Heterogeneous Disease Progression in a Mouse Model of Vascular Cognitive Impairment.

Recently, an asymmetric vascular compromise approach that replicates many aspects of human vascular cognitive impairment (VCI) has been reported. The present study aimed to first investigate on the reproducibility in the disease progression of this newly reported VCI model using wild-type C57BL6/J mice. The second aim was to assess how this approach will affect the disease progression of transgenic Alzheimer's disease (AD) 5XFAD mice subjected to VCI. C57BL6/J and 5XFAD mice were subjected to VCI by placing an ameroid constrictor on the right CCA and a microcoil on the left CCA. Infarcts and hippocampal neuronal loss did not appear predominantly in the right (ameroid side) as expected but randomly in both hemispheres. The mortality rate of C57BL6/J mice was unexpectedly high. Inducing VCI reduced amyloid burden in the hippocampi of 5XFAD mice. Since VCI is known to be complex and complicated, the heterogeneous disease progression observed from this current study shares close resemblance to the clinical manifestation of VCI. This heterogeneity, however, makes it challenging to test novel treatment options using this model. Further study is warranted to tackle the heterogeneous nature of VCI.

Exploring the Potential of Mesenchymal Stem Cell-Based Therapy in Mouse Models of Vascular Cognitive Impairment.

Closely linked to Alzheimer's disease (AD), the pathological spectrum of vascular cognitive impairment (VCI) is known to be wide and complex. Considering that multiple instead of a single targeting approach is considered a treatment option for such complicated diseases, the multifaceted aspects of mesenchymal stem cells (MSCs) make them a suitable candidate to tackle the heterogeneity of VCI. MSCs were delivered via the intracerebroventricular (ICV) route in mice that were subjected to VCI by carotid artery stenosis. VCI was induced in C57BL6/J mice wild type (C57VCI) mice by applying a combination of ameroid constrictors and microcoils, while ameroid constrictors alone were bilaterally applied to 5xFAD (transgenic AD mouse model) mice (5xVCI). Compared to the controls (minimal essential medium (MEM)-injected C57VCI mice), changes in spatial working memory were not noted in the MSC-injected C57VCI mice, and unexpectedly, the mortality rate was higher. In contrast, compared to the MEM-injected 5xVCI mice, mortality was not observed, and the spatial working memory was also improved in MSC-injected 5xVCI mice. Disease progression of the VCI-induced mice seems to be affected by the method of carotid artery stenosis and due to this heterogeneity, various factors must be considered to maximize the therapeutic benefits exerted by MSCs. Factors, such as the optimal MSC injection time point, cell concentration, sacrifice time point, and immunogenicity of the transplanted cells, must all be adequately addressed so that MSCs can be appropriately and effectively used as a treatment option for VCI.

Correlation of quantitative dynamic contrast-enhanced MRI with microvascular density in necrotic, partial necrotic, and viable liver tumors in a rabbit model.

The purpose of this study was to examine the correlation of quantitative dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) with microvessel density (MVD) in necrotic, partial necrotic, and viable tumors using a rabbit VX2 liver tumor model. Nine rabbits were used for this study. The complete necrotic area (CNA), partial necrotic area (PNA), and viable tumor area (VTA) of liver tumors were experimentally induced by radiofrequency ablation (RFA). DCE-MRI data were processed based on the extended Kety model to estimate Ktrans, ve and vp parameters. The boundaries among CNA, PNA, and VTA were delineated based on H&E stain images, and MVD was assessed for each subregion of each VX2 tumor based. There were no correlations between ph-parameters (Ktrans, ve, and vp) and MVD for CNA. For PNA, the Ktrans values were positively correlated with the MVD (r = 0.8124, p < 0.001). For VTA, we found a positive correlation between Ktrans values and the MVD (r = 0.5743, p < 0.05). Measuring from both the PNA and the VTA, mean Ktrans values were positively correlated with mean MVD (r = 0.8470, p < 0.0001). In a rabbit VX2 liver tumor model, Ktrans values correlated well with MVD counts of PNA and VTA in liver tumors.

