Utilization of a kinetic isotope effect to decrease decomposition of ceftriaxone in a mixture of D2O/H2O

The discovery of cephalosporin and demonstration of its improved stability in aqueous solution, as well as enhanced in vitro activity against penicillin-resistant organisms, were major breakthroughs in the development of β-lactam antibiotics. Although cephalosporins are more stable with respect to hydrolytic degradation than penicillins, they still experience a variety of chemical transformations. The present study offers an insight into the rates and mechanisms of ceftriaxone degradation at the therapeutic concentration in water, a mixture of water and deuterium oxide, and deuterium oxide itself at the neutral pH. Specific ceftriaxone degradation products were observed in aged samples (including a previously unreported dimer-type species), and by comparing the degradation rates in H₂O and D₂O, the observation of a kinetic isotope effect provided some valuable insight as to the nature of the initial ceftriaxone degradation. The effect of protium to deuterium isotope change on the degradation kinetics of ceftriaxone was evaluated using the method of initial rates based on HPLC analysis as well as by quantitative ¹H NMR spectroscopy. Moreover, computational analysis was utilized to get a molecular insight into chemical processes governing the ceftriaxone degradation and to rationalize the stabilizing effect of replacing H₂O with D₂O.

A post processing pipeline to prepare raw data for machine learning algorithms in cardiac magnetic resonance imaging

Funding Acknowledgements

Type of funding sources: None.

Background

Artificial Intelligence is an emergent tool in clinical practice for post processing of medical images. Machine Learning (ML) pipelines are created for data of interest extraction and algorithm application. A common issue in data extraction is represented by noisy datasets, like those of CMR studies, characterized by multiple images, acquired by different techniques, axis orientation and contrast timing.

Purpose

A ML pipeline for extraction of LGE images from raw DICOM data is presented. Additionally, steps for normalization of image number and automatically heart localization are outlined.

Methods and Results

642 consecutive CMR studies were analyzed.

Pipeline, Part 1. By looking at the metadata in raw files, ‘SequenceName’ tag was used to discard cine images, ‘ScanningSequence’ tag to select Gradient Recall and Inversion Recovery techniques (Inversion Time > 100 ms), ‘SequenceVariant’ tag to discard Steady State images (See Fig. 1). Orientation of the major axis was computed and ‘Axial’ or ‘Coronal’ images removed. Scans were grouped together by image orientation (requesting a min and max number of elements per group) and only the group with the largest number of files was selected. Finally, DICOMs were grouped by image shape (demanding a min number of elements), and only the series with the highest resolution was retained. Then, for each subject, the extracted series consists of a 3D-array (N,H,W), with N number of slices, and (H,W) image resolution. The attributes were not homogeneous between subjects.

Pipeline, Part 2. Given a desired final number of slices and resolution, the 3D-array was reshaped through a spline interpolation. In order to have a focus on the heart, a Region of Interest (ROI) extractor was implemented, based on a YOLO network for object detection. The network was applied on all the slices (Fig. 2); then the images were cropped by keeping the largest bounding box. This step allowed us to remove the background by only selecting the relevant ROIs. To manage the data more easily, images were saved as a NumPy Array, while other useful Dicom metadata (e.g. weight, age, …) were stored using the json standard.

At the end of the ML pipeline, images can be reduced to a common resolution and forwarded to ML algorithms.

By using this pipeline, a great amount of information not needed for LGE analysis can be discarded, granting a significant reduction in terms of data storage. In our series, the original dataset extended for about 200 GB; by requesting 10 slices per subject with a resolution of 128 by 128 pixels (also extracting heart ROI) the final dimension was reduced to 108 MB.

Conclusions

In this work, we presented a post-processing pipeline for CRM images and LGE analysis. Given in input raw CRM the pipeline is able to (i) remove unuseful data, (ii) extract heart ROIs storing also Dicom metadata, (iii) normalize slices and image resolution, and (iv) store the processed CRM into ready-format for ML techniques. Fig.1:Pipeline Schematic RepresentationFig.2:YOLO Heart Extraction

P12 SUBCUTANEOUS IMPLANTABLE CARDIOVERTER–DEFIBRILLATOR AFTER TRANSVENOUS LEAD EXTRACTION: SAFETY, EFFICACY AND OUTCOME

Background

Subcutaneous implantable cardioverter defibrillator (S–ICD) is a suitable alternative for trans–venous–ICD (TV–ICD) patients underwent transvenous lead extraction (TLE) for any reason, but limited data are available about outcome of s–ICD patients implanted after TLE.

