Infectious Granuloma With Mycobacterium abscessus After Facial Injection of Botulinum Toxin: A Case Report.

Botulinum toxin injections have garnered increasing employment in facial rhytidectomy due to their demonstrable efficacy and safety profile. In this study, the authors present the case of a 39-year-old woman who manifested painful crimson nodules and multiple abscesses on her face, which manifested 1 week postinjection. Subsequent histopathological scrutiny unveiled the development of histiocytic granulomas accompanied by infiltrates of inflammatory cells, and microbiological investigation and polymerase chain reaction assays identified the causative agent as Mycobacterium abscessus .

[Study on mechanism of Aconitum pendulum in treating rheumatoid arthritis based on toxicity efficacy evaluation and metabonomics].

The study aims to investigate the effects and potential mechanism of raw and processed Aconitum pendulum Busch on rheumatoid arthritis(RA) and analyze their toxicity attenuating and efficacy retaining effects. The bovine type Ⅱ collagen-induced arthritis(CIA) rat model was established. The weight, cardiac index, immune organ index, and arthritis index of the rats were recorded and calculated after administration. ELISA was used to measure the expressions of creatine kinase(CK), cardiac troponin T(cTnT), and multiple factors. The pathological morphological changes in heart tissue and ankle joint tissue were observed by hematoxylin-eosin staining. Connexin 43(Cx43) expression in the hearts of CIA rats was detected via immunohistochemical method. The levels of endogenous metabolites in the serum of CIA rats were detected by UPLC-Q-TOF-MS. Potential biomarkers were screened, and related metabolic pathways were analyzed. The results showed that raw A. pendulum could induce local myocardial fiber degeneration and necrosis, increase the cardiac index, decrease the average positive area of Cx43 expression significantly, and increase the expressions of CK and cTnT in cardiac tissue of rats. Meanwhile, raw A. pendulum could decrease the immune organ index, interleukin-6(IL-6), and other inflammatory cytokine contents in the serum and improve the damaged synovium and joint surface of CIA rats, with toxicity and efficacy coexisting. The Zanba stir-fired A. pendulum could reduce the index of arthritis, immune organ index, and content of IL-6 and inflammatory cytokines in serum and improve damaged synovium and joint surface of CIA rats with no obvious cardiac toxicity, showing significant toxicity attenuating and efficacy retaining effects. A total of 19 potential biomarkers of raw A. pendulum and Zanba stir-fired A. pendulum against RA were screened by serum metabolomics, including glycerophospholipid metabolism, glycine, serine, and threonine metabolism, arginine and proline metabolism, and steroid hormone synthesis. In conclusion, Xizang medicine A. pendulum is preventive and curative for RA. Raw A. pendulum has certain cardiotoxicity, and Zanba stir-fired A. pendulum has significant toxicity attenuating and efficacy retaining effects. The anti-RA mechanism may be related to the regulation of glycerophospholipid and amino acid metabolism.

Vascular Compromise and Alopecia After Hyaluronic Acid Filler Injection in Temple Region.

Hyaluronic acid filler injection is widely applied in facial shaping and facial filling. Although hyaluronic acid injection is thought to be relatively safe and effective, there are still incidents being reported occasionally. The authors report here a case of alopecia at vascular compromise area after receiving hyaluronic acid filler injection in the left temple region, skin necrosis, and alopecia were well recovered with the treatment of hyaluronidase and external application of minoxidil.

AR-PDEF pathway promotes tumour proliferation and upregulates MYC-mediated gene transcription by promoting MAD1 degradation in ER-negative breast cancer.

BACKGROUND: Androgen receptor (AR) is expressed in 60%~ 70% oestrogen receptor (ER)-negative breast cancer (BC) cases and promotes the growth of this cancer subtype. Expression of prostate-derived Ets factor (PDEF), a transcription factor, is highly restricted to epithelial cells in hormone-regulated tissues. MYC and its negative regulator MAD1 play an important role in BC progression. Previously, we found that PDEF expression is strongly correlated with AR expression. However, the relationship between AR and PDEF and the function of PDEF in ER-negative BC proliferation are unclear. METHODS: AR and PDEF expression in ER-negative BC tissues and cell lines was determined by performing immunohistochemistry or western blotting. Protein expression levels and location were analysed by performing western blotting, RT-qPCR and immunofluorescence staining. Co-immunoprecipitation and chromatin immunoprecipitation assays were performed to validate the regulation of AR-PDEF-MAD1-MYC axis. Moreover, the effect of AR and PDEF on BC progression was investigated both in vitro and in vivo. RESULTS: We found that PDEF was overexpressed in ER-negative BC tissues and cell lines and appeared to function as an oncogene. PDEF expression levels were strongly correlated with AR expression in ER-negative BC, and PDEF transcription was positively regulated by AR. PDEF upregulated MYC-mediated gene transcription by promoting MAD1 degradation in ER-negative BC. Finally, we found that compared with the inhibition of AR expression alone, simultaneous inhibition of AR and PDEF expression further suppressed tumour proliferation both in vitro and in vivo. CONCLUSIONS: Our data highlight the role of the AR-PDEF-MAD1-MYC axis in BC progression and suggest that PDEF can be used as a new clinical therapeutic target for treating ER-negative BC.

