Pan-Asian adapted ESMO Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with gastric cancer

The European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with gastric cancer (GC), published in late 2022 and the updated ESMO Gastric Cancer Living Guideline published in July 2023, were adapted in August 2023, according to previously established standard methodology, to produce the Pan-Asian adapted (PAGA) ESMO consensus guidelines for the management of Asian patients with GC. The adapted guidelines presented in this manuscript represent the consensus opinions reached by a panel of Asian experts in the treatment of patients with GC representing the oncological societies of China (CSCO), Indonesia (ISHMO), India (ISMPO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), the Philippines (PSMO), Singapore (SSO), Taiwan (TOS) and Thailand (TSCO), coordinated by ESMO and the Japanese Society of Medical Oncology (JSMO). The voting was based on scientific evidence and was independent of the current treatment practices, drug access restrictions and reimbursement decisions in the different Asian regions represented by the 10 oncological societies. The latter are discussed separately in the manuscript. The aim is to provide guidance for the optimisation and harmonisation of the management of patients with GC across the different regions of Asia, drawing on the evidence provided by both Western and Asian trials, whilst respecting the differences in screening practices, molecular profiling and age and stage at presentation. Attention is drawn to the disparity in the drug approvals and reimbursement strategies, between the different regions of Asia.

Thromboelastographic evaluation after cardiac surgery optimizes transfusion requirements in the intensive care unit: a single-center retrospective cohort study using an inverse probability weighting method

OBJECTIVE

There are no reports from Japan showing the effects of using the thromboelastography algorithm on transfusion requirements after Intensive Care Unit (ICU) admission, and post-implementation knowledge regarding the thromboelastography algorithm under the Japanese healthcare system is insufficient. Therefore, this study aimed to clarify the effect of the TEG6s thromboelastography algorithm on transfusion requirements for patients in the ICU after cardiac surgery.

METHODS

We retrospectively compared the requirements for blood transfusion up to 24 h after ICU admission using the thromboelastography algorithm (January 2021 to April 2022) (thromboelastography group; n = 201) and specialist consultation with surgeons and anesthesiologists (January 2018 to December 2020) (non-thromboelastography group; n = 494).

RESULTS

There were no significant between-group differences in terms of age, height, weight, body mass index, operative procedure, duration of surgery or cardiopulmonary bypass, body temperature, or urine volume during surgical intervention. Moreover, there was no significant between-group difference in the amount of drainage at 24 h after ICU admission. However, crystalloid and urine volumes were significantly higher in the thromboelastography group than in the non-thromboelastography group. Additionally, fresh-frozen plasma (FFP) transfusion volumes were significantly lower in the thromboelastography group. However, there were no significant between-group differences in red blood cell count or platelet transfusion volume. After variable adjustment, the amount of FFP used from the operating room to 24 h after ICU admission was significantly reduced in the thromboelastography group.

CONCLUSIONS

The thromboelastography algorithm optimized transfusion requirements at 24 h after admission to the ICU following cardiac surgery.

Chemotherapy after nivolumab for advanced gastric cancer (REVIVE): a prospective observational study

BACKGROUND

Nivolumab therapy is a standard-of-care treatment for heavily pretreated patients with advanced gastric cancer (AGC). Previous studies have reported improvement in the objective response rate to chemotherapy after nivolumab therapy for other types of cancer. This study evaluated the efficacy and safety of chemotherapy after nivolumab therapy in AGC.

PATIENTS AND METHODS

We conducted a prospective, multicenter, observational study in pretreated patients with nivolumab-refractory or -intolerant AGC. Patients received irinotecan, oxaliplatin-containing regimens, or trifluridine/tipiracil. The primary endpoint was overall survival.

RESULTS

A total of 199 patients were included (median age: 69 years; male: 70%; female: 30%). Median overall survival and progression-free survival were 7.5 months [95% confidence interval (CI): 6.7-9.7 months] and 2.9 months (95% CI: 2.2-3.5 months), respectively. Objective response and disease control rates were 16.8% (95% CI: 11.6% to 23.6%) and 18.9% (95% CI: 38.9% to 54.6%), respectively. A prognostic index using alkaline phosphatase and the Glasgow Prognostic Score was generated to classify patients into three risk groups (good, moderate, and poor). The hazard ratios of the moderate and poor groups to the good group were 1.88 (95% CI: 1.22-2.92) and 3.29 (95% CI: 1.92-5.63), respectively. At the initiation of chemotherapy, 42 patients had experienced immune-related adverse events due to prior nivolumab therapy. The most common grade 3-4 adverse events were neutropenia (7.5%), anemia (8.0%), and anorexia (7.5%).

CONCLUSIONS

The administration of cytotoxic chemotherapy after nivolumab therapy may give rise to a synergistic antitumor effect in AGC. Further investigation is warranted to confirm these findings.

Development of novel waxy bone haemostatic agents composed of biodegradable polymers with osteogenic-enhancing peptides in rabbit models

OBJECTIVES

The use of bone wax (BW) is controversial for sternal haemostasis because it increases the risk of wound infection and inhibits bone healing. We developed new waxy bone haemostatic agents made from biodegradable polymers containing peptides and evaluated them using rabbit models.

METHODS

We designed 2 types of waxy bone haemostatic agents: peptide wax (PW) and non-peptide wax (NPW), which used poly(ε-caprolactone)-based biodegradable polymers with or without an osteogenesis-enhancing peptide, respectively. Rabbits were randomly divided into 4 groups based on treatment with BW, NPW, PW or no treatment. In a tibial defect model, the bleeding amount was measured and bone healing was evaluated by micro-computed tomography over 16 weeks. Bone healing in a median sternotomy model was assessed for 2 weeks using X-ray, micro-computed tomography, histological examination and flexural strength testing.

RESULTS

The textures of PW and NPW (n = 12 each) were similar to that of BW and achieved a comparable degree of haemostasis. The crevice area of the sternal fracture line in the BW group was significantly larger than that in other groups (n = 10 each). The PW group demonstrated the strongest sternal flexural strength (n = 10), with complete tibial healing at 16 weeks. No groups exhibited wound infection, including osteomyelitis.

CONCLUSIONS

Waxy biodegradable haemostatic agents showed satisfactory results in haemostasis and bone healing in rabbit models and may be an effective alternative to BW.

