Site-Selective Antibody-Drug Conjugation by a Proximity-Driven S to N Acyl Transfer Reaction on a Therapeutic Antibody.

Immunoglobulin Gs (IgGs) contain many Lys and Cys residues, which results in an unwanted complex product mixture with conventional drug conjugation methods. We selectively acylated the ε-NH2 of K248 on trastuzumab using an IgG Fc-binding peptide (FcBP) equipped with a 5-norbornene-2-carboxylic acid thioester (AbClick-1). AbClick-1 locates its thioester close to the ε-NH2 of K248 while binding to trastuzumab. Consequently, the thioester underwent proximity-driven selective acylation of ε-NH2 through an S to N acyl transfer reaction. Furthermore, N-tert-butyl maleimide accelerated the cross-linking reaction with an approximately 95% yield of the desired product by scavenging the byproduct (FcBP-SH). Only K248 was modified selectively with the 5-norbornene-2-carbonyl group, which was further modified by click reaction to afford an antibody-drug conjugate (ADC) with two drugs per antibody. The resulting ADCs showed remarkable in vitro and in vivo anticancer activity. Our results demonstrate that a thioester is a promising chemical entity for proximity-driven site-selective conjugation of antibodies.

Association between Elevated Plasma Homocysteine and Low Skeletal Muscle Mass in Asymptomatic Adults.

BACKGROUND: Homocysteine has been drawing attention with a closed linkage with skeletal muscle. However, the association of hyperhomocysteinemia with decreased skeletal muscle mass remains unclear. We aimed to investigate the association of hyperhomocysteinemia with low skeletal muscle mass (LMM) in asymptomatic adults. METHODS: This was a cross-sectional study of 114,583 community-dwelling adults without cancer, stroke, or cardiovascular diseases who underwent measurements of plasma homocysteine and body composition analysis from 2012 to 2018. Hyperhomocysteinemia was defined as >15 µmol/L. Skeletal muscle mass index (SMI) was calculated based on appendicular muscle mass (kg)/height (m)2. Participants were classified into three groups based on SMI: "normal," "mildly low," and "severely low." RESULTS: The prevalence of hyperhomocysteinemia was the highest in subjects with severely LMM (12.9%), followed by those with mildly LMM (9.8%), and those with normal muscle mass (8.5%) (P for trend <0.001). In a multivariable logistic regression model, hyperhomocysteinemia was significantly associated with having a mildly LMM (odds ratio [OR], 1.305; 95% confidence interval [CI], 1.224 to 1.392) and severely LMM (OR, 1.958; 95% CI, 1.667 to 2.286), respectively. One unit increment of log-transformed homocysteine was associated with 1.360 and 2.169 times higher risk of having mildly LMM and severely LMM, respectively. CONCLUSION: We demonstrated that elevated homocysteine has an independent association with LMM in asymptomatic adults, supporting that hyperhomocysteinemia itself can be a risk for decline in skeletal musculature.

Survey on tick distribution and tick-borne pathogens in Daejeon and adjacent areas in South Korea.

Ticks (Ixodidae, also known as hard ticks) as principal vectors of zoonotic diseases such as severe fever with thrombocytopenia syndrome (SFTS), Lyme borreliosis, relapsing fever, anaplasmosis, ehrlichiosis, babesiosis, coxiellosis (Q fever), and tularemia pose a major public health threat. This study was conducted to identify the distribution profile of ticks and tick-borne pathogens in Daejeon and the adjacent areas in South Korea, where no such epidemiological study has been conducted. From April to October 2019, 16,765 ticks were collected from three genera and four species: Haemaphysalis longicornis (n = 14,949; 89.2 %), Haemaphysalis flava (n = 987; 5.9 %), Ixodes nipponensis (n = 828; 5.0 %), and Amblyomma testudinarium (n = 1; 0.01 %). Homogenized samples of ticks were screened by real-time reverse transcription polymerase chain reaction (PCR), real-time PCR, and PCR for the presence of the following tick-borne pathogens: SFTS virus (SFTSV), Borrelia spp., Babesia microti, Coxiella burnetii, Francisella tularensis, Anaplasma phagocytophilum, and Ehrlichia spp. As a result, SFTSV (2 cases), Borrelia spp. (32 cases), and Babesia microti (7 cases) were detected. The findings of this study will contribute to the prevention and management of tick-borne zoonoses.

Self-augmentation: Generalizing deep networks to unseen classes for few-shot learning.

