To compare metabolic magnetic resonance (MR) imaging findings (ie, quantification of tumor choline concentration) with percentage of necrosis on pathologic examination in rabbits bearing VX2 liver ...tumors.
VX2 tumors were implanted in the livers of 16 rabbits. MR imaging was performed with a 1.5-T MR scanner and extremity coil, and a hydrogen-1 ((1)H) proton MR spectroscopy ((1)H MRS) imaging protocol was used. Rabbits were euthanized immediately after imaging, and the tumor was harvested and sliced at 4-mm intervals in the axial plane. Choline concentration was calculated and was compared with the percentage of tumor necrosis on pathologic examination.
Mean tumor size at pathologic examination was 16 mm (range, 12-22 mm). Mean percentage of necrosis at pathologic examination was 22% (range, 4%-44%). Choline concentration showed a relatively high inverse correlation with percentage of necrosis on pathologic examination, with an r value of 0.78 (P < .002).
Choline concentration showed a relatively high inverse correlation with tumor necrosis on pathologic examination. Therefore, (1)H MRS may be useful to assess tumor necrosis.
Background and aims
Varicella zoster virus (VZV) reactivation following hematopoietic stem cell transplantation (HSCT) may cause significant morbidity and mortality. We undertook a retrospective ...study to determine the frequency and risk factors associated with VZV reactivation, including underlying disease, the use of fludarabine in high‐risk leukemia chemotherapy protocols, and immune status before HSCT.
Patients and methods
We studied 163 children who underwent a first HSCT between 2002 and 2008, before introduction of routine VZV prophylaxis on our unit. VZV diagnosis was based on clinical features and supported by polymerase chain reaction on plasma and/or vesical fluid. Patient data and possible risk factors pre‐ and post HSCT were recorded and compared using a multivariate regression analysis.
Results
Within this cohort, 41 (25%) patients developed VZV reactivation during the first year after transplantation at a median of 60 days post HSCT. VZV reactivation occurred more often within the subgroup of patients with acute leukemia compared with the remainder of patients (38% vs. 15%, P < 0.01). Multivariate Cox regression analysis revealed that, besides positive VZV serology in patients pre‐HSCT (P = 0.03), acute leukemia as the indication for HSCT remained the only independent risk factor for VZV reactivation (P = 0.025, odds ratio 2.5, 95% confidence interval 1.1–5.6). This was associated with low pre‐transplant T‐cell counts, especially in the CD4+ subset. No differences were found in relation to donor type, age, or use of serotherapy.
Conclusion
VZV reactivation after HSCT predominates in acute leukemia patients and is associated with low T CD4+ lymphocyte counts. This finding demonstrates the impact of pre‐HSCT host immune suppression on VZV reactivation patterns after HSCT.
To evaluate the role of diffusion-weighted imaging in differentiating between hepatic hemangiomas, both typical and atypical, and other hypervascular liver lesions.
Retrospective review of 182 ...hypervascular liver lesions in 117 patients was performed. Diffusion and contrast-enhanced magnetic resonance imaging were performed using a 1.5-T unit. Imaging protocol consisted of T2-weighted fast spin-echo images, breath-hold diffusion-weighted echo-planar images, and breath-hold unenhanced and contrast-enhanced T1-weighted 3-dimensional fat-suppressed spoiled gradient-echo images in the arterial phase (20 seconds) and portal venous phase (60 seconds). Signal intensity changes and apparent diffusion coefficient (ADC) values were evaluated for all lesions. Unpaired t test was used to compare the mean ADC values for different lesions, and statistical significance was set at P < 0.01. Receiver operating characteristic analysis was used to determine the accuracy of diffusion-weighted imaging in differentiating hemangiomas from other hypervascular liver lesions.
Lesions included typical and atypical hemangioma (n = 38), hepatocellular carcinoma (HCC; n = 58), focal nodular hyperplasia (FNH; n = 22), and neuroendocrine tumor metastasis (NET; n = 64) with a mean tumor size of 5.3 cm. Mean ADC value for hemangioma, HCC, FNH, and NET was 2.29 x 10(-3), 1.55 x 10(-3), 1.65 x 10(-3), and 1.43 x 10(-3) mm2/s, respectively. There was a statistically significant difference in the ADC value of hemangioma compared with that of FNH (P < 0.001), HCC (P < 0.001), and NET (P < 0.001), respectively. The area under the receiver operating characteristic curve was 0.91.