Clinical significance of PDEF factor expression and its relation to androgen receptor in ER- breast cancer.

AIMS: The mechanism of androgen receptor (AR) promoting tumour growth in oestrogen receptor-negative (ER- ) breast cancer (BC) is undetermined. Prostate-derived ETS factor (PDEF) is highly restricted to the hormone-regulated tissues of epithelial cells, such as those in the prostate, breast and other tissues. It has been demonstrated that PDEF expression is associated with AR in prostate cancer. In this research, we aimed to investigate the relationship between PDEF and AR in ER- BC. METHODS AND RESULTS: We immunohistochemically evaluated the correlation between PDEF and AR expression in 246 cases of ER- invasive BC, and investigated their relationship in ER- BC cell lines. The expression of PDEF was associated with the positive expression of AR (P < 0.001) and a worse survival rate (P = 0.006). PDEF+ tumours were significantly more often AR+ (P < 0.001). AR and PDEF were more often co-expressed and the series of AR+ PDEF+ (126 of 246, 51.2%) had a poor survival rate (P = 0.046). In Cox models, PDEF expression (P = 0.028) was an independent predictor for overall survival (OS). At the cellular protein and mRNA levels, our experiments also showed a statistically significant positive correlation between PDEF and AR, and that PDEF may be regulated by AR. CONCLUSIONS: PDEF is associated with markers of bad prognosis, supporting its role as a growth promoter in ER- BC. Our findings also provide evidence that PDEF is strongly correlated with AR expression in ER- breast cancer; it may be a downstream target gene of AR and a potential prognostic factor in ER- BC.

MiR-183 overexpression inhibits tumorigenesis and enhances DDP-induced cytotoxicity by targeting MTA1 in nasopharyngeal carcinoma.

MicroRNA 183 (miR-183) was identified to be downregulated in nasopharyngeal carcinoma spheroids and served as a tumor suppressor in nasopharyngeal carcinoma. However, the regulatory mechanism of miR-183 and its role in cisplatin (DDP) resistance in nasopharyngeal carcinoma cells are still unclear. The expression of miR-183 and metastasis-associated protein 1 at messenger RNA and protein levels in nasopharyngeal carcinoma tissues and cells was evaluated using quantitative reverse transcription real-time polymerase chain reaction and western blotting, respectively. CNE1 and CNE2 cells were transfected with miR-183 mimic, miR-183 inhibitor, pcDNA-metastasis-associated protein 1, or respective controls. The effects of miR-183 and metastasis-associated protein 1 overexpression on cell proliferation, invasion, and DDP-induced apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, Transwell invasion assay, and flow cytometry analysis, respectively. Luciferase reporter assay was performed to explore whether miR-183 directly targeted metastasis-associated protein 1. Xenograft tumor experiment was applied to confirm the biological function of miR-183 in vivo. MiR-183 was downregulated in nasopharyngeal carcinoma tissues and cells and negatively correlated with metastasis-associated protein 1 expression. Ectopic expression of miR-183 markedly suppressed cell proliferation and invasion and strikingly enhanced DDP-induced apoptosis in nasopharyngeal carcinoma cells, whereas metastasis-associated protein 1 overexpression partially reversed these effects. Luciferase reporter assay demonstrated that metastasis-associated protein 1 was a direct target of miR-183. MiR-183 negatively regulated the expression of metastasis-associated protein 1 at both the messenger RNA and protein levels. Xenograft tumor experiment indicated that miR-183 overexpression repressed tumor growth and improved DDP-induced cytotoxicity in nasopharyngeal carcinoma cells in vivo. MiR-183 overexpression inhibited tumorigenesis and enhanced DDP-induced cytotoxicity by targeting metastasis-associated protein 1 in nasopharyngeal carcinoma, contributing to the development of novel therapeutic approaches for the treatment of clinical nasopharyngeal carcinoma patients.

