Automated reference region extraction and population-based input function for brain [11C]TMSX PET image analyses

[¹¹C]TMSX ([7-N-methyl-¹¹C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine) is a selective adenosine A2A receptor (A_2AR) radioligand. In the central nervous system (CNS), A_2AR are linked to dopamine D₂ receptor function in striatum, but they are also important modulators of inflammation. The golden standard for kinetic modeling of brain [¹¹C]TMSX positron emission tomography (PET) is to obtain arterial input function via arterial blood sampling. However, this method is laborious, prone to errors and unpleasant for study subjects. The aim of this work was to evaluate alternative input function acquisition methods for brain [¹¹C]TMSX PET imaging. First, a noninvasive, automated method for the extraction of gray matter reference region using supervised clustering (SCgm) was developed. Second, a method for obtaining a population-based arterial input function (PBIF) was implemented. These methods were created using data from 28 study subjects (7 healthy controls, 12 multiple sclerosis patients, and 9 patients with Parkinson''s disease). The results with PBIF correlated well with original plasma input, and the SCgm yielded similar results compared with cerebellum as a reference region. The clustering method for extracting reference region and the population-based approach for acquiring input for dynamic [¹¹C]TMSX brain PET image analyses appear to be feasible and robust methods, that can be applied in patients with CNS pathology.     

Validation of [11C]ORM‐13070 as a PET tracer for alpha2c‐adrenoceptors in the human brain

This study explored the use of the α_2C‐adrenoceptor PET tracer [¹¹C]ORM‐13070 to monitor α_2C‐AR occupancy in the human brain. The subtype‐nonselective α₂‐AR antagonist atipamezole was administered to eight healthy volunteer subjects to determine its efficacy and potency (E_max and EC₅₀) at inhibiting tracer uptake. We also explored whether the tracer could reveal changes in the synaptic concentrations of endogenous noradrenaline in the brain, in response to several pharmacological and sensory challenge conditions. We assessed occupancy from the bound‐to‐free ratio measured during 5–30 min post injection. Based on extrapolation of one‐site binding, the maximal extent of inhibition of striatal [¹¹C]ORM‐13070 uptake (E_max) achievable by atipamezole was 78% (95% CI 69–87%) in the caudate nucleus and 65% (53–77%) in the putamen. The EC₅₀ estimates of atipamezole (1.6 and 2.5 ng/ml, respectively) were in agreement with the drug's affinity to α_2C‐ARs. These findings represent clear support for the use of [¹¹C]ORM‐13070 for monitoring drug occupancy of α_2C‐ARs in the living human brain. Three of the employed noradrenaline challenges were associated with small, approximately 10–16% average reductions in tracer uptake in the dorsal striatum (atomoxetine, ketamine, and the cold pressor test; P < 0.05 for all), but insulin‐induced hypoglycemia did not affect tracer uptake. The tracer is suitable for studying central nervous system receptor occupancy by α_2C‐AR ligands in human subjects. [¹¹C]ORM‐13070 also holds potential as a tool for in vivo monitoring of synaptic concentrations of noradrenaline, but this remains to be further evaluated in future studies. Synapse 69:172–181, 2015. © 2014 Wiley Periodicals, Inc.     

Effects of anti-Helicobacter pylori treatment and probiotic supplementation on intestinal microbiota

The aims of this study were (i) to evaluate the effect of recommended antimicrobial treatment of Helicobacter pylori infection, consisting of clarithromycin, amoxicillin and lansoprazole, on intestinal microbiota and (ii) to determine the ability of a probiotic combination containing Lactobacillus rhamnosus GG, L. rhamnosus LC705, Propionibacterium freudenreichii ssp. shermanii JS and Bifidobacterium breve Bb99 to prevent treatment-induced alterations in the intestinal microbiota. Faecal samples were obtained from 39 H. pylori-infected patients randomised into two treatment groups. In addition, 19 H. pylori-negative volunteers were included in the study as a control group. Samples were collected before, during and after treatment and microbiota were analysed by fluorescence in situ hybridisation and culture. The quantities of the predominant bacterial groups were altered significantly in both groups and disturbances were seen even 9 weeks after treatment was complete. Probiotics slightly counteracted the effects of anti-H. pylori treatment, seen as significantly less alterations in the total numbers of aerobes and lactobacilli/enterococci. At baseline, the composition of the microbiota between H. pylori-positive versus H. pylori-negative control individuals differed with regard to clostridia and the total number of anaerobes. The recommended treatment for H. pylori infection induces long-term disturbances in the intestinal microbiota. The probiotic combination appeared to result in only minor changes in the microbiota.     

