Chronic stress accelerates ligature-induced periodontitis by suppressing glucocorticoid receptor-α signaling

Periodontitis is a common chronic inflammatory disease. Recent studies have shown that chronic stress (CS) might modulate periodontal disease, but there are few models of CS-induced periodontitis, and the underlying mechanisms are unclear. The present study established a rat model of periodontitis associated with CS induced by nylon thread ligatures. The severity of periodontitis was evaluated in this model by radiographic and pathological examination. The inflammatory reaction indicated by the elevated serum levels of interleukin (IL)-1β, IL-6 and IL-8 was assessed by enzyme-linked immunosorbent assay. Toll-like receptor-4 (TLR4) and glucocorticoid receptor-α (GR-α) expressions were detected by reverse transcriptase-PCR and western blotting. Open-field tests and serum corticosterone were used to evaluate CS. The results showed that CS induced behavioral changes and increased corticosterone levels of the animals with periodontitis. CS stimulation markedly increased alveolar bone loss, periodontal pocket depth and the number of plaques. It also enhanced the inflammatory reaction. These results suggest that CS accelerated the ligature-induced pathological changes associated with periodontitis. Further analysis of the mechanisms involved showed that GR-α expression was significantly downregulated in periodontal tissues of the animals undergoing CS. Blocking GR-α signaling in lipopolysaccharide and corticosteroid-treated human periodontal ligament fibroblast cells in vitro significantly upregulated the expression of p-Akt (protein kinase B) and TLR4, promoted nuclear factor-κB activity and increased levels of IL-1β, IL-6 and IL-8. This research suggests that CS might accelerate the pathological progression of periodontitis by a GR-α signaling-mediated inflammatory response and that this may be a potential therapeutic target for the treatment of periodontal disease, particularly in patients with CS.

Chronic stress enhances progression of periodontitis via alpha1-adrenergic signaling: a potential target for periodontal disease therapy

This study assessed the roles of chronic stress (CS) in the stimulation of the sympathetic nervous system and explored the underlying mechanisms of periodontitis. Using an animal model of periodontitis and CS, the expression of tyrosine hydroxylase (TH) and the protein levels of the alpha1-adrenergic receptor (alpha1-AR) and beta2-adrenergic receptor (beta2-AR) were assessed. Furthermore, human periodontal ligament fibroblasts (HPDLFs) were stimulated with lipopolysaccharide (LPS) to mimic the process of inflammation. The proliferation of the HPDLFs and the expression of alpha1-AR and beta2-AR were assessed. The inflammatory-related cytokines interleukin (IL)-1beta, IL-6 and IL-8 were detected after pretreatment with the alpha1/beta2-AR blockers phentolamine/propranolol, both in vitro and in vivo. Results show that periodontitis under CS conditions enhanced the expression of TH, alpha1-AR and beta2-AR. Phentolamine significantly reduced the inflammatory cytokine levels. Furthermore, we observed a marked decrease in HPDLF proliferation and the increased expression of alpha1-ARfollowing LPS pretreatment. Pretreatment with phentolamine dramatically ameliorated LPS-inhibited cell proliferation. In addition, the blocking of alpha1-ARsignaling also hindered the upregulation of the inflammatory-related cytokines IL-1beta, IL-6 and IL-8. These results suggest that CS can significantly enhance the pathological progression of periodontitis by an alpha1-adrenergic signaling-mediated inflammatory response. We have identified a potential therapeutic target for the treatment of periodontal disease, particularly in those patients suffering from concurrent CS.

Analysis and solutions on issues in auto-scan spectrophotometer’s verification / 中国医学装备

Objective:Spectrophotometer is a device to be verified obligatory in hospital. This article introduced some techniques to avoid ordinary mistakes in measurement. Methods:We introduced principle and verification regulation of spectrophotometer. Such methods as parameter configuration, proper maintenance can reduce our mistakes. Results: This article analyzed some common problems in measurement and also offered solutions. Conclusion: In the measurements of spectrophotometers, because the operators have less spectrophotometer operation experience, they often get inaccurate data which lead to an error. Conclusion: To avoid these mistakes, strictly regulate operations in spectrophotometer’s verification and proper routine maintenance are necessary.

