Inversion symmetry breaking induced triply degenerate points in orderly arranged PtSeTe family materials

k paths exactly with [Formula: see text] symmetry allow to find triply degenerate points (TDPs) in band structures. The paths that host the type-II Dirac points in PtSe₂ family materials also have the [Formula: see text] spatial symmetry. However, due to Kramers degeneracy (the systems have both inversion symmetry and time reversal symmetry), the crossing points in them are Dirac ones. In this work, based on symmetry analysis, first-principles calculations, and [Formula: see text] method, we predict that PtSe₂ family materials should undergo topological transitions if the inversion symmetry is broken, i.e. the Dirac fermions in PtSe₂ family materials split into TDPs in PtSeTe family materials (PtSSe, PtSeTe, and PdSeTe) with orderly arranged S/Se (Se/Te). It is different from the case in high-energy physics that breaking inversion symmetry I leads to the splitting of Dirac fermion into Weyl fermions. We also address a possible method to achieve the orderly arranged in PtSeTe family materials in experiments. Our study provides a real example that Dirac points transform into TDPs, and is helpful to investigate the topological transition between Dirac fermions and TDP fermions.

Differentiation of autoimmune pancreatitis with pancreatic carcinoma remains a challenge to physicians

OBJECTIVE

The aim of this study was to summarize the clinical features of autoimmune pancreatitis (AIP) and review the advances in the differential diagnosis with pancreatic carcinoma, thus help to make a correct diagnosis and avoid unnecessary surgery in clinical practice.

METHODS

Five patients diagnosed as AIP in accordance with the HISORt criteria in Zhongshan Hospital, Fudan University from 2008 to 2010 were enrolled in the study. Clinical features were analyzed and related literature was reviewed.

RESULTS

Progressive jaundice and abdominal pain were the most frequent symptoms, as well as weight loss, together with serological changes such as elevation of alkaline phosphatase, γ-glutamyl-transpeptidase and serum bilirubin. Two of them showed high serum immunoglobulin G4 (IgG4) levels. Both focal and diffuse changes were found on computed tomography and magnetic resonance imaging. Two of our patients underwent operation because of a high suspicion of malignant tumor, and steroid therapy was administered to the other three patients diagnosed as AIP. No relapse was observed during the follow-up duration of all the patients.

CONCLUSIONS

Although some recent advances have been made to help the diagnosis of AIP, the differentiation between AIP and pancreatic carcinoma is still a challenge. Clinicians must remember to exclude AIP before making a diagnosis of pancreatic carcinoma.

Global dynamics and stochastic resonance of the forced FitzHugh-Nagumo neuron model

We have analyzed the responses of an excitable FitzHugh-Nagumo neuron model to a weak periodic signal with and without noise. In contrast to previous studies which have dealt with stochastic resonance in the excitable model when the model with periodic input has only one stable attractor, we have focused our attention on the relationship between the global dynamics of the forced excitable neuron model and stochastic resonance. Our results show that for some parameters the forced FitzHugh-Nagumo neuron model has two attractors: the small-amplitude subthreshold periodic oscillation and the large-amplitude suprathreshold periodic oscillation. Random transitions between these two periodic oscillations are the essential mechanism underlying stochastic resonance in this model. Differences of such stochastic resonance to that in a classical bistable system and the excitable system are discussed. We also report that the state of the basin of attraction has a significant effect on the stability of neuronal firings, in the sense that the fractal basin boundary of the system enhances the noise-induced transitions.

Stereoselective steady state disposition and action of propafenone in Chinese subjects

AIMS

To investigate the steady state disposition and action of racemic propafenone and its enantiomers and the potential for an enantiomer-enantiomer interaction in Chinese subjects.

METHODS

Eight healthy male Chinese individuals received in a double-blind, randomized, cross-over study racemic propafenone (150 mg every 6 h), (S)-, and (R)-propafenone (150 mg each every 6 h) and placebo orally for 4 days. During the last dosing interval the plasma concentrations of both enantiomers of propafenone were measured and ECG, blood pressure (MAP) and heart rate were monitored.

