Energy Structure and Luminescence of CeF3 Crystals

The results of the calculation of the energy band structure and luminescent research of CeF₃ crystals are presented. The existence of two 5d1 and 5d2 subbands of the conduction band genetically derived from 5d states of Ce³⁺ ions with different effective electron masses of 4.9 m_e and 0.9 m_e, respectively, is revealed. The large electron effective mass in the 5d1 subband facilitates the localization of electronic excitations forming the 4f-5d cerium Frenkel self-trapped excitons responsible for the CeF₃ luminescence. The structure of the excitation spectra of the exciton luminescence peaked at 290 nm, and the defect luminescence at 340 nm confirms the aforementioned calculated features of the conduction band of CeF₃ crystals. The peculiarities of the excitation spectra of the luminescence of CaF₂:Ce crystals dependent on the cerium concentration are considered with respect to the phase formation possibility of CeF₃.     

Medical management of spontaneous celiac artery dissection: case report and literature review

Spontaneous visceral artery dissections are a rare occurrence. Here we report a case of spontaneous celiac artery dissection that was treated without surgery.     

College of American Pathologists Tumor Regression Grading System for Long-Term Outcome in Patients with Locally Advanced Rectal Cancer

BackgroundThe National Comprehensive Cancer Network''s Rectal Cancer Guideline Panel recommends American Joint Committee of Cancer and College of American Pathologists (AJCC/CAP) tumor regression grading (TRG) system to evaluate pathologic response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer (LARC). Yet, the clinical significance of the AJCC/CAP TRG system has not been fully defined.Materials and MethodsThis was a multicenter, retrospectively recruited, and prospectively maintained cohort study. Patients with LARC from one institution formed the discovery set, and cases from external independent institutions formed a validation set to verify the findings from discovery set. Overall survival (OS), disease‐free survival (DFS), local recurrence‐free survival (LRFS), and distant metastasis‐free survival (DMFS) were assessed by Kaplan‐Meier analysis, log‐rank test, and Cox regression model.ResultsThe discovery set (940 cases) found, and the validation set (2,156 cases) further confirmed, that inferior AJCC/CAP TRG categories were closely /ccorrelated with unfavorable survival (OS, DFS, LRFS, and DMFS) and higher risk of disease progression (death, accumulative relapse, local recurrence, and distant metastasis) (all p < .05). Significantly, pairwise comparison revealed that any two of four TRG categories had the distinguished survival and risk of disease progression. After propensity score matching, AJCC/CAP TRG0 category (pathological complete response) patients treated with or without adjuvant chemotherapy displayed similar survival of OS, DFS, LRFS, and DMFS (all p > .05). For AJCC/CAP TRG1–3 cases, adjuvant chemotherapy treatment significantly improved 3‐year OS (90.2% vs. 84.6%, p < .001). Multivariate analysis demonstrated the AJCC/CAP TRG system was an independent prognostic surrogate.ConclusionAJCC/CAP TRG system, an accurate prognostic surrogate, appears ideal for further strategizing adjuvant chemotherapy for LARC.Implications for PracticeThe National Comprehensive Cancer Network recommends the American Joint Committee of Cancer and College of American Pathologists (AJCC/CAP) tumor regression grading (TRG) four‐category system to evaluate the pathologic response to neoadjuvant treatment for patients with locally advanced rectal cancer; however, the clinical significance of the AJCC/CAP TRG system has not yet been clearly addressed. This study found, for the first time, that any two of four AJCC/CAP TRG categories had the distinguished long‐term survival outcome. Importantly, adjuvant chemotherapy may improve the 3‐year overall survival for AJCC/CAP TRG1–3 category patients but not for AJCC/CAP TRG0 category patients. Thus, AJCC/CAP TRG system, an accurate surrogate of long‐term survival outcome, is useful in guiding adjuvant chemotherapy management for rectal cancer.     

On the transmit field inhomogeneity correction of relaxation‐compensated amide and NOE CEST effects at 7 T

High field MRI is beneficial for chemical exchange saturation transfer (CEST) in terms of high SNR, CNR, and chemical shift dispersion. These advantages may, however, be counter‐balanced by the increased transmit field inhomogeneity normally associated with high field MRI. The relatively high sensitivity of the CEST contrast to B₁ inhomogeneity necessitates the development of correction methods, which is essential for the clinical translation of CEST. In this work, two B₁ correction algorithms for the most studied CEST effects, amide‐CEST and nuclear Overhauser enhancement (NOE), were analyzed. Both methods rely on fitting the multi‐pool Bloch‐McConnell equations to the densely sampled CEST spectra. In the first method, the correction is achieved by using a linear B₁ correction of the calculated amide and NOE CEST effects. The second method uses the Bloch‐McConnell fit parameters and the desired B₁ amplitude to recalculate the CEST spectra, followed by the calculation of B₁‐corrected amide and NOE CEST effects. Both algorithms were systematically studied in Bloch‐McConnell equations and in human data, and compared with the earlier proposed ideal interpolation‐based B₁ correction method. In the low B₁ regime of 0.15–0.50 μT (average power), a simple linear model was sufficient to mitigate B₁ inhomogeneity effects on a par with the interpolation B₁ correction, as demonstrated by a reduced correlation of the CEST contrast with B₁ in both the simulations and the experiments.     

