A neuron-specific deletion of the microRNA-processing enzyme DICER induces severe but transient obesity in mice.

MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate gene expression post-transcriptionally. MiRNAs are implicated in various biological processes associated with obesity, including adipocyte differentiation and lipid metabolism. We used a neuronal-specific inhibition of miRNA maturation in adult mice to study the consequences of miRNA loss on obesity development. Camk2a-CreERT2 (Cre+) and floxed Dicer (Dicerlox/lox) mice were crossed to generate tamoxifen-inducible conditional Dicer knockouts (cKO). Vehicle- and/or tamoxifen-injected Cre+;Dicerlox/lox and Cre+;Dicer+/+ served as controls. Four cohorts were used to a) measure body composition, b) follow food intake and body weight dynamics, c) evaluate basal metabolism and effects of food deprivation, and d) assess the brain transcriptome consequences of miRNA loss. cKO mice developed severe obesity and gained 18 g extra weight over the 5 weeks following tamoxifen injection, mainly due to increased fat mass. This phenotype was highly reproducible and observed in all 38 cKO mice recorded and in none of the controls, excluding possible effects of tamoxifen or the non-induced transgene. Development of obesity was concomitant with hyperphagia, increased food efficiency, and decreased activity. Surprisingly, after reaching maximum body weight, obese cKO mice spontaneously started losing weight as rapidly as it was gained. Weight loss was accompanied by lowered O2-consumption and respiratory-exchange ratio. Brain transcriptome analyses in obese mice identified several obesity-related pathways (e.g. leptin, somatostatin, and nemo-like kinase signaling), as well as genes involved in feeding and appetite (e.g. Pmch, Neurotensin) and in metabolism (e.g. Bmp4, Bmp7, Ptger1, Cox7a1). A gene cluster with anti-correlated expression in the cerebral cortex of post-obese compared to obese mice was enriched for synaptic plasticity pathways. While other studies have identified a role for miRNAs in obesity, we here present a unique model that allows for the study of processes involved in reversing obesity. Moreover, our study identified the cortex as a brain area important for body weight homeostasis.

Transient global amnesia associated with an acute infarction at the cingulate gyrus.

Background. Transient global amnesia (TGA) is a syndrome of sudden, unexplained isolated short-term memory loss. In the majority of TGA cases, no causes can be identified and neuroimaging, CSF studies and EEG are usually normal. We present a patient with TGA associated with a small acute infarct at the cingulate gyrus. Case Report. The patient, a 62 year-old man, developed two episodes of TGA. He had hypertension and hypercholesterolemia. He was found to have an acute ischemic stroke of small size (15 mm of maximal diameter) at the right cerebral cingulate gyrus diagnosed on brain magnetic resonance imaging. No lesions involving other limbic system structures such as thalamus, fornix, corpus callosum, or hippocampal structures were seen. The remainder of the examination was normal. Conclusion. Unilateral ischemic lesions of limbic system structures may result in TGA. We must bear in mind that TGA can be an associated clinical disorder of cingulate gyrus infarct.

Transient prenatal expression of NPY-Y1 receptor in trigeminal axons innervating the mystacial vibrissae.

Using immunohistochemistry in combination with confocal laser scanning microscopy, we studied the ontogeny of neuropeptide Y-Y1 receptor (Y1-R) expression in the trigeminal system of the rat. The study was limited to the nerve fibers innervating the mystacial pad and the trigeminal ganglia. In the trigeminal ganglia, Y1-R-immunoreactive (IR) neurons were first observed at E16.5. At this same stage some nerve fibers in the trigeminal ganglia also exhibited Y1-R-like immunoreactivity (LI). Strongly Y1-R-IR nerve fibers innervating the follicles of the mystacial vibrissae were first observed at E18. After double labeling, the Y1-R-LI was found to be colocalized with the neuronal marker protein gene product 9.5. At P1 only weak labeling for the Y1-R was found around the vibrissae follicles, whereas the neurons in the trigeminal ganglia were intensely labeled. The same was true for the adult rat, but at this stage no Y1-R labeling at all was observed in nerve fibers around the vibrissal follicles. These results strongly support an axonal localization of the Y1-R at this developmental stage. The transient expression of the Y1-R during prenatal mystacial pad development suggests a role for the Y1-R in the functional development of the vibrissae.

