Isolation of 76Br from irradiated Cu276Se targets using dry distillation: evaluations and improvement for routine production

Introduction 76Br is of interest for in vivo PET imaging applications. Its relatively long half-life (16.1 h) allows use not only on small molecules but also proteins which have slow excretion as carrier molecules. Irradiation using a low energy proton beam (~ 20 MeV) on an enriched Cu276Se target, followed by dry distillation with thermal chromatography, is one of the best methods to obtain sufficient amounts of 76Br for clinical applications1,2. However, the thermal chromatography is plagued by poor reproducibility and appears unsuitable for automation of its production, leading us to remove the thermal chroma-tography from the dry distillation. In this investigation we employed H2O solution to collect 76Br and optimized the distillation condition using a small amount of 77Br (57.0 h). We also produced large amount of 76Br under the optimized conditions to evaluate the dry distillation method. Material and Methods Target preparation and dry distillation were conducted based on the methods described in previous reports1,2. To produce 77Br, Cu2natSe target was irradiated with 20 MeV proton beams (5 µA) accelerated by AVF cyclotron in the Japan Atomic Energy Agency. The following two systems were used in the dry distillation optimization studies; (1) an initial system was composed of two furnaces, a main and an auxiliary furnace. Temperature of each furnace was set at 1050 °C (main) and 200 °C (auxiliary) respectively; (2) the second system was made of one large furnace composed of heating and cooling area. Temperature of the heating area was varied from 1050 to 1120 °C. In both systems PTFE tubing, leading to a H2O solution (15 mL), was inserted into the apparatus. The irradiated target was heated under streaming Ar gas (30 mL/min.). An enriched Cu276Se target (76Se enrichment: 99.67%) was used for 76Br production. Radioactivity was measured on a high-purity germanium (HPGe) detector coupled to a multichannel analyzer. TLC analyses were conducted on Al2O3 plates (Merck) using 7:1 acetone:H2O as the eluting solvent. Results and Conclusion Low efficiency (33 %) of 77Br recovery was ob-served in the initial system. Distribution of radioactivity inside the apparatus showed that 35 % was trapped in the PTFE tube and the quartz tube. The recovery yield was increased up to 54 % when the auxiliary furnace was turned off, indicating that the temperature gradient inside the quartz tube is suitable to carry 77Br effectively to the H2O trap. We initially used a quartz boat to place the irradiated target in the furnace, but found that using a reusable tungsten backing was better. However, we found that recovery yield was dramatically reduced to 18 %. The studies where the temperature was varied showed that releasing efficiency was increased up to 100 % at the temperature of 1120 °C. Good recovery yield (~ 77 %) was achieved after optimizing the temperature gradient (FIG. 1b). Using the optimized setup, 76Br production runs (n = 6) have been conducted, allowing us to recover up to 39.8 MBq/µAh (EOB) of 76Br. High specific activity (~4400 GBq/µmol) was obtained in the final solution. TLC analysis showed that chemical form obtained was bromide. We concluded that the dry distillation using H2O trap is capable of providing enough high purity 76Br for clinical applications

Collectivity of neutron-rich Ti isotopes

The structure of the neutron-rich nucleus 58Ti was investigated via proton inelastic scattering in inverse kinematics at a mean energy of 42.0 MeV/nucleon. By measuring the deexcitation γ rays, three transitions with the energies of 1046(11) keV, 1376(18) keV, and 1835(27) keV were identified. The angle-integrated cross section for the 1046-keV excitation, which corresponds to the decay from the first 2+ state, was determined to be 13(7) mb. The deformation length δp,p′ was extracted from the cross section to be 0.83−0.30+0.22 fm. The energy of the first 2+ state and the δp,p′ value are comparable to the ones of 56Ti, which indicates that the collectivity of the Ti isotopes does not increase significantly with neutron number until N=36. This fact indicates that 58Ti is outside of the region of the deformation known in the neutron-rich nuclei around N=40

