Characteristics and clinical outcomes of patients with sarcoidosis admitted for ST-elevation myocardial infarction in the United States: a propensity matched analysis from the National Inpatient Sample.

Introduction: Sarcoidosis is a systemic inflammatory disorder characterised by non-caseating granulomas. Cardiac sarcoidosis (CS) normally causes conduction abnormalities, ventricular arrhythmias, and heart failure. Little is known about the characteristics and impact of sarcoidosis in patients admitted with ST-elevation myocardial infarction (STEMI). This study aims to fill this void. Material and methods: Utilising the National Inpatient Sample (NIS) database (2016-2020), individuals with STEMI were identified and categorised based on sarcoidosis presence whilst adjusting for confounders via logistic regression models. Results: Among 851,290 STEMI patients, 1215 had sarcoidosis. Before propensity matching, sarcoidosis patients were notably different in demographics and comorbidities compared to non-sarcoidosis patients. After propensity score matching (PSM), sarcoidosis patients were found to have a higher incidence of supraventricular tachycardia (SVT) (2.5% vs. 1.3%, p = 0.024) and acute kidney injury (AKI) (23.3% vs. 20.8%, aOR = 1.269, 95% CI: 1.02-1.58, p = 0.033) but a lower incidence of undergoing coronary artery bypass graft (CABG) (5.5% vs. 8.5%, aOR = 0.663; 95% CI: 0.472-0.931, p = 0.018), while no significant disparities were noted in PCI, cardiogenic shock, mortality, or mean length of stay (LOS). Conclusions: Using propensity-matched large real-world data of STEMI patients, sarcoidosis was associated with fewer cases of CABG and a greater incidence of AKI and SVT compared to non-sarcoidosis patients.

Effect of the Polypill on Adherence and Prevention of Cardiovascular Diseases in Patients With or at High Risk of Cardiovascular Diseases: A Meta-Analysis of Randomized Controlled Trials.

It is important to understand the role of polypills on medication adherence and clinical outcomes in patients with or at high risk of cardiovascular diseases (CVD) to help decision-makers make robust guidelines on using polypills in these people. Therefore, the current meta-analysis was conducted to assess the impact of polypills on medication adherence and clinical outcomes in patients with or at high risk of CVD. The present meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We searched the electronic databases PubMed, Embase, and the Cochrane Library for randomized control trials (RCTs) from inception to January 1, 2023. The outcomes assessed in the present meta-analysis were adherence to prescribed drugs at the study end, the incidence of cardiovascular events, and change in low-density lipoprotein cholesterol (LDL-C), total cholesterol, and high-density lipoprotein (HDL) from baseline to the study end in mmol/l. A total of six studies were included in the present meta-analysis, with a total sample size of 13139 (6577 in the polypill group and 6562 in the control group). Meta-analysis showed that medication adherence was significantly higher in patients receiving polypills compared to the control group (relative risk (RR): 1.38, 95% confidence interval (CI): 1.22-1.56, p-value: 0.001). The risk of a cardiovascular event was significantly lower in the polypill group (RR: 0.72, 95% CI: 0.63-0.82, p-value: 0.001). No significant differences were found in the changes in LDL-C and total cholesterol between the two groups. This meta-analysis shows a significant impact of polypills on medication adherence. We also found that polypills can reduce the incidence of cardiovascular events in patients with or at high risk of CVD. Our study has also shown that regardless of the history of CVD, polypills play an important role in promoting medication adherence in patients with and without a history of CVD.

Comparison of the Efficacy and Safety of Apixaban and Warfarin in the Prevention of Stroke in Patients With Non-valvular Atrial Fibrillation: A Meta-Analysis.

