Filler Mixed Into Adhesives Does Not Necessarily Improve Their Mechanical Properties

OBJECTIVES

To investigate the influence of filler type/loading on the micro-tensile fracture strength (μTFS) of adhesive resins, as measured 'immediately' upon preparation and after 1-week water storage ('water-stored').

METHODS

The morphology and particle-size distribution of three filler particles, referred to as 'Glass-S' (Esschem Europe), 'BioUnion' (GC), and 'CPC_Mont', were correlatively characterized by SEM, TEM, and particle-size analysis. These filler particles were incorporated into an unfilled adhesive resin ('BZF-29unfilled', GC) in different concentrations to measure the 'immediate' μTFS. After 1-week water storage, the 'water-stored' μTFS of the experimental particle-filled adhesive resins with the most optimum filler loading, specific for each filler type, was measured. In addition, the immediate and water-stored μTFS of the adhesive resins of three experimental two-step universal adhesives based on the same resin matrix but varying for filler type/loading, coded as 'BZF-21' (containing silica and bioglass), 'BZF-29' (containing solely silica), and 'BZF-29_hv' (highly viscous with a higher silica loading than BZF-29), and of the adhesive resins of the gold-standard adhesives OptiBond FL ('Opti-FL', Kerr) and Clearfil SE Bond 2 ('C-SE2', Kuraray Noritake) was measured along with that of BZF-29unfilled (GC) serving as control/reference. Statistics involved one-way and two-way ANOVA followed by post-hoc multiple comparisons (α<0.05).

RESULTS

Glass-S, BioUnion, and CPC_Mont represent irregular fillers with an average particle size of 8.5-9.9 μm. Adding filler to BZF-29unfilled decreased μTFS regardless of filler type/loading. One-week water storage reduced μTFS of all adhesive resins except BZF-21, with the largest reduction in μTFS recorded for BZF-29unfilled. Among the three filler types, the μTFS of the 30 wt% Glass-S and 20 wt% BioUnion filled adhesive resin was not significantly different from the μTFS of BZF-29unfilled upon water storage.

CONCLUSIONS

Adding filler particles into adhesive resin did not enhance its micro-tensile fracture strength but appeared to render it less sensitive to water storage as compared to the unfilled adhesive resin investigated.

Practical use of the central venous access port for contrast-enhanced CT: comparison with peripheral intravenous access regarding enhancement and safety

AIM

To evaluate the efficacy of using the central venous (CV) port compared with peripheral intravenous access for contrast-material injection for contrast enhancement during the portal venous phase.

MATERIALS AND METHODS

Patients were divided into three groups: CV delay, CV routine, and peripheral access (PA) groups. Patients in the CV delay group underwent injection in the arm-down position with an additional delay, while those in the CV routine and PA groups underwent injections with the routine injection protocol for portal venous phase imaging. Contrast enhancement was evaluated by measuring the mean radiodensity (Hounsfield units) values for the aortic arch, abdominal aorta, inferior vena cava, portal vein, and spleen. The peak injection pressure was recorded and compared among the three groups.

RESULTS

No complications related to power injection were observed during 119 contrast-material injections performed using the CV port device. The CV delay group showed significantly lower radiodensity values than the PA group (165.7 ± 20.1 versus 181 ± 19 HU [p<0.01] for the portal vein); however, no significant differences in mean radiodensity values were observed between the CV routine and PA groups (p>0.05). The median peak injection pressure was 73.5, 67, and 47 psi in the CV delay, CV routine, and PA groups, respectively (p<0.01).

CONCLUSION

The CV port can be used for safe contrast-material injection while maintaining contrast enhancement on portal venous phase comparable to that achieved with peripheral intravenous access.

A simple method to shorten the apparent dead time in the dosimetry of Lu-177 for targeted radionuclide therapy using a gamma camera

BACKGROUND

The dead-time loss reportedly degrades the accuracy of dosimetry using a gamma camera for targeted radionuclide therapy with Lu-177; therefore, the dead-time loss needs to be corrected. However, the correction is challenging. In this study, we propose a novel and simple method to shorten the apparent dead time rather than correcting it through experiments and Monte Carlo simulations.

METHODS

An energy window of 208 keV ± 10 % is generally used for the imaging of Lu-177. Lower-energy gamma photons and X-rays of Lu-177 do not contribute to image formation but lead to dead-time losses. In our proposed method, a thin lead sheet was used to shield gamma photons and X-rays with energies lower than 208 keV, while detecting 208 keV gamma photons that penetrated the thin sheet. We measured and simulated the energy spectra and count rate characteristics of a clinical gamma camera system using a cylindrical phantom filled with a Lu-177 solution. Lead sheets of 1.0- and 0.5-mm thicknesses were used as thin shields, and the dead-time losses in tumour imaging with consumed Lu-177 were simulated.

RESULTS

The apparent dead times with lead sheets of 1.0- and 0.5-mm thicknesses and without a lead sheet were 1.7, 1.9, and 5.8 µs for an energy window of 208 keV ± 10 %, respectively. The dead-time losses could be reduced from 10 % to 1.3 % using the 1.0-mm thick lead sheet in the simulated imaging of tumour.

CONCLUSION

Our method is promising in clinical situations and studies on Lu-177 dosimetry for tumours.

A triple-imaging-modality system for simultaneous measurements of prompt gamma photons, prompt x-rays, and induced positrons during proton beam irradiation

Objective. Prompt gamma photon, prompt x-ray, and induced positron imaging are possible methods for observing a proton beam's shape from outside the subject. However, since these three types of images have not been measured simultaneously nor compared using the same subject, their advantages and disadvantages remain unknown for imaging beam shapes in therapy. To clarify these points, we developed a triple-imaging-modality system to simultaneously measure prompt gamma photons, prompt x-rays, and induced positrons during proton beam irradiation to a phantom.Approach. The developed triple-imaging-modality system consists of a gamma camera, an x-ray camera, and a dual-head positron emission tomography (PET) system. During 80 MeV proton beam irradiation to a polymethyl methacrylate (PMMA) phantom, imaging of prompt gamma photons was conducted by the developed gamma camera from one side of the phantom. Imaging of prompt x-rays was conducted by the developed x-ray camera from the other side. Induced positrons were measured by the developed dual-head PET system set on the upper and lower sides of the phantom.Main results. With the proposed triple-imaging-modality system, we could simultaneously image the prompt gamma photons and prompt x-rays during proton beam irradiation. Induced positron distributions could be measured after the irradiation by the PET system and the gamma camera. Among these imaging modalities, image quality was the best for the induced positrons measured by PET. The estimated ranges were actually similar to those imaged with prompt gamma photons, prompt x-rays and induced positrons measured by PET.Significance. The developed triple-imaging-modality system made possible to simultaneously measure the three different beam images. The system will contribute to increasing the data available for imaging in therapy and will contribute to better estimating the shapes or ranges of proton beam.

