Quantitative Assessment of Breast Tumor: Comparison of Four Methods of Positioning Region of Interest for Synthetic Relaxometry and Diffusion Measurement

RATIONALE AND OBJECTIVES

To compare the differences in apparent diffusion coefficient (ADC) and synthetic magnetic resonance (MR) measurements of four region of interest (ROI) placement methods for breast tumor and to investigate their diagnostic performance.

METHODS

110 (70 malignant, 40 benign) newly diagnosed breast tumors were evaluated. The patients underwent 3.0 T MR examinations including diffusion-weighted imaging and synthetic MR. Two radiologists independently measured ADCs, T1 relaxation time (T1), T2 relaxation time (T2), and proton density (PD) using four ROI methods: round, square, freehand, and whole-tumor volume (WTV). The interclass correlation coefficient (ICC) was used to assess their measurement reliability. Diagnostic performance was evaluated using multivariate logistic regression analysis and the receiver operating characteristic (ROC) curves.

RESULTS

The mean values of all ROI methods showed good or excellent interobserver reproducibility (0.79-0.99) and showed the best diagnostic performance compared to the minimum and maximum values. The square ROI exhibited superior performance in differentiating between benign from malignant breast lesions, followed by the freehand ROI. T2, PD, and ADC values were significantly lower in malignant breast lesions compared to benign ones for all ROI methods (p < 0.05). Multiparameters of T2 + ADC demonstrated the highest AUC values (0.82-0.95), surpassing the diagnostic efficacy of ADC or T2 alone (p < 0.05).

CONCLUSION

ROI placement significantly influences ADC and synthetic MR values measured in breast tumors. Square ROI and mean values showed superior performance in differentiating benign and malignant breast lesions. The multiparameters of T2 + ADC surpassed the diagnostic efficacy of a single parameter.

A Novel DNA Aptamer Probe Recognizing Castration Resistant Prostate Cancer in vitro and in vivo Based on Cell-SELEX

Background

Early recognition of castration-resistant state is of significance for timely adjustment of treatment regimens and improvement of prognosis.

Purpose

This study aims to screen new aptamers CRda8 and CRda21 which recognize castration resistant prostate cancer (CRPC) cells with high affinity and specificity by SELEX technology.

Methods

The enrichment of specific aptamer candidates was monitored by flow cytometric analysis. The affinity and specificity of aptamer candidates were evaluated by flow cytometry and immunofluorescence assay. MR imaging of CRda21-conjugated polyethylene glycol (PEG)-Fe3O4 nanoparticles to CRPC was further explored in vivo.

Results

Both aptamers showed high specificity to target cells with dissociation constants in the nanomolar range, and did not recognize other tested cells. The staining of clinical tissue sections with fluorescent dye labeled aptamers showed that sections from CRPC exhibited stronger fluorescence while sections from benign prostatic hyperplasia and androgen dependent prostate cancer did not exhibit notable fluorescence. In vivo MRI demonstrated that CRda21-conjugated PEG-Fe3O4 had good affinity to CRPC and produced strong T2WI signal intensity reduction distinguished from peritumoral tissue.

Conclusion

The high affinity and specificity of CRda8 and CRda21 make the aptamer hold potential for early recognition of castration-resistant state and diagnosis of CRPC at the cellular level.

Synthetic MRI and amide proton transfer-weighted MRI for differentiating between benign and malignant sinonasal lesions

OBJECTIVES

To explore the value of the synthetic MRI (SyMRI), combined with amide proton transfer-weighted (APTw) MRI for quantitative and morphologic assessment of sinonasal lesions, which could provide relative scale for the quantitative assessment of tissue properties.

METHODS

A total of 80 patients (31 malignant and 49 benign) with sinonasal lesions, who underwent the SyMRI and APTw examination, were retrospectively analyzed. Quantitative parameters (T1, T2, proton density (PD)) and APT % were obtained through outlining the region of interest (ROI) and comparing the two groups utilizing independent Student t test or a Wilcoxon test. Receiver operating characteristic curve (ROC), Delong test, and logistic regression analysis were performed to assess the diagnostic efficiency of one-parameter and multiparametric models.

RESULTS

SyMRI-derived mean T1, T2, and PD were significantly higher and APT % was relatively lower in benign compared to malignant sinonasal lesions (p < 0.05). The ROC analysis showed that the AUCs of the SyMRI-derived quantitative (T1, T2, PD) values and APT % ranged from 0.677 to 0.781 for differential diagnosis between benign and malignant sinonasal lesions. The T2 values showed the best diagnostic performance among all single parameters for differentiating these two masses. The AUCs of combined SyMRI-derived multiple parameters with APT % (AUC = 0.866) were the highest than that of any single parameter, which was significantly improved (p < 0.05).

CONCLUSION

The combination of SyMRI and APTw imaging has the potential to reflect intrinsic tissue characteristics useful for differentiating benign from malignant sinonasal lesions.

CLINICAL RELEVANCE STATEMENT

Combining synthetic MRI with amide proton transfer-weighted imaging could function as a quantitative and contrast-free approach, significantly enhancing the differentiation of benign and malignant sinonasal lesions and overcoming the limitations associated with the superficial nature of endoscopic nasal sampling.

KEY POINTS

• Synthetic MRI and amide proton transfer-weighted MRI could differentiate benign from malignant sinonasal lesions based on quantitative parameters. • The diagnostic efficiency could be significantly improved through synthetic MRI + amide proton transfer-weighted imaging. • The combination of synthetic MRI and amide proton transfer-weighted MRI is a noninvasive method to evaluate sinonasal lesions.

[The non-bacterial pathogenic and clinical characteristics of acute respiratory tract infection in children in a hospital of pediatric in Sichuan Province from 2019 to 2021]

Objective: To explore the non-bacterial pathogen distribution, epidemiological characteristics, and clinical features of acute respiratory infections in children in Sichuan Province. Methods: Using a retrospective cohort study method, this study selected hospitalized children diagnosed with acute respiratory infections at West China Second Hospital of Sichuan University from February 2019 to January 2021, and tested 13 pathogens using polymerase chain reaction (PCR)-fragment analysis. The children were divided into infant group (<1 year old), toddler group (1 year old ≤ age <3 years old), preschool group (3 years old ≤ age <6 years old) and school-age group (6 years old ≤ age <18 years old). The distribution of pathogen positive rates, seasonal epidemic characteristics, clinical characteristics, and some laboratory test indicators were analyzed in children. Statistical analysis was performed on the results using SPSS 22.0 software, with count data expressed as percentages and inter group comparisons using SPSS 22.0 software χ2 Inspection. Results: A total of 2 922 pediatric patients were included in this study, with 1 748 (59.8%) positive for pathogens detected. Among them, 1 391 (79.6%) were detected as a single pathogen, and 357 (20.4%) were detected as a mixture of two or more pathogens. The most commonly detected pathogens were rhinovirus (HRV) (39.7%), syncytial virus (RSV) (22.8%), and parainfluenza virus (PIV) (12.5%). Pathogen positivity is more common in children under 6 years old (χ2=146.59, P<0.001), with a slightly higher positivity rate in male children (61.3%, 1 047/1 707) than in female children (57.7%, 701/1 215) (χ2=3.91, P=0.048), and compared with pathogen negative children, positive children are more prone to symptoms such as cough, wheezing, and shortness of breath (χ2=259.15, 366.06, 12.48, P<0.001). The distribution of different pathogens varies among children of different age groups, and HRV is more common in children aged 1-3 and 3-6 years old (χ2=9.74, P<0.001), while RSV is more common in children under 1 year old (χ2=178.63, P<0.001), while mycoplasma pneumoniae (MP) and influenza virus (InfA/B) are less common in children under 1 year old (χ2=92.54, 12.90,22.21, P<0.01). The prevalence of multiple pathogens showed seasonal changes. HRV showed a high prevalence trend in spring and autumn, while the prevalence of RSV infection was mainly seen in autumn and winter festivals. The positive rate of different pathogens after the outbreak of novel coronavirus pneumonia was significantly lower than that before the outbreak (χ2=252.68, P<0.001). Conclusion: The detection rate of non-bacterial respiratory pathogens in children in Sichuan Province from 2019 to 2021 is high, which is prone to symptoms such as cough, wheezing, and shortness of breath, with HRV and RSV being the main types. The positive rate of respiratory pathogens varies among different age groups, genders, and seasons.

Study on Enhancing the Thermoelectric Stability of the β-Cu2Se Phase by Mn Doping

Cu₂Se is a promising thermoelectric (TE) material due to its low cost, Earth abundance, and high thermoelectric properties. However, the biggest problem of Cu₂Se is its unstable chemical properties. In particular, under the action of an electric field or gradient temperature field, the chemical potential of copper ions inside the material increases. When the external field is strong enough, the chemical potential of copper ions at the negative end of the material reaches the chemical potential of elemental copper. Under these conditions, copper ions must precipitate out, causing Cu₂Se to be unstable, and making it unsuitable for use in applications. In this study, we prepared Cu_2-xMn_xSe (x = 0, 0.02, 0.04 and 0.06) series bulk materials by vacuum melting-annealing and sintered by spark plasma sintering (SPS). We investigated the effects of Mn doping on the composition, microstructure, band structure, scattering mechanism, thermoelectric properties, and stability of Cu₂Se. The results show that Mn doping can adjust the carrier concentration, promote the stabilization of the β-phase structure and improve the electrical properties of Cu₂Se. When x = 0.06, the highest power factor (PF) value of Cu_1.94Mn_0.06Se at 873 K was 1.62 mW m^-1 K^-2. The results of carrier scattering mechanism analysis based on the conductivity ratio method show that the sample doped with Mn and pure Cu₂Se had the characteristics of ionization impurity scattering, and the scattering factor was 3/2. However, the deterioration in thermal conductivity was large, and a superior zT value needs to be obtained. The cyclic test results of high-temperature thermoelectric properties show that Mn doping can hinder Cu⁺ migration and improve its thermoelectric stability, which preliminarily verifies the feasibility of using the stable zirconia mechanism to improve the thermoelectric stability of Cu₂Se.

