Modified Unit-Mediated Strand Displacement Reactions for Direct Detection of Single Nucleotide Variants in Active Double-Stranded DNA.

Accurate identification of single nucleotide variants (SNVs) in key driver genes holds a significant value for disease diagnosis and treatment. Fluorescent probes exhibit tremendous potential in specific, high-resolution, and rapid detection of SNVs. However, additional steps are required in most post-PCR assays to convert double-stranded DNA (dsDNA) products into single-stranded DNA (ssDNA), enabling them to possess hybridization activity to trigger subsequent reactions. This process not only prolongs the complexity of the experiment but also introduces the risk of losing target information. In this study, we proposed two strategies for enriching active double-stranded DNA, involving PCR based on obstructive groups and cleavable units. Building upon this, we explored the impact of modified units on the strand displacement reaction (SDR) and assessed their discriminatory efficacy for mutations. The results showed that detection of low variant allele frequencies (VAF) as low as 0.1% can be achieved. The proposed strategy allowed orthogonal identification of 45 clinical colorectal cancer tissue samples with 100% specificity, and the results were generally consistent with sequencing results. Compared to existing methods for enriching active targets, our approach offers a more diverse set of enrichment strategies, characterized by the advantage of being simple and fast and preserving original information to the maximum extent. The objective of this study is to offer an effective solution for the swift and facile acquisition of active double-stranded DNA. We anticipate that our work will facilitate the practical applications of SDR based on dsDNA.

Unusual coexistence: branchial cleft cyst harboring papillary thyroid carcinoma with lymph node metastasis - a rare case report and clinical insights.

Background: The simultaneous occurrence of Branchial Cleft Cyst (BCC) and Papillary Thyroid Carcinoma (PTC) represents an unusual malignant tumor, with cases featuring associated lymph node metastasis being particularly rare. This combination underscores an increased potential for metastasis, and the assessment of neck masses, particularly on the lateral aspect, may inadvertently overlook the scrutiny of the thyroid. Therefore, healthcare providers should exercise vigilance, especially in patients over the age of 40, regarding the potential for neck masses to signify metastasis from thyroid malignancies. Currently, surgical intervention stands as the primary effective curative method, while the postoperative administration of radioactive iodine therapy remains a topic of ongoing debate. Case report: In the presented case, a 48-year-old male patient with a right neck mass underwent surgical intervention. The procedure included the excision of the right neck mass, unilateral thyroidectomy with isthmus resection, and functional neck lymph node dissection under tracheal intubation and general anesthesia. Postoperative pathology findings revealed the coexistence of a BCC with metastatic PTC in the right neck mass, as well as papillary carcinoma in the right thyroid lobe. Lymph node metastasis was observed in the central and levels III of the right neck. Conclusion: The rare amalgamation of a BCC with PTC and concurrent lymph node metastasis underscores the invasive nature of this malignancy. Healthcare professionals should be well-acquainted with its clinical presentation, pathological characteristics, and diagnostic criteria. A multidisciplinary approach is strongly recommended to enhance patient outcomes.

The feasibility and clinical significance of lateral approach thyroidectomy.

BACKGROUND: By comparing the three lateral approaches to thyroidectomy, the feasibility and clinical effects were analyzed, and the advantages of the lateral approach were summarized. METHODS: From January 2022 to January 2023, 52 patients with thyroid cancer admitted to our department were selected and subjected to Lateral approach for thyroidectomy. Among them, 31 patients underwent thyroidectomy via the supraclavicular approach, 13 patients underwent endoscopic thyroidectomy via the subclavicular approach, and 8 patients underwent endoscopic thyroidectomy via the axillary approach. The basic conditions, surgical conditions, complications, postoperative pain scores and postoperative satisfaction of patients in the three approach surgery groups were recorded and analyzed. RESULTS: There were no significant differences among the three approach groups in terms of patient characteristics, number of central lymph node dissections, intraoperative blood loss, postoperative drainage volume, duration of drainage tube placement, length of hospital stay, postoperative pain, satisfaction, and complications. However, the operation time was longest in the subclavicular approach group, followed by the axillary approach group, and shortest in the supraclavicular approach group. The total hospitalization cost was highest in the axillary approach group, followed by the subclavicular approach group, and lowest in the supraclavicular approach group. CONCLUSION: The lateral approach for thyroidectomy is deemed a safe and effective method. The three different approach paths gradually increase in length, allowing for the accumulation of anatomical experience. This approach has a shorter learning curve for clinical doctors and is a favorable choice for patients seeking aesthetic benefits.