Atrial fibrillation is an irregular heart rhythm, and it is one of the most common cardiac arrhythmias. It is associated with a five times increase in the risk of stroke. Anti-coagulants are prescribed routinely to prevent strokes, especially in patients with atrial fibrillation for many years decreasing the risk of stroke among patients with atrial fibrillation. Non-vitamin K oral anticoagulants especially apixaban and rivaroxaban are frequently used and they are considered to be safe and more effective than warfarin. The aim of this meta-analysis is to compare the efficacy and safety of apixaban and warfarin in preventing stroke among patients with non-valvular arterial fibrillation. The current meta-analysis was conducted using the guidelines established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A systematic search was done using databases, including PubMed, EMBASE, and Cochrane Library, with no restrictions on language and year of publication. The current meta-analysis included randomized control trials and non-randomized control trials (prospective and retrospective cohort studies) comparing the efficacy and safety of apixaban and warfarin in preventing stroke in patients with non-valvular atrial fibrillation. The primary efficacy outcome was stroke or systemic embolism while the primary safety outcome was major bleeding events. Overall, nine articles were included in the current meta-analysis with a pooled sample size of 267998 patients with non-valvular atrial fibrillation. The administration of apixaban was associated with a significant decrease in stroke or systemic embolism (RR: 0.77, 95% CI: 0.67-0.90) and major bleeding events (RR=0.63, 95% CI: 0.58-0.68) as compared to warfarin. However, no significant difference was reported in all-cause mortality (RR=0.80, 95% CI: 0.30-2.14) between the two groups. The current meta-analysis concluded that apixaban, compared to warfarin in patients with non-valvular atrial fibrillation showed a reduction in stroke and systemic embolism. Apixaban has also a better safety profile in terms of reduction in overall major bleeding events.

Comparison of Cardiovascular Outcomes Between Dapagliflozin and Empagliflozin in Patients With Type 2 Diabetes: A Meta-Analysis.

Sodium-glucose cotransporter-2 (SGLT2) inhibitors are oral diabetes medications that enhance the excretion of glucose by preventing the renal proximal tubules from reabsorbing glucose, which lowers glucose levels in plasma. Currently, studies have shown that SGLT2 inhibitors have beneficial impacts on cardiovascular outcomes, but their effect varies between the individual SGLT2 inhibitors. Thus, the current meta-analysis was conducted to compare the efficacy of dapagliflozin and empagliflozin in preventing cardiovascular events in patients with type 2 diabetes. The current meta-analysis was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. A search of studies comparing cardiovascular events between dapagliflozin and empagliflozin in patients with type 2 diabetes published up to 1 July 2022 was done by two reviewers independently on PubMed, Embase and Cumulated Index to Nursing and Allied Health Literature (CINAHIL). The pre-specified primary endpoints were cardiovascular death, stroke, myocardial infarction and heart failure. Overall four studies were included in this meta-analysis. No significant difference was found in the incidence of myocardial infarction (risk ratio (RR)=0.81, 95% confidence interval (CI): 0.60-1.09), heart failure (RR=0.76, 95% CI: 0.56-1.04), cardiovascular mortality (RR=0.46, 95% CI: 0.18-1.20) and stroke (RR=1.07, 95% CI: 0.84-1.38) between dapagliflozin and empagliflozin. Results have shown that the risk of developing stroke, heart failure, myocardial infarction and cardiovascular death were not significantly different in the two groups.

Efficacy and Safety of Colchicine in Prevention of Secondary Cardiovascular Outcomes Among Patients With Coronary Vessel Disease: A Meta-Analysis.

Coronary vessel disease (CVD) is a class of diseases that impacts the blood vessels and heart and is one of the leading causes of disability and death. CVD includes cerebrovascular disease and coronary heart disease, both illnesses of the vessels transporting the oxygenated blood to the brain or heart. Colchicine is an inexpensive and old drug with strong anti-inflammatory effects. Numerous randomized control trials (RCTs) have demonstrated the effectiveness of low-dose colchicine for the prevention of severe cardiovascular events without showing any signs of serious adverse effects within the regime of treatment. In the current meta-analysis, we aim to assess the efficacy and safety of colchicine for secondary cardiovascular outcome prevention among patients with clinically proven CVD. The current meta-analysis was carried out using the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines. PUBMED, Cochrane, and EMBASE databases were used to search for RCTs comparing colchicine and placebos for the prevention of secondary cardiovascular outcomes. The primary efficacy endpoint was mortality due to cardiovascular disease, stroke, urgent coronary revascularization, and myocardial infarction. Secondary efficacy outcomes included death due to all-cause mortality. Seven RCTs were reviewed, with a pooled sample size of 12114, out of which 6099 were randomized to the colchicine group, and 6015 were randomized to the control group. The decrease in cardiovascular events, including myocardial infarction, stroke, urgent coronary revascularization, and cardiac-related death, was significantly lower in patients randomized to colchicine (p-value<0.05). The incidence of safety outcomes did not vary significantly different between groups (p>0.05). In patients with CVD, compared to standard medical therapy, colchicine significantly decreases the risk of cardiovascular events such as cardiovascular-related death, myocardial infarction, stroke, and urgent coronary revascularizations.

