A computer-controlled stimulator with applications to cardiac electrophysiology

1980 ◽  
Vol 239 (2) ◽  
pp. H278-H282
Author(s):  
V. Elharrar
Keyword(s):  
Cardiac Electrophysiology ◽  
Current Mode ◽  
Pulse Amplitude ◽  
Constant Current ◽  
Constant Voltage ◽  
S 100 ◽  
Computer Controlled ◽  
Constant Current Mode

A computer-controlled stimulator compatible with S-100 microcomputers using an 8080 or Z-80 microprocessor is described. The pusle interval is controlled from 1 to 65,535 ms and the pulse duration from 1 to 255 ms by steps of 1 ms. The pulse amplitude is controlled from 0 to 10.24 V (in constant voltage mode) and from 0 to 1 mA (in constant current mode) by steps of 4 mV and 4 mu A, respectively. The characteristics of the stimuli and their timing can be altered automatically according to programmed protocols that may or may not take into account the response of the biologic preparation. Applications of this stimulator to the study of experimental cardiac electrophysiology are illustrated in vivo and in vitro.

scholarly journals Fabrication of freestanding Pt nanowires for use as thermal anemometry probes in turbulence measurements

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Hai Le-The ◽  
Christian Küchler ◽  
Albert van den Berg ◽  
Eberhard Bodenschatz ◽  
Detlef Lohse ◽  
...  
Keyword(s):  
Room Temperature ◽  
Fluid Velocity ◽  
Current Mode ◽  
Constant Current ◽  
Small Scale ◽  
Turbulence Measurements ◽  
High Dynamic ◽  
Scale Turbulence ◽  
Constant Current Mode ◽  
Pt Nanowires

AbstractWe report a robust fabrication method for patterning freestanding Pt nanowires for use as thermal anemometry probes for small-scale turbulence measurements. Using e-beam lithography, high aspect ratio Pt nanowires (~300 nm width, ~70 µm length, ~100 nm thickness) were patterned on the surface of oxidized silicon (Si) wafers. Combining wet etching processes with dry etching processes, these Pt nanowires were successfully released, rendering them freestanding between two silicon dioxide (SiO2) beams supported on Si cantilevers. Moreover, the unique design of the bridge holding the device allowed gentle release of the device without damaging the Pt nanowires. The total fabrication time was minimized by restricting the use of e-beam lithography to the patterning of the Pt nanowires, while standard photolithography was employed for other parts of the devices. We demonstrate that the fabricated sensors are suitable for turbulence measurements when operated in constant-current mode. A robust calibration between the output voltage and the fluid velocity was established over the velocity range from 0.5 to 5 m s−1 in a SF6 atmosphere at a pressure of 2 bar and a temperature of 21 °C. The sensing signal from the nanowires showed negligible drift over a period of several hours. Moreover, we confirmed that the nanowires can withstand high dynamic pressures by testing them in air at room temperature for velocities up to 55 m s−1.

scholarly journals A complex control region of the mouse rRNA gene directs accurate initiation by RNA polymerase I.

1985 ◽  
Vol 5 (3) ◽  
pp. 554-562 ◽  
Author(s):  
K G Miller ◽  
J Tower ◽  
B Sollner-Webb
Keyword(s):  
Initiation Site ◽  
Rrna Gene ◽  
Sufficient Information ◽  
Reaction Conditions ◽  
Cell Extracts ◽  
S 100 ◽  
Initiation Reaction ◽  
Polymerase I

To determine the size and location of the mouse rDNA promoter, we constructed systematic series of deletion mutants approaching the initiation site from the 5' and 3' directions. These templates were transcribed in vitro under various conditions with S-100 and whole-cell extracts. Surprisingly, the size of the rDNA region that determines the level of transcription differed markedly, depending on the reaction conditions. In both kinds of cell extracts, the apparent 5' border of the promoter was at residue ca. -27 under optimal transcription conditions, but as reaction conditions became less favorable, the 5' border moved progressively out to residues -35, -39, and -45. The complete promoter, however, extends considerably further, for under other nonoptimal conditions, we observed major effects of promoter domains extending in the 5' direction to positions ca. -100 and -140. In contrast, the apparent 3' border of the mouse rDNA promoter was at residue ca. +9 under all conditions examined. We also show that the subcloned rDNA region from -39 to +9 contains sufficient information to initiate accurately and that the region between +2 and +9 can influence the specificity of initiation. These data indicate that, although the polymerase I transcription factors recognize and accurately initiate with only the sequences downstream of residue -40, sequences extending out to residue -140 greatly favor the initiation reaction; presumably, this entire region is involved in rRNA transcription in vivo.

scholarly journals In vitro and in vivo cardiac toxicity of flavored electronic nicotine delivery systems

2021 ◽  
Vol 320 (1) ◽  
pp. H133-H143
Author(s):  
Obada Abouassali ◽  
Mengmeng Chang ◽  
Bojjibabu Chidipi ◽  
Jose Luis Martinez ◽  
Michelle Reiser ◽  
...  
Keyword(s):  
Ventricular Arrhythmias ◽  
Cardiac Electrophysiology ◽  
Cardiac Toxicity ◽  
Delivery Systems ◽  
Cardiac Safety ◽  
Electronic Nicotine Delivery Systems ◽  
Nicotine Delivery

The use of electronic nicotine delivery systems (ENDS) is not harm free. It is not known whether ENDS negatively affect cardiac electrophysiological function. Our study in cell lines and in mice shows that ENDS can compromise cardiac electrophysiology, leading to action potential instability and inducible ventricular arrhythmias. Further investigations are necessary to assess the long-term cardiac safety profile of ENDS products in humans and to better understand how individual components of ENDS affect cardiac toxicity.