Angiosarcoma of the breast: A review.

Breast angiosarcoma is a rare and highly aggressive malignancy with a poor prognosis. It can occur spontaneously or be associated with factors such as radiation therapy or chronic lymphedema. The etiology and pathogenesis of this disease are still unclear, the clinical symptoms and imaging findings lack specificity, and the pathological morphology is diverse, which is easy to be confused with other diseases. There is no clear guideline for surgical treatment. Although the optimal surgical approach remains unclear, the ultimate goal is surgical excision with optimal margins, which remains the primary method of treatment. In clinical practice, the choice of the surgical approach should be made by considering the tumor size, pathological type, and patient preferences. In clinical practice, the selection of surgical methods should be carried out with comprehensive consideration of tumor size, pathological types and patients' wishes. There is no clear consensus on whether radiotherapy and chemotherapy should be carried out after surgery, and its optimal program and efficacy are uncertain. This article reviews the etiology, clinical manifestations, pathological features, imaging findings, treatment, prognosis and other aspects of breast angiosarcoma, so as to strengthen clinicians' overall understanding of this disease and avoid missed diagnosis and misdiagnosis.

Development of Antibacterial Peptides with Membrane Disruption and Folate Pathway Inhibitory Activities against Methicillin-Resistant Staphylococcus aureus.

Antimicrobial peptides (AMPs) offer an opportunity to overcome multidrug resistance. Here, novel peptides were designed based on AMP fragments derived from sea cucumber hemolytic lectin to enhance anti-methicillin-resistant Staphylococcus aureus (MRSA) activity with less side effects. Two designed peptides, CGS19 (LARVARRVIRFIRRAW-NH2) and CGS20 (RRRLARRLIFFIRRAW-NH2), exhibited strong antibacterial activities against clinically isolated MRSA with MICs of 3-6 µM, but no obvious cytotoxicity was observed. Consistently, CGS19 and CGS20 exerted rapid bactericidal activity and effectively induced 5.9 and 5.8 log reduction of MRSA counts in mouse subeschar, respectively. Further, CGS19 and CGS20 kill bacteria not only through disturbing membrane integrity but also by binding formate-tetrahydrofolate ligase, a key enzyme in the folate metabolism pathway, thereby inhibiting the folate pathway of MRSA. CGS19 and CGS20 are promising lead candidates for drug development against MRSA infection. The dual mechanisms on the identical peptide sequence or scaffold might be an underappreciated manner of treating life-threatening pathogens.

Coupling electrokinetic remediation with flushing using green tea synthesized nano zero-valent iron/nickel to remediate Cr (VI).

This study focuses on a flushing-electrokinetic remediation technology of hexavalent chromium from the chromium slag dump site. A suspension of nanoscale zero-valent iron/nickel fabricated from green tea (GT-nZVI/Ni), was employed as an eluent to degrade Cr (VI) and enhance the remediation effectiveness of a single EK. The removal efficiency of Cr (VI) was compared under different voltages, electrode spacings and pH values of the anolyte. The results demonstrated that the combined flushing and EK achieved a removal rate of Cr (VI) in the soil throughout all the experiments ranging from 83.08 to 96.97% after 120 h. The optimal result was obtained when the voltage was 28 V, the pH value of anolyte was 3 and the electrode spacing was 15 cm. The removal of Cr (VI) reached 91.49% and the energy consumption was 0.32606 kW·h·g-1. The underlying mechanisms responsible for the removal of Cr (VI) by GT-nZVI/Ni flushing-EK primarily involved electromigration, reduction and adsorption co-precipitation processes. The fractionation analysis of Cr (VI) concentration in the soil after remediation showed that the presence of GT-nZVI/Ni facilitated the conversion of Cr (VI) into oxidizable and residual states with low mobility and toxicity. The results of toxicity characteristic leaching procedure (TCLP) indicated that the leaching concentration of Cr (VI) was below 1 mg·L-1, complying with the standards set by the Environmental Protection Agency. Additionally, the phytotoxicity testing revealed that the germination index (GI) of the remediated soil reached 54.75%, indicating no potential harm to plants.

