The role of stress in the mosaic of autoimmunity: An overlooked association

Stress is defined as the pscyophysiological reaction in which the steady state is disturbed or threatened. Stress is not always perceived as a negative response. Stress results when environmental demands exceed an individuals' adaptive capacities. Autoimmune diseases are heterogeneous group of chronic diseases which occur secondary to loss of self antigen tolerance. The etiopathogenesis of autoimmune disease is uncertain. Genetic factors as well as environmental factors appear to interplay, leading to a cascade of events resulting in disease onset. Stress has been postulated to play a role in disease onset in the genetically susceptible patients. During the stress response, catecholamines and glucocorticoids are released from locus coeruleus and adrenal gland. These biomolecules exert control over various immune cells in the innate and adaptive arms of the immune system, thereby altering the cytokine profile released. The increase of IL-4 promotes T-helper 2 (T_h2) cell differentiation, while the decrease in IL-12 and the increased IL-10 production reduce the number of T-helper 1 (T_h1) cells. The relationship between stress and autoimmune diseases is intricate. Stress has been shown to be associated with disease onset, and disease exacerbations in rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, multiple sclerosis, Graves' disease as well as other autoimmune conditions. In certain conditions such as psoriasis, stress has been implicated in delaying lesion clearance upon the application of standard treatment regimes. Finally, psychological therapy and cognitive behavioral therapy aimed to reduce stress levels was shown to be effective in influencing better outcomes in many autoimmune diseases. The purpose of this paper is to closer inspect the clinical evidence regarding the role of stress on influencing the various aspects of disease entities.     

High trait emotional intelligence in men: Beneficial for perceived stress levels but disadvantageous for the physiological response to acute stressors?

This study examined the relationship between trait emotional intelligence (EI) and stress in 110 male employees. Particularly, the association between trait EI and perceived chronic stress, occupational stress, and the physiological stress response was examined. Trait EI, perceived chronic stress, and occupational stress levels were assessed via questionnaires. The physiological stress response was measured by means of salivary free cortisol and heart rate variability (HRV) in response to the Trier Social Stress Test for Groups. Consistent with previous findings, men with high trait EI showed significantly lower perceived chronic and occupational stress levels than men with low trait EI. However, men with high trait EI also showed significantly higher cortisol reactivity than their low trait EI counterparts. Similarly, HRV in men with high trait EI appeared to be lower than in men with low trait EI but HRV differences between groups were not significant. Our findings suggest that trait EI might play a critical role in the stress regulation process but due to the cross‐sectional design of the study no causal conclusions can be drawn. Experimental studies need to explore further whether and how trait EI affects psychological and physiological stress responses.     

Positive social interaction offsets impact of low socioeconomic status on stress

Background

Stress is associated with unhealthy behaviors and premature morbidity and mortality, especially among those of low socioeconomic status (SES). Clarifying the roles of stress-related risk and protective factors can guide interventions designed to reduce stress and improve health among socioeconomically disadvantaged populations.

The effect of ferrule height on stress distribution within a tooth restored with fibre posts and ceramic crown: A finite element analysis

ObjectivesTo evaluate via finite element analysis the effect of different ferrule heights on stress distribution within each part of a maxillary first premolar (MFP) restored with adhesively luted glass fiber-reinforced resin (GFRR) posts and a ceramic crown.MethodsThe solid models consisted of MFP, periodontal ligament and the corresponding alveolar bone process. Four models were created representing different degrees of coronal tissue loss (0 mm, 1 mm, 2 mm and 3 mm of ferrule height). First set of computing runs was performed for in vivo FE-model validation purposes. In the second part, a 200-N force was applied on the buccal cusp directed at 45° to the longitudinal axis of the tooth. Principal stresses values and distribution were recorded within root, abutment, posts, crown and related adhesive interfaces.ResultsAll FE-models showed similar stress distribution within roots, with highest stress present in the chamfer area. In composite abutments higher stress was observed when no ferrule was present compared to ferruled FE-models. Stress distribution within crown and GFRR posts did not differ among the models. Stress values at the adhesive interfaces decreased with increasing ferrule height.SignificanceThe stress state at abutment-crown and post-root interfaces was very close to their strength, when ferrule was not present. Similarly, higher ferrule produced more favorable stress distribution at post-abutment and abutment-root interfaces. Endodontically treated teeth with higher ferrule exhibit lower stress at adhesive interfaces that may be expected to lower the probability of clinical failure.     