Induction of PUMA-α and down-regulation of PUMA-β expression is associated with benzo(a)pyrene-induced apoptosis in MCF-7 cells

Benzo(a)pyrene (BP) forms benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE)-DNA adducts in human breast adenocarcinoma MCF-7 cells, leading to p53 protein induction and phosphorylation. Although BP-induced apoptosis in rodent cells is known, it is still unclear in human cells. Here we have analyzed the effects of BP on p53 related apoptotic proteins, cell cycle and cell death in MCF-7 cells. PUMA-protein (p53 up-regulated modulator of apoptosis) levels were changed after BP exposure so that PUMA-α protein was statistically significantly increased whereas PUMA-β protein was statistically significantly decreased. PUMA-protein levels were also investigated in ZR-75-1 cells, where PUMA-α protein was statistically significantly increased. Cytochrome c, which is released from mitochondria during apoptosis to form the apoptosome, was increased in cytoplasmic fraction after BP exposure in MCF-7 cells. Increased apoptosis was also seen after 48 and 72 h BP exposure (2.5 and 5 μM). In addition, BP decreased dose dependently cell viability (2.5 and 5 μM) and increased ROS formation (1 and 10 μM). Our results suggest that PUMA-α protein is involved in BP-induced cell death most likely through a p53 dependent apoptotic pathway.     

The red cell LW blood group protein is an intercellular adhesion molecule which binds to CD11/CD18 leukocyte integrins

Leukocyte adhesion involves the leukocyte-specific integrins CD11a/CD18, CD11b/CD18 and CD11c/CD18, which bind to intercellular adhesion molecules (ICAM). Three ICAM have been described, and are expressed on leukocytes and various other cells, but are absent from red cells. Here, we show that the red cell Landsteiner-Wiener (LW) blood group glycoprotein is an ICAM which binds to the leukocyte-specific integrins. This finding has important implications in red cell physiology.     

Clustering of Serratia marcescens infections in a neonatal intensive care unit.

OBJECTIVES: To study clusters of infections caused by Serratia marcescens in a neonatal intensive care unit (NICU) and to determine risk factors for S. marcescens infection or colonization. DESIGN: Genotyping of S. marcescens isolates was performed by pulsed-field gel electrophoresis (PFGE). A retrospective case-control study was conducted. SETTING: A tertiary-care pediatric hospital with a 16-bed NICU. PATIENTS: All neonates with at least one culture positive for S. marcescens in the NICU during December 1999 to July 2002. Case-patients (n = 11) treated in the NICU during December 1999 to February 2000 were included in the case-control study. Neonates treated in the NICU for at least 72 hours during the same period with cultures negative for S. marcescens were used as control-patients (n = 27). RESULTS: S. marcescens was cultured from 19 neonates; 9 were infected and 10 were colonized. PFGE analysis identified three epidemic strains; each cluster consisted of identical isolates, except one isolate in the first cluster that was different. The risk factors identified were low birth weight, prematurity, prolonged respiratory therapy, prolonged use of antibiotics, and maternal infection prior to delivery. Overcrowding and understaffing were recorded simultaneously with the clusters. CONCLUSIONS: PFGE analysis showed three independent clusters. Several factors contributed to spread of the epidemic strains: (1) there were many severely premature and susceptible neonates, (2) the NICU was overcrowded during the clusters, and (3) transmission was likely to occur via the hands of staff. Cohorting and improvement of routine infection control measures led to the cessation of each cluster.     

Up-regulation of Bcl-2 during adipogenesis mediates apoptosis resistance in human adipocytes

Targeting apoptotic pathways in adipocytes has been suggested as a pharmacological approach to treat obesity. However, adipocyte apoptosis was identified as a cause for macrophage infiltration into adipose tissue. Previous studies suggest that mature adipocytes are less sensitive to apoptotic stimuli as compared to preadipocytes. Here, we aimed to identify proteins mediating apoptosis resistance in adipocytes.