Assessment of acute radial artery injury after distal transradial access for coronary intervention: an optical coherence tomography study.

There is a paucity of data on acute radial artery (RA) injuries using optical coherence tomography (OCT) in patients undergoing coronary intervention via distal transradial coronary access (dTRA). To evaluate the incidence of acute RA injury following dTRA for coronary intervention using OCT. We retrospectively analyzed 200 consecutive patients with acute coronary syndrome (ACS) who underwent coronary intervention guided by OCT and RA-OCT after dTRA at our center between June 2021 and November 2022. Total length of RA was divided into three segments based on the sheath location during dTRA: no sheath protection portion (proximal RA segment) and sheath protection portion (divided into mid- and distal segments). Acute RA injuries, including tears, dissections, perforations, thrombi, and spasms, were analyzed. Radial artery occlusion (RAO) was assessed using ultrasonography 24 h after dTRA. Acute RA injury was observed in 45.5% of patients after dTRA. The incidence of tear, dissection, perforation, thrombi, and spasm in all the patients was 11.5%, 16.5%, 1.5%, 17.5%, and 17.5%, respectively. In segment-level analysis, dissection and spasm were significantly more frequent in the proximal segment, followed by the mid and distal segments (11.0% vs. 5.5% vs. 4.5%, P = 0.015; 13.0% vs. 4.0% vs. 4.5%, P = 0.002). The rate of RAO at 24-h follow-up was 3.0%. Acute RA injuries were observed in nearly half of the patients using OCT via dTRA; dissection and spasm occurred more frequently in the proximal segment. Hydrophilic-coated sheaths have the potential advantage of preventing radial artery spasm and dissection.

A Novel Cell Membrane-Associated RNA Extraction Method and Its Application in the Discovery of Breast Cancer Markers.

Cell membrane-associated RNA (mem-RNA) has been demonstrated to be cell-specific and disease-related and are considered as potential biomarkers for disease diagnostics, drug delivery, and cell screening. However, there is still a lack of methods specifically designed to extract mem-RNA from cells, limiting the discovery and applications of mem-RNA. In this study, we propose the first all-in-one solution for high-purity mem-RNA isolation based on two types of magnetic nanoparticles, named MREMB (Membrane-associated RNA Extraction based on Magnetic Beads), which achieved ten times enrichment of cell membrane components and over 90% recovery rate of RNA extraction. To demonstrate MREMB's potential in clinical research, we extracted and sequenced mem-RNA of typical breast cancer MCF-7, MDA-MB-231, and SKBR-3 cell lines and non-neoplastic breast epithelial cell MCF-10A. Compared to total RNA, sequencing results revealed that membrane/secreted protein-encoding mRNAs and long noncoding RNAs (lncRNAs) were enriched in the mem-RNA, some of which were significantly overexpressed in the three cancer cell lines, including extracellular matrix-related genes COL5A1 and lncRNA TALAM1. The results indicated that MREMB could enrich membrane/secreted protein-coding RNA and amplify the expression differences of related RNAs between cancer and non-neoplastic cells, promising for cancer biomarker discovery.

Bone marrow mesenchymal stem cell-derived exosomal miR-30e-5p ameliorates high-glucose induced renal proximal tubular cell pyroptosis by inhibiting ELAVL1.

BACKGROUND: The rapid increase in the prevalence of diabetes has resulted in more cases of diabetic kidney disease (DKD). Treatment with bone marrow mesenchymal stem cells (BMSCs) may represent an alternative strategy to manage DKD. METHODS: HK-2 cells were treated with 30 mM high glucose (HG). Bone marrow MSC-derived exosomes (BMSC-exos) were isolated and internalized into HK-2 cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) and lactate dehydrogenase (LDH) assays were used to measure viability and cytotoxicity. The secretion of IL-1ß and IL-18 was measured by ELISA. Pyroptosis was assessed by flow cytometry. Quantitative RT-PCR was used to measure the levels of miR-30e-5p, ELAV like RNA binding protein 1 (ELAVL1), IL-1ß, and IL-18. The expression of ELAVL1 and pyroptosis-associated cytokine proteins was determined by western blot analysis. A dual-luciferase reporter gene assay was conducted to confirm the relationship between miR-30e-5p and ELAVL1. RESULTS: BMSC-exos decreased LDH, IL-1ß, and IL-18 secretion and inhibited the expression of the pyroptosis-related factors (IL-1ß, caspase-1, GSDMD-N, and NLRP3) in HG-induced HK-2 cells. Moreover, miR-30e-5p depletion derived from BMSC-exos promoted HK-2 cell pyroptosis. Besides, miR-30e-5p over-expression or ELVAL1 knockdown could directly inhibit pyroptosis. ELAVL1 was a target of miR-30e-5p and knocking down ELAVL1 reversed the effect of miR-30e-5p inhibition in BMSC-exos-treated HK-2 cells. CONCLUSIONS: BMSC-derived exosomal miR-30e-5p inhibits caspase-1-mediated pyroptosis by targeting ELAVL1 in HG-induced HK-2 cells, which might provide a new strategy for treating DKD.

