Difference in Radiosensitivity Depending on the Presence and Absence of EGFR Mutations: Clinical and In Vitro Analyses

PURPOSE/OBJECTIVE(S)

For stage IV non-small cell lung cancer (NSCLC), the treatment drug is selected based on the gene mutation status. However, the dose or field of radiation therapy is not change based on the genetic status. We evaluated both clinical and in vitro data, showing that the presence or absence of epidermal growth factor receptor (EGFR) mutations affects radiosensitivity in patients with brain metastases (BM) from NSCLC.

MATERIALS/METHODS

Patients with BM from NSCLC who received whole brain radiotherapy (WBRT) were enrolled in this study. Patient characteristics are shown in the Table. EGFR mutations were observed in 13 (31.0%) patients. The prescribed dose was 30 Gy in 10 fractions (85.7%). The A549, VMRC-LCD, NCI-H1975, and HCC4006 cell lines were used for the in vitro study. EGFR mutation was negative in A549 and VMRC-LCD and positive in NCI-H1975 (exon21) and HCC4006 (exon19). After irradiation of these cell lines with 0, 2, 4, and 8 Gy, a colony formation assay was performed. DNA double-strand breaks (DSBs) were assessed 30 min and 24 h after 4 Gy irradiation using γH2AX.

RESULTS

The median follow-up period was 4 months (range, 1-35). Intracranial recurrence was observed in 14 (33.3%) patients during the follow-up period. Thirty-nine (92.9%) patients died during the follow-up period. Patients with EGFR mutation-positive tumors had significantly better intracranial control rates than those with EGFR mutation-negative tumors (p = 0.0213). A similar tendency was observed in the analysis conducted, except for the cases in which tyrosine kinase inhibitor (TKI) was administered after WBRT. In the EGFR mutation-positive group, no significant difference was observed between patients who received TKI after WBRT and those who did not (p = 0.527). In the colony formation assay, EGFR mutation-positive cell lines showed a significantly lower number of colonies formed after irradiation with 2 and 4 Gy than mutation-negative cell lines (p = 0.00018 and 0.0000291, respectively). EGFR mutation-positive cell lines had significantly more DNA-DSBs remaining 24 h after irradiation than mutation-negative cell lines (p = 0.0000000312).

CONCLUSION

Our data suggest that patients with EGFR mutation-positive NSCLC are more radiosensitive than those with negative EGFR mutations.

Effects of Radiation Doses on Clinical Recurrence in Patients with Biochemically Recurrent Prostate Cancer after Prostatectomy

PURPOSE/OBJECTIVE(S)

Salvage radiotherapy (SRT) to the prostate bed is the only curative treatment for patients with biochemical recurrence (BCR) after radical prostatectomy (RP). Although several systematic reviews indicated that a dose escalation in the range of 60-70 Gy improved biochemical control, the effects of radiation doses on clinical relapse after SRT remain unclear. Our aim was to investigate the relationship between radiation doses and clinical relapse-free survival (cRFS) after SRT.

MATERIALS/METHODS

We identified 295 eligible patients receiving SRT for biochemically recurrent prostate cancer after RP between 2005 and 2018 at 15 institutions. Sixteen patients (5%) received short-term (< 6 months) androgen deprivation therapy (ADT) following RP and/or concurrently with SRT. SRT was delivered to the prostate and seminal vesicle bed using photon beams at a median (range) dose of 66 Gy (61-85) in 1.8-3.0 Gy fractions. The primary outcome was cRFS. Clinical relapse was identified on radiological imaging and/or biopsy and included local recurrence, lymph node metastasis, and distant metastasis. In all analyses, doses were recalculated as an equivalent dose in 2-Gy fractions (EQD2) with α/β = 1.5 Gy. Clinical RFS between the EQD2 ≥ 66 Gy (n = 229) and EQD2 < 66 Gy (n = 66) groups were compared using the Log-rank test, followed by univariate and multivariate Cox regression analyses and a subgroup analysis.

