Development and application of a nitrogen oxides analyzer based on the cavity attenuated phase shift technique.

Nitrogen oxides (NOx) are crucial in tropospheric photochemical ozone (O3) production and oxidation capacity. Currently, the widely used NOx measurement technique is chemiluminescence (CL) (CL-NOx), which tends to overestimate NO2 due to atmospheric oxidation products of NOx (i.e., NOz). We developed and characterized a NOx measurement system using the cavity attenuated phase shift (CAPS) technique (CAPS-NOx), which is free from interferences with nitrogen-containing species. The NOx measured by the CAPS-NOx and CL-NOx analyzers were compared. Results show that both analyzers showed consistent measurement results for NO, but the NO2 measured by the CAPS-NOx analyzer (NO2_CAPS) was mostly lower than that measured by the CL-NOx analyzer (NO2_CL), which led to the deviations in O3 formation sensitivity regime and Ox (= O3 + NO2) sources (i.e., regional background and photochemically produced Ox) determined by the ozone production efficiencies (OPE) calculated from NO2_CL and NO2_CAPS. Overall, OPE_CL exceeded OPE_CAPS by 18.9%, which shifted 3 out of 13 observation days from the VOCs-limited to the transition regime when judging using OPE_CL, as compared to calculations using OPE_CAPS. During the observation period, days dominated by regional background Ox accounted for 46% and 62% when determined using NO2_CL and NO2_CAPS, respectively. These findings suggest that the use of the CL-NOx analyzer tends to underestimate both the VOCs-limited regime and the regional background Ox dominated days. The newly built CAPS-NOx analyzer here can promote the accurate measurement of NO2, which is meaningful for diagnosing O3 formation regimes and Ox sources.

Plant-Soil Moisture Positive Feedback Maintaining Alternative Stable States in the Alpine Marsh Ecosystem.

A self-reinforcing positive feedback is regarded as a critical process for maintaining alternative stable states (ASS); however, identification of ASS and quantification of positive feedbacks remain elusive in natural ecosystems. Here, we used large-scale field surveys to search for ASS and a positive feedback mechanism under a wide range of habitats on the Tibetan Plateau. Using multiple methods, we proved that three stable states exist that accompany alpine marsh degradation. Positive feedbacks between changing soil moisture and plant community composition forced the ecosystem into another stable state, and the alteration of water use efficiency (WUE) of the component species contributed to this shift. This study provides the first empirical evidence that positive feedback loops maintain ASS in the alpine marsh ecosystem on the Tibetan Plateau. Our research revealed the powerful driving role of plants in transitions between states, which may support the conservation and restoration of global alpine marsh ecosystems.

Expression of CD68 and CD163 in malignant epithelial cells of oral squamous cell carcinoma: Phenotypic shift or mere cell fusion.

BACKGROUND / PURPOSE: The progression of epithelial to mesenchymal tissue (EMT) is a highly intricate process that facilitates the transformation of cancer cells, allowing them to changeover their characteristic epithelial properties to mesenchymal attributes. This notable change empowers the cells with enhanced mobility and the ability to migrate to distant locations. Furthermore, it is imperative to adopt the idea of macrophage tumor cell fusion to achieve comprehensive considerate of this phenomenon. Our primary objective was to conduct a thorough investigation of macrophage-restricted antigens expression, specifically CD68 and CD163, in malignant epithelial cells of oral cavity squamous cell carcinoma (OSCC) to elucidate aforementioned perceptions. MATERIALS AND METHODS: CD68 and CD163 immunohistochemical expression were assessed in oral squamous cell carcinoma (OSCC), encompassing both the neoplastic cells and the tumor-associated macrophages (TAMs). RESULTS: Both CD68 and CD163 antigens were revealed in OSCC malignant epithelial cells in a granular cell pattern, localized in membrane and cytoplasm of tumor cells respectively as well as in the infiltrating TAMs. CONCLUSION: The macrophage antigens were not limited to the infiltrating tumor-associated macrophages (TAMs), but were also observed in a substantial proportion of OSCC malignant epithelial cells within the tumor parenchyma. This particular expression pattern may represent a subset of tumor cells that have undergone an epithelial to a mesenchymal phenotypic transition. In addition, fusion of macrophages with tumor cells cannot be excluded; both might be associated with increased metastatic activity of OSCC.

