A platform utilizing Drosophila ovulation for nonhormonal contraceptive screening.

A significant unmet need for new contraceptive options for both women and men remains due to side-effect profiles, medical concerns, and the inconvenience of many currently available contraceptive products. Unfortunately, the development of novel nonsteroidal female contraceptive medicine has been stalled in the last couple of decades due to the lack of effective screening platforms. Drosophila utilizes conserved signaling pathways for follicle rupture, a final step in ovulation that is essential for female reproduction. Therefore, we explored the potential to use Drosophila as a model to screen compounds that could inhibit follicle rupture and be nonsteroidal contraceptive candidates. Using our ex vivo follicle rupture assay, we screened 1,172 Food and Drug Administration (FDA)-approved drugs and identified six drugs that could inhibit Drosophila follicle rupture in a dose-dependent manner. In addition, we characterized the molecular actions of these drugs in the inhibition of adrenergic signaling and follicle rupture. Furthermore, we validated that three of the four drugs consistently inhibited mouse follicle rupture in vitro and that two of them did not affect progesterone production. Finally, we showed that chlorpromazine, one of the candidate drugs, can significantly inhibit mouse follicle rupture in vivo. Our work suggests that Drosophila ovulation is a valuable platform for identifying lead compounds for nonsteroidal contraceptive development and highlights the potential of these FDA-approved drugs as novel nonsteroidal contraceptive agents.

An ex vivo ovulation system enables the discovery of novel ovulatory pathways and nonhormonal contraceptive candidates†.

Ovulation is an integral part of women's menstrual cycle and fertility. Understanding the mechanisms of ovulation has broad implications for the treatment of anovulatory diseases and the development of novel contraceptives. Now, few studies have developed effective models that both faithfully recapitulate the hallmarks of ovulation and possess scalability. We established a three-dimensional encapsulated in vitro follicle growth (eIVFG) system that recapitulates folliculogenesis and produces follicles that undergo ovulation in a controlled manner. Here, we determined whether ex vivo ovulation preserves molecular signatures of ovulation and demonstrated its use in discovering novel ovulatory pathways and nonhormonal contraceptive candidates through a high-throughput ovulation screening. Mature murine follicles from eIVFG were induced to ovulate ex vivo using human chorionic gonadotropin and collected at 0, 1, 4, and 8 hours post-induction. Phenotypic analyses confirmed key ovulatory events, including cumulus expansion, oocyte maturation, follicle rupture, and luteinization. Single-follicle RNA-sequencing analysis revealed the preservation of ovulatory genes and dynamic transcriptomic profiles and signaling. Soft clustering identified distinct gene expression patterns and new pathways that may critically regulate ovulation. We further used this ex vivo ovulation system to screen 21 compounds targeting established and newly identified ovulatory pathways. We discovered that proprotein convertases activate gelatinases to sustain follicle rupture and do not regulate luteinization and progesterone secretion. Together, our ex vivo ovulation system preserves molecular signatures of ovulation, presenting a new powerful tool for studying ovulation and anovulatory diseases as well as for establishing a high-throughput ovulation screening to identify novel nonhormonal contraceptives for women.

Hepatic NLRP3-Derived Hsp70 Binding to TLR4 Mediates MASLD to MASH Progression upon Inhibition of PP2A by Harmful Algal Bloom Toxin Microcystin, a Second Hit.

