Determination of [11C]PBR28 binding potential in vivo: a first human TSPO blocking study

Positron emission tomography (PET) targeting the 18 kDa translocator protein (TSPO) is used to quantify neuroinflammation. Translocator protein is expressed throughout the brain, and therefore a classical reference region approach cannot be used to estimate binding potential (BP_ND). Here, we used blockade of the TSPO radioligand [¹¹C]PBR28 with the TSPO ligand XBD173, to determine the non-displaceable volume of distribution (V_ND), and hence estimate the BP_ND. A total of 26 healthy volunteers, 16 high-affinity binders (HABs) and 10 mixed affinity binders (MABs) underwent a [¹¹C]PBR28 PET scan with arterial sampling. Six of the HABs received oral XBD173 (10 to 90 mg), 2 hours before a repeat scan. In XBD173-dosed subjects, V_ND was estimated via the occupancy plot. Values of BP_ND for all subjects were calculated using this V_ND estimate. Total volume of distribution (V_T) of MABs (2.94±0.31) was lower than V_T of HABs (4.33±0.29) (P<0.005). There was dose-dependent occupancy of TSPO by XBD173 (ED50=0.34±0.13 mg/kg). The occupancy plot provided a V_ND estimate of 1.98 (1.69, 2.26). Based on these V_ND estimates, BP_ND for HABs is approximately twice that of MABs, consistent with predictions from in vitro data. Our estimates of [¹¹C]PBR28 V_ND and hence BP_ND in the healthy human brain are consistent with in vitro predictions. XBD173 blockade provides a practical means of estimating V_ND for TSPO targeting radioligands.     

AMPA receptor potentiation can prevent ethanol-induced intoxication.

We present a substantial series of behavioral and imaging experiments, which demonstrate, for the first time, that increasing AMPA receptor-mediated neurotransmission via administration of potent and selective biarylsulfonamide AMPA potentiators LY404187 and LY451395 reverses the central effects of an acutely intoxicating dose of ethanol in the rat. Using pharmacological magnetic resonance imaging (phMRI), we observed that LY404187 attenuated ethanol-induced reductions in blood oxygenation level dependent (BOLD) in the anesthetized rat brain. A similar attenuation was apparent when measuring local cerebral glucose utilization (LCGU) via C14-2-deoxyglucose autoradiography in freely moving conscious rats. Both LY404187 and LY451395 significantly and dose-dependently reversed ethanol-induced deficits in both motor coordination and disruptions in an operant task where animals were trained to press a lever for food reward. Both prophylactic and acute intervention treatment with LY404187 reversed ethanol-induced deficits in motor coordination. Given that LY451395 and related AMPA receptor potentiators/ampakines are tolerated in both healthy volunteers and elderly patients, these data suggest that such compounds may form a potential management strategy for acute alcohol intoxication.     

Che-1 affects cell growth by interfering with the recruitment of HDAC1 by Rb

DNA tumor virus oncoproteins bind and inactivate Rb by interfering with the Rb/HDAC1 interaction. Che-1 is a recently identified human Rb binding protein that inhibits the Rb growth suppressing function. Here we show that Che-1 contacts the Rb pocket region and competes with HDAC1 for Rb binding site, removing HDAC1 from the Rb/E2F complex in vitro and from the E2F target promoters in vivo. Che-1 overexpression activates DNA synthesis in quiescent NIH-3T3 cells through HDAC1 displacement. Consistently, Che-1-specific RNA interference affects E2F activity and cell proliferation in human fibroblasts but not in the pocket protein-defective 293 cells. These findings indicate the existence of a pathway of Rb regulation supporting Che-1 as the cellular counterpart of DNA tumor virus oncoproteins.     

Laparoscopic removal of a persistent Müllerian duct in a male: case report.

The authors refer to the use of the laparoscopic approach in Persistent Mullerian Duct Syndrome, starting from a case of "male vagina" with an anomaly inserted left ductus deferens inside the mullerian persistent duct. This patient was operated on using the laparoscopic technique.     

Examining the neural targets of the AMPA receptor potentiator LY404187 in the rat brain using pharmacological magnetic resonance imaging

Rationale Drugs that enhance α-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid (AMPA) receptor-mediated glutamatergic transmission, such as the AMPA receptor potentiator LY404187, may form treatment strategies for disorders of cognition, learning and memory. Objectives Pharmacological magnetic resonance imaging (phMRI) uses blood oxygenation level dependent (BOLD) contrast as a marker of neuronal activity and allows dynamic non-invasive in vivo imaging of the effects of CNS-active compounds. This study used phMRI to examine the effects of LY404187 in the rat brain. Method Groups of Sprague Dawley rats (n=7) were anaesthetised and placed in a 4.7 Tesla superconducting magnet before receiving an acute dose of LY404187 (0.5 mg/kg s.c.), either alone or after pretreatment with the selective AMPA/kainate antagonist LY293558 (15 mg/kg s.c.), or LY293558 alone (15 mg/kg s.c.). Brain images were acquired for each subject every minute for 180 min. These volumes were extensively pre-processed before being analysed for changes in BOLD contrast. Results LY404187 produced significant increases in BOLD contrast in brain regions including the hippocampus, lateral and medial habenulae and superior and inferior colliculi. These changes were blocked by LY293558. When administered alone, LY293558 caused widespread decreases in BOLD contrast. Conclusions The known actions of LY404187 suggest the observed BOLD signal increases reflect increases in excitatory neurotransmission. The decreases in signal following LY293558 alone are harder to interpret and are discussed in terms of the negative BOLD response. This study provides the first evidence that the effects of AMPA receptor-mediating compounds can be observed using phMRI.     

Effects of pertussis toxin on the behavioural and ECoG spectrum changes induced by clonidine and yohimbine after their microinfusion into the locus coeruleus.

1. Pertussis toxin, a substance which interferes selectively with receptor-mediated signal transduction mechanisms, was injected into the locus coeruleus of rats 1, 2, 3, 6 or 10 days before the microinjection of clonidine or yohimbine into the same site. 2. Clonidine produced in control rats typical behavioural sedation and/or sleep and ECoG synchronization while yohimbine produced behavioural arousal and ECoG desynchronization. 3. The behavioural and ECoG effects of both compounds were blocked in animals pretreated with pertussis toxin. This activity was more marked from 2 to 6 days after pertussis toxin pretreatment and was restored 10 days after toxin administration. In addition, the behavioural and ECoG slow-wave sleep observed after intraperitoneal administration of clonidine (0.2 mumol kg-1) was significantly reduced by prior (3 days) microinfusion of pertussis toxin into the locus coeruleus. 4. These results are consistent with the hypothesis that the behavioural and ECoG effects of clonidine and yohimbine are mediated via a guanine regulatory protein which is affected by pertussis toxin.