PTMdyna: exploring the influence of post-translation modifications on protein conformational dynamics.

Protein post-translational modifications (PTM) play vital roles in cellular regulation, modulating functions by driving changes in protein structure and dynamics. Exploring comprehensively the influence of PTM on conformational dynamics can facilitate the understanding of the related biological function and molecular mechanism. Currently, a series of excellent computation tools have been designed to analyze the time-dependent structural properties of proteins. However, the protocol aimed to explore conformational dynamics of post-translational modified protein is still a blank. To fill this gap, we present PTMdyna to visually predict the conformational dynamics differences between unmodified and modified proteins, thus indicating the influence of specific PTM. PTMdyna exhibits an AUC of 0.884 tested on 220 protein-protein complex structures. The case of heterochromatin protein 1α complexed with lysine 9-methylated histone H3, which is critical for genomic stability and cell differentiation, was used to demonstrate its applicability. PTMdyna provides a reliable platform to predict the influence of PTM on protein dynamics, making it easier to interpret PTM functionality at the structure level. The web server is freely available at http://ccbportal.com/PTMdyna.

Connecting chemical exposome to human health using high-resolution mass spectrometry-based biomonitoring: Recent advances and future perspectives.

Compared with the rapid advances in genomics leading to broad understanding of human disease, the linkage between chemical exposome and diseases is still under investigation. High-resolution mass spectrometry (HRMS) is expected to accelerate the process via relatively accurate and precise biomonitoring of human exposome. This review covers recent advancements in biomonitoring of exposed environmental chemicals (chemical exposome) using HRMS described in the 124 articles that resulted from a systematic literature search on Medline and Web of Science databases. The analytical strategic aspects, including the selection of specimens, sample preparation, instrumentation, untargeted versus targeted analysis, and workflows for MS-based biomonitoring to explore the environmental chemical space of human exposome, are deliberated. Applications of HRMS in human exposome investigation are presented by biomonitoring (1) exposed chemical compounds and their biotransformation products; (2) DNA/protein adducts; and (3) endogenous compound perturbations. Challenges and future perspectives are also discussed.

Gut microbiota alterations in colorectal adenoma-carcinoma sequence based on 16S rRNA gene sequencing: A systematic review and meta-analysis.