Methods

Thirty–six consecutive patients underwent TLE of TV–ICD and subsequent S–ICD implantation in our center were included in this prospective single–center observational study (72.2% male, median age 52 years–old).

Results

During a median follow-up of 31 months, 3 patients (8.3%) experienced appropriate therapy and 7 patients (19.4%) experienced complications including innapropriate therapy (IAT) (n = 4; 11.1%), pulse generator decubitus with no evidence of infection (n = 2; 5.5%) and ineffective therapy (n = 1; 2.7%). Reasons of IAT were: T–wave oversensing in one patient and extracardiac signals in the remaining 3 patients. Of note, 2 patients who experienced IAT had a left–ventricular assist device (LVAD) for refractory heart failure (HF). Premature device explantation and TV–ICD re–implantation occurred in 4 patients (11%) for pulse generator decubitus despite surgical pocket revisions (n = 2), for recurrent IAT despite reprogramming (n = 1) and ineffective therapy during arrhythmic storm (n = 1). Eight patients (22.2%) died, 3 patients (9%) underwent LVAD implantation due refractory HF during follow-up. Six patients died because of refractory HF, 1 patient died due to intracerebral hemorrhage and 1 due to sarcoidosis. There were no documented deaths associated with the procedure or the S–ICD system itself. No patient had the device removed because of a perceived need for antitachycardia pacing (ATP) or the necessity of pacing or cardiac resynchronization therapy despite 9 patients (25%) after TLE of a two–chamber ICD and one patient (3%) after TLE of a CRT–D. Univariate predictors of death included hypertension (HR 22.72; p = 0.02), diabetes (HR 10.64; p = 0.001), ischemic heart disease (HR 5.92; p = 0.01) and NYHA class > = II (p = 0.04). We did not observed any predictors for complications including IATs and device-related complications requiring surgical revision.

Conclusions

S–ICD implantaion after TLE of TV–ICD is safy and effective. Baseline clinical characterisctics including ischemic heart disease, diabetes, hypertension and NYHA class > = II are associated with worse survival.

N-substituted benzimidazole acrylonitriles as in vitro tubulin polymerization inhibitors: Synthesis, biological activity and computational analysis

We present the design, synthesis and biological activity of novel N-substituted benzimidazole based acrylonitriles as potential tubulin polymerization inhibitors. Their synthesis was achieved using classical linear organic and microwave assisted techniques, starting from aromatic aldehydes and N-substituted-2-cyanomethylbenzimidazoles. All newly prepared compounds were tested for their antiproliferative activity in vitro on eight human cancer cell lines and one reference non-cancerous assay. N,N-dimethylamino substituted acrylonitriles 30 and 41, bearing N-isobutyl and cyano substituents placed on the benzimidazole nuclei, showed strong and selective antiproliferative activity in the submicromolar range of inhibitory concentrations (IC₅₀ 0.2-0.6 μM), while being significantly less toxic than reference systems docetaxel and staurosporine, thus promoting them as lead compounds. Mechanism of action studies demonstrated that two most active compounds inhibited tubulin polymerization. Computational analysis confirmed the suitability of the employed benzimidazole-acrylonitrile skeleton for the binding within the colchicine binding site in tubulin, thus rationalizing the observed antitumor activities, and demonstrated that E-isomers are active substances. It also provided structural determinants affecting both the binding position and the matching affinities, identifying the attached NMe₂ group as the most dominant in promoting the binding, which allows ligands to optimize favourable cation∙∙∙π and hydrogen bonding interactions with Lys352.

Working memory in Down syndrome: is there a dual task deficit?

BACKGROUND

Recent studies have shown that individuals with Down syndrome (DS) are poorer than controls in performing verbal and visuospatial dual tasks. The present study aims at better investigating the dual task deficit in working memory in individuals with DS.

METHOD

Forty-five individuals with DS and 45 typically developing children matched for verbal mental age completed a series of verbal and visuospatial working memory tasks, involving conditions that either required the combination of two tasks in the same modality (verbal or visual) or of cross-modality pairs of tasks.

RESULTS AND CONCLUSIONS

Two distinct deficits were found in individuals with DS: impairment in verbal tasks and further impairment in all dual task conditions. The results confirm the hypothesis of a central executive impairment in individuals with DS.

Executive function in adolescents with Down Syndrome

BACKGROUND

The present work is aimed at analysing executive function (EF) in adolescents with Down Syndrome (DS). So far, EF has been analysed mainly in adults with DS, showing a pattern of impairment. However, less is known about children and adolescents with this syndrome. Studying adolescents with DS might help us better understand whether performances on EF tasks of individuals with DS are determined by age or by Alzheimer disease, as some studies suggest, or whether their performances are directly related to DS cognitive profile.