Preservation of an extreme transient geotherm in the Raft River detachment shear zone

Extensional detachment systems separate hot footwalls from cool hanging walls, but the degree to which this thermal gradient is the product of ductile or brittle deformation or a preserved original transient geotherm is unclear. Oxygen isotope thermometry using recrystallized quartz-muscovite pairs indicates a smooth thermal gradient (140 degrees C/100 m) across the gently dipping, quartzite-dominated detachment zone that bounds the Raft River core complex in northwest Utah (United States). Hydrogen isotope values of muscovite (delta D-Ms similar to-100 parts per thousand) and fluid inclusions in quartz (delta D-Fluid similar to-85 parts per thousand) indicate the presence of meteoric fluids during detachment dynamics. Recrystallized grain-shape fabrics and quartz c-axis fabric patterns reveal a large component of coaxial strain (pure shear), consistent with thinning of the detachment section. Therefore, the high thermal gradient preserved in the Raft River detachment reflects the transient geotherm that developed owing to shearing, thinning, and the potentially prominent role of convective flow of surface fluids.

Selective neurodegeneration induced in rotation-mediated aggregate cell cultures by a transient switch to stationary culture conditions: a potential model to study ischemia-related pathogenic mechanisms.

Aggregating brain cell cultures at an advanced maturational stage (20-21 days in vitro) were subjected for 1-3 h to anaerobic (hypoxic) and/or stationary (ischemic) conditions. After restoration of the normal culture conditions, cell loss was estimated by measuring the release of lactate dehydrogenase as well as the irreversible decrease of cell type-specific enzyme activities, total protein and DNA content. Ischemia for 2 h induced significant neuronal cell death. Hypoxia combined with ischemia affected both neuronal and glial cells to different degrees (GABAergic neurons>cholinergic neurons>astrocytes). Hypoxic and ischemic conditions greatly stimulated the uptake of 2-deoxy-D-glucose, indicating increased glucose consumption. Furthermore, glucose restriction (5.5 mM instead of 25 mM) dramatically increased the susceptibility of neuronal and glial cells to hypoxic and ischemic conditions. Glucose media concentrations below 2 mM caused selective neuronal cell death in otherwise normal culture conditions. GABAergic neurons showed a particularly high sensitivity to glucose restriction, hypoxia, and ischemia. The pattern of ischemia-induced changes in vitro showed many similarities to in vivo findings, suggesting that aggregating brain cell cultures provide a useful in vitro model to study pathogenic mechanisms related to brain ischemia.

Generation of mouse-induced pluripotent stem cells by transient expression of a single nonviral polycistronic vector

Induced pluripotent stem (iPS) cells have generated keen interestdue to their potential use in regenerative medicine. They havebeen obtained from various cell types of both mice and humans byexogenous delivery of different combinations of Oct4, Sox2, Klf4,c-Myc, Nanog, and Lin28. The delivery of these transcription factorshas mostly entailed the use of integrating viral vectors (retrovirusesor lentiviruses), carrying the risk of both insertional mutagenesisand oncogenesis due to misexpression of these exogenousfactors. Therefore, obtaining iPS cells that do not carry integratedtransgene sequences is an important prerequisite for their eventualtherapeutic use. Here we report the generation of iPS cell linesfrom mouse embryonic fibroblasts with no evidence of integrationof the reprogramming vector in their genome, achieved by nucleofectionof a polycistronic construct coexpressing Oct4, Sox2, Klf4,and c-Myc

Activation of Transient Receptor Potential Canonical 3 (TRPC3)-mediated Ca2+ Entry by A1 Adenosine Receptor in Cardiomyocytes Disturbs Atrioventricular Conduction.

