Development of a small prototype for a proof-of-concept of OpenPET imaging

The OpenPET geometry is our new idea to visualize a physically opened space between two detector rings. In this paper, we developed the first small prototype to show a proof-of-concept of OpenPET imaging. Two detector rings of 110 mm diameter and 42 mm axial length were placed with a gap of 42 mm. The basic imaging performance was confirmed through phantom studies; the open imaging was realized at the cost of slight loss of axial resolution and 24% loss of sensitivity. For a proof-of-concept of PET image-guided radiation therapy, we carried out the in-beam tests with (11)C radioactive beam irradiation in the heavy ion medical accelerator in Chiba to visualize in situ distribution of primary particles stopped in a phantom. We showed that PET images corresponding to dose distribution were obtained. For an initial proof-of-concept of real-time multimodal imaging, we measured a tumor-inoculated mouse with (18)F-FDG, and an optical image of the mouse body surface was taken during the PET measurement by inserting a digital camera in the ring gap. We confirmed that the tumor in the gap was clearly visualized. The result also showed the extension effect of an axial field-of-view (FOV); a large axial FOV of 126 mm was obtained with the detectors that originally covered only an 84 mm axial FOV. In conclusion, our initial imaging studies showed promising performance of the OpenPET.     

Impaired ability to organize information in individuals with autism spectrum disorders and their siblings

Despite rigorous research on disturbances of executive function and social cognition in autism spectrum disorders (ASD), little information has been available concerning higher cognitive functions, such as the ability to focus and associate relevant features to form categories, or 'organizing of information'. The purpose of this study was to investigate this issue by using the Wisconsin Card Sorting Test (WCST) and the Verbal Learning Task (VLT). Cognitive assessments were conducted in 22 individuals with ASD, 14 non-affected siblings, and 15 age-matched control subjects. Overall, individuals with ASD performed significantly worse on the WCST and VLT compared to their siblings and normal control subjects. Although siblings performed generally well on both tasks, they exhibited similar degree of perseverative responses in the WCST compared to the probands. A linear increase of the memory organization score in the VLT was also absent in siblings as well as the ASD group. These results suggest an impaired ability to organize information is one of the cognitive endophenotypes for ASD.     

Apolar surface area determines the efficiency of translocon-mediated membrane-protein integration into the endoplasmic reticulum

Integral membrane proteins are integrated cotranslationally into the membrane of the endoplasmic reticulum in a process mediated by the Sec61 translocon. Transmembrane α-helices in a translocating polypeptide chain gain access to the surrounding membrane through a lateral gate in the wall of the translocon channel [van den Berg B, et al. (2004) Nature 427:36–44; Zimmer J, et al. (2008) Nature 455:936–943; Egea PF, Stroud RM (2010) Proc Natl Acad Sci USA 107:17182–17187]. To clarify the nature of the membrane-integration process, we have measured the insertion efficiency into the endoplasmic reticulum membrane of model hydrophobic segments containing nonproteinogenic aliphatic and aromatic amino acids. We find that an amino acid’s contribution to the apparent free energy of membrane-insertion is directly proportional to the nonpolar accessible surface area of its side chain, as expected for thermodynamic partitioning between aqueous and nonpolar phases. But unlike bulk-phase partitioning, characterized by a nonpolar solvation parameter of 23 cal/(mol·Å²), the solvation parameter for transfer from translocon to bilayer is 6–10 cal/(mol·Å²), pointing to important differences between translocon-guided partitioning and simple water-to-membrane partitioning. Our results provide compelling evidence for a thermodynamic partitioning model and insights into the physical properties of the translocon.     

Analysis of functional responses at G protein-coupled receptors: estimation of relative affinity constants for the inactive receptor state

We describe a modification of receptor theory that enables the estimation of relative affinity constants for the inactive state of a G protein-coupled receptor. Our approach includes the traditional parameters of observed affinity (K(obs)) and efficacy (fraction of ligand-receptor complex in the active state, ε) and introduces the concept of the fraction of the ligand-receptor complex in the inactive state (intrinsic inactivity, ε(i)). The relationship between receptor activation and the ligand concentration is known as the stimulus, and the operational model expresses the response as a logistic function of the stimulus. The latter function includes K(obs) and the parameter τ, which is proportional to ε. We introduce the parameter τ(i), which is proportional to ε(i). We have previously shown that the product, K(obs)τ, of one agonist, expressed relative to that of another (intrinsic relative activity, RA(i)), is a relative measure of the affinity constant for the active state of the receptor. In this report, we show that the product, K(obs)τ(i), of one agonist, expressed relative to that of another (intrinsic relative inactivity, RI(i)), is a relative measure of the affinity constant for the inactive state of the receptor. We use computer simulation techniques to verify our analysis and apply our method to the analysis of published data on agonist activity at the M(3) muscarinic receptor. Our method should have widespread application in the analysis of agonist bias in drug discovery programs and in the estimation of a more fundamental relative measure of efficacy (RA(i)/RI(i)).     

