Nonlinear optical response of heme solutions.

Heme is the prosthetic group for cytochrome that exists in nearly all living organisms and serves as a vital component of human red blood cells (RBCs). Tunable optical nonlinearity in suspensions of RBCs has been demonstrated previously, however, the nonlinear optical response of a pure heme (without membrane structure) solution has not been studied to our knowledge. In this work, we show optical nonlinearity in two common kinds of heme (i.e., hemin and hematin) solutions by a series of experiments and numerical simulations. We find that the mechanism of nonlinearity in heme solutions is distinct from that observed in the RBC suspensions where the nonlinearity can be easily tuned through optical power, concentration, and the solution properties. In particular, we observe an unusual phenomenon wherein the heme solution exhibits negative optical nonlinearity and render self-collimation of a focused beam at specific optical powers, enabling shape-preserving propagation of light to long distances. Our results may have potential applications in optical imaging and medical diagnosis through blood.

Prognostic value of red blood cell distribution width to albumin ratio for predicting mortality in adult patients meeting sepsis-3 criteria in intensive care units.

BACKGROUND: Patients with sepsis with low albumin levels and high red blood cell distribution width levels have poor prognoses. Red blood cell distribution width to albumin ratio (RAR) has recently attracted attention as an innovative inflammation biomarker. We aimed to explore the association between RAR and the prognosis of patients with sepsis. METHODS: This retrospective observational study included 402 patients meeting the sepsis-3 standards admitted to Yantai Yuhuangding Hospital's intensive care units (ICUs) between January 2020 and December 2022. The relationship between RAR and mortality in patients with sepsis was examined using regression analysis, Kaplan-Meier analyses, and a receiver operating characteristic curve. Subgroup and sensitivity analyses were conducted to assess the results' robustness. RESULTS: RAR, when considered as a continuous variable, was a significant independent in-hospital mortality risk factor (adjusted odds ratio [OR]: 1.383; 95% confidence interval [CI]: 1.164-1.645; P < 0.001). When considering RAR as a categorical variable, the ORs (95% CIs) of hospital mortality for quartile 2 (Q2), Q3, and Q4 compared with Q1 were 1.027 (0.413-2.551), 3.632 (1.579-8.354), and 4.175 (1.625-10.729), respectively, P < 0.001. Similar outcomes were observed for 28- and 90-day mortalities. CONCLUSIONS: RAR may indicate clinical prognosis for patients with sepsis in the ICU, potentially providing a low-cost, easily repeatable, and accessible biomarker for risk categorization for these patients.

Increased oxidative stress and disrupted small intestinal tight junctions in cigarette smoke-exposed rats.

Chronic obstructive pulmonary disease (COPD) is a major public health problem, and cigarette smoke (CS) is the primary risk factor. The pathology is often observed in the lung, but COPD is also associated with intestinal barrier disruption, although the underlying mechanisms are poorly understood. To address this, a CS­exposed rat model was evaluated in the present study by analyzing small intestinal gene expression using reverse transcription­quantitative polymerase chain reaction. CS exposure caused upregulation of the nicotinamide adenine dinucleotide phosphate­oxidase subunits nox2 and p22phox in the small intestine, while the antioxidative enzyme superoxide dismutase was downregulated. CS exposure also increased bax expression and decreased bcl­2 expression. This was associated with an elevation of hypoxia­inducible factor (HIF)­1α. Claudin­1 was decreased and claudin­2 increased, indicating a loosening of small intestinal tight junctions (TJs). These data suggest that during the development of COPD, HIF­1α expression is altered in the small intestine, which may be associated with the increased oxidative stress and apoptosis, eventually resulting in disruption of the intestinal TJs.