RESULTS

The median follow-up duration was 73 months. Among patients with BCR (n = 119), 79 of 96 (82%) in the EQD2 ≥ 66 Gy group and 21 of 23 (91%) in the EQD2 < 66 Gy group received second salvage ADT (p = 0.36). Among all patients (n = 295), clinical relapse was identified in 22 (7%) patients after SRT. Six-year biochemical relapse-free survival (bRFS), cRFS, cancer-specific survival (CSS), and overall survival (OS) rates were 58%, 93%, 98%, and 94%, respectively. Six-year cRFS rates were 94% (95% confidence interval [CI], 90-97) in the EQD2 ≥ 66 Gy group and 87% (95% CI, 75-93) in the EQD2 < 66 Gy group (p = 0.020). The multivariate analysis revealed that EQD2 < 66 Gy, Gleason score ≥ 8, seminal vesicle involvement, and PSA at BCR ≥ 0.5 ng/ml correlated with clinical relapse (p = 0.0016, 0.014, 0.011, and 0.027, respectively). The subgroup analysis showed the consistent benefit of EQD2 ≥ 66 Gy in patients across most subgroups including PSA at BCR after RP, extracapsular extension, and age at SRT.

CONCLUSION

This large multi-institutional observational study demonstrated that a higher SRT dose (EQD2 ≥ 66 Gy) resulted in superior cRFS. The present result supports the dose recommendations in the 2023 National Comprehensive Cancer Network guidelines (64-72 Gy) even in terms of clinical relapse. Prospective trial is warranted to investigate an upper threshold for optimal SRT dose.

Deep-Inspiration Breath-Hold Stereotactic Body Radiation Therapy by Combining Spirometer-Guided Breath-Hold and a Real-Time Tumor Tracking System: A Novel Approach

PURPOSE/OBJECTIVE(S)

There are several methods used against respiratory motion (RM). Expiratory breath-hold (BH) is considered more stable and reproducible than inspiratory BH; therefore, BH with spirometry is often used for expiration. The real-time tumor tracking radiotherapy (RTRT) system is a highly effective method for reducing the margin of RM. This system ambushes and irradiates tumors during the expiratory phase when tumors move slowly. Although these methods usually involve expiration, it is advantageous to expand the lungs with inspiration to reduce the risk of adverse events. Here, we developed a new approach of performing stereotactic body radiation therapy (SBRT) under deep-inspiration BH (DIBH) by combining these two methods.

MATERIALS/METHODS

Lung tumors with respiratory motion ≥ 1 cm were included. Three or four fiducial markers were placed near the tumor via bronchoscopy. DIBH CT (CT-IN) was performed under the guidance of spirometer. The PTV was obtained by adding a 5-mm margin to the GTV delineated on CT-IN. The prescribed dose was 42 Gy in four fractions for the D95 of the PTV. An error of 2.0 mm around the planned position of the fiducial marker on CT-IN was permitted along each orthogonal axis as a gating box. In preparation for cases in which the reproducibility of DIBH is low and treatment cannot be performed, light expiration BH CT (CT-EX) was also performed, and a radiotherapy plan was prepared for the conventional RTRT system so that it could be switched at any time. Lung volumes and doses (mean dose, V20 Gy, V10 Gy, and V5 Gy) on CT-EX and CT-IN were compared.

RESULTS

Five patients underwent SBRT with DIBH, and all completed the planned irradiation course. The median treatment time per fraction was 27.86 min (range, 25.5-40.6). Four tumors were located in the left lower lobe and one in the right lower lobe. The median volume of PTV was 12.4 (range, 5.2-26.2) mL. The lung volumes and doses on CT-EX and CT-IN are shown in the Table. The lung volume on CT-IN was 1.6 times larger than that on CT-EX. The PTV-to-lung ratio on CT-IN was significantly lower than that on CT-EX. V20 Gy and V10 Gy on CT-IN were significantly lower than those on CT-EX.

CONCLUSION

SBRT with DIBH was achieved by combining the spirometer and RTRT system. This can help to eliminate concerns about reproducibility and high-speed tumor movement during inspiration, which are weaknesses of spirometer-guided breath-hold and the RTRT system, respectively, while ensuring the accuracy of the RTRT system. DIBH SBRT is a promising method that can reduce lung dose.