The Use of the SMART-COP Score in Predicting Severity Outcomes Among Patients With Community-Acquired Pneumonia: A Meta-Analysis.

Pneumonia is a pathological process of interstitial lung tissue and distal airway and alveolar infection and infiltration. SMART-COP (systolic blood pressure, multilobar infiltrates, albumin, respiratory rate, tachycardia, confusion, oxygen, and pH) is a severity score method designed to identify individuals who require intensive respiratory or vasopressor support (IRVS) support due to pneumonia. Therefore, it is important for management decisions in pneumonia. This meta-analysis was conducted to determine the performance of the SMART-COP score in predicting the prognosis and severity of patients presenting with community-acquired pneumonia (CAP). The current meta-analysis was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic search was conducted using Medline, Embase, and CINAHL to identify relevant studies assessing the validity of the SMART-COP score in predicting the severity of patients with CAP. Overall, nine studies were included in the current meta-analysis. A pooled sensitivity of the SMART-COP score to predict the use of IRVS is 89% (95% CI: 84%-92%) while its specificity is 68% (95% CI: 65%-70%). The pooled sensitivity of the SMART-COP score to predict 30-day mortality is 92% (95% CI: 89%-94%) while its specificity is 39% (95% CI: 37%-42%). To summarize, SMART-COP is a new, eight-variable instrument that appears to accurately identify patients with CAP who will require IRVS and 30-day mortality. Our findings show that SMART-COP will be a valuable tool for clinicians in accurately predicting illness severity in CAP patients as compared to other scoring systems. SMART-COP can be useful to identify patients who need urgent management.

Fixed Versus Variable Dosing of Prothrombin Complex Concentrate for Bleeding Complications of Vitamin K Antagonists-The PROPER3 Randomized Clinical Trial.

STUDY OBJECTIVE: To determine if a fixed dose of 1000 IU of 4-factor prothrombin complex concentrate (4F-PCC) is as effective as traditional variable dosing based on body weight and international normalized ratio (INR) for reversal of vitamin K antagonist (VKA) anticoagulation. METHODS: In this open-label, multicenter, randomized clinical trial, patients with nonintracranial bleeds requiring VKA reversal with 4F-PCC were allocated to either a 1,000-IU fixed dose of 4F-PCC or the variable dose. The primary outcome was the proportion of patients with effective hemostasis according to the International Society of Thrombosis and Haemostasis definition. The design was noninferiority with a lower 95% confidence interval of no more than -6%. When estimating sample size, we assumed that fixed dosing would be 4% superior. RESULTS: From October 2015 until January 2020, 199 of 310 intended patients were included before study termination due to decreasing enrollment rates. Of the 199 patients, 159 were allowed in the per-protocol analysis. Effective hemostasis was achieved in 87.3% (n=69 of 79) in fixed compared to 89.9% (n=71 of 79) in the variable dosing cohort (risk difference 2.5%, 95% confidence interval -13.3 to 7.9%, P=.27). Median door-to-needle times were 109 minutes (range 16 to 796) in fixed and 142 (17 to 1076) for the variable dose (P=.027). INR less than 2.0 at 60 minutes after 4F-PCC infusion was reached in 91.2% versus 91.7% (P=1.0). CONCLUSION: The large majority of patients had good clinical outcome after 4F-PCC use; however, noninferiority of the fixed dose could not be demonstrated because the design assumed the fixed dose would be 4% superior. Door-to-needle time was shortened with the fixed dose, and INR reduction was similar in both dosing regimens.

Method agreement analysis and interobserver reliability of the ISTH proposed definitions for effective hemostasis in management of major bleeding.

