Deteriorated bone microarchitecture caused by sympathetic overstimulation in pheochromocytoma and paraganglioma

PURPOSE

Despite the potentially destructive effect of sympathetic activity on bone metabolism, its impact on bone microarchitecture, a key determinant of bone quality, has not been thoroughly investigated. This study aims to evaluate the impact of sympathetic activity on bone microarchitecture and bone strength in patients with pheochromocytoma and paraganglioma (PPGL).

METHODS

A cross-sectional study was conducted in 38 PPGL patients (15 males and 23 females). Bone turnover markers serum procollagen type 1 N-terminal propeptide (P1NP) and β-carboxy-terminal crosslinked telopeptide of type 1 collagen (β-CTX) were measured. 24-h urinary adrenaline (24hUE) and 24-h urinary norepinephrine levels (24hUNE) were measured to indicate sympathetic activity. High-resolution peripheral quantitative computed tomography (HR-pQCT) was conducted to evaluate bone microarchitecture in PPGL patients and 76 age-, sex-matched healthy controls (30 males and 46 females). Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry (DXA) simultaneously.

RESULTS

PPGL patients had a higher level of β-CTX. HR-pQCT assessment revealed that PPGL patients had notably thinner and more sparse trabecular bone (decreased trabecular number and thickness with increased trabecular separation), significantly decreased volume BMD (vBMD), and bone strength at both the radius and tibia compared with healthy controls. The deterioration of Tt.vBMD, Tb.Sp, and Tb.1/N.SD was more pronounced in postmenopausal patients compared with the premenopausal subjects. Moreover, subjects in the highest 24hUNE quartile (Q4) showed markedly lower Tb.N and higher Tb.Sp and Tb.1/N.SD at the tibia than those in the lowest quartile (Q1). Age-related bone loss was also exacerbated in PPGL patients to a certain extent.

CONCLUSIONS

PPGL patients had significantly deteriorated bone microarchitecture and strength, especially in the trabecular bone, with an increased bone resorption rate. Our findings provide clinical evidence that sympathetic overstimulation may serve as a secondary cause of osteoporosis, especially in subjects with increased sympathetic activity.

Identification and characterization of TatD DNase in planarian Dugesia japonica and its antibiofilm effect

TatD DNase, a key enzyme in vertebrates and invertebrates, plays a pivotal role in various physiological processes. Dugesia japonica (D. japonica), a flatworm species, has remarkable regenerative capabilities and possesses a simplified immune system. However, the existence and biological functions of TatD DNase in D. japonica require further investigation. Here, we obtained the open reading frame (ORF) of DjTatD and demonstrated its conservation. The three-dimensional structure of DjTatD revealed its active site and binding mechanism. To investigate its enzymological properties, we overexpressed, purified, and characterized recombinant DjTatD (rDjTatD). We observed that DjTatD was primarily expressed in the pharynx and its expression could be significantly challenged upon stimulation with lipopolysaccharide, peptidoglycan, gram-positive and gram-negative bacteria. RNA interference results indicated that both DjTatD and DjDN2s play a role in pharyngeal regeneration and may serve as functional complements to each other. Additionally, we found that rDjTatD and recombinant T7DjTatD effectively reduce biofilm formation regardless of their bacterial origin. Together, our results demonstrated that DjTatD may be involved in the planarian immune response and pharyngeal regeneration. Furthermore, after further optimization in the future, rDjTatD and T7DjTatD can be considered highly effective antibiofilm agents.

[From treatment to whole course management: envisioning comprehensive management of Talaromycosis marneffei]

Talaromycosis marneffei has been increasing in recent years. Our understanding of this disease has gradually deepened through extensive basic and clinical research, but there are still many limitations. In this article, by incorporating the latest research advancements, we discuss important issues in managing Talaromycosis marneffei trends, aiming to guide effective prevention and control of the disease, improving public health, and reducing the healthcare burden.

CD133+ endothelial-like stem cells restore neovascularization and promote longevity in progeroid and naturally aged mice

The stem cell theory of aging dictates that a decline in the number and/or function of stem cells causes tissue degeneration and aging; however, it still lacks unequivocal experimental support. Here, using lineage tracing and single-cell transcriptomics, we identify a population of CD133+ bone marrow-derived endothelial-like cells (ELCs) as potential endothelial progenitor cells, which contribute to tubular structures in vitro and neovascularization in vivo. We demonstrate that supplementation with wild-type and young ELCs respectively restores neovascularization and extends lifespan in progeric and naturally aged mice. Mechanistically, we identify an upregulation of farnesyl diphosphate synthase (FDPS) in aged CD133+ ELCs-a key enzyme in isoprenoid biosynthesis. Overexpression of FDPS compromises the neovascularization capacity of CD133+ ELCs, whereas FDPS inhibition by pamidronate enhances neovascularization, improves health measures and extends lifespan in aged mice. These findings highlight stem cell-based strategies for the treatment of progeria and age-related pathologies.

Leveraging aptamers for targeted protein degradation

Targeted protein degradation (TPD) technologies, particularly proteolysis-targeting chimeras (PROTACs), have emerged as a significant advancement in drug discovery. However, several hurdles - such as the difficulty of identifying suitable ligands for traditionally undruggable proteins, poor solubility and impermeability, nonspecific biodistribution, and on-target off-tissue toxicity - present challenges to their clinical applications. Aptamers are promising ligands for broad-ranging molecular recognition. Utilizing aptamers in TPD has shown potential advantages in overcoming these challenges. Here, we provide an overview of recent developments in aptamer-based TPD, emphasizing their potential to achieve targeted delivery and their promise for the spatiotemporal degradation of undruggable proteins. We also discuss the challenges and future directions of aptamer-based TPD with the goal of facilitating their clinical applications.

