Catheter ablation in patients with multiple and unstable ventricular tachycardias after myocardial infarction: short ablation lines guided by reentry circuit isthmuses and sinus rhythm mapping

BACKGROUND

Extensive lines of radiofrequency (RF) lesions through infarct (MI) can ablate multiple and unstable ventricular tachycardias (VTs). Methods for guiding ablation that minimize unnecessary RF applications are needed. This study assesses the feasibility of guiding RF line placement by mapping to identify a reentry circuit isthmus.

METHODS AND RESULTS

Catheter mapping and ablation were performed in 40 patients (MI location: inferior, 28; anterior, 7; and both, 5) with an electroanatomic mapping system to measure the infarct region and ablation lines. The initial line was placed in the MI region either through a circuit isthmus identified from entrainment mapping or a target identified from pace mapping. A total of 143 VTs (42 stable, 101 unstable) were induced. An isthmus was identified in 25 patients (63%; 5 with only stable VTs, 5 with only unstable VTs, and 15 with both VTs). Inducible VTs were abolished or modified in 100% of patients when the RF line included an isthmus compared with 53% when RF had to be guided by pace mapping (P=0.0002); those with an isthmus identified received shorter ablation lines (4.9+/-2.4 versus 7.4+/-4.3 cm total length, P=0.02). During follow-up, spontaneous VT decreased markedly regardless of whether an isthmus was identified. VT stability and number of morphologies did not influence outcome.

CONCLUSIONS

A 4- to 5-cm line of RF lesions abolishes all inducible VTs in more than 50% of patients. Less ablation is required if a reentry circuit isthmus is identified even when multiple and unstable VTs are present.

GDF10 is a signal for axonal sprouting and functional recovery after stroke

Stroke produces a limited process of neural repair. Axonal sprouting in cortex adjacent to the infarct is part of this recovery process, but the signal that initiates axonal sprouting is not known. Growth and differentiation factor 10 (GDF10) is induced in peri-infarct neurons in mice, non-human primates and humans. GDF10 promotes axonal outgrowth in vitro in mouse, rat and human neurons through TGFβRI and TGFβRII signaling. Using pharmacogenetic gain- and loss-of-function studies, we found that GDF10 produced axonal sprouting and enhanced functional recovery after stroke; knocking down GDF10 blocked axonal sprouting and reduced recovery. RNA sequencing from peri-infarct cortical neurons revealed that GDF10 downregulated PTEN, upregulated PI3 kinase signaling and induced specific axonal guidance molecules. Using unsupervised genome-wide association analysis of the GDF10 transcriptome, we found that it was not related to neurodevelopment, but may partially overlap with other CNS injury patterns. Thus, GDF10 is a stroke-induced signal for axonal sprouting and functional recovery.

Sleep disturbances in clinic patients with functional bowel disorders

OBJECTIVE

Sleep deprivation can lower visceral perception thresholds and nonregenerative sleep has been implicated as an etiological factor in chronic hyperalgesia syndromes. The aims of our study were to quantify the self-reported prevalence and type of sleep disturbances in patients with different functional bowel disorders (FBD) and to determine if this prevalence is related to involvement of the upper or lower gastrointestinal (GI) tract, perceived disease severity, or psychological comorbidity.

METHODS

We enrolled 505 new FBD patients from an academic referral center specializing in functional GI disorders and 247 community based healthy controls. All patients and controls were prospectively evaluated by validated bowel symptom and sleep questionnaires. A psychological profile was obtained by SCL-90R.

RESULTS

We found that 68% of functional dyspepsia (FD), 71.2% of irritable bowel syndrome (IBS)+FD, 50.2% of IBS, and 55.1% of the normal subjects reported having sleep disturbances. Waking up repeatedly during the night and waking up in the morning feeling tired or not rested were the most commonly reported sleep patterns; 57.2% of the patients reported that their abdominal ache awakened them from sleep during the night. Self-reported sleep disturbance was directly related to the perceived intensity of GI symptoms. Self-reported sleep disturbances were equally common in both male (57%) and female (58.4%) FBD patients. There was no significant difference between the mean anxiety and depression scores between patients with and without sleep dysfunction.