Essentials In 2016 the SSC proposed definitions for effective hemostasis in management of major bleeding. To validate these definitions, we studied the use in three large anticoagulant-reversal studies. Method agreement analysis and interobserver reliability showed at least acceptable agreement. Recommendations were made, advising use of the definition in hemostatic effectiveness studies. SUMMARY: Introduction In 2016 the Scientific and Standardization Subcommittee (SSC) on Control of Anticoagulation of the International Society on Thrombosis and Haemostasis (ISTH) proposed criteria to evaluate the effectiveness of anticoagulant reversal in major bleeding management. Testing and validation of these criteria are required. Objective To investigate the method agreement, interobserver reliability and applicability of the ISTH proposed definitions for hemostatic effectiveness. Methods Patient data from three anticoagulant-antidote studies were used for hemostatic effectiveness assessment using the ISTH-proposed definitions and clinical opinion. For every patient a case document was produced. For each cohort, four adjudicators were asked to assess the hemostatic effectiveness independently on a case-by-case basis. Agreement between the two methods of hemostatic effectiveness assessment was calculated using Cohen's kappa (κ), with a calculated sample size of at least 73 cases. Results The full dataset consisted of 116 cases, resulting in 464 assessments. Method agreement in outcome was observed in 364 of 464 assessments (78.5%), resulting in κ of 0.634 (95% CI: 0.575-0.694), or "substantial agreement." Interobserver reliability analysis of the proposed definitions computed an overall agreement of 54.2% with κ of 0.312 ("fair agreement"). Discussion Method agreement analysis shows that the conclusions drawn using the ISTH definitions have "substantial agreement" with clinical opinion. Interobserver reliability analysis demonstrated acceptable agreement. In-depth analysis provided minor opportunities for further improvement and correct application of the definition. The definition is recommended to be used in all future studies evaluating hemostatic effectiveness, taking the suggested recommendations into account.

Clinical outcome of patients with a vitamin K antagonist-associated bleeding treated with prothrombin complex concentrate.

BACKGROUND: Vitamin K antagonists (VKA) are used for the treatment of thromboembolism. Patients with severe VKA-associated bleeding require immediate restoration of haemostasis. Clinical studies on the effect of prothrombin complex concentrate (PCC) are heterogeneous with respect to outcome of bleeding. OBJECTIVE: To evaluate the clinical outcome of patients treated with PCC for VKA-associated bleeding. METHODS: We performed a cohort study of consecutive patients who received PCC for VKA-related bleeding in five Dutch hospitals. Data were collected by chart review on the bleeding event, international normalized ratio (INR), haemostatic efficacy, thromboembolic (TE) complications, and mortality. The primary outcome was effective haemostasis, assessed by an adaptation of the Sarode criteria with a surrogate outcome for patients with ICH without repeat CT. RESULTS: One hundred patients were included. Mean age was 74 years, 54% were male and 79% received VKA for atrial fibrillation. Most patients presented with ICH (41%) or GI bleeding (36%). Effective haemostasis was achieved in 67/98 (68%) patients using the adapted classification. Surrogate outcomes were applied for 32 patients and data for two patients was missing. Median pre-treatment INR was 3.9 (IQR 2.9-5.8). One hour after PCC infusion, the INR was available for 50 patients and of these, 35 (70%) had an INR ≤1.4. TE complications occurred in five patients and 22 died (60% bleeding-related) within 30 days. CONCLUSION: PCC achieved effective haemostasis in 68% of evaluable patients with VKA-associated bleeding. TE complication rates were low, but mortality rates were high, due to the large number of patients with ICH.

Randomised controlled trial protocol to evaluate a fixed dose prothrombin complex concentrate against the variable dose in vitamin K antagonist related bleeding (PROPER3).

INTRODUCTION: There is currently little evidence for the optimal dosing strategy of four-factor prothrombin complex concentrates (PCC) in vitamin K antagonist (VKA)-related bleeds. The generally accepted dosing strategy is the use of a variable dose calculated using patient-specific characteristics as per manufacturer's instruction. However, evidence exists that the use of a fixed low dose of 1000 international units of factor IX (IU fIX) might also suffice. Recent studies indicate that in terms of haemostatic effectiveness, the fixed dosing strategy might be even superior to the variable dosing strategy. The PROPER3 (PROthrombin complex concentrate: Prospective Evaluation and Rationalisation, number 3) study aims to confirm the non-inferiority, and explore superiority, in haemostatic effectiveness of the fixed PCC dosing strategy compared with the variable dosing strategy in VKA-related extracranial bleeding emergencies. METHODS AND ANALYSIS: The study is designed as a randomised controlled multicentre non-inferiority trial. Eligibility criteria are an indication for PCC due to VKA-related extracranial bleeding in subjects 18 years of age or older. The control group will receive a variable dose, determined by patient-specific bodyweight and international normalised ratio. The intervention group is dosed a fixed 1000 IU fIX PCC. Primary outcome is the haemostatic effectiveness of both treatments, as defined by the 2016 International Society on Thrombosis and Haemostasis (ISTH) criteria. The sample size is set at 155 patients per treatment arm, requiring 310 patients in total. Non-inferiority on the proportion (risk) difference of the primary outcome will be evaluated using the asymptotic Wald test for non-inferiority. The non-inferiority margin is set at 6%. The primary analysis will be based on the per-protocol population. ETHICS AND DISSEMINATION: Study results will be published in an international journal, communicated to discipline-specific associations and presented at (inter)national meetings and congresses. TRIAL REGISTRATION NUMBER: EUCTR2014-000392-33; Pre-results.