DjFARP Contributes to the Regeneration and Maintenance of the Brain through Activation of DjRac1 in Dugesia japonica

FERM, RhoGEF, and Pleckstrin domain protein (FARP) mediated RhoGTPase pathways are involved in diverse biological processes, such as neuronal development and tumorigenesis. However, little is known about their role in neural regeneration. We uncovered for the first time that FARP-Rac1 signaling plays an important role in neural regeneration in Dugesia japonica, a planarian that possesses unparalleled regenerative capacities. The planarian FARP homolog DjFARP was primarily expressed in both intact and regenerating brain and pharynx tissue. Functional studies suggested that downregulation of DjFARP with dsRNA in Dugesia japonica led to smaller brain sizes, defects in brain lateral branches, and loss of cholinergic, GABAergic, and dopaminergic neurons in both intact and regenerating animals. Moreover, the Rho GTPase DjRac1 was shown to play a similar role in neural regeneration and maintenance. Rac1 activation assay showed that DjFARP acts as a guanine nucleotide exchange factor (GEF) for DjRac1. Together, these findings indicate that the brain defects seen in DjFARP knockdown animals may be attributable to DjRac1 inactivation. In conclusion, our study demonstrated that DjFARP-DjRac1 signaling was required for the maintenance and proper regeneration of the brain in Dugesia japonica.

The Physiological Function of nNOS-Associated CAPON Proteins and the Roles of CAPON in Diseases

In this review, the structure, isoform, and physiological role of the carboxy-terminal PDZ ligand of neuronal nitric oxide synthase (CAPON) are summarized. There are three isoforms of CAPON in humans, including long CAPON protein (CAPON-L), short CAPON protein (CAPON-S), and CAPON-S' protein. CAPON-L includes three functional regions: a C-terminal PDZ-binding motif, carboxypeptidase (CPE)-binding region, and N-terminal phosphotyrosine (PTB) structural domain. Both CAPON-S and CAPON-S' only contain the C-terminal PDZ-binding motif. The C-terminal PDZ-binding motif of CAPON can bind with neuronal nitric oxide synthase (nNOS) and participates in regulating NO production and neuronal development. An overview is given on the relationship between CAPON and heart diseases, diabetes, psychiatric disorders, and tumors. This review will clarify future research directions on the signal pathways related to CAPON, which will be helpful for studying the regulatory mechanism of CAPON. CAPON may be used as a drug target, which will provide new ideas and solutions for treating human diseases.

Neodymium affects the generation of reactive oxygen species via GSK-3β/Nrf2 signaling in the gill of zebrafish

Rare earth element neodymium (Nd) is widely used in industry and agriculture, which may result in the pollution of aquatic environment. In this study, we exposed zebrafish with 10, 50, and 100 μg/L Nd for four weeks. The results showed that Nd could be accumulated in fish gill and Nd accumulation affected the equilibrium of nutrient elements. Nd decreased the antioxidant enzymes' activity and gene expression level, but enhanced the generation of reactive oxygen species (ROS). Moreover, various concentration of Nd treatments inhibited Nrf2 signaling in gill. To examine the critical role of GSK-3β/Nrf2 signaling on ROS generation under Nd stress, we further interfered gsk-3β gene in zebrafish under 100 μg/L Nd exposure. The result showed that gsk-3β gene interference induced Nrf2 signaling as well as the expression and activity of antioxidant enzymes in fish gill. In all, Nd could be accumulated in fish gill, and the signaling of GSK-3β/Nrf2 was involved in regulating ROS generation under Nd treatments.

WTAP regulates stem cells via TRAF6 to maintain planarian homeostasis and regeneration

WTAP, a highly conserved Wilms' tumor 1 interacting protein, is involved in a variety of biological processes. However, functional studies of WTAP in planarians have not been reported. In this study, we examined the spatiotemporal expression pattern of planarian DjWTAP and investigated its functions in planarians regeneration and homeostasis. Knocking-down DjWTAP resulted in severe morphological defects leading to lethality within 20 days. Silencing DjWTAP promoted the proliferation of PiwiA⁺ cells but impaired the lineage differentiation of epidermal, neural, digestive, and excretory cell types, suggesting a critical role for DjWTAP in stem cell self-renewal and differentiation in planarian. To further investigate the mechanisms underlying the defective differentiation, RNA-seq was employed to determine the transcriptomic alterations upon DjWTAP RNA interference. Histone 4 (H4), Histone-lysine N-methyltransferase-SETMAR like, and TNF receptor-associated factor 6 (TRAF6), were significantly upregulated in response to DjWTAP RNAi. Knocking-down TRAF6 largely rescued the defective tissue homeostasis and regeneration resulted from DjWTAP knockdown in planarians, suggesting that DjWTAP maintains planarian regeneration and homeostasis via TRAF6.

Extracellular matrix-regulator MMPA is required for the orderly proliferation of neoblasts and differentiation of ectodermal progenitor cells in the planarian Dugesia japonica

Matrix metalloproteinases (MMPs) are members of a family of zinc-dependent metallopeptidase proteins that are widely found in plants, animals, and microorganisms. As the regulators of the extracellular matrix and basement membrane, MMPs play an important role in embryogenesis, development, innate immunity, and regeneration. However, the function of MMP family in planarian, a model for regeneration research, is still ambiguous. Here, we cloned 5 MMPs genes from Dugesia japonica and found that DjMMPA was associated with the process of regeneration, neoblasts cell maintenance confusion and destruction. Loss of DjMMPA led to homeostasis confusion and eventually death, owing to neoblasts proliferation disorder. Additionally, DjMMPA RNAi-treated animals had impaired regeneration after amputation. Furthermore, knockdown of DjMMPA had noticeable defects in cell differentiation of ectoderm, especially in eyes and neural progenitor cells, possibly by inhibiting Wnt signaling. Our results suggest that extracellular matrix-regulator MMPA is required for the orderly proliferation of neoblasts and differentiation of ectodermal progenitor cells in the planarian, which provide valuable information for further explorations into the molecular mechanism of MMPS, stem cells, and regeneration.

High prevalence of vertebral deformity in tumor-induced osteomalacia associated with impaired bone microstructure

PURPOSE

Patients with tumor-induced osteomalacia (TIO) often suffer from irreversible height loss due to vertebral deformity. However, the prevalence of vertebral deformity in TIO patients varies among limited studies. In addition, the distribution and type of vertebral deformity, as well as its risk factors, remain unknown. This study aimed to identify the prevalence, distribution, type and risk factors for vertebral deformity in a large cohort of TIO patients.

METHODS

A total of 164 TIO patients were enrolled in this retrospective study. Deformity in vertebrae T4-L4 by lateral thoracolumbar spine radiographs was evaluated according to the semiquantitative method of Genant. Bone microstructure was evaluated by trabecular bone score (TBS) and high-resolution peripheral QCT (HR-pQCT).

