Human biodistribution and dosimetry of ¹¹C-CUMI-101, an agonist radioligand for serotonin-1a receptors in brain

As a reported agonist,¹¹C-CUMI-101 is believed to selectively bind the G-protein-coupled state of the serotonin-1A (5-HT_1A) receptor, thereby providing a measure of the active subset of all 5-HT_1A receptors in brain. Although ¹¹C-CUMI-101 has been successfully used to quantify 5-HT_1A receptors in human and monkey brain, its radiation exposure has not previously been reported. The purpose of this study was to calculate the radiation exposure to organs of the body based on serial whole-body imaging with positron emission tomography (PET) in human subjects.

Methods

Nine healthy volunteers were injected with 428±84 MBq (mean ± SD) ¹¹C-CUMI-101 and then imaged with a PET-only device for two hours from head to mid-thigh. Eleven source organs (brain, heart, liver, pancreas, stomach, spleen, lungs, kidneys, lumbar spine L1-5, thyroid, and urinary bladder) were identified on whole body images and used to calculate radiation doses using the software program OLINDA/EXM 1.1. To confirm that we had correctly identified the pancreas, a tenth subject was imaged on a PET/CT device.

Results

Brain had high uptake (∼11% of injected activity (IA)) at 10 min. Although liver had the highest uptake (∼35% IA at 120 min), excretion of this activity was not visible in gall bladder or intestine during the scanning session. Organs which received the highest doses (microSv/MBq) were pancreas (32.0), liver (18.4), and spleen (14.5). The effective dose of ¹¹C-CUMI-101 was 5.3±0.5 microSv/MBq.

Conclusion

The peak brain uptake (∼11% IA) of ¹¹C-CUMI-101 is the highest among more than twenty ¹¹C-labeled ligands reported in the literature and provides good counting statistics from relatively low injected activities. Similar to that of other ¹¹C-labeled ligands for brain imaging, the effective dose of ¹¹C-CUMI-101 is 5.3±0.5 microSv/MBq, a value that can now be used to estimate the radiation risks in future research studies.     

Spontaneous hemodynamic oscillations during human sleep and sleep stage transitions characterized with near-infrared spectroscopy

Understanding the interaction between the nervous system and cerebral vasculature is fundamental to forming a complete picture of the neurophysiology of sleep and its role in maintaining physiological homeostasis. However, the intrinsic hemodynamics of slow-wave sleep (SWS) are still poorly known. We carried out 30 all-night sleep measurements with combined near-infrared spectroscopy (NIRS) and polysomnography to investigate spontaneous hemodynamic behavior in SWS compared to light (LS) and rapid-eye-movement sleep (REM). In particular, we concentrated on slow oscillations (3-150 mHz) in oxy- and deoxyhemoglobin concentrations, heart rate, arterial oxygen saturation, and the pulsation amplitude of the photoplethysmographic signal. We also analyzed the behavior of these variables during sleep stage transitions. The results indicate that slow spontaneous cortical and systemic hemodynamic activity is reduced in SWS compared to LS, REM, and wakefulness. This behavior may be explained by neuronal synchronization observed in electrophysiological studies of SWS and a reduction in autonomic nervous system activity. Also, sleep stage transitions are asymmetric, so that the SWS-to-LS and LS-to-REM transitions, which are associated with an increase in the complexity of cortical electrophysiological activity, are characterized by more dramatic hemodynamic changes than the opposite transitions. Thus, it appears that while the onset of SWS and termination of REM occur only as gradual processes over time, the termination of SWS and onset of REM may be triggered more abruptly by a particular physiological event or condition. The results suggest that scalp hemodynamic changes should be considered alongside cortical hemodynamic changes in NIRS sleep studies to assess the interaction between the autonomic and central nervous systems.     