Harmful algal bloom toxin microcystin has been associated with metabolic dysfunction-associated steatotic liver disease (MASLD) progression and hepatocellular carcinoma, though the mechanisms remain unclear. Using an established mouse model of MASLD, we show that the NLRP3-Hsp70-TLR4 axis drives in part the inflammation of the liver lobule that results in the progression of MASLD to metabolic dysfunction-associated steatohepatitis (MASH). Results showed that mice deficient in NLRP3 exhibited decreased MASH pathology, blocked Hsp70 expression, and co-binding with NLRP3, a crucial protein component of the liver inflammasome. Hsp70, both in the liver lobule and extracellularly released in the liver vasculature, acted as a ligand to TLR4 in the liver, primarily in hepatocytes to activate the NF-κB pathway, ultimately leading to hepatic cell death and necroptosis, a crucial pathology of MASH progression. The above studies show a novel insight into an inflammasome-triggered Hsp70-mediated inflammation that may have broader implications in MASLD pathology. MASLD to MASH progression often requires multiple hits. One of the mediators of progressive MASLD is environmental toxins. In this research report, we show for the first time a novel mechanism where microcystin-LR, an environmental toxin, advances MASLD to MASH by triggering the release of Hsp70 as a DAMP to activate TLR4-induced inflammation in the liver.

Preserving Oocytes in Oncofertility†.

The prodigious rise of cancer survival rates enables many cancer survivors to live long lives. Therefore, the side effects of cancer treatments as well as the long-term quality of life after cancer have become more relevant. Ovarian toxicity is a major off-target effect of anticancer agents for childhood and young adult female cancer patients. Both chemotherapy and irradiation have been demonstrated to damage the ovary and increase the risks of premature ovarian failure (POF), early menopause, ovarian endocrine disorders, and sub- or infertility. Oncofertility is an emerging and multidisciplinary research and medical field that focuses on providing cancer patients with fertility preservation options. Oocyte quality and quantity are one of the most important factors to determine women's fertility success; therefore, preserving oocytes is paramount for maintaining the ability of young female cancer patients' reproduction after their recovery. This review summarizes peer-reviewed literature on current oocyte preservation options in oncofertility. We describe in-depth oocyte and embryo cryopreservation, ovarian suppression, ovarian tissue cryopreservation, in vitro maturation, ovarian transposition, and adjuvant therapy. Further, we discuss current guidelines and practices of female fertility preservation that cover preserving oocytes.

Identification of nonmonotonic concentration-responses in Tox21 high-throughput screening estrogen receptor assays.

Environmental endocrine-disrupting chemicals (EDCs) interfere with the metabolism and actions of endogenous hormones. It has been well documented in numerous in vivo and in vitro studies that EDCs can exhibit nonmonotonic dose response (NMDR) behaviors. Not conforming to the conventional linear or linear-no-threshold response paradigm, these NMDR relationships pose practical challenges to the risk assessment of EDCs. In the meantime, the endocrine signaling pathways and biological mechanisms underpinning NMDR remain incompletely understood. The US Tox21 program has conducted in vitro cell-based high-throughput screening assays for estrogen receptors (ER), androgen receptors, and other nuclear receptors, and screened the 10 K-compound library for potential endocrine activities. Using 15 concentrations across several orders of magnitude of concentration range and run in both agonist and antagonist modes, these Tox21 assay datasets contain valuable quantitative information that can be explored to evaluate the nonlinear effects of EDCs and may infer potential mechanisms. In this study we analyzed the concentration-response curves (CRCs) in all 8 Tox21 ERα and ERß assays by developing clustering and classification algorithms customized to the datasets to identify various shapes of CRCs. After excluding NMDR curves likely caused by cytotoxicity, luciferase inhibition, or autofluorescence, hundreds of compounds were identified to exhibit Bell or U-shaped CRCs. Bell-shaped CRCs are about 7 times more frequent than U-shaped ones in the Tox21 ER assays. Many compounds exhibit NMDR in at least one assay, and some EDCs well-known for their NMDRs in the literature were also identified, suggesting their nonmonotonic effects may originate at cellular levels involving transcriptional ER signaling. The developed computational methods for NMDR identification in ER assays can be adapted and applied to other high-throughput bioassays.

Task Offloading Strategy Based on Mobile Edge Computing in UAV Network.