Reduced polymerization stress of MAPO-containing resin composites with increased curing speed,degree of conversion and mechanical properties

Objectives

The degree and rate of photopolymerization in resin-based dental composites will significantly affect polymer network formation and resultant material properties that may determine their clinical success. This study investigates the mechanical properties, the generation of stress from polymerization, tooth cusp deflection and marginal integrity of experimental resin composites that contain different photoinitiators.

Methods

Experimental light-activated resin composites (60 vol% particulate filled in 50/50 mass% bis-GMA/TEGDMA) were formulated using a monoacylphosphine oxide (MAPO) photoinitiator and compared with a conventional camphoroquinone (CQ)-based system. Similar radiant exposure was used (18 J cm⁻²) for polymerization of each material although the curing protocol was varied (400 mW cm⁻² for 45 s, 1500 mW cm⁻² for 12 s and 3000 mW cm⁻² for 6 s). Degree and rate of polymerization was calculated in real-time by near infrared spectroscopy and the generation of stress throughout polymerization measured using a cantilever beam method. Flexural strength and modulus were acquired by three-point bend tests. Standardized cavities in extract pre-molar teeth were restored with each material, the total cuspal deflection measured and post-placement marginal integrity between the tooth and restoration recorded.

Results

Generally, MAPO- exhibited a significantly higher degree of conversion (72 ± 0.8 to 82 ± 0.5%) compared with CQ-based materials (39 ± 0.7 to 65 ± 1.6%) regardless of curing protocol (p < 0.05) and MAPO-based materials exhibited less difference in conversion between curing protocols. CQ-based materials exhibited between ∼85 and 95% of the maximum rate of polymerization at <15% conversion, whereas MAPO-based RBCs did not approach the maximum rate until >50% conversion. Higher irradiance polymerization had a significant deleterious effect on the mechanical properties of CQ-based materials (p < 0.05) whereas MAPO-based materials exhibited increased strength and modulus and were less affected by the curing method. Total cuspal deflection in restored extracted teeth was higher for CQ- compared with MAPO-based materials cured at the lowest irradiance curing protocol (12.9 ± 4.0 and 8.3 ± 1.5 μm) and similar at 3000 mW cm⁻¹ for 6 s (10.1 ± 3.5 and 9.0 ± 1.5 μm). A significant decrease in marginal integrity was observed for CQ-based RBCs cured at high irradiance for short exposure time compared with that of the MAPO-based RBC cured using a similar protocol (p = 0.037).

Significance

Polymer network formation dictates the final properties of the set composite and the use MAPO photoinitiators may provide an effective restorative material that exhibits higher curing speeds, increased degree of conversion, strength and modulus without compromise in terms of polymerization stress and marginal integrity between tooth and restoration.     

Influence of thermal gradients on stress state of veneered restorations

Objectives

To assess transient and residual stresses within the porcelain of veneered restorations (zirconia and metal) as a result of cooling rate and porcelain thickness.

Methods

Porcelain-on-zirconia (PZ) and porcelain-fused-to-metal (PFM) crowns were fabricated with 1 or 2 mm of porcelain. Thermocouples were attached both internally and externally to the crowns to record transient temperatures. For fast cooling, the furnace was opened after the holding time and switched off. Slow cooling was accomplished by opening the furnace at 50 °C below the glass transition temperature (T_g) of the material. An axially symmetric FEA model simulated thermal stresses. Time-dependent temperature equations from thermocouple readings were set as boundary conditions. Framework materials and the porcelain below T_g were considered to behave elastically. Visco-elastic behavior was assumed for porcelain above the T_g modeling properties as dependent on cooling rate.

Results

Differences in residual stress were found for fast and slow cooled PZ and PFM crowns. Significant transient stress waves were observed within the porcelain when fast cooling through T_g. They are believed to be related to non-uniform volumetric changes originated from thermal gradients. Results were confirmed by modeling and physical testing of crowns containing a defect.

Significance

Residual stresses do not distinguish PZ from PFM. High magnitude transient stresses observed within the porcelain during fast cooling may explain clinical fractures involving internal defects. Stress waves may also originate internal micro-cracking which could grow under function. Therefore, slow cooling, especially for all-ceramic crowns with thick porcelain, is important to prevent thermal gradients and high-magnitude transient stresses.     

Three dimensional finite element analysis of the stress distribution around the mandibular posterior implant during non-working movement according to the amount of cantilever

PURPOSE

In case of large horizontal discrepancy of alveolar ridge due to severe resorption, cantilevered crown is usually an unavoidable treatment modality. The purpose of this study was to evaluate the clinical criteria for the placement of the aforementioned implant crown.