Progressive pseudorheumatoid dysplasia involving a novel WISP3 mutation and sacroiliac and hip arthritis: A case report and literature review.

INTRODUCTION: Progressive pseudorheumatoid dysplasia (PPRD) is a rare autosomal recessive genetic disease caused by mutations in the Wnt1-inducible signaling pathway protein 3 gene. PPRD is considered a noninflammatory disease, and involvement of the sacroiliac joint and hip arthritis have not been reported previously. PATIENT CONCERNS: We report a case of PPRD in an 11-year-old boy, who presented with bilateral pain and swelling in the knees, elbows, and ankles, and bilateral pain without swelling in the shoulders, wrists, knuckles, and proximal and distal interphalangeal joints for the past 5 years. He had been misdiagnosed with juvenile idiopathic arthritis for more than 6 years. DIAGNOSIS: The correct PPRD diagnosis was made using whole-exome sequencing for Wnt1-inducible signaling pathway protein 3 gene mutations (c.589 + 2T>C and c.721T>G; both mutations have rarely been reported) and magnetic resonance imaging examination; moreover, the latter showed inflammation of the sacroiliac joint and hip joint. INTERVENTION: The patient was administered supplemental calcium, active vitamin D, and glucosamine sulfate. OUTCOME: The patient experienced alleviation of joint pain following treatment initiation; however, joint motion improvement was not obvious. Above all, the long-term use of biologic or targeted synthetic disease-modifying antirheumatic drugs in the future was avoided. CONCLUSION: The findings of the inflammatory aspects in PPRD will enrich our understanding of this rheumatological disease.

Synthetic nanoparticles for the delivery of CRISPR/Cas9 gene editing system: classification and biomedical applications.

Gene editing has great potential in biomedical research including disease diagnosis and treatment. Clustered regularly interspaced short palindromic repeats (CRISPR) is the most straightforward and cost-effective method. The efficient and precise delivery of CRISPR can impact the specificity and efficacy of gene editing. In recent years, synthetic nanoparticles have been discovered as effective CRISPR/Cas9 delivery vehicles. We categorized synthetic nanoparticles for CRISPR/Cas9 delivery and discribed their advantages and disadvantages. Further, the building blocks of different kinds of nanoparticles and their applications in cells/tissues, cancer and other diseases were described in detail. Finally, the challenges encountered in the clinical application of CRISPR/Cas9 delivery materials were discussed, and potential solutions were provided regarding efficiency and biosafety issues.

Noninvasive carbon dioxide monitoring in pediatric patients undergoing laparoscopic surgery: transcutaneous vs. end-tidal techniques.

PURPOSE: The present study aimed to investigate the correlation between transcutaneous carbon dioxide partial pressure (PtcCO2) and arterial carbon dioxide pressure (PaCO2) and the accuracy of PtcCO2 in predicting PaCO2 during laparoscopic surgery in pediatric patients. METHODS: Children aged 2-8 years with American Society of Anesthesiologists (ASA) class I or II who underwent laparoscopic surgery under general anesthesia were selected. After anesthesia induction and tracheal intubation, PtcCO2 was monitored, and radial arterial catheterization was performed for continuous pressure measurement. PaCO2, PtcCO2, and end-tidal carbon dioxide partial pressure (PetCO2) were measured before pneumoperitoneum, and 30, 60, and 90 min after pneumoperitoneum, respectively. The correlation and agreement between PtcCO2 and PaCO2, PetCO2, and PaCO2 were evaluated. RESULTS: A total of 32 patients were eventually enrolled in this study, resulting in 128 datasets. The linear regression equations were: PtcCO2 = 7.89 + 0.82 × PaCO2 (r2 = 0.70, P < 0.01); PetCO2 = 9.87 + 0.64 × PaCO2 (r2 = 0.69, P < 0.01). The 95% limits of agreement (LOA) of PtcCO2 - PaCO2 average was 0.66 ± 4.92 mmHg, and the 95% LOA of PetCO2 - PaCO2 average was -4.4 ± 4.86 mmHg. A difference of ≤ 5 mmHg was noted between PtcCO2 and PaCO2 in 122/128 samples and between PetCO2 and PaCO2 in 81/128 samples (P < 0.01). CONCLUSION: In pediatric laparoscopic surgery, a close correlation was established between PtcCO2 and PaCO2. Compared to PetCO2, PtcCO2 can estimate PaCO2 accurately and could be used as an auxiliary monitoring indicator to optimize anesthesia management for laparoscopic surgery in children; however, it is not a substitute for PetCO2. REGISTRATION NUMBER OF CHINESE CLINICAL TRIAL REGISTRY: ChiCTR2100043636.