RESULTS

Ninety-nine (99/164, 60.4%) patients had 517 deformed vertebrae with a bimodal pattern of distribution (T7-9 and T11-L1), and biconcave deformity was the most common type (267/517, 51.6%). Compared with patients without vertebral deformity, those with vertebral deformity had a higher male/female ratio, longer disease duration, more height loss, lower serum phosphate, higher bone turnover markers, lower TBS, lower areal bone mineral density (aBMD), lower peripheral volumetric BMD (vBMD) and worse microstructure. Lower trabecular vBMD and worse trabecular microstructure in the peripheral bone and lower spine TBS were associated with an increased risk of vertebral deformity independently of aBMD. After adjusting for the number of deformed vertebrae, we found little difference in clinical indexes among the patients with different types of vertebral deformity. However, we found significant correlations of clinical indexes with the number of deformed vertebrae and the spinal deformity index.

CONCLUSION

We reported a high prevalence of vertebral deformity in the largest cohort of TIO patients and described the vertebral deformity in detail for the first time. Risk factors for vertebral deformity included male sex, long disease duration, height loss, abnormal biochemical indexes and bone impairment. Clinical manifestation, biochemical indexes and bone impairment were correlated with the number of deformed vertebrae and degree of deformity, but not the type of deformity.

Characterization of the lipidomic profile of clam Meretrix petechialis in response to Vibrio parahaemolyticus infection

Vibrio parahaemolyticus is a devastating pathogen of clam Meretrix petechialis, which brings about huge economic losses in aquaculture breeding industry. In our previous study, we have found that Vibrio infection is closely associated with lipid metabolism of clams. In this study, an untargeted lipidomics approach was used to explore the lipid profiling changes upon Vibrio infection. The results demonstrated that the hepatopancreas of clams was composed of five lipid categories including fatty acyls, glycerolipids, glycerophospholipids, sphingolipids and sterol lipids. And the content of lipid classes altered during Vibrio infection, implying that Vibrio infection altered intracellular lipid homeostasis in clams. Meanwhile, a total of 200 lipid species including 82 up-regulated and 118 down-regulated significantly were identified in response to Vibrio infection, of which ceramide (Cer), phosphatidylcholine (PC) and triglyceride (TG) accounted for the largest proportion. Notably, all Cers showed a significantly decreased trend while nearly all TG species were increased significantly during Vibrio infection, which suggested that Cer and TG could be determined as effective biomarkers. Furthermore, these differentially expressed lipid species were enriched in 20 metabolic pathways and sphingolipid metabolism was one of the most enriched pathways. These results evidenced how the lipid metabolism altered in the process of Vibrio infection and opened a new perspective on the response of marine bivalves to pathogen infection.

From marine to freshwater environment: A review of the ecotoxicological effects of microplastics

Microplastics (MPs) have been widely detected in the world's water, which may pose a significant threat to the ecosystem as a whole and have been a subject of much attention because their presence impacts seas, lakes, rivers, and even the Polar Regions. There have been numerous studies that report direct adverse effects on marine organisms, but only a few have explored their ecological effects on freshwater organisms. In this field, there is still a lack of a systematic overview of the toxic effects and mechanisms of MPs on aquatic organisms, as well as a consistent understanding of the potential ecological consequences. This review describes the fate and impact on marine and freshwater aquatic organisms. Further, we examine the toxicology of MPs in order to uncover the relationship between aquatic organism responses to MPs and ecological disorders. In addition, an overview of the factors that may affect the toxicity effects of MPs on aquatic organisms was presented along with a brief examination of their identification and characterization. MPs were discussed in terms of their physicochemical properties in relation to their toxicological concerns regarding their bioavailability and environmental impact. This paper focuses on the progress of the toxicological studies of MPs on aquatic organisms (bacteria, algae, Daphnia, and fish, etc.) of different trophic levels, and explores its toxic mechanism, such as behavioral alternations, metabolism disorders, immune response, and poses a threat to the composition and stability of the ecosystem. We also review the main factors affecting the toxicity of MPs to aquatic organisms, including direct factors (polymer types, sizes, shapes, surface chemistry, etc.) and indirect factors (persistent organic pollutants, heavy metal ions, additives, and monomer, etc.), and the future research trends of MPs ecotoxicology are also pointed out. The findings of this study will be helpful in guiding future marine and freshwater rubbish studies and management strategies.

Toxicity of ceria nanoparticles to the regeneration of freshwater planarian Dugesia japonica: The role of biotransformation

Cerium oxide nanoparticles (n-CeO₂) have wide applications ranging from industrial to consumer products, which would inevitably lead to their release into the environment. Despite the toxicity of n-CeO₂ on aquatic organisms has been largely reported, research on developing organisms is still lacking. In this study, we investigate the toxic effects of n-CeO₂ on the stem cells, tissue- and neuro-regeneration, using freshwater planarian Dugesia japonica as a model. Effects of bulk sized (μ-) CeO₂ and ionic Ce (Ce³⁺) were compared with that of n-CeO₂ to explore the origin of the toxic effects of n-CeO₂. No overt toxicity was observed in μ-CeO₂ treatment. n-CeO₂ not only impaired the homeostasis of normal planarians, but also inhibited the regeneration processes of regenerated planarians, demonstrated by the inhibited blastema growth, disturbed antioxidant defense system at molecular levels, elevated DNA-damage and decreased stem cell proliferation. Regenerating organisms are more susceptible to n-CeO₂ than the normal ones. Ce³⁺ exhibited significantly higher toxicity than n-CeO₂, even though the total Ce uptake is 0.2 % less in Ce³⁺ than in n-CeO₂ treated in planarian. X-ray absorption near edge spectroscopy (XANES) analysis revealed that 12.8 % of n-CeO₂ (5.95 mg/kg Ce per planarian) was transformed to Ce³⁺ after interaction with planarian, suggesting that biotransformation at the nano-bio interface might play an important role in the observed toxicity. Since the biotransformation of n-CeO₂ is a slow process, it may cause long-term chronic toxicity to planarians due to the slow while sustained release of toxic Ce³⁺ ions.