BACKGROUND: Most sporadic colorectal cancers (CRC) develop through the adenoma-carcinoma sequence. While dysbiosis of the intestinal flora contributes to CRC's pathogenesis, precise microbial taxa closely associated with the colorectal adenoma-carcinoma sequence remain elusive. This meta-analysis aimed to summarize the features of intestinal flora in patients with AD and CRC. METHODS: PubMed, Embase, Cochrane Library, and Web of Science were searched for case-control studies comparing the relative abundance of gut microbiota in the feces of patients with AD, CRC, and healthy controls (HC) from inception to January 2024. The weighted mean difference (WMD) with a 95 % confidence interval (CI) was used to display the results. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the entailed literature. Publication bias was evaluated with the Egger's and Begg's tests. RESULTS: Eleven studies were included, involving 477 CRC patients, 628 AD patients, and 864 healthy controls. Compared with HC, the patients with AD had a significantly lower Chao 1 index (WMD = -30.17, 95 % CI [-41.10, -19.23], P < 0.001) and Shannon index (WMD = -0.11 95 % CI [-0.18, -0.04], P = 0.002). Compared with AD, the CRC patients had a significantly higher Chao1 index (WMD = 22.09, 95 % CI [7.59, 36.00], P = 0.003) and Shannon index (WMD = 0.08, 95 % CI [0.00, 0.15], P = 0.037). Enterobacteriaceae (WMD = 0.03 95 % CI [0.00,0.05], P = 0.047; WMD = 0.02 95 % CI [0.00,0.04], P = 0.027) significantly increased in the order of Control-AD-CRC, while that of Blautia (WMD = -0.00 95 % CI [-0.01, -0.00], P = 0.001; WMD = -0.00 95 % CI [-0.00, -0.00], P = 0.002) was reduced. Compared with HC, the relative abundance of Proteobacteria (WMD = 0.05 95 % CI [0.03,0.07], P < 0.001), Fusobacteria (WMD = 0.02 95 % CI [0.00,0.03], P = 0.042), Streptococcaceae (WMD = 0.03 95 % CI [0.01,0.05], P = 0.017), Prevotellaceae (WMD = 0.02 95 % CI [0.00,0.04], P = 0.040), and Escherichia-Shigella (WMD = 0.06 95 % CI [0.01, 0.11], P = 0.021) was enriched in the CRC group. The relative abundance of Alistipes (WMD = 0.00 95 % CI [0.00,0.01], P = 0.032) and Streptococcus (WMD = 0.00 95 % CI [0.00,0.00], P = 0.001) was increased in the AD vs HC. The relative abundance of Firmicutes (WMD = -0.07 95 % CI [-0.12, -0.03], P = 0.003), Bifidobacteria (WMD = -0.03 95 % CI [-0.05, -0.01], P = 0.016), and Klebsiella (WMD = -0.01 95 % CI [-0.01, -0.00], P = 0.001) was decreased in the CRC vs HC. Compared with AD, the relative abundance of Firmicutes (WMD = -0.04 95 % CI [-0.07, -0.02], P = 0.002), Peptostreptococcaceae (WMD = -0.03 95 % CI [-0.05, -0.00], P = 0.021), Lachnospiraceae (WMD = -0.04 95 % CI [-0.08,-0.00], P = 0.037), Ruminococcaceae (WMD = -0.06 95 % CI [-0.09,-0.03], P < 0.001), Faecalibacterium (WMD = -0.01 95 % CI [-0.02, -0.01], P = 0.001), and Lachnoclostridium (WMD = -0.02 95 % CI [-0.03, -0.00], P = 0.040) was decreased in the CRC group, while Proteobacteria (WMD = 0.04 95 % CI [0.02,0.05], P < 0.001) was increased. CONCLUSIONS: The dysbiosis characterized by reduced levels of short-chain fatty acid (SCFA)-producing bacteria, decreased anti-inflammatory bacteria, increased pro-inflammatory bacteria, and an elevation of bacteria with cytotoxic effects damaging to DNA may represent the specific microbial signature of colorectal adenoma/carcinoma. Further research is required to elucidate the mechanisms by which gut dysbiosis leads to the progression from AD to CRC and to explore the potential of specific microbiota markers in clinical treatment and non-invasive screening.

Synthesis and structural optimization of oncolytic peptide LTX-315.

Oncolytic peptides represented potential novel candidates for anticancer treatments especially drug-resistant cancer cell lines. One of the most promising and extensively studied is LTX-315, which is considered as the first in class oncolytic peptide and has entered phase I/II clinical trials. Nevertheless, the shortcomings including poor proteolytic stability, moderate anticancer durability and high synthesis costs may hinder the widespread clinical applications of LTX-315. In order to reduce the synthesis costs, as well as develop derivatives possessing both high protease-stability and durable anticancer efficiency, twenty LTX-315-based derived-peptides were designed and efficiently synthesized. Especially, through solid-phase S-alkylation, as well as the optimized peptide cleavage condition, the derived peptides could be prepared with drastically reduced synthesis cost. The in vitro anticancer efficiency, serum stability, anticancer durability, anti-migration activity, and hemolysis effect were systematically investigated. It was found that derived peptide MS-13 exhibited comparable anticancer efficiency and durability to those of LTX-315. Strikingly, the D-type peptide MS-20, which is the enantiomer of MS-13, was demonstrated to possess significantly high proteolytic stability and sustained anticancer durability. In general, the cost-effective synthesis and stability-guided structural optimizations were conducted on LTX-315, affording the highly hydrolysis resistant MS-20 which possessed durable anticancer activity. Meanwhile, this study also provided a reliable reference for the future optimization of anticancer peptides through the solid-phase S-alkylation and L-type to D-type amino acid substitutions.

A case of right aortic arch type II combined with Kommerell's diverticulum and left innominate vein beneath the aortic arch.

The combination of the right aortic arch and aberrant left subclavian artery (ALSA) with Kommerell's diverticulum (KD) is rare to coexist with the left innominate vein (LINV) beneath the aortic arch. It escalates the surgical risk undoubtedly and increases the difficulty of clinical procedures. We report one case diagnosed by Ultrasound and Computed Tomography Angiography (CTA).

Primary cardiac angiosarcoma: Imaging characterization.