Role of Toll-Like Receptor 3 Gene Polymorphisms in Preeclampsia.

BACKGROUND/AIMS: Accumulating evidence suggests that an excessive maternal systemic inflammatory response to pregnancy with exaggerated activation of the innate immune system plays a critical role in the development of preeclampsia (PE). In this study, we investigated whether polymorphisms in the Toll-like receptor 3 (TLR3) gene are associated with susceptibility to PE in the Chinese Han population. METHODS: We recruited 987 PE patients and 1227 healthy pregnant women. Two polymorphisms (rs3775291 and rs3775296) located in TLR3 were genotyped by TaqMan allelic discrimination real-time PCR. The association between the genotype or allele frequencies and PE was examined using chi-square tests. Clinical data were compared between cases and controls using Student's t test. RESULTS: No significant difference was determined in the genetic distribution of rs3775291 and rs3775296 between cases and controls. There were also no significant differences in the genotype and allele frequencies of either SNP between healthy pregnant women and patients with late or early onset PE, or with mild or severe PE. CONCLUSION: Although this is the first study of the association between TLR3 polymorphisms and preeclampsia, we found that TLR3 polymorphisms are unlikely to play a significant role in the development of preeclampsia in the Chinese Han population.

Quantitative relations between chemical oxygen demand concentration and its influence factors in the sluice-controlled river reaches of Shaying River, China.

Recent research on the effects of dam and sluice construction on the water environment has attracted extensive attention from academia and governments alike. Because the operation of sluices greatly alters environmental factors such as water flow and sediment load, the water quality in sluice-controlled river reaches (SCRRs) undergoes complex changes compared with those in normal reaches. This work used river reaches near the Huaidian Sluice in Shaying River of China as a case study to analyse the effects of sluice operation on water quality evolution in SCRRs. The most influential factors affecting the rate of change in chemical oxygen demand (COD) concentration in SCRRs were identified through water quality monitoring experiments performed under various modes of sluice operation and by applying a statistical method 'partial correlation analysis'. Then, a hydrodynamic model incorporating sluice operation and a water quality transport and transform model incorporating the release of endogenous loads were developed. Using these two models, the processes of temporal and spatial change of COD concentrations in the SCRRs were simulated under various scenarios designed to represent the dominant factors of influence. Finally, the simulation results were used to develop empirical relationships between the rate of change in COD concentrations and the dominant factors of influence. The results reveal that three factors, i.e., water inflow concentration, gate opening size, and gate opening number, are the dominant factors of influence, and there are logarithmic relationships between the rate of change in COD concentration in the SCRRs and these factors.

[UFLC-PDA fingerprint of Tibetan medicine Pterocephalus hookeir].

This study was aimed to establish an UFLC fingerprint of Tibetan medicine Pterocephalus hookeir samples from different habitats. UFLC-PDA was adopted to analyse 21 batches of P. hookeir samples from different habitats. The chromatographic condition was as follow: Agilent proshell 120 SB-C18 column (4.6 mm x 100 mm, 2.7 microm) eluted with the mobile phases of acetonitrile and 0.2% phosphoric acid water in gradient mode. The flow rate was 1.0 mL x min(-1), and the detection wavelength was set at 238 nm. The fingerprints of 21 batches P. hookeir were carried out by similarity comparation, and 15 chromatographic peaks were extracted as the common peaks of fingerprint, of which 5 peaks were identified as chlorogenic acid, loganin, sweroside, sylvestroside III, triplostoside A. The similarity degrees of 18 batchs of samples were above 0.9, and the other 3 batchs of samples were below 0.9. This is the first established fingerprint of P. hookeir by using UFLC-PDA. This method has good precision, stability and repeatability that it could provide basis for quality control and evaluation of P. hookeir.

Fractional CO2 Laser for Vulvar Tissue Rejuvenation: A Prospective Study.