A review of current status of cell-based therapies for aortic aneurysms

An aortic aneurysm (AA) is defined as focal aortic dilation that occurs mainly with older age and with chronic inflammation associated with atherosclerosis. The aneurysmal wall is a complex inflammatory environment characterized by endothelial dysfunction, macrophage activation, vascular smooth muscle cell (VSMC) apoptosis, and the production of proinflammatory molecules and matrix metalloproteases (MMPs) secreted by infiltrated inflammatory cells such as macrophages, T and B cells, dendritic cells, neutrophils, mast cells, and natural killer cells. To date, a considerable number of studies have been conducted on stem cell research, and growing evidence indicates that inflammation and tissue repair can be controlled through the functions of stem/progenitor cells. This review summarizes current cell-based therapies for AA, involving mesenchymal stem cells, VSMCs, multilineage-differentiating stress-enduring cells, and anti-inflammatory M2 macrophages. These cells produce beneficial outcomes in AA treatment by modulating the inflammatory environment, including decreasing the activity of proinflammatory molecules and MMPs, increasing anti-inflammatory molecules, modulating VSMC phenotypes, and preserving elastin. This article also describes detailed studies on pathophysiological mechanisms and the current progress of clinical trials.

A rare case of delayed complete lead dislodgement after deep septal pacing: A hidden risk of the specific procedure

Deep septal ventricular pacing is a recently developed physiological pacing modality with good efficacy; however, it has a potential risk of unusual complications. Here, we report a patient with pacing failure and spontaneous, complete lead dislodgement after >2 years of deep septal pacing, possibly caused by systemic bacterial infection and specific lead behavior in the septal myocardium. This case report may implicate a hidden risk of unusual complications in deep septal pacing.

Novel Functional Peptide for Next-Generation Vital Pulp Therapy

Although vital pulp therapy should be performed by promoting the wound-healing capacity of dental pulp, existing pulp-capping materials were not developed with a focus on the pulpal repair process. In previous investigations of wound healing in dental pulp, we found that organic dentin matrix components (DMCs) were degraded by matrix metalloproteinase-20, and DMC degradation products containing protein S100A7 (S100A7) and protein S100A8 (S100A8) promoted the pulpal wound-healing process. However, the direct use of recombinant proteins as pulp-capping materials may cause clinical problems or lead to high medical costs. Thus, we hypothesized that functional peptides derived from recombinant proteins could solve the problems associated with direct use of such proteins. In this study, we identified functional peptides derived from the protein S100 family and investigated their effects on dental pulp tissue. We first performed amino acid sequence alignments of protein S100 family members from several mammalian sources, then identified candidate peptides. Next, we used a peptide array method that involved human dental pulp stem cells (hDPSCs) to evaluate the mineralization-inducing ability of each peptide. Our results supported the selection of 4 candidate functional peptides derived from proteins S100A8 and S100A9. Direct pulp-capping experiments in a rat model demonstrated that 1 S100A8-derived peptide induced greater tertiary dentin formation compared with the other peptides. To investigate the mechanism underlying this induction effect, we performed liquid chromatography-tandem mass spectrometry analysis using hDPSCs and the S100A8-derived peptide; the results suggested that this peptide promotes tertiary dentin formation by inhibiting inflammatory responses. In addition, this peptide was located in a hairpin region on the surface of S100A8 and could function by direct interaction with other molecules. In summary, this study demonstrated that a S100A8-derived functional peptide promoted wound healing in dental pulp; our findings provide insights for the development of next-generation biological vital pulp therapies.

Impact of an improved driveline management for HeartMate II and HeartMate 3 left ventricular assist devices

BACKGROUND

We evaluated the impact of a standardized driveline care strategy, including a subfascial-tunneling method and dressing protocol, on the incidence of driveline infection (DLI).

METHODS

DLI data from all HeartMate II (HMII) and HeartMate 3 (HM3) patients (including exchange devices) were retrospectively collected between 2013 and 2021. The driveline subfascial-tunneling method was altered in three steps (A: right direct; B: left triple, C: right triple), and the shower protocol was changed in two steps (A: with/without cover, B: with cover). Disinfection was individually tailored after changing the shower protocol. Complications associated with morbidity and mortality were evaluated for each modification.

RESULTS

During the study period, 80 devices were implanted (HMII, n = 54; HM3, n = 26). The 8-year incidence of DLI was 15% (n = 8) in HMII patients and 0% in HM3 patients (p = 0.039). DLI was not associated with hospital mortality. The modified dressing protocol and tunneling method was associated with a significantly better DLI incidence rate in comparison to the previous one: Protocol-A (n = 17), Protocol-B (n = 63), 35% vs 3% (p = 0.0009), Method-A (n = 13), Method-B (n = 42), Method-C (n = 25), 46% vs 5% vs 0% (p = 0.0001). The rete of freedom form DLI at 1, 2, and 3 years had also significant difference between groups: Protocol-A and Protocol-B, 80%, 54%, 54% vs 96%, 96%, 96%, respectively (p < 0.0001), Method-A, Method-B and Method-C, 76%, 44%, 44%, vs 94%, 94%, 94% vs 100%, 100%, respectively (p < 0.0001).

CONCLUSIONS

A standardized triple driveline tunneling strategy and waterproof dressing protocol reduced driveline infection in HM3 patients to 0%.

Administration of anti-inflammatory M2 macrophages suppresses progression of angiotensin II-induced aortic aneurysm in mice

Aortic aneurysm (AA) is a vascular disorder characterized pathologically by inflammatory cell invasion and extracellular matrix (ECM) degradation. It is known that regulation of the balance between pro-inflammatory M1 macrophages (M1Ms) and anti-inflammatory M2 macrophages (M2Ms) plays a pivotal role in AA stabilization. We investigated the effects of M2M administration in an apolipoprotein E-deficient (apoE^-/-) mouse model in which AA was induced by angiotensin II (ATII) infusion. Mice received intraperitoneal administration of 1 million M2Ms 4 weeks after ATII infusion. Compared with a control group that was administered saline, the M2M group exhibited reduced AA expansion; decreased expression levels of interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1); and a lower M1M/M2M ratio. Moreover, the M2M group exhibited upregulation of anti-inflammatory factors, including IL-4 and IL-10. PKH26-labeled M2Ms accounted for 6.5% of cells in the aneurysmal site and co-expressed CD206. Taken together, intraperitoneal administration of M2Ms inhibited AA expansion by reducing the inflammatory reaction via regulating the M1M/M2M ratio. This study shows that M2M administration might be useful for the treatment of AA.