When an unmanned aerial vehicle (UAV) performs tasks such as power patrol inspection, water quality detection, field scientific observation, etc., due to the limitations of the computing capacity and battery power, it cannot complete the tasks efficiently. Therefore, an effective method is to deploy edge servers near the UAV. The UAV can offload some of the computationally intensive and real-time tasks to edge servers. In this paper, a mobile edge computing offloading strategy based on reinforcement learning is proposed. Firstly, the Stackelberg game model is introduced to model the UAV and edge nodes in the network, and the utility function is used to calculate the maximization of offloading revenue. Secondly, as the problem is a mixed-integer non-linear programming (MINLP) problem, we introduce the multi-agent deep deterministic policy gradient (MADDPG) to solve it. Finally, the effects of the number of UAVs and the summation of computing resources on the total revenue of the UAVs were simulated through simulation experiments. The experimental results show that compared with other algorithms, the algorithm proposed in this paper can more effectively improve the total benefit of UAVs.

Varied effects of doxorubicin (DOX) on the corpus luteum of C57BL/6 mice during early pregnancy†.

Certain chemotherapeutic drugs are toxic to ovarian follicles. The corpus luteum (CL) is normally developed from an ovulated follicle for producing progesterone (P4) to support early pregnancy. To fill in the knowledge gap about effects of chemotherapy on the CL, we tested the hypothesis that chemotherapy may target endothelial cells and/or luteal cells in the CL to impair CL function in P4 steroidogenesis using doxorubicin (DOX) as a representative chemotherapeutic drug in mice. In both mixed background mice and C57BL/6 mice, a single intraperitoneal injection of DOX (10 mg/kg) on 0.5-day postcoitum (D0.5, postovulation) led to ~58% D3.5 mice with serum P4 levels lower than the serum P4 range in the phosphate buffer saline-treated control mice. Further studies in the C57BL/6 ovaries revealed that CLs from DOX-treated mice with low P4 levels had less defined luteal cords and disrupted collagen IV expression pattern, indicating disrupted capillary, accompanied with less differentiated luteal cells that had smaller cytoplasm and reduced StAR expression. DOX-treated ovaries had increased granulosa cell death in the growing follicles, reduced proliferating cell nuclear antigen-positive endothelial cells in the CLs, enlarged lipid droplets, and disrupted F-actin in the luteal cells. These novel data suggest that the proliferating endothelial cells in the developing CL may be the primary target of DOX to impair the vascular support for luteal cell differentiation and subsequently P4 steroidogenesis. This study fills in the knowledge gap about the toxic effects of chemotherapy on the CL and provides critical information for risk assessment of chemotherapy in premenopausal patients.

The integration of proportion and cell counts of stromal, not intratumoral, PD-1+ tumor-infiltrating lymphocytes has prognostic significance in esophageal squamous cell carcinoma.

The present study aimed to investigate the prognostic effect of intratumoral and stromal exhausted tumor-infiltrating lymphocytes (TILs) on operable esophageal cancer patients. We performed a retrospective cohort study by consecutively recruiting 142 patients with esophageal cancer. The proportion and cell counts of intratumoral and stromal PD-1+ TILs in tumor microenvironment were independently evaluated by two pathologists. Neither proportion nor cell counts of intratumoral PD-1+ TILs was associated with prognosis (p > 0.05). However, patients with the proportion of stromal PD1+ TILs >20% had the median overall survival (OS) at 19 months, significantly longer than those with the proportion = 20%. The adjusted hazard ratio (HR) was 1.49 (95%CI 0.82, 2.69). Patients with cell counts of stromal PD1+ TILs = 18/ high-power field (HPF) had the median disease-free survival (DFS) at 10 months. However, patients with cell counts>18/HPF had the median DFS at 48 months (p = 0.037), and the adjusted HR was 0.59 (95%CI 0.35, 1.01). Compared with patients with proportion = 20% and cell counts >18/HPF of stromal PD1+ TILs, patients with proportion = 20% and cell counts = 18/HPF, proportion >20% and cell counts >18/HPF, and proportion >20% and cell counts = 18/HPF, had the adjusted HRs increased to 3.73, 3.36 and 3.99 for DFS (p for trend being 0.030) and the adjusted HRs increased to 2.95, 3.64 and 3.82 (p for trend being 0.015) for OS, respectively. The integration of proportion and cell counts of PD-1+ stromal TILs has a significant association with the relapse and overall survival of esophageal cancer patients. Further prospective studies are warranted.