Objective: Aging and changes in hormone levels influence the appearance of the vulva, including the texture, pigmentation, and other manifestations, all of which may largely affect the physical and mental health of women. This study aimed to evaluate the efficacy and safety of fractional carbon dioxide (CO2) laser treatment for vulvar rejuvenation in Chinese women. Background: The limited options currently available for vulvar rejuvenation raise concerns. There is insufficient evidence to determine whether the fractional CO2 laser can safely and effectively rejuvenate the vulvar area for women of various ages and races. Methods: The study included 17 patients (mean age = 36.4 years) treated three times by continuous fractional CO2 laser with an interval of 1 month between each session. The primary outcomes were changes in vulva texture and pigmentation. Treatment was evaluated using images of the patients. Baseline and posttreatment images were collected and evaluated using a scoring system from 0 to 3 to grade the vulvar texture and pigmentation changes. In addition, patients rated their degree of vaginal rejuvenation after the treatment using a scoring system from 0 to 3. Results: Fractional CO2 laser treatment effectively and significantly increased vulvar texture and decreased vulvar pigmentation after three sessions (p < 0.05). Patients also self-reported noticeable improvement. There were no adverse reactions during the treatment and follow-up. Conclusions: Fractional CO2 laser treatment is a safe and effective method for vulvar rejuvenation in women.

Au-Pt Coating Improved Catalytic Stability of Au@AuPt Nanoparticles for Pressure-Based Point-of-Care Detection of Escherichia coli O157:H7.

Point-of-care testing (POCT) technologies facilitate onsite detection of pathogens in minutes to hours. Among various POCT approaches, pressure-based sensors that utilize gas-generating reactions, particularly those catalyzed by nanozymes (e.g., platinum nanoparticles, PtNPs, or platinum-coated gold nanoparticles, and Au@PtNPs) have been shown to provide rapid and sensitive detection capabilities. The current study introduces Au-Pt alloy-coated gold nanoparticles (Au@AuPtNPs), an innovative nanozyme with enhanced catalytic activity and relatively high stability. For pathogen detection, Au@AuPtNPs are modified with H1 or H2 hairpin DNAs that can be triggered to undergo a hybridization chain reaction (HCR) that leads to their aggregation upon recognition by an initiator strand (Ini) with H1-/H2-complementary aptamers tethered to magnetic beads (MBs). Pathogen binding to the aptamer exposes Ini, which then binds Au@AuPtNPs and initiates a HCR, resulting in Au@AuPtNP aggregation on MBs. These Au@AuPtNP aggregates exhibit strong catalysis of O2 from the H2O2 substrate, which is measured by a pressure meter, enabling detection of Escherichia coli (E. coli) O157:H7 at concentrations as low as 3 CFU/mL with high specificity. Additionally, E. coli O157:H7 could also be detected in simulated water and tea samples. This method eliminates the need for costly, labor- and training-intensive instruments, supporting its further testing and validation for deployment as a rapid-response POCT application in the detection of bacterial contaminants.

Community Structure and Diversity of Endophytic Fungi in Cultivated Polygala crotalarioides at Two Different Growth Stages Based on Culture-Independent and Culture-Based Methods.

Polygala crotalarioides, a perennial herbaceous plant found in southwest China, has the potential to be used in the treatment of Alzheimer's disease. Endophytic fungi that reside within medicinal herbs play an important ecological role in their host plants and can serve as a valuable source for identifying active components. However, little is known about the diversity, and structure of endophytic fungi in P. crotalarioides. In this study, we investigated the community structure and diversity of endophytic fungi in the leaves, stems, and roots of P. crotalarioides at both 1- and 2-year-growth stages using a modern culture-independent method using both culture-independent (high-throughput sequencing, HTS) and culture-based methods. Using HTS, our results revealed that the richness and diversity of endophytic fungi in P. crotalarioides varied depending on the organs and growth stages. Specifically, stems and leaves exhibited significantly higher diversity compared to roots. Additionally, the highest diversity of endophytic fungi was observed in the stems of the 2-year-old plants. At the genus level, Fusarium, Colletotrichum, and Phoma were the most abundant endophytic fungi in 1-year-old samples, while Cercospora, Apiotrichum, and Fusarium were prevalent in 2-year-old samples. A total of 55 endophytic fungal strains belonging to two phyla and 24 genera were isolated from 150 plant tissue segments using culture-based methods. The anti-acetylcholinesterase activity of these isolates was evaluated in vitro and five of them, Phialophora mustea PCAM010, Diaporthe nobilis PCBM027, Fusarium oxysporum LP41, F. oxysporum SR60, and Phoma herbarum SM81, showed strong activity (>50% inhibition rate). These findings will serve as a theoretical basis and practical guide for comprehending the structural composition, biological diversity and bioactivity of endophytic fungi in P. crotalarioides.