Archaeal Communities in Boreal Forest Tree Rhizospheres Respond to Changing Soil Temperatures

Temperature has generally great effects on both the activity and composition of microbial communities in different soils. We tested the impact of soil temperature and three different boreal forest tree species on the archaeal populations in the bulk soil, rhizosphere, and mycorrhizosphere. Scots pine, silver birch, and Norway spruce seedlings were grown in forest humus microcosms at three different temperatures, 7–11.5°C (night–day temperature), 12–16°C, and 16–22°C, of which 12–16°C represents the typical mid-summer soil temperature in Finnish forests. RNA and DNA were extracted from indigenous ectomycorrhiza, non-mycorrhizal long roots, and boreal forest humus and tested for the presence of archaea by nested PCR of the archaeal 16S rRNA gene followed by denaturing gradient gel electrophoresis (DGGE) profiling and sequencing. Methanogenic Euryarchaeota belonging to Methanolobus sp. and Methanosaeta sp. were detected on the roots and mycorrhiza. The most commonly detected archaeal 16S rRNA gene sequences belonged to group I.1c Crenarchaeota, which are typically found in boreal and alpine forest soils. Interestingly, also one sequence belonging to group I.1b Crenarchaeota was detected from Scots pine mycorrhiza although sequences of this group are usually found in agricultural and forest soils in temperate areas. Tree- and temperature-related shifts in the archaeal population structure were observed. A clear decrease in crenarchaeotal DGGE band number was seen with increasing temperature, and correspondingly, the number of euryarchaeotal DGGE bands, mostly methanogens, increased. The greatest diversity of archaeal DGGE bands was detected in Scots pine roots and mycorrhizas. No archaea were detected from humus samples from microcosms without tree seedling, indicating that the archaea found in the mycorrhizosphere and root systems were dependent on the plant host. The detection of archaeal 16S rRNA gene sequences from both RNA and DNA extractions show that the archaeal populations were living and that they may have significant contribution to the methane cycle in boreal forest soil, especially when soil temperatures rise.     

T cell receptor expression can switch on and off at a posttranslational level.

The human T acute lymphocytic leukemia cell line, SUP-T13, is a mosaic of TCR/CD3+ and TCR/CD3- cells. Individual SUP-T13 cells can spontaneously switch on and off surface TCR/CD3 expression. This switching was demonstrated by culturing and analysis of single cell clones that were TCR/CD3+ or TCR/CD3-. The rate of switching is about 10(-2)/cell per generation in either direction. This is too high to be due to a spontaneous mutation event. Furthermore, switched cells can revert at similar rates, as demonstrated by repeated cloning and reanalysis. This makes it likely that a regulatory change is responsible for switching. In support of this, all known TCR/CD3 proteins are found intracellularly in TCR/CD3- cells, and they associate with each other as in TCR/CD3+ cells. Furthermore, no structural abnormalities of the TCR/CD3 chains can be seen in TCR/CD3- cells using two-dimensional electrophoresis. However, in these cells, the chains accumulate in great excess intracellularly. This accumulation is specific to the TCR/CD3 complex, as other glycoproteins are still expressed normally on the cell surface. Thus, there is regulation of TCR expression at a posttranslational level. These TCR/CD3- cells may lead to the identification of novel protein(s) involved in glycosylating, processing, or transporting the TCR/CD3 complex. Potential loss of TCR/CD3 expression may also limit the feasibility of TCR-based therapies for T cell leukemias.     

Quantitative Changes in Gimap3 and Gimap5 Expression Modify Mitochondrial DNA Segregation in Mice

Mammalian mitochondrial DNA (mtDNA) is a high-copy maternally inherited genome essential for aerobic energy metabolism. Mutations in mtDNA can lead to heteroplasmy, the co-occurence of two different mtDNA variants in the same cell, which can segregate in a tissue-specific manner affecting the onset and severity of mitochondrial dysfunction. To investigate mechanisms regulating mtDNA segregation we use a heteroplasmic mouse model with two polymorphic neutral mtDNA haplotypes (NZB and BALB) that displays tissue-specific and age-dependent selection for mtDNA haplotypes. In the hematopoietic compartment there is selection for the BALB mtDNA haplotype, a phenotype that can be modified by allelic variants of Gimap3. Gimap3 is a tail-anchored member of the GTPase of the immunity-associated protein (Gimap) family of protein scaffolds important for leukocyte development and survival. Here we show how the expression of two murine Gimap3 alleles from Mus musculus domesticus and M. m. castaneus differentially affect mtDNA segregation. The castaneus allele has incorporated a uORF (upstream open reading frame) in-frame with the Gimap3 mRNA that impairs translation and imparts a negative effect on the steady-state protein abundance. We found that quantitative changes in the expression of Gimap3 and the paralogue Gimap5, which encodes a lysosomal protein, affect mtDNA segregation in the mouse hematopoietic tissues. We also show that Gimap3 localizes to the endoplasmic reticulum and not mitochondria as previously reported. Collectively these data show that the abundance of protein scaffolds on the endoplasmic reticulum and lysosomes are important to the segregation of the mitochondrial genome in the mouse hematopoietic compartment.     