Network Pharmacology and Molecular Docking to Explore the Mechanism of Kangxian Decoction for Epilepsy.

Purpose: Kangxian decoction (KXD) has been used in clinical practice to treat epilepsy. The purpose of this study was to explore the active components of KXD and clarify its antiepileptic mechanism through network pharmacology and molecular docking. Methods: The components of KXD were collected from the Encyclopedia of Traditional Chinese Medicine (ETCM) database and the literature was searched. Then, active ingredients were screened by SwissADME and potential targets were predicted by the SwissTargetPrediction database. Epilepsy-related differentially expressed genes were downloaded from the Gene Expression Omnibus database. A component-target-pathway network was constructed with Cytoscape. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and protein‒protein interaction network analysis revealed the potential mechanism and critical targets. Receiver operating characteristic (ROC) curves and box plots in microarray data validated the good diagnostic value and significant differential expression of these critical genes. Molecular docking verified the association between active ingredients and essential target proteins. Results: In our study, we screened the important compounds of KXD for epilepsy, including quercetin, baicalin, kaempferol, yohimbine, geissoschizine methyl ether, baicalein, etc. KXD may exert its therapeutic effect on epilepsy through the following targets: PTGS2, MMP9, CXCL8, ERBB2, and ARG1, acting on the following pathways: neuroactive ligand-receptor interactions, arachidonic acid metabolism, IL-17, TNF, NF-kappa B, and MAPK signaling pathways. The molecular docking results showed that the active ingredients in KXD exhibited good binding ability to the key targets. Conclusion: In this study, we explored the possibility that KXD for epilepsy may act on multiple targets through multiple active ingredients, involving neurotransmitters and neuroinflammatory pathways, providing a theoretical basis for subsequent clinical and experimental studies that will help develop effective new drugs to treat epilepsy.

[The comorbid mechanism of vestibular migraine and persistent postural-perceptual dizziness].

Vestibular migraine and persistent postural-perceptual dizziness both involve the vestibular system and are similar in clinical manifestations. After acute attack of vestibular migraine, it can gradually evolve into persistent posture-perceptual dizziness; persistent posture-perceptual dizziness caused by various factors can be combined with symptoms similar to vestibular migraine. Studies have shown that abnormal multi-sensory signal integration, abnormal neurotransmitters and genetic factors may be the co-disease mechanism of the two.

Integrated genomic analyses identify high-risk factors and actionable targets in T-cell acute lymphoblastic leukemia.

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy often associated with poor outcomes. To identify high-risk factors and potential actionable targets for T-ALL, we perform integrated genomic and transcriptomic analyses on samples from 165 Chinese pediatric and adult T-ALL patients, of whom 85% have outcome information. The genomic mutation landscape of this Chinese cohort is very similar to the Western cohort published previously, except that the rate of NOTCH1 mutations is significant lower in the Chinese T-ALL patients. Among 47 recurrently mutated genes in 7 functional categories, we identify RAS pathway and PTEN mutations as poor survival factors for non-TAL and TAL subtypes, respectively. Mutations in the PI3K pathway are mutually exclusive with mutations in the RAS and NOTCH1 pathways as well as transcription factors. Further analysis demonstrates that approximately 43% of the high-risk patients harbor at least one potential actionable alteration identified in this study, and T-ALLs with RAS pathway mutations are hypersensitive to MEKi in vitro and in vivo. Thus, our integrated genomic analyses not only systematically identify high-risk factors but suggest that these high-risk factors are promising targets for T-ALL therapies.

Engineering pro-angiogenic biomaterials via chemoselective extracellular vesicle immobilization.

