Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck.

The nonlinear post-flutter instabilities were experimentally investigated through two-degree-of-freedom sectional model tests on a typical flat closed-box bridge deck (width-to-depth ratio 9.14). Laser displacement sensors and piezoelectric force balances were used in the synchronous measurement of dynamic displacement and aerodynamic force. Beyond linear flutter boundary, the sectional model exhibited heave-torsion coupled limit cycle oscillation (LCOs) with an unrestricted increase of stable amplitudes with reduced velocity. The post-critical LCOs vibrated in a complex mode with amplitude-dependent mode modulus and phase angle. Obvious heaving static deformation was found to be coupled with the large-amplitude post-critical LCOs, for which classical quasi-steady theory was not applicable. The aerodynamic torsional moment and lift during post-critical LCOs were measured through a novel wind-tunnel technique by 4 piezoelectric force balances. The measured force signals were found to contain significantly higher-order components. The energy evolution mechanism during post-critical LCOs was revealed via the hysteresis loops of the measured force signals.

Spontaneous spinal epidural hematomas: One case report and rehabilitation outcome.

RATIONALE: Spontaneous spinal epidural hematoma (SSEH) is a relatively rare but potentially disabling disease, and the classical presentation of it includes an acute onset of severe, sometimes radiating back or neck pain, followed by signs and symptoms of rapidly evolving nerve root or spinal cord compression. PATIENT CONCERNS: Here, we report a 26-year-old female patient presented with weakness in bilateral lower extremities, progressing to intense paraplegia and anesthesia without recent medical history of trauma, infection, surgery, or drug use. DIAGNOSIS: A magnetic resonance imaging (MRI) scan of spinal cord was planned and a posterior epidural hematoma of the thoracic spine was observed. INTERVENTIONS: A posterior decompression and hematoma evacuation was performed after diagnosis immediately. Early rehabilitation program of the specific kind spinal cord injury was formulated and implemented. OUTCOMES: The patient finally can handle basic living activities, such as completing wheelchair locomotion, transferring from bed to wheelchair independently after 3 months of rehabilitation. LESSONS: SSEH is a rarely occurring case in emergency. Acute chest pain and paraplegia could be the initial presentation of acute spinal epidural hemorrhage, but the diagnosis of patient without classical manifestations is still a challenge for doctors. Early diagnosis, prompt decompression, and individualized rehabilitation program can improve the prognosis and outcome.

Effect of Bone Cement Volume Fraction on Adjacent Vertebral Fractures After Unilateral Percutaneous Kyphoplasty.

STUDY DESIGN: A retrospective study. SUMMARY OF BACKGROUND DATA: Complications of the bone cement used in vertebroplasty and kyphoplasty procedures have received increasingly more attention, especially for bone cement volume. OBJECTIVE: The aim of the study was to retrospectively assess the relationship between bone cement volume fraction and adjacent vertebral fracture (AVF) after unilateral percutaneous kyphoplasty (PKP). MATERIALS AND METHODS: Between 2006 and 2011, 495 patients with single-level osteoporotic vertebral compression fracture (OVCF) were surgically treated by unilateral PKP and had completed 12-month follow-up in our hospital. According to the new OVCF, they were divided into 3 groups: AVF group, non-AVF group, and normal group (who were not new OVCF). On the basis of the value of the plain radiography, the cement volume fraction for the vertebral body was calculated, and cement leakage, bone mineral density, visual analog scale, and Cobb angle of preoperative and postoperative were analyzed. RESULTS: During the follow-up, 110 (22.2%) patients had new OVCF, and others were normal (n=385). Fifty-two cases were AVF and 58 were non-AVF. The cement volume fraction of AVF group, non-AVF group, and normal group were 32.5%±5.5%, 27.3%±1.8%, and 27.1%±2.6%, respectively. The 95% confidence interval of volume fraction were (31.0, 34.1), (26.8, 27.7), and (26.9, 28.5), respectively. The AVF group showed higher cement volume fraction in 3 groups (P<0.05), and there were no significant difference between non-AVF and normal group (P>0.05). There were 19 (36.5%) patients with cement leakage in AVF group, 12 (20.7%) in non-AVF group, and 68 (17.7%) in normal group. The AVF group showed higher cement leakage (P<0.05). Compared with AVF group and normal group, non-AVF group had lower bone mineral density in preoperation. All groups reported significantly improved visual analog scale scores and Cobb angle on the day of surgery. However, there were no significant difference between the 3 groups. CONCLUSIONS: Unilateral PKP is an effective and safe procedure for patients with OVCF. However, cement volume should be determined in terms of the vertebral body fraction to obtain a favorable outcome. The risk of AVF and cement leakage will increase obviously with the cement volume fraction increased. We recommend that a bone cement volume fraction of about one fourth is suitable for unilateral PKP.