Although the activation of the A(1)-subtype of the adenosine receptors (A(1)AR) is arrhythmogenic in the developing heart, little is known about the underlying downstream mechanisms. The aim of this study was to determine to what extent the transient receptor potential canonical (TRPC) channel 3, functioning as receptor-operated channel (ROC), contributes to the A(1)AR-induced conduction disturbances. Using embryonic atrial and ventricular myocytes obtained from 4-day-old chick embryos, we found that the specific activation of A(1)AR by CCPA induced sarcolemmal Ca(2+) entry. However, A(1)AR stimulation did not induce Ca(2+) release from the sarcoplasmic reticulum. Specific blockade of TRPC3 activity by Pyr3, by a dominant negative of TRPC3 construct, or inhibition of phospholipase Cs and PKCs strongly inhibited the A(1)AR-enhanced Ca(2+) entry. Ca(2+) entry through TRPC3 was activated by the 1,2-diacylglycerol (DAG) analog OAG via PKC-independent and -dependent mechanisms in atrial and ventricular myocytes, respectively. In parallel, inhibition of the atypical PKCζ by myristoylated PKCζ pseudosubstrate inhibitor significantly decreased the A(1)AR-enhanced Ca(2+) entry in both types of myocytes. Additionally, electrocardiography showed that inhibition of TRPC3 channel suppressed transient A(1)AR-induced conduction disturbances in the embryonic heart. Our data showing that A(1)AR activation subtly mediates a proarrhythmic Ca(2+) entry through TRPC3-encoded ROC by stimulating the phospholipase C/DAG/PKC cascade provide evidence for a novel pathway whereby Ca(2+) entry and cardiac function are altered. Thus, the A(1)AR-TRPC3 axis may represent a potential therapeutic target.

Glibenclamide enhances neurogenesis and improves long-term functional recovery after transient focal cerebral ischemia

Glibenclamide is neuroprotective against cerebral ischemia in rats. We studied whether glibenclamide enhances long-term brain repair and improves behavioral recovery after stroke. Adult male Wistar rats were subjected to transient middle cerebral artery occlusion (MCAO) for 90 minutes. A low dose of glibenclamide (total 0.6mg) was administered intravenously 6, 12, and 24 hours after reperfusion. We assessed behavioral outcome during a 30-day follow-up and animals were perfused for histological evaluation. In vitro specific binding of glibenclamide to microglia increased after pro-inflammatory stimuli. In vivo glibenclamide was associated with increased migration of doublecortin-positive cells in the striatum toward the ischemic lesion 72 hours after MCAO, and reactive microglia expressed sulfonylurea receptor 1 (SUR1) and Kir6.2 in the medial striatum. One month after MCAO, glibenclamide was also associated with increased number of NeuN-positive and 5-bromo-2-deoxyuridine-positive neurons in the cortex and hippocampus, and enhanced angiogenesis in the hippocampus. Consequently, glibenclamide-treated MCAO rats showed improved performance in the limb-placing test on postoperative days 22 to 29, and in the cylinder and water-maze test on postoperative day 29. Therefore, acute blockade of SUR1 by glibenclamide enhanced long-term brain repair in MCAO rats, which was associated with improved behavioral outcome.

Improved multiexponential transient spectroscopy by iterative deconvolution

The analysis of multiexponential decays is challenging because of their complex nature. When analyzing these signals, not only the parameters, but also the orders of the models, have to be estimated. We present an improved spectroscopic technique specially suited for this purpose. The proposed algorithm combines an iterative linear filter with an iterative deconvolution method. A thorough analysis of the noise effect is presented. The performance is tested with synthetic and experimental data.

Measurements of seismic attenuation and transient fluid pressure in partially saturated Berea sandstone: Evidence of fluid flow on the mesoscopic scale

A novel laboratory technique is proposed to investigate wave-induced fluid flow on the mesoscopic scale as a mechanism for seismic attenuation in partially saturated rocks. This technique combines measurements of seismic attenuation in the frequency range from 1 to 100?Hz with measurements of transient fluid pressure as a response of a step stress applied on top of the sample. We used a Berea sandstone sample partially saturated with water. The laboratory results suggest that wave-induced fluid flow on the mesoscopic scale is dominant in partially saturated samples. A 3-D numerical model representing the sample was used to verify the experimental results. Biot's equations of consolidation were solved with the finite-element method. Wave-induced fluid flow on the mesoscopic scale was the only attenuation mechanism accounted for in the numerical solution. The numerically calculated transient fluid pressure reproduced the laboratory data. Moreover, the numerically calculated attenuation, superposed to the frequency-independent matrix anelasticity, reproduced the attenuation measured in the laboratory in the partially saturated sample. This experimental?numerical fit demonstrates that wave-induced fluid flow on the mesoscopic scale and matrix anelasticity are the dominant mechanisms for seismic attenuation in partially saturated Berea sandstone.

