Evaluation of early tissue reactions after lumbar intertransverse process fusion using CT in a rabbit

OBJECTIVE: The objective of the study was to evaluate tissue reactions such as bone genesis, cartilage genesis and graft materials in the early phase of lumbar intertransverse process fusion in a rabbit model using computed tomography (CT) imaging with CT intensity (Hounsfield units) measurement, and to compare these data with histological results. MATERIALS AND METHODS: Lumbar intertransverse process fusion was performed on 18 rabbits. Four graft materials were used: autograft bone (n = 3); collagen membrane soaked with recombinant human bone morphogenetic protein-2 (rhBMP-2) (n = 5); granular calcium phosphate (n = 5); and granular calcium phosphate coated with rhBMP-2 (n = 5). All rabbits were euthanized 3 weeks post-operatively and lumbar spines were removed for CT imaging and histological examination. RESULTS: Computed tomography imaging demonstrated that each fusion mass component had the appropriate CT intensity range. CT also showed the different distributions and intensities of bone genesis in the fusion masses between the groups. Each component of tissue reactions was identified successfully on CT images using the CT intensity difference. Using CT color mapping, these observations could be easily visualized, and the results correlated well with histological findings. CONCLUSIONS: The use of CT intensity is an effective approach for observing and comparing early tissue reactions such as newly synthesized bone, newly synthesized cartilage, and graft materials after lumbar intertransverse process fusion in a rabbit model.

Ability of dGEMRIC and T2 mapping to evaluate cartilage repair after microfracture: a goat study

OBJECTIVE: To investigate the ability of delayed gadolinium-enhanced magnetic resonance (MR) imaging of cartilage (dGEMRIC) and T2 mapping to evaluate the quality of repair tissue after microfracture. DESIGN: Twelve knees from 12 goats were studied. An osteochondral defect (diameter, 6mm; depth, 3mm) with microfracture was created in the weight-bearing aspect of both the medial and lateral femoral condyles. Goats were euthanized at 24 weeks (n=6) and 48 weeks (n=6) postsurgery. Pre-contrast R1 (R1pre) and post-contrast R1 (R1post) measurements for dGEMRIC and a pre-contrast T2 measurement for T2 mapping were performed with a 3T MR imaging system. MR imaging findings were compared with histological and biochemical assessments. RESULTS: In native cartilage, significant correlations were observed between the R1post and the glycosaminoglycan (GAG) concentration, as well as DeltaR1 (difference between the R1pre and R1post) and the GAG concentration (P<0.05). In repair tissue, a significant correlation was observed between DeltaR1 and the GAG concentration (P<0.05), but not between the R1post and the GAG concentration. In both repair tissue and native cartilage, no correlation was observed between T2 and the water concentration or between T2 and the hydroxyproline (HP) concentration. A zonal variation of T2 and a clear dependence of T2 on the angles relative to B0 were observed in native cartilage, but not in repair tissue. CONCLUSION: dGEMRIC with DeltaR1 measurement might be useful for the evaluation of the GAG concentration in repair tissue after microfracture. T2 mapping might be useful for the differentiation of repair tissue after microfracture from native cartilage; however, its potential to assess the specific biochemical markers in native cartilage as well as repair tissue may be limited.

Human intervertebral disc stiffness correlates better with the Otsu threshold computed from axial T2 map of its posterior annulus fibrosus than with clinical classifications