Preventive effects of CTLA4Ig-overexpressing adipose tissue--derived mesenchymal stromal cells in rheumatoid arthritis.

BACKGROUND AIMS: Rheumatoid arthritis is a systemic autoimmune disorder. In this study, we first compared the therapeutic effects of syngeneic and xenogeneic adipose tissue-derived stem cells on a collagen-induced arthritis mouse model. Second, we investigated the synergistic preventive effects of CTLA4Ig and adipose tissue-derived mesenchymal stromal cells (ASCs) as a therapeutic substance. METHODS: Arthritis was induced in all groups except for the normal, saline (N) group, using chicken type II collagen (CII). Animals were divided into C (control, saline), H (hASCs), M (mASCs) and N groups (experiment I) and C, H, CT (CTLA4Ig-overexpressing human ASC [CTLA4Ig-hASCs]) and N groups (experiment II), according to transplanted material. Approximately 2 × 10(6) ASCs or 150 µL of saline was intravenously administered on days 24, 27, 30 and 34, and all animals were killed on days 42 to 44 after CII immunization. RESULTS: Anti-mouse CII autoantibodies were significantly lower in the H, M and CT groups than in the C group. Cartilage damage severity score and C-telopeptide of type II collagen were significantly lower in the CT group than in the C group. The serum levels of IL-6 were significantly lower in the H, M and CT groups than in the C group. The serum levels of keratinocyte chemoattractant were significantly lower in the CT group than the C group. CONCLUSIONS: There were similar effects of ASCs on the decrease of anti-mouse CII autoantibody levels between syngeneic and xenogeneic transplantations, and CTLA4Ig-hASCs showed synergistic preventive effects compared with non-transduced hASCs.

Evaluation of tumor microvascular response to brivanib by dynamic contrast-enhanced 7-T MRI in an orthotopic xenograft model of hepatocellular carcinoma.

OBJECTIVE: The purpose of this article is to evaluate the antiangiogenic effects of brivanib using dynamic contrast-enhanced MRI (DCE-MRI) in an orthotopic mouse model of human hepatocellular carcinoma (HCC). MATERIALS AND METHODS: With human HCC (HepG2 cell line) orthotopic nude mouse xenografts, brivanib was administered orally to the treatment group, and the vehicle was administered to the control group for 14 days. DCE-MRI was performed before the start of the therapy and 7 and 14 days after the start of therapy. Treatment-induced changes in tumor volume and microvessel density (MVD) assessed by CD31 immunohistochemistry were analyzed. Perfusion parameters, including volume transfer constant between blood plasma and extravascular extracellular space (K(trans)), fractional extravascular extracellular space per unit volume of tissue (ve), and rate constant between extravascular extracellular space and blood plasma (Kep), were calculated using the two-compartment model. RESULTS: Brivanib shows potent antitumor activity in tumor volume. The mean (± SD) MVD of the tumors was statistically significantly lower in the brivanib-treated group (40.8 ± 17.3 vessels/field) than in the control group (55.2 ± 9.05 vessels/field) (p < 0.05). In the control group, the K(trans) value increased statistically significantly between the baseline and 14 days after treatment (p = 0.048). In the brivanib-treated group, the K(trans) and ve values decreased statistically significantly between baseline and 7 days after treatment (p = 0.024 and p = 0.031, respectively) and between baseline and 14 days after treatment (p = 0.043 and p = 0.018, respectively). The difference between the K(trans) and ve values between baseline and 14 days after treatment showed a statistically significant difference between the two groups (p = 0.004 and p = 0.034, respectively). CONCLUSION: DCE-MRI is feasible in the orthotopic mouse model of human HCC, and it can noninvasively monitor brivanib-induced changes in tumor microvasculature.

Quantitative dynamic contrast-enhanced MRI for mouse models using automatic detection of the arterial input function.