Structural basis of selective beta-carotene binding by a soluble protein.

ß-carotene (BCR) is the most abundant carotenoid, a colorant, antioxidant, and provitamin A. The extreme hydrophobicity of this hydrocarbon requires special mechanisms for distribution in aqueous media, including water-soluble carotenoproteins. However, all known carotenoproteins prefer oxygenated carotenoids and bind BCR inefficiently. Here, we present the crystal structure of the BCR-binding protein (BBP) from gregarious male locusts, which is responsible for their vivid yellow body coloration, in complex with its natural ligand, BCR. BBP forms an antiparallel tubular homodimer with α/ß-wrap folded monomers, each forming a hydrophobic 47 Å long, coaxial tunnel that opens outward and is occupied by one s-cisC6-C7, all-trans BCR molecule. In the BCR absence, BBP accepts a range of xanthophylls, with reduced efficiency depending on the position and number of oxygen atoms, but rejects lycopene. The structure captures a pigment complex with a Takeout 1 protein and inspires potential applications of BBP as a BCR solubilizer.

Assessing the climatic niche changes and global invasion risk of Solanum elaeagnifolium in relation to human activities.

As an invasive plant, Solanum elaeagnifolium has posed a serious threat to agriculture and natural ecosystems worldwide. In order to better manage and limit its spread, we established niche models by combining distribution information and climate data from the native and invasive ranges of S. elaeagnifolium to analyze its niche changes during its colonization. Additionally, we evaluated its global invasion risk. Our results showed that the distribution of S. elaeagnifolium is affected by temperature, precipitation, altitude, and human activities. Solanum elaeagnifolium exhibits different degrees of niche conservatism and niche shift in different invasion ranges. During the global invasion of S. elaeagnifolium, both the niche shift and conservatism were observed, however, niche shift was particularly significant due to the presence of unoccupied niches (niche unfilling). Solanum elaeagnifolium generally occupied a relatively stable niche. However, a notable expansion was observed primarily in Europe and China. In Australia and Africa, its niche largely remains a subset of its native niche. Compared to the niche observed in its native range, its realized niche in China and Europe has shifted toward lower temperature and higher precipitation levels. Conversely, in Africa, the niche has shifted toward lower precipitation levels, while in Australia, it has shifted toward higher temperature. Our model predicted that S. elaeagnifolium has high invasion potential in many countries and regions. The populations of S. elaeagnifolium in China and Africa have reached the adapted stage, while the populations in Australia and Europe are currently in the stabilization stage. In addition, our research suggests that the potential distribution of S. elaeagnifolium will expand further in the future as the climate warms. All in all, our study suggests that S. elaeagnifolium has high potential to invade globally. Due to its high invasive potential, global surveillance and preventive measures are necessary to address its spread.

Sharp habitat shifts, evolutionary tipping points and rescue: Quantifying the perilous path of a specialist species toward a refugium in a changing environment.

Specialist species thriving under specific environmental conditions in narrow geographic ranges are widely recognised as heavily threatened by climate deregulation. Many might rely on both their potential to adapt and to disperse toward a refugium to avoid extinction. It is thus crucial to understand the influence of environmental conditions on the unfolding process of adaptation. Here, I study the eco-evolutionary dynamics of a sexually reproducing specialist species in a two-patch quantitative genetic model with moving optima. Thanks to a separation of ecological and evolutionary time scales and the phase-line study of the selection gradient, I derive the critical environmental speed for persistence, which reflects how the existence of a refugium impacts extinction patterns and how it relates to the cost of dispersal. Moreover, the analysis provides key insights about the dynamics that arise on the path towards this refugium. I show that after an initial increase of population size, there exists a critical environmental speed above which the species crosses a tipping point, resulting into an abrupt habitat switch. In addition, when selection for local adaptation is strong, this habitat switch passes through an evolutionary "death valley", leading to a phenomenon related to evolutionary rescue, which can promote extinction for lower environmental speeds than the critical one.