Dual Functions of ASCIZ in the DNA Base Damage Response and Pulmonary Organogenesis

Zn2+-finger proteins comprise one of the largest protein superfamilies with diverse biological functions. The ATM substrate Chk2-interacting Zn2+-finger protein (ASCIZ; also known as ATMIN and ZNF822) was originally linked to functions in the DNA base damage response and has also been proposed to be an essential cofactor of the ATM kinase. Here we show that absence of ASCIZ leads to p53-independent late-embryonic lethality in mice. Asciz-deficient primary fibroblasts exhibit increased sensitivity to DNA base damaging agents MMS and H2O2, but Asciz deletion or knock-down does not affect ATM levels and activation in mouse, chicken, or human cells. Unexpectedly, Asciz-deficient embryos also exhibit severe respiratory tract defects with complete pulmonary agenesis and severe tracheal atresia. Nkx2.1-expressing respiratory precursors are still specified in the absence of ASCIZ, but fail to segregate properly within the ventral foregut, and as a consequence lung buds never form and separation of the trachea from the oesophagus stalls early. Comparison of phenotypes suggests that ASCIZ functions between Wnt2-2b/ß-catenin and FGF10/FGF-receptor 2b signaling pathways in the mesodermal/endodermal crosstalk regulating early respiratory development. We also find that ASCIZ can activate expression of reporter genes via its SQ/TQ-cluster domain in vitro, suggesting that it may exert its developmental functions as a transcription factor. Altogether, the data indicate that, in addition to its role in the DNA base damage response, ASCIZ has separate developmental functions as an essential regulator of respiratory organogenesis

Reduced Food Intake and Body Weight in Mice Deficient for the G Protein-Coupled Receptor GPR82

G protein-coupled receptors (GPCR) are involved in the regulation of numerous physiological functions. Therefore, GPCR variants may have conferred important selective advantages during periods of human evolution. Indeed, several genomic loci with signatures of recent selection in humans contain GPCR genes among them the X-chromosomally located gene for GPR82. This gene encodes a so-called orphan GPCR with unknown function. To address the functional relevance of GPR82 gene-deficient mice were characterized. GPR82-deficient mice were viable, reproduced normally, and showed no gross anatomical abnormalities. However, GPR82-deficient mice have a reduced body weight and body fat content associated with a lower food intake. Moreover, GPR82-deficient mice showed decreased serum triacylglyceride levels, increased insulin sensitivity and glucose tolerance, most pronounced under Western diet. Because there were no differences in respiratory and metabolic rates between wild-type and GPR82-deficient mice our data suggest that GPR82 function influences food intake and, therefore, energy and body weight balance. GPR82 may represent a thrifty gene most probably representing an advantage during human expansion into new environments

Gastrointestinal Hyperplasia with Altered Expression of DNA Polymerase β

Background: Altered expression of DNA polymerase β (Pol β) has been documented in a large percentage of human tumors. However, tumor prevalence or predisposition resulting from Pol β over-expression has not yet been evaluated in a mouse model. Methodology/Principal Findings: We have recently developed a novel transgenic mouse model that over-expresses Pol β. These mice present with an elevated incidence of spontaneous histologic lesions, including cataracts, hyperplasia of Brunner's gland and mucosal hyperplasia in the duodenum. In addition, osteogenic tumors in mice tails, such as osteoma and osteosarcoma were detected. This is the first report of elevated tumor incidence in a mouse model of Pol β over-expression. These findings prompted an evaluation of human gastrointestinal tumors with regard to Pol β expression. We observed elevated expression of Pol β in stomach adenomas and thyroid follicular carcinomas, but reduced Pol β expression in esophageal adenocarcinomas and squamous carcinomas. Conclusions/Significance: These data support the hypothesis that balanced and proficient base excision repair protein expression and base excision repair capacity is required for genome stability and protection from hyperplasia and tumor formation