Dynamic contrast-enhanced MRI (DCE-MRI) is widely accepted for the evaluation of cancer. DCE-MRI, a noninvasive measurement of microvessel permeability, blood volume and blood flow, is extremely useful for understanding disease mechanisms and monitoring therapeutic responses in preclinical research. For the accurate quantification of pharmacokinetic parameters using DCE-MRI, determination of the arterial input function (AIF) from a large arterial vessel near the tumor is required. However, a manual determination of AIF in mouse MR images is often difficult because of the small spatial dimensions or the location of the tumor. In this study, we propose an algorithm for the automatic detection of AIF from mouse DCE-MR images using Kendall's coefficient of concordance. The proposed method was tested with computer simulations and then applied to tumor-bearing mice (n = 8). Results from computer simulations showed that the proposed algorithm is capable of categorizing simulated AIF signals according to their noise levels. We found that the resulting pharmacokinetic parameters computed from our method were comparable with those from the manual determination of AIF, with acceptable differences in K(trans) (5.14 ± 3.60%), v(e) (6.02 ± 3.22%), v(p) (5.10 ± 7.05%) and k(ep) (5.38 ± 4.72%). The results of the current study suggest the usefulness of an automatically defined AIF using Kendall's coefficient of concordance for quantitative DCE-MRI in mouse models for cancer evaluation.

Synthesis and evaluation of 1-(4-[¹8F]fluoroethyl)-7-(4'-methyl)curcumin with improved brain permeability for ß-amyloid plaque imaging.

Alzheimer's disease is characterized by the accumulation of ß-amyloid (Aß) plaques and neurofibrillary tangles (NFTs) in the brain. We previously developed [(18)F]fluoropropylcurcumin ([(18)F]FP-curcumin), which demonstrated excellent binding affinity (K(i)=0.07 nM) for Aß(1-40) aggregates and good pharmacokinetics in normal mouse brains. However, its initial brain uptake was poor (0.52% ID/g at 2 min post-injection). Therefore, in the present study, fluorine-substituted 4,4'-bissubstituted or pegylated curcumin derivatives were synthesized and evaluated. Their binding affinities for Aß(1-42) aggregates were measured and 1-(4-fluoroethyl)-7-(4'-methyl)curcumin (1) had the highest binding affinity (K(i)=2.12 nM). Fluorescence staining of Tg APP/PS-1 mouse brain sections demonstrated high and specific labeling of Aß plaques by 1 in the cortex region, which was confirmed with thioflavin-S staining of the same spots in the adjacent brain sections. Radioligand [(18)F]1 was found to have an appropriate partition coefficient (logP(o/w)=2.40), and its tissue distribution in normal mice demonstrated improved brain permeability (1.44% ID/g at 2 min post-injection) compared to that of [(18)F]FP-curcumin by a factor of 2.8 and fast wash-out from mouse brains (0.45% ID/g at 30 min post-injection). These results suggest that [(18)F]1 may hold promise as a PET radioligand for Aß plaque imaging.

Induced neural stem cells from human patient-derived fibroblasts attenuate neurodegeneration in Niemann-Pick type C mice.

BACKGROUND: Niemann-Pick disease type C (NPC) is caused by the mutation of NPC genes, which leads to the abnormal accumulation of unesterified cholesterol and glycolipids in lysosomes. This autosomal recessive disease is characterized by liver dysfunction, hepatosplenomegaly, and progressive neurodegeneration. Recently, the application of induced neural stem cells (iNSCs), converted from fibroblasts using specific transcription factors, to repair degenerated lesions has been considered a novel therapy. OBJECTIVES: The therapeutic effects on NPC by human iNSCs generated by our research group have not yet been studied in vivo; in this study, we investigate those effects. METHODS: We used an NPC mouse model to efficiently evaluate the therapeutic effect of iNSCs, because neurodegeneration progress is rapid in NPC. In addition, application of human iNSCs from NPC patient-derived fibroblasts in an NPC model in vivo can give insight into the clinical usefulness of iNSC treatment. The iNSCs, generated from NPC patient-derived fibroblasts using the SOX2 and HMGA2 reprogramming factors, were transplanted by intracerebral injection into NPC mice. RESULTS: Transplantation of iNSCs showed positive results in survival and body weight change in vivo. Additionally, iNSC-treated mice showed improved learning and memory in behavior test results. Furthermore, through magnetic resonance imaging and histopathological assessments, we observed delayed neurodegeneration in NPC mouse brains. CONCLUSIONS: iNSCs converted from patient-derived fibroblasts can become another choice of treatment for neurodegenerative diseases such as NPC.