Laparoscopic proximal gastrectomy with double-tract reconstruction for upper third gastric cancer.

BACKGROUND: Proximal gastrectomy with double-tract reconstruction (DTR) has been used for upper third gastric cancer as a function-preserving procedure. However, the safety and feasibility of laparoscopic proximal gastrectomy (LPG) with DTR remain uncertain. This study compared open proximal gastrectomy (OPG) with DTR and LPG with DTR for proximal gastric cancer. METHODS: Sixty-four patients who had undergone OPG with DTR and forty-six patients who had undergone LPG with DTR were enrolled in this case-control study. The clinical characteristics, surgical outcomes and postoperative nutrition index were analysed retrospectively. RESULTS: The operation time was significantly longer in the LGP group than in the OPG group (258.3 min vs 205.8 min; p = 0.00). However, the time to first flatus and postoperative hospital stay were shorter in the LPG group [4.0 days vs 3.5 days (p = 0.00) and 10.6 days vs 9.2 days (p = 0.001), respectively]. No significant difference was found between the two groups in the number of retrieved lymph nodes, complications or reflux oesophagitis. The nutrition status was assessed using the haemoglobin, albumin, prealbumin and weight levels from pre-operation to six months after surgery. No significant difference was found between the groups. CONCLUSION: LPG with DTR can be safely performed for proximal gastric cancer patients by experienced surgeons.

Research on a Task Offloading Strategy for the Internet of Vehicles Based on Reinforcement Learning.

Today, vehicles are increasingly being connected to the Internet of Things, which enables them to obtain high-quality services. However, the numerous vehicular applications and time-varying network status make it challenging for onboard terminals to achieve efficient computing. Therefore, based on a three-stage model of local-edge clouds and reinforcement learning, we propose a task offloading algorithm for the Internet of Vehicles (IoV). First, we establish communication methods between vehicles and their cost functions. In addition, according to the real-time state of vehicles, we analyze their computing requirements and the price function. Finally, we propose an experience-driven offloading strategy based on multi-agent reinforcement learning. The simulation results show that the algorithm increases the probability of success for the task and achieves a balance between the task vehicle delay, expenditure, task vehicle utility and service vehicle utility under various constraints.

Health impacts of environmental contamination of micro- and nanoplastics: a review.

Plastics are extensively used in our daily life. However, a significant amount of plastic waste is discharged to the environment directly or via improper reuse or recycling. Degradation of plastic waste generates micro- or nano-sized plastic particles that are defined as micro- or nanoplastics (MNPs). Microplastics (MPs) are plastic particles with a diameter less than 5 mm, while nanoplastics (NPs) range in diameter from 1 to 100 or 1000 nm. In the current review, we first briefly summarized the environmental contamination of MNPs and then discussed their health impacts based on existing MNP research. Our review indicates that MNPs can be detected in both marine and terrestrial ecosystems worldwide and be ingested and accumulated by animals along the food chain. Evidence has suggested the harmful health impacts of MNPs on marine and freshwater animals. Recent studies found MPs in human stool samples, suggesting that humans are exposed to MPs through food and/or drinking water. However, the effect of MNPs on human health is scarcely researched. In addition to the MNPs themselves, these tiny plastic particles can release plastic additives and/or adsorb other environmental chemicals, many of which have been shown to exhibit endocrine disrupting and other toxic effects. In summary, we conclude that more studies are necessary to provide a comprehensive understanding of MNP pollution hazards and also provide a basis for the subsequent pollution management and control.

The Development of an International Oncofertility Competency Framework: A Model to Increase Oncofertility Implementation.