[Analysis of different types of soil by FTIR and ICP-MS].

Fourier transform infrared spectroscopy (FTIR) and inductively coupled plasma mass spectrometry (ICP-MS) were used to study six types of farmland soil from different areas. The FTIR results showed that the infrared spectra of soil were mainly composed of the absorption band of clay minerals, organic matter and inorganic salts, such as carbonate, phosphate, manganate and so on. The mineral atlas of six soil samples were all of montmorillonite type. The ICP-MS test results showed that the available elements content of different types and colours of soil samples were different There was significant lack status of available Ca between different types of farmland soil, the content of available Mg in Huludao soil was in the medium level, other areas were in the status of shortage. There was only significant lack status of available Mn and available Zn in Baiyin soil, the content of available Fe in Chenggong soil was in the status of shortage, the content of available Cu in all areas was particularly rich. The content of available P in Jining soil was rich, Luoyang and Huludao soil were in the medium level, the soil of Chenggong, Baiyin and Luliang were in the status of shortage. The content of available K in Luoyang, Chenggong and Jining soil was relatively rich, Luliang soil was in the medium level, the soil of Huludao and Baiyin were in the status of shortage. It is observed that the deeper the color of soil samples, the richer the amount of some available trace elements such as magnesium, copper, iron, manganese and zinc. According to the national classification standard of available elements content, we analyzed the nutrients of available elements content in the farmland soil of different areas, and implemented remedial measures for the lacking of available elements for all of the six areas.

Emergent surgical reduction and fixation for Pipkin type I femoral fractures.

The purpose of this study was to assess the effect of timing of large fragment fixation in patients with Pipkin type-I fractures. Patients with Pipkin type-I fractures from the authors' trauma center were prospectively observed between July 2007 and July 2010. Fragments that constituted more than one-fourth of the femoral head were included. Thirty-six patients were equally randomized to undergo emergent surgical reduction and fixation or secondary operative fixation after emergent closed reduction. No significant differences existed between the 2 groups with regard to the baseline characteristics, operating time, and blood loss (P>.05). However, the emergent surgical reduction and fixation group had a shorter hospital stay (P<.05). The results after more than 2-year follow-up showed that the complication and avascular necrosis rates were higher in the secondary operative fixation after emergent closed reduction group compared with the emergent surgical reduction and fixation group (P<.05). It was difficult to achieve an anatomically reduced femoral head when the fragments constituted more than one-fourth of the femoral head. Patients who underwent secondary operative fixation after emergent closed reduction had a high avascular necrosis rate and a relatively poor outcome. Emergent surgical reduction and fixation should be performed shortly after injury to enhance the treatment outcome.

[Infrared spectroscopic study on leaf senescence of evergreen tree].

In order to investigate plant physiological process of leaf senescence and aging, Fourier transform infrared (FTIR) spectroscopy was used to study the young, mature, and old yellow leaves from seven species of evergreen trees. The spectra of the leaves from different growing period are different in the region of 1 800-700 cm(-1). The absorption ratios A1 070/A2 927, A1 070/A1 160 were used to evaluate the relative changes of polysaccharides, and A1 318/A2 922 was used to estimate the change of calcium oxalate during leaf senescence. Decomposition and curve-fitting analysis was performed in the region of 1 800 -1 500 cm(-1). The sub-band absorption ratio H1 650/H1 740 was used to evaluate the relative changes of protein in the leaves. The results show that the accumulation and mobilization of polysaccharides, protein, and calcium oxalate during leaf growing period were different in different plant species. This study demonstrates the potential of mid-infrared spectroscopy for investigation of plants senescence, as well as physiological and biochemical changes of plants.

Regulation of cardiomyocyte signaling by RGS proteins: differential selectivity towards G proteins and susceptibility to regulation.

