Serial changes of myocardial perfusion imaging in takotsubo and reverse takotsubo cardiomyopathy.

BACKGROUND: Takotsubo cardiomyopathy (TTC) shows reversible hypokinesis in the left ventricular (LV) apical-half segment and hyperkinesis in the LV basal-half segment. However, the precise pathophysiological mechanism of TTC is unclear. Therefore, this study sought to clarify the nuclear characteristics, degree of myocardial damage, and serial change of TTC and rTTC using myocardial perfusion imaging. METHODS: We performed myocardial perfusion scintigraphy in 28 patients (TTC: 20, rTTC: 8) using Tc-99m sestamibi and assessed minimum percentage uptake (min-%-uptake), extent score (ES) and summed rest score (SRS) at acute and chronic phases. RESULTS: Min-%-uptake improved from the acute to the chronic phase (TTC: 54 [48-59]% vs 87 [81-90]%, P  < 0.01; rTTC: 60 [55-64]% vs 77 [71-79]%, P < 0.01), as did the ES (TTC: 32 [26-41]% vs 0.0 [0.0-6.0]%, P < 0.01; rTTC: 16 [12-34]% vs 0.0 [0.0-0.0]%, P = 0.02) and SRS (TTC: 4.5 [3.9-5.3] vs 0.0 [0.0-0.2], P < 0.01; rTTC: 3.6 [3.3-3.8] vs 0.0 [0.0-0.0], P = 0.01). CONCLUSION: Tc-99m sestamibi uptake was reduced in hypokinetic regions in the acute phase and improved in the chronic phase. TTC and rTTC may involve a reversible disorder of the myocardial cell membrane, mitochondria, and microcirculation.

SARS-CoV-2 Disinfection of Air and Surface Contamination by TiO2 Photocatalyst-Mediated Damage to Viral Morphology, RNA, and Protein.

SARS-CoV-2 is the causative agent of COVID-19, which is a global pandemic. SARS-CoV-2 is transmitted rapidly via contaminated surfaces and aerosols, emphasizing the importance of environmental disinfection to block the spread of virus. Ultraviolet C radiation and chemical compounds are effective for SARS-CoV-2 disinfection, but can only be applied in the absence of humans due to their toxicities. Therefore, development of disinfectants that can be applied in working spaces without evacuating people is needed. Here we showed that TiO2-mediated photocatalytic reaction inactivates SARS-CoV-2 in a time-dependent manner and decreases its infectivity by 99.9% after 20 min and 120 min of treatment in aerosol and liquid, respectively. The mechanistic effects of TiO2 photocatalyst on SARS-CoV-2 virion included decreased total observed virion count, increased virion size, and reduced particle surface spike structure, as determined by transmission electron microscopy. Damage to viral proteins and genome was further confirmed by western blotting and RT-qPCR, respectively. The multi-antiviral effects of TiO2-mediated photocatalytic reaction implies universal disinfection potential for different infectious agents. Notably, TiO2 has no adverse effects on human health, and therefore, TiO2-induced photocatalytic reaction is suitable for disinfection of SARS-CoV-2 and other emerging infectious disease-causing agents in human habitation.

Ex Vivo Evaluation of Gingival Ablation with Various Laser Systems and Electroscalpel.