Lack of Musashi-2 induces type IIa fiber-dominated muscle atrophy

Skeletal muscle is a highly plastic tissue, adapting its structure and metabolism in response to diverse conditions such as contractile activity, nutrients, and diseases. Finding a novel master regulator of muscle mass and quality will provide new therapeutic targets for the prevention and treatment of muscle weakness. Musashi is an RNA-binding protein that dynamically regulates protein expression; it was originally discovered as a cell fate determination factor in neural cells. Here, we report that Musashi-2 (Msi2) is dominantly expressed in slow-type muscle fibers, fibers characterized by high metabolism and endurance. Msi2 knockout (KO) mice exhibited a decrease in both soleus myofiber size and number compared to control mice. Biochemical and histological analyses revealed that type IIa fibers, which are of the fast type but have high metabolic capacity, were decreased in Msi2 KO mice. The contraction force of isolated soleus muscle was lower in KO mice, and the expression of the metabolic proteins, cytochrome c oxidase and myoglobin, was also decreased in KO muscle. Our data demonstrate the critical role of Msi2 in the maintenance of normal fiber-type composition and metabolism.

Stable isotope-labeled carnitine reveals its rapid transport into muscle cells and acetylation during contraction

Carnitine plays multiple roles in skeletal muscle metabolism, including fatty acid transport and buffering of excess acetyl-CoA in the mitochondria. The skeletal muscle cannot synthesize carnitine; therefore, carnitine must be taken up from the blood into the cytoplasm. Carnitine metabolism, its uptake into cells, and the subsequent reactions of carnitine are accelerated by muscle contraction. Isotope tracing enables the marking of target molecules and monitoring of tissue distribution. In this study, stable isotope-labeled carnitine tracing was combined with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging to determine carnitine distribution in mouse skeletal muscle tissues. Deuterium-labeled carnitine (d3-carnitine) was intravenously injected into the mice and diffused to the skeletal muscles for 30 and 60 min. To examine whether muscle contraction changes the distribution of carnitine and its derivatives, unilateral in situ muscle contraction was performed; 60 min muscle contraction showed increased d3-carnitine and its derivative d3-acetylcarnitine in the muscle, indicating that carnitine uptake in cells is promptly converted to acetylcarnitine, consequently, buffering accumulated acetyl-CoA. While the endogenous carnitine was localized in the slow type fibers rather than fast type, the contraction-induced distributions of d3-carnitine and acetylcarnitine were not necessarily associated with muscle fiber type. In conclusion, the combination of isotope tracing and MALDI-MS imaging can reveal carnitine flux during muscle contraction and show the significance of carnitine in skeletal muscles.

PDGF-B secreted from skeletal muscle enhances myoblast proliferation and myotube maturation via activation of the PDGFR signaling cascade

Myokines, secreted factors from skeletal muscle, act locally on muscle cells or satellite cells, which is important in regulating muscle mass and function. Here, we found platelet-derived growth factor subunit B (PDGF-B) is constitutively secreted from muscle cells without muscle contraction. Furthermore, PDGF-B secretion increased with myoblast to myotube differentiation. To examine the role of PDGF-B as a paracrine or autocrine myokine, myoblasts or myotubes were treated with PDGF-B. As a result, myoblast proliferation was significantly enhanced via several signaling pathways. Intriguingly, myotubes treated with PDGF-B showed enhanced maturation as indicated by their increased myotube diameter, myosin heavy chain expression, and strengthened contractile force. These findings suggest that PDGF-B is constitutively secreted by myokines to enhance myoblast proliferation and myotube maturation, which may contribute to skeletal muscle regeneration.

POS0794 PREGNANCY AND CHILDBIRTH IN TAKAYASU ARTERITIS IN JAPAN – A NATIONWIDE RETROSPECTIVE STUDY

Background

Takayasu arteritis (TAK), a granulomatous large vessel vasculitis, mainly involves the aorta and its proximal branches and commonly occurs in young females. However, studies of pregnancy in women with TAK are sparse and limited, probably due to the rarity of the disease.

Objectives

The purpose of this study was to understand the status quo of medical treatments of the primary disease and outcomes of pregnancy in patients with TAK, and birth outcomes of the children in Japan.

Methods

Patients with TAK who conceived after the onset of the disease and were managed at medical facilities participating in the Japan Research Committee of the Ministry of Health, Labour, and Welfare for Intractable Vasculitis (JPVAS) were retrospectively enrolled in this study. The following information was collected from patients who had a live-born baby: age at diagnosis of TAK, disease classification, age at delivery, treatments before and during pregnancy, complications during pregnancy, birth outcomes of the children, and changes in disease activity during pregnancy and after delivery.