Ultrafast laser fabrication of efficient polarization-insensitive demultiplexer circuit in YAG crystal

Wavelength division multiplexing is a widely used monolithic device with modulating light sources at different wavelengths based on a designed configuration. In this paper, we report an in-chip demultiplexer with a simple design operating at 532/1064 nm in pure YAG crystal. The device is fabricated by femtosecond laser direct writing inside the transparent substrate with just a width of 36 µm. The compact structure is designed based on the principle of self-imaging, and the propagation features have been simulated by utilizing the beam propagation method. The performance of this wavelength demultiplexer has been investigated through an end-face coupling system, which proves the device can separate 532 nm and 1064 nm light into two discrete waveguides polarization-insensitively with an extinction ratio as high as 13 dB. These superior performances manifest this exquisite device can emerge into kinds of photonic applications in the future. Also, this work further proves that femtosecond laser direct writing technology has irreplaceable advantages in processing micro-nano devices in transparent materials for in-chip integration.

High Pressure Drives Microstructure Modification and zT Enhancement in Bismuth Telluride-Based Alloys

Manipulating and integrating the microstructures at different scales is crucial to tune the electrical and thermal properties of a given compound. High-pressure sintering can modify the multiscale microstructures and thus empower the cutting-edge thermoelectric performance. In this work, the high-pressure sintering technique followed by annealing is adopted to prepare Gd-doped p-type (Bi_0.2Sb_0.8)₂(Te_0.97Se_0.03)₃ alloys. First, the high energy of high-pressure sintering promotes the reduction of grain size, thus increasing the content of 2D grain boundaries. Next, high-pressure sintering induces strong interior strain, where 1D dense dislocations are generated near the strain field. More interestingly, the rare-earth element Gd with a high melting temperature is dissolved into the matrix via high-pressure sintering, thus promoting the formation of 0D extrinsic point defects. This concurrently improves the carrier concentration and density-of-state effective mass, resulting in an enhanced power factor. In addition, the integrated 0D point defects, 1D dislocations, and 2D grain boundaries by high-pressure sintering strengthen phonon scattering, thereby achieving a low lattice thermal conductivity of 0.5 Wm^-1 K^-1 at 348 K. Consequently, a maximum zT value of ∼1.1 at 348 K is achieved in the 0.4 at % Gd-doped (Bi_0.2Sb_0.8)₂(Te_0.97Se_0.03)₃ sample. This work demonstrates that high-pressure sintering enables microstructure modification to enhance the thermoelectric performance of Bi₂Te₃-based and other bulk materials.

A tailored 100%-efficient 532/1064-nm demultiplexer in y-cut LiNbO3 crystal

In this Letter, we report a tailored 532/1064-nm demultiplexer based on a multimode interference (MMI) coupler with an efficiency of 100%. The device structure is designed according to the self-imaging principle, and the propagation and the wavelength division performance are simulated by the beam propagation method. The demultiplexer is fabricated in a y-cut LiNbO₃ crystal by femtosecond laser direct writing (FLDW) combined with the ion implantation technique. The end-face coupling system is used to measure the near field intensity distribution, and the spectra collected from the output ports are obtained by spectrometers. The simulated and the experimental results indicate that the customized demultiplexer in the LiNbO₃ crystal presents excellent wavelength division performance operating at 532 nm and 1064 nm. This work demonstrates the application potential of FLDW technology for developing miniaturized photonic components and provides a new strategy for fabricating high-efficiency integrated wavelength division devices on an optical monocrystalline platform.

Opportunistic screening for osteoporosis using hydroxyapatite measurements of the vertebral by thorax dual-energy spectral CT in postmenopausal females

The purpose of this study was to evaluate the feasibility of opportunistic screening for osteoporosis in postmenopausal females using the dual-energy CT(DECT)-derived hydroxyapatite (HAP) concentration and CT value of L1-vertebra. 239 consecutive postmenopausal female patients were enrolled and underwent both chest DECT and Dual energy X-ray absorptiometry (DXA). According to the T-score of the 1st lumbar vertebra on DXA, patients were divided into the osteoporosis group (T [Formula: see text]- 2.5, n = 112) and non-osteoporosis group (T [Formula: see text] - 2.5, n = 127). The HAP values of the 1st lumbar vertebra were measured from the coronal-view HAP(Fat)-based material decomposition(MD) images, and CT values were measured on the 75 keV monochromatic image. The cutoff values of using HAP and CT value for diagnosing osteoporosis were obtained by drawing receiver operating characteristic (ROC) curves. Both HAP and CT value of the 1st lumbar vertebra had moderate-high correlation with bone-mineral-density measurement on DXA (HAP, r = 0.614; CT value, r = 0.625; all p < 0.01). The area-under-the-curve (AUC), sensitivity, specificity, PPV and NPV for diagnosing osteoporosis was 0.754, 0.714, 0.693, 0.68 and 0.752 using HAP (cutoff value: 142.05 mg/cm³) and 0.766, 0.741, 0.7, 0.685 and 0.754 using CT value (cutoff value: 132HU), respectively. HAP measurements on HAP(Fat)-based MD images in DECT could provide reasonably accurate BMD quantification for diagnosing osteoporosis in postmenopausal females. DECT prescribed for lung cancer screening could also provide opportunistic screening for osteoporosis, extending the clinical application of DECT without additional radiation to patients.

Femtosecond Laser Induced Lattice Deformation in KTN Crystal

In recent years, many novel optical phenomena have been discovered based on perovskite materials, but the practical applications are limited because of the difficulties of device fabrication. Here, we propose a method to directly induce localized lattice modification inside the potassium tantalate niobate crystal by using the femtosecond laser. This selective modification at the processed regions and the surrounding areas is characterized by two-dimensional Raman spectrum mapping. The spectrum variations corresponding to specific lattice vibration modes demonstrate the lattice structure deformation. In this way, the lattice expansion at the femtosecond laser irradiated regions and the lattice compression at the surrounding areas are revealed. Furthermore, surface morphology measurement confirms this lattice expansion and suggests the extension of lattice structure along the space diagonal direction. Moreover, the existence of an amorphization core is revealed. These modifications on the sample lattice can induce localized changes in physicochemical properties; therefore, this method can realize the fabrication of both linear diffraction and nonlinear frequency conversion devices by utilizing the novel optical responses of perovskite materials.

Enabling High Quality Factor and Enhanced Thermoelectric Performance in BiBr3-Doped Sn0.93Mn0.1Te via Band Convergence and Band Sharpening

Lead-free SnTe-based materials are expected to replace PbTe and have gained much attention from the thermoelectric community. In this work, a maximum ZT of ∼1.31 at 873 K is attained in SnTe via promoting a high quality factor resulting from Mn alloying and BiBr₃ doping. The results show that Mn alloying in SnTe converges the L band and the ∑ band in valence bands to supply enhanced valley degeneracy and the density of states effective mass, giving rise to a high power factor of ∼21.67 μW cm^-1 K^-2 at 723 K in Sn_0.93Mn_0.1Te. In addition, the subsequent BiBr₃ doping can sharpen the top of the valence band to coordinate the contradiction between the band effective mass and the carrier mobility, thus enhancing the carrier mobility while maintaining a relatively large density of states effective mass. Consequently, a maximum power factor of 23.85 μW cm^-1 K^-2 at 873 K is achieved in Sn_0.93Mn_0.1Te-0.8 atom % BiBr₃. In addition to band sharpening, BiBr₃ doping can also effectively suppress the bipolar effect at elevated temperatures and reduce the lattice thermal conductivity by strengthening the point defect phonon scattering. Benefitting from doping BiBr₃ in Sn_0.93Mn_0.1Te optimizes the carrier mobility and suppresses the lattice thermal conductivity, resulting in a dramatically enhanced quality factor. Accordingly, an average ZT of ∼0.62 in the temperature range of 300-873 K is obtained in Sn_0.93Mn_0.1Te-0.8 atom % BiBr₃, ∼250% increase compared with that in Sn_1.03Te.

The influence of a deep learning image reconstruction algorithm on the image quality and auto-analysis of pulmonary nodules at ultra-low dose chest CT: a phantom study

BACKGROUND

To investigate the effect of a new deep learning image reconstruction (DLIR) algorithm on the detection, characterization and image quality of pulmonary nodules (PNs) in ultra-low dose chest computed tomography (CT) in comparison with the adaptive statistical iterative reconstruction (ASIR-V) algorithm.

