The Feasibility of Fast, Four-Dimensional Computed Tomography-Based O-Ring Linac Plans for Stereotactic Body Radiotherapy in Patients with Poor Performance Status

PURPOSE/OBJECTIVE(S)

As patients with poor performance status cannot endure long treatment times, it can lead to unplanned and prolonged radiation treatment or discontinuation of treatment. Moreover, prolonged radiation treatment appears to negatively affect survival for patients. We aimed to verify the feasibility of fast 4DCT-based O-ring linear accelerator (LINAC) treatment in lung 4D stereotactic body radiotherapy (SBRT).

MATERIALS/METHODS

This study included data of 38 patients who received lung 4D-SBRT. Gating20-70% plans were based on 4DCT data obtained at phase values ranging from 20-70% using a C-arm LINAC. Non-GatingFB plans were retrospectively established based on 4DCT data obtained at phase values of 0-90% using an O-ring LINAC. The prescribed dose of 4,800 cGy was delivered to PTV in four fractions. The conformity index (CI), homogeneity index (HI), and gradient measurement (GM) of the PTV were analyzed to compare dosimetric data between Gating20-70% and Non-GatingFB plans. Organs at risks (OARs) were analyzed in accordance with the RTOG 0915 protocol. Treatment delivery time and total monitor units (MU) were analyzed to compare the efficiency of treatment delivery. Statistical comparisons were performed using the Wilcoxon signed-rank test (p<0.05).

RESULTS

For the PTV, there was no significant difference in the CI or HI between Gating20-70% and Non-GatingFB plans (CI: 1.337±0.137, 1.335±0.174, HI: 0.939±0.015, 0.939±0.016, all at p>0.05). However, there was a significant difference in GM between Gating20-70% and Non-GatingFB plan (1.528±0.206 cm, 1.381±0.222 cm, p<0.001). For OARs, all plans met the criteria for dose constraint. There was a significant difference between Gating20-70% and Non-GatingFB plans except in the spinal cord. In particular, D1000cc and D1500cc values for the ipsilateral lung for Gating20-70% plans were 31.6% and 59.9% lower than those for Non-GatingFB plans (D1000cc: 50.780±132.061 cGy, 34.755±102.480 cGy, p<0.001, D1500cc: 6.641±14.598 cGy, 2.666±7.926 cGy, p<0.001). Treatment delivery time was 92% longer for Gating20-70% plans than for Non-GatingFB plans (5.0±0.4 min, 9.6±3.3 min, p = 0.043). The total MU value for Gating20-70% plans was 9.6% higher than that for Non-GatingFB plans (3665.8±230.7, 4016±236.9, p = 0.039).

CONCLUSION

When compared to OARs both plans were acceptable per RTOG-0915 protocol, but significant differences were between Non-GatingFB and Gating20-70% plans. However, treatment delivery time of Non-GatingFB plans decreased by 47.9% than Gating20-70% plans. We verified the feasibility of fast 4DCT-based O-ring LINAC treatment for patients who cannot endure long treatment times due to poor performance status in lung 4D-SBRT. In further study, we will analyze dosimetric differences and treatment delivery efficiency considering tumor motion according to tumor location.

Ribosomal protein S3 associates with the TFIIH complex and positively regulates nucleotide excision repair

In mammalian cells, the bulky DNA adducts caused by ultraviolet radiation are mainly repaired via the nucleotide excision repair (NER) pathway; some defects in this pathway lead to a genetic disorder known as xeroderma pigmentosum (XP). Ribosomal protein S3 (rpS3), a constituent of the 40S ribosomal subunit, is a multi-functional protein with various extra-ribosomal functions, including a role in the cellular stress response and DNA repair-related activities. We report that rpS3 associates with transcription factor IIH (TFIIH) via an interaction with the xeroderma pigmentosum complementation group D (XPD) protein and complements its function in the NER pathway. For optimal repair of UV-induced duplex DNA lesions, the strong helicase activity of the TFIIH complex is required for unwinding damaged DNA around the lesion. Here, we show that XP-D cells overexpressing rpS3 showed markedly increased resistance to UV radiation through XPD and rpS3 interaction. Additionally, the knockdown of rpS3 caused reduced NER efficiency in HeLa cells and the overexpression of rpS3 partially restored helicase activity of the TFIIH complex of XP-D cells in vitro. We also present data suggesting that rpS3 is involved in post-excision processing in NER, assisting TFIIH in expediting the repair process by increasing its turnover rate when DNA is damaged. We propose that rpS3 is an accessory protein of the NER pathway and its recruitment to the repair machinery augments repair efficiency upon UV damage by enhancing XPD helicase function and increasing its turnover rate.

