Non-Invasive Identification of Atrial Fibrillation Driver Location Using the 12-lead ECG: Pulmonary Vein Rotors vs. other Locations.

Atrial fibrillation (AF) is an irregular heart rhythm due to disorganized atrial electrical activity, often sustained by rotational drivers called rotors. In the present work, we sought to characterize and discriminate whether simulated single stable rotors are located in the pulmonary veins (PVs) or not, only by using non-invasive signals (i.e., the 12-lead ECG). Several features have been extracted from the signals, such as Hjort descriptors, recurrence quantification analysis (RQA), and principal component analysis. All the extracted features have shown significant discriminatory power, with particular emphasis to the RQA parameters. A decision tree classifier achieved 98.48% accuracy, 83.33% sensitivity, and 100% specificity on simulated data.Clinical Relevance-This study might guide ablation procedures, suggesting doctors to proceed directly in some patients with a pulmonary veins isolation, and avoiding the prior use of an invasive atrial mapping system.

Automated cortical thickness and skewness feature selection in bipolar disorder using a semi-supervised learning method.

BACKGROUND: Bipolar disorder (BD) broadly affects brain structure, in particular areas involved in emotion processing and cognition. In the last years, the psychiatric field's interest in machine learning approaches has been steadily growing, thanks to the potentiality of automatically discriminating patients from healthy controls. METHODS: In this work, we employed cortical thickness of 58 regions of interest obtained from magnetic resonance imaging scans of 41 BD patients and 34 healthy controls, to automatically identify the regions which are mostly involved with the disease. We used a semi-supervised method, addressing the criticisms on supervised methods, related to the fact that the diagnosis is not unaffected by uncertainty. RESULTS: Our results confirm findings in previous studies, with a classification accuracy of about 75% when mean thickness and skewness of up to five regions are considered. We obtained that the parietal lobe and some areas in the temporal sulcus were the regions which were the most involved with BD. LIMITATIONS: The major limitation of our work is the limited size or our dataset, but in line with other recent machine learning works in the field. Moreover, we considered chronic patients, whose brain characteristics may thus be affected. CONCLUSIONS: The automatic selection of the brain regions most involved in BD may be of great importance when dealing with the pathogenesis of the disorder. Our method selected regions which are known to be involved with BD, indicating that damage to the identified areas can be considered as a marker of disease.

Probing the mechanism for hydrogel-based stasis induction in human pluripotent stem cells: is the chemical functionality of the hydrogel important?

It is well-known that pluripotent human embryonic stem cells (hPSC) can differentiate into any cell type. Recently, we reported that hPSC colonies enter stasis when immersed in an extremely soft hydrogel comprising hydroxyl-functional block copolymer worms (I. Canton, N. J. Warren, A. Chahal, K. Amps, A. Wood, R. Weightman, E. Wang, H. Moore and S. P. Armes, ACS Centr. Sci., 2016, 2, 65-74). The gel modulus and chemical structure of this synthetic hydrogel are similar to that of natural mucins, which are implicated in the mechanism of diapause for mammalian embryos. Does stasis induction occur merely because of the very soft nature of such hydrogels or does chemical functionality also play a role? Herein, we address this key question by designing a new hydrogel of comparable softness in which the PGMA stabilizer chains are replaced with non-hydroxylated poly(ethylene glycol) [PEG]. Immunolabeling studies confirm that hPSC colonies immersed in such PEG-based hydrogels do not enter stasis but instead proliferate (and differentiate if no adhesion substrate is present). However, pluripotency is retained if an appropriate adhesion substrate is provided. Thus, the chemical functionality of the hydrogel clearly plays a decisive role in the stasis induction mechanism.

Brain sparing effect in growth-restricted fetuses is associated with decreased cardiac acceleration and deceleration capacities: a case-control study.

