PET and MRI studies applied on characterization of Fisher/F98 rat glioma model

Introduction: Preclinical brain tumor models have provided a wealth of information on the biology, imaging and experimental therapeuticsof brain tumors. The aim of our study is characterized Fisher/F98 rat glioma model using Positron Emission Tomography (PET) and Magnetic Resonance (MR) analysis to set up an experimental model useful to study the efficacy of new colloidal vectors for chemotherapy. Methods: Syngenic rat brain-glioma models (Fisher/F98) was obtained by stereotactic (x=2; y=5; z=3) implantation of different cell concentrations (102, 103, 104 and 105). To monitor tumor growth progression, rats underwent once a week Gadolinium enhanced T1-MRI studies followed by [18F]FDG PET studies, starting from 7 days after surgery. A group of animals performed also [18F]FAZA PET studies to evaluate regional tissue hypoxia. To improve quantification, PET and MRI images were fused using PMOD 2.7 software. Max radiotracers uptake was calculated for tumor,frontal cortex, cerebellum and background using region of interest (ROI) analysis. Radioactivity concentration values expressed in MBq/g were then transformed into percentage of injected dose per gram of tissue (%ID/g). Moreover, histological analysis of proliferation, apoptosis, differentiation, neoangiogenesis and hypoxia markers were performed. Results: Mean survival time of rats injected with 104 and 105 cells was nine days. One week after surgery, MRI revealed a rapid growth that reached 0.11 cm3 mean tumour volume. Animals injected with 103 and 102 cells showed a mean survival time of 18 and 24 days respectively. In rats injected with 103 cells, tumor was revealed 14 days after surgery at MRI and [18F]FDG PET and successively tumors rapidly increased. Disease course in 102 cells injected rats was slower. Tumors were characterized by high [18F]FDG uptake and hypoxic subareas which only partially overlapped. Hypoxic areas were mainly localized in correspondence to Gd-enhanced regions whereas hyper glucose metabolic areas were localized in the outer part of the tumors. At histological analysis tumoral masses showed an infiltrative pattern of growth and moderate neoangiogenesis. Tumors obtained at animals death showed diffused necrotic areas. HIF1 was clearly expressed by glial and neuronal cells in oedematous and hypoxic areas. Conclusions: Our study indicates that Fisher/ F98 rat glioma model reproduces the characteristic of aggressiveness of human glioblastoma. Tumor was characterized by high glucose metabolism and by hypoxic sub-areas. The concentration of 102 cells permits to better monitor disease onset and progression and to plan experiments to test new anti-neoplastic therapies efficacy

Biologia reprodutiva do peixe-rei Odontesthes argentinensis (Valenciennes) (Atherinopsidae) da região marinha costeira do sul do Brasil Reproductive biology of silverside Odontesthes argentinensis (Valenciennes) (Atherinopsidae) of coastal sea region of the south of Brazil

O peixe-rei Odontesthes argentinensis (Valenciennes, 1835) distribui-se na região costeira do Atlântico Sul desde o sul do Brasil até a Argentina. Esta espécie apresenta duas populações, uma população residente no estuário da Lagoa dos Patos e outra na região marinha costeira. Este trabalho teve como objetivo determinar a biologia reprodutiva da população marinha costeira. A proporção sexual indicou predomínio de fêmeas. O tamanho de primeira maturação (L50) foi estimado em 13,8 cm CT para os machos e 16,1 cm CT para as fêmeas e o comprimento em que todos estão aptos para desovar (L100), foi estimado em 16,3 e 19,3 cm CT para machos e fêmeas, respectivamente. A relação gonadossomática indicou período reprodutivo entre final de agosto e início dezembro, período em que a temperatura da água se manteve abaixo dos 20ºC. Os fatores de condição total (KT) e somático (KS) apresentaram grandes variações ao longo do ciclo. Houve uma queda nos valores de K coincidindo com o início da desova estabelecendo uma relação com este período. Na análise do diâmetro dos ovócitos há evidências de três lotes caracterizando desova parcelada. A fecundidade total (FT) e por lote (FL) são proporcionais ao comprimento total. A média de ovócitos foi de 10.014 para FT e 3.651 para FL.<br>The silverside Odontesthes argentinensis (Valenciennes, 1835) is distributed in the coastal region of the South Atlantic since the south of Brazil until Argentina. This species presents two populations, a population resident in the Patos Lagoon estuary and another one in the coastal sea region. This work had as objective to determine the reproductive biology of the populations of coastal sea region. The sex ratio indicated predominance of females. The size of first maturation (L50) was estimated in 13.8 cm LT for the males and 16.1 cm LT for the females and the length where all were apt to spawn (L100) was estimated in 16.3 and 19.3cm LT for males and females, respectively. The gonadossomatic relation indicated reproductive period between ends of August and beginning of December, period where the temperature of the water is below 20ºC. The factors of total condition (KT) and somatic (KS) had presented great variations during the cycle. A fall in the values of K coincided with the beginning of the spawning, establishing a relation this fall of K represented the energy that was directed for the development of the gonads. In the analysis of the diameter of the oocytes evidence was found allowing state that the spawning don't occur at once. The total fecundity (TF) and the lot fecundity (LF) are proportional to the total length. The average of oocytes was of 10,014 for FT and 3,651 for FL

Euclid: Early Release Observations -- A glance at free-floating new-born planets in the sigma Orionis cluster

International audienceWe provide an early assessment of the imaging capabilities of the Euclid space mission to probe deeply into nearby star-forming regions and associated very young open clusters, and in particular to check to what extent it can shed light on the new-born free-floating planet population. This paper focuses on a low-reddening region observed in just one Euclid pointing where the dust and gas has been cleared out by the hot sigma Orionis star. One late-M and six known spectroscopically confirmed L-type substellar members in the sigma Orionis cluster are used as benchmarks to provide a high-purity procedure to select new candidate members with Euclid. The exquisite angular resolution and depth delivered by the Euclid instruments allow us to focus on bona-fide point sources. A cleaned sample of sigma Orionis cluster substellar members has been produced and the initial mass function (IMF) has been estimated by combining Euclid and Gaia data. Our sigma Orionis substellar IMF is consistent with a power-law distribution with no significant steepening at the planetary-mass end. No evidence of a low-mass cutoff is found down to about 4 Jupiter masses at the young age (3 Myr) of the sigma Orionis open cluster