Test-Retest Reproducibility of Reduced-Field-of-View Density-Weighted CRT MRSI at 3T.

Quantifying an imaging modality's ability to reproduce results is important for establishing its utility. In magnetic resonance spectroscopic imaging (MRSI), new acquisition protocols are regularly introduced which improve upon their precursors with respect to signal-to-noise ratio (SNR), total acquisition duration, and nominal voxel resolution. This study has quantified the within-subject and between-subject reproducibility of one such new protocol (reduced-field-of-view density-weighted concentric ring trajectory (rFOV-DW-CRT) MRSI) by calculating the coefficient of variance of data acquired from a test-retest experiment. The posterior cingulate cortex (PCC) and the right superior corona radiata (SCR) were selected as the regions of interest (ROIs) for grey matter (GM) and white matter (WM), respectively. CVs for between-subject and within-subject were consistently around or below 15% for Glx, tCho, and Myo-Ins, and below 5% for tNAA and tCr.

Fast in vivo 23 Na imaging and T2∗ mapping using accelerated 2D-FID UTE magnetic resonance spectroscopic imaging at 3 T: Proof of concept and reliability study.

PURPOSE: To implement an accelerated MR-acquisition method allowing to map T2∗ relaxation and absolute concentration of sodium within skeletal muscles at 3T. METHODS: A fast-UTE-2D density-weighted concentric-ring-trajectory 23 Na-MRSI technique was used to acquire 64 time points of FID with a spectral bandwidth of 312.5 Hz with an in-plane resolution of 2.5 × 2.5 mm2 in ~15 min. The fast-relaxing 23 Na signal was localized with a single-shot, inversion-recovery-based, non-echo (SIRENE) outer volume suppression (OVS) method. The sequence was verified using simulation and phantom studies before implementing it in human calf muscles. To evaluate the 2D-SIRENE-MRSI (UTE = 0.55 ms) imaging performance, it was compared to a 3D-MRI (UTE = 0.3 ms) sequence. Both data sets were acquired within 2 same-day sessions to assess repeatability. The T2∗ values were fitted voxel-by-voxel using a biexponential model for the 2D-MRSI data. Finally, intra-subject coefficients of variation (CV) were estimated. RESULTS: The MRSI-FID data allowed us to map the fast and slow components of T2∗ in the calf muscles. The spatial distributions of 23 Na concentration for both MRSI and 3D-MRI acquisitions were significantly correlated (P < .001). The test-retest analysis rendered high repeatability for MRSI with a CV of 5%. The mean T2Fast∗ in muscles was 0.7 ± 0.1 ms (contribution fraction = 37%), whereas T2Slow∗ was 13.2 ± 0.2 ms (63%). The mean absolute muscle 23 Na concentration calculated from the T2∗ -corrected data was 28.6 ± 3.3 mM. CONCLUSION: The proposed MRSI technique is a reliable technique to map sodium's absolute concentration and T2∗ within a clinically acceptable scan time at 3T.

Recurrent vaginal shedding of herpes simplex type 2 virus in the mouse and effects of antiviral therapy.

A mouse model of recurrent herpes simplex type 2 (HSV-2) would improve our understanding of the immunobiology of recurrent disease and provide a useful model for evaluating antiviral treatments. We developed a model to evaluate recurrent vaginal HSV-2 shedding using high-dose acyclovir (ACV) therapy beginning at 3 days post infection (dpi). Treatment with 150mg/kg of ACV for 10 days increased survival to 80% following vaginal challenge with HSV-2 strain 186 and to 100% after challenge with strain MS. We then evaluated recurrent vaginal HSV-2 shedding in surviving mice. Although infectious virus was not detected in vaginal samples after 21dpi, viral DNA was detectable by PCR in 80% of mice (47/59) on at least 1 day, while no animal was positive for virus on every day. ACV therapy administered from day 21 to 31 significantly reduced recurrent virus shedding during this period from 7.3% (8/109 swabs) to 0.8% (1/126 swabs) (p=0.013). Lastly, ACV-rescued HSV-2-infected mice treated with cyclophosphamide at 35 and 38dpi rapidly succumbed, indicating that this model can be used to study immune control of the persistent infection. Thus, this model provides an inexpensive model for evaluating therapeutic strategies and immune control of persistent HSV.

The adjuvant CLDC increases protection of a herpes simplex type 2 glycoprotein D vaccine in guinea pigs.