Local transient myocardial liposomal gene transfer of inducible nitric oxide synthase does not aggravate myocardial function and fibrosis and leads to moderate neovascularization in chronic myocardial ischemia in pigs.

Microcirculation (2010) 17, 69-78. doi: 10.1111/j.1549-8719.2010.00002.x Abstract Background: This study was designed to explore the effect of transient inducible nitric oxide synthase (iNOS) overexpression via cationic liposome-mediated gene transfer on cardiac function, fibrosis, and microvascular perfusion in a porcine model of chronic ischemia. Methods and Results: Chronic myocardial ischemia was induced using a minimally invasive model in 23 landrace pigs. Upon demonstration of heart failure, 10 animals were treated with liposome-mediated iNOS-gene-transfer by local intramyocardial injection and 13 animals received a sham procedure to serve as control. The efficacy of this iNOS-gene-transfer was demonstrated for up to 7 days by reverse transcriptase-polymerase chain reaction in preliminary studies. Four weeks after iNOS transfer, magnetic resonance imaging showed no effect of iNOS overexpression on cardiac contractility at rest and during dobutamine stress (resting ejection fraction: control 27%, iNOS 26%; P = ns). Late enhancement, infarct size, and the amount of fibrosis were similar between groups. Although perfusion and perfusion reserve in response to adenosine and dobutamine were not significantly modified by iNOS-transfer, both vessel number and diameter were significantly increased in the ischemic area in the iNOS-treated group versus control (point score: control 15.3, iNOS 34.7; P < 0.05). Conclusions: Our findings demonstrate that transient iNOS overexpression does not aggravate cardiac dysfunction or postischemic fibrosis, while potentially contributing to neovascularization in the chronically ischemic heart.

Transient Ischemic Dilation (TID) ratio measurement during Rb-82 cardiac PET: Comparison between three different software packages.

Background: TIDratio indirectly reflects myocardial ischemia and is correlated with cardiacprognosis. We aimed at comparing the influence of three different softwarepackages for the assessment of TID using Rb-82 cardiac PET/CT. Methods: Intotal, data of 30 patients were used based on normal myocardial perfusion(SSS<3 and SRS<3) and stress myocardial blood flow 2mL/min/g)assessed by Rb-82 cardiac PET/CT. After reconstruction using 2D OSEM (2Iterations, 28 subsets), 3-D filtering (Butterworth, order=10, ωc=0.5), data were automatically processed, and then manually processed fordefining identical basal and apical limits on both stress and rest images.TIDratio were determined with Myometrix®, ECToolbox® and QGS®software packages. Comparisons used ANOVA, Student t-tests and Lin concordancetest (ρc). Results: All of the 90 processings were successfullyperformed. TID ratio were not statistically different between software packageswhen data were processed automatically (P=0.2) or manually (P=0.17). There was a slight, butsignificant relative overestimation of TID with automatic processing incomparison to manual processing using ECToolbox® (1.07 ± 0.13 vs 1.0± 0.13, P=0.001)and Myometrix® (1.07 ± 0.15 vs 1.01 ± 0.11, P=0.003) but not using QGS®(1.02 ±0.12 vs 1.05 ± 0.11, P=0.16). The best concordance was achieved between ECToolbox®and Myometrix® manual (ρc=0.67) processing.Conclusion: Using automatic or manual mode TID estimation was not significantlyinfluenced by software type. Using Myometrix® or ECToolbox®TID was significantly different between automatic and manual processing, butnot using QGS®. Software package should be account for when definingTID normal reference limits, as well as when used in multicenter studies. QGS®software seemed to be the most operator-independent software package, whileECToolbox® and Myometrix® produced the closest results.