METHODS

Nine artificial pulmonary nodules [six ground glass nodules (GGNs) and three solid nodules (SNs); density: -800 HU, -630 HU, 100 HU; diameter: 12 mm, 10 mm, 8 mm] were randomly placed in a thorax anthropomorphic phantom (Lungman, Kyoto Kagaku Inc.) and scanned on a 256-row CT (Revolution CT, GE Healthcare). Eight scans were performed at 70 kVp with different tube currents (20, 30, 50, 70, 90, 100, 120, 150 mA). Raw data were reconstructed using the filtered back projection (FBP), ASIR-V (30%, 50%, 80%) and DLIR (Low, Medium, High; TrueFidelity™) at 0.625 mm thickness. The effective radiation dose was recorded. All images were automatically analyzed using a commercially available artificial intelligence software (Intelligent 4D Imaging System for Chest CT 5.5, YITU Healthcare) and CT value, standard deviation (SD), long and short diameters of each nodule and SD of air (background) were measured. The detection rate, deformation degree (long diameter/short diameter), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of pulmonary nodules were calculated.

RESULTS

Nodule CT values were the same in all mA settings for all three types of reconstruction algorithms (all P>0.05). DLIR groups had significantly lower SD and higher SNR and CNR values, with better overall image quality than ASIR-V and FBP groups at each mA, ranging from 65-85% reduction in SD, 67-83% increase in SNR with DLIR-H over 50%ASIR-V and 75-91% reduction in SD and 77-89% increase in SNR with DLIR-H over FBP (all P<0.05). At ultra-low dose conditions (30 mA), the DLIR-H images had the highest detection rate of PNs (100%). In addition, the DLIR-M had a minimal negative effect on the characterization of PNs.

CONCLUSIONS

DLIR algorithm can be a potential reconstruction technique to optimize image quality and improve detection rate of PNs in ultra-low dose lung screening.

Selection of DNA Aptamers Recognizing EpCAM-Positive Prostate Cancer by Cell-SELEX for in vitro and in vivo MR Imaging

Background

The sensitive and specific detection of pathogenic cells is important in tumor diagnosis at an early stage. Aptamers are short single-stranded oligonucleotides evolved from systematic evolution of ligands by exponential enrichment (SELEX). It has been proved that aptamers can interact with cognate target molecules with high affinity and specificity and have great potential in the development of medical imaging at molecular level.

Purpose

To select epithelial cell adhesion molecule (EpCAM) specific aptamers targeting prostate cancer and further to conjugate aptamers with GoldMag nanoparticles (a typical iron oxide core/gold shell structure) to construct magnetic molecular probes for medical imaging.

Methods

EpCAM-specific aptamers were selected by Cell-SELEX. The enrichment of specific aptamer candidates was monitored by flow cytometric analysis. Aptamers were further conjugated with GoldMag nanoparticles to construct magnetic molecular probes. The affinity and specificity of aptamer candidates and aptamer-conjugated GoldMag nanoparticles were evaluated. The MR imaging of aptamer-conjugated GoldMag nanoparticles to prostate cancer was further explored in vitro and in vivo.

Results

After 12 rounds of selection, aptamer candidates Eppc6 and Eppc14 could specifically target three types of prostate cancer cells, revealing a high affinity of Eppc6 and Eppc14. Moreover, aptamer-conjugated GoldMag nanoparticles not only exhibited good affinity to different prostate cancer cells but also produced strong T2WI signal intensity reduction distinguished from peritumoral tissue in MRI, indicating that the molecular probes possess both the affinity properties of EpCAM-specific aptamer and the superparamagnetic features of iron oxide.

Conclusion

Our study indicates that aptamer Eppc6 and Eppc14 can recognize prostate cancer cells and tissues. The aptamer-conjugated GoldMag nanoparticles constructed in the study can be used as a molecular imaging agent for detection of PCa in MRI.

Unique beam deflection based on dynamic polarized nano-domains in Cu-doped KTN

In this report, we successfully implement a unique cross-field beam deflector by exploiting the modulation of a one-dimensional refractive index in a copper-doped potassium tantalite niobite crystal. A theoretical model is established based on an electrostrictive effect regulated by the dynamic polarized nano-domains to explicate the mechanism of the abnormal beam deflection which is perpendicular to the applied electric field. Experimental results agree well with our theoretical deduction while validating the interactions between the dynamic polarized nano-domains and the applied electric field. Our findings will break the limitation of conventional electro-optic deflectors, paving the way to develop promising optical functional devices with a large field-of-view scanning angle and ultra-low driving voltage.

Anion exchanged Cl doping achieving band sharpening and low lattice thermal conductivity for improving thermoelectric performance in SnTe

Cl doping achieves band sharpening as a potential strategy for improving the power factor in SnTe thermoelectrics.

[Research on feasibility of in vitro inflammatory wound microenvironment simulated by using inflammatory wound tissue homogenate of mice]

Objective: To investigate the feasibility of in vitro inflammatory wound microenvironment simulated by using inflammatory wound tissue homogenate of mice. Methods: (1) Ten eight-week-old C57BL/6 male mice were collected and full-thickness skin tissue with diameter of 1.0 cm on both sides of the midline of the back was taken with a perforator to make the normal skin tissue homogenate supernatant. At 48 h after the full-thickness skin defect wound was established, the wound tissue within 2 mm from the wound edge was taken to make inflammatory wound tissue homogenate supernatant. Two kinds of tissue homogenate supernatant were taken to adjust the total protein concentration to 1 mg/mL, and the tumor necrosis factor α (TNF-α) content was detected by enzyme-linked immunosorbent assay. The number of sample was 6. (2) The primary passage of human umbilical cord mesenchymal stem cells (hUCMSCs) were collected and cultured to the 3rd passage with the normal exosomes being extracted from the hUCMSCs after cultured for 48 h. Another batch of hUCMSCs in the 3rd passage was collected and stimulated with inflammatory wound tissue homogenate supernatant of 30, 50, and 100 μg/mL total protein and normal skin tissue homogenate supernatant of 30, 50, and 100 μg/mL total protein, respectively. After cultured for 48 h, the exosomes stimulated with normal protein of 30, 50, and 100 μg/mL and exosomes stimulated with inflammatory protein of 30, 50, and 100 μg/mL were extracted. Normal exosomes, exosomes stimulated with 30 μg/mL normal protein, and exosomes stimulated with 30 μg/mL inflammatory protein were collected, the morphology was observed by transmission electron microscope, the particle size was detected by nanoparticle tracking analyzer, and the expressions of CD9 and CD63 were detected by Western blotting. (3) Twenty one-day-old C57BL/6 mice were taken to isolate the primary passage of fibroblasts (Fbs) and the 3rd passage of Fbs, whose morphology was observed under the inverted phase contrast microscope. The Fbs of 3rd passage were collected to observe the expression of vimentin by cell crawling method combined with immunofluorescence method at culture hour (CH) 2. (4) The Fbs of 3rd passage were divided into control group, normal exosome group, 30, 50, 100 μg/mL normal protein stimulating exosome group, and 30, 50, 100 μg/mL inflammatory protein stimulating exosome group according to the random number table, with 4 wells in each group. Cells in control group received no treatment, and cells in the other 7 groups were respectively added with normal exosomes, exosomes stimulated with normal protein of 30, 50, and 100 μg/mL, and exosomes stimulated with inflammatory protein of 30, 50, and 100 μg/mL prepared in experiment (2). The final mass concentration of exosomes was adjusted to 10 μg/mL. The cell viability was detected by cell count kit 8 at CH 48. (5) Two batches of Fbs in the 3rd passage were divided and treated as those in experiment (4), with 4 wells in each group, and the final mass concentration of exosomes was adjusted to 1 and 10 μg/mL, respectively. The cell mobility was detected by cell scratch test at CH 6, 12, and 24. (6) Two batches of the Fbs of 3rd passage were collected, divided, and treated as those in experiment (4) except with no control group, with 3 wells in each group, and the final mass concentration of exosomes was respectively adjusted to 1 and 10 μg/mL. The mRNA expression levels of transforming growth factor β(1) (TGF-β(1)), TGF-β(3), and α smooth muscle actin (α-SMA) were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction at CH 48. Data were statistically analyzed with analysis of variance for repeated measurement, one-way analysis of variance, and Bonferroni method. Results: (1) The content of TNF-α in inflammatory wound tissue homogenate supernatant of mice was (116±3) pg/mL, significantly higher than (97±5) pg/mL in normal skin tissue homogenate supernatant at post injury hour 48 (t=3.306, P<0.05). (2) Normal exosomes, exosomes stimulated with 30 μg/mL normal protein, and exosomes stimulated with 30 μg/mL inflammatory protein of hUCMSCs showed the typical saucer-like shape. The particle sizes of the three exosomes of hUCMSCs were 30-150 nm, which were all within the normal particle size range of exosome. Three exosomes of hUCMSCs positively expressed CD9 and CD63. (3) The primary passage of cells were clearly defined and showed protruding spindle shape, irregular polygon shape, or slender strip shape. The morphology of the 3rd and the primary passage of cells is similar. At CH 2, vimentin in cells was positively expressed, and the cells were identified as Fbs. (4) At CH 48, the cell viability was (137.4±2.8)% in 30 μg/mL inflammatory protein stimulating exosome group, obviously higher than 100%, (107.5±2.4)%, (113.3±3.2)%, (104.0±2.0)%, and (101.9±1.5)% in control group, normal exosome group, 30 μg/mL normal protein stimulating exosome group, and 50 and 100 μg/mL inflammatory protein stimulating exosome groups, respectively (P<0.01), and cell viability in 30 μg/mL normal protein stimulating exosome group was obviously higher than that in control group, normal exosome group, and 50 and 100 μg/mL normal protein stimulating exosome groups [(103.4±2.2)% and (102.5±1.4)%], respectively (P<0.01). (5) At CH 6, 12, and 24, the mobility rate of cells in 30 μg/mL inflammatory protein stimulating exosome group was significantly higher than that in control group, normal exosome group, 30 μg/mL normal protein stimulating exosome group, and 50 and 100 μg/mL inflammatory protein stimulating exosome groups, respectively, when the final mass concentrations of exosome was 1 μg/mL (P<0.05) . At CH 12, the mobility rate of cells in 30 μg/mL normal protein stimulating exosome group was obviously higher than that in control group, normal exosome group, and 50 and 100 μg/mL normal protein stimulating exosome groups, respectively, when the final mass concentration of exosome was 1 μg/mL (P<0.05). At CH 6, the mobility rate of cells in 30 μg/mL inflammatory protein stimulating exosome group was significantly higher than that in control group and normal exosome group (P<0.05), and the mobility rate of cells in 30 μg/mL normal protein stimulating exosome group was significantly higher than that in 50 and 100 μg/mL normal protein stimulating exosome groups, respectively, when the final mass concentration of exosome was 10 μg/mL (P<0.05). At CH 12 and 24, the mobility rate of cells in 30 μg/mL inflammatory protein stimulating exosome group was significantly higher than that in control group, normal exosome group, and 50 and 100 μg/mL inflammatory protein stimulating exosome groups (P<0.05), and the mobility rate of cells in 30 μg/mL normal protein stimulating exosome group was significantly higher than that in control group, normal exosome group, and 50 and 100 μg/mL normal protein stimulating exosome groups, respectively, when the final mass concentration of exosome was 10 μg/mL (P<0.05). (6) There were no statistically significant differences in mRNA expression levels of TGF-β(1), TGF-β(3), and α-SMA of cells among the 7 groups at CH 48 when the final mass concentration of exosome was 1 μg/mL (F=1.123, 1.537, 1.653, P>0.05). There were no statistically significant differences in mRNA expression levels of TGF-β(1) and α-SMA of cells among the 7 groups at CH 48 when the final mass concentration of exosome was 10 μg/mL (F=1.487, 1.308, P>0.05), and mRNA expression level of TGF-β(3) of cells in 50 μg/mL inflammatory protein stimulating exosome group at CH 48 was significantly higher than that in normal exosome group, 50 μg/mL normal protein stimulating exosome group, and 30 and 100 μg/mL inflammatory protein stimulating exosome groups when the final mass concentration of exosome was 10 μg/mL (P<0.05). Conclusions: The pretreatment with inflammatory wound tissue homogenate supernatant of mice has no significant effect on the total protein of hUCMSCs exosomes. The hUCMSCs exosomes stimulated by low concentration inflammatory wound tissue homogenate supernatant can significantly promote the proliferation and migration ability of Fbs. The content of inflammatory mediators in the wound tissue homogenate supernatant during the inflammatory phase is extremely low, which may be the reason that the anti-inflammation and tissue repair paracrine effects of mesenchymal stem cell cannot be effectively started.

