Operando High-Valence Cr-Modified NiFe Hydroxides for Water Oxidation.

High-valence metal-doped multimetal (oxy)hydroxides outperform noble metal electrocatalysts for the oxygen evolution reaction (OER) owing to the modified energetics between 3d metals and high-valence dopants. However, the rational design of sufficient and subtle modulators is still challenging. With a multimetal layered double hydroxide (LDH) as the OER catalyst, this study introduces a series of operando high-valence dopants (Cr, Ru, Ce, and V), which can restrict the 3+ valence states in the LDH template to prevent phase separation and operando transfer to the >3+ valence states for sufficient electronic interaction during the OER process. Through density functional theory simulations, ultrathin Cr-doped NiFe (NiFeCr) LDH is synthesized with strong electronic interaction between Cr dopants and NiFe bimetallic sites, evidenced by X-ray absorption spectroscopy. The resulting NiFeCr-LDH catalyzes the OER with ultralow overpotentials of 189 and 284 mV, obtaining current densities of 10 and 1000 mA cm-2 , respectively. Further, a NiFeCr-LDH anode is coupled in the anion exchange membrane electrolyzers to promote alkaline water splitting and CO2 -to-CO electrolysis, which achieves low full cell voltages at high current densities.

Design, synthesis, and anti-influenza A virus activity evaluation of novel indole containing derivatives of triazole.

We designed and synthesized 18 substituted indole derivatives containing a triazole scaffold as novel anti-influenza A virus candidates using a bio-isosteric and scaffold-hopping strategy from the lead compound 4-32-2. Most of the target compounds (eg: 6, 7a, 7d, 7f-j, 7l, 7m, 7o, 7q) exhibited potent anti-influenza A virus activity and low cytotoxicity in vitro. In particular, 7a exhibited the most potent anti-IAV activity (IC50: 1.34 ± 0.13 µM) with low cytotoxicity (CC50: > 100 µM), and high selectivity index (SI: > 74.63), which provides a new chemical scaffold for the development of novel anti-IAV drug.

Diel Fluctuation Superimposed on Steady High pCO2 Generates the Most Serious Cadmium Toxicity to Marine Copepods.

Coastal systems experience diel fluctuation of pCO2 and cadmium (Cd) pollution; nevertheless, the effect of fluctuating pCO2 on Cd biotoxicity is poorly known. In this study, we initially performed the isotopically enriched organism bioassay to label Tigriopus japonicus with 113Cd (5 µg/L) to determine the Cd accumulation rate constant (kaccu) under ambient (400 µatm) and steadily (1000 µatm) and fluctuatingly elevated (1000 ± 600 µatm) pCO2 conditions for 48 h. Next, T. japonicus was interactively subjected to the above pCO2 exposures at Cd (control, 5, and 500 µg/L) treatments for 7 d. Biochemical and physiological responses for copepods were analyzed. The results showed that steadily increased pCO2 facilitated Cd bioaccumulation compared to ambient pCO2, and it was more under fluctuating acidification conditions. Despite compensatory reactions (e.g., increased energy production), Cd ultimately induced oxidative damage and apoptosis. Meanwhile, combined treatment exhibited higher toxicity (e.g., increased apoptosis) relative to Cd exposure, and even more if fluctuating acidification was considered. Intriguingly, fluctuating acidification inhibited Cd exclusion in Cd-treated copepods compared to steady acidification, linking to higher Cd kaccu and bioaccumulation. Collectively, CO2-driven acidification could aggravate Cd toxicity, providing a mechanistic understanding of the interaction between seawater acidification and Cd pollution in marine copepods.

Metabolic Adaptation of a Globally Important Diatom following 700 Generations of Selection under a Warmer Temperature.