OBJECTIVE: Phase rectified signal averaging (PRSA) is a new method of fetal heart rate variability (fHRV) analysis that quantifies the average acceleration (AC) and deceleration capacity (DC) of the heart. The aim of this study was to evaluate AC and DC of fHR [recorded by trans-abdominal fetal electrocardiogram (ta-fECG)] in relation to Doppler velocimetry characteristics of intrauterine growth restriction (IUGR). DESIGN: Prospective case-control study. SETTING: Single third referral centre. POPULATION: IUGR (n = 66) between 25 and 40 gestational weeks and uncomplicated pregnancies (n = 79). METHODS: In IUGR the nearest ta-fECG monitoring to delivery was used for PRSA analysis and Doppler velocimetry parameters obtained within 48 hours. AC and DC were computed at s = T = 9. The relation was evaluated between either AC or DC and Doppler velocimetry parameters adjusting for gestational age at monitoring, as well as the association between either AC or DC and IUGR with or without brain sparing. RESULTS: In IUGRs there was a significant association between either AC and DC and middle cerebral artery pulsatility index (PI; P = 0.01; P = 0.005), but the same was not true for uterine or umbilical artery PI (P > 0.05). Both IUGR fetuses with and without brain sparing had lower AC and DC than controls, but this association was stronger for IUGRs with brain sparing. CONCLUSIONS: Our study observed for the first time that AC and DC at PRSA analysis are associated with middle cerebral artery PI, but not with uterine or umbilical artery PI, and that there is a significant decrease of AC and DC in association with brain sparing in IUGR fetuses from 25 weeks of gestation to term. TWEETABLE ABSTRACT: Brain sparing in IUGR fetuses is associated with decreased acceleration and deceleration capacities of the heart.

Quantification of ventricular repolarization heterogeneity during moxifloxacin or sotalol administration using [Formula: see text]-index.

Drug-induced alterations of ventricular heterogeneity must be limited to avoid induction of lethal ventricular arrhythmias. In here, a new parameter called [Formula: see text]-index, able to measure the standard deviation of myocites' repolarization times, was evaluated after moxifloxacin and sotalol administration. The two drugs are known to provide different alteration of the QT interval length ranging from subtle (moxifloxacin) to evident (sotalol). In fact, while the former is employed as active-comparator in thorough QT studies, the latter might induce torsades de pointes. 24 h Holter ECGs of 39 (sotalol) and 68 (moxifloxacin) healthy subjects were retrospectively analyzed. The recordings were performed after infusion of the drugs and after the placebo (moxifloxacin) or at baseline (sotalol). The corrected QT interval (QTc) was included as well in the study, for a direct comparison. In both populations, [Formula: see text]-index and QTc increased along with the drugs' serum concentration and were statistically different from values in the placebo arm or at baseline (p < 0.05).With sotalol, the maximum value of [Formula: see text]-index occurred, on average, after 5.64 h from the infusion, whereas for QTc after about 4.27 h. The two metrics displayed evident changes ([Formula: see text]-index: 27.79 ms ± 4.89 ms versus 60.13 ms ± 18.52 ms; QT corrected: 387.07 ms ± 19.84 ms versus 437.76 ± 32.05 ms; p < 0.05). Regarding moxifloxacin, maximum values were reached, on average, 5.01 h after administration for [Formula: see text]-index (30.70 ms ± 8.32 ms versus 40.48 ms ± 7.61 ms; p < 0.05), and 4.37 h for QTc (404.29 ms ± 29.05 ms versus 426.77 ± 36.67 ms; p < 0.05). They were statistically different from baseline values. With both drugs, the maximal percent variation after administration was higher for [Formula: see text]-index than QTc (moxifloxacin: 34.56% ± 24.60% versus 5.56% ± 2.98% ; sotalol: 114.77% ± 33.15% versus 12.13% ± 2.85% ; p < 0.05).The study suggests that the standard deviation of the ventricular repolarization times, as quantified by the [Formula: see text]-index, might be an effective measure of spatial heterogeneity.

Spatial repolarization heterogeneity and survival in Chagas disease.

OBJECTIVES: We investigated if cardiac spatial repolarization heterogeneity might be associated with an increased risk of death in patients with chronic Chagas disease. METHODS: Repolarization heterogeneity was assessed using the V-index, a recently introduced metric founded on a biophysical model of the ECG. This metric provides an estimate of the standard deviation of the repolarization times across the heart. We analyzed 113 patients (aged 21- 67 years) enrolled between 1998 and 1999 who had a known serological status showing positive reactions to Trypanosoma cruzi. Fourteen subjects died during a 10-year follow-up period. RESULTS: The V-index was significantly lower in survivor (S) than in non-survivor (NS) subjects (S: 31.2 ± 13.3 ms vs NS: 41.2 ± 18.6 ms, single-tail t-test: p = 0.009, single-tail Wilcoxon rank sum test: p = 0.029). A V-index larger than 36.3 ms was related to a significantly higher risk of death in a univariate Cox proportional-hazards analysis (hazard ratio, HR = 5.34, p = 0.0046). In addition, V-index > 36.3 ms retained its prognostic value in a multivariate Cox proportional-hazards analysis after adjustment for other three clinical variables (left ventricular ejection factor < 0.50, QRS duration > 133 ms, ventricular tachycardia during stress testing or 24 hours Holter) and for T-wave amplitude variability > 30 µV, even using shrinkage, a statistical procedure that protects against over-fitting due to small sample size. CONCLUSIONS: The study showed that an increased dispersion of repolarization times in patients with Chagas disease, as measured by the V-index, is significantly correlated with the risk of death in a univariate survival analysis. The V-index captures prognostic information not immediately available from the analysis of other established risk factors.

