Risk Factors for Postoperative Complications Following Aesthetic Breast Surgery: A Retrospective Cohort Study of 4973 Patients in China.

BACKGROUND: The popularity of aesthetic breast surgery in China results in greater demand for assessing risk factors for complications and mortality. OBJECTIVES: To determine the incidence and independent risk factors for postoperative complications following aesthetic breast surgery in China. METHODS: A retrospective cohort study on 4973 patients who had aesthetic breast surgery between 2012 and 2021 was performed. Postoperative complications include minor complications (incision healing impaired, hematoma, or fat liquefaction) and surgical site infection (SSI), which were recorded within 30 days after surgery. The follow-up time was expanded to 1 year only after prosthesis implantation procedures. Potential risk factors including age, weight, length of hospital stay, operation time, volume resection, incision location, and other clinical profile information were evaluated. RESULTS: Among 4973 patients who underwent aesthetic breast surgery, the minor complication rate was 0.54%, and SSI was 0.68%. Augmentation with prosthesis implantation had the highest SSI rate (4.23%), which was significantly associated with increasing age (relative risk [RR] 1.12; P < 0.01) and periareolar incision (RR 5.87, P < 0.01). After augmentation with autologous fat transplantation, postoperative antibiotic use (RR 6.65, P < 0.01) was an independent risk factor for SSI. After adjusting for weight, volume resection over 1500 g (RR 14.7, P < 0.01) was an independent risk factor for SSI of reduction-mastopexy surgery. The complication rate of reduction mammaplasty (1.01%) and gynecomastia correction was lower (0.75%), and there was no record of complication in mastopexy procedures (n = 161). CONCLUSION: The incidence of postoperative complications following aesthetic breast surgery is low. Risk factors for complications mainly include increasing age, perioperative antibiotic use, periareolar incision, and extensive volume resection. Much more attention should be focused on those high-risk patients in clinical practice to decrease breast infection. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Polyamines Disrupt the KaiABC Oscillator by Inducing Protein Denaturation.

Polyamines are positively charged small molecules ubiquitously existing in all living organisms, and they are considered as one kind of the most ancient cellular components. The most common polyamines are spermidine, spermine, and their precursor putrescine generated from ornithine. Polyamines play critical roles in cells by stabilizing chromatin structure, regulating DNA replication, modulating gene expression, etc., and they also affect the structure and function of proteins. A few studies have investigated the impact of polyamines on protein structure and function previously, but no reports have focused on a protein-based biological module with a dedicated function. In this report, we investigated the impact of polyamines (putrescine, spermidine, and spermine) on the cyanobacterial KaiABC circadian oscillator. Using an established in vitro reconstitution system, we noticed that polyamines could disrupt the robustness of the KaiABC oscillator by inducing the denaturation of the Kai proteins (KaiA, KaiB, and KaiC). Further experiments showed that the denaturation was likely due to the induced change of the thermal stability of the clock proteins. Our study revealed an intriguing role of polyamines as a component in complex cellular environments and would be of great importance for elucidating the biological function of polyamines in future.

The influence of KaiA mutations on its function in the KaiABC circadian clock system.

The core oscillator of the circadian clock of cyanobacteria consists of three proteins, KaiA, KaiB, and KaiC. The KaiABC oscillator can be re-constituted in vitro with the purified proteins in buffer containing ATP and Mg2+. The interaction between KaiA and KaiC has not been well studied. In this article, different KaiA mutants were designed and used to elucidate the influence of KaiA structure on its function in the in vitro system. Molecular dynamics simulations were adopted to study the structural flexibility of KaiA homodimer. The data presented in this article provide further experimental supports to our work in Chen et al. (2017) [1].

[Progress in the effect of polyamines on proteins].

Polyamines are a kind of aliphatic amines that exist widely in nearly all organisms. Polyamines interact with biological macromolecules through ionic interactions and hydrogen bonds, thereby they could affect the cell growth via regulating the function of macro-molecules. The impact of polyamines on nucleic acids has been thoroughly studied. However, their effects on protein structure and functions are not well established. This review summarizes the recent progress on how polyamines affect proteins, including metabolic enzymes, ion channel proteins and other important proteins. The interaction between polyamines and proteins is discussed, and the review also summarizes the challenges in studying polyamine-protein interaction as well as the potential application of these studies on the therapy of correlated diseases.

The reversible function switching of the circadian clock protein KaiA is encoded in its structure.

BACKGROUND: Circadian rhythms are important to the evolution of organisms and human health, and recent studies proved that post-translational circadian clocks widely exist in all phyla. The circadian clock of cyanobacteria is an important model system as the first verified circadian oscillator independent of transcriptional-/translational-level regulations. This circadian oscillator consists of three proteins, KaiA, KaiB, and KaiC, in which KaiA stimulates KaiC's phosphorylation but KaiB antagonizes KaiA. Despite of intense research on the molecular mechanism of this oscillator in the last decades, the regulation mechanism of KaiA's function remains unclear. METHODS: In this study, we combined computational tools and experimental assays to study the function switching of KaiA. We adopted different strategies to re-design KaiA protein to elucidate its function switch during the circadian oscillation. RESULTS: We showed that KaiA's function switch is determined by its structural dynamics, and KaiB antagonizes KaiA by switching it from an active state to an inactive state with the help of KaiC. CONCLUSIONS: The reversible function switching of KaiA is key to the KaiABC oscillator, and the switching could be regulated by the 3-D domain swapped homo-dimer conformation of KaiA, which provides the necessary structural flexibility. GENERAL SIGNIFICANCE: Our finding updated the current knowledge on the regulation of KaiA's function. This work would deepen our understanding of the KaiABC oscillator, and should be conceptually useful in the design of artificial biological oscillators.