BACKGROUND: Despite international evidence about fertility preservation (FP), several barriers still prevent the implementation of equitable FP practice. Currently, oncofertility competencies do not exist. The aim of this study was to develop an oncofertility competency framework that defines the key components of oncofertility care, develops a model for prioritizing service development, and defines the roles that health care professionals (HCPs) play. MATERIALS AND METHOD: A quantitative modified Delphi methodology was used to conduct two rounds of an electronic survey, querying and synthesizing opinions about statements regarding oncofertility care with HCPs and patient and family advocacy groups (PFAs) from 16 countries (12 high and 4 middle income). Statements included the roles of HCPs and priorities for service development care across ten domains (communication, oncofertility decision aids, age-appropriate care, referral pathways, documentation, oncofertility training, reproductive survivorship care and fertility-related psychosocial support, supportive care, and ethical frameworks) that represent 33 different elements of care. RESULTS: The first questionnaire was completed by 457 participants (332 HCPs and 125 PFAs). One hundred and thirty-eight participants completed the second questionnaire (122 HCPs and 16 PFAs). Consensus was agreed on 108 oncofertility competencies and the roles HCPs should play in oncofertility care. A three-tier service development model is proposed, with gradual implementation of different components of care. A total of 92.8% of the 108 agreed competencies also had agreement between high and middle income participants. CONCLUSION: FP guidelines establish best practice but do not consider the skills and requirements to implement these guidelines. The competency framework gives HCPs and services a structure for the training of HCPs and implementation of care, as well as defining a model for prioritizing oncofertility service development. IMPLICATIONS FOR PRACTICE: Despite international evidence about fertility preservation (FP), several barriers still prevent the implementation of equitable FP practice. The competency framework gives 108 competencies that will allow health care professionals (HCPs) and services a structure for the development of oncofertility care, as well as define the role HCPs play to provide care and support. The framework also proposes a three-tier oncofertility service development model which prioritizes the development of components of oncofertility care into essential, enhanced, and expert services, giving clear recommendations for service development. The competency framework will enhance the implementation of FP guidelines, improving the equitable access to medical and psychological oncofertility care.

Chemotherapeutic agent doxorubicin alters uterine gene expression in response to estrogen in ovariectomized CD-1 adult mice†.

Chemotherapy can potentially impair fertility in premenopausal cancer patients. Female fertility preservation has been mainly focused on the ovarian aspects and benefited greatly from assisted reproductive technologies, such as in vitro fertilization (IVF). The rate-limiting step for the success of IVF is embryo implantation in the uterus. Doxorubicin (DOX) is a widely used chemotherapeutic agent with ovarian toxicity. It remains unknown if the uterus is a direct target of DOX. To circumvent the indirect uterine effect from ovarian toxicity of DOX and to investigate potential long-term impact of DOX on the uterus, young adult ovariectomized CD-1 mice were given an intraperitoneal injection once with PBS or DOX (10 mg/kg, a human relevant chemotherapeutic dose), and 30 days later, each set of mice was randomly assigned into three groups and subcutaneously injected with oil, 17ß-estradiol (E2, for 6 h), and progesterone (P4, for 54 h), respectively. Uterine transcriptomic profiles were determined using RNA-seq. Principal component analysis of the uterine transcriptomes revealed four clusters from the six treatment groups: PBS-oil & DOX-oil, PBS-P4 & DOX-P4, PBS-E2, and DOX-E2, indicating that DOX treatment did not affect the overall uterine transcriptomic profiles in the oil and P4-treated mice but altered uterine responses to E2 treatment. DAVID analysis indicated that the top-affected gene cluster was "Glycoprotein". These data demonstrate that DOX can directly target the uterus and has a long-term impact on uterine responses to E2.

Doxorubicin obliterates mouse ovarian reserve through both primordial follicle atresia and overactivation.