Degeneration of the intervertebral disc, sometimes associated with low back pain and abnormal spinal motions, represents a major health issue with high costs. A non-invasive degeneration assessment via qualitative or quantitative MRI (magnetic resonance imaging) is possible, yet, no relation between mechanical properties and T2 maps of the intervertebral disc (IVD) has been considered, albeit T2 relaxation time values quantify the degree of degeneration. Therefore, MRI scans and mechanical tests were performed on 14 human lumbar intervertebral segments freed from posterior elements and all soft tissues excluding the IVD. Degeneration was evaluated in each specimen using morphological criteria, qualitative T2 weighted images and quantitative axial T2 map data and stiffness was calculated from the load-deflection curves of in vitro compression, torsion, lateral bending and flexion/extension tests. In addition to mean T2, the OTSU threshold of T2 (TOTSU), a robust and automatic histogram-based method that computes the optimal threshold maximizing the distinction of two classes of values, was calculated for anterior, posterior, left and right regions of each annulus fibrosus (AF). While mean T2 and degeneration schemes were not related to the IVDs' mechanical properties, TOTSU computed in the posterior AF correlated significantly with those classifications as well as with all stiffness values. TOTSU should therefore be included in future degeneration grading schemes.

TH2 cytokines from malignant cells suppress TH1 responses and enforce a global TH2 bias in leukemic cutaneous T-cell lymphoma

PURPOSE In leukemic cutaneous T-cell lymphoma (L-CTCL), malignant T cells accumulate in the blood and give rise to widespread skin inflammation. Patients have intense pruritus, increased immunoglobulin E (IgE), and decreased T-helper (TH)-1 responses, and most die from infection. Depleting malignant T cells while preserving normal immunity is a clinical challenge. L-CTCL has been variably described as a malignancy of regulatory, TH2 and TH17 cells. EXPERIMENTAL DESIGN We analyzed phenotype and cytokine production in malignant and benign L-CTCL T cells, characterized the effects of malignant T cells on healthy T cells, and studied the immunomodulatory effects of treatment modalities in patients with L-CTCL. RESULTS Twelve out of 12 patients with L-CTCL overproduced TH2 cytokines. Remaining benign T cells were also strongly TH2 biased, suggesting a global TH2 skewing of the T-cell repertoire. Culture of benign T cells away from the malignant clone reduced TH2 and enhanced TH1 responses, but separate culture had no effect on malignant T cells. Coculture of healthy T cells with L-CTCL T cells reduced IFNγ production and neutralizing antibodies to interleukin (IL)-4 and IL-13 restored TH1 responses. In patients, enhanced TH1 responses were observed following a variety of treatment modalities that reduced malignant T-cell burden. CONCLUSIONS A global TH2 bias exists in both benign and malignant T cells in L-CTCL and may underlie the infectious susceptibility of patients. TH2 cytokines from malignant cells strongly inhibited TH1 responses. Our results suggest that therapies that inhibit TH2 cytokine activity, by virtue of their ability to improve TH1 responses, may have the potential to enhance both anticancer and antipathogen responses.

Conversion of myoblasts to physiologically active neuronal phenotype.

Repressor element 1 (RE1)-silencing transcription factor (REST)/neuron-restrictive silencer factor (NRSF) can repress several terminal neuronal differentiation genes by binding to a specific DNA sequence (RE1/neuron-restrictive silencer element [NRSE]) present in their regulatory regions. REST-VP16 binds to the same RE1/NRSE, but activates these REST/NRSF target genes. However, it is unclear whether REST-VP16 expression is sufficient to cause formation of functional neurons either from neural stem cells or from heterologous stem cells. Here we show that the expression of REST-VP16 in myoblasts grown under muscle differentiation conditions blocked entry into the muscle differentiation pathway, countered endogenous REST/NRSF-dependent repression, activated the REST/NRSF target genes, and, surprisingly, activated other neuronal differentiation genes and converted the myoblasts to a physiologically active neuronal phenotype. Furthermore, in vitro differentiated neurons produced by REST-VP16-expressing myoblasts, when injected into mouse brain, survived, incorporated into the normal brain, and did not form tumors. This is the first instance in which myoblasts were converted to a neuronal phenotype. Our results suggest that direct activation of REST/NRSF target genes with a single transgene, REST-VP16, is sufficient to activate other terminal neuronal differentiation genes and to override the muscle differentiation pathways, and they suggest that this approach provides an efficient way of triggering neuronal differentiation in myoblasts and possibly other stem cells.