PL02.4.A International validation study of an EORTC instrument measuring instrumental activities of daily living (IADL) in patients with brain tumours: EORTC IADL-BN32

Background

Brain tumour patients often have neurocognitive deficits which can result in problems with activities in daily living that are cognitively complex. Currently, no valid and reliable brain tumour-specific instrument to measure these instrumental activities of daily living (IADL) is available, but such an instrument is being developed. This study aimed to validate the EORTC IADL-BN32 questionnaire, comprising five multi-item and two single item scales, in a large set of international brain tumour patients.

Material and Methods

This international study was conducted in 10 countries worldwide. Primary and metastatic brain tumour patients and their proxies were requested to complete the EORTC IADL-BN32 and a subjective cognitive questionnaire (MOS COG-R) at multiple time points. Several psychometric properties were evaluated with baseline data, including the structural validity (bi-factor confirmatory factor analysis [CFA]), reliability (internal consistency), construct validity (known groups comparisons) and patient-proxy congruency (intra-class correlation coefficients [ICC], Spearman's correlation).

Results

At baseline, 326 patients ( 30% low-grade glioma, 37% high-grade glioma (HGG) and 33% brain metastases) and 311 proxies completed the EORTC IADL-BN32. The bi-factor CFA was found to have a satisfactory model fit (CFI=0.92 and TLI=0.90), and other parameters indicated a good fit (RMSEA=0.08 and SRMR=0.05), thereby validating the preliminary scale structure, but also an IADL sum score. The multi-item scales showed good (0.9&gt;α≥0.8) to excellent (α≥0.9) internal consistency (range α=0.86-0.97). Known groups comparisons analyses regarding patient’s cognitive status (indications vs. no cognitive impairment), subjective cognitive complaints (MOS COG-R ≤30 vs. &gt;30), basic ADL (Barthel Index &lt;100 vs. 100) and performance status (KPS &lt;70 vs. ≥70) showed significant differences on all IADL outcome measures in line with a priori defined hypotheses. On a group level, patient and proxy ratings had moderate to strong correlations, however, proxies tended to report more problems on all scales. The ICCs showed moderate to good congruency between patients and proxies (range ICC: 0.63-0.81).

Conclusion

The evaluated psychometric properties support the current scale structure of the EORTC IADL-BN32. Additional psychometric properties with longitudinal data are needed, such as test-retest reliability and responsiveness, to further validate the EORTC-IADL BN32 questionnaire.

Higher F-wave frequency associates with poor procedural success rate after Maze procedure

OBJECTIVES

Persistent atrial fibrillation (AF) causes atrial remodeling, which causes myocardial fibrosis and micro-reentry. Fibrosis may reduce wave voltage and micro-reentry may enhance the dominant frequency (DF) of the F-wave. We investigated whether the DF predicts procedural success by the Maze procedure.

METHODS

In 138 consecutive patients who underwent mitral valve surgery and a modified Cox-Maze III procedure for persistent AF in Nagoya University in 2002-2018, 96 (70%) were successfully cardioverted (group S); 42 had persistent or relapsed AF after surgery (group F). Patient data were compared between the groups. Cut-off values were determined by an ROC analysis and predictors of procedural success were evaluated. The DF was obtained from the F-wave of V1 by a high-speed Fourier analysis using the CEPAS software program.

RESULTS

Group F showed a significantly larger LA diameter, better LVEF, lower F-wave voltage, higher DF, and longer duration of AF. The cut-off values were as follows: LA diameter, 56 mm; EF, 64.5%; F-wave voltage, 0.13 mV; DF, 7.3 Hz; and duration of AF, 44 months. Each factor showed statistical significance in a univariate analysis; DF lost significance in the multivariate analysis. The higher (DF ≥ 7.3 Hz) and lower voltage group (≤ 0.13 mV) showed the worst procedural success rate (36%), while the lower DF (< 7.3 Hz) and higher voltage group (> 0.13 mV) showed a good rate (86%).

CONCLUSIONS

The DF of the F-wave is a useful predictor of procedural success after the Maze procedure in addition to the voltage of F-wave.

Multiple giant coronary artery aneurysms with extended coronary ectasia emerging 12 years after previous coronary artery bypass grafting

A 73-year-old man presented with multiple giant coronary artery aneurysms. Twelve years prior to the presentation, he had undergone coronary artery bypass grafting. At that time, he exhibited small aneurysms (16 mm diameter) in the right coronary artery and a single aneurysm (10 mm diameter) in the left circumflex artery. During follow-up, the aneurysms gradually increased in size (to 45 and 30 mm, respectively, at 12 years after surgery). We resected all of the aneurysms and performed coronary artery bypass grafting of the left circumflex artery through re-sternotomy.

Alternative therapeutic strategy for existing aortic aneurysms using mesenchymal stem cell-derived exosomes

BACKGROUND

Several studies demonstrated the therapeutic potential of mesenchymal stem cell-derived exosomes (MSC-exs) based on their anti-inflammatory properties. The objective was to determine the therapeutic effects of MSC-exs on aortic aneurysms (AAs) caused by atherosclerosis.

RESEARCH DESIGN AND METHODS

Apolipoprotein E knockout mice with AAs induced by angiotensin II were injected with MSC-exs or saline as a control. The change in the diameter of the aorta was measured. The expression of AA-related proteins and the histology of the aortic wall were investigated at 1 week after treatment. MicroRNA and protein profiles of MSC-exs were examined.

RESULTS

MSC-exs significantly attenuated AA progression (2.04 ± 0.20 mm in the saline group and 1.34 ± 0.13 mm in the MSC-ex group, P = 0.004). In the MSC-ex group, the expression of IL-1β, TNF-α and MCP-1 decreased, and expression of IGF-1 and TIMP-2 increased. MSC-ex induced the M2 phenotype in macrophages and suppressed the destruction of the elastic lamellae in the aortic wall. MSC-exs contained high levels of 10 microRNAs that inhibit AA formation and 13 proteins that inhibit inflammation and promote extracellular matrix synthesis.

CONCLUSIONS

MSC-ex might be a novel alternative therapeutic tool for treatment of existing AAs.

Sudden circulatory collapse caused by mechanical obstruction of the left main coronary trunk with infective endocarditis vegetation: a case report

Background

Acute coronary syndrome (ACS) caused by mechanical obstruction of the coronary artery with a vegetation is extremely rare but associated with high mortality. The optimal management strategy of this condition remains controversial because of its scarcity. We experienced a case of sudden circulatory collapse due to mechanical occlusion of the left main coronary trunk with a vegetation.

