Magnetic resonance imaging relaxation time measurements of the placenta at 1.5 T

Placental insufficiency is a major cause of fetal growth restriction (FGR) and accumulating evidence indicates several aspects of placental morphology are altered in this condition. MRI provides quantitative indices that may be used in non-invasive assessment of the human placenta, such as relaxation time measurements, T1 and T2. We hypothesised that placental relaxation times relate to alterations in placental tissue morphology and hence may be useful in identifying the changes associated with FGR. We report on the first phase of testing this hypothesis, in a study of women in normal pregnancy.

Aims

To assess relaxation time measurements in the placenta in normal pregnancy and correlate these with gestational age and stereological analyses of placental morphology following delivery.

Methods

30 women underwent MRI examination (1.5 T) between 20 and 41 weeks gestation. Placental T1 and T2 measurements were acquired from a mid-depth placental region, co-localised to a structural scan. Fixed, wax-embedded sections of these placentas collected at delivery were stained with hematoxylin/eosin and subjected to stereological analysis.

Results

Placental T1 and T2 show a significant negative correlation with gestation, (Pearson correlation p = 0.01, 0.03 respectively). 17 placentas were analysed stereologically. In the group as a whole there was no significant correlation between T1 and T2 and morphological features. However, in a subset of 7 pregnancies scanned within a week of delivery, a significant positive correlation was observed between the fibrin volume density and the ratio of fibrin: villous volume densities and T2 (Spearman correlation p = 0.02, 0.03 respectively).

Discussion

The correlations between placental T1 and T2 and gestation show that these variables are clearly influenced by changes in placental structure. Fibrin might be a key component but further work is needed to fully elucidate the major structural influences on placental T1 and T2.     

Early callus of fractured rib of rat contracts and relaxes ex vivo.

PURPOSE: Wound contraction is an essential process in early soft-tissue repair, yet contraction of callus in fracture repair has not been investigated previously. Fracture callus consists of several cell types, many of which may have the capacity to contract. Accordingly, the purpose of the present study was to (i) determine whether early soft fracture calluses contract and relax ex vivo and (ii) identify and locate the contractile protein, alpha smooth muscle actin (alphaSMA) in callus. METHODS: One non-weight-bearing rib was fractured in adult male rats under anaesthesia and 10 calluses were removed 5, 7 and 9 days later for examination. Force production by calluses was measured using a sensitive force transducer when callus preparations were immersed sequentially in solutions known to either contract or relax smooth muscle preparations. Calluses and unfractured rib were analysed for the presence of alphaSMA using Western Blot and immunohistochemical techniques. RESULTS: When immersed in normal Krebs-Henseleit solution (K-H; pH 7.4, 22 degrees C) 7 callus preparations contracted and 3 relaxed. The force response was phasic (3 calluses) or tonic (7 calluses). Subsequent immersion in Ca(2+)-free K-H resulted in no change in force in 4 calluses, a decrease in force (relaxation) in 3 calluses, and an increase in force (contraction) in 2 calluses when compared to the force in the preceding solution (K-H). The final incubation in a solution having a high [K+] (64 mM) partially relaxed 6 calluses, contracted 3 and produced no change in force in 1 callus compared to the final force of the callus in the Ca(2+)-free solution. Collagen (in the form of rat Achilles tendon), the major structural protein in soft fracture callus, relaxed in K-H and continued to relax during exposure to Ca(2+)-free K-H and to solutions having a high [K+]. Western Blot and immunohistochemical studies detected the presence of alphaSMA in calluses and (in particular) in osteoprogenitor cells of fibrous callus respectively, as well as its absence from unfractured rib. CONCLUSIONS: (i) Early, soft fracture callus is capable of contracting and relaxing, (ii) the responses of callus to K-H, Ca(2+)-free and high [K+] solutions are distinctly different from the responses of smooth muscle preparations reported in the literature, (iii) the cell types in callus, particularly osteoprogenitor cells in uncalcified, collagenous matrix, have an essential contractile protein, alphaSMA, to support the observed contraction and relaxation and (iv) the contraction of soft fracture callus may facilitate fracture repair by creating tension within the callus and drawing the fracture ends together.     

Viscoelastic effects during loading play an integral role in soft tissue mechanics

Viscoelastic relaxation during tensioning is an intrinsic protective mechanism of biological soft tissues. However, current viscoelastic characterization methodologies for these tissues either negate this important behavior or provide correction methods that are severely restricted to a specific viscoelastic formulation and/or assume an a priori (linear) strain ramp history. In order to address these shortcomings, we present a novel finite ramp time correction method for stress relaxation experiments (to incorporate relaxation manifested during loading) that is independent of a specific viscoelastic formulation and can accommodate an arbitrary strain ramp history. We demonstrate transferability of our correction method between viscoelastic formulations by applying it to quasi-linear viscoelastic (QLV) and fully nonlinear viscoelastic constitutive equations. The errors associated with currently accepted methodologies for QLV and fully nonlinear viscoelastic formulations are elucidated. Our correction method is validated by demonstrating the ability of its fitted parameters to predict an independent cyclic experiment across multiple strain amplitudes and frequencies. The results presented herein: (i) indicate that our correction method significantly reduces the errors associated with previous methodologies; and (ii) demonstrate the necessity for the use of a fully nonlinear viscoelastic formulation, which incorporates relaxation manifested during loading, to model the viscoelastic behavior of biological soft tissues.     

