BACKGROUND

Determination of serum bicarbonate (HCO3 - ) using arterial blood gas analysis in patients with diabetic ketoacidosis allows for the evaluation of the severity of the condition, determines whether HCO3 - therapy is required, and tracks the progression and resolution of the disease. Serum carbon dioxide combining power (CO2CP) from venous chemistry analysis has often been used as an indicator of metabolic acidosis. This study investigated the relationship between HCO3 - and CO2CP and developed an approximation formula for serum bicarbonate concentration using its predictor variables, as this may lessen the need to repeat arterial blood gas analysis or be used in settings in which blood gas analyzers are unavailable.

METHODOLOGY

This single-center, retrospective, cross-sectional study investigated a total of 77 patients diagnosed with diabetic ketoacidosis. Assessment of the bivariate correlations between serum HCO3 - and serum CO2CP as well as other potential predictor variables was done via Pearson’s correlation coefficient. Predictor variables that were significantly correlated with serum HCO3 - were identified and an approximation formula was developed by regression analysis. Evaluation of the correlation between the approximated HCO3 - value and the actual serum HCO3 - concentration was performed using correlation coefficient and residual statistics to assess agreement.

RESULTS

Serum CO2CP had significant correlation with serum HCO3 - (r = 0.768, p < 0.05). By multiple regression analysis, the following approximation formula was therefore expressed: HCO3 - = 12.682 + (0.612 x CO2CP) – [ketones] + (0.085 x BUN) - (0.026 x SGPT) – (1.23 x Creatinine) - (0.067 x Chloride). Examination of residuals revealed a mean of zero (0), indicating no significant difference between the actual and approximated levels of serum HCO3 -

CONCLUSION

The predictor variables included in the formula collectively contribute significantly to the approximation of serum HCO3 - . The approximated serum HCO3 - values also showed significant correlation with actual serum HCO3 - concentration; thus, the formula may be utilized to derive an approximation of serum bicarbonate concentration in patients with diabetic ketoacidosis.

Human ; Male ; Female ; Adolescent: 13-18 Yrs Old ; Young Adult: 19-24 Yrs Old ; Adult: 25-44 Yrs Old ; Attention ; Bicarbonates ; Carbon Dioxide ; Diabetic Ketoacidosis ; Ketosis ; Patients ; Carbon ; Power (psychology) ; Power, Psychological ; Serum

In this study, high-throughput promoter screening was employed to optimize the heterologous expression of Mesorhizobium loti carbonic anhydrase (MlCA) in order to reduce the costs associated with carbon capture and storage (CCS). To simplify the complexity of traditional vectors, a fusion protein expression system was constructed using superfolder green fluorescent protein (sfGFP) and MlCA. The synthetic promoter library in Escherichia coli was utilized for efficient one-step screening. Based on fluorescence intensity on agar plates, a total of 143 monoclonal colonies were identified, forming a library with varying expression levels. The top four recombinants with the highest fluorescence intensity were selected, among which MlCA driven by the promoter 342042/+ exhibited the highest enzymatic activity, with a specific activity of the 34.6 Wilbur-Anderson units (WAU)/mg. Optimization experiments revealed that MlCA exhibited the best performance when cultured for 4 days under pH 7.0 and 40 ℃ conditions. The Michaelis constant (K_m·hdy) and maximum reaction rate (V_max·hdy) for CO₂ hydration were determined to be 62.46 mmol/L and 0.164 mmol/(s·L), respectively. For esterase hydrolysis, MlCA showed the K_m and V_max of 639.8 mmol/L and 0.035 mmol/(s·L), respectively. MlCA accelerated the CO₂ hydration process, promoting CO₂ mineralized into CaCO₃ within 9 min at low pH and room temperature conditions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirmed that the precipitated product was calcite. This study provides a low-cost and environmentally friendly alternative for future CCS applications.
Carbonic Anhydrases/biosynthesis* ; Promoter Regions, Genetic/genetics* ; Escherichia coli/metabolism* ; Carbon Sequestration ; Carbon Dioxide/metabolism* ; Green Fluorescent Proteins/metabolism*