CONCLUSIONS

FD patients, but not IBS patients, reported sleep disturbances more frequently than healthy control subjects. Abdominal pain or discomfort that awaken FBD patients from sleep during the night were common, and thus a poor discriminating factor between organic and functional disorders.

Symptoms and visceral perception in patients with pain-predominant irritable bowel syndrome

OBJECTIVE

Abdominal pain is thought to be a hallmark of the irritable bowel syndrome (IBS), although currently used symptom criteria do not differentiate between abdominal pain and discomfort. By focusing on viscerosensory symptoms, we sought to determine: 1) which type of symptoms are most commonly reported by IBS patients, and 2) whether patients who report pain as their most bothersome symptom differ in clinical, psychological, and physiological characteristics.

METHODS

A total of 443 consecutive new patient referrals to a tertiary referral center for functional gastrointestinal disorders who met symptom criteria for IBS were given validated, psychometric, health status, and bowel symptom questionnaires containing specific questions regarding the patients' predominant viscerosensory gastrointestinal symptom. Of these patients, 155 (35%) also met criteria for functional dyspepsia. A representative subset of the total IBS patient population (n = 58) underwent evaluation of perceptual responses to controlled rectal distension before and after a noxious sigmoid conditioning stimulus.

RESULTS

Viscerosensory symptoms clustered into four groups: 1) abdominal pain, 2) bloating-type discomfort, 3) sensation of incomplete rectal evacuation, and 4) extraabdominal (chest pain or pressure and nausea). A total of 66% of patients reported gas as one of their viscerosensory symptoms, whereas 60% reported abdominal pain as one of their symptoms. Only 29% rated abdominal pain as their most bothersome symptom, whereas bloating-type symptoms were listed by 60% as most bothersome. Although pain predominance did not correlate with the severity of gastrointestinal or psychological symptoms, there was a significant correlation with the development of rectal hypersensitivity in response to the sigmoid conditioning stimulus.

CONCLUSIONS

In a tertiary referral population of IBS patients: 1) abdominal pain is reported by only one third of patients as their most bothersome viscerosensory symptoms; and 2) pain-predominance correlates with development of rectal hypersensitivity after a noxious sigmoid stimulus.

Epidemiological survey of oral submucous fibrosis and leukoplakia in aborigines of Taiwan

A population-based survey was designed to investigate the prevalence of areca/betel quid chewing, oral submucous fibrosis and leukoplakia in a typical aboriginal community of southern Taiwan. Three hundred and twelve people 20 years of age or older were collected in the study. The prevalence of chewing areca/betel quid was 69.5%, with an average of 17.3 portions a day for an average 24.4 years. More women (78.7%) than men (60.6%) chewed areca/betel quid. The prevalences of oral submucous fibrosis and leukoplakia were 17.6% and 24.4%, respectively. It was found that the odds ratio for chewing areca/betel quid and having at least one of the above oral mucosal lesions was 8.21. Any additional smoking or drinking habits were not significant for having oral mucosal lesions. Although the areca/betel quid in Taiwan does not contain any tobacco, a significant association was still identified between areca/betel quid chewing and oral mucosal lesions.

Verification data for electron beam dose algorithms

The Collaborative Working Group (CWG) of the National Cancer Institute (NCI) electron beam treatment planning contract has performed a set of 14 experiments that measured dose distributions for 28 unique beam-phantom configurations that simulated various patient anatomic structures and beam geometries. Multiple dose distributions were measured with film or diode detectors for each configuration, resulting in 78, 2-D planar dose distributions and one, 1-D depth-dose distribution. Measurements were made for 9- and 20-MeV electron beams, using primarily 6 x 6- and 15 x 15-cm applicators at several SSDs. Dose distributions were measured for shaped fields, irregular surfaces, and inhomogeneities (1-D, 2-D, and 3-D), which were designed to simulate many clinical electron treatments. The data were corrected for asymmetries, and normalized in an absolute manner. This set of measured data can be used for verification of electron beam dose algorithms and is available to others for that purpose.