Caspase-independent apoptosis induction of quorum-sensing autoinducer analogs against chronic myeloid leukemia K562

Quorum sensing is defined as the ability of microorganisms to sense their population density via the release of signaling molecules called autoinducers (AIs). Various types of AI analogs were prepared and their antitumor properties against chronic myeloid leukemia (CML) K562 cells were investigated. Two AI analogs induced progressive apoptosis with JNK activation and p21 induction. In addition, this induction of apoptosis is not related to bcr-abl kinase, which sustains CML proliferation. However, the progression of　apoptosis was not inhibited by a caspase family inhibitor. These results suggested that AI analogs could induce caspase-independent apoptosis in CML K562.     

Effect of gambierol and its tetracyclic and heptacyclic analogues in cultured cerebellar neurons: a structure-activity relationships study

The polycyclic ether class of marine natural products has attracted the attention of researchers due to their complex and large chemical structures and diverse biological activities. Gambierol is a marine polycyclic ether toxin, first isolated along with ciguatoxin congeners from the dinoflagellate Gambierdiscus toxicus. The parent compound gambierol and the analogues evaluated in this work share the main crucial elements for biological activity, previously described to be the C28═C29 double bond within the H ring and the unsaturated side chain [ Fuwa , H. , Kainuma , N. , Tachibana , K. , Tsukano , C. , Satake , M. , and Sasaki , M. ( 2004 ) Diverted total synthesis and biological evaluation of gambierol analogues: Elucidation of crucial structural elements for potent toxicity . Chem. Eur. J. 10 , 4894 - 4909 ]. With the aim to gain a deeper understanding of the cellular mechanisms involved in the biological activity of these compounds, we compared its activity in primary cultured neurons. The three compounds inhibited voltage-gated potassium channels (Kv) in a concentration-dependent manner and with similar potency, caused a small inhibition of voltage-gated sodium channels (Nav), and evoked cytosolic calcium oscillations. Moreover, the three compounds elicited a "loss of function" effect on Kv channels at concentrations of 0.1 nM. Additionally, both the tetracyclic and the heptacyclic derivatives of gambierol elicited synchronous calcium oscillations similar to those previously described for gambierol in cultured cerebellar neurons. Neither gambierol nor its tetracyclic derivative elicited cell toxicity, while the heptacyclic analogue caused a time-dependent decrease in cell viability. Neither the tetracyclic nor the heptacyclic analogues of gambierol exhibited lethality in mice after ip injection of 50 or 80 μg/kg of each compound. Altogether, the results presented in this work support an identical mechanism of action for gambierol and its tetracyclic and heptacyclic analogues and indicate a "loss of function" effect on potassium channels even after administration of the three compounds at subnanomolar concentrations. In addition, because gambierol is known to stabilize the closed state of Kv3 channels, the results presented in this paper may have implications for understanding of channel functions and for future development of therapies against ciguatera poisoning and potassium channel-related diseases.     

Infantile neuroblastoma of the urinary bladder detected by hematuria

Malignant tumors of the urinary bladder in infants are extremely rare. Rhabdomyosarcoma is the most likely tumor in this site, whereas neuroblastoma of the urinary bladder is exceedingly uncommon and is not listed as a differential diagnosis for tumors of this site. We present a case of neuroblastoma arising from the dome of the bladder wall, detected by hematuria. Only six cases of neuroblastoma originating from the bladder, including the present case have been reported. Of the cases, five arose from the dome of the bladder wall. In this report, the differential diagnosis of bladder tumors in children is discussed. A diagnosis of neuroblastoma should be taken into consideration, especially in the case of tumors arising from the dome of the bladder wall despite an uncommon location.     

Dual-energy perfusion CT of non-diseased lung segments using dual-source CT: correlation with perfusion SPECT

Purpose

To determine the utility of dual-energy perfusion CT (DEpCT) of non-diseased lung segments, using dual-source CT, in comparison with perfusion single-photon emission computed tomography (SPECT).

Materials and methods

28 patients (18 male and 10 female; mean age 63 years; age range 18–86 years) underwent DEpCT and SPECT within a 3-day interval. The presence and location of perfusion defects in each segment of the lungs were evaluated.

Results

Perfusion defects were noted in 7 of 361 segments (1.9 %) by DEpCT and in 19 of 361 segments (5.3 %) by perfusion SPECT. DEpCT was in good agreement with perfusion SPECT for 338 of 361 segments (93.6 %). Intraobserver agreement was also good, ranging from 93.4 to 93.6 % (κ = 0.64–0.75, p < 0.01).

Conclusion

For non-diseased lung segments, DEpCT correlated well with SPECT.