Diatoms, accounting for 40% of the marine primary production and 20% of global carbon dioxide fixation, are threatened by the ongoing ocean warming (OW). However, whether and how these ecologically important phytoplankton adapt to OW remains poorly unknown. Here, we experimentally examined the metabolic adaptation of a globally important diatom species Skeletonema dohrnii (S. dohrnii) to OW at two elevated temperatures (24 and 28 °C compared with 20 °C) under short-term (∼300 generations) and long-term (∼700 generations) selection. Both warming levels significantly increased the cell growth rate but decreased the chlorophyll a content. The contents of particulate organic carbon (POC) and particulate organic nitrogen (PON) decreased significantly initially (i.e., until 300 generations) at two temperature treatments but completely recovered after 700 generations of selection, suggesting that S. dohrnii ultimately developed thermal adaptation. Proteomic analysis demonstrated that elevated temperatures upregulated energy metabolism via glycolysis, tricarboxylic acid cycle, and fatty acid oxidation as well as nitrogen acquisition and utilization, which in turn reduced substance storage because of trade-off in the 300th generation, thus decreasing POC and PON. Interestingly, populations at both elevated temperatures exhibited significant proteome plasticity in the 700th generation, as primarily demonstrated by the increased lipid catabolism and glucose accumulation, accounting for the recovery of POC and PON. Changes occurring in cells at the 300th and 700th generations demonstrate that S. dohrnii can adapt to the projected OW, and readjusting the energy metabolism is an important adaptive strategy.

Design, synthesis, and antibacterial evaluation of PFK-158 derivatives as potent agents against drug-resistant bacteria.

Infections caused by antibiotic resistant bacteria are a major health concern throughout the world. It is well known that PFK-158 can enhance the antibacterial effect of polymyxin, but its own anti-bactericidal effect is rarely discussed. In order to investigate the anti-bactericidal effect of PFK-158 and its derivatives, PFK-158 and 35 derivatives were designed, synthesized, and evaluated for their antibacterial activities. Compounds A1, A3, A14, A15 and B6 exhibited potent antibacterial effect against both clinical drug sensitive and resistant Gram-positive bacteria, and they are 2-8 folds more potent than levofloxacin against Methicillin-resistant staphylococcus epidermidis (MRSE). A significant synergistic effect of these compounds and polymyxin against drug-resistant Gram-negative bacteria, which is similar to PFK-158 was also observed. The result can provided a new and broader prospect for the development of new medicine against drug-resistant bacteria.

Metaproteomics of marine viral concentrates reveals key viral populations and abundant periplasmic proteins in the oligotrophic deep chlorophyll maximum of the South China Sea.

Viral concentrates (VCs), containing bioinformative DNA and proteins, have been used to study viral diversity, viral metagenomics and virus-host interactions in natural ecosystems. Besides viruses, VCs also contain many noncellular biological components including diverse functional proteins. Here, we used a shotgun proteomic approach to characterize the proteins of VCs collected from the oligotrophic deep chlorophyll maximum (DCM) of the South China Sea. Proteins of viruses infecting picophytoplankton, that is, cyanobacteria and prasinophytes, and heterotrophic bacterioplankton, such as SAR11 and SAR116, dominated the viral proteome. Almost no proteins from RNA viruses or known gene transfer agents were detected, suggesting that they were not abundant at the sampling site. Remarkably, nonviral proteins made up about two thirds of VC proteins, including overwhelmingly abundant periplasmic transporters for nutrient acquisition and proteins for diverse cellular processes, that is, translation, energy metabolism and one carbon metabolism. Interestingly, three 56 kDa selenium-binding proteins putatively involved in peroxide reduction from gammaproteobacteria were abundant in the VCs, suggesting active removal of peroxide compounds at DCM. Our study demonstrated that metaproteomics provides a valuable avenue to explore the diversity and structure of the viral community and also the pivotal biological functions affiliated with microbes in the natural environment.

Dihydropyrazothiazole derivatives as potential MMP-2/MMP-8 inhibitors for cancer therapy.