Rapid detection of avian influenza H5N1 virus using impedance measurement of immuno-reaction coupled with RBC amplification

Avian influenza virus (AIV) subtype H5N1 was first discovered in the 1990 s and since then its emergence has become a likely source of a global pandemic and economic loss. Currently accepted gold standard methods of influenza detection, viral culture and rRT-PCR, are time consuming, expensive and require special training and laboratory facilities. A rapid, sensitive, and specific screening method is needed for in-field or bedside testing of AI virus to effectively implement quarantines and medications. Therefore, the objective of this study was to improve the specificity and sensitivity of an impedance biosensor that has been developed for the screening of AIV H5. Three major components of the developed biosensor are immunomagnetic nanoparticles for the separation of AI virus, a microfluidic chip for sample control and an interdigitated microelectrode for impedance measurement. In this study polyclonal antibody against N1 subtype was immobilized on the surface of the microelectrode to specifically bind AIV H5N1 to generate more specific impedance signal and chicken red blood cells (RBC) were used as biolabels to attach to AIV H5N1 captured on the microelectrode to amplify impedance signal. RBC amplification was shown to increase the impedance signal change by more than 100% compared to the protocol without RBC biolabels, and was necessary for forming a linear calibration curve for the biosensor. The use of a second antibody against N1 offered much greater specificity and reliability than the previous biosensor protocol. The biosensor was able to detect AIV H5N1 at concentrations down to 10(3) EID(50)ml(-1) in less than 2h.

An Impedance Aptasensor with Microfluidic Chips for Specific Detection of H5N1 Avian Influenza Virus

In this research a DNA aptamer, which was selected through SELEX (systematic evolution of ligands by exponential enrichment) to be specific against the H5N1 subtype of the avian influenza virus (AIV), was used as an alternative reagent to monoclonal antibodies in an impedance biosensor utilizing a microfluidics flow cell and an interdigitated microelectrode for the specific detection of H5N1 AIV. The gold surface of the interdigitated microelectrode embedded in a microfluidics flow cell was modified using streptavidin. The biotinylated aptamer against H5N1 was then immobilized on the electrode surface using biotin-streptavidin binding. The target virus was captured on the microelectrode surface, causing an increase in impedance magnitude. The aptasensor had a detection time of 30 min with a detection limit of 0.0128 hemagglutinin units (HAU). Scanning electron microscopy confirmed the binding of the target virus onto the electrode surface. The DNA aptamer was specific to H5N1 and had no cross-reaction to other subtypes of AIV (e.g., H1N1, H2N2, H7N2). The newly developed aptasensor offers a portable, rapid, low-cost alternative to current methods with the same sensitivity and specificity.

Fetal cerebral ventricular atrium: difference in size according to sex

PURPOSE

To determine whether the diameter of the fetal lateral ventricular atrium is larger in male than in female fetuses.

MATERIALS AND METHODS

The atrial diameter in 219 fetuses retrospectively identified from a consecutive group of healthy newborns was measured without knowledge of the subject's sex.

RESULTS

Atrial size demonstrated a near-normal distribution, with mean size for all subjects 6.1 mm +/- 1.3 (standard deviation). When separated by sex, the mean atrial diameter of 122 female fetuses was 5.8 mm +/- 1.3, and the mean atrial diameter of 97 male fetuses was 6.4 mm +/- 1.3. The difference in mean size is statistically significant (P < .005).

CONCLUSION

Male fetuses have a slightly larger atrial size than female fetuses. This discovery has implications for defining the upper limit of normal for fetal ventricular atrial size.