Low free T3 to free T4 ratio was associated with low muscle mass and impaired physical performance in community-dwelling aged population

In aged population, the association of thyroid hormones on physical performance, especially within their normal range, has yet to be elucidated. In this study, individuals with low serum free T3/free T4 were likely to have low muscle mass and impaired physical performance.

PURPOSE

We aimed to evaluate the associations of muscle mass, strength, and physical performance with thyroid hormone in an aged euthyroid population from a community-based cohort.

METHODS

We examined 918 men aged over 60 years and 1215 postmenopausal women from the Ansung cohort study. Appendicular skeletal muscle mass divided by square of height (ASM/ht²) was used as the muscle mass index. Hand grip strength was measured using a hydraulic dynamometer. Physical performance was assessed using the short physical performance battery (SPPB).

RESULTS

Participants with higher tertiles of free T3 and free T3/free T4 were younger and had higher ASM/ht², stronger hand grip strength, and higher SPPB scores than those in the lower tertiles. In adjusted models, men within higher tertiles of free T3 had higher ASM/ht² compared with those within lower tertiles (p = 0.033), whereas subjects with higher tertiles of free T4 had lower ASM/ht² compared with those within lower tertiles (p = 0.043). Subjects within higher tertiles of free T3/free T4 had higher ASM/ht² (p < 0.001) and better physical performance (p = 0.048) than those within lower tertiles after adjustments. However, free T3, free T4, or free T3/free T4 was not related to hand grip strength after adjustment for covariates.

CONCLUSION

Our results thus indicate that in an aged euthyroid population, low serum free T3/free T4 was a better index for low muscle mass and impaired physical performance than serum free T3 or free T4 alone.

P3617Systolic blood pressure, glycemic control and clinical outcome in diabetic patients with acute myocardial infarction

Background

Recent blood pressure guidelines recommend intensive blood pressure control in diabetic patients with cardiovascular disease.

Purpose

We sought to investigate combined impact of intensive blood glucose lowering and blood pressure control on clinical outcome in diabetic patients with acute myocardial infarction (AMI) has not been fully investigated yet.

Method

Korean Acute Myocardial Infarction Registry (KAMIR) – National Institute of Health (NIH) database included 12,179 patients (9,046 men; mean age = 63.6±12.6 year-old) who were discharged alive. Among them, 3,430 (28.2%) had a diabetes mellitus (DM). MACCEs were defined as a composition of all cause death, non-fatal MI, repeat revascularizations including repeated percutaneous coronary intervention and coronary bypass grafting, cerebrovascular accident and rehospitalizations at 1 year. This research was supported by a fund by Research of Korea Centers for Disease Control and Prevention.

Result

We determined cut-off value of discharge systolic blood pressure (SBP) to predict 1-year MACCE in DM and non-DM patients. Discharge SBP of less than 130mmHg was associated with a lower MACCE at 1 year compared to SBP level of 130mmHg or greater (10.8% versus 15.4%; log-rank p=0.001) in DM patients, whereas discharge SBP cut-off level was 140mmHg to discriminate 1-year MACCE in non-DM patients (6.4% versus 8.5%, log-rank p=0.045). In DM patients, there were no significant difference in 1-year MACCEs between patients with HbA1c less than 7% versus 7% or greater (12.0% versus 10.7%; log-rank p=0.325). DM patients were categorized into 4 groups; discharge SBP <130mmHg and HbA1c <7% (Group 1); discharge SBP <130mmHg and HbA1c ≥7% (Group 2); discharge SBP ≥130mmHg and HbA1c <7% (Group 3); discharge SBP ≥130mmHg and HbA1c ≥7% (Group 4). Intensive BP control was associated lower 1-year MACCEs in patients with good glycemic control (Group 1 & 3; 10.7% versus 16.7%; log-rank p=0.009). However, in patients with poor glycemic control, intensive BP control did not improve 1-year MACCEs (Group 2 & 4; 10.6% versus 11.1%; log-rank p=0.761).

Conclusion

Strict BP control is more important than glycemic control to improve short-term clinical outcome in DM patients with AMI. However, in patients with poor glycemic control, strict BP control did not improve clinical outcome.