Data of crystal structure of the large Stokes shift fluorescent protein tKeima.

Large Stokes shift (LSS) fluorescent proteins (FPs) are important for dual-color fluorescence cross-correlation spectroscopy and multicolor imaging. tKeima is a tetrameric LSS FP from the stony coral Montipora sp. Analyzing the tetrameric interface of tKeima is necessary to understand the oligomeric state of the Keima family and to provide insights into engineering oligomeric FPs to generate monomeric FPs, which are useful for FP-based molecular and cell biology studies. Here, detailed experimental procedures for tKeima were reported, including spontaneous crystal growth, data collection for X-ray diffraction, and structure determination. This information can be used for future experiments to obtain the high-resolution structure of tKeima, providing accurate structural information to comprehensively understand the molecular function of tKeima and the protein engineering of tetrameric FPs.

The emerging invasive species and climate-change lexicon.

The rapid diversification of terminology associated with invasion ecology is a known barrier to effective communication and management. These challenges are magnified by the addition of terms and concepts related to climate-induced range-shifting taxa and/or changes to impacts. Further, institutional policies and terminologies for invasive species introduce new ambiguities when considering climate change. To alleviate communication and application challenges, we introduce a conceptual framework that organizes climate-related invasion terms, revealing ambiguities and gaps. Additionally, we illustrate how these ambiguities can affect management with four case studies and consider situations where resolution can improve policy and management outcomes. The framework can help users avoid inconsistent use of terminology, and prioritize when to address management and policy consequences related to associated terminological ambiguity.

Unraveling the Origin of Elemental Chemical Shift and the Role of Atomic Hydrogen in a Surface Ullmann Coupling System.

The Ullmann coupling of aryl halides is a powerful method in the on-surface synthesis of functional materials. Understanding its basic aspects and influencing factors can aid in the use of this tool for the fabrication of intriguing structures. In this study, we unveil (1) the origin of the shift in the elemental binding energy (BE) and (2) the functions of atomic hydrogen (AH) in a typical Ullmann coupling system using combined spectroscopy and microscopy techniques. During debromination of the aryl halide precursor, the work function (WF) alteration is correlated with the surface Br amount. The WF change instead of C-Ag formation is proposed to play a dominant role in the shift of the molecular C 1s BE. AH dosing onto organometallic chains leads to chain decomposition and surface Br removal. In contrast, AH dosing onto covalent poly(para-phenylene) (PPP) chains results in superhydrogenation in addition to Br removal. The C 1s BE shift is attributed to both WF change and superhydrogenation effects. Thermal annealing restores the PPP chains by eliminating superhydrogenation, which causes the C 1s BE to shift to a high BE. This study provides deep insights into the mechanisms of Ullmann coupling on surfaces, highlighting the significant role of WF alterations and AH treatments in these processes.

The Beauty Revolution of Nanotechnology: Unveiling the Impact of Cosmetic Nano Wonders.

The infusion of nanotechnology into cosmetic formulations marks a transformative shift in beauty science. Although Raymond Reed originally used the word "cosmeceutical," Dr. Albert Kligman popularised the idea in the late 1970s. Cosmetic Nano Wonders are redefining skincare by leveraging nanomaterials to enhance the stability, delivery, and efficacy of active ingredients. The paradigm shift holds promise for overcoming longstanding challenges in traditional cosmetic formulations. This article aims to explore and showcase the revolutionary impact of nanotechnology on the cosmetic industry. Focusing on key nanocarriers, such as liposomes and nanoparticles, our objective is to illuminate how nanotechnology elevates the performance of beauty products, providing advanced solutions for skincare concerns. This revolution promotes sustainability through green synthesis techniques and enables more accurate and effective therapies for a variety of skin issues, including acne and ageing that raises the bar for safety and innovation in the cosmetics business by enhancing product performance and environmental impact. Conducting a thorough literature review, we analyze recent scientific studies and industry reports to unveil the mechanisms and applications of nanotechnology in cosmetics. Special attention is given to the role of nanocarriers in stability enhancement, targeted delivery, and controlled release, unraveling the methods that drive the transformative potential of Cosmetic Nano Wonders. The database sources are Scopus, PubMed, Google Scholar, and Google Patents. The examination of recent research underscores the tangible benefits of nanotechnology in cosmetics. Cosmetic Nano Wonders demonstrate superior stability, enhanced penetration into skin layers, and controlled release mechanisms, showcasing their potential to revolutionize beauty science and address longstanding challenges in skincare. Cosmetic Nano Wonders represent a groundbreaking shift in beauty science, offering unprecedented possibilities for formulators and consumers. As nanotechnology continues to reshape cosmetic formulations, the future holds the promise of safer, more effective, and personalized skincare solutions, ushering in a new era in beauty science.