cIRCR201-dPBD, a Novel Pyrrolobenzodiazepine Dimer-Containing Site-Specific Antibody-Drug Conjugate Targeting c-Met Overexpression Tumors.

c-Met, as a receptor expressed on the cell membrane, contributes to the growth and metastasis of tumors, as well as angiogenesis, mainly through the hepatocyte growth factor (HGF)/c-Met axis during tumor progression. Although several c-Met inhibitors, including small molecules and monoclonal antibody inhibitors, are currently being investigated, their clinical outcomes have not been promising. Development of an antibody-drug conjugate (ADC) against c-Met could be an attractive therapeutic strategy that would provide superior antitumor efficacy with broad-spectrum c-Met expression levels. In the present study, site-specific drug-conjugate technology was applied to develop an ADC using the human-mouse cross-reactive c-Met antibody and a prodrug pyrrolobenzodiazepine (PBD). The toxin payload was uniformly conjugated to the light-chain C-terminus of the native cIRCR201 antibody (drug-to-antibody ratio = 2), as confirmed using LC-MS. Using a high-throughput screening system, we found that cIRCR201-dPBD exhibited varying sensitivities depending on the expression levels of c-Met, and it induced receptor-mediated endocytosis and toxin-mediated apoptosis in 47 different cancer cell lines. cIRCR201-dPBD also showed significant antitumor activity on the MET-amplified cancer cells using in vivo xenograft models. Therefore, cIRCR201-dPBD could be a promising therapeutic strategy for tumors with c-Met expression.

Double-filtered leukoreduction as a method for risk reduction of transfusion-associated graft-versus-host disease.

BACKGROUND: Transfusion-associated graft-versus-host disease (TA-GvHD) is caused by leukocytes, specifically T cells within a transfused blood product. Currently, the prevention of transfusion-associated graft-versus-host disease is performed by irradiation of blood products. With a sufficient reduction of leukocytes, the risk for TA-GvHD can be decreased. With consistent advances in current state-of-the-art blood filters, we herein propose that double filtration can sufficiently reduce leukocytes to reduce the risk for TA-GvHD. MATERIALS: Thirty RBC concentrates were filtered with leukocyte filters, followed by storage at 1-6 oC for 72 hours, and then a second filtration was performed. Residual leukocytes in the double-filtered RBC units (n = 30) were assessed with flow cytometric methods, and an additional assay with isolated peripheral blood mononuclear cells (PBMCs) (n = 6) was done by both flow cytometric methods and an automated hematology analyzer. Quality of the RBCs after filtration was evaluated by hematological and biochemical tests. In vitro T cell expansion was performed using anti-CD3/CD28-coated Dynabeads or anti-CD3 (OKT3). In vivo experiment for GvHD was performed by using NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. RESULTS: Double-filtered blood products showed residual leukocyte levels below detection limits, which calculated to be below 1200-2500 cells per blood unit. In vitro expansion rate of T cells showed that 6x103 and 1x103 cell-seeded specimens showed 60.8±10.6 fold and 10.2±9.7-fold expansion, respectively. Cell expansion was not sufficiently observed in wells planted with 1x102 or 10 cells. In vivo experiments showed that mice injected with 1x105 or more cells cause fatal GvHD. GvHD induced inflammation was observed in mice injected with 1x104 or more cells. No evidence of GvHD was found in mice injected with 103 cells. CONCLUSIONS: Our study suggests that additional removal of contaminating lymphocytes by a second leukodepletion step may further reduce the risk for TA-GvHD.

Fas mutation reduces obesity by increasing IL-4 and IL-10 expression and promoting white adipose tissue browning.