Nanoscale extracellular vesicles (EVs) represent a unique cellular derivative that reflect the therapeutic potential of mesenchymal stem cells (MSCs) toward tissue engineering and injury repair without the logistical and safety concerns of utilizing living cells. However, upon systemic administration in vivo,EVs undergo rapid clearance and typically lack controlled targeted delivery, thus reducing their effectiveness in therapeutic regenerative therapies. Here, we describe a strategy that enables long-term in vivo spatial EV retention by chemoselective immobilization of metabolically incoporated azido ligand-bearing EVs (azido-EVs) within a dibenzocyclooctyne-modified collagen hydrogel. MSC-derived azido-EVs exhibit comparable morphological and functional properties as their non-labeled EV counterparts and, when immobilized within collagen hydrogel implants via click chemistry, they elicited more robust host cell infiltration, angiogenic and immunoregulatory responses including vascular ingrowth and macrophage recruitment compared to ten times the higher dose required by non-immobilized EVs. We envision this technology will enable a wide range of applications to spatially promote vascularization and host integration relevant to tissue engineering and regenerative medicine applications.

Case report: Kimura's disease with minimal degenerative glomerulopathy without eosinophil infiltration responds to mycophenolate mofetil treatment.

Kimura's disease (KD) is a rare chronic progressive immune inflammatory disease. The etiology is unknown and manifests as a chronic inflammatory process, which is more common in young Asian men. The clinical manifestations are painless subcutaneous swelling of the head and neck and periauricular lymphadenopathy, which is slow growing and has a benign course. KD may involve the kidney, and pathological examination revealed eosinophil infiltration in the renal tissue. Proteinuria has been reported in 12-16% of KD cases, and about 60-70% of KD patients will develop nephrotic proteinuria. KD is easily confused with nephrotic syndrome, because KD does not have specific clinical manifestations, laboratory and imaging, and early misdiagnosis is easy. We report a case of KD that was biopsy-proven to have minimal lesion glomerulopathy after ~11 years. In this report, we describe a clinical case of KD with nephrotic syndrome, but there's no eosinophil infiltration in the kidneys. The clinical manifestations of KD recurrence were bilateral eyelid edema, bilateral lower limb swelling, and massive proteinuria in response to mycophenolate mofetil treatment (1.5 g).

The Clinical and MRI Effect of TNF-α Inhibitors in Spondyloarthritis Patients With Hip Involvement: A Real-World Observational Clinical Study.

Objectives: Hip involvement is an important cause of disability and poor prognosis in patients with spondyloarthritis (SpA). Tumor necrosis factor (TNF)-α inhibitor treatment has been demonstrated to be effective in SpA patients with hip arthritis; however, quantitative assessment using MRI in long-term follow-up needs further application and observation. Methods: A total of 239 patients were involved in this study. Methotrexate and sulfasalazine were given as basic treatment. In total, 165 patients received TNF-α inhibitors plus basic treatment, and 74 received basic treatment only, as controls. Clinical symptoms were assessed at baseline and at weeks 12, 24, and 52. MRI performances of hip arthritis, including bone marrow edema (BME) and synovitis, were quantitatively assessed using the Hip Inflammation MRI Scoring System (HIMRISS). Results: The clinical values of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Harris hip score, and Ankylosing Spondylitis Disease Activity Score (ASDAS)-ESR in both groups showed significant clinical remission at week 52 (p < 0.001). However, the change in disease activity levels at week 52 in the control group was significantly worse than in the TNF-α inhibitor group. At week 52, MRI showed a significant remission trend in the TNF-α inhibitor group versus baseline, and total HIMRISS scores were significantly decreased (26.49 ± 10.37 vs. 20.59 ± 9.41, p < 0.001); the control group only had slight improvement (p < 0.05). Conclusions: TNF-α inhibitors could significantly improve clinical and MRI manifestations of hip involvement in patients with SpA. Quantitative MRI assessment combined with clinical assessment can be used to accurately evaluate the treatment effect of TNF-α in SpA patients with hip involvement to help guide targeted treatment.

Bony Orbital Surgery for Graves' Ophthalmopathy.

The majority of Graves' ophthalmopathy, or thyroid eye disease, can be managed medically; however, in refractory or severe cases, surgical intervention with orbital decompression may be necessary. The majority of the published literature is retrospective in nature, and there is no standardized approach to orbital decompression. The purpose of this review is to evaluate the various surgical approaches and techniques for orbital decompression. Outcomes are ultimately dependent on individual patient factors, surgical approach, and surgeon experience.

Cranioplasty.