Results

Fifty-one cases and 69 pregnancies from 19 ethics committee-approved centers were enrolled during the study period 2019–2021. Of these, 49 cases and 66 pregnancies (95.7%) resulted in delivery and live-born babies. The Numano classification of the 49 cases was as follows: type I, 11; type IIa, 15; type IIb,12; type III, 1; type IV, 1; type V, 9; with type IIa being the most common. The age of diagnosis was 22 years (13–37 years, year of diagnosis 1965–2017), the median age of the delivery of 66 pregnancies was 31 years (year of delivery 1969-2021), and the median duration of illness at delivery was nine years. There were 34 planned pregnancies (51.5%, including four pregnancies by artificial insemination/ovulation induction). Preconception therapy included prednisolone (PSL) in 51 pregnancies (77.3%, median dose 7.5 mg (range 4–30 mg)/day), immunosuppressive drugs in 18 pregnancies (27.3%, azathioprine 8, tacrolimus 7, methotrexate 4, cyclosporin A 1, and colchicine 1), biologics in 12 pregnancies (18.1%, infliximab 6, tocilizumab 5, and adalimumab 1), antihypertensive drugs in 5 pregnancies (7.6%). Surgical treatment had been performed before pregnancy in 6 cases (aortic root replacement 2, subclavian artery dilatation 1, subclavian artery bypass 1, subclavian artery stenting 1, and ascending aorta semicircular artery replacement 1). Medications used during the course of pregnancy included PSL in 48 pregnancies (72.7%, median dose 8 mg (range 4–30 mg)/day, increased in 13 pregnancies, decreased in 1 pregnancy), immunosuppressants in 13 pregnancies (19.7%, azathioprine 6, tacrolimus 6, and cyclosporin A 1), biologics 9 pregnancies (13.6%, infliximab 4, tocilizumab 4, and adalimumab 1). Immunosuppressants and biologics were discontinued in five and four pregnancies after conception. Complications during pregnancy were observed in 20 pregnancies (30.3%), with hypertension being the most common. Complications related to TAK or its treatment were severe infections in two pregnancies and aneurysm enlargement due to increased circulating plasma volume in one pregnancy. Aortic arch replacement was performed after delivery for the latter case. Relapse of TAK was observed in 4 pregnancies (6.1%) during pregnancy and in 8 pregnancies (12.1%) after delivery. One pregnancy resulted in restenosis of subclavian artery for which dilatation procedure was performed prior to the pregnancy. There were 13/66 (19.7%) preterm infants and 17/59 (28.8%) low birth weight infants; all but one had a birth weight of more than 2,000 g and no had serious postnatal abnormalities. Forty-three (82.7%) of the 52 confirmed infants were breastfeed fully or mixed.

Conclusion

Most of the pregnancies in patients with TAK were successfully delivered while they had low disease activity at a dose of less than 10 mg/day of PSL. Relapse occurred during pregnancy and after delivery in some cases. The babies tended to have low birth weight, but 82.7% of them were breastfed without serious complications.

Disclosure of Interests

Takako Miyamae: None declared, Yusuke Manabe: None declared, takahiko sugihara Speakers bureau: TS has received honoraria from Abbvie Japan Co., Ltd., AsahiKASEI Co., Ltd., Astellas Pharma Inc., Ayumi Pharmaceutical, Bristol Myers Squibb K.K., Chugai Pharmaceutical Co., Ltd., Eli Lilly Japan K.K., Mitsubishi-Tanabe Pharma Co., Ono Pharmaceutical, Pfizer Japan Inc., Takeda Pharmaceutical Co. Ltd., and UCB Japan Co., Grant/research support from: TS has received research grants from AsahiKASEI Co., Ltd., Daiichi Sankyo., Chugai Pharmaceutical Co., Ltd., and Ono Pharmaceutical., Natsuka Umezawa: None declared, Hajime Yoshifuji Speakers bureau: HY has received lecture fees from Janssen and Chugai., Naoto Tamura: None declared, Yoshiyuki Abe: None declared, Shunsuke Furuta Speakers bureau: Chugai Pharmaceutical Co.,Ltd.

DaiichiSankyo Co.,Ltd.