Pre‐ to postsleep change in psychophysiological reactivity to emotional films: Late‐night REM sleep is associated with attenuated emotional processing

Rapid eye movement (REM) sleep has been postulated to facilitate emotional processing of negative stimuli. However, empirical evidence is mixed and primarily based on self‐report data and picture‐viewing studies. This study used a full‐length aversive film to elicit intense emotion on one evening, and an emotionally neutral control film on another evening while psychophysiological and experiential responses were measured. Subsequent sleep was monitored polysomnographically, and specific film scenes were presented again on the next morning. Correlation analyses revealed that participants with longer late‐night REM sleep after the aversive film showed higher increase of electrodermal reactivity and less reduction of facial corrugator muscle reactivity to negative film scenes on the next morning. This indicates that REM sleep may be associated with attenuated emotional processing of prolonged and intense emotional stimuli from pre‐ to postsleep.     

Intracerebroventricular infusion of CRF increases extracellular concentrations of norepinephrine in the hippocampus and cortex as determined by in vivo voltammetry

Previous studies have indicated that intracerebroventricular (i.c.v.) infusions of corticotropin-releasing factor (CRF) activate locus coeruleus (LC) noradrenergic neurons and increase the metabolism and extracellular concentrations of norepinephrine (NE) in several brain regions, suggesting increased release. To examine the temporal aspects and mechanism of the presumed release of NE, CRF was infused i.c.v. and the oxidation current was recorded using carbon fiber voltammetric electrodes placed in rat hippocampus or cortex. The CRF (1 μg, i.c.v.) caused a significant increase of oxidation current with a delay of approximately 5 min, and a peak at approximately 35 min. Similar responses were observed in the medial prefrontal cortex. The hippocampal response was markedly attenuated when CRF was infused into rats pretreated with DSP-4 to deplete NE, suggesting that the observed changes in current resulted from oxidation of NE. The increase of NE-like current did not occur when 25 μg alpha-helical CRF_9–41 (ahCRF) was injected immediately before 1 μg CRF, suggesting that the response was mediated by cerebral CRF-receptors. Subcutaneous pretreatment with the ganglionic blocker, chlorisondamine, at a dose of 3 mg/kg had no effect on the voltammetric response to CRF, but a 6 mg/kg dose completely prevented the response. The β-adrenoceptor antagonists, S-propranolol (5 mg/kg), nadolol (5 and 10 mg/kg), and timolol (5 mg/kg) attenuated the NE response to i.c.v. CRF to varying degrees. When chlorisondamine (3 μg) or nadolol (5 μg) were given i.c.v. before the CRF, the hippocampal responses were not blocked. These results suggest peripheral actions of ganglionic and β-adrenergic blockers. We conclude that peripheral autonomic mechanisms, and probably both central and peripheral β-adrenoceptors, contribute to the increased secretion of hippocampal NE in response to i.c.v. CRF.     

Effects of α-adrenoceptor-stimulating drugs on baroreceptor reflexes in conscious cats

The action of some α-adrenoceptor stimulating drugs with a central effect (clonidine, α-methyldopa, reserpine) on baroreceptor reflexes was studied in conscious cats (both in the resting condition and when influenced by emotional tension or electrical stimulation of the hypothalamus). The sedative effect of these drugs was observed simultaneously with bradycardia and the increase of baroreceptor reflexes. Clonidine and reserpine (in 6–24 h after injection) lowered blood pressure while α-methyldopa (40 mg/kg) increased it. Confrontation with a dog or electrical hypothalamic stimulation produced hypertensive reactions and diminished the baroreflexes. All drugs reduced the emotional and hypertensive reactions caused by natural stress situations and restored baroreceptor reflexes. On the other hand, neither clonidine nor α-methyldopa changed the decrease of baroreceptor reflexes caused by electrical hypothalamic stimulation. It is supposed that central α-adrenoceptor stimulating drugs do not influence processes of hypothalamic modulation of baroreceptor reflexes. The increase in baroreflex activity after clonidine, α-methyldopa and reserpine appears to be due to a direct effect of the drugs on the central neurones mediating baroreceptor reflexes and to the tranquillizing action of these drugs.     

Shape and oligomerization state of the cytoplasmic domain of the phototaxis transducer II from Natronobacterium pharaonis

Phototaxis allows archaea to adjust flagellar motion in response to light. In the photophobic response of Natronobacterium pharaonis, light-activated sensory rhodopsin II causes conformational changes in the transducer II protein (pHtrII), initiating the two-component signaling system analogous to bacterial chemotaxis. pHtrII's cytoplasmic domain (pHtrII-cyt) is homologous to the cytoplasmic domains of eubacterial chemotaxis receptors. Chemotaxis receptors require dimerization for activity and are in vivo-organized in large clusters. In this study we investigated the oligomerization and aggregation states of pHtrII-cyt by using chemical cross-linking, analytical gel-filtration chromatography, and small-angle neutron scattering. We show that pHtrII-cyt is monomeric in dilute buffers, but forms dimers in 4 M KCl, the physiological salt concentration for halophilic archaea. At high ammonium sulfate concentration, the protein forms higher-order aggregates. The monomeric protein has a rod-like shape, 202 A in length and 14.4 A in diameter; upon dimerization the length increases to 248 A and the diameter to 18.2 A. These results suggest that under high salt concentration the shape and oligomerization state of pHtrII-cyt are comparable to those of chemotaxis receptors.