Calvarial defects are commonly encountered after neurosurgical procedures, trauma, and ablative procedures of advanced head neck cancers. The goals of cranioplasty are to provide a protective barrier for the intracranial contents, to restore form, and prevent syndrome of the trephined. Autologous and alloplastic techniques are available, each with their advantages and drawbacks. A multitude of materials are available for cranioplasty, and proper timing of reconstruction with attention to the overlying skin envelope is important in minimizing complications.

[Potential targets of Euodiae Fructus in treatment of insomnia based on network pharmacology].

The acupoint application of Euodiae Fructus at Yongquan(KI1) can significantly improve the sleep quality of patients with insomnia with berberine as the main effective component for the efficacy. Nineteen active compounds and 203 drug targets were screened out from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP). After comparison with GeneCards and Online Mendelian Inheritance in Man(OMIM), 24 common genes of diseases and drugs were obtained. STRING 11.0 was used to construct a protein-protein interaction(PPI) network of the overlapping genes, and Matthews correlation coefficient(MCC) was employed to screen the core genes, which were then subjected to enrichment analysis with gene ontology(GO) and Kyoto encyclopedia of genes and genomes(KEGG). The results revealed that the main compounds of Euodiae Fructus, such as berberine and rutaecarpine, participated in the biological processes(such as neurotransmitter receptor activity) by regulating C-reactive protein(CRP), estrogen receptor 1(ESR1), 5-hydroxytryptamine(5-HT) receptor, and interleukin-6(IL-6) to exert sedative, anxiolytic, and antidepressant effects. Sixty 4-week-old SPF mice were randomly divided into a control group, a model group, a positive drug(diazepam tablets) group, and low-, medium-, and high-dose berberine groups. Medication with corresponding drugs was performed for one week. The results demonstrated that berberine was potent in reducing the activities and standing times of mice, down-regulating the levels of CRP and IL-6 mRNA in the hypothalamus, and up-regulating the expression of 5-HT(P<0.01); however, no significant effect on ESR1 was observed. The network of Euodiae Fructus in treating insomnia was constructed by network pharmacology and verified by tests. The findings indicated that the therapeutic efficacy of Euodiae Fructus in treating insomnia was achieved by participating in multiple biological processes, such as neurotransmitter receptor activity, which provided a scientific basis for its clinical application.

3D genome alterations associated with dysregulated HOXA13 expression in high-risk T-lineage acute lymphoblastic leukemia.

3D genome alternations can dysregulate gene expression by rewiring enhancer-promoter interactions and lead to diseases. We report integrated analyses of 3D genome alterations and differential gene expressions in 18 newly diagnosed T-lineage acute lymphoblastic leukemia (T-ALL) patients and 4 healthy controls. 3D genome organizations at the levels of compartment, topologically associated domains and loop could hierarchically classify different subtypes of T-ALL according to T cell differentiation trajectory, similar to gene expressions-based classification. Thirty-four previously unrecognized translocations and 44 translocation-mediated neo-loops are mapped by Hi-C analysis. We find that neo-loops formed in the non-coding region of the genome could potentially regulate ectopic expressions of TLX3, TAL2 and HOXA transcription factors via enhancer hijacking. Importantly, both translocation-mediated neo-loops and NUP98-related fusions are associated with HOXA13 ectopic expressions. Patients with HOXA11-A13 expressions, but not other genes in the HOXA cluster, have immature immunophenotype and poor outcomes. Here, we highlight the potentially important roles of 3D genome alterations in the etiology and prognosis of T-ALL.

Genome-wide mapping of human DNA replication by optical replication mapping supports a stochastic model of eukaryotic replication.

The heterogeneous nature of eukaryotic replication kinetics and the low efficiency of individual initiation sites make mapping the location and timing of replication initiation in human cells difficult. To address this challenge, we have developed optical replication mapping (ORM), a high-throughput single-molecule approach, and used it to map early-initiation events in human cells. The single-molecule nature of our data and a total of >2,500-fold coverage of the human genome on 27 million fibers averaging ∼300 kb in length allow us to identify initiation sites and their firing probability with high confidence. We find that the distribution of human replication initiation is consistent with inefficient, stochastic activation of heterogeneously distributed potential initiation complexes enriched in accessible chromatin. These observations are consistent with stochastic models of initiation-timing regulation and suggest that stochastic regulation of replication kinetics is a fundamental feature of eukaryotic replication, conserved from yeast to humans.