Investigation of Synthetic Relaxometry and Diffusion Measures in the Differentiation of Benign and Malignant Breast Lesions as Compared to BI-RADS

BACKGROUND

Breast cancer is the most common malignant tumor in women and a quantitative contrast-free method is highly desirable for its diagnosis.

PURPOSE

To investigate the performance of quantitative MRI in differentiating malignant from benign breast lesions and to compare with the Breast Imaging Reporting and Data System (BI-RADS).

STUDY TYPE

Retrospective.

SUBJECTS

Eighty patients (56 with malignant lesions and 24 with benign lesions).

FIELD STRENGTH/SEQUENCE

Diffusion-weighted imaging (DWI) with a single-shot echo planar sequence and synthetic MRI with magnetic resonance image compilation (MAGiC) were performed at 3T.

ASSESSMENT

T₁ relaxation time (T₁ ), T₂ relaxation time (T₂ ), and proton density (PD) from synthetic MRI and apparent diffusion coefficient (ADC) from DWI were analyzed by two radiologists (Reader A, Reader B). Univariable and multivariable models were developed to optimize differentiation between malignant and benign lesions and their performances compared to BI-RADS.

STATISTICAL TESTS

The diagnostic performance was evaluated using multivariate logistic regression analysis and area under the receiver operating characteristic (ROC) curves (AUC).

RESULTS

T₂ , PD, and ADC values for malignant lesions were significantly lower than those in benign breast lesions for both radiologists (all P < 0.05). The combined T₂ , PD, and ADC model had the best performance for differentiating malignant and benign lesions with AUC, sensitivity, specificity, positive predictive value, and negative predictive values of 0.904, 94.6%, 87.5%, 94.6%, and 87.5%, respectively. The corresponding results for BI-RADS were no AUC, 94.6%, 75.0%, 89.8%, and 85.7%, respectively.

DATA CONCLUSION

The approach that combined synthetic MRI and DWI outperformed BI-RADS in the differential diagnosis of malignant and benign breast lesions and was achieved without contrast agents. This approach may serve as an alternative and effective strategy for the improvement of breast lesion differentiation.

LEVEL OF EVIDENCE

3.

TECHNICAL EFFICACY STAGE

3.

[Kaiser score for diagnosis of breast lesions presenting as non-mass enhancement on MRI]

OBJECTIVE

To evaluate the diagnostic efficacy of Kaiser score for breast lesions presenting as non-mass enhancement.

METHODS

We collected data from patients with breast lesions presenting as non-mass enhancement on preoperative DCE-MRI between January, 2014 and June, 2019. All the cases were confirmed by surgical pathology or puncture biopsy. With pathology results as the gold standard, we evaluated the diagnostic efficacy of Kaiser score and MRI BI-RADS classification and the consistency between the diagnostic results by the two methods and the pathological results.

RESULTS

A total of 90 lesions were detected in 88 patients, including 28 benign lesions (31.1%) and 62 malignant lesions (68.9%). For diagnosis of the lesions, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of Kaiser Score were 100%, 75%, 89.9%, 100% and 92%, as compared with 93.5%, 46.4%, 79.5%, 76.5% and 78.9% of MRI BI-RADS, respectively. The diagnostic specificity of Kaiser score was significantly higher than that of BI-RADS classification (P=0.021).

CONCLUSIONS

The Kaiser score system provides a diagnostic strategy for BI-RADS classification of breast lesions with non-mass enhancement and has a better diagnostic efficacy than BI-RADS classification alone. The use of Kaiser score can significantly improve the diagnostic specificity of such breast lesions for inexperienced radiologists.

Mode-controllable waveguide fabricated by laser-induced phase transition in KTN

We report the fabrication of a hexagonal cladding waveguide by femtosecond laser direct writing (FLDW) in a potassium tantalate niobate (KTN) crystal with a large electric-optical effect. Confocal micro-Raman results show the laser-induced phase transition occurs in the filament areas during the waveguide fabrication. The small filaments can strongly confine the polar nanoregions especially in its ferroelectric state to enhance the waveguide birefringence, enabling excellent polarization maintaining features for both TE and TM-polarized light propagations. The temperature-dependent phase transition allows for an active control of waveguide polarization modes as well as a switchable polarization-maintaining feature.

[Advances in the research of effects of epithelial-mesenchymal interaction on wound healing and scar formation]

Wound healing is a dynamic process which involves interaction of various types of cells, cytokines, and extracellular matrix. Among them, epithelial cells and mesenchymal cells are the key components which involve in wound healing and scar formation. Related scholars had done a great number of studies about the functions of epithelial cells and fibroblasts(Fbs) in wound healing and scar formation. The results showed that under the stimulation of complex microenvironment, epithelial cells would lose their epithelial characteristics and acquire the typical characteristics and migration ability of mesenchymal cells. At the same time, with the complex changes of cell structure and cell behavior, they would participate in the process of tissue wound repair, including normal or fibrotic repair, by covering the wound with migration. Fbs are the key cells for the wound fibrotic repair, and play important roles in the process of wound healing, including excessive wound healing or delayed wound healing. In the recent years, the researchers realized that the cross-talk between epithelial cells and Fbs in wound healing, which is referred to as epithelial-mesenchymal interaction, significantly changes the biological behaviors of these two cell types, which affects the dermal remodeling and re-epithelialization quality of wound. Epithelial-mesenchymal interaction plays an important role in skin morphogenesis during embryonic development and maintaining the structural integrity of adult skin. In the process of re-epithelialization, Fbs could promote the proliferation and migration of keratinocytes, meanwhile keratinocytes would receive the signals from Fbs to reconstruct functional epithelium, which has become a hot topic in the field of wound healing at present. In this paper, a comprehensive analysis of the literature on the role of epithelial-mesenchymal interaction in wound healing and scar formation at home and abroad in recent years is presented for the reference of relevant scholars.