Asahi-Kasei Pharma Corporation, Manami Kato: None declared, Takashi Kumagai: None declared, Kaito Nakamura: None declared, Hiroko Nagafuchi: None declared, Jun Ishizaki: None declared, Naoko Nakano: None declared, Tatsuya Atsumi Speakers bureau: Mitsubishi Tanabe Pharma Co., Chugai Pharmaceutical Co., Ltd., Astellas Pharma Inc., Takeda Pharmaceutical Co., Ltd., Pfizer Inc., AbbVie Inc., Eisai Co. Ltd., Daiichi Sankyo Co., Ltd., Bristol-Myers Squibb Co., UCB Japan Co. Ltd., Eli Lilly Japan K.K., Novartis Pharma K.K., Eli Lilly Japan K.K., Kyowa Kirin Co., Ltd.,TAIHO PHARMACEUTICAL CO., LTD., Consultant of: AstraZeneca plc., MEDICAL & BIOLOGICAL LABORATORIES CO., LTD., Pfizer Inc., AbbVie Inc., ONO PHARMACEUTICAL CO. LTD.,

Novartis Pharma K.K., Nippon Boehringer Ingelheim Co., Ltd., Grant/research support from: Astellas Pharma Inc., TAIHO PHARMACEUTICAL CO., LTD.AbbVie Inc., Nippon Boehringer Ingelheim Co., Ltd.,Takeda Pharmaceutical Co., Ltd., Mitsubishi Tanabe Pharma Co., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co. Ltd., Otsuka Pharmaceutical Co., Ltd. and Pfizer Inc. Alexion Inc., TEIJIN PHARMA LIMITED., Kohei Karino: None declared, Koichi Amano Speakers bureau: AbbVie GK, Asahi-Kasei Pharma, Astellas, Chugai Pharmaceutical Co.Ltd., Eisai, Eli Lilly, GlaxoSmithKlein, Janssen Pharma, Pfizer Japan, Grant/research support from: Asahi-Kasei Pharma,Chugai Pharmaceutical Co.Ltd., Takahiko Kurasawa: None declared, Shuichi Ito: None declared, Ryusuke Yoshimi: None declared, Noriyoshi Ogawa: None declared, Shogo Banno: None declared, Taio Naniwa Speakers bureau: Chugai, Tanabe, Abbbvie, Eisai, Grant/research support from: Chugai, Tanabe, Abbbvie, Eisai, Satoshi Ito Speakers bureau: SI has received speaker’s fees from pharmaceutical companies., Akinori Hara: None declared, Shinya Hirahara: None declared, Haruhito A. Uchida: None declared, Yasuhiro Onishi: None declared, Yohko Murakawa Speakers bureau: Astellas, UCB, Chugai, AbbVie, Grant/research support from: Chugai, AbbVie, Yoshinori Komagata: None declared, Yoshikazu Nakaoka: None declared, Masayoshi Harigai Speakers bureau: MH has received speaker’s fee from AbbVie Japan GK, Ayumi Pharmaceutical Co., Boehringer Ingelheim Japan, Inc., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., Janssen Pharmaceutical K.K., Kissei Pharmaceutical Co., Ltd., Novartis Japan, Pfizer Japan Inc., Mitsubishi Tanabe Pharma Co., Teijin Pharma Ltd and UCB Japan., Consultant of: MH is a consultant for AbbVie, Boehringer-Ingelheim, Kissei Pharmaceutical Co., Ltd., and Teijin Pharma.

Mass spectrometry imaging reveals local metabolic changes in skeletal muscle due to chronic training

Muscle atrophy is a major health problem that needs effective prevention and treatment approaches. Chronic exercise, an effective treatment strategy for atrophy, promotes muscle hypertrophy, which leads to dynamic metabolic changes; however, the metabolic changes vary among myofiber types. To investigate local metabolic changes due to chronic exercise, we utilized comprehensive proteome and mass spectrometry (MS) imaging analyses. Our training model exhibited hypertrophic features only in glycolytic myofibers. The proteome analyses demonstrated that exercise promoted anabolic pathways, such as protein synthesis, and significant changes in lipid metabolism, but not in glucose metabolism. Furthermore, the fundamental energy sources, glycogen, neutral lipids, and ATP, were sensitive to exercise, and the changes in these sources differed between glycolytic and oxidative myofibers. MS imaging revealed that the lipid composition differs among myofibers; arachidonic acid might be an effective target for promoting lipid metabolism during muscle hypertrophy in oxidative myofibers.