MMP-2/MMP-8 is established as one of the most important metalloenzymes for targeting cancer. A series of dihydropyrazothiazole derivatives (E1-E18) bearing a salicylaldehyde group linked to Pyrazole ring were designed, synthesized, and evaluated for their pharmacological activity as MMP-2/MMP-8 inhibitors. Among them, compound E17 exhibited most potent inhibitory activity (IC50 = 2.80 µM for MMP-2 and IC50 = 5.6 µM for MMP-8), compared to the positive drug CMT-1 (IC50 = 1.29 µM). Compounds (E1-E18) were scrutinized by CoMFA and CoMSIA techniques of Three-dimensional quant. structure-activity relationship (3D-QSAR), as well as a docking simulation. Moreover, treatment with compound E4 could induce MCF-7 cell apoptosis. Overall, the biological profile of E1-E18 may provide a research basis for the development of new agents against cancer.

Comparative proteomics reveals highly and differentially expressed proteins in field-collected and laboratory-cultured blooming cells of the diatom Skeletonema costatum.

Diatoms are a major phytoplankton group causing extensive blooms in the ocean. However, little is known about the intracellular biological processes occurring during the blooming period. This study compared the protein profiles of field-collected and laboratory-cultured blooming cells of Skeletonema costatum, and identified highly and differentially expressed proteins using the shotgun proteomic approach. A total of 1372 proteins were confidently identified with two or more peptides. Among them, 222 and 311 proteins were unique to the laboratory and field samples respectively. Proteins involved in photosynthesis, translation, nucleosome assembly, carbohydrate and energy metabolism dominated the protein profiles in both samples. However, different features of specific proteins were also found: proteins participated in light harvesting, photosynthetic pigment biosynthesis, photoprotection, cell division and redox homeostasis were highly detected in the field sample, whereas proteins involved in translation, amino acid and protein metabolic processes, and nitrogen and carbon assimilation presented high detection rates in the laboratory sample. ATP synthase cf1 subunit beta and light harvest complex protein were the most abundant protein in the laboratory and field samples respectively. These results indicated that S. costatum had evolved adaptive mechanisms to the changing environment, and integrating field and laboratory proteomic data should provide comprehensive understanding of bloom mechanisms.

Indole-3-acetic acid reverses the harpin-induced hypersensitive response and alters the expression of hypersensitive-response-related genes in tobacco.

Harpin proteins stimulate hypersensitive response (HR) in plants. However, the mechanism by which HR is regulated is not clear. The role of the auxin, indole-3-acetic acid (IAA), in the control of harpin-stimulated HR was investigated. IAA was used to inhibit HR that was stimulated by purified fusion harpin(Xoo) protein in tobacco. Semi-quantitative PCR and qRT-PCR were employed to detect the expression of HR related genes. IAA at 100 µM reversed harpin-induced HR which was inhibited by 500 µM 2,3,5-triiodobenzoic acid (TIBA). Semi-quantitative PCR and qRT-PCR showed the combined application of 100 µM IAA and harpin protein from Xanthomonas oryzae enhanced the expression of HR marker gene, hsr203J, but weakened the expression of the disease-defense gene, chia5. TIBA also decreased the expression of hsr203J but increased the expression of chia5. Thus, the auxin can reverse harpin(Xoo)-induced HR.

Development of a chemiluminescence enzyme-linked immunosorbent assay for the simultaneous detection of imidaclothiz and thiacloprid in agricultural samples.

A novel and sensitive enhanced chemiluminescence enzyme-linked immunosorbent assay (ECL-ELISA) for the simultaneous analysis of imidaclothiz and thiacloprid is described. The concentrations of coating antibodies and enzyme tracers were optimised by three different ECL-ELISA formats. Under the optimised conditions, when anti-imidaclothiz polyclonal and anti-thiacloprid polyclonal antibodies were immobilised in a single well, single-enzyme tracer ECL-ELISA was used to screen the corresponding pesticide residue, and multi-enzyme tracer ECL-ELISA was used for the analysis of imidaclothiz and thiacloprid residue mixtures. The average recoveries of the two pesticides from spiked tomato, cabbage, and rice samples were in the range of 83.7-117%. Meanwhile, the results showed that the multi-enzyme tracer ECL-ELISA could be applied to the accurate analysis of different proportions of imidaclothiz and thiacloprid (1 : 4 to 4 : 1, m/m) when the gross residues ranged from 20 to 250 µg kg(-1). The results of the multi-enzyme tracer ECL-ELISA in the real tomato samples correlated well with those of high-performance liquid chromatography, with a correlation coefficient of 0.996. Therefore, this new strategy for developing immunoassays is suitable for the simultaneous quantitative detection of imidaclothiz and thiacloprid residues in agricultural samples.