The leaf-footed cactus bug is not a cactus specialist: Narnia femorata feeds, fights, and mates on thistle.

Novel host plants are incorporated into the diets of phytophagous insects when females oviposit and juveniles feed and survive on them. A change in diet, however, can have morphological consequences. We recently found a population of the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae), a historical cactus specialist, living and feeding on Cirsium thistle. We also found adults breeding and males using their enlarged hind legs (i.e., weapons) in male-male combat on thistle. When we compared this thistle population with a population feeding on cactus, we found that both populations had similar body and weapon sizes as well as weapon composition. However, the population living on thistle had longer mouthparts than the population found on cactus, although this difference only occurred at larger body sizes. This difference in adult mouthpart size is likely a result of the juvenile rearing environment (i.e., thistle or cactus). However, genetic differences may also affect this trait. Our results provide some interesting avenues for future research (e.g., a reciprocal transplant experiment) in a species with a recent host range expansion.

Use of two-point and six-point Dixon MRI for fat fraction analysis in the lumbar vertebral bodies and paraspinal muscles in healthy dogs: comparison with magnetic resonance spectroscopy.

Introduction: Fatty degeneration of the vertebral bodies and paravertebral muscles is associated with the presence, severity, and prognosis of spinal disease such as intervertebral disc degeneration. Therefore, the fat fraction (FF) of the vertebral bodies and paraspinal muscles has been considered a potential biomarker for assessing the pathophysiology, progression, and treatment response of spinal disease. Magnetic resonance spectroscopy (MRS) is considered the reference standard for fat quantification; however, it has limitations of a long acquisition time and is technically demanding. Chemical shift-encoding water-fat imaging, called the Dixon method, has recently been applied for rapid fat quantification with high spatial resolution. However, the Dixon method has not been validated in veterinary medicine, and we hypothesized that the Dixon method would provide a comparable assessment of the FF to MRS but would be faster and easier to implement in dogs. Methods: In this prospective study, we assessed the FF of the lumbar vertebral bodies and paravertebral muscles from the first to sixth lumbar vertebrae using MRS, the two-point Dixon method (LAVA-FLEX), and the six-point Dixon method (IDEAL-IQ) and compared these techniques. Results and discussion: The FFs of vertebral bodies and paravertebral muscles derived from LAVA-FLEX and IDEAL-IQ showed significant correlations and agreement with those obtained with MRS. In particular, the FFs obtained with IDEAL-IQ showed higher correlations and better agreement with those obtained with MRS than those derived by LAVA-FLEX. Both Dixon methods showed excellent intra- and interobserver reproducibility for FF analysis of the vertebral bodies and paraspinal muscles. However, the test-retest repeatability of vertebral body and paraspinal muscle FF analysis was low for all three sequences, especially for the paraspinal muscles. The results of this study showed that LAVA-FLEX and IDEAL-IQ have high reproducibility and that their findings were highly correlated with the FFs of the lumber vertebral bodies and paraspinal muscles determined by MRS in dogs. The FF analysis could be performed much more easily and quickly using LAVA-FLEX and IDEAL-IQ than using MRS. In conclusion, LAVA-FLEX and IDEAL-IQ can be used as routine procedures in spinal magnetic resonance imaging in dogs for FF analysis of the vertebral bodies and paraspinal muscles.

