In vivo quantitative lipidic map of brown adipose tissue by chemical shift imaging at 4.7 tesla

In the present paper, chemical shift imaging techniques are applied to quantitative in vivo evaluation of fat and water content in interscapular brown adipose tissue (BAT). The experiments have been carried out on five female Sprague-Dawley rats after calibration and testing with suitable phantoms containing known amounts of water and oil. We found that, in the interscapular BAT, the fat is about 50% at the surface (mainly unilocular) region, but its percentage drops to 20–30% in the deepest (mainly multilocular) portion. The perirenal deposits of white adipose tissue (WAT) contained significantly higher amount of fat with large areas ranging from 70 to 90%. Later the rats were killed and the same procedure was repeated with dead animals. Experiments performed in dead rats show a modification of the hydro-lipidic ratio more evident in the multilocular portions of the deposit. The present work demonstrates that MRI-based methods allow a non-invasive, in vivo quantitative mapping of the lipid content which can be applied to investigation of brown adipose tissue deposits in small experiment animals.—Lunati, E., P. Marzola, E. Nicolato, M. Fedrigo, M. Villa, and A. Sbarbati. In vivo quantitative lipidic map of brown adipose tissue by chemical shift imaging at 4.7 tesla. J. Lipid Res. 1999. 40: 1395–1400

Age-related in vivo structural changes in the male mouse olfactory bulb and their correlation with olfactory-driven behavior

Olfactory areas in mammalian brains are linked to centers that modulate behavior. During aging, sensitivity to odors decreases and structural changes are described in olfactory areas. We explored, in two groups of male mice (young and elderly, 6 and 19 months old, respectively), the link between the changes in olfactory bulb structure, detected with magnetic resonance imaging, and behavioral changes in a battery of tests on motor, olfactory, cognitive performance, and emotional reactivity. The behavioral pattern of elderly mice appears less anxious, being less scared by new situations. Additionally, the olfactory bulb of young and elderly mice differed in two variables derived from magnetic resonance imaging (fractional anisotropy and T2 maps). A random forest approach allowed to select the variables most predictive of the differences between young and elderly mice, and correlations were found between three behavioral variables indicative of anxious behavior and the two magnetic resonance variables mentioned above. These data suggest that in the living mouse, it is possible to describe co-occurring age-related behavioral and structural changes in the olfactory bulb. These data serve as a basis for studies on normal and pathological aging in the mouse, but also open new opportunities for in vivo human aging studies

Magnetic resonance imaging investigations in a murine model of Down syndrome: the Ts65Dn mouse

Trisomy 21, or Down’s syndrome, is the most common genetic cause of intellectual disability; moreover, DS patients suffer from muscle hypotonia and low muscle strength whose mechanisms are still unknown and only partially explained by intellectual disability. Genetic mouse models (e.g., the Ts65Dn mouse) may offer insights into the responsible mechanisms . Moreover, the Ts65Dn mouse show muscle weakness and share morphological similarities with sarcopenia of aging [1]. To characterize skeletal muscle in theTs65Dn model, we explored the hindlimb of young adult (6-month-old) mice in euploid (n=9, mean weight: 43.8±4.10 g) and trisomic (n=9, mean weight: 38.2±4.0 g ) individuals by magnetic resonance imaging. Mice were imaged in a Bruker Tomograph at 4.7 Tesla using a RARE T2-weighed sequence (TR: 5000ms, TE: 56ms; spatial resolution 0.0182cm2 per pixel). Muscle cross sectional area was measured in a section taken at mid-femur in either hindlimbs and values averaged for further analysis. Results showed that mean hindlimbs muscle cross sectional area was larger in trisomic than in euploid mice (0.29±0.05 vs. 0.23±0.05 cm2, p=0.03 [t test]). Because of significant difference in body weight between euploid and trisomic mice (p=0.009), data were adjusted per body weight. Using adjusted data, a significant difference was still found between groups (euploid: 0.005±0.001; trisomic: 0.007±0.001 cm2/g body weight). It is concluded that young adult trisomic mice has increased apparent muscle mass in hindlimbs. Since trisomic Ts65Dn mice show reduced grip strength as well as running and swimming speed in the presence of roughly normal muscle biochemistry [2], possible structural and fibertype changes in hindlimb muscles of these mice are under investigation to explain such a discrepancy

Blood volume is improved by forced mild physical training in the motor and hippocampal cortex of old mice

The effect of mild forced physical training [1] (treadmill running 30 min a day, five days a week for 30 days at belt speed = 8 m/min, 0% incline) on the motor and hippocampal brain cortex was investigated in old (>24mo) mice by means of magnetic resonance imaging. The possible additive effect of physical training and testosterone [2] administration was also examined. Cortical thickness, quantitative transverse relaxation time (T2) maps, and regional cerebral blood volume (rCBV) were evaluated at baseline and after training. Results show that physical training alone induced significant increase of rCBV in both motor and hippocampal cortex. Cortex thickness and T2 maps were similar before and after training. Similar results were obtained in testosterone treated mice suggesting that testosterone does not add to physical training effect. This work provides first quantitative evidence that exercise initiated at old age is able to improve the hemodynamic status of the brain cortex in key regions for movement and cognition without inducing edema