Case presentation

A 68-year-old woman with aortic and mitral valve infective endocarditis suffered sudden dyspnea followed by heart arrest while awaiting surgery. Despite treatment with adequate antibiotic therapy, she had had multiple embolic infarctions and ruptured infectious cerebral aneurysms. We conducted transcatheter arterial embolization of the aneurysm and postponed the cardiac surgery due to residual aneurysmal blood flow. She suffered sudden cardiac arrest, and extracorporeal membrane oxygenation was applied after cardiopulmonary resuscitation. An echocardiogram revealed diffuse severe hypokinesis, and emergency coronary angiography was performed under suspicion of ACS. It revealed obstruction of the left main coronary trunk by a vegetation. Emergent cardiac surgery was performed. A vegetation had occluded the left coronary orifice. Aortic and mitral valve replacement with coronary artery bypass to the left antero-descending branch was performed. Regarding her cardiac function, she still required extracorporeal membrane oxygenation after surgery. She passed away 19 days after surgery due to multiple organ failure.

Conclusions

ACS caused by mechanical obstruction of the coronary artery with a vegetation is rare but associated with high mortality. When circulatory collapse acutely occurs in patients with aortic valve infective endocarditis, we should suspect acute coronary artery obstruction. Urgent coronary angiography is mandatory to rescue the patient while preparing for emergency surgery.

OS05.4.A Do neurocognitive deficits explain the differences between brain tumour patients and their proxies assessing the patient’s I-ADL?

BACKGROUND

Neurocognitive deficits are common among brain tumour patients, and may impact on patient awareness of deficits in instrumental activities in daily life (IADL). This study aimed to examine differences between patient-reported and proxy-reported assessments of the patient’s performance of IADL, and whether the level of (dis)agreement is associated with neurocognitive deficits.

MATERIAL AND METHODS

A phase III EORTC questionnaire measuring IADL in brain tumour patients (EORTC IADL-BN32) and six neurocognitive test measures were administered as part of a larger multicentre international study designed to develop a brain tumour specific IADL questionnaire. Bland-Altman plots and Mann-Whitney U tests were used to evaluated patient- and proxy-reported IADL on a group level. Subsequently, Mann-Whitney U tests were performed to compare patient-proxy difference scores (patient IADL score - their proxy IADL score) between patients who were considered clearly neurocognitively impaired (≥2 neurocognitive test measures; ≤2.0 SD below healthy controls) and patients who were not. Furthermore, multinomial logistic regression analyses were performed to examined which sociodemgraphic, clinical, and particularly neurocognitive variables were independently associated with patients and proxies differing in their evaluation of patient’s IADL.

RESULTS

Patients (N=81) and proxies (N=81), on group level, did not significantly differ on either the IADL individual item or scale scores. However, significant differences were found on patient-proxy difference scores between patients who were (N=37) and were not (N=44) considered clearly neurocognitively impaired for 10/32 individual items and one of the scales (i.e. Scale 4: Administrative tasks), all showing that the proxies of clearly neurocognitively impaired patients reported more problems relative to the patients themselves, compared to proxies of patients not clearly neurocognitively impaired. Furthermore, for each scale, a neurocognitive variable, either impaired information processing speed, cognitive flexibility, verbal fluency or the number of neurocognitive test measures impaired, was found to be independently associated with proxies reporting more problems. For 4/5 scales, a clinical variable was additionally independently associated with proxies reporting more problems. Only one variable was independently associated with patient reporting more problems, namely being in active treatment was found to be associated with patients reporting more problems on Scale 4: Administrative tasks.

CONCLUSION

Results imply a consistent trend of clearly neurocognitively impaired patients underreporting problems with IADL compared to their proxies. It would therefore be advised to administer both the patient- and proxy-version of the EORTC IADL-BN32, particularly if neurocognitive deficits are presumed.

Fabrication of Cationic Poly(vinyl alcohol) Films Cross-Linked Using Copolymers Containing Quaternary Ammonium Cations, Benzoxaborole, and Carboxy Groups

Water-insoluble cationic poly(vinyl alcohol) (PVA) films were fabricated using a mixed aqueous solution of PVA and poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC)-co-methacrylic acid (MAAc)-co-5-methacrylamido-1,2-benzoxaborole (MAAmBO)) copolymer (3D). The surface of the PVA film is typically negatively charged, and simple fabrication methods for water-insoluble PVA films with cationic surface charges are required to expand their application fields. METAC, which has a permanent positive charge owing to the presence of a quaternary ammonium cation, was selected as the cationic unit. The MAAc and MAAmBO units were used as two types of cross-linking structures for the thermal cross-linking of the hydroxy and carboxy groups of the MAAc unit (covalent bonding) as well as the diol and benzoxaborole groups of the MAAmBO unit (dynamic covalent bonding). The films were thermally cross-linked at 135 °C for 4 h without the addition of materials. After immersion in surplus water at 80 °C for 3 h, the cross-linked PVA/3D films retained almost 100% of their weights. The ζ-potential of the water-insoluble PVA/3D film was 9.4 ± 0.8 mV. The PVA/3D film was strongly dyed using anionic acid red 1 (AR1) because of its positively charged surface. Interestingly, it could also be slightly dyed using cationic methylene blue (MB) and became transparent (original state) after immersion in water for 2 days. These results suggested that positive and negative charges coexisted in the PVA/3D film, and the surface properties were positively inclined. Moreover, the degree of hemolysis of the PVA/3D films was similar to that of the negative control, which showed high blood compatibility. To our knowledge, this is the first report on the fabrication of water-insoluble cationic PVA films using two types of cross-linking structures containing carboxy and benzoxaborole groups. The cross-linked PVA films were analyzed using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and contact angle (CA) and ζ-potential measurement, as well as by determining the mechanical properties, adsorption of charged molecules, and biocompatibility. These readily fabricated water-insoluble PVA films with positive charges can show potential applications in sensors, adsorption systems, and antimicrobial materials.

Impact of tumor growth rate during preceding treatment on tumor response to nivolumab or irinotecan in advanced gastric cancer

Background

Nivolumab (NIVO) and irinotecan (IRI) are standard treatments for refractory advanced gastric cancer (AGC); however, it is unclear which drug should be administered first or in which cases. The tumor growth rate (TGR) during preceding treatment is reported to be associated with tumor response in metastatic colorectal cancer patients treated with regorafenib or trifluridine/tipiracil, suggesting that TGR may be useful for drug selection. Therefore, we evaluated the association between TGR during preceding treatment and the tumor response to NIVO or IRI.