[Influence of human amniotic mesenchymal stem cells on macrophage phenotypes and inflammatory factors in full-thickness skin wounds of mice]

Objective: To explore the influence of human amniotic mesenchymal stem cells (hAMSCs) on the in vivo and in vitro regulation of macrophage phenotypes and inflammatory factors associated with wound healing of full-thickness skin wounds in mice. Methods: Fresh amniotic membrane discarded from full-term delivery by 5 healthy pregnant women in the Department of Obstetrics and Gynecology of the Affiliated Hospital of Zunyi Medical University was used for the isolation and culture of hAMSCs by enzyme digestion method. The third passage of cells was used for identification of adipogenic and osteogenic differentiation. The fourth passage of cells was used for identification of hAMSCs surface markers. Ten C57BL/6 mice (all male, aged 6 to 8 weeks, the same gender and age below) were selected for extracting mouse peritoneal macrophages by intraperitoneal lavage, and M1-type macrophages were induced by Dulbecco's modified eagle medium (DMEM) medium containing interferon-γ. The M1-type macrophages were divided into hAMSCs+ macrophage group and macrophage alone group. Then 1×10(4) hAMSCs/per well of fourth passage were added to macrophage in hAMSCs+ macrophage group and cultured in 2 mL DMEM medium for routine culture. In macrophage alone group, each well was only added with 2 mL DMEM medium for routine culture. On day 1 and 7 in culture, the content of interleukin-12 (IL-12), arginase 1, and IL-10 in the cell culture supernatant of the 2 groups were detected by enzyme-linked immunosorbent assay with sample number of 6/per group. (2) Full-thickness skin wound model was reproduced in the back of 56 C57BL/6 mice, which were divided into hAMSCs group and phosphate buffer solution (PBS) group using the random number table, with 28 mice in each group. Mice in hAMSCs group were subcutaneously injected with 100 μL of cell suspension containing 1×10(7) hAMSCs per mL in PBS suspension along the wound edge. While mice in PBS group were only subcutaneously injected with 100 μL PBS along the wound edge. On post injection day (PID) 1, 3, 7, and 14, 7 mice in the two groups were sacrificed respectively. Histopathological observation was performed with hematoxylin-eosin staining. The expressions of macrophage surface markers [CD68 and inducible nitric oxide synthase (iNOS) double positive cells and CD68 and arginase 1 double positive] in the wounds were detected by immunofluorescent staining. The mRNA expressions of IL-10, macrophage inflammatory protein 1α (MIP-1α), and MIP-2 in the wounds were detected by real-time fluorescent quantitative reverse transcription polymerase chain reaction. Data were statistically analyzed with analysis of variance for factorial design, t test, and Bonferroni correction. Results: (1) On day 1 in culture, the content of IL-12 and arginase 1 in the cell culture supernatant of the two groups were similar (t=0.448, 0.536, P>0.05), and the content of IL-10 in the cell culture supernatant of hAMSCs+ macrophage group was significantly lower than that in macrophage alone group (t=14.722, P<0.01). On day 7 in culture, the content of IL-12 in the cell culture supernatant of hAMSCs+ macrophage group was significantly lower than that in macrophage alone group (t=13.226, P<0.01), and the content of arginase 1 and IL-10 was significantly higher than that in macrophage alone group (t=30.172, 31.406, P<0.01). (2) On PID 1, a large number of inflammatory cells infiltration were observed in the skin wounds of both groups. On PID 3, the inflammatory cells infiltration in the skin wounds increased in both groups, and the inflammatory cells infiltration in hAMSCs group was less than that in the PBS group. On PID 7, the inflammatory cells infiltration in the wounds decreased in both groups, and the inflammatory cells infiltration in hAMSCs group was less than that in the PBS group. On PID 14, no obvious inflammatory cells infiltration was observed in the wounds in the two groups. (3) On PID 1 and 14, the percentages of CD68 and iNOS double positive cells and CD68 and arginase 1 double positive cells in the wounds were similar in the two groups (t(1 d)=0.134, 0.693, t(14 d)=1.146, 2.585, P>0.05). On PID 3 and 7, the percentages of CD68 and iNOS double positive cells in the wounds in hAMSCs group were significantly lower than those of PBS group (t=6.396, 4.787, P<0.01), while the percentages of CD68 and arginase 1 double positive cells were significantly higher than those of PBS group (t=3.928, 4.473, P<0.01). (4) On PID 1, the mRNA expressions of IL-10 in the wounds of mice in the two groups were similar (t=2.005, P>0.05). On PID 3, 7, and 14, the mRNA expressions of IL-10 in the wounds of mice in hAMSCs group were significantly higher than those of PBS group (t=7.758, 124.355, 80.823, P<0.01). On PID 1, 3, 7, and 14, the mRNA expressions of MIP-1α and MIP-2 in the wounds of mice in hAMSCs group (0.341±0.212, 0.648±0.004, 0.611±0.106, 0.763±0.049, 1.377±0.099, 1.841±0.042, 1.181±0.035, 0.553±0.028) were significantly lower than those of PBS group (3.853±0.035, 6.914±0.163, 3.648±0.113, 2.250±0.046, 11.119±0.495, 8.634±0.092, 5.722±0.021, 4.862±0.036, t=43.198, 101.904, 51.845, 58.231, 51.074, 177.501, 291.752, 251.614, P<0.01). Conclusions: hAMSCs demonstrates biological effects of promoting the transformation of M1-type macrophages into M2-type macrophages in full-thickness skin wounds of mice. They can up-regulate the expression of anti-inflammatory and anti-fibrotic factor IL-10, and down-regulate the expression of important inflammation mediated factors MIP-1α and MIP-2.

A novel double-variant RHAG allele leads to Rhmod phenotype

AIMS/OBJECTIVES

We aimed to analyse the molecular backgrounds and red blood cell (RBC) antigen expression of a male blood donor with Rh_mod phenotype and his family members.

BACKGROUND

Rh deficiency phenotypes are rarely found worldwide and are characterised by the lack of Rh antigen expression on RBCs. During routine screening, we found a blood donor who seemingly lacked Rh antigens. Therefore, we recruited the donor and his family for further investigation.

METHODS

RBC serotyping and antibody screening/identification were performed for each sample. A routine blood examination was also conducted. RHD, RHCE and RHAG were sequenced at the genomic DNA or RNA level. Eleven antigens or proteins associated with Rh complex were tested using flow cytometry analysis.

RESULTS

The proband and one of his brothers showed extremely weak D antigen and Rh expression levels but did not manifest anaemia. Most of the expressed RBC antigens of the two Rh-deficient individuals were similar to the previously reported cases but with some exceptions. Molecular analyses demonstrated homozygous expression of a novel RHAG allele, namely, c.[572G>A;707A>C], both in the proband and one of his brothers.

CONCLUSIONS

To our knowledge, we identified the second double-variant RHAG allele and the first one related to Rh_mod phenotype. The novel allele was also confirmed to be heritable by family analyses.

The utility of measuring the apparent diffusion coefficient for peritumoral zone in assessing infiltration depth of endometrial cancer

BACKGROUND

The invasion depth of endometrial cancer is one of the most important prognosis factors. The aim of the current study was to investigate the diagnostic value of the apparent diffusion coefficient (ADC) of the peritumoral zone for assessing the infiltration depth of endometrial cancer.

METHODS

An institutional review board approved this prospective study, and all study participants provided informed consent. A total of 58 patients (mean age 54 ± 8.3 years, range 34-69 years) with endometrial cancer were prospectively enrolled. Two radiologists assessed all preoperative magnetic resonance images with T1, T2, and diffusion-weighted imaging, and determined the location of the deepest invasion of the tumor. The peritumoral zone was defined as a 5-mm-thick zone surrounding and adjacent to the cancerous endometrium. The mean ADC (ADCm) values of the tumor and the peritumoral zone were measured. Sensitivity, specificity, positive and negative predictive values, and the area under the receiver operating characteristic curve (Az) were calculated for visual inspection, and an ADC cutoff value for the peri-endometrial zone was determined for predicting the myometrial invasion depth.

RESULTS

The ADCm values of tumors and peritumoral zones were 0.83 × 10- 3 mm2/sec and 1.06 × 10- 3 mm2/sec, respectively. There was no significant difference between the ADCm values of the tumors in the superficial and deep myometrial invasion groups (P > 0.05). However, the ADCm value at the peritumoral zone in the deep myometrial invasion group (1.23 × 10- 3 mm2/sec) significantly differed from that in the superficial myometrial invasion group (0.99 × 10- 3 mm2/sec) (p = 0.005). In assessments of deep myometrial invasion, the sensitivity, specificity, negative predictive value, and positive predictive value were 0.58, 0.93, 0.84, and 0.77, respectively, for the ADCm cutoff value of the peritumoral zone, and 0.71, 0.80, 0.87, and 0.60. respectively, for visual inspection. The accuracy of myometrial invasion depth assessment using the ADCm cutoff value and visual inspection were 83 and 78%, respectively. The Az for both was 0.76.

CONCLUSION

ADCm at the peritumoral zone can predict deep myometrial invasion of endometrial cancer. This value can therefore enhance confidence in preoperative endometrial cancer evaluation, and when tailoring surgical approaches.

Upgraded flowing liquid lithium limiter for improving Li coverage uniformity and erosion resistance in EAST device

We report on design and technology improvements for a flowing liquid lithium (FLiLi) limiter inserted into auxiliary heated discharges in the experimental advanced superconducting tokamak device. In order to enhance Li coverage uniformity and erosion resistance, a new liquid Li distributor with homogenous channels was implemented. In addition, two independent electromagnetic pumps and a new horizontal capillary structure contributed to an improvement in the observed Li flow uniformity (from 30% in the previous FLiLi design to >80% in this FLiLi design). To improve limiter surface erosion resistance, hot isostatic press technology was applied, which improved the thermal contact between thin stainless steel protective layers covering the Cu heat sink. The thickness of the stainless steel layer was increased from 0.1 mm to 0.5 mm, which also helped macroscopic erosion resilience. Despite the high auxiliary heating power up to 4.5 MW, no Li bursts were recorded from FLiLi, underscoring the improved performance of this new design.