Diffusion-weighted magnetic resonance imaging and ADC maps can provide rapid quantifiable information to differentiate typical and atypical hemangiomas from other hypervascular liver lesions.
The Irish potato famine pathogen Phytophthora infestans is predicted to secrete hundreds of effector proteins. To address the challenge of assigning biological functions to computationally predicted ...effector genes, we combined allele mining with high-throughput in planta expression. We developed a library of 62 infection-ready P. infestans RXLR effector clones, obtained using primer pairs corresponding to 32 genes and assigned activities to several of these genes. This approach revealed that 16 of the 62 examined effectors cause phenotypes when expressed inside plant cells. Besides the well-studied AVR3a effector, two additional effectors, PexRD8 and PexRD36₄₅₋₁, suppressed the hypersensitive cell death triggered by the elicitin INF1, another secreted protein of P. infestans. One effector, PexRD2, promoted cell death in Nicotiana benthamiana and other solanaceous plants. Finally, two families of effectors induced hypersensitive cell death specifically in the presence of the Solanum bulbocastanum late blight resistance genes Rpi-blb1 and Rpi-blb2, thereby exhibiting the activities expected for Avrblb1 and Avrblb2. The AVRblb2 family was then studied in more detail and found to be highly variable and under diversifying selection in P. infestans. Structure-function experiments indicated that a 34-amino acid region in the C-terminal half of AVRblb2 is sufficient for triggering Rpi-blb2 hypersensitivity and that a single positively selected AVRblb2 residue is critical for recognition by Rpi-blb2.
Plasma D-dimer measurement is used in the assessment of the clinical probability of pulmonary embolism (PE), in order to minimize the requirement for pulmonary computed tomography angiography (CTA).
...To evaluate whether doubling the threshold value of serum D-dimer from 500 μg/L to 1000 μg/L could safely reduce utilization of pulmonary CTA to exclude PE in our emergency department patient population.
Emergency department patients evaluated for PE with a quantitative D-dimer assay and pulmonary CTA were eligible for inclusion. D-dimer values were retrospectively collected in all included patients. Pulmonary CT angiograms were reviewed and scored as positive or negative for PE. Receiver-operating characteristic (ROC) analysis was used to determine the accuracy of quantitative D-dimer measurements in differentiating between positive and negative PE patients as per CTA.
A total of 237 consecutive patients underwent pulmonary CTA and had a D-dimer measurement performed. Median D-dimer level was 1007 μg/L and in 11 (5%) patients the pulmonary CT CTA was positive for PE. The ROC curve showed an area under the curve (AUC) of 0.91 (P < 0.0001). Increasing the D-dimer threshold value of 500 μg/L to 1000 μg/L increased the specificity from 8% to 52% without changing the sensitivity.
Adjusting the D-dimer cut-off value for the emergency department community population and patient age increases the yield and specificity of the ELISA D-dimer assay for the exclusion of PE without reducing sensitivity.
Large variation exists in mitochondrial DNA (mtDNA) not only between but also within individuals. Also in human cancer, tumor-specific mtDNA variation exists. In this work, we describe the comparison ...of four methods to extract mtDNA as pure as possible from frozen tumor tissue. Also, three state-of-the-art methods for sensitive detection of mtDNA variants were evaluated. The main aim was to develop a procedure to detect low-frequent single-nucleotide mtDNA-specific variants in frozen tumor tissue. We show that of the methods evaluated, DNA extracted from cytosol fractions following exonuclease treatment results in highest mtDNA yield and purity from frozen tumor tissue (270-fold mtDNA enrichment). Next, we demonstrate the sensitivity of detection of low-frequent single-nucleotide mtDNA variants (≤1% allele frequency) in breast cancer cell lines MDA-MB-231 and MCF-7 by single-molecule real-time (SMRT) sequencing, UltraSEEK chemistry based mass spectrometry, and digital PCR. We also show de novo detection and allelic phasing of variants by SMRT sequencing. We conclude that our sensitive procedure to detect low-frequent single-nucleotide mtDNA variants from frozen tumor tissue is based on extraction of DNA from cytosol fractions followed by exonuclease treatment to obtain high mtDNA purity, and subsequent SMRT sequencing for (de novo) detection and allelic phasing of variants.