Synthesis and antioxidant activity of novel Mannich base of 1,3,4-oxadiazole derivatives possessing 1,4-benzodioxan.

A new series of Mannich base of 1,3,4-oxadiazole derivatives possessing 1,4-benzodioxan (6a-6ae) were synthesized and characterized by (1)H NMR, ESI-MS and elemental analysis. The structure of 6b was further confirmed by single crystal X-ray diffraction. All these novel compounds were screened for their in vitro antioxidant activity employing 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(+)) and ferric reducing antioxidant power (FRAP) scavenging assays. Due to the combination of 1,4-benzodioxan, 1,3,4-oxadiazoles and substituted phenyl ring, most of them exhibited nice antioxidant activities. In all of these three assays mentioned above, compounds 6f and 6e showed significant radical scavenging ability comparable to the commonly used antioxidants, BHT and Trolox. Seven compounds with representative substituents or activities were selected for further assays in chemical simulation biological systems-inhibition of microsomal lipid peroxidation (LPO) and protection against 2,2'-azobis (2-amidinopropane hydrochloride) (AAPH) induced DNA strand breakage, in which, 6f and 6e were demonstrated to be of the most potent antioxidant activities.

A matched case-control study in Taiwan to evaluate potential risk factors for prostate cancer.

The rising incidence rate of prostate cancer (PCa) worldwide has become a public health concern. PCa has a multifactorial etiology, and the link between human papillomavirus (HPV) and PCa has been widely investigated by numerous case-control studies. This age-matched, case-control study included 143 PCa patients and 135 benign prostatic hyperplasia (BPH) patients, with prostatic specimens testing negative for malignancy, as control. Study participants were recruited from four major hospitals in Taoyuan City, Taiwan, period 2018-2020, looking into HPV infection and other PCa risk factors, including dietary habits, family history, personal lifestyle, and sexual behavior. Multiple logistic regression analysis and forward stepwise selection analysis were conducted to identify potential risk factors for PCa. HPV DNA was found in 10 of the 143 PCa cases (7%) and 2 of the 135 BPH controls (1.5%) (OR = 6.02, 95% CI = 1.03-30.3, p = 0.046). This association was slightly significant, and furthermore, high risk HPV was not found to be associated with PCa. Higher body mass index (BMI) (OR = 1.15, 95% CI = 1.05-1.27, p = 0.003), more total meat consumption (OR = 2.74, 95% CI = 1.26-5.94, p = 0.011), exhibited association to PCa. However, PCa family history only presented a statistically significant difference by forward stepwise analysis (OR = 3.91, 95% CI = 1.17-13.12, p = 0.027). While much focus has been on the association between HPV and PCa, the results of this study indicate that more efforts should be directed towards investigating dietary habits, personal lifestyle and family history as factors for PCa. These results could serve as a basis for designing PCa prevention strategies.

Construction of a ruthenium-doped CoFe-layered double hydroxide as a bifunctional electrocatalyst for overall water splitting.

In this study, ruthenium-doped CoFe-based layered double hydroxides on Ni foam (CoFe-ZLDH/Ru@NF) were fabricated via an etching-precipitation strategy. The resultant CoFe-ZLDH/Ru@NF exhibited excellent activity, showing low overpotentials of 219.8 mV and 60.9 mV to reach the current density of 10 mA cm-2 for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. As a bifunctional electrocatalyst, it was assembled in an anion exchange membrane water electrolyser (AEMWE) unit, performing as an anode and cathode simultaneously, which only required a cell voltage of 2.33 V to accomplish the industrial level current density of 1 A cm-2 and operated steadily for over 12 h, making it promising for utilization in hydrogen production.