Development of an event-by-event based Li-ZnS(Ag) neutron imaging detector with selective neutron detection capability

High sensitivity and high resolution is desired in such technologies as neutron radiography. However, the contamination of gamma photons in neutron images decreases the accuracy of neutron radiography. To solve this problem, we developed an event-by-event based neutron imaging system that can selectively detect neutrons. The developed neutron imaging system consists of an Li-ZnS(Ag) scintillator plate optically coupled to a flat panel photomultiplier tube (FP-PMT) with a light guide. Scintillation light emitted from the Li-ZnS(Ag) by the interaction with neutron-induced particles is used to calculate the position based on the center of mass calculations. The spatial resolution of the neutron imaging detector is ∼2.3 mm FWHM, and the sensitivity for 252Cf at 2 cm from the source with 2-cm-thick polystyrene is 20 cps/MBq. Background count fraction from 60Co gamma photons was 0.2 %. For various types of neutron absorption phantoms, high-contrast and high-resolution neutron images are obtained with the developed neutron imaging detector using a252Cf neutron source.

A comparative study of EM-CCD and CMOS cameras for particle ion trajectory imaging

High-resolution and real-time imaging of particle ion trajectories is essential in nuclear medicine and nuclear engineering. One potential method to achieve high-resolution real-time trajectory imaging of particle ions involves utilizing an imaging system that integrates a scintillator plate with a magnifying unit and a cooled electron multiplying charge-coupled device (EM-CCD) camera. However, acquiring an EM-CCD camera might prove challenging due to the discontinuation of CCD sensor manufacturing by vendors. As an alternative imaging approach, a low-noise, high-sensitivity camera utilizing a cooled complementary metal-oxide-semiconductor (CMOS) sensor offers a promising solution for imaging particle ion trajectories. Yet, it remains uncertain whether CMOS-based cameras can perform as effectively as CCD-based cameras in capturing particle ion trajectories. To address these concerns, we conducted a comparative analysis of the imaging performance between a CMOS-based system and an EM-CCD-based system for capturing alpha particle trajectories. The results revealed that both systems could image the trajectories of alpha particle, but the spatial resolution with the CMOS-based camera exceeded that of the EM-CCD-based camera, primarily due to the smaller pixel size of the sensor. While the signal-to-noise ratio (SNR) of the trajectory image from the CMOS-based camera initially lagged behind that from the EM-CCD-based camera, this disparity was mitigated by implementing binning techniques on the CMOS-based camera images. In conclusion, our findings suggest that a cooled CMOS camera could serve as a viable alternative for imaging particle ion trajectories.

Estimating blurless and noise-free Ir-192 source images from gamma camera images for high-dose-rate brachytherapy using a deep-learning approach

Objective. Precise monitoring of the position and dwell time of iridium-192 (Ir-192) during high-dose-rate (HDR) brachytherapy is crucial to avoid serious damage to normal tissues. Source imaging using a compact gamma camera is a potential approach for monitoring. However, images from the gamma camera are affected by blurring and statistical noise, which impact the accuracy of source position monitoring. This study aimed to develop a deep-learning approach for estimating ideal source images that reduce the effect of blurring and statistical noise from experimental images captured using a compact gamma camera.Approach. A double pix2pix model was trained using the simulated gamma camera images of an Ir-192 source. The first model was responsible for denoising the Ir-192 images, whereas the second model performed super resolution. Trained models were then applied to the experimental images to estimate the ideal images.Main results. At a distance of 100 mm between the compact gamma camera and the Ir-192 source, the difference in full width at half maximum (FWHM) between the estimated and actual source sizes was approximately 0.5 mm for a measurement time of 1.5 s. This difference has been improved from approximately 2.7 mm without the use of DL. Even with a measurement time of 0.1 s, the ideal images could be estimated as accurately as in the 1.5 s measurements. This method consistently achieved accurate estimations of the source images at any position within the field of view; however, the difference increased with the distance between the Ir-192 source and the compact gamma camera.Significance. The proposed method successfully provided estimated images from the experimental images within errors smaller than 0.5 mm at 100 mm. This method is promising for reducing blurring and statistical noise from the experimental images, enabling precise real-time monitoring of Ir-192 sources during HDR brachytherapy.

Comparison of organ dose from chest radiography with varying beam quality and constant exposure index

The optimum X-ray tube voltage for chest radiographic examinations remains unclear; hence, the tube voltage varies between medical facilities. An exposure index (EI) was proposed to standardize the parameters for radiographic examinations. However, even if identical EI values are used to examine the same person, organ doses may vary due to differences in tube voltages. In this study, the variation in organ doses between different beam qualities under identical EI values for chest radiographic examinations was investigated using Monte Carlo simulations. A focused anti-scatter grid as well as standard and larger physique-type medical internal radiation dose (MIRD) phantoms were studied under tube voltages of 90, 100, 110, and 120 kVp. The organ doses in the MIRD phantom increased as the X-ray tube voltage decreased, even with identical EI values. The absorbed doses in the lungs of standard and large-sized MIRD phantoms at 90 kVp were 23% and 35% higher than those at 120 kVp, respectively. The doses to organs other than the lung at 90 kVp were also higher than those at 120 kVp. From the perspective of reducing radiation doses, a tube voltage of 120 kVp is considered better for chest examinations compared with a tube voltage of 90 kVp under identical EI values.

Hybrid imaging of prompt x-rays and induced positrons using a pinhole gamma camera during and after irradiation of protons

Objective. Prompt x-ray imaging using a low-energy x-ray camera is a promising method for observing a proton beam's shape from outside the subject. Furthermore, imaging of positrons produced by nuclear reactions with protons is a possible method for observing the beam shape. However, it has not been possible to measure these two types of images with a single imaging system due to the limited imaging capability of existing systems. Imaging of both prompt x-rays and the distribution of positrons may compensate for the shortcomings of each method.Approach. We conducted imaging of the prompt x-ray using a pinhole x-ray camera during irradiation with protons in list mode. Then, after irradiation with protons, imaging of annihilation radiations from the produced positrons was conducted using the same pinhole x-ray camera in list mode. After this imaging, list-mode data were sorted to obtain prompt x-ray images and positron images.Main results. With the proposed procedure, we could measure both prompt x-ray images and induced positron images with a single irradiation by a proton beam. From the prompt x-ray images, ranges and widths of the proton beams could be estimated. The distributions of positrons were slightly wider than those of the prompt x-rays. From the time sequential positron images, we could derive the time activity curves of the produced positrons.Significance. Hybrid imaging of prompt x-rays and induced positrons using a pinhole x-ray camera was achieved. The proposed procedure would be useful for measuring prompt x-ray images during irradiation to estimate the beam structures as well as for measuring the induced positron images after irradiation to estimate the distributions and time activity curves of the induced positrons.