Late blight caused by
Phytophthora infestans
is the most important disease of potato. Many efforts have been made to understand molecular mechanism of the durable resistance to address the challenge ...raised by rapid evolution of the pathogen. A pathogenesis related protein (PR) gene
StPRp27
was previously isolated from the potato leaves challenged by
P. infestans
. The sequence analysis and expression pattern reveal that
StPRp27
may be associated with resistance to
P. infestans
. In present research, transient expression of
StPRp27
in
Nicotiana benthamiana
enhanced resistance to
P. infestans
isolates 99189 and PY23 indicating its potential contribution to the disease resistance. These findings were also confirmed by over-expression of
StPRp27
in potato cv. E-potato 3, which significantly slowed down the development of the disease after inoculation with a mixture of
P
.
infestans
races. Further, silencing of
StPRp27
homologous genes in
N. benthamiana
harboring dominant
Phytophthora
resistance gene
Rpi-blb1
or
Rpi-blb2
showed no effects on the resistance triggered by these
R
genes. Our results suggest that
StPRp27
contributes to a race-nonspecific resistance against
P. infestans
by inhibiting the disease development and has a potential use in selection and breeding for durable resistance to late blight.
Late blight, caused by Phytophthora infestans, is one of the most devastating diseases in cultivated potato. Breeding of new potato cultivars with high levels of resistance to P. infestans is ...considered the most durable strategy for future potato cultivation. In this study, we report the identification of a new late-blight resistance (R) locus from the wild potato species Solanum bulbocastanum. Using several different approaches, a high-resolution genetic map of the new locus was generated, delimiting Rpi-blb3 to a 0.93 cM interval on chromosome 4. One amplification fragment length polymorphism marker was identified that cosegregated in 1,396 progeny plants of an intraspecific mapping population with Rpi-blb3. For comparative genomics purposes, markers linked to Rpi-blb3 were tested in mapping populations used to map the three other late-blight R loci Rpi-abpt, R2, and R2-like also to chromosome 4. Marker order and allelic conservation suggest that Rpi-blb3, Rpi-abpt, R2, and R2-like reside in the same R gene cluster on chromosome 4 and likely belong to the same gene family. Our findings provide novel insights in the evolution of R gene clusters conferring late-blight resistance in Solanum spp.
The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with ...developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.
A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.
NBS profiling is a method for the identification of resistance gene analog (RGA) derived fragments. Here we report the use of NBS profiling for the genome wide mapping of RGA loci in potato. NBS ...profiling analyses on a minimal set of F1 genotypes of the diploid mapping population previously used to generate the ultra dense (UHD) genetic map of potato, allowed us to efficiently map polymorphic RGA fragments relative to 10,000 existing AFLP markers. In total, 34 RGA loci were mapped, of which only 13 contained RGA sequences homologous to RGAs genetically positioned at approximately similar positions in potato or tomato. The remaining RGA loci mapped either at approximate chromosomal regions previously shown to contain RGAs in potato or tomato without sharing homology to these RGAs, or mapped at positions not yet identified as RGA-containing regions. In addition to markers representing RGAs with unknown functions, segregating markers were detected that were closely linked to four functional R genes that segregate in the UHD mapping population. To explore the potential of NBS profiling in RGA transcription analyses, RNA isolated from different tissues was used as template for NBS profiling. Of all the fragments amplified approximately 15% showed putative intensity or absent/present differences between different tissues suggesting putative tissue specific RGA or R gene transcription. Putative absent/present differences between individuals were also found. In addition to being a powerful tool for generating candidate gene markers linked to R gene loci, NBS profiling, when applied to cDNA, can be instrumental in identifying those members of an R gene cluster that are transcribed, and thus putatively functional.
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