Interactions between cyclosporin A, low-density lipoprotein and the low-density lipoprotein receptor

Cyclosporine A (CSA) is a cyclic eleven amino acid, lipophilic molecule used therapeutically as an immunosuppressive agent. Cyclosporine can specifically inhibit the transcription of a number of different genes. It is known that CSA is bound almost exclusively to lipoproteins in plasma, however, the relationship between the low density lipoprotein (LDL), the LDL receptor, and CSA has not been fully elucidated. The exact mechanism of cellular uptake of CSA is unknown, but it is believed to be by simple passive diffusion across the cell membrane. In addition, it has been recently shown that the frequent finding of hypercholesterolemia seen in patients treated with CSA can be explained by a CSA-induced effect. The mechanism by which CSA induces hypercholesterolemia is not known. We have used an LDL receptor-deficient animal model, the Watanabe Heritable Hyperlipidemic (WHHL) rabbit to investigate the role of LDL and the LDL receptor in the cellular uptake of CSA. Using this animal model, we have shown that CSA uptake by lymphocytes is predominantly LDL receptor-mediated. Chemical modification of apoB-100 on LDL particles abolishes their ability to bind to the LDL receptor. When CSA is incubated with modified LDL much less is taken-up than when native LDL is incubated with CSA. Treatment of two human cell lines with CSA results in a dose-dependent decrease in LDL receptor mRNA levels. Using a novel transfection system involving the 5$\sp\prime$-flanking region of the LDL receptor gene, we have found that CSA decreases the number of transcripts, but is dependent on whether or not cholesterol is present and the stage of growth of the cells. ^

Human TH9 cells are skin-tropic and have autocrine and paracrine proinflammatory capacity.

T helper type 9 (TH9) cells can mediate tumor immunity and participate in autoimmune and allergic inflammation in mice, but little is known about the TH9 cells that develop in vivo in humans. We isolated T cells from human blood and tissues and found that most memory TH9 cells were skin-tropic or skin-resident. Human TH9 cells coexpressed tumor necrosis factor-α and granzyme B and lacked coproduction of TH1/TH2/TH17 cytokines, and many were specific for Candida albicans. Interleukin-9 (IL-9) production was transient and preceded the up-regulation of other inflammatory cytokines. Blocking studies demonstrated that IL-9 was required for maximal production of interferon-γ, IL-9, IL-13, and IL-17 by skin-tropic T cells. IL-9-producing T cells were increased in the skin lesions of psoriasis, suggesting that these cells may contribute to human inflammatory skin disease. Our results indicate that human TH9 cells are a discrete T cell subset, many are tropic for the skin, and although they may function normally to protect against extracellular pathogens, aberrant activation of these cells may contribute to inflammatory diseases of the skin.

Transcatheter Aortic Valve Replacement in Bicuspid Aortic Valve Disease.