Bulk Carbon Nanotubes for Micro Anemometry (Invited Paper)

2003 ◽  
Author(s):  
Victor T. S. Wong ◽  
Wen J. Li
Keyword(s):  
Current Mode ◽  
Constant Current ◽  
Experimental Measurements ◽  
Dynamic Characterization ◽  
Temperature Coefficient Of Resistance ◽  
Micro Electro Mechanical Systems ◽  
Mode Configuration ◽  
Multi Walled Carbon Nanotube ◽  
Constant Current Mode ◽  
Bulk Carbon

We have successfully developed a process to manipulate post-growth multi-walled carbon nanotube (MWNT) by AC electrophoresis to form resistive elements and showed that these elements can potentially served as novel sensing elements for micro/nano thermal and anemometry sensing. We have measured the temperature coefficient of resistance (TCR) of these MWNT bundles and integrated them into constant current mode configuration for dynamic characterization. Preliminary experimental measurements showed that the devices could be operated in micro-watt power range for micro thermal and anemometry sensing. This operation range is three orders of magnitude lower than conventional Micro-Electro-Mechanical Systems (MEMS) polysilicon sensors in constant current (CC) mode configuration. In addition, the devices exhibited very fast frequency response (> 100 kHz) in CC mode. Based on these results, we are currently developing polymer-based MWNT embedded sensor for various micro/nano fluidic applications.

Constant-Current-Mode LAPS (CLAPS) for the Detectionof Penicillin

2001 ◽  
Vol 13 (8-9) ◽  
pp. 733-736 ◽  
Author(s):  
Tatsuo Yoshinobu ◽  
Holger Ecken ◽  
Arshak Poghossian ◽  
Anette Simonis ◽  
Hiroshi Iwasaki ◽  
...  
Keyword(s):  
Current Mode ◽  
Constant Current ◽  
Constant Current Mode

scholarly journals Orphanin FQ: Evidence for a Role in the Control of the Reproductive Neuroendocrine System

Endocrinology ◽  
2007 ◽  
Vol 148 (10) ◽  
pp. 4993-5001 ◽  
Author(s):  
Chad D. Foradori ◽  
Marcel Amstalden ◽  
Lique M. Coolen ◽  
Sushma R. Singh ◽  
Christine J. McManus ◽  
...  
Keyword(s):  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Brain Regions ◽  
Orphanin Fq ◽  
Endogenous Opioid ◽  
Endogenous Opioid Peptide ◽  
External Zone ◽  
Gnrh Secretion

Orphanin FQ (OFQ), also known as nociceptin, is a member of the endogenous opioid peptide family that has been functionally implicated in the control of pain, anxiety, circadian rhythms, and neuroendocrine function. In the reproductive system, endogenous opioid peptides are involved in the steroid feedback control of GnRH pulses and the induction of the GnRH surge. The distribution of OFQ in the preoptic area and hypothalamus overlaps with GnRH, and in vitro evidence suggests that OFQ can inhibit GnRH secretion from hypothalamic fragments. Using the sheep as a model, we examined the potential anatomical colocalization between OFQ and GnRH using dual-label immunocytochemistry. Confocal microscopy revealed that approximately 93% of GnRH neurons, evenly distributed across brain regions, were also immunoreactive for OFQ. In addition, almost all GnRH fibers and terminals in the external zone of the median eminence, the site of neurosecretory release of GnRH, also colocalized OFQ. This high degree of colocalization suggested that OFQ might be functionally important in controlling reproductive endocrine events. We tested this possibility by examining the effects of intracerebroventricular administration of [Arg14, Lys15] OFQ, an agonist to the OFQ receptor, on pulsatile LH secretion. The agonist inhibited LH pulse frequency in both luteal phase and ovariectomized ewes and suppressed pulse amplitude in the latter. The results provide in vivo evidence supporting a role for OFQ in the control of GnRH secretion and raise the possibility that it acts as part of an ultrashort, autocrine feedback loop controlling GnRH pulses.

scholarly journals In Vitro Cytotoxicity Analysis of Chloroform Extract of Novel Poly Herbal Formulation

2017 ◽  
Vol 9 (2) ◽  
Author(s):  
S. Selvakumar ◽  
Barnali Sarkar
Keyword(s):  
Human Subjects ◽  
Current Mode ◽  
Chloroform Extract ◽  
In Vitro Cytotoxicity ◽  
Synthetic Drugs ◽  
Polyherbal Formulation ◽  
Herbal Formulation ◽  
Toxicity Effects

Objective: It is of interest to investigate the in vitro cyto toxicity effects of chloroformic extract of Novel polyherbal formulation were studied. Materials and Methods: Cytotoxicity of the crude extract of polyherbal formulation was evaluated on LLCMK2 monkey kidney epithelial cells and Cell viability was determined by using MTT assay. Results and Discussion: Our results indicate that the non toxic nature of a poly herbal formulation of Novel polyherbal formulation on control and experimental cell lines. Conclusion: The current mode of treatment for various diseases including cancer is based on synthetic drugs. These drugs are effective but they show serious adverse effects and also alter the genetic and metabolic activity of the patient. Furthermore, in vivo activity of the active compounds of a poly herbal formulation Novel polyherbal formulation needs to be determined in animal models and human subjects, so as to determine their efficacy in a metabolic environment.

Sign in / Sign up

Export Citation Format

Share Document