Graphene oxide disruption of homeostasis and regeneration processes in freshwater planarian Dugesia japonica via intracellular redox deviation and apoptosis

The aquatic system is a major sink for engineered nanomaterials released into the environment. Here, we assessed the toxicity of graphene oxide (GO) using the freshwater planarian Dugesia japonica, an invertebrate model that has been widely used for studying the effects of toxins on tissue regeneration and neuronal development. GO not only impaired the growth of normal (homeostatic) worms, but also inhibited the regeneration processes of regenerating (amputated) worms, with LC₁₀ values of 9.86 mg/L and 9.32 mg/L for the 48-h acute toxicity test, respectively. High concentration (200 mg/L) of GO killed all the worms after 3 (regenerating) or 4 (homeostasis) days of exposure. Whole-mount in situ hybridization (WISH) and immunofluorescence analyses suggest GO impaired stem cell proliferation and differentiation, and subsequently caused cell apoptosis and oxidative DNA damage during planarian regeneration. Mechanistic analysis suggests that GO disturbed the antioxidative system (enzymatic and non-enzymatic) and energy metabolism in the planarian at both molecular and genetic levels, thus causing reactive oxygen species (ROS) over accumulation and oxidative damage, including oxidative DNA damage, loss of mitochondrial membrane integrity, lack of energy supply for cell differentiation and proliferation leading to retardance of neuron regeneration. The intrinsic oxidative potential of GO contributes to the GO-induced toxicity in planarians. These data suggest that GO in aquatic systems can cause oxidative stress and neurotoxicity in planarians. Overall, regenerated tissues are more sensitive to GO toxicity than homeostatic ones, suggesting that careful handling and appropriate decisions are needed in the application of GO to achieve healing and tissue regeneration.

The feedback loop between calcineurin, calmodulin-dependent protein kinase II, and nuclear factor of activated T-cells regulates the number of GABAergic neurons during planarian head regeneration

Disturbances in the excitatory/inhibitory balance of brain neural circuits are the main source of encephalopathy during neurodevelopment. Changes in the function of neural circuits can lead to depolarization or repeat rhythmic firing of neurons in a manner similar to epilepsy. GABAergic neurons are inhibitory neurons found in all the main domains of the CNS. Previous studies suggested that DjCamkII and DjCaln play a crucial role in the regulation of GABAergic neurons during planarian regeneration. However, the mechanisms behind the regeneration of GABAergic neurons have not been fully explained. Herein, we demonstrated that DjCamkII and DjCaln were mutual negative regulation during planarian head regeneration. DjNFAT exerted feedback positive regulation on both DjCaln and DjCamkII. Whole-mount in situ hybridization (WISH) and fluorescence in situ hybridization (FISH) revealed that DjNFAT was predominantly expressed in the pharynx and parenchymal cells in intact planarian. Interestingly, during planarian head regeneration, DjNFAT was predominantly located in the newborn brain. Down-regulation of DjNFAT led to regeneration defects in the brain including regenerative brain became small and the lateral nerves cannot be regenerated completely, and a decreasein the number of GABAergic neurons during planarian head regeneration. These findings suggest that the feedback loop between DjCaln, DjCamkII, and DjNFAT is crucial for the formation of GABAergic neurons during planarian head regeneration.

Sodium Benzoate Delays the Development of Drosophila melanogaster Larvae and Alters Commensal Microbiota in Adult Flies

Sodium benzoate (SB), the sodium salt of benzoic acid, is widely used as a preservative in foods and drinks. The toxicity of SB to the human body attracted people’s attention due to the excessive use of preservatives and the increased consumption of processed and fast foods in modern society. The SB can inhibit the growth of bacteria, fungi, and yeast. However, less is known of the effect of SB on host commensal microbial community compositions and their functions. In this study, we investigated the effect of SB on the growth and development of Drosophila melanogaster larvae and whether SB affects the commensal microbial compositions and functions. We also attempted to clarify the interaction between SB, commensal microbiota and host development by detecting the response of commensal microbiota after the intervention. The results show that SB significantly retarded the development of D. melanogaster larvae, shortened the life span, and changed the commensal microbial community. In addition, SB changed the transcription level of endocrine coding genes such as ERR and DmJHAMT. These results indicate that the slow down in D. melanogaster larvae developmental timing and shortened life span of adult flies caused by SB intake may result from the changes in endocrine hormone levels and commensal microbiota. This study provided experimental data that indicate SB could affect host growth and development of D. melanogaster through altering endocrine hormone levels and commensal microbial composition.

Identification and characterization of Deoxyribonuclease II in planarian Dugesia japonica

Deoxyribonuclease II (DNase II) has been found to regulate inflammation, autoimmunity and apoptosis in vertebrates and invertebrates. The strong capacity of degrading DNA makes DNase II play an important role in the immune process. Planarian has become one of the model references due to its strong immune system, the environment they live makes planarians face the threat of microorganisms and injury, the strong immune system can protect planarians from the threat of bacterial and infection. In this study, we found that there was DNase in the lysis buffer of planarians, then we acquired the sequence of DjDN2s (Dugesia japonica DNase2s) and confirmed the DjDN2s were conserved DNase IIs. The predicted structure showed the active sites and binding patterns of DjDN2s. Whole-mount in situ hybridization results showed DjDN2s mainly expressed in immune organs. Quantitative real-time PCR revealed that the expression of DjDN2s upregulated in varying degrees when got hurt and challenged with bacteria, and the knockdown of DjDN2s led to the slower repair of wound. The recombinant phages which take DjDN2 also had the ability to degrade DNA and clear young biofilm of Gram-negative bacteria. Collectively, DNase II of planarian might play a role in the antimicrobial response and wound-induced response.

Roles of ubiquitination in the crosstalk between tumors and the tumor microenvironment (Review)

The interaction between a tumor and the tumor microenvironment (TME) plays a key role in tumorigenesis and tumor progression. Ubiquitination, a crucial post-translational modification for regulating protein degradation and turnover, plays a role in regulating the crosstalk between a tumor and the TME. Thus, identifying the roles of ubiquitination in the process may assist researchers to investigate the mechanisms underlying tumorigenesis and tumor progression. In the present review article, new insights into the substrates for ubiquitination that are involved in the regulation of hypoxic environments, angiogenesis, chronic inflammation-mediated tumor formation, and the function of cancer-associated fibroblasts and infiltrating immune cells (tumor-associated macrophages, T-cells, myeloid-derived suppressor cells, dendritic cells, and natural killer cells) are summarized. In addition, the potential targets of the ubiquitination proteasome system within the TME for cancer therapy and their therapeutic effects are reviewed and discussed.