Psychosocial approaches to pain management: an organizational framework

Many different psychosocial treatments for pain have been described in the literature. All of these treatments have at least some evidence supporting their efficacy. However, each treatment is based on a theory or model that is most useful only for that particular intervention. An overarching model or framework that includes all of the factors hypothesized to play a role in the effects of these treatments would be useful for (1) understanding the similarities and differences between existing and future psychosocial pain treatments, (2) guiding the psychosocial evaluation of patients with chronic pain, and (3) giving clinicians greater flexibility for including psychosocial interventions that have proven efficacy, but that may not be explained by their preferred (but perhaps limited) model. This article proposes an initial version of such a framework, with the hope that it will increase our understanding of the role that psychosocial factors play in the experience of pain and its negative effects on functioning, and informs future research seeking to identify the common and specific factors associated with psychosocial pain treatments.     

槟榔碱对高糖诱导血管内皮依赖性舒张功能损伤的保护作用

目的 探讨槟榔碱对高糖诱导的内皮依赖性舒张功能损伤的保护作用及其可能的机制.方法 采用离体血管环灌流方法,观察槟榔碱对高糖诱导的大鼠血管内皮依赖性舒张功能损伤的影响以及血管组织中一氧化氮和丙二醛含量以及超氧化物歧化酶活性的影响.同时,观察M受体阻断剂阿托品和一氧化氮合酶抑制剂N-硝基-L-精氨酸甲酯对槟榔碱作用的影响.结果 高糖(44mmol/L)处理组显著降低了乙酰胆碱诱导的大鼠血管内皮依赖性舒张反应,槟榔碱(0.001、0.01和0.1mmol/L)以浓度依赖的方式抑制了高糖诱导的血管内皮依赖性舒张反应损伤.而阿托品和N-硝基-L-精氨酸甲酯取消了槟榔碱的作用.高糖(44mmol/L)处理组显著降低了血管组织中一氧化氮含量和超氧化物歧化酶活性而增加了血管组织中丙二醛含量,槟榔碱(0.1mmol/L)逆转了高糖的这种作用.结论 槟榔碱抑制了高糖诱导的血管内皮依赖性舒张功能损伤,其机制可能与槟榔碱能激动M受体,增加一氧化氮的释放,抑制氧化应激有关.     

Lifestyle alterations for the amelioration of hot flashes

Hot flashes are a common complaint among women as they transition through menopause. This article reviews the evidence of lifestyle alterations for the amelioration of hot flashes including obesity, exercise, smoking, relaxation techniques, and acupuncture. Further randomized controlled trials regarding these lifestyle alterations are needed to determine their full potential benefits regarding hot flashes.     

Localization and Function of Cannabinoid Receptors in the Corpus Cavernosum: Basis for Modulation of Nitric Oxide Synthase Nerve Activity

Background

Anandamide, a proposed endogenous cannabinoid (CB) agonist, has been shown to enhance neurogenic responses in vitro of the rat corpus cavernosal tissue (CC). However, no information is available on the distribution of CB-receptors or effects by anandamide in CC from primates or humans.

Objective

To characterize the distribution of CB-receptor isoforms in the human and primate CC and to investigate the effects of anandamide on isolated CC preparations.

Design, setting, and participants

CC tissue was excised from the crura penis of six rhesus monkeys and five patients. Expression and distribution of CB1 and CB2 receptors were characterized with Western blot analyses and immunohistochemical investigations. The effects of anandamide on isolated CC preparations were analyzed during pharmacologic and nerve-mediated activation of primate tissue in aerated organ baths.

Measurements

The expression and localization of CB1 and CB2 receptors in the primate CC and effects of anandamide on nerve-mediated relaxations and pharmacologically evoked contractions.

Results and limitations

Western blot experiments revealed CB1 and CB2 receptors at expected band weights. Within and between strands of CC smooth muscle, CB1 and CB2 immunoreactivity (IR) was found in nerve fibers that also expressed IR for nitric oxide synthase (NOS) or transient receptor potential V1 (TRPV1). Neither CB1-IR nor CB2-IR nerves were colocalized with calcitonin-gene–related peptide (CGRP)-containing or tyrosine hydroxylase-containing nerves. No differences were observed between primate and human CC sections.Anandamide (10⁻⁹ to 10⁻⁴ M) had no contractile effects on CC smooth muscle, no relaxant effects on precontracted preparations, and no effect on phenylephrine-induced contractions. However, anandamide (10 μM) inhibited electrically evoked smooth-muscle relaxations (34–48%; p ≤ 0.05).

Conclusions

CB1 and CB2 receptors are located on NOS-containing nerves in primate and human CC tissue. In contrast to findings in rats, anandamide antagonized nerve-mediated relaxations of the primate CC, suggesting important species differences for CB-mediated functions. The results also suggest a peripheral mechanism for cannabis-related sexual dysfunction.     

钩藤提取液致离体大鼠胸主动脉环舒张作用的研究

目的研究钩藤提取液(FZA)对离体大鼠胸主动脉环舒张力的作用与机制。方法采用大鼠离体胸主动脉灌流技术,以累积浓度法观测钩藤提取液对基础状态血管环张力的影响。结果单独加入钩藤提取液观察到离体血管张力的改变,有显著的舒展血管作用P≤0.05,n=6。结论钩藤提取液具有明显的舒张血管的作用,其作用机制可能直接舒张血管。     

放松技术对减轻骨科患者术后疼痛的护理研究

目的:通过对放松技术对减轻骨科患者术后疼痛的护理进行对比分析,达到推广放松技术来护理骨科患者的目的。方法:回顾性分析就诊的208例骨科患者资料,对208例骨科患者手术后的护理采取放松技术护理。同时,设置198例骨科患者采用正常的护理,该组设置为B组。结果:通过对A组和B组的比较发现,通过骨科放松技术护理的A组骨科患者康复更快,恢复效果更好。结论:放松技术对于减轻骨科患者手术后的疼痛具有重要的作用,值得推广。