This case report describes a 35-year-old female patient who presented with palpitations and shortness of breath. Imaging findings suggested a cardiac tumor, histopathology confirmed primary cardiac angiosarcoma. This tumor is highly aggressive, usually occurs in the right atrium, lacks specificity in clinical presentation, is prone to early metastasis, and has a poor prognosis. Echocardiography is the method of choice for early detection and is important in assessing tumor size, location, mode of attachment and whether cardiac function is impaired.

KLK7, KLK10, and KLK11 in Papillary Thyroid Cancer: Bioinformatic Analysis and Experimental Validation.

Despite many studies on papillary thyroid carcinoma (PTC) in the past few decades, some critical and significant genes remain undiscovered. To explore genes that may play crucial roles in PTC, a detailed analysis of the expression levels, mutations, and clinical significance of Kallikrein-related peptidases (KLKs) family genes in PTC was undertaken to provide new targets for the precise treatment of the disease. A comprehensive analysis of KLK family genes was performed using various online tools, such as GEPIA, Kaplan-Meier Plotter, LinkedOmics, GSCA, TIMER, and Cluego. KLK7, KLK10, and KLK11 were critical factors of KLK family genes. Then, functional assays were carried out on KLK7/10/11 to determine their proliferation, migration, and invasion capabilities in PTC. The mRNA expression levels of KLK7, KLK10, KLK11, and KLK13 were significantly elevated in thyroid carcinoma, while KLK1, KLK2, KLK3 and KLK4 mRNA levels were decreased compared to normal tissues. Correlations between KLK2/7-12/15 expression levels and tumor stage were also observed in thyroid carcinoma. Survival analysis demonstrated that KLK4/5/7/9-12/14 was associated with overall survival in patients with thyroid cancer. Not only were KLK genes strongly associated with cancer-related pathways, but also KLK7/10/11 was associated with immune-cell infiltration. Finally, silencing KLK7/10/11 impaired human papillary thyroid carcinoma cells' growth, migration ability, and invasiveness. The increased expression of KLK7, KLK10, and KLK11 may serve as molecular markers to identify PTC patients. KLK7, KLK10, and KLK11 could be potential prognostic indicators and targets for precision therapy against PTC.

Imaging Manifestations of Cervical Internal Jugular Pseudoaneurysm: A Case Report.

Pseudoaneurysm is a relatively rare venous disease characterized by increased intravascular pressure leading to the rupture of the venous wall. Blood flows through the rupture into the surrounding loose connective tissue, where it is encapsulated by fibrous tissue, forming a localized hematoma with a communication channel to the venous vessel, thus forming a pseudoaneurysm. Currently, there are few reports on its imaging manifestations both domestically and internationally. This article reports a case of imaging manifestations of pseudoaneurysm of the right internal jugular vein and analyzes its characteristics.

Diagnosis of membranous supravalvular aortic stenosis with severe aortic valve insufficiency.

Although the clinical manifestations of membranous supravalvular aortic stenosis (SVAS) are distinctive, its diagnosis remains challenging. Failure to initiate surgical treatment in a timely manner greatly increases the risk of sudden cardiac death. We report a case of membranous SVAS, detailing the clinical presentation and imaging manifestations.

Classification accuracy of machine learning algorithms for Chinese local cattle breeds using genomic markers.

Accurate breed classification is required for the conservation and utilization of farm animal genetic resources. Traditional classification methods mainly rely on phenotypic characterization. However, it is difficult to distinguish between the highly similar breeds due to the challenges in qualifying the phenotypic character. Machine learning algorithms show unique advantages in breed classification using genomic information. To evaluate the classification methods for Chinese cattle breeds, this study utilized genomic SNP data from 213 individuals across seven Chinese local breeds and compared the classification accuracies of three feature selection methods (FST value sorting and screening, mRMR, and Relief-F) and three machine learning algorithms (Random Forest, Support Vector Machine, and Naive Bayes). Results showed that: 1) using the FST method to screen more than 1500 SNPs, or using the mRMR algorithm to screen more than 1000 SNPs, the SVM classification algorithm can achieve more than 99.47% classification accuracy; 2) the most effective algorithm was SVM, followed by NB, while the best SNP selection method was FST and mRMR, followed by Relief-F; 3) species misclassification often occurs between breeds with high similarity. This study demonstrates that machine learning classification models combined with genomic data are effective methods for the classification of local cattle breeds, providing a technical basis for the rapid and accurate classification of cattle breeds in China.