Brown adipose tissue generates heat via the mitochondrial uncoupling protein UCP1 to protect against obesity and hypothermia. Fas mutant MRL/lpr mice exhibit a significantly leaner phenotype compared to wild type MRL/MpJ mice. In this study, we evaluated the inflammatory cell population in the adipose tissue of MRL/lpr mice, which could potentially influence their lean phenotype. Furthermore, we compared beige fat activity between the MRL/MpJ and MRL/lpr mice. Fas mutation resulted in high body temperature, improved glucose tolerance, and decreased fat mass and adipocyte size. Fas mutation prevented high-fat diet-induced obesity and decreased the white adipose tissue M1:M2 ratio. When mice were fed a high-fat diet, UCP1, IL-4, IL-10, and tyrosine hydroxylase genes had significantly higher expression in Fas-mutant mice than in wild type mice. After a cold challenge, UCP1 expression and browning were also significantly higher in the Fas-mutant mice. In summary, Fas-mutant mice are resistant to high-fat diet-induced obesity due to increased IL-4 and IL-10 levels and the promotion of thermogenic protein activity and browning in their adipose tissues. STAT6 activation might contribute to M2 polarisation by increasing IL-4 and IL-10 levels while increases in M2 and tyrosine hydroxylase levels promote browning in response to Fas mutation.

In vivo 13C magnetic resonance spectroscopy of human brain on a clinical 3 T scanner using [2-13C]glucose infusion and low-power stochastic decoupling.

This study presents the detection of [2-(13)C]glucose metabolism in the carboxylic/amide region in the human brain, and demonstrates that the cerebral metabolism of [2-(13)C]glucose can be studied in human subjects in the presence of severe hardware constraints of widely available 3 T clinical scanners and with low-power stochastic decoupling. In the carboxylic/amide region of human brain, the primary products of (13)C label incorporation from [2-(13)C]glucose into glutamate, glutamine, aspartate, gamma-aminobutyric acid, and N-acetylaspartate were detected. Unlike the commonly used alkanyl region where lipid signals spread over a broad frequency range, the carboxylic carbon signal of lipids was found to be confined to a narrow range centered at 172.5 ppm and present no spectral interference in the absence of lipid suppression. Comparison using phantoms shows that stochastic decoupling is far superior to the commonly used WALTZ sequence at very low decoupling power at 3 T. It was found that glutamine C1 and C5 can be decoupled using stochastic decoupling at 2.2 W, although glutamine protons span a frequency range of approximately 700 Hz. Detailed specific absorption rate analysis was also performed using finite difference time domain numerical simulation.

Elevated endogenous GABA concentration attenuates glutamate-glutamine cycling between neurons and astroglia.

In this study, the relationship between endogenous brain GABA concentration and glutamate-glutamine cycling flux (V (cyc)) was investigated using in vivo (1)H and (1)H{(13)C} magnetic resonance spectroscopy techniques. Graded elevations of brain GABA levels were induced in rat brain after administration of the highly specific GABA-transaminase inhibitor vigabatrin (gamma-vinyl-GABA). The glial-specific substrate [2-(13)C]acetate and (1)H{(13)C} magnetic resonance spectroscopy were used to measure V (cyc) at different GABA levels. Significantly reduced V (cyc) was found in rats pretreated with vigabatrin. The reduction in group mean V (cyc) over the range of GABA concentrations investigated in this study (1.0 +/- 0.3-5.1 +/- 0.5 micromol/g) was found to be nonlinear: Delta V (cyc)/V (cyc) = [GABA (micromol/g)](-0.35 )- 1.0 (r (2) = 0.98). The results demonstrate that V (cyc) is modulated by endogenous GABA levels, and that glutamatergic and GABAergic interactions can be studied in vivo using noninvasive magnetic resonance spectroscopy techniques.

Synthesis and in vivo characterization of 18F-labeled difluoroboron-curcumin derivative for ß-amyloid plaque imaging.

