49,346 research outputs found

    Investigating microstructural variation in the human hippocampus using non-negative matrix factorization

    No full text
    In this work we use non-negative matrix factorization to identify patterns of microstructural variance in the human hippocampus. We utilize high-resolution structural and diffusion magnetic resonance imaging data from the Human Connectome Project to query hippocampus microstructure on a multivariate, voxelwise basis. Application of non-negative matrix factorization identifies spatial components (clusters of voxels sharing similar covariance patterns), as well as subject weightings (individual variance across hippocampus microstructure). By assessing the stability of spatial components as well as the accuracy of factorization, we identified 4 distinct microstructural components. Furthermore, we quantified the benefit of using multiple microstructural metrics by demonstrating that using three microstructural metrics (T1-weighted/T2-weighted signal, mean diffusivity and fractional anisotropy) produced more stable spatial components than when assessing metrics individually. Finally, we related individual subject weightings to demographic and behavioural measures using a partial least squares analysis. Through this approach we identified interpretable relationships between hippocampus microstructure and demographic and behavioural measures. Taken together, our work suggests non-negative matrix factorization as a spatially specific analytical approach for neuroimaging studies and advocates for the use of multiple metrics for data-driven component analyses

    Tissue plasminogen activator dose and pulmonary artery pressure reduction in catheter directed thrombolysis of submassive pulmonary embolism.

    Get PDF
    PURPOSE:The purpose of this study is to assess the incremental effect of tissue plasminogen activator (t-PA) dose on pulmonary artery pressure (PAP) and bleeding during catheter directed thrombolysis (CDT) of submassive pulmonary embolism (PE). MATERIALS AND METHODS:Records of 46 consecutive patients (25 men, 21 women, mean age 55±14 y) who underwent CDT for submassive PE between September 2009 and February 2017 were retrospectively reviewed. Mean t-PA rate was 0.7±0.3 mg/h. PAP was measured at baseline and daily until CDT termination. Mixed-effects regression modeling was performed of repeated PAP measures in individual patients. Bleeding events were classified by Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) and t-PA dose at onset. RESULTS:Mean t-PA dose was 43.0±30.0 mg over 61.9± 28.8 h. Mean systolic PAP decreased from 51.7±15.5 mmHg at baseline to 35.6±12.7 mmHg at CDT termination (p<0.001). Mixed-effects regression revealed a linear decrease in systolic PAP over time (β = -0.37 (SE = 0.05), p<0.001) with reduction in mean systolic PAP to 44.8±1.9 mmHg at 12 mg t-PA/20 h, 39.5±2.0 mmHg at 24 mg t-PA/40 h, and 34.9±2.1 mmHg at 36 mg/60 h. No severe, one moderate, and 8 mild bleeding events occurred; bleeding onset was more frequent at ≤24 mg t-PA (p <0.001). One patient expired from cardiopulmonary arrest after 16 h of CDT (15.4 mg t-PA); no additional intra-procedural fatalities occurred. CONCLUSION:Increased total t-PA dose and CDT duration were associated with greater PAP reduction without increased bleeding events

    Measuring access: how accurate are patient-reported waiting times?

    Get PDF
    Introduction: A national audit of waiting times in England’s genitourinary medicine clinics measures patient access. Data are collected by patient questionnaires, which rely upon patients’ recollection of first contact with health services, often several days previously. The aim of this study was to assess the accuracy of patient-reported waiting times. Methods: Data on true waiting times were collected at the time of patient booking over a three-week period and compared with patient-reported data collected upon clinic attendance. Factors contributing to patient inaccuracy were explored. Results: Of 341 patients providing initial data, 255 attended; 207 as appointments and 48 ‘walk-in’. The accuracy of patient-reported waiting times overall was 52% (133/255). 85% of patients (216/255) correctly identified themselves as seen within or outside of 48 hours. 17% of patients (17/103) seen within 48 hours reported a longer waiting period, whereas 20% of patients (22/108) reporting waits under 48 hours were seen outside that period. Men were more likely to overestimate their waiting time (10.4% versus 3.1% p<0.02). The sensitivity of patient-completed questionnaires as a tool for assessing waiting times of less than 48 hours was 83.5%. The specificity and positive predictive value were 85.5% and 79.6%, respectively. Conclusion: The overall accuracy of patient reported waiting times was poor. Although nearly one in six patients misclassified themselves as being seen within or outside of 48 hours, given the under and overreporting rates observed, the overall impact on Health Protection Agency waiting time data is likely to be limited

    Novel 2-phenyl-3-{4’-[N-(4”-aminophenyl)carbamoyl]-phenyl}-quinazoline-4(3H)one-6-sulphonic acidbased mono azo reactive dyes

    Get PDF
    A series of new heterocyclic mono azo reactive dyes 7a–m were prepared by diazotization of 2-phenyl-3-{4’-[N-(4”-aminophenyl)carbamoyl]-phenyl}-quinazoline-4(3H)-one-6-sulphonic acid (3) and coupling with various cyanurated coupling components 6a–m and their dyeing performance on silk, wool and cotton fibres was assessed. These dyes were found to give a variety of colour shades with very good depth and levelness on the fibres. All the compounds were identified by conventional method (IR and 1H-NMR) and elemental analyses. The percentage dye bath exhaustion on different fibres was reasonably good and acceptable. The dyed fibre showed moderate to very good fastness to light, washing and rubbing

    A Study to Compare Major Adverse Cardiac Event in Patient Undergoing PCI with Drug Eluting Stents Vs Bare Metal Stents

    Full text link
    This study compared Major Adverse Cardiac Event in patient with Acute Coronary Syndromes undergoing PCI with Drug Eluting Stents Vs Bare Metal Stents. A retrospective, observational study was carried out in an inpatient setting of the private tertiary care hospital. Patients with >18 years, diagnosed for Acute Coronary Syndromes (ACS), required intervention in coronary artery with implantation of Drug Eluting Stents (DES) or Bare Metal Stents (BMS) were recruited in the study. The data had been collected from file or database of the hospital. All subjects were followed for major adverse cardiac event. Result. A total of 202 patients who underwent percutaneous coronary intervention (PCI) were enrolled into DES group (N=101) and BMS group (N=101). All patients were followed up at 1 month, 3 months, 6 months & 12 months for Major Adverse Cardiac Events (MACE). Clinical outcomes during 12 months were compared between DES group & BMS group. There was no significant difference in baseline parameters including demographic, risk factors of ACS, diagnosis, angiographic parameters between both groups. Overall MACE rates were reported non-significantly high in BMS group patients (14.85%) compare to DES group patients (8.91%) (P=0.458). However, DES group had lower rates of death (0.99% vs 1.98%, P=0.57), rate of MI (3.96% vs 4.95% P=0.73), rate of revascularization (1.98% vs 3.96% p=0.42) & rate of sub acute thrombosis (1.98% vs 3.96% P=0.42) and higher rate of bleeding (1.98% vs 0.99% p=0.57) compare to cohort-II. Conclusion. The use of DES in the setting of Acute Coronary Syndrome is associated with lower Major Adverse Cardiac Event (MACE) rate compared to BMS without compromising the overall safety over the course of one-year follow-up. The long-term safety of drug-eluting stents needs to be ascertained in large, randomized trials
    corecore