Effects of contralateral nephrectomy timing and ischemic conditions on kidney fibrosis after unilateral kidney ischemia-reperfusion injury.

Acute kidney injury (AKI) is an important cause of chronic kidney disease (CKD), but the underlying mechanisms are unclear. Animal models are tools for studying the AKI-CKD progression. Kidney ischemia-reperfusion injury (IRI) models, especially the unilateral IRI (uIRI) model with delayed contralateral kidney resection, are commonly used to induce fibrotic progression to CKD after AKI. However, in previous studies, we found that details of the operation had a significant impact on the long-term outcomes of the kidney in this uIRI model. In this study, we investigated the effects of resection timing of the contralateral intact kidney, core body temperatures during ischemia, and time length of kidney ischemia on kidney function, histological injury and kidney fibrosis after AKI, using a mouse uIRI model with delayed contralateral nephrectomy. The results showed that all these parameters significantly affected the AKI-CKD transition. The post-AKI fibrosis worsened and the survival rate declined with a longer interval between contralateral nephrectomy and uIRI, higher ischemic body temperature, or longer ischemic duration when the other two variables were fixed. In conclusion, in the uIRI model with delayed contralateral nephrectomy, kidney fibrosis after AKI is influenced by many factors. Strictly controlling the experimental conditions is very important for the stability and consistency of the model.

Bivalirudin vs. Heparin on Radial Artery Thrombosis during Transradial Coronary Intervention: An Optical Coherence Tomography Study.

OBJECTIVES: This study aimed to evaluate the antithrombotic efficacy between bivalirudin and unfractionated heparin (UFH) on radial artery thrombosis (RAT) during transradial coronary intervention (TRI) by optical coherence tomography (OCT). METHODS AND RESULTS: We consecutively reviewed a total of 307 patients who underwent radial artery OCT inspection after TRI in our centre from October 2017 to January 2019; afterwards, 211 screened patients were divided into the UFH group (n = 144) and the bivalirudin group (n = 67) according to their anticoagulation strategy during TRI. The thrombosis in the radial artery was observed in 51 cases (24.17%) with a median thrombus volume of 0.054 mm3 (0.024, 0.334) and median thrombus score of 7 (4, 15). Thrombus occurred in 28 cases in the bivalirudin group with an incidence of 41.8%, which was significantly higher than that in the UFH group (n = 23, 16.0%, P < 0.001). This difference was even more remarkable after propensity score matching (bivalirudin group n = 22, 42.3% vs. UHF group n = 11, 13.9%, P < 0.001). Multivariate logistic analysis revealed that bivalirudin increased the RAT risk by 3.872 times (95% CI 2.006-8.354, P < 0.001) after adjustment for the other predictors. CONCLUSION: In this present study, the use of bivalirudin was associated with a higher risk of RAT than UFH. It highlighted UFH should be a more considerable choice to prevent radial artery access thrombosis in TRI.

Prognostic significance of TOP2A in non-small cell lung cancer revealed by bioinformatic analysis.