Epidemiological study (2006-2012) on the poisoning of small animals by human and veterinary drugs.

A retrospective study was conducted on the exposure of dogs and cats to drugs, reported to the Poison Control Centre of Milan (Centro Antiveleni di Milano (CAV)) between January 2006 and December 2012. Calls related to drugs for human use and veterinary drugs accounted for 23.7 per cent of total inquiries (1415) received by CAV and mostly involved dogs (70 per cent of enquiries). Exposure to drugs for human use accounted for 79 per cent of cases involving dogs, whereas veterinary drugs were the main culprit (77 per cent) in the case of cats. The most common class of drugs for human use proved to be CNS drugs (26.8 per cent), followed by NSAIDs (19.6 per cent) and cardiovascular and endocrine drugs (12.9 per cent each). The majority of calls (95.2 per cent) related to veterinary drugs involved dogs and cats exposed to parasiticides. The outcome was reported in only 58.2 per cent of cases, and fatal poisoning accounted for 8.7 per cent of these cases. Epidemiological data from this Italian survey provide useful information on animal exposure to drugs. The knowledge of agents involved in poisoning episodes can help veterinarians make the correct diagnosis and institute preventive measures to possibly reduce animal exposure to drugs.

Plant poisoning in domestic animals: epidemiological data from an Italian survey (2000-2011).

An Italian epidemiological study based on the human Poison Control Centre of Milan (Centro Antiveleni di Milano (CAV)) data related to domestic animal poisoning by exposure to plants, was carried out in collaboration with the Veterinary Toxicology Section of the University of Milan. It encompasses a 12-year period, from the beginning of 2000 to the end of 2011. Calls related to toxic plants accounted for 5.7 per cent of total inquiries (2150) received by CAV. The dog was the most commonly poisoned species (61.8 per cent of calls) followed by the cat (26 per cent). Little information was recorded for other species. Most exposures (73.8 per cent) resulted in mild to moderate clinical signs. The outcome was reported in only 53.7 per cent of cases, and fatal poisoning accounted for 10.6 per cent of these cases. Glycoside, alkaloid, oxalate, toxalbumin, saponin, terpene and terpenoid-containing plants were recorded and found to be responsible for intoxication. Cycas revoluta, Euphorbia pulcherrima, Hydrangea macrophylla, Nerium oleander, Rhododendron species and Prunus species were the plants most frequently involved. Epidemiological data from this Italian survey provide useful information on animal exposure to plants and confirm the importance of plants as causative agents of animal poisoning.

Animal poisoning in Italy: 10 years of epidemiological data from the Poison Control Centre of Milan.

From 2000 to 2010, the Poison Control Centre of Milan (CAV), in collaboration with the University of Milan, Faculty of Veterinary Medicine, Department of Veterinary Sciences and Technologies for Food Safety, Toxicology Section, collected epidemiological information related to animal poisoning and classified it in an organised and computerised data bank. Data recorded were predominantly related to small animals and to some extent to horses, ruminants and other food-production animals. Few calls were registered involving exotics and no information was recorded on wildlife. The dog was reported to be the most common species involved in animal poisoning, and pesticides constituted the primary group of toxicants. In the case of pets, 'drugs' including veterinary parasiticide and drugs for human use constituted the second class of toxicants responsible for poisoning followed by household products, plants, zootoxins and metals. With regard to horses and farm animals, the second group consisted of phytotoxins, even if only episodically. In Italy, published data on this subject are scarce but this information is crucial for better management of the poisoning of domestic animals in an effort to reduce mortality.

A model for mammalian cochlear hair cell differentiation in vitro: effects of retinoic acid on cytoskeletal proteins and potassium conductances.