Development of an ultrahigh resolution real time alpha particle imaging system for observing the trajectories of alpha particles in a scintillator

High-resolution imaging of alpha particles is required in the detection of alpha radionuclides in cells or small organs for the development of radio-compounds for targeted alpha-particle therapy or other purposes. We developed an ultrahigh resolution, real time alpha-particle imaging system for observing the trajectories of alpha particles in a scintillator. The developed system is based on a magnifying unit and a cooled electron multiplying charge-coupled device (EM-CCD) camera, combined with a 100-µm-thick Ce-doped Gd₃Al₂Ga₃O₁₂ (GAGG) scintillator plate. Alpha particles from an Am-241 source were irradiated to the GAGG scintillator and imaged with the system. Using our system, we measured the trajectories of the alpha particles having different shapes in real time. In some of these measured trajectories, the line shapes of the alpha particles that flew in the GAGG scintillator were clearly observed. The lateral profiles of the alpha-particle trajectories were imaged with widths of ~ 2 µm. We conclude that the developed imaging system is promising for research on targeted alpha-particle therapy or other alpha particle detections that require high spatial resolution.

Technical note: Short-time sequential high-energy gamma photon imaging using list-mode data acquisition system for high-dose-rate brachytherapy

PURPOSE

Measurement of the dwell time and moving speed of a high-activity iridium-192 (Ir-192) source used for high-dose-rate (HDR) brachytherapy is important for estimating the precise dose delivery to a tumor. For this purpose, we used a cerium-doped yttrium aluminum perovskite (YA1O₃ :YAP(Ce)) gamma camera system, combined with a list-mode data acquisition system that can acquire short-time sequential images, and measured the dwell times and moving speeds of the Ir-192 source.

METHODS

Gamma photon imaging was conducted using the gamma camera in list mode for the Ir-192 source of HDR brachytherapy with fixed dwell times and positions. The acquired list-mode images were sorted to millisecond-order interval time sequential images to evaluate the dwell time at each position. Time count rate curves were derived to calculate the dwell time at each source position and moving speed of the source.

RESULTS

We could measure the millisecond-order time sequential images for the Ir-192 source. The measured times for the preset dwell times of 2 s and 10 s were 1.98 to 2.00 s full width at half maximum (FWHM) and 10.0 s FWHM, respectively. The dwell times at the first dwell position were larger than those at other positions. We also measured the moving speeds of the source after the dwells while moving back to the afterloader and found the speed increased with the distance from the edge of the field of view to the last dwell position.

CONCLUSION

We conclude that millisecond-order time sequential imaging of the Ir-192 source is possible by using a gamma camera and is useful for evaluating the dwell times and moving speeds of the Ir-192 source.

Mechanism of Budded Virus Envelope Fusion into a Planar Bilayer Lipid Membrane on a SiO2 Substrate

Artificial planar bilayer lipid membranes (BLMs) are simple models of cellular systems under physically and chemically controlled conditions, and they have been used to investigate membrane protein activity. Baculovirus-budded virus (BV) systems can express recombinant membrane proteins. In this study, aiming for membrane protein reconstitution, we examined the fusion of BVs containing recombinant membrane proteins into artificial planar BLMs on a Si microwell substrate. BV fusion with the BLMs depended on the pH of the solution, and it was enhanced at lower pH. Based on fluorescence recovery after photobleaching (FRAP) measurement, the fusion state of BVs was evaluated, and full fusion at low pH was confirmed. The fluorescent labeling the membrane proteins was also observed in the freestanding part of the BLMs as well as in the supported part. These results demonstrate the effectiveness of BLMs as a platform to examine detailed fusion dynamics of BVs. Furthermore, this study revealed that the fusion of BVs is a promising method for reconstituting membrane proteins to artificial freestanding BLMs for the development of biodevices with which we can examine membrane protein activity.

Performance evaluation of YAlO3 scintillator plates with different Ce concentrations

Since Ce-doped YAlO₃ (YAP(Ce)) scintillators have small non-proportionality, it is useful to develop a radiation imaging detector for low-energy gamma photons or X-rays. However, the YAP(Ce) performance with different Ce concentrations remains unclear. Consequently, we measured the basic performance of YAP(Ce) plates with different Ce concentrations. We used three types of YAP(Ce) scintillator plates with different Ce concentrations: 0.05% Ce, 1% Ce, and 2% Ce. The YAP(Ce) plates were 10 mm × 10 mm x 0.5 mm. We measured and compared the energy spectra, the decay times, the α-γ ratio, and the non-proportionality. We also evaluated the relation between these performances and the Ce concentrations. The light output of a YAP(Ce) showed positive correlation with the Ce concentrations, and the decay time of the YAP(Ce) showed a negative correlation with them. The energy resolution slightly improved for a YAP(Ce) with higher Ce concentrations. We found the α-γ ratio were slightly larger for higher Ce concentrations. The YAP(Ce) plate with a 2% Ce had the highest light output and the best energy resolution as well as the shortest decay time. Based on these results, the YAP(Ce) plate with a concentration of 2% Ce is a better selection for the development of radiation detectors or radiation imaging detectors for low-energy gamma photons or X-rays as well as alpha particles.

Visceral fat accumulation and left atrial phasic function in the general population

Background

Obesity carries independent risk for incident atrial fibrillation (AF), although the impact of abdominal fat distribution on LA morphological and functional remodeling is not fully elucidated. Speckle-tracking echocardiography is a novel and sensitive tool that allows quantification and detection of subtle alterations in left atrial (LA) phasic function.

Purpose

This study aimed to investigate whether increased visceral adiposity is independently associated with impaired LA phasic function in a community-based cohort.

Methods

We included 527 participants without overt cardiac disease who underwent laboratory testing, abdominal computed tomographic examination and speckle-tracking echocardiography. Abdominal adiposity was quantitatively assessed as visceral fat area (VFA) and subcutaneous fat area (SFA) at the level of the umbilicus. Speckle-tracking echocardiography was performed to assess LA phasic function including reservoir, conduit and pump strain as well as left ventricular global longitudinal strain (LVGLS).

Results

Mean age was 57±10 years and 362 of the participants (69%) were men. LA reservoir and conduit strain were decreased according to the VFA quartiles (both p&lt;0.05), whereas there was no significant difference in LA volume index and LA pump strain. When stratified by SFA, there was no significant differences in LA volume index and all LA phasic strain across the quartiles. In multivariable analysis, VFA as continuous variable was significantly associated with LA conduit strain, independent of traditional cardiovascular risk factors, pertinent laboratory parameters and LV morphology and function including LVGLS (standardized b=−0.146, p=0.011). Representative cases are shown in the Figure.