Hypoxia increases intensity of epidermal papillomatosis in roach Rutilus rutilus

Hypoxia, which occurs frequently in aquatic ecosystems and is mainly due to increasing eutrophication can cause severe environmental stress in fish. We investigated experimentally the hypothesis that hypoxia could be one of the environmental stress factors that can induce papillomatosis in fish. Male roach Rutilus rutilus exposed to periodic oxygen deficiency and accompanied temperature increases (OT group) showed the highest increase in the intensity of papillomatosis, as measured by the number of scales covered by papillomatosis tumors. The second highest increase in disease intensity was among male roach exposed to periodical temperature increases. The incidence of such tumors was lowest in the control group, which was exposed to neither hypoxia nor increased temperature. The mortality of fish during the 17 d experiment was highest and the condition factor was lowest in the OT group, indicating this group experienced a higher level of stress. The apparent interaction of hypoxia and temperature suggests that these environmental stressors are among the multifactorial elements leading to papillomatosis in roach. Furthermore, these results provide experimental evidence to indicate that hypoxia may contribute to tumor development in fish.     

Skills training groups for men with ADHD in compulsory care due to substance use disorder: a feasibility study

Dialectical behavior therapy (DBT)-based skills training has been developed and previously evaluated for adults with ADHD in a psychiatric outpatient context. The aim of the present study was to evaluate the feasibility of DBT-based skills training as a voluntary intervention for men with ADHD in compulsory care due to severe substance abuse. Forty sufficiently detoxified men with ADHD in compulsory care due to life-threatening substance use disorder (SUD) were included in DBT-based skills training groups. Self- and staff-rating scales were administered before and after the treatment. The refusal rate was 42.9 %. Of those who started the DBT-based skills training, 70 % completed the treatment (attendance at ≥75 % of the sessions). The treatment acceptability was good. Both ADHD and psychiatric symptoms decreased from pre- to post-intervention in self-ratings, but not in staff ratings. The patients reported improved general well-being. The correlation between self- and staff ratings was poor. Motivation for voluntary nonpharmacological treatment was low in a compulsory care context. However, the results indicate that a DBT-based skills training program for adults with ADHD may be feasible for some patients with ADHD in combination with SUD in compulsory care, provided that considerable resources are allocated with adjustments to the target group and compulsory care context.     

The 3′→5′ exonuclease associated with HeLa DNA polymerase epsilon

The 3′→5′ exonuclease activity of highly purified large form of human DNA polymerase epsilon was studied. The activity removes mononucleotides from the 3′ end of an oligonucleotide with a non-processive mechanism and leaves 5′-terminal trinucleotide non-hydrolyzed. This is the case both with single-stranded oligonucleotides and with oligonucleotides annealed to complementary regions of M13DNA. However, the reaction rates with single-stranded oligonucleotides are at least ten-fold when compared to those with completely base-paired oligonucleotides. Conceivably, mismatched 3′ end of an oligonucleotide annealed to M13DNA is rapidly removed and the hydrolysis is slown down when double-stranded region is reached. The preferential removal of a non-complementary 3′ end and the non-processive mechanism are consistent with anticipated proofreading function. In addition to the 3′→5′ exonuclease activity, an 5′→3′ exonuclease activity is often present even in relatively highly purified DNA polymerase epsilon preparates suggesting that such an activity may be an essential com-ponent for the action of this enzymein vivo. Contrary to the 3′→5′ exonuclease activity, the 5′→3′ exonuclease is separable from the polymerase activity.     