METHOD

A battery of EF tasks assessing set shifting, planning/problem-solving, working memory, inhibition/perseveration and fluency, as well as a tasks assessing sustained attention has been administered to a group of 15 adolescents with DS and 15 typically developing children matched for mental age. All EF tasks were selected from previous studies with individuals with intellectual disabilities or from developmental literature and are thought to be useful for the samples considered.

RESULTS

The present results revealed that the group of individuals with DS performed at a significantly lower level on tasks assessing set shifting, planning/problem-solving, working memory and inhibition/perseveration, but not on the tasks assessing fluency. In addition, individuals with DS demonstrated a greater number of errors and less strategy use for the sustained attention task.

CONCLUSIONS

The results suggest a broad impairment in EF in adolescents with DS, and are consistent with several similar studies conducted with adults with DS. We assume that EF deficit is a characteristic of DS.

Factors affecting false-negative rates on ex vivo sentinel lymph node mapping in colorectal cancer

PURPOSE

Despite the increasing use of sentinel lymph node (SLN) mapping after colorectal cancer resection, reported node identification and false-negative rates vary considerably. The main aim of this prospective study was to quantify the false-negative rates on SLN mapping after resection and to evaluate factors influencing them.

METHODS

Sixty-nine patients with biopsy-proven cancer of the colon and rectum underwent SLN mapping according to a protocol involving the ex vivo submucosal and peritumoral injection of 2-4 ml of Patent Blue V dye. All lymph nodes visualized were marked as SLN and totally embedded, then two 4 microm sections were cut for hematoxylin and eosin staining, and cytokeratin (AE1/AE3) immunostaining. A standard examination of the whole specimen and of the regional non-sentinel lymph nodes was also performed.

RESULTS

SLNs were identified in 97.3% of the evaluable cases. A mean of 5.0 SLNs were removed per patient (SD+/-4.2). Nine false negatives were identified. Rectal cancer, tumor size>60mm, number of metastatic non-sentinel lymph nodes, and mucinous tumors were associated with false-negative SLNs. At multivariate analysis, a rectal location and mucinous differentiation were independently associated with false-negative SLNs.

CONCLUSIONS

Ex vivo SLN mapping after colorectal cancer surgery is technically feasible with a high identification rate. Tumor size and stage, rectal involvement and a mucinous histology seem to interfere with the reliability of SLN staging. It is mandatory to standardize the procedure and selection criteria in order to deal with the question of the reliability of SLN mapping in colorectal cancer.

Rupture of the quadriceps tendon after arthroscopic lateral meniscectomy: A postoperative complication?

We report a case of complete quadriceps tendon rupture that occurred a few days after arthroscopic lateral meniscectomy. Complications following arthroscopy are rare; there have been many reports of quadriceps tendon rupture in the literature, but none by this kind of mechanism.

An unusual epidemic of Staphylococcus-negative infections involving anterior cruciate ligament reconstruction with salvage of the graft and function

We performed a retrospective study of 13 patients who had postoperative clinical and laboratory signs of infection after autogenous bone-patellar tendon-bone (BPTB) anterior cruciate ligament (ACL) reconstructions. From January 1991 to November 1996 we experienced only 2 infected knees in 1,300 reconstructions, but between December 1996 and February 1997 10 patients in 70 ACL reconstructions developed a postoperative suspected infection. We found the origin of contamination (coagulase-negative Staphylococcus) in the supposedly sterile inflow cannula. When we changed this device, we had only 1 infection in the next 400 reconstructions. The diagnosis in these cases was derived from clinical signs and laboratory results, but only 2 of 11 samples of aspirated synovial fluid tested positive for Staphylococcus. The mean interval between the surgery and the onset of signs of infection and the start of antibiotic therapy was 7.7 days. All the patients had antibiotic association at the highest level. Six knees underwent arthroscopic debridement when the clinical signs indicated resistence to antibiotics. The normal postoperative rehabilitation program was modified but was not discontinued. Although recovery time was longer, overall results were similar to uncomplicated reconstructions. On the basis of our experience, we believe that when there is a notable increase in infection rates, a thorough search for contamination is indicated. Our source of infection was material that was thought to be sterile. Ultimately, early diagnosis and treatment is of critical importance to obtain good results. Even suspicion of infective postoperative complication should be sufficient cause to search for responsible microorganisms and begin antibiotic therapy. Arthroscopic debridement should be proposed to patients with resistence to antibiotics.