Single-Cell Information Analysis Reveals That Skeletal Muscles Incorporate Cell-to-Cell Variability as Information Not Noise

Cell-to-cell variability in signal transduction in biological systems is often considered noise. However, intercellular variation (i.e., cell-to-cell variability) has the potential to enable individual cells to encode different information. Here, we show that intercellular variation increases information transmission of skeletal muscle. We analyze the responses of multiple cultured myotubes or isolated skeletal muscle fibers as a multiple-cell channel composed of single-cell channels. We find that the multiple-cell channel, which incorporates intercellular variation as information, not noise, transmitted more information in the presence of intercellular variation than in the absence according to the "response diversity effect," increasing in the gradualness of dose response by summing the cell-to-cell variable dose responses. We quantify the information transmission of human facial muscle contraction during intraoperative neurophysiological monitoring and find that information transmission of muscle contraction is comparable to that of a multiple-cell channel. Thus, our data indicate that intercellular variation can increase the information capacity of tissues.

Excess Glucose Impedes the Proliferation of Skeletal Muscle Satellite Cells Under Adherent Culture Conditions

Glucose is a major energy source consumed by proliferating mammalian cells. Therefore, in general, proliferating cells have the preference of high glucose contents in extracellular environment. Here, we showed that high glucose concentrations impede the proliferation of satellite cells, which are muscle-specific stem cells, under adherent culture conditions. We found that the proliferation activity of satellite cells was higher in glucose-free DMEM growth medium (low-glucose medium with a glucose concentration of 2 mM) than in standard glucose DMEM (high-glucose medium with a glucose concentration of 19 mM). Satellite cells cultured in the high-glucose medium showed a decreased population of reserve cells, identified by staining for Pax7 expression, suggesting that glucose concentration affects cell fate determination. In conclusion, glucose is a factor that decides the cell fate of skeletal muscle-specific stem cells. Due to this unique feature of satellite cells, hyperglycemia may negatively affect the regenerative capability of skeletal muscle myofibers and thus facilitate sarcopenia.

Effect of antioxidant supplementation on skeletal muscle and metabolic profile in aging mice

Aging induces drastic changes in muscle mass and function (sarcopenia); however, the detailed mechanisms underlying sarcopenia remain poorly understood. Recent studies suggested that age-related increases in oxidative stress induce muscle atrophy. In this study, we investigated the effect of 6-month supplementation of antioxidants, specifically piceatannol (PIC) and enzymatically modified isoquercitrin (EMIQ), on age-related physiological changes, including skeletal muscle weight and quality, in 25-month-old (OLD) mice, compared to in 4-month-old (young, YNG) C57BL/6J mice. Muscle weight corrected by body weight significantly declined in OLD mice, compared to in YNG mice. The control OLD mice also showed changes in the expression of genes related to muscle fiber type, reduced locomotor activity, and increased oxidative stress markers in blood. Consistent with the muscle weight and quality changes, whole-body fat oxidation during sedentary conditions and exercise periods in control OLD mice was significantly lower than that in YNG mice. Interestingly, compared to the control OLD mice, the PIC- or EMIQ-fed OLD mice showed higher fat oxidation. Furthermore, EMIQ, but not PIC, increased locomotor activity, the expression of genes encoding antioxidant enzymes, and suppressed the carbonylated protein in the skeletal muscle of OLD mice. These results suggested that chronic antioxidant intake could alleviate aging-related muscle function changes.

Behavior of glycolylated sialoglycans in the binding pockets of murine and human CD22

Siglecs (sialic acid binding immunoglobulin (Ig)-like lectins) constitute a group of 15 human and 9 murine cell-surface transmembrane receptors belonging to the I-type lectin family, mostly expressed on innate immune cells and characterized by broadly similar structural features. Here, the prominent inhibitory CD22 (Siglec-2), well known in maintaining tolerance and preventing autoimmune responses on B cells, is studied in its human and murine forms in complex with sialoglycans. In detail, the role of the N-glycolyl neuraminic acid (Neu5Gc) moiety in the interaction with both orthologues was explored. The analysis of the binding mode was carried out by the combination of NMR spectroscopy, computational approaches, and CORCEMA-ST calculations. Our findings provide a first model of Neu5Gc recognition by h-CD22 and show a comparable molecular recognition profile by h- and m-CD22. These data open the way to innovative diagnostic and/or therapeutic methodologies to be used in the modulation of the immune responses.