Many signals that regulate cardiomyocyte growth, differentiation and function are mediated via heterotrimeric G proteins, which are under the control of RGS proteins (Regulators of G protein Signaling). Several RGS proteins are expressed in the heart, but so far little is known about their function and regulation. Using adenoviral gene transfer, we conducted the first comprehensive analysis of the capacity and selectivity of the major cardiac RGS proteins (RGS2-RGS5) to regulate central G protein-mediated signaling pathways in adult ventricular myocytes (AVM). All four RGS proteins potently inhibited Gq/11-mediated phospholipase C beta stimulation and cell growth (assessed in neonatal myocytes). Importantly, RGS2 selectively inhibited Gq/11 signaling, whereas RGS3, RGS4 and RGS5 had the capacity to regulate both Gq/11 and Gi/o signaling (carbachol-induced cAMP inhibition). Gs signaling was unaffected, and, contrary to reports in other cell lines, RGS2-RGS5 did not appear to regulate adenylate cyclase directly in AVM. Since RGS proteins can be highly regulated in their expression by many different stimuli, we also tested the hypothesis that RGS expression is subject to G protein-mediated regulation in AVM and determined the specificity with which enhanced G protein signaling alters endogenous RGS expression in AVM. RGS2 mRNA and protein were markedly but transiently up-regulated by enhanced Gq/11 signaling (alpha1-adrenergic stimulation or Galphaq* overexpression), possibly by a negative feedback mechanism. In contrast, the other negative regulators of Gq/11 signaling (RGS3-RGS5) were unchanged. Endogenous RGS2 (but not RGS3-RGS5) expression was also up-regulated in cells with enhanced AC signaling (beta-adrenergic or forskolin stimulation). Taken together, these findings suggest diverse roles of RGS proteins in regulating myocyte signaling. RGS2 emerged as the only selective and highly regulated inhibitor of Gq/11 signaling that could potentially become a promising target for ameliorating Gq/11-mediated signaling and growth.

Selective loss of fine tuning of Gq/11 signaling by RGS2 protein exacerbates cardiomyocyte hypertrophy.

Alterations in cardiac G protein-mediated signaling, most prominently G(q/11) signaling, are centrally involved in hypertrophy and heart failure development. Several RGS proteins that can act as negative regulators of G protein signaling are expressed in the heart, but their functional roles are still poorly understood. RGS expression changes have been described in hypertrophic and failing hearts. In this study, we report a marked decrease in RGS2 (but not other major cardiac RGS proteins (RGS3-RGS5)) that occurs prior to hypertrophy development in different models with enhanced G(q/11) signaling (transgenic expression of activated Galpha(q)(*) and pressure overload due to aortic constriction). To assess functional consequences of selective down-regulation of endogenous RGS2, we identified targeting sequences for effective RGS2 RNA interference and used lipid-based transfection to achieve uptake of fluorescently labeled RGS2 small interfering RNA in >90% of neonatal and adult ventricular myocytes. Endogenous RGS2 expression was dose-dependently suppressed (up to 90%) with no major change in RGS3-RGS5. RGS2 knockdown increased phenylephrine- and endothelin-1-induced phospholipase Cbeta stimulation in both cell types and exacerbated the hypertrophic effect (increase in cell size and radiolabeled protein) in neonatal myocytes, with no major change in G(q/11)-mediated ERK1/2, p38, or JNK activation. Taken together, this study demonstrates that endogenous RGS2 exerts functionally important inhibitory restraint on G(q/11)-mediated phospholipase Cbeta activation and hypertrophy in ventricular myocytes. Our findings point toward a potential pathophysiological role of loss of fine tuning due to selective RGS2 down-regulation in G(q/11)-mediated remodeling. Furthermore, this study shows the feasibility of effective RNA interference in cardiomyocytes using lipid-based small interfering RNA transfection.

The basic helix-loop-helix factor Hand 2 regulates autonomic nervous system development.

Mammalian autonomic nervous system (ANS) development requires the combinatorial action of a number of transcription factors, which include Mash 1, Phox 2b, and GATA 3. Here we show that the bHLH transcription factor, Hand 2 (dHAND), is expressed concurrently with Mash 1 during sympathetic nervous system (SNS) development and that the expression of Hand 2 is not dependent on Mash 1. This suggests that these two bHLH factors work in parallel during SNS development. We also show that ectopic expression of Hand 2 activates the neuronal program and promotes the acquisition of a phenotype corresponding to peripheral neurons including neurons of the SNS lineage in P19 embryonic carcinoma cells. We propose that Hand 2 works in parallel with other members of the transcriptional network to regulate ANS developmental but can ectopically activate the program by a cross-regulatory mechanism that includes the activation of Mash 1. We show that this function is dependent on its interaction with the histone acetyltransferase p300/CBP, indicating that Hand 2 functions to promote ANS development as part of a larger transcriptional complex.