RESULTS

Whereas the apparent elimination half-life (t1/2,z), mean residence time (MRT) and time to reach peak concentrations (tmax) of (S)- and (R)-propafenone were similar and independent of the administered agent, significant differences were observed in the apparent oral clearance (CLO) of the enantiomers. During dosing with racemic propafenone CLO of (S)- and (R)-propafenone averaged (+/-s.d.) 1226+751 and 1678+625 ml min(-1), respectively (P=0.024). Following the administration of the pure enantiomers CLO of (S)-propafenone increased (P= 0.007) to 2028+/-959 ml min(-1) and that of (R)-propafenone was reduced (P= 0.042) to 1318+/-867 ml min(-1). Both enantiomers and the racemate caused about a 10% increase in the QRS duration (P<0.05) and PR-interval (P<0.01) when compared with placebo. The increase in maximum exercise heart rate was significantly (P<0.05) attenuated only at 3 h following the administration of the racemate and the S-enantiomer. MAP and QTC were not affected significantly.

CONCLUSIONS

These data indicate that the stereoselective disposition of propafenone is similar in Chinese and Caucasian subjects (previously published findings), the (R)-enantiomer being cleared more rapidly. A similar enantiomer-enantiomer interaction also occurred. Thus, when the racemate was given, the elimination of (S)-propafenone was impaired and that of the (R)-form accelerated compared with single enantiomer administration. The results indicate that dosage adjustments are probably not required in Chinese patients receiving propafenone.

Inhibitory effect of trapidil on proliferation of cultured rat aortic smooth muscle cells induced by endothelin-1

AIM

To study the effect of trapidil (Tra) on endothelin-1-induced proliferation of cultured rat aortic vascular smooth muscle cells (VSMC).

METHODS

The [3H]TdR incorporation into DNA assay, the number of VSMC, and cell cycle distribution were measured.

RESULTS

Pretreated with endothelin-1 100 nmol.L-1, cell number, [3H]TdR uptake, and cell mitogenic activity increased 134% +/- 23%, 210% +/- 70%, and 86% +/- 18%, respectively. This proliferation was inhibited by Tra 5, 50, 500 mumol.L-1. The inhibitory rates were 12%-48%, 35%-54% and 15%-47%, respectively. Tra did not influence the proliferation of VSMC without endothelin-1 pretreatment.

CONCLUSION

Tra antagonized the proliferation of VSMC induced by endothelin-1.

Inhibitory effect of artemether on proteinase of Schistosoma japonicum

AIM

To study the effect of artemether (Art) on the thio proteinase ("hemoglobinase", Hem) of Schistosoma japonicum.

METHODS

Hem was extracted from S japonicum adults. The inhibitory effect of Art on the activity of Hem to degrade human hemoglobin (Hgb) was examined with UV-photometer at 280 nm, SDS-PAGE and scanning at 600 nm on a chromoscanner.

RESULTS

Human Hgb was degraded at pH 4.0 by the Hem. The activities of Hem preincubated at 37 degrees C with Art 0.14, 1.4, and 14 mmol.L-1, were inhibited by 30.2%, 39.8%, and 45.0%, respectively.

CONCLUSION

Art possesses an inhibitory effect to Hem of S japonicum.

Effects of captopril and nadolol on renal hemodynamics in patients with essential hypertension

The randomized single-blind study was designed to compare the effects of captopril (Cap) and nadolol (Nad) on renal hemodynamics in 60 patients with essential hypertension. They were divided into two groups at random. Cap was given in dosage of 37.5-75 mg/d per os and Nad 40-80 mg/d. The results show that both drugs increase the blood volume distributed to the kidneys from cardiac output (renal blood flow/cardiac output), Cap increasing 10% (P < 0.05) and Nad 8% (P < 0.05). Renal vascular resistance (RVR) is lowered by the two drugs, 13% (P < 0.05) by Cap and 11% (P < 0.05) by Nad. These suggest that both drugs facilitate the maintenance of renal blood circulation in patients with essential hypertension, being beneficial for long-term treatment of hypertension.