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The structural basis of sialoglycans recognition by h/m CD22 has been investigated

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The binding modes of Neu5Gc-/Neu5Ac-containing ligands to m/h-CD22 were compared

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The bioactive conformation of sialoglycans has been derived

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Our findings may help in the regulation of immune response and cancer prevention

Trans-omic Analysis Reveals ROS-Dependent Pentose Phosphate Pathway Activation after High-Frequency Electrical Stimulation in C2C12 Myotubes

Skeletal muscle adaptation is mediated by cooperative regulation of metabolism, signal transduction, and gene expression. However, the global regulatory mechanism remains unclear. To address this issue, we performed electrical pulse stimulation (EPS) in differentiated C2C12 myotubes at low and high frequency, carried out metabolome and transcriptome analyses, and investigated phosphorylation status of signaling molecules. EPS triggered extensive and specific changes in metabolites, signaling phosphorylation, and gene expression during and after EPS in a frequency-dependent manner. We constructed trans-omic network by integrating these data and found selective activation of the pentose phosphate pathway including metabolites, upstream signaling molecules, and gene expression of metabolic enzymes after high-frequency EPS. We experimentally validated that activation of these molecules after high-frequency EPS was dependent on reactive oxygen species (ROS). Thus, the trans-omic analysis revealed ROS-dependent activation in signal transduction, metabolome, and transcriptome after high-frequency EPS in C2C12 myotubes, shedding light on possible mechanisms of muscle adaptation.

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We performed electrical pulse stimulation in differentiated C2C12 myotubes

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We constructed trans-omic network after high-frequency electrical pulse stimulation

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Trans-omic network integrates metabolome, transcriptome, and signaling molecules

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We identified ROS-dependent pentose phosphate pathway activation

R3hdml regulates satellite cell proliferation and differentiation

In this study, we identified a previously uncharacterized skeletal satellite cell-secreted protein, R3h domain containing-like (R3hdml). Expression of R3hdml increases during skeletal muscle development and differentiation in mice. Body weight and skeletal muscle mass of R3hdml knockout (KO) mice are lower compared to control mice. Expression levels of cell cycle-related markers, phosphorylation of Akt, and expression of insulin-like growth factor within the skeletal muscle are reduced in R3hdml KO mice compared to control mice. Expression of R3hdml increases during muscle regeneration in response to cardiotoxin (CTX)-induced muscle injury. Recovery of handgrip strength after CTX injection was significantly impaired in R3hdml KO mice, which is rescued by R3hdml. Our results indicate that R3hdml is required for skeletal muscle development, regeneration, and, in particular, satellite cell proliferation and differentiation.

A new in vitro muscle contraction model and its application for analysis of mTORC1 signaling in combination with contraction and beta-hydroxy-beta-methylbutyrate administration

Several food constituents augment exercise-induced muscle strength improvement; however, the detailed mechanism underlying these combined effects is unknown because of the lack of a cultured cell model for evaluating the contraction-induced muscle protein synthesis level. Here, we aimed to establish a new in vitro muscle contraction model for analyzing the activation of mammalian target of rapamycin complex 1 (mTORC1) signaling. We adopted the tetanic electric stimulation of 50 V at 100 Hz for 10 min in L6.C11 myotubes. Akt, ERK1/2, and p70S6K phosphorylation increased significantly after electrical pulse stimulation (EPS), compared to untreated cells. Next, we used this model to analyze mTORC1 signaling in combination with exercise and beta-hydroxy-beta-methylbutyrate (HMB), an l-leucine metabolite. p70S6K phosphorylation increased significantly in the EPS+HMB group compared to that in the EPS-alone group. These findings show that our model could be used to analyze mTORC1 signaling and that HMB enhances muscle contraction-activated mTORC1 signaling.

What are the risk factors for postoperative infections of third molar extraction surgery: A retrospective clinical study?

BACKGROUND

This study aimed to identify (1) the predilection site of postoperative infection after third molar extraction surgery, (2) risk factors associated with postoperative infection, and (3) the cause of the difference between delayed- and early-onset infections.

MATERIALS AND METHODS

This retrospective study included 1010 patients (396 male, 614 female) who had ≥1 third molars extracted (2407; 812 maxilla, 1595 mandible). The risk factors were classified as attributes, general health, anatomic, and operative. Outcome variables were delayed- and early-onset infections.

RESULTS

Postoperative infection was completely absent in the maxilla, and all infections occurred in the mandible, with a probability of 1.94% (31/1595). Bivariate analysis for postoperative infection showed depth of inclusion and intraoperative hemostatic treatment to be significantly associated with the development of infections. Bivariate analysis for delayed- and early-onset infections showed simultaneous extraction of the left and right mandibular third molars to be prominent risk factors.