P3583Optimal procedural strategy to improve clinical outcome in primary percutaneous coronary intervention

Background

Current guideline recommends potent antiplatelet agents and transradial intervention. However, it is uncertain whether routine use of IVUS, thrombus aspiration and glycoprotein IIB-IIIA inhibitor is beneficial for improving clinical outcome in patients with ST-segment elevation myocardial infarction (STEMI).

Purpose

The aim of this study was to investigate optimal procedural strategy to improve clinical outcome.

Methods

A total of 6,046 patients who underwent primary percutaneous coronary intervention (PCI) for STEMI were analyzed from the Korean Acute Myocardial Infarction Registry (KAMIR) – National Institute of Health (NIH) database. MACCEs were defined as a composition of all cause death, non-fatal MI, repeat revascularizations including repeated percutaneous coronary intervention and coronary bypass grafting, cerebrovascular accident and rehospitalizations. This research was supported by a fund by Research of Korea Centers for Disease Control and Prevention.

Results

During the primary PCI, potent antiplatelet agents such as prasugrel and ticagrelor were used in 2342 (38.4%). PCI was performed through transradial approach in 1490 (25.2%). Thrombus aspiration and intravascular ultrasound (IVUS) examination was done in 2204 (36.1%) and 1079 (18.1%), respectively. Glycoprotein IIB-IIIA inhibitor was administered in 1295 (21.7%). Among them, potent antiplatelet agents, transradial intervention, IVUS, and thrombus aspiration significantly reduced MACCEs at 1 year. Glycoprotein IIB-IIIA inhibitor was not effective to improved clinical outcome. In Cox-proportional hazards model, potent antiplatelet agents (hazard ratio 0.82, 95% confidence interval 0.67–0.99; p=0.045) and transradial intervention (hazard ratio 0.61, 95% confidence interval 0.47–0.78; p<0.001) was an independent predictor of MACCEs after adjusting for confounding variables. Combined use of potent antiplatelet agents and transradial intervention (hazard ratio 0.54; 95% confidence interval 0.37–0.80; p=0.002) substantially reduced MACCEs at 1 year.

Conclusion

Among evidence based procedures during the primary PCI, combined use of potent antiplatelet agents and transradial intervention was optimal procedural strategy to improve clinical outcome.

Anion gap and base deficit are predictors of mortality in acute pesticide poisoning

BACKGROUND:

Acute pesticide poisoning has long been a serious problem as a method of suicide worldwide. This poisoning is a highly fatal condition that requires a rapid and precise diagnosis for adequate treatment. However, various studies on mortality predictor factors have been insufficient for whole pesticide treatments. We hypothesized that the initial plasma anion gap (AG) and base deficit (BD) are reliable prognostic factors.

METHODS:

A retrospective study analyzed 561 patients with a diagnosis of acute pesticide poisoning between January 1, 2014 and June 30, 2017. The initial AG and BD values were divided into quartiles according to the number of patients. Survival at 30 days from admission was estimated using the Kaplan-Meier survival analysis. Receiver-operator characteristic (ROC) curves were drawn, and the areas under the curve for AG and BD for mortality were calculated.

RESULTS:

Fifty-eight (10.3%) of 561 patients died within 30 days. The highest AG quartile (>22 mEq/L) was associated with an increased risk of 30-day hospital mortality. Compared to patients with an AG less than 14.7 mEq/L, these patients had a 4.18-fold higher risk of 30-day hospital mortality and the highest BD quartile (>7.9 mEq/L) was associated with an increased risk of 30-day hospital mortality. Compared to patients with a BD less than 1.4 mEq/L, these patients had 2.23-fold higher risk of 30-day hospital mortality. The areas under the ROC for AG and BD curve were 0.699 and 0.744, respectively.

CONCLUSIONS:

Initial high AG and BD values could predict mortality and require precise intensive care.

Results from the Survey of Antibiotic Resistance (SOAR) 2012-14 in Thailand, India, South Korea and Singapore

OBJECTIVES

To provide susceptibility data for community-acquired respiratory tract isolates of Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Moraxella catarrhalis collected in 2012-14 from four Asian countries.

METHODS

MICs were determined using Etest(®) for all antibiotics except erythromycin, which was evaluated by disc diffusion. Susceptibility was assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. For macrolide/clindamycin interpretation, breakpoints were adjusted for incubation in CO2 where available.