[Effect of Shoutai Pills on expression of key glycolytic proteins and apoptosis related factors at maternal fetal interface in mouse model of threatened abortion with syndrome of kidney deficiency].

This study aims to explore the mechanism of Shoutai Pills in treating threatened abortion. According to the random number table method, ICR female mice were randomized into a normal group, a model group, a dydrogesterone group, and a Shoutai Pills group, with 15 mice in each group. Mice were administrated with normal saline(normal and model groups) or the suspension of Shoutai Pills or dydrogesterone by gavage at 9:00 am every day. At 16:00 every day, mice in the normal group were administrated with an equal volume of distilled water, while those in the model, Shoutai Pills, and dydrogesterone groups were administrated with hydrocortisone solution by gavage for 4 consecutive days. ICR female and male mice were caged in a ratio of 2∶1 during the pre-estrous or estrous period. From the first day of pregnancy, drug administration was continued for 5 consecutive days. On day 6, mice were administrated with mifepristone by gavage to establish the model of kidney deficiency-induced abortion. On day 6 of pregnancy, 10 female ICR mice were randomly selected from each group, and the uterus was collected for observation of the pathological changes of trophoblasts at the maternal-fetal interface by hematoxylin-eosin(HE) staining. The protein levels of key enzymes of glycolysis, hexokinase 2(HK2), enolase 1(ENO1), pyruvate kinase M2(PKM2), and lactate dehydrogenase A(LDHA), were determined by Western blot and immunofluorescence. The expression of apoptosis-related proteins including B cell lymphoma-2(Bcl-2), Bcl-2-associated protein X(Bax), and cysteinyl aspartate-specific proteinase-3(caspase-3) was determined by Western blot and real-time PCR. Terminal-deoxynucleoitidyl transferase-mediated nick-end labeling was employed to examine apoptosis. The embryo loss rate of the remaining five female mice was calculated by trypan blue staining method on day 14 of pregnancy. On day 14 of pregnancy, the embryo loss rate of the normal group was 5.00%, which was lower than that(27.78%) in the model group(P<0.05). Dydrogesterone and Shoutai Pills groups showed reduced embryo loss rates(10.26% and 7.50%, respectively) compared with the model group. On day 6 of pregnancy, compared with the normal group, the model group showed down-regulated expression of HK2, ENO1, PKM2, LDHA, and Bcl-2 and up-regulated expression of Bax and caspase-3(P<0.05). Compared with the model group, dydrogesterone and Shoutai Pills up-regulated the expression of HK2, ENO1, PKM2, LDHA, and Bcl-2 and down-regulated the expression of Bax and caspase-3(P<0.05). Compared with that in the normal group, the apoptosis rate in the model group increased(P<0.05). Compared with the model group, dydrogesterone and Shoutai Pills reduced the apoptosis rate(P<0.05). In conclusion, Shoutai Pills can reduce the embryo loss rate and protect embryos by promoting aerobic glycolysis at the maternal-fetal interface and inhibiting the apoptosis of trophoblasts in mice.

Chromosome-scale genome assembly and insights into the metabolome and gene regulation of leaf color transition in an important oak species, Quercus dentata.

Quercus dentata Thunb., a dominant forest tree species in northern China, has significant ecological and ornamental value due to its adaptability and beautiful autumn coloration, with color changes from green to yellow into red resulting from the autumnal shifts in leaf pigmentation. However, the key genes and molecular regulatory mechanisms for leaf color transition remain to be investigated. First, we presented a high-quality chromosome-scale assembly for Q. dentata. This 893.54 Mb sized genome (contig N50 = 4.21 Mb, scaffold N50 = 75.55 Mb; 2n = 24) harbors 31 584 protein-coding genes. Second, our metabolome analyses uncovered pelargonidin-3-O-glucoside, cyanidin-3-O-arabinoside, and cyanidin-3-O-glucoside as the main pigments involved in leaf color transition. Third, gene co-expression further identified the MYB-bHLH-WD40 (MBW) transcription activation complex as central to anthocyanin biosynthesis regulation. Notably, transcription factor (TF) QdNAC (QD08G038820) was highly co-expressed with this MBW complex and may regulate anthocyanin accumulation and chlorophyll degradation during leaf senescence through direct interaction with another TF, QdMYB (QD01G020890), as revealed by our further protein-protein and DNA-protein interaction assays. Our high-quality genome assembly, metabolome, and transcriptome resources further enrich Quercus genomics and will facilitate upcoming exploration of ornamental values and environmental adaptability in this important genus.