Gambierdiscus and Its Associated Toxins: A Minireview.

Gambierdiscus is a dinoflagellate genus widely distributed throughout tropical and subtropical regions. Some members of this genus can produce a group of potent polycyclic polyether neurotoxins responsible for ciguatera fish poisoning (CFP), one of the most significant food-borne illnesses associated with fish consumption. Ciguatoxins and maitotoxins, the two major toxins produced by Gambierdiscus, act on voltage-gated channels and TRPA1 receptors, consequently leading to poisoning and even death in both humans and animals. Over the past few decades, the occurrence and geographic distribution of CFP have undergone a significant expansion due to intensive anthropogenic activities and global climate change, which results in more human illness, a greater public health impact, and larger economic losses. The global spread of CFP has led to Gambierdiscus and its toxins being considered an environmental and human health concern worldwide. In this review, we seek to provide an overview of recent advances in the field of Gambierdiscus and its associated toxins based on the existing literature combined with re-analyses of current data. The taxonomy, phylogenetics, geographic distribution, environmental regulation, toxin detection method, toxin biosynthesis, and pharmacology and toxicology of Gambierdiscus are summarized and discussed. We also highlight future perspectives on Gambierdiscus and its associated toxins.

[Toxicity Testing Organisms for Marine Ecotoxicological Research in China].

Since the late 1970s, marine ecotoxicology began to sprout and develop in China. Based on the principles of dose-response relationships, some marine organisms are used in toxicity tests to evaluate the impact of marine pollutants on marine organisms and marine ecosystems. At the early stage, marine ecotoxicological research mainly focused on the bioaccumulation, biomagnification, and biodegradation of traditional pollutants such as heavy metals, radioactive elements, organotin, petroleum hydrocarbons, and pesticides, as well as their toxic effects on survival, growth, and other physiological indicators. With the development of Chinese industry, marine pollution has become increasingly serious. In addition to the traditional marine pollutants, toxicological research has been conducted on emerging pollutants with potential risks to marine ecosystems, such as POPs, emerging organic pollutants, nanomaterials, and microplastics. Moreover, the species of marine organisms used in toxicity testing have become more diverse. The selection of testing organisms is essential for evaluating toxicity correctly. The toxicity tests should be conducted on a variety of organisms from different trophic levels to ensure the comprehensive understanding of the impact of pollutants on marine ecosystems. The major types of marine organisms used in the toxicity testing include marine alga, protozoa, rotifera, annelida, mollusc, echinoderma, arthropoda, cephalopoda, and marine fish, which have been used in the toxicological studies of various marine pollutants. The outcome results can serve as the scientific basis for the ecological risk assessment of marine pollutants and the establishment of seawater quality criteria. It should be noted that the sensitivity of different testing organisms to different types of pollutants is quite diverse. Therefore, in addition to conducting a battery of tests on a variety of species which play important roles in marine ecosystems, elucidating the toxic mechanisms in different species is also important for marine ecotoxicological studies. The application of the above-mentioned organisms in marine ecotoxicology research in recent years is briefly reviewed here. Particularly, the six commonly used marine model species (Skeletonema costatum, Euplotes vannus, oysters, sea urchins, Tigriopus japonicus, and Oryzias melastigma) used in toxicity testing are introduced in detail.

Calreticulin Regulates ß1-Integrin mRNA Stability in PC-3 Prostate Cancer Cells.