Conclusion

In a sample of the general population, VFA accumulation was independently associated with worse LA conduit strain, which may be involved in the pathophysiological mechanism of obesity-related AF.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Yamauchi Susumu Scholarship for Cardiovascular Research

Carotid intima-media thickness and subclinical left heart dysfunction in the general population

Background

Although carotid intima-media thickness (IMT) is an established marker of atherosclerosis and carries independent risk for cardiovascular disease, its possible association with subclinical cardiac dysfunction has not been extensively evaluated. Left ventricular global longitudinal strain (LVGLS) and peak left atrial longitudinal systolic strain (PALS) can detect subclinical left heart dysfunction.

Purpose

This study aimed to investigate the association between carotid IMT and subclinical left heart dysfunction in a large sample of the general population without overt cardiac disease.

Methods

We examined 1,161 participants who underwent extensive cardiovascular examination. Ultrasonography of common carotid artery was performed for the measurement of maximal carotid IMT. LVGLS and PALS were assessed by 2-dimensional speckle-tracking echocardiography.

Results

Mean age was 62±12 years, and 56% were male. The prevalence of abnormal LVGLS (&gt;−18.6%) and PALS (&lt;31.4%) was greatest in the upper quartile of carotid IMT (both p&lt;0.001; Figure). In multivariable analyses, carotid IMT was associated with abnormal LVGLS (adjusted odds ratio = 1.33 per 1SD increase of IMT, p=0.003) as well as PALS (adjusted odds ratio = 1.33 per 1SD increase of IMT, p=0.005) independent of traditional cardiovascular risk factors, echocardiographic parameters including LV ejection fraction, LV mass index and diastolic dysfunction, and pertinent laboratory parameters. The independent association between carotid IMT and PALS persisted even after adjustment for LVGLS. When carotid IMT was examined as a categorical variable, the upper quartile of carotid IMT carried a significant risk of abnormal LVGLS and PALS in a fully-adjusted model including echocardiographic and laboratory parameters (adjusted odds ratio 2.27 and 3.03 vs. lower quartile, both p&lt;0.01).

Conclusion

Participants with increased IMT had significantly impaired LV and LA function in an unselected community-based cohort. This association may be involved in the higher incidence of cardiovascular disease in individuals with increased carotid IMT.

Funding Acknowledgement

Type of funding source: None

Sex-specific difference in the association between arterial stiffness and subclinical left ventricular dysfunction

Background

Increased arterial stiffness has been proposed as one of the key mechanisms of incident heart failure with preserved ejection fraction (HFpEF). However, the possible association between arterial stiffness and subclinical left ventricular (LV) dysfunction and possible sex-specific differences remain unclarified. LV strain is emerging as a highly sensitive tool to unmask early LV abnormalities.

Purpose

We investigated whether increased arterial stiffness is independently associated with subclinical LV dysfunction in a large community-based cohort without overt cardiovascular disease.

Methods

We examined 1,155 participants who underwent extensive cardiovascular examination. Speckle-tracking echocardiography was employed to assess LV global longitudinal strain (LVGLS) and circumferential strain (GCS), and arterial stiffness was assessed by cardio-ankle vascular index (CAVI).

Results

Mean age was 62±12 years, and 56% were male. CAVI as continuous variable was associated with abnormal LVGLS (&gt;−18.6%), independent of cardiovascular risk factors and pertinent laboratory and echocardiographic parameters (adjusted odds ratio [OR] 1.23, p=0.034), whereas there was no relationship with LVGCS. In sex-stratified analysis, more pronounced association between quartiles of CAVI and abnormal LVGLS was observed in women than in men (unadjusted OR = 6.43 in women and 2.46 in men for upper quartile vs. lower quartile, both p&lt;0.01; Figure). Multivariable analyses demonstrated that CAVI was significantly associated with abnormal LVGLS independent of cardiovascular risk factors in both sexes. However, after further adjustment for LV mass index and diastolic parameters, the independent association persisted in women (adjusted OR 1.49, p=0.041), but not in men (adjusted OR 1.15, p=0.209).

Conclusion

Increased arterial stiffness was independently associated with decreased LVGLS even in the absence of overt cardiovascular disease; a sex-specific pattern exists in the alteration of vascular-ventricular coupling, which might partially explain the greater susceptibility to HFpEF in women.

Funding Acknowledgement

Type of funding source: None

Apple latent spherical virus (ALSV)-induced gene silencing in a medicinal plant, Lithospermum erythrorhizon

Lithospermum erythrorhizon is a medicinal plant that produces shikonin, a red lipophilic naphthoquinone derivative that accumulates exclusively in roots. The biosynthetic steps required to complete the naphthalene ring of shikonin and its mechanism of secretion remain unclear. Multiple omics studies identified several candidate genes involved in shikonin production. The functions of these genes can be evaluated using virus-induced gene silencing (VIGS) systems, which have been shown advantageous in introducing iRNA genes into non-model plants. This study describes the development of a VIGS system using an apple latent spherical virus (ALSV) vector and a target gene, phytoene desaturase (LePDS1). Virus particles packaged in Nicotiana benthamiana were inoculated into L. erythrorhizon seedlings, yielding new leaves with albino phenotype but without disease symptoms. The levels of LePDS1 mRNAs were significantly lower in the albino plants than in mock control or escape plants. Virus-derived mRNA was detected in infected plants but not in escape and mock plants. Quantitative PCR and deep sequencing analysis indicated that transcription of another hypothetical PDS gene (LePDS2) also decreased in the defective leaves. Virus infection, however, had no effect on shikonin production. These results suggest that virus-based genetic transformation and the VIGS system silence target genes in soil-grown L. erythrorhizon.

P1357 Left atrial function decreases with age in patients with repaired tetralogy of Fallot decrease

BACKGROUND

Left ventricular function has been shown to be an important prognostic indicator in patients with repaired tetralogy of Fallot (rTOF) and tends to decrease with age. In recent years, left atrial (LA) function was reported to be a useful prognostic indicator more than or equal to left ventricular function in acquired heart diseases. However, atrial function in rTOF has not yet been sufficiently examined.

PURPOSE

The aim of this study was to investigate the relationship between LA dysfunction and age in rTOF using strain analysis.

METHODS

In order to assess the relationship between LA function and age, we recruited 59 patients with rTOF ranging in age from 5-40 years. We stratified the patients into 3 groups (T1: 5-10 years, T2: 11-20 years, T3: 21-40 years) and divided 54 controls of similar age into 3 corresponding groups (N1, N2, and N3). Two-dimensional speckle tracking images (2D-STI) obtained from four- and two-chamber views were used to assess LA functions by measuring reservoir, conduit, and pump strain. Additionally, we measured the strain rate (SR) in the systole, early diastole, and late diastole.