Comparative evaluation of efficacy and safety profile of rhubarb and α-keto analogs of essential amino acids supplementation in patients with diabetic nephropathy.

To determine the efficacy and safety profile of rhubarb and α-keto analogs of essential amino acids supplementation in patients of diabetic nephropathy (DN), we studied 96 patients of DN attending a tertiary care center of the North India. The patients were randomly divided into three equal interventional groups. Group I (control) that received conservative management along with placebo, Group II (rhubarb) that received conservative management along with rhubarb capsule (350 mg, thrice daily), and Group III [keto amino acid (KAA)] that received conservative management along with α-keto analogs of essential amino acids (600 mg, thrice daily). The treatment was continued for 12 weeks. Clinical and biochemical parameters were assessed at 0, 4, 8, and 12 weeks of treatment. A progressive improvement in clinical features and biochemical parameters was seen in all three groups after 12 weeks of treatment. The KAA group showed more marked improvement in clinical features as well as biochemical parameters compared to the rhubarb group. There was a reduction in blood glucose, blood urea, serum creatinine, and 24 h total urine protein. There was an increase in hemoglobin, 24 h total urine volume, and glomerular filtration rate. There was no statistical difference between the rhubarb and KAA groups with respect to side effects (P > 0.05). Our study suggests that KAA is more effective than rhubarb as add-on therapy with conservative management in patients of DN.

Evaluation of Rhubarb Supplementation in Stages 3 and 4 of Chronic Kidney Disease: A Randomized Clinical Trial.

Objective. To evaluate the efficacy and safety of Rhubarb supplementation in patients of chronic kidney disease. Material and Methods. This study was a prospective comparative study conducted in patients of chronic kidney disease (stages 3 & 4) attending Renal Clinic of Department of Medicine, JN Medical College & Hospital, AMU, Aligarh. Patients were randomly divided into two interventional groups. Group I (Control) was given conservative management while Group II (Rhubarb) received conservative management along with Rhubarb capsule (350 mg, thrice daily) for 12 weeks. Haemogram and renal function tests were measured at 0, 4, 8, and 12 weeks of treatment. Results. There was progressive improvement in clinical features in both the groups after 12 weeks of treatment but Rhubarb group showed more marked improvement as compared to control group. Both groups showed gradual improvement in the biochemical parameters as compared to their pretreated values which was more marked in Rhubarb supplemented group. There was reduction in blood glucose, blood urea, serum creatinine, and 24 hour total urine protein (TUP). There was increase in haemoglobin, 24 hour total urine volume (TUV), and glomerular filtration rate (GFR). There was no statistical difference in two groups with respect to side effects (P > 0.05). Conclusion. Rhubarb supplementation improved the therapeutic effect of conservative management in stage 3 and stage 4 patients of chronic kidney disease.

One-third of doctors completing specialist training in diabetes fail to secure a substantive consultant post: young Diabetologists' Forum Survey 2010.

Reports have highlighted a shortage of consultant diabetologist posts in the UK. The number of doctors completing specialist training in diabetes has increased in recent years, but little is known about their employment after they receive their certificate of completion of training. An online survey was sent to all doctors who completed specialist diabetes training from January 2008 to September 2010. Of the 95 eligible respondents, 69 (73%) completed the survey (61% men; median age 36 years). Forty-three (62%) respondents secured substantive NHS consultant posts, and of those who gave their job breakdown, 48/51 (94%) were contributing to specialist diabetes care. Five (7%) respondents held substantive academic positions, while 11 (16%) were locum consultants. Seven (9%) respondents worked abroad, with half of these attributing their emigration to lack of opportunities in the UK. When asked about alternative choices, 39% of respondents were likely to seek 'general physician' roles, which equalled the number who would consider emigrating. Overall, only two-thirds of doctors who complete specialist training in diabetes secure substantive NHS consultant positions, which suggests a failure in workforce planning and a lack of expansion of the number of consultant posts despite progression of the diabetes epidemic.

Modulation of in vivo immunoglobulin production by endogenous histamine and H1R and H2R agonists and antagonists.