Synthesis of a water-soluble naphthalene-based macrocycle and its host-guest properties.

Reported here is the synthesis of a naphthalene-based macrocycle bearing anionic carboxylato groups on the rims along with its complexation with cationic guests in aqueous media. The macrocycle could strongly bind guests in a molecular clip model with association constants of 106-107 M-1.

Prediction of the transcription factor binding sites with meta-learning.

With the accumulation of ChIP-seq data, convolution neural network (CNN)-based methods have been proposed for predicting transcription factor binding sites (TFBSs). However, biological experimental data are noisy, and are often treated as ground truth for both training and testing. Particularly, existing classification methods ignore the false positive and false negative which are caused by the error in the peak calling stage, and therefore, they can easily overfit to biased training data. It leads to inaccurate identification and inability to reveal the rules of governing protein-DNA binding. To address this issue, we proposed a meta learning-based CNN method (namely TFBS_MLCNN or MLCNN for short) for suppressing the influence of noisy labels data and accurately recognizing TFBSs from ChIP-seq data. Guided by a small amount of unbiased meta-data, MLCNN can adaptively learn an explicit weighting function from ChIP-seq data and update the parameter of classifier simultaneously. The weighting function overcomes the influence of biased training data on classifier by assigning a weight to each sample according to its training loss. The experimental results on 424 ChIP-seq datasets show that MLCNN not only outperforms other existing state-of-the-art CNN methods, but can also detect noisy samples which are given the small weights to suppress them. The suppression ability to the noisy samples can be revealed through the visualization of samples' weights. Several case studies demonstrate that MLCNN has superior performance to others.

Design, synthesis and anticancer evaluation of novel oncolytic peptide-chlorambucil conjugates.

Nitrogen mustards (NMs) are an important class of chemotherapeutic drugs and have been widely employed for the treatment of various cancers. However, due to the high reactivity of nitrogen mustard, most NMs react with proteins and phospholipids within the cell membrane. Therefore, only a very small fraction of NMs can reach the reach nucleus, alkylating and cross-linking DNA. To efficiently penetrate the cell membrane barrier, the hybridization of NMs with a membranolytic agent may be an effective strategy. Herein, the chlorambucil (CLB, a kind of NM) hybrids were first designed by conjugation with membranolytic peptide LTX-315. However, although LTX-315 could help large amounts of CLB penetrate the cytomembrane and enter the cytoplasm, CLB still did not readily reach the nucleus. Our previous work demonstrated that the hybrid peptide NTP-385 obtained by covalent conjugation of rhodamine B with LTX-315 could accumulate in the nucleus. Hence, the NTP-385-CLB conjugate, named FXY-3, was then designed and systematically evaluated both in vitro and in vivo. FXY-3 displayed prominent localization in the cancer cell nucleus and induced severe DNA double-strand breaks (DSBs) to trigger cell apoptosis. Especially, compared with CLB and LTX-315, FXY-3 exhibited significantly increased in vitro cytotoxicity against a panel of cancer cell lines. Moreover, FXY-3 showed superior in vivo anticancer efficiency in the mouse cancer model. Collectively, this study established an effective strategy to increase the anticancer activity and the nuclear accumulation of NMs, which will provide a valuable reference for future nucleus-targeting modification of nitrogen mustards.

The relationship between childhood trauma and insomnia among college students with major depressive disorder: Mediation by the role of negative life events and dysfunctional attitudes.