RESULTS

LA reservoir strain (37.4 ± 2.2% vs. 47.9 ± 1.7%, P= 0.004), LA pump strain (8.3 ± 1.4% vs. 14.1 ± 2.7%, p &lt;.001), atrial systolic LA-SR (1.5 ± 0.4% vs. 2.4 ± 0.6%, p &lt;.001), and systolic LA-SR (1.5 ± 0.3% vs. 2.1 ± 0.4%, p = 0.003) were significantly decreased in T3 compared with N3. Although only LA conduit strain decreased with aging (r = -0.3204, p = 0011) in controls, all of the LA reservoir (r = -0.325, p = 0.020), conduit (r = -0.314, p = 0.025), and pump strain (r = -0.481, p &lt; 0.001) in rTOF decreased with aging.

Early diastole SR was significantly decreased in the T1 and T3 groups compared with the N1 and N3 groups (T1 vs N1, 3.00 ± 0.63% vs. 4.03 ± 0.0.80%, p &lt;.0.001, T3 vs N3, 2.31 ± 0.57% vs.3.31 ± 0.47%, p &lt; 0.001). Both systolic SR and late diastole SR decreased in T3 group compared with the N3 (1.54 ± 0.32% vs. 2.08 ± 0.42%, p = 0.003, 1.42 ± 0.32% vs.2.42 ± 0.61%, p &lt; 0.001), respectively. Although only early diastole SR decreased with aging (r = -0.415, p &lt; 0.001) in controls, all of the systole (r = -0.287, p = 0.041), early diastole (r = -0.337, p = 0.019), and late diastole SR (r = -0.407, p = 0.003) in rTOF decreased with aging.

CONCLUSIONS

In rTOF, most of the LA functions assessed by strain analysis decreased compared to normal controls in over 20 years old age. Furthermore, all measured functions decreased with age in rTOF while only two parameters decreased with age in normal controls. These results suggest that LA function may be an important indicator in long-term rTOF follow-up. These are new insights into LA function in patients with rTOF.

P198 Validation of the updated blood pressure classification based on the ACC/AHA guidelines in the perspective of subclinical atherosclerosis in general population

Background

American College of Cardiology (ACC) and American Heart Association (AHA) revised their guideline for hypertension in 2017, and the threshold of normal blood pressure (BP) was lowered, in the perspective of the prevention of optimal prevention of cardiovascular diseases. On the other hand European Society of Cardiology and European Society of Hypertension updated their guideline in 2018. However, the cut off value of blood pressure for hypertension was not changed (sBP ≥ 140 mmHg or dBP ≥ 90 mmHg). Therefore, the validity of the updated guideline of ACC/AHA still remains controversial, and there is so far no evidence regarding the BP category according to the ACC/AHA guidelines in general population.

Purpose

We aimed to clarify the association between the updated BP classification and carotid intima-media thickness (IMT), as a marker of subclinical atherosclerosis, in general population using a community-based cohort.

Methods

We analyzed 1,241 subjects undergoing medical check-ups at the University of Tokyo Hospital. Study subjects were categorized into 3 groups based on their BP levels: normal pressure (sBP &lt; 130 mmHg and dBP &lt; 80 mmHg); stage 1 hypertension (130 mmHg ≤ sBP &lt; 140 mmHg or 80 mmHg ≤ dBP&lt; 90 mmHg); and stage 2 hypertension (sBP ≥ 140 mmHg or dBP ≥ 90 mmHg, including subjects prescribed with antihypertensive agents). We defined carotid plaque as IMT ≥ 1.1 mm.

Results

Out of 1,241 subjects, 556 patients (44.8%) were categorized in the normal BP group, whereas 236 subjects (19.0%) and 449 subjects (36.2%) were categorized in the stage 1 and stage 2 hypertension groups, respectively. Among subjects categorized in the stage 2 hypertension group, 348 subjects (77.5%) patients were taking antihypertensive medications. Percentage of male gender, and age increased with BP category. Classical CVD risk factors such as diabetes mellitus and hypercholesterolemia were common in subjects in the hypertension groups. IMT increased as the BP category progressed from normal BP to stage 2 hypertension. The prevalence of carotid plaque also increased with an increase in BP. Univariate regression analysis showed the linear association between the BP category and prevalence of carotid plaque. Multivariable logistic regression analysis demonstrated that BP category as well as age ≥60 years, male gender, body mass index ≥25 kg/m2, and diabetes mellitus were independently associated with carotid plaque formation. BP category was associated with the prevalence of carotid plaque formation in any subgroup divided by age (&lt; 60 years old, and ≥60 years old) or gender.

Conclusions

Thickening of IMT developed in stage 1 hypertension, and further increased in stage 2 hypertension even in general population, indicating the importance of the therapeutic intervention according to the updated ACC/AHA guideline for hypertension.

Abstract P198 Figure.

Membrane fusion and infection abilities of baculovirus virions are preserved during freezing and thawing in the presence of trehalose

Budded viruses (BVs) of baculovirus such as Autographa californica nucleopolyhedrovirus (AcNPV) have recently been studied as biological nanomaterials, and methods for their longer-term storage without deterioration would be desirable. The cryopreservation of virions with a naturally occurring saccharide like trehalose as a cryoprotectant is known to be useful for maintaining the viral structure and function. In this study, we examined how useful trehalose is as protectant for BV cryopreservation during repeated freeze-thaw cycles: 1) membrane fusion between liposomes (multilamellar vesicles, MLVs) and BVs, 2) infection of insect culture cells (Sf9 cells) by RFP-expressing BVs, and 3) morphologies of these BVs were investigated by fluorescent dequenching assay, fluorescence microscopy, and transmission electron microscopy (TEM), respectively. The results suggest that the BVs deteriorate in quality with each freeze-thaw cycle, and this deterioration can be diminished with the use of trehalose to an extent similar to that seen with storage on ice.

2140Association of arterial stiffness with left atrial structure and phasic function: a community-based cohort study

Background

Increased arterial stiffness is recognized as an independent risk factor for atrial fibrillation, although the pathophysiological mechanisms remain unclear. Cardio-ankle vascular index (CAVI) is emerging as an important tool to assess arterial stiffness noninvasively which is derived from the concept of stiffness β index and is less dependent on blood pressure at the time of measurement than pulse wave velocity.

Purpose

This study aimed to investigate the association of arterial stiffness with left atrial (LA) volume and phasic function in a community-based cohort.

Methods

We included 1,156 participants without overt cardiovascular disease who underwent extensive cardiovascular examination. Arterial stiffness was evaluated by CAVI. Speckle-tracking echocardiography was employed to evaluate LA phasic function including reservoir, conduit and pump strain as well as left ventricular global longitudinal strain (LVGLS).