Intra-articular ACL reconstruction in the over-40-year-old patient

We compared two groups of patients who had undergone anterior cruciate ligament (ACL) reconstruction. The groups were similar in regard to sex distribution, index injury, absence of meniscal or chondral lesions, surgical technique, and postoperative rehabilitation programs, but different in age. In the study group the mean age was 42.6 years, while in the control group the mean age was 20 years. The clinical results were assessed at a mean of 29 months after surgery using the Lysholm score, International Knee Documentation Committee form, Tegner activity level, and the KT-1000 arthrometer test. No significant differences were reported. Standard X-ray studies showed no variation between the two groups in the postoperative period. Intra-articular ACL reconstruction using a bone-patellar tendon-bone graft can be recommended in selected patients over 40 years of age as an alternative to conservative treatment.

Three cases of patella fracture in 1,320 anterior cruciate ligament reconstructions with bone-patellar tendon-bone autograft

Between September 1992 and December 1996 we reviewed three transverse displaced fractures of the patella occuring in 1,320 ACL reconstructions using bone-patellar tendon-bone autograft. All the patients suffered local injury to the donor knee between 8 and 12 weeks postoperatively. Immediate rigid fixation using single or double anterior tension band allowed early mobilization and full weight bearing. Between 6 and 9 months after fracture, the screws and the wire were removed and the grafts tested. Results of the pivot shift and Lachman test under anesthesia were negative and arthroscopic visualisation showed the graft to be intact. Postoperative assessment included the Lysholm and Tegner scales, the International Knee Documentation Committee Evaluation form (IKDC), KT-1000 arthrometer, and isokinetic dynamometer strength testing. No significant differences in the final outcome were noted between reconstructions complicated by patellar fracture and normal ACL reconstructions.

Preoperative and postoperative evaluation of prostate-specific antigen in localized prostatic cancer treated by radical prostatectomy

Preoperative prostate-specific antigen (PSA) values were determined in 73 patients with clinically localized prostatic cancer and candidates for a radical procedure. Correlation of preoperative PSA with a final pathological stage was attempted. Only in 44.8% of our 22 patients with organ-confined disease was the PSA value within the normal range; in 17.3% of cases PSA values were higher than 20 ng/ml. 18.2% of the patients with locally advanced disease showed normal PSA values, while 45.5% had concentrations above 20 ng/ml. In the case of lymph node involvement, PSA values were normal in 22.7% of the cases. Our data indicate that no strict relationship can be suggested between PSA and the final pathological stage and grading of the tumor in patients who underwent radical prostatectomy.

Signal averaging of pre- and post-extrasystolic beats in patients with ventricular arrhythmias

To evaluate the effects of premature ventricular beats on the impulse conduction of adjacent sinus cycles, we compared the high amplification signal-averaged electrocardiogram parameters of the pre- and post-extrasystolic beats with those of the remaining sinus cycle. According to the duration of filtered QRS (fQRS), to the voltage of root mean square of the terminal 40 ms (RMS 40) and to the duration of low amplitude terminal components of the sinus cycles, ventricular late potentials were detected in nine out of 29 subjects. Patients with an abnormal signal-averaged electrocardiogram exhibited a longer fQRS (146 +/- 6 versus 116 +/- 2 ms), a reduced RMS40 voltage (18 +/- 2 versus 80 +/- 10 microV) and a prolonged duration of less than 40 microV components (42 +/- 4 versus 17 +/- 2 ms). Analysis of the pre-extrasystolic beats did not reveal any significant variation in the above parameters, showing a mean difference of 0.44 +/- 2.4 ms; 0.02 +/- 1.14 microV; 1 +/- 1.9 ms and of -1.45 +/- 1.02 ms; 3.5 +/- 8.6 microV; -0.7 +/- 0.84 ms respectively, for patients with and without ventricular late potentials. In addition, no significant variation was observed when the post-extrasystolic beats were considered. These results indicate that the sinus cycles adjacent to premature ventricular discharges do not present variations of signal-averaged electrocardiogram parameters that may suggest an influence of the ectopic beats on their intramyocardial impulse propagation.

Children's understanding of death according to parents and pediatricians

Thirty pediatricians and 30 parents were interviewed on (a) how and when children develop concepts about death, (b) children's emotional responses to the thought of death, (c) the possibility of dialogue between adults and children about death, and (d) differences in healthy and seriously ill children's conceptualization of death. Pediatricians were no different than parents in their opinions. Moreover, in some cases, less educated parents and older doctors tended to hold opinions that were even farther from reality. Overall, the results suggest that children, healthy or sick, are left alone with the problem of death and are not helped either by their parents or by their doctors.