Patients and methods

We retrospectively evaluated consecutive AGC patients treated with NIVO or IRI and divided them into slow-growing (Slow) and rapid-growing (Rapid) groups according to TGR and the presence or absence of new lesions (NL+/NL−, respectively) during preceding treatment (Slow group: NL− with low TGR <0.30%/day; Rapid group: NL+ or high TGR ≥0.30%/day).

Results

A total of 117 patients (Rapid/Slow groups, 72/45; NIVO/IRI groups, 32/85) were eligible. All baseline characteristics except peritoneal metastases were similar between patients treated with NIVO and IRI in the Rapid and Slow groups. The response rate was significantly higher in patients treated with NIVO compared with IRI [31%/3%; odds ratio (OR), 13.8; P = 0.01; adjusted OR, 52; P = 0.002] in the Slow group, but there was no difference between patients treated with NIVO and IRI (5%/8%; OR, 0.68; P = 0.73; adjusted OR, 0.94; P = 0.96) in the Rapid group. Disease control rate, progression-free survival, and overall survival were consistent with these results.

Conclusions

Our findings suggest that NIVO treatment is a more favorable option for patients with slow-growing tumors, and NIVO and IRI are similarly recommended for patients with rapid-growing tumors in refractory AGC. TGR and NL emergence during preceding treatment may be helpful for drug selection and warrant further investigation.

•

NIVO and IRI are standard treatments for refractory AGC, although it is unclear which should be administered first.

•

TGR may be useful for drug selection, therefore we evaluated the association between TGR and the tumor response to NIVO or IRI.

•

In the Slow group, the response rate (RR) was significantly higher in patients treated with NIVO compared with IRI.

•

In the Rapid group, there was no significant difference in RR between the NIVO and IRI groups.

•

TGR and NL emergence during preceding treatment may be useful for drug selection.

Predictors of failure of mitral valve repair using artificial chordae

BACKGROUND

We investigate predictors of failure of mitral valve repair (MVr) using expanded polytetrafluoroethylene (ePTFE) and durability of them in the long-term period in single institution.

METHODS

Four hundred twenty-one consecutive patients with primary mitral valve disease underwent MVr using artificial chordae (group A: n=304) and suture repair (group S: n=117) at our institution from January 2002 to April 2020. A comparison study was performed to examine the long-term outcomes, re-operation rate and risk factors for re-operation.

RESULTS

One hospital death and 5 late deaths occurred in group S, and 20 late deaths occurred in group A. The re-operation rates were similar [group A; n=8 (2.6%), group S; n=6 (5%)]. The major cause of re-operation was ruptured ePTFE (CV-4: n=1, CV-5: n=6) in group A, and suture rupture in group S. Re-operation was performed after a median period of 88 months for ruptured ePTFE, and 26 months for group S. The rate of ePTFE rupture was 1.8% with CV5 and 0.2% with CV4. Risk factors for re-operation included post-operative arrhythmia, urgent operation, no annular-ring, ruptured ePTFE and suture rupture. The rates of freedom from re-operation and actuarial mitral valve survival rates at 5, 10, and 15 years were 99%, 95%, and 93% and 96%, 91%, and 89%, respectively, in group A, and 96%, 91%, and 91% and95%, 94%, and 94% in group S.

CONCLUSIONS

The long-term surgical outcomes of MVr using both techniques were feasible. Over the long-term, the ePTFE rupture rate of CV-5 was higher than that of CV-4.

Long term efficacy and fate of a right ventricular outflow tract replacement using an elastomeric cardiac patch consisting of caprolactone and D,L-lactide copolymers

For decades, researchers have investigated the ideal material for clinical use in the cardiovascular field. Several substitute materials are used clinically, but each has drawbacks. Recently we developed biodegradable and elastic poly(ε-caprolactone-co-D,L-lactide) (P(CL-DLLA)) copolymers by adjusting the CL/DLLA composition, and evaluated the long-term efficacy and outcomes of these copolymers when used for right ventricular outflow tract (RVOT) replacement. This P(CL-DLLA) material was processed into a circular patch and used to replace a surgical defect in the RVOT of adult rats. Control rats were implanted with expanded polytetrafluoroethylene (ePTFE). Histologic evaluation was performed at 8, 24, and 48 weeks post-surgery. All animals survived the surgery with no aneurysm formation or thrombus. In all periods, ePTFE demonstrated fibrous tissue. In contrast, at 8 weeks P(CL-DLLA) showed infiltration of macrophages and fibroblast-like cells into the remaining material. At 24 weeks, P(CL-DLLA) was absorbed completely, and muscle-like tissue was present with positive staining for α-sarcomeric actinin and cardiac troponin T (cTnT). At 48 weeks, the cTnT-positive area had increased. The biodegradable and elastic P(CL-DLLA) induced cardiac regeneration throughout the 48-week study period. Future application of this material as a cardiovascular scaffold seems promising. STATEMENT OF SIGNIFICANCE: Biomaterials for reconstruction of tissue deficiencies in cardiovascular surgery require having suitable mechanical properties for cardiac tissue and biodegradation resulting in native tissue growth. Several biodegradable polymers such as poly-ε-caprolactone (PCL) and polylactic acid (PLA) have excellent biocompatibility and already been widely used clinically. In general, PCL and PLA are quite mechanically rigid. Meanwhile, significant elasticity is required in the high-pressure environment of the heart while the material is being replaced by new tissue. The present study provides a novel four-armed crosslinked poly(ε-caprolactone-co-D,L-lactide) (i.e., P(CL-DLLA)) material for cardiac patch, which was demonstrated properties including tissue-compatible, super-elastic nature, that made it suitable for long-term, in vivo RVOT repair. This super-elastic biomaterial could be useful for reconstruction of various muscular tissues deficiencies.