RESULTS

Susceptibility of S. pneumoniae was generally lower in South Korea than in other countries. Penicillin susceptibility assessed using CLSI oral or EUCAST breakpoints ranged from 21.2% in South Korea to 63.8% in Singapore. In contrast, susceptibility using CLSI intravenous breakpoints was much higher, at 79% in South Korea and ∼95% or higher elsewhere. Macrolide susceptibility was ∼20% in South Korea and ∼50%-60% elsewhere. Among S. pyogenes isolates (India only), erythromycin susceptibility (∼20%) was lowest of the antibiotics tested. In H. influenzae antibiotic susceptibility was high except for ampicillin, where susceptibility ranged from 16.7% in South Korea to 91.1% in India. South Korea also had a high percentage (18.1%) of β-lactamase-negative ampicillin-resistant isolates. Amoxicillin/clavulanic acid susceptibility for each pathogen (PK/PD high dose) was between 93% and 100% in all countries except for H. influenzae in South Korea (62.5%).

CONCLUSIONS

Use of EUCAST versus CLSI breakpoints had profound differences for cefaclor, cefuroxime and ofloxacin, with EUCAST showing lower susceptibility. There was considerable variability in susceptibility among countries in the same region. Thus, continued surveillance is necessary to track future changes in antibiotic resistance.

Whole-breast US following mammography and breast MRI in newly diagnosed breast cancer patients: can it be more than just a guidance tool for biopsy?

AIM

To evaluate the role of ultrasound (US) following magnetic resonance imaging (MRI) and mammography in patients with newly diagnosed breast cancers by assessing the additional cancer detection rate of US.

MATERIAL AND METHODS

Two hundred and twenty-five women who had undergone 225 MRI examinations followed by US were included. An US-detected additional cancer was defined as a lesion detected using breast US that had not been detected by MRI, and which was shown to be malignant at histopathology. The rate of additional cancer detection, incidence of additional malignancies, positive predictive value (PPV), and false-positive (FP) rate were analysed. Factors associated with an increase in the additional cancer detection rate were analysed.

RESULTS

The additional cancer detection rate was 0% (0/225) for the ipsilateral breast and 0.9% (2/225) for the contralateral breast, and the PPVs were 0% (0/5) and 100% (2/2), respectively. The overall TP:FP ratio was 0.4 (2:5). The additional cancer detection rate was higher for cases with moderate and severe background parenchymal enhancement than cases with minimal and mild background parenchymal enhancement (p=0.003). The additional cancer detection rate for cases with moderate and severe background parenchymal enhancement was 5.7% (2/35) for the contralateral breast (p=0.003).

CONCLUSION

Preoperative breast US following MRI and mammography can help clinicians screen for contralateral cancers with an additional detection rate of 0.9%. Moreover, whole-breast US might be a useful contralateral screening modality in cases with moderate or marked parenchymal enhancement on breast MRI.

Myometrial relaxation of mice via expression of two pore domain acid sensitive K(+) (TASK-2) channels

Myometrial relaxation of mouse via expression of two-pore domain acid sensitive (TASK) channels was studied. In our previous report, we suggested that two-pore domain acid-sensing K⁺ channels (TASK-2) might be one of the candidates for the regulation of uterine circular smooth muscles in mice. In this study, we tried to show the mechanisms of relaxation via TASK-2 channels in marine myometrium. Isometric contraction measurements and patch clamp technique were used to verify TASK conductance in murine myometrium. Western blot and immunehistochemical study under confocal microscopy were used to investigate molecular identity of TASK channel. In this study, we showed that TEA and 4-AP insensitive non-inactivating outward K⁺ current (NIOK) may be responsible for the quiescence of murine pregnant longitudinal myometrium. The characteristics of NIOK coincided with two-pore domain acid-sensing K⁺ channels (TASK-2). NIOK in the presence of K⁺ channel blockers was inhibited further by TASK inhibitors such as quinidine, bupivacaine, lidocaine, and extracellular acidosis. Furthermore, oxytocin and estrogen inhibited NIOK in pregnant myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed stronger inhibition of NIOK by quinidine and increased immunohistochemical expression of TASK-2. Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretch-activated channels in the longitudinal myometrium of mouse. Activation of TASK-2 channels seems to play an essential role for relaxing uterus during pregnancy and it might be one of the alternatives for preventing preterm delivery.