Positron emission tomography imaging of ß-amyloid (Aß) plaques has proven useful in the diagnosis of Alzheimer's disease. A previous study from our group showed that 4'-O-[18F]fluoropropylcurcumin has poor brain permeability, which is thought to be due to its rapid metabolism. In this study, we synthesized difluoroboron complexes of fluorine-substituted curcumin derivatives (1-4) and selected one of them based on the in vitro binding assays. The selected ligand 2 was found to distinctively stain Aß plaques in APP/PS1 transgenic mouse brain sections. Radioligand [18F]2 was synthesized via a two-step reaction consisting of [18F]fluorination and subsequent aldol condensation. Biodistribution and metabolism studies indicated that radioligand [18F]2 was converted to polar radioactive products and trapped in the normal mouse brain. In contrast, optical images of mice acquired after injection of 2 showed moderate fluorescence signal intensity in the mouse brain at 2 min with a decrease in the signal within 30 min. In the ex vivo optical images, the fluorescence signals in major tissues disappeared within 30 min. Taken together, these results suggest that [18F]2 may be converted to polar 18F-labeled blue-shifted fluorescent products. Further structural modifications are thus needed to render the radioligand metabolically stable.

Measuring N-acetylaspartate synthesis in vivo using proton magnetic resonance spectroscopy.

N-Acetylaspartate (NAA) is an important marker of neuronal function and viability that can be measured using magnetic resonance spectroscopy (MRS). In this paper, we proposed a method to measure NAA synthesis using proton MRS with infusion of uniformly (13)C-labeled glucose, and demonstrated its feasibility in an in vivo study of the rat brain. The rate of (13)C-label incorporation into the acetyl group of NAA was measured using a localized, long echo-time proton MRS method. Signals from the (13)C satellites of the main NAA methyl protons at 2.02 ppm were continuously monitored for 10h. Quantification of the data based on a linear kinetic model showed that NAA synthesis rate in isoflurane-anesthetized rats was 0.19+/-0.02 micromol/g/h (mean+/-standard deviation, n=12).

Inverse polarization transfer for detecting in vivo 13C magnetization transfer effect of specific enzyme reactions in 1H spectra.

The wide chemical shift dispersion and long T(1) of (13)C have allowed determination of in vivo magnetization transfer effects caused by aspartate aminotransferase and lactate dehydrogenase reactions using (13)C magnetic resonance spectroscopy. In this report, we demonstrate that these effects can be observed in the proton spectra by transferring the equilibrium magnetization of (13)C via the one-bond scalar coupling between (13)C and (1)H using an inverse insensitive nuclei enhanced by polarization transfer-based heteronuclear polarization transfer method. This inverse method allows a combination of the advantages of the long (13)C T(1) for maximum magnetization transfer and the high sensitivity of proton detection. The feasibility of this in vivo inverse polarization transfer approach was evaluated for detecting the (13)C magnetization transfer effect of aspartate aminotransferase and lactate dehydrogenase reactions from a 72.5-microl voxel in the rat brain at 11.7 T.

Active contour configuration model for estimating the posterior ablative margin in image fusion of real-time ultrasound and 3D ultrasound or magnetic resonance images for radiofrequency ablation: an experimental study.

PURPOSE: The purpose of this study was to evaluate the accuracy of an active contour model for estimating the posterior ablative margin in images obtained by the fusion of real-time ultrasonography (US) and 3-dimensional (3D) US or magnetic resonance (MR) images of an experimental tumor model for radiofrequency ablation. METHODS: Chickpeas (n=12) and bovine rump meat (n=12) were used as an experimental tumor model. Grayscale 3D US and T1-weighted MR images were pre-acquired for use as reference datasets. US and MR/3D US fusion was performed for one group (n=4), and US and 3D US fusion only (n=8) was performed for the other group. Half of the models in each group were completely ablated, while the other half were incompletely ablated. Hyperechoic ablation areas were extracted using an active contour model from real-time US images, and the posterior margin of the ablation zone was estimated from the anterior margin. After the experiments, the ablated pieces of bovine rump meat were cut along the electrode path and the cut planes were photographed. The US images with the estimated posterior margin were compared with the photographs and post-ablation MR images. The extracted contours of the ablation zones from 12 US fusion videos and post-ablation MR images were also matched. RESULTS: In the four models fused under real-time US with MR/3D US, compression from the transducer and the insertion of an electrode resulted in misregistration between the real-time US and MR images, making the estimation of the ablation zones less accurate than was achieved through fusion between real-time US and 3D US. Eight of the 12 post-ablation 3D US images were graded as good when compared with the sectioned specimens, and 10 of the 12 were graded as good in a comparison with nicotinamide adenine dinucleotide staining and histopathologic results. CONCLUSION: Estimating the posterior ablative margin using an active contour model is a feasible way of predicting the ablation area, and US/3D US fusion was more accurate than US/MR fusion.