Pancreatic cancer growth using magnetic resonance and bioluminescence imaging

OBJECT:Pancreatic cancer is one of the most lethal human cancer and appropriate experimental tumor models are needed for the development of innovative therapeutic approaches. This paper describes an experimental model of human pancreatic cancer and a related non invasive imaging technique suitable for monitoring tumor growth and metastatization. The aim of the work was the implementation of an experimental platform suitable for assessing the efficacy of new therapeutic agents.MATERIALS AND METHODS:Human pancreatic cancer cells (PANC-1-Luc+) were injected into the pancreas of female athymic CD1 mice. Magnetic Resonance Imaging (MRI) at 4.7T and Bioluminescence Imaging (BLI) were performed in each mouse at three time points after cell inoculation (1, 2 and 3months). Two groups of mice were studied: the first group of n=13 mice in which 5*106 cells were injected and the second group of n=10 mice in which 2*106 cells were injected. MRI examination included T2w acquisitions and (at the last time point) Dynamic-contrast-enhanced-MRI (DCE-MRI).RESULTS:Each mouse underwent three longitudinal MRI and BLI examinations. BLI was more sensitive than MRI producing higher detection rate at early time points. Moreover in one case of abdominal dissemination of pancreatic tumor cells, small tumoral masses were detected by BLI and not detected by MRI. However BLI appears more prone to experimental error most likely due to photon attenuation. In 4 mice BLI produced false negative results. DCE-MRI experiments providing information on tumor perfusion were conducted successfully in this anatomical district and demonstrated that the tumor tissues from the second experimental group are more vascularized compared to the first group.CONCLUSION:The present study performed on the experimental model of pancreatic cancer here described shows that MRI and BLI are complementary techniques and that synergistic application of both can overcome the intrinsic limitations of each.Object Pancreatic cancer is one of the most lethal human cancer and appropriate experimental tumor models are needed for the development of innovative therapeutic approaches. This paper describes an experimental model of human pancreatic cancer and a related non invasive imaging technique suitable for monitoring tumor growth and metastatization. The aim of the work was the implementation of an experimental platform suitable for assessing the efficacy of new therapeutic agents.Materials and methods: Human pancreatic cancer cells (PANC-1-Luc +) were injected into the pancreas of female athymic CD1 mice. Magnetic Resonance Imaging (MRI) at 4.7 T and Bioluminescence Imaging (BLI) were performed in each mouse at three time points after cell inoculation (1, 2 and 3 months). Two groups of mice were studied: the first group of n = 13 mice in which 5 * 10(6) cells were injected and the second group of n = 10 mice in which 2 * 10(6) cells were injected. MRI examination included T2w acquisitions and (at the last time point) Dynamic-contrast-enhanced-MRI (DCE-MRI).Results: Each mouse underwent three longitudinal MRI and BLI examinations. BLI was more sensitive than MRI producing higher detection rate at early time points. Moreover in one case of abdominal dissemination of pancreatic tumor cells, small tumoral masses were detected by BLI and not detected by MRI. However BLI appears more prone to experimental error most likely due to photon attenuation. In 4 mice BLI produced false negative results. DCE-MRI experiments providing information on tumor perfusion were conducted successfully in this anatomical district and demonstrated that the tumor tissues from the second experimental group are more vascularized compared to the first group.Conclusion: The present study performed on the experimental model of pancreatic cancer here described shows that MRI and BLI are complementary techniques and that synergistic application of both can overcome the intrinsic limitations of each. (C) 2015 Elsevier Inc. All rights reserved

Polymer-coated superparamagnetic iron oxide nanoparticles as T2 contrast agent for MRI and their uptake in liver

Aim: To study the efficiency of multifunctional polymer-based superparamagnetic iron oxide nanoparticles (bioferrofluids) as a T2 magnetic resonance contrast agent and their uptake and toxicity in liver. Materials & methods: Mice were intravenously injected with bioferrofluids and Endorem\uae. The magnetic resonance efficiency, uptake and in vivo toxicity were investigated by means of magnetic resonance imaging (MRI) and histological techniques. Results: Bioferrofluids are a good T2 contrast agent with a higher r2/r1 ratio than Endorem. Bioferrofluids have a shorter blood circulation time and persist in liver for longer time period compared with Endorem. Both bioferrofluids and Endorem do not generate any noticeable histological lesions in liver over a period of 60 days post-injection. Conclusion: Our bioferrofluids are powerful diagnostic tool without any observed toxicity over a period of 60 days post-injection

Does Pilocarpine-Induced Epilepsy in Adult Rats Require Status epilepticus?