Small urban wetlands are widely distributed and susceptible to human activities, serving as important sources and sinks of carbon. Microorganisms play a crucial role in carbon cycle, while limited studies have been conducted on the microbial diversity in small urban wetlands and the functions of microbiome in carbon fixation and metabolism. To probe into the microbiome-driven carbon cycling in small urban wetlands and dissect the composition and functional groups of microbiome, we analyzed the relationships between the microbiome structure, element metabolism pathways, and habitat physicochemical properties in sediment samples across three small wetlands in Huzhou City, and compared them with natural wetlands in the Zoige wetland. High-throughput sequencing of 16S rRNA gene amplicons and metagenomics was employed to determine the species and functional groups. Sixty medium to high-quality metagenome-assembled genomes (MAGs) were constructed, including 55 bacterial and 5 archaeal taxa, and their potential in driving elemental cycles were analyzed, with a focus on carbon fixation. Several bacterial species were found to encode a nearly complete carbon fixation pathway, including the Calvin cycle, the reductive tricarboxylic acid cycle, the Wood-Ljungdahl pathway, and the reductive glycine pathway. There were several potential novel carbon-fixing bacterial members, such as those belonging to Syntrophorhabdus (Desulfobacterota) and UBA4417 (Bacteroidetes), which had high relative abundance in the wetland microbiome. Unveiling the genetic potential of these functional groups to facilitate element cycling is of great scientific importance for enhancing the carbon sequestration capacity of small urban wetlands.
Wetlands ; Microbiota/genetics* ; Carbon Cycle/genetics* ; Bacteria/classification* ; RNA, Ribosomal, 16S/genetics* ; China ; Cities ; Geologic Sediments/microbiology* ; Archaea/classification* ; Metagenomics ; Metagenome

Microalgae possess high photosynthetic efficiency, robust adaptability, and substantial biomass, serving as excellent biological resources for large-scale cultivation. Malic enzyme (ME), a ubiquitous metabolic enzyme in living organisms, catalyzes the decarboxylation of malate to produce pyruvate, CO₂, and NAD(P)H, playing a role in multiple metabolic pathways including energy metabolism, photosynthesis, respiration, and biosynthesis. In this study, we identified the Scenedesmus quadricauda malic enzyme gene (SqME) and its biological functions, aiming to provide excellent target genes for the genetic improvement of higher plants. Based on the RNA-seq data from S. quadricauda under the biofilm cultivation mode with high CO₂ and light energy transfer efficiency and small water use, a highly expressed gene (SqME) functionally annotated as ME was cloned. The physicochemical properties of the SqME-encoded protein were systematically analyzed by bioinformatics tools. The subcellular localization of SqME was determined via transient transformation in Nicotiana benthamiana leaves. The biological functions of SqME were identified via genetic transformation in Nicotiana tabacum, and the potential of SqME in the genetic improvement of higher plants was evaluated. The ORF of SqME was 1 770 bp, encoding 590 amino acid residues, and the encoded protein was located in chloroplasts. SqME was a NADP-ME, with the typical structural characteristics of ME. The ME activity in the transgenic N. tabacum plant was 1.8 folds of that in the wild-type control. Heterologous expression of SqME increased the content of chlorophyll a, chlorophyll b, and total chlorophyll by 20.9%, 26.9%, and 25.2%, respectively, compared with the control. The transgenic tobacco leaves showed an increase of 54.0% in the fluorescence parameter NPQ and a decrease of 30.1% in Fo compared with the control. Moreover, the biomass, total lipids, and soluble sugars in the transgenic tobacco leaves enhanced by 20.5%, 25.7%, and 9.5%, respectively. On the contrary, the starch and protein content in the transgenic tobacco leaves decreased by 22.4% and 12.2%, respectively. Collectively, the SqME-encoded protein exhibited a strong enzymatic activity. Heterologous expressing of SqME could significantly enhance photosynthetic protection, photosynthesis, and biomass accumulation in the host. Additionally, SqME can facilitate carbon metabolism remodeling in the host, driving more carbon flux towards lipid synthesis. Therefore, SqME can be applied in the genetic improvement of higher plants for enhancing photosynthetic carbon fixation and lipid accumulation. These findings provide scientific references for mining of functional genes from S. quadricauda and application of these genes in the genetic engineering of higher plants.
Nicotiana/genetics* ; Photosynthesis/physiology* ; Malate Dehydrogenase/biosynthesis* ; Plant Leaves/genetics* ; Scenedesmus/enzymology* ; Carbon Cycle/genetics* ; Lipid Metabolism/genetics* ; Plants, Genetically Modified/metabolism*