BACKGROUND: Insomnia is a common problem among patients with major depressive disorder (MDD). According to previous studies, the development and severity of Insomnia are influenced by childhood trauma experience. Furthermore, negative life events and dysfunctional attitudes may also mediate the impact. So, this study aimed to examine the association between childhood trauma, negative life events, dysfunctional attitudes and insomnia and investigate how negative life events and dysfunctional attitudes mediate the relationship between childhood trauma and insomnia in MDD. METHOD: This cross-sectional study recruited 621 college students with MDD. The Childhood Trauma Questionnaire (CTQ), Life Event Scale (LES), Dysfunctional Attitude Scale (DAS), Insomnia Severity Index (ISI), and Hamilton Depression Scale-17 (HAMD-17) were used to assess participants' psychosocial factors. Descriptive analysis, Chi-square test, t-test, Pearson correlations, and serial mediation analyses were used in data analysis. In order to eliminate the influence of the severity of depression symptoms, severity of depression symptoms was used as a control variable in this study. RESULTS: There were 166 (26.7%) participants having clinical insomnia (ISI score > 14). After controlling for the effect of severity of depression symptoms, results of serial mediation analyses determined that childhood trauma has a direct (Estimate = 0.109, 95%CI: 0.023,0.190) and indirect (Estimate = 0.090, 95%CI: 0.054,0.137) impact to insomnia. The indirect impact of childhood trauma on insomnia through the pathways of negative life events alone (Estimate = 0.050, 95%CI: 0.024,0.093), dysfunctional attitudes alone (Estimate = 0.027, 95%CI: 0.008,0.050), and negative life events to dysfunctional attitudes (Estimate = 0.013, 95%CI: 0.006,0.024) were significant. CONCLUSIONS: This study demonstrates that screening for childhood trauma should be considered when treating insomnia in college students with MDD. Managing negative life events and dysfunctional attitudes may mitigate the negative impact of childhood trauma on insomnia in college students with MDD.

Urinary heavy metals and attention-deficit/hyperactivity symptoms of preschool children: a mixed-exposure analysis.

The neurotoxic effects of certain heavy metals are well established, but only a few studies have investigated the joint effect of concurrent exposure to multiple ones. The study aims to evaluate the association between mixed exposure to neurotoxic metals and the psychosocial behavior of preschool children. Using a stratified sampling strategy, we recruited participants from 105 kindergartens in 41 townships of Taiwan and excluded those with blood lead levels ≥ 3.5 µg/L. The first-morning void urines were collected and analyzed for cadmium, manganese, arsenic, chromium, lead, and nickel concentrations using inductively coupled plasma mass spectrometry. We applied the parentally reported Strengths and Difficulties Questionnaire (SDQ) and Swanson, Nolan, and Pelham IV (SNAP-IV) scales to evaluate the psychosocial behaviors. Multiple linear regressions were utilized to evaluate the associations between each heavy metal and the outcomes, while the mixed effect of concurrent exposure was estimated by using a Quantile g-computation approach. A total of 977 preschool children were included in the study, and the mean (SD) age was 5.7 (0.7) years old. In single pollutant models, we observed adverse effects of urinary manganese, nickel, arsenic, and lead on the specific subsets of SDQ. Furthermore, the combined effect of six heavy metals significantly affected the hyperactivity/inattention symptoms (beta = 0.46, 95% CI: 0.13-0.78, with all metals increased by one quartile), and chromium and lead were the two major contributors. Similar detrimental effects of urinary cadmium and lead were also observed in the SNAP-IV subsets, although the joint effect analysis was not significant. The study provided evidence that concurrent exposure to multiple heavy metals may exert increased risks of hyperactivity/inattention in children compared to single pollutant exposure. Further studies are needed to verify our findings regarding mixed exposure to multiple neurotoxic metals.

The confusing pelvic cystic mass: A case of giant prostatic utricle cyst diagnosed by ultrasound.

The giant prostatic utricle cyst, located behindthe bladder with removable irregular mixed echo, communicating with the urethraat the level of the seminal colliculus, was diagnosed by ultrasound andverified by pathology and surgery.

Prenatal ultrasound diagnosis of fetal isolated left innominate vein under the aortic arch: A case report.

Abnormalities of the left innominate vein beneath the aortic arch are exceedingly rare. While they may not exhibit overt clinical symptoms, misdiagnosis, or failure to diagnose can significantly complicate and increase the risk associated with cardiac interventional procedures.

Multimodal imaging of morning glory syndrome with persistent hyperplastic primary vitreous.

Morning glory syndrome (MGS) and persistent hyperplastic primary vitreous (PHPV) are congenital abnormity, which may be related to the increased incidence of systemic abnormalities and retinal detachment，diagnosed by ultrasound, identified by CT, MRI, and with the confirmation of fundus examination.