Regulation of myometrial contraction by ATP-sensitive potassium (KATP) channel via activation of SUR2B and Kir 6.2 in mouse

ATP-sensitive potassium (K_ATP) channels are well characterized in cardiac, pancreatic and many other muscle cells. In the present study, functional expression of the K_ATP channel was examined in non-pregnant murine longitudinal myometrium. Isometric contraction measurements and Western blot were used. K_ATP channel openers (KCOs), such as pinacidil, cromakalim, diazoxide and nicorandil, inhibited spontaneous myometrial contractions in a reversible and glibenclamide-sensitive manner. KCOs inhibited oxytocin (OXT)- and prostaglandin F_2α (PGF_2α)-induced phasic contractions in a glibenclamide-sensitive manner. SUR2B and Kir6.2 were detected by Western blot, whereas SUR1, SUR2A and Kir6.1 were not. These results show that pinacidl, cromakalim, diazoxide and nicorandil-sensitive K_ATP channels exist in murine myometrium, which are composed of SUR2B and Kir6.2. Based on the modulatory effects of the K_ATP channel on spontaneous contraction, OXT- and PGF_2α-induced contractions, K_ATP channels seem to play an essential role in murine myometrial motility via activation of SUR2B and Kir6.2.

High-normal free thyroxine levels are associated with low trabecular bone scores in euthyroid postmenopausal women

Trabecular bone scores (TBS) have recently been developed as a diagnostic tool to assess bone texture. We studied thyroid status and TBS in a population-based cohort and demonstrated that high-normal thyroxine levels are associated with low TBS in healthy euthyroid postmenopausal women.

INTRODUCTION

Increased thyroid hormone levels affect bone mineral density (BMD) and, if untreated, increase the risk of fracture. However, the relationship between thyroid function and bone microarchitecture has not yet been established. Trabecular bone scores (TBS) are gray-level textural measurements of dual energy X-ray absorptiometry (DXA) images. The TBS has been proposed as an indirect index of bone microarchitecture. The goal of this study was to characterize the relationship between thyroid function and TBS in euthyroid men and postmenopausal euthyroid women.

METHODS

A total of 1376 euthyroid subjects (648 postmenopausal women and 728 men) were recruited from a community-based cohort in Korea. Free thyroxine (fT4) levels, thyroid stimulating hormone (TSH) levels, BMD, and TBS were measured and compared.

RESULTS

There was no significant relationship between either fT4 or TSH levels and BMD in men and women. Multiple linear regression analysis showed that high-normal fT4 levels were negatively correlated with TBS (β = -0.111; P = 0.002, after adjusting for both age and body mass index [BMI]) in postmenopausal women. In men, however, there was no significant correlation between fT4 levels and TBS. TSH levels were not significantly associated with TBS in either men or women.

CONCLUSION

Higher fT4 levels within the normal reference range are associated with deterioration of trabecular microarchitecture in healthy euthyroid postmenopausal women.

Investigation of thermal and electrical stabilities of a GdBCO coil using grease as an insulation material for practical superconducting applications

This paper presents the effects of thermal grease on the electrical and thermal characteristics of GdBCO pancake coils, observed through charge-discharge, sudden discharge, over-current, and thermal quench testing. In charge-discharge and sudden discharge tests, a coil using thermal grease as an insulation material demonstrated faster charging/discharging rates compared to a coil without turn-to-turn insulation. In the case of over-current tests, the coil using thermal grease exhibited the highest electrical stability. Furthermore, thermal quench testing showed the coil employing thermal grease to possess superior thermal characteristics, with rapid cooling and low temperature rise. Overall, the use of thermal grease as an insulation material may be a potential solution to the problems observed with the existing insulation materials, possessing fast charging/discharging rates with superior thermal and electrical stabilities.