Few-shot learning aims to classify unseen classes with a few training examples. While recent works have shown that standard mini-batch training with carefully designed training strategies can improve generalization ability for unseen classes, well-known problems in deep networks such as memorizing training statistics have been less explored for few-shot learning. To tackle this issue, we propose self-augmentation that consolidates self-mix and self-distillation. Specifically, we propose a regional dropout technique called self-mix, in which a patch of an image is substituted into other values in the same image. With this dropout effect, we show that the generalization ability of deep networks can be improved as it prevents us from learning specific structures of a dataset. Then, we employ a backbone network that has auxiliary branches with its own classifier to enforce knowledge sharing. This sharing of knowledge forces each branch to learn diverse optimal points during training. Additionally, we present a local representation learner to further exploit a few training examples of unseen classes by generating fake queries and novel weights. Experimental results show that the proposed method outperforms the state-of-the-art methods for prevalent few-shot benchmarks and improves the generalization ability.

Fungal melanin as a biocompatible broad-spectrum sunscreen with high antioxidant activity.

Melanin is considered a bio-inspired dermo-cosmetic component due to its high UV absorption and antioxidant activity. Among various melanin sources, fungal melanin is a promising candidate for sunscreen because of its sustainability and scalability; however, quantitative assessment of its function has not yet been sufficiently explored. In this study, melanin samples derived from Amorphotheca resinae were prepared, followed by the evaluation of their sunscreen performance, antioxidant activity, and cytotoxicity. Melanin-blended cream was prepared by blending a melanin suspension and a pure cream. The cream showed an in vitro sun protection factor value of 2.5 when the pigment content was 5%. The cream showed a critical wavelength of approximately 388 nm and a UVA/UVB ratio of more than 0.81, satisfying the broad-spectrum sunscreen requirement. Oxygen radical absorbance capacity assays indicated that fungal melanin had antioxidant activity similar to ascorbic acid but higher than reduced glutathione. Fungal melanin had no statistically significant cytotoxicity to human keratinocyte cell lines until 72 h of exposure, even at a concentration of 4 mg mL-1. Consequently, melanin pigment can be used as a biocompatible broad-spectrum sunscreen with high antioxidant activity and as a practical alternative in dermo-cosmetic formulations.

Selection and characterization of toxic Aspergillus spore-specific DNA aptamer using spore-SELEX.

As airborne spores of toxic Aspergillus species cause mild symptoms to invasive fungal infections, their indoor concentration should be controlled through real-time management. Aptamer-based biosensors could provide economical and simple solutions for point-of-care. In this study, we isolated aptamers binding to the spores of three representative toxic Aspergillus species (A. fumigatus, A. flavus, and A. niger) for the first time, using cell-SELEX (systematic evolution of ligands through exponential enrichment). Among the aptamer candidates, Asp-3 showed a broad and high binding affinity for the Aspergillus spores. Considering the low binding affinity with proteinase-treated spores, we speculated that the Asp-3 binding sites could be possibly associated with cell surface proteins. The high Asp-3 specificity was confirmed by comparing the binding affinity between the Aspergillus target species and other common indoor fungal species. Moreover, we also established quantitative linear relationships between Asp-3 and the spore concentration of each Aspergillus species. Therefore, the selected Asp-3 aptamer, conjugated with detection sensors, could be an effective biorecognition element for the spores of three toxic Aspergillus species.

Non-constraining sleep/wake monitoring system using bed actigraphy.

This paper introduces a new method, bed actigraphy (BACT) for user-friendly sleep-wake monitoring. BACT provides a non-intrusive acquisition of activity data, and in particular does not require that sensors be attached to the subject's body. The system consists of four load-sensing cells supporting the bed, an A/D converter, and a microcontroller with appropriate software. The performance of BACT was compared to that of standard polysomnography (PSG) recordings and wrist-worn actigraphy (ACT). Ten normal volunteers underwent overnight PSG recordings and were examined simultaneously with BACT and ACT. An automatic scoring algorithm scored each 30-s epoch of the BACT recordings for either 'Wake' or 'Sleep.' A sleep specialist manually scored the PSG recordings, and the results were divided into 'Wake' and 'Sleep' categories. The three methods showed a significant correlation when compared with in the contingency test. The mean epoch-by-epoch agreements between the BACT and PSG, ACT and PSG, and BACT and ACT recordings were 95.2, 92.9, and 94.3%, respectively. The mean absolute differences in sleep percentage (SP) between them were 1.8 +/- 0.82, 3.4 +/- 1.45, and 1.9 +/- 1.16 %, respectively. BACT differentiation of the 'Wake' and 'Sleep' stages proved to be sufficiently robust, and its results were comparable to PSG analysis. This finding supports the experimental and clinical value of bed-activity monitoring during sleep.