Bi-stability of mixed states in neural network storing hierarchical patterns

We discuss the properties of equilibrium states in an autoassociative memory model storing hierarchically correlated patterns (hereafter, hierarchical patterns). We will show that symmetric mixed states (hereafter, mixed states) are bi-stable on the associative memory model storing the hierarchical patterns in a region of the ferromagnetic phase. This means that the first-order transition occurs in this ferromagnetic phase. We treat these contents with a statistical mechanical method (SCSNA) and by computer simulation. Finally, we discuss a physiological implication of this model. Sugase et al. analyzed the time-course of the information carried by the firing of face-responsive neurons in the inferior temporal cortex. We also discuss the relation between the theoretical results and the physiological experiments of Sugase et al.Comment: 18 pages, 6 figure

Radiation-induced Liver Injury after 3D-conformal Radiotherapy for Hepatocellular Carcinoma: Quantitative Assessment Using Gd-EOB-DTPA-enhanced MRI

Focal liver reaction (FLR) appears in the hepatobiliary-phase images of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-enhanced MRI) following radiotherapy (RT). We investigated the threshold dose (TD) for FLR development in 13 patients with hepatocellular carcinoma (HCC) who underwent three-dimensional conformal radiotherapy (3D-CRT) with 45 Gy in 15 fractions. FLR volumes (FLRVs) were calculated based on planning CT images by referring to fused hepatobiliary-phase images. We also calculated the TD and the irradiated volumes (IVs) of the liver parenchyma at a given dose of every 5 Gy (IVdose) based on a dose-volume histogram (DVH). The median TD was 35.2 Gy. The median IV20, IV25, IV30, IV35, IV40, and IV45 values were 371.1, 274.8, 233.4, 188.6, 145.8, and 31.0 ml, respectively. The median FLRV was 144.9 ml. There was a significant difference between the FLRV and IV20, IV25, and IV45 (p<0.05), but no significant differences between the FLRV and IV30, IV35, or IV40. These results suggest that the threshold dose of the FLR is approx. 35 Gy in HCC patients who undergo 3D-CRT in 15 fractions. The percentage of the whole liver volume receiving a dose of more than 30-40 Gy (V30-40) is a potential candidate optimal DVH parameter for this fractionation schedule

Identification and characterization of adenosine A1 receptor-cAMP system in human glomeruli

Identification and characterization of adenosine A1 receptor-cAMP system in human glomeruli. Although adenosine is known to affect renal function through stimulating adenosine receptors, little is known about A1 receptors in human glomeruli. Thus, we attempted to identify the adenosine A1 receptor-cyclic AMP (cAMP) system in human glomeruli. Normal renal cortical tissues were obtained at nephrectomy of patients with renal cell carcinoma. Glomeruli were isolated using a graded sieving method or dissected manually under a stereomicroscope. Radioligand binding assay using 2-chloro-N-[3H] cyclopentyl adenosine ([3H]CCPA, an A1 agonist ligand) was performed at 30°C for 90 minutes. Cyclic AMP (cAMP) produced in glomeruli was measured after incubation with different concentrations of N6-cyclohexyladenosine (CHA; A1 agonist) and a phosphodiesterase inhibitor. The specific binding was saturated within 60 minutes and reversible by adding 1 mM of theophylline. Scatchard plot analysis revealed a single class of binding site (Kd = 1.78 ± 0.21 nM, Bmax = 271.7 ± 35.8 fmol/mg protein). The specific binding was inhibited dose-dependently by various agents in an order suggesting A1 receptor specificity. CHA inhibited the production of cAMP in microdissected human glomeruli. This inhibitory effect was antagonized by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; A1 antagonist). This is the first study revealing the presence of the A1 receptor-cAMP system in human glomeruli using a radioligand binding assay method and by measuring the cAMP production

Ischemic preconditioning prevents ischemia-induced beta-adrenergic receptor sequestration