The escalating pressure from global population growth, climate change, and resource consumption is intensifying the burden on traditional agricultural production. Against this backdrop, soil degradation and pollution present increasingly severe challenges, creating a vicious cycle with rising food demands. Maintaining soil health and its ecosystem services has thus become a critical prerequisite for achieving sustainable agriculture in the future. This review explores the impacts of soil carbon (C) and nitrogen (N) dynamics on soil microbial communities and their interactions. Soil C and N are key determinants of microbial diversity and community structure, intrinsically linked to soil C/N cycling, crop productivity, and ecological balance. Environmental factors such as nitrogen fertilizer application, organic matter amendment application, litter decomposition, elevated CO₂ concentrations, and nitrogen deposition significantly influence soil C and N dynamics. Changes in soil C and N content regulate microbial community dynamics and the synergistic, competitive, and antagonistic interactions among microorganisms. Meanwhile, microbial communities actively respond to alterations in soil C and N availability. The resulting shifts in microbial communities and their interactions subsequently regulate soil C/N cycling and ecosystem stability, ultimately influencing ecosystem functions. By elucidating the mechanisms underlying soil carbon-nitrogen-microbial interactions, this review significantly advances our understanding of soil ecosystem responses and feedback mechanisms in the context of global change, while also providing crucial practical guidance for enhancing soil fertility and promoting sustainable agricultural development through microbial regulation.
Soil Microbiology ; Nitrogen/metabolism* ; Carbon/metabolism* ; Soil/chemistry* ; Bacteria/growth & development* ; Fungi/metabolism* ; Ecosystem ; Fertilizers ; Agriculture

Case 1: A 19-day-old male infant presented with poor feeding and decreased activity for 2 weeks, worsening with poor responsiveness for 3 days. At 5 days old, he developed poor feeding and poor responsiveness, was hospitalized, and was found to have elevated blood ammonia and thrombocytopenia. Whole-genome genetic analysis revealed a pathogenic homozygous mutation in the PCCA gene, NM-000282.4: c.1834-1835del (p.Arg612AspfsTer44), leading to a diagnosis of propionic acidemia. Case 2: A 4-day-old male infant presented with poor responsiveness and feeding difficulties since birth, with elevated blood ammonia for 1 day. He showed weak sucking and deteriorating responsiveness, with blood ammonia >200 µmol/L. Genetic testing identified two heterozygous mutations in the MMUT gene: NM_000255.4: c.1677-1G>A and NM_000255.4: ex.5del, confirming methylmalonic acidemia. Case 3: A 20-day-old male infant presented with poor feeding for 15 days and skin petechiae for 8 days. He developed feeding difficulties at 5 days old and lower limb petechiae at 12 days old, with blood ammonia measured at 551.6 µmol/L. Genetic analysis found two heterozygous mutations in the PCCA gene: NM_000282.4: c.1118T>A (p.Met373Lys) and NM_000282.4: ex.16-18del, confirming propionic acidemia. In the first two cases, continuous hemodiafiltration was performed for 30 hours and 20 hours, respectively, before administering carglumic acid. In the third case, carglumic acid was administered orally without continuous hemodiafiltration, resulting in a decrease in blood ammonia from 551.6 µmol/L to 72.0 µmol/L within 6 hours, with a reduction rate of approximately 20-25 µmol/(kg·h), similar to the first two cases. Carglumic acid was effective in all three cases, suggesting it may help optimize future treatment protocols for organic acidemia.
Humans ; Male ; Infant, Newborn ; Propionic Acidemia/drug therapy* ; Amino Acid Metabolism, Inborn Errors/genetics* ; Mutation ; Methylmalonyl-CoA Decarboxylase/genetics* ; Citrates/administration & dosage* ; Carbon-Carbon Ligases/genetics* ; Glutamates