BACKGROUND: Lung cancer has been a common malignant tumor with a leading cause of morbidity and mortality, current molecular targets are woefully lacking comparing to the highly progressive cancer. The study is designed to identify new prognostic predictors and potential gene targets based on bioinformatic analysis of Gene Expression Omnibus (GEO) database. METHODS: Four cDNA expression profiles GSE19188, GSE101929, GSE18842 and GSE33532 were chosen from GEO database to analyze the differently expressed genes (DEGs) between non-small cell lung cancer (NSCLC) and normal lung tissues. After the DEGs functions were analyzed, the protein-protein interaction network (PPI) of DEGs were constructed, and the core gene in the network which has high connectivity degree with other genes was identified. We analyzed the association of the gene with the development of NSCLC as well as its prognosis. Lastly we explored the conceivable signaling mechanism of the gene regulation during the development of NSCLC. RESULTS: A total of 92 up regulated and 214 down regulated DEGs were shared in four cDNA expression profiles. Based on their PPI network, TOP2A was connected with most of other genes and was selected for further analysis. Kaplan-Meier overall survival analysis (OS) revealed that TOP2A was associated with worse NSCLC patients survival. And both GEPIA analysis and immunohistochemistry experiment (IHC) confirmed that TOP2A was aberrant gain of expression in cancer comparing to normal tissues. The clinical significance of TOP2A and probable signaling pathways it involved in were further explored, and a positive correlation between TOP2A and TPX2 expression was found in lung cancer tissues. CONCLUSION: Using bioinformatic analysis, we revealed that TOP2A could be adopted as a prognostic indicator of NSCLC and it potentially regulate cancer development through co-work with TPX2. However, more detailed experiments are needed to clarify its drug target role in clinical medical use.

Rs1520220 and Rs2195239 Polymorphisms of IGF-1 Gene Associated with Histopathological Grades in IgA Nephropathy in Northwestern Chinese Han Population.

BACKGROUND/AIMS: Insulin-like growth factor-1 (IGF-1) plays important roles in cellular proliferation, differentiation, and growth. Previous studies showed that single-nucleotide polymorphisms (SNPs) of IGF-1 are associated with various diseases. This case-control study aimed to examine the relationship between IGF-1 polymorphisms and IgA nephropathy (IgAN) risk in a Chinese Han population. METHODS: We recruited 351 IgAN patients and 310 healthy controls from Northwestern China. Sequenom MassARRAY was utilized to examine the genotypes of two common IGF-1 SNPs (rs1520220 and rs2195239). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by the Chi square test to evaluate the associations between IGF-1 and IgAN. RESULTS: Our study demonstrated that IGF-1 gene rs1520220 and rs2195239 polymorphisms did not confer susceptibility to IgAN. We found no correlation between gender, blood pressure, proteinuria, eGFR, and IgAN in both SNPs. However, the rs1520220 and rs2195239 variants were correlated with M1 and E1 in patients with IgAN (M0/M1: CC vs. CG+GG: OR = 1.62, P = 0.04; E0/E1: CC vs. CG+GG: OR = 1.95, P = 0.004; GG vs. GC+CC: OR = 1.90, P = 0.004, respectively). CONCLUSION: These results indicate that IGF-1 gene polymorphisms play crucial roles in the histopathological progression of IgAN in the Chinese Han population.

Association Between IFN-γ Gene Polymorphisms and IgA Nephropathy in a Chinese Han Population.

BACKGROUND/AIMS: IFN-γ was reported to be involved in the development and progression of Immunoglobulin A nephropathy (IgAN), however, few studies have investigated the association between IFN-γ polymorphisms and IgAN. Therefore, we performed a case-control study to assess the association between IFN-γ polymorphisms and the risk of IgAN. METHODS: Sequenom MassARRAY was used to genotype two SNPs (rs1861494 and rs2430561) in 351 patients with IgAN and 310 healthy controls. Associations were evaluated as odd ratios (OR) with 95% confidence intervals (CI). RESULTS: No association was found between IFN-γ rs1861494 and IgAN risk or clinical parameters. For rs2430561, the AA genotype was more common in patients with IgAN, compared with controls (AT vs. AA: OR = 0.57, P = 0.035). IFN-γ-rs2430561 T allele may be a protective factor for IgAN susceptibility (T vs. A: OR = 0.59, P = 0.04). Subgroup analysis based on clinical features revealed no significant association between rs2430561 polymorphism and clinical data such as gender, 24-h urine protein, blood pressure, Oxford classifcation and estimated glomerular fltration rate. IgAN patients had a higher IFN-γ serum level than healthy controls and patients with rs1861494 AA genotype had a higher IFN-γ serum level compared with those with AG/GG genotypes. CONCLUSIONS: IFN-γ polymorphisms may be involved in the development and progression of IgAN.