Therapeutic effect of allogeneic bone marrow-derived mesenchymal stromal cells on aortic aneurysms

We previously reported the effectiveness of autologous mesenchymal stromal cells (MSCs) for the treatment of aortic aneurysm (AA), mediated mainly by these cells' anti-inflammatory properties. In this study, we investigate whether the therapeutic effects of allogeneic MSCs on AA are the same as those of autologous MSCs. To examine the immune response to allogeneic MSCs, C57BL/6 lymphocytes were co-cultured with BALB/c MSCs for 5 days in vitro. Apolipoprotein E-deficient C57BL/6 mice with AA induced by angiotensin II were randomly divided into three groups defined by the following intravenous injections: (i) 0.2 ml of saline (n = 10, group S) as a control, (ii) 1 × 106 autologous MSCs (isolated from C57BL/6, n = 10, group Au) and (iii) 1 × 106 allogeneic MSCs (isolated from BALB/c, n = 10, group Al). Two weeks after injection, aortic diameters were measured, along with enzymatic activities of MMP-2 and MMP-9 and cytokine concentrations in AAs. Neither allogenic (BALB/c) MSCs nor autologous (C57BL/6) MSCs accelerated the proliferation of lymphocytes obtained from C57BL/6. Compared with group S, groups Au and Al had significantly shorter aortic diameters (group S vs Au vs Al; 2.29 vs 1.40 vs 1.36 mm, respectively, p < 0.01), reduced MMP-2 and MMP-9 activities, downregulated IL-6 and MCP-1 and upregulated expression of IGF-1 and TIMP-2. There were no differences in these results between groups Au and Al. Thus, our study suggests that treatment with allogeneic MSCs improves chronic inflammation and reduced aortic dilatation. These effects were equivalent to those of autologous MSCs in established mouse models of AA.

Performance of a Biodegradable Composite with Hydroxyapatite as a Scaffold in Pulp Tissue Repair

Vital pulp therapy is an important endodontic treatment. Strategies using growth factors and biological molecules are effective in developing pulp capping materials based on wound healing by the dentin-pulp complex. Our group developed biodegradable viscoelastic polymer materials for tissue-engineered medical devices. The polymer contents help overcome the poor fracture toughness of hydroxyapatite (HAp)-facilitated osteogenic differentiation of pulp cells. However, the composition of this novel polymer remained unclear. This study evaluated a novel polymer composite, P(CL-co-DLLA) and HAp, as a direct pulp capping carrier for biological molecules. The biocompatibility of the novel polymer composite was evaluated by determining the cytotoxicity and proliferation of human dental stem cells in vitro. The novel polymer composite with BMP-2, which reportedly induced tertiary dentin, was tested as a direct pulp capping material in a rat model. Cytotoxicity and proliferation assays revealed that the biocompatibility of the novel polymer composite was similar to that of the control. The novel polymer composite with BMP-2-induced tertiary dentin, similar to hydraulic calcium-silicate cement, in the direct pulp capping model. The BMP-2 composite upregulated wound healing-related gene expression compared to the novel polymer composite alone. Therefore, we suggest that novel polymer composites could be effective carriers for pulp capping.

Cardiac fiber tracking on super high-resolution CT images: a comparative study

Purpose: High-resolution cardiac imaging and fiber analysis methods are required to understand cardiac anatomy. Although refraction-contrast x-ray CT (RCT) has high soft tissue contrast, it cannot be commonly used because it requires a synchrotron system. Microfocus x-ray CT (μCT) is another commercially available imaging modality.

Approach: We evaluate the usefulness of μCT for analyzing fibers by quantitatively and objectively comparing the results with RCT. To do so, we scanned a rabbit heart by both modalities with our original protocol of prepared materials and compared their image-based analysis results, including fiber orientation estimation and fiber tracking.

Results: Fiber orientations estimated by two modalities were closely resembled under the correlation coefficient of 0.63. Tracked fibers from both modalities matched well the anatomical knowledge that fiber orientations are different inside and outside of the left ventricle. However, the μCT volume caused incorrect tracking around the boundaries caused by stitching scanning.

Conclusions: Our experimental results demonstrated that μCT scanning can be used for cardiac fiber analysis, although further investigation is required in the differences of fiber analysis results on RCT and μCT.

P3112The oral administration of colchicine prevents the progression of aortic aneurysm

Objective

The pathogenesis of aortic aneurysm (AA) is characterized by the chronic inflammation of the aortic wall with the accumulation of macrophages and the degradation of the extracellular matrix (ECM) including elastin. Colchicine (COL) is an alkaloid derived from the plant Lily family Colchicum autumnale, and it is known for anti-inflammatory effects. Plant extracts containing COL have been used in the treatment of gout from ancient period. Currently, pseudogout, familial Mediterranean fever, Behçet's disease and pericarditis are also treated by COL. Furthermore, recent evidence suggests the use of COL for secondary prevention of cardiovascular disease, and the phase 3 clinical trial for it has begun. The objective of this study is to investigate whether COL could prevent the progression of aortic aneurysms.

Methods

In vitro: Macrophages (J774A.1 cell line) stimulated TNF-α 24 hours before and smooth muscle cell (SMC) were cultured with 10 ng/mL COL, and the gene expression of inflammatory cytokines involved in the AA formation was measured 24 hours later.

In vivo: Male apolipoprotein E-deficient mice (30–35 weeks of age) were infused with angiotensin II for 28 days. COL (20 μg/kg/d) or saline (NS, as a control) was administered orally to the mice every day (COL group, n=8; NS group, n=8). Aortic diameter was measured by echography every week and all mice were sacrificed and their thoracoabdominal aorta was harvested at the last day of the administration period and elastin content, MMP activitis, and levels of inflammatory cytokines involved in the AA formation were measured.

Results

In vitro: The gene expression of IL-1β, TNF-α, MCP-1, NF-κB, MMP-9 in the macrophages was significantly decreased in the COL group. The gene expression of Lox, TIMP-2 in the SMC were significantly increased in COL group.

In vivo: Aortic diameter measured by echography every week was significantly suppressed in the COL group (2.25 vs 2.81 mm, p<0.05). The incidence of AA was decreased in the COL group (62.5% vs 100%). COL significantly suppressed the degeneration of aortic elastin in EVG staining (p<0.05). There is no significant difference in the enzyme activities of MMP-2 and MMP-9 between COL and NS groups, but IL-1β (54.4 vs 81.4, p<0.05), TNF-α (31.0 vs 60.6, p<0.05), MCP-1 (258.2 vs 411.2, p<0.05), NLRP3 inflammasome (7.1 vs 8.6, p<0.05), NE (1.5 vs 2.4, p<0.05), MPO (44.9 vs 48.1, p<0.05) were decreased in the COL group.

Discussion

In AA model mice, COL seems to suppress the progression of AA by anti-infammation and preservation of the ECM structure through the inhibition of NLRP3 inflammasome. That NLRP3 inflammasome activation leads to the progression of AA in AA model mice was previously reported and this supports out results.

Methods and Results (in vivo)

Conclusions

This results suggest that the oral administration of COL prevents the progression of AA in AA model mice and it is expected as a novel therapeutic agent for AA.

