Microampere Electric Current Causes Bacterial Membrane Damage and Two-Way Leakage in a Short Period of Time

ABSTRACT Physical agents, such as low electric voltage and current, have recently gained attention for antimicrobial treatment due to their bactericidal capability. Although microampere electric current was shown to suppress the growth of bacteria, it remains unclear to what extent the microampere current damaged the bacterial membrane. Here, we investigated the membrane damage and two-way leakage caused by microampere electric current (≤100 μA) with a short exposure time (30 min). Based on MitoTracker staining, propidium iodide staining, filtration assays, and quantitative single-molecule localization microscopy, we observed significant membrane damage, which allowed two-way leakage of ions, small molecules, and proteins. This study paves the way to new development of antimicrobial applications for ultralow electric voltage and current. IMPORTANCE Although electric voltage and current have been studied for a long time in terms of their ability to suppress the growth of bacteria and to kill bacteria, increasing interest has been aroused more recently due to the prevalence of antibiotic resistance of microbes in past decades. Toward understanding the antimicrobial mechanism of low electric voltage and current, previous studies showed that treating bacteria with milliampere electric currents (≥5 mA) for ≥72 h led to significant damage of the bacterial membrane, which likely resulted in leakage of cellular contents and influx of toxic substances through the damaged membrane. However, it remains unclear to what extent membrane damage and two-way (i.e., inward and outward) leakage are caused by lower (i.e., microampere) electric current in a shorter time frame. In this work, we set out to answer this question. We observed that the membrane damage was caused by microampere electric current in half an hour, which allowed two-way leakage of ions, small molecules, and proteins.

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Microampere electric currents caused bacterial membrane damage and two-way leakage in short time

10.1101/2020.03.13.991067 ◽

2020 ◽

Author(s):

V R Krishnamurthi ◽

A Rogers ◽

J Peifer ◽

I Niyonshuti ◽

J Chen ◽

...

Keyword(s):

Small Molecules ◽

Single Molecule ◽

Propidium Iodide ◽

Membrane Damage ◽

Bacterial Membrane ◽

Electric Currents ◽

Localization Microscopy ◽

Propidium Iodide Staining ◽

Short Time ◽

Single Molecule Localization Microscopy

AbstractPhysical agents such as low electric voltages and currents have recently gained attention for antimicrobial treatment due to their bactericidal capability. Although microampere electric currents were shown to suppress the growth of bacteria, it remains unclear to what extent the microampere currents damage bacterial membrane. Here, we investigated the membrane damage and two-way leakage caused by microampere electric currents (≤ 100 μA) in a short time (30 min). Based on MitoTracker staining, propidium iodide staining, filtration assays, and quantitative single-molecule localization microscopy, we found that microampere electric currents caused significant membrane damages and allowed two-way leakages of ions, small molecules and proteins. This study paves the way to new development and antibiotic applications of ultra-low electric voltages and currents.Statement of SignificancePrevious studies showed that treating bacteria with milliampere electric currents for 72 hours led to significant damages of the bacterial membrane. However, it remains unclear to what extent membrane damages and two-way (i.e. inward and outward) leakages are caused by lower electric currents in a shorter time. In this work, we set out to answer this question. We carried out several assays on the bacteria treated by microampere electric currents of ≤ 100 μA for 30 min, including MitoTracker staining, propidium iodide staining, filtration assays, and quantitative single-molecule localization microscopy. We found and quantified that the membrane damages were caused by microampere electric currents in half an hour and allowed two-way leakages of ions, small molecules, and proteins.

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Antigiardiasic activity of Cu(II) coordination compounds: Redox imbalance and membrane damage after a short exposure time

Journal of Inorganic Biochemistry ◽

10.1016/j.jinorgbio.2019.03.012 ◽

2019 ◽

Vol 195 ◽

pp. 83-90 ◽

Cited By ~ 6

Author(s):

Yadira Rufino-González ◽

Martha Ponce-Macotela ◽

Juan Carlos García-Ramos ◽

Mario N. Martínez-Gordillo ◽

Rodrigo Galindo-Murillo ◽

...

Keyword(s):

Exposure Time ◽

Coordination Compounds ◽

Membrane Damage ◽

Short Exposure ◽

Short Exposure Time ◽

Redox Imbalance

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Multiple phase transitions investigated by high-speed TEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100175880 ◽

1990 ◽

Vol 48 (4) ◽

pp. 550-551

Author(s):

Oleg Bostanjoglo ◽

Peter Thomsen-Schmidt

Keyword(s):

Phase Transitions ◽

High Speed ◽

Short Exposure ◽

Semiconductor Film ◽

Time Resolved ◽

Short Exposure Time ◽

Multiple Phase ◽

Model Substance ◽

History Of ◽

Electron Image

Thin GexTe1-x (x = 0.15-0.8) were studied as a model substance of a composite semiconductor film, in addition being of interest for optical storage material. Two complementary modes of time-resolved TEM were used to trace the phase transitions, induced by an attached Q-switched (50 ns FWHM) and frequency doubled (532 nm) Nd:YAG laser. The laser radiation was focused onto the specimen within the TEM to a 20 μm spot (FWHM). Discrete intermediate states were visualized by short-exposure time doubleframe imaging /1,2/. The full history of a transformation was gained by tracking the electron image intensity with photomultiplier and storage oscilloscopes (space/time resolution 100 nm/3 ns) /3/. In order to avoid radiation damage by the probing electron beam to detector and specimen, the beam is pulsed in this continuous mode of time-resolved TEM,too.Short events ( <2 μs) are followed by illuminating with an extended single electron pulse (fig. 1c)