BACKGROUND Limited information exists describing the results of transcatheter aortic valve (TAV) replacement in patients with bicuspid aortic valve (BAV) disease (TAV-in-BAV). OBJECTIVES This study sought to evaluate clinical outcomes of a large cohort of patients undergoing TAV-in-BAV. METHODS We retrospectively collected baseline characteristics, procedural data, and clinical follow-up findings from 12 centers in Europe and Canada that had performed TAV-in-BAV. RESULTS A total of 139 patients underwent TAV-in-BAV with the balloon-expandable transcatheter heart valve (THV) (n = 48) or self-expandable THV (n = 91) systems. Patient mean age and Society of Thoracic Surgeons predicted risk of mortality scores were 78.0 ± 8.9 years and 4.9 ± 3.4%, respectively. BAV stenosis occurred in 65.5%, regurgitation in 0.7%, and mixed disease in 33.8% of patients. Incidence of type 0 BAV was 26.7%; type 1 BAV was 68.3%; and type 2 BAV was 5.0%. Multislice computed tomography (MSCT)-based TAV sizing was used in 63.5% of patients (77.1% balloon-expandable THV vs. 56.0% self-expandable THV, p = 0.02). Procedural mortality was 3.6%, with TAV embolization in 2.2% and conversion to surgery in 2.2%. The mean aortic gradient decreased from 48.7 ± 16.5 mm Hg to 11.4 ± 9.9 mm Hg (p < 0.0001). Post-implantation aortic regurgitation (AR) grade ≥2 occurred in 28.4% (19.6% balloon-expandable THV vs. 32.2% self-expandable THV, p = 0.11) but was prevalent in only 17.4% when MSCT-based TAV sizing was performed (16.7% balloon-expandable THV vs. 17.6% self-expandable THV, p = 0.99). MSCT sizing was associated with reduced AR on multivariate analysis (odds ratio [OR]: 0.19, 95% confidence intervals [CI]: 0.08 to 0.45; p < 0.0001). Thirty-day device safety, success, and efficacy were noted in 79.1%, 89.9%, and 84.9% of patients, respectively. One-year mortality was 17.5%. Major vascular complications were associated with increased 1-year mortality (OR: 5.66, 95% CI: 1.21 to 26.43; p = 0.03). CONCLUSIONS TAV-in-BAV is feasible with encouraging short- and intermediate-term clinical outcomes. Importantly, a high incidence of post-implantation AR is observed, which appears to be mitigated by MSCT-based TAV sizing. Given the suboptimal echocardiographic results, further study is required to evaluate long-term efficacy.

Study of Heavy-ion Induced Fission for Heavy Element Synthesis

Fission fragment mass distributions were measured in heavy-ion induced fission of 238U. The mass distributions changed drastically with incident energy. The results are explained by a change of the ratio between fusion and quasifission with nuclear orientation. A calculation based on a fluctuation dissipation model reproduced the mass distributions and their incident energy dependence. Fusion probability was determined in the analysis. Evaporation residue cross sections were calculated with a statistical model for the reactions of 30Si+238U and 34S+238U using the obtained fusion probability in the entrance channel. The results agree with the measured cross sections of 263,264Sg and 267,268Hs, produced by 30Si+238U and 34S+238U, respectively. It is also suggested that sub-barrier energies can be used for heavy element synthesis.

The Chloroplast-Localized Phospholipases D a4 and a5 Regulate Herbivore-Induced Direct and Indirect Defenses in Rice

The oxylipin pathway is of central importance for plant defensive responses. Yet, the first step of the pathway, the liberation of linolenic acid following induction, is poorly understood. Phospholipases D (PLDs) have been hypothesized to mediate this process, but data from Arabidopsis (Arabidopsis thaliana) regarding the role of PLDs in plant resistance have remained controversial. Here, we cloned two chloroplast-localized PLD genes from rice (Oryza sativa), OsPLDα4 and OsPLDα5, both of which were up-regulated in response to feeding by the rice striped stem borer (SSB) Chilo suppressalis, mechanical wounding, and treatment with jasmonic acid (JA). Antisense expression of OsPLDα4 and -α5 (as-pld), which resulted in a 50% reduction of the expression of the two genes, reduced elicited levels of linolenic acid, JA, green leaf volatiles, and ethylene and attenuated the SSB-induced expression of a mitogen-activated protein kinase (OsMPK3), a lipoxygenase (OsHI-LOX), a hydroperoxide lyase (OsHPL3), as well as a 1-aminocyclopropane-1-carboxylic acid synthase (OsACS2). The impaired oxylipin and ethylene signaling in as-pld plants decreased the levels of herbivore-induced trypsin protease inhibitors and volatiles, improved the performance of SSB and the rice brown planthopper Nilaparvata lugens, and reduced the attractiveness of plants to a larval parasitoid of SSB, Apanteles chilonis. The production of trypsin protease inhibitors in as-pld plants could be partially restored by JA, while the resistance to rice brown planthopper and SSB was restored by green leaf volatile application. Our results show that phospholipases function as important components of herbivore-induced direct and indirect defenses in rice.