCT visante y tiempo de ruptura precorneal (TRP) respectivamente. RESULTADOS: El cobayo parpadea de forma completa y parcial, siendo más frecuente ésta última modalidad. La frecuencia y tipo de parpadeos/ minuto fue: Total= 2.35± 0.87; completos= 0.68±0.43; parciales=1.49±0.75. Su frecuencia de parpadeo es 5 veces menor que en humanos. La respuesta palpebral frente a diferentes estímulos externos fue escasa. Los cobayos no poseen hábitos nocturnos como muchos roedores y duermen por cortos períodos. A menudo no cierran completamente los ojos. Test de Schirmer cobayos: 8.14±1.86 mm/5 min (Humanos: 11.9 ± 6.79 mm/5 min). Altura menisco inferior cobayos: 0,206 ± 0,059 mm (Humanos: 0,277 ± 0,033 mm). TRP cobayos: 2-3 min. (Humanos: 10-15 seg). CONCLUSIONES: Los resultados obtenidos muestran que el cobayo, a diferencia de humanos, tiene una frecuencia de parpadeo menor. A su vez, esto se puede correlacionar con una producción de lágrima disminuida (objetivada con Test de Schirmer) y una mayor estabilidad de la película lagrimal, como lo evidencia el prolongado TRP. (AU)

PURPOSE: Climatic spheroidal keratophaty (CSK), also known as climatic droplet keratopathy (CDK), is a degenerative human corneal disease characterized by protein aggregation under the corneal epithelium that leads to a progressive corneal opacity. Of unknown etiology, it is related to harsh environmental conditions. Although CSK was described many years ago and no experimental model of the disease is still available, we perform different physiological test on the guinea pig´s ocular surface and compare the results with human parameters. METHODS: 15 guinea pigs were used for this study. Video recordings of their behavior in a quiet environment and under certain stimulus were performed to study the blinking and sleeping dynamic. Test de Schirmer, Inferior tear meniscus height measurement, Break up time (BUT) test were performed, with the aim of analyze the tear film production and stability. RESULTS: The guinea pig blinks in both a complete and a partial way, being more frequent the last one. The blink type and frequency were: Total = 2.35± 0.87; complete= 0.68±0.43; partial=1.49±0.75. The blink frequency is 5 times smaller than in humans. The eyelid response against different external stimuli was poor. The night habits of this animals were different compared with other rodents, they sleep for a short periods of time. They often do not close their eyes completely. Schirmer test in guinea pigs was 8.14±1.86 mm/5 min (humans: 11.9 ± 6.79 mm/5 min). Inferior tear meniscus height measurement in guinea pigs was 0,206 ± 0,059 mm (humans: 0,277 ± 0,033 mm). BUT in Guinea Pig: 2-3 min. (Humans: 10-15 seg). CONCLUSIONS: Guinea Pigs have a short blink frequency unlike humans, a decreased tear production, and an increased tear film stability. (AU)

Bevacizumab intravítreo como tratamiento de maculopatías miópicas neovasculares / Intravitreal bevacizumab for neovascular myopic maculopathy

INTRODUCCIÓN: La miopía patológica es una causa importante de pérdida de visión irreversible y es la cuarta a novena causa más frecuente de ceguera en el mundo. Es también conocida como miopía alta, degenerativa o maligna; condición en la que los individuos tienen una longitud axial superior a 25,5 - 26,5mm, y/o un error de refracción de por lo menos -5.0 dioptrías, acompañado por cambios patológicos. La neovascularización coroidea (NVC) asociada a miopía patológica puede resultar en la pérdida significativa de la visión y/o la ceguera. La NVC suele ser subfoveal y es una importante complicación, desarrollándose en aproximadamente 5-10% de ojos con miopía patológica. De manera similar que en otras enfermedades maculares asociadas a NVC, se ha encontrado un aumento del nivel del factor de crecimiento de endotelial (VEGF) en NVC miópicas, y por lo tanto, la terapia anti-VEGF sería útil. Desde la introducción en oftalmología de agentes anti factor de crecimiento de endotelial (anti-VEGF), el tratamiento anti-angiogénico con antiVEGF intravítreo se ha convertido en el tratamiento de primera línea para la NVC miópica. El bevacizumab es un anticuerpo monoclonal humano, anti factor de crecimiento endotelial (anti-VEGF), que inhibe la proliferación de nuevas células endoteliales produciendo un bloqueo de la fosforilación de las uniones estrechas (tight junctions) de las mismas. Este mecanismo produciría una mejoría anatómica-funcional en los pacientes e impediría una de las complicaciones más importantes de esta patología como lo es la neovascularización. OBJETIVO: Evaluar la eficacia de bevacizumab intravítreo (Avastin ®™) como tratamiento de la neovascularización coroidea (NVC) en miopías patológicas. PACIENTES Y MÉTODOS: Se evaluaron retrospectivamente 22 pacientes con diagnóstico de maculopatía miópica neovascular tratados mediante inyección intravítrea de bevacizumab, con un seguimiento mínimo de 12 meses. La agudeza visual se evaluó mediante tabla de Snellen y se convirtió en unidades LogMAR. El espesor macular se evaluó mediante tomografía de coherencia óptica (OCT). Las variables cuantitativas se analizaron mediante medidas de tendencia central, dispersión y forma. Los cambios en la agudeza visual se calcularon utilizando la prueba de Wilcoxon para variables apareadas y con la prueba de Mann Whitney para comparar variables independientes. Las diferencias entre variables continuas con distribución normal y de muestras independientes fueron calculadas mediante la prueba T de Student. RESULTADO: Se estudiaron 22 pacientes con diagnóstico de maculopatía miópica neovascular, cuya edad promedio fue de 59,68 (de 11,75; rango 34,00 ­ 85,00), de los cuales 7 (31,8%) fueron hombres y 15 (68,2%) fueron mujeres. El tiempo de seguimiento fue de 12 meses. El tiempo promedio transcurrido entre el comienzo de los síntomas y el inicio del tratamiento fue 38,68 (de 34,63) días. El 68,2% (15) de los pacientes consultaron por disminución brusca de la agudeza visual del ojo afectado y 31,8% (7) consultaron por metamorfopsias. Todos los pacientes presentaron miopía patológica (> 5.0 dioptrías). La cantidad total de inyecciones durante el seguimiento tuvo una media de 4,27 (DE 1.86; Rango 2,00 ­ 9,00), con un máximo de 9 inyecciones y un mínimo de 2 inyecciones. Durante los primeros 6 meses se realizaron la mayor parte de las inyecciones con una media de 3,36 (DE 1,22; Rango 1,00 ­ 6,00). La mediana de la AV al momento del tratamiento fue de 1,00 (P25-75=0,40-1,00). Al analizar la totalidad de los pacientes se encontró que existe una diferencia significativa al comparar las agudezas visuales previas al tratamiento y a los 12 meses de tratamiento (p=<0.0001). La mejoría franca de la AV se observó entre el primer mes (mediana= 1.00 RIQ= 0,6) y los 3 meses de tratamiento (mediana= 0,60 RIQ= 0,6) (p= 0,0002), mientras que no hubo diferencias significativas en la variación de la AV más allá de los 3 meses de seguimiento (p= 0,09). Al estudiar los espesores maculares antes del tratamiento, encontramos una mediana de 290 (RIQ=105); mientras que a los 12 meses de seguimiento fue de 269,50 (RIQ= 91). Teniendo en cuenta el total de los pacientes estudiados, no hubo diferencias significativas en el análisis del espesor macular medido por OCT antes y después del tratamiento (p=0,8812). CONCLUSIONES: El bevacizumab fue eficaz en el tratamiento de la maculopatía miópica, si bien no se encontraron diferencias significativas en la variación del espesor macular. En nuestra serie no hubo complicaciones oculares ni sistémicas vinculadas al tratamiento. (AU)