Association of Interleukin-10 Polymorphisms (rs1800872, rs1800871, and rs1800896) with Predisposition to IgA Nephropathy in a Chinese Han Population: A Case-Control Study.

BACKGROUND/AIMS: IgA nephropathy (IgAN) is a common form of primary glomerulonephritis worldwide. Previous studies indicated that IL-10 single nucleotide polymorphisms (SNP) play an important role in IgAN pathogenesis, but the results were controversy. This study aimed to investigate the association between IL-10 SNPs (rs1800872, rs1800871, and rs1800896) with IgAN in a Chinese Han population. METHODS: We conducted a case-control study that included 351 patients with IgAN and 310 age-, gender- and ethnicity-matched healthy controls. Three promoter SNPs (rs1800872, rs1800871, and rs1800896) of IL-10 were genotyped by Sequenom MassARRAY. Odds ratios (ORs) with 95% confidence intervals (CI) were used to assess the relationship with IgAN. RESULTS: We found that the rs1800896 did not correlate with IgAN risk, whereas rs1800872 and rs1800871 were significantly associated with increased IgAN risk in all genetic models. The haplotype analysis indicated that the CCA haplotype was associated with increased IgAN risk (OR = 1.36; 95% CI = 1.05-1.75). Moreover, there were no associations between these SNPs and blood pressure or gender, whereas the rs1800896 variant was correlated with higher 24-hour urine protein in patients with IgAN. CONCLUSION: Taken together, these results suggest that IL-10 is a susceptibility gene in patients with IgAN.

The Endothelial Nitric Oxide Synthase Gene Polymorphism is Associated with the Susceptibility to Immunoglobulin a Nephropathy in Chinese Population.

BACKGROUND/AIMS: Endothelial nitric oxide synthase (eNOS) is one of the most important enzymes for producting nitric oxide (NO), which regulate the function of many organs and cells. The single nucleotide polymorphisms (SNPs) of eNOS were found to be associated with many kidney diseases. However, it is lack of relevant studies to evaluate the associations between eNOS polymorphisms and immunoglobulin A nephropathy (IgAN). This case-control study aimed to evaluate the relationship between eNOS polymorphisms and IgAN. METHODS: We recruited 351 IgAN patients and 310 age- and sex-matched healthy controls from Northwest China. Sequenom MassARRAY was used to detect the genotypes of two common eNOS SNPs (rs1799983 and rs2070744). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by the Chi square test to evaluate the associations between eNOS and IgAN. Phase 2.1 was used to conduct haplotype analysis. RESULTS: In the overall analysis, we found that the rs1799983 polymorphism was associated with a decreased risk of IgAN (G/T vs. G/G: OR=0.57, 95%CI=0.34-0.96; G/T+T/T vs. G/G: OR=0.52, 95%CI=0.31-0.86; G/T vs. G/G-T/T: OR=0.60, 95%CI=0.36-0.99; Log-additive model: OR=0.48, 95%CI=0.30-0.78). Haplotype analysis indicated that Trs1799983Crs2070744 is a protective factor against IgAN (OR=0.62, 95%CI=0.42--0.92). However, no significant differences were found between the two SNPs (rs1799983 and rs2070744) and clinical features (age, sex, blood pressure, and Lee's grade) of IgAN. CONCLUSION: The eNOS gene rs1799983 polymorphism and Trs1799983Crs2070744 haplotype may reduce the risk of IgAN in Chinese populations.

Association between CCDC132, FDX1 and TNFSF13 gene polymorphisms and the risk of IgA nephropathy.

