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A reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed for the detection of Apple chlorotic leaf spot virus (ACLSV) and Apple stem pitting virus (ASPV), two important viruses frequently occurring in pear trees. A set of four RT-LAMP primers designed based on the highly conserved region of each CP gene of the two viruses showed high specificity and feasibility for ACLSV and ASPV detections. The RT-LAMP assays for ACLSV and ASPV in pear samples were 104 and 103 times more sensitive than that of conventional RT-PCR assays. The RT-LAMP under optimal reaction condition was subsequently utilized in the detection of the two viruses in-vitro cultures of pear and field pear samples. This study provides a rapid and sensitive tool to determine the infection statues of the two viruses in pear certification program.

A highly sensitive nested multiplex reverse transcription-polymerase chain reaction (nmRT-PCR) assay was developed for the simultaneous detection of Apple chlorotic leaf spot virus (ACLSV), Apple stem grooving virus (ASGV) and Apple stem pitting virus (ASPV) infecting pear trees. In the assay, a set of three forward primers specific to each of the three viruses and a universal reverse primer was used as external primers in the first-round PCR, which was followed by a second-round PCR developed previously. The nmRT-PCR assay was 104 times more sensitive than conventional mRT-PCR assay in detecting the three viruses in in vitro pear plantlets. This assay was subsequently used to detect these viruses in leaf and bark samples of cultivated and wild pear trees from orchards and demonstrated to be highly sensitive and reliable. This is the first report describing a use of nmRT-PCR for the sensitive and simultaneous detection of the three viruses infecting pear plants. The assay would be useful for the certification of pear planting materials and surveillance of nursery stocks.

To evaluate the utility of dual-energy spectral computed tomography (CT) and low-iodine intake in CT angiography (CTA) of deep inferior epigastric perforator (DIEP) flaps.In this prospective study, 40 patients with a BMI28.0 kg/m(2) underwent CTA examination for breast reconstruction and were randomly assigned into two groups (n=20 for each group) as follows: Group A was submitted to dual-energy spectral CT and iodixanol (270 mg I/mL) and Group B was submitted to conventional high iodine contrast agent iohexol (350 mg I/mL). The volume CT dose index (CTDIvol ) and dose length product were recorded and the effective dose (ED) was calculated. The best mono-spectrum images of Group A were selected according to the optimal contrast to noise ratio (CNR). Both mono-spectrum images of Group A and polychromatic images of Group B were used to reconstruct maximum intensity projection (MIP) and volume rendering (VR) images of the perforating artery, respectively. Two radiologists evaluated subjective image quality using a 4-point score. The diameter of the perforating artery, CT value and SD value for the common femoral artery were measured and the CNR was calculated. The total iodine intake and radiation doses of the two groups were calculated and compared.The best mono-spectrum energy with the optimal CNR of the perforating artery was 63 keV. The CT value of common femoral artery in Group A (380.96±42.75HU) was 7.40% higher than in Group B (354.71±42.01 HU) but with no statistical significance (P.05). The CNR of the common femoral artery in Group A (23.84±6.73) was 6.88% lower than in Group B (25.60±6.20), with no significant difference (P.05). The diameters of the perforator vessels were 2.44±0.15 and 2.49±0.14 mm, respectively, with no significant difference (P.05). Subjective image qualities for the two groups were both good for diagnostics, and the scores for Group A and Group B were (3.88±0.28) and (3.93±0.18), respectively. The scores of the two radiologists were consistent (kappa=0.634). The effective radiation dose in Group A (9.09±0 mSv) was 10.62% lower than in Group B (10.17±1.91 mSv). The total iodine intake in Group A (27 000 mg) was 22.86% lower than in Group B (35 000 mg).The combination of dual-energy spectral CT and low-iodine intake in CTA of DIEP flap examination with the optimal CNR technology can meet the requirements of clinical diagnostics, with a 22.86% reduction in total iodine intake and an 11.01% reduction in radiation dose.

A multiplex RT-PCR (mRT-PCR) assay was developed for detection and differentiation of the Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV) and Apple chlorotic leaf spot virus (ACLSV), which are viruses frequently occurring in pear trees. Different combinations of mixed primer pairs were tested for their specificity and sensitivity for the simultaneous detection of the three viruses. Three primer pairs were used to amplify their fragments of 247bp, 358bp and 500bp, respectively. The primer pair for ASPV was designed in this work, while the primer pairs for ACLSV and ASGV were from previous reports. The sensitivity and specificity of the mRT-PCR assay for the three viruses were comparable to that of each uniplex RT-PCR. The mRT-PCR was applied successfully for the detection of three viruses in leaves of pear and apple plants, but was unreliable in the detection of ASGV in dormant barks. In conclusion, this mRT-PCR provides a useful tool for the routine and rapid detection and the differentiation of three pear viruses.