MAPK mediates cardiac myocyte survival promoted by CT-1 in rats / 基础医学与临床

Objective Cardiac muscle cells play a critical role in maintaining normal function of the heart.Cardiotrophin-1(CT-1),a potent cardiac survival factor,is capable of inhibiting apoptosis or promoting survival in cardiomyocytes.To elucidate the mechanism of CT-1 promoting cardiac myocyte survival in cultured neonatal rat cardiomyocytes.To explore the potential signaling pathway that might be responsible for this effect.Methods We examined the cardiac myocyte survival effect of CT-1 in cultured neonatal rat cardiomyocytes.The cardiomyocytes were stained [3-(4,5-dimethyl-thiaziazol-2-yl)-2-5-diphenyltetrazolium bromide,MTT] and the counted.Results The survival rate of cardiac myocytes was increased by CT-1 in a dose-dependent manner(10-10～10-7 mol/L) and in a time-dependent manner(1～4 d,10-8 mol/L) in cultured neonatal rat cardiomyocytes.Pretreatment of PD098059(5?10-5mol/L),a MAPK blocker,decreased significantly survival rate of cardiac myocytes by promoted CT-1.The phorbol 12-myristate 13-acetate(PMA)(10-5mol/L),a PKC activator,increased significantly this effect of CT-1,but inhibited significantly by MAPK blocker PD098059.Conclusion CT-1 is a potent factor of promoting cardiac myocyte survival,and increase significantly survival rate of cardiac myocytes in a dose-dependentand a time-dependent manner in cultured neonatal rat cardiomyocytes.The MAPK signaling pathway mediates CT-1 induced cardiac myocyte survival.PKC signaling molecule may be a upstream signaling transduction pathway which cascades of MAPK in CT-1 induced cardiac myocyte survival.

Analysis of the EEG information of rats epileptic model using unstable periodic orbits / 生物医学工程学杂志

In order to further research into the EEG information of rats epileptic model, we applied different nonlinear dynamic methods. After having analyzed the EEG signal of rat falling sickness by means of approximate entropy and correlation dimension, we adopted a the new method, unstable periodic orbits, which was used to analyze complex activity of neurons system to look for the change regularity of change in the EEG signal in the whole course of rat's falling sickness. We found period 1 orbits and period 2 orbits to be statistically significant in the data of ictal time of epilepsy. At the same time, we found period 1 orbits to be statistically significant in the data of preictal time of epilepsy.

Changes in electroencephalogram in rat epilepsy model via nonlinear dynamical approach / 中国组织工程研究