Efficient separation and sensitive detection of Listeria monocytogenes using an impedance immunosensor based on magnetic nanoparticles, a microfluidic chip, and an interdigitated microelectrode

Listeria monocytogenes continues to be a major foodborne pathogen that causes food poisoning, and sometimes death, among immunosuppressed people and abortion among pregnant women. In this study, magnetic nanoparticles with a diameter of 30 nm were functionalized with anti-L. monocytogenes antibodies via biotin-streptavidin bonds to become immunomagnetic nanoparticles (IMNPs) to capture L. monocytogenes in a sample during a 2-h immunoreaction. A magnetic separator was used to collect and hold the IMNPs-L. monocytogenes complex while the supernatants were removed. After the washing step, the nanoparticle-L. monocytogenes complex was separated from the sample and injected into a microfluidic chip. The impedance change caused by L. monocytogenes was measured by an impedance analyzer through the interdigitated microelectrode in the microfluidic chip. For L. monocytogenes in phosphate-buffered saline solution, up to 75% of the cells in the sample could be separated, and as few as three to five cells in the microfluidic chip could be detected, which is equivalent to 10(3) CFU/ml of cells in the original sample. The detection of L. monocytogenes was not interfered with by other major foodborne bacteria, including E. coli O157:H7, E. coli K-12, L. innocua, Salmonella Typhimurium, and Staphylococcus aureus. A linear correlation (R(2) = 0.86) was found between the impedance change and the number of L. monocytogenes in a range of 10(3) to 10(7) CFU/ml. Equivalent circuit analysis indicated that the impedance change was mainly due to the decrease in medium resistance when the IMNPs-L. monocytogenes complexes existed in mannitol solution. Finally, the immunosensor was evaluated with food sample tests; the results showed that, without preenrichment and labeling, 10(4) and 10(5) CFU/ml L. monocytogenes in lettuce, milk, and ground beef samples could be detected in 3 h.

Photoresponsive Graphene Composite Bilayer Actuator for Soft Robots

Highly deformable and photoresponsive smart actuators are attracting increasing attention. Here, a high concentration of graphene is dispersed in polydimethylsiloxane (PDMS) by combining the advantages of various dispersion methods. The composite and pure PDMS layers are used to fabricate bilayer actuators with a high capacity for rapid deformation. The fabricated bilayer actuators exhibit novel and interesting properties. A bilayer actuator containing a 30 wt % graphene composite can be deflected by 7.9 mm in the horizontal direction under infrared laser irradiation. The graphene concentration in the composite influences actuator adjustment to deformation and its response speed, and the composite also exhibits superhydrophobicity. On the basis of its superhydrophobicity and large deformation capacity, the actuator made with 30 wt % graphene composite is used to construct a beluga whale soft robot. The robot can swim quickly in water at an average speed of 6 mm/s, and it can cover a distance of 30 mm in 5 s when irradiated just once with an infrared laser. Actuators fabricated with this method can be used in artificial muscle, bionic grippers, and various soft robots that require actuators with large deformation capacities.

Evaluation study of a portable impedance biosensor for detection of avian influenza virus

Current methods for detection of avian influenza virus (AIV) based on virus culture and RT-PCR are well established, but they are either time consuming or require specialized laboratory facilities and highly trained technicians. A simple, rapid, robust, and reliable test, suitable for use in the field or at the patient's bedside, is urgently needed. In this study, the performance of a newly developed portable impedance biosensor was evaluated by comparison with real-time reverse transcriptase PCR (rRT-PCR) and virus culture for detection of AIV in tracheal and cloacal swab samples collected from experimentally H5N2 AIV infected chickens. The impedance biosensor system was based on a combination of magnetic nanobeads, which were coated with AIV subtype-specific antibody for capture (separation and concentration) of a target virus, and a microfluidic chip with an interdigitated array microelectrode for transfer and detection of target virus, and impedance measurement of the bio-nanobeads and AI virus complexes in a buffer solution. A comparison of results obtained from 59 swab samples using virus culture, impedance biosensor and rRT-PCR methods showed that the impedance biosensor technique was comparable in sensitivity and specificity to rRT-PCR. Detection time for the impedance biosensor is less than 1h.