BACKGROUND: Cancer is a major public health concern, particularly among middle-aged and elderly populations, who are disproportionately affected by rising cancer incidence. Environmental pollution has been identified as a significant risk factor for cancer development. China's Carbon Emission Trading Policy (CETP), implemented in pilot regions since 2013, aims to reduce carbon emissions and improve air quality. This study evaluates the impact of CETP on pan-cancer incidence, with a focus on its effects on specific cancer types and vulnerable populations. METHODS: This quasi-natural experiment utilized data from the China Health and Retirement Longitudinal Study (CHARLS) and environmental data from the China National Environmental Monitoring Center (2011-2018). A staggered difference-in-differences (DID) model was employed to estimate the impact of CETP on cancer incidence. Robustness tests, including parallel trend tests, placebo analysis, and entropy balancing, validated the findings. Subgroup analyses were performed to assess the policy's heterogeneous effects based on gender, Body Mass Index (BMI), and smoking status. RESULTS: CETP implementation significantly reduced the incidence of six cancer types: endometrial, cervical, gastric, esophageal, breast, and lung cancers. Overall, pan-cancer incidence significantly declined post-policy implementation (CETP × POST: -47.200, 95% CI: [-61.103, -33.296], p < 0.001). The policy demonstrated stronger effects in highly polluted areas and among individuals with poorer mental health. Subgroup analysis revealed that females, individuals with lower BMI, and non-smokers experienced more substantial benefits. CONCLUSIONS CETP significantly reduces cancer incidence by improving environmental quality and influencing mental health, with particularly strong effects observed among high-risk populations. This study highlights the important role of environmental economic policies in mitigating cancer burden and promoting public health. Future research should further explore the long-term impacts of this policy and its applicability across different national and regional contexts.
Humans ; Incidence ; Neoplasms/epidemiology* ; China/epidemiology* ; Middle Aged ; Female ; Male ; Aged ; Air Pollution/legislation & jurisprudence* ; Carbon/analysis* ; Longitudinal Studies ; Air Pollutants/analysis* ; Environmental Exposure

End-tidal carbon dioxide monitoring is an important means of evaluating human lung function and is widely used in fields such as clinical emergency treatment and cardiopulmonary resuscitation. This paper develops a microstream end-tidal carbon dioxide monitoring system. It adopts an integrated gas circuit design to further reduce the size of the equipment. The system uses the method of calculating the root mean square (RMS) of differential pressure signals to regulate the gas circuit flow, enabling the system to stably operate at a flow state of 30 mL/min. In addition, by simultaneously detecting multiple environmental parameters such as temperature and pressure, the system realizes system state monitoring and gas parameter compensation. The test results show that various indicators of the system meet the requirements of relevant standards, laying a good foundation for subsequent engineering applications.
Carbon Dioxide/analysis* ; Equipment Design ; Monitoring, Physiologic/methods* ; Humans