BACKGROUND: Pathological myopia is observed in about 2% of the general population. Submacular choroidal neovascularization is a leading cause of severe visual loss and blindness in eyes with pathological myopia, affecting 4-11% of those eyes. PURPOSE: Our aim is to evaluate the efficacy and safety of intravitreal bevacizumab in the treatment of neovascular myopic maculopathy (NMM). PATIENTS AND METHODS: 22 nonpreviously treated eyes of 22 consecutive patients with NMM. were reated with monthly intravitreal injections of bevacizumab and followed up for 12 months. Changes in BCVA and central macular thickness were evaluated at 12 months of follow-up. Snellen best-corrected visual acuity (BCVA) was converted into LogMAR units. Mean central macular thickness was obtained by means of spectral domain optical coherence tomography (SP-OCT). Quantitative variables were analyzed with central tendency, dispersion and shape. Changes in BCVA were calculated with Wilcoxon test in paired variables. Mann Whitney test was used to compare independent variables. Differences between continuous variables with normal distribution and independent samples were calculated with the Student T test. Main outcome measures: Changes in BCVA and central macular thickness at12 months of follow-up. RESULTS: Mean age was 54.45 (SD 12.30; r= 28.00 ­ 79.00); 7 patients (31.8%) were male and 15 (68.2%) female. Mean spherical equivalent refractive error was -10.89±4.13 (r= 7.00 to -21,00) Mean time elapsed between initial symptoms and the beginning of treatment was 38.68 (SD34.63) days. Patients received a mean of 4.27 (SD 1.86; r=2.00 to 9.00) injections. Most injections were performed during the first 6 months of treatment (mean 3.36 months; SD 1.22; r=1.00 to 6.00). Median BCVA at baseline was 1.00 (P25-75=0.40-1.00) and at 12 months 0.45 (P25-75=0.30- 0.70) (p<0.0001). Significant visual improvement was observed between the first (median=1.00, IQR= 0.6) and the third month of treatment (median=0.60, IQR=0.6) (p=0.0002), with no further significant improvement (p=0.09). No ocular or systemic side effects attributable to treatment were observed. When comparing patients 55 years old or younger with those older, and between both genders, all individuals improved, although not significantly (Mann Whitney for age P=0.1765; gender P=3454). No significant improvement in macular thickness was observed (pretreatment median thickness 290 microns, IQR=105; month 12 post-treatment median thickness 269.5 microns, IQR=91) (P=0.8812). CONCLUSIONS: Bevacizumab was effective and safe in our series of myopic patients with neovascular maculopathy, and visual gain remained stable during follow-up. (AU)

Bevacizumab intravítreo en el tratamiento de las oclusiones venosas de la retina / Bevacizumab in the treatment of macular edema complicating retinal vein occlusions

INTRODUCCIÓN: Dentro de las vasculopatías retinianas, las oclusiones venosas de la retina (OVR) representan la segunda causa más frecuente de pérdida de visión luego de la retinopatía diabética. Se han descripto dos tipos diferentes de OVR: la oclusión de vena central de la retina (OVCR), y la oclusión de rama venosa retinal (ORVR). De acuerdo al compromiso oclusivo del lecho capilar de la retina, se las clasifica en isquémicas (o no perfundidas), y no isquémicas (perfundidas), presentando una patogénesis, diagnóstico, pronóstico y tratamiento diferente. Se ha demostrado que los niveles de factor de crecimiento vascular endotelial (VEGF) aumentan significativamente en las oclusiones venosas retinianas, lo que tiene como consecuencia una disfunción de la barrera hematorretinal y el aumento de la permeabilidad vascular, con el consecuente edema macular. La inyección intravítrea de bevacizumab, un anticuerpo monoclonal recombinante que actúa en forma directa contra cualquier forma activa de VEGF, ha demostrado ser efectiva para reducir el espesor macular y mejorar la agudeza visual en el tratamiento de OVR. OBJETIVO: Evaluar los cambios en la agudeza visual y en los espesores maculares de pacientes con oclusiones venosas retinianas tratados con inyecciones intravítreas de bevacizumab. Pacientes y métodos: Se evaluaron retrospectivamente 39 pacientes con diagnóstico de oclusión venosa retiniana (OVR) complicada de edema macular y tratados mediante inyección intravítrea de 1,25 mg/0,05 ml bevacizumab (Avastin®, Roche Diagnostic GmbH, Manheim, Alemania), con un seguimiento mínimo de 18 meses. La agudeza visual se evaluó mediante tabla de Snellen y se convirtió en unidades LogMAR. El espesor macular se evaluó mediante tomografía de coherencia óptica (OCT). Según la presentación clínica se las clasificó en: 1. Oclusión de rama (ORVR), incluyendo las oclusiones hemisféricas y 2. Oclusión de vena central (OVCR), incluyendo oclusión venosa hemicentral. A su vez, mediante angiografía fluoresceínica se las clasificó en oclusiones predominántemente isquémicas, y predominántemente no isquémicas. Las variables cuantitativas se analizaron mediante medidas de tendencia central, dispersión y forma. Los cambios en la agudeza visual se calcularon utilizando la prueba de Wilcoxon. Las diferencias entre variables continuas fueron calculadas mediante la prueba T de Student para variables paramétricas, y Mann Whitney para variables no paramétricas. RESULTADOS: La edad promedio fue de 66,8 años (DE: 13,65; rango= 31-92 años). El 55% de los casos estudiados fueron OVCR y el 37,5% ORVR. La media del total de inyecciones durante los 18 meses de seguimiento fue de 4,11±1,61 (rango= 1 a 6). La terapia con láser de rescate se realizó en 10 (25%) pacientes. Todos los pacientes que debieron ser tratados con láser tuvieron una AV inferior a 1 décima al final del seguimiento. La agudeza visual promedio al inicio del tratamiento fue de 1,092 con una desviación estándar (DE) de 0,36, con un rango de 0,10 y 1,60. Tras el inicio del tratamiento, todos los grupos de pacientes logran un incremento significativo en la AV (P= <0,0001). A los 18 meses de tratamiento la agudeza visual promedio fue de 0,739 con una DE de 0,45 con un rango de entre 0,00 y 1,50. La agudeza visual media de los pacientes con OVCR antes del tratamiento fue de 1,09 (DE: 0,35; rango= máxima 0,50 y mínima 1,60), y a los 18 meses de tratamiento de 0,87 (DE: 0,73; rango= 0,20 a 1,50). En cambio, los pacientes con ORVR antes del tratamiento presentaron una media de 1,10 (DE: 0,31; rango= máxima de 0,40 y mínima de 1,6), y luego del tratamiento una media de 0,53 (DE: 0,38; rango= máxima 0,1 y mínima 1,2). El 54,5% de los casos fue de predominio isquémico o mixtos, y el 43,5% fue a predominio edematosos al inicio del tratamiento. La agudeza visual media de los pacientes con tipo edematoso fue de 0,93 (DE: 0,34; rango= máxima 0,10 y mínima 1,40), mientras que los pacientes con patología isquémica presentaron una media de 1,25 (DE: 0,32; rango= máxima de 0,40 y mínima de 1,6). Ambos grupos respondieron en forma significativa al tratamiento (p< 0.05). Sin embargo, los pacientes con predominio edematoso lograron una mejoría mayor que aquellos con predominio isquémico. (P=0.0054) La agudeza visual media de los pacientes con predominio edematoso a los 18 meses del tratamiento fue de 0,50 (DE: 0,44; rango= máxima 0,0 y mínima 1,40), mientras que los pacientes con predominio isquémico presentaron una media de 0,97 (DE: 0,35; rango= máxima 0,20 y mínima 1,4). La media de los espesores maculares previo al inicio del tratamiento fue de 654.19 ± 272.05 micras (rango= 215 a 1497 micras), mientras que la media luego del tratamiento fue de 449 ± 247,62 micras (rango= 140 a 1005 micras) (p=0,0009). No hubo efectos colaterales ni complicaciones locales ni sistémicas atribuibles a la inyección de bevacizumab durante el seguimiento. CONCLUSIÓN: El bevacizumab fue eficaz en el tratamiento del edema macular secundario a OVR. La respuesta terapéutica fue mayor en las ORVR. En nuestra serie no hubo complicaciones oculares ni sistémicas vinculadas al tratamiento. (AU)