We have established a model for the in-vitro differentiation of mouse cochlear hair cells and have used it to explore the influence of retinoic acid on proliferation, cytoskeletal proteins and voltage-gated potassium conductances. The model is based on the conditionally immortal cell line University of Sheffield/ventral otocyst-epithelial cell line clone 36 (US/VOT-E36), derived from ventral otic epithelial cells of the mouse at embryonic day 10.5 and transfected with a reporter for myosin VIIa. Retinoic acid did not increase cell proliferation but led to up-regulation of myosin VIIa and formation of prominent actin rings that gave rise to numerous large, linear actin bundles. Cells expressing myosin VIIa had larger potassium conductances and did not express the cyclin-dependent kinase inhibitor p27(kip1). US/VOT-E36 endogenously expressed the voltage-gated potassium channel alpha-subunits Kv1.3 and Kv2.1, which we subsequently identified in embryonic and neonatal hair cells in both auditory and vestibular sensory epithelia in vivo. These subunits could underlie the embryonic and neonatal delayed-rectifiers recorded in nascent hair cells in vivo. Kv2.1 was particularly prominent on the basolateral membrane of cochlear inner hair cells. Kv1.3 was distributed throughout all hair cells but tended to be localized to the cuticular plates. US/VOT-E36 recapitulates a coherent pattern of cell differentiation under the influence of retinoic acid and will provide a convenient model for screening the effects of other extrinsic factors on the differentiation of cochlear epithelial cell types in vitro.

Differentiation of an auditory neuronal cell line suitable for cell transplantation.

The auditory neuroblast cell line US/VOT-N33 (N33), which is conditionally immortal, was studied as an in vitro model for the differentiation of spiral ganglion neurons (SGNs) and as a candidate for cell transplantation in rodents. It expresses numerous molecular markers characteristic of auditory neuroblasts, including the transcription factors GATA3, NeuroD, Brn3a and Islet1, as well as the neuronal cytoskeletal protein beta3-tubulin. It displays active migratory behaviour in vitro and in vivo. In the presence of the fibroblast growth factors FGF1 or FGF2 it differentiates bipolar morphologies similar to those of native SGNs. In coculture with neonatal cochlear tissue it is repelled from epithelial surfaces but not from native SGNs, alongside which it extends parallel neuronal processes. When injected into the retina in vivo, EGFP-labelled N33 cells were traced for 1-2 weeks and migrated rapidly within the subretinal space. Cells that found their way into the retinal ganglion cell layer extended multiple processes but did not express beta3-tubulin. The ability of N33 to migrate, to differentiate, to localize with native SGNs in vitro and to survive in vivo suggests that they provide an effective model for SGN differentiation and for cell transplantation into the ear.

Ventral otic cell lines as developmental models of auditory epithelial and neural precursors.

Conditionally immortal cell lines were established from the ventral otocyst of the Immortomouse at embryonic day 10.5 and selected to represent precursors of auditory sensory neural and epithelial cells. Selection was based upon dissection, tissue-specific markers, and expression of the transcription factor GATA3. Two cell lines expressed GATA3 but possessed intrinsically different genetic programs under differentiating conditions. US/VOT-E36 represented epithelial progenitors with potential to differentiate into sensory and nonsensory epithelial cells. US/VOT-N33 represented migrating neuroblasts. Under differentiating conditions in vitro the cell lines expressed very different gene expression profiles. Expression of several cell- and tissue-specific markers, including the transcription factors Pax2, GATA3, and NeuroD, differed between the cell lines in a pattern consistent with that observed between their counterparts in vivo. We suggest that these and other conditionally immortal cell lines can be used to study transient events in development against different backgrounds of cell competence.

Notch signaling and the emergence of auditory hair cells.

OBJECTIVE: Recent insights into the mechanisms that determine a hair cell's fate have emerged from studies on invertebrate sensory organs and the avian inner ear. These mechanisms have important implications for our understanding of the possible therapeutic management of sensorineural deafness. This article reviews the current state of our knowledge regarding mammalian auditory hair cell fate specification. DESIGN: Data were obtained from the MEDLINE database and data presented at the Molecular Biology of Hearing and Deafness Meeting (Bethesda, Md, October 1998). Articles reporting information about cell fate specification and Notch and its ligands were selected. MAIN OUTCOME MEASURES: Data pertaining to cell fate mechanisms, Notch and its ligands, and application to hearing were extracted. RESULTS: The Notch/ligand mechanism is responsible for the specification of the hair cell phenotype. CONCLUSIONS: Major progress has been made in understanding this fundamental process, and its application to hair cell determination is only now being realized. Possible applications could involve the "switching" of supporting cells to hair cells, thus replenishing those hair cells damaged in sensorineural hearing loss.