Verification of radiosurgery target point alignment with an electronic portal imaging device (EPID)

A procedure has been developed using an electronic portal imaging device (EPID) to verify that the center of a patient's lesion is aligned with the center of a treatment cone prior to treatment in a linac-based stereotactic radiosurgery procedure. The coordinates of the lesion center are set on the Brown-Roberts-Wells phantom base using a target simulator. A 3 mm tungsten ball, mounted on the target simulator, is used as the reference point for the planned isocenter. The target simulator is then attached to an adapter mounted on the linac couch, and an EPID image of the simulated target is acquired. The center of the circular-shaped radiation field is calculated from the centroid of the segmented EPID image, and the center of the tungsten ball is identified by an automated computer search algorithm. A summation filter is used to find the position of the lowest radiation intensity coincident with the center of the ball. The alignment error is defined as the difference between the center of the radiation field and the center of the ball. The accuracy of this method was tested and found to be within 0.2 mm. The advantage of the EPID-based procedure is that it can give quantitative offset values quickly for immediate readjustment. We have found that the method is also a convenient tool for testing room laser alignment and the accuracy of the treatment cones.

Observation of vortex pinning in Bose-Einstein condensates

We report the observation of vortex pinning in rotating gaseous Bose-Einstein condensates. Vortices are pinned to columnar pinning sites created by a corotating optical lattice superimposed on the rotating Bose-Einstein condensates. We study the effects of two types of optical lattice: triangular and square. In both geometries we see an orientation locking between the vortex and the optical lattices. At sufficient intensity the square optical lattice induces a structural crossover in the vortex lattice.

Alterations in phospholipid N-methylation of cardiac subcellular membranes due to experimentally induced diabetes in rats

Phosphatidylethanolamine N-methylation was examined in cardiac subcellular membranes after inducing chronic experimental diabetes in rats (65 mg streptozotocin/kg, i.v.). The incorporation of radiolabeled methyl groups from S-adenosyl-L-methionine in diabetic sarcolemma was significantly depressed at all three catalytic sites (I, II, and III) of the methyltransferase system. An increase in methyl group incorporation was evident at site I without any changes at sites II and III in diabetic sarcoplasmic reticulum and mitochondria. Similar changes were also seen for the individual N-methylated lipids (monomethyl-, dimethylphosphatidylethanolamine, and phosphatidylcholine) specifically formed at each catalytic site in all cardiac membranes from diabetic animals. These alterations in N-methylation were reversible by a 14-d insulin therapy to the diabetic animals. In the presence of 10 microM ATP and 0.1 microM Ca2+, N-methylation was maximally activated at site I in both control and diabetic sarcolemma and sarcoplasmic reticulum, but not in mitochondria. Incubation of cardiac membranes with of S-adenosyl-L-methionine showed that Ca2(+)-stimulated ATPase activities in both sarcolemma and sarcoplasmic reticulum were augmented; however, the activation of diabetic sarcolemma was lesser and that of diabetic sarcoplasmic reticulum was greater in comparison with the control preparations. These results identify alterations in phosphatidylethanolamine N-methylation in subcellular membranes from diabetic heart, and it is suggested that these defects may be crucial in the development of cardiac dysfunction in chronic diabetes.

Multilobated B-cell lymphoma, a variant of centroblastic lymphoma. Report of four cases

Four cases of multilobated B-cell lymphoma, one follicular and three diffuse, are described. Many of the lymphoma cells show marked lobulation of the nuclei, and possess multiple prominent nucleoli. There are admixed classical centrocytes, classical centroblasts, and cells with morphology intermediate between classical centroblasts and multilobated cells. Multilobated cells are also observed in small numbers in germinal centres of lymph nodes showing reactive follicular hyperplasia. We believe that the multilobated B-cell may represent one form of centroblast during transition between the centroblastic and centrocytic stages. Multilobated B-cell lymphoma may be its neoplastic counterpart in which the nuclear lobulation is further exaggerated.