AIM: Previous genome-wide association studies have identified multiple susceptibility loci for IgA nephropathy (IgAN); however, validation of these findings is still needed. METHODS: We performed a case-control study among 347 Chinese Han IgAN patients and 310 ethnicity-matched controls. Twenty-two single nucleotide polymorphisms (SNPs) were genotyped and association analysis was performed. RESULTS: We found three alleles for IgAN in patients: the allele "C" of rs2188404 in the CCDC132 gene by recessive model (odds ratio (OR), 1.65; 95% confidence interval (CI), 1.10-2.48; P = 0.014) and additive model (OR, 1.29; 95% CI, 1.03-1.61; P = 0.024) analysis, respectively, the allele "A" of rs10488764 in FDX1 gene by additive model (OR, 1.27; 95% CI, 1.00-1.61; P = 0.048) analysis, the allele "A" of rs3803800 in TNFSF13 gene by recessive model (OR, 2.05; 95% CI, 1.16-3.62; P = 0.010) and additive model (OR, 1.35; 95% CI, 1.06-1.72; P = 0.013) analysis, respectively. However, the associations between these SNPs and the risk of IgAN were not significant when adjusted for age and sex. Additionally, we found polymorphisms of rs2188404, rs10488764 and rs3803800 were correlated with urine protein (UPRO), human serum albumin (HSA), total cholesterol (TC) and Lee's pathological grades. CONCLUSION: We did not find any positive association between these SNPs and the risk of IgAN after adjustment by age and sex, but did find a significant and strong correlation with relevant clinical pathological parameters. Our study may provide a new perspective to understanding the aetiology of IgAN.

Association of the podocyte phenotype with extracapillary hypercellularity in patients with diabetic kidney disease.

BACKGROUND: Extracapillary hypercellularity was recently identified as a poor prognostic factor for diabetic kidney disease (DKD), but its nature, pathogenesis, and relationship with glomerular sclerosis are still unclear. METHODS: We retrospectively studied 107 patients with biopsy-proven DKD, recruited from January 2018 through December 2020. We compared the clinicopathologic characteristics of 25 patients with extracapillary hypercellularity lesions (the extracapillary hypercellularity group) to those of 82 patients without extracapillary hypercellularity (the control group). Multiple cell-specific markers were used for immunohistochemical staining to analyse the types of cells that exhibited extracapillary hypercellularity. Podocyte phenotype changes were evaluated via immunohistochemical staining for Synaptopodin and Nephrin, and foot process width was measured via transmission electron microscopy. RESULTS: Patients with extracapillary hypercellularity lesions had more severe clinical features than patients without extracapillary hypercellularity in DKD, as indicated by elevated proteinuria and serum creatinine levels, and decreased serum albumin. Pathologically, extracapillary hypercellularity was accompanied by increased mesangial hyperplasia and interstitial fibrosis. Severe obliterative microvascular disease was observed more frequently in the extracapillary hypercellularity group than in the control group. At cell type analysis, 25 patients in the DKD-extracapillary hypercellularity group showed that a mixture of cells expressed either Wilm's tumor-1 or paired box protein 2. Furthermore, DKD-extracapillary hypercellularity patients had significant loss of podocyte phenotype and severe foot process effacement. Cells in extracapillary hypercellularity had increased hypoxia-induced factor-1 alpha expression. CONCLUSIONS: Extracapillary hypercellularity is associated with severe renal dysfunction and renal sclerosis. Vascular damage is closely related to severe podocyte hypoxia injury and requires additional attention in future research.

PCSK9 inhibitors suppress oxidative stress and inflammation in atherosclerotic development by promoting macrophage autophagy.