The present study was designed to delineate the immunomodulatory role of histamine receptors (H1R and H2R) and their antibody generation in a rabbit model. Six groups containing 18 rabbits each received either vehicle (sterile distilled water, 1 ml/kg x b.i.d), histamine (100 µg/kg x b.i.d.), H1R agonist (HTMT, 10 µg/kg x b.i.d.), H2R agonist (amthamine, 10 µg/kg x b.i.d.), H1R antagonist (pheniramine, 10 mg/kg x b.i.d.) or H2R antagonist (ranitidine, 10 mg/kg x b.i.d.). All animals were subsequently immunized with an intravenous injection of sheep red blood cells (SRBC). Estimations of total serum immunoglobulins (Igs), immunoglobulin M (IgM) and immunoglobulin G (IgG) were performed by ELISA and hemagglutination assay (HA) at days 0 (pre-immunization), 7, 14, 21, 28 and 58 (post-immunization). Both the ELISA and the HA showed similar production of Igs, IgM and IgG but the results were found comparatively more significant by ELISA as opposed to HA. Results showed that histamine could influence a detectable antibody response to SRBC early (i.e., at day 7), which lasted until day 58. Immunomodulatory processes showed suppression of an Ig generation in the H1R-antagonist group with enhancement in the H2R-antagonist group. The H1R-agonist group showed an increased Ig production in comparison to the H2R-agonist group. The IgM production was inhibited in the H1R-antagonist group as compared to the H2R-antagonist group, and it was also suppressed in H1R-agonist group as compared to H2R-agonist group. IgG production was inhibited in the H1R-antagonist group as opposed to the H2R-antagonist group. In contrast, the H1R-agonist group increased IgG production as compared to the H2R-agonist group. All the results were found to be statistically significant (p < 0.05 or p < 0.01). In conclusion, histamine and its receptor (H1R and H2R) agonists enhance antibody production by triggering the histamine receptors (H1R and H2R), and both the H1R antagonist and the H2R antagonist positively or negatively regulate the antibody production. The findings of this study may have clinical significance.

Interplay between ATM and ATR in the regulation of common fragile site stability.

Common fragile sites are specific genomic loci that form constrictions and gaps on metaphase chromosomes under conditions that slow, but do not arrest, DNA replication. These sites have been shown to have a role in various chromosomal rearrangements in tumors. Different DNA damage response proteins were shown to regulate fragile site stability, including ataxia-telangiectasia and Rad3-related (ATR) and its effector Chk1. Here, we investigated the role of ataxia-telangiectasia mutated (ATM), the main transducer of DNA double-strand break (DSB) signal, in this regulation. We demonstrate that replication stress conditions, which induce fragile site expression, lead to DNA fragmentation and recruitment of phosphorylated ATM to nuclear foci at DSBs. We further show that ATM plays a role in maintaining fragile site stability, which is revealed only in the absence of ATR. However, the activation of ATM under these replication stress conditions is ATR independent. Following conditions that induce fragile site expression both ATR and ATM phosphorylate Chk1, suggesting that both proteins regulate fragile site expression probably via their effect on Chk1 activation. Our findings provide new insights into the interplay between ATR and ATM pathways in response to partial replication inhibition and in the regulation of fragile site stability.

Replication delay along FRA7H, a common fragile site on human chromosome 7, leads to chromosomal instability.

Common fragile sites are specific chromosomal loci that show gaps, breaks, or rearrangements in metaphase chromosomes under conditions that interfere with DNA replication. The mechanism underlying the chromosomal instability at fragile sites was hypothesized to associate with late replication time. Here, we aimed to investigate the replication pattern of the common fragile site FRA7H, encompassing 160 kb on the long arm of human chromosome 7. Using in situ hybridization on interphase nuclei, we revealed that the replication of this region is initiated relatively early, before 30% of S phase is completed. However, a high fraction ( approximately 35%) of S-phase nuclei showed allelic asynchrony, indicating that the replication of FRA7H is accomplished at different times in S phase. This allelic asynchrony is not the result of a specific replication time of each FRA7H allele. Analysis of the replication pattern of adjacent clones along FRA7H by using cell population and two-color fluorescent in situ hybridization analyses showed significant differences in the replication of adjacent clones, under normal growth condition and upon aphidicolin treatment. This pattern significantly differed from that of two nonfragile regions which showed a coordinated replication under both conditions. These results indicate that aphidicolin is enhancing an already existing difference in the replication time along the FRA7H region. Based on our replication analysis of FRA7H and on previous analysis of the common fragile site FRA3B, we suggest that delayed replication is underlying the fragility at aphidicolin-induced common fragile sites.