Acknowledgement/Funding

JSPS KAKENHI Grant

A Floating Stitch on the Anterior Mitral Leaflet Can Eliminate Systolic Anterior Motion in Hypertrophic Obstructive Cardiomyopathy

Reducing the systolic anterior motion is a key way of resolving left ventricular outflow tract obstruction in surgery for hypertrophic obstructive cardiomyopathy. We developed a new technique using a floating stitch on the anterior mitral leaflet (AML). It is applied just to the middle of the tip of the AML and fixed to the annuloplasty ring at the middle of the posterior annulus. The AML is prevented from touching the interventricular septum and systolic anterior motion can theoretically be solved.

Hydrogen water alleviates obliterative airway disease in mice

OBJECTIVE

Bronchiolitis obliterans syndrome arising from chronic airway inflammation is a leading cause of death following lung transplantation. Several studies have suggested that inhaled hydrogen can protect lung grafts from ischemia-reperfusion injury via anti-inflammatory and -oxidative mechanisms. We investigated whether molecular hydrogen-saturated water can preserve lung allograft function in a heterotopic tracheal allograft mouse model of obliterative airway disease METHODS: Obliterative airway disease was induced by heterotopically transplanting tracheal allografts from BALB/c donor mice into C57BL/6 recipient mice, which were subsequently administered hydrogen water (10 ppm) or tap water (control group) (n = 6 each) daily without any immunosuppressive treatment. Histological and immunohistochemical analyses were performed on days 7, 14, and 21.

RESULTS

Hydrogen water decreased airway occlusion on day 14. No significant histological differences were observed on days 7 or 21. The cluster of differentiation 4/cluster of differentiation 3 ratio in tracheal allografts on day 14 was higher in the hydrogen water group than in control mice. Enzyme-linked immunosorbent assay performed on day 7 revealed that hydrogen water reduced the level of the pro-inflammatory cytokine interleukin-6 and increased that of forkhead box P3 transcription factor, suggesting an enhancement of regulatory T cell activity.

CONCLUSIONS

Hydrogen water suppressed the development of mid-term obliterative airway disease in a mouse tracheal allograft model via anti-oxidant and -inflammatory mechanisms and through the activation of Tregs. Thus, hydrogen water is a potential treatment strategy for BOS that can improve the outcome of lung transplant patients.

Intratumoural immune cell landscape in germinoma reveals multipotent lineages and exhibits prognostic significance

AIMS

Alterations in microenvironments are a hallmark of cancer, and these alterations in germinomas are of particular significance. Germinoma, the most common subtype of central nervous system germ cell tumours, often exhibits massive immune cell infiltration intermingled with tumour cells. The role of these immune cells in germinoma, however, remains unknown.

METHODS

We investigated the cellular constituents of immune microenvironments and their clinical impacts on prognosis in 100 germinoma cases.

RESULTS

Patients with germinomas lower in tumour cell content (i.e. higher immune cell infiltration) had a significantly longer progression-free survival time than those with higher tumour cell contents (P = 0.03). Transcriptome analyses and RNA in-situ hybridization indicated that infiltrating immune cells comprised a wide variety of cell types, including lymphocytes and myelocyte-lineage cells. High expression of CD4 was significantly associated with good prognosis, whereas elevated nitric oxide synthase 2 was associated with poor prognosis. PD1 (PDCD1) was expressed by immune cells present in most germinomas (93.8%), and PD-L1 (CD274) expression was found in tumour cells in the majority of germinomas examined (73.5%).

CONCLUSIONS

The collective data strongly suggest that infiltrating immune cells play an important role in predicting treatment response. Further investigation should lead to additional categorization of germinoma to safely reduce treatment intensity depending on tumour/immune cell balance and to develop possible future immunotherapies.

Single-center Experience of Living-donor Liver Transplantation in Patients Receiving Maintenance Renal Replacement Therapy

BACKGROUND

For most patients with liver failure receiving maintenance renal replacement therapy (RRT), treatment with living-donor liver transplantation (LDLT) alone is indicated in Japan.

MATERIAL AND METHODS

We retrospectively reviewed patients who underwent LDLT while receiving RRT in our hospital.

RESULTS

Three of the 5 patients who underwent LDLT while on RRT died during the first year after transplantation.

CONCLUSIONS

The indications for liver transplantation in patients on RRT require careful examination.

Neurologic Deficit After Aortic Arch Replacement: The Influence of the Aortic Atherosclerosis

BACKGROUND

Postoperative neurologic deficits are associated with severe morbidity in aortic arch replacement.

METHODS

A group of 198 consecutive patients undergoing isolated total aortic arch replacement with the use of antegrade cerebral perfusion were analyzed for the risk factors for predicting neurologic deficit. With the use of computed tomography, atherothrombotic lesions (defined as extensive intimal thickening exceeding 4 mm) were identified in the proximal aorta (the ascending aorta or aortic arch) in 26.2% of cases and in the distal aorta in 34.9% of cases.

RESULTS

Permanent neurologic deficits occurred in 11.1% (including non-disabling stroke confirmed by imaging) and transient neurologic deficits in 8.1% of patients. A univariate analysis identified proximal atherothrombotic aorta (p = 0.0057), distal atherothrombotic aorta (p = 0.032), and retrograde systemic perfusion from the femoral artery in the presence of distal atherothrombotic aorta (p = 0.0022) as risk factors for neurologic deficits. A multivariate logistic regression analysis identified atherothrombotic proximal aorta (odds ratio 2.4, p = 0.033) as the independent risk factor. The presence of carotid stenosis did not affect the rate of neurologic deficit. Intracranial hemorrhagic lesions were found in 23% of permanent neurologic deficit cases.

CONCLUSIONS

Atherothrombotic lesions found by objectively graded computed tomography were predictors of neurologic deficit. Retrograde perfusion in the presence of a distal atherothrombotic lesion should be avoided whenever possible. Strategies based on the full assessment of the whole aortic morphologic characteristics appear to be mandatory. Anticoagulation therapy should be performed carefully to avoid intracranial hemorrhagic changes.