A pencil-beam photon dose algorithm for stereotactic radiosurgery using a miniature multileaf collimator

A computer-controlled miniature multileaf collimator (MMLC) with 4 mm leaf width and a maximum field size of 6 cm X 6 cm has been designed as a tertiary beam-shaping device for linac-based stereotactic radiosurgery. The purpose of this study is to develop an accurate and efficient dose calculation model for use with the MMLC. A pencil-beam based algorithm using a sum of three Gaussian kernels was developed to model the off-axis ratio of MMLC fields. Because the kernel integration over a rectangular field can be solved in closed form, dose to any point from an arbitrary MMLC field can be calculated efficiently by summing dose contribution from a set of rectangular apertures and transmission blocks that model individual leaf openings or leaf transmissions. The model uses an effective rectangular field and equivalent square method for determination of depth dose and dose output. Results showed that the calculated percentage depth dose was within 1% and output factor was within 1.5% of measured data. The parameters of the pencil beam kernels were extracted by fitting measured off-axis profiles for a few field sizes at a few depths. The accuracy of the calculated off-axis ratio was tested by comparison with measured data for a number of MMLC fields. The algorithm was shown to be accurate to within 1.5% or 1 mm for off-axis ratios. The algorithm computes at a speed of 34,600 data points per second on a DEC Alpha server model 2000/433 (Digital Equipment Corp., Maynard, MA), which is about 15 times faster than a Clarkson-type summation method.

Enzymatic/Magnetic Hybrid Micromotors for Synergistic Anticancer Therapy

Micro/nanomotors (MNMs), which propel by transforming various forms of energy into kinetic energy, have emerged as promising therapeutic nanosystems in biomedical applications. However, most MNMs used for anticancer treatment are only powered by one engine or provide a single therapeutic strategy. Although double-engined micromotors for synergistic anticancer therapy can achieve more flexible movement and efficient treatment efficacy, their design remains challenging. In this study, we used a facile preparation method to develop enzymatic/magnetic micromotors for synergetic cancer treatment via chemotherapy and starvation therapy (ST), and the size of micromotors can be easily regulated during the synthetic process. The enzymatic reaction of glucose oxidase, which served as the chemical engine, led to self-propulsion using glucose as a fuel and ST via a reduction in the energy available to cancer cells. Moreover, the incorporation of Fe₃O₄ nanoparticles as a magnetic engine enhanced the kinetic power and provided control over the direction of movement. Inherent pH-responsive drug release behavior was observed owing to the acidic decomposition of drug carriers in the intracellular microenvironment of cancer cells. This system displayed enhanced anticancer efficacy owing to the synergetic therapeutic strategies and increased cellular uptake in a targeted area because of the improved motion behavior provided by the double engines. Therefore, the demonstrated micromotors are promising candidates for anticancer biomedical microsystems.

Dosimetry of effective wedge fields produced by an internal wedge

A procedure is described to calculate the monitor unit ratios required to produce effective wedge fields having a desired wedge angle by combining an internal 60 degrees wedge with an open field. Complementary procedures are derived and demonstrated for calculating the effective wedge dose distributions with wedge angles of 15 degrees, 30 degrees, and 45 degrees using the central axis depth dose data and off-axis ratios of the open field and the 60 degrees wedged field. Measurements at five points on and off the central axis within each field and measurements of the effective wedge factor demonstrated that the calculated wedge distributions were correctly delivered to within 2% in all cases.

Multistimuli-Responsive Hydroplaning Superhydrophobic Microrobots with Programmable Motion and Multifunctional Applications

Superhydrophobic microrobots that can swim efficiently and rapidly on water under the action of external stimuli have attracted significant research attention for various applications. However, most studies on superhydrophobic microrobots have focused on single-stimulus driving modes, which limit the motion and functional applications of microrobots in complex aquatic environments. Therefore, multistimuli-responsive superhydrophobic microrobots that are capable of drifting rapidly on water through light, magnetic, and chemical control were developed in this study. The stability and environmental adaptability of the microrobots were systematically investigated. The microrobots achieved programmable trajectory motion on water, particularly complex motions such as circular, spiral, and helical movements under the coupled influence of chemical and magnetic fields. Importantly, the motion and control of multimicrorobots can be realized by combining control methods. Under the action of light and magnetic field, multimicrorobots could realize cooperative movement and completed the transportation of cargo. Additionally, broad multifunctional applications of the microrobots were explored in terms of oil spill recovery and solution mix. This study provides a method for the preparation and development of superhydrophobic microrobots with multistimuli-responsive characteristics.