Abstract Preconditioning enables endogenous protection to repeated myocardial ischemia. However, the effect of preconditioning on beta1 adrenergic receptor (AR) signal remains controversial. We have recently developed receptor assay system using whole cells, in which overexpressed cell surface beta ARs can be readily quantitated without disrupting the cell. Using this technique, we examined the effects of chemical/metabolic ischemia on the beta1 AR sequestration and adenylyl cyclase activity. Isoproterenol treatment, but not forskolin treatment, of HEK293T cells overexpressing beta1 ARs led to a rapid decrease (within 2 hours) in the number of the cell surface receptor, which was negated in the presence of concanavalin A. Similarly, treatment of cells with potassium cyanide and 2-deoxy-D-glucose (chemical/metabolic ischemia) induced similar receptor sequestration. When isoproterenol was superimposed on chemical/metabolic ischemia, the degree of sequestration became greater. However, when cells were pre-exposed to potassium cyanide on the preceding day (chemical preconditioning), the sequestration induced by either isoproterenol or chemical/metabolic ischemia was attenuated. Adenylyl cyclase catalytic activity as assessed by stimulation with forskolin was decreased by chemical/metabolic ischemia but fully recovered after 24 hours, suggesting that chemical/metabolic ischemia treatment did not alter cell viability. Putting together, chemical/metabolic ischemia induced beta1 AR sequestration in a similar manner to isoproterenol. In addition, preconditioning prevented the beta1 AR sequestration induced by both isoproterenol and chemical/metabolic ischemia. Pre-conditioning may play a role in preserving the cell surface beta ARs by inhibiting the sequestration that is usually induced by an ischemic event or beta adrenergic stimulation

Disruption of type 5 adenylyl cyclase negates the developmental increase in Gαolf expression in the striatum

AbstractThe two stimulatory G protein α subunits, Gαs and Gαolf, activate adenylyl cyclase in a similar way. We examined whether type 5 adenylyl cyclase knockout, the major striatal isoform, can differentially and/or developmentally change the expression of these G proteins in the striatum. Gαs and Gαolf expressions at birth were unaffected in knockouts, which, however, demonstrated a blunted developmental increase in Gαolf, but not Gαs. Adenylyl cyclase activity was unaffected at birth, but subsequently became lower in knockouts. These findings suggest that type 5 adenylyl cyclase does not contribute to striatal cAMP signaling at birth. However, it may play an important role in developmental changes in the expression of Gαolf, but not Gαs

Timing-adjusted iron dosing enhances erythropoiesis-stimulating agent-induced erythropoiesis response and iron utilization

Abstract Background We recently demonstrated, using an index of recently synthesized hemoglobin, reticulocyte hemoglobin (Ret-Hb), that iron administration remarkably improves hemoglobin (Hb) synthesis during the period of high activation of erythropoiesis induced by the administration of a continuous erythropoietin receptor activator (CERA). We aimed to investigate whether repetition of iron dosing sustains effective erythropoiesis and suppresses iron storage. Methods In a 3-month comparison of monthly CERA administration, 104 hemodialysis patients were randomized into two groups that received 40 mg iron intravenously 3 times; the first-week iron group [n = 51], given iron in the first week after CERA administration, during the period of high activation of erythropoiesis, and the third-week iron group [n = 53], given iron in the third week at the time of mild erythropoiesis activation. Results Initial mean CERA dosages were 123.5 ± 67.5 μg/month and did not differ between the groups. Hb levels were not different between the groups throughout the study. One-week increases in Ret-Hb levels after CERA administration were higher, during the first and the third month, in the group given iron in the first week compared with the third-week iron group (241.9 ± 63.3 vs. 196.2 ± 82.8 mg/dL, P = 0.004; 227.2 ± 83.5 vs. 187.9 ± 88.7 mg/dL, P = 0.037, respectively). The increase in ferritin levels was suppressed 3 months later in the first-week iron group compared with that of the third-week iron group (22.3 ± 64.0 vs. 69.0 ± 76.6 ng/mL, P = 0.002). Hepcidin levels decreased 1 week after CERA administration in both groups and were not different between the groups. Conclusions Timing-adjusted iron administration increased the levels of recently produced Hb and iron utilization and suppressed the ferritin levels. The iron administration timing deserves consideration when optimizing the efficiency of erythropoiesis-stimulating agents in patients undergoing hemodialysis. Trial registration UMIN000016375 . Registered 29 January 2015