BACKGROUND: The dynamic characteristics of electroencephalogram (EEG) include a decrease in the chaotic dimension, the correlation dimen sion, the Lyapunov exponent, the chaotic complexity, the freedom of EEG and an enhanced synchronization and periodicity of the EEG from several minutes to tens of minutes before epileptic seizures. All these characteristics prefigure the forthcoming seizures. Some studies have proven that the non linear dynamical system can be used as a feasible approach to explore the potential variables for describing the chaos portrait of EEG. OBJECTIVE: To analyze the electric characteristics of EEG signal in the epileptic seizures in rat model by investigating the nonlinear dynamical variables, such as the approximate entropy (ApEn) and correlation dimen sion. DESIGN: Observational and experimental study based on animals. SETTING: Department of Medical Engineering, Department of Gastroen terology, Second Artilleryman General Hospital of Chinese PLA; Department of Physics, Faulty of Biomedical Engineering, Fourth Military Medical Uni versity of Chinese PLA. MATERIALS: From September 2001 to January 2002, this study was conducted at the Complexity Laboratory of the Biomedical Department of the Fourth Military Medical University of Chinese PLA. Six male SD rats,weighing 150- 200 g, were selected.INTERVENTIONS: After intraperitoneal injection of chloral hydrate (0. 5 mL), the male SD rats were deeply anesthetized. When their EEG signal became stable, bemegride injection was diluted at 1:1 with saline and was given on a volume of 0.5 mL to the rats intraperitoneally. After a while,the epileptic seizures started marked by a spasm with a deep roar. The entire epileptic seizures were recorded. According to the shape of EEG waves and the corresponding symptoms of the rats during their seizures, data of the four phases, referring to normal condition, preictal phase, ictal phase and postictal phases of epileptic seizures, were selected for nonlinear analysis. The variations of the ApEn and the correlation dimension were calculated.MAIN OUTCOME MEASURES: In the four phases of the seizures, before seizures, preictal phase, ictal phase and postictal phases, the changes in the ApEn and correlation dimension were observed.RESULTS: All the 6 rats entered the statistical procedure. During epilepsy, the ApEn and correlation dimension of the EEG signal in ictal phases (0. 447 ±0. 126, 2. 166 ±0. 377) decreased significantly while those in preictal phases(0. 807 ±0. 182, 4. 773 ±0. 319) and postictal phases (1. 241 ±0. 125, 6. 042 ±0. 373) (t = -3. 984to 17. 902, P ＜0. 01). The ApEn and the correlation dimension of the EEG signal in preictal and ictal phases had significant difference with those observed under normal conditions (1.313 ± 0. 090, 6. 405 ± 0. 694) (t = -5. 228 to 12. 740, P ＜ 0. 01 ).CONCLUSION: The changes in ApEn and correlation dimension showed by nonlinear dynamical approach in this study reflect the characteristics of EEG signals in preictal time, ictal time and postictal timeof the epileptic seizures and the differences among them. Additionally, they also reveal the laws in the changes of the complex ictal EEG signal.

Discussion on check & acceptance of medical equipment / 医疗卫生装备

The check & acceptance is an important component of medical equipment management,and it is the key to guarantee the quality,application and safety of medical equipment.In this article,we introduce some methods to check & accept the medical equipment according to our own experience.

Nonlinear analysis on the EEG information of rat epileptic model / 生物医学工程学杂志

The aim of this study was to develop a new method of epileptic prediction using nonlinear dynamic theory. When rat was falling sickness, its EEG was researched by using approximate entropy and correlation dimension. The results showed the approximate entropy and correlation dimension during epileptic seizure are obviously lower than those before seizure and after seizure. The span of time before seizure is a special phase. Before the seizure symptom appeared, the complexity of EEG had begun declining. Thus, the outbreak of epilepsy could be predicted in short time using nonlinear dynamic methods.

Discussion on How to Equip Backup Power for Medical Equipment in Hospital / 医疗卫生装备

Backup power should be equipped in hospitals in order to prevent the medical risks.At present,there are three choices of the backup power including UPS,EPS and diesel generator.The principles of three backup powers are introduced.Methods for equipping backup power are also discussed to guarantee the security of power supply system for emergency medical equipment.

The design of a cardiac monitor able to measure QRS parameter / 医疗卫生装备

Based an ordinary ECG, this paper deals with a portable monitor system able to measure the values of QRS. With a liquid crystal display (LCD), this monitor is suitable for China's special condition. Besides developing the overall scheme of the system, this paper also performs the designs for the hardware and software. The 80196 single chip microcomputer is taken as the central microprocessor to process and analyze the realtime ECG signals. With the performances of the ordinary monitor, this monitor also has such functions as arrhythmia analysis, HRV analysis, alarm, self-freeze and paper self-advance. Being convenient to carry, this monitor can be powered by alternate current (AC) or direct current (DC). Stability, low power consumption and low cost are emphasized on in the hardware design and structured design is applied to the software design. With a high versatility and a low cost, this monitor has a valuable reference to China's monitor.

HDCT and Its Clinical Application / 医疗卫生装备

The number of detector rows has been the focus of the CT development for decades.During the last decade,CT development has reached a threshold which is represented by coverage,mechanics,resolution and dosage.In order to break this bottleneck,two further development directions have been shown in recent years,of which,one is to increase the number of the detector rows,and the other is to revolutionize the material of detector to explore new clinical applications.Generally,HDCT opens the new era for whole CT modality,bringing the radiologists the high-resolution image,spectral imaging,large coverage and low dosage application.