Calcium signalling mediated by the 9 acetylcholine receptor in a cochlear cell line from the immortomouse.

1. We have investigated the characteristics of the alpha9 acetylcholine receptor (alpha9AChR) expressed in hair cell precursors in an immortalized cell line UB/OC-2 developed from the organ of Corti of the transgenic H-2Kb-tsA58 mouse (the Immortomouse) using both calcium imaging and whole-cell recording. 2. Ratiometric measurements of fura-2 fluorescence revealed an increase of intracellular calcium concentration in cells when challenged with 10 microM ACh. The calcium increase was seen in 66 % of the cells grown at 39 degrees C in differentiated conditions. A sm aller fraction (34%) of cells grown at 33 degrees C in proliferative con ditions responded. 3. Caffeine (10mM) elevated cell calcium. In the ab sence of caffeine, the majority of imaged cells responded only once to A Ch presentations. Pretreatment with caffeine ingibited all calcium respo nses to ACh. 4. In whole-cell tight-seal recordings 10 microM ACh activa ted inward current was dependent on the extracellular calcium concentrat ion with an estimated PCa/PNa of 80 for the alpha9 receptor at physiological calcium levels. 5 . The data indicate that ACh activates a calcium-permeable channel alpha 9AChR in UB/OC-2 cells and that the channel has a significantly higher c alcium permeability than other AChRs. The results indicate that the alp ha9AChR may be able to elevate intracellular calcium levels in hair cell s both directly and via store release.

Identification of differentiating cochlear hair cells in vitro.

HYPOTHESIS: The expression of hair cell-specific genes involved in differentiation was studied in the cell line UB/OC-1 (University Bristol/Organ of Corti). BACKGROUND: Studies of gene expression in cochlear hair cells are restricted by the small number of cells available and by their experimental inaccessibility. The cell line was derived from the H2K(b)tsA58 transgenic mouse, which harbors a conditionally expressed immortalizing gene. Two genes that are characteristic of hair cells were upregulated during differentiation of UB/OC-1 cells in vitro. They are the transcription factor Brn3.1, which is essential for hair cell differentiation, and the alpha9 subunit of the nicotinic acetylcholine receptor that is involved in olivocochlear efferent innervation. METHODS: The expression of Brn3.1 and alpha9, at different time points under differentiating conditions, was analyzed by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR). Western blot analysis and immunofluorescence analysis were performed on the cell line with anti-Brn3.1 antibody. RESULTS: Reaction products for alpha9 were detected after 3 to 6 days under differentiating conditions. Low levels of Brn3.1 were detectable under proliferating conditions and increased under differentiating conditions. All cells expressed Brn3.1 under differentiating conditions. This temporal pattern of gene expression is very closely similar to that found in vivo. CONCLUSION: The cochlear hair cell line UB/OC-1 provides a valuable experimental system because it conditionally expresses genes essential for normal differentiation and electrophysiology. It should prove valuable in the identification and characterization of genes involved in development and may provide material for screening new therapeutic methods of stimulating recovery and regeneration of hair cells.

Differentiation of mammalian vestibular hair cells from conditionally immortal, postnatal supporting cells.

We provide evidence from a newly established, conditionally immortal cell line (UB/UE-1) that vestibular supporting cells from the mammalian inner ear can differentiate postnatally into more than one variant of hair cell. A clonal supporting cell line was established from pure utricular sensory epithelia of H2k(b)tsA58 transgenic mice 2 d after birth. Cell proliferation was dependent on conditional expression of the immortalizing gene, the "T" antigen from the SV40 virus. Proliferating cells expressed cytokeratins, and patch-clamp recordings revealed that they all expressed small membrane currents with little time-dependence. They stopped dividing within 2 d of being transferred to differentiating conditions, and within a week they formed three defined populations expressing membrane currents characteristic of supporting cells and two kinds of neonatal hair cell. The cells expressed several characteristic features of normal hair cells, including the transcription factor Brn3.1, a functional acetylcholine receptor composed of alpha9 subunits, and the cytoskeletal proteins myosin VI, myosin VIIa, and fimbrin. Immunofluorescence labeling and electron microscopy showed that the cells formed complex cytoskeletal arrays on their upper surfaces with structural features resembling those at the apices of normal hair cells. The cell line UB/UE-1 provides a valuable in vitro preparation in which the expression of numerous structural and physiological components can be initiated or upregulated during early stages of mammalian hair cell commitment and differentiation.