[Expression and clinical significance of moesin and E-cadherin in invasive carcinoma of breast, no specific type]

OBJECTIVE

To investigate the correlation of moesin and E-cadherin with biological behavior of breast cancer and its mechanism by comparing expression of moesin and E-cadherin in breast invasive carcinoma of no specific type(BIC-NST), breast ductal carcinoma in situ(BDCIS) and normal breast tissues adjacent to carcinoma.

METHODS

Breast cancer cases of the Huizhou Municipal Center People Hospital were collected between Jan 2008 and Dec 2010, expression of moesin and E-cadherin in 104 cases of BIC-NST, 84 cases of BDCIS and 53 cases of normal breast tissues adjacent to carcinoma were detected by tissue-microarray and SP immunohistochemical staining. Western blot was used to detect moesin expression of 16 BIC-NST fresh tissues.

RESULTS

Expression rate of moesin in BIC-NST and BDCIS were significantly higher than normal tissues(P<0.01), but the expression rate of E-cadherin in BIC-NST and BDCIS were significantly lower than those of normal tissues(P<0.01). Expression rate of moesin in BIC-NST grade Ⅲ group was significantly higher than that of the grade Ⅰ group.There was a significantly positive correlation between histological grade and moesin expression(P<0.05). However, E-cadherin expression rate in BIC-NST grade Ⅲ group was significantly lower than that in grade Ⅰ group , and there was a significantly negative correlation between histological grade and E-cadherin expression(P<0.05). Moreover, no significant correlation was observed between moesin and E-cadherin expression in BDCIS tissues. Expression of moesin in clinical stage Ⅱ + Ⅲ BIC-NST was significantly higher than that in stage Ⅰ(P<0.01) . Expression of moesin was significantly associated with lymph node metastasis (P<0.01). But no significant correlation was observed between moesin expression and age, tumor size and vascular invasion . However, expression of E-cadherin in clinical stage Ⅱ+ Ⅲ BIC-NST was significantly lower than that in stage Ⅰ(P<0.01). Expression of E-cadherin was significantly associated with lymph node metastasis and vascular invasion (P<0.01). But no significant correlation was observed between E-cadherin expression, age and tumor size. There was a negative correlation between expression of moesin and E-cadherin in BIC-NST(P=0.021)and BDCIS(P=0.032).

CONCLUSION

Higher moesin and lower E-cadherin signal transduction is closely related to the recurrence and development of breast carcinoma, therefore moesin and E-cadherin might provide new targets for gene therapy in breast carcinoma.

A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak

A program involving the extensive and systematic use of lithium (Li) as a "first," or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak-both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thin flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST.

[Activation of transcription factor NF-κB in a rat model of cardiac fibrosis induced by β-adrenoceptor stimulation]

OBJECTIVE

To establish a model of cardiac fibrosis induced by isoproterenol (ISO), the non-selective β adrenoceptor agonist, injected subcutaneously for 7 days in rats, and to observe changes of transcription factor NF-κB in the model.

METHODS

Male SD rats weighing 280-320 g were injected with ISO (0.25 mg/kg/d) subcutaneously for 7 days to induce cardiac fibrosis. The collagen volume fraction was determined by quantitative morphometry of picrosirius red stained left ventricular sections. Collagen types I/III and IL-6 mRNA expressions were analyzed by real time PCR. The pathological changes of the heart were investigated by Hematoxylin and Eosin staining. NF-κB was localized by immunohistochemistry (IHC) and phosphorylated NF-κB levels were assessed by Western blot analysis.

RESULTS

Compared with the controls, ISO significantly elevated the sirius red stained area and collagen volume fraction (12.01±1.644 vs. 0.95±0.067, P<0.001). Similarly, ISO increased the mRNA expressions of collagen Iand collagen III of the heart compared with the controls (10.51±0.47 vs. 0.98±0.02,P<0.001 for collagen I; 9.58±1.33 vs. 1.02±0.02, P<0.001 for collagen III). The number of nuclei was increased and nuclear accumulation was presented in myocardial tissue induced by ISO. The mRNA expression of IL-6 increased in ISO group (1.64±0.18 vs. 1.04±0.07, P<0.01). ISO induced NF-κB nuclear translocation, accompanied by an increase in phosphorylation of NF-κB (10.83±2.05 vs. 1.05±0.27, P<0.001).

CONCLUSION

We conclude that the model of cardiac fibrosis can be successfully induced by ISO injected subcutaneously for 7 days in rats and the activation of nuclear factor NF-κB increased by β-adrenoceptor stimulation.

Revisiting the relationship between environmental and financial performance in Chinese industry

The debate on the relationship between corporate or industrial environmental performance (EP) and financial performance (FP) has yet to be resolved, and studies need to examine the possible moderating effects on the EP-FP link. We argue that industrial EP has a positive effect on FP and that industrial munificence and resource slack can moderate the EP-FP link. Using a dataset from Chinese industrial firms, we examine the direct effect of industrial EP on FP and the indirect effects of industrial munificence and resource slack on the EP-FP link. Our results show that improving corporate or industrial-level EP significantly influences FP and that slack resources play a significant role on the EP-FP link. However, we found no significant moderating effect of industrial munificence on the link.

Methods and preliminary measurement results of liquid Li wettability

A test of lithium wettability was performed in high vacuum (< 3 × 10(-4) Pa). High magnification images of Li droplets on stainless steel substrates were produced and processed using the MATLAB(®) program to obtain clear image edge points. In contrast to the more standard "θ/2" or polynomial fitting methods, ellipse fitting of the complete Li droplet shape resulted in reliable contact angle measurements over a wide range of contact angles. Using the ellipse fitting method, it was observed that the contact angle of a liquid Li droplet on a stainless steel substrate gradually decreased with increasing substrate temperature. The critical wetting temperature of liquid Li on stainless steel was observed to be about 290 °C.

Regional activation in the rat brain during visceral stimulation detected by c-fos expression and fMRI

AIM

The aim of the study was to determine and compare the areas of brain activated in response to colorectal distention (CRD) using functional magnetic resonance imaging (fMRI) and c-fos protein expression.

METHODS

For fMRI study (3.0 T magnet), anaesthetized rats underwent phasic CRD, synchronized with fMRI acquisition. Stimulation consisted of eight cycles of balloon deflation (90 s) and inflation (30 s), at 40, 60 or 80 mmHg of pressure. For c-fos study two sets of experiments were performed on anaesthetized rats: comparing (A) brain activation in rats with the inserted colorectal balloon (n = 5), to the rats without the balloon (n = 5); and (B) rats with inserted balloon (n = 10), to the rats with inserted and distended balloon (n = 10). The pressure of 80 mmHg was applied for 2 h of 30 s inflation and 90 s deflation, alternating cycles.

RESULTS

Functional MRI revealed significant activation in the amygdala, hypothalamus, thalamus, cerebellum and hippocampus. Significant increase in c-fos expression was observed in amygdala and thalamus in the first set of experiments, and hypothalamus and parabrachial nuclei in the second.

CONCLUSION

The two methods are not interchangeable but appeared to be complementary: fMRI was more sensitive, whereas c-fos had much greater resolution.

Removal of local field gradient artefacts in BOLD contrast imaging of head and neck tumours

Monitoring of oxygenation in tumours is an important issue in predicting the success of anti-cancer treatments such as radiotherapy. Gradient echo (GE) imaging sequences can be used for monitoring changes in tumour blood flow and oxygenation. However, the application of this method in head and neck tumours is hampered by significant artefacts and losses of the MR signal near air-tissue interfaces. We investigated the usefulness of a gradient-echo slice excitation profile (GESEPI) sequence that should keep the oxygen contrast while recovering the signal loss caused by susceptibility artefacts. A tumour model was implanted in the neck and in the leg of mice. MR imaging was performed at 4.7 T. GE and GESEPI sequences were used for monitoring the blood oxygen level dependent (BOLD) contrast after carbogen breathing. The pO2 was also monitored in tumours using an OxyLite probe (Oxford Optronics). Using the tumours implanted in the leg, we found that the variations of signal intensity after carbogen breathing were similarin both sequences. In the tumour implanted in the neck, it was possible, using GESEPI sequences, to recover the signal loss caused by susceptibility artefacts and to monitor the effect of carbogen-induced changes in the tumour.

Different excitation and reception distributions with a single-loop transmit-receive surface coil near a head-sized spherical phantom at 300 MHz

Calculations and experiments were used to examine the B(1) field behavior and signal intensity distribution in a 16-cm diameter spherical phantom excited by a 10-cm diameter surface coil at 300 MHz. In this simple system at this high frequency very complex RF field behavior exists, resulting in different excitation and reception distributions. Included in this work is a straightforward demonstration that coil receptivity is proportional to the magnitude of the circularly polarized component of the B(1) field that rotates in the direction opposite to that of nuclear precession. It is clearly apparent that even in very simple systems in head-sized samples at this frequency it is important to consider the separate excitation and reception distributions in order to understand the signal intensity distribution.

Spatial variation in cartilage T2 of the knee

Technical limitations imposed by resolution and B1 homogeneity have thus far limited quantitative in vivo T2 mapping of cartilage to the patella. The purpose of this study is to develop T2 mapping of the femoral/tibial joint and assess regional variability of cartilage T2 in the knee. Quantitative in vivo T2 mapping of the knee was performed on 15 asymptomatic adults (age, 22-44) using a 3T MR scanner. There is a consistent pattern of spatial variation in cartilage T2 with longer values near the articular surface. The greatest variation occurs in the patella, where T2 increases from 45.3 +/- 2.5 msec at a normalized distance of 0.33-67 +/- 5.5 msec at a distance of 1.0. These results demonstrate feasibility of performing in vivo T2 mapping of femoral tibial cartilage. Except for the superficial 15% where T2 values are lower, the spatial variation in T2 of femoral and tibial cartilage is similar to patellar cartilage.

