Nitrogen Deposition Amplifies the Legacy Effects of Plant Invasion.

The legacy effects of invasive plant species can hinder the recovery of native communities, especially under nitrogen deposition conditions, where invasive species show growth advantages and trigger secondary invasions in controlled areas. Therefore, it is crucial to thoroughly investigate the effects of nitrogen deposition on the legacy effects of plant invasions and their mechanisms. The hypotheses of this study are as follows: (1) Nitrogen deposition amplifies the legacy effects of plant invasion. This phenomenon was investigated by analysing four potential mechanisms covering community system structure, nitrogen metabolism, geochemical cycles, and microbial mechanisms. The results suggest that microorganisms drive plant-soil feedback processes, even regulating or limiting other factors. (2) The impact of nitrogen deposition on the legacy effects of plant invasions may be intensified primarily through enhanced nitrogen metabolism via microbial anaerobes bacteria. Essential insights into invasion ecology and ecological management have been provided by analysing how nitrogen-fixing bacteria improve nitrogen metabolism and establish sustainable methods for controlling invasive plant species. This in-depth study contributes to our better understanding of the lasting effects of plant invasions on ecosystems and provides valuable guidance for future ecological management.

Effect of procalcitonin on the severity and prognostic value of elderly patients with a severe infection of oral and maxillofacial space.

This study aimed to investigate the effect on the severity and prognostic value of serum procalcitonin for elderly patients with oral and maxillofacial infections. We divided 163 elderly patients with severe oral and maxillofacial infection into survival and death groups according to the prognosis between June 2015 and May 2021, measured serum procalcitonin by enzyme-linked immunosorbent assay on the 1st, 2nd, 3rd, 5th, and 7th day after admission for the dynamic changes of serum procalcitonin level, collected the general physiological and biochemical indexes for the scores of acute physiology and general chronic condition, compared the correlation between serum procalcitonin, mean platelet count and APACHE score, analyzed the prognostic value of serum procalcitonin levels at different time after admission by ROC curve. The serum procalcitonin level increased significantly in both groups after admission, sharply increased at first and then rapidly decreased in the survival group, and continued to rise or declined slowly with fluctuation of high level in the death group. There was a negative correlation between serum procalcitonin level and mean platelet count (r = -0.698, P < .05) and a positive correlation between serum procalcitonin and APACHE II (R = 0.803, P < .05). The ROC curve showed that the serum procalcitonin level had little value on the first day and great value on the third day in predicting the prognosis of elderly patients with severe oral and maxillofacial infection (PCT1d = 0.539, PCT3d = 0.875, P < .05). The serum procalcitonin level is correlated with the severity of the disease in elderly patients with severe oral and maxillofacial space infection. Dynamic observation of it is helpful for the prognosis judgment of patients. After admission, serum procalcitonin level on the third day has a great value for the prognosis judgment of elderly patients with severe oral and maxillofacial space infection.

Procalcitonin kinetics to guide sequential invasive-noninvasive mechanical ventilation weaning in patients with acute exacerbation of chronic obstructive pulmonary disease and respiratory failure: procalcitonin's adjunct role.

How to identify the optimum switch point of sequential invasive and noninvasive ventilation is the focus of clinical attention on the patients suffering from acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated by acute respiratory failure (ARF). This study aims to explore the clinical significance of taking the change rate of procalcitonin (PCT) as identifying the timing of weaning on the mechanical ventilation for the patients of AECOPD followed by ARF as a complication. There were altogether 140 patients of AECOPD complicated with ARF, who were randomly selected and divided into a study group and a control group respectively. A change rate of serum PCT level exceeding 50% was taken as the switch point selection of tracheal intubation removal for the patients of the study group, while the 'pulmonary infection control (PIC) window' was done for those in the control group. With CRP, IL-6, TNF-a, PaCO2, PaO2, and Lac having been detected before and after treatment to them all, clinical indexes were obtained and compared between these two groups. The CRP, TNF-a, and IL-6 levels of the patients in the study group after treatment (p < 0.05) were lower than those in the control group. There was no significant difference in PaCO2, PaO2, and Lac between these two groups before and after treatment (p > 0.05). Even so, some other indexes available for the study group of patients were found to be lower than those for the control group (p < 0.05) in the following aspects: duration of invasive ventilation support, total time of mechanical ventilation support, incidence rate of ventilator-associated pneumonia, 48-hour reintubation rate, incidence rate of upper gastrointestinal bleeding, hospitalization time of critical respiratory illness, total hospitalization time, RICU treatment cost, total treatment cost, and mortality. It is preferable to take the change rate of PCT level exceeding 50% as the switch point of weaning time in sequential mechanical ventilation rather than the PIC window. AbbreviationsAECOPD: acute exacerbation of chronic obstructive pulmonary disease; ARF: acute respiratory failure; PCT: procalcitonin; PaO2: the oxygen partial pressure; PaCO2: the partial pressure of carbon dioxide; TNF-a: serum tumor necrosis factor-a; IL-6: interleukin-6; CRP: serum C-reactive protein; PIC window: pulmonary infection control window; RICU: respiration and intensive care unit.