Betaine Regulates the Production of Reactive Oxygen Species Through Wnt10b Signaling in the Liver of Zebrafish

When fish are under oxidative stress, levels of reactive oxygen species (ROS) are chronically elevated, which play a crucial role in fish innate immunity. In the present study, the mechanism by which betaine regulates ROS production via Wnt10b/β-catenin signaling was investigated in zebrafish liver. Our results showed that betaine enrichment of diet at 0.1, 0.2 and 0.4 g/kg induced Wnt10b and β-catenin gene expression, but suppressed GSK-3β expression in zebrafish liver. In addition, the content of superoxide anion (O₂^·−), hydrogen peroxide (H₂O₂) and hydroxyl radical (·OH) was decreased by all of the experimental betaine treatments. However, betaine enrichment of diet at 0.1, 0.2 and 0.4 g/kg enhanced gene expression and activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) in zebrafish liver. In addition, Wnt10b RNA was further interfered in zebrafish, and the results of Wnt10b RNAi indicated that Wnt10b plays a key role in regulating ROS production and antioxidant enzyme activity. In conclusion, betaine can inhibit ROS production in zebrafish liver through the Wnt10b/β-catenin signaling pathway.

DjPtpn11 is an essential modulator of planarian (Dugesia japonica) regeneration

Freshwater planarian Dugesia japonica is an excellent model organism for investigating stem cell behavior during regeneration. Despite studies showing that numerous genetic factors are involved in regeneration, much more research is required to fully understand the molecular mechanisms that orchestrate regeneration. In this study, we identified an evolutionarily conserved gene DjPtpn11(DjShp2). DjPtpn11 transcripts are expressed in neoblasts and some differentiated cells, with a high expression at the newly formed blastema. Its silencing by RNA interference (RNAi) affected anterior regeneration and inhibited the regeneration of posterior regions, including cholinergic and serotonergic neuron regeneration. In adult planarians, DjPtpn11 knockdown did not affect neoblast survival and proliferation but might prevent the stem cell migration and differentiation through ERK signaling. DjPtpn11 was demonstrated to be necessary for the anterior blastema cell differentiation partially via regulating ERK-DjMkpA activity. DjPtpn11 also influenced posterior specification via DjIslet, suggesting that DjPtpn11 may be involved in regulating the Wnt signaling pathway during the development of posterior blastema. Together, these data identified that DjPtpn11 is an essential modulator for the regeneration of planarians, and it may influence the appropriate differentiation of blastema cells.

Definition of large niche after Cesarean section based on prediction of postmenstrual spotting: Chinese cohort study in non-pregnant women

OBJECTIVE

A large niche after Cesarean section (CS) is associated with long-term complications, of which postmenstrual spotting is associated positively with the size of the niche. However, the diagnosis of a large niche in the literature is inconsistent and the definition is largely subjective. The aim of this study was to generate a definition for a large niche in non-pregnant women based on the presence of postmenstrual spotting.

METHODS

Women who had undergone CS in our hospital between January 2012 and June 2017 were selected randomly from our database, contacted by telephone and subsequently examined between January 2016 and June 2020. Eligible for inclusion were non-pregnant women who had their last CS more than 1 year earlier and agreed to undergo transvaginal sonography (TVS). All participants underwent examination of their CS scar by TVS (two-dimensional color Doppler) during the midfollicular phase. Niche depth, length, width, residual myometrial thickness (RMT), adjacent myometrial thickness (AMT) and ratio of niche depth/AMT were recorded. Women diagnosed with a niche, defined as an indentation at the site of the CS with a depth of at least 2 mm, were classified into two groups (symptomatic or asymptomatic) according to whether they experienced postmenstrual spotting. Logistic regression analysis was used to establish the best cut-off values for the niche parameters to predict postmenstrual spotting. A new definition was generated based on the niche parameters with the highest area under the receiver-operating-characteristics (ROC) curve (AUC) for the prediction of postmenstrual spotting.

RESULTS

A total of 727 women who had a CS > 1 year earlier underwent TVS examination, of whom 263 were diagnosed with a niche (prevalence of 36.2%). Of these, 160 women experienced postmenstrual spotting and 103 were asymptomatic. The three variables with the highest AUC for prediction of postmenstrual spotting were niche depth/AMT ratio (AUC, 0.798; 95% CI, 0.745-0.852), niche depth (AUC, 0.731; 95% CI, 0.668-0.795) and RMT (AUC, 0.683; 95% CI, 0.618-0.748). Based on the best cut-offs according to ROC-curve analysis, a large niche was defined as: niche depth ≥ 0.50 cm, RMT ≤ 0.21 cm or niche depth/AMT ratio ≥ 0.56. The prevalence of a large niche according to this definition was 22.4% (163/727). The new definition had a specificity of 61.17% (95% CI, 52.34-70.41%) and sensitivity of 76.87% (95% CI, 70.28-84.16%) for a large niche.

CONCLUSION

This study has provided a new definition for a large niche after CS. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

DjApi5 is required for homeostasis in planarian Dugesia japonica

Orchestrated apoptosis in planarian Dugesia japonica is very important for its degrowth and regeneration. Apoptosis Inhibitor-5 (API5) is an anti-apoptotic factor that negatively regulates cell apoptosis. We characterized the conserved structure of DjApi5, however, the biological function of DjApi5 in planarians needs further investigation. In this study, we found that DjApi5 and its interacting molecular DjAcinus are required for planarian homeostasis, which may be correlated with their specific localization in neoblasts in addition to their anti-apoptosis functions. We further demonstrated the increased expression of DjApi5 during planarian regeneration, and DjApi5 deficiency affects normal regeneration processes. These results indicated new functions of DjApi5 in development.

Protein Arginine Methyltransferase 1 and its Dynamic Regulation Associated with Cellular Processes and Diseases

Abstract:

Post-translational modifications (PTMs) of proteins influence protein degradation, protein- protein interactions, expression of genes, and intracellular signal transduction, thereby regulating major life processes. Among the PTMs occurring within the cytoplasm and nucleus, the most commonly studied one is the arginine methylation of proteins catalyzed by PRMTs. PRMT1 is the most excellent and extensively studied member of the PRMT family. PRMT1 occurs in various isoforms, and the unique sequence splicing of each of these isoforms encodes differential proteins that exhibit different cellular localization, substrate specificity, and enzyme activity. In addition to methylating histones, PRMT1 also methylates a large number of non-histone substrates that regulate a broad range of cellular processes. In recent years, research has revealed an increasing number of pathological diseases caused by the misregulation and aberrant expression of PRMT1, demonstrating the potential of PRMT1 as an effective biomarker for drug targets. In this context, the present study discusses the structural characteristics and the biological functions of PRMT1.