Objective: The aim of this study was to perform a systematic and multifaceted comparison of thermal effects during soft tissue ablation with various lasers and an electroscalpel (ES). Materials and methods: Er:YAG, Er,Cr:YSGG, CO2, Diode, Nd:YAG lasers (1 W, pulsed or continuous wave), an ES, and a scalpel (Sc; control), were employed for porcine gingival tissue ablation. Temperature changes during ablation were measured by using an infrared thermal imaging camera and a thermocouple. After ablations, the wounds were observed using stereomicroscopy and scanning electron microscopy (SEM), and histological sections were analyzed. Compositional analysis was also performed on ablated sites by SEM wavelength dispersive X-ray spectroscopy. Results: The surface temperature during irradiation was highest with CO2 (over 500°C), followed by Diode (267°C) and Nd:YAG (258°C), Er:YAG (164°C), ES (135°C), and Er,Cr:YSGG (85°C). Carbonization was negligible (Er:YAG), slight (Er,Cr:YSGG), moderate (Nd:YAG and ES), and severe (CO2 and Diode). Under SEM observation, Er:YAG and Er,Cr:YSGG showed smooth surfaces but other devices resulted in rough appearances. Histologically, the coagulated and thermally affected layer was extremely minimal (38 µm in thickness) and free from epithelial collapse for Er:YAG. Compared with other devices, less compositional surface change was detected with Er:YAG and Er,Cr:YSGG; additionally, the use of water spray further minimized thermal influence. Conclusions: Among various power devices, Er:YAG laser showed the most efficient and refined gingival ablation with minimal thermal influence on the surrounding tissues. Er:YAG and Er,Cr:YSGG lasers with water spray could be considered as minimally invasive power devices for soft tissue surgery.

Self-starting mode-locked Cr:ZnS laser using single-walled carbon nanotubes with resonant absorption at 2.4 µm.

We develop a mode-locked Cr:ZnS polycrystalline laser using single-walled carbon nanotubes (SWCNTs) that have resonant absorption at the wavelength of 2.4 µm. The laser generates ultrashort pulses of 49 fs duration, a 2.4 µm center wavelength, and a 9.2 THz (176 nm) spectral span at a repetition rate of 76 MHz. We also confirm self-starting of the mode-locked operation. SWCNTs, if appropriately controlled in terms of their diameters, prove to be useful as ultrafast saturable absorbers in the mid-infrared region.

High-energy, nanosecond pulsed Cr:CdSe laser with a 2.25-3.08 µm tuning range for laser biomaterial processing.

We have developed a mid-infrared (mid-IR) tunable Cr:CdSe laser with nanosecond pulse operation. A broad tuning range from 2.25 to 3.08 µm and an output energy exceeding 4 mJ at 2.64 µm were demonstrated. The maximum energy conversion for absorbed energy reached 35% when the pump fluence was 2.1 J/cm2. We showed that Cr:CdSe is an attractive laser material for obtaining high-energy pulses in the mid-IR region and that the Cr:CdSe laser has high potential for laser biomaterial processing.

High-efficiency generation of pulsed Lyman-α radiation by resonant laser wave mixing in low pressure Kr-Ar mixture.

We report an experimental generation of ns pulsed 121.568 nm Lyman-α radiation by the resonant nonlinear four-wave mixing of 212.556 nm and 845.015 nm radiation pulses providing a high conversion efficiency 1.7x10-3 with the output pulse energy 3.6 µJ achieved using a low pressure Kr-Ar mixture. Theoretical analysis shows that this efficiency is achieved due to the advantage of using (i) the high input laser intensities in combination with (ii) the low gas pressure allowing us to avoid the onset of full-scale discharge in the laser focus. In particular, under our experimental conditions the main mechanism of photoionization caused by the resonant 2-photon 212.556 nm radiation excitation of Kr atoms followed by the 1-photon ionization leads to ≈17% loss of Kr atoms and efficiency loss only by the end of the pulse. The energy of free electrons, generated by 212.556 nm radiation via (2 + 1)-photon ionization and accelerated mainly by 845.015 nm radiation, remains during the pulse below the level sufficient for the onset of full-scale discharge by the electron avalanche. Our analysis also suggests that ≈30-fold increase of 845.015 nm pulse energy can allow one to scale up the L-α radiation pulse energy towards the level of ≈100 µJ.

Dental hard tissue ablation using mid-infrared tunable nanosecond pulsed Cr:CdSe laser.