Ischemic exercise and the muscle metaboreflex

In exercising muscle, interstitial metabolites accumulate and stimulate muscle afferents. This evokes the muscle metaboreflex and raises arterial blood pressure (BP). In this report, we examined the effects of tension generation on muscle metabolites and BP during ischemic forearm exercise in humans. Heart rate (HR), BP, P(i), H(2)PO(4)(-), and pH ((31)P-NMR spectroscopy) data were collected in 10 normal healthy men (age 23 +/- 1 yr) during rhythmic handgrip exercise. After baseline measurements, the subjects performed rhythmic handgrip for 2 min. At 2 min, a 250-mmHg occlusion cuff was inflated, and ischemic handgrip exercise was continued until near fatigue (Borg 19). Measurements were continued for an additional 30 s of ischemia. This protocol was performed at 15, 30, 45, and 60% of the subjects' maximum voluntary contraction (MVC) in random order. As tension increased, the time to fatigue decreased. In addition, mean arterial pressure and HR were higher at 60% MVC than at any of the other lower tensions. The NMR data showed significantly greater increases in H(2)PO(4)(-), P(i), and H(+) at 60% than at 15 and 30% MVC. Therefore, despite the subjects working to the same perceived effort level, a greater reflex response (represented by BP and HR data) was elicited at 60% MVC than at any of the other ischemic tensions. These data are consistent with the hypothesis that, as tension increases, factors aside from insufficient blood flow contribute to the work effect on muscle metabolites and the magnitude of the reflex response.

Effects of forearm bier block with bretylium on the hemodynamic and metabolic responses to handgrip

We tested the hypothesis that a reduction in sympathetic tone to exercising forearm muscle would increase blood flow, reduce muscle acidosis, and attenuate reflex responses. Subjects performed a progressive, four-stage rhythmic handgrip protocol before and after forearm bier block with bretylium as forearm blood flow (Doppler) and metabolic (venous effluent metabolite concentration and (31)P-NMR indexes) and autonomic reflex responses (heart rate, blood pressure, and sympathetic nerve traffic) were measured. Bretylium inhibits the release of norepinephrine at the neurovascular junction. Bier block increased blood flow as well as oxygen consumption in the exercising forearm (P < 0.03 and P < 0.02, respectively). However, despite this increase in flow, venous K(+) release and H(+) release were both increased during exercise (P < 0.002 for both indexes). Additionally, minimal muscle pH measured during the first minute of recovery with NMR was lower after bier block (6.41 +/- 0.08 vs. 6.20 +/- 0.06; P < 0.036, simple effects). Meanwhile, reflex effects were unaffected by the bretylium bier block. The results support the conclusion that sympathetic stimulation to muscle during exercise not only limits muscle blood flow but also appears to limit anaerobiosis and H(+) release, presumably through a preferential recruitment of oxidative fibers.

Microimaging at 14 tesla using GESEPI for removal of magnetic susceptibility artifacts in T(2)(*)-weighted image contrast

In magnetic resonance imaging (MRI), T(2)(*)-weighted contrast is significantly enhanced by extremely high magnetic field strength, offering broad potential applications. However, the T(2)(*)-weighted image contrast distortion and signal loss artifact arising from discontinuities of magnetic susceptibility within and around the sample are also increased, limiting utilization of high field systems for T(2)(*)-weighted contrast applications. Due to the B(0) dependence of the contrast distortions and signal losses, and the heterogeneity of magnetic susceptibility in biological samples, magnetic susceptibility artifacts worsen dramatically for in vivo microimaging at higher fields. Practical applications of T(2)(*)-sensitive techniques enhanced by higher magnetic fields are therefore challenged. This report shows that magnetic susceptibility artifacts dominate T(2)(*)-weighted image contrast at 14 T, and demonstrates that the GESEPI (gradient echo slice excitation profile imaging) technique effectively reduces or eliminates these artifacts at long TE in the highest field (14 T) currently available for (1)H imaging.

Multiple echo frequency-domain image contrast: improved signal-to-noise ratio and T2 (T2*) weighting

Conventional T2- and T2*-weighted image contrasts are produced by waiting a TE period for the transverse magnetic resonance (MR) signals to decay to differentiate tissue types with distinct relaxation rates. Significant image signal-to-noise ratio (SNR) is compromised by this contrast-producing process. In this report, a multiple echo frequency-domain image contrast (MEFIC) method is presented. During the conventional TE period, a multiple echo train modulated by T2 or T2* decay is acquired. A third Fourier transform along the echo direction produces an image set with pixel signal intensity modulated by the spectrum of the decay curve. This method simultaneously enhances image contrast with a large increase in SNR. Experimental studies of cerebral vasogenic edema in immature rats and functional MR imaging studies of the human motor cortex have demonstrated that the MEFIC method produces superior image quality over conventional methods for generating T2- and T2* weighted images.

Effects of the ovarian cycle on sympathetic neural outflow during static exercise

We compared reflex responses to static handgrip at 30% maximal voluntary contraction (MVC) in 10 women (mean age 24.1 +/- 1.7 yr) during two phases of their ovarian cycle: the menstrual phase (days 1-4) and the follicular phase (days 10-12). Changes in muscle sympathetic nerve activity (MSNA; microneurography) in response to static exercise were greater during the menstrual compared with follicular phase (phase effect P = 0.01). Levels of estrogen were less during the menstrual phase (75 +/- 5.5 vs. 116 +/- 9.6 pg/ml, days 1-4 vs. days 10-12; P = 0.002). Generated tension did not explain differences in MSNA responses (MVC: 29.3 +/- 1.3 vs. 28.2 +/- 1.5 kg, days 1-4 vs. days 10-12; P = 0.13). In a group of experiments with the use of 31P-NMR spectroscopy, no phase effect was observed for H+ and H2PO-4 concentrations (n = 5). During an ischemic rhythmic handgrip paradigm (20% MVC), a phase effect was not observed for MSNA or H+ or H2PO-4 concentrations, suggesting that blood flow was necessary for the expression of the cycle-related effect. The present studies suggest that, during static handgrip exercise, MSNA is increased during the menstrual compared with the follicular phase of the ovarian cycle.

Altered mechanisms of sympathetic activation during rhythmic forearm exercise in heart failure

In congestive heart failure (CHF), the mechanisms of exercise-induced sympathoexcitation are poorly defined. We compared the responses of sympathetic nerve activity directed to muscle (MSNA) and to skin (SSNA, peroneal microneurography) during rhythmic handgrip (RHG) at 25% of maximal voluntary contraction and during posthandgrip circulatory arrest (PHG-CA) in CHF patients with those of an age-matched control group. During RHG, the CHF patients fatigued prematurely. At end exercise, the increase in MSNA was similar in both groups (CHF patients, n = 12; controls, n = 10). However, during PHG-CA, in the controls MSNA returned to baseline, whereas it remained elevated in CHF patients (P < 0.05). Similarly, at end exercise, the increase in SSNA was comparable in both groups (CHF patients, n = 11; controls, n = 12), whereas SSNA remained elevated during PHG-CA in CHF patients but not in the controls (P < 0.05). In a separate control group (n = 6), even high-intensity static handgrip was not accompanied by sustained elevation of SSNA during PHG-CA. 31P-nuclear magnetic resonance spectroscopy during RHG demonstrated significant muscle acidosis and accumulation of inorganic phosphate in CHF patients (n = 7) but not in controls (n = 9). We conclude that in CHF patients rhythmic forearm exercise leads to premature fatigue and accumulation of muscle metabolites. The prominent PHG-CA response of MSNA and SSNA in CHF patients suggests activation of the muscle metaboreflex. Because, in contrast to controls, in CHF patients both MSNA and SSNA appear to be under muscle metaboreflex control, the mechanisms and distribution of sympathetic outflow during exercise appear to be different from normal.

Removal of local field gradient artifacts in T2*-weighted images at high fields by gradient-echo slice excitation profile imaging

Development of high magnetic field MRI techniques is hampered by the significant artifacts produced by B0 field inhomogeneities in the excited slices. A technique, gradient-echo slice excitation profile imaging (GESEPI), is presented for recovering the signal lost caused by intravoxel phase dispersion in T2*-weighted images. This technique superimposes an incremental gradient offset on the slice refocusing gradient to sample k-space over the full range of spatial frequencies of the excitation profile. A third Fourier transform of the initial two-dimensional image set generates an image set in which the artifacts produced by the low-order B0 inhomogeneity field gradients in the sample are separated and removed from the high-order microscopic field gradients responsible for T2* contrast. Application to high field brain imaging, at 3.0 T for human and at 9.4 T for immature rat imaging demonstrates the significant improvement in quality of the T2*-weighted contrast images.