Practical applications:

Several diseases originate from aberrant post-translational modifications. The misregulation of the arginine methylation of proteins, which is regulated by PRMTs and influences a series of cellular activities, leads to developmental abnormalities and physiological diseases. PRMT1, which accounts for 85% of the activity of PRMTs, is involved in several cellular processes occurring in various diseases. Multiple inhibitors have been developed and studied for their potential as biomarkers and suitable drug targets in clinical application. The present report summarizes the findings of the most recent studies focusing on the structural characteristics, splicing, substrates, and biological functions of PRMT1, to contribute to future research for deciphering the molecular mechanisms of PRMT1 and drug improvement.

A prospective study on vulvovaginal candidiasis: multicentre molecular epidemiology of pathogenic yeasts in China

BACKGROUND

Vulvovaginal candidiasis (VVC) is frequent in women of reproductive age, but very limited data are available on the epidemiology in cases of VVC in China.

OBJECTIVES

The current study has been conducted to reveal the prevalence, species distribution of yeast causing VVC and molecular genetics of Candida albicans in China.

METHODS

Vaginal swabs were collected from 543 VVC outpatients recruited in 12 hospitals in China between September 2017 and March 2018. They were preliminarily incubated on Sabouraud dextrose agar and then positive subjects of which were then transmitted to our institute for further identification. CHROMagar™ was used to isolate Candida species, and all isolates were finally identified by DNA sequencing. Multilocus sequence typing (MLST) was used to analyse phylogenetic relationships of the various C. albicans isolates.

RESULTS

Eleven different yeast species were identified in 543 isolates, among which C. albicans (84.7%) was the most frequent, followed by C. glabrata (8.7%). We obtained 117 unique diploid sequence types from 451 clinical C. albicans isolates and 92 isolates (20.4%) belonged to a New Clade. All the strains appearing in the New Clade were from northern China and they were isolated from non-recurrent VVC.

CONCLUSIONS

Our findings suggest that C. albicans are still the main cause of VVC in China and the majority of C. albicans isolates belongs to Clade 1 with DST 79 and DST 45 being two most common. Moreover, the New Clade revealed in our study seems to be specific to northern China.

An Overview on Functional and Structural Properties of Monomeric and Multimeric β-thymosin in Invertebrates

β-thymosin 4 (Tβ4) is a prototypical actin-monomer sequestering protein that plays an important role in mammalian cells and tissues. In vertebrates, Tβ4 is involved in various physiological and pathophysiological processes, such as angiogenesis, hair follicle and hair regeneration, nervous system development, inflammatory response, wound healing, tumour metastasis, and liver and heart protection. Additionally, thymosin domain-containing protein was discovered in invertebrates and was recently shown to be more homologous to Tβ4. However, the structural and functional properties are more complex and diverse than those of Tβ4. In this review article, we will discuss in detail the structural and functional aspects of β-thymosin in invertebrates.

Effect of rare earth element lanthanum on lipid deposition and Wnt10b signaling in the liver of male zebrafish

This paper investigates the effect of lanthanum (La) on lipid deposition and Wnt10b signaling in the liver of male zebrafish with exposure of 0, 10, 20, and 30 μmol/L La. It suggests that La can be accumulated in liver, and its treatments decrease the activities and gene expression of enzymes related to fatty acid synthesis. The levels of total cholesterol (TC), triglyceride (TG), and nonesterified fatty acids (NEFA) as well as the size of lipid droplets are decreased by La treatments. Moreover, La treatments affect the composition of fatty acids and the content of nutrient elements. Meanwhile, they also induce the gene expression of wnt10b, β-catenin, pparα, and pparγ, but inhibit gsk-3β gene expression in liver. Further study on the result of wnt10b gene interference shows that Wnt10b/β-catenin signaling plays a crucial role in the regulatory process of hepatic lipid deposition. Taken together, our observations suggest that La accumulation affects lipid deposition in the liver of male zebrafish, and Wnt10b signaling pathway may be involved in this process.

β-Thymosin is an essential regulator of stem cell proliferation and neuron regeneration in planarian (Dugesia japonica)

β-Thymosin is a multifunctional peptide ubiquitously expressed in vertebrates and invertebrates. Many studies have found β-thymosin is critical for wound healing, angiogenesis, cardiac repair, hair regrowth, and anti-fibrosis in vertebrates, and plays an important role in antimicrobial immunity in invertebrates. However, whether β-thymosin participates in the regeneration of organisms is still poorly understood. In this study, we identified a β-thymosin gene in Dugesia japonica which played an important role in stem cell proliferation and neuron regeneration during the tissue repair process in D. japonica. Sequencing analysis showed that β-thymosin contained two conserved β-thymosin domains and two actin-binding motifs, and had a high similarity with other β-thymosins of invertebrates. In situ or fluorescence in situ hybridization analysis revealed that Djβ-thymosin was co-localized with DjPiWi in the neoblast cells of intact adult planarians and the blastema of regenerating planarians, suggesting Djβ-thymosin has a potential function of regeneration. Disruption Djβ-thymosin by RNA interference results in a slightly curled up head of planarian and stem cell proliferation defects. Additionally, we found that, upon amputation, Djβ-thymosin RNAi-treated animals had impaired regeneration ability, including impaired blastema formation, delayed eyespot formation, decreased brain area, and disrupted central CNS formation, implying Djβ-thymosin is an essential regulator of stem cell proliferation and neuron regeneration.

Evolution and Structure of API5 and Its Roles in Anti-Apoptosis

Apoptosis, also named programmed cell death, is a highly conserved physiological mechanism. Apoptosis plays crucial roles in many life processes, such as tissue development, organ formation, homeostasis maintenance, resistance against external aggression, and immune responses. Apoptosis is regulated by many genes, among which Apoptosis Inhibitor-5 (API5) is an effective inhibitor, though the structure of API5 is completely different from the other known Inhibitors of Apoptosis Proteins (IAPs). Due to its high expression in many types of tumors, API5 has received extensive attention, and may be an effective target for cancer treatment. In order to comprehensively and systematically understand the biological roles of API5, we summarized the evolution and structure of API5 and its roles in anti-apoptosis in this review.

