Multiple Focus Reflectance Confocal Microscopy for In Vivo Imaging

Light microscopy techniques provide a means to image interesting features on the very small scale. Advances in passive and active optical elements have driven progress in microscopy, including but not limited to super-resolution, large field of view, and three-dimensional microscopy. Medical diagnostics can benefit from this progress. Typically, for a suspected cancerous tissue, a biopsy is taken and analyzed by histology. Features of the tissue can be identified throughout the depth of the slice to inform diagnosis. Translating optical techniques to clinical applications presents a unique challenge. Typically, a microscopy sample is cut, sliced, and stained as part of the preparation needed for benchtop microscopes. In the clinic, the sample is inaccessible within a living, breathing human subject. Confocal microscopy is a well-known technique that can solve part of the problem, as it can image thin slices of tissue optically (i.e. no cutting necessary). Additionally, as a reflectance microscope, no exogenous contrast agents are needed. However, current techniques have not shown to be effective for imaging the entire tissue due to the cumbersome nature of in vivo imaging. This dissertation reports solutions by designing a confocal microscope capable of imaging live bulk tissue at multiple depths by means of some non-mechanical tunable focus. First, we evaluate the technique, chromatic confocal microscopy, to simultaneously capture images at multiple depths. We present a chromatic confocal microscope with expanded range that can produce images from a highly scattering tissue sample. Design considerations and future work are discussed. Second, we discuss the use of a hand-held confocal microscope which employs a tunable lens for multi-depth imaging and present a second generation alignment-free design with improved image quality. Image quality and reliability are paramount to validating an imaging system for use as a clinical diagnostic tool. We show the capability of the system to detect features by means of optical biopsy and compare these images to the actual histological analysis

Atrial defibrillation with a transvenous lead A randomized comparison of active can shocking pathways

AbstractOBJECTIVESThe purpose of this study was to compare transvenous atrial defibrillation thresholds with lead configurations consisting of an active left pectoral electrode and either single or dual transvenous coils.BACKGROUNDLow atrial defibrillation thresholds are achieved using complex lead systems including coils in the coronary sinus. However, the efficacy of more simple ventricular defibrillation leads with active pectoral pulse generators to defibrillate atrial fibrillation (AF) is unknown.METHODSThis study was a prospective, randomized assessment of shock configuration on atrial defibrillation thresholds in 32 patients. The lead system was a dual coil Endotak DSP lead with a left pectoral pulse generator emulator. Shocks were delivered either between the right ventricular coil and an active can in common with the proximal atrial coil (triad) or between the atrial coil and active can (transatrial).RESULTSDelivered energy at defibrillation threshold was 7.1 ± 6.0 J in the transatrial configuration and 4.0 ± 4.2 J in the triad configuration (p < 0.005). Moreover, a low threshold (≤3 J) was observed in 69% of subjects in the triad configuration but only 47% in the transatrial configuration. Peak voltage and shock impedance were also lowered significantly in the triad configuration. Left atrial size was the only clinical predictor of the defibrillation theshold (r = 0.57, p < 0.002).CONCLUSIONSThese results indicate that low atrial defibrillation thresholds can be achieved using a single-pass transvenous ventricular defibrillation lead with a conventional ventricular defibrillation pathway. These data support the development of the combined atrial and ventricular defibrillator system

Mitogen-Activated Protein Kinases and Mitogen-Activated Protein Kinase Phosphatases Mediate the Inhibitory Effects of All-Trans Retinoic Acid on the Hypertrophic Growth of Cardiomyocytes

All-trans retinoic acid (RA) has been implicated in mediation of cardiac growth inhibition in neonatal cardiomyocytes. However, the associated signaling mechanisms remain unclear. Utilizing neonatal cardiomyocytes, we demonstrated that RA suppressed the hypertrophic features induced by cyclic stretch or angiotensin II (Ang II). Cyclic stretch- or Ang II-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2), C-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAP kinase) was dose- and time-dependently inhibited by RA. Significant inhibition was observed by 5 μM RA, from 8 to 24 h of pretreatment. This inhibitory effect was not mediated at the level of mitogen-activated protein kinase kinases (MKKs), because RA had no effect on stretch- or Ang II-induced phosphorylation of MEK1/2, MKK4, and MKK3/6. However, the phosphatase inhibitor vanadate reversed the inhibitory effect of RA on MAP kinases and protein synthesis. RA up-regulated the expression level of MAP kinase phosphatase-1 (MKP-1) and MKP-2, and the time course was correlated with the inhibitory effect of RA on activation of MAP kinases. Overexpression of wild-type MKP-1 inhibited the phosphorylation of JNK and p38 in cardiomyocytes. These data indicated that MKPs were involved in the inhibitory effect of RA on MAP kinases. Using specific RAR and RXR antagonists, we demonstrated that both RARs and RXRs were involved in regulating stretch- or Ang II-induced activation of MAP kinases. Our findings provide the first evidence that the anti-hypertrophic effect of RA is mediated by up-regulation of MKPs and inhibition of MAP kinase signaling pathways