Therapeutic effects of anti-CD154 antibody in cynomolgus monkeys with advanced rheumatoid arthritis.

Rheumatoid arthritis is one major chronic inflammatory systemic autoimmune disease. The CD154-CD40 interactions play a critical role in the regulation of immune responses and the maintenance of autoimmunity. Therefore, we aimed to determine whether anti-CD154 antibody treatment show positive effects on immunomodulation and clinical improvement of sustained severe rheumatoid arthritis in cynomolgus monkeys. Arthritis was induced using chicken type II collagen (CII) and arthritic monkey were divided into control and anti-CD154 treatment groups based on their concentrations of anti-CII antibodies on week 7 post-immunization. Blood and tissue samples were collected on week 16 post-immunization. Anti-CD154 antibody treatment improved arthritis and movement, and significantly decreased the numbers of proliferating B cells and the serum levels of anti-type II collagen antibody and sCD154 compared with non-treatment group. Further anti-CD154 antibody treatment significantly decreased the percentage of CD4+ cells and the ratio of CD4+ to CD8+ T cells and significantly increased the percentage of CD8+ cells and effector memory CD8+ cells in peripheral blood. We have shown for the first time in a nonhuman primate model of RA that CD154 blockade has beneficial effects. This study might be valuable as preclinical data of CD154 blockade in nonhuman primate models of severe rheumatoid arthritis.

Quantification of cortical GABA-glutamine cycling rate using in vivo magnetic resonance signal of [2-13C]GABA derived from glia-specific substrate [2-13C]acetate.

Brain [2-(13)C]gamma-aminobutyric acid (GABA) signal derived from the glia-specific substrate [2-(13)C]acetate reflects the extent of the GABA-glutamine neurotransmitter cycling between GABAergic neurons and glial cells. We report, for the first time, in vivo quantification of the GABA-glutamine cycling flux. The GABA-glutamine cycling flux rate was determined to be 1.8+/-0.4 micromol/(gh) (mean+/-S.D., n=6, approximately 6% of total tricarboxylic acid cycle rate) in the neocortex of vigabatrin-treated rats. The relatively small magnitude of glial contribution to the clearance of extracellular GABA measured in this study provided in vivo evidence to support the concept of a significant neuronal reuptake of GABA, which short-circuits the GABA-glutamine cycling pathway for repletion of released neurotransmitter GABA.

Relayed (13)C magnetization transfer: detection of malate dehydrogenase reaction in vivo.

Malate dehydrogenase catalyzes rapid interconversion between dilute metabolites oxaloacetate and malate. Both oxaloacetate and malate are below the detection threshold of in vivo MRS. Oxaloacetate is also in rapid exchange with aspartate catalyzed by aspartate aminotransferase, the latter metabolite is observable in vivo using (13)C MRS. We hypothesized that the rapid turnover of oxaloacetate can effectively relay perturbation of magnetization between malate and aspartate. Here, we report indirect observation of the malate dehydrogenase reaction by saturating malate C2 resonance at 71.2 ppm and detecting a reduced aspartate C2 signal at 53.2 ppm due to relayed magnetization transfer via oxaloacetate C2 at 201.3 ppm. Using this strategy the rate of the cerebral malate dehydrogenase reaction was determined to be 9+/-2 micromol/g wet weight/min (means+/-SD, n=5) at 11.7 Tesla in anesthetized adult rats infused with [1,6-(13)C(2)]glucose.