Results

CAVI was negatively correlated with reservoir and conduit strain (r=−0.37 and −0.45, both p<0.001; Figure), whereas weakly, but positively correlated with LA volume index and pump strain (r=0.12 and 0.09, both p<0.01). In multivariable analysis, CAVI was significantly associated with reservoir and conduit strain independent of traditional cardiovascular risk factors, pertinent laboratory parameters and LV morphology and function including LVGLS (standardized β=−0.22 and −0.26, respectively, both p<0.001), whereas there was no independent association with LA volume index and pump strain. In the categorical analysis, the abnormal CAVI (≥9.0) carried the significant risk of impaired reservoir (<31.4%) and conduit (<12.4%) strain (adjusted odds ratio = 2.63 and 3.71 vs. normal CAVI, both p<0.01) in a fully-adjusted model including laboratory and echocardiographic parameters.

Figure 1

Conclusion

Arterial stiffness was independently associated with LA reservoir and conduit function, even in the absence of overt cardiovascular disease. This association may explain the higher incidence of atrial fibrillation in individuals with increased arterial stiffness.

P5293Effect of metabolically health obesity on carotid intima-media thickness in general population: a community-based cohort study

Introduction

Obesity is a common and independent risk factor for all-cause mortality. More specifically, obesity is a major component of atherosclerosis in association with metabolic disorders including metabolic syndrome (MetS), resulting in various cardiovascular diseases (CVD). Alternatively, obese subjects without MetS are prevalent, also referred to as metabolically healthy obesity (MHO). However, most preceding studies regarding MHO have been limited by small cohorts. Therefore, the effect of MHO on atherosclerosis in the general population remains unclear.

Purpose

In this study, we sought to clarify the effect of MHO on carotid intima-media thickness (IMT) as a marker of early stage atherosclerosis using a community-based cohort in general population.

Methods

We examined subjects who underwent medical check-up at our University Hospital. We defined obesity as body mass index ≥25.0 kg/m2. Abdominal obesity, defined as waist circumstance at umbilical level ≥85 cm in men and ≥90 cm in women, was obligatory for the diagnosis of MetS. In addition to abdominal obesity, any two of the following three abnormalities should be observed for the diagnosis of MetS, [1] Dyslipidemia: triglyceride ≥150 mg/dL, HDL-C <40 mg/dL, or use of lipid lowering medication, [2] Hypertension: systolic blood pressure ≥130 mmHg, diastolic blood pressure ≥85 mmHg, or use of antihypertensive medication, and [3] Hyperglycemia: fasting plasma glucose ≥110 mg/dL or use of hypoglycemic medication. MHO was defined as obese subjects without MetS, whereas we defined metabolically unhealthy obesity (MUO) as obese subjects with MetS. We defined carotid plaque as IMT ≥1.1 mm.

Results

Among 1,241 subjects, 857 subjects (69%) were categorized in the normal body weight group, whereas 275 subjects (22%) were categorized as MHO, and 109 subjects (9%) were categorized as MUO. Compared to non-obese subjects, prevalence of classical cardiovascular risk factors including hypertension, diabetes mellitus, and dyslipidemia increased in subjects with MHO, and further increased in those with MUO. IMT was higher in obese subjects compared to those without obesity. Similarly, the prevalence of carotid plaque formation was also higher in obese subjects. Multivariable logistic regression analysis demonstrated that age ≥60 years, male sex, hypertension, diabetes mellitus, MHO subjects (Odds ratio [OR]; 1.6, p=0.005), and MUO subjects (OR 1.7, p=0.04) were independently associated with carotid plaque formation. There was no statistical difference in the risk of carotid plaque formation between subjects with MHO and MUO.

IMT and Carotid Plaque

Conclusions

IMT and the prevalence of carotid plaque are higher in both subjects with MHO and MUO compared to non-obese subjects in the general population. We need to take obesity regardless of the presence of MetS into consideration as high-risk subjects for subsequent CVD.

P4389Effect of cigarette smoking on carotid artery atherosclerosis: a community-based cohort study

Background

Cigarette smoking is closely associated with the development of cardiovascular diseases (CVD), and the European Society of Cardiology/European Atherosclerosis Society (ESC/EAS) guidelines recommend smoking bans.On the other hand, the relationship between cigarette smoking and subclinical atherosclerosis has not been fully studied. Carotid intima-media thickness (cIMT) is commonly used as a subclinical atherosclerosis marker, and a carotid plaque feature is also known to be an important predictor of cardiovascular diseases.

Purpose

We sought to clarify the association between cigarette smoking and subclinical atherosclerosis by evaluating carotid plaque including cIMT and carotid plaque features in general population.

Methods and results

Among 1,209 participants with no prior coronary artery disease who received a medical check-up with cardiovascular examination at our institution, 450 participants (37.2%) were smokers (including both past and current smokers). We defined carotid plaque as cIMT ≥1.1 mm and high-risk plaque as carotid plaque with hypoechoic dominant and/or plaque ulceration. The value of cIMT and the rate of carotid plaque were not different between smokers and never smokers (Figure A & B). However, the rate of carotid high-risk plaque was significantly higher in participants with smokers than those with never smokers (29.7%, vs 23.5%, p=0.011) (Figure C). Even after adjustment with covariates including age, gender and traditional cardiovascular risk factors, cigarette smoking was independently associated with high-risk plaque formation (odds ratio 1.384, 95% CI 1.020–1.877; p=0.037). According to the subgroup analysis classified by age, cigarette smoking was associated with not only the development of high-risk plaque but also the increased value of cIMT in the subgroup over 60 years old, whereas only the rate of high-risk plaque was higher in smokers than never smokers in the subgroup under 60 years old.

Carotid plaque and smoking

Conclusion

The development of high-risk carotid artery plaque may precede thickening of cIMT in cigarette smokers, suggesting that the novel insight for the pathological mechanism underlying cardiovascular events and cigarette smoking.

Adhesion of Epoxy Resin with Hexagonal Boron Nitride and Graphite

Adhesion interaction of epoxy resin with the basal surfaces of h-BN and graphite is investigated with the first-principles density functional theory calculations in conjunction with the dispersion correction. The h-BN/epoxy and graphite/epoxy interfaces play an important role in producing nanocomposite materials with excellent thermal dissipation properties. The epoxy resin structure is simulated by using four kinds of fragmentary models. Their structures are optimized on the h-BN and graphite surfaces after an annealing simulation. The distance between the epoxy fragment and the surface is about 3 Å. At the interface between h-BN and epoxy resin, no H-bonding formation is observed, though one could expect that the active functional groups of epoxy resin, such as hydroxyl (-OH) group, would be involved in a hydrogen-bonding interaction with nitrogen atoms of the h-BN surface. The adhesion energies for the two interfaces are calculated, showing that these two interfaces are characterized by almost the same strength of adhesion interaction. To obtain the adhesion force-separation curve for the two interfaces, the potential energy surface associated with the detachment of the epoxy fragment from the surface is calculated with the help of the nudged elastic band method and then the adhesion force is obtained by using either the Morse-potential approximation or the Hellmann-Feynman force calculation. The results from both methods agree with each other. The maximum adhesion force for the h-BN/epoxy interface is as high as that for the graphite/epoxy interface. To better understand this result, a force-decomposition analysis is carried out, and it has been disclosed that the adhesion forces working at both interfaces mainly come from the dispersion force. The trend of increase in the C 6 parameters used for the dispersion correction for the atoms included in the h-BN or graphite surface is in the order: N < C < B, which reasonably explains why the strengths of the dispersion forces operating at the two interfaces are similar. Also, the electron localization function analysis can explain why the h-BN surface cannot form an H bond with the hydroxyl group in epoxy resin.