Prostate cancer (PCa) is the major cause of cancer-related death among aging men worldwide. Recent studies have suggested that calreticulin (CRT), a multifunctional chaperon protein, may play an important role in the regulation of PCa tumorigenesis and progression. However, the underlying mechanisms are still unclear. Integrin is an important regulator of cancer metastasis. Our previous study demonstrated that in J82 bladder cancer cells, CRT affects integrin activity through FUBP-1-FUT-1-dependent fucosylation, rather than directly affecting the expression of ß1-integrin itself. However, whether this regulatory mechanism is conserved among different cell types remains to be determined. Herein, we attempted to determine the effects of CRT on ß1-integrin in human prostate cancer PC-3 cells. CRT expression was suppressed in PC-3 cells through siRNA treatment, and then the expression levels of FUT-1 and ß1-integrin were monitored through RT-PCR. We found that knockdown of CRT expression in PC-3 cells significantly affected the expression of ß1-integrin itself. In addition, the lower expression level of ß1-integrin was due to affecting the mRNA stability. In contrast, FUT-1 expression level was not affected by knockdown of CRT. These results strongly suggested that CRT regulates cellular behavior differently in different cell types. We further confirmed that CRT directly binds to the 3'UTR of ß1-integrin mRNA by EMSA and therefore affects its stability. The suppression of CRT expression also affects PC-3 cell adhesion to type I collagen substrate. In addition, the levels of total and activated ß1-integrin expressed on cell surface were both significantly suppressed by CRT knockdown. Furthermore, the intracellular distribution of ß1-integrin was also affected by lowering the expression of CRT. This change in distribution is not lysosomal nor proteosomal pathway-dependent. The treatment of fucosydase significantly affected the activation of surface ß1-integrin, which is conserved among different cell types. These results suggested that CRT affects the expression of ß1-integrin through distinct regulatory mechanisms.

Metaexoproteomics Reveals Microbial Behavior in the Ocean's Interior.

The proteins present in the extracellular environment of cells, named the "exoproteome," are critical for microbial survival, growth, and interaction with their surroundings. However, little is known about microbial exoproteomes in natural marine environments. Here, we used a metaproteomic approach to characterize the exoprotein profiles (10 kDa-0.2 µm) throughout a water column in the South China Sea. Viruses, together with Alpha- and Gammaproteobacteria were the predominant contributors. However, the exoprotein-producing microbial communities varied with depth: SAR11 in the shallow waters, Pseudomonadales and Nitrososphaeria in the mesopelagic layer, and Alteromonadales, Rhizobiales, and Betaproteobacteria in the bathypelagic layer. Besides viral and unknown proteins, diverse transporters contributed substantially to the exoproteomes and varied vertically in their microbial origins, but presented similar patterns in their predicted substrate identities throughout the water column. Other microbial metabolic processes subject to vertical zonation included proteolysis, the oxidation of ammonia, nitrite and carbon monoxide, C1 metabolism, and the degradation of sulfur-containing dissolved organic matter (DOM). Our metaexoproteomic study provides insights into the depth-variable trends in the in situ ecological traits of the marine microbial community hidden in the non-cellular world, including nutrient cycling, niche partitioning and DOM remineralization.

Development of an enzyme-linked immunosorbent assay for determination of pretilachlor in water and soil.

An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) has been developed for detection of pretilachlor in water and soil. An immunogen was prepared from haptens of pretilachlor conjugated to bovine serum albumin(BSA). The specific polyclonal antibodies were obtained by immunizing New Zealand white rabbits. The influence of parameters including concentrations of methanol, ionic strength and pH values were optimized to improve the sensitivity of the assay. The optimized ELISA was shown to have a high sensitivity and specificity for pretilachlor. Under optimal conditions, the ELISA has demonstrated an 50% inhibitory concentration (IC(50)) value of 0.0359 mg/L with a limit of detection (LOD, IC(10)) of 6.9 ng/L. The cross-reactivities to some analogs of pretilachlor (acetochlor, butachlor, metazachlor and metalaxyl) were below 1.5%. The average recoveries of pretilachlor from distilled water, tap water, paddy water and soil were in the range of 77.0-115.2% between 0.005 and 5.0mg/L. The results of ELISA for spiked samples were confirmed by GC-ECD with a high correlation coefficient of 0.9950(n=11). Thus, the ELISA proven to be a sensitive, specific, inexpensive and quantitative tool for detection of pretilachlor from four kinds of spiked samples.