Pilocarpine-induced seizures in rats provide a widely animal model of temporal lobe epilepsy. Some evidences reported in the literature suggest that at least 1 h of status epilepticus (SE) is required to produce subsequent chronic phase, due to the SE-related acute neuronal damage. However, recent data seems to indicate that neuro-inflammation plays a crucial role in epileptogenesis, modulating secondarily a neuronal insult. For this reason, we decided to test the following hypotheses: a) whether pilocarpine-injected rats that did not develop SE can exhibit long-term chronic spontaneous recurrent seizures (SRS) and b) whether acute neurodegeneration is mandatory to obtain chronic epilepsy. Therefore, we compared animals injected with the same dose of pilocarpine that developed or did not SE, and saline treated rats. We used telemetric acquisition of EEG as long-term monitoring system to evaluate the occurrence of seizures in non-SE pilocarpineinjected animals. Furthermore, histology and MRI analysis were applied in order to detect neuronal injury and neuropathological signs. Our observations indicate that non-SE rats exhibit SRS almost 8 (+/22) months after pilocarpine-injection, independently to the absence of initial acute neuronal injury. This is the first time reported that pilocarpine injected rats without developing SE, can experience SRS after a long latency period resembling human pathology. Thus, we strongly emphasize the important meaning of including these animals to model human epileptogenesis in pilocarpine induced epilepsy

Pilocarpine-Induced Status Epilepticus in Rats Involves Ischemic and Excitotoxic Mechanisms

The neuron loss characteristic of hippocampal sclerosis in temporal lobe epilepsy patients is thought to be the result of excitotoxic, rather than ischemic, injury. In this study, we assessed changes in vascular structure, gene expression, and the time course of neuronal degeneration in the cerebral cortex during the acute period after onset of pilocarpine-induced status epilepticus (SE). Immediately after 2 hr SE, the subgranular layers of somatosensory cortex exhibited a reduced vascular perfusion indicative of ischemia, whereas the immediately adjacent supragranular layers exhibited increased perfusion. Subgranular layers exhibited necrotic pathology, whereas the supergranular layers were characterized by a delayed (24 h after SE) degeneration apparently via programmed cell death. These results indicate that both excitotoxic and ischemic injuries occur during pilocarpine-induced SE. Both of these degenerative pathways, as well as the widespread and severe brain damage observed, should be considered when animal model-based data are compared to human pathology

A role for leukocyte-endothelial adhesion mechanisms in epilepsy

The mechanisms involved in the pathogenesis of epilepsy, a chronic neurological disorder that affects approximately 1 percent of the world population, are not well understood1–3. Using a mouse model of epilepsy, we show that seizures induce elevated expression of vascular cell adhesion molecules and enhanced leukocyte rolling and arrest in brain vessels mediated by the leukocyte mucin P-selectin glycoprotein ligand-1 (PSGL-1) and leukocyte integrins α4β1 and αLβ2. Inhibition of leukocyte-vascular interactions either with blocking antibodies, or in mice genetically deficient in functional PSGL-1, dramatically reduced seizures. Treatment with blocking antibodies following acute seizures prevented the development of epilepsy. Neutrophil depletion also inhibited acute seizure induction and chronic spontaneous recurrent seizures. Blood-brain barrier (BBB) leakage, which is known to enhance neuronal excitability, was induced by acute seizure activity but was prevented by blockade of leukocyte-vascular adhesion, suggesting a pathogenetic link between leukocyte-vascular interactions, BBB damage and seizure generation. Consistent with potential leukocyte involvement in the human, leukocytes were more abundant in brains of epileptics than of controls. Our results suggest leukocyte-endothelial interaction as a potential target for the prevention and treatment of epilepsy

High-field-magnetic resonance imaging of the developing human brain from the 10th to the 16th week of gestational age

In the present work, high-field magnetic resonance imaging (HF-MRI) was applied to study the developing human brain paying particular attention to the structures of interest in pathology of malformation. The aim of the work was to evaluate the possible application of HF-MRI to the analysis of brain development in the absence of some limits of conventional histological technique. Seven formalin-fixed human fetuses of 50, 65, 70, 85, 110, 116 and 125 mm crown/ rump length (corresponding to a gestational age ranging from 10 to 16 weeks) were examined in an imager-spectrometer equipped with a 4,7-tesla horizontal magnet with a 33-cm bore, In the brain of all the fetuses the telencephalic, mesencephalic and rhombencephalic vesicles were recognizable and an easy quantitative evaluation of the brain curvatures in the absence of distortion due to dissection was possible. Comparing fetuses at different gestational ages, the spatial modification of the different vesicles was evident. In fetuses at 16 weeks of gestational age, stratified compartments of the telencephalic wall were evident. The germinal zone and the cortical plate were visible: the germinal layer was identifiable as a hypointensity in the periventricular area. The subplate zone and the intermediate zone emitted a strong intensity signal, Our study demonstrates that HF-MRI can contribute to the study of the complex developmental events in the human brain from the 10th to 16th week of gestational age in a submillimetric scale of resolution. This technique can provide information about the morphology of the encephalic vesicles and their relations with the bone cavity that cannot be obtained with conventional methods and may be a useful adjunct to histological techniques