Long-term follow-up of collateral pathways established after lymphadenectomy in rats

A collateral pathway established after lymphadenectomy could play an important role in long-term lymphedema treatment. The present study investigated alterations of lymph dynamics 1 year after lymphadenectomy using indocyanine green fluorescent lymphography to determine if a collateral pathway may be used for long-term lymphedema treatment. Wistar rats were anaesthetized and lymph nodes were excised at the inguinal and popliteal fossae. The treated hind limb was evaluated by fluorescent lymphography between 10 weeks and 6 months and between 6 months and 1 year postoperatively. Fluorescent lymphography demonstrated a lymphatic pathway to the ipsilateral axillary fossa in all rats 1 year after lymphadenectomy. Some capillary branches in the paths leading to the ipsilateral axillary fossa were dilated and tortuous. In addition, areas in which a fluorescent signal was not visible were increased in the thigh. In conclusion, the collateral pathway did not appear to be only for temporary use to compensate for drainage from the edematous limb but appears more stable as a component of a compensating lymphatic system. These new dilated vessels, although functional at this point, may still be susceptible to disturbance by further alteration to the lymph vessels.

Nanostructured titanium phosphates prepared via hydrothermal reaction and their electrochemical Li- and Na-ion intercalation properties

A series of titanium phosphates with various morphologies are fabricated via a simple hydrothermal reaction of TiO₂ in H₃PO₄ aq.

Sonographic Staging of Cancer of the Mobile Tongue

In order to determine the value of sonography (US), in staging cancer of the mobile tongue, 57 patients were studied prospectively. Real-time sector scanners (5 and 7.5 MHz) were used with a submental approach. The findings by US were compared with those obtained by inspection and palpation and in 13 operated patients with the surgical results. US failed to visualize the tumor in 3 of the 57 patients (5%); in 30 patients (53%), the tumor was considered to be of nearly the same size by US and by palpation, but in 17 cases (30%), to be larger by US than by palpation, and in the remaining 7 cases (12%), to be smaller by US. Extension across the midline (8/8), and depth of tumor penetration, or extension to adjacent structures (5/5) were more correctly evaluated by US. We conclude that US is useful for staging work-up of tumors of the mobile tongue.

Angiomyolipoma of the Liver

Angiomyolipoma, a rare benign liver tumor, was observed in a 50-year-old woman examined with US, CT, MR imaging and angiography. Dynamic studies using CT and MR imaging were valuable in differentiating the disease from hepatocellular carcinoma with fat deposits.

Detection of Viable Tumor Cells in Hepatocellular Carcinoma following Transcatheter Arterial Chemoembolization with Iodized Oil

To evaluate the effect of transcatheter arterial chemoembolization (TACE) with iodized oil for hepatocellular carcinoma (HCC), dynamic turbo-fast low angle shot (turbo-FLASH) (TR/TE/flip angle/TI, 8.5/4.6/10/200) MR imaging with gadopentetate dimeglumine was performed in 10 patients with HCC after TACE with iodized oil and before partial hepatectomy. Immediately after 0.05 mmol/kg b.w. of gadopentetate dimeglumine was administered intravenously, 10 images were obtained in the first 20 s (early phase). Then, one image every 30 s from 1 to 3 min (late phase), and images at 5 min and 7 min (delayed phase) were obtained serially. In the early phase, HCC showed no enhancement in 5 patients, partial hyperintense enhancement in 4, and total hyperintense enhancement in one. Viable regions of the tumor, evaluated at histopathology, showed hyperintense enhancement relative to the surrounding liver parenchyma in the early phase, while necrotic regions showed no enhancement. Both viable and necrotic regions showed lower signal intensities than the surrounding liver parenchyma in both late and delayed phases. By using dynamic turbo-FLASH MR imaging, we were able to accurately evaluate the effect of TACE with iodized oil for HCC in 8 of the 10 patients. In 2 patients, in whom small viable cells were seen in the HCC, viable regions could not be detected with our technique. It is concluded that turbo-FLASH dynamic MR imaging was useful for evaluating the effect of TACE for HCC.

Computed Tomography following Endoscopic Sclerotherapy of Esophageal Varices

Computed tomography of the chest following endoscopic injection sclerotherapy for esophageal varices was performed in 17 procedures in 13 patients. CT scans were obtained before and within 48 hours after the procedure. CT findings included: esophageal wall thickening; a low-attenuating lesion within the wall of the esophagus with varying appearances, either laminated, localized, or inhomogeneous; a mediastinal lesion; pleural effusion; and various types of pulmonary changes such as atelectasis, pleural-based lesions, dilatation of peripheral pulmonary vessels, and nodular lesions. However, on follow-up CT they had regressed or disappeared. The changes in the mediastinum and pleural space might be caused by direct extension of inflammation from the esophagus, but those in the lungs, especially dilatation of peripheral vessels, may be caused by the sclerosing agent passing to the pulmonary vessels.

The method used to culture host cells (Sf9 cells) can affect the qualities of baculovirus budding particles expressing recombinant proteins

Budded virus (BV) particles of baculovirus (Autographa californica nucleopolyhedrovirus, AcNPV) are harvested from the supernatant of liquid culture of Sf9 host cells by ultracentrifugation. Using polyacrylamide gel electrophoresis, Western blot and transmission electron microscopy (TEM) of BV samples fractionated closely by sucrose density gradient centrifugation, we observed that BVs exhibited different qualities depending on whether they had been harvested from the supernatant from a standing (static), shaking (suspension), or standing/shaking (pre-/post-infection) culture of Sf9 cells. The amount of BV protein apparently increased in the order of standing, standing/shaking, and shaking procedure, and the yield of intact particles showed an opposite trend. TEM observation clearly showed that appropriate fractions of the standing and standing/shaking cultures contained more intact BV particles than those from the shaking culture. These results suggest that the qualities of recombinant BV particles may be related to the culture conditions of the host cells.

P450 oxidoreductase deficiency with maternal virilization during pregnancy

PURPOSE

The authors report on a rare case of maternal virilization during pregnancy caused by autosomal recessive P450 oxidore- ductase (POR) deficiency.