CD11a, CD11c, and CD18 gene polymorphisms and susceptibility to Behçet's disease in Koreans

Lesions of Behçet's disease (BD) show vascular infiltrates of immune cells expressing integrins. β2 integrins (CD11/CD18) play a major role in cell migration to the inflammatory lesion and also induce cytokine production. Thus, genetic polymorphisms of CD11/CD18 may be associated with the pathogenesis of BD. In this study, nine single nucleotide polymorphisms (SNPs) of the CD11a, CD11c, and CD18 were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and haplotype analysis in 305 BD patients and 266 healthy controls. The frequencies of genotype rs11574944 CC and haplotype rs11574944C-rs2230433G-rs8058823A in CD11a were significantly lower in BD patients. The frequencies of genotype rs2230429 CC, rs2929 GG, and haplotype rs2230429C-rs2929G in CD11c were higher in BD patients. The frequencies of genotype rs235326CC and haplotype rs2070946A-rs235326C-rs760456G-rs684G in CD18 were significantly higher in the BD patients than in the controls. Other SNPs in CD11a, CD11c, and CD18 gene were not significantly different. Therefore, the major genotype and haplotype of CD11a/CD18 may play a role in decreasing the susceptibility of BD, whereas the major genotype and haplotype of CD11c/CD18 may play a role in increasing the susceptibility of BD.

Role of the superior turbinate when performing endoscopic endonasal transsphenoidal approach

BACKGROUND

This study examined the relationship between the superior turbinate and natural ostium of the sphenoid sinus, as seen during the endoscopic endonasal transsphenoidal approach (EETSA) for sellar lesions and described how to enter the sphenoethmoid cell safely for complete exposure of the sellar floor, including adjacent vital structures such as the prominence of the optic nerve and carotid artery.

MATERIALS AND METHODS

This study retrospectively reviewed the medical records and operative findings of 154 patients, who underwent EETSA between February 2009 and February 2011. We evaluated the location of the natural ostium of the sphenoid sinus relative to the superior turbinate and revealed the clinical significance of the superior turbinate as a surgical guide to enter into the sphenoethmoid cell during EETSA.

RESULTS

The natural ostium of the sphenoid sinus was located medially to the posteroinferior end of the superior turbinate in 151 (98%) patients. In 1 patient, the natural ostia of the sphenoid sinus were located lateral to the superior turbinate bilaterally. Sphenoethmoid cell was encountered in 53 (34%) patients. We could easily enter the sphenoethmoid cell at the point where the superior turbinate was attached to the anterior wall of the sphenoid sinus.

CONCLUSIONS

The superior turbinate is a good surgical landmark for identifying the natural ostium of the sphenoid sinus and as a guide for the surgical entrance to the sphenoethmoid cell extending to the sphenoid sinus during EETSA.

Experimental validation of a novel compact focusing scheme for future energy-frontier linear lepton colliders

A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.

Phylogenetic relationships of chrysanthemums in Korea based on novel SSR markers

Chrysanthemums are well known for their esthetic and medicinal values. Characterization of chrysanthemums is vital for their conservation and management as well as for understanding their genetic relationships. We found 12 simple sequence repeat markers (SSRs) of 100 designed primers to be polymorphic. These novel SSR markers were used to evaluate 95 accessions of chrysanthemums (3 indigenous and 92 cultivated accessions). Two hundred alleles were identified, with an average of 16.7 alleles per locus. KNUCRY-77 gave the highest polymorphic information content value (0.879), while KNUCRY-10 gave the lowest (0.218). Similar patterns of grouping were observed with a distance-based dendrogram developed using PowerMarker and model-based clustering with Structure. Three clusters with some admixtures were identified by model-based clustering. These newly developed SSR markers will be useful for further studies of chrysanthemums, such as taxonomy and marker-assisted selection breeding.

Mechanism of Relaxation Via TASK-2 Channels in Uterine Circular Muscle of Mouse

Plasma pH can be altered during pregnancy and at labor. Membrane excitability of smooth muscle including uterine muscle is suppressed by the activation of K⁺ channels. Because contractility of uterine muscle is regulated by extracellular pH and humoral factors, K⁺ conductance could be connected to factors regulating uterine contractility during pregnancy. Here, we showed that TASK-2 inhibitors such as quinidine, lidocaine, and extracellular acidosis produced contraction in uterine circular muscle of mouse. Furthermore, contractility was significantly increased in pregnant uterine circular muscle than that of non-pregnant muscle. These patterns were not changed even in the presence of tetraetylammonium (TEA) and 4-aminopyridine (4-AP). Finally, TASK-2 inhibitors induced strong myometrial contraction even in the presence of L-methionine, a known inhibitor of stretchactivated channels in myometrium. When compared to non-pregnant myometrium, pregnant myometrium showed increased immunohistochemical expression of TASK-2. Therefore, TASK-2, seems to play a key role during regulation of myometrial contractility in the pregnancy and provides new insight into preventing preterm delivery.