Incisional atrial reentrant tachycardia: experimental study on the conduction property through the isthmus

AbstractBackgroundIncisional atrial reentrant tachycardia is a life-threatening tachyarrhythmia after surgery for congenital heart disease. Slow conduction through an isthmus between anatomical barriers, such as a right atriotomy or the sites for cannulation, has been shown to be a prerequisite for perpetuation of the incisional atrial reentrant tachycardia. However, the conduction property through the isthmus has not been examined in detail.MethodsTo examine the conduction property, 2 tandem incisions were made on the lateral right atrium with various distances (3 to 20 mm) between the incisions in 16 canines. Four weeks after the surgery, the lateral right atrium was mapped epicardially during pacing to examine the conduction property through the isthmus. The conduction property was characterized by approximated curves of the conduction velocity through the isthmus in accordance with the pacing cycle lengths. The atrial tissue at the isthmus was examined microscopically.ResultsThe approximated curves of the conduction velocity were classified into 3 different types. Decremental conduction was observed only in the isthmi between 5 and 15 mm in width. A small amount of surviving myocardium between the scars formed the critical isthmus microscopically (decremental type). In the isthmi wider than 15 mm in width, slow conduction was not seen at any paced cycle length (nondecremental type). In the extremely narrow isthmi less than 5 mm in width, all of the atrial myocardium at the isthmus was replaced by fibrous tissue. Conduction was blocked at the isthmus and the activation detoured around the incisions (block type). There was a statistically significant difference in the approximated curves between the 3 different types of conduction properties (P < .01).ConclusionThe width of the isthmus determines the conduction property through the isthmus that contributes to the development of the incisional atrial reentrant tachycardia. Thus, the incisional atrial reentrant tachycardia may be preventable by leaving a sufficient amount of surviving myocardium between the incisions or by connecting the incisions by an ablative procedure

Contactless mass transfer for intra-droplet extraction

This study demonstrates the possibility of “contactless” mass transfer between two aqueous slugs (droplets) separated by an oil slug in Taylor flow inside milli-channels. Separation of the alternating aqueous slugs at the outlet was performed by switching a couple of solenoid valves at branched outlets according to signals obtained by an optical sensor at the branch. Transfer of bromothymol blue (BTB) from acidic to basic aqueous slugs was performed for demonstration. In some cases, aqueous slugs separated by oil, merged catching on each other due to the velocity difference. Interfacial tension which was affected by the solute concentration was responsible for the velocity difference. Position-specific mass transfer activity at the rear end of the aqueous slugs was found on the course of the experiment. A meandering channel decreased the velocity difference and enhanced mass transfer. Almost complete (93%) transfer of BTB was achieved within a short residence time of several minutes under optimized conditions. The presented system opens a way for advanced separation using minimum amounts of the oil phase and allows concentrating the solute by altering relative lengths of the sender and receiver slugs

Predictors of cognitive function in patients with hypothalamic hamartoma following stereotactic radiofrequency thermocoagulation surgery

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138275/1/epi13838.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138275/2/epi13838_am.pd

Suppression of cell migration by phospholipase C-related catalytically inactive protein-dependent modulation of PI3K signalling

The metabolic processes of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] into PI(3,4,5)P3 and the subsequent PI(3,4,5)P3 signalling are involved in cell migration. Dysfunctions in the control of this pathway can cause human cancer cell migration and metastatic growth. Here we investigated whether phospholipase C-related catalytically inactive protein (PRIP), a PI(4,5)P2-binding protein, regulates cancer cell migration. PRIP overexpression in MCF-7 and BT-549 human breast cancer cells inhibited cell migration in vitro and metastasis development in vivo. Overexpression of the PRIP pleckstrin homology domain, a PI(4,5)P2 binding motif, in MCF-7 cells caused significant suppression of cell migration. Consistent with these results, in comparison with wild-type cells, Prip-deficient mouse embryonic fibroblasts exhibited increased cell migration, and this was significantly attenuated upon transfection with a siRNA targeting p110α, a catalytic subunit of class I phosphoinositide 3-kinases (PI3Ks). PI(3,4,5)P3 production was decreased in Prip-overexpressing MCF-7 and BT-549 cells. PI3K binding to PI(4,5)P2 was significantly inhibited by recombinant PRIP in vitro, and thus the activity of PI3K was downregulated. Collectively, PRIP regulates the production of PI(3,4,5)P3 from PI(4,5)P2 by PI3K, and the suppressor activity of PRIP in PI(4,5)P2 metabolism regulates the tumour migration, suggesting PRIP as a promising target for protection against metastatic progression.This work was supported by grants from JSPS KAKENHI Grant Numbers JP15K20372, JP17K11644, JP16K11503

Risk of higher dose methotrexate for renal impairment in patients with rheumatoid arthritis

Renal impairment is a major concern in patients taking high-dose methotrexate (MTX) for malignancy, but it has not been fully explored in rheumatoid arthritis (RA) patients taking low-dose MTX. This study aimed to elucidate the dose-dependent effects of MTX on the renal function of patients with RA. We retrospectively reviewed 502 consecutive RA patients who were prescribed MTX for >= 1 year at Okayama University Hospital between 2006 and 2018. The primary outcome was the change in estimated glomerular filtration rate (eGFR) over 1 year. The association between MTX dosage (= 12 mg/week) and the change in eGFR was evaluated using multiple linear regression analysis with adjustment for possible confounding factors including age, sex, disease duration, body weight, comorbidity, baseline eGFR, concomitant treatment, and disease activity. Mean patient age was 63 years; 394 (78%) were female. Median disease duration was 77 months, while mean MTX dosage was 8.6 mg/week. The last 1-year change of eGFR (mean +/- SD) in patients treated with MTX= 12 mg/week (n=97) decreased by 0.2 +/- 7.3, 0.6 +/- 8.6, and 4.5 +/- 7.9 mL/min/1.73 m(2)/year, respectively (p= 12 mg/week was still correlated with a decrease in 1-year eGFR (beta-coefficient:-2.5; 95% confidence interval,-4.3 to-0.6; p=0.0089) in contrast to MTX 8-12 mg/week. Careful monitoring of renal function is required in patients with MTX >= 12 mg/week over the course of RA treatment regardless of disease duration