Augmented sympathetic tone alters muscle metabolism with exercise: lack of evidence for functional sympatholysis

It is unclear whether sympathetic tone opposes dilator influences in exercising skeletal muscle. We examined high levels of sympathetic tone, evoked by lower body negative pressure (LBNP, -60 mmHg) on intramuscular pH and phosphocreatine (PCr) levels (31P-nuclear magnetic resonance spectroscopy) during graded rhythmic handgrip (30 contractions/min; approximately 17, 34, 52 and 69% maximal voluntary contraction). Exercise was performed with LBNP and without LBNP (Control). At the end of exercise, LBNP caused lower levels of muscle pH (6.59 +/- 0.09) compared with Control (6.78 +/- 0.05; P < 0.05). PCr recovery, an index of mitochondrial respiration, was less during the recovery phase of the LBNP trial. Exercise mean arterial pressure was not altered by LBNP. The protocols were repeated with measurements of forearm blood flow velocity and deep venous samples (active forearm) of hemoglobin (Hb) saturation, pH, and lactate. With LBNP, mean blood velocity was reduced at rest, during exercise, and during recovery compared with Control (P < 0.05). Also, venous Hb saturation and pH levels during exercise and recovery were lower with LBNP and lactate was higher compared with Control (P < 0.05). We conclude that LBNP enhanced sympathetic tone and reduced oxygen transport. At high workloads, there was a greater reliance on nonoxidative metabolism. In other words, sympatholysis did not occur.

Multi-gradient echo with susceptibility inhomogeneity compensation (MGESIC): demonstration of fMRI in the olfactory cortex at 3.0 T

Short image acquisition times and sensitivity to magnetic susceptibility favor the use of gradient echo imaging methods in functional MRI (fMRI). However, magnetic susceptibility effects attributed to air-tissue interfaces also lead to severe signal loss in images of the large inferior frontal and lateral temporal cortices of the human brain, which renders these regions inaccessible to fMRI. The signal loss is caused by the local field gradients in the silce selection direction. A multigradient echo with magnetic susceptibility inhomogeneity compensation method (MGESIC) is proposed to overcome this problem. The MGESIC method effectively corrects the susceptibility artifacts and maintains the advantages of gradient echo methods to both BOLD sensitivity and fast image acquisition. The effectiveness of the MGESIC method is demonstrated by fMRI experimental results within the olfactory cortex.

Dynamics of trimethoprim bound to dihydrofolate reductase--a deuterium NMR study

We have employed deuterium NMR techniques to determine the dynamics of trimethoprim (TMP) in a binary complex with dihydrofolate reductase (DHFR) or in a ternary complex with DHFR and cofactor NADP+ in the fully hydrated state. TMP was deuterated at the following positions: (2',6'-D2)TMP, (3'-Ome-D3)TMP and (3',4'-Ome-D6)TMP. Dynamics of TMP were deduced from lineshape simulation and relaxation measurements of the deuterium NMR powder spectra of the three samples obtained at various temperatures. The results showed that in the polycrystalline state the TMP molecule is very rigid. The only detectable motion is the methyl group rotation at a rate of 10(10) s-1 at 25 degrees C, as determined from simulation of the partially relaxed powder patterns. When bound to DHFR a residual deuterium quadrupole splitting of 140 kHz was observed for (2',6'-D2)TMP at temperatures up to 30 degrees C, suggesting that the benzyl ring in the bound state is also very rigid. In contrast, in the binary complex with DHFR the methoxyl groups of TMP undergo librational motion of 10(7) s-1 about the C3-O bond at an amplitude of 54 degrees for the meta methoxyl group and about the C4-O bond at an amplitude of 70 degrees and similar rate for the para methoxyl group at 30 degrees C. The presence of the cofactor, NADP+, appears to tighten up the binding pocket such that the motion freedom of TMP is more restricted. The rigidity of TMP in a protein complex as revealed by our deuterium NMR results is in accord with the tight binding of TMP to DHFR.

Double-sampled echo-planar imaging at 3 tesla

A persistent artifact in the images acquired by the echo-planar imaging (EPI) method is the Nyquist or N/2 ghost which interferes with the image and reduces the signal-to-noise ratio (SNR). The Nyquist ghost is the result of the time-reversal asymmetry between the even and odd echoes. To eliminate this artifact, the authors present a double-sampled EPI (DSEPI) method in which echoes from each even and odd echo pair are equally phase encoded. The even and odd echoes are separately reconstructed into two distinct images which are then added together. The DSEPI method has been applied to human brain at 3.0 T and shown to be a simple and effective way to eliminate the Nyquist ghost and restore image SNR loss.

Three-dimensional mapping of the static magnetic field inside the human head

Finite element analysis was used to calculate the static magnetic field within the three-dimensional head model. Localized field distributions were evaluated by using the magnetic field histogram technique. Experimental field maps and histograms of the human head were also obtained to validate the simulation results. Field deviations and gradients inside the human head cause NMR signal frequency shifts and line broadening, respectively. Voxels 2 x 2 x 0.5 cm may have frequency differences of more than 2.0 ppm. The linewidth of a single voxel may be broadened by more than 0.5 ppm. Calculated and experimental field maps are in excellent agreement. The global field distortion in the human head is primarily due to the susceptibility difference between air and tissues and their corresponding geometrical shapes.

Influences of gender on sympathetic nerve responses to static exercise

We compared reflex responses to static handgrip at 30% maximal voluntary contraction (MVC) in 26 untrained men (mean age 35 +/- 3 yr) and 23 untrained women (mean age 39 +/- 4 yr). Women demonstrated attenuated increases in blood pressure and muscle sympathetic nerve activity (MSNA; by microneurography) compared with men. This difference was also observed during a period of posthandgrip circulatory arrest. 31P-nuclear magnetic resonance (NMR) spectroscopy studies demonstrated attenuations in the production of diprotonated phosphate and the development of cellular acidosis in women compared with men. Subjects also performed ischemic handgrip to fatigue. During this paradigm, MSNA responses were similar in the two groups, suggesting that freely perfused conditions are necessary for the full expression of the gender effect. Finally, we examined MSNA responses to adductor pollicus exercise in 7 men (26 +/- 1 yr) and 6 women (25 +/- 2 yr). MVC values and times to fatigue were similar in the two groups (MVC: men, 4.3 +/- 0.4 kg; women, 4.0 +/- 0.3 kg; not significant. Time to fatigue: men, 209 +/- 16 s; women, 287 +/- 50 s; not significant). At periods of end exercise and postexercise circulatory arrest, MSNA responses were attenuated in the women compared with the men. We conclude that, during nonischemic static exercise, sympathetic neural outflow is less in women compared with men. This response is due to an attenuated metaboreflex in women. Finally, on the basis of the adductor pollicus experiments, this effect appears independent of muscle mass, workload, and the level of training.

Sympathetic nerve activity during prolonged rhythmic forearm exercise

Exercise is a potent stimulus to activate the sympathetic nervous system. Previous work suggests that metabolite-sensitive muscle afferents are activated near the point of fatigue, and, when activated, they determine the muscle sympathetic nerve activity (MSNA) response to isometric forearm exercise. Yet, studies using a more prolonged rhythmic exercise paradigm suggest that the sympathetic nervous system can be activated in a more graded fashion. The purpose of this study was to determine whether metaboreceptor stimulation would also be responsible for MSNA responses to prolonged rhythmic isotonic forearm exercise. Subjects (n = 16) performed rhythmic isotonic forearm exercise at 25% maximal voluntary contraction for 30 min as we measured MSNA (microneurography). We observed progressive increases in MSNA with a peak increase of 161 units from a baseline value of 180 units. We also performed posthandgrip circulatory arrest (PHG-CA) in nine of these subjects. This maneuver isolates the metaboreceptor contribution to MSNA. During PHG-CA, delta MSNA values were not different from those observed during a freely perfused recovery period (n = 7). We also compared MSNA responses during the rhythmic paradigm with those seen during a static protocol at 40% of maximal voluntary contraction in five subjects. The two types of exercise caused similar increases in MSNA, but only the static paradigm was associated with a sustained MSNA response during PHG-CA. Finally, 31P-nuclear magnetic resonance was used to evaluate muscle metabolic responses during rhythmic and static forearm exercise (n = 6). Static exercise caused muscle acidosis and an increase in H2PO4-, whereas rhythmic exercise had no effect on muscle metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

RF coil optimization: evaluation of B1 field homogeneity using field histograms and finite element calculations

Two-dimensional (2D) finite element analysis has been used to solve the full set of Maxwell's equations for the 2D magnetic field of radiofrequency (RF) coils. The field histogram method has been applied to evaluate and optimize the magnetic field homogeneity of some commonly used RF coils: the saddle coil, the slotted tube resonator, the multiple elements coil and the birdcage resonator, as well as the radial plate coil. Each coil model represents a cross-section of an infinitely long cylinder. The optimum configuration of each of these five RF coils is suggested. It was found that field homogeneity is more strongly dependent on the coil's window angle than on any other parameter. Additionally, eddy currents in the coil's conductive elements distort the current and magnetic field distribution. The frequency dependence of this eddy current distortion is analyzed and discussed.

The effect of hydration on the dynamics of trimethoprim bound to dihydrofolate reductase. A deuterium NMR study

To determine the effect of hydration on the dynamics of a protein complex, we used deuterium nuclear magnetic resonance (NMR) techniques to examine a trimethoprim (TMP)/E. coli dihydrofolate reductase (DHFR) complex in its lyophilized, partially hydrated, polycrystalline, and ammonium sulfate-precipitated states. The results indicate that TMP is rigid in the lyophilized powder state. The dynamic behavior could be restored by partial rehydration. At 30 wt% hydration the deuterium spectrum of the partially hydrated sample was indistinguishable from that of the polycrystalline and ammonium sulfate-precipitated samples, suggesting that the structure of the protein/TMP complex is similar in the three physical states. Furthermore, we found that the para- and meta-methoxyl groups have very different dynamical behavior.