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EVALUATION OF OCCUPATIONAL RADIATION EXPOSURE IN A RADIO-DIAGNOSTIC FACILITY IN KATSINA- NIGERIA

FUDMA Journal of Sciences ◽

10.33003/fjs-2020-0402-406 ◽

2020 ◽

Vol 4 (2) ◽

pp. 722-729

Author(s):

Usman Sani ◽

Bashir Gide Muhammad ◽

Dimas Skam Joseph ◽

D. Z. Joseph

Keyword(s):

Radiation Dose ◽

Radiation Exposure ◽

Short Exposure ◽

Skin Dose ◽

Continuous Training ◽

Short Exposure Time ◽

Occupational Dose ◽

Dose Limits ◽

Radiation Workers ◽

Occupational Radiation

Poor implementation of quality assurance programs in the radiation industry has been a major setback in our locality. Several studies revealed that occupational workers are exposed to many potential hazards of ionizing radiation during radio-diagnostic procedures, yet radiation workers are often not monitored. This study aims to evaluate the occupational exposure of the radiation workers in Federal Medical Centre Katsina, and to compare the exposure with recommended occupational radiation dose limits. The quarterly readings of 20 thermo-luminescent dosimeters (TLDs') used by the radiation workers from January to December, 2019 were collected from the facility's radiation monitoring archive, and subsequently assessed and analyzed. The results indicate that the average annual equivalent dose per occupational worker range from 0.74 to 1.20 mSv and 1.28 to 2.21 mSv for skin surface and deep skin dose, measured at 10 mm and 0.07 mm tissue depth respectively. The occupational dose was within the recommended national and international limits of 5 mSv per annum or an average of 20 mSv in 5 years. Therefore, there was no significant radiation exposure to all the occupational workers in the study area. Though, the occupational radiation dose is within recommended limit, this does not eliminate stochastic effect of radiation. The study recommended that the occupational workers should adhere and strictly comply with the principles of radiation protection which includes distance, short exposure time, shielding and proper monitoring of dose limits. Furthermore, continuous training of the radiation workers is advised.

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Infrared nanospectroscopy reveals the molecular interaction fingerprint of an aggregation inhibitor with single Aβ42 oligomers

Nature Communications ◽

10.1038/s41467-020-20782-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Francesco Simone Ruggeri ◽

Johnny Habchi ◽

Sean Chia ◽

Robert I. Horne ◽

Michele Vendruscolo ◽

...

Keyword(s):

Small Molecules ◽

Single Molecule ◽

Protein Misfolding ◽

Molecular Mechanisms ◽

Chemical Sensitivity ◽

Incomplete Knowledge ◽

Parkinson’S Diseases ◽

Aggregation Inhibitor ◽

Misfolding Diseases

AbstractSignificant efforts have been devoted in the last twenty years to developing compounds that can interfere with the aggregation pathways of proteins related to misfolding disorders, including Alzheimer’s and Parkinson’s diseases. However, no disease-modifying drug has become available for clinical use to date for these conditions. One of the main reasons for this failure is the incomplete knowledge of the molecular mechanisms underlying the process by which small molecules interact with protein aggregates and interfere with their aggregation pathways. Here, we leverage the single molecule morphological and chemical sensitivity of infrared nanospectroscopy to provide the first direct measurement of the structure and interaction between single Aβ42 oligomeric and fibrillar species and an aggregation inhibitor, bexarotene, which is able to prevent Aβ42 aggregation in vitro and reverses its neurotoxicity in cell and animal models of Alzheimer’s disease. Our results demonstrate that the carboxyl group of this compound interacts with Aβ42 aggregates through a single hydrogen bond. These results establish infrared nanospectroscopy as a powerful tool in structure-based drug discovery for protein misfolding diseases.

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The Interaction of Temperature and Bending Load on Structural Performance of Chinese Larch Wood

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.531-532.122 ◽

2012 ◽

Vol 531-532 ◽

pp. 122-126

Author(s):

Hai Bin Zhou ◽

Chuan Shuang Hu ◽

Jian Hui Zhou

Keyword(s):

Elevated Temperatures ◽

Coupling Effect ◽

Structural Performance ◽

Effect Of Temperature ◽

Short Exposure ◽

Short Exposure Time ◽

Larch Wood ◽

Timber Construction ◽

Bending Load ◽

Stress Levels

Wood is being used extensively in timber construction in China. In fire-resistant design for timber construction, the main goal is to ensure that enough structural integrity is maintained during a fire to prevent structure collapse. It is important to understand its structural performance when exposed to elevated temperatures and loaded by stress levels. To study the interaction effect of Chinese larch wood, a total of 72 small clear wood samples were observed under constant stress levels when the wood temperature was elevated. The results indicated that Chinese larch wood was more susceptible to the coupling effect of temperature and stress. The interaction promoted a temporary stable flexural structure to collapse during a short exposure time.

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