BACKGROUND AND OBJECTIVE: Mid-infrared erbium: yttrium-aluminum-garnet (Er:YAG) and erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers (2.94- and 2.78-µm, respectively) are utilized for effective dental hard tissue treatment because of their high absorption in water, hydroxide ion, or both. Recently, a mid-infrared tunable, nanosecond pulsed, all-solid-state chromium-doped: cadmium-selenide (Cr:CdSe) laser system was developed, which enables laser oscillation in the broad spectral range around 2.9 µm. The purpose of this study was to evaluate the ablation of dental hard tissue by the nanosecond pulsed Cr:CdSe laser at a wavelength range of 2.76-3.00 µm. STUDY DESIGN/MATERIALS AND METHODS: Enamel, dentin, and cementum tissue were irradiated at a spot or line at a fluence of 0-11.20 J/cm2 /pulse (energy output: 0-2.00 mJ/pulse) with a repetition rate of 10 Hz and beam diameter of ∼150 µm on the target (pulse width ∼250 ns). After irradiation, morphological changes, ablation threshold, depth, and efficiency, and thickness of the structurally and thermally affected layer of irradiated surfaces were analyzed using stereomicroscopy, scanning electron microscopy (SEM), and light microscopy of non-decalcified histological sections. RESULTS: The nanosecond pulsed irradiation without water spray effectively ablated dental hard tissue with no visible thermal damage such as carbonization. The SEM analysis revealed characteristic micro-irregularities without major melting and cracks in the lased tissue. The ablation threshold of dentin was the lowest at 2.76 µm and the highest at 3.00 µm. The histological analysis revealed minimal thermal and structural changes ∼20 µm wide on the irradiated dentin surfaces with no significant differences between wavelengths. The efficiency of dentin ablation gradually increased from 3.00 to 2.76 µm, at which point the highest ablation efficiency was observed. CONCLUSION: The nanosecond pulsed Cr:CdSe laser demonstrated an effective ablation ability of hard dental tissues, which was remarkably wavelength-dependent on dentin at the spectral range of 2.76-3.00 µm. These results demonstrate the potential feasibility of the use of pulsed Cr:CdSe laser as a novel laser system for dental treatment. Lasers Surg. Med. 48:965-977, 2016. © 2016 Wiley Periodicals, Inc.

Energy output reduction and surface alteration of quartz tips following Er:YAG laser contact irradiation on soft and hard tissues in vitro.

Though the Er:YAG laser (ErL) has been used in periodontal therapy, the irradiated tip damage has not been studied in detail. In this study, the change in the energy output, surface morphology, and temperature of quartz tips was evaluated following contact irradiation. Soft tissue, calculus on extracted human teeth, and porcine bone were irradiated by ErL for 60 min at 14.2 or 28.3 J/cm(2)/pulse and 20 Hz with or without water spray. The energy output ratio declined the most in the calculus group, followed by the bone and soft tissue groups with and/or without water spray. Carbon contamination was detected in all groups, and contamination by P, Ca, and/or other inorganic elements was observed in the calculus and bone groups. The rate of energy output reduction and the degree of surface alteration/contamination is variously influenced by the targeting tissue, temperature elevation of the tip and water spray.

Electronically tuned Cr:ZnSe laser pumped with Q-switched Tm:YAG laser.

We demonstrated a Q-switched, Tm:YAG-laser-pumped electronically tuned Cr:ZnSe laser, which was equipped with an acousto-optic tunable filter as a wavelength-tuning element. A tuning range from 2.17 to 2.71 µm and a maximum output energy of 7.9 mJ at 2.41 µm were realized. The energy conversion efficiency reached 34.1% at 2.41 µm. In addition, the Cr:ZnSe laser produced a high-quality beam in the TEM(00) mode.

Sodium D2 resonance radiation in single-pass sum-frequency generation with actively mode-locked Nd:YAG lasers.

We report on a sodium D(2) resonance coherent light source achieved in single-pass sum-frequency generation in periodically poled MgO-doped stoichiometric lithium tantalate with actively mode-locked Nd:YAG lasers. Mode-locked pulses at 1064 and 1319 nm are synchronized with a time resolution of 37 ps with the phase adjustment of the radio frequencies fed to acousto-optic mode lockers. An output power of 4.6 W at 589.1586 nm is obtained, and beam quality near the diffraction limit is also achieved in a simple design.