Assessment of chemical-shift and diffusion-weighted magnetic resonance imaging in differentiating malignant and benign vertebral lesions in oncologic patients. A single institution experience.

BACKGROUND: To analyze the contribution of two non-standard magnetic resonance imaging (MRI) techniques the chemical-shift image (CSI), and diffusion-weighted imaging (DWI) in distinguishing malignant and benign vertebral bone marrow lesions (VBMLs). PATIENTS AND METHODS: Conventional spine MRI protocol, followed by CSI and DWI was performed with a 1.5 T system on 102 oncologic patients between January 2020 and December 2023. From the identified 325 VBMLs, 102 representative lesions (one per patient) were selected. VBMLs were divided into malignant (n = 74) and benign (n = 28) based on histopathology, or imaging follow-up. The quantitative parameters for VBMLs assessment were signal intensity ratio (SIR) derived from CSI and apparent diffusion coefficient (ADC) derived from DWI. RESULTS: The malignant VBMLs had significantly higher SIR values (p < 0.05) and lower ADC values compared to benign VBMLs (p < 0.05). The area under the curve (AUC) was 0.953 (p < 0.001) for SIR, and 0.894 for ADC (p < 0.001) (cut-off at > 0.82, and ≤ 1.57x10-3 mm2/s, respectively). The sensitivity and specificity for SIR were 93.6%, and 88.5%, while for ADC were 88.2% and 92.3% (respectively). The combined use of SIR and ADC improved the diagnostic accuracy to AUC of 0.988 (p < 0.001, cut-off at > 0.19), sensitivity, and specificity of 100.0% and 90.9% (respectively). CONCLUSIONS: Quantitative parameters, SIR and ADC, derived from two non-standard MRI techniques, CSI, and DWI, showed diagnostic strength in differentiating malignant and benign VBMLs. Combining both methods can further enhance the diagnostic performance and accuracy of spine MRI in clinical practice.

Perceptions of Sleep Quality, Fatigue, and Cognition Among Women Shift Workers.

OBJECTIVE: To explore the perceptions of sleep quality, levels of fatigue, and cognitive executive function in women shift workers. DESIGN: Qualitative, descriptive study of a sample of participants who participated in a cross-sectional, mixed-methods study. SETTING: Online focus groups. PARTICIPANTS: Women shift workers (N = 14) recruited from the southeastern United States. METHODS: Four focus groups were conducted using the Zoom online videoconferencing platform. Transcripts were coded inductively, and data were analyzed using a thematic analysis approach. RESULTS: Five major themes were developed from the data: Lots of Sleep Lost, Day Sleep Difficulties, Negative Consequences, Missing Out, and Not in My Own Thoughts. CONCLUSION: Shift work is associated with sleep loss, which has a negative impact on women's emotional, mental, and physical health. Further nursing science investigation into strategies to enable women to improve their sleep quality, sleep quantity, and social/domestic environment is warranted. Education to increase sleep knowledge and decrease accidents and errors that can result from insufficient sleep is vital.

Imino chemical shift assignments of tRNAAsp, tRNAVal and tRNAPhe from Escherichia coli.

Transfer RNAs (tRNAs) are an essential component of the protein synthesis machinery. In order to accomplish their cellular functions, tRNAs go through a highly controlled biogenesis process leading to the production of correctly folded tRNAs. tRNAs in solution adopt the characteristic L-shape form, a stable tertiary conformation imperative for the cellular stability of tRNAs, their thermotolerance, their interaction with protein and RNA complexes and their activity in the translation process. The introduction of post-transcriptional modifications by modification enzymes, the global conformation of tRNAs, and their cellular stability are highly interconnected. We aim to further investigate this existing link by monitoring the maturation of bacterial tRNAs in E. coli extracts using NMR. Here, we report on the 1H, 15N chemical shift assignment of the imino groups and some amino groups of unmodified and modified E. coli tRNAAsp, tRNAVal and tRNAPhe, which are essential for characterizing their maturation process using NMR spectroscopy.

Development of a new paradigm model for deciphering action mechanism of Danhong injection using a combination of isothermal shift assay and database interrogation.

BACKGROUND: Identification of active components of traditional Chinese Medicine (TCM) and their respective targets is important for understanding the mechanisms underlying TCM efficacy. However, there are still no effective technical methods to achieve this. METHODS: Herein, we have established a method for rapidly identifying targets of a specific TCM and interrogating the targets with their corresponding active components based on Isothermal Shift Assay (iTSA) and database interrogation. RESULTS: We optimized iTSA workflow and identified 110 targets for Danhong injection (DHI) which is used as an effective remedy for cardiovascular and cerebrovascular diseases. Moreover, we identified the targets of the nine major ingredients found in DHI. Database interrogation found that the potential targets for DHI, in which we verified that ADK as the target for salvianolic acid A and ALDH1B1 as the target for protocatechualdehyde in DHI, respectively. CONCLUSION: Overall, we established a novel paradigm model for the identification of targets and their respective ingredients in DHI, which facilitates the discovery of drug candidates and targets for improving disease management and contributes to revealing the underlying mechanisms of TCM and fostering TCM development and modernization.

The Incidence of Injuries to Ramp Semimembranosus Complex Lesions After ACL Injury: An MRI Study.

Background: Medial meniscal ramp lesions have recently been an area of interest because of their recognized prevalence in association with anterior cruciate ligament (ACL) ruptures. Anatomically, the medial meniscal ramp is composed of the meniscocapsular ligament in continuity with the semimembranosus muscle and the meniscotibial ligament. Diagnosis of ramp semimembranosus complex (RSC) injuries remains challenging, and their prevalence is likely to be underestimated in comparison with ramp lesions. Purpose: To determine the prevalence of RSC lesions after a complete ACL rupture. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A retrospective database analysis was performed. The cohort consisted of the first 100 patients with complete ACL rupture confirmed by magnetic resonance imaging (MRI) who underwent knee arthroscopy for ACL reconstruction in 2019. The semimembranosus lesions were identified using MRI by 2 independent radiologists specializing in musculoskeletal imaging. The ramp lesions were initially diagnosed using MRI and then confirmed during arthroscopy by an experienced knee surgeon. The magnitude of rotatory instability was recorded using the pivot-shift test. A multivariate analysis was used to determine the lesions associated with the semimembranosus complex. Results: Of 100 patients, 53 showed lesions of the RSC; among them, 30 ramp lesions were confirmed after arthroscopic evaluation, and 40 semimembranosus lesions (23 without ramp lesion and 17 with ramp lesion) were found using MRI. A positive pivot shift was present in 57% of patients with combined RSC injury (P = .04) compared with 36% in patients without an RSC lesion. Conclusion: Lesions of the RSC were found in more than half of ACL ruptures in this retrospective cohort. Rotational instability could be associated with combined ACL and RSC injury.

Positive selection, genetic recombination, and intra-host evolution in novel equine coronavirus genomes and other members of the Embecovirus subgenus.

There are several examples of coronaviruses in the Betacoronavirus subgenus Embecovirus that have jumped from an animal to the human host. Studying how evolutionary factors shape coronaviruses in non-human hosts may provide insight into the coronavirus host-switching potential. Equids, such as horses and donkeys, are susceptible to equine coronaviruses (ECoVs). With increased testing prevalence, several ECoV genome sequences have become available for molecular evolutionary analyses, especially those from the United States of America (USA). To date, no analyses have been performed to characterize evolution within coding regions of the ECoV genome. Here, we obtain and describe four new ECoV genome sequences from infected equines from across the USA presenting clinical symptoms of ECoV, and infer ECoV-specific and Embecovirus-wide patterns of molecular evolution. Within two of the four data sets analyzed, we find evidence of intra-host evolution within the nucleocapsid (N) gene, suggestive of quasispecies development. We also identify 12 putative genetic recombination events within the ECoV genome, 11 of which fall in ORF1ab. Finally, we infer and compare sites subject to positive selection on the ancestral branch of each major Embecovirus member clade. Specifically, for the two currently identified human coronavirus (HCoV) embecoviruses that have spilled from animals to humans (HCoV-OC43 and HCoV-HKU1), we find that there are 42 and 2 such sites, respectively, perhaps reflective of the more complex ancestral evolutionary history of HCoV-OC43, which involves several different animal hosts.IMPORTANCEThe Betacoronavirus subgenus Embecovirus contains coronaviruses that not only pose a health threat to animals and humans, but also have jumped from animal to human host. Equids, such as horses and donkeys are susceptible to equine coronavirus (ECoV) infections. No studies have systematically examined evolutionary patterns within ECoV genomes. Our study addresses this gap and provides insight into intra-host ECoV evolution from infected horses. Further, we identify and report natural selection pattern differences between two embecoviruses that have jumped from animals to humans [human coronavirus OC43 and HKU1 (HCoV-OC43 and HCoV-HKU1, respectively)], and hypothesize that the differences observed may be due to the different animal host(s) that each virus circulated in prior to its jump into humans. Finally, we contribute four novel, high-quality ECoV genomes to the scientific community.

Shift in Demographic Involvement and Clinical Characteristics of COVID-19 From Wild-Type SARS-CoV-2 to the Delta Variant in the Indian Population: In Silico Analysis.

BACKGROUND: The Delta variant (B.1.617.2) was considered the most dangerous SARS-CoV-2 strain; however, in-depth studies on its impact based on demographic and clinical characteristics of COVID-19 are scarce. OBJECTIVE: We aimed to investigate the shift in demographic and clinical characteristics of the COVID-19 pandemic with the emergence of the SARS-CoV-2 Delta variant compared with the wild-type (WT) strain (B.1). METHODS: A cross-sectional study of COVID-19 cases in the Indian population caused by the WT strain (B.1) and Delta variant of SARS-CoV-2 was performed. The viral genomic sequence metadata containing demographic, vaccination, and patient status details (N=9500, NDelta=6238, NWT=3262) were statistically analyzed. RESULTS: With the Delta variant, in comparison with the WT strain, a higher proportion of young individuals (<20 years) were infected (0-9 years: Delta: 281/6238, 4.5% vs B.1: 75/3262, 2.3%; 10-19 years: Delta: 562/6238, 9% vs B.1: 229/3262, 7%; P<.001). The proportion of women contracting infection increased (Delta: 2557/6238, 41% vs B.1: 1174/3262, 36%; P<.001). However, it decreased for men (Delta: 3681/6238, 59% vs B.1: 2088/3262, 64%; P<.001). An increased proportion of the young population developed symptomatic illness and were hospitalized (Delta: 27/262, 10.3% vs B.1: 5/130, 3.8%; P=.02). Moreover, an increased proportion of the women (albeit not men) from the young (Delta: 37/262, 14.1% vs B.1: 4/130, 3.1%; P<.001) and adult (Delta: 197/262, 75.2% vs B.1: 72/130, 55.4%; P<.001) groups developed symptomatic illness and were hospitalized. The mean age of men and women who contracted infection (Delta: men=37.9, SD 17.2 years; women=36.6, SD 17.6 years; P<.001; B.1: men=39.6, SD 16.9 years; women=40.1, SD 17.4 years; P<.001) as well as developing symptoms or being hospitalized (Delta: men=39.6, SD 17.4 years; women=35.6, SD 16.9 years, P<.001; B.1: men=47, SD 18 years; women=49.5, SD 20.9 years, P<.001) were considerably lower with the Delta variant than the B.1 strain. The total mortality was about 1.8 times higher with the Delta variant than with the WT strain. With the Delta variant, compared with B.1, mortality decreased for men (Delta: 58/85, 68% vs B.1: 15/20, 75%; P<.001); in contrast, it increased for women (Delta: 27/85, 32% vs B.1: 5/20, 25%; P<.001). The odds of death increased with age, irrespective of sex (odds ratio 3.034, 95% CI 1.7-5.2, P<.001). Frequent postvaccination infections (24/6238) occurred with the Delta variant following complete doses. CONCLUSIONS: The increased involvement of young people and women, the lower mean age for illness, higher mortality, and frequent postvaccination infections were significant epidemiological concerns with the Delta variant.