Herpes simplex virus (HSV) infections are common but there is no vaccine available. We evaluated cationic liposome-DNA complexes (CLDC) as an adjuvant for an HSV gD2 vaccine and compared it to an MPL/Alum adjuvant in a guinea pig model of genital herpes. The addition of CLDC to the gD2 vaccine significantly decreased acute and recurrent disease and most importantly the number of days with recurrent virus shedding compared to gD2 alone. Reductions in these outcomes were also detected when gD2+CLDC was compared to gD2+MPL/Alum. When the vaccine and adjuvants were evaluated as therapeutic vaccines, they were ineffective. CLDC enhanced protection compared to MPL/Alum and is the first vaccine to reduce recurrent virus shedding, a key to decreasing the spread of HSV-2.

Potent adjuvant activity of cationic liposome-DNA complexes for genital herpes vaccines.

Development of a herpes simplex virus (HSV) vaccine is a priority because these infections are common. It appears that potent adjuvants will be required to augment the immune response to subunit HSV vaccines. Therefore, we evaluated cationic liposome-DNA complexes (CLDC) as an adjuvant in a mouse model of genital herpes. Using a whole-virus vaccine (HVAC), we showed that the addition of CLDC improved antibody responses compared to vaccine alone. Most important, CLDC increased survival, reduced symptoms, and decreased vaginal virus replication compared to vaccine alone or vaccine administered with monophosphoryl lipid A (MPL) plus trehalose dicorynomycolate (TDM) following intravaginal challenge of mice. When CLDC was added to an HSV gD2 vaccine, it increased the amount of gamma interferon that was produced from splenocytes stimulated with gD2 compared to the amount produced with gD2 alone or with MPL-alum. The addition of CLDC to the gD2 vaccine also improved the outcome following vaginal HSV type 2 challenge compared to vaccine alone and was equivalent to vaccination with an MPL-alum adjuvant. CLDC appears to be a potent adjuvant for HSV vaccines and should be evaluated further.

Methylation-controlled J protein promotes c-Jun degradation to prevent ABCB1 transporter expression.

Methylation-controlled J protein (MCJ) is a newly identified member of the DnaJ family of cochaperones. Hypermethylation-mediated transcriptional silencing of the MCJ gene has been associated with increased chemotherapeutic resistance in ovarian cancer. However, the biology and function of MCJ remain unknown. Here we show that MCJ is a type II transmembrane cochaperone localized in the Golgi network and present only in vertebrates. MCJ is expressed in drug-sensitive breast cancer cells but not in multidrug-resistant cells. The inhibition of MCJ expression increases resistance to specific drugs by inducing expression of the ABCB1 drug transporter that prevents intracellular drug accumulation. The induction of ABCB1 gene expression is mediated by increased levels of c-Jun due to an impaired degradation of this transcription factor in the absence of MCJ. Thus, MCJ is required in these cells to prevent c-Jun-mediated expression of ABCB1 and maintain drug response.

Cloning and functional characterization of allelic variation in the porcine prolactin receptor.

Prolactin (PRL) regulates various functions in pigs including reproduction, mammary development and lactation. We used 5'-rapid amplification of cDNA ends (5'-RACE) to clone three full-length alleles of the porcine PRL receptor (pPRLR) from Landrace (alleles LR2 and LR4) and Yucatan miniature (MP) pigs, corresponding to the A and B alleles previously reported to be associated with reproductive traits. When expressed in Chinese hamster ovary (CHO-K1) cells, all three pPRLRs transduced differentiation signals to a beta-casein promoter with the same effectiveness, where human growth hormone (hGH) and porcine PRL (pPRL) were more effective ligands than ovine PRL (oPRL). The pPRLR had a lower binding affinity for oPRL than pPRL while binding affinity for hGH was not different between the three pPRLR variants. The pPRLRs primarily localized to the cytoplasm with perinuclear concentration. In conclusion, we have cloned three allelic variants of the pPRLR and have functionally characterized these as different from the hPRLR. However, our data do not support the proposal that allelic variation of the pPRLR confers functional differences in vivo.

p38 mitogen-activated protein kinase mediates the Fas-induced mitochondrial death pathway in CD8+ T cells.

The p38 mitogen-activated protein kinase (MAPK) signaling pathway can be activated by a variety of stress stimuli such as UV radiation and osmotic stress. The regulation and role of this pathway in death receptor-induced apoptosis remain unclear and may depend on the specific death receptor and cell type. Here we show that binding of Fas ligand to Fas activates p38 MAPK in CD8+ T cells and that activation of this pathway is required for Fas-mediated CD8+ T-cell death. Active p38 MAPK phosphorylates Bcl-xL and Bcl-2 and prevents the accumulation of these antiapoptotic molecules within the mitochondria. Consequently, a loss of mitochondrial membrane potential and the release of cytochrome c lead to the activation of caspase 9 and, subsequently, caspase 3. Therefore, the activation of p38 MAPK is a critical link between Fas and the mitochondrial death pathway and is required for the Fas-induced apoptosis of CD8+ T cells.