MATERIALS AND METHODS

A 24-year-old primigravida developed a deepening voice and hirsutism in the second trimester. Prenatal ultrasonography failed to detect any fetal abnormality and fetal growth was normal. POR deficiency was suspected, but the mother declined fetal genetic testing. A female neonate was delivered by cesarean section at 41 weeks' gestation.

RESULTS

The neonate had skeletal abnormalities. Mutational analysis of the POR gene demonstrated homozygosity for c.1370 G>A and p.R457H in the patient and heterozygosity in her parents. POR deficiency was confirmed in the neonate.

CONCLUSION

POR deficiency should be suspected in cases of maternal virilization. Maternal urinary estriol, fetal magnetic resonance imaging, and parental genetic testing should be performed. Parental consent for fetal genetic testing should be sought to ensure prompt diagnosis and early treatment.

Superparamagnetic iron oxide-enhanced MRI at 3 T for accurate axillary staging in breast cancer

BACKGROUND

The aim of this study was to evaluate whether MRI at 3 T with superparamagnetic iron oxide (SPIO) enhancement is an accurate and useful method for detecting metastases in sentinel nodes identified by CT-lymphography (CT-LG) in patients with breast cancer. The results were compared with those obtained using CT-LG alone and diagnosing metastasis according to size criteria.

METHODS

Patients with clinically node-negative breast cancer were included. Sentinel nodes identified by CT-LG were evaluated prospectively using SPIO-enhanced MRI at 3 T. Sentinel node size was measured on CT-LG, and a node larger than 5 mm in short-axis diameter was considered metastatic. Sentinel nodes localized by CT-LG were removed, and imaging results and histopathological findings were compared.

RESULTS

Sentinel nodes were identified successfully by CT-LG in 69 (99 per cent) of 70 patients. All 19 patients with a finding of metastasis in sentinel nodes at pathology were also shown to have metastases on MRI. Forty-eight of 50 patients with non-metastatic sentinel nodes diagnosed at pathology were classified as having non-metastatic nodes on MRI. On a patient-by-patient basis, the sensitivity, specificity and accuracy of MRI for the diagnosis of sentinel node metastases were 100, 96 and 97 per cent; respective values for CT-LG were 79, 56 and 62 per cent. The specificity and accuracy of MRI were superior to those of CT-LG (P < 0·001 and P = 0·002 respectively).

CONCLUSION

SPIO-enhanced MRI at 3 T is useful for accurate diagnosis of metastatic sentinel nodes, indicating that sentinel node biopsy may be avoided in patients with breast cancer who have non-metastatic sentinel nodes on imaging.

Two γ-ray bursts from dusty regions with little molecular gas

Long-duration γ-ray bursts are associated with the explosions of massive stars and are accordingly expected to reside in star-forming regions with molecular gas (the fuel for star formation). Previous searches for carbon monoxide (CO), a tracer of molecular gas, in burst host galaxies did not detect any emission. Molecules have been detected as absorption in the spectra of γ-ray burst afterglows, and the molecular gas is similar to the translucent or diffuse molecular clouds of the Milky Way. Absorption lines probe the interstellar medium only along the line of sight, so it is not clear whether the molecular gas represents the general properties of the regions where the bursts occur. Here we report spatially resolved observations of CO line emission and millimetre-wavelength continuum emission in two galaxies hosting γ-ray bursts. The bursts happened in regions rich in dust, but not particularly rich in molecular gas. The ratio of molecular gas to dust (<9-14) is significantly lower than in star-forming regions of the Milky Way and nearby star-forming galaxies, suggesting that much of the dense gas where stars form has been dissipated by other massive stars.

Interferon γ and plasminogen activator inhibitor 1 regulate adhesion formation after partial hepatectomy

BACKGROUND

The pathophysiology of intra-abdominal adhesions has not been studied extensively. The aim of this study was to elucidate the molecular mechanisms underlying adhesion formation in a murine model and in patients undergoing hepatectomy.

METHODS

Partial hepatectomy was performed using bipolar forceps in mice. Wild-type mice, antibodies to CD4 and interferon (IFN) γ, IFN-γ, natural killer T (NKT) cells and plasminogen activator inhibitor (PAI) 1 knockout (KO) mice were used. Recombinant hepatocyte growth factor (HGF) was tested for its ability to prevent adhesions. Liver specimens were obtained during surgery from patients undergoing hepatectomy. Adhesion formation was evaluated using a scoring system that ranged from 0 (no adhesions) to 5 (severe adhesions). Levels of IFN-γ and PAI-1 mRNA, and protein concentration of PAI-I were measured, and fluorescence immunostaining was performed.

RESULTS

Adhesion formation depended on IFN-γ produced by NKT cells, and NKT KO mice developed few adhesions (mean(s.d.) 1·7(0·3) versus 4·6(0·4) in wild-type mice; P = 0·037). In wild-type mice, the level of PAI-1 mRNA increased after hepatectomy, followed by a decrease in the tissue plasminogen activator (tPA) mRNA level. Adhesion formation was inhibited completely in PAI-1 KO mice (0(0) versus 4·1(0·8) in wild-type mice; P = 0·002). HGF inhibited formation of abdominal adhesions after hepatectomy by reducing IFN-γ and PAI-1 levels, and increasing tPA levels compared with those in mice treated with phosphate-buffered saline (P < 0·001, P = 0·002 and P = 0·035 respectively). In human liver specimens, NKT cells accumulated in the liver after hepatectomy, and PAI-1 expression was increased 5·25-fold (P = 0·030).

CONCLUSION

IFN-γ is a key molecule for abdominal adhesion formation after hepatectomy, acting via the reciprocal balance of PAI-1 and tPA. This molecular mechanism may also regulate adhesion formation in patients following hepatectomy. HGF inhibited formation of adhesions by regulating IFN-γ and PAI-1, suggesting that it may be an important target for prevention of adhesions after hepatectomy. SURGICAL RELEVANCE: Postoperative intra-abdominal adhesions can be asymptomatic or cause significant morbidity and mortality. Adhesion formation after hepatectomy has not been studied extensively. In the present study, the molecular mechanisms underlying intra-abdominal adhesions after hepatectomy were investigated in a murine model and in patients. Interferon (IFN) γ produced by natural killer T cells is a key molecule for adhesion formation after hepatectomy in mice, acting via the reciprocal balance between plasminogen activator inhibitor (PAI) 1 and tissue plasminogen activator, the pivotal factors in fibrinolytic activity. This mechanism was also involved in the regulation of adhesions in human tissue samples. Hepatocyte growth factor (HGF) strongly inhibited adhesion formation by regulating IFN-γ and PAI-1. These results indicate that IFN-γ and PAI-1 are possible therapeutic targets, and HGF could prevent postoperative adhesion formation after hepatectomy.