INTRODUCTION: Within the retinal vascular disease,retinal venous occlusion (RVO) represents the second most common cause of vision loss after diabetic retinopathy. In turn, it is estimated that the RVO affects approximately 1.6% of people worldwide. It has been described two different types of RVO: the central retinal vein occlusion (CRVO), which includes the hemicentral retinal vein occlusion (HCRVO), and the branch retinal vein occlusion (BRVO), which includes Major BRVO (occlusion of a retinal vein that drains one of the quadrants or more), Minor BRVO (occlusion of a retinal vein that drains less than a quadrant) and Hemispheric retinal vein occlusions (half or more of the retina). According to the occlusive pattern of the retinal capillary bed, this disease is classified as ischemic (or non perfused); when the areas of noncapillary perfusion, seen under fluorescein angiography, have an extension of more than 10 disc diameters; and non-ischemic (o perfused), presenting a pathogenesis, diagnosis, prognosis and different treatment. Non-ischemic form is generally more benign, with a less dramatic visual impairment, a greater chance of spontaneous recovery, a better treatment response, and generally has no risk of neovascularization. Instead; ischemic form is much more severe, causing a more dramatic visual acuity decline, with little chance of clinical improvement, an increased risk of blindness and an increased risk of neovascularization. Although the physiopathogenesis of OVR is not accurately known, it is suggested that the thickening and stiffness of arteries and arterioles caused by arteriosclerosis leads to compression of the retinal veins at the sites where adventitia is shared with arteries (in its intraneural route to the optic nerve and the arteriovenous crossings), leading eventually to a turbulent blood flow, damage to endothelial cells, thrombus formation and eventual vein occlusion. This theory is supported by studies showing pathological structural changes in veins and arteries of patients with VO. Moreover, other factors related to venous deregulation, such as inadequate vasoconstriction and increased vascular permeability, could also play an important role in the retinal venous occlusive phenomena. In some patients, especially young people and adults under 50 years old, inflammatory disorders and hypercoagulable states may contribute to the hysiopathogenesis of the RVO. It has been shown that the presence of vascular endothelial growth factor (VEGF) increased significantly the chances to develop retinal vein occlusions. The result is a blood­retinal barrier dysfunction and an increased vascular permeability, with consequent macular edema. It has also been reported that VEGF plays an important role in the pathogenesis of macular edema in both ORV and CRVO.10 While there is insufficient level 1 evidence to support OVR treatment, multiple therapeutic possibilities have been described, such as anticoagulation, intravitreal fibrinolysis, hemodilution, laser photocoagulation, laser-induced anastomosis, radial optical neurotomy, adventiciotomía, intravitreal injection of triamcinolone acetonide, intravitreal injection of dexamethasone, and injection intravitreal antiangiogenic monoclonal antibodies, such as ranibizumab, bevacizumab, and aflibercept, alone or associated with photocoagulation, have shown efficacy and variables complications rates. Intravitreal injection of bevacizumab, a recombinant monoclonal antibody that acts directly against any active form of VEGF, has been shown to be effective in reducing macular thickness and improving visual acuity in the treatment of OVR. However, the need for multiple injections has been reported since the effects of intravitreal bevacizumab (as well as the other antiangiogenics) are short-lived. On one hand, Bevacizumab has the disadvantage that it is administered off-label; in addition each dose must be extracted from a vial for oncological use, which represents a risk of contamination if strictly rules of asepsis are not taken. On the other hand, the cost of each dose is lower than that of other products (ranibizumab, aflibercept) already approved for intraocular use. This allows that more patients have access to a prolonged treatment in underdeveloped or developing countries, such as Argentina. PURPOSE: To evaluate changes in visual acuity and macular thickness after intravitreal bevacizumab for the treatment of macular edema in patients with retinal vein occlusions (RVO). PATIENS AND METHODS: 39 consecutive patients with macular edema complicating RVO and treated with intravitreal injections of bevacizumab 1.25 mg/0.05 ml alone or associated with scattered peripheral laser photocoagulation, with a minimun follow-up of 18 months, were evaluated. Snellen visual acuity in LogMar units and macular thinckness measured by optical coherence tomography (OCT) were the end points. According to clinical and fluorescein angiographic presentation RVO were classified in branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO), and in non ischemic and ischemic. Wilcoxon test for paired variables, Mann Whitney for independant variables, and Student test for continuous variables, were used for statistical analysis. RESULTS: With a mean age of 66.8 years (SD: 13.65; range= 31-92 years), 62.5% of cases were CRVO and 37.5% BRVO. Mean number of injections was 4.11±161 (range= 1-6). Laser was performed in 25% of patients that did not respond to bevacizumab. At 18 months of follow-up, improvement of visual acuity and macular thickness was statistically significant (p=0.0001 and p=0.0009 respectively). BRVO showed better response to treatment than CRVO. Best visual results were obtained at first month (median= 1.00 P25= 0.5 P75= 1.30) and at 9 month (median= 0.8 P25= 0.5 P75= 1.20) after first injection, but no further improvement was observed beyond 9 months of treatment (p=0.84). No significant visual and macular thickness differences were obtained between patients treated with bevacizumab alone (p=0.116) and bevacizumab and laser (p=0.846). No ocular or systemic attributable-to-treatment side effects were observed. CONCLUSIONS: Bevacizumab was effective in improving visual acuity and reducing macular thinckness in patients with macular edema complicating RVO, especially in BRVO. No ocular or systemic complications were observed during follow-up. (AU)

Effects produced by different types of laser in cornea of Guinea pigs: Identification of a laser capable of producing superficial lesions without leaving scars.

PURPOSE: Climatic droplets keratopathy (CDK) is closely associated with superficial corneal erosions and lack of protective mechanisms against the harmful effects of ultraviolet radiation (UVR) during a prolonged period of time. One of the difficulties in studying the pathogenic mechanisms involved in this human disease is the lack of an experimental animal model. In this paper, a study is conducted on the effects of 4 types of lasers at various powers and time conditions on the normal guinea pig corneas in order to select only one laser condition that reversibly injures the epithelium and superficial stroma, without leaving scarring. METHODS: Damage was induced in the cornea of Guinea pigs using different powers and exposure times of 4 types of laser: argon, CO2, diode and Nd-Yag, and any injuries were evaluated by biomicroscopy (BM) and optical microscopy. Corneas from other normal animals were exposed to argon laser (350 mW, 0.3s, 50 µm of diameter), and the induced alterations were studied at different times using BM, optical coherence tomography (OCT) and transmission electron microscopy (TEM). RESULTS: Only argon laser at 350 mW, 0.3s, 50 µm of diameter produced epithelium and superficial stroma lesions. Some leukomas were observed by BM, and they disappeared by day 15. Corneal thickness measured by OCT decreased in the eyes treated with argon laser during the first week. Using TEM, different ultra structural alterations in corneal epithelium and stroma were observed during the early days, which disappeared by day 15. CONCLUSIONS: It was possible to develop reproducible corneal epithelium and anterior stroma injuries using Argon laser at 350 mW, 0.3s, 50 µm of diameter. In vivo and in vitro studies showed that injured corneas with these laser conditions did not leave irreversible microscopic or ultra structural alterations. This protocol of corneal erosion combined with exposure to UVR and partial deficiency of ascorbate in the diets of the animals for an extended period of time has been used in order to try to develop an experimental model of CDK.

On the Cornea of Healthy Merino Sheep: A Detailed Ex Vivo Confocal, Histological and Ultrastructural Study.

Our study performed qualitative and quantitative studies on the corneal ultrastructure of healthy female Merino sheep of ages 4 months and 6 years old from the Argentinean Pampa. The corneas were evaluated using ex vivo laser-scanning confocal microscopy, light microscopy and transmission electron microscopy. Those studies allowed us to obtain detailed images of the corneal layers as well as quantitative data of the cellular and sub-basal nerve densities in the cornea from sheep of different ages. The density of the corneal cells was significantly different in the anterior versus the posterior epithelium and stroma. Moreover, the density of the epithelial, stromal cells and endothelial cells, as well as the sub-basal nerve density were significantly lower in adult than in young animals. Our work provided a wide-ranging description of the corneal ultrastructure of healthy female Merino sheep, which adds to the current knowledge about the ophthalmological aspects of this species and undoubtedly benefits veterinarians.

IgE sérica e IgA salival, total y específica para Dermatophagoides pteronyssinus y subpoblaciones leucocitarias en niños atópicos y no atópicos con asma y/o rinitis / Total and Dermatophagoides pteronyssinus specific IgE and salivary IgA and leukocyte populations in atopic and nonatopic children with asthma and/or rhinitis

Objetivo. Investigar inmunológicamente niños con problemas respiratorios de asma y/o rinitis (atópicos o no atópicos) en la búsqueda de evidencias que permitan una mejor comprensión del desbalance que padecen estos niños en su sistema inmune. Materiales y métodos. Se estudiaron 47 niños de ambos sexos, con edades comprendidas entre los 6 y 15 años, que concurrieron a la consulta por afecciones respiratorias compatibles con asma y/o rinitis a la División de Alergia e Inmunología del Hospital de Niños de la Santísima Trinidad de la Ciudad de Córdoba. Según la información obtenida en la anamnesis, examen físico y prick tests, fueron divididos en dos grupos: atópicos (n=25) y no atópicos (n=22). Luego que los padres firmaron el consentimiento informado y los niños mayores a 7 años dieron su asentimiento para participar del trabajo de investigación, se tomaron muestras de sangre y saliva, para determinar concentración y actividad específica en inmunoglobulinas (Igs) así como estudiar poblaciones leucocitarias y subpoblaciones linfocitarias. Resultados. Como era previsible, los niveles de IgE sérica total y los porcentajes relativos de eosinófilos sanguíneos se mostraron significativamente elevados en el grupo de los niños atópicos (A) con respecto a los no atópicos (NA). El estudio de IgE sérica específica para Dermatophagoides pteronyssinus solo arrojó resultados positivos en los pacientes A y se observó una correlación significativa entre los niveles de IgE total y específica para dicho alérgeno, y entre los niveles de prick y RAST. Los niveles séricos de IgG e IgA no demostraron diferencias de significación entre ambos grupos. El estudio de la IgA salival (IgAs) total permitió observar en el grupo de los niños NA concentraciones significativamente mayores que las correspondientes al grupo de pacientes A. Sin embargo, al estudiar la IgAs específica para el D. pteronyssinus, se observó lo inverso: los pacientes A tienen casi el doble de IgAs específica para el alérgeno respecto del grupo NA. En el estudio de subpoblaciones de células T (CD3, CD4 y CD8), no se observaron diferencias significativas entre ambos grupos. Las subpoblaciones de linfocitos B CD27-y linfocitos B CD27+ tuvieron valores similares en ambos grupos (aproximadamente 80% y 20%, respectivamente). En ambos grupos, alrededor de un 50% de los linfocitos B CD27+ expresaron IgD y el 50% restante fueron IgD­. Sin embargo, el grupo de niños A tuvo dos veces menos de linfocitos B que expresan alta densidad de la molécula CD27 (CD27+++) con respecto a los niños NA (p=0,044). Conclusión. Entre los parámetros inmunológicos investigados encontramos diferencias significativas entre niños A y NA en las concentraciones totales y específicas para el D. pteronyssinus en los isotipos de IgE e IgAs, y en una subpoblación de linfocitos B CD27+++. Dichos hallazgos son analizados en la discusión del manuscrito. (AU)

Purpose. To perform an immunologically investigation in children with respiratory problems of asthma and/or rhinitis (atopic or non atopic) in order to get a better understanding of the immune system imbalance in these patients. Materials and methods. 47 children of both sexes, aged between 6 and 15 years, who were attended for respiratory diseases at the Division of Allergy and Immunology at Children's Hospital de la Santísima Trinidad from Córdoba city were studied. According to information obtained on clinical history, physical examination and prick tests they were divided into two groups: Atopics (n=25) and non-atopic (n=22). After parents signed informed consent and children over 7 years assent to participate in the research work, samples of blood and saliva were taken to determine immune globulins concentrations and specific activities as well as to study leukocyte populations and lymphocytes subpopulations. Results. As expected, levels of total serum IgE and the relative percentages of blood eosinophils were significantly higher in the group of atopic (A) children with regard to non¬atopic (NA) children. The study of specific serum IgE for Dermatophagoides pteronissynus only showed positive results in the A group, and positive correlations between the levels of total and specific IgE, as well as prick and RAST values. Serum IgG and IgA levels showed no significant differences between both groups. Total salivary IgA concentrations were significantly higher in the group of NA children than in the group of A patients. Surprisingly, when specific salivary IgA for D. pteronyssinus was studied, the opposite was observed: Atopic patients have nearly twice specific salivary IgA for this allergen than the NA children. In the study of T cells subpopulations (CD3, CD4 and CD8), no significant differences between groups were observed. The subpopulations of CD27-B cells and CD27+ B cells were similar in both groups (roughly 80% and 20%, respectively). In both groups, approximately 50% of CD27+ B cells expressed IgD and the remaining 50% were IgD­. However, atopic children had less than half B cells expressing high density of CD27 molecule (CD27+++) with respect to the NA children (p=0.044). Conclusion: Among the immunological parameters investigated, we found significant differences between A and NA children in the concentrations of total and specific IgE and salivary IgA to the allergen, and in a subpopulation of CD27+++ B cells. These findings are debated in the discussion of the manuscript(AU)

Estudio del polimorfismo del gen de TNF-α, de dicha citocina, y de MCP-1 en pacientes con queratopatía climática esferoidea / Studies of TNF-α gene polymorphism, TNF-α and MCP-1 cytokines in patients with spheroidal climatic keratopathy

Objetivo. Investigar polimorfismo de nucleótidos únicos (SNP) en la posición -308 (G/A) del gen TNF-α y la participación de las citocinas TNF-α y MCP-1 en pacientes con queratopatía climática esferoidea (QCE) y en controles sanos. Materiales y métodos. Participaron 15 pacientes con QCE y 15 individuos sanos del departamento El Cuy, Provincia de Río Negro. Todos ellos, luego de firmar el consentimiento informado, recibieron un examen oftalmológico completo y se recolectaron muestras de sangre y lágrima para realizar diferentes estudios. EL ADN genómico fue obtenido de sangre de todos los individuos mediante el método de salting out y posteriormente amplificado y estudiado mediante reacción en cadena de la polimerasa (PCR) con el sistema de amplificación refractaria a la mutación (ARMS). También se investigaron concentraciones de algunas citocinas proinflamatorias en lágrimas y en sobrenadante de cultivo de células epiteliales corneales humanas (CECH) tratadas o no con radiación ultravioleta B (RUV-B). Resultados. Los resultados de SNP en la posición -308 (G/A) del gen TNF-α (frecuencia alélica y genotípica) indicaron ausencia de diferencias significativas entre pacientes y controles sanos. Fenotípicamente ambos grupos de individuos serían bajos o intermedios productores in vitro de la citocina TNF-α. Sin embargo en las lágrimas de pacientes con QCE se detectaron concentraciones significativamente superiores de TNF-α, IL-1ß y MCP-1 (citocinas proinflamatorias) que en lágrimas de individuos controles sanos (p<0,0001) En la periferia y limbo de la córnea las células dendríticas (CD) incrementaron significativamente con el progreso de la enfermedad (p<0,05). La contribución del epitelio corneal en el proceso inflamatorio fue investigada utilizando CECH expuestas o no a 10 mJ/cm2 de RUV-B. A pesar de la presencia de gelatinasas, IL-6 e IL-8 en sobrenadantes de cultivos obtenidos a las 48 horas (datos no mostrados) no observamos niveles detectables de TNF-α, IL-1ß ni MCP-1. Conclusión. Este trabajo aporta nuevos datos para aumentar los conocimientos sobre los mecanismos inmunológicos involucrados en la etiopatogenia y progresión de la QCE. Demostramos que las citocinas proinflamatorias MCP-1 y TNF-α están significativamente elevadas en lágrimas de individuos con QCE, como se observó previamente con IL-1ß. MCP-1 sería la responsable del aumento de CD en córnea periférica y limbo de estos pacientes a medida de que la enfermedad avanza. El hallazgo de que estas citocinas no pudieron ser detectadas en cultivos de CECH estresadas con RUV-B implica que otras células son las responsables de su producción o que además de RUV-B otros factores son necesarios para iniciar esta cascada de eventos que se observan en esta hipersensibilidad corneal humana(AU)

Purpose. To investigate Single Nucleotide Polymorphism (SNP) at -308 position (G/A) of TNF-α gen and involving of TNF-α and MCP-1 cytokines in Climatic Droplet Keratopathy (CDK) patients and healthy controls. Materials and methods. Fifteen patients with CDK and fifteen healthy controls from departamento El Cuy, province of Rio Negro were involved in this study. After informed consent was obtained from all participants, they had a complete eye examination and then tear and blood samples were collected to perform different assays. DNA was obtained from blood of all individuals using the method of "salting out" and then amplified and studied performing the polymerase chain reaction (PCR) with Amplification-refractory Mutation System (ARMS). Furthermore, some cytokines concentrations were measured in tears and supernatants from human corneal epithelial cells (HCEs) exposed or not to UVR-B radiation. Results. Analysis from SNP at position -308 (G/A) of TNF-α gen (allelic and genotypic frequency) showed no significant differences between patients and healthy controls. Phenotypically both groups of individuals would be low or intermediate in vitro producers of TNF-α cytokine. However, in tears from CDK's patients we detected significantly higher concentrations of TNF-α, IL-1ß and MCP-1 (pro-inflammatory cytokines) than in healthy control subjects tears (p<0.0001). At the corneal peripheral / limbus area, dendritic cells (DCs) increased significantly with the progression of the disease (p<0.05). The corneal epithelium contribution to the inflammatory process was investigated using HCEs exposed or not to 10 mJ/cm2 of UV radiation­B (UVR-B). Despite the presence of gelatinases, IL-6 and IL-8 in culture supernatants obtained after 48 hours (data not shown), detectable levels of TNF-α, IL-1ß and MCP-1 were not detected. Conclusion. This study provides new insights to increase our knowledge about the immunological mechanisms involved in the etiopathogenesis and progression of CDK. We showed that pro-inflammatory cytokines MCP-1 y TNF-α were significantly increased in tears from CDK's patients, as previously described with IL-1ß. MCP-1 would be responsible for the increasing of DCs on the corneal peripheral / limbus area of these subjects as the disease progresses. The fact that these cytokines could not be detected in cultures of HCEs stressed with UVR-B implies that other cells are responsible for their production or, in addition to UVR-B, other factors are necessary to initiate the cascade of events observed in this human corneal hypersensitivity. (AU)

Participación de componentes inmunológicos en la etiopatogenia de la queratopatía climática esferoidea / Involvement of immune components in the etiopathogenia of climatic droplet keratopathy

Objetivo. Investigar si componentes de la inmunidad innata están involucrados en la iniciación/perpetuación de las anormalidades estructurales observadas en la capa de Bowman y el estroma superficial de la córnea de pacientes con queratopatía climática esferoidea (QCE). Materiales y métodos. En el estudio participaron 8 pacientes con QCE y 12 individuos sanos del Departamento El Cuy, Provincia de Río Negro, y 10 individuos sanos de la ciudad de Córdoba. Todos ellos, luego de firmar el consentimiento informado, recibieron un examen oftalmológico completo y se recolectaron muestras de lágrima para estudiar las concentraciones de diferentes citocinas, niveles y formas de metaloproteinasas de matriz (MMPs), y el inhibidor natural de MMPs (TIMP-1). Se realizó microscopía confocal in vivo (MCF) en algunos pacientes y controles. Biopsias de córneas provenientes de pacientes que fueron tratados con queratoplastia penetrante también fueron estudiadas mediante inmunohistoquímica (IHQ). Resultados. Los resultados de MCF indicaron claramente una progresión en la cantidad de depósitos a nivel subepitelial, a medida que la enfermedad avanza. El daño progresivo de las fibras nerviosas sub basales y estromales en los estadios 2 y 3 se correlaciona con pérdida de la sensibilidad corneal. Además de estas alteraciones, observamos que el número de células dendríticas (CD) en el limbo corneal aumentó significativamente a medida que la QCE progresa. En lágrimas de pacientes con QCE se detectaron concentraciones significativamente superiores de citocinas proinflamatorias (IL1ß e IL-8) que en individuos controles (p<0,005). No se halló IL-2, IL-17, IL-4, IL-13 ni IL-10 en pacientes y ni controles. Las actividades de gelatinasas (MMP-9 y -2) fueron significativamente mayores en QCE que en los controles (p<0,001), mientras que los niveles de TIMP-1 fueron significativamente menores en los pacientes (p<0,05). La concentración de MMP-8 fue mayor en controles pero los niveles de esta colagenasa-2 fueron 30 veces superiores, tanto en QCE como controles, con respecto a los valores de los individuos de un centro urbano. Mediante IHC observamos reactividad para MMP-9 en la mayoría de las células epiteliales, solamente en córneas con QCE. Conclusión. Demostramos un rol protagónico del eje citocinas proinflamatorias - gela-tinasas en el desarrollo de la QCE. Los altos niveles de IL-1ß e IL-8 en lágrimas de pacientes facilitan la producción de MMP-8 y gelatinasas, y los efectos de las mismas se exacerban, ya que los pacientes tienen bajos niveles de sus inhibidores naturales (TIMP-1). La MMP-9, además de degradar componentes de la matriz extracelular, cataliza la activación postranscripcional de IL-1ß, potenciando el proceso inflamatorio. Estos resultados son los primeros en explicar mecanismos inmunológicos involucrados en la etiopatogénesis de la QCE y aportan nuevas alternativas para el desarrollo de terapias preventivas utilizando inhibidores de IL-1ß y/o gelatinasas(AU)

Objective. To investigate whether components of innate immunity are involved in the initiation / perpetuation of the structural abnormalities observed in Bowman's layer and superficial stroma of the córnea of patients with Climatic droplet keratopathy (CDK). Materials and Methods. The study included 8 CDK patients and 12 healthy individuals from Department El Cuy, Province of Río Negro, and 10 healthy subjects from the city of Córdoba. All of them, after signing informed consent, received a thorough eye exam and tear samples were collected to study the concentrations of different cytokines, and levels and forms of matrix metalloproteinases (MMPs) and their natural inhibitor (TIMP-1). In vivo confocal microscopy (CFM) was performed in some patients and controls. Corneal biopsies from CDK patients treated with penetrating keratoplasty were also studied by immunohistochemistry (IHC). Results. CFM results clearly indicated a progression in the amount of deposits at corneal sub epithelial level as the disease progresses. The progressive damage in the nerve plexus in stages 2 and 3 correlated with a loss of corneal sensitivity. In addition to these alterations, we observed that the number of dendritic cells (DC) in the limbus increased significantly as the disease progresses.In tears of patients with CDK we detected significantly higher concentrations of pro-inflammatory cytokines (IL-1ß and IL-8) than in control subjects (p < 0.005). We found no IL-2, IL-17, IL-4, IL-13 and IL-10 in patients and controls. The activities of gelatinases (MMP-9 and -2) were significantly higher in CDK than in controls (p < 0.001), while TIMP-1 levels were significantly lower in patients (p < 0.05). The concentration of MMP-8 was higher in controls, but levels of this collagenase-2 were 30 times higher, both in CDK and controls, with respect to MMP-8 values of individuals inhabiting an urban area. By IHC we observed reactivity for MMP-9 in most epithelial cells only in CDK corneas. Conclussion. We demonstrated a key role of the axis pro-inflammatory cytokines ­ gelatinases in the development of CDK. High levels of IL-1ß and IL-8 in tears of patients facilitate the production of MMP-8 and gelatinases, and the effects of these molecules are exacerbated because patients have low levels of their natural inhibitors (TIMP-1). Since MMP-9 besides degrading extracellular matrix components, catalyzes the post translational activation of IL-1ß, the inflammatory process is fuelled. These results are the first to explain immunological mechanisms involved in the pathogenesis of the QCE and provide new alternatives for the development of preventive therapies using inhibitors of IL-1ß and / or gelatinases.(AU)

Cavidad oral: importante sitio de vigilancia inmunológica / Oral cavity: important site for immune surveillance

La cavidad oral es el principio del tracto digestivo y uno de los sitios del cuerpo más expuestos al ingreso de todo tipo de patógenos, tanto del aire como de los alimentos. Aunque varios excelentes artículos han examinado distintos aspectos de tejidos linfoides asociados a mucosas (MALT), no hay suficiente información acerca de la respuesta inmune en la cavidad oral. En esta revisión destacamos algunos aspectos sobre la anatomía / histología de la cavidad oral, estructuras asociadas y células o moléculas con crucial función inmunológica contra antígenos que ingresan en la boca. Los estudios sobre la mucosa oral han adquirido mucha notoriedad últimamente debido a que ofrece una excelente accesibilidad y evita la degradación de las proteínas y péptidos. En la cavidad bucal se puede generar una respuesta inmune apropiada contra microorganismos, en donde además de la IgA salival muchas otras moléculas son liberadas y cumplen un rol protagónico. A pesar de todos estos factores de defensa, existen momentos en donde el individuo se encuentra más expuesto, dependiendo de la edad, factores hormonales, genéticos, hábitos de fumar y la actividad física, ya que todo esto modifica la tasa de flujo salival, tasa de secreción y concentración de IgA salival y demás proteínas. (AU)

The oral cavity is the beginning of the digestive tract and one of the most exposed body sites to the entry of all types of pathogens in the air as food. Although several excellent articles have examined various aspects of mucosa-associated lymphoid tissue (MALT), there is insufficient information about the oral cavity immune response. In this review we highlight some aspects of the anatomy / histology of the oral cavity, associated structures and cells or molecules with crucial immunological function against antigens that enter the mouth. Studies on the oral mucosa have gained much notoriety lately because it offers excellent accessibility and prevents the degradation of proteins and peptides. In the oral cavity can generate an appropriate immune response against microorganisms, where salivary IgA in addition to many other molecules are released and play a role. Despite these defense factors, there are moments where the individual is more exposed, depending on age, hormonal factors, genetic, smoking habits and physical activity, and that this changes the rate of salivary flow rate secretion and concentration of salivary IgA and other proteins.(AU)

What do we need to learn to optimize the SLIT alternative?

Allergen-specific immunotherapy (IT) is the only treatment of allergy in adults and children capable of modifying the immune response at early steps. As a consequence, IT improves symptoms, prevents the onset of new sensitizations, reduces the risk of developing asthma and its clinical efficacy lasts many years. The main rationale for administering sublingually IT (SLIT) is to reduce the occurrence of side effects, still yet preserving the immunological effects. SLIT with the most common allergens have been used in many studies with significant clinical effectiveness in both asthma and rhinitis. The pharmacokinetic of allergens administered through non injection routes is complex. Peptide absorption across oral mucosa occurs mainly by passive diffusion but delivery of proteins has some limitations. Moreover, the molecular mechanisms responsible for the efficacy of SLIT are poorly defined. In this review we focus on the anatomy/histology of the oral cavity as well as on the associated immunological structures to envisage what may happen when an allergen is kept in the mouth. Moreover, the induction of immune responses in this particular immunological environment is also discussed.

Is secondary lymphoid-organ chemokine (SLC/CCL21) much more than a constitutive chemokine?

Chemokines are a superfamily of small cytokines with activities ranging from leukocyte traffick to hematopoiesis, angiogenesis, and tissue organogenesis. Secondary lymphoid-organ chemokine (SLC/CCL21) was originally reported as a chemokine constitutively expressed by stromal cells and high endothelial venules in secondary lymphoid tissues and endothelium of afferent lymphatics, directing CCR7+ cells. More recently, others and we have demonstrated that SLC/CCL21 is up-regulated in different skin inflammatory conditions. Thereafter, this molecule is much more than a constitutive chemokine, which could play a role in effector and regulatory immune functions.

La "entrada y salida" de las células inmunitarias durante la inflamación de la piel: lecciones provenientes de las dermatitis alérgica e irritativa por contacto / The "in and out" of immune cells from the skin during inflammation: lessons from allergic and irritant contact dermatitis

El daño a nivel cutáneo puede tomar diversas formas entre las que se destacan la Dermatitis Alérgica por Contacto (DAC) y la Dermatitis Irritativa por Contacto (DIC). DAC es una enfermedad mediada por linfocitos Th1/ Tc1 y ha sido muy investigada debido a la disponibilidad de un modelo excelente en ratón y la facilidad para reproducir las lesiones en seres humanos. El término DIC es utilizado para describir cambios cutáneos no inmunológicos causados por contacto con sustancias del medio ambiente. En ambas enfermedades, keratinocitos, fibroblastos, células endoteliales y leucocitos infiltrantes interaccionan entre ellos bajo el control de una compleja red de citocinas y mediadores lipídicos. En esta revisión describiremos los mas recientes hallazgos respecto al rol que tienen los vasos sanguíneos y linfáticos en el desarrollo de DAC y DIC (AU)

Expression of CS-1 fibronectin precedes monocyte chemoattractant protein-1 production during elicitation of allergic contact dermatitis.

BACKGROUND: Leucocyte migration within inflammatory skin compartments in allergic contact dermatitis (ACD) is the result of a sophisticated multi-step event where multiple molecules are involved. OBJECTIVE: Since non-antigen-specific mechanisms have been described as an early participant in elicitation of ACD, we investigated the kinetics of the expression of monocyte chemoattractant protein-1 (MCP-1/CCL2) and the type of infiltrating cells. We compared the time course production of MCP-1/CCL2 with connecting segment-1 (CS-1) fibronectin and thymus and activation-regulated chemokine (TARC/ CCL17) expression. METHODS: Biopsies from 10 individuals challenged in their back with the antigen responsible for their contact dermatitis and an irrelevant antigen were taken at different times and histology, immunohistochemistry for CS-1 fibronectin, TARC/CCL17, CD3, CD68, CXCR3, CCR4 and in situ hybridization for MCP-1/CCL2 were performed. RESULTS: At positive antigen stimulated sites expression of MCP-1/CCL2 by basal keratinocytes and isolated cells in dermis started at 10 h. CS-1 fibronectin and TARC/CCL17 expression by blood endothelial cells was found at 2 and 10 h, respectively. This was followed by dermal accumulation of mononuclear cells with a significant increase of CD3+ and CD68+cells. At 48 h, approximately 58% of infiltrating cells were CXCR3+, and 35% CCR4+. CONCLUSIONS: We showed evidence of the fact that CS-1 fibronectin expression precedes the production of MCP-1/CCL2 and TARC/CCL17 in the skin of patients with ACD, suggesting that these molecules participate in the early complex process of migrating mononuclear cells during elicitation of ACD.

Clinical signs and symptoms are not enough for the correct diagnosis of allergic conjunctivitis.

BACKGROUND: Allergic Conjunctivitis (AC) has a high incidence in the general population and sometimes it is difficult to make a correct diagnosis, distinguish among the different subtypes of AC, and therefore, to indicate the suitable therapy. OBJECTIVE: To determine the best way to carry out an appropriate diagnosis of AC. METHODS: Thirty-one patients with clinical manifestations of AC and eleven controls were studied by measuring allergic and immunologic parameters. Only those patients confirmed as having AC were treated with ketotifen fumarate and further evaluated. RESULTS: According to allergic and immunological parameters, patients were divided into two groups. Group I patients had positive prick test toward at least one allergen, 60% exhibited high levels of tear-IgE, and only 36% conjunctival eosinophils. By contrast, patients from Group II had negative prick tests and laboratory findings similar to the control group. In group I there was a good correlation between levels of tear-IgE and eosinophils (r = 0.55; p = 0.009); key symptoms and signs and prick test (r = 0.52; p = 0.015), and prick test and eosinophils (r = 0.50 p = 0.022). The cardinal signs and symptoms scores dropped significantly in Group I as a consequence of the treatment (p < 0.0001). CONCLUSION: In order to have a reliable AC diagnosis, allergen-skin prick test, IgE in tears, and conjunctival eosinophils must be studied. Serum IgE is less important.

Seroprevalence of human herpesvirus 6 in Andino Puneños (Argentina).

We carried out a seroepidemiological survey to define the prevalence of human herpesvirus 6 (HHV6) infection in an aboriginal population (Andino Puneños) from a remote region in north-west Argentina. Antibodies against HHV6 (total IgG and the 4 subclasses of IgG) were studied in 84 serum samples (collected in 1995 and stored at -70 degrees C), using core blood mononuclear cells infected with HHV6 in an immunofluorescence assay. Of the 84 samples, 70 (83%; 95% confidence interval, 75-91%) exhibited IgG antibodies against HHV6. No significant differences in the frequency of humoral immunity were found among the 4 age-groups studied (mean ages 13, 31, 47 and 70 years) namely, 75%, 89.7%, 79.2% and 100%, respectively. HHV6-specific IgG1 was found in all the positive serum samples tested but none of them contained specific IgG2, IgG3 and IgG4. These results confirmed a high rate of infection with HHV6 within this aboriginal group in Argentina and an IgG1 anti-HHV6 activity compatible with a maintenance of immunity.

Injury prevention: is there a role for out-of-hospital emergency medical services?

OBJECTIVE: To review the literature for options for integrating injury prevention into the role of out-of-hospital emergency medical services (EMS). DATA SOURCES: Computerized searches of the English-language literature from 1966 through 1994 were conducted using the MEDLINE and National Association of EMS Physicians (NAEMSP) databases. These were supplemented by hand searches of pertinent journals not indexed on MEDLINE or by NAEMSP and the reference lists of retrieved articles. Key words searched included emergency medical services, accident, injury, prevention, and safety. ARTICLE SELECTION: The review included all articles that described the experience of EMS organizations or individuals providing primary injury prevention (PIP) services or that proposed EMS PIP activities. SYNTHESIS: PIP EMS experiences and PIP activities proposed for EMS included: preventing injuries in EMS providers, serving as role models, identifying persons at risk for injury, providing prevention counseling, collecting injury data, surveying residences and institutions for injury risks and hazards, conducting educational programs and media campaigns, and advocating legislative changes that promote injury prevention. Few studies have evaluated the effectiveness of EMS PIP activities. CONCLUSION: As changes in the market compel health care systems to focus more on prevention, EMS organizations and individual providers may be assuming new injury prevention roles. Some EMS systems in many parts of the country have incorporated PIP into their work. It is necessary, however, to determine which PIP roles are effective and how they will be supported.

Law enforcement agencies and out-of-hospital emergency care.

STUDY OBJECTIVE: We sought to assess the involvement of law enforcement agencies in out-of-hospital emergency medical care and their attitudes toward expanded roles in emergency medical services (EMS) systems. METHODS: We mailed a 20-question survey to 800 police chiefs and sheriffs randomly selected from a list of all law enforcement agencies in the United States. The questions focused on the characteristics of each law enforcement agency, its current level of involvement in providing out-of-hospital emergency medical care, and the characteristics of its associated community and local EMS system. The survey concluded with four statements to assess officer attitudes toward an expanded role in EMS-related activities. We used the chi 2 or Fisher exact test to analyze differences in proportions. The alpha-error rate was set at .05. RESULTS: Seventeen surveys were returned as undeliverable. Of the remaining 783 surveys, we received 602 responses (77%). Five hundred forty-nine (70.1%) of the respondents were the primary law enforcement agencies in their communities; they make up the final sample. The median number of officers per agency was 12 (range, 1 to 2,623), and the median population served was 6,936 (range, 150 to 1,500,000). Responses indicated that 442 (80.7%) agencies responded to one or more specific types of medical emergencies and 263 (50.3%) provided some level of patient care. Law enforcement officers frequently arrived at the scene of medical emergencies before EMS personnel (81.5%), with a roll-time interval of less than 8 minutes (87.2%). Only 14 agencies (2.6%) used automatic external defibrillators. Fifty-three percent agreed with the statement that EMS-related activities would interfere with their law enforcement duties. However, more than 60% of respondents agreed that law enforcement agencies should be involved in providing emergency medical services for life-threatening emergencies, that their officers would be willing to undertake extra medical training and that EMS-related activities would improve their public images. CONCLUSION: Many law enforcement agencies are involved to some extent in providing out-of-hospital emergency medical care, and most of the agencies we surveyed would support additional medical training and new or expanded roles for themselves in EMS systems.

Involvement of accessory cells in the Trypanosoma cruzi-induced inhibition of the polyclonal response of T lymphocytes.

Infection with Trypanosoma cruzi is characterized by hyporesponsiveness of the immune system during the acute phase of infection. To better understand the immunological mechanisms affected by T. cruzi, we studied if a reduced T cell proliferative response could originate from an inability of T cells to proliferate or a functional deficiency at the level of accessory cells (AC). The inhibitory effect exerted by T. cruzi was during the induction phase of the lymphoproliferative response, suggesting the participation of AC in the hyporesponse. Then we further investigated the potential of the parasite to interfere with accessory cell-dependent and -independent pathways of human T cell proliferation. Peripheral blood mononuclear cells and peripheral blood lymphocytes from healthy individuals, enriched for T cells, were analysed with regard to their proliferative capacity using: phytohaemagglutinin, immobilized anti-CD3 monoclonal antibody (MoAb) and MoAb to the CD28 antigen, anti-CD3 MoAb and recombinant IL-2 and anti-CD3 MoAb plus phorbol myristate acetate in the presence of parasites. Significant suppression of the proliferative response was caused by the parasite only when AC were present. The parasite markedly reduced the surface expression of HLA-DR and CD11b antigens, key molecules in PHA-induced proliferation. Addition of indomethacin to the culture failed to reverse the inhibitory effect of the parasites, suggesting that prostaglandin E2 was not involved. These data suggest that AC in contact with T. cruzi become incompetent as antigen presenting cell because they are unable to induce a normal proliferative response in T lymphocytes.