OBJECTIVES: The neurotoxicity of carbon monoxide (CO) to the central nervous system is a key pathogenesis of delayed encephalopathy after acute carbon monoxide poisoning (DEACMP). Our previous study found that retinoic acid (RA) can suppress the neurotoxic effects of CO. This study further explores, in vivo and in vitro, the molecular mechanisms by which RA alleviates CO-induced central nervous system damage. METHODS: A cytotoxic model was established using the mouse hippocampal neuronal cell line HT22 and primary oligodendrocytes exposed to CO, and a DEACMP animal model was established in adult Kunming mice. Cell viability and apoptosis of hippocampal neurons and oligodendrocytes were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Annexin V/propidium iodide (PI) double staining. The transcriptional and protein expression of each gene was detected using real-time fluorescence quantitative PCR (RT-qPCR) and Western blotting. Long noncoding RNA (lncRNA) SNHG15 and LINGO-1 were knocked down or overexpressed to observe changes in neurons and oligodendrocytes. In DEACMP mice, SNHG15 or LINGO-1 were knocked down to assess changes in central nervous tissue and downstream protein expression. RESULTS: RA at 10 and 20 μmol/L significantly reversed CO-induced apoptosis of hippocampal neurons and oligodendrocytes, downregulation of SNHG15 and LINGO-1, and upregulation of brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB) (all P<0.05). Overexpression of SNHG15 or LINGO-1 weakened the protective effect of RA against CO-induced cytotoxicity (all P<0.05). Knockdown of SNHG15 or LINGO-1 alleviated CO-induced apoptosis of hippocampal neurons and oligodendrocytes and upregulated BDNF and TrkB expression levels (all P<0.05). Experiments in DEACMP model mice showed that knockdown of SNHG15 or LINGO-1 mitigated central nervous system injury in DEACMP (all P<0.05). CONCLUSIONS RA alleviates CO-induced apoptosis of hippocampal neurons and oligodendrocytes, thereby reducing central nervous system injury and exerting neuroprotective effects. LncRNA SNHG15 and LINGO-1 are key molecules mediating RA-induced inhibition of neuronal apoptosis and are associated with the BDNF/TrkB pathway. These findings provide a theoretical framework for optimizing the clinical treatment of DEACMP and lay an experimental foundation for elucidating its molecular mechanisms.
Animals ; RNA, Long Noncoding/physiology* ; Brain-Derived Neurotrophic Factor/genetics* ; Carbon Monoxide Poisoning/complications* ; Mice ; Tretinoin/pharmacology* ; Nerve Tissue Proteins/metabolism* ; Membrane Proteins/metabolism* ; Apoptosis/drug effects* ; Hippocampus/cytology* ; Receptor, trkB/metabolism* ; Neurons/drug effects* ; Male ; Brain Diseases/etiology* ; Oligodendroglia/drug effects* ; Signal Transduction ; Cell Line

OBJECTIVES: To prepare a stable mouse model of chronic liver fibrosis induced by dietary vitamin A (VA) deficiency combined with CCl₄ injections. METHODS: A total of 126 Balb/c mice were randomized into 3 groups for feeding with a normal VA diet or a VA-deficient diet containing 500 or 200 IU/kg VA. After 4 weeks of feeding, half of the mice in each group were given intraperitoneal injections of 5% CCl₄ (10 mL/kg, twice a week) for 8 weeks. Serum retinol, ALT/AST and liver index of the mice were examined, liver tissue pathologies were observed with HE and Masson staining, and liver fibrosis score and oxidative stress level were evaluated. RESULTS: Four weeks of VA-deficient feeding, especially at 200 IU/kg, significantly lowered serum retinol level of the mice. CCl₄ injections for 8 weeks obviously increased liver index and ALT/AST and caused obvious liver fibrosis in all the mice, but liver pathologies were more severe in the 2 VA-deficient groups; severe liver necrosis with inflammatory cell infiltration was observed in 200 IU/kg VA group, where 2 mice died. After discontinuation of CCl₄, the mice with normal dietary VA showed gradual recovery of the liver index, ALT/AST, liver cord structure and liver fibrosis; the mice with VA deficiency, however, showed no significant improvements in these parameters, and the mice with 200 IU/kg VA still had serious abdominal adhesion, false lobules and massive inflammatory cell infiltration with a fibrosis stage score of 3. The oxidative damage index 8-OHdG was significantly higher in 500 IU/kg VA group than in normal VA group after CCl₄ modeling. CONCLUSIONS Feeding with diet containing 500 IU/kg VA for 4 weeks and 10 mL/kg CCl₄ injections for 8 weeks can result in stable moderate to severe liver fibrosis in mice without spontaneous reversal at 8 weeks of drug withdrawal.
Animals ; Mice ; Mice, Inbred BALB C ; Disease Models, Animal ; Carbon Tetrachloride ; Vitamin A Deficiency/complications* ; Male ; Liver Cirrhosis/etiology* ; Oxidative Stress ; Vitamin A/blood*