Temporal decline in defibrillation thresholds with an active pectoral lead system

AbstractOBJECTIVESThe objective of this study was to characterize temporal changes in defibrillation thresholds (DFTs) after implantation with an active pectoral, dual-coil transvenous lead system.BACKGROUNDVentricular DFTs rise over time when monophasic waveforms are used with non-thoracotomy lead systems. This effect is attenuated when biphasic waveforms are used with transvenous lead systems; however, significant increases in DFT still occur in a minority of patients. The long-term stability of DFTs with contemporary active pectoral lead systems is unknown.METHODSThis study was a prospective assessment of temporal changes in DFT using a uniform testing algorithm, shock polarity and dual-coil active pectoral lead system. Thresholds were measured at implantation, before discharge and at long-term follow-up (70 ± 40 weeks) in 50 patients.RESULTSThe DFTs were 9.2 ± 5.4 J at implantation, 8.3 ± 5.8 J before discharge and 6.9 ± 3.6 J at long-term follow-up (p < 0.01 by analysis of variance; p < 0.05 for long-term follow-up vs. at implantation or before discharge). The effect was most marked in a prespecified subgroup with high implant DFTs (≥15 J). No patient developed an inadequate safety margin (<9 J) during follow-up.CONCLUSIONSThe DFTs declined significantly after implantation with an active pectoral, dual-coil transvenous lead system, and no clinically significant increases in DFT were observed. Therefore, routine defibrillation testing may not be required during the first two years after implantation with this lead system, in the absence of a change in the cardiac substrate or treatment with antiarrhythmic drugs

Chromatic confocal microscopy for multi-depth imaging of epithelial tissue

We present a novel chromatic confocal microscope capable of volumetric reflectance imaging of microstructure in non-transparent tissue. Our design takes advantage of the chromatic aberration of aspheric lenses that are otherwise well corrected. Strong chromatic aberration, generated by multiple aspheres, longitudinally disperses supercontinuum light onto the sample. The backscattered light detected with a spectrometer is therefore wavelength encoded and each spectrum corresponds to a line image. This approach obviates the need for traditional axial mechanical scanning techniques that are difficult to implement for endoscopy and susceptible to motion artifact. A wavelength range of 590-775 nm yielded a >150 µm imaging depth with ~3 µm axial resolution. The system was further demonstrated by capturing volumetric images of buccal mucosa. We believe these represent the first microstructural images in non-transparent biological tissue using chromatic confocal microscopy that exhibit long imaging depth while maintaining acceptable resolution for resolving cell morphology. Miniaturization of this optical system could bring enhanced speed and accuracy to endomicroscopic in vivo volumetric imaging of epithelial tissue

An efficient digital signal processing method for RRNS-based DS-CDMA systems

This paper deals with an efficient method for achieving low power and high speed in advanced Direct-Sequence Code Division Multiple-Access (DS-CDMA) wireless communication systems based on the Residue Number System (RNS). A modified algorithm for multiuser DS-CDMA signal generation in MATLAB is proposed and investigated. The most important characteristics of the generated PN code are also presented. Subsequently, a DS-CDMA system based on the combination of the RNS or the so-called Redundant Residue Number System (RRNS) is proposed. The enhanced method using a spectrally efficient 8-PSK data modulation scheme to improve the bandwidth efficiency for RRNS-based DS-CDMA systems is presented. By using the C-measure (complexity measure) of the error detection function, it is possible to estimate the size of the circuit. Error detection function in RRNSs can be efficiently implemented by LookUp Table (LUT) cascades

Texas Beef Cattle Producers' Behavioral Intention to Adopt Recommended Stocking Rates: Implications for Water and Land Quality

Water has a significant role in society, whether through human consumption or agricultural use. The Lavaca River Watershed is an agricultural community affected by nonpoint source pollution, and water quality protection is of high concern. Often, beef cattle operations are linked to nonpoint source pollution which contaminates surrounding water sources. If proper grazing management practices are not used, wastes from the operation impair water quality in the area. Landowners must use proper stocking rates and implement practices to benefit land and water quality in addition to overall operation profit. In an effort to combat these water quality issues, this study measured the effect of knowledge of stocking rates and awareness of the Natural Resources Conservation Services and Texas State Soil and Water Conservation Board on behavioral intention to adopt grazing management practices. A regression analysis found three items, based on county appraisal district recommendations, based on calculated grazeable acres, and household income from agriculture production , to have the most variance on Lavaca County landowner intention to adopt grazing management practices

Analyza moznosti vyuziti obecne transformace pro transformaci elipsoidickych souradnic a vypoctu relativnich odlehlosti elipsoidu

Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi