Dynamic behaviour of selected PET tracers in embryonated chicken eggs

La tomografía por emisión de positrones/tomografía computarizada (PET/TC) es una técnica establecida en la investigación preclínica de enfermedades en modelos de animales peque˜nos y en el diagnóstico clínico de cáncer. Esta técnica combina la información funcional del biomarcador emisor de positrones con los datos anatómicos de la imagen TC, permitiendo de este modo la investigación in vivo de los procesos biológicos en 4 dimensiones. Recientemente, el crecimiento de los huesos de los embriones de pollo se ha podido monitorizar usando PET/TC con 18F fluoruro como trazador óseo. Estamos interesados en la investigación de otros trazadores PET/TC en embriones de pollo como sistema de modelo in vivo. Para ello, evaluamos varios radiotrazadores usados habitualmente en pruebas clínicas o sintetizamos aquellos que no estaban disponibles comercialmente. Utilizando un microPET/TC de animales peque˜nos, evaluamos las características de 18F, 68Ga y 64Cu cloruro en huevos con sondaje. La 2-Deoxy-2[18F]fluorodeoxiglucosa (18F FDG) estaba absorbida en los sitios de crecimiento de los huesos. El 64Cu cloruro y un anticuerpo de unión a fibrillas de amiloide marcado con 68Ga se acumularon en el hígado, mientras que el 68Ga ligado a un conjugado de desferroxamina disminuyó con el tiempo en ese mismo órgano. Los resultados indican que estos biomarcadores pueden ser utilizados para la monitorización de procesos biológicos en huevos de pollo como modelo animal (AU)

Positron emission tomography/computer tomography (PET/CT) is an established method in preclinical research in small animal disease models and the clinical diagnosis of cancer. It combines functional information of the positron-emitting biomarker with the anatomical data obtained from the CT image. Thus, it allows for 4D in vivo investigation of biological processes. Recently, PET/CT was used to monitor bone growth of chicken embryos using 18F-fluoride as a bone-seeking tracer. We are interested in investigating the adequacy of additional PET/CT tracers in chicken embryos as an in vivo model system. For this reason, we evaluated several positron emitting compounds typically used in clinical tests or if these were not commercially available, we synthesised them. We studied the properties of these 18F- and 68Ga-labelled tracers and of 64Cu-chloride in catheterised eggs via small animal microPET/CT. 2-Deoxy-2-[18F]fluoroglucose ([18F]FDG) was primarily absorbed at the sites of bone growth. 64Cu chloride and a 68Ga-labelled amyloid-fibril-binding antibody accumulated in the liver, while the 68Ga-albumin desferrioxamine conjugate signal in liver decreased over time. These results indicate that these biomarkers can potentially be used for the monitoring of biological processes in chicken eggs as an animal model (AU)

Reduced O2 concentration during CAM development--its effect on physiological parameters of broiler embryos.

Embryo development is a dynamic process, determined by both the genetic background of the organism and the environment in which it develops. Environmental alterations during an organism's embryogenesis may induce changes in the development of some physiological regulatory systems, thereby causing permanent phenotypic changes in the embryo. The present study aimed to assess the effect of 17% O(2) concentration during chorioallantoic membrane (CAM) development on a) CAM development, b) cardiovascular parameters, and c) embryo development postexposure and up to hatch. Two replicated trials, each with 840 fertile Cobb eggs, were conducted. At embryonic d 5 (E5) eggs were divided into 2 treatments: 1) control, and 2) 17% O(2) concentration for 12 h/d from E5 through E12 (12H). The 12H embryos exhibited a clear and significant increase in the vascular area of the CAM, which grew to 6.8% larger than that of the control. Hematocrit and hemoglobin levels, as measured on E13 and E14, increased in response to the hypoxic treatments, but these differences were not maintained subsequently. Heart rate and relative heart weight were not affected by hypoxic exposure, but eggshell temperature in the 12H treatment was higher than that of the control, indicating higher heat production, which is consistent with the elevated plasma concentrations of triiodothyronine and thyroxin and with the enhanced oxygen consumption and residual yolk intake rate that followed exposure to hypoxic conditions. These findings indicate that embryos adapted to hypoxic condition enhance angiogenesis processes, which subsequently increase their blood oxygen-carrying capacity, enabling the increase of oxygen consumption, which positively affects their growth development and maturation compared with the control embryos. Such alterations may affect posthatch performance and the ability of broilers cardiovascular system to meet elevated oxygen demand.

Measurement of strain and strain rate in embryonic chick heart in vivo using spectral domain optical coherence tomography.

The ability to measure in vivo strain and strain rate in embryonic chick heart is one of the key requirements for understanding the mechanisms of cardiac development. Due to its high temporal and spatial resolution as well as its fast imaging capability, optical coherence tomography (OCT) has the potential to reveal the complex myocardial activity in the living chick heart. We describe a method to evaluate the in vivo strain and strain rate of the myocardium through analyzing the periodic variation of the myocardial wall thickness calculated from real time serial OCT images. The results demonstrate that OCT can be a useful tool to describe the biomechanical characteristics of the embryonic heart.

Effects of gamma-hydroxybutyrate (liquid ecstasy) on the eye development of the chick embryo

Gamma-hydroxybutyrate (GHB), a precursorto gamma aminobutyric acid (GABA), wasinitially employed as an anesthetic. As a relativelynovel drug, few people are aware of itsharmful effects and few studies have beenundertaken to investigate its long-term effectsor its action on developing tissues.We performed an experimental study onthe action of GHB on the developing eye, anorgan very closely related to the developmentof the CNS. Chick embryos were treated with20% or 30% dilutions of 100 ìl GHB at 7(30-31 HH) and 11 (37 HH) days of incubation(i.e., two doses per group), and the effectswere observed at 21 days of incubation (45HH). An ophthalmologic ultrasonographydevice (Hondex A/B SCAN IS-500) was usedto measure different eye parameters (cornealthickness; posterior surface of cornea – anteriorsurface of lens; anteroposterior diameter oflens; anteroposterior diameter of eye).We observed significant differencesbetween the treated and control groups asregards the thickness of the cornea and lens,and in the anteroposterior diameter of the eye.The present results demonstrate a possibleeffect of GHB on development (AU)

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The effect of hypoxia at different embryonic ages on impairment of memory ability in chicks.

Hypoxia during the prenatal period is a principal antecedent to cognitive impairment after birth. In this study we have investigated the duration, severity and timing of acute hypoxia during chick embryonic development to elucidate the relative importance of these factors. Our results show that 24h of hypoxia (exposure to 14% oxygen) at embryonic day 10 (E10) results in significant impairment of intermediate and long-term memory in the post-hatch chick, which is the same as we observed with 4 days of hypoxia. At E14, 24h of hypoxia, 5min of anoxia, but not 1h of hypoxia, resulted only in impaired long-term memory; the same as 4 days of hypoxia from E14. Corticosterone levels, measured post-hatch as an indicator of a stress response, were significantly elevated in response to E10 hypoxia, and E14 hypoxia (both 1 and 24h) and anoxia. In a separate experiment we exposed embryos to 24h of hypoxia from E6 to E16, and found that memory deficits resulted from hypoxia at E9 and E10, and E13-E15, while corticosterone concentrations at hatch were significantly raised following E10-E16 hypoxia. These results demonstrate that the developmental age when the insult occurs determines the nature of the cognitive deficit and, if the severity of the insult is sufficient, then the outcome, or deficits in memory ability, are consistent whether the insult is acute or chronic. Importantly, there are two critical stages in development, which in the chick are around E10 and E14, when acute hypoxia results in significant adverse cognitive effects after hatch. These time-points correspond to two different stages in growth and development.

The role of corticosterone in prehatch-induced memory deficits in chicks.