[SERS spectra of L-carnosine under the interaction of coordination with adsorbed SnCl2].

The authors have found that by virtue of utilizing the interaction of strongly chemically adsorbed SnCl2 with the analytes of organic/biologic molecules, the authors can not only effectively eliminate the laser carbonization and oxidation of probe molecules (e. g. pyridine), but also obtain specially enhanced Raman signals (e. g. vitamin B6). This method is applicable to the SERS spectroscopic analysis of highly reactive organic/biologic molecules. In the present paper, the authors report the investigation results on the electrochemical SERS spectra of L-carnosine (LCar) for the first time, mainly concentrating on the influence of adsorbed SnCl2 and applied potential on the SERS spectra of LCar. The SERS spectra of LCar were badly interfered by laser carbonization in the absence of SnCl2. However, in the presence of SnCl2 high quality SERS spectra of LCar could be obtained free of carbonization. It is demonstrated that LCar can be immobilized on the gold substrate indirectly via surface coordination with the pre-adsorbed SnCl2 under potential control. Apparently, such a sandwich-like adsorption configuration as Au-Sn(II)-LCar is beneficial both to sensing the strong electromagnetic field at the nanostructured gold surface and to preventing the LCar from damage by the laser.

Dosimetric comparison of helical tomotherapy, volumetric-modulated arc therapy, intensity-modulated radiotherapy, and field-in-field technique for synchronous bilateral breast cancer.

PURPOSE: To compare the dosimetric characteristics of helical tomotherapy (HT), volumetric-modulated arc therapy (VMAT), intensity-modulated radiotherapy (IMRT), and tangential field-in-field technique (FIF) for the treatment of synchronous bilateral breast cancer (SBBC). METHODS AND MATERIALS: Ten patients with early-stage unilateral breast cancer were selected for simulating the patients with SBBC in this retrospective analysis. Treatment plans with HT, VMAT, IMRT, and FIF were generated for each patient with a total dose of 50.4 Gy in 28 fractions to the target. Plan quality, namely conformity index (CI), homogeneity index (HI), dose-volume statistics of organs at risk (OARs), and beam-on time (BOT), were evaluated. RESULTS: HT plans showed a lower mean heart dose (3.53 ± 0.31Gy) compared with the other plans (VMAT = 5.6 ± 1.36 Gy, IMRT = 3.80 ± 0.76 Gy, and FIF = 4.84 ± 2.13 Gy). Moreover, HT plans showed a significantly lower mean lung dose (p < 0.01) compared with the other plans: mean right lung doses were 6.81 ± 0.67, 10.32 ± 1.04, 9.07 ± 1.21, and 10.03 ± 1.22 Gy and mean left lung doses were 6.33 ± 0.87, 8.82 ± 0.91, 7.84 ± 1.07, and 8.64 ± 0.99 Gy for HT, VMAT, IMRT, and FIF plans, respectively. The mean dose to the left anterior descending artery was significantly lower in HT plans (p < 0.01) than in the other plans: HT = 19.41 ± 0.51 Gy, VMAT = 25.77 ± 7.23 Gy, IMRT = 27.87 ± 6.48 Gy, and FIF = 30.95 ± 10.17 Gy. FIF plans showed a worse CI and HI compared with the other plans. VMAT plans showed shorter BOT (average, 3.9 ± 0.2 minutes) than did HT (average, 11.0 ± 3.0 minutes), IMRT (average, 6.1 ± 0.5 minutes), and FIF (average, 4.6 ± 0.7 minutes) plans. CONCLUSIONS: In a dosimetric comparison for SBBC, HT provided the most favorable dose sparing of OARs. However, HT with longer BOT may increase patient discomfort and treatment uncertainty. VMAT enabled shorter BOT with acceptable doses to OARs and had a better CI than did FIF and IMRT.