SOX2 Co-Occupies Distal Enhancer Elements with Distinct POU Factors in ESCs and NPCs to Specify Cell State

SOX2 is a master regulator of both pluripotent embryonic stem cells (ESCs) and multipotent neural progenitor cells (NPCs); however, we currently lack a detailed understanding of how SOX2 controls these distinct stem cell populations. Here we show by genome-wide analysis that, while SOX2 bound to a distinct set of gene promoters in ESCs and NPCs, the majority of regions coincided with unique distal enhancer elements, important cis-acting regulators of tissue-specific gene expression programs. Notably, SOX2 bound the same consensus DNA motif in both cell types, suggesting that additional factors contribute to target specificity. We found that, similar to its association with OCT4 (Pou5f1) in ESCs, the related POU family member BRN2 (Pou3f2) co-occupied a large set of putative distal enhancers with SOX2 in NPCs. Forced expression of BRN2 in ESCs led to functional recruitment of SOX2 to a subset of NPC-specific targets and to precocious differentiation toward a neural-like state. Further analysis of the bound sequences revealed differences in the distances of SOX and POU peaks in the two cell types and identified motifs for additional transcription factors. Together, these data suggest that SOX2 controls a larger network of genes than previously anticipated through binding of distal enhancers and that transitions in POU partner factors may control tissue-specific transcriptional programs. Our findings have important implications for understanding lineage specification and somatic cell reprogramming, where SOX2, OCT4, and BRN2 have been shown to be key factors

Structural and functional evolution of the P2Y12-like receptor group

Metabotropic pyrimidine and purine nucleotide receptors (P2Y receptors) belong to the superfamily of G protein-coupled receptors (GPCR). They are distinguishable from adenosine receptors (P1) as they bind adenine and/or uracil nucleotide triphosphates or diphosphates depending on the subtype. Over the past decade, P2Y receptors have been cloned from a variety of tissues and species, and as many as eight functional subtypes have been characterized. Most recently, several members of the P2Y12-like receptor group, which includes the clopidogrel-sensitive ADP receptor P2Y12, have been deorphanized. The P2Y12-like receptor group comprises several structurally related GPCR which, however, display heterogeneous agonist specificity including nucleotides, their derivatives, and lipids. Besides the established function of P2Y12 in platelet activation, expression in macrophages, neuronal and glial cells as well as recent results from functional studies implicate that several members of this group may have specific functions in neurotransmission, inflammation, chemotaxis, and response to tissue injury. This review focuses specifically on the structure-function relation and shortly summarizes some aspects of the physiological relevance of P2Y12-like receptor members

Investigation of the human oesophagus as a new monitoring site for blood oxygen saturation

Pulse oximeter probes placed peripherally may fail to give accurate values of arterial blood oxygen saturation (SpO2) when peripheral perfusion is poor. Since central blood flow may be preferentially preserved, the oesophagus was suggested as an alternative monitoring site. A reflectance oesophageal photoplethysmographic (PPG) probe and a multiplexed data acquisition system, operating simultaneously at two wavelengths and incorporating an external three-lead electrocardiogram (ECG) reference channel, has been developed. It has been used to investigate the suitability of the oesophagus as a possible monitoring site for SpO2 in cases of compromised peripheral perfusion. Oesophageal PPG signals and standard ECG traces were obtained from 16 anaesthetized patients and displayed on a laptop computer. Measurable PPG signals with high signal-to-noise ratios at both infrared and red wavelengths were obtained from all five oesophageal depths investigated. The maximum PPG amplitude occurred at 25 cm from the upper incisors in the mid-oesophagus. The measured pulse transit times (PTTs) to the oesophagus were consistent with previous measurements at peripheral sites and had a minimum value of 67 +/- 30 ms at a depth of 30 cm. There was broad agreement between the calculated values of oesophageal SpO2 and those from a commercial finger pulse oximeter