Evaluation of non-thermal effect of microwave radiation and its mode of action in bacterial cell inactivation.

A growing body of literature has recognized the non-thermal effect of pulsed microwave radiation (PMR) on bacterial systems. However, its mode of action in deactivating bacteria has not yet been extensively investigated. Nevertheless, it is highly important to advance the applications of PMR from simple to complex biological systems. In this study, we first optimized the conditions of the PMR device and we assessed the results by simulations, using ANSYS HFSS (High Frequency Structure Simulator) and a 3D particle-in-cell code for the electron behavior, to provide a better overview of the bacterial cell exposure to microwave radiation. To determine the sensitivity of PMR, Escherichia coli and Staphylococcus aureus cultures were exposed to PMR (pulse duration: 60 ns, peak frequency: 3.5 GHz) with power density of 17 kW/cm2 at the free space of sample position, which would induce electric field of 8.0 kV/cm inside the PBS solution of falcon tube in this experiment at 25 °C. At various discharges (D) of microwaves, the colony forming unit curves were analyzed. The highest ratios of viable count reductions were observed when the doses were increased from 20D to 80D, which resulted in an approximate 6 log reduction in E. coli and 4 log reduction in S. aureus. Moreover, scanning electron microscopy also revealed surface damage in both bacterial strains after PMR exposure. The bacterial inactivation was attributed to the deactivation of oxidation-regulating genes and DNA damage.

Pulsed 3.5 GHz high power microwaves irradiation on physiological solution and their biological evaluation on human cell lines.

Microwave (MW) radiation is increasingly being used for several biological applications. Many investigations have focused on understanding the potential influences of pulsed MW irradiation on biological solutions. The current study aimed to investigate the effects of 3.5 GHz pulsed MW radiation-irradiated liquid solutions on the survival of human cancer and normal cells. Different physiological solutions such as phosphate buffer saline, deionized water, and Dulbecco's modified Eagle medium (DMEM) for cell culture growth were irradiated with pulsed MW radiation (45 shots with the energy of 1 mJ/shot). We then evaluated physiological effects such as cell viability, metabolic activity, mitochondrial membrane potential, cell cycle, and cell death in cells treated with MW-irradiated biological solutions. As MW irradiation with power density ~ 12 kW/cm2 mainly induces reactive nitrogen oxygen species in deionized water, it altered the cell cycle, membrane potential, and cell death rates in U373MG cells due to its high electric field ~ 11 kV/cm in water. Interestingly, MW-irradiated cell culture medium and phosphate-buffered saline did not alter the cellular viability and metabolic energy of cancer and normal cells without affecting the expression of genes responsible for cell death. Taken together, MW-irradiated water can alter cellular physiology noticeably, whereas irradiated media and buffered saline solutions induce negligible or irrelevant changes that do not affect cellular health.

Impact of Community-Onset Methicillin-Resistant Staphylococcus aureus on Staphylococcus aureus Bacteremia in a Central Korea Veterans Health Service Hospital.

BACKGROUND: No study has examined the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in Korean veterans' hospitals. We investigated the microbiological and clinical epidemiology of S. aureus bacteremia at the central Veterans Health Services (VHS) hospital in Korea. METHODS: Patients with S. aureus bacteremia were consecutively enrolled from February to August 2015. Bacteremia was classified as hospital-acquired (HA), community-onset healthcare-associated (COHA), or community-acquired (CA). MRSA bacteremia risk factors were analyzed. Species identification, antimicrobial susceptibility, and presence of luk and tst were tested. Staphylococcal cassette chromosome mec (SCCmec) typing, spa sequence typing agr polymorphism typing, and multilocus sequence typing were performed. Biofilm production and δ-hemolysin activity were measured to determine agr function. RESULTS: In total, 60 patients were enrolled (30 HA, 23 COHA, and seven CA bacteremia); 44 (73.3%) had MRSA bacteremia (26 HA, 16 COHA, and two CA). MRSA bacteremia occurred more frequently in non-CA patients and those who had received antibiotic treatment within the past month (P<0.05). The major MRSA strains comprised 24 ST5-agr2-SCCmecII, 11 ST72-agr 1-SCCmecIV, and five ST8-agr1-SCCmecIV strains. Of 26 agr2-SCCmecII strains, including two MSSA strains, 25 were multidrug-resistant, 18 were tst-positive, and 13 were agr-defective, whereas only five of the 18 agr1-SCCmecIV strains were multidrug-resistant, and all were tst-negative and agr-intact. agr1-SCCmecIV and ST8-agr1-SCCmecIV strains were more likely than agr2-SCCmecII strains to be COHA. CONCLUSIONS: MRSA was highly prevalent in both COHA and HA bacteremia. The introduction of virulent CA-MRSA strains may be an important cause of increased HA-MRSA bacteremia in VHS hospitals.