Inhibition of CISD1 alleviates mitochondrial dysfunction and ferroptosis in mice with acute lung injury.

The NET family member, CDGSH iron-sulfur domain-containing protein 1 (CISD1), is located in theoutermembrane of mitochondria, where it regulates energy and iron metabolism. CISD1 has vital functions in certain human diseases; however, its function in acute lung injury (ALI) is unknown. ALI pathogenesis critically involves mitochondrial dysfunction and ferroptosis, which might be regulated by CISD1. Therefore, we investigated CISD1's function in mitochondrial dysfunction and ferroptosis regulation in lipopolysaccharide (LPS)-induced ALI. We found that CISD1 was upregulated in LPS-induced ALI,and silencing Cisd1 prevented cell apoptosis and increased cell viability. When CISD1was inhibited by mitoNEET ligand-1 (NL-1) there was a significant mitigation of pathological injury and lung edema, and reduced numbers of total cells, polymorphonuclear leukocytes, and a decreased protein content in the bronchoalveolar lavage fluid (BALF). Moreover, inhibition of CISD1 markedly decreased the interleukin (IL)6, IL-1ß, and tumor necrosis factor alpha (TNF-α) levels in the lungs and BALF of ALI-model mice. Silencing of Cisd1 prevented LPS-induced mitochondrial membrane potential depolarization, cellular ATP reduction, and reactive oxygen species (ROS) accumulation, suggesting mitochondrial protection. ALI activated ferroptosis, as evidenced by the increased lipid-ROS, intracellular Fe2+ level, reduced Gpx4 (glutathione peroxidase 4) expression, and the glutathione/glutathione disulfide ratio. Interestingly, inhibition of CISD1 reduced LPS-induced ferroptosis in vivo and in vitro. In conclusion, inhibition of CISD1 alleviated mitochondrial dysfunction and ferroptosis in LPS-induced ALI, identifying CISD1 as possible target for therapy of LPS-induced ALI.

Phenanthrenes from Juncus effusus.

A chemical investigation of the EtOAc-soluble fraction from the ethanol extract of the medullae of Juncus effusus led to the isolation of three new 9,10-dihydrophenanthrenes, juncuenins E-G (1-3); two new phenanthrenes, dehydrojuncuenins D-E (4-5); one new feruloylated glycoside (6); and one known 9,10-dihydrophenanthrene (7). The structures of these compounds were determined by analyzing their spectroscopic data. Metabolites 1-4 and 7 were further evaluated for their in vitro cytotoxic activities against seven human cancer lines (A549, MCF-7, BEL-7402, HeLa, COLO205, BGC-823, and SK-OV-3). Among them, compound 1 exhibited weak cytotoxicity against MCF-7 and HeLa cell lines. Compound 7 showed moderate cytotoxicity against MCF-7 and HeLa cell lines, with IC50 values of 9.17 and 19.6 µM, respectively.

New dimeric phenanthrene and flavone from Spiranthes sinensis.

From the whole plant of Spiranthes sinensis, one novel dimeric phenanthrene, 2,2'-dihydroxy-5,5',7,7'-tetramethoxy-9,9',10,10'-tetrahydro-3,3'-biphenanthrene (1) and flavone 5-hydroxy-3,7-dimethoxy-4'-(1-hydroxy-3-methylbut-3-en-2-yloxy)-flavone (2) were isolated along with three other known flavonoids, which are reported for the first time from this species. Their structures were established after an extensive analysis by 1D and 2D NMR spectroscopy (NOESY, HSQC, and HMBC) as well as HR-TOF-MS.

Influence of changes in hydrodynamic conditions on cadmium transport in tidal river network of the Pearl River Delta, China.

With rapid economic development, the Pearl River Delta (PRD) of China has experienced a series of serious heavy metal pollution events. Considering complex hydrodynamic and pollutants transport process, one-dimensional hydrodynamic model and heavy metal transport model were developed for tidal river network of the PRD. Then, several pollution emergency scenarios were designed by combining with the upper inflow, water quality and the lower tide level boundary conditions. Using this set of models, the temporal and spatial change process of cadmium (Cd) concentration was simulated. The influence of change in hydrodynamic conditions on Cd transport in tidal river network was assessed, and its transport laws were summarized. The result showed the following: Flow changes in the tidal river network were influenced remarkably by tidal backwater action, which further influenced the transport process of heavy metals; Cd concentrations in most sections while encountering high tide were far greater than those while encountering middle or low tides; and increased inflows from upper reaches could intensify water pollution in the West River (while encountering high tide) or the North River (while encountering middle or low tides).