Pan-Asian adapted ESMO Clinical Practice Guidelines for the management of patients with metastatic oesophageal cancer: a JSMO-ESMO initiative endorsed by CSCO, KSMO, MOS, SSO and TOS

The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of oesophageal cancer was published in 2016, and covered the management and treatment of local/locoregional disease, limited disease, locally advanced disease and the management of advanced/metastatic disease. At the ESMO Asia Meeting in November 2017 it was decided by both ESMO and the Japanese Society of Medical Oncology (JSMO) to convene a special guidelines meeting immediately after the JSMO Annual Meeting in 2018. The aim was to adapt the ESMO 2016 guidelines to take into account the ethnic differences associated with the treatment of metastatic oesophageal cancer in Asian patients. These guidelines represent the consensus opinions reached by experts in the treatment of patients with metastatic oesophageal cancer representing the oncological societies of Japan (JSMO), China (CSCO), Korea (KSMO), Malaysia (MOS), Singapore (SSO) and Taiwan (TOS). The voting was based on scientific evidence, and was independent of both the current treatment practices and the drug availability and reimbursement situations in the individual participating Asian countries.

Pan-Asian adapted ESMO Clinical Practice Guidelines for the management of patients with metastatic gastric cancer: a JSMO-ESMO initiative endorsed by CSCO, KSMO, MOS, SSO and TOS

The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of gastric cancer (GC) was published in 2016, and covered the management and treatment of local, locoregional, locally advanced and metastatic disease. At the ESMO Asia Meeting in November 2017 it was decided by both ESMO and The Japanese Society of Medical Oncology (JSMO) to convene a special guidelines meeting immediately after the JSMO Annual Meeting in 2018. The aim was to adapt the ESMO 2016 guidelines to take into account the ethnic differences associated with the treatment of metastatic GC in Asian patients. These guidelines represent the consensus opinions reached by experts in the treatment of patients with metastatic GC representing the oncological societies of Japan (JSMO), China (CSCO), Korea (KSMO), Malaysia (MOS), Singapore (SSO) and Taiwan (TOS). The voting was based on scientific evidence and was independent of both the current treatment practices and the drug availability and reimbursement situations in the individual participating Asian countries.

Strategy of Cardiovascular Surgery for Patients With Dementia as Evaluated by Mini-Mental State Examination

BACKGROUND

The strategy for cardiovascular surgery in dementia patients is controversial, so we aimed to investigate whether preoperative dementia and its severity might affect the outcomes of cardiovascular surgery by evaluating with the Mini-Mental State Examination (MMSE). Methods and Results: The study group comprised 490 patients undergoing cardiovascular surgery. Their preoperative cognitive status was evaluated using the MMSE, and analysis was performed to compare the patients with MMSE score <24 (dementia group, n=51) or MMSE score 24-30 (non-dementia group, n=439). Furthermore, the effect of the severity of dementia was analyzed with a cut-off MMSE score of 19/20. Risk factors for surgical outcomes were explored using multivariate logistic regression analysis. Hospital mortality was 11.8% in the dementia group and 2.1% in the non-dementia group (P=0.002). Regarding the postoperative morbidities, the incidence of cerebrovascular disorder (P=0.001), pneumonia (P=0.039), delirium (P=0.004), and infection (P=0.006) was more frequent in dementia group. Among the patients with MMSE <20, hospital mortality was as high as 25%, and the rate of delirium was 58%. Multivariate logistic regression analysis revealed that MMSE score <24 (P=0.003), lower serum albumin (P=0.023) and aortic surgery (P=0.036) were independent risk factors for hospital death.

CONCLUSIONS

Preoperative dementia affects the outcomes of cardiovascular surgery with regard to hospital death and delirium. The surgical indication for patients with MMSE <20 might be difficult, but surgery with an appropriate strategy should be considered for patients with MMSE <24.

＜Editors' Choice＞ Effect of postoperative doxorubicin administration on ischemic wound healing

Some patients undergo postoperative chemotherapy despite showing impaired wound healing after a major surgery. We speculated that postoperative chemotherapy further delays wound healing in these patients. This study aimed to compare the effects of doxorubicin (DXR) in ischemic skin flap and normal incisional wound models after surgery. A 2-cm incisional wound was made in group 1 rats, and saline was injected intravenously, following surgery on the same day. Incisional wound was made in group 2–5 rats, and 8 mg/kg DXR was injected intravenously, following surgery on the same day and after 7, 14, and 21 days respectively. H-shaped double flaps were made in group 6 rats, and saline was injected intravenously, following surgery on the same day. Flaps were made in group 7–10 rats, and 8 mg/kg DXR was injected intravenously, following surgery on the same day and after 7, 14, and 21 days respectively. On days 7, 14, 21, and 28 after surgery, the suture wounds were removed, tensile wound strengths were measured, and tissue samples were collected for histopathological evaluation. The tensile strength was significantly lower in the DXR-treated groups than in the control groups for both ischemic skin flaps and incision wounds. Additionally, the cross effect between DXR and ischemia was not significant. On pathological examination, DXR showed atrophic skin changes and degeneration of skin appendages on days 14–21 after the surgery in both the models. DXR decreased the wound tensile strength and caused an atrophic change in the ischemic wound.

Evaluation of the Bactericidal and Fungicidal Activities of Poly([2-(methacryloyloxy)ethyl]trimethyl Ammonium Chloride)(Poly (METAC))-Based Materials

Poly([2-(methacryloyloxy)ethyl]trimethyl ammonium chloride) (METAC) and the gels were prepared and evaluated for their bactericidal and fungicidal activities. The antimicrobial properties of poly(METAC) were tested against Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), Saccharomyces cerevisiae (Sa. cerevisiae), methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (P. aeruginosa), and Candida albicans (C. albicans). Moreover, the structural forms of the linear and cross-linked poly(METAC) were investigated for their influences on bacterial aggregation, precipitation, and cell-death. To our knowledge, this is the first report on the comparison of the antimicrobial properties of poly(METAC) and poly(METAC)-gels. The bactericidal and fungicidal activities were evaluated by determining minimum inhibitory concentrations (MICs), UV⁻Vis spectroscopy, and fluorescence and confocal microscopies. The MICs were found to be 123 (MSSA), 123 (MRSA), 123 (P. aeruginosa), 370 (E. coli), 123 (B. subtilis), 370 (C. albicans), and 370 μg/mL (Sa. cerevisiae), as determined by broth dilution, and 370 (MSSA), 370 (MRSA), 370 (P. aeruginosa), 3300 (E. coli), 370 (B. subtilis), 1100 (C. albicans), and >10,000 μg/mL (Sa. cerevisiae), as determined by paper disc diffusion (on solid medium). The poly(METAC)-gels achieved rapid adsorption/precipitation of bacteria via the cationic surface charge. Thus, these poly(METAC)-based polymers can potentially be used as antibacterial materials.