Photodynamic therapy combined with intravitreal bevacizumab in a patient with choroidal neovascularization secondary to choroidal osteoma.

Choroidal osteoma is a benign ossified tumor that is found predominantly in healthy young women during their second and third decades of life. The lesions are white-to-cream or orange in color, are located in the peripapillary and macular areas, and are unilateral in most patients. The symptoms of choroidal osteoma include decreased visual acuity and metamorphopsia or scotoma corresponding to the location of the osteoma, but some patients have no symptoms. Prognosis of vision varies according to tumor location, retinal pigment epithelial and sensory retinal degeneration, subretinal fluid and hemorrhage, and development of a subretinal neovascular membrane.

Factors predisposing to consecutive esotropia after surgery to correct intermittent exotropia.

BACKGROUND: To investigate the incidence of and factors predisposing to consecutive esotropia after intermittent exotropia surgery, and to prevent the onset of consecutive esotropia. METHODS: We retrospectively surveyed 226 patients who had been followed up for more than 1 year after surgery for intermittent exotropia conducted between February 2005 and September 2010. Consecutive esotropia was defined as an esotropia of at least 10 prism diopters (PD) at distance or near at least once in 2 weeks after surgery. Presumed risk factors for consecutive esotropia were analyzed. Gender, age at surgery, average binocular spherical equivalent, anisometropia, high myopia, amblyopia, preoperative angle of deviation, vertical deviation, A-V pattern strabismus, exotropia type, type of surgery, stereopsis, and suppression were investigated to evaluate factors influencing the onset of consecutive esotropia. RESULTS: Consecutive esotropia occurred in 22 patients (9.7 %). Significant correlations with occurrence of the condition were found with high myopia (P = 0.013), amblyopia (P = 0.047), preoperative angle of deviation of 25-40 PD at distance (P = 0.016), deviation at distance - deviation at near > 10 PD (P = 0.041), lateral incomitance (P = 0.007), tenacious proximal convergence fusion type (P = 0.001), unilateral lateral rectus muscle recession and medial rectus muscle resection (P = 0.001). CONCLUSIONS: High myopia, amblyopia, and lateral incomitance were predisposing factors for consecutive esotropia. Furthermore, the preoperative angle of deviation at distance, differences between the angle of deviation at near and at distance, the type of intermittent exotropia, and the type of surgery affected the incidence of consecutive esotropia. More attention must be paid to patients with such factors.

Abducens nerve palsy complicated by inferior petrosal sinus septic thrombosis due to mastoiditis.

We present a very rare case of a 29-month-old boy with acute onset right abducens nerve palsy complicated by inferior petrosal sinus septic thrombosis due to mastoiditis without petrous apicitis. Four months after mastoidectomy, the patient fully recovered from an esotropia of 30 prism diopters and an abduction limitation (-4) in his right eye.

Drill and chop: modified vertical chop technique for hard cataract.

The authors describe a technique to improve the control and safety of vertical chopping during hard cataract surgery. Whereas the conventional vertical chop technique uses a sharp vertical chopper, the proposed technique uses a short blunt chopper. This requires complete engagement of the central nucleus by a phaco tip. The authors first drilled a hole into the endonucleus. By rotating the Kelman phaco tip clockwise, the nucleus was deeply impaled horizontally and firmly engaged with the phaco tip. This was followed by vertical chopping. This technique results in safer and more effective vertical chopping in patients with hard cataracts.