Ovarian toxicity and infertility are major side effects of cancer therapy in young female cancer patients. We and others have previously demonstrated that doxorubicin (DOX), one of the most widely used chemotherapeutic chemicals, has a dose-dependent toxicity on growing follicles. However, it is not fully understood if the primordial follicles are the direct or indirect target of DOX. Using both prepubertal and young adult female mouse models, we comprehensively investigated the effect of DOX on all developmental stages of follicles, determined the impact of DOX on primordial follicle survival, activation, and development, as well as compared the impact of age on DOX-induced ovarian toxicity. Twenty-one-day-old CD-1 female mice were intraperitoneally injected with PBS or clinically relevant dose of DOX at 10 mg/kg once. Results indicated that DOX primarily damaged granulosa cells in growing follicles and oocytes in primordial follicles and DOX-induced growing follicle apoptosis was associated with the primordial follicle overactivation. Using the 5-day-old female mice with a more uniform primordial follicle population, our data revealed that DOX also directly promoted primordial follicle death and the DNA damage-TAp63α-C-CASP3 pathway was involved in DOX-induced primordial follicle oocyte apoptosis. Compared to 21-day- and 8-week-old female mice that were treated with the same dose of DOX, the 5-day-old mice had the most severe primordial follicle loss as well as the least degree of primordial follicle overactivation. Taken together, these results demonstrate that DOX obliterates mouse ovarian reserve through both primordial follicle atresia and overactivation and the DOX-induced ovarian toxicity is age dependent.

Female oncofertility attitude and knowledge: a survey of reproductive health professionals in Shanghai, China.

AIM: To evaluate the female oncofertility attitude and knowledge of reproductive health professionals in China. METHODS: An online survey was distributed to reproductive health professionals in Shanghai, China. RESULTS: Female professionals were more likely to consider that cancer patients would want to preserve their fertility. Participants with higher educational background tended to have a more positive attitude toward oncofertility. The majority of the participants (71.0%) obtained a fair or low level of oncofertility knowledge, and only 25.3% of them received scores at the 'good knowledge' level. CONCLUSION: There are significant gaps in the current oncofertility knowledge among reproductive health professionals in China, suggesting an urgent, unmet need for establishing an interdisciplinary fertility preservation training and service system.

Retrievable hydrogels for ovarian follicle transplantation and oocyte collection.

Cancer survivorship rates have drastically increased due to improved efficacy of oncologic treatments. Consequently, clinical concerns have shifted from solely focusing on survival to quality of life, with fertility preservation as an important consideration. Among fertility preservation strategies for female patients, ovarian tissue cryopreservation and subsequent reimplantation has been the only clinical option available to cancer survivors with cryopreserved tissue. However, follicle atresia after transplantation and risk of reintroducing malignant cells have prevented this procedure from becoming widely adopted in clinics. Herein, we investigated the encapsulation of ovarian follicles in alginate hydrogels that isolate the graft from the host, yet allows for maturation after transplantation at a heterotopic (i.e., subcutaneous) site, a process we termed in vivo follicle maturation. Survival of multiple follicle populations was confirmed via histology, with the notable development of the antral follicles. Collected oocytes (63%) exhibited polar body extrusion and were fertilized by intracytoplasmic sperm injection and standard in vitro fertilization procedures. Successfully fertilized oocytes developed to the pronucleus (14%), two-cell (36%), and four-cell (7%) stages. Furthermore, ovarian follicles cotransplanted with metastatic breast cancer cells within the hydrogels allowed for retrieval of the follicles, and no mice developed tumors after removal of the implant, confirming that the hydrogel prevented seeding of disease within the host. Collectively, these findings demonstrate a viable option for safe use of potentially cancer-laden ovarian donor tissue for in vivo follicle maturation within a retrievable hydrogel and subsequent oocyte collection. Ultimately, this technology may provide novel options to preserve fertility for young female patients with cancer.

Acidification of uterine epithelium during embryo implantation in mice.