We have previously shown that prehatch hypoxia (14% oxygen for 24 h), at E10 or E14 of chick embryonic development, produces significant memory deficits, with E10 hypoxia significantly affecting short-term memory and the subsequent formation of long-term memory, whereas E14 hypoxia only affects long-term memory. One of the consequences of hypoxia is the release of stress hormones and we found in this study that hypoxia at E10 or E14 induced a significant increase in circulating corticosterone immediately after the cessation of hypoxia (E11 and E15, respectively). Corticosterone levels remained significantly elevated at hatch in the E14 hypoxia group. This study describes the effect of a single, in ovo, injection of corticosterone on subsequent memory ability in hatched chicks. It was found that corticosterone (0.2 nmol/egg) at E10 or E14 mimicked the memory deficits produced by hypoxia at the same prehatch ages. Embryos treated with corticosterone at E10 had poor short-term memory at hatch, whereas corticosterone administration at E14 resulted in poor long-term memory. Embryos treated with corticosterone at E16 had raised circulating corticosterone levels at hatch, but did not have impaired memory. Treatment with corticosterone at E10, E12, E14 and E16 produced the same cognitive outcomes as hypoxia at the same prehatch ages. However, elevated plasma corticosterone levels at hatch did not necessarily cause the impaired memory processing. Raised levels were observed after treatment at E14 when memory processing was impaired, at E16 when memory was not impaired and not at E10 when memory was impaired. This suggests that an acute rather than sustained increase in plasma corticosterone at particular developmental ages is the cause of impaired memory processing seen at hatch.

Avaliação do efeito tóxico do PM10 no desenvolvimento embrionário do Gallus domesticus / Evaluation of the toxic effect of PM10 in the embrionary development of Gallus domesticus

Partículas atmosféricas urbanas têm sido associadas a danos fetais. Neste estudo avaliamos o potencial embriotóxico do PM10, o período de desenvolvimento de maior suscetibilidade e a participação de metais hidrossolúveis na determinação do efeito lesivo da partícula, no modelo experimental do embrião de galinha. Ovos fertilizados de galinha foram inoculados com extratos aquosos de PM10 (3 µg e 0,03µg) em 4 momentos do desenvolvimento embrionário (24, 48, 72 e 96 h de incubação). Os embriões foram também tratados com a solução combinada de PM10 (3µg) e o agente quelante de metal EDTA. Os resultados apontam o 3º e 4º dias de incubação como os períodos do desenvolvimento embrionário mais sensível às partículas tóxicas (p=0,001). A embriotoxicidade do PM10 foi dose-dependente e promoveu danos significativos no desenvolvimento embrionário e menor viabilidade dos embriões (p=0,001). Ambos efeitos foram reduzidos (p=0,006 e p=0,02, respectivamente) pelo uso do quelante de metal (EDTA). Tais observações respaldam o conceito do ar e sugerem que metais podem Ter um papel importante na indução embiotóxica de partículas / Airborn urban particles have been shown to be associated with adverse foetal outcomes. In this study we evaluated the potential embryotoxity of the PM10, the period of development with greater susceptibility and the participation of metals in determinang particle hazardous efecct in a chicken embryo model. Chicken fertilized eggs were inoculated with PM10 aqueous extracts (3µg and 0,03µg) at 4 moments of embryo development (24, 48, 72 na 96 hr of inoculation). Embryos were also treated with the combined solution of PM10 (3µg) plus the metal chelating agent EDTA. The results pointed the 3rd and the 4th days of incubation as the most sensitive embryo developmental period to particles toxicity (p=0,001). The embryotoxicity of PM10 was dose-dependent and promoted significant impairment of embryo development and low embryo viability (p=0,001). Both effects were reduced (p=0,006 and p=0,02) by the use of metal chelation. These observations are supportive of the concept that foetuses may represent a target of air contaminants and suggests that metals play a role in particle-induced embryotoxicity...