CCDC114, DNAI2 and TOP2A involves in the effects of tibolone treatment on postmenopausal endometrium

BACKGROUND

This study aimed to explore the molecular mechanisms of tibolone treatment in postmenopausal women.

METHODS

The gene set enrichment profile, GSE12446, which includes 9 human endometrial samples from postmenopausal women treated with tibolone (tibolone group) and 9 control samples (control group), was downloaded from GEO database for analysis. Differentially expressed genes (DEGs) in tibolone vs. control groups were identified and then used for function and pathway enrichment analysis. Protein-protein interaction (PPI) network and module analyses were also performed. Finally, drug-target interaction was predicted for genes in modules, and then were validated in Pubmed.

RESULTS

A total of 238 up-regulated DEGs and 72 down-regulated DEGs were identified. These DEGs were mainly enriched in various biological processed and pathways, such as cilium movement (e.g., CCDC114 and DNAI2), calcium ion homeostasis, regulation of hormone levels and complement/coagulation cascades. PPI network contained 368 interactions and 166 genes, of which IGF1, DNALI1, CCDC114, TOP2A, DNAH5 and DNAI2 were the hue genes. A total of 96 drug-gene interactions were obtained, including 94 drugs and eight genes. TOP2A and HTR2B were found to be targets of 28 drugs and 38 drugs, respectively. Among the 94 obtained drugs, only 12 drugs were reported in studies, of which 7 drugs (e.g., epirubicin) were found to target TOP2A.

CONCLUSIONS

CCDC114 and DNAI2 might play important roles in tibolone-treated postmenopausal women via cilium movement function. TOP2A might be a crucial target of tibolone in endometrium of postmenopausal women.

Revisiting stacking interactions in tetrathiafulvalene and selected derivatives using tight-binding quantum chemical calculations and local coupled-cluster method

The engineering of supramolecular architectures needs accurate descriptions of the intermolecular interactions in crystal structures. Tetrathiafulvalene (TTF) is an effective building block used in the construction of promising functional materials. The parallel packing of the neutral TTF-TTF system was studied previously using the high-level quantum chemical method, advancing it as a valuable model system. The recently developed tight-binding quantum chemical method GFN2-xTB and local coupled-cluster method DLPNO-CCSD(T) were used to investigate the stacking interactions of TTF and selected derivatives deposited in the Cambridge Structural Database. Using the interaction energy of the TTF-TTF dimer calculated at the CCSD(T)/CBS level as the reference, the accuracies of the two methods are investigated. The energy decomposition analysis within the DLPNO-CCSD(T) framework reveals the importance of dispersion interaction in the TTF-related stacking systems. The dispersion interaction density plot vividly shows the magnitude and distribution of the dispersion interaction, providing a revealing insight into the stacking interactions in crystal structures. The results show that the GFN2-xTB and DLPNO-CCSD(T) methods could achieve accuracy at an affordable computational cost, which would be valuable in understanding the nature of parallel stacking in supramolecular systems.

Planarian gamma-interferon-inducible lysosomal thiol reductase (GILT) is required for gram-negative bacterial clearance

The powerful regenerative ability of planarians has long been a concern of scientists, but recently, their efficient immune system has attracted more and more attention from researchers. Gamma-interferon-inducible lysosomal thiol reductase (GILT) is related not only to antigen presentation but also to bacteria invasions. But the systematic studies are not yet to be conducted on the relationship between bacterial infection. Our study reveals for the first time that GILT of planarian (DjGILT) plays an essential role in the clearance of Gram-negative bacteria by conducting H₂O₂ concentration in planarians. In animals that DjGILT was silenced, it persisted for up to 9 days before all bacteria were cleared, compared with 6 days of the control group. When infected with E. coli and V. anguillarum, the level of H₂O₂ was significantly increased in DjGILT-silenced planarians, and concomitantly, mRNA level of C-type lectin DjCTL, which modulates agglutination and clearance efficiency of invading bacteria, was decreased. Further study showed that the decrease of H₂O₂ level led to a significant increase in DjCTL transcripts. Collectively, we proposed a mechanism model for the involvement of GILT gene in bacterial elimination. We have for the first time revealed the specific mechanism of GILT in innate immune response against bacterial infection.

Ubiquitination of Nonhistone Proteins in Cancer Development and Treatment

Ubiquitination, a crucial post-translation modification, regulates the localization and stability of the substrate proteins including nonhistone proteins. The ubiquitin-proteasome system (UPS) on nonhistone proteins plays a critical role in many cellular processes such as DNA repair, transcription, signal transduction, and apoptosis. Its dysregulation induces various diseases including cancer, and the identification of this process may provide potential therapeutic targets for cancer treatment. In this review, we summarize the regulatory roles of key UPS members on major nonhistone substrates in cancer-related processes, such as cell cycle, cell proliferation, apoptosis, DNA damage repair, inflammation, and T cell dysfunction in cancer. In addition, we also highlight novel therapeutic interventions targeting the UPS members (E1s, E2s, E3s, proteasomes, and deubiquitinating enzymes). Furthermore, we discuss the application of proteolysis-targeting chimeras (PROTACs) technology as a novel anticancer therapeutic strategy in modulating protein target levels with the aid of UPS.

A fluorescent molecular rotor probe for tracking plasma membranes and exosomes in living cells

A rotor-based probe MRMP-1 was designed and synthesized. MRMP-1 can bind to plasma membranes very quickly and stably with remarkable fluorescence enhancement. It can be used to monitor the dynamic changes in cell membranes in real-time under stimuli conditions. Importantly, MRMP-1 is the first rotor-based fluorescent sensor to label exosomes in living cells.