OBJECTIVES: Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, a novel class of cholesterol-lowering drugs, can reduce atherosclerosis independent of systemic lipid changes. However, the mechanism by which PCSK9 inhibition protects against arteriosclerosis has not been fully elucidated. Recent evidence has demonstrated a correlation between PCSK9 inhibitors and oxidative stress, which accelerates atherosclerotic development. Moreover, an increasing number of studies have shown that autophagy protects the vasculature against atherosclerosis. Therefore, the aims of this study were to investigate the effect of PCSK9 inhibition on oxidative stress and autophagy in atherosclerosis and determine whether autophagy regulates PCSK9 inhibition-mediated oxidative stress and inflammation in macrophages. METHODS: Male apolipoprotein E (ApoE)-/- mice were fed a high-fat diet (HFD) for 8 weeks and then received the PCSK9 inhibitor (evolocumab), vehicle, or evolocumab plus chloroquine (CQ) for another 8 weeks. ApoE-/- mice in the control group were fed a regular (i.e., non-high-fat) diet for 16 weeks. Additional in vitro experiments were performed in oxidized low-density lipoprotein (ox-LDL)-treated human acute monocytic leukemia cell line THP-1-derived macrophages to mimic the pathophysiologic process of atherosclerosis. RESULTS: PCSK9 inhibitor treatment reduced oxidative stress, lipid deposition, and plaque lesion area and induced autophagy in HFD-fed ApoE-/- mice. Most importantly, the administration of chloroquine (CQ), an autophagy inhibitor, significantly reduced the beneficial effects of PCSK9-inhibitor treatment on oxidative stress, lipid accumulation, inflammation, and atherosclerotic lesions in HFD-fed ApoE-/- mice. The in vitro experiments further showed that the PCSK9 inhibitor enhanced autophagic flux in ox-LDL-treated THP-1-derived macrophages, as indicated by increases in the numbers of autophagosomes and autolysosomes. Moreover, the autophagy inhibitor CQ also reduced PCSK9 inhibition-mediated protection against oxidative stress, generation of reactive oxygen species (ROS) and inflammation in ox-LDL-treated THP-1-derived macrophages. CONCLUSIONS: This study reveals a novel protective mechanism by which PCSK9 inhibition enhances autophagy and thereby reduces oxidative stress and inflammation in atherosclerosis.

A Silver Lining of Neuropathic Pain: Predicting Favorable Functional Outcome in Spinal Cord Injury.

Background: Neuropathic pain (NP) is a common and severe problem following spinal cord injury (SCI). However, its relationship with functional outcome remains unclear. Methods: A retrospective explorative analysis was performed on SCI patients admitted to a tertiary academic medical center between January 2018 and June 2022. The candidate predictor variables, including demographics, clinical characteristics and complications, were analyzed with logistic and linear regression. Spinal Cord Independence Measure (SCIM) scores at discharge and mean relative functional gain (mRFG) of SCIM were as outcome parameters. Results: A total of 140 SCI patients included for the final analysis. Among them, 44 (31.43%) patients were tetraplegics, and 96 (68.57%) patients were paraplegics; 68 (48.57%) patients developed NP, and 72 (51.43%) patients did not. Logistic and linear regression analyses of SCIM at discharge both showed that NP [OR=3.10, 95% CI (1.29,7.45), P=0.01; unstandardized ß=11.47, 95% CI (4.95,17.99), P<0.01; respectively] was significantly independent predictors for a favorable outcome (SCIM at discharge ≥ 50, logistic regression results) and higher SCIM total score at discharge (linear regression results). Besides, NP [unstandardized ß=15.67, 95% CI (8.94,22.41), P<0.01] was also independently associated with higher mRFG of SCIM scores. Furthermore, the NP group had significantly higher mRFG, SCIM total scores and subscales (self-care, respiration and sphincter management, and mobility) at discharge compared to the non-NP group. However, there were no significant differences in mRFG, SCIM total score or subscales at discharge among the NP subgroups in terms of locations (at level pain, below level pain, and both) or timing of occurrence (within and after one month after SCI). This study also showed that incomplete injury, lumbar-sacral injury level and non-anemia were significantly independent predictors for a favorable outcome, and higher mRFG of SCIM scores (except for non-anemia). Conclusion: NP appears independently associated with better functional recovery in SCI patients, suggesting the bright side of this undesirable complication. These findings may help to alleviate the psychological burden of NP patients and ultimately restore their confidence in rehabilitation.

Multiplexed discrimination of SARS-CoV-2 variants via plasmonic-enhanced fluorescence in a portable and automated device.

Portable assays for the rapid identification of lineages of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are needed to aid large-scale efforts in monitoring the evolution of the virus. Here we report a multiplexed assay in a microarray format for the detection, via isothermal amplification and plasmonic-gold-enhanced near-infrared fluorescence, of variants of SARS-CoV-2. The assay, which has single-nucleotide specificity for variant discrimination, single-RNA-copy sensitivity and does not require RNA extraction, discriminated 12 lineages of SARS-CoV-2 (in three mutational hotspots of the Spike protein) and detected the virus in nasopharyngeal swabs from 1,034 individuals at 98.8% sensitivity and 100% specificity, with 97.6% concordance with genome sequencing in variant discrimination. We also report a compact, portable and fully automated device integrating the entire swab-to-result workflow and amenable to the point-of-care detection of SARS-CoV-2 variants. Portable, rapid, accurate and multiplexed assays for the detection of SARS-CoV-2 variants and lineages may facilitate variant-surveillance efforts.