JAB1 enhances HAND2 transcriptional activity by regulating HAND2 DNA binding.

HAND2 (also known as dHAND) is a basic helix-loop-helix (bHLH) transcription factor essential for development of the heart, limbs, and neural crest-derived lineages. HAND2 expression is observed in a number of tissues derived from the neural crest, including components of the peripheral nervous system, where it has been shown to regulate sympathetic nervous system development. Here we show that HAND2 is expressed in both the sympathetic and the parasympathetic divisions of the autonomic nervous system (ANS). How HAND2 functions during development of these neuronal lineages is uncertain. An important mechanism involved in HAND2's function is its interactions with other proteins. To understand better the molecular interactions regulating HAND2 during ANS development, we employed a yeast two-hybrid screen to identify HAND2-interacting proteins. One protein identified in this screen, Jun activation domain-binding protein (JAB1), is involved in numerous cell processes, including regulation of transcription and protein turnover. We show that JAB1 binds directly to the HLH domain of HAND2 and increases HAND2 transcription-stimulating activity. However, JAB1 does not contain a transcriptional activation domain, nor does it recruit an activation domain to HAND2. Our data indicate that JAB1 augments HAND2 transcriptional activity by enhancing HAND2 DNA binding. We further show that enhanced HAND2 DNA binding is mediated through the HLH domain and not through the DNA binding domain. These results show that JAB1 regulates the transcriptional activity of HAND2 in a unique manner that may account, in part, for the apparent ability of this bHLH factor to regulate gene expression through numerous mechanisms.

Decreased Smad 7 expression contributes to cardiac fibrosis in the infarcted rat heart.

We examined the role of the transforming growth factor (TGF)-beta(1) signaling inhibitor Smad 7 in cardiac fibrosis. TGF-beta(1) (10 ng/ml) was found to increase cytosolic Smad 7 expression in primary adult rat fibroblasts and induce rapid nuclear export of exogenous Smad 7 in COS-7 cells. Furthermore, overexpression of Smad 7 in primary adult fibroblasts was associated with suppressed collagen type I and III expression. We detected Smad 7, phosphorylated Smad 2, TGF-beta type I receptor (TbetaRI), and TGF-beta(1) proteins in postmyocardial infarct (MI) rat hearts. In 2 and 4 wk post-MI hearts, Smad 7 and TbetaRI expression were decreased in scar tissue, whereas TGF-beta(1) expression was increased in scar and viable tissue. In the 8 wk post-MI heart, Smad 7 expression was decreased in both scar tissue and myocardium remote to the infarct scar. Finally, we confirmed that these changes are paralleled by decreased expression of cytosolic phosphorylated receptor-regulated Smad 2 in 4-wk viable myocardium and in 2- and 4-wk infarct scar tissues. Taken together, our data imply that decreased inhibitory Smad 7 signal in cardiac fibroblasts may play a role in the pathogenesis of cardiac fibrosis in the post-MI heart.

Acute protection of ischemic heart by FGF-2: involvement of FGF-2 receptors and protein kinase C.

We examined the effect of fibroblast growth factor (FGF)-2 on myocardial resistance to injury when administered after the onset of ischemia, in vivo and ex vivo, and the role of FGF-2 receptors and protein kinase C (PKC). FGF-2 was injected into the left ventricle of rats undergoing permanent surgical coronary occlusion leading to myocardial infarction (MI). After 24 h, FGF-2-treated hearts displayed significantly reduced injury, determined by histological staining and troponin T release, and improved developed pressure compared with untreated controls. An FGF-2 mutant with diminished affinity for the tyrosine kinase FGF-2 receptor 1 (FGFR1) was not cardioprotective. FGF-2-treated hearts retained improved function and decreased damage at 6 wk after MI. In the ex vivo heart, FGF-2 administration during reperfusion after 30-min ischemia improved functional recovery and increased relative levels of PKC subtypes alpha, epsilon, and zeta in the particulate fraction, in a chelerythrine-preventable mode; it also decreased loss of energy metabolites. We conclude that intramyocardial FGF-2 administration shortly after the onset of ischemia confers protection from acute and chronic cardiac dysfunction and damage; FGF-2 delivered during reperfusion protects from ischemia-reperfusion injury; and protection by FGF-2 requires intact binding to FGFR1 and is likely mediated by PKC.