Uterine luminal epithelium (LE) is essential for establishing uterine receptivity. Previous microarray analysis revealed upregulation of Atp6v0d2 in gestation day 4.5 (D4.5) LE in mice. Realtime PCR showed upregulation of uterine Atp6v0d2 starting right before embryo attachment ∼D4.0. In situ hybridization demonstrated specific uterine localization of Atp6v0d2 in LE upon embryo implantation. Atp6v0d2 encodes one subunit for vacuolar-type H+-ATPase (V-ATPase), which regulates acidity of intracellular organelles and extracellular environment. LysoSensor Green DND-189 detected acidic signals in LE and glandular epithelium upon embryo implantation, correlating with Atp6v0d2 upregulation in early pregnant uterus. Atp6v0d2-/- females had significantly reduced implantation rate and marginally reduced delivery rate from first mating only, but comparable number of implantation sites and litter size compared to control and comparable fertility to control from subsequent matings, suggesting a nonessential role of Atp6v0d2 subunit in embryo implantation. Successful implantation in both control and Atp6v0d2-/- females was associated with uterine epithelial acidification. No significant compensatory upregulation of Atp6v0d1 mRNA was detected in D4.5 Atp6v0d2-/- uteri. To determine the role of V-ATPase instead of a single subunit in embryo implantation, a specific V-ATPase inhibitor bafilomycin A1 (2.5 µg/kg) was injected via uterine fat pad on D3 18:00 h. This treatment resulted in reduced uterine epithelial acidification, delayed implantation, and reduced number of implantation sites. It also suppressed oil-induced artificial decidualization. These data demonstrate uterine epithelial acidification as a novel phenomenon during embryo implantation and V-ATPase is involved in uterine epithelial acidification and uterine preparation for embryo implantation.

The role of group III, IV elements in Nb4AC3 MAX phases (A = Al, Si, Ga, Ge) and the unusual anisotropic behavior of the electronic and optical properties.

Niobium based Nb4AlC3, Nb4SiC3, Nb4GeC3 and Nb4GaC3 were investigated by means of density functional theory. Together with the known Nb4AlC3, the role of group III, IV elements in various properties of Nb4AC3 (A = Al, Si, Ga, Ge) was systematically investigated, and particularly the bulk moduli, shear moduli, and Young's moduli helped us to approach the ductility. All the studied compounds were found to be mechanically stable, and they also exhibit the metallic nature that results from the Nb-4d states being dominant at the Fermi level. The typical 4d-2p hybridization leads to strong Nb-C covalent bonding and a relatively weaker 4d-3p (4p) hybridization between Nb and A is identified. The latter does perturb the performance of materials. By varying A elements in Nb4AC3, the position and the width of the p states as well as hybridizations are altered, which determine the covalency and the ionicity of the chemical bonds. A high density of states at the Fermi level and the nesting effects in the Fermi surface are identified in Nb4SiC3 and linked to its unusual anisotropic behavior. Furthermore, Nb4GeC3 is predicted to be a very promising candidate solar heating barrier material. Overall, the present work gives insights into the role of A elements in the electronic structure and the physical properties of Nb4AC3 compounds. The tendencies and rules established here will help in the designing of functional ceramic materials with desirable properties.

Splenosis with lower gastrointestinal bleeding mimicking colonical gastrointestinal stromal tumour.

BACKGROUND: Splenosis refers to the heterotopic transplantation of splenic tissue following splenic trauma or splenectomy. Splenosis is typically asymptomatic and is often identified incidentally. CASE PRESENTATION: We report a case of splenosis with colon and stomach invasion presenting as lower gastrointestinal bleeding and mimicking colonic gastrointestinal stromal tumour (GIST). The importance of suspicion for splenosis in patients with a history of splenic injury should be highlighted. Computed tomography (CT)-guided biopsy, nuclear scintigraphy and ferumoxide-enhanced magnetic resonance imaging (MRI) can support an accurate diagnosis. CONCLUSIONS: An accurate diagnosis of splenosis is important to avoid unnecessary operations, especially in patients with previous histories of splenic trauma or splenectomy.