CONCLUSIONS

Postoperative infection occurs mainly in the mandible, and that in the maxilla is very rare. The risk of postoperative infection in the mandible was found to be related to the depth of inclusion and intraoperative hemostatic treatment. Simultaneous extraction of the left and right mandibular third molars appear to increase the risk of delayed-onset postoperative infection.

Evidence for acute contraction-induced myokine secretion by C2C12 myotubes

Skeletal muscle is considered a secretory organ that produces bioactive proteins known as myokines, which are released in response to various stimuli. However, no experimental evidence exists regarding the mechanism by which acute muscle contraction regulates myokine secretion. Here, we present evidence that acute contractions induced myokine secretion from C2C12 myotubes. Changes in the cell culture medium unexpectedly triggered the release of large amounts of proteins from the myotubes, and these proteins obscured the contraction-induced myokine secretion. Once protein release was abolished, the secretion of interleukin-6 (IL-6), the best-known regulatory myokine, increased in response to a 1-hour contraction evoked by electrical stimulation. Using this experimental condition, intracellular calcium flux, rather than the contraction itself, triggered contraction-induced IL-6 secretion. This is the first report to show an evidence for acute contraction-induced myokine secretion by skeletal muscle cells.

[Do Myokines Have Potential as Exercise Mimetics?]

　Exercise is generally considered to have health benefits for the body, although its beneficial mechanisms have not been fully elucidated. Recent progressive research suggests that myokines, bioactive substances secreted from skeletal muscle, play an important role in mediating the benefits of exercise. There are three types of myokines in terms of the muscular secretion mechanism: those in which the secretion is promoted by stimulation, such as irisin, interleukin (IL)-6, and IL-15; those whose secretion is constitutive, such as thioredoxin, glutaredoxin, and peroxiredoxin; and those whose secretion is suppressed by stimulation, such as by a macrophage migration inhibitory factor. Although dozens of myokines have been reported, their physiological roles are not well understood. Therefore, there currently exists no advanced drug discovery research specifically targeting myokines, with the exception of Myostatin. Myostatin was discovered as a negative regulator of muscle growth. Myostatin is secreted from muscle cells as a myokine; it signals via an activin type IIB receptor in an autocrine manner, and regulates gene expressions involved in myogenesis. Given the studies to date that have been conducted on the utilization of myostatin inhibitors for the treatment of muscle weakness, including cachexia and sarcopenia, other myokines may also be new potential drug targets.

Dammarane-type triterpene extracts of Panax notoginseng root ameliorates hyperglycemia and insulin sensitivity by enhancing glucose uptake in skeletal muscle

Skeletal muscle is an important organ for controlling the development of type 2 diabetes. We discovered Panax notoginseng roots as a candidate to improve hyperglycemia through in vitro muscle cells screening test. Saponins are considered as the active ingredients of ginseng. However, in the body, saponins are converted to dammarane-type triterpenes, which may account for the anti-hyperglycemic activity. We developed a method for producing a dammarane-type triterpene extract (DTE) from Panax notoginseng roots and investigated the extract's potential anti-hyperglycemic activity. We found that DTE had stronger suppressive activity on blood glucose levels than the saponin extract (SE) did in KK-Ay mice. Additionally, DTE improved oral glucose tolerance, insulin sensitivity, glucose uptake, and Akt phosphorylation in skeletal muscle. These results suggest that DTE is a promising agent for controlling hyperglycemia by enhancing glucose uptake in skeletal muscle.

An improved glucose transport assay system for isolated mouse skeletal muscle tissues

There is a growing demand for a system in the field of sarcopenia and diabetes research that could be used to evaluate the effects of functional food ingredients that enhance muscle mass/contractile force or muscle glucose uptake. In this study, we developed a new type of in vitro muscle incubation system that systemizes an apparatus for muscle incubation, using an electrode, a transducer, an incubator, and a pulse generator in a compact design. The new system enables us to analyze the muscle force stimulated by the electric pulses and glucose uptake during contraction and it may thus be a useful tool for analyzing the metabolic changes that occur during muscle contraction. The system may also contribute to the assessments of new food ingredients that act directly on skeletal muscle in the treatment of sarcopenia and diabetes.