Antigenic Differences between AS03 Adjuvanted Influenza A (H1N1) Pandemic Vaccines: Implications for Pandemrix-Associated Narcolepsy Risk

Background

Narcolepsy results from immune-mediated destruction of hypocretin secreting neurons in hypothalamus, however the triggers and disease mechanisms are poorly understood. Vaccine-attributable risk of narcolepsy reported so far with the AS03 adjuvanted H1N1 vaccination Pandemrix has been manifold compared to the AS03 adjuvanted Arepanrix, which contained differently produced H1N1 viral antigen preparation. Hence, antigenic differences and antibody response to these vaccines were investigated.

Methods and Findings

Increased circulating IgG-antibody levels to Pandemrix H1N1 antigen were found in 47 children with Pandemrix-associated narcolepsy when compared to 57 healthy children vaccinated with Pandemrix. H1N1 antigen of Arepanrix inhibited poorly these antibodies indicating antigenic difference between Arepanrix and Pandemrix. High-resolution gel electrophoresis quantitation and mass spectrometry identification analyses revealed higher amounts of structurally altered viral nucleoprotein (NP) in Pandemrix. Increased antibody levels to hemagglutinin (HA) and NP, particularly to detergent treated NP, was seen in narcolepsy. Higher levels of antibodies to NP were found in children with DQB1*06∶02 risk allele and in DQB1*06∶02 transgenic mice immunized with Pandemrix when compared to controls.

Conclusions

This work identified 1) higher amounts of structurally altered viral NP in Pandemrix than in Arepanrix, 2) detergent-induced antigenic changes of viral NP, that are recognized by antibodies from children with narcolepsy, and 3) increased antibody response to NP in association of DQB1*06∶02 risk allele of narcolepsy. These findings provide a link between Pandemrix and narcolepsy. Although detailed mechanisms of Pandemrix in narcolepsy remain elusive, our results move the focus from adjuvant(s) onto the H1N1 viral proteins.     

Novel Mechanism of Arenavirus-Induced Liver Pathology

Viral hemorrhagic fevers (VHFs) encompass a group of diseases with cardinal symptoms of fever, hemorrhage, and shock. The liver is a critical mediator of VHF disease pathogenesis and high levels of ALT/AST transaminases in plasma correlate with poor prognosis. In fact, Lassa Fever (LF), the most prevalent VHF in Africa, was initially clinically described as hepatitis. Previous studies in non-human primate (NHP) models also correlated LF pathogenesis with a robust proliferative response in the liver. The purpose of the current study was to gain insight into the mechanism of liver injury and to determine the potential role of proliferation in LF pathogenesis. C57Bl/6J mice were infected with either the pathogenic (for NHPs) strain of lymphocytic choriomeningitis virus (LCMV, the prototypic arenavirus), LCMV-WE, or with the non-pathogenic strain, LCMV-ARM. As expected, LCMV-WE, but not ARM, caused a hepatitis-like infection. LCMV-WE also induced a robust increase in the number of actively cycling hepatocytes. Despite this increase in proliferation, there was no significant difference in liver size between LCMV-WE and LCMV-ARM, suggesting that cell cycle was incomplete. Indeed, cells appeared arrested in the G₁ phase and LCMV-WE infection increased the number of hepatocytes that were simultaneously stained for proliferation and apoptosis. LCMV-WE infection also induced expression of a non-conventional virus receptor, AXL-1, from the TAM (TYRO3/AXL/MERTK) family of receptor tyrosine kinases and this expression correlated with proliferation. Taken together, these results shed new light on the mechanism of liver involvement in VHF pathogenesis. Specifically, it is hypothesized that the induction of hepatocyte proliferation contributes to expansion of the infection to parenchymal cells. Elevated levels of plasma transaminases are likely explained, at least in part, by abortive cell cycle arrest induced by the infection. These results may lead to the development of new therapies to prevent VHF progression.