MATERIALS AND METHODS

The mandible model with 2 mm thick cortical bone and cancellous bone was fabricated from CT cross-section image. An external connection type implant was installed and cantilevered crowns with increasing offset of 3, 4, 5, 6, and 7 mm were connected. Vertical load and 30° oblique load of 300 N was applied and stress around bone and implant component was analyzed. A total of 14 cases were modeled and finite element analysis was performed using COSMOS Works (Solid works Inc, USA).

RESULTS

As for the location of the vertical load, the maximum stress generated on the lingual side of the implant became larger according to the increase of offset distance. When the oblique load was applied at 30°, the maximum stress was generated on the buccal side and its magnitude gradually decreased as the distance of the offset load increased to 5 mm. After that point, the magnitude of implant component''s stress increased gradually.

CONCLUSION

The results of this study suggest that for the patient with atrophied alveolar ridge following the loss of molar teeth, von-Mises stress on implant components was the lowest under the 30° oblique load at the 5 mm offset point. Further studies for the various crown height and numbers of occusal points are needed to generalize the conclusion of present study.     

经阴道无张力尿道中段悬吊术治疗女性压力性尿失禁28例围术期护理体会

目的:探讨经阴道无张力尿道中段悬吊术(TVT)治疗女性压力性尿失禁的护理方法。方法:回顾性分析行TVT手术治疗的28例女性压力性尿失禁患者的护理资料,术前做好充分准备,术后加强对伤口的护理,密切观察病情变化,观察有无排尿困难、出血、感染等并发症。结果:本组24例术后排尿功能恢复良好,4例因膀胱不稳定或感染发生排尿困难,经持续导尿、膀胱训练及药物治疗后均恢复排尿功能。结论:对女性压力性尿失禁患者行TVT手术,并给予术前充分准备和术后严密观察护理,可减少术后并发症的发生,促进患者康复。     

天鹅记忆接骨器对骨折愈合中皮质骨胶原构筑的影响

目的 探讨天鹅记忆接骨器（SMC）对实验性骨折愈合中皮质骨胶原构筑的影响。方法 20只新西兰大白兔双侧肱骨干截骨后，随机选取一侧用SMC固定，对侧用4孔动力加压接骨板（DCP）固定，分别在术后2、4、8、16、32周时各处死4只动物取材，扫描电镜观察固定段皮质骨胶原构筑的变化。结果 SMC组在整个固定过程中，皮质骨结构与正常对照组相比无明显变化。而DCP组术后4周，胶原排列出现稀疏，局部有小吸收陷窝形成；术后8周，胶原排列紊乱，且有多个吸收腔形成；术后16周，DCP组胶原纤维出现中断；术后32周，DCP组骨质松化更加明显。结论SMC具有材料特性和几何构型上的优势，不仅对骨干不产生应力遮挡效应，而且对骨血供损伤也非常轻，故能有效防止骨质疏松的发生。     

Predictors of psychosocial adaptation among people with spinal cord injury or disorder

OBJECTIVE: To examine the influence of disability-related medical and psychologic variables on psychosocial adaptation to spinal cord injury or disorder (SCI/D). DESIGN: A structural equation modeling design linking 3 sets of predictive variables to an outcome measure of adaptation. SETTING: Two outpatient SCI clinics (1 veteran, 1 civilian) in Texas. PARTICIPANTS: Veterans (n=181) and civilians (n=132) with SCI/D. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The adaptation outcome was measured by 2 subscales (acknowledgment, adjustment) of the Reactions to Impairment and Disability Inventory (RIDI) and by the Quality of Life Scale. The predictive variables were measured by a demographic questionnaire, 3 subscales (intrusion, re-experiencing, hyperarousal) of the Purdue Posttraumatic Stress Disorder-Revised scale, the McMordie-Templer Death Anxiety Scale, and 3 subscales (anxiety, depression, denial) of the RIDI. RESULTS: Goodness-of-fit indices suggested that a revised model of adaptation was a moderately good fit to the data. The revised model of adaptation indicated that there were medium total effects (direct plus indirect) on psychosocial adaptation by 2 latent variables (disability severity and impact, negative affectivity) and small total effects on psychosocial adaptation by disengagement coping. The latent factor of disengagement coping had the strongest direct effect on adaptation (although not statistically significant). Disability severity and impact had medium indirect effects and negative affectivity had small indirect effects on psychosocial adaptation. All of the aforementioned effects had a negative coefficient. CONCLUSIONS: Negative emotional responses (eg, depression, anxiety) to SCI/D, disengagement-type coping (eg, disability denial, avoidance), and the severity and impact of disability were related to lower levels of adaptation to SCI/D.