Genetically switched D-lactate production in Escherichia coli.

During a fermentation process, the formation of the desired product during the cell growth phase competes with the biomass for substrates or inhibits cell growth directly, which results in a decrease in production efficiency. A genetic switch is required to precisely separate growth from production and to simplify the fermentation process. The ldhA promoter, which encodes the fermentative D-lactate dehydrogenase (LDH) in the lactate producer Escherichia coli CICIM B0013-070 (ack-pta pps pflB dld poxB adhE frdA), was replaced with the λ p(R) and p(L) promoters (as a genetic switch) using genomic recombination and the thermo-controllable strain B0013-070B (B0013-070, ldhAp::kan-cI(ts)857-p(R)-p(L)), which could produce two-fold higher LDH activity at 42°C than the B0013-070 strain, was created. When the genetic switch was turned off at 33°C, strain B0013-070B produced 10% more biomass aerobically than strain B0013-070 and produced only trace levels of lactate which could reduce the growth inhibition caused by oxygen insufficiency in large scale fermentation. However, 42°C is the most efficient temperature for switching on lactate production. The volumetric productivity of B0013-070B improved by 9% compared to that of strain B0013-070 when it was grown aerobically at 33°C with a short thermo-induction at 42°C and then switched to the production phase at 42°C. In a bioreactor experiment using scaled-up conditions that were optimized in a shake flask experiment, strain B0013-070B produced 122.8 g/l D-lactate with an increased oxygen-limited productivity of 0.89 g/g·h. The results revealed the effectiveness of using a genetic switch to regulate cell growth and the production of a metabolic compound.

Improvement of D-lactate productivity in recombinant Escherichia coli by coupling production with growth.

Coupling lactate fermentation with cell growth was investigated in shake-flask and bioreactor cultivation systems by increasing aeration to improve lactate productivity in Escherichia coli CICIM B0013-070 (ackA pta pps pflB dld poxB adhE frdA). In shake-flasks, cells reached 1 g dry wt/l then, cultivated at 100 rpm and 42°C, achieved a twofold higher productivity of lactic acid compared to aerobic and O(2)-limited two-phase fermentation. The cells in the bioreactor yielded an overall volumetric productivity of 5.5 g/l h and a yield of 86 g lactic acid/100 g glucose which were 66% higher and the same level compared to that of the aerobic and O(2)-limited two-phase fermentation, respectively, using scaled-up conditions optimized from shake-flask experiments. These results have revealed an approach for improving production of fermentative products in E. coli.

Fine tuning the transcription of ldhA for D-lactate production.

Fine tuning of the key enzymes to moderate rather than high expression levels could overproduce the desired metabolic products without inhibiting cell growth. The aims of this investigation were to regulate rates of lactate production and cell growth in recombinant Escherichia coli through promoter engineering and to evaluate the transcriptional function of the upstream region of ldhA (encoding fermentative lactate dehydrogenase in E. coli). Twelve ldhA genes with sequentially shortened chromosomal upstream regions were cloned in an ldhA deletion, E. coli CICIM B0013-080C (ack-pta pps pflB dld poxB adhE frdA ldhA). The varied ldhA upstream regions were further analyzed using program NNPP2.2 (Neural Network Promoter Prediction 2.2) to predict the possible promoter regions. Two-phase fermentations (aerobic growth and oxygen-limited production) of these strains showed that shortening the ldhA upstream sequence from 291 to 106 bp successively reduced aerobic lactate synthesis and the inhibition effect on cell growth during the first phase. Simultaneously, oxygen-limited lactate productivity was increased during the second phase. The putative promoter downstream of the -96 site of ldhA could function as a transcriptional promoter or regulator. B0013-080C/pTH-rrnB-ldhA8, with the 72-bp upstream segment of ldhA, could be grown at a high rate and achieve a high oxygen-limited lactate productivity of 1.09 g g(-1) h(-1). No transcriptional promoting region was apparent downstream of the -61 site of ldhA. We identified the latent transcription regions in the ldhA upstream sequence, which will help to understand regulation of ldhA expression.