Computational model for operation of 2 mum co-doped Tm,Ho solid state lasers.

A computational model for operation of co-doped Tm,Ho solid-state lasers is developed coupling (i) 8-level rate equations with (ii) TEM00 laser beam distribution, and (iii) complex heat dissipation model. Simulations done for Q-switched approximately 0.1 J giant pulse generation by Tm,Ho:YLF laser show that approximately 43% of the 785 nm light diode side-pumped energy is directly transformed into the heat inside the crystal, whereas approximately 45% is the spontaneously emitted radiation from (3)F(4), (5)I(7) , (3)H(4) and (3)H(5) levels. In water-cooled operation this radiation is absorbed inside the thermal boundary layer where the heat transfer is dominated by heat conduction. In high-power operation the resulting temperature increase is shown to lead to (i) significant decrease in giant pulse energy and (ii) thermal lensing.

Automatic continuous scanning and random-access switching of mid-infrared waves generated by difference-frequency mixing.

We report the rapid tuning of mid-infrared waves beyond 5 microm emitted in difference-frequency mixing with an electronically tuned dual-wavelength Ti:Al2O3 laser used as a pumping source. Simultaneous rapid tuning of the dual wavelengths, which satisfy phase matching in AgGaS2, allows rapid random access switching and continuous tuning of mid-infrared wavelengths. In random-access switching, the mid-infrared wavelength is tuned every pulse shot at a repetition rate of 1 kHz. Mid-infrared wavelengths continuously tuned from 5.2 to 7.2 microm, from 7.0 to 9.1 microm, and from 8.9 to 12.0 microm are achieved at phase-matched angles of 55 degrees, 50 degrees, and 45 degrees, respectively.

[Usefulness of lung and right ventricular thallium-201 uptake during single photon emission computed tomography in exercise testing of patients with coronary artery disease].

OBJECTIVES: Increased pulmonary or right ventricular 201Tl uptake during the exercise test has been used as a marker of multivessel coronary artery disease. The most useful method for assessing the severity of coronary artery disease was evaluated among conventional evaluation of single photon emission computed tomography (SPECT), measurement of lung to heart uptake ratio (L/H), and right ventricular to left ventricular uptake ratio (RV/LV) on 201Tl images during exercise testing. METHODS: Regions-of-interest (4 X 4 pixels) were placed at the lung and the heart, and L/H was defined as mean lung uptake/mean heart uptake. Correspondingly, regions-of-interest (4 X 4 pixels) were placed at the RV and the LV, and RV/LV was defined as maximum RV uptake /maximum LV uptake. L/H and RV/LV on the initial image were analyzed in 216 patients(angiographically normal coronary arteries: 89, single-vessel disease: 82, multivessel disease: 45). The diagnostic value was evaluated using the receiver operating characteristic curve. RESULTS: All methods showed significantly higher values in patients with multivessel disease than in patients with no coronary artery disease or single-vessel disease. L/H was significantly higher in patients with prior myocardial infarction and RV/LV was significantly higher in patients without infarction. The sensitivity of only conventional SPECT evaluation for multivessel coronary artery disease was low (sensitivity 53%, specificity 94%). However, addition of evaluation of L/H and RV/LV to SPECT improved the sensitivity for multivessel coronary artery disease (sensitivity 93%, specificity 49%). CONCLUSIONS: The diagnostic sensitivity for multivessel coronary artery disease was improved by adding L/H and RV/LV to conventional evaluation of exercise 201Tl SPECT. L/H and RV/LV during exercise 201Tl imaging may provide additional information regarding the severity of coronary artery disease.

Narrow-band, widely electronically tuned frequency-shifted feedback laser.

The bandwidth of a frequency-shifted feedback Ti:sapphire laser is compressed through compensation for the shifted frequency inside the laser cavity by means of dual acousto-optic tunable filters (AOTFs) without the employment of an etalon. The laser wavelength can be tuned electronically in a 167-nm range by changes in the rf input to the two AOTFs. Wide-range tunability is achieved without mechanical adjustment or the addition of dispersive elements.