Rapid visual characterization of alkaloid changes in traditional processing of Tibetan medicine Aconitum pendulum by high-performance thin-layer chromatography coupled with desorption electrospray ionization mass spectrometry imaging.

Radix Aconiti, also known as Tie-bang-chui (TBC), Pang-a-na-bao, and Bang-na, is a typical aconitum Tibetan medicine and a perennial herb of the genus Aconitum pendulum Busch. and A. flavum Hand. -Mazz. dry roots. It has high toxicity and remarkable efficacy; as such, it is a typical "highly toxic and effective" drug that needs be processed and used. Processing methods of this Tibetan medicine include non-heating of highland barley wine (HBW) and fructus chebulae soup (FCS). This work aimed to understand differences in chemical composition between non-heat processed products and raw TBC. In this study, high-performance thin-layer chromatography (HPTLC) and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) were used to analyze the chemical composition of TBC processed by FCS (F-TBC) and HBW (H-TBC). The MRM mode of HPLC-QqQ-MS/MS was selected to determine the changes of several representative alkaloids to comparison with the former results. A total of 52 chemical constituents were identified in raw and processed products, and the chemical composition of F-TBC and H-TBC changed slightly compared with that of raw TBC. The processing mechanism of H-TBC was also different from that of F-TBC, which might be related to the large amount of acidic tannins in FCS. It was found that the content of all six alkaloids decreased after processing by FCS, and all five alkaloids decreased except aconitine increased after processing by HBW. The combination of HPTLC and DESI-MSI could be an effective method for rapid identification of chemical components and changing rules in ethnic medicine. The wide application of this technology provides not only an alternative method for the traditional separation and identification of secondary metabolism but also a reference for research on the processing mechanism and quality control of ethnic medicine.

Optimization of Processing Technology for Tiebangchui with Zanba Based on CRITIC Combined with Box-Behnken Response Surface Method.

The dried root of Aconitum pendulum Busch., called Tiebangchui (TBC) in Chinese, is one of the most famous Tibetan medicines. It is a widely used herb in northwest China. However, many cases of poisoning have occurred because of TBC's intense toxicity and because its therapeutic and toxic doses are similar. Therefore, finding a safe and effective method to reduce its toxicity is an urgent task. A search through the Tibetan medicine classics shows that the processing method of TBC stir-fried with Zanba was recorded in the "Processing specification of Tibetan medicine of Qinghai Province (2010)". However, the specific processing parameters are not yet clear. Thus, this study aims to optimize and standardize the processing technology of Zanba-stir-fried TBC. First, a single-factor experiment was conducted on four factors: the slice thickness of TBC, amount of Zanba, processing temperature, and time. With monoester and diester alkaloid contents in Zanba-stir-fried TBC as indexes, CRITIC combined with the Box-Behnken response surface method was used to optimize the processing technology of Zanba-stir-fried TBC. The optimized processing conditions of Zanba-stir-fried TBC were a TBC slice thickness of 2 cm, three times more Zanba than TBC, a processing temperature of 125 °C, and 60 min of stir-frying. This study determined the optimized and standard processing conditions for the usage of Zanba-stir-fried TBC, thus providing an experimental basis for the safe clinical use and industrial production of Zanba-stir-fried TBC.

An emerging plume head interacting with the Hawaiian plume tail.

The Hawaiian-Emperor seamount chain has shown two subparallel geographical and geochemical volcanic trends, Loa and Kea, since ∼5 Ma, for which numerous models have been proposed that usually involve a single mantle plume sampling different compositional sources of the deep or shallow mantle. However, both the dramatically increased eruption rate of the Hawaiian hotspot since ∼5 Ma and the nearly simultaneous southward bending of the Hawaiian chain remain unexplained. Here, we propose a plume-plume interaction model where the compositionally depleted Kea trend represents the original Hawaiian plume tail and the relatively enriched Loa trend represents an emerging plume head southeast of the Hawaiian plume tail. Geodynamic modeling further suggests that the interaction between the existing Hawaiian plume tail and the emerging Loa plume head is responsible for the southward bending of the Hawaiian chain. We show that the arrival of the new plume head also dramatically increases the eruption rate along the hotspot track. We suggest that this double-plume scenario may also represent an important mechanism for the formation of other hotspot tracks in the Pacific plate, likely reflecting a dynamic reorganization of the lowermost mantle.