Elucidating the origin of the surface functionalization - dependent bacterial toxicity of graphene nanomaterials: Oxidative damage, physical disruption, and cell autolysis

Previous studies have shown that the toxicity of graphene nanomaterials (GNMs) to bacteria are related to the surface functionalization, however, the involved mechanisms are not fully understood. The present study aims to explore the toxic mechanisms of differentially functionalized GNMs to bacteria from the aspects of physical interaction, oxidative damage and cell autolysis. Three basic functionalization of GNMs including carboxylation (G-COOH), hydroxylation (G-OH) and amination (G-NH₂) were studied. G-COOH (66% viability vs CT group) and G-OH (54%) graphene showed higher toxicity to E. coli than G-NH₂ (96%) within 3 h at a concentration of 50 mg/L. The three materials showed distinct physical interaction modes with bacterial cells. G-COOH and G-OH contact with cell membrane via their sharp edges thus causing more damage than G-NH₂ which covered the bacteria attaching along the basal plane. The three GNMs showed similar radical generation capacities, thus the direct generation of radicals is not the mechanism causing the toxicity. Instead, the GNMs can oxidize the cellular antioxidant glutathione (GSH) thereby causing oxidative damage. The oxidative capacity follows the order: G-COOH > G-OH > G-NH₂, which correlated with the antibacterial activity. Cell autolysis, the degradation of cell wall component peptidoglycan, was found to be a new mechanism inducing the death of bacteria. G-COOH and G-OH caused more cell autolysis than G-NH₂, which accounts partially for the different toxicity of the three GNMs. The findings provide significant insights into the mechanism of GNMs toxicity to bacteria for not only the risk assessment of GNMs but also the design of graphene based antibacterial materials.

Different classes of small RNAs are essential for head regeneration in the planarian Dugesia japonica

BACKGROUND

Planarians reliably regenerate all body parts after injury, including a fully functional head and central nervous system. But until now, the expression dynamics and functional role of miRNAs and other small RNAs during the process of head regeneration are not well understood. Furthermore, little is known about the evolutionary conservation of the relevant small RNAs pathways, rendering it difficult to assess whether insights from planarians will apply to other taxa.

RESULTS

In this study, we applied high throughput sequencing to identify miRNAs, tRNA fragments and piRNAs that are dynamically expressed during head regeneration in Dugesia japonica. We further show that knockdown of selected small RNAs, including three novel Dugesia-specific miRNAs, during head regeneration induces severe defects including abnormally small-sized eyes, cyclopia and complete absence of eyes.

CONCLUSIONS

Our findings suggest that a complex pool of small RNAs takes part in the process of head regeneration in Dugesia japonica and provide novel insights into global small RNA expression profiles and expression changes in response to head amputation. Our study reveals the evolutionary conserved role of miR-124 and brings further promising candidate small RNAs into play that might unveil new avenues for inducing restorative programs in non-regenerative organisms via small RNA mimics based therapies.

The Wnt/Ca2+ signaling pathway is essential for the regeneration of GABAergic neurons in planarian Dugesia japonica

The growth and differentiation of neurons are critical events in the establishment of proper neuron connectivity and function. Planarians have a remarkable ability to completely regenerate a functional nervous system from a pluripotent stem cell population. Thus, planarians provide a powerful model to identify genes required for neuronal differentiation in vivo. The Wnt/Ca²⁺ signaling pathway is crucial for cancer development, arousing inflammatory responses, and neurodegeneration. We analyzed the expression patterns and RNAi phenotypes for members of the Wnt/Ca²⁺ signaling pathway in the planarian, Dugesia japonica. The expression of DjWnt5a, DjPLC-β, DjCamKII, and DjCaln during regeneration was surprisingly similar and revealing in the regenerated brain. RNAi knockdown of DjWnt5a, DjPLC-β, DjCamKII, and DjCaln led to defects in regenerated brains including brain partial deletions, incompact phenotypes at the posterior of the new brain, and lateral branches, which could not regenerate. Furthermore, the expressions of GAD and the number of GABAergic neurons decreased. Together, these results suggest that the Wnt/Ca²⁺ signaling pathway is required for GABAergic neuron regeneration.

Deacetylase-independent function of SIRT6 couples GATA4 transcription factor and epigenetic activation against cardiomyocyte apoptosis

SIRT6 deacetylase activity improves stress resistance via gene silencing and genome maintenance. Here, we reveal a deacetylase-independent function of SIRT6, which promotes anti-apoptotic gene expression via the transcription factor GATA4. SIRT6 recruits TIP60 acetyltransferase to acetylate GATA4 at K328/330, thus enhancing its chromatin binding capacity. In turn, GATA4 inhibits the deacetylase activity of SIRT6, thus ensuring the local chromatin accessibility via TIP60-promoted H3K9 acetylation. Significantly, the treatment of doxorubicin (DOX), an anti-cancer chemotherapeutic, impairs the SIRT6-TIP60-GATA4 trimeric complex, blocking GATA4 acetylation and causing cardiomyocyte apoptosis. While GATA4 hyperacetylation-mimic retains the protective effect against DOX, the hypoacetylation-mimic loses such ability. Thus, the data reveal a novel SIRT6-TIP60-GATA4 axis, which promotes the anti-apoptotic pathway to prevent DOX toxicity. Targeting the trimeric complex constitutes a new strategy to improve the safety of DOX chemotherapy in clinical application.

Synergy between SIRT1 and SIRT6 helps recognize DNA breaks and potentiates the DNA damage response and repair in humans and mice

The DNA damage response (DDR) is a highly orchestrated process but how double-strand DNA breaks (DSBs) are initially recognized is unclear. Here, we show that polymerized SIRT6 deacetylase recognizes DSBs and potentiates the DDR in human and mouse cells. First, SIRT1 deacetylates SIRT6 at residue K33, which is important for SIRT6 polymerization and mobilization toward DSBs. Then, K33-deacetylated SIRT6 anchors to γH2AX, allowing its retention on and subsequent remodeling of local chromatin. We show that a K33R mutation that mimics hypoacetylated SIRT6 can rescue defective DNA repair as a result of SIRT1 deficiency in cultured cells. These data highlight the synergistic action between SIRTs in the spatiotemporal regulation of the DDR and DNA repair in humans and mice.

Extreme Environmental Stress-Induced Biological Responses in the Planarian

Planarians are bilaterally symmetric metazoans of the phylum Platyhelminthes. They have well-defined anteroposterior and dorsoventral axes and have a highly structured true brain which consists of all neural cell types and neuropeptides found in a vertebrate. Planarian flatworms are famous for their strong regenerative ability; they can easily regenerate any part of the body including the complete neoformation of a functional brain within a few days and can survive a series of extreme environmental stress. Nowadays, they are an emerging model system in the field of developmental, regenerative, and stem cell biology and have offered lots of helpful information for these realms. In this review, we will summarize the response of planarians to some typical environmental stress and hope to shed light on basic mechanisms of how organisms interact with extreme environmental